Content:
Presentation type:
CL – Climate: Past, Present & Future

Major efforts have been made in recent decades to decipher the climate of the past and its drivers with the help of proxy archives. Reconstructions of past climate variations are of immediate societal relevance because they serve as a baseline for anthropogenic climate change, and help us understand how past societies coped (or failed to cope) with extreme climate events. Good paleoclimatology, however, relies on ever more precise and accurate dates. While many proxy archives provide continuous year-by-year sequences going back many thousands of years, ambiguities in their interpretation introduce time uncertainty which increases over time. As a consequence, natural climate variability is underestimated when time-uncertain climate reconstructions are combined.

Through the use of "Miyake events" novel time markers that are accurate to the year, globally distributed and detectable in different climate archives it has recently become possible to better date and synchronize some of these climate archives, notably the polar ice-core records. The revised dating of ice cores from both Greenland and Antarctica combined with technological advances based on real-time continuous flow analysis techniques has shed new light on a prominent impact of volcanic eruptions on past climate and human societies. In this talk, I will highlight how we can date ancient eruptions, (sometimes to the season), geochemically identify their provenance and quantify their climate impact potential through emissions of sulfuric gases using large networks of ice cores. Case studies include prominent eruptions from Vesuvius or Santorini as well as eruptions largely unknown to the general public, for example from Alaska. I will discuss linkages to precisely dated proxies (e.g. tree-rings) and documentary records to demonstrate the accuracy of the new ice-core chronologies and to delineate climatic and societal responses to external shocks caused by major volcanic eruptions. In my concluding remarks, I will show how such lessons from the past can help to improve our understanding of past natural climate variability and to quantify global risks arising from volcanic activity in the future.

How to cite: Sigl, M.: A slice through time — securing timelines of past climate, global volcanism and human societies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8168, https://doi.org/10.5194/egusphere-egu24-8168, 2024.

EGU24-3722 | Orals | CL1.2.5 | Milutin Milankovic Medal Lecture by Peter U. Clark

A Revisionist View of the Mid-Pleistocene Transition 

Peter U. Clark, Jeremy Shakun, Yair Rosenthal, David Pollard, Peter Köhler, Steven Hostetler, Patrick Bartlein, Zhengyu Liu, Chenyu Zhu, Daniel Schrag, and Nicklas Pisias

The Mid-Pleistocene Transition (MPT) is commonly characterized as a change in both temperature and ice volume from smaller amplitude, 41-kyr variability to higher amplitude, ~100-kyr variability in the absence of any significant change in orbital forcing. Here we reassess these characteristics based on our new reconstructions of changes in global mean surface temperature (DGMST) and global mean sea level over the last 2.5 Myr. Our reconstruction of DGMST includes an initial phase of long-term cooling through the early Pleistocene followed by a second phase of accelerated cooling during the MPT (1.5-0.9 Ma) that was accompanied by a transition from dominant 41-kyr low-amplitude periodicity to dominant ~100-kyr high-amplitude periodicity. Changes in rates of long-term cooling and variability are consistent with changes in the carbon cycle driven initially by geologic processes followed by additional changes during the MPT in the Southern Ocean carbon cycle. The spectrum of our sea-level reconstruction is dominated by 41-kyr variance until ~1.2 Ma with subsequent emergence of a ~100-kyr signal that, unlike global temperature, has nearly the same concentration of variance as the 41-kyr signal during this time. Moreover, our sea-level reconstruction is significantly different than all other reconstructions in showing fluctuations of large ice sheets throughout the Pleistocene as compared to a change from fluctuations in smaller to larger ice sheets during the MPT. We attribute their longer period variations after the MPT to modulation of obliquity forcing by the newly established low-frequency CO2 variability. Specifically, prior to reaching their maximum size at the end of each ~100-kyr interval, ice-sheet response to periods of lower CO2 was modulated by higher obliquity, and vice versa, with the times of maximum ice-sheet growth only occurring when low CO2 combined with the next obliquity low. Ice sheets then began to melt in response to the next increase in obliquity, with the subsequent sequence of events and feedbacks leading to a termination. High-resolution ice-core CO2 records that extend beyond 0.8 Ma are needed to test this hypothesis. Otherwise, large ice sheets shared a common size threshold throughout the Pleistocene equivalent to sea level below -80 m that, when exceeded, resulted in a termination that was paced by the next increase in obliquity.

How to cite: Clark, P. U., Shakun, J., Rosenthal, Y., Pollard, D., Köhler, P., Hostetler, S., Bartlein, P., Liu, Z., Zhu, C., Schrag, D., and Pisias, N.: A Revisionist View of the Mid-Pleistocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3722, https://doi.org/10.5194/egusphere-egu24-3722, 2024.

EGU24-12777 | Orals | CL2.1 | Highlight | CL Division Outstanding ECS Award Lecture

The pattern effect: How radiative feedbacks depend on surface warming patterns and influence near-term projections  

Maria Rugenstein

Recent research has highlighted that radiative feedbacks — and thus climate sensitivity — are not constant in time but depend sensitively on sea surface temperature patterns. I will discuss three implications of this realization.

First, I will show how coupled climate models fail to reproduce observed surface warming patterns and global mean top of the atmosphere (TOA) radiation trends. I use large initial condition ensembles to compare observations to account for internal variability and model mean-state biases. For certain periods, not a single ensemble member can reproduce observed values of surface temperature trends and TOA radiation trends. Models which more greatly underestimate the observed local sensitivity of surface and TOA, and models with a weak variability in the Equatorial Pacific surface temperatures tend to have a higher equilibrium climate sensitivity. Despite these astonishing observation-model discrepancies their global-mean temperatures are simulated well which points to a common model problem in surface heat fluxes and ocean heat uptake.

Second, I will discuss the relevance of the pattern effect for climate change projections. Given that problems coupled models have in reproducing observed warming patterns, we should doubt their pattern evolution in projections. I will introduce “surface warming pattern storylines” starting from the observations and bridging to simulated future patterns in standard scenarios. I show that (CMIP) coupled climate models used ubiquitously for climate change projections underestimate the uncertainty of possible global-mean temperature evolutions due to their surface warming patterns throughout the 21st century.

Third, I will introduce how a feed-forward convolutional neural network (CNN) can be trained to learn the pattern effect and predict global-mean TOA radiation from surface warming patterns. I use explainable artificial intelligence methods to visualize and quantify that the CNN draws its predictive skill for physically meaningful reasons. Remarkably and different from traditional approaches, I can predict radiation under strong climate change from training the CNN on internal variability alone. This out-of-sample application works only when feedbacks are allowed to be non-linear or equivalent, changing in time, which is another, independent manifestation of the relevance of the pattern effect.

How to cite: Rugenstein, M.: The pattern effect: How radiative feedbacks depend on surface warming patterns and influence near-term projections , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12777, https://doi.org/10.5194/egusphere-egu24-12777, 2024.

CL0.1 – Inter- and Transdisciplinary Sessions

 

Weather Compound Events (WCE), broadly defined as “the combination of multiple drivers and/or hazards that contributes to societal or environmental risk” [1], contribute to important societal impacts and widespread economical damages. However, the underlying mechanisms and complete storylines of these events are complex and not well understood yet.

In this study, we build an 25-year database of co-occurrent hot and dry compound events (HDCE) including heatwaves, droughts, dust storms and wildfires affecting Europe and the Mediterranean Basin from 2003 to 2020. based on Earth Observation exclusively. Individual natural hazards were systematically identified by a spatial and temporal matching algorithm applied on consistent ESA CCI Earth Observation datasets. The resulting individual natural hazard masks were then overlayed over Europe and permitted to identify regions simultaneously affected by two or more natural hazards on a daily basis. The climatology revealed HDCE hotspots among others in Northern Italy, Balkans and Caucasus regions.

Characteristics of HDCE such as their duration, intensity and spatial extension are stored in the database. HDCE could also be associated with a severity index to aid comparison across events.

Long-term statistics of the generated HDCE have shown a high interannual variability with HDCE being more frequent during the 5 last years rather than two decades ago.

The large-scale preconditions preceding and occurring during HDCE are investigated as well in this study and revealed systematic patterns in the atmospheric dynamics.

 

[1] Zscheischler, J., Martius, O., Westra, S., Bevacqua, E., Raymond, C., Horton, R.M., van den Hurk, B., AghaKouchak, A., Jézéquel, A., Mahecha, M.D. and Maraun, D., 2020. A typology of compound weather and climate events. Nature reviews earth & environment1(7), pp.333-347.

How to cite: Fluck, E.: A 25-year assessment of Hot and Dry Weather Compound Events in Europe using Earth Observation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-109, https://doi.org/10.5194/egusphere-egu24-109, 2024.

EGU24-134 | ECS | Orals | ITS2.3/CL0.1.1 | Highlight

Revealing the role of long-term drought in the record-shattering April 2023 heatwave in the Western Mediterranean 

Marc Lemus-Canovas, Damian Insua-Costa, Ricardo M. Trigo, and Diego G. Miralles

In April 2023, the Western Mediterranean region was hit by an exceptional and unprecedented heatwave that broke several temperature records. In Cordoba (Spain), the previous April maximum temperature record was exceeded by almost 5ºC. In this study, we investigated the interaction between soil moisture and the extreme temperatures reached during this event, using the latest available observational data and several statistical techniques capable of quantifying this relationship. Our results revealed that soil moisture deficit preconditions, concurring with a strong subtropical ridge as a synoptic driver, had a key contribution to the amplification of this record-breaking heatwave. Specifically, we estimated that the most extreme temperature records would have been 4.53 times less likely and 2.19°C lower if the soils had been wet. These findings indicated that soil moisture content may be a crucial variable for seasonal forecasting of early HW in this region and other Mediterranean climate regimes that already suffering an increment in the frequency of compound drought–heatwave events. 

How to cite: Lemus-Canovas, M., Insua-Costa, D., Trigo, R. M., and Miralles, D. G.: Revealing the role of long-term drought in the record-shattering April 2023 heatwave in the Western Mediterranean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-134, https://doi.org/10.5194/egusphere-egu24-134, 2024.

Attribution of compound events informs preparedness for emerging hazards. However, the task remains challenging because of complex space-time interactions amongst extremes, climate models’ deficiency in reproducing dynamics of various scales, and uncertainties in dynamic aspects of climate change. 
During June-July 2020, a historic flood hit the Yangtze River Valley and to its south the hottest summer since 1961 was observed, leading to disproportionate socioeconomic and environmental impacts to southern China. For attributing the recording-breaking spatially compounding event, we conduct a storyline attribution analysis by designing a series of simulation experiments via a weather forecast model, with large-scale dynamics equally constrained and thermodynamics of the climate system modified. We report that given the large-scale dynamic setup, anthropogenic influence has exacerbated the 2020 extreme Mei-yu rainfall by ~6.5% and warmed the southern co-occurring seasonal heat by ~1℃. The framework further details human influence on key elements to the two extremes individually and their coupling in space. If the same compound event unfolds in the 2090s, it is plausible to expect the monsoonal rainfall extremes ~14% wetter and the accompanying South China heat ~2.1°C warmer than observed.
This method opens an avenue for attribution of low-likelihood, dynamically-driven, spatially and temporally compounding events.

How to cite: Chen, Y.: Storyline attribution and projection of the 2020 spatially compounding flood-heat event in southern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-185, https://doi.org/10.5194/egusphere-egu24-185, 2024.

Extreme droughts and pluvials are recurrent natural hazards that often lead to disastrous socio-economic impacts. These hydroclimatic extremes are generally characterized by large-scale spatial-temporal patterns spanning thousands of kilometres with time-evolving features of expansion or shrinkage. The spatial-temporal dynamics of these hydroclimatic extremes can pose compound impacts across multiple locations. Understanding the propagation behaviour, including movement and propagation, is crucial for disaster response and mitigation. The spatial propagation dynamics of droughts/pluvials are inherently complex as they are often associated with and modulated by natural climate variability, such as El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and atmospheric dynamics like Rossby waves. However, the specific influences of these drivers on the spatial propagation pathways of droughts and pluvials remain elusive. Here, we conduct a multi-layer complex network-based analysis to explore the interactions between drought/pluvial propagation pathways and potential modulating mechanisms with a focus on the conterminous United States. We first identify extreme drought and pluvial occurrences using self-calibrated Palmer Drought Severity Index (scPDSI) and Standardized Precipitation Index (SPI) during 1948–2016. We then apply event coincidence analysis (ECA) for all location pairs to construct fully-connected drought and pluvial complex networks, based on which we identify the spatial-temporal propagation pathways through community analysis. Subsequently, partial event coincidence analysis is carried out to elucidate the direct links from potential climate modulators (e.g., ENSO, NAO, and Rossby waves) to extreme event propagation. Our results provide insights into how climate variability and large-scale circulation patterns affect the spatial propagation of droughts and pluvials, offering valuable information for pre-emptive actions to mitigate remotely synchronized extreme events.

How to cite: Wang, H.-M. and He, X.: Lagged Synchronizations of Hydroclimatic Extremes and Their Propagation Dynamics Revealed by Complex Event Coincidence Networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-842, https://doi.org/10.5194/egusphere-egu24-842, 2024.

EGU24-955 | ECS | Posters on site | ITS2.3/CL0.1.1 | Highlight

A European Perspective on Joint Probabilities of Multi-Hazards 

Judith Claassen, Philip Ward, Wiebke Jäger, Elco Koks, and Marleen de Ruiter

Natural hazards rarely occur in isolation. Frequently, one hazard triggers another, such as an earthquake triggering a tsunami. Likewise, the likelihood of a hazardous event can be amplified by the occurrence of a previous event, such as a drought amplifying the likelihood of a wildfire to occur. However, two extremes can also co-occur as a compound event, leading to even higher combined impacts.

While the field of compound events is advancing rapidly, studies often focus solely on climatic extremes occurring at the same time, excluding non-climate-related hazards or previous triggering and amplifying conditions. Therefore, this research aims to better understand the dependencies between different (pre-conditioning) hazard magnitudes, geographic features, and historic natural hazard footprints accounting for both climatic and geological hazards.

With the use of statistical tools, such as vine copulas, we model the relationships within two different hazard groups. The first group consists of drought, heatwave, and fuel indicators to calculate the risk of wildfires. The second group includes earthquakes, precipitation, and slope data to calculate the risk of landslides. While the first group is considered a compound event, the second group can be classified as a multi-hazard, with different triggering or amplifying relationships. For both groups, we attempt to use the same method to model stochastic events that include a potential hazard footprint for wildfires and landslides on a local to European scale. This model allows users to evaluate potential hazard combinations and footprints in their regions, enabling better preparedness for potential multi-hazard events.

How to cite: Claassen, J., Ward, P., Jäger, W., Koks, E., and de Ruiter, M.: A European Perspective on Joint Probabilities of Multi-Hazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-955, https://doi.org/10.5194/egusphere-egu24-955, 2024.

The emergency of global‐scale hydroclimatic extremes (i.e., meteorological droughts, extreme precipitations, heat waves and cold surges) and associated compound events has recently drawn much attention. A global‐scale unified and comprehensive event set with accurate information on spatiotemporal evolutions is necessary for better mechanism understanding and reliable predictions in sequential studies. Accordingly, this manuscript describes the first‐generation global event‐based database of hydroclimatic extremes produced with the newly proposed 3D (longitude–latitude–time) DBSCAN‐based workflow of event detection. The short name of this database is Glo3DHydroClimEventSet(v1.0) , which is obtained from the FigsharePlus webpage ( https://doi.org/10.25452/figshare.plus.23564517 ). The 1951–2022 ERA5‐based multiscale and multi‐threshold daily running datasets of precipitation and near‐surface air temperature are calculated and employed as the input data. A comprehensive event set of hydroclimate extremes is the output of the 3D DBSCAN‐based workflow. From perspectives of spatiotemporal evolutions, this event‐based database is also measured and attached with metric information. For case‐based validation, some recently reported hydroclimatic extremes (e.g., the 2020 summertime flood‐inducing Yangtze River extreme precipitation event) are employed and accurately detected in the Glo3DHydroClimEventSet(v1.0) database. Meanwhile, global‐scale spatiotemporal distributions are preliminarily analysed. For example, global‐scale event counts of extreme heatwaves displayed an increasing tendency since 2005, with a rapid increase after 2010. To sum up, this Glo3DHydroClimEventSet(v1.0) database may facilitate new scientific achievements concerning event‐based hydroclimatic extremes, especially in communities of atmosphere, hydrology, natural hazards and associated socioeconomics. The DOI-based linkage is  https://doi.org/10.1002/joc.8289 .

How to cite: Liu, Z. and Zhou, W.: Glo3DHydroClimEventSet(v1.0) : A global‐scale event set of hydroclimatic extremes detected with the 3D DBSCAN ‐based workflow (1951–2022), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2346, https://doi.org/10.5194/egusphere-egu24-2346, 2024.

This study investigates the coupled variability of temperature and precipitation in eastern China during summer using empirical orthogonal function (EOF) analysis to better understand and mitigate simultaneous occurrences of extreme events,such as compound droughts and heat waves. Two dominant modes are identified: the first exhibits a strong warming and drying trend in the region north of the Yangtze River, with the opposite occurring in the south; the second illustrates decadal oscillations in temperature and precipitation, alternating between cool-wet conditions and warm-dry conditions in southern China. The underlying mechanisms for these leading modes are revealed through correlation, composite analysis,and model simulations. The first mode is associated with a negative Pacific-Japan teleconnection in the lower atmosphere and a stationary Rossby wave train across Eurasia in the upper troposphere, which are influenced by global warming and sea surface temperature anomalies in the western North Atlantic. The second mode is linked to alternating active periods of the North Atlantic Oscillation (NAO) and Pacific Decadal Oscillation (PDO). The NAO exerts a significant influence on the summer climate in eastern China during its active phases, while the PDO shows an opposite effect when the NAO is less active. These findings provide valuable implications for long-term planning and adaptation strategies to better cope with compound extreme events in eastern China.

How to cite: Zhang, Y. and Zhou, W.: Long-term coupled variability of temperature and precipitationin eastern China and the underlying mechanisms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2743, https://doi.org/10.5194/egusphere-egu24-2743, 2024.

EGU24-2962 | Orals | ITS2.3/CL0.1.1 | Highlight

Intensification and Poleward Shift of Compound Wind and Precipitation Extremes in a Warmer Climate 

Delei Li, Jakob Zscheischler, Yang Chen, Baoshu Yin, Jianlong Feng, Mandy Freund, Jifeng Qi, Yuchao Zhu, and Emanuele Bevacqua

Compound wind and precipitation extremes (CWPEs) can severely impact natural and socioeconomic systems. However, our understanding of CWPE future changes, drivers, and uncertainties under a warmer climate is limited. Here, analyzing the event both on oceans and landmasses via state-of-the-art climate model simulations, we reveal a poleward shift of CWPE occurrences by the late 21st century, with notable increases at latitudes exceeding 50° in both hemispheres and decreases in the subtropics around 25°. CWPE intensification occurs across approximately 90% of global landmasses, especially under a high-emission scenario. Most changes in CWPE frequency and intensity (about 70% and 80%, respectively) stem from changes in precipitation extremes. We further identify large uncertainties in CWPE changes, which can be understood at the regional level by considering climate model differences in trends of CWPE drivers. These results provide insights into understanding CWPE changes under a warmer climate, aiding robust regional adaptation strategy development.

How to cite: Li, D., Zscheischler, J., Chen, Y., Yin, B., Feng, J., Freund, M., Qi, J., Zhu, Y., and Bevacqua, E.: Intensification and Poleward Shift of Compound Wind and Precipitation Extremes in a Warmer Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2962, https://doi.org/10.5194/egusphere-egu24-2962, 2024.

EGU24-3151 | Orals | ITS2.3/CL0.1.1

Usable Compound Event Research 

Kai Kornhuber

High impact events are often compound events with relevance for a wide range of societal sectors: Infrastructure and Urban Resilience, Agricultural Adaptation and Food Security, Public Health and Healthcare Preparedness, Insurance and Financial Risk Management, Energy Systems, Natural Systems, Globally interconnected Networks: Food Networks, Supply chains, transport systems.

 Consequently, compound events and associated physical risks have been prominently acknowledged in recent high-level reports such as the sixth assessment report of the IPCC, fifth US National Climate Assessment, numerous UNDRR briefing notes and the Risk report of the world economic forum among others.

Driven by the need to enhance our physical and statistical understanding of high impact climate events, compound event research has made substantial progress and has emerged as a new inter/trans/multi-disciplinary field of study over the past decade, bridging climate, environmental science as well as statistics and data science. To be fully usable for solving real world problems substantial challenges remain, these include lack of high-resolution data, model biases in tail risks, and impact relevant event definition. This talk will provide an overview of current challenges in accurately projecting and predicting risks from compound events for various societal sectors and points towards potential solutions to address these.

How to cite: Kornhuber, K.: Usable Compound Event Research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3151, https://doi.org/10.5194/egusphere-egu24-3151, 2024.

EGU24-3395 | Posters on site | ITS2.3/CL0.1.1

Global Warming Determines Future Increase in Compound Dry and Hot Days within Wheat Growing Seasons Worldwide 

Yan He, Yanxia Zhao, Yihong Duan, Xiaokang Hu, and Peijun Shi

Compound dry and hot extremes are proved to be the most damaging climatic stressor to wheat thereby with grave implications for food security, thus it is critical to systematically reveal their changes under unabated global warming. This study provides a comprehensive analysis of the changes in compound dry and hot days (CDHD) occurring within dynamic wheat growing seasons of 2015-2100 over dynamic wheat planting regions worldwide under SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5, including CDHD’s frequency and severity. This study sought to fill the gap in knowledge by identifying the CDHD occurring within dynamic wheat growing seasons, clarifying the correlations between droughts and heats as well as their impacts on CDHD, and revealing the driven mechanism of global warming for the increase of CDHD.

Our results demonstrate a notable increase in CDHD’s frequency and severity worldwide under all SSPs, such increase is sharper over southern Asia in winter wheat growing season, and southern Canada, northern America, Ukraine, Turkey and northern Kazakhstan in spring wheat growing season. As the top 10 wheat producer, India and America will suffer much more detrimental CDHD in their wheat growing season. Adopting a low forcing pathway will mitigate CDHD risks in up to 93.3% of wheat areas. Positive dependence between droughts and heats in wheat growing season is found over more than 74.2% of wheat areas, which will effectively promote the frequency and severity of CDHD. Global warming will dominate the increase of CDHD directly by increasing hot days and indirectly by enhancing potential evapotranspiration thereby aggravating droughts. This study helps to optimize adaptation strategies for mitigating CDHD risks on wheat production, and provides new insights and analysis paradigm for investigating future variations in compound extremes occurring within dynamic crops growing seasons.

How to cite: He, Y., Zhao, Y., Duan, Y., Hu, X., and Shi, P.: Global Warming Determines Future Increase in Compound Dry and Hot Days within Wheat Growing Seasons Worldwide, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3395, https://doi.org/10.5194/egusphere-egu24-3395, 2024.

EGU24-3689 | ECS | Posters on site | ITS2.3/CL0.1.1

Abrupt transitions between drought and pluvial events becoming more widespread and intense 

Yuheng Yang, Xixi Lu, and Xue Xiao

Droughts and floods, as individual hazards, pose significant challenges, but their consecutive occurrence can trigger catastrophic cascades of disasters. Therefore, it is crucial to understand these extreme events, known as drought-pluvial (DPAT) and pluvial-drought abrupt transitions (PDAT), to mitigate their risks and potential impacts effectively. Our study utilizes historical records spanning from 1940 to 2022 to identify DPAT and PDAT events, investigating their frequencies, durations, intensities, and underlying causes. Additionally, we analyzed the frequency, duration, and intensity of these events under projected future scenarios. Globally, there has been an increasing trend in the frequency of DPAT and PDAT events, with significant upticks observed in Eastern North America, South Asia, East Asia, the Middle East, Africa, and Australia. In the 2010s, these disasters impacted over 100 million people, predominantly in less economically developed countries. Our findings enhance the current understanding of DPAT and PDAT, thereby contributing to the development of more effective mitigation and adaptation strategies against their impacts.

How to cite: Yang, Y., Lu, X., and Xiao, X.: Abrupt transitions between drought and pluvial events becoming more widespread and intense, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3689, https://doi.org/10.5194/egusphere-egu24-3689, 2024.

EGU24-4229 | Orals | ITS2.3/CL0.1.1 | Highlight

Human influences on spatially compounding flooding and heatwave events in China and future increasing risks 

Cheng Qian, Yangbo Ye, Emanuele Bevacqua, and Jakob Zscheischler

Attribution of high-impact weather events to anthropogenic climate change is important for disentangling long-term trends from natural variability and estimating potential future impacts. Up to this point, most attribution studies have focused on univariate drivers, despite the fact that many impacts are related to multiple compounding weather and climate drivers. For instance, co-occurring climate extremes in neighbouring regions can lead to very large combined impacts. Yet, attribution of spatially compounding events with different hazards poses a great challenge. Here, we present a comprehensive framework for compound event attribution to disentangle the effects of natural variability and anthropogenic climate change on the event. Taking the 2020 spatially compounding heavy precipitation and heatwave event in China as a showcase, we find that the respective dynamic and thermodynamic contributions to the intensity of this event are 51% (35–67%) and 39% (18–59%), and anthropogenic climate change has increased the occurrence probability of similar events at least 10-fold. We estimate that compared to the current climate, such events will become 10 times and 14 times more likely until the middle and end of the 21st century, respectively, under a high-emissions scenario. This increase in likelihood can be substantially reduced (to seven times more likely) under a low-emissions scenario. Our study demonstrates the effect of anthropogenic climate change on high-impact compound extreme events and highlights the urgent need to reduce greenhouse gas emissions.

How to cite: Qian, C., Ye, Y., Bevacqua, E., and Zscheischler, J.: Human influences on spatially compounding flooding and heatwave events in China and future increasing risks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4229, https://doi.org/10.5194/egusphere-egu24-4229, 2024.

EGU24-4582 | Orals | ITS2.3/CL0.1.1

Increasing occurrence of sudden turns from drought to flood over China 

Hao Wang, Shanshan Wang, Xinya Shu, Yongli He, and Jianping Huang

This study focuses on a new compounding concern, the sudden turn from drought to flood (STDF), that is becoming increasingly prominent. Droughts usually end due to increased precipitation, but if excessive rainfall occurs, it can lead to secondary impacts on already barren land, increasing the likelihood of landslides and making farmland flooding significantly costlier than it would have been if only flooding had occurred. Therefore, we must pay more attention to compound disasters that increase the vulnerability of populations and ecosystems. Most studies on rapid drought-to-flood transitions have analyzed individual cases, whereas few have studied the STDF characteristics in China or even globally or the long-term changes in the STDF trend. In this study, we selected an STDF screening method that is accurate on a daily scale.

In this study we calculated the SPEI on a 1-month scale, sliding a 30-day window in order to obtain the SPEI values for each day. Second, we used a relative threshold rather than an absolute threshold to define a flood in consideration of regional precipitation differences. A definition of STDF as follows:

,where to is the drought start time, td is the drought end time, and tp is the time when flooding starts. Here, a drought is said to have occurred when the SPEI ≤-0.5 for more than 40 consecutive days. Our reference method considers drought duration to be more than 20 days, which is based on the persistence of the drought. And the main reason for our choice of 40 days is mainly to exclude the effect of flash droughts, although that type of event proved not to have a significant impact on our results in the subsequent discussion. PREt represents the t-d precipitation (for example, t=3, PRE3 is the 3d cumulative precipitation), when PREt is greater than the 99.5th (for PRE3)/99.3th (for PRE5)/98.7th (for PRE10) percentile precipitation for each reference period (1961-2020) as the flood threshold. (Based on the natural disasters released by the Emergency Management Department and the China’s Yearbook of Meteorological Disasters , 234 floods events were obtained for the period of 2010-2020, and so a threshold of 99.5th, 99.3th, and 98.7th percentile (corresponding to 3d/5d/10d continuous precipitation) was determined for their ranking in the rainfall series from 1961 to 2020.)

The results show that STDFs have been increasing more frequently in China at a rate of average 2.8 events per decade. The most significant increases occurred in May and June, resulting in an advance of one month for the STDF peak. The STDF hotspots are concentrated in north and northeast China and YRD. Nearly 35% of droughts in northern and northeast China have been immediately followed by a flood rather than a gradual drought mitigation or a drought alone. STDFs have become more prevalent in northern China as a result of increased flood frequency and precipitation volatility, while in southern China, the increase in STDF frequency is primarily due to an increase in drought frequency.

How to cite: Wang, H., Wang, S., Shu, X., He, Y., and Huang, J.: Increasing occurrence of sudden turns from drought to flood over China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4582, https://doi.org/10.5194/egusphere-egu24-4582, 2024.

In the context of global climate change, extreme climate events are becoming increasingly frequent.  Extreme climate events constitute major risks to global food security. The simultaneous occurrence of multiple extreme climate events may have a much greater impact than individual extreme events in isolation. Here we quantitatively analyzed the impact of individual and combined extreme climate indices, including cold days (CD), warm degree days (WDD), precipitation, and compound hot – windy - dry (HWD), on the yields of three major crops (winter wheat, soybeans, and maize) globally by establishing a linear mixed-effects model. CD, HWD, and WDD are identified as the most significant driving factors causing yield losses in winter wheat, soybeans, and maize, respectively. During the planting to the jointing stage, per 10 days of CD account for a 3.2% reduction in winter wheat yield. During the jointing to heading stage, per 10 h of HWD and per 10 °C day-1 WDD result in a 7.5% reduction in soybean yield and a 2.7% reduction in maize yield, respectively. We quantified "yield shocks" and found that the regions experiencing yield shocks exhibit a similar spatial distribution to extreme climate indices. These extreme climate indices are likely to be the driving factors behind yield shocks for the three crops. Our findings indicate that multiple individual extreme climate factors, as well as compound heat-drought-wind (HDW) indices that have been overlooked in traditional risk assessments, impact the yield of the three major crops globally.

How to cite: kun, X. and Xin, Q. C. X.: Investigate the Effects of Compound Extreme Climate Events on Global  crop Yield from 1982 to 2016, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4843, https://doi.org/10.5194/egusphere-egu24-4843, 2024.

EGU24-5030 | ECS | Orals | ITS2.3/CL0.1.1 | Highlight

Projecting Changes in the Drivers of Compound Flooding in Europe Using CMIP6 Models 

Tim Hermans, Julius Busecke, Thomas Wahl, Víctor Malagón-Santos, Michael Tadesse, Robert Jane, and Roderik van de Wal

When different flooding drivers co-occur, they can cause compound floods. Despite the potential impact of compound flooding, few studies have projected how the joint probability of flooding drivers may change. Furthermore, existing projections are based on only 5 to 6 climate model simulations because flooding drivers such as storm surges and river run-off need to be simulated offline using computationally expensive hydrodynamic and hydrological models. Here, we use a large ensemble of simulations from the Coupled Model Intercomparison Project 6 to project changes in the joint probability of extreme storm surges and precipitation in Europe under a medium and high emissions scenario. To compute storm surges for so many simulations, we apply a statistical storm surge model trained with tide gauge observations and atmospheric forcing from the ERA5 reanalysis. We find that the joint probability of extreme storm surges and precipitation will increase in the northwest and decrease in most of the southwest of Europe. On average, the absolute magnitude of these changes is 36% to 49% by 2080, depending on the scenario. We show that due to internal climate variability and inter-model differences, projections based on small climate model ensembles can differ qualitatively depending on the specific simulations included. Therefore, our results provide a more robust and less uncertain representation of changes in the potential for compound flooding in Europe than previous projections.

How to cite: Hermans, T., Busecke, J., Wahl, T., Malagón-Santos, V., Tadesse, M., Jane, R., and van de Wal, R.: Projecting Changes in the Drivers of Compound Flooding in Europe Using CMIP6 Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5030, https://doi.org/10.5194/egusphere-egu24-5030, 2024.

EGU24-5210 | ECS | Orals | ITS2.3/CL0.1.1

Compounding preconditions leading to wildfires differ across European climate regions 

Julia Miller, Michaela Macakova, Danielle Touma, and Manuela Brunner

Recent wildfire seasons broke records in terms of severity and damage in different regions of the world, e.g. in California in 2021 and in Southern Europe in 2022. The  probability of such severe and large wildfires is enhanced by compounding meteorological conditions of hot, dry and windy weather, which lead to dry fuels supporting the spread of fires. Drivers of low-frequency but high-impact fire events operate on different spatio-temporal scales and are difficult to identify with classical regression methods. Here, we use causal inference methods to describe the relationships between different variables driving fires and quantify their effect on the occurrence of fire events. We examine hydro-meteorological and land-surface drivers of wildfires in different European climate regions by leveraging ESAs’ FireCCI burnt area product together with CERRA reanalysis data from 2002 to 2022. Our results show region-specific patterns of the different variables prior to the wildfire events, which allow us to identify different wildfire pre-condition types. Highlighting the spatial variability of different wildfire drivers in various climate regions of Europe provides valuable insights for the development of targeted fire prevention measures and management. 

How to cite: Miller, J., Macakova, M., Touma, D., and Brunner, M.: Compounding preconditions leading to wildfires differ across European climate regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5210, https://doi.org/10.5194/egusphere-egu24-5210, 2024.

Hot extremes impose severe effects on human health and the ecosystem, especially when high-temperature extremes sequentially occur in both daytime and nighttime within 1 day, known as Compound Hot Extremes (CHEs). Although a number of studies have focused on independent hot extremes, not enough work is devoted to compound ones, not to mention the coupling strength in covariations between the two variables (daytime and nighttime temperature: Tmax and Tmin) over a given region. The instantaneous coupling strength can be derived by Dynamical System (DS) approach from covariations between Tmax and Tmin over a given region, and used to classify CHEs into coupled and decoupled types. Results show that coupled CHEs tend to be more intense with prolonged duration and extensive spatial extent compared with decoupled CHEs. Also, the mechanisms behind these two types of CHEs are largely different. Coupled CHEs are accompanied by a significant intensification and westward extension of the western North Pacific subtropical high (WNPSH), and the extremely high-temperature is mainly caused by receiving more solar radiation under the corresponding anticyclone. It is found that barotropic structure, weak jet stream and developing La Niña are conducive to the enhancement and persistence of WNPSH, in favor of the occurrence of long-lasting CHEs. Decoupled CHEs are associated with strong sea-land breeze (SLB), whose diurnal cycle could weaken the persistent large-scale circulation and suppress covariations between Tmax and Tmin. This kind of decoupled hot extremes are attributed to the combined effect of receiving more solar radiation during the day and trapping more long-wave radiation at night, where moisture and cloud cover play an important role.

How to cite: Guo, Y. and Fu, Z.: Regional coupled and decoupled day-night compound hot extremes over the mid-lower reaches of the Yangtze River: characteristics and mechanisms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5420, https://doi.org/10.5194/egusphere-egu24-5420, 2024.

EGU24-5617 | ECS | Posters on site | ITS2.3/CL0.1.1

Preconditioned biosphere flux extremes in terrestrial carbon cycle models and reanalyses in the recent past, present, and future 

Björn Riebandt, Moritz Adam, Elisa Ziegler, and Kira Rehfeld

The increasing frequency and severity of climate extremes pose a multifaceted threat to health, economic stability, and both natural and human-made environments. Potential overlap and accumulation of extremes as compound extremes poses further challenges. Ongoing climate change intensifies these challenges, underscoring the importance of a better understanding of the causes and drivers for compound events. Earth system model projections suggest that more frequent climatic compound extremes affect terrestrial biosphere fluxes, potentially reducing the land’s CO2 storage potential. However, whether models are able to represent such interactions like the priming of the biosphere towards extremes accurately remains to be shown.

Here, we focus on the role of concurrent precipitation and temperature as drivers of biosphere flux extremes and investigate their change in frequency and intensity based on their occurrence in historical simulations, reanalyses, and future projections. We use thresholds to define concurrent extremes and Monte Carlo randomization to constrain uncertainties. Further, we examine the association of climatic compound events with anomalies in biosphere carbon fluxes to ascertain their mutual relation, aiming to establish how these climatic compound events contribute to preconditioning extremes in the biosphere. Given this assessment of the occurrence change of climatic compound events and their connection to extremes in biosphere carbon fluxes, we infer how climatic compound events may precondition the biosphere for extremes. Lagged overlaps show significant seasonality and spatial heterogeneity in preconditioning. Comparing reanalyses and historical simulations in a model of the terrestrial carbon cycle and a comprehensive Earth System Model, we examine how well primed biosphere extremes agree in different data sources. Leveraging these findings, we evaluate if model projections show signs of stronger climatic priming of the biosphere in the next century.

How to cite: Riebandt, B., Adam, M., Ziegler, E., and Rehfeld, K.: Preconditioned biosphere flux extremes in terrestrial carbon cycle models and reanalyses in the recent past, present, and future, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5617, https://doi.org/10.5194/egusphere-egu24-5617, 2024.

EGU24-5986 | Orals | ITS2.3/CL0.1.1

Compound events increase the ground-level tropospheric ozone concentrations worldwide. 

Pedro Jimenez-Guerrero, Ivana Cvijanovic, Xavier Rodó, and Patricia Tarín-Carrasco

Compound extreme weather events (CE), characterized by the concurrent influence of multiple weather and climate drivers, have the potential to exacerbate the concentration of air pollution on the atmosphere. Attributing specific extreme weather events directly to climate change is challenging; however, it is widely acknowledged that climate change will intensify different extreme events by changing their frequency, intensity, spatial extent, duration, and timing. Several types of weather extremes, such as stagnation conditions and heatwaves (HW), can lead to hazardous air quality situations by allowing some pollutants, such as ozone (O3), to accumulate and persist in the near-surface environment. O3 is in general more pronounced in the summer due to the photochemical nature of the source. Given its highly heterogeneous distribution across both space and time, combined with a relatively short life-time, it becomes imperative to gain insights into the patterns governing the global spatial data distribution related to this complex phenomenon. This study aims to evaluate the amplifying effects of CE (concurrence of stagnation and heatwaves) on O3 peak levels globally during the summer season.

The study utilizes the simulations of historical 1980-2009) and future (2050-2079) climate under the Shared Socio-economic Pathways (SSP) SSP2-4.5 and SSP5-8.5. Using a model from the Coupled Model Intercomparison Project Phase 6 (CMIP6), the investigation explores the global temporo-spatial trends and disparities in compound-event occurrences across countries.

We find that O3 concentrations during the summer are higher in the center of North America and the center of the Asian continent compare with the other parts in the world (surpassing the 85 pbb during summer). A significant disparity in ozone concentrations was observed between the SSP2-4.5 and SSP5-8.5 scenarios. The SSP5-8.5 scenario demonstrates notably higher concentrations of peak O3 compared to the historical period, with increase of up to 20 ppb in certain regions, such as the Asian continent. Furthermore, it is noteworthy that O3 concentrations are expected to decrease in the future in the central part of North America in both scenarios up to 15 ppb during the summer season.

Focusing on CE throughout the summer season and under all scenarios studied, elevated O3 concentrations are observed worldwide during CE compared to non-event conditions, particularly during heatwaves, with an increase of 40, 35 and 40 ppb during summer in the historical, SSP2-4.5 and SSP5-8.5 scenarios in comparison with non-event conditions. These heatwave events generally dominate the formation of O3 peak concentrations during CE.

Comparatively, during stagnation events, the highest peak O3 concentrations undergo a substantial increase in the mid-to-late century scenario, notably in the Asian continent, with a projected increase of nearly 12% in Ofor the SSP2-4.5 scenario and a 25% increase for the SSP5-8.5 scenario. Conversely, during combined heatwave and stagnation events in the SSP2-4.5 scenario, a decrease in average concentrations is expected in the future across all continents.

These results underscore the imperative need to further mitigate air pollutant emissions during weather extremes to minimize the adverse impacts of these events on air quality and human health.

How to cite: Jimenez-Guerrero, P., Cvijanovic, I., Rodó, X., and Tarín-Carrasco, P.: Compound events increase the ground-level tropospheric ozone concentrations worldwide., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5986, https://doi.org/10.5194/egusphere-egu24-5986, 2024.

EGU24-6635 | Posters on site | ITS2.3/CL0.1.1

Temporal Analysis of Large-Scale Winds in Austral Chile 

Ana Maria Cordova, Pablo Andrade, Diana Pozo, Deniz Bozkurt, and Jorge Arevalo

Austral Chile, characterized by its intricate topography of small islands, channels, and fiords, relies heavily on navigation for local economic activities, security, and societal functions. Wind-related hazards pose a significant safety threat to navigation, with the complex topography exerting a profound influence on local wind patterns. This study undertakes a comprehensive examination of large-scale winds in the region as an initial step toward understanding the intricate dynamics of local wind systems. This study is part of a larger research project that aims to produce a very high-resolution wind forecasting system, based on the downscaling of WRF simulations by using Deep learning techniques (SiVAR-Austral, funded by ANID ID22I10206).

Utilizing 50 years of ERA 5 reanalysis daily wind fields, we employ a self-organizing map (SOM) approach, with four distinct SOMs corresponding to each season, to unveil seasonal wind patterns. Furthermore, a cluster algorithm is applied to establish relationships between these patterns, elucidating the various stages of synoptic conditions associated with different wind patterns. Through an in-depth analysis, we explore the frequencies of these patterns across different decades, providing insights into their temporal evolution.

Our findings reveal the complex interplay between the region's topography and wind patterns, offering a better understanding of the seasonal variations in large-scale winds. The identification of distinct synoptic conditions associated with specific wind patterns enhances our ability to predict and mitigate navigation-related safety threats. Additionally, the temporal evolution of these patterns across decades contributes valuable information for long-term planning and risk assessment. This research lays the foundation for a more robust comprehension of wind dynamics in Austral Chile, with potential applications in enhancing navigation safety protocols and supporting sustainable coastal development.

How to cite: Cordova, A. M., Andrade, P., Pozo, D., Bozkurt, D., and Arevalo, J.: Temporal Analysis of Large-Scale Winds in Austral Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6635, https://doi.org/10.5194/egusphere-egu24-6635, 2024.

EGU24-7651 | Orals | ITS2.3/CL0.1.1

Climatology and Trends in Concurrent Temperature Extremes in the Global Extratropics 

Antonio Segalini, Gabriele Messori, and Alexandre M. Ramos

Simultaneous occurrences of multiple heatwaves or cold spells in remote geographical regions have drawn considerable attention in the literature, due to their potentially far-reaching impacts. These include widespread crop failures, increased mortality, wildfires, power supply disruptions and more. We introduce a flexible toolbox to identify and study such concurrent temperature extremes, with adjustable parameters that different users can tailor to their specific needs and impacts of interest. We then use the toolbox to present a climatological analysis of concurrent heatwaves and cold spells in the global midlatitudes. Specific geographical areas, such as Western Russia, Central Europe, Southwestern Eurasia and Western North America, emerge as hotspots for concurrent temperature extremes. Concurrent heatwaves are becoming more frequent, longer-lasting and more extended in the Northern Hemisphere, while the opposite holds for concurrent cold spells. Concurrent heatwaves in the Southern Hemisphere are comparatively rare. However, their sharp increase in recent decades means that they are becoming an emerging hazard in the Southern midlatitudes. Notably, trends in concurrent temperature extremes are significantly stronger than the corresponding trends in all temperature extremes. This suggests that concurrent heatwaves will be an increasingly important climatic hazard in both absolute and relative terms in a future, warmer, climate.

How to cite: Segalini, A., Messori, G., and Ramos, A. M.: Climatology and Trends in Concurrent Temperature Extremes in the Global Extratropics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7651, https://doi.org/10.5194/egusphere-egu24-7651, 2024.

EGU24-8078 | ECS | Posters on site | ITS2.3/CL0.1.1

Characteristics of compound flooding along the Indian coastline: Seasonal and interannual variability 

Diljit Dutta, Venkata Vemavarapu Srinivas, and Govindasamy Bala

The Indian coastline, flanked by the Bay of Bengal and the Arabian Sea, is prone to the impact of intense low-pressure systems, specifically tropical cyclones and monsoon depressions and lows, which are accompanied by extreme rainfall and storm surges. The vulnerability of the Indian coastline to compound flooding, characterized by concurrent occurrence of extreme rainfall with extreme storm surge (SS-RF) or extreme rainfall with extreme sea level (SL-RF), poses a significant challenge in the face of changing climatic conditions. Analysing the past changes in the characteristics of compound flood events is essential to understanding the changing flood risks associated with concurrent extremes along the Indian coastline. This study utilises hourly sea level data from 8 tide gauge stations operated by Survey of India and daily rainfall data at those stations prepared from 0.25° gridded rainfall product of the India Meteorological Department (IMD). The skew surge time series corresponding to the stations are prepared by harmonic analysis of sea level data, and daily maxima of the time series which represent storm surge are analyzed. The concurrent extremes are identified as events where extremes of rainfall, sea level, and skew surge exceeded their respective 95th percentile thresholds concurrently. Our findings reveal distinct seasonal patterns, with higher occurrences of extreme sea level-rainfall (SL-RF) and extreme storm surge-rainfall (SS-RF) events during the summer monsoon (June to September) and post-monsoon (October to December) seasons along the east coast. Conversely, along the west coast, there are negligible SL-RF events throughout the year and the SS-RF events are clustered in the summer monsoon season only. The variability in frequency and intensity of concurrent extremes is higher in the post-monsoon than in the summer monsoon season along the east coast. The interannual variability of compound extremes on the east coast is primarily influenced by the El Niño Southern Oscillation (ENSO). During El Niño conditions, a decreasing trend in the frequency and intensity of concurrent extremes is observed, while La Niña conditions contribute to an increasing trend. ENSO impact also extends to the frequency and intensity of tropical cyclones during the post-monsoon season, also contributing to the interannual variability of concurrent extremes. The findings underscore the complex dynamics of the compound flood risk along the Indian coastline and provide valuable insights for assessing and managing flood risk under changing climate.

Figure 1: The number of compound extremes witnessed at typical locations along the east-coast of India during (a) the summer monsoon (JJAS) and (b) post-monsoon (OND) seasons. The El Nino and La Nina composite of the frequency of compound extremes are plotted for JJAS in (c), (d) and for OND in (e), (f).

How to cite: Dutta, D., Srinivas, V. V., and Bala, G.: Characteristics of compound flooding along the Indian coastline: Seasonal and interannual variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8078, https://doi.org/10.5194/egusphere-egu24-8078, 2024.

EGU24-8594 | ECS | Orals | ITS2.3/CL0.1.1

Reconstructing compound events from crop variability in Europe 

Niklas Luther, Arthur Hrast Essenfelder, Andrej Ceglar, Andrea Toreti, Odysseas Vlachopoulos, and Elena Xoplaki

Many studies have shown that compounding extreme events are likely to exacerbate socio-economic risks compared to single extremes. Despite this important fact, studies focussing on the connectivity of extreme events and their associated impacts frequently have some shortcomings. First, extreme events such as droughts and heat waves are often predefined through thresholds, restricting the class of meteorological events leading to the observed impacts. The choice of threshold for defining these extreme events is also often of meteorological and/or statistical nature and thus potentially unsuitable for the holistic identification of the associated impacts. Furthermore, impacts can arise from combinations of non-extreme events that might fall short of the threshold-based identification, thereby limiting the ability to account for key dynamics that determine the risk associated with compound events. Our study aims to overcome those shortcomings by linking climate events with their observed impacts in agriculture. We analyse wet and warm late winters followed by dry and hot springs, and the associated agricultural damages in Europe with the aim of reconstructing these compound events based on the observed impact. A first analysis is conducted for winter wheat impacts in France, the largest European winter wheat producer. We identify agro-climatic zones based on multivariate time series clustering and employ a regularized generalized canonical correlation analysis to identify the large-scale drivers of crop variability for these regions. The patterns that emerge from the analysis are characterized by wet and warm conditions in January and February linked to a positive North Atlantic Oscillation (NAO) state, followed by warm and dry conditions in April induced by a tripole with a blocking high over Central Europe. Using imbalanced random forests, we construct objective bounds and define thresholds to identify which temperatures are warm enough or which water balances are low enough to be associated with significant effect on crop yield reduction. Our results indicate that imbalanced random forests can predict these types of events reasonably well at the local scale, and that the derived thresholds are mostly lower than the commonly used thresholds for detecting similar extreme events. The latter illustrates that the combination of non-extreme climate events can indeed be detrimental to agricultural production in Europe, which is also crucial as the analysed types of events are predicted to occur more often in the future as a result of climate change. 

How to cite: Luther, N., Essenfelder, A. H., Ceglar, A., Toreti, A., Vlachopoulos, O., and Xoplaki, E.: Reconstructing compound events from crop variability in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8594, https://doi.org/10.5194/egusphere-egu24-8594, 2024.

EGU24-9036 | ECS | Orals | ITS2.3/CL0.1.1

Temporal clustering of rainfall for landslides detection 

Fabiola Banfi, Emanuele Bevacqua, Pauline Rivoire, Sérgio C. Oliveira, Joaquim G. Pinto, Alexandre M. Ramos, and Carlo De Michele

Landslides are impactful and complex natural hazards, causing important damages in vulnerable areas. They can be related to several pre-existing conditions and triggering factors. The former are variables that do not directly cause the event but that increase its likelihood in the presence of a triggering variable. Example of the former are the slope or the aspect, of the latter precipitation, earthquakes, snowmelt, or human disturbances. Among the triggering factors the most important is rainfall. Usually deep-seated movement, characterized by a slip surface deeper than 1.5 m, are related to repeated moderate precipitation episodes while shallow landslides, characterized by a slip surface less deep than 1.5 m, to single and more intense episodes. Landslide detection is usually performed with the use of precipitation thresholds, either process-based or empirical ones. Here we introduce a new methodology to detect landslides based on temporal clustering of precipitation. Temporal clustering is a particular typology of compound event falling inside the category of temporal compounding events and it is defined as the occurrence of multiple events of the same type in close succession. The new method is compared with the use of empirical rainfall threhsolds considering as case study two landslide inventories in the Lisbon region, Portugal. The method shows a better sensitivity with respect to empirical rainfall thresholds and a performance in terms of precision variable dependending on the site. In general, the detection of deep landslides is better than of shallow landslide. The method requires only precipitation data and the selection of a precipitation quantile to identify events and it could help to improve the detection of rainfall-triggered landslides.

How to cite: Banfi, F., Bevacqua, E., Rivoire, P., Oliveira, S. C., Pinto, J. G., Ramos, A. M., and De Michele, C.: Temporal clustering of rainfall for landslides detection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9036, https://doi.org/10.5194/egusphere-egu24-9036, 2024.

EGU24-9167 | ECS | Posters on site | ITS2.3/CL0.1.1

Avoided impacts of climate change on compound hot-dry events under sustainable development versus fossil-fueled development 

Parisa Hosseinzadehtalaei, Piet Termonia, and Hossein Tabari

Climate change is expected to increase the frequency and intensity of compound hot-dry events, which can have significant impacts on human life, economic systems, and agriculture. The extent of this impact depends on the socioeconomic pathway we adopt in the future. While sustainable development aspires to reconcile economic growth, environmental protection, and social equity, thereby ensuring a more sustainable future for all, fossil-fueled development may drive economic growth at the expense of exacerbating climate change, pollution, and resource depletion. This study employs a CMIP6 multi-model ensemble to scrutinize the global-scale potential for mitigating climate change impacts on compound hot-dry events under sustainable development versus fossil-fueled development. These events are quantified by analyzing the joint distribution probability between temperature and soil moisture extremes through bivariate copula functions. The results show that although the likelihood of compound hot-dry events is expected to increase under both scenarios, the increase under fossil-fueled development is anticipated to be twice larger than that under sustainable development. The results show that although the likelihood of compound hot-dry events is expected to increase under both scenarios, the increase under fossil-fueled development is anticipated to be twice as large as that under sustainable development. The mitigated impact through sustainable development is not regionally uniform, with the largest mitigation, up to one-third, expected in the Mediterranean region.

How to cite: Hosseinzadehtalaei, P., Termonia, P., and Tabari, H.: Avoided impacts of climate change on compound hot-dry events under sustainable development versus fossil-fueled development, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9167, https://doi.org/10.5194/egusphere-egu24-9167, 2024.

EGU24-9271 | Posters on site | ITS2.3/CL0.1.1

Monitoring compound drought-heat events over Brazil’s Pantanal wetland 

Ana Paula Martins do Amaral Cunha

Brazil’s Pantanal wetland is one of the most threatened Brazilian ecosystems from direct anthropogenic pressures and climate change. In this study, the overarching research question is to explore whether compound drought-heat events (CDHEs) have become more recurrent, intense, and widespread over Brazil’s Pantanal wetland in recent decades. For this, two different approaches were proposed and tested using validated long-term time series of monthly precipitation, temperature, and the satellite-based Vegetation Health Index (VHI) to characterize the spatiotemporal pattern of CDHEs over Pantanal. The Standardized Precipitation Index (SPI), Standardized Temperature Index (STI), and Standardized Precipitation Evapotranspiration Index (SPEI) from 1981 to 2021 were calculated. The results showed that using both approaches, the frequency of events is higher in the moderate category, which is expected since the criteria are less restrictive. In addition, the highest frequency of CDHE events occurs at the end of the dry season. The results also indicated that CDHE events have been more recurrent and widespread since 2000 in Pantanal. Besides, considering all methods for identifying the CDHEs, the probability density function indicates a shift pattern to warmer and drier conditions in the last 40 years. The Mann-Kendall tests also confirmed the assumption that there is a significantly increasing trend in the compound drought-heat events in the Pantanal. Developing methodologies for monitoring compound climate events is crucial for assessing climate risks in a warming climate. Besides, it is expected that the results contribute to convincing the urgent need for environmental protection strategies and disaster risk reduction plans for the Pantanal.

How to cite: Martins do Amaral Cunha, A. P.: Monitoring compound drought-heat events over Brazil’s Pantanal wetland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9271, https://doi.org/10.5194/egusphere-egu24-9271, 2024.

EGU24-10748 | ECS | Orals | ITS2.3/CL0.1.1

Changes in the causal effect networks of single and compound extreme hot and dry events in Central Europe 

Giorgia Di Capua, Yinglin Tian, Domenico Giaquinto, Judith Claassen, Javed Ali, Hao Li, and Carlo De Michele

Hot and dry extreme events in Europe have become more frequent and pose serious threats to human health, agriculture, infrastructure, and ecology. Single and compound hot and dry extremes in Europe have been attributed to synoptic atmospheric circulation variations and land-atmosphere interactions. However, the exact causal pathways and their strength, as well as their historical trends, have not been quantified. An accurate understanding of the mechanisms behind these land-atmosphere extremes is crucial to improving S2S forecasts and implementing appropriate adaptation measures. Here, we use the Peter and Clark momentary conditional independence (PCMCI) based Causal Effect Networks (CENs) to detect and quantify dynamic and thermodynamic causal precursors of extremely high 2m temperature (T2m) and extremely low soil water deficit and surplus (WSD) in central Europe (CEU).

Our analysis reveals that the single hot events are driven mainly by anomalous atmospheric patterns and soil water deficiency, while single dry events are mainly driven by the soil moisture memory, and anomalous atmospheric patterns, and only marginally by temperature changes. The atmospheric circulation patterns preceding both single hot and dry events show a high-pressure system over central Europe, with a low-pressure system over the Atlantic Ocean, and partly explain the occurrence of the compound events. This atmospheric pattern is also linked to an anomalous zonal cold-warm-cold SST pattern over the Atlantic Ocean and a warmer eastern Pacific Ocean.

The identified causal links vary with temperature and humidity conditions, that is, the impact of soil moisture memory on the WSD variation is sensitive to T2m and WSD, while the influence of soil moisture condition on T2m changes is strengthened by reduced WSD. Moreover, during compound hot and dry extremes, the effect of reduced soil moisture on temperature is significantly higher than during single events, reaching twice the magnitude under moderate conditions. When historical trends are analyzed, we show that the impact of dry soil on temperature is amplified by 42% (46%) for single (compound) extremes during 1979-2020, while the influence of atmospheric drivers on soil moisture is intensified by 28% (43%).

This work emphasizes (i) the intensification of the strength of the thermodynamic causal pathways for warmer and dryer CEU over time and (ii) the stress on the varying forcing strength of the drivers, which can lead to non-linear variations of weather stressors under climate changes and thus add extra challenges to extreme adaptations.

 

 

How to cite: Di Capua, G., Tian, Y., Giaquinto, D., Claassen, J., Ali, J., Li, H., and De Michele, C.: Changes in the causal effect networks of single and compound extreme hot and dry events in Central Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10748, https://doi.org/10.5194/egusphere-egu24-10748, 2024.

EGU24-11331 | ECS | Posters on site | ITS2.3/CL0.1.1

Time and period of emergence of compound events in France 

Joséphine Schmutz, Mathieu Vrac, and Bastien François

Compound events (CE) are the combination of climate phenomena which, taken individually, are not necessarily extreme but whose (concurrent or sequential) composition can cause very strong impacts and damages. Hence, the understanding of their potential past and future changes and evolutions are of great importance and, thus, more and more research is being carried out on this issue ([1], [2]). However, these questions are still rarely addressed over France, especially at high spatial resolution, even though they are necessary for the development of adaptation strategies. The present study focuses on historical multivariate compound events (several events occurring at the same time and same location), like hot and dry events or extreme wind and precipitation events, and aims to detect past changes in probability of such events over France. ERA5 reanalyses [3] are then used on the 1950-2022 period.

The first question that arises is: Where and when did these signals emerge in France? Are patterns forming? This issue is addressed through the analysis of “times” and “periods” of emergence, corresponding to moments when the change in probability of a specific CE is out of its natural variability [4].  The second question that comes up is: “What drives the emergence? What are the contributions of the changes in the marginal distributions and in the dependence structure to the change of compound events probability?” The study tries to answer this question thanks to the copula theory, allowing to decompose these different contributions. Copula functions are used to model bivariate joint probabilities, and are increasingly applied to hydroclimatic variables ([5], [6]).

Depending on the intensity and the type of the compound, the results indicate that (1) maps of time of emergence show clear spatial patterns and (2) that the changes in marginal distributions play a much more significant role than the changes in dependence during the emergence. This work opens perspectives for future projects, such as investigating physical phenomena driving these patterns and more deeply understanding changes in dependence between the different climate variables. Then analyzing climate model ability to reproduce the results would enable the application of the methodology to attribution framework and a better assessment of the risks associated with past and future climate change. 

References
[1] Singh, Harsimrenjit, Mohammad Reza Najafi, and Alex J. Cannon. "Characterizing non-stationary compound extreme events in a changing climate based on large-ensemble climate simulations." Climate Dynamics 56 (2021): 1389-1405.
[2] Ridder, N. N., et al. "Increased occurrence of high impact compound events under climate change." Npj Climate and Atmospheric Science 5.1 (2022): 3.
[3] Hersbach, Hans, et al. "The ERA5 global reanalysis." Quarterly Journal of the Royal Meteorological Society 146.730 (2020): 1999-2049.
[4] François, Bastien, and Mathieu Vrac. "Time of emergence of compound events: contribution of univariate and dependence properties." Natural Hazards and Earth System Sciences 23.1 (2023): 21-44.
[5] Zscheischler, Jakob, and Sonia I. Seneviratne. "Dependence of drivers affects risks associated with compound events." Science advances 3.6 (2017): e1700263.
[6] Tootoonchi, Faranak, et al. "Copulas for hydroclimatic analysis: A practice‐oriented overview." Wiley Interdisciplinary Reviews: Water 9.2 (2022): e1579.

How to cite: Schmutz, J., Vrac, M., and François, B.: Time and period of emergence of compound events in France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11331, https://doi.org/10.5194/egusphere-egu24-11331, 2024.

EGU24-11345 | Orals | ITS2.3/CL0.1.1

Understanding the association between global teleconnections and concurrent drought and heatwaves events over India 

Rajarshi Das Bhowmik, Ruhhee Tabbussum, and Pradeep Mujumdar

The variability in the occurrence of concurrent extremes like droughts and heatwaves is often attributed to climate change and anthropogenic factors, neglecting its connection with large-scale global teleconnections. The current study investigates the temporal and spatial connections between concurrent droughts and heatwaves (CDHW) in India to large scale global teleconnections like El Nino Southern Oscillation, North Atlantic Oscillation, Pacific Decadal Oscillation, and Indian Ocean Dipole. Utilizing composite and wavelet coherence analyses, we conduct a univariate assessment of droughts and heatwaves, quantified with the standardized precipitation index and standardized heat index, respectively, in association with large-scale global teleconnections (referred as climate drivers). Further, a novel attribution table framework proposed to quantify the conditional probability of CDHW given the onset of climate drivers. We found that the probability of CDHW preceeding the onset of climate drivers is much higher compared to the probability of CDHW occuring without the onset of climate drivers. The insights from this study suggest the potential use of global teleconnections for issuing season-ahead forecasts of CDHW.

How to cite: Das Bhowmik, R., Tabbussum, R., and Mujumdar, P.: Understanding the association between global teleconnections and concurrent drought and heatwaves events over India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11345, https://doi.org/10.5194/egusphere-egu24-11345, 2024.

EGU24-11560 | Orals | ITS2.3/CL0.1.1

Compound Flood Potential from Co-occurrence of River Discharge and Storm Surge in Croatia 

Nino Krvavica, Marta Marija Bilić, and Igor Ružić

Coastal areas are becoming increasingly vulnerable due to climate change. These regions are exposed to various sources of flooding, such as high sea levels, river discharge and heavy rainfall. Our study focuses on understanding compound flooding from storm surges and river discharge in Croatia. This is the first study on compound floods in this country. For this purpose, we analysed the time series of water levels and discharges from hydrological stations located along ten major coastal rivers. Since there are only a limited number of tide gauges in Croatia, we combined measured data with numerical reanalyses. The sea level data for the entire Adriatic Sea were obtained from the Copernicus Marine Service (Mediterranean Sea Physics Reanalysis) and were then corrected using machine learning and measured data.

Previous studies have shown that neglecting seasonal variations in river discharge and storm surges could lead to a significant underestimation of the expected annual damage from compound floods. Different seasons bring distinct weather and river discharge patterns that influence the probability and severity of compound floods. To address this, our study investigated seasonal correlation and co-occurrence by analysing the monthly maximum values. By examining each season in detail, we uncovered the variations in the compound flood potential index.

This analysis provides a more comprehensive understanding of compound floods in Croatia, which is crucial for risk assessment and risk management. Finally, we mapped the correlation coefficients, the number of co-occurrences and the compound flood potential index along the Croatian coast and organised the results in a GIS database. These maps will improve our ability to systematically select the most vulnerable areas where the risk of compound flooding should be analysed at the local level.

How to cite: Krvavica, N., Bilić, M. M., and Ružić, I.: Compound Flood Potential from Co-occurrence of River Discharge and Storm Surge in Croatia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11560, https://doi.org/10.5194/egusphere-egu24-11560, 2024.

Changes in wind speed and temperature significantly co-alter soil erosion climatic erosivity. However, knowledge on compound climatic elements of soil erosion to climate change is limited. Here, we quantify long-term climatic erosivity based on the wind erosion climatic erovisity and freeze-thaw climatic index, and analyze the contributions of single and compound factors using the slope change ratio of accumulative quantity methods. Our results show frequency of compound events is gradually decreasing as a result of climate change. Compound climatic erosivity exhibits large spatial variability and decreases with the wind erosion climatic erosivity and freeze-thaw climatic index. Moreover, a negative temporal trend of compound climatic erosivity is found in 61.28% of the study area from 1981 to 2020, which is largely attributed to declining wind speed. One unanticipated finding was that the frequency of compound erosion has shown a decreasing trend at some sites, but the intensity has shown an increasing trend. A possible explanation for this might be the extreme wind speeds and temperatures. Our findings highlight compounding effects of climatic conditions have a more severe impact on soil erosion.

How to cite: Yang, W.: Compound variation in freeze-thaw index and wind climatic erosivity in the agro-pastoral ecotone in northern China , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12712, https://doi.org/10.5194/egusphere-egu24-12712, 2024.

EGU24-12824 | Orals | ITS2.3/CL0.1.1

Local climate change impacts - new insights for mountain regions of Salzburg based on high resolution climate simulations 

Marianne Bügelmayer-Blaschek, Kristofer Hasel, Johann Züger, Robert Monjo, and César Paradinas

Climate change impacts are accelerating and intensifying, as observed over the past years, especially in the past year 2023.The current CMIP6 global climate simulations (GCMs) show higher climate sensitivity resulting in stronger warming and related impacts than previous simulations. Mountain regions are especially vulnerable as the warming climate relates to thawing of permafrost destabilising slopes and the emerging risk of heat and altered precipitation pattern that cause (extreme) flooding. Furthermore, the occurrence of compound events has gained increased attention as those pose substantial threat to the prevailing settlements and infrastructure.

Nevertheless, the available GCM simulations are spatially too coarse to investigate the mentioned extreme events in complex terrain. Therefore, statistical and dynamical downscaling is performed within the ICARIA project (Russo et al., 2023) to better analyse future climate impacts for the mountain regions of Salzburg. For the dynamical downscaling two regional climate models (RCMs), the WRF and COSMO-CLM (CCLM) are used to simulate the future climate conditions for the SSP126, SSP585 at spatial resolution of 2-5 km2 until 2100.

The verification of the two RCMs with respect to CHELSA (Karger et al., 2017) display that the 5km² WRF model simulations overestimate the precipitation intensities, especially in mountainous regions, the same goes for CCLM. With respect to temperature, WRF and CCLM display an underestimation of temperature in higher altitudes (above 600m) and a good representation below.

Additionally, statistical downscaling has also been performed within ICARIA following the FICLIMA method. For this procedure, a set of 59 weather observations were used together with 10 CMIP6 GCMs. ERA5-Land and statistics such as MAE, Bias or Kolmogorov-Smirnov test were used for verification purposes of the methodology for each spot and model. Those that passed filters of quality and performance in the representation of past climate produced local downscaled climate projections at daily resolution for each location for the Tier 1 SSPs (1.26, 2.45, 3.70 and 5.85). Both the statistical and dynamical downscaling methods' outputs will serve to compare results and better assess the inherent uncertainties of climate projections.

Since the focus is on extreme events, the prevailing simulations are analysed with respect to the global warming levels (1.5°C, 2°C, 3°C and 4°C) and their related local impacts. To investigate extreme events related to precipitation and wind, as well as their compound occurrence, suitable indicators are investigated, such as precipitation intensity estimates through future IDF curves and wind gust events with return periods of 1, 2, 5, 10, 20, 50, 100, 500 years. Further, consecutive events, that have a compound impact on the system, are considered through investigating the region and hazard specific time period before and after the occurrence of the extreme event.

 

Russo, B., de la Cruz Coronas, À., Leone, M., Evans, B., Brito, R. S., Havlik, D., ... & Sfetsos, A. (2023). Improving Climate Resilience of Critical Assets: The ICARIA Project. Sustainability, 15(19), 14090

Karger, D. N., Conrad, O., Böhner, J., Kawohl, T., Kreft, H., Soria-Auza, R. W., ... & Kessler, M. (2017). Climatologies at high resolution for the earth’s land surface areas. Scientific data, 4(1), 1-20.

How to cite: Bügelmayer-Blaschek, M., Hasel, K., Züger, J., Monjo, R., and Paradinas, C.: Local climate change impacts - new insights for mountain regions of Salzburg based on high resolution climate simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12824, https://doi.org/10.5194/egusphere-egu24-12824, 2024.

EGU24-12906 | ECS | Orals | ITS2.3/CL0.1.1 | Highlight

Summers full of extreme heat: using ensemble boosting storylines to quantify the drivers of heatwave clusters 

Laura Suarez-Gutierrez, Urs Beyerle, Magdalena Mittermeier, Robert Vautard, and Erich M. Fischer

We investigate the most extreme but physically plausible heat-loaded European summers in current and near future climate conditions using ensemble boosting. With this approach, we identify the most extreme summers in an initial-condition large ensemble with the model CESM2 and boost them, creating a large ensemble of re-initialized simulations with slightly perturbed atmospheric initial conditions. This allows us to efficiently generate storylines for summers that are even more extreme than the original simulations, either due to a higher number of days or grid cells exceeding extreme heat thresholds, or original heatwave clusters exceeding such thresholds by larger margins.

We compare these storylines of summer heat clusters to the most extreme European summers in the observational record, and determine the necessary and exacerbating mechanisms behind these clusters of extreme heat. We quantify how factors such as the intensity and persistence of atmospheric patterns as well as sea surface temperatures and terrestrial water budgets contribute to the most extreme simulated summers. Furthermore, we disentangle the effects of extreme early heat in May-June acting as a preconditioning factor in driving more extreme conditions during the rest of the summer, due to it causing more heat-prone conditions such as warmer oceanic basins and dryer soils, versus the effects of large-scale preconditioning factors that may lead to more persistent and intense heat through the summer, regardless of if it starts early in the season or not.

Ensemble boosting is a computationally efficient approach that allows us to sample extreme rare events, now over time scales of several months, while preserving physical consistency both in time, space and across variables. This is an ideal setup for disentangling contributions from different driving factors, and the generated boosting storylines can be used in impact studies that require physical consistency, a prolonged simulation time, and successive or compounding hazard exposure.

How to cite: Suarez-Gutierrez, L., Beyerle, U., Mittermeier, M., Vautard, R., and Fischer, E. M.: Summers full of extreme heat: using ensemble boosting storylines to quantify the drivers of heatwave clusters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12906, https://doi.org/10.5194/egusphere-egu24-12906, 2024.

Global coffee production is at risk from synchronous crop failures, characterised by widespread reductions in yield occurring in multiple regions at the same time. For other crops, we know that these synchronous failures can be forced by spatially compounding climate anomalies, which in turn may be driven by large-scale climate modes like the El Niño Southern Oscillation (ENSO).

This talk will discuss the extent to which climate hazards occur and co-occur across the world’s major coffee-growing regions. These climate hazards include temperature and rainfall anomalies and are selected to cover two coffee species and different periods of the crop growing cycle. The talk will show that regional and global risk posed from spatially compounding hazards has increased over recent decades. There is a clear shift in the profile of this risk. Temperature-based hazards are now much more likely to exceed thresholds for optimal growing conditions, rather than being overly cold as observed during the 1980s.

Through multiple lines of evidence we find relationships between spatially compounding hazards and six tropical climate modes such as ENSO and the Madden Julian Oscillation. Individual regions exhibit differing relationships with these modes. ENSO is found to have the strongest links with multiple regions during the same crop cycle, posing implications for ENSO-driven global impacts to supply.

How to cite: Richardson, D.: The risk to global coffee supply from synchronous climate hazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13620, https://doi.org/10.5194/egusphere-egu24-13620, 2024.

EGU24-14082 | Orals | ITS2.3/CL0.1.1

Translating Flood Insurance Claims in the Coastal CONUS within the Spectrum of Compound Flood Risk 

Mahjabeen Fatema Mitu, Giulia Sofia, Xinyi Shen, and Emmanouil N. Anagnostou

The intricate physical complexity of compound coastal flooding—resulting from the combination of river floods and storm surges—is known for often leading to more severe consequences than independent-driver floods. Damages from this type of flooding are expected to increase due to the impact of climate change on precipitation patterns and coastal storms, coupled with the increasing trends in population growth and economic activities along coastal regions. In the United States, the Federal Emergency Management Agency’s (FEMA) National Flood Insurance Program (NFIP) is the largest provider of flood insurance policies, and currently, more than two million NFIP flood claim transactions (1978 to present) are available to the public for analysis. However, there is a lack of studies that analyze how compound events reflect on insurance claims.

In this study, we focus on over 60,000 counties across the entire coastline of the United States to provide an exhaustive analysis of the distribution of economic losses in areas subject to river flooding, coastal flooding, and regions susceptible to compound events.

To identify the relative importance of the driving mechanisms (inland vs. coastal flows) for a particular location, we apply a published index [D-Index, readers are referred to the article, https://doi.org/10.1016/j.jhydrol.2023.130278 for details] that is capable of physically attributing the cause of flood depth to either river or coastal drivers, or a combination of both rainfall and storm surge.

We focus the analysis on the number of damages reported in the claims, comparing and contrasting claims in counties physically labeled as coastal, river, or compound. By calculating the quantile weight distance (QWD) of the damages from claims in the ‘compound’ counties and claims in the ‘independent-driver’ counties, we further investigate how rainfall and tide characteristics of storm events relate to the NFIP flood claims in the case of compound events. We further quantify differences in QWD by comparing and contrasting FEMA’s high-risk flood zones (identifying the 1-percent annual chance floodplain), where insurance is required for homes financed through federally backed or federally-regulated lenders, and FEMA’s low and moderate-risk flood zones, where flood insurance is not required.

In conclusion, this study furnishes invaluable insights into the intricate challenges of assessing compound coastal flooding impacts on insurance claims. The proposed methodology, integrating a flood type-specific mapping system and considering spatial variabilities of inundation characteristics, establishes a robust foundation for a comprehensive and improved flood risk assessment in coastal CONUS.

These findings empower coastal communities to proactively manage concealed risks and fortify their resilience against the compounding impacts of environmental forcings. This research offers a proactive and informed strategy to mitigate the potentially disastrous consequences of compound coastal flooding in a changing climate and socio-economic landscape.

How to cite: Mitu, M. F., Sofia, G., Shen, X., and Anagnostou, E. N.: Translating Flood Insurance Claims in the Coastal CONUS within the Spectrum of Compound Flood Risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14082, https://doi.org/10.5194/egusphere-egu24-14082, 2024.

EGU24-14205 | ECS | Orals | ITS2.3/CL0.1.1

Fast and Accurate Calculation of Wet-bulb Temperature for Humid-Heat Extremes 

Cassandra Rogers and Robert Warren

It is well known that heat extremes have increased in frequency, intensity, and duration over recent decades. However, since extreme heat is typically examined using dry-bulb temperature, the reported changes do not fully reflect the impacts these events may have on human health. By accounting for humidity in measures of extreme heat, we can gain a better understanding of the health risk associated with these events in current and future climates.  

  

A variety of indices are used to examine humid heat. One of the simplest is wet-bulb temperature (Tw), which is defined as the temperature of a parcel of air cooled to saturation by the evaporation of water into it. Tw is typically calculated using empirical equations (e.g., Stull 2011, Davies-Jones 2008); however, these can be inaccurate for extreme values or slow due to the need for iterations in the solution. Here, we present a fast and highly accurate calculation of Tw, which we call NEWT (Noniterative Evaluation of Wet-bulb Temperature). This method follows the diagrammatic approach to evaluating Tw, where a parcel is lifted dry adiabatically to its lifting condensation level (LCL) and then brought pseudoadiabatically back to its original level. To avoid the need for iterations, NEWT uses exact equations for the LCL from Romps (2017) and a modified version of the high-order polynomial fits to pseudoadiabats from Moisseeva and Stull (2017).  

  

A comparison of NEWT with three other methods for calculating Tw (Stull, MetPy, and Davies-Jones) reveals a marked improvement in accuracy, with maximum errors of ~0.01°C (cf. ~1.3°C for Stull, ~0.4°C for MetPy, and ~0.05°C for Davies-Jones). The accuracy of each method is further assessed using Automatic Weather Station data from the Bureau of Meteorology, with a focus on extreme values. 

How to cite: Rogers, C. and Warren, R.: Fast and Accurate Calculation of Wet-bulb Temperature for Humid-Heat Extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14205, https://doi.org/10.5194/egusphere-egu24-14205, 2024.

EGU24-14358 | ECS | Posters on site | ITS2.3/CL0.1.1

Compound occurrence of heat waves and drought in the Northern Hemisphere, atmospheric circulation patterns and impacts. 

Natalia Castillo, Marco Gaetani, and Mario Martina

The compound occurrence of heatwaves and droughts (COHWD) may result in disastrous impacts and losses across various socioeconomic sectors. Therefore, it is important to understand and predict these phenomena to support decision makers and stakeholders in implementing preparedness and adaptation measures. However, questions concerning the underlying physics that drive and potentially exacerbate these extremes in the future still remain open. 

This study focuses on identifying COHWD and their characteristics during the lasts 62 summers through the analysis of atmospheric variables from the ERA5, GPCC and CRU datasets in the northern hemisphere (NH). Three regions, as categorized in the latest IPCC report, are analyzed: Western & Central Europe (WCE), the Mediterranean (MED) and Eastern Asia (EAS). These regions are selected because they account for the main breadbaskets in the NH.

Results show that WCE and MED have witnessed an increase in the area affected by COHWD over . In contrast, EAS does not exhibit a clear trend over the past six decades.  Moreover, by analyzing the variability of large atmospheric circulation patterns and climate oscillations, such as the North Atlantic Oscillation and the El Niño/Southern Oscillation, the dynamical drivers of COHWDs are identified. This research aims at providing new insights into the dynamical mechanisms driving COHWDs, to improve the identification, understanding, prediction and management of such events in the future. 

How to cite: Castillo, N., Gaetani, M., and Martina, M.: Compound occurrence of heat waves and drought in the Northern Hemisphere, atmospheric circulation patterns and impacts., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14358, https://doi.org/10.5194/egusphere-egu24-14358, 2024.

EGU24-14371 | ECS | Posters virtual | ITS2.3/CL0.1.1

Pathways to temperature variability in South Asia 

Hardik Shah and Joy Monteiro

For improving climate projections, there is a need to understand the physical processes governing the variability of dynamically driven variables, like near-surface temperature. Studies have shown that some features like surface drying and anticyclonic upper level conditions are associated with enhanced surface warming. However, the different ways in which surface, radiative and atmospheric variables compound to cause a heatwave, and the relative magnitudes of these variables and their relationship with heatwave intensity has not been well understood. Further, the large scale dynamics governing such conditions, and the effects of slowly varying climate features like ENSO and AO, are unresolved.

Using the ERA5 reanalysis dataset, we are studying the drivers of variability of daily mean 2 meter temperature (T2m) anomaly over the northwest Indian heatwave hotspot region, in the entire premonsoon season (March to June). Our approach is to develop an interaction framework which identifies governing surface and weather regimes active during different months, and quantify how large-scale climate patterns modulate their frequency of occurrence. We are leveraging the decision tree classification framework to identify the dominant weather patterns explaining different quartiles of T2m anomaly, owing to its non-linear modeling capability. 

During March and April, the T2m anomalies are accompanied by a vertically coherent temperature anomaly field, and typically last only for a day or two. The decision tree classification algorithm suggests that anomalous surface warming during this period is preceded by increased shortwave radiation corresponding to subsidence across the tropospheric extent. The decay of such an anomaly is marked by decreased downward shortwave radiation fluxes and increased downward longwave radiation fluxes, indicating the role of ventilation and cloud formation. The direction of sensible flux anomaly also changes between the two phases, directed from the atmosphere to the surface in the warming phase, and from the surface of the atmosphere in the decay phase. During May and June, the warming anomalies last for more than three days, and the sensible heat flux anomalies are directed toward the surface. Although shortwave anomalies peak along with T2m anomalies, there is also an increased convergence of dry static energy in the lower troposphere, between 600–900 hPa, in the region. Geopotential anomalies on the 350 K isentropic surface are anti-correlated with potential vorticity anomaly, establishing the role of Rossby wave packets as the dynamical drivers of temperature variability in this region. 

Thus, we show how an interpretable machine learning algorithm like the decision tree could potentially identify proximal drivers and compounding factors of heatwaves, provide a way to rank them by their importance, and eventually lead to a multiscale framework by incorporating longer term signals such as ENSO. 

How to cite: Shah, H. and Monteiro, J.: Pathways to temperature variability in South Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14371, https://doi.org/10.5194/egusphere-egu24-14371, 2024.

EGU24-14461 | ECS | Orals | ITS2.3/CL0.1.1

Accelerating Heatwaves Intensify Spatial Synchronization of Compound Drought and Heatwave Events 

Waqar ul Hassan, Md Saquib Saharwardi, Hari Prasad Dasari, Harikishan Gandham, Ibrahim Hoteit, and Yasser Abualnaja

Compound droughts and heatwaves (CDHWs) exert substantial socio-economic and ecological impacts, with their impacts reach epidemic proportions when CDHWs manifest simultaneously across multiple locations. Recent studies have begun to understand CDHWs, but their spatial compounding effects are not yet explored. This study utilizes weekly precipitation and temperature data to investigate the spatial synchronization of CDHWs and its changes. We define drought and heatwave weeks using the Standardized Precipitation Index (SPI 3-weekly) and the 90th percentile threshold of weekly temperatures. Our analysis reveals an unprecedented increase in the global land area and the number of regions experiencing concurrent CDHWs, particularly notable post-2000. The frequency of globally synchronized CDHWs (more than 5 regions affected simultaneously) has surged from 3 weeks (1982-1992) to 18 weeks (2012-2022), which is primarily attributed to a simultaneous global rise in temperatures driven by climate change. Analyzing CDHWs from observed data and counterfactual scenarios, where temperature data is detrended, we noted significantly higher likelihood of synchronization in observations due to intensified heatwaves in a warmer world. Notably, certain region pairs exhibit a higher likelihood of CDHW synchronization regardless being geographically distant. Spearman correlation and Granger causality analyses highlight major climatic modes, including El-Nino Southern Oscillation, Atlantic Multidecadal Oscillation, Western Tropical Indian Ocean, and Mode-2 of global Sea Surface Temperature, influencing changes in the areal extent of CDHWs globally as well as regionally. These insights are useful to predict the CDHWs and to quantify their socio-ecological impacts.

How to cite: ul Hassan, W., Saharwardi, M. S., Prasad Dasari, H., Gandham, H., Hoteit, I., and Abualnaja, Y.: Accelerating Heatwaves Intensify Spatial Synchronization of Compound Drought and Heatwave Events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14461, https://doi.org/10.5194/egusphere-egu24-14461, 2024.

EGU24-14796 | ECS | Orals | ITS2.3/CL0.1.1

Compound Coastal Flooding Drivers in the Pacific Northwest: Understanding Precipitation-Surge-Wave Interactions and Projected Changes 

Mohammad Fereshtehpour, Mohammad Reza Najafi, and Mercè Casas-Prat

Coastal regions face escalating threats under climate change, necessitating a comprehensive understanding of compound flooding dynamics. This study aims to investigate the interplay between precipitation, wind waves, and meteorologically-driven storm surge, assessing their joint behavior leading to compound coastal flood risks in the Pacific Northwest. We examined two approaches to capture all possible drivers leading to compound events, which may not necessarily result from the extreme conditions of individual marginal variables. First, we used a conditional approach and assessed the block maxima (BM) of each variable in conjunction with the corresponding values of the other variables. Second, a peak-over-threshold (POT) investigation was conducted to generate datasets where all variables exceed their 95th percentiles. To calculate the joint return period of coastal flooding drivers, we used the most appropriate marginal distributions commonly used in coastal engineering, including the Generalized Pareto Distribution (GPD) for the POT-based approach and the Generalized Extreme Value (GEV) distribution for the BM. Subsequently, we computed the joint probability distribution by fitting the best-suited copula to the datasets to capture the interdependencies between the drivers. Moreover, as meteorological drivers may change under global warming, we extended our analysis to consider future projections of surge, waves, and precipitation. This enabled us to examine changes in the aforementioned dependencies and return periods. Sub-daily time series of surge and wave heights were obtained from the Canadian Coastal Climate Risk Information System (CCCRIS) (https://cccris.ca/), which provides high-resolution (~250 m along coastlines) simulations driven by ERA5 reanalysis and future projections until 2100 under the RCP8.5 emission scenario driven by four different combinations of global and regional models, namely, CanESM2.CanRCM4, CanESM2.CRCM5-QUAM, MPI-ESM-MR.CRCM5-QUAM, and GFDL-ESM2M.WRF. For each grid point, the corresponding precipitation data is obtained from the nearest grid point of the respective climate models. We assessed the degree to which each driver contributed to the overall change in the joint return period of concurring extremes in coastal flooding. We also conducted an analysis to quantify the respective contributions of each driver’s projection and their dependence structure to the uncertainty in changes of return periods. This study leveraged high-resolution data that encapsulated the regional dynamic responses, which is pivotal for precisely evaluating climatic hazards and developing efficient adaptation schemes, thereby ensuring a more informed decision-making process for coastal management and engineering applications.

How to cite: Fereshtehpour, M., Najafi, M. R., and Casas-Prat, M.: Compound Coastal Flooding Drivers in the Pacific Northwest: Understanding Precipitation-Surge-Wave Interactions and Projected Changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14796, https://doi.org/10.5194/egusphere-egu24-14796, 2024.

EGU24-15681 | Posters on site | ITS2.3/CL0.1.1

Climate change impact on inland flood risks due to compound storm tide and precipitation events for managed low-lying coastal areas. 

Lidia Gaslikova, Helge Bormann, Jenny Kebschull, Ralf Weisse, and Elke Meyer

Many coastal low-lying areas prone to coastal floods are protected by defense constructions. This often entails the establishing of artificial drainage systems to keep the hinterlands from flooding during heavy rain events. The coincidence of storm tide and heavy precipitation events may considerably limit the technical drainage capacity and lead to flooding. This situation can be exacerbated in the future due to changing conditions of both single drivers as well and their combinations. To assess the risks of inland flooding, a model based approach, combining the results from regional climate models with hydrological model for hinterlands and hydrodynamic model for coastal areas is established and applied. As a focus area, the water board Emden (Germany) and the gauge Knock are selected, which is a low-lying artificially drained area between the Ems river and the North Sea. For historical events, the main drivers leading to diminished drainage capacity and system overload were moderate storm series combined with the large-scale heavy precipitations. Whereas extreme storm tides or heavy precipitations alone posed no significant challenge for the system. The combinations of future emission scenarios (RCP2.6 and RCP8.5) and regionalized climate models (MPI-ESM and HadGEM2) together with local sea level rise projections are used to estimate the system overload and flood risk under the climate change conditions. For control period, the main cause of moderate system overload appears to be heavy precipitations rather than storm tides. For future projections, the importance and intensity of compound events will increase, reflecting changes in mean sea level and thus storm tides as well as intensification of heavy rain events.

How to cite: Gaslikova, L., Bormann, H., Kebschull, J., Weisse, R., and Meyer, E.: Climate change impact on inland flood risks due to compound storm tide and precipitation events for managed low-lying coastal areas., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15681, https://doi.org/10.5194/egusphere-egu24-15681, 2024.

EGU24-15746 | ECS | Posters on site | ITS2.3/CL0.1.1

Determining the frequency of unfavorable conditions for sailing in Adriatic Sea channels  

Ena Kožul, Iris Odak Plenković, and Ines Muić

The intricate coastline of the Adriatic Sea presents challenges for sailing, especially through narrow island channels in severe weather conditions. To plan construction work, an assessment was requested to determine the most favorable period for conducting maritime activities in two channels in the first half of the year, the Hvar Channel and the Korčula Channel. Motivated by that request, climatological analysis using available measurements of several meteorological parameters was conducted.

Favorable conditions for sailing usually include weak or moderate wind intensity, often generated by island or coastal circulation. To determine the unfavorable conditions for maritime transport several meteorological parameters are examined with emphasis on wind, wave height, and thunderstorms, as these might contribute to the most hazardous sailing conditions in this region. The eastern coast of the Adriatic Sea is exposed to the strong winds blowing during the colder part of the year: the bora (northeast wind) and the jugo (southeast wind). Due to the orientation of the Adriatic Sea and analyzed sea channels, the jugo usually generates larger waves than the bora thus endangering maritime transport. However, navigating in strong bora conditions poses different risks due to its typically turbulent nature and strong intensity.

With these considerations in mind, unfavorable navigation conditions are defined using three criteria: (i) wind strength reaching or exceeding Force 5 (Beaufort scale) and at least a moderate wave height, (ii) wind strength reaching or exceeding Force 8 regardless of the sea state, and (iii) the presence of thunderstorm conditions involving hail, thunder, and showers.

In the analysis, it is concluded that the number of days with unfavorable conditions decreases from January to June, as expected. The most unfavorable conditions are most likely to occur in January, while June proves to be the most suitable month for conducting work with an average of 5.7 days with unfavorable conditions. Throughout all considered months, there should be at least 10 days with favorable conditions. Moreover, in June of any year, the number of days with unfavorable conditions did not exceed 7.

How to cite: Kožul, E., Odak Plenković, I., and Muić, I.: Determining the frequency of unfavorable conditions for sailing in Adriatic Sea channels , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15746, https://doi.org/10.5194/egusphere-egu24-15746, 2024.

Various countries around the world have been experiencing coastal disasters caused by coastal flooding, and Korean Peninsula is no exception. Most coastal flooding occurs during extreme sea level conditions which is comprised astronomical tides, nontidal residuals, wind wave, and mean sea level. To respond to coastal flooding disasters, it is important to understand the characteristics of extreme sea levels. Therefore, this study analyzed the spatiotemporal patterns of extreme sea levels along the Korean Peninsula and evaluated the effects of the astronomical tides and nontidal residuals represented by storm surges on extreme sea levels among the components constituting extreme sea levels. At this time, when analyzing the impact of the storm surge, it was evaluated whether the storm surge was caused by tropical cyclones or extra-tropical cyclones, and what storm condition were more dangerous in the Korean Peninsula. This study collected observed tidal data from 1979 to 2021 at 48 tide stations which are installed along the coast of the KP and performed a hormonic analysis to distinguish them into astronomical and storm surge components. In this case, storm surges occurring in summer and winter were considered to be caused by tropical cyclones and continental cyclones, respectively. In addition, to more accurately analyze the regional characteristics, the Korea’s coast was divided in the three zones: the East Sea, the West Sea, and the South Sea. As a result of the study, it was found that the extreme sea levels along the Korean Peninsula showed regional differences, and in the case of the south coast, storm surges generated by tropical cyclones were the main drive of extreme sea levels.

How to cite: Yang, J.-A.: Spatio-temporal analysis of extreme sea level in the Korean Peninsula, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16044, https://doi.org/10.5194/egusphere-egu24-16044, 2024.

EGU24-17562 | ECS | Posters on site | ITS2.3/CL0.1.1

Drivers of compound drought-heat extremes across recent decades 

Josephin Kroll, Ruth Stephan, Harald Rieder, Jens Hesselbjerg Christensen, and Rene Orth

The joint occurrence of droughts and heat waves is expected to change with advancing climate change. While drought and heat themselves can already have major impacts on ecosystems and society, their compound occurrence can lead to amplified effects. Previous studies have analyzed changes in the occurrences frequency of compound drought-heat events and found increasing trends in some regions. In this study, we revisit these occurrence trends and additionally analyze the mechanisms that couple drought and heat as well as their changes in space and time. Considering drought as deficit of soil moisture and heat as an extreme temperature, evapotranspiration (ET) is the main physical process connecting both extremes. Therefore, we focus particularly on ET anomalies, because higher-than-normal ET during drought-heat events indicates that heat is inducing drought (heat → drought) as high temperatures lead to high vapor pressure deficit which increases ET that in turn depletes soil moisture. Vice versa, lower-than-normal ET suggests drought is triggering hot temperatures (drought → heat) as low soil moisture limits ET such that more of the incoming radiation is partitioned to sensible heat flux and hence warming the air. To better understand the underlying controls of these ET anomalies, we analyze their drivers by considering anomalies of precipitation, radiation, vapor pressure deficit and Leaf Area Index, which are in turn linked to anomalies in atmospheric circulation. Finally, we compare the relevance of these drivers, and of the drought → heat vs. heat → drought mechanisms in space, and link them with aridity and land cover type. In our analysis, we employ weekly data from the ERA5 reanalysis alongside gridded products derived with machine learning methods which were trained with in-situ observations. We define drought and heat with a percentile based approach filtering the lowest (< 5th percentile) absolute soil moisture values and highest (> 95th percentile) absolute temperatures at each grid cell. Understanding the mechanisms behind compound drought-heat extremes can help improve related forecasts, and to validate and constrain model projections of trends in these events. 

How to cite: Kroll, J., Stephan, R., Rieder, H., Hesselbjerg Christensen, J., and Orth, R.: Drivers of compound drought-heat extremes across recent decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17562, https://doi.org/10.5194/egusphere-egu24-17562, 2024.

EGU24-18239 | ECS | Posters on site | ITS2.3/CL0.1.1

Changes in extreme precipitation patterns over the Greater Antilles and teleconnection with large-scale sea surface temperature 

Carlo Destouches, Arona Diedhiou, Sandrine Anquetin, Benoit Hingray, Armand Pierre, Adermis Joseph, and Dominique Boisson

This study investigates the evolution of extreme precipitation over the Greater Antilles and its relationship with large-scale sea surface temperature (SST) during the period 1985-2015. The data used are derived from two satellite datasets, CHIRPS (Climate Hazards Group InfraRed Precipitation, Funk et al. (2015)) and NOAA (OI V2 Sea Surface Temperature, Huang et al. (2021)), at resolution of 5km and 25km respectively.  Changes in the characteristics of six indices of precipitation extremes (Precipitation total; number of rainy days;  contribution of heavy rainfall, R95p, maximum duration of consecutive rainy and dry days) defined by the WMO ETCCDI (World Meteorological Organization Expert Team on Climate Change Detection and Indices, Peterson et al. (2001)) are described and the influence of four large-scale SST indices (Northern Oscillation Index, NAO; Southern Oscillation Index, SOI; Tropical South Atlantic, TSA; Caribbean Sea Surface Temperature, SST-CAR) is investigated using Spearman's correlation coefficient. The results show that at regional scale, a positive phase of the TSA index contributes to an increase of the rainfall intensity while a positive phase of NAO is significantly associated with a decrease of total precipitation, of daily rainfall intensity, and of heavy rainfall. At country level, in southeastern Cuba and Puerto Rico, the increase in heavy precipitation and rainfall intensity is linked to a positive phase of the SOI, TSA and SST-CAR, while in Jamaica and northern Haiti, they are associated with positive phase of TSA and SST-CAR. Increases in the number of rainy days and the maximum duration of consecutive rainy days over the southern Haiti and the Dominican Republic are significantly associated with positive phase of the Southern Oscillation (SOI) and warming of SST over the east of the Caribbean Sea. The results of this study show that, in the Caribbean, particularly in the Greater Antilles, large-scale SST have had a strong influence on extreme precipitation over the past 30 years.

 

Keywords: Caribbean region; Greater Antilles; Extreme precipitation; Climate variability; Sea surface temperature

How to cite: Destouches, C., Diedhiou, A., Anquetin, S., Hingray, B., Pierre, A., Joseph, A., and Boisson, D.: Changes in extreme precipitation patterns over the Greater Antilles and teleconnection with large-scale sea surface temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18239, https://doi.org/10.5194/egusphere-egu24-18239, 2024.

EGU24-18528 | ECS | Orals | ITS2.3/CL0.1.1

Interconnections and decadal predictability of global hot, dry and compound hot-dry events 

Alvise Aranyossy, Markus Donat, Paolo Deluca, Carlos Delgado-Torres, and Balakrishnan Solaraju-Murali

We investigate the representation of compound hot-dry events in decadal predictions and their relationship with their univariate hot and dry components. We use a CMIP6 multi-model ensemble (MME) of 125 members from the Decadal Climate Prediction Project (DCPP) hindcast simulations and compare it with different observational references. Our analysis focuses on the first five lead years of the simulations, with the different ensemble members initialised every year from 1960 to 2014. We analyse the skill of predicting hot, dry and hot-dry events in the multi-model ensemble. Specifically, we select the days above the 90th percentile of the daily maximum temperature for hot events. For dry events, we use two indicators, the Standardised Precipitation Index (SPI) and the Standardised Precipitation Evapotranspiration Index (SPEI), with accumulation periods of 3, 6 and 12 months, and we consider a dry event a month that shows an SPI or an SPEI value ≤1. Finally, we identify days that present both hot and dry conditions according to these criteria as compound hot-dry days.

Preliminary results for the observations show a strong correlation between precipitation and the occurrence of compound events, especially for long accumulation periods, suggesting the importance of dryness as a driver for compound hot-dry events. In the DCPP hindcasts, the hot events show some robust predictive skill, mainly as a consequence of the increasing trend in temperature. On the other hand, dry events show sparse skill, concentrated in dry areas of the world and especially for extended accumulation periods. Further analysis of the skill of compound events and their relationship to their univariate counterparts in DCPP hindcasts will shed light on the representation of such events in decadal forecasts. However, these initial results underline the importance of precipitation in both the occurrence of present hot-dry compound events and the prediction of such events in the future.

How to cite: Aranyossy, A., Donat, M., Deluca, P., Delgado-Torres, C., and Solaraju-Murali, B.: Interconnections and decadal predictability of global hot, dry and compound hot-dry events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18528, https://doi.org/10.5194/egusphere-egu24-18528, 2024.

EGU24-18959 | Orals | ITS2.3/CL0.1.1

Bayesian Network Approach for Assessing Probability of Multi-Hazard Climate Driven Events 

Barry Evans, Albert Chen, Alex De La Cruz Coronas, Beniamino Russo, Agnese Turchi, Mattia Leone, and Marianne Büegelmayer

With the intensity and frequency of climate driven disasters increasing as result of climate change, there is ever more need to plan for such events and develop means to mitigate against them (UNDRR, 2015). Traditionally, the assessment of risks and impacts to regions posed by climate extreme events have been carried out in a “one at a time” approach, where the effects of each hazard, are assessed individually (Russo et al., 2023). However, it is recognised that  a transition to a more multi-hazard and multisectoral approach  is needed to be more efficient and effective in mitigating the risks/impacts posed to society, infrastructures, or the environment (Sendai Framework, 2015), (Russo et al. 2023). Whilst risk/impact assessment modelling can be complex, the derivation of risk/impacts is complicated further within a multi-hazard assessment due to the interdependent relationships between hazard, exposure and vulnerability, and that these vary over time in response to a preceding hazard (Gill et al. 2021).

The European Funded ICARIA project seeks to create an asset level modelling framework for understanding the potential risks/impacts posed by multi-hazard climate driven hazards, whilst also providing insight into cost-effective means of mitigating against them through the application of suitable adaptation measures. Two of the key challenges when transitioning from a single to a multi-hazard modelling approach are that (1) hazards are not directly comparable due differences in their processes and metrics, and (2) the effects of one hazard can influence the behaviour/characteristics of another hazard (Forzieri et al., 2016). To simulate the potential risks/impacts that could result from the modelled range of compound and consecutive hazards, a two-stage approach is being adopted that consists of (1) a deterministic physical modelling approach for quantifying the risks/impacts that can arise through simulation of various compound and consecutive hazard scenarios, along with (2) a stochastic Bayesian Network (BN) method for defining the probability distribution of such events. The BN will consider historical data for defining the probability distribution of modelled, multi-hazard scenarios for both current and future scenarios whilst data from the physical modelling will be used for defining the distribution of parameters relating to exposure, vulnerability, and impacts for the business as usual (no adaptation) and future adaptation scenarios.

 

Acknowledgement

The ICARIA project (Improving Climate Resilience of Critical Assets) is funded by the European Commission through the Horizon Europe Programme, grant number 101093806. https://cordis.europa.eu/project/id/101093806.

 

References

Forzieri, G., Feyen, L., Russo, S., Vousdoukas, M., Alfieri, L., Outten, S., Migliavacca, M., Bianchi, A., Rojas, R., & Cid, A. (2016). Multi-hazard assessment in Europe under climate change. Climatic Change, 137(1), 105–119. https://doi.org/10.1007/s10584-016-1661-x

Gill, J. C., Hussain, E., & Malamud, B. D. (2021). Workshop Report: Multi-Hazard Risk Scenarios for Tomorrow’s Cities.

Russo, B., de la Cruz Coronas, À., Leone, M., Evans, B., Brito, R. S., Havlik, D., Bügelmayer-Blaschek, M., Pacheco, D., & Sfetsos, A. (2023). Improving Climate Resilience of Critical Assets: The ICARIA Project. Sustainability, 15(19). https://doi.org/10.3390/su151914090

“United Nations - Headquarters United Nations Office for Disaster Risk Reduction.” (2015). Sendai Framework for Disaster Risk Reduction 2015-2030.

How to cite: Evans, B., Chen, A., De La Cruz Coronas, A., Russo, B., Turchi, A., Leone, M., and Büegelmayer, M.: Bayesian Network Approach for Assessing Probability of Multi-Hazard Climate Driven Events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18959, https://doi.org/10.5194/egusphere-egu24-18959, 2024.

EGU24-20174 | ECS | Orals | ITS2.3/CL0.1.1

Extreme and compounding events in Pakistan 

aamir imran

Globally, climate change is a vital issue which exacerbates many severe consequences and causes the increasing frequency and severity of extreme weather events. Extreme climatic events, such as flash flooding, heatwaves, and droughts, pose severe impacts on societies and ecosystems, due to their large spatial coverage and high intensity. These extreme climatic events often occur simultaneously or sequentially as so-called compound events (CEs), causing high economic and societal losses as compared to the losses due to individual climatic extreme events. In the last two decades, Pakistan was ranked among the top ten countries which are most vulnerable to climate change and disasters, such as intense flooding, extreme heat, and droughts, among others. This paper presents case studies of extreme and compounding events in the last two decades with severe devastating impacts on people, infrastructure, and ecosystems. Specifically, two worst-case studies have been focused such as a flood in 2010 followed by a drought and a flood in 2022 followed by the heatwave. The post-disaster analysis shows that major part of the country was severely affected by these two CEs as a result of damaging the standing crops, destroying land, and causing displacement of millions of people along with losses and damages in fatalities and monetary terms. Therefore, this study is very vital for decision-making authorities to perceive the expected risk for human life, environment, and infrastructure in the future. So that pre and post-disaster mitigation policies and strategies could be formulated at local and national levels. The paper concludes with a discussion of the implications for CE adaptation in Pakistan. Key recommendations are provided to mitigate the impacts of future CEs.

How to cite: imran, A.: Extreme and compounding events in Pakistan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20174, https://doi.org/10.5194/egusphere-egu24-20174, 2024.

EGU24-20589 | ECS | Posters virtual | ITS2.3/CL0.1.1

On the use of probabilistic network models to assess spatially compound events in a warmer world 

Catharina Elisabeth Graafland, Ana Casanueva, Rodrigo Manzanas, and José Manuel Gutierrez

Probabilistic network models (PNMs) have established themselves as a data-driven modeling and machine learning prediction technique utilized across various disciplines, including climate analysis. Learning algorithms efficiently extract the underlying spatial dependency structure in a graph and a consistent probabilistic model from data (e.g. gridded reanalysis or climate model outputs for particular variables). The graph and probabilistic model together constitute a truly probabilistic backbone of the system underlying the data. The complex dependency structure between the variables in the dataset is encoded using both pairwise and conditional dependencies and can be explored and characterized using network and probabilistic metrics. When applied to climate data, PNMs have been demonstrated to faithfully uncover the various long‐range teleconnections relevant in temperature datasets, in particular those emerging in El Niño periods (Graafland, 2020).

The combination of multiple climate drivers and/or hazards that contribute to societal or environmental risk are the so-called compound weather and climate events. These compound events can be the result of a combination of factors over different dimensions: temporal, spatial, multi-variable, etc. (Zscheischler et al. 2020). In particular, spatially compound events take place when hazards in multiple connected locations cause an aggregated impact. In this work we apply PNMs to extract and characterize most essential spatial dependencies of compound events resulting from concurrent temperature and precipitation hazards, either in the same location or spatially connected, which can be relevant for agriculture. Furthermore, PNMs are used to propagate evidence of different levels of observed and projected global warming to assess the possible evolution of compound events in a changing climate.

References

Graafland, C.E., Gutiérrez, J.M., López, J.M. et al. The probabilistic backbone of data-driven complex networks: an example in climate. Sci Rep 10, 11484 (2020). DOI: 10.1038/s41598-020-67970-y

Zscheischler, J., Martius, O., Westra, S. et al.  (2020). A typology of compound weather and climate events. Nat Rev Earth Environ 1, 333–347, doi: 10.1038/s43017-020-0060-z.

Acknowledgement

This work is part of Project COMPOUND (TED2021-131334A-I00) funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR. 



How to cite: Graafland, C. E., Casanueva, A., Manzanas, R., and Gutierrez, J. M.: On the use of probabilistic network models to assess spatially compound events in a warmer world, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20589, https://doi.org/10.5194/egusphere-egu24-20589, 2024.

EGU24-20600 | ECS | Orals | ITS2.3/CL0.1.1

Assessing Multidimensional Climate Extremes and Associated Vulnerabilities Across the United States  

Saurav Bhattarai, Sanjib Sharma, and Rocky Talchabhadel

Climate change is intensifying the occurrence of various extreme weather events across different geographic regions. While most research tends to concentrate on individual extremes, such as heatwaves, droughts, or floods, there’s been minimal exploration into how multiple, diverse extremes interact and compound impact social vulnerability. This study analyzes the overlapping spatial and temporal impact of temperature, precipitation, and hydroclimatic extremes across the US in the context of climate change.

 

Using data and predictions from global and regional climate models for present (including historical) and future emissions scenarios, we compute several indices of different extremes related to heatwaves, floods, and droughts. The aim is to categorize regions, or states or counties, based on their exposure to simultaneous extremes, incorporating social vulnerability and socioeconomic factors. The combination of exposure to multiple hazards and social vulnerability reveals regions in the US that face the highest risks from climate change.

 

Understanding the likelihood of compound climatic extremes occurring in areas with vulnerable populations can significantly aid in planning for adaptation and reducing the risk of disasters. By employing machine learning techniques to predict both multidimensional extremes and social vulnerability, policymakers can tailor evidence-based strategies to enhance community resilience. The methodology and findings provide a framework for evaluating multidimensional climate risks, applicable not just in the US but also in other countries and regions worldwide.



How to cite: Bhattarai, S., Sharma, S., and Talchabhadel, R.: Assessing Multidimensional Climate Extremes and Associated Vulnerabilities Across the United States , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20600, https://doi.org/10.5194/egusphere-egu24-20600, 2024.

EGU24-2668 | ECS | Posters virtual | ITS2.1/CL0.1.2

Hominin response to oscillations in climate and local environments during the Mid-Pleistocene Climate Transition in northern China 

Zhe Wang, Bin Zhou, Xiangchun Xu, Yang Pang, Michael Bird, Bin Wang, Michael Meadows, and David Taylor

Long-term climate trends superimposed on climate variability changes are recognized to manipulate the living environments, and ultimately ecological resources for hominins, which in turn affect hominin activities. Archaeological evidence from loess sediments from Shangchen on the southeastern Chinese Loess Plateau indicates a suspension of hominin occupation around the time of the early mid-Pleistocene climate transition (MPT), prompting a re-assessment of climate-vegetation-hominin interactions. Our research generated magnetic susceptibility, total organic carbon cotent and its carbon isotope compositions, black carbon content and brGDGTs-derived mean annual temperatue and precipitation records in loess deposits with in situ lithic records covering the period of hominin occupation (~2.1–0.6 Ma). The results reveal four distinct climate-vegetation periods (2.1–1.8 Ma, 1.8–1.26 Ma, 1.26–0.9 Ma and 0.9–0.6 Ma). During the early MPT (1.26–0.9 Ma), unprecendently high variability in climate-environment and a long-term aridification with C4 vegetation expansion trend may have driven early humans to move to more hospitable locations in the region. Comparison with the record at Nihewan indicates that large-scale climate oscillations induced disparate hominin responses due to distinctive local environmental conditions.

How to cite: Wang, Z., Zhou, B., Xu, X., Pang, Y., Bird, M., Wang, B., Meadows, M., and Taylor, D.: Hominin response to oscillations in climate and local environments during the Mid-Pleistocene Climate Transition in northern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2668, https://doi.org/10.5194/egusphere-egu24-2668, 2024.

Community assembly principles driving microbial biogeography have been studied in many environments, but rarely in the Arctic deep biosphere. The sea-level rise during the Holocene (11–0 ky BP) and its resulting sedimentation and biogeochemical processes can control microbial life in the Arctic sediments. We investigated subsurface sediments from the Arctic Ocean using metabarcoding-based sequencing to characterize bacterial 16S rRNA gene composition, respectively. We found enriched cyanobacterial sequences in methanogenic sediments, suggesting past cyanobacterial blooms in the Arctic Mid-Holocene (7–8 ky BP). Bacterial assemblage profiles with a sedimentary history of Holocene sea-level rise in the Arctic Ocean enabled a better understanding of the ecological processes governing community assembly across Holocene sedimentary habitats. The Arctic subsurface sediments deposited during the Holocene harbour distinguishable bacterial communities reflecting geochemical and paleoclimate separations. These local bacterial communities were phylogenetically influenced by interactions between biotic (symbiosis–competition or immigration–emigration) and abiotic (habitat specificity) factors governing community assembly under paleoclimate conditions. We conclude that bacterial profiles integrated with geological records seem useful for tracking microbial habitat preference, which reflects climate-triggered changes from the paleodepositional environment (the so-called ‘ancient DNAs’).

How to cite: Dukki, H. and Seung-Il, N.: Ancient DNAs: Influence of Sedimentary Deposition on Bacterial Communities in Arctic Holocene Sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2955, https://doi.org/10.5194/egusphere-egu24-2955, 2024.

EGU24-4247 | ECS | Posters on site | ITS2.1/CL0.1.2

Modeling and future prediction of spring phenology in grassland on the Qinghai-Tibetan Plateau 

Lei Wang, Xinyi Zhao, Haobo Yin, and Guoying Zhu

The Qinghai-Tibet Plateau (QTP) is an important ecological barrier in China and even East Asia, and its main vegetation cover type is grassland. With the global climate change, the phenological period of grassland on the QTP is constantly changing, which affects the climate and ecosystem through carbon cycle, hydrothermal cycle, etc. The influencing factors of phenology and its future change trend have become the key issues. In this paper, the spring phenological model of the QTP grassland was constructed by using the start of growing season (SOS) extracted from MODIS NDVI, air temperature and soil moisture data from 2000 to 2020. Combined with CMIP6 climate data, the future phenological changes of the QTP grassland under the SSP245 scenario were predicted. The results showed that: (1) The cumulative temperature and cumulative soil water threshold model was effective in simulating spring phenology of grassland on the QTP, and the root-mean-square error was only about 8 days. (2) The climatic thresholds at SOS of different vegetation types are closely related to their spatial distribution locations. Vegetation growth in the eastern and southern parts of the QTP requires higher hydrothermal conditions. (3) The QTP showed an overall warming and wetting trend in the future, with greater changes in the first half of the 21st century than those in the second half of the 21st century. (4) The advance of SOS in the northwest grassland was significantly higher than that in the southeast grassland. By the end of the 21st century, most grasslands on the QTP began to grow before mid-June.

How to cite: Wang, L., Zhao, X., Yin, H., and Zhu, G.: Modeling and future prediction of spring phenology in grassland on the Qinghai-Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4247, https://doi.org/10.5194/egusphere-egu24-4247, 2024.

EGU24-4791 * | Orals | ITS2.1/CL0.1.2 | Highlight

Climate, culture and population size 

Axel Timmermann, Abdul Wasay, Pasquale Raia, and Jiaoyang Ruan

Human history is full of examples documenting that cultural innovations played a key role in reducing the impact of environmental stress on early populations. Over the past 1 million years this type of adaptation (e.g., clothing, shelter, hunting techniques, social behaviour) likely also increased human population size. Humans are cumulative cultural learners, who can integrate knowledge and culture from one generation to the next. The larger the number of interacting people, the faster the rate of innovation.  Here we introduce a stochastic consumer-resource modeling framework, that simulates the dynamics of cultural transmission, learning, and innovation, population size, and resource depletion in a changing environment. Culture is introduced as a booster to carrying capacity. A zero-dimensional version of the model simulates nonlinear phase-synchronization between culture, population and external climate forcings. We will also present the first results of the model in 2 dimensions with full global resolution and 3 interacting hominin species to assess which role differences in cultural innovation played in the extinction of Neanderthals and Denisovans.

 

 

How to cite: Timmermann, A., Wasay, A., Raia, P., and Ruan, J.: Climate, culture and population size, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4791, https://doi.org/10.5194/egusphere-egu24-4791, 2024.

EGU24-5928 | Posters on site | ITS2.1/CL0.1.2

Snapshots of Ireland’s Holocene climate and fauna from stalagmites 

Claire Ansberque, Anna Linderholm, Chris Mark, Malin Kylander, and Frank McDermott

Stalagmites are well-known as paleoclimatic archives, but recent work [e.g., 1,2] has also demonstrated their paleobiological potential as archives of ancient animal and plant DNA. Because of this property, stalagmites have the potential to provide information on how past climatic fluctuations have impacted land fauna, specifically cave fauna of which bats are key ecosystem services providers. The aim of this work is to use stalagmites to gain precisely such knowledge. With this endeavour, we acquired geochemical data (Sr/Ca, δ18O, δ13C) along the growth axis of three early Holocene stalagmites from Ireland, which we used for climatic and environmental reconstruction. In addition, we acquired ancient DNA data in stalagmite laminae, including those where climatic and environmental shifts were observed. Results of these analyses are presented here and include new U-Th-dated stable isotopic curves and ancient DNA data chronologically anchored to stalagmite-derived climatic records. We also discuss our analytical workflow and the pros and cons we faced while combining geological and biological data on stalagmites such as data acquisition resolution, stalagmite chemistry, and DNA data quality.

[1] Stahlschmidt et al. (2019) Scientific Reports, 9, 6628. [2] Marchesini et al. (2023) Quaternary Research, 112, 180-188

How to cite: Ansberque, C., Linderholm, A., Mark, C., Kylander, M., and McDermott, F.: Snapshots of Ireland’s Holocene climate and fauna from stalagmites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5928, https://doi.org/10.5194/egusphere-egu24-5928, 2024.

EGU24-6756 | ECS | Posters on site | ITS2.1/CL0.1.2

Assessing Model Relevance: Agroclimatic Indices Across Different CORDEX Domains for Enhanced Climate Projections in the Houceima-Tanger-Tétouan Region 

Meryem Qacami, Marc-André Bourgault, Mohamed Chikhaoui, Thierry Badard, Mélanie Trudel, and Bhiry Najat

Understanding the intricacies of climate behavior is paramount for regions like Houceima-Tanger-Tétouan, where agroclimatic phenomena directly influence socio-economic stability. This study rigorously evaluates the performance of climate models against the ERA5-Land reanalysis data, focusing on two pivotal agroclimatic indices: dry spell and heat wave frequencies. Such indices are integral for regional drought risk management, agricultural planning, and environmental policy formulation.

Our approach integrates a dual comparison framework—comparing model outputs against each other (inter-model) and against multiple runs of the same model (intra-model). We also validate the ERA5-Land data against 16 years of in-situ measurements to confirm its aptitude as a benchmark dataset, particularly examining its representation of temperature and precipitation.

Findings indicate a strong temperature data correlation with in-situ measurements, affirming the ERA5-Land's reliability for temperature-related indices. However, precipitation data showed considerable variability, necessitating cautious application and potential model adjustments. Among the models, the MOHC-HadGEM2-ES demonstrated notable accuracy in dry spell predictions for selected domains, while the MPI-M-MPI-ESM-MR model stood out for its heat wave frequency projections, especially in the EUR-44 domain.

Our results pave the way for selecting the most appropriate models for regional climate projections. They also highlight the necessity of model calibration, especially for precipitation indices, to ensure the precision of climate-related predictions. The study contributes to the field by providing a clear pathway for the utilization of tailored climate models in developing robust adaptive strategies to climate variability in the Houceima-Tanger-Tétouan region.

How to cite: Qacami, M., Bourgault, M.-A., Chikhaoui, M., Badard, T., Trudel, M., and Najat, B.: Assessing Model Relevance: Agroclimatic Indices Across Different CORDEX Domains for Enhanced Climate Projections in the Houceima-Tanger-Tétouan Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6756, https://doi.org/10.5194/egusphere-egu24-6756, 2024.

EGU24-6896 | ECS | Orals | ITS2.1/CL0.1.2

Climatic and ecological responses to medium-sized asteroid collision 

Lan Dai and Axel Timmermann

There is a chance of 1 in 2,700 that asteroid Bennu will hit Earth in 2182 CE. The collision of such medium-sized asteroids (~0.3-1 km in diameter) with our planet can inject massive amounts of dust into the atmosphere, with unknown consequences for terrestrial and marine ecosystems. Here, we use the coupled high-top Community Earth System Model Version 2 (CESM2) with interactive chemistry to investigate how medium-sized asteroid strikes would impact climate, vegetation, and marine productivity. Our idealized simulations show that globally dispersed dust layers of up to 400 Tg in mass block shortwave radiation to the surface for nearly two years, resulting in rapid global cooling and delayed weakening of the hydrological cycle for up to four years after the impact. The combined effects of reduced sunlight, cold temperature, and decreased precipitation significantly inhibit photosynthesis in the terrestrial ecosystem for almost nineteen months. Marine phytoplankton production decreases moderately within five months due to reduced sunlight. Subsequently, however, and depending on the iron amount of the asteroid, large diatom blooms occur over the eastern equatorial Pacific and Southern Ocean due to iron fertilization from strong upwelling and dust deposition, respectively.

How to cite: Dai, L. and Timmermann, A.: Climatic and ecological responses to medium-sized asteroid collision, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6896, https://doi.org/10.5194/egusphere-egu24-6896, 2024.

EGU24-9488 | ECS | Posters virtual | ITS2.1/CL0.1.2

Enhancing Climate Resilience in IoT Devices: Challenges, innovations, and best practices.  

Dinara Zhunissova, Professor David Topping, and Professor James Evans

With growing concern about climate change and the increasing importance of Internet of Things (IoT) devices, the interaction between these two topics has been a focus of increased research. The purpose of this research paper, "Enhancing Climate Change Resilience in IoT Devices: Qualitative Analysis of Problems, Innovations, and Best Practises of IoT Devices," is to conduct a comprehensive qualitative analysis of the relation between IoT technology and climate resilience. This paper details the findings, providing contribution to the departments by offering solutions and recommendations that organisations can consider for improving the resilience of IoT devices in a severe weather condition. The paper includes an in-depth analysis of the present condition of IoT device usage, showing the broad and diverse areas of their application in many sectors, such as smart infrastructure, industrial manufacturing, agriculture, healthcare and more. This analysis highlights that many companies in both, the public and private sectors, are using sensors, actuators, cameras, routers and other devices. It then conducts a qualitative analysis of the particular problems that these devices deal with when subjected to challenging climatic conditions, with a focus on the impact of the environment on their performance. The paper illustrates IoT devices that have shown great climate resilience through real-world examples and in-depth qualitative evaluations of effective situations, delivering useful quality lessons for both developers and consumers. Furthermore, the study conducts a qualitative analysis of the elements that manufacturers and developers should consider while developing climate resistant IoT devices.

The evaluation of the importance of quality aspects, such as standards and certifications, in assuring the reliability of IoT devices in various climatic situations is a key aspect of this qualitative study. The paper conducts deep research of these parameters and their influence on device performance, it also emphasises the significance of subjective components of maintenance and protection practises, providing organisations with practical qualitative to overcome severe weather conditions and secure their IoT devices. By looking more closely at these factors, the study aims to find the deeper fundamental factors that affect how resilient and durable devices are. Bringing up the importance of qualitative aspects of maintenance and protection practises shows how important it is to think about not only technological aspects but also subjective features that make IoT devices more durable and make sure they work well even in extreme weather conditions. Over this research, comprehensive interviews with IT professionals from a variety of companies were used to gather data for this study. Open-ended questions were used to get rich and detailed insights. Along with the descriptive information, reports from the sector, case studies, and best practises were also analysed analytically. This created a complete narrative framework for learning about the problems and chances that come with those devices that are resilient to climate change. Besides that, includes qualitative analysis of predicted quality improvements and IoT device applications, taking into consideration changing climatic challenges and technology developments. Remote tracking and predictive maintenance are critical for maintaining the reliability and resilience of IoT devices.  

 

How to cite: Zhunissova, D., Topping, P. D., and Evans, P. J.: Enhancing Climate Resilience in IoT Devices: Challenges, innovations, and best practices. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9488, https://doi.org/10.5194/egusphere-egu24-9488, 2024.

EGU24-10113 | ECS | Posters on site | ITS2.1/CL0.1.2

Microbial evidences of abrupt shifts in dunes ecosystems after passing an aridity threshold 

Shuai Wu, Manuel Delgado-Baquerizo, and Aidong Ruan

Dune ecosystems are among the most vulnerable regions to climate change worldwide. However, studies on how crossing critical aridity thresholds influence the microbiome of these ecosystems remains scarce. These microbes play a pivotal role in shaping terrestrial ecosystem traits and functions.

In this study, we collected 1.4-meter sediment cores at 5 cm intervals from deserts in Xinjiang, China, in two study sites before and after crossing a previously described aridity threshold. We conducted a comprehensive analysis of community diversity and spatial structure, in light of the changes in environmental heterogeneity and autocorrelation, further exploring the community’s differential sensitivity to fluctuations and evidence of state transitions under various states.

The results demonstrate that microbial communities in sand dunes before and after crossing aridity thresholds exhibit distinct vertical ecological niche differentiation patterns under spatial effects. This includes variations in their beta diversity, rarity mode, assembly process, topological properties, and the stability of their networks. This offers new insights into the possible evidence of microbial community state transitions and potential mechanisms in deserts crossing aridity thresholds.

How to cite: Wu, S., Delgado-Baquerizo, M., and Ruan, A.: Microbial evidences of abrupt shifts in dunes ecosystems after passing an aridity threshold, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10113, https://doi.org/10.5194/egusphere-egu24-10113, 2024.

Climate variations during the last glacial period had major impacts on plant and animal populations including humans. Yet, relationships between human population levels and climate through time and across space remain elusive. Here, we used the archaeological radiocarbon dates spanning 50 to 10 ka BP in China to indicate fluctuations in human population sizes, and investigated their correlations with climate variables from paleoclimate proxies and climate model outputs using a Bayesian radiocarbon‐dated event count (REC) statistical model. We find that temperature has a significant positive effect on population in China during 50 – 10 ka, while the sensitivity of population size to temperature exhibits a declining trend over time, suggesting a potential gradual adaptation to cold climates. We further used a global ecosystem model that explicitly simulates human population dynamics, the ORCHIDEE-FOEGE model, to reconstruct human densities during the LGM, and investigated the roles of climate and atmospheric CO2 levels in shaping the distribution of human populations in China.

How to cite: Zhu, D., Lin, Z., and Zhou, J.: Spatiotemporal relationships between human population and climate during the last glacial period in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10236, https://doi.org/10.5194/egusphere-egu24-10236, 2024.

EGU24-12518 | ECS | Posters on site | ITS2.1/CL0.1.2

Strontium isotope turnover event mapped onto an elephant molar: implications for movement reconstructions 

Deming Yang, Katya Podkovyroff, Kevin Uno, Gabriel Bowen, Diego Fernandez, and Thure Cerling

Strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) of incrementally grown tissues have been used to study movement and migration of animals. Despite advances in characterizing ⁸⁷Sr/⁸⁶Sr turnover [1], the 2-D geometry of turnover in the tooth enamel is still poorly understood. The relocation of a zoo elephant (Loxodonta africana) named Misha provided an exceptional case study for understanding this pattern [1]. We documented the ⁸⁷Sr/⁸⁶Sr turnover in Misha’s molar using high-resolution in situ measurements with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

We prepared a longitudinally-cut thick section from Misha’s molar plate for LA-ICP-MS analysis. Within the tooth enamel, we measured 10 LA-ICP-MS transects parallel to the enamel dentine junction (EDJ), to map the 2-D pattern of ⁸⁷Sr/⁸⁶Sr turnover. Within the dentine, we measured a transect adjacent to the EDJ to document the unattenuated ⁸⁷Sr/⁸⁶Sr turnover sequence. We also analyzed conventionally drilled enamel samples from the same molar plate using the solution method for ⁸⁷Sr/⁸⁶Sr to document any turnover signal attenuation.

Molar dentine data are consistent with the published Sr turnover pattern in Misha’s tusk dentine. The inner half of the molar enamel preserves the turnover features in high fidelity, with a 2-D turnover geometry closely following that of enamel apposition. By contrast, the middle to outer surface of the enamel shows progressively more elevated ⁸⁷Sr/⁸⁶Sr values than those of the dentine. Data from drilled enamel samples show an attenuated turnover pattern due to averaging during drilling, as well as more elevated ⁸⁷Sr/⁸⁶Sr. We attribute these elevated Sr ratios to post-relocation Sr overprinting primarily on the outer enamel surface during enamel maturation.

Our results suggest that in situ LA-ICP-MS analysis of the inner half of enamel best recovers the time scale and magnitude of the ⁸⁷Sr/⁸⁶Sr turnover in an elephant molar. By contrast, the attenuated and overprinted turnover sequence from conventionally drilled enamel samples may lead to biased interpretations of the timing and geospatial scale of the animal’s movement history. To properly interpret conventionally drilled enamel sequences, future work would benefit from a modeling framework that can account for attenuation, overprint, and turnover of Sr, to quantitatively reconstruct movement or life history of extant and extinct animals. 

References:

[1] Yang, D.Bowen, G. J.Uno, K. T.Podkovyroff, K.Carpenter, N. A.Fernandez, D. P., & Cerling, T. E. (2023). BITS: A Bayesian Isotope Turnover and Sampling model for strontium isotopes in proboscideans and its potential utility in movement ecologyMethods in Ecology and Evolution1428002813. https://doi.org/10.1111/2041-210X.14218

How to cite: Yang, D., Podkovyroff, K., Uno, K., Bowen, G., Fernandez, D., and Cerling, T.: Strontium isotope turnover event mapped onto an elephant molar: implications for movement reconstructions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12518, https://doi.org/10.5194/egusphere-egu24-12518, 2024.

EGU24-12629 | ECS | Posters on site | ITS2.1/CL0.1.2

The impact of protected areas on biodiversity conservation under different climate and land use change projections 

Chantal Hari, Markus Fischer, and Édouard Davin

Increasing conservation efforts are required to avert biodiversity decline caused by climate and land use changes.

In a recent study (Hari et al. in prep), we combined climate change scenarios (RCP2.6 and RCP6.0) and land use change projections to assess their impact on future species distribution for a large number of mammals, birds and amphibians. Future projections of land use change were derived from the Land Use Harmonization dataset v2 (LUH2), which does not make any explicit assumptions about the area under protection in these scenarios.

Here, we extend the scope of our future biodiversity projections by adding new land use scenarios explicitly accounting for different “Nature Futures” in the sense of different levels of biodiversity conservation (i.e., current protected areas or 30x30 target). In the first conservation scenario, we fix the protected areas based on the World Database on Protected Areas (WDPA), thereby assuming that protected areas will remain the same in the future as it is today. In a second category of scenarios, we create land use scenarios compatible with the Global Biodiversity Framework’s “30x30” target based on the spatially optimized dataset by Jung et al. (2021) combined with LUH2.

We then quantify how incorporating different levels of protected areas for conservation change the future species richness based on our land use filtering approach. We also analyze how these two scenarios of land management for conservation interfere with different levels of global warming and what are the implications for the climate resilience of different biodiversity conservation choices.

How to cite: Hari, C., Fischer, M., and Davin, É.: The impact of protected areas on biodiversity conservation under different climate and land use change projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12629, https://doi.org/10.5194/egusphere-egu24-12629, 2024.

EGU24-13260 | ECS | Orals | ITS2.1/CL0.1.2 | Highlight

Human adaptation to diverse biomes over the past 3 million years 

Elke Zeller, Axel Timmermann, Kyung-Sook Yun, Pasquale Raia, Karl Stein, and Jiaoyang Ruan

We identify past human habitat preferences over time to investigate the role of vegetation and ecosystem diversity on hominin adaptation and migration. Using a transient 3-million-year earth system-biome model simulation and an extensive hominin fossil and archaeological database we distinguish in what habitat previous Hominin lived. Our analysis shows that early African hominins predominantly lived in open environments such as grassland and dry shrubland. Hominins adapted to a broader range of biomes by migrating into Eurasia. By linking the location and age of hominin sites with corresponding simulated regional biomes, we also find a preference for spatially diverse environments. Suggesting our ancestors actively sought out mosaic landscapes.

How to cite: Zeller, E., Timmermann, A., Yun, K.-S., Raia, P., Stein, K., and Ruan, J.: Human adaptation to diverse biomes over the past 3 million years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13260, https://doi.org/10.5194/egusphere-egu24-13260, 2024.

EGU24-14207 | Orals | ITS2.1/CL0.1.2 | Highlight

Decoding Cryptic Population Structures using Stable Isotope Markers 

Gabriel Bowen, Kyle Brennan, Sean Brennan, and Timothy Cline

Life-history diversity has been shown to contribute to the resilience of species but can be challenging to quantify, particularly where intra-population genetic structure is lacking. Such is the case for salmon within many fisheries of the North American Pacific Northwest, where the resolution of genetic markers is variable and limited. For Sockeye salmon (Oncorhynchus nerka) within the U.S.-Canada transboundary Taku Watershed, for example, single-nucleotide polymorphisms have successfully distinguished populations associated with specific inland lakes but allocates many individuals to an undifferentiated “River Type” stock. The extent and dynamics of geographic structure within this stock, and thus its potential contribution to the fishery’s resilience, remain unresolved.

In such cases, intrinsic non-genetic markers that record key aspects of life history, such as the isotope ratios of body tissues, can provide valuable information on population structure and diversity. We combined a recently published stream network model for strontium stable isotopes (87Sr/86Sr) with otolith (ear stone) microchemistry data to infer the geographic natal origins of 45 adult fish captured during the 2019 run. Our analysis was implemented in a Bayesian framework and leveraged radio tag data as a source of prior information. We distinguish 4 previously undifferentiated sub-populations within the River Type stock, characterized by groups of fish with distinct natal 87Sr/86Sr values and, by inference, natal habitat locations. Although data from additional years will be needed to assess the persistence of these patterns, the result implies potential for previously unrecognized geographic structure within the River Type stock as a contributor to resilience within the population. The lack of genetic differentiation among the subpopulations may suggest that plasticity of habitat use is prevalent and contributes to adaptation. Alternatively, individuals may exhibit strong site fidelity, but differentiation of these sub-populations may be relatively recent or obscured by gene flow. Distinction between these hypotheses should be resolvable by applying the Sr-isotope method to fish recovered across multiple years.

How to cite: Bowen, G., Brennan, K., Brennan, S., and Cline, T.: Decoding Cryptic Population Structures using Stable Isotope Markers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14207, https://doi.org/10.5194/egusphere-egu24-14207, 2024.

EGU24-14448 | Posters on site | ITS2.1/CL0.1.2

Concurrent Asian monsoon strengthening and early modern human dispersal to East Asia during the last interglacial 

Jiaoyang Ruan, Hong Ao, María Martinón-Torrese, Mario Krapp, Diederik Liebrandh, Mark J. Dekkers, Thibaut Caley, Tara N. Jonell, Zongmin Zhu, Chunju Huang, Xinxia Li, Ziyun Zhang, Qiang Sun, Pingguo Yang, Jiali Jiang, Xinzhou Li, Yougui Song, Xiaoke Qiang, Peng Zhang, and Zhisheng An

The relationship between initial Homo sapiens dispersal from Africa to East Asia and the orbitally paced evolution of the Asian summer monsoon (ASM)—currently the largest monsoon system—remains underexplored due to lack of coordinated synthesis of both Asianpaleoanthropological and paleoclimatic data. Here, we investigate orbital-scale ASM dynamics during the last 280 thousand years (kyr) and their likely influences on early H. sapiens dispersal to East Asia, through a unique integration of i) new centennial-resolution ASM records from the Chinese Loess Plateau, ii) model-basedEast Asian hydroclimatic reconstructions, iii) paleoanthropological data compilations, and iv) global H. sapiens habitat suitability simulations. Our combined proxy- and model-based reconstructions suggest that ASM precipitation responded to a combination of Northern Hemisphere ice volume, greenhouse gas, and regional summer insolation forcing, with cooccurring primary orbital cycles of ~100-kyr,41-kyr, and ~20-kyr. Between ~125 and 70 kyr ago, summer monsoon rains and temperatures increased in vast areas across Asia. This episode coincides with the earliest H. sapiens fossil occurrence at multiple localities in East Asia. Following the transcontinental increase in simulated habitat suitability, we suggest that ASM strengthening together with Southeast African climate deterioration may have promoted the initial H. sapiens dispersal from their African homeland to remote East Asia during the last interglacial.

How to cite: Ruan, J., Ao, H., Martinón-Torrese, M., Krapp, M., Liebrandh, D., Dekkers, M. J., Caley, T., Jonell, T. N., Zhu, Z., Huang, C., Li, X., Zhang, Z., Sun, Q., Yang, P., Jiang, J., Li, X., Song, Y., Qiang, X., Zhang, P., and An, Z.: Concurrent Asian monsoon strengthening and early modern human dispersal to East Asia during the last interglacial, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14448, https://doi.org/10.5194/egusphere-egu24-14448, 2024.

EGU24-18466 | Orals | ITS2.1/CL0.1.2

Using long-term remote sensing series to upscale the vegetation shifts along elevation in the GLORIA network Italian peaks 

Marco Vuerich, Francesco Boscutti, Davide Mosanghini, and Giacomo Trotta and the GLORIA Italian Network team

Plant species and communities’ distribution are remarkably affected by the climate change, particularly in arctic and alpine biomes. In alpine ecosystems, species and communities are shifting upwards due to the temperature increase, seeking for the optimum growth conditions. As a prominent effect, a progressive increase of vegetation cover is leading an alpine greening, with important consequences for the overall plant diversity. Nonetheless, little is known about how this trend may produce different effects along elevation gradients. Innovative upscaling approaches able to link field monitoring evidence to remote sensing data represent a promising tool to get new insights into the ecological mechanisms involved in these changes, and to produce reliable projections over time. This study aimed at parsing the long-term trends of remote sensing-derived vegetation indices in five GLORIA (Global Observation Research Initiative in Alpine Environments) network target regions, located across the Italian Alps and Apennines. Normalized Difference Vegetation Index (NDVI) was calculated for each growing season (June-September) in the period 1985-2022, using Landsat 5 and 8 multispectral satellite images of each mountain summit. Linear mixed-effects models were used to analyze the relationships between NDVI, time and climate variables, in different elevation belts. NDVI linearly increased over the last 37 years, but with significant higher increase rates and values at the treeline, lower alpine and alpine zones, compared to the upper alpine, subnival and nival belts. Moreover, NDVI was significantly affected by temperature at lower altitudes, with a significant interaction with rain precipitations, while climate variables were not determinant at high elevations. These results provided further evidence of the ongoing alpine greening and showed that vegetation at the treeline is responding faster than the other communities to a warmer and drier climate. Therefore, future scenarios depicting the fate of alpine plant community communities should not neglect for the interplay of temperature and precipitation regimes. Our finding opens future perspectives on the interpretation of GLORIA field evidence, in a continental upscaling perspective.

How to cite: Vuerich, M., Boscutti, F., Mosanghini, D., and Trotta, G. and the GLORIA Italian Network team: Using long-term remote sensing series to upscale the vegetation shifts along elevation in the GLORIA network Italian peaks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18466, https://doi.org/10.5194/egusphere-egu24-18466, 2024.

EGU24-18850 | ECS | Posters on site | ITS2.1/CL0.1.2

Testing the climate-niche paradigm for species extinction risk 

Claus Sarnighausen, Maximilian Kotz, Leonie Wenz, and Sanam Vardag

The increasing relevance of climate change as a threat of species extinction is a pressing concern, as highlighted by the recent IUCN Red List accessment for amphibians (Luedtke et al., 2023). Despite the reported threats of climate change, measuring its influence across species remains complex and lacking the appropiate tools (Cazalis et al., 2022). Changes in "climate niche", referring to the environmental conditions necessary for a species to thrive, have long been discussed and used to predict species distributions and extinctions. Here, we utilize the recently available Red List classifications to test this paradigm within state-of-the-art predictive models of comparative extinction risk. Using historical weather data from the ERA-5 reanalysis, we explore the predictive significance of a wide range of potential definitions of climate niche exceedance. Extinction risk models have consistently identified geographic range size and human population density as important correlates to extinction risk. Also controling for factors such as habitat fragmentation, land use, human preassures, biogeographical realms and biological traits, we use a random forest model to predict the transitions between Red List categories for over 5.000 amphibian species and evaluate results against the official accessments. This approach tests the evidence base of the climate niche paradigm and evaluates its effectiveness as a tool for incorporating climate change into extinction risk models.


Luedtke, J.A., Chanson, J., Neam, K. et al. Ongoing declines for the world’s amphibians in the face of emerging threats. Nature 622, 308–314 (2023). https://doi.org/10.1038/s41586-023-06578-4

Cazalis, V., Di Marco, M., Butchart, S. H. et al., Bridging the research-implementation gap in iucn red list assessments, Trends in Ecology & Evolution (2022).
https://doi.org/10.1016/j.tree.2021.12.002

How to cite: Sarnighausen, C., Kotz, M., Wenz, L., and Vardag, S.: Testing the climate-niche paradigm for species extinction risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18850, https://doi.org/10.5194/egusphere-egu24-18850, 2024.

EGU24-19008 | ECS | Orals | ITS2.1/CL0.1.2 | Highlight

Anthropogenic intensification of climate extremes has altered vertebrate species abundance 

Maximilian Kotz, Tatsuya Amano, James Watson, and Leonie Wenz

Assessments of the effects of climate change on terrestrial biodiversity typically rely on species distribution models [1] which neither exploit data on historical abundance changes nor consider the potentially important role of climate extremes. Here, we combine global data on the abundance of vertebrate species populations [2] with metrics of exposure to local climate conditions to demonstrate that historical warming and increased exposure to heat, heavy precipitation extremes and drought have had significant impacts on abundance, even after controlling for changing human pressures. Fixed-effects models reveal plausibly causal impacts which vary by species class and habitat system, as well as by latitude and the extent of human pressure. Results indicate that warming and intensified heat extremes have negative impacts at low latitudes for freshwater fish and terrestrial birds. By contrast, warming can bring benefits to freshwater birds and terrestrial mammals. Heavy precipitation extremes and drought appear to have had mainly negative impacts on abundance across species’ and habitats. We then combine these empirical results with estimates of the changes in climate conditions and extremes which are attributable to anthropogenic influence, using an established impact-attribution framework [3]. This approach reveals that anthropogenic climate change has caused considerable alterations to the abundance of terrestrial life, for example by reducing the abundance of terrestrial birds and freshwater fish by up to 40% at low latitudes.

 

[1] Thomas, Chris D., et al. "Extinction risk from climate change." Nature 427.6970 (2004): 145-148.

 

[2] Loh, Jonathan, et al. "The Living Planet Index: using species population time series to track trends in biodiversity." Philosophical Transactions of the Royal Society B: Biological Sciences 360.1454 (2005): 289-295.

 

[3] Mengel, Matthias, et al. "ATTRICI v1. 1–counterfactual climate for impact attribution." Geoscientific Model Development 14.8 (2021): 5269-5284.

How to cite: Kotz, M., Amano, T., Watson, J., and Wenz, L.: Anthropogenic intensification of climate extremes has altered vertebrate species abundance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19008, https://doi.org/10.5194/egusphere-egu24-19008, 2024.

EGU24-21192 | ECS | Orals | ITS2.1/CL0.1.2 | Highlight

29 million years of diverse mammalian enamel proteomes from Turkana in the East African Rift System 

Daniel Green, Kevin Uno, Ellen Miller, Craig Feibel, Eipa Aoron, Catherine Beck, Aryeh Grossman, Francis Kirera, Martin Kirinya, Louise Leakey, Cynthia Liutkus-Pierce, Fredrick Manthi, Emmanuel Ndiema, Cyprian Nyete, John Rowan, Gabrielle Russo, William Sanders, Tara Smiley, Patricia Princehouse, Natasha Vitek, and Timothy Cleland

Exploration of the paleobiology of extinct taxa through ancient DNA and proteomics has been largely limited to Plio-Pleistocene fossils due to molecular breakdown over time, a problem exacerbated in tropical settings. Here, we report small proteomes from the interior enamel of fossils deposited at paleontological sites dating between 29–1.5 Ma in the Turkana Basin, Kenya, which has produced the richest record of Cenozoic mammal evolution in eastern Africa. We recovered enamel protein fragments in all sampled fossils, including a ~ 29 Ma Arsinoitherium specimen belonging to an extinct mammalian order, Embrithopoda. Identified proteins include the classical structural enamel proteins amelogenin, enamelin, and ameloblastin, but also less abundant enamel proteins including collagens and proteases. Protein fragment counts decline in progressively older fossils, but we observe significant variability in Early Miocene preservation across sites, with ~17 Ma deinothere and elephantimorph proboscidean fossils from Buluk preserving substantially more proteins than rhinocerotid and anthracotheriid fossils from ~18 Ma Locherangan and hippopotamids from younger localities at Napudet (< 11 Ma). Most specimens yield known clade-specific diagenetiforms that support morphology-based taxonomic identifications. Matches to clade-specific proteins suggest the future potential of paleoproteomics to contribute to the systematic placement of extinct taxa, but should be approached with caution due to sometimes sparse fragment identification and the possibility of sequence diagenesis. We identify likely modifications that support the ancient age of these proteins, and the oldest examples of advanced glycation end-products and carbamylation yet known. The discovery of protein sequences within dense enamel tissues in one of the persistently warmest regions on Earth promises the discovery of far older proteomes that will aid in the study of the biology and evolutionary relationships of extinct taxa.

How to cite: Green, D., Uno, K., Miller, E., Feibel, C., Aoron, E., Beck, C., Grossman, A., Kirera, F., Kirinya, M., Leakey, L., Liutkus-Pierce, C., Manthi, F., Ndiema, E., Nyete, C., Rowan, J., Russo, G., Sanders, W., Smiley, T., Princehouse, P., Vitek, N., and Cleland, T.: 29 million years of diverse mammalian enamel proteomes from Turkana in the East African Rift System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21192, https://doi.org/10.5194/egusphere-egu24-21192, 2024.

Issues related to whether climate change have caused great calamites in human society are of fundamental importance to current climate change research. The causes and ecological consequences of climate change can, of course, be measured at different levels according to different scales because the natural sciences have long understood the verification of causality and importance of scale. Research regarding human responses to climate change in the humanities and social sciences has been less explicit, less precise, and more variable. The growing need for interdisciplinary work in the issues across the natural/social science boundary (gap), however, demands some common understandings about the causality and scaling issues on climate impact. We seek to facilitate the dialogue between natural and social scientists by reviewing some of the fundamental aspects of the philosophical concepts of causality and scale that can be employed in the climate change/human response study, especially as they relate to large scales of the human responses to ever-changing global climate in history. Here we present the common philosophical concepts of causality and scale in natural sciences and social sciences, examine how researchers in the field employ the philosophical concepts to verify the relationship between human societies and climate change using various samples with multiple scales and explore how to connect and break the links between climate change, human calamites and resilience at different levels of hierarchies. 

How to cite: Zhang, D. D.: Scale and Causal inference: from philosophical concepts to empirical verification in relationship between climate change and social responses., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21871, https://doi.org/10.5194/egusphere-egu24-21871, 2024.

EGU24-22198 | Orals | ITS2.1/CL0.1.2

Variable enamel growth rates in hippopotamid canines: Implications for seasonality reconstructions using inverse modeling of intra-tooth isotope data 

Antoine Souron, Maëlle Couvrat, Éric Pubert, Frédéric Santos, Deming Yang, Delphine Frémondeau, Clarisse Nékoulnang, and Olga Otero

Seasonal variations in climatic variables, and the resulting changes in vegetation, are strong factors governing ecosystem dynamics in modern and ancient times. Stable isotope ratios recorded in tooth enamel document isotopic variations in the environment at the time of enamel formation and thus reveal the intensity and duration of seasonal dietary and climatic variations. However, the long and multi-phased process of enamel mineralization causes a dampening of the original input signal. An inverse model previously developed for ever-growing canines of Hippopotamus amphibius proposes to recover the original input signal and assumes constant enamel growth rate, appositional angle, and maturation length. The present study aims to test these assumptions. To do so, we integrated data from histological thin sections, microtomodensitometric analyses, and stable isotope analyses on teeth of extant H. amphibius specimens (3 upper canines, 1 lower canine, 1 third molar) to quantify the geometric and temporal patterns of enamel mineralization. To estimate enamel extension rates (EER, in µm/increment), we counted the number of increments representing the position of appositional front for each segment of 5 mm along the enamel-dentine junction in thin sections made along the growth axis of each tooth. We used microtomodensitometry to determine the pattern of enamel maturation using grey values profiles of X-ray radiographies as a proxy for enamel mineralization degree. Serial sampling along one upper canine of an individual from Chad, coming from an environment with one rainy season per year, allowed us to document the intra-tooth d13C and d18O variations over 6 years and thus provided an independent temporal control on histological variations. The histological study showed that the enamel apposition phase is strongly irregular over time within the canines, with no clear temporal trend. EERs vary strongly among teeth and within each tooth (50-200 µm/increment, 100-350 µm/increment, and 80-200 µm/increment for the 3 upper canines; 150-550 µm/increment for the lower canine; 70-130 µm/increment for the third molar). The median EER value from the upper canine of the juvenile individual (ca. 180 µm/increment) is significantly higher than median EER values from the upper canines of two adult individuals (ca. 110 µm/increment). Similar variations are also observed in apposition angles (3°-8°, 2.5°-4.5°, 3°-7° for the 3 upper canines; 2°-8° for the lower canine; 6°-18° for the third molar). The enamel mineralization parameters vary with age and tooth type (canine vs. molar). Based on strongly correlated seasonal variations in d13C and d18O, we also confirm cyclic dietary variations with higher proportions of C4 plants consumed during the dry seasons. Using the range of enamel mineralization parameters observed within one single hippo canine, we conducted sensitivity tests on the inverse modeling method, producing different modeled input signals that suggest a wider range of uncertainty. In conclusion, the documented intra-canine variability of EER, as well as other histological parameters (apposition angle, maturation length), reveals challenges when applying the current inverse model to wild populations. Future work would benefit from a systematic histological investigation into the sources of variation of enamel growth and mineralization patterns. 

How to cite: Souron, A., Couvrat, M., Pubert, É., Santos, F., Yang, D., Frémondeau, D., Nékoulnang, C., and Otero, O.: Variable enamel growth rates in hippopotamid canines: Implications for seasonality reconstructions using inverse modeling of intra-tooth isotope data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22198, https://doi.org/10.5194/egusphere-egu24-22198, 2024.

With the evolution in climate, heat waves are occurring more commonly which leads to imply indoor temperatures. Several temperature thresholds have been suggested in diverse environments for the indication of indoor overheating. In this study, threshold values for perceived heat stress are evaluated and differentiated between susceptible households and non-susceptible households for the residents of Faisalabad in Pakistan. Data from 52 low to middle-income households were analyzed with the help of regression analysis, t-tests, and analysis of variances to discover characteristics associated with perceived heat stress during the nighttime period in the selected houses. We considered socio-demographic characteristics, health-related queries, heat-related health problems, and house/building material variables from the selected households. The results suggest that the health status during heat stress, age factor, climate zone, and high indoor temperature were the key attributes for the perceived heat stress. The threshold limit advised by the WHO for indoor is 24°C and most of the dwellers in case study live in 36-38°C. People appeared to be at risk for perceived heat stress without knowing to be at risk, particularly when numerous people live in one room (threshold limit 34.8C), suffering from disease (35.6 C) and below 60 (39.8 oC); therefore they do not take it seriously, to take adaption measures.

How to cite: Ibrahim, M., Ehsan, S., and Abbas, F.: Estimate Temperature Threshold for Low to Middle-Income Dwellers of Faisalabad City during Hot Summer Days, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-384, https://doi.org/10.5194/egusphere-egu24-384, 2024.

Air pollution, the largest global environmental health threat, associated with millions of premature death each year, is getting worse with climate change. To protect their health from air pollution, governments encourage people to stay indoors and avoid high pollution episodes. Moving indoors to reduce exposure to outdoor air is a form of avoidance adaptation. The frequency of this adaptive action can affect the amount of time people spend inside buildings. In Europe and North America, people already spend 90% of their time indoors. Air pollution from outdoors can infiltrate the building envelope, exposing people to pollution of outdoor origin at all times, and reducing the value of avoidance adaptation. To better understand the effect of this infiltration on human health, we examine the impact of building standards on the value of avoidance adaptation. This involves considering the costs of improving building envelopes and ventilation, and associated benefits due to avoided premature death from air pollution exposure. We conduct a historical study in the United States from 1980 to 2010 to examine the spatial and temporal patterns of costs and benefits associated with improving building standards to enhance adaptation to air pollution. This includes investigating past missed opportunities in reducing mortality and laying the foundation for future studies on existing long-term opportunities, all within the context of a changing climate. To achieve this, we establish baseline levels of exposure to the most harmful air pollutant, fine particulate matter, under this historical building stock across the United States. Subsequently, we assess the benefits and costs realized under each building standard improvement scenario (Improved Building Envelope and Improved Ventilation). This study will identify the demographics that can benefit the most from these improvements, quantifying, for example, the potential net gains of improving housing quality for low-income communities. It will address open questions on the value of adaptation in protecting human health under increasing risks from a changing climate.

How to cite: Salehi, A. R., Sparks, M., and Saari, R.: Hidden Health Opportunities: The Role of Building Standards in Adapting to Air Pollution in a Changing Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-783, https://doi.org/10.5194/egusphere-egu24-783, 2024.

EGU24-1878 | PICO | ITS2.12/CL0.1.4

Combined Impacts of Weather Conditions and COPD on the Risk for Community-Acquired Pneumonia 

Thomas Brenner, Ann-Christine Link, Christoph Reudenbach, Jörg Bendix, Barbara Weckler, Hendrik Pott, Jan Rupp, Martin Witzenrath, Gernot Rohde, Mathias Pletz, Wilhelm Bertrams, and Bernd Schmeck

Community-acquired pneumonia (CAP) is one of the most frequent causes of death among infectious diseases worldwide. Analyzing a dataset of 5,223 CAP patients in a German multicenter cohort study, our research uniquely explores the twofold combined impact of meteorological conditions, air quality conditions, and pre-existing chronic obstructive pulmonary disease (COPD) on CAP admissions. Both the twofold compound effect of absolute values of meteorological and air quality conditions and, even more, their day-to-day changes significantly influence CAP admissions. Our study emphasizes the important role of air quality conditions over meteorological conditions in contributing to increased CAP admissions, with these weather conditions exerting their influence with a lag time of approximately three to four days. Individuals with pre-existing COPD face the highest risk of CAP admission in the general cohort. The implications of our findings extend to supporting at-risk individuals through protective measures and providing healthcare providers with valuable insights for resource planning during pneumonia-inducing weather conditions.

How to cite: Brenner, T., Link, A.-C., Reudenbach, C., Bendix, J., Weckler, B., Pott, H., Rupp, J., Witzenrath, M., Rohde, G., Pletz, M., Bertrams, W., and Schmeck, B.: Combined Impacts of Weather Conditions and COPD on the Risk for Community-Acquired Pneumonia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1878, https://doi.org/10.5194/egusphere-egu24-1878, 2024.

EGU24-2325 | PICO | ITS2.12/CL0.1.4

The influence of humid heat on morbidity of megacity Shanghai in China 

Chen Liang, Jiacan Yuan, Xu Tang, Haidong Kan, Wenjia Cai, and Jianmin Chen

Background: Increased attention has been paid to humid-heat extremes as they are projected to increase in both frequency and intensity. However, it remains unclear how compound extremes of heat and humidity affects morbidity when the climate is projected to continue warming in the future, in particular for a megacity with a large population.

Methods: We chose the Wet-Bulb Globe Temperature (WBGT) index as the metric to characterize the humid-heat exposure. The historical associations between daily outpatient visits and daily mean WBGT was established using a Distributed Lag Non-linear Model (DLNM) during the warm season (June to September) from 2013 to 2015 in Shanghai, a prominent megacity of China. Future morbidity burden related to the combined effect of high temperature and humidity were projected under four greenhouse gases (GHGs) emission scenarios (SSP126, SSP245, SSP370 and SSP585).

Results: The humid-heat weather was significantly associated with a higher risk of outpatient visits in Shanghai than the high-temperature conditions. Relative to the baseline period (2010–2019), the morbidity burden due to humid-heat weather was projected to increase 4.4% (95% confidence interval (CI): 1.1% –10.1%) even under the strict emission control scenario (SSP126) by 2100. Under the high-GHGs emission scenario (SSP585), this burden was projected to be 25.4% (95% CI: 15.8% –38.4%), which is 10.1% (95% CI: 6.5% –15.8%) more than that due to high-temperature weather. Our results also indicate that humid-hot nights could cause large morbidity risks under high-GHGs emission scenarios particularly in heat-sensible diseases such as the respiratory and cardiovascular disease by the end of this century.

Conclusions: Humid heat exposures significantly increased the all-cause morbidity risk in the megacity Shanghai, especially in humid-hot nights. Our findings suggest that the combined effect of elevated temperature and humidity is projected to have more substantial impact on health compared to high temperature alone in a warming climate.

How to cite: Liang, C., Yuan, J., Tang, X., Kan, H., Cai, W., and Chen, J.: The influence of humid heat on morbidity of megacity Shanghai in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2325, https://doi.org/10.5194/egusphere-egu24-2325, 2024.

Climate change is expected to substantially alter biodiversity, leading to alterations in phenology, genetic composition, and species distribution while also affecting species interactions and ecosystem. Invasive alien species (IAS) have threatened the integrity of ecosystems throughout the world. They affect the species diversity of native ecosystems and threaten their biological integrity. Due to increasing movement of people and goods around the world, and with new trade routes opening and enhanced transportation, the number of species being introduced into new areas is rising. IAS reduce agricultural yields, irrigated croplands, grazing areas, and water availability, and contribute to the spread of mosquito-borne diseases. Mosquitoes are widely spread Mosquitoes are widely spread and transmit malaria and several arthropod-borne viruses. A particular example of IAS is Parthenium hysterophorus (Asteraceae). It is one of the world's most serious invasive plants that is able to thrive and spread aggressively outside its original geographical areas. Native to the subtropics and tropics of North and South America, Parthenium has negative effects on human, livestock, agriculture and the environment. The aim of this study is to determine the abundance and diversity of mosquito vectors at sites with different degrees of invasive plant infestations in the Rift valley area in Kenya. Currently, the spread of invasive plant species is a major problem in Kenya, where indigenous flora is replaced. The study sites are located in Baringo county. A total of 50000 mosquitoes were captured using a combination of different trapping techniques from six sites, three of them with IAS (Parthenium) and three without. We identified 48 species. A subset of 1000 mosquitoes was analyzed for evidence of recent plant feeding using cold anthrone test. An overall low fructose positivity rate (10.9%) was found. Barcode technique was applied to identify plant food source using specific primers for a locus from the chloroplast genome, ribulose diphosphate carboxylase. The DNA from all trees or shrubs within a 100m radius from the trap was collected to build a barcode reference library. Plant DNA with 55.3% (n = 553) success rate was identified. Sequences were successfully generated from samples, indicating Parthenium plants as the predominant plant fed by mosquito vectors. This survey is an inventory of the mosquito population composition and of the abundance and richness of arboviruses. It provides an insight into how changes in community ecology interact with the main types of land-use change and influence the dynamics of relevant arboviruses in Kenya. Thus, it provides a beneficial knowledge for targeted control.

Keywords

Climate change, land-use changes, agricultural expansion, infectious diseases, mosquito ecology, invasive plants, Parthenium hysterophorus

How to cite: Osman, T., Fevre, E., and Borgemeister, C.: Land-use management of invasive species could help prevent spread of mosquitoes borne diseases: Evidence from Kenya  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3257, https://doi.org/10.5194/egusphere-egu24-3257, 2024.

EGU24-3476 | ECS | PICO | ITS2.12/CL0.1.4 | Highlight

Real-time forecast of temperature-related excess mortality at small-area level: A conceptual framework 

Malcolm N. Mistry and Antonio Gasparrini

Development of innovative tools for real-time monitoring and forecast of environmental health impacts is central to effective public health interventions and resource allocation strategies. Though a need for such generic tools has been previously echoed by public health planners and regional authorities responsible for issuing anticipatory alerts, a comprehensive, robust and scalable real-time operational framework for predicting temperature-related excess deaths at local scale has not been developed yet. Filling this gap, we propose a flexible conceptual framework for coupling publicly available operational weather forecasts with temperature-mortality risk functions specific to small census-based zones, the latter derived using state-of-the-art environmental epidemiological models. Utilising high-resolution temperature data forecast by a leading European meteorological centre, we demonstrate a real-time application to forecast the excess mortality during the July 2022 heatwave over England and Wales. The output by way of expected temperature-related excess deaths at small geographic areas on different lead times, can be automated to generate maps at various spatio-temporal scales, thus facilitating preventive action and allocation of public-health resources in advance. While the real-case example discussed here demonstrates an application for predicting (expected) heat-related excess deaths, the framework can also be adapted to other weather-related health risks and to different geographical areas, provided data on both meteorological exposure and the underlying health outcomes are available to calibrate the associated risk functions. The proposed framework addresses an urgent need for predicting the short-term environmental health burden on public health systems globally, especially in low- and middle-income regions, where rapid response to mitigate adverse exposures and impacts to extreme temperatures are often constrained by available resources.

How to cite: Mistry, M. N. and Gasparrini, A.: Real-time forecast of temperature-related excess mortality at small-area level: A conceptual framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3476, https://doi.org/10.5194/egusphere-egu24-3476, 2024.

EGU24-3881 | ECS | PICO | ITS2.12/CL0.1.4

How seasonal flooding affects diets in Bangladesh during a nutrition-sensitive agriculture intervention. 

Claudia Offner, Thalia M Sparling, Claire Dooley, Jillian Waid, Sabine Gabrysch, and Suneetha Kadiyala

Background and aims: Climate change is expected to increase the frequency and severity of monsoon floods in south-east Asia and will severely impact food and nutrition security. The Food and Agricultural Approaches to Reducing Malnutrition (FAARM) cluster-randomized controlled trial in rural Bangladesh, aimed to improve nutrition outcomes through a Nutrition-Sensitive Agriculture (NSA) intervention. We evaluated the role of the intervention in moderating the impact of seasonal flood exposures on women’s dietary diversity (WDD) and food group consumption.

Description and recommendations: Using Bayesian interaction models, we paired a time series measure of seasonal flooding with high-frequency dietary data collected bi-monthly from 2,701 women throughout the trial (2015-2019). We found that for a 1% increase in flooding in Mar/Apr, subsequent WDD decreased by 18% of a food group in the control-arm, with no detrimental effect observed in the treatment-arm. Of the food groups, vitamin-A-rich foods (VA) was most influenced by seasonal flooding. The odds of consuming VA are normally 41% higher in the May/June months. However, for every 1% increase in flooding in Mar/Apr, the odds of consuming VA in May/June only increases by 13% for the control-arm, and by 27% for the treatment group.

Significance: Flooding has a variable impact on WDD and food consumption, and the NSA intervention appeared to offset the detrimental effects of flooding on WDD in the most volatile season. This study highlights the sensitivity of diets to changing monsoon patterns and provides an approach to evaluating the impacts of interventions on these intricate pathways.

How to cite: Offner, C., Sparling, T. M., Dooley, C., Waid, J., Gabrysch, S., and Kadiyala, S.: How seasonal flooding affects diets in Bangladesh during a nutrition-sensitive agriculture intervention., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3881, https://doi.org/10.5194/egusphere-egu24-3881, 2024.

EGU24-5480 | ECS | PICO | ITS2.12/CL0.1.4 | Highlight

Health Benefits of Meeting 2-degree Warming Scenario in India 

Debajit Sarkar, Sagnik Dey, Pallav Purohit, and Sourangsu Chowdhury

Anthropogenic emissions are responsible for deteriorated air quality and accelerated climate change in developing countries like India. The current trajectory of emissions is expected to further degrade air quality, potentially leading to increased warming levels by the end of the century, posing severe consequences for public health. In this study, we analyzed two scenarios using the GAINS-model framework - the business-as-usual (BAU), relying on existing air pollution control policies and measures, and the sustainable development scenario (SDS), integrating advanced air pollution control policies and measures, aiming to contain the global temperature increase below 2°C by 2100. We estimated the health burden attributable to ambient air pollution in BAU and SDS scenarios, segregated into regional and sectoral emissions in India for the years 2030 and 2050. Under the BAU scenario, premature mortality and disability-adjusted life-years (DALYs) are projected to increase from 0.72 million (95% CI: 0.53-0.89) and 24.8 million (15.4-30.5) in 2015 by 9.7% and 2.4% in 2030, respectively. In 2050, mortality and DALYs are projected to further increase to 0.88 million (0.75-1.01) and 26.2 million (22.8-29.6). At the sub-national level, states with a low Socio-demographic Index (SDI) are expected to possess majority (49-53%) of the health burden. However, if India follows the SDS scenario, 0.16 million (0.14-0.18) lives and 3.7 million (3.2-4.3) DALYs can be avoided in 2030. The corresponding benefits in 2050 will be 0.34 million (0.29-0.39) lives and 8.4 million (7.1-9.7) DALYs, respectively, relative to the BAU scenario. Our results reveal that states with a high SDI would experience the most significant benefits (15% and 26% for mortality & 26% and 44% for DALYs in 2030 and 2050), as compared to middle and low SDI states. The findings underscore the importance of immediate adoption of cost-effective and advanced technologies driven by sustainable development policies is imperative to mitigate air pollution and climate change simultaneously. A stronger mandate to revise the environmental standards and health policies is necessary to maximize health benefits in India. 

How to cite: Sarkar, D., Dey, S., Purohit, P., and Chowdhury, S.: Health Benefits of Meeting 2-degree Warming Scenario in India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5480, https://doi.org/10.5194/egusphere-egu24-5480, 2024.

The concurrent rise in global temperatures and air pollution levels has raised concerns regarding their joint effects on human health. Heatwaves, exacerbated by climate change, have become more frequent and intense, posing significant health risks to vulnerable populations. Concurrently, air pollution, stemming from anthropogenic activities and environmental factors, contributes to respiratory and cardiovascular ailments, amplifying the health burden.

 

It becomes important to utilize multifaceted data from climate models, demographic and socioeconomic projections like the Shared Socioeconomic Pathways (SSPs), geographical information and other pertinent datasets in exploring the complex relationship between climate change, exposure to air pollution, extreme heat and related health outcomes. Using various data sets including climate, demographic, and socioeconomic information at different scales (cohort, city, and small area levels), the recently concluded EU Horizon 2020 EXHAUSTION project quantified the synergetic effects of exposure to extreme heat and air pollution on mortality risks for respiratory and cardiovascular diseases. The project also investigated the influence of various vulnerability factors (e.g. socioeconomic conditions, access to green space) on the health risks. The heat-health burden was projected under future scenarios until 2100, taking into account shifting demographic patterns and baseline health status in various scenarios.

 

We advocate for the extension of methodologies employed in EXHAUSTION to encompass low- and middle-income countries in South Asia and sub-Saharan Africa, where extreme occurrences of heat and air pollution prevail. The assessment of climate change impacts on human health in these regions is notably challenging due to the scarcity of data across various domains, encompassing health, climate, and socio-demographic information. We advocate for enhanced accessibility and availability of this data to deepen our understanding of the effects of climate change-induced extreme heat and air pollution on mortality and morbidity in LMICs. This improved access will better equip health officials to strategize interventions and bolster adaptation responses. Furthermore, there is a need for more detailed emission and socio-demographic projections in LMICs, underpinned by data and reflective of current trends.

How to cite: Aunan, K.: Connecting climate change and health to protect the most vulnerable, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6687, https://doi.org/10.5194/egusphere-egu24-6687, 2024.

EGU24-6696 | ECS | PICO | ITS2.12/CL0.1.4

The role of shading on biometeorological conditions in the historic centre of Prague, Czech Republic. 

Lucie Chlapcová, Aleš Urban, and Jan Kyselý

Prague is the capital and the largest city of the Czech Republic and its historic centre near the Vltava river is a popular tourist destination. Especially the area along the right bank of the Vltava river, called Náplavka, is one of the most popular locations to visit during the summer months due to many social and cultural events that take place here. However, given the north-south orientation of the Vltava river and the lack of greenery and shade in this area, the question arises as to what extent thermal conditions are comfortable during hot summer days at Náplavka. Many previous studies have shown that the presence of greenery and shade is essential for reducing the heat stress in the streets.

In this study we assessed the effect of shading on biometeorological conditions at eight different measuring sites located along a loop between Charles Square and the Náplavka riverbank. Meteorological parameters (including air temperature, relative humidity, wind speed, Heat Index, Wet-Bulb Globe Temperature) were measured and recorded using the Kestrel 5400 portable tool, every two hours between 8:00 a.m. and 6:00 p.m. CEST on 9 days during summer in 2019 and on 5 days in 2022. In addition, fisheye photographs were taken at each location to quantify the effect of shading. From these data, we calculated advanced thermal comfort indices (Physiologically Equivalent Temperature, Universal Thermal Climate Index) and Sky View Factor (SVF) in the RayMan Pro program. We compared measured data from all sites under different weather conditions between 2019 and 2022, and assessed the evolution of heat stress during the day as a function of shading at each site.

Our results showed that while in the morning Náplavka’s biometeorological conditions were most comfortable among all measurement sites, they became most stressful in the afternoon. The analysis of the fisheye images showed that the lack of greenery and shading at Náplavka contributed significantly to the high heat stress levels. Our results suggest that the relocation of day-long events from Náplavka to other locations (e.g. a park at Charles Square) should be considered and/or adequate sun protection should be provided on hot summer days.

How to cite: Chlapcová, L., Urban, A., and Kyselý, J.: The role of shading on biometeorological conditions in the historic centre of Prague, Czech Republic., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6696, https://doi.org/10.5194/egusphere-egu24-6696, 2024.

Heat stroke is a serious heat-related health outcome that can eventually lead to death. Due to the poor accessibility of heat stroke data, the large-scale relationship between heat stroke and meteorological factors is still unclear. We collected daily heat stroke search index and meteorological data for the period 2013–2020 in 333 Chinese cities to quantify the threshold of people may suffer from heat stroke by Random Forest model. When the daily mean temperature exceeded 23.5°C, heat stroke cases may occur in China. Then, we calculated the total heatwave duration exceeding the threshold quantified aforementioned and population exposure to heatwave in China using four scenario combinations, namely SSP1SSP1-2.6, SSP2SSP2-4.5, SSP3SSP3-7.0, SSP5SSP5-8.5, for 1986-2005, 2041-2060 and 2081-2100 periods.

How to cite: Han, Q.: Heat stroke risk in China quantified by web-based data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7407, https://doi.org/10.5194/egusphere-egu24-7407, 2024.

EGU24-7794 | PICO | ITS2.12/CL0.1.4 | Highlight

Weather, influenza epidemics and mortality patterns in central Europe 

Hana Hanzlíková, Aleš Urban, Eva Plavcová, Jan Kynčl, and Jan Kyselý

In temperate climates, influenza follows a seasonal pattern with peak incidence in winter and contributes significantly to excess winter mortality. The relationship between weather variability, influenza and human health is complex and the underlying mechanisms remain unclear. This study investigated the links between meteorological variables, influenza epidemics, and mortality in the Czech Republic over the 1982/83 to 2019/20 epidemics seasons. Results showed that severe influenza outbreaks with largest mortality impacts, primarily driven by A/H3N2 viruses, were preceded by falling temperatures, increasing relative humidity and cloud cover, and low air temperatures, high cloud cover and high relative humidity prevailed for their duration. In contrast, A/H1N1-related epidemics with lower mortality impacts occurred usually during periods of average or above-average temperatures, accompanied by elevated relative humidity and cloud cover. Influenza epidemics peaking later in winter or in early spring were associated with high excess mortality, usually lasted longer and were accompanied by prolonged periods of low temperatures. The results highlight the importance of ambient temperature and other weather variables in the transmission of influenza virus and course and severity of the epidemics. Prolonged periods of low temperatures in winter, together with the prevalence of influenza A/H3N2 in the population, were identified as an important contributing factors to the significant excess mortality in the temperate climate of central Europe.

How to cite: Hanzlíková, H., Urban, A., Plavcová, E., Kynčl, J., and Kyselý, J.: Weather, influenza epidemics and mortality patterns in central Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7794, https://doi.org/10.5194/egusphere-egu24-7794, 2024.

EGU24-8031 | PICO | ITS2.12/CL0.1.4

Inequality in the exposure to air pollution and temperature through the century 

Andrea Pozzer, Sourangsu Chowdhury, Lin Ma, and Brendan Steffens

Air quality and surface temperature exert significant influences on human health. However, the impact of air pollution and non-optimal temperature is not uniformly experienced across the population. In this study, we employ the "Gini" coefficient, a commonly used concept in economics. While traditionally applied to represent wealth inequality, we adapt this coefficient to gauge spatial inequality in population exposure to air pollutants and temperature, irrespective of the economic income of the population. As pollution and temperature are dynamic and subject to change in the future due to varying climate change and socioeconomic scenarios, our analysis extends to potential scenarios projected by the Coupled Model Intercomparison Project (CMIP6). We show changes of the Gini coefficient both at global, regional and country scale for the present century (2000-2100) covered by the model simulations. Our findings indicate that at global level, air quality inequality has peaked around the present time, with a trend towards decreasing inequality in most projections, reaching a minimum by the end of the century. Conversely, temperature exposure inequality will fluctuate based on the scenario, primarily showing an increasing inequality trend over time in alignment with anticipated climate change impacts. Importantly, the Gini coefficient estimation provides a complementary view to air quality and climate change assessment, indicating exposure disparities among the population in a specific region. Our study shows the unequal distribution of air quality and temperature exposure among populations, emphasizing the need for targeted interventions and policies to address these disparities, especially considering the projected changes in climate and socioeconomic factors.

How to cite: Pozzer, A., Chowdhury, S., Ma, L., and Steffens, B.: Inequality in the exposure to air pollution and temperature through the century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8031, https://doi.org/10.5194/egusphere-egu24-8031, 2024.

EGU24-9746 | ECS | PICO | ITS2.12/CL0.1.4

Residential green space and summer heat stress: a repeated cross-sectional study 

Eva Beele, Raf Aerts, Maarten Reyniers, and Ben Somers

Urbanization and global warming have led to the emergence of urban heat islands, profoundly impacting the liveability and long-term well-being of people living in cities. This study investigates the impact of urban green space composition and configuration on stress and sleep quality in Leuven, Belgium, during the summers of 2021 and 2022.

Utilizing three validated stress questionnaires (PSS, PSQI, and HSSI), we assessed mental health, sleep quality and heat stress during 4 heat and 4 control events for 785 respondents. Concurrently, we recorded risk and vulnerability factors related to physical sensitivity, socio-economic sensitivity and personal living space for each respondent. Urban land cover data at 50m and 250m buffer scales were analysed using composition and configuration metrics. Structural equation models were employed to investigate the impact of urban green space on stress and sleep quality during both heat and non-heat control events. Models were adjusted for risk and vulnerability factors, and effectively dealt with spatial autocorrelation inherent in our data.

During control events, mental health, sleep quality and heat stress were predominantly associated with risk and vulnerability factors. High physical sensitivity, elevated socio-economic sensitivity and suboptimal personal living spaces were associated with higher physiological stress, poor sleep quality, and higher heat stress. Conversely, during heat events, stress indicators were predominantly associated with the surrounding green space, while associations with risk and vulnerability factors were limited. Augmenting high green relative cover may mitigate heat stress, while increasing low green cover may alleviate both heat stress and enhance sleep quality. Stratified analyses for socio-economic status and distinct urban-rural regions revealed notable differences among subgroups.

In conclusion, this study emphasizes the importance of incorporating both low and high green spaces to mitigate heat stress and improve sleep quality and therefore, human health, during heat events.

How to cite: Beele, E., Aerts, R., Reyniers, M., and Somers, B.: Residential green space and summer heat stress: a repeated cross-sectional study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9746, https://doi.org/10.5194/egusphere-egu24-9746, 2024.

EGU24-10908 | ECS | PICO | ITS2.12/CL0.1.4

Reacting to climate change and temperature extremes: A case study on the tiger mosquito in Italy­ 

Miguel Garrido Zornoza, Cyril Caminade, and Adrian Tompkins

Native to tropical and subtropical regions of Southeast Asia, Aedes albopictus, commonly known as the tiger mosquito, has been spreading worldwide with the aid of human activity. The geographical distribution and temporal dynamics of this mosquito are of special interest, given its role as a vector for arboviruses such as dengue (DENV) and chikungunya (CHIKV). Climate change, and its consequent increase in ­­both mean surface temperatures and the frequency and intensity of heat waves, has the potential to affect the behavior and seasonal activity of this mosquito, thereby posing a significant risk to human health. Understanding the impact of mean temperature changes and extremes on potential vector-borne disease risk is paramount to forecasting future trends as well as developing meaningful intervention strategies.

 

In this work, we study the dynamics of Ae. albopictus over three decades, spanning 1990-2019, with a particular emphasis on the Italian Peninsula, which has remained a significant hotspot in Europe, since its introduction in the 1990s. We employed and adapted VECTRI, a climate-sensitive dynamical model that was originally designed for malaria. The model has been modified to parameterize Ae. albopictus and successfully calibrated to reproduce the seasonality of the vector using ovitrap data from various locations in Italy. Driving the model using high resolution EOBS gridded observation data, we perform various experiments to isolate the impact of temperature trends and late-spring to summer temperature extremes. Our results show a temperature-driven linear increase in the length of the mosquito season, with larger increases over the southern regions. Overall, temperature extremes tend to increase the bulk egg population across the country, although different spatial trends are highlighted: warm events tend to reduce vector populations in the Po valley and southern regions of Italy,already subject to the highest temperatures, while they tend to increase vector abundance over fringe highland areas. Our results indicate that 10-day temperature forecasts could be utilized to predict mosquito activity and consequently guide vector control intervention strategies such as insecticide spraying in the higher altitude regions identified in this study.

How to cite: Garrido Zornoza, M., Caminade, C., and Tompkins, A.: Reacting to climate change and temperature extremes: A case study on the tiger mosquito in Italy­, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10908, https://doi.org/10.5194/egusphere-egu24-10908, 2024.

EGU24-11803 | PICO | ITS2.12/CL0.1.4 | Highlight

Copernicus Health Hub: Health community accessing environmental information from the Copernicus Programme 

Julie Letertre, Christian Borger, Cristina Ananasso, and Vincent-Henri Peuch

Copernicus is the Earth observation component of the European Union’s Space programme, looking at our planet and its environment to benefit all European citizens.

The Copernicus services transform a wealth of satellite and ground-based measurements into value-added information by processing and analysing the products.

All the information is provided with an open and free data policy to help public national and European authorities, policy makers, international organisations, and service providers to improve European citizens' quality of life.

There are six operational Copernicus Services covering the whole Earth System including ocean, land, atmosphere, and more horizontal domains such as climate change, emergency and security.

To facilitate the use of these information by the different user communities, some Thematic Hubs have been created and are under development. One of the first hubs is the Copernicus Health Hub (CHH) and it is focusing on the health community.

The CHH collects and provides all the Copernicus environmental information that are pertinent to Health, following the WHO definition: Physical, Mental and Well-being. The Health Hub is also supporting the users in better exploiting and uptake Copernicus data and products (via documentation, access to catalogues, inspirational use case stories, …). In addition, the CHH should collect new requirements for the evolution of the Copernicus programme.

In this presentation, the CHH will be introduced in more details, the different types of environmental information will be presented accompanied by some use cases to inspire further developments and new applications for the health community.

How to cite: Letertre, J., Borger, C., Ananasso, C., and Peuch, V.-H.: Copernicus Health Hub: Health community accessing environmental information from the Copernicus Programme, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11803, https://doi.org/10.5194/egusphere-egu24-11803, 2024.

EGU24-12490 | ECS | PICO | ITS2.12/CL0.1.4

Digital thermal 3D model for thermal comfort analysis at district scale. 

Chaimaa Delasse, Rafika Hajji, Tania Landes, Hélène Macher, Pierre Kastendeuch, and Georges Najjar

Today’s cities face many challenges, including those related to climate change, energy efficiency, and human well-being. These issues are closely linked to the thermal dynamics of the built environment. Sub-optimal solutions and increased vulnerability often result from a lack of deep understanding of the spatial and temporal variations of thermal interactions in the urban context, particularly in data-limited regions. The primary objective of this thesis is to develop a methodology for creating "as-built" digital thermal models through 3D reconstruction of urban scene objects such as buildings, trees, and pavements. The coupling of 3D geometry and TIR (Thermal Infra-Red) acquisitions at different periods enhances the semantic richness of the model and facilitates the study of building-tree thermal interactions. This, in turn, enables the calculation and the monitoring of the evolution of thermal comfort indices at a micro-scale (<2km). To this end, the TRIO team has developed LASER/F (Latent And Sensible Radiation Fluxes), a microclimate simulation software that can replicate the effect of buildings and trees on the urban microclimate. The buildings and trees of interest are modeled with a high level of detail (LOD3) to improve the accuracy of the simulations. The simulated thermal model will be evaluated using "real" thermal and eco-physiological data collected in the field. The validated model will be used to simulate various scenarios for improving thermal comfort, making it a valuable decision-making tool for urban planning. The study will be conducted at two sites, one in Strasbourg (France) and the other in Rabat (Morocco). This study aims to analyze, compare, and improve LASER/F simulations at two sites, in two different countries and climates. The goal is to assess the impact of existing vegetation configurations and propose scenarios for improving thermal comfort. This may include changes to tree species or positions and the modification of urban geometry. Measurement campaigns have been carried out at the Strasbourg site during the summer of 2023. Fixed environmental measurements such as wind speed, relative humidity, global radiation, and sap flow were carried out. 3D geometry acquisitions were performed using laser scanners. TIR data was also acquired thanks to thermal cameras at fixed positions and thermobuttons located on facades. Moreover, a mobile system composed of RGB (Red Green Blue) cameras and a TIR camera has been specifically designed. Similar campaigns are planned for the Rabat site in 2024.

How to cite: Delasse, C., Hajji, R., Landes, T., Macher, H., Kastendeuch, P., and Najjar, G.: Digital thermal 3D model for thermal comfort analysis at district scale., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12490, https://doi.org/10.5194/egusphere-egu24-12490, 2024.

EGU24-12795 | ECS | PICO | ITS2.12/CL0.1.4

The association between tropical sea surface temperature variability and sentinel reporting of travel-related dengue  

Stella Dafka, Michael Libman, Davidson H. Hamer, Joacim Rocklöv, and Ralph Huits

Oceanic-atmospheric interactions play a crucial role in the modulation of monsoon rainfall. This is the first study that directly investigates the impact of tropical sea surface temperature (SST) variability on the frequency of sentinel reporting of travel-related dengue from the Geosentinel global emerging infectious disease surveillance network, by using the latest climate reanalysis ERA-5 produced by the European Center for Medium-Range Weather Forecasts, for the period 2007 to 2019. More specifically, we explore lag structures and the associated spatial correlation patterns between travel-related dengue cases, SSTs, and total precipitation over the tropics. We found that the Indo-Pacific and Atlantic Ocean SSTs have a remote influence on dengue risk in global regions that exhibit distinct monsoon characteristics. The coupling between SST variations and rainfall is an important driver of travel-related dengue cases and could act as an early warning signal for outbreak preparedness and travel medicine preventive advice. Finally, our findings highlight the need to better understand the large-scale and local circulation response to changes in the pattern of tropical ocean warming, to be able to better predict extreme events such as droughts and floods and devise adaptation measures against dengue outbreaks.

How to cite: Dafka, S., Libman, M., Hamer, D. H., Rocklöv, J., and Huits, R.: The association between tropical sea surface temperature variability and sentinel reporting of travel-related dengue , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12795, https://doi.org/10.5194/egusphere-egu24-12795, 2024.

The city of Belgrade has experienced a rise in temperatures during summers, marked by an increased frequency and intensity of heat waves. A concerning element is the escalation of overnight temperatures, which fail to cool down adequately. This phenomenon is particularly prevalent in urban areas due to the urban heat island effect. This study aims to provide evidence of the summer discomfort experienced in Belgrade during tropical nights over the past two decades and its impact on health. To achieve this, it is compiled a dataset containing daily weather information recorded at 9 pm (CET) spanning the years 2000 to 2020.

How to cite: Pecelj, M.: Summer Discomfort During Tropical Nights in Belgrade (Serbia), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13063, https://doi.org/10.5194/egusphere-egu24-13063, 2024.

EGU24-13800 | ECS | PICO | ITS2.12/CL0.1.4 | Highlight

The exceedance of physiologically relevant thresholds in South Asia 

Joy Monteiro, Jenix Justine, Hardik Shah, and Neethi Rao

Since the pioneering work in the early 2000s, there has been interest in the climate science community in using the compounding effects of heat and humidity (in the form of wet-bulb temperatures or other meteorological indices such as heat index) to understand health risks due to thermal stress on humans. For instance it has been suggested that the combination of high heat and humidity was responsible for the high mortality observed during the 2015 heatwaves in South Asia. However, assessing health impacts of temperature and humidity is challenging in South Asia since the health data required for epidemiological work is rarely available or reliable for robust analyses.

Using quality-controlled surface observations, we show that the humidity (or equivalently, wet-bulb temperatures) was in fact lower during most high impact heatwaves in South Asia -- the daily maximum was very close to its monthly mean value whereas the daily minimum dropped to much lower values. We show that this is due to a deeper boundary layer which dilutes the near-surface water vapour concentrations. Therefore, our analysis suggests that one-dimensional indices such as wet-bulb temperature may not be accurate in predicting health risks across the wide variety of meteorological conditions that South Asia experiences.

Using recent experimental results that demonstrate that hazardous conditions can occur at lower humidity values, we show that thresholds derived from these experiments produce a more realistic spatial and temporal distribution of hazardous conditions in South Asia as compared to wet-bulb temperatures alone. Furthermore, we show that hazardous exposure during the day extends to times not usually considered hazardous in public health messaging. Our results suggest that physiological thresholds provide a complementary way to assess health risk due to heat along with epidemiological regression studies.

How to cite: Monteiro, J., Justine, J., Shah, H., and Rao, N.: The exceedance of physiologically relevant thresholds in South Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13800, https://doi.org/10.5194/egusphere-egu24-13800, 2024.

EGU24-13976 | ECS | PICO | ITS2.12/CL0.1.4

Quantifying future risk of South Pacific Hospitals from climate change 

Michelle McCrystall, Chris Horvat, Liz McLeod, Madelyn Stewart, Lydia Stone, Subhashni Taylor, Callum Forbes, Eileen Natuzzi, and Berlin Kafoa

Health facilities in Pacific Island Countries are under threat due to ongoing climate change, namely from extreme weather events such as tropical cyclones. However, obtaining accurate projections of risks are inhibited due to the size and complex geometries of these islands which are not accurately or sometimes even entirely represented in the current resolution of global climate models.  Using higher resolution models and the Synthetic Tropical cyclOne geneRation Model (STORM) to generate 10,000 synthentic tropical cyclones, this study takes a greater in-depth analysis of extreme weather events and tropical cyclones at hospitals in Fiji, Vanuatu, Solomon Islands and Tonga.

Preliminary results show an approximately 150% increase in the frequency of extreme cyclones of category 4 or 5 at hospitals across the Pacific, with Vanuatu and Tonga projected to experience a 200% increase in extreme storms. Projected increases in extreme rainfall days (number of days where rainfall exceeds 95th percentile) ranges between 14-161% and extreme heat days are expected to increase between 43-303 days per year by the end of the century. Mitigating against the impacts of climate change on medical care in these islands is hugely important, and so future aims of this work are to use statistical downscaling and AI-driven model acceleration, as part of our project EMPIRIC2 (EMulation of Pacific Island Risk to Infrastructure from Climate), to provide robust, time-variant facility risks statistics directly to policymakers who are working to improve health infrastructure resilience across the South Pacific.

How to cite: McCrystall, M., Horvat, C., McLeod, L., Stewart, M., Stone, L., Taylor, S., Forbes, C., Natuzzi, E., and Kafoa, B.: Quantifying future risk of South Pacific Hospitals from climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13976, https://doi.org/10.5194/egusphere-egu24-13976, 2024.

EGU24-15152 | PICO | ITS2.12/CL0.1.4 | Highlight

Health-relevant compound ground-level ozone and temperature events in Europe 

Elke Hertig and Irena Kaspar-Ott

Ground-level ozone is a major air pollutant harmful for human health and there are concerns that ground-level ozone will increase over Europe under climate change despite efforts for a rigorous air pollution control. In addition, high levels of ground-level ozone often occur in combination with high air temperatures, for instance under persistent anticyclonic conditions in summer. Due to climate change heat events such as hot days and heat waves are also increasing. Thus, ground-level ozone health risks could combine with increased health risks from heat exposure.

Changes in the atmospheric chemistry from increased biogenic volatile organic compound emissions, faster chemistry kinetics, and faster peroxyacetyl nitrate decomposition as well as enhanced stratosphere-troposphere exchange, changes of the large-scale atmospheric circulation and synoptic patterns, increased stagnancy, and changes of atmospheric humidity may lead to increases of ground-level ozone in the scope of climate change. For Europe regional differences exist. For instance, over central Europe there is a strong relationship with meteorological conditions, while over southern and northern Europe the influence of ozone persistence and hence precursor emissions is comparably strong on ozone exceedances.

The present contribution comprises relationships of ground-level ozone and temperature with the atmospheric circulation, changes of health-relevant ground-level ozone and temperature events under future climate change as well as the connection of ground-level ozone and temperature with human health outcomes.  

How to cite: Hertig, E. and Kaspar-Ott, I.: Health-relevant compound ground-level ozone and temperature events in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15152, https://doi.org/10.5194/egusphere-egu24-15152, 2024.

EGU24-15296 | PICO | ITS2.12/CL0.1.4

A computational framework for personal multi-exposure assessment using space-time activity and socio-economic data 

Oliver Schmitz, Kees de Hoogh, Nicole Probst-Hensch, Ayoung Jeong, Benjamin Flückiger, Danielle Vienneau, Gerard Hoek, Kalliopi Kyriakou, Roel C. H. Vermeulen, and Derek Karssenberg

The construction of simulation models for personal exposure analysis requires the integration of field-based data representing spatially distributed values (e.g. air pollution, noise, temperatures), agent-based data (e.g. daily activities, residential and work locations) and socio-economic data (e.g. age, social economic status, mode of commute) to fully cover the space-time activity patterns of cohort participants. In addition, evaluating the associated uncertainty is necessary as potentially not all required input variables are known.

We developed a modelling framework implemented in Python providing modules for 1) the specification of agents' activity diaries including the durations of activities and their spatial contexts, i.e. the location of a person during that activity, commute trips between residential and work location are thereby routed using OpenStreetMap data; 2) incorporating multiple environmental factors potentially on different temporal and spatial scales; 3) personal exposure assessment by calculating, for each time step and environmental factor, average exposure values within the spatial contexts. The modules can be combined in a Python script for exposure assessment of all agents in a cohort, including Monte Carlo simulations.

We show results from a modelling study conducted for the province of Utrecht, the Netherlands. The study area covers about 500000 residential address locations covering urban and rural areas. We used cadastral and census data to define characteristic diurnal activity profiles describing different characteristics such as social economic status and commute type (e.g. car, bicycle, on foot). We calculated individual exposures to NO2, PM2.5 and noise in Monte Carlo mode and demonstrate the spatial variability of exposures per activity profile and the associated uncertainty. The personal exposures for commuter profiles show more contrast across addresses compared to the homemaker profiles.

Our activity-based mobility simulation provides a representative description of space-time activities of individuals. The calculated personal exposures can be used for further epidemiological analysis to investigate the relationship between air pollution exposure and chronic diseases such as diabetes or cardiovascular disease.

How to cite: Schmitz, O., de Hoogh, K., Probst-Hensch, N., Jeong, A., Flückiger, B., Vienneau, D., Hoek, G., Kyriakou, K., Vermeulen, R. C. H., and Karssenberg, D.: A computational framework for personal multi-exposure assessment using space-time activity and socio-economic data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15296, https://doi.org/10.5194/egusphere-egu24-15296, 2024.

EGU24-16105 | ECS | PICO | ITS2.12/CL0.1.4 | Highlight

Increasing climate change changes household medical expenditures 

Dianyu Zhu, Miaomiao Liu, Ruoqi Li, Yuli Shan, Haofan Zhang, Jun Bi, and Klaus Hubacek

Climate change is exacerbating global disease risks, which will change household medical expenditures. Employing machine learning techniques and fine-scale bank transaction data, this study explores the changing household medical expenditures in 290 Chinese cities under four SSP scenarios (SSP1-2.6、SSP2-4.5、SSP3-7.0、SSP5-8.5) and further evaluates the adaptive impacts from socio-economic and physiological adaptations. The results show that the increasing temperature is projected to decrease future medical expenses in China by 5.24% (SSP1-2.6) to 5.60% (SSP5-8.5) in 2060. Cities exhibit differentiated sensitivity to increasing temperatures. Richer cities have enhanced resilience to high temperatures, and cold regions demonstrate less vulnerability to extreme cold weather. Physiological adaptation to climate change can significantly reduce medical expenditures by 27.6% by 2060. Meanwhile, socio-economic adaptation is expected to amplify national total medical expenses by 22.5% in 2060 under the SSP5-8.5 scenario. Our study incorporates adaptation into the prediction of future medical expenditures in China, aiming to assist cities in devising tailored climate adaptation strategies to alleviate the household economic strain induced by climate change. 

How to cite: Zhu, D., Liu, M., Li, R., Shan, Y., Zhang, H., Bi, J., and Hubacek, K.: Increasing climate change changes household medical expenditures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16105, https://doi.org/10.5194/egusphere-egu24-16105, 2024.

EGU24-16469 | PICO | ITS2.12/CL0.1.4

Health protection from heat waves in Croatia - today and in the future 

Lidija Srnec, Vjeran Magjarević, and Renata Sokol Jurković

Some recent research shows that the average annual excess of deaths is higher due to cold than warm events. Despite that fact, the last two decades are the warmest in history of air temperature monitoring so the long term series analyses show the increase in the frequency but also the severity of the heat waves. 

A heat wave early warning system is a very useful way of protecting human health. This system in Croatia has been operational since 2012 and thanks to it vulnerable groups of people are timely warned about the level of possible risk. In this work, we will briefly explain how Croatian early warning system works nowadays and show the change of number and level of heat wave risks through the past.  

The possible change in heat wave risk in the future will be analysed by using regional climate simulations from the EURO-CORDEX data set. Simulations will cover a set of projections on 12.5 km horizontal resolution, taking into account moderate and high RCP scenarios. The future climate will be considered for three 30-year time slices.  

The operational criteria currently used in the Croatian heat wave early warning system will be applied to the projected daily minimum and maximum air temperatures. The modelled data will be bias-corrected according to the measured data at Croatian meteorological stations. Original outputs and bias-corrected data will be analysed and compared to see which data sets approach closer to the measured data set. Historical climate risk simulated by models will be compared with issued warnings to evaluate simulations. The difference between projected and historical climate risk will be analysed by level of risk, duration, and spatial distribution.              

How to cite: Srnec, L., Magjarević, V., and Sokol Jurković, R.: Health protection from heat waves in Croatia - today and in the future, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16469, https://doi.org/10.5194/egusphere-egu24-16469, 2024.

Although the World Health Organization has declared that the COVID-19 pandemic no longer qualifies as a global public health emergency, it still needs to review the response of society to the COVID-19 pandemic. Previous studies indicated that socio-economic status (SES) was linearly associated with the COVID-19 pandemic. However, this relationship may be more complex due to regional differences. Meanwhile, it needs to analyze the nonlinear impact of multiple factors on the infection rate. In the study, we analyzed the differences in infections among low, lower-middle, upper-middle and high SES group (LSG, LMSG, UMSG, and HSG, respectively), and considered the social and meteorological factors, revealing the effect and mechanisms of SES on infections. The results showed that the relationship between SES and infection rate was inverted U-shaped, especially in the first three phases. The contribution of meteorological factors to the infection rate first increased and then decreased. In the first phase, mask usage was the most important factor affecting the change in infection rate, with the contribution of 23.17%. In the second phase, temperature was the most important factor affecting the change in infection rate. In the third and fourth phases, vaccination was the most important factor. Furthermore, the nonlinear impact of multiple factors related to SES on the infections explains the complex relationship between SES and infections. The study argues for greater attention to countries with medium SES and the need for future targeted measures to cope with infectious diseases.

How to cite: Sun, Y. and Shi, P.: Multiple factors drive the infection rate in the progress of the COVID-19 pandemic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18312, https://doi.org/10.5194/egusphere-egu24-18312, 2024.

EGU24-19453 | ECS | PICO | ITS2.12/CL0.1.4

Assessing health risks in Croatia for cases of severe weather via UTCI and PET 

Ines Muić, Iris Odak Plenković, Lidija Srnec, and Kristian Horvath

As our climate is changing due to global warming, severe weather is expected to increase in frequency and it's intensity. Out of many examples of severe weather, we are focusing on cold and heat waves which greatly affect people causing increased mortality and morbidity. Also, some of the most important climate modifiers in Croatia are the Adriatic, the Mediterranean, the Dinarides orography, and the Pannonian plain. Because of this, the strongest winds in the Adriatic coast of Croatia are jugo and bora which can sometimes reach gale strength. They are associated with different weather conditions and can also have an impact on morbidity. For example, people describe a favorable impact on health and mood during most cases of moderate bora and unfavorable during moderate jugo episodes.

 In this work, we are exploring the potential of the Universal Thermal Climate Index (UTCI) and Potential Equivalent Temperature (PET) as severe weather-related health risk indicators in Croatia. The UTCI and PET are bioclimate indices that use human heat balance models to represent the thermal stress and comfort that is induced in the human body by meteorological conditions. For a couple of continental, maritime, and mountain stations in Croatia UTCI and PET are calculated from measurements. The exception is the mean radiant temperature which is estimated from the Rayman model based again on the measurements of global radiation, air temperature, and relative humidity. The distribution of all-cause death counts at different UTCI and PET values is investigated to determine a more appropriate measure of health risk.

The UTCI and PET are calculated for the domain over Croatia for the selected cases of a heat wave, a cold wave, and strong wind episodes. The meteorological data used for the calculation of UTCI and PET are hourly NWP model ALADIN-HR output values of air temperature, relative humidity, wind speed, and mean radiant temperature. The UTCI and PET are compared and show good agreement. Results for the cases of strong wind show UTCI sensitivity to the wind but depend on the air temperature primarily.

How to cite: Muić, I., Odak Plenković, I., Srnec, L., and Horvath, K.: Assessing health risks in Croatia for cases of severe weather via UTCI and PET, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19453, https://doi.org/10.5194/egusphere-egu24-19453, 2024.

EGU24-20406 | ECS | PICO | ITS2.12/CL0.1.4

Regional Features of Long-Term Exposure to PM2.5 Air Quality over Asia under SSP Scenarios Based on CMIP6 Models 

Hyun Min Sung, Sungbo Shim, Jisun Kim, Jae-Hee Lee, Min-Ah Sun, Chu-Yong Chung, and Young-Hwa Byun

This study investigates changes in fine particulate matter (PM2.5) concentration and air-quality index (AQI) in Asia using nine different Coupled Model Inter-Comparison Project 6 (CMIP6) climate model ensembles from historical and future scenarios under shared socioeconomic pathways (SSPs). The results indicated that the estimated present-day PM2.5 concentrations were comparable to satellite-derived data. Overall, the PM2.5 concentrations of the analyzed regions exceeded the WHO air-quality guidelines, particularly in East Asia and South Asia. In future SSP scenarios that consider the implementation of significant air-quality controls (SSP1-2.6, SSP5-8.5) and medium air-quality controls (SSP2-4.5), the annual PM2.5 levels were predicted to substantially reduce (by 46% to around 66% of the present-day levels) in East Asia, resulting in a significant improvement in the AQI values in the mid-future. Conversely, weak air pollution controls considered in the SSP3-7.0 scenario resulted in poor AQI values in China and India. Moreover, a predicted increase in the percentage of aged populations (>65 years) in these regions, coupled with high AQI values, may increase the risk of premature deaths in the future. This study also examined the regional impact of PM2.5 mitigations on downward shortwave energy and surface air temperature. Our results revealed that, although significant air pollution controls can reduce long-term exposure to PM2.5, it may also contribute to the warming of near- and mid-future climates.

How to cite: Sung, H. M., Shim, S., Kim, J., Lee, J.-H., Sun, M.-A., Chung, C.-Y., and Byun, Y.-H.: Regional Features of Long-Term Exposure to PM2.5 Air Quality over Asia under SSP Scenarios Based on CMIP6 Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20406, https://doi.org/10.5194/egusphere-egu24-20406, 2024.

EGU24-20465 | ECS | PICO | ITS2.12/CL0.1.4 | Highlight

Health integration in climate-related policies: evidence and gaps in the EU policy context   

Claudia de Luca, Benedetta Cavalieri, Benedetta Baldassarre, Joy Ommer, and Milan Kalas

Climate change represents the greatest threat to human health, with both direct and indirect effects. 

The direct increase of deaths, due to extreme weather and climate events, the emergence and spread of infectious diseases related to changing temperature, habitat and precipitation patterns, and eventually climate shocks and growing stress and anxiety that are affecting mental health. Moreover, extreme weather events cause issues on our health systems and infrastructures, reducing capacity to provide health coverage.  

An increasing awareness on adverse effects of climate change is leading to an update of the EU policy framework through the introduction of  the EU Green Deal, a ‘package’ of directive, policies and strategies to ensure planning, monitoring and reporting of progress towards responsive climate adaptation and climate neutrality; however, a clear demonstration of the health-relevant outcomes of climate policies and actions is still missing, and current policies do not properly consider human health protection.  

The study is developed within the Horizon Europe-funded project TRIGGER, aimed at deepening the understanding of the linkage between climate change and health and advancing society uptake at policy level. 

Starting from mapping and screening the existing climate-related policies and measures at European level, this study assesses the integration of health in such documents. Specifically, through a keyword-based content analysis, it evaluates the integration of health-relevant considerations in 11 European plans and strategies, referring to climate mitigation and adaptation, environmental sustainability and biodiversity conservation. To establish to what extent they consider the direct and indirect impacts of climate change on human health, a qualitative assessment of health integration is performed, exploring also, when available, cost-benefits estimation to possible health impacts and health-related indicators developed.  

The results show that extreme events, such as heat waves and droughts, heavy precipitation and flooding, are the climate-related hazards mostly mentioned in relation to health, even though the policy integration remains limited. Indeed, just few policies contain references to physical health impacts determined by climate change, such as infectious and vector borne diseases, injuries from extreme weather events and cardiovascular and respiratory diseases, while social and mental health effects are even less considered.  

 

How to cite: de Luca, C., Cavalieri, B., Baldassarre, B., Ommer, J., and Kalas, M.: Health integration in climate-related policies: evidence and gaps in the EU policy context  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20465, https://doi.org/10.5194/egusphere-egu24-20465, 2024.

EGU24-20786 | PICO | ITS2.12/CL0.1.4

Smart information system based on RS and GIS as an adaptation strategy for reducing mortality from heat waves  

Fabiola D. Yépez-Rincón, Alicia Avendaño, Sergio Fernández Delgadillo, Adrían L. Ferriño Fierro, Víctor H. Guerra Cobián, Roberto E. Huerta García, Bárbara González Méndez, Nelly L. Ramírez Serrato, Carlos J. Ábrego Góngora, Rebeca Pérez Ruiz, and Rogelio Aguilar Cruz

Multiple factors influence the risk of heat stroke and that, collectively, define the vulnerability of the population. This vulnerability can be physiologically differentiated by older adults and children, by gender, or due to the level of exposure to sporting activities or labor, among others. During the last two decades, hot extreme events are drastically increasing related to climate change and other climate phenomena such as El Niño event. The World Health Organization estimates that more than 70,000 heat-related deaths occurred in Europe during the last two weeks of August 2003 and almost 62,000 deaths during summer 2022. In Mexico, the record of heat-related deaths was set during the summer of 2023 when the Health Secretariat reported 373 deaths due to extreme heat events. The five ranking states were Nuevo León (27% of the cases), Sonora (20%), Baja California (14%), Tamaulipas and Veracruz (8% respectively), and 80% of them are located between the 25 to 31°Latitude North. To understand which the most influential factors for heat-related deaths are, this study analyzes the interaction between land surface temperature, spatial population dynamics, and the exposure-response relationship to urban form and the concentration of air pollution in the Monterrey Metropolitan Area. The paper will present the operational structure of a smart information system based on RS and GIS for planning a better and safer city life in San Nicolás de los Garza, the municipality that ranked first on heat-related deaths. In summary, results indicate the next highlights: (1) extreme heat waves are increasing every year in the metropolitan area, (2) urban heat islands are spatially and temporally located, therefore, (3) risk reduction and civil protection actions must include a holistic approach including warning early systems, social, labor and health care actions, (4) preventive policies must be implemented such as sustainable urban planning for population climate justice, (5) and adopting nature-based solutions. 

How to cite: Yépez-Rincón, F. D., Avendaño, A., Fernández Delgadillo, S., Ferriño Fierro, A. L., Guerra Cobián, V. H., Huerta García, R. E., González Méndez, B., Ramírez Serrato, N. L., Ábrego Góngora, C. J., Pérez Ruiz, R., and Aguilar Cruz, R.: Smart information system based on RS and GIS as an adaptation strategy for reducing mortality from heat waves , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20786, https://doi.org/10.5194/egusphere-egu24-20786, 2024.

EGU24-20931 | ECS | PICO | ITS2.12/CL0.1.4

How agricultural droughts are contributing to child undernutrition in sub-Saharan Africa 

Anna Dimitrova, Alexander Gershunov, and Tarik Benmarhnia

Countries in sub-Saharan Africa (SSA) have some of the highest levels of child malnutrition, with more than one-third of children under five in the region characterized as chronically undernourished. High reliance on subsistence farming, poor adoption of irrigation technologies, and variable climate conditions make populations in SSA highly vulnerable to malnutrition during droughts. We use anthropometric data for 520,734 children under the age of five from 34 countries in SSA collected between 1990 and 2022 in combination with high-resolution agricultural and climate data to estimate the association between agricultural droughts and child undernutrition in the region. We use global gridded data on the geographical distribution of crop areas for 15 major crops. Data on crop planting and harvesting dates are also collected for each crop. The Standardized Precipitation Evapotranspiration Index (SPEI), a multi-scalar drought index, is used to measure the intensity and spatial distribution of droughts during key periods of agricultural production (planting, growth, and harvesting) and of different duration (seasonal and long-lasting droughts). Our analysis shows that droughts during the crop-growing seasons are associated with an increased risk of child undernutrition in SSA. The findings presented in this study call for urgent action to improve drought monitoring and response in SSA where the risks to child health posed by global warming are considerable. Under climate change, the severity and frequency of extreme weather and climate events, including droughts, are projected to increase, which will place millions of children at risk of hunger unless timely action plans are taken to improve food security in the region.

How to cite: Dimitrova, A., Gershunov, A., and Benmarhnia, T.: How agricultural droughts are contributing to child undernutrition in sub-Saharan Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20931, https://doi.org/10.5194/egusphere-egu24-20931, 2024.

EGU24-947 | ECS | Orals | ITS4.1/CL0.1.7

Identifying the Transitions in the Stable Socio-Environmental System Due to Extreme Events  

Jagriti Jain, Deepak Khare, and Francisco Munoz-Arriola

The critical challenge in a hydrological system is to predict whether the system approaches a critical threshold. The urban centres are grappled by the extreme events especially floods with the shifts from one stable state to another in an urban socio-environmental system. Here, we identified the critical transitions of hydrological processes, including precipitation and runoff, by analyzing their shifting nature. Structural break-regression models, incorporating shifts in both mean and trend, are applied to the series.  The point of change indicates the transition within the system.  These models are then evaluated using two widely employed penalized likelihood criteria for multiple changepoints. These criteria strike a balance between the quality of model fit (measured by likelihood) and the consideration of parsimony. Two models are tested i.e., bisegmentation and penalised maximum likelihood with the white noise detection. The latter was found to be better fit to both precipitation and runoff for the three cities (Guwahati, Mumbai, and Dehradun) in India.

How to cite: Jain, J., Khare, D., and Munoz-Arriola, F.: Identifying the Transitions in the Stable Socio-Environmental System Due to Extreme Events , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-947, https://doi.org/10.5194/egusphere-egu24-947, 2024.

EGU24-2179 | ECS | Posters on site | ITS4.1/CL0.1.7

Analysis of the Fertilizer Footprint of Principal Crops in China: A Spatial Allocation Perspective 

Yifan Wu, Jingyu Liu, and Yong Geng

Utilizing the sophisticated Multi-Regional Input-Output Analysis (MRIO) approach, this investigation meticulously examines the nitrogen (N), phosphorus (P), and potassium (K) fertilizer footprints associated with predominant crops throughout various Chinese provinces. Crucial provinces, namely Heilongjiang, Jiangsu, Shandong, and Henan, manifest a pronounced geographical aggregation in fertilizer footprints. Intriguingly, Heilongjiang, Shandong, and Henan collectively represent 49.2% and 42.7% of the cumulative national footprint.

From a provisioning perspective, the assimilation of N, P, and K fertilizers predominantly gravitates towards Heilongjiang, Shandong, Henan, Jiangsu, and Anhui, cumulatively contributing 32.74%, 35.73%, and 36.48% to the nation's aggregate input. Distinctly, regions such as the Yangtze River Delta, Pearl River Delta, and the Beijing-Tianjin-Hebei conurbation emerge as paramount crop consumption hubs, with aggregate consumptions scaling to 4505.12 Gg, 1741.71 Gg, and 2026.57 Gg, respectively. Notably, the exogenous crop provisions in metropolises like Shanghai and Beijing play a pivotal role in shaping their N, P, and K footprints, quantified at 6.78%, 5.56%, and 5.79%, and 1.26%, 1.37%, and 1.71%, respectively.

Furthermore, three salient regions—the Northeastern Plains, the Huang-Huai-Hai Plains, and the Middle to Lower tracts of the Yangtze River—collectively encompass 57.4%, 66.1%, and 66.26% of the national N, P, and K footprints. Compellingly, the dynamics of crop footprint migration in provinces such as Henan, Heilongjiang, and Shandong appear to be predominantly modulated by wheat and corn.

In summation, this scholarly endeavor elucidates the intricate spatial delineation of the fertilizer footprint, its translocation mechanisms, and its intricate interplay with socio-economic and demographic paradigms, thereby laying a robust theoretical groundwork for augmenting fertilizer efficacy and championing the cause of sustainable agricultural practices.

How to cite: Wu, Y., Liu, J., and Geng, Y.: Analysis of the Fertilizer Footprint of Principal Crops in China: A Spatial Allocation Perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2179, https://doi.org/10.5194/egusphere-egu24-2179, 2024.

EGU24-2326 | ECS | Posters on site | ITS4.1/CL0.1.7

Shifts in water availability due to environmental flows 

Ye Zhao, Xiang Zhang, Shiyong Tao, Feng Xiong, Zhimin Deng, Jianping Bing, Shaofeng Yan, Jianfeng Liu, and Jun Xia

Human society is grappling with the need to supply reliable and affordable freshwater for growing populations without destroying ecosystems. Environmental flows (EF) have been considered, and implemented, as a promising approach to sustainable water systems since its inception. However, the persistent antagonism between EF and other water demands is questionable, as the loss of hydro-ecological functions due to excessive water withdrawal (WW) could be balanced by the compensatory benefits of EF (i.e., EF improves resilience). Here, we introduce a mathematical push-pull framework to demonstrate how can EF be applied to lead to shifts in water availability explicitly in terms of magnitude and frequency. Our case study in the Yangtze River Basin reveals that EF implementation improves water availability over long time scales. We determine a boundary between EF and WW that leads to an escape from or stabilization within a stable equilibrium attraction. We use this boundary to define reasonable EF tailored to repeated, discrete WWs. Our results support the implementation of EF and its accompanying measures as part of the post-2030 eco-restoration framework.

How to cite: Zhao, Y., Zhang, X., Tao, S., Xiong, F., Deng, Z., Bing, J., Yan, S., Liu, J., and Xia, J.: Shifts in water availability due to environmental flows, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2326, https://doi.org/10.5194/egusphere-egu24-2326, 2024.

EGU24-2580 | ECS | Orals | ITS4.1/CL0.1.7

The safe operating spaces for grazing in China’s drylands 

Changjia Li, Bojie Fu, Shuai Wang, Lindsay Stringer, Wenxin Zhou, and Zhuobing Ren

Degradation of ecosystems can occur when certain ecological thresholds are passed below which ecosystem responses remain within ‘safe ecological limits’. Ecosystems such as drylands are sensitive to both aridification and grazing, but the combined effects of such factors on the emergence of ecological thresholds beyond which ecosystem degradation occurs has yet to be quantitatively evaluated. This limits our understanding on ‘safe operating spaces’ for grazing, the main land use in drylands worldwide. Here we assessed how 20 structural and functional ecosystem attributes respond to joint changes in aridity and grazing pressure across China´s drylands. Gradual increases in aridity resulted in abrupt decreases in productivity, soil fertility and plant richness. Rising grazing pressures lowered such aridity thresholds for most ecosystem variables, thus showing how ecological thresholds can be amplified by the joint effects of these two factors. We found that 44.4% of China’s drylands are unsuitable for grazing due to climate change-induced aridification, a percentage that may increase to 50.8% by 2100. Of current dryland grazing areas, 8.9% exceeded their maximum allowable grazing pressure. Our findings provide important insights into the relationship between aridity and optimal grazing pressure and identify safe operating spaces for grazing across China’s drylands.

How to cite: Li, C., Fu, B., Wang, S., Stringer, L., Zhou, W., and Ren, Z.: The safe operating spaces for grazing in China’s drylands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2580, https://doi.org/10.5194/egusphere-egu24-2580, 2024.

The analysis of global catastrophic events often occurs in isolation, simplifying their study. In reality, risks cascade and interact. Therefore, it is essential to consider the interconnected nature of global risks. This investigation explores the interplay between nuclear winter and planetary boundaries. It may seem reasonable to assume that respecting planetary boundaries, which define a safe operating space for the planet, is preferable before a nuclear war. However, that does not always seem to be the case. For instance, increased nitrogen emissions today could serve as a nutrient buffer during nuclear winter. Contrastingly, mitigating climate change, means an even larger temperature drop in nuclear winter in comparison with pre-industrial times. This exploratory study also highlights planetary boundaries that could enhance human survival if we adhere to their limits, both presently and after a nuclear war. The best example being biosphere integrity, as conserving it has no direct downsides and would make the Earth system more resilient to resist the shock of a nuclear winter.

How to cite: Jehn, F. U.: Anthropocene Under Dark Skies: The Compounding Effects of Nuclear Winter and Overstepped Planetary Boundaries, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2773, https://doi.org/10.5194/egusphere-egu24-2773, 2024.

EGU24-4134 | ECS | Orals | ITS4.1/CL0.1.7

Resilience of the AMOC 

Valérian Jacques-Dumas, Christian Kühn, and Henk A. Dijkstra

The Atlantic Meridional Overturning Circulation (AMOC) is a crucial part of the climate system that carries warm and saline water towards the northern Atlantic and is an important component in the global meridional heat transport. However, the AMOC is a so-called “tipping element”: there is observational evidence that it is in a bistable regime and may thus collapse under anthropogenic greenhouse gas emissions. Bi-stability has also been found in a hierarchy of models, from a simple two-box model up to a CMIP5 global climate model (CESM1). Considering a possible upcoming tipping, it is critical to assess how likely the AMOC is to undergo a collapse under different greenhouse gas forcing scenarios.  This issue is tightly related to the notion of resilience, which refers to the ability of a system to sustain a certain forcing while remaining in its original state or to return to its original state after being displaced.

Studying the resilience of the AMOC requires to observe its collapse, which is very difficult due to its rarity, especially in very complex models. That is why we use a rare-event algorithm called Transition-Adaptive Multilevel Splitting (TAMS). Given a certain definition of the current-day and collapsed AMOC, TAMS pushes trajectories in the direction of a collapse at a much lower cost than Monte-Carlo simulations. This method outputs typical collapse trajectories starting from a present-day AMOC, under a certain chosen hosing flux. This process is repeated for a wide range of freshwater forcings. From those trajectories, we extract observables (e.g. the AMOC strength), which are scalar functions that are interpreted as resilience observables. By monitoring these observables, we can rank different climate change scenarios depending on the risks they impose on the AMOC. Moreover, we relate these observables to existing mathematical definitions of resilience. Finally, we determine which observables are best suited to describe the resilience of the  AMOC, with a focus on those that can be measured in the field.

How to cite: Jacques-Dumas, V., Kühn, C., and Dijkstra, H. A.: Resilience of the AMOC, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4134, https://doi.org/10.5194/egusphere-egu24-4134, 2024.

EGU24-6874 | Orals | ITS4.1/CL0.1.7 | Highlight

Assessing impacts of Earth system tipping points on human societies  

Richard Betts, James Dyke, Elizabeth Fuller, Laura Jackson, Laurie Laybourn-Langton, Norman Steinert, and Yangyang Xu

Assessments of climate change effects on humans and ecosystems have previously included only limited information on the consequences of climate tipping points. While some national evaluations have touched on tipping point implications, assessment has been largely qualitative, with minimal quantitative analysis. Understanding and quantification of impacts of tipping points is recognised as a significant knowledge gap, and improving the research base in this area is essential for climate risks to be fully evaluated.

This presentation examines the current knowledge of Earth system tipping point impacts on people, exploring the evidence on impacts from individual tipping points, and assessing specific sectors and their vulnerability to these tipping points. Localised effects arise when climate tipping points, such as permafrost thaw and forest dieback, are crossed. These effects stem from land surface changes and alterations in regional climates and weather extremes. Global impacts manifest through large-scale shifts in atmospheric and oceanic circulations, altering global warming rates and sea level rise. Oceanic dynamics, like collapse of the Atlantic Meridional Overturning Circulation, can reshape regional climates and cause widespread shifts in temperature and precipitation patterns. Similarly, cryospheric tipping points, such as marine ice cliff collapse, have the potential to accelerate sea level rise, affecting flooding hazards like coastal inundation. Biosphere tipping points, such as Amazon dieback, intensify greenhouse gas concentrations, hastening global warming and its associated extreme weather events, regional climate shifts and sea level rise.

All these have the potential to impact the security of water, food and energy, human health, ecosystem services, communities and economies. The body of evidence varies across tipping points and sectors, but the implications for profound impacts across all areas of human society are clear.

How to cite: Betts, R., Dyke, J., Fuller, E., Jackson, L., Laybourn-Langton, L., Steinert, N., and Xu, Y.: Assessing impacts of Earth system tipping points on human societies , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6874, https://doi.org/10.5194/egusphere-egu24-6874, 2024.

EGU24-7633 | ECS | Orals | ITS4.1/CL0.1.7 | Highlight

Achieving net zero greenhouse gas emissions critical to limit climate tipping risks 

Annika (Ernest) Högner, Tessa Möller, Carl-Friedrich Schleussner, Samuel Bien, Niklas H. Kitzmann, Robin D. Lamboll, Joeri Rogelj, Jonathan F. Donges, Johan Rockström, and Nico Wunderling

Under current emission trajectories, at least temporarily overshooting the Paris global warming limit of 1.5 °C above pre-industrial levels is a distinct possibility. Permanently exceeding this limit would substantially increase the risks of triggering several climate tipping elements with associated high-end impacts on human societies and the Earth system. It is essential to assess this risk under emission pathways that temporarily overshoot 1.5 °C. Here, we investigate the tipping risks associated with a number of policy-relevant future emission scenarios, using a stylised Earth system model that comprises four interconnected core tipping elements. Assessing tipping risks in the year 2300, we find a non-linear increase for overshoots that exceed 1.8 °C peak temperature or persist above 1.5 °C beyond the end of the 21st century. Scenarios following current policies or pledges lead to high tipping risk of 30% (median) and more, with uncertainty from climate sensitivity and carbon-cycle feedbacks translating to large uncertainties in tipping risk (45% and more) for these scenarios. Further, we show that on multi-century timescales achieving and maintaining at least net-zero greenhouse gas emissions is paramount to minimise tipping risks. Our results underscore that stringent emission reductions in the current decade in line with the Paris Agreement 1.5 °C limit are critical for planetary stability.

How to cite: Högner, A. (., Möller, T., Schleussner, C.-F., Bien, S., Kitzmann, N. H., Lamboll, R. D., Rogelj, J., Donges, J. F., Rockström, J., and Wunderling, N.: Achieving net zero greenhouse gas emissions critical to limit climate tipping risks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7633, https://doi.org/10.5194/egusphere-egu24-7633, 2024.

The Anthropocene is the current geological epoch characterized by co-evolutionary dynamics between human societies and the Earth system. Linking biogeophysical and social processes is therefore essential to understand current developments in the Earth system. Especially the agricultural sector is a key driver of land system change, biodiversity loss, soil degradation, and a major contributor to global greenhouse gas emissions. To analyse and understand the mechanisms of these interactive systems, we developed the model of Integrated Social-Ecological rEsilient lanD Systems (InSEEDS), which couples the Dynamic Global Vegetation Model LPJmL with the agent-based modeling framework copan:CORE. LPJmL simulates the biogeophysical processes of the Earth system on a global 0.5° grid, in particular the terrestrial carbon, water, and nitrogen cycle, and can model, for example, plant and crop growth or water and fertilizer consumption. Various agricultural management practices can also be modeled, such as tillage, mulching, or cover crop cultivation. copan:CORE, on the other hand, can instantiate agents that reflect the behavior of farmers, management decisions, or interactions of the social world in different regions.
We here describe this novelty of World-Earth modeling and present the first exemplary application of the coupled model system which explores potential pathways for sustainable agricultural practices to spread. In this example we compare the potential social spreading of conservation tillage practices in contrast to conventional tillage practices based on the distribution of two different farmer types in the model, so-called agent functional types.

How to cite: Breier, J.: The InSEEDS Model - coupling LPJmL and copan:CORE towards an integrated human-earth system model of regenerative land-system change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7670, https://doi.org/10.5194/egusphere-egu24-7670, 2024.

EGU24-7905 | ECS | Orals | ITS4.1/CL0.1.7

Reviewing climate tipping point interactions and cascades under global warming 

Nico Wunderling and Anna von der Heydt and the GTPR-tipping-interactions-team

Climate tipping elements are large-scale subsystems of the Earth that may transgress critical thresholds (tipping points) under ongoing global warming, with substantial impacts on biosphere and human societies. While recent scientific efforts have improved our knowledge on individual tipping elements, the interactions between them are less well understood. Also, the potential of individual tipping events to induce cascading tipping elsewhere, or stabilize other tipping elements is largely unknown. As a contribution to the Global Tipping Points Report (GTPR) 2023 for COP28, we mapped out the current state of the literature on interactions between climate tipping elements. We find that tipping elements in the climate system are closely interacting, meaning a substantial change in one will have consequences for subsequently connected tipping systems. A majority of interactions between climate tipping systems are destabilising. While confirmation or rejection through future research is necessary, it seems possible that interactions between climate tipping systems destabilise the Earth system in addition to climate change effects on individual tipping systems. Further, we are quickly approaching global warming thresholds where tipping system interactions become relevant, because multiple individual thresholds are being crossed. Concretely, tipping cascades can neither be ruled out on centennial to millennial timescales at global warming levels between 1.5–2.0°C, nor on shorter timescales if global warming would surpass 2.0°C. To address crucial knowledge gaps in tipping system interactions, we propose four strategies forward combining observation-based approaches, Earth system modelling expertise, computational advances, and expert knowledge.

How to cite: Wunderling, N. and von der Heydt, A. and the GTPR-tipping-interactions-team: Reviewing climate tipping point interactions and cascades under global warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7905, https://doi.org/10.5194/egusphere-egu24-7905, 2024.

EGU24-10861 | Posters on site | ITS4.1/CL0.1.7

A tool for objective detection of abrupt transitions in CMIP6 models 

Valerio Lembo, Susanna Corti, Joran Angevaare, and Sybren Drijfhout

We present here a tool for the detection of abrupt transitions in CMIP6 model outputs, that is aimed to update and extend the catalog of tipping points presented in Drijfhout et al. 2015, based on the evaluation of CMIP5 intercomparison.

The tool consists of three fundamental steps: 

  • Data manipulation: model outputs are sampled according to the user’s preferences, aggregated along the integration period and interpolated to a common grid for the whole multi-model ensemble. A 10-years moving average is also applied;
  • Criteria for abrupt transitions: Criteria for the detection of abrupt transitions are computed and combined. These are: exceedance of the preindustrial 99-percentile standard deviation, exceedance of the preindustrial 99-percentile jump over 10 years period, exceedance of the preindustriak 99-percentile yearly anomaly for each year in the last 30 years of the simulation, p-value of a Kolmogorov-Smirnov hypothesis test for normality of the distribution;
  • Masking and clustering: grid points for which the time series of anomalies with respect to preindustrial conditions that satisfy at least 3 out of 4 of the criteria illustrated above are selected. Successively, grid points are clustered in order to exclude sparse points and highlight significant regions affected by widespread abrupt transitions;

We present a preliminary analysis demonstrating the usage of this tool on a set of ocean-sea-ice-related quantities for a number of models participating in CMIP6 project under disparate SSP scenarios. 

How to cite: Lembo, V., Corti, S., Angevaare, J., and Drijfhout, S.: A tool for objective detection of abrupt transitions in CMIP6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10861, https://doi.org/10.5194/egusphere-egu24-10861, 2024.

EGU24-12076 | ECS | Orals | ITS4.1/CL0.1.7 | Highlight

Interpretable Early Warning Signals in Large Human Groups, using Machine Learning in an Online Game-experiment 

Guillaume Falmagne and Anna B Stephenson

Understanding the emergent dynamics – in particular critical transitions – in complex social-ecological systems is key to foster positive social transformations in the Anthropocene era. Regime shifts in some ecosystems may be preceded by statistical early warning signals, but systems where such signals can be tested systematically are elusive. The r/place game hosted by Reddit is a social experiment that provides data for thousands of subsystems that can undergo critical transitions. It is therefore an excellent testbed for comparing the performance of various warning indicators. In r/place, millions of users collaborated to build many discernible drawings on a canvas of pixels. A drawing undergoes a transition when it is rapidly replaced by another. We build an early warning signal indicator that uses machine learning to combine the predictive power of a number of time-dependent and system-specific variables, and we show that its performance far exceeds that of standard indicators. For example, when training the algorithm and testing its performance on separate parts of the 2022 r/place, we detect half of the transitions coming in less than 20 minutes with only a 0.6% false positive rate. The performance only slightly decreases when training on 2022 data and testing on the 2023 experiment, showing that the predictive power holds across significantly different setups. We use SHAP values to elucidate the drivers of any given warning and highlight generic properties of warnings in online social systems. Some properties, such as a decreasing return time, are at odds with standard statistical indicators. Where sufficient data is available, our tool and resulting insights can contribute to warn of – and possibly trigger or avoid – macroscopic social and ecological change.

How to cite: Falmagne, G. and Stephenson, A. B.: Interpretable Early Warning Signals in Large Human Groups, using Machine Learning in an Online Game-experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12076, https://doi.org/10.5194/egusphere-egu24-12076, 2024.

EGU24-12856 | ECS | Posters on site | ITS4.1/CL0.1.7

Global terrestrial ecosystem resilience: a high-resolution multivariate analysis of patterns and drivers 

Nielja Knecht, Ingo Fetzer, and Juan Rocha

Natural terrestrial ecosystems in different parts of the world have been losing resilience in the past decades. Such losses of resilience can be the precursors for regime shifts on local or regional scales that can have large impacts on ecosystem structure and function as well as nature’s contributions to people. Drivers of resilience loss include mainly changes in the mean and variability of temperature and precipitation, and anthropogenic land modifications of adjacent or remote ecosystems.

Global assessments of ecosystem resilience often exclude areas with direct anthropogenic land use changes and focus instead on remnant natural ecosystems. However, for regional stakeholders it is important to understand how land-use and zoning decisions may affect the resilience of remaining ecosystems and the risk of critical transitions.

In this study, we conduct a high-resolution global assessment of terrestrial ecosystem resilience losses, using time series of multiple remotely-sensed ecosystem indicators, and employing a range of early warning signals. We also evaluate the importance of different climatic and anthropogenic drivers at a local scale of administrative units in causing the detected changes in resilience. This allows us to get a comprehensive and robust understanding of different dimensions of change in global ecosystem resilience and their locally relevant drivers of change.

How to cite: Knecht, N., Fetzer, I., and Rocha, J.: Global terrestrial ecosystem resilience: a high-resolution multivariate analysis of patterns and drivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12856, https://doi.org/10.5194/egusphere-egu24-12856, 2024.

EGU24-13183 | ECS | Orals | ITS4.1/CL0.1.7

Climate Change and Social- Ecological Vulnerability Index in the Brazilian Amazon: A study with a cascade model approach 

Moara Almeida Canova, Bianca Rius, João Darela Filho, and David Montenegro Lapola

The Brazilian Amazon is a powerful Ecosystem Service (ES) provider. Simultaneously, many Amazonian local communities still preserve an intrinsic economic and cultural relationship in this Social-Ecological System. Paradoxically, the region concentrates a significant portion of the nation's poorest people, demonstrating the risks and susceptibility to socio-ecological vulnerability that region. Thus, the Amazon Forest dieback hypothesis predicts that the increased CO2 (eCO2), rising temperatures and droughts may push the forest toward a tipping point, which would bring a new composition of ES and would reflect on regional economic - cultural ways of living, as well as, social wellbeing and health. Hence, the research employed a cascade model using the Functional Diversity (FD) approach. The aim was to assess the impact of climate changes on CO2 storage related to Ecosystem Services and their implications for the adaptation capacity of both rural and urban populations in the Brazilian Amazon. The initial analysis, using the CAETE model, evaluated vegetation FD responses in a scenario of 50% precipitation reduction. This revealed a shift in plant composition towards drought-related strategies, leading to a 37-49% reduction in total carbon storage in the basin, resulting in increased carbon release into the atmosphere. This result translates direct impacts to global and local climate regulation and indirect to shifting of water flux and to native provisioning services. The second evaluating was on social dimension ambit, through drafting of Social Ecological Vulnerability Index (SEVI) with secondary data of the municipalities of Manaus, Itacoatiara e Silves in the state of Amazonas and Ilha de Cotijuba in the Belém city in the state of Pará. The SEVI points out that the common factor of the vulnerability among the municipalities was the indicators of the socio-climate exposure for susceptibility to disasters, to rising temperature and FD changes. The SEVI result summed to FD modelling demonstrate that the social well-being of communities is threated due to the impacts on the native ES, even though they are placed in the one of most biodiverse forest from the globe. In addition, the susceptibility to diseases related to climate change increases in the regions greater urbanized (score 2.5, in the range from 0 low to 4 high vulnerability) with in turn can undermine the public health system in the urban centres in expanding in the Amazonia. Thus, the SEVI reveals that the impacts, stemming from the shifting FD of the modelled plant community, do not merely pose a distant threat to social well-being, health, and income; instead, they exacerbate socio-ecological vulnerability. In view that, people recognize and link hazards in infrastructure (ES for erosion control), mobility, and food supply (ES for water flow, fish, and wild food). Therefore, all the results support the challenges for the development of public policies of climate adaptation involving social health, future maintenance of provisioning native ES, above all in the municipalities with inadequate socioeconomic indicators

How to cite: Almeida Canova, M., Rius, B., Darela Filho, J., and Montenegro Lapola, D.: Climate Change and Social- Ecological Vulnerability Index in the Brazilian Amazon: A study with a cascade model approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13183, https://doi.org/10.5194/egusphere-egu24-13183, 2024.

EGU24-13292 | ECS | Orals | ITS4.1/CL0.1.7

Using biosphere metrics to assess the Planetary boundary for functional biosphere integrity 

Fabian Stenzel, Jannes Breier, Johanna Braun, Karlheinz Erb, Dieter Gerten, Sarah Matej, Helmut Haberl, Sebastian Ostberg, Nicolas Roux, Sibyll Schaphoff, and Wolfgang Lucht

In the recent update of the Planetary Boundaries framework, Richardson et al. propose to use human appropriation of net primary productivity (HANPP) as a new indicator for the functional biosphere integrity boundary. They provide a planetary scale analysis and suggest to further complement this by an ecological metric.

To aid with the spatially explicit analysis of both HANPP and an ecological metric in an automated and easy way, we developed the "biospheremetrics" R package. The package combines 2 complementary metrics:

The BioCol metric operationalizes the HANPP framework in order to represent a meaningful Planetary Boundary indicator, and is accompanied by the EcoRisk metric, which quantifies biogeochemical and vegetation structural changes as a proxy for the risk of ecosystem destabilization. Both metrics are computable in a dynamic global vegetation modelling framework.

We spatially explicitly analyse both metrics over the past 500 years with simulations of the dynamic global vegetation model LPJmL and find that presently (period 2007-2016), large regions show modification and extraction of >25% of the preindustrial potential net primary production, leading to drastic alterations in key ecosystem properties and suggesting a high risk for ecosystem destabilization. In consequence of these dynamics, EcoRisk shows particularly high values in regions with intense land use and deforestation, but also in regions prone to impacts of climate change such as the arctic and boreal zone.

We additionally show how both metrics could be combined to inform the Planetary Boundary of functional biosphere integrity, compare our results with other spatially explicit global biosphere integrity metrics and discuss the setting of (provisional) thresholds.

How to cite: Stenzel, F., Breier, J., Braun, J., Erb, K., Gerten, D., Matej, S., Haberl, H., Ostberg, S., Roux, N., Schaphoff, S., and Lucht, W.: Using biosphere metrics to assess the Planetary boundary for functional biosphere integrity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13292, https://doi.org/10.5194/egusphere-egu24-13292, 2024.

EGU24-14873 | ECS | Posters on site | ITS4.1/CL0.1.7

Assessing historical and potential future Planetary Boundary transgressions in a consistent modelling framework 

Johanna Braun, Dieter Gerten, Jannes Breier, Fabian Stenzel, Constanze Werner, and Wolfgang Lucht

In an attempt to define a safe operating space for humanity, the Planetary Boundary (PB) framework proposes precautionary limits to human interference with nine critical Earth system processes. However, quantitative assessments of these limits and past, present or potential future statuses and transgressions of PBs are (i) inflicted by differences in definitions, data and models used and (ii) require process-based models of the Earth system in the absence of globally available observational datasets on the PB control variables. To advance such process-based and consistent PB quantifications for terrestrial PBs (land system change, biosphere integrity, freshwater change, biogeochemical flows), we developed an R based software package, “boundaries”, for calculation and visualization of PBs based on outputs from the global terrestrial biosphere model LPJmL. The coupled, spatiotemporally explicit and dynamic simulation of the biogeochemical processes underlying the control variables in LPJmL allows for calculation of the temporal evolution of PB statuses, i.e. if, where and how strongly boundaries are transgressed, at different scales (for both planetary and corresponding subglobal boundaries from regional to grid cell scale).

Next to a short technical overview on boundaries and its structure, the poster shows calculated current spatially-explicit statuses of the four PBs considered as well as their simulated evolution during past decades, based on one consistent modelling framework and applying the latest PB definitions. In addition to contributing to a better understanding of temporal trajectories, spatial patterns and drivers of PB transgressions, boundaries can be applied to evaluate future scenarios in terms of their PB impacts and potentials to return to a safe space within PBs. As one potential critical PB trade-off, the poster focuses on different land-based carbon dioxide removal (CDR) strategies for reducing pressures on the climate change PB. The scenarios’ results show the importance of dietary changes towards less livestock products to release pasture areas for CDR. If forests can be restored on spared land, pressures on multiple PBs could be synergistically alleviated.

How to cite: Braun, J., Gerten, D., Breier, J., Stenzel, F., Werner, C., and Lucht, W.: Assessing historical and potential future Planetary Boundary transgressions in a consistent modelling framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14873, https://doi.org/10.5194/egusphere-egu24-14873, 2024.

EGU24-15269 | ECS | Orals | ITS4.1/CL0.1.7

Advancing Planetary Boundary Science 

Levke Caesar, Niklas Kitzmann, and Johan Rockström

While Planetary Boundary science has advanced tremendously over the past decades, we still lack a deep understanding of the intricate, yet pivotal connections between many biological and physical functions of the Earth system. This is of grave concern, since the stability of the planet and interactions between its components are the foundation of human civilization. Moreover, as it stands, science only has the resources to measure and analyze the planet’s vital signs every 6-8 years (Rockström et al. 2009, Steffen et al. 2015, Richardson et al., 2003), and our imperfect measurement framework has some worrying blind spots.
To address these challenges, the Potsdam Institute for Climate Impact Research and its partners are launching a major scientific effort to close the knowledge gaps, both in terms of our ability to model how the Earth system evolves under the pressure of human activity, as well as our ability to measure the state of the Earth system with high temporal resolution. This will culminate in an annual Planetary Boundary (PB) Health Check, conceived and reviewed by a diverse international scientific and stakeholder community. Employing cutting-edge Earth-system and tipping-point modelling, ambitious whole-Earth monitoring, and exploring artificial-intelligence-based big-data analytics, the Health Check shall offer a comprehensive, timely, and unparalleled assessment of the planet's health. With yearly updates of PB transgressions at its core, the Health Check will further develop the boundary measures themselves and provide important context, e.g. via case studies and policy implications.  It will reveal current risks due to ongoing transgression of PBs and develop transformation pathways to guide global development back to Earth’s safe operating space. Besides peer-reviewed publications, these results will be communicated to the public using state-of-the-art visualizations and communication partnerships.

In this presentation we will give details about this new science initiative, the partners we work with, out short and long-term goals and give an overview of involvement opportunities in this rapidly growing project.

References

Rockström, J., Steffen, W., Noone, K. et al. A safe operating space for humanity. Nature 461, 472–475 (2009). https://doi.org/10.1038/461472a
Steffen, W. et al. ,Planetary boundaries: Guiding human development on a changing planet.Science347,1259855(2015).DOI:10.1126/science.1259855 
Richardson, K. et al., Earth beyond six of nine planetary boundaries.Sci. Adv.9,eadh2458(2023).DOI:10.1126/sciadv.adh2458

How to cite: Caesar, L., Kitzmann, N., and Rockström, J.: Advancing Planetary Boundary Science, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15269, https://doi.org/10.5194/egusphere-egu24-15269, 2024.

EGU24-15331 | Orals | ITS4.1/CL0.1.7 | Highlight

Early opportunity signals of a tipping point in the UK’s second-hand electric vehicle market 

Chris Boulton, Joshua Buxton, and Timothy Lenton

The use of early warning signals to detect the movement of natural systems towards tipping points is well established. Here, we explore whether the same indicators can provide early opportunity signals (EOS) of a tipping point in a social dataset – views of online electric vehicle (EV) adverts from a UK car selling website (2018–2023). The daily share of EV adverts views (versus non-EV adverts) is small but increasing overall and responds to specific external events, including abrupt petrol/diesel price increases, by spiking upwards before returning to a quasi-equilibrium state. An increasing return time observed over time indicates a loss of resilience of the incumbent state dominated by ICEV advert views. View share also exhibits increases in lag-1 autocorrelation and variance consistent with hypothesised movement towards a tipping point to an EV-dominated market. Segregating the viewing data by price range and year, we find a change in viewing habits from 2023. Trends in EOS from EV advert views in low-mid price ranges provide evidence that these sectors of the market may have passed a tipping point, consistent with other evidence that second-hand EVs recently reached price parity with equivalent ICEV models. We provide a case study of how EOS can be used to predict the movement towards tipping in social systems using novel data.

How to cite: Boulton, C., Buxton, J., and Lenton, T.: Early opportunity signals of a tipping point in the UK’s second-hand electric vehicle market, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15331, https://doi.org/10.5194/egusphere-egu24-15331, 2024.

EGU24-15457 | ECS | Posters on site | ITS4.1/CL0.1.7

Assessing the stability of glacial-interglacial cycles: a stochastic model analysis of Earth system resilience 

Jakob S. Harteg, Nico Wunderling, Ann Kristin Klose, and Jonathan F. Donges

Earth system stability commonly denotes the continuation of the Holocene's relatively stable climatic and ecological conditions essential for human civilisation, whereas Earth resilience describes the Earth system’s ability to recover from significant disturbances, such as the transgression of any of the nine planetary boundaries. Given the nature of the Earth system as a non-autonomous, stochastic, non-linear system, it is not clear what exactly constitutes stable states, semi-stable states or mere transients. An alternative approach is to regard the glacial-interglacial cycle as a stable attractor and thus ask, how stable or resilient is this cycle to perturbations? The answer could provide insights relevant for contextualising the embedded transitions of critical tipping points happening on much shorter time scales.

In this study, we explore the stability and resilience of the glacial-interglacial cycle using a conceptual climate model developed by Talento and Ganopolski (2021), based on atmospheric CO2 concentration, global mean temperature, and global ice volume. The model is driven by astronomical forcing and replicates the ice age cycles of the last 800,000 years with a correlation of 0.86. Following the classical idea of Hasselmann, we have extended this model with additive noise to represent unresolved processes. An analysis of an ensemble of trajectories reveals periods of significant divergence and convergence, indicating that the model’s sensitivity to noise varies in response to astronomical forcing. We have further applied a transfer operator approach in an attempt to identify stable and decaying states of the model and to study their evolution with changes in astronomical forcing. Findings shed light on the complexity and sensitivity of the Earth system's dynamics.

References:
Talento, S., & Ganopolski, A. (2021). Reduced-complexity model for the impact of anthropogenic CO2 emissions on future glacial cycles. Earth System Dynamics12(4), 1275-1293.

How to cite: Harteg, J. S., Wunderling, N., Klose, A. K., and Donges, J. F.: Assessing the stability of glacial-interglacial cycles: a stochastic model analysis of Earth system resilience, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15457, https://doi.org/10.5194/egusphere-egu24-15457, 2024.

EGU24-16017 | ECS | Orals | ITS4.1/CL0.1.7

Assessing the relationship between forest structural diversity and resilience in a warming climate 

Mark Pickering, Agata Elia, Marco Girardello, Gonzalo Oton, Samuele Capobianco, Matteo Piccardo, Guido Ceccherini, Giovanni Forzieri, Mirco Migliavacca, and Alessandro Cescatti

Ecosystem resilience represents the capacity of an ecosystem to withstand and recover from external perturbations, an increasingly important property for ecosystem function in an era of escalating climate extremes and anthropogenic pressures. Whilst recent studies have related forest resilience to natural factors such as climate and biomass, the link between forest diversity and resilience is not yet understood.

 

This study quantifies the sensitivity of ecosystem resilience on forest diversity in Europe over the period 2003-2021. Two commonly used resilience indicators are considered based on MODIS kNDVI (kernel Normalized Difference Vegetation Index) data acquired at high spatial and temporal resolution: the 1-lag temporal autocorrelation, relating to the ecosystem memory, and the standard deviation, relating to the ecosystem stability. Forest diversity is expressed in terms of horizontal and vertical structural heterogeneity metrics derived from GEDI (LiDAR) (Light Detection and Ranging) acquisitions. A Random Forest (RF) model is leveraged to isolate the interplay between forest resilience and diversity metrics by disentangling possible confounding environmental variables such as climate. The RF model is then applied to retrieve local sensitivities in terms of Individual Conditional Expectations.

 

The work first finds that European forests with a higher level of vertical and horizontal structural diversity are systematically associated with higher resilience levels. The relationship is coherent across bio-geographical regions in Europe. Importantly, the emerging relation between forest resilience and forest diversity is consistent under increasing temperature patterns. This suggests that forest management targeted to higher levels of forest heterogeneity has the potential to offset the decline in forest resilience associated with the projected climate warming scenarios and the consequent increasing disturbance regimes.

How to cite: Pickering, M., Elia, A., Girardello, M., Oton, G., Capobianco, S., Piccardo, M., Ceccherini, G., Forzieri, G., Migliavacca, M., and Cescatti, A.: Assessing the relationship between forest structural diversity and resilience in a warming climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16017, https://doi.org/10.5194/egusphere-egu24-16017, 2024.

The climate of the Pleistocene is characterized by alternating cold (glacial) and warm (interglacial) periods. This cyclicity is mainly caused by the so-called Milankovitch cycles as a result of periodic changes in Earth’s orbital parameters. Many models have already successfully captured the non-linearities of the climate-cryosphere system responsible for the 100 kyrs cycles and the Mid-Pleistocene transition. However, these models widely differ in the number of explicit physical processes included and in the degree of complexity to solve them (from purely conceptual to Earth-system models). 

In this talk I will present a simple a-dimensional model that sequentially includes ice-sheet dynamics, ice aging and climate-cryosphere feedbacks. This model is able to capture the timing and shape of glacial cycles of the last 2 million years and can also be used to predict future glacial inceptions and thus the duration of the Anthropocene. Following different assumptions of human greenhouse gas emissions, I will show the expected timing of future glacial inceptions as well as the periodicities of the late Anthropocene glacial cycles.

How to cite: Alvarez-Solas, J.: Simulating glacial cycles from the Pleistocene to the end of the Anthropocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16345, https://doi.org/10.5194/egusphere-egu24-16345, 2024.

EGU24-17019 | ECS | Posters on site | ITS4.1/CL0.1.7

Remote sensing-based detection of resilience loss in the terrestrial water cycle 

Romi Lotcheris, Lan Wang-Erlandsson, and Juan Rocha

In the face of Anthropogenic change, ecosystems globally have shown evidence of resilience loss in the past several decades. By governing key processes in terrestrial ecosystems, the hydrological cycle is critical for Earth system stability. A resilient system is able to retain its function and structure in the face of external perturbations. Changes to driving hydrological variables, i.e., precipitation, evaporation, and soil moisture, are thought to be important drivers of terrestrial ecosystem resilience, and vice-versa through land-atmosphere feedbacks. Resilience has been estimated through time series analysis, where an increase in metrics of system recovery time can signal a loss of system resilience. To date, such methods of resilience analysis have not yet been applied to hydrological variables. As a result, there is limited quantification of the role of the water cycle in Earth system resilience.

Here, using remotely sensed time series data, we employ both early warning signals of resilience loss and indicators of rate-based tipping to asses resilience loss in key hydrological variables at the global scale. In doing so, we present a spatially distributed assessment of global water resilience, highlight regions vulnerable to resilience loss, and provide insights into how water resilience affects terrestrial ecosystem resilience. Changes to hydrological variables can have wide-reaching impacts on ecological (e.g., affecting biodiversity, ecosystem structure and function), and social systems (e.g., affecting crop yields in breadbasket regions). Here, we present a new dimension to the characterisation of regions vulnerable to resilience loss.

How to cite: Lotcheris, R., Wang-Erlandsson, L., and Rocha, J.: Remote sensing-based detection of resilience loss in the terrestrial water cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17019, https://doi.org/10.5194/egusphere-egu24-17019, 2024.

EGU24-17216 | Orals | ITS4.1/CL0.1.7

Transgression of the climate change planetary boundary critically affects the status of other boundaries 

Dieter Gerten, Arne Tobian, Johanna Braun, Jannes Breier, and Fabian Stenzel

To date, statues and trajectories of planetary boundaries have mostly been investigated separately, without fully quantifying if and to what extent transgression of one or more boundaries affects the status of respective others. To address this research gap, we have configured the state-of-the-art LPJmL Dynamic Global Vegetation Model so as to represent the terrestrial planetary boundaries (for land-system change, biosphere integrity, freshwater change, and biogeochemical/nitrogen flows) in an internally consistent, process-based framework. As the model simulates these boundaries’ underlying processes and control variables in a spatially explicit and dynamic manner, and as it also accounts for effects of climate change (a fifth planetary boundary considered through external forcing), it enables systematic studies of interactive effects among any of the five boundaries considered.

In a scenario study focused on here, we employed the model to systematically quantify the effects of different transgression levels of the climate change boundary (using gridded climate output from ten CMIP6 models for distinct atmospheric CO2 levels from 350 ppm to 1000 ppm) upon the land-system change boundary (areal extent of temperate, boreal and tropical forest biomes). Changes are analysed both by the end of this century and, to account for long-term legacy effects, by the end of the millennium, respectively. The simulations indicate that staying within the 350 ppm climate change boundary would stabilize the land-system change boundary, not inducing notable expansions or contractions of forest biome extent (on top of the historical shifts that have been brought about by anthropogenic deforestation). However, transgressing the climate change boundary beyond its zone of increasing risk (>450 ppm) is simulated to lead to increasingly substantial forest biome shifts, the higher the ppm level rises and the more time passes. Specifically, this involves a poleward tree-line shift, boreal forest dieback, expansion of temperate forest into today’s boreal zone, and a slight tropical forest expansion.

We furthermore find that these one-way interactions imply changes of the status of other planetary boundaries as well, as shifts in their control variables (e.g. large soil moisture and runoff anomalies) are simulated for the very areas where the forest biome shifts occur. Moreover, the vegetation changes are likely to provide feedback to the climate change boundary itself.

In additional simulations (making use of a planetary boundary simulation package linked to the LPJmL model), we investigate the historical evolution of the terrestrial planetary boundaries’ statuses during the past century. This examination suggests that the timing and spatial location of transgressions differs strongly among boundaries, with multiple boundaries crossed in the late 20th century, and transgression of the climate change boundary gaining increasing impact. Possible cascading and compound effects of these simultaneous transgressions, and particularly their likely aggravation in the future, require comprehensive analyses in further studies.

How to cite: Gerten, D., Tobian, A., Braun, J., Breier, J., and Stenzel, F.: Transgression of the climate change planetary boundary critically affects the status of other boundaries, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17216, https://doi.org/10.5194/egusphere-egu24-17216, 2024.

The capacity for tipping points in the climate system was elucidated decades ago by numerical climate models, which showed that nonlinearities could arise from physical interactions between the ocean, sea ice, and atmospheric components, leading to rapid shifts between qualitatively different states. However, there has been comparatively little work on physical interactions with the human component of the Earth system through numerical modeling due, in part, to the rarity of inclusion of the human system directly in Earth system models. Earth System economics provides a new approach for doing so, by proposing a particular set of physical variables that can be used as a basis for simulating such changes. These variables include spatially resolved population demography, time allocation to activities, a spatially resolved technosphere, and spatial networks that capture transportation fluxes. New global compilations of time use and technosphere data are helping to enable this approach, by quantifying the dependencies of material fluxes on time use and context. This opens the possibility of simulating long-term dynamics through motivated changes to time allocation, with outcomes dependent on the evolution of the technosphere and other coupled features of the Earth system. Examples will be discussed regarding how this approach can provide holistic, physically-grounded ways to identify possible nonlinearities and tipping points, by explicitly resolving aspects of human activities and technosphere changes, constrained by the conservation of mass, energy, and time.

How to cite: Galbraith, E.: Estimating possible nonlinearities in the Human-Earth system with Earth system economics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17717, https://doi.org/10.5194/egusphere-egu24-17717, 2024.

EGU24-18263 | ECS | Orals | ITS4.1/CL0.1.7

Resilience across the Amazon basin regions under increased drought frequency and severity 

Bianca Rius, Barbara Cardeli, Carolina Blanco, João Paulo Darela Filho, Marina Hirota, and David Lapola

The anticipated rise in the frequency of severe droughts triggered by events such as El Niño and abnormal warming of the Atlantic Ocean is expected to have profound impacts on the Amazon forest. However, whether the Amazon forest can effectively cope with changes in precipitation patterns and maintain its resilience remains to be determined. The impacts can vary across different regions of the Amazon due to the inherent heterogeneity in annual precipitation rate and periodicity in dry and wet periods. Furthermore, it is essential to highlight that resilience assessment frequently revolves around the ecosystem's ability to maintain or restore its carbon stock after a disturbance. Nonetheless, numerous other ecosystem processes and properties, such as evapotranspiration and functional diversity, might signal a shift in resilience before a consistent alteration in carbon stock becomes apparent. To address these concerns, our study will apply the trait-based vegetation model CAETÊ (CArbon and Ecosystem functional Trait Evaluation model). To comprehend the effects of an elevated frequency of decreased precipitation in the Amazon forest, we will apply a 20% precipitation reduction across three different frequencies: 7 years, 3 years, and 1 year. The model will be run across five distinct Amazon regions: northwest, center, south, northeast, and southeast. The assessment of resilience will encompass both resistance and recovery measures and will be evaluated using standard metrics such as carbon stock, while the analysis will extend to include other crucial indicators such as evapotranspiration, net primary productivity, and functional diversity. We anticipate uncovering differences in resilience among the regions, primarily influenced by natural climatic heterogeneity that selects distinct compositions of functional traits, leading to varying levels of functional diversity. Our hypothesis suggests that initially, the northwest region may experience a buffering effect from its naturally high precipitation rate. This could potentially result in more subtle impacts, even in the face of reduced precipitation. However, over time, other regions may demonstrate greater resilience, as their communities might show functional strategies acclimated to prolonged dry conditions and lower precipitation rates. Additionally, we also expect to observe a prior decrease in evapotranspiration and functional diversity before the eventual collapse of carbon stock and net primary productivity. This expectation is rooted in the anticipated intensification of environmental filtering, wherein the ecosystem undergoes a process of selecting more conservative adaptive strategies to deal with drier climatic conditions. By employing this innovative approach to assess resilience, incorporating diverse indicators beyond solely relying on carbon stock, we aim to significantly improve the understanding of Amazonian ecosystem dynamics under changing climatic conditions. Ultimately, our findings may unveil that the Amazon forests are potentially more susceptible to environmental changes than previously envisioned.

How to cite: Rius, B., Cardeli, B., Blanco, C., Darela Filho, J. P., Hirota, M., and Lapola, D.: Resilience across the Amazon basin regions under increased drought frequency and severity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18263, https://doi.org/10.5194/egusphere-egu24-18263, 2024.

EGU24-18581 | ECS | Posters on site | ITS4.1/CL0.1.7

Assessing the accuracy of GEDI for mapping resilience in the Amazon rainforest along a gradient of disturbance to recovery  

Emily Doyle, Chris Boulton, Hugh Graham, Tim Lenton, Ted Feldpausch, and Andrew Cunliffe

Understanding the resilience of tropical vegetation, its ability to recover from disturbance, is fundamental to assess future responses to environmental and climatic fluctuations. The Amazon rainforest has been identified as a potential tipping element in the Earth’s climate system and there is mounting concern over its persistent degradation. Extreme climate events and continued logging, forest fire and fragmentation threaten the Amazon’s structural integrity and its role as a carbon sink, with remotely sensed data providing observational evidence of resilience loss since the early 2000s. Fragmentation and degradation of tropical forest is suggested to slow recovery from perturbations, ensuing a potential to destabilise the rainforest and cause widespread transition from forest to savanna-like ecosystem state.

Remotely sensed LiDAR data provides a structural blueprint of forest canopy. The Global Ecosystem Dynamics Investigation (GEDI) spaceborne LiDAR characterises a new era of large-scale forest height quantification, with capabilities to further understand forest structure, and therefore forest response to perturbation across the entire Amazon. Although GEDI’s capabilities have been realised in boreal forest early disturbance monitoring, and to assess growth rates of tropical secondary forest, research thus far is yet to assess its ability to identify tropical forest of various degradation and recovery including logged, burned and fragmented over increasing timescales of recovery. Forest degraded by burning is characterised by different structure than selectively logged, or edge forest, and validating the ability of GEDI to represent these states is essential for identifying alternative forest states.  

Here, we investigate the potential of the GEDI LiDAR mission to map tropical forest along a gradient of degradation to recovery. A combination of ground data, MapBiomas secondary forest and burned area products are utilised to classify perturbed forest. We then assess the correspondence of GEDI waveform metrics including relative height and canopy cover, extracted from 2A and 2B products using the newly developed R package ‘chewie’, with airborne LiDAR across the Brazilian Amazon. This research will inform further tropical forest alternative-state study, whilst the assessment of GEDI’s structural capability to represent degraded forest types provides valuable information for forest restoration status to support post-degradation management strategies. 

How to cite: Doyle, E., Boulton, C., Graham, H., Lenton, T., Feldpausch, T., and Cunliffe, A.: Assessing the accuracy of GEDI for mapping resilience in the Amazon rainforest along a gradient of disturbance to recovery , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18581, https://doi.org/10.5194/egusphere-egu24-18581, 2024.

EGU24-18673 | Orals | ITS4.1/CL0.1.7

Impacts and state-dependence of AMOC weakening in a warming climate 

Jost von Hardenberg, Katinka Bellomo, and Oliver Mehling

All climate models project a weakening of the Atlantic Meridional Overturning Circulation (AMOC) strength in response to greenhouse gas forcing. However, the climate impacts of the AMOC decline in relation to other drivers of climate change, cannot be assessed from existing Coupled Model Intercomparison Project (CMIP) simulations. To address this issue, we conduct idealized experiments using the EC-Earth3 climate model. We compare an abrupt 4xCO2 simulation with an identical one, except we artificially fix the AMOC strength at preindustrial levels. With this design, we can formally attribute differences in climate change impacts between these two experiments to the AMOC decline. In addition, we quantify the state-dependence of AMOC impacts by comparing the aforementioned experiments with a preindustrial simulation in which we artificially reduce the AMOC strength. Our findings demonstrate that AMOC decline impacts are state-dependent, thus understanding AMOC impacts on future climate change requires targeted model experiments.

How to cite: von Hardenberg, J., Bellomo, K., and Mehling, O.: Impacts and state-dependence of AMOC weakening in a warming climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18673, https://doi.org/10.5194/egusphere-egu24-18673, 2024.

EGU24-18923 | ECS | Posters on site | ITS4.1/CL0.1.7

Rethinking the Intertwined Biosphere 

Chelsea Kaandorp, Juan Rocha, Lan Wang-Erlandsson, Cynthia Flores, Andrew Hattle, Henrik Österblom, and Carl Folke

Transformations towards sustainable futures can only be achieved with an advanced understanding of how human life is intertwined with the whole biosphere. Systems of people and nature are not separate entities but inherently connected across temporal and spatial scales. There is a dynamic interplay between the biosphere and the broader Earth system. Life in the biosphere has evolved with the basic building blocks of planet Earth, like water, carbon, nitrogen, and other biogeochemical cycles. Social conditions, such as health, culture, democracy, power, justice, equity, matters of security, and even survival, are interwoven with the Earth system and its biosphere resulting in a complex interplay of local, regional, and global interactions and dependencies.

In “The Intertwined Biosphere” project at the Anthropocene Laboratory, we explore empirical evidence of biosphere-Earth system dynamics since deep time and synthesise insights that can foster radical changes towards recognising humanity’s embeddedness in the world. By doing so, we aim to contribute to narratives that bridge human-nature dialectics to foster a deeper understanding of the critical interplay of humans as part of the living biosphere. In this presentation, we share our preliminary conceptual model of the biosphere as intertwined. We invite you to discuss human embeddedness in the biosphere and new directions for guiding human actions in the Anthropocene. What are the ontological and epistemological implications of understanding the Anthropocene biosphere as intertwined complex human-nature entanglements? How to study how life shapes its own living conditions?  

How to cite: Kaandorp, C., Rocha, J., Wang-Erlandsson, L., Flores, C., Hattle, A., Österblom, H., and Folke, C.: Rethinking the Intertwined Biosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18923, https://doi.org/10.5194/egusphere-egu24-18923, 2024.

EGU24-19347 | Orals | ITS4.1/CL0.1.7

The Planetary Boundaries Framework: Status (“PB3.0”) 

Katherine Richardson, Will Steffen, and Wolfgang Lucht and the PB3.0-Team

The planetary boundaries framework emerges from Earth system science and was developed to help guide the global community in its efforts to manage Anthroposphere interactions with the Earth’s bio-physical components. In the third iteration of the framework, PB3.0 (September 2023), six of the nine boundaries are found to be transgressed and anthropogenic pressure is increasing on all the boundaries earlier found to be exceeded. Metrics are, for the first time, proposed for all boundaries. Human Appropriation of Net Primary Production is proposed as the control variable for the function of the biosphere as photosynthesis represents the energy input supporting almost all life. The probability of achieving global climate goals is argued to be closely linked to the fate of global forests. Thus, the climate and biodiversity crises must be addressed together. Directions for the framework’s further development are discussed.

How to cite: Richardson, K., Steffen, W., and Lucht, W. and the PB3.0-Team: The Planetary Boundaries Framework: Status (“PB3.0”), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19347, https://doi.org/10.5194/egusphere-egu24-19347, 2024.

EGU24-19383 | Orals | ITS4.1/CL0.1.7

The new planetary boundary for freshwater change: key findings and their potential to guide water management and policy 

Miina Porkka, Vili Virkki, Lan Wang-Erlandsson, and Matti Kummu

The recent third planetary boundary (PB) assessment replaced the original PB for ‘freshwater use’ with a new PB for ‘freshwater change’. The new PB is defined by the percentage of global land area experiencing streamflow (blue water component of the PB) and root-zone soil moisture (green water) deviations from pre-industrial baseline conditions. Here, we first present the spatiotemporally explicit results of the comprehensive analysis underlying the new PB, and then discuss possible applications of the approach and the challenges related to providing meaningful guidance for water management and policy across scales.

We find a clear transgression of both the blue and green water components of the freshwater change PB already during the first half of the 20th century. Our spatiotemporally explicit analysis reveals a general pattern of drying across a significant portion of the tropics and subtropics, contrasting with wetting in temperate and subpolar regions as well as numerous highland areas. This overall pattern is likely attributed to alterations in precipitation patterns associated with global warming. Significant increases in streamflow and soil moisture deviations are also found in regions facing the highest direct human pressures, such as irrigation, flow regulation, and land use change. In many cases, both streamflow and soil moisture deviations have increased – underlining the influence of human impacts on the freshwater cycle as a whole.

While our analysis highlights regions undergoing the most substantial freshwater changes and their potential drivers, using the results to guide water policy and management remains challenging. Key knowledge gaps include our limited understanding of the (quantitative) driver–freshwater change–Earth system response relationships, and the mismatches between spatiotemporal scales of 1) human drivers of freshwater change, 2) the Earth system impacts of freshwater change, and 3) water management and governance institutions. We conclude our presentation by proposing a research agenda to bridge these gaps, with a goal to provide policy-relevant information on freshwater change that would enable a stronger adoption of an  Earth system perspective in water management and governance.

How to cite: Porkka, M., Virkki, V., Wang-Erlandsson, L., and Kummu, M.: The new planetary boundary for freshwater change: key findings and their potential to guide water management and policy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19383, https://doi.org/10.5194/egusphere-egu24-19383, 2024.

EGU24-19468 | Orals | ITS4.1/CL0.1.7

 Systematic detection of abrupt change and tipping points in TIPMIP  

Sina Loriani, Donovan Dennis, Jonathan Donges, Boris Sakschewski, and Ricarda Winkelmann

With ongoing anthropogenic emissions and ensuing accelerated climate change, the planet is increasingly leaving its long-stable Holocene state. In fact, recent assessments have shown that a range of climate tipping points are at risk of being crossed at warming levels well within temperature projections of the 21st century. However, such assessments have been largely based on expert judgement of scattered literature, with corresponding large uncertainties in critical thresholds and potential tipping dynamics. The Tipping Point Modelling Intercomparison Project (TIPMIP, www.tipmip.org) aims to close this research gap through a standardised framework for numerical experiments exploring tipping across systems and models. Built on precursory experiments, we here introduce the Tipping and Other Abrupt Events Detector (TOAD) method, to automatically identify spatial clusters of dynamically connected regions exhibiting tipping dynamics. This will serve as an evaluation scheme for the suite of experiments generated within the TIPMIP protocol. Overall, this systematic approach to tipping point risks at different levels of human pressures can inform quantification of planetary or Earth system boundaries to map out the safe and just operating space for humanity in the Anthropocene.

How to cite: Loriani, S., Dennis, D., Donges, J., Sakschewski, B., and Winkelmann, R.:  Systematic detection of abrupt change and tipping points in TIPMIP , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19468, https://doi.org/10.5194/egusphere-egu24-19468, 2024.

EGU24-19685 | ECS | Posters on site | ITS4.1/CL0.1.7

Rapid dietary change can foster desired food system transformations: lessons from past evolutions of dietary patterns. 

Vittorio Giordano, Marta Tuninetti, and Francesco Laio

The global food system is currently at a critical turning point as it is driving the planet’s trajectory towards exceeding 1.5 °C warming and crossing tipping points in the Earth system. It is responsible for one-third of global emissions and the primary cause of freshwater consumption and pollution, biodiversity loss and terrestrial ecosystem destruction. The prevalence of undernourishment is persistent, while unhealthy diets and widespread overnutrition cause diet-related chronic diseases and health damages. To achieve international agreements’ targets on climate and biodiversity its transformation is essential.

Rapid dietary change to more plant-based diets and reduced animal products consumption is a powerful leverage for plummeting the environmental and climate impacts of food habits. It has been referred to as one of the potential positive tipping points that can be harnessed to transform the global food system, profoundly altering its modes of operation. Nevertheless, there is limited empirical evidence regarding whether such non-linear dynamics occur in the food sector, resulting in an important gap in the identification of specific factors that can trigger a desired transition.

We propose a quantitative framework to identify historic and ongoing tipping dynamics in food system transformation. We first implement statistical analyses to explore the past evolution of the dominant dietary patterns within historical data series (1961-2020) of country-scale food supply quantities, across different food categories. We then unravel the drivers behind dietary patterns evolution in time (e.g., per capita GDP, cultural and social factors, supply patterns), also highlighting significant similarities across different countries, possibly suggesting coupled dietary evolutions. The outputs of our statistical framework provide ground for the analysis of past shifts in dietary patterns and the role that potential tipping elements driving dietary shifts - changes of normative consumer beliefs and behaviours, agricultural practices and policies - had in triggering food system transformations, or that may have in accelerating future desired transitions towards a more sustainable food system.

How to cite: Giordano, V., Tuninetti, M., and Laio, F.: Rapid dietary change can foster desired food system transformations: lessons from past evolutions of dietary patterns., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19685, https://doi.org/10.5194/egusphere-egu24-19685, 2024.

EGU24-19730 | ECS | Posters on site | ITS4.1/CL0.1.7

Next steps towards the Tipping Point Modelling Intercomparison Project (TIPMIP) 

Donovan Dennis, Jonathan Donges, Sina Loriani, Boris Sakschewski, and Ricarda Winkelmann

Anthropogenic climate change poses considerable risk to the stability of the Earth system. The consequences associated with crossing certain tipping thresholds, wherein relatively small-scale changes in the state of a specific tipping element may induce widespread and potentially irreversible feedbacks, are among the most severe. The Tipping Point Modelling Intercomparison Project (TIPMIP, www.tipmip.org) seeks to systematically investigate tipping risks for the Greenland and Antarctic ice sheets, the Atlantic Meridional Overturning Circulation, tropical and boreal forests as well as high-latitude permafrost  in order to both advance the understanding of the underlying  dynamics as well as to quantify the associated uncertainties around crossing such thresholds. Here, we discuss the initial proposed experimental protocols for TIPMIP for each domain (cryosphere, ocean, biosphere, fully coupled), the next  steps towards their implementation within the modelling community as well as the alignment with other ongoing and planned MIPs. 

How to cite: Dennis, D., Donges, J., Loriani, S., Sakschewski, B., and Winkelmann, R.: Next steps towards the Tipping Point Modelling Intercomparison Project (TIPMIP), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19730, https://doi.org/10.5194/egusphere-egu24-19730, 2024.

EGU24-20293 | Orals | ITS4.1/CL0.1.7

Using Ecotron experimentation to quantify planetary boundaries 

Nadia Soudzilovskaia, Francois Rineau, Jonas Schoelynck, Hans De Boek, and Ivan Nijs

As the world’s population grows at unprecedented rates, planetary-scale environmental forcing by humankind continues to push Earth system components out of the equilibrium state. The planetary boundaries framework provides an elegant and comprehensive tool to estimate the extent to which nine key processes of human-induced biosphere alteration affect the stability and resilience of Earth system. Yet quantifying planetary boundaries and especially the interactions between them, based on a process-based understanding of ecosystem functioning, remains a great challenge, as observations and experimentation in natural ecosystems typically provide only a narrow snapshot of a process in question. While conventional controlled environment facilities, such as growth chambers and advanced greenhouses provide a standard tool to simulate environmental change and disentangle processes controlling ecosystem functioning, the capacity of such systems to provide realistic quantifications of ecosystem tipping point is limited, due to (1) a typical focus on a single environmental change process, and (2) a use of simplified, small scale experimental ecosystems. In contrast, novel state-of-the-art terrestrial and aquatic Ecotron research facilities enable both (1) simulation of a wide range of natural environmental conditions, employing  highly realistic scenarios of environmental change, as well as (2) operating with natural ecosystems in their full complexity in replicated design.  An important advantage of ecotrons is a possibility of obtaining long-term (years to decennia scale) and high resolution (minutes-to-days) time series of continues observations of multiple ecosystem functions and their drivers, allowing to infer relations between those in a process-based manner. These advantages are increasingly acknowledged by the scientific community, as having a great potential to help obtaining experimental data to quantify the ecosystem tipping points, accounting for interactions between multiple forces driving planetary boundaries. I will discuss the framework of using a European network of Ecotrons and Ecotorn-like systems within AnaEE ERIC (Analysis and Experimentation on Ecosystems European Research Infrastructure Consortium) in the context of quantification of planetary boundaries, and will present a suit of a case studies illustrating assessments of cascading effects of land use change and climate change on ecosystem integrity, terrestrial above and belowground biodiversity, terrestrial and oceanic biogeochemical cycles, and soil moisture regime. I aim to inspire a discussion about new avenues in assessment of planetary boundary levels based on high throughput experimental and observational data obtained in ecotron-like experimental facilities.

How to cite: Soudzilovskaia, N., Rineau, F., Schoelynck, J., De Boek, H., and Nijs, I.: Using Ecotron experimentation to quantify planetary boundaries, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20293, https://doi.org/10.5194/egusphere-egu24-20293, 2024.

EGU24-20483 | Orals | ITS4.1/CL0.1.7

Feedbacks and social tipping: A dynamic systems approach to rapid decarbonization 

Sibel Eker, Charlie Wilson, Niklas Hohne, Mark McCaffrey, Irene Monasterolo, Leila Niamir, and Caroline Zimm

Social tipping points are promising levers for accelerating progress towards net-zero greenhouse gas emission targets. They describe how social, political, economic or technological systems can move rapidly into a new state if cascading positive feedback mechanisms are triggered. Analysing the potential for social tipping requires considering the inherent complexity of social systems and their feedbacks. Here, drawing on insights from an expert elicitation workshop, we outline a dynamic systems approach that entails i) a systems outlook involving interconnected feedback mechanisms alongside cross-system and cross-scale interactions, ii) directed data collection efforts to provide empirical evidence and monitoring of social tipping dynamics, and iii) global, integrated, descriptive modelling to project future dynamics and provide ex-ante evidence for interventions aiming to trigger positive feedback mechanisms. We argue how and why this approach will strengthen the climate policy relevance of research on social tipping.

How to cite: Eker, S., Wilson, C., Hohne, N., McCaffrey, M., Monasterolo, I., Niamir, L., and Zimm, C.: Feedbacks and social tipping: A dynamic systems approach to rapid decarbonization, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20483, https://doi.org/10.5194/egusphere-egu24-20483, 2024.

EGU24-20878 | Orals | ITS4.1/CL0.1.7

Socio-metabolic class conflicts in the Anthropocene 

Ilona M. Otto and Antonia Schuster

The Anthropocene epoch is characterized by an excessive use of natural resources and energy that drives the environmental destruction of the planet. However, large inequalities exist among different social groups that benefit to various degrees from the use of resources and energy, as well as among those suffering from the negative impacts of environmental destruction. In this paper, we systematically analyze these differences and propose a novel social stratification theory based not only on differences in terms of possessions or social status, but also on differences in how these groups can control and benefit from the planetary material cycles and energy flows or suffer the consequences of environmental degradation. Referring to consumption data, we propose six global socio-metabolic classes and show distinctive patterns in the energy use of these classes. More research is needed to reveal differences in the use of natural resources essential for maintaining the biosphere integrity, such as land, water, nitrogen, and phosphorus. Targeted policy measures that address excessive appropriation of energy and natural resources are needed, as are expansions in infrastructure and institutional change that supports the wellbeing of humankind, and especially of the most marginalized classes.

How to cite: Otto, I. M. and Schuster, A.: Socio-metabolic class conflicts in the Anthropocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20878, https://doi.org/10.5194/egusphere-egu24-20878, 2024.

EGU24-20891 | Posters on site | ITS4.1/CL0.1.7

Clams reveal the North Atlantic subpolar gyre has destabilised over recent decades 

Beatriz Arellano Nava, Paul R. Halloran, Chris A. Boulton, and Timothy M. Lenton

Amidst the ongoing climate crisis, there is a pressing need to assess the resilience of different components of the climate system. Two candidate tipping elements involve changes in circulation in the Atlantic Ocean, raising alarms about the potential consequences for the climate system and human societies. An approach to measure changes in resilience consists of assessing signs of critical slowing down by measuring changes in lag-1 autocorrelation and variance. However, this approach requires long-term, regularly spaced time-series, characteristics that are rare among observational records, especially in the ocean. The recent development of annually-resolved proxy records based on information encoded in bivalve shells provides a unique opportunity for assessing resilience in the marine environment. Here, we assess changes in resilience in the northern North Atlantic by measuring changes in lag-1 autocorrelation in a compilation of 29 bivalve-derived records. Our findings indicate that the marine environment has lost stability over the last decades over much of the North Atlantic sea shelves. Records that exhibit significant increasing trends in autocorrelation are highly sensitive to temperature variability over the subpolar gyre region, suggesting that the observed slowing down in variability may be associated with this system. Furthermore, bivalves reveal a basin-scale destabilisation episode preceding a documented regime shift in the northern North Atlantic circulation system around 1920, demonstrating their sensitivity to changes in resilience in circulation elements. Both findings suggest that the subpolar North Atlantic circulation system has lost resilience over recent decades and is potentially approaching a tipping point.

How to cite: Arellano Nava, B., Halloran, P. R., Boulton, C. A., and Lenton, T. M.: Clams reveal the North Atlantic subpolar gyre has destabilised over recent decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20891, https://doi.org/10.5194/egusphere-egu24-20891, 2024.

EGU24-21005 * | Orals | ITS4.1/CL0.1.7 | Highlight

Evolution of the polycrisis: Anthropocene traps that challenge global sustainability 

Peter Søgaard Jørgensen, Raf Jansen, Daniel Avila Ortega, Lan Wang-Erlandsson, Jonathan F. Donges, Henrik Österblom, Per Olsson, Magnus Nyström, Steve Lade, Thomas Hahn, Carl Folke, Garry Peterson, and Anne-Sophie Crepin

The Anthropocene is characterized by accelerating change and global challenges of increasing complexity and most recently by what some have called a polycrisis. Based on an adaptation of the evolutionary traps concept to a global human context, we explore whether the human trajectory of increasing complexity and influence on the Earth system could become a form of Anthropocene trap for humanity. We identify 14 Anthropocene traps and categorize them as either global, technology or structural traps. An assessment reveals that 12 traps (86%) could be in an advanced phase of trapping with high risk of hard-to-reverse lock-ins and growing risks of negative impacts on human well-being. Ten traps (71%) currently see growing trends in their indicators. Revealing the systemic nature of the polycrisis, we assess that Anthropocene traps often interact reinforcingly (45% of pairwise interactions), and rarely in a dampening fashion (3%). We end by discussing capacities that will be important for navigating these systemic challenges in pursuit of global sustainability. Doing so, we introduce evolvability as a unifying concept for such research between the sustainability and evolutionary sciences.

How to cite: Søgaard Jørgensen, P., Jansen, R., Avila Ortega, D., Wang-Erlandsson, L., Donges, J. F., Österblom, H., Olsson, P., Nyström, M., Lade, S., Hahn, T., Folke, C., Peterson, G., and Crepin, A.-S.: Evolution of the polycrisis: Anthropocene traps that challenge global sustainability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21005, https://doi.org/10.5194/egusphere-egu24-21005, 2024.

EGU24-21091 | Orals | ITS4.1/CL0.1.7

Safe and just Earth system boundaries 

Steven Lade and the Earth Commission

We present our paper published in Nature last year: https://www.nature.com/articles/s41586-023-06083-8. The work can be viewed as a "deep dive" into a subset of the planetary boundaries on dimensions of justice and operational spatial scales.

Abstract from the paper: The stability and resilience of the Earth system and human well-being are inseparably linked, yet their interdependencies are generally under-recognized; consequently, they are often treated independently. Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice). The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future.

This work is an output of the Earth Commission, an independent international scientific assessment initiative hosted by Future Earth. The Earth Commission is the scientific cornerstone of the Global Commons Alliance.

How to cite: Lade, S. and the Earth Commission: Safe and just Earth system boundaries, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21091, https://doi.org/10.5194/egusphere-egu24-21091, 2024.

EGU24-22274 | ECS | Orals | ITS4.1/CL0.1.7

Positive Tipping Points in the Food Systems: the Role of Scales 

Marta Tuninetti, Vittorio Giordano, Sara Constantino, Saverio Perri, Juan Rocha, Luana Schwarz, Jonathan F. Donges, Francesco Laio, and Simon Levin

The global food system is at a critical inflection point with rising awareness of the need for change and progress on several fronts, pertaining both human health and the environment. One of the ten critical transitions envisioned by the Food and Land Use Coalitions states that global diets need to converge towards local variations of the “human and planetary healthy diet” which includes more protective foods a diverse protein supply, and reduced consumption of sugar, salt and highly processed foods. 

Positive tipping points (PTP) offer a new perspective to support and boost the implementation of solutions for sustainable and healthy food systems. A PTP in the food system can be seen as critical points where targeted interventions lead to large and long-term consequences on the evolution of that system, profoundly altering its modes of operation.  While discussions on food PTP dynamics are an intriguing theoretical debate, we still lack empirical evidence if and how such dynamics unfold in practice, especially in the food sector. Literature on inducing positive tipping and feedback dynamics in sustainability transitions almost exclusively focuses on the energy sector, leaving an important gap in the empirical research on the specific enabling factors for triggering these dynamics in respect to food and global diets transformation.  

How do different organizational, geographical, and temporal scales should interact with each other to accelerate a transition to a sustainable food system? In this study we integrate complex network theory tools with systems’ emergent properties to better define multi-scale food systems dynamics. We develop indicators (with country resolution and global coverage) to synthesize the food system’s structure and its weak and strong points where the spread of positive changes can be maximized. This quantitative framework is aimed at supporting the actions of government in repurposed agricultural subsidies, targeted public food procurement, taxes and regulations on unhealthy food; and business in redesigning product portfolio based on the human and planetary health diet. 

How to cite: Tuninetti, M., Giordano, V., Constantino, S., Perri, S., Rocha, J., Schwarz, L., Donges, J. F., Laio, F., and Levin, S.: Positive Tipping Points in the Food Systems: the Role of Scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22274, https://doi.org/10.5194/egusphere-egu24-22274, 2024.

EGU24-111 | ECS | Orals | ITS1.10/CL0.1.9

CMIP6 precipitation and temperature projections for Chile 

Álvaro Salazar, Marcus Thatcher, Katerina Goubanova, Patricio Bernal, Julio Guitérrez, and Francisco Squeo

Precipitation and near-surface temperature from an ensemble of 36 new state‐of‐the‐art climate models under the Coupled Model Inter‐comparison Project phase 6 (CMIP6) are evaluated over Chile´s climate. The analysis is focused on four distinct climatic subregions: Northern Chile, Central Chile, Northern Patagonia, and Southern Patagonia. Over each of the subregions, first, we evaluate the performance of individual global climate models (GCMs) against a suit of precipitation and temperature observation-based gridded datasets over the historical period (1986-2014) and then we analyze the models’ projections for the end of the century (2080-2099) for four different shared socioeconomic pathways scenarios (SSP). Although the models are characterized by general wet and warm mean bias, they reproduce realistically the main spatiotemporal climatic variability over different subregions. However, none of the models is best across all subregions for both precipitation and temperature. Moreover, among the best performing models defined based on the Taylor skill score, one finds the so-called “hot models” likely exhibiting an overestimated climate sensitivity, which suggests caution in using these models for accessing future climate change in Chile. We found robust (90% of models agree in the direction of change) projected end-of-the-century reductions in mean annual precipitation for Central Chile (~-20% to ~-40%) and Northern Patagonia (~-10% to ~-30%) under scenario SSP585, but changes are strong from scenario SSP245 onwards, where precipitation is reduced by 10-20%. Northern Chile and Southern Patagonia show non-robust changes in precipitation across the models. Yet, future near-surface temperature warming presented high inter-model agreement across subregions, where the greatest increments occurred along the Andes Mountains. Northern Chile displays the strongest increment of up to ~6°C in SSP585, followed by Central Chile (up to ~5°C). Both Northern and Southern Patagonia show a corresponding increment by up to ~4°C. We also briefly discuss about the environmental and socio-economic implications of these future changes for Chile.

How to cite: Salazar, Á., Thatcher, M., Goubanova, K., Bernal, P., Guitérrez, J., and Squeo, F.: CMIP6 precipitation and temperature projections for Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-111, https://doi.org/10.5194/egusphere-egu24-111, 2024.

EGU24-1411 | Posters on site | ITS1.10/CL0.1.9

The North Atlantic climate variability in single-forcing large ensemble simulations with MPI-ESM-LR 

Holger Pohlmann and Wolfgang A. Müller

The origin of multi-decadal climate variability in the North Atlantic is under debate. The variability could be caused by oceanic internal variability or by external anthropogenic or natural forcing. We have produced a set of single-forcing historical simulations with the Max Planck Institute - Earth System Model (MPI-ESM) in low resolution (LR). The historical-like simulations consists of 30 ensemble members and the external forcing is from the Coupled Model Intercomparison phase 6 (CMIP6). Each set of simulation is forced by either only greenhouse-gases, total ozone, solar insolation, anthropogenic aerosols or volcanic aerosols. We present first results of our attribution of the climate signals in the North Atlantic region to the different single forcings.

How to cite: Pohlmann, H. and Müller, W. A.: The North Atlantic climate variability in single-forcing large ensemble simulations with MPI-ESM-LR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1411, https://doi.org/10.5194/egusphere-egu24-1411, 2024.

EGU24-1657 | Orals | ITS1.10/CL0.1.9

Climatological Evaluation of the Mei-yu Front Representation in CMIP6 

Gregor C. Leckebusch, Kelvin S. Ng, and Kevin I. Hodges

Given the significant socioeconomic impact of the East Asian Summer Monsoon (EASM), a critical area of investigation involves comprehending how the EASM and, consequently, the hydrological cycle over East Asia might change in future climates. To address this inquiry, reliable climate models must be employed. While assessments of model performance commonly concentrate on the generated precipitation amounts during the EASM period, it is important to note that the representation of dynamical components such as the Mei-yu front (MYF) are not frequently investigated. As model outputs may be correct for incorrect reasons, the dynamical components of the EASM might be misrepresented.
In this investigation, we scrutinized the representation of the MYF in historical simulations of 38 CMIP6 models from May to August, comparing them to ERA5. Our findings reveal that numerous CMIP6 models encounter difficulties in reproducing the climatology of the MYF similar to observations. By sub-sampling models based on the meridional position bias of the MYF in May, we identified distinct monthly variations within these groupings. Additionally, the origins of these biases were examined. Our study stresses the link between the misrepresentation of MYF climatology in CMIP6 models and the depiction of the North Pacific High, particularly its western edge. The implications of these discoveries are also explored. 

How to cite: Leckebusch, G. C., Ng, K. S., and Hodges, K. I.: Climatological Evaluation of the Mei-yu Front Representation in CMIP6, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1657, https://doi.org/10.5194/egusphere-egu24-1657, 2024.

EGU24-1711 | Orals | ITS1.10/CL0.1.9

Recognizing distinctiveness of SSP3-7.0 for use in impact assessments 

Hideo Shiogama, Shinichiro Fujimori, Tomoko Hasegawa, Michiya Hayashi, Yukiko Hirabayashi, Tomoo Ogura, Toshichika Iizumi, Kiyoshi Takahashi, and Toshihiko Takemura

Because recent mitigation efforts have made the upper-end scenario of the future GHG concentration (SSP5-8.5) highly unlikely, SSP3-7.0 has received attention as an alternative high-end scenario for impacts, adaptation, and vulnerability (IAV) studies. However, the ‘distinctiveness’ of SSP3-7.0 may not be well-recognized by the IAV community. When the integrated assessment model (IAM) community developed the SSP-RCPs, they did not anticipate the limelight on SSP3-7.0 for IAV studies because SSP3-7.0 was the ‘distinctive’ scenario regarding to aerosol emissions (and land-use land cover changes). Aerosol emissions increase or change little in SSP3-7.0 due to the assumption of a lenient air quality policy, while they decrease in the other SSP-RCPs of CMIP6 and all the RCPs of CMIP5. This distinctive high-aerosol-emission design of SSP3-7.0 was intended to enable climate model (CM) researchers to investigate influences of extreme aerosol emissions on climate. Here we show that large aerosol emissions in SSP3-7.0 significantly suppress future increases in precipitation. We recommend IAV researchers to compare impact simulations at the same warming level between SSP3-7.0 and SSP5-8.5 to examine the effects of aerosols in the case that such analyses are adequate. We also recommend ScenarioMIP for CMIP7 to exclude scenarios with extreme policies of aerosols (and land-use land-cover changes) from Tier 1 experiments and instead include them in Tier 2.

 

Reference: Shiogama, H., et al. Nat. Clim. Chang. 13, 1276–1278 (2023). https://doi.org/10.1038/s41558-023-01883-2

How to cite: Shiogama, H., Fujimori, S., Hasegawa, T., Hayashi, M., Hirabayashi, Y., Ogura, T., Iizumi, T., Takahashi, K., and Takemura, T.: Recognizing distinctiveness of SSP3-7.0 for use in impact assessments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1711, https://doi.org/10.5194/egusphere-egu24-1711, 2024.

The IPCC’s 2021 assessment suggested that substantial emissions reduction and limiting global temperature rise to well below 2.0°C could prevent the complete loss of Arctic sea ice in this century. However, these assessments come with large uncertainties. Recent research projects a summer ice-free Arctic by the 2050s even under a low emission scenario by constraining future sea ice area with satellite-derived sea ice concentration (SIC) since 1979. Notably, the climate models in these assessments commonly underestimate the accelerated Arctic warming and the pace of sea ice melting, particularly over the last two decades. Moreover, recent studies indicate that in a warming climate, the thinning of sea ice and snow over sea ice may intensify surface warming, thereby accelerating the melting.

In this study, we leverage the increasing availability of observations and recent reanalysis data for Arctic-wide sea ice to investigate the link between changes in sea ice thickness (SIT), sea ice concentration (SIC), and Arctic warming. We employ these datasets to evaluate biases in historical periods and uncertainties in future scenarios within the CMIP6 multi-model ensemble for SIT and SIC. We further investigate the relationship between the thinning of sea ice and the snow layer on sea ice and surface temperature changes on a basin or regional scale. The findings are then used to constrain projected Arctic changes. Our study aims to gain some insights into the impact of model biases in the Arctic on projected climate projections, crucial for decision-making in a changing climate.

How to cite: Tian, T. and Yang, S.: The impact of sea ice thickness biases on the projected summer sea ice-free Arctic in CMIP6 ensemble experiments , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1855, https://doi.org/10.5194/egusphere-egu24-1855, 2024.

The southeastern U.S. is frequently impacted by severe thunderstorms, which are known for producing damaging winds, hail, and tornadoes. The National Oceanic and Atmospheric Administration (NOAA) reports that this region experiences the highest frequency of thunderstorms in the country. In recent decades, these storms have shown a trend of increasing both in frequency and intensity. Moreover, the southeastern states are susceptible to hurricanes and tropical storms, which have been intensifying due to warmer ocean temperatures. The escalating severity of these weather events poses significant risks to public safety, infrastructure, and the economy in the southeast. Our proposed study uses advanced satellite technology, specifically Interferometric Synthetic Aperture Radar (InSAR), to map storm-induced flooding and damage from October 2019 to August 2021. This period includes Hurricane Sally, which caused significant destruction in Alabama on September 16, 2020. By analyzing satellite images taken before and after hurricanes, we aim to identify affected areas and assess infrastructural damage. The study employs Sentinel-1 InSAR data processed by the COMET-LiCSAR system and the LiCSBAS processing package, generating surface deformation time series. We also integrate optical images to examine soil moisture and climate changes, correlating them with displacement and radar coherence data from SAR images. This research will classify and discuss the impact of hurricanes on infrastructure and roadways, providing critical information to prioritize emergency response and inform repair and reconstruction planning.

How to cite: Khosravi, A., Ghorbani, Z., and Maghsoudi, Y.: Monitoring Severe Storm Impacts and Climate Trends in the Southeastern US using Satellite-Based Proxy Indicators: A Case Study of Hurricane Sally, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2173, https://doi.org/10.5194/egusphere-egu24-2173, 2024.

EGU24-2368 | Posters on site | ITS1.10/CL0.1.9

Changes in Day-to-day temperature variability in United States driven by cleaner air 

Guzailinuer Yasen, Qi Liu, and Weidong Guo

Day-to-day (DTD) temperature variability is an important characteristic of air temperature, which significantly affects human health and ecosystems. However, the changing trend of DTD under recent climate warming and its causes need to be further explored. Here, Using daily temperature observations, we examine the spatial heterogeneity of DTD and its long-term trends in the United States (US) over the last 26 years and find a significant increase in winter DTD in the central and eastern United States during the study period. In addition, by using the observed data and The Coupled Model Intercomparison Project Phase 6 (CMIP6) multi-model simulations, we further demonstrate that cleaner air leads to significant changes in DTD. Specifically, by comparing the contributions of greenhouse gases, anthropogenic aerosols, natural forcing, and total forcing, it is concluded that the reduction of anthropogenic aerosol concentrations in the United States after 1997 led to enhanced DTD . Of the 32 members used in this study, nearly 60% show positive trends in the DTD index during 1997–2022 in the historical simulations. The trends for the ensemble members range from -0.06 to 0.08 °C ·decade-1  with an ensemble mean of 0.008°C· decade-1 which encompasses the trend derived from the observations (0.08 °C·decade-1 ) . The historical simulations reasonably capture the observed DTD trends except with a weaker magnitude. The increasing trend is also evident in the anthropogenic-aerosol-only historical simulations, where about 56% of the 32members show positive trends, with an ensemble mean of 0.01 °C·decade-1. While contrary to the results of the anthropogenic-aerosol-only historical simulations (hist-aer), there was negative trends In the natural-only historical (hist-nat) and the greenhouse-gas-only historical (hist-GHG) simulations, only about 44% and 47% of the members showed the positive trends, The trend for the ensemble mean is -0.013/-0.015°C·decade-1 for the hist-nat / hist-GHG simulations. Therefore, the positive trend of the DTD index can be attributed to the anthropogenic aerosols , while the negative trend of which can be attributed to the natural forcing and greenhouse gas forcing. The observed DTD enhancement over 1997-2022 is dominated by the effect of anthropogenic aerosols, while natural forcing and GHGS partially counteract the effect of anthropogenic aerosols. That is, Based on climate modeling experiments, we demonstrate that the reduced aerosol emissions in US can contribute to the enhanced trend of DTD in USA.

How to cite: Yasen, G., Liu, Q., and Guo, W.: Changes in Day-to-day temperature variability in United States driven by cleaner air, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2368, https://doi.org/10.5194/egusphere-egu24-2368, 2024.

Despite the early warnings of the scientific community in general and of the IPCC in particular, we have entered decades in which climate models are no longer black boxes as the consequences of past emissions of greenhouse gases are emerging rapidly in multiple climate records. This unprecedented situation is likely to change our methods and our view of the respective roles of models and observations in understanding recent and predicting future climate change, regardless of the considered emission scenario. Among the key questions raised are the role of observations in model tuning versus projection constraining and the design of future model intercomparison projects. These questions will be illustrated by several recent studies aimed at constraining CMIP6 projections and, hopefully, with a fresh although critical look on the forthcoming CMIP7 project.

How to cite: Douville, H.: Confronting Earth System Model Trends with Observations: The Good, the Bad, and the Ugly, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2903, https://doi.org/10.5194/egusphere-egu24-2903, 2024.

The reversibility of a wide range of components of the earth system was investigated by comparing forward and time-reversed 
historical and future simulations of a coupled earth system model known as the Beijing Normal University earth system 
model. Many characteristics of the climate system, including the surface temperature, ocean heat content (OHC), convective 
precipitation, total runof, ground evaporation, soil moisture, sea ice extent, and Atlantic Meridional Overturning Circulation, 
did not fully return to their initial values when the historical or future natural and anthropogenic forcing agents were reversed. 
The surface temperature and OHC declines lagged behind the decline in greenhouse gases (GHGs). Reverses in other variables occurred in direct response to the decline in GHGs. The sea level increased, even after all of the forces returned to the 
original values. Furthermore, most of the climate variables did not return to their original values because of thermal inertial. 
The end states of variables, other than those related to thermal storage, mainly depended on the original state of the natural 
and anthropogenic forces, and were unafected by the future growth rate of the GHGs. The climate policy implication of this 
study is that climate change cannot be completely reversed even if all the external forces are returned to their initial values

How to cite: Yang, S.: Reversibility of historical and future climate change with a complex earth system model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2964, https://doi.org/10.5194/egusphere-egu24-2964, 2024.

Untangling the impact of anthropogenic forcing on drought is particularly essential for climate change mitigation. Previous studies have indicated that anthropogenic forcing exacerbates drought, raising concerns about global drought evolution, yet little is known about the impact of anthropogenic forcing on drought evolution through anthropogenic greenhouse gases (GHGs) and aerosol (AER). We integrated standardized precipitation evapotranspiration index (SPEI) data under different experiments to study drought development with Coupled Model Intercomparison Project Phase 6 (CMIP6) global climate models (GCMs). Subsequently, we conducted sensitivity analyses to quantify the changes in drought sensitivity to anthropogenic greenhouse gas (DSG) and aerosol (DSA) from 1900 to 2014. Our findings reveal different effects of AER and GHGs on drought trends during three periods. Specifically, GHGs slightly increased global drought severity in the early 20th century. Conversely, from 1956 to 1982, the drought-mitigating effects of AER surpassed the drought-enhancing effects of GHGs, and the global was humidified. Then, from 1982 to 2014, the trends of increasing DSG and decreasing DSA suggest that an important global shift is taking place. GHG re-emerged as the primary driver, thus leading to increased drought severity. Taken together, these findings elucidate how anthropogenic forcing impacts global drought severity through drought-enhancing effects of GHGs and drought-mitigating effects of AER, which provides new insights into understanding the risk of anthropogenic impacts on global drought.

How to cite: Li, H.: Anthropogenic forcing inconsistently exacerbates global drought, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4371, https://doi.org/10.5194/egusphere-egu24-4371, 2024.

EGU24-5200 | Orals | ITS1.10/CL0.1.9

Anthropogenic aerosol forcing in CMIP from prescribed optical and cloud microphysical properties 

Stephanie Fiedler, Sabine Bischof, Natalia Sudarchikova, Rachel M. Hoesly, and Steven J. Smith

Anthropogenic aerosol forcing is quantitatively uncertain affecting the ability to constrain the climate response to anthropogenic perturbations. Climate models participating in the Coupled Model Intercomparison Project (CMIP) use different methods to incorporate direct and cloud-mediated aerosol effects. Some models in CMIP6 used prescribed anthropogenic aerosol optical properties and associated effects on cloud droplet number concentrations from the Simple Plumes parameterization fitted to the Max-Planck-Institute for Meteorology’s Aerosol Climatology version 2 (MACv2-SP). MACv2-SP was originally designed for the use in a subset of experiments for the Radiative Forcing Model Intercomparison Project to better understand the model diversity in aerosol forcing (Fiedler et al., 2023). The final uptake of MACv2-SP for research was, however, much broader. In the context of CMIP, the implementation of MACv2-SP in several climate models led to the request for new MACv2-SP input data that are consistent with updated emissions, e.g., in the framework of CovidMIP (Fiedler et al., 2021) and now in preparation for CMIP7 via the CMIP Climate Forcings Task Team. Moreover, MACv2-SP also serves in creating seasonal and decadal predictions, and satellite products.

We will therefore derive and freely provide new data for the anthropogenic aerosol optical properties and their cloud-mediated effects based on newly available emissions. The next data version of MACv2-SP is currently in preparation for interests in using CMIP6plus compliant boundary data. It will use the historical emission data for aerosols and their precursors from the new release of the Community Emission Data System (CEDS), which will be published at the beginning of 2024. The new emissions will allow us to revise and extent the historical data for MACv2-SP to include years after 2014. Expected changes compared to the MACv2-SP data used in CMIP6 are improved aerosol optical depth over some land regions in recent years, where the observations developed differently compared to assumptions in the scenarios. We will further translate uncertainty in the emission data to expected differences in the aerosol forcing. In addition to the new data for CMIP6plus, a new development of the simple plumes approach will be made for an assessment of the radiative forcing and climate response to aerosols from severe wild fires in recent years that are not represented by CMIP6 models.

Fiedler, S., Wyser, K., Rogelj, J. and van Noije, T. (2021) Radiative effects of reduced aerosol emissions during the COVID-19 pandemic and the future recovery.  Atmospheric Research, 264 . Art.Nr. 105866. DOI 10.1016/j.atmosres.2021.105866.

Fiedler, S., van Noije, T., Smith, C. J., Boucher, O., Dufresne, J., Kirkevåg, A., Olivié, D., Pinto, R., Reerink, T., Sima, A. and Schulz, M. (2023) Historical Changes and Reasons for Model Differences in Anthropogenic Aerosol Forcing in CMIP6. Geophysical Research Letters, 50 (15). Art.Nr. e2023GL104848. DOI 10.1029/2023GL104848.

How to cite: Fiedler, S., Bischof, S., Sudarchikova, N., Hoesly, R. M., and Smith, S. J.: Anthropogenic aerosol forcing in CMIP from prescribed optical and cloud microphysical properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5200, https://doi.org/10.5194/egusphere-egu24-5200, 2024.

EGU24-5527 | Orals | ITS1.10/CL0.1.9

Regional impacts poorly constrained by climate sensitivity  

Ranjini Swaminathan, Jacob Schewe, Jeremy Walton, Klaus Zimmermann, Richard Betts, Chantelle Burton, Chris Jones, Colin Jones, Matthias Mengel, Christopher Reyer, Andrew Turner, and Katja Weigel

Climate risk assessments must account for a wide range of possible future changes, so scientists often use many climate models in order to fully explore the range of potential changes in regional climates and their impacts. Many of the latest-generation global climate models have high values of effective climate sensitivity (EffCS), which are unlikely according to independent estimates of EffCS. It has been argued that these “hot” models are unrealistic and should therefore be excluded from analyses of climate change impacts. However, whether this would really improve regional impact assessments, or actually make them worse, is unclear. Here we show that there is no universal relationship between EffCS and projected changes in important climatic impact drivers. Analysing three different impacts - heavy rainfall, meteorological drought, and fire weather in important world regions, we find a significant correlation with EffCS only in some regions and for some metrics. Moreover, even in those cases, internal variability has a larger effect on projected changes than has EffCS. This means that impact studies should not select climate models based solely on their EffCS, which does not help constrain projections and may potentially neglect realistic impacts in models deemed “unrealistic” on the basis of their sensitivity. We recommend that model selection or filtering must be based on a more specific evaluation of models vis-à-vis the impact of interest.

How to cite: Swaminathan, R., Schewe, J., Walton, J., Zimmermann, K., Betts, R., Burton, C., Jones, C., Jones, C., Mengel, M., Reyer, C., Turner, A., and Weigel, K.: Regional impacts poorly constrained by climate sensitivity , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5527, https://doi.org/10.5194/egusphere-egu24-5527, 2024.

EGU24-5895 | ECS | Orals | ITS1.10/CL0.1.9

Pathways for avoiding ocean biogeochemical damage: Mitigation targets, mitigation options, and projections 

Timothée Bourgeois, Olivier Torres, Friederike Fröb, Aurich Jeltsch-Thömmes, Giang T. Tran, Jörg Schwinger, Thomas L. Frölicher, Fortunat Joos, David Keller, Andreas Oschlies, and Laurent Bopp

Tipping points are thresholds beyond which large, abrupt and possibly irreversible changes in the climate system or in large scale ecosystems would occur. The crossing of such tipping points under anthropogenic forcing poses a threat to biodiversity, food security, and human societies. However, due to the complexity of the processes involved, it remains notoriously difficult to determine exact thresholds that need to be avoided to stay within a “safe operating space” for humanity. Here, we map, for a variety of mitigation metrics, the crossing of thresholds, which we define to represent a wide range of deviations from the unperturbed state. We assess the crossing of these thresholds in a wide range of plausible future emission pathways: two climate mitigation scenarios (one with a strong overshoot) and one no-mitigation high-emissions scenario. These scenarios are simulated by the latest generation of Earth system models and by two Earth system models of intermediate complexity, for which we created large perturbed-parameter ensembles. Using this comprehensive model database we provide estimates of when and at which warming level 4 mitigation targets (thresholds) for 14 different impact metrics are exceeded along with an assessment of uncertainties. We find that under the high-emissions scenario, even the highest thresholds for many of the impact metrics are exceeded with high confidence, such as the expansion of ocean areas that are undersaturated with respect to aragonite, decreases in plankton biomass, Arctic summer sea ice extent, strength of the Atlantic meridional overturning circulation (AMOC), and subsurface oxygen concentration. The risk of exceeding a given mitigation target decreases under low-emissions and overshoot scenarios. Yet, exceedance of ambitious targets for aragonite undersaturation, Arctic summer sea ice extent, and steric sea level rise (SSLR) are projected to be difficult to avoid (high confidence) even under the low-emissions scenario. The overshoot scenario reduces the risk of exceeding mitigation targets related to Arctic summer sea ice extent, SSLR, AMOC and plankton biomass compared to the high-emissions scenario, particularly in the long-term. Uncertainties in Earth system model projections of net primary production prevent us from concluding on the risk of mitigation target exceedance for this impact metric.

How to cite: Bourgeois, T., Torres, O., Fröb, F., Jeltsch-Thömmes, A., Tran, G. T., Schwinger, J., Frölicher, T. L., Joos, F., Keller, D., Oschlies, A., and Bopp, L.: Pathways for avoiding ocean biogeochemical damage: Mitigation targets, mitigation options, and projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5895, https://doi.org/10.5194/egusphere-egu24-5895, 2024.

Over four decades, CMIP has driven massive improvements in the modelled representation of the Earth system, whilst also seeing huge growth in its scope and complexity. In its most recent phase, CMIP6, a broad spectrum of questions continues to be answered across twenty-four individual model intercomparison projects (MIPs). This science improves process understanding and assesses the climate’s response to forcing, systematic biases, variability, and predictability in line with WCRP Scientific Objectives. CMIP and its associated data infrastructure have become essential to the Intergovernmental Panel on Climate Change (IPCC) and other international and national climate assessments, increasingly including the downstream mitigation, impacts, and adaptation communities.

However, despite the invaluable science produced from CMIP6 data, many challenges were still faced by the model data providers, the data delivery infrastructure, and users, which need to be addressed moving forwards. A specific challenge in CMIP6 was the burden placed on the modelling centres, in part due to the large number of requested experiments and delays in the preparation of the CMIP6 forcing datasets and climate data request.

The CMIP structure is evolving into a continuous, community-based climate modelling programme to tackle key and timely climate science questions and facilitate delivery of relevant multi-model simulations. This activity will be supported by the design of experimental protocols, an infrastructure that supports data publication and access, and quasi-operational extension of historical forcings.  A subset of experiments is proposed to be fast-tracked to deliver climate information for national and international climate assessments and informing policy and decision making. The CMIP governing panels are coordinating community activities to reduce the burden placed on modelling centres, continue to enhance novel and innovative scientific activities, and maximise computational efficiencies, whilst continuing to deliver impactful climate model data.

How to cite: Hewitt, H. and Dunne, J. and the CMIP Panel and IPO: Evolving The Coupled Model Intercomparison Project (CMIP) To Better Support The Climate Community And Future Climate Assessments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6364, https://doi.org/10.5194/egusphere-egu24-6364, 2024.

Global climate change projections, such as those from the Coupled Model Intercomparison Project phase 6 (CMIP6), are still subject to substantial modelling uncertainties. A variety of Emergent Constraints (ECs) have been suggested to address these uncertainties, but remain heavily debated in the scientific community. Still, the central idea behind ECs to relate future projections to already observable quantities has no real substitute.

Here we discuss machine learning (ML) approaches for new types of controlling factor analyses (CFA) as a promising alternative. The principal idea is to use ML to find climate-invariant relationships in historical data, which also hold approximately under strong climate change scenarios. On the basis of existing big data archives such as those from the CMIPs, these climate-invariant relationships can be validated in perfect-climate-model frameworks.

From a ML perspective, we argue that CFA are promising for three reasons: (a) they can be objectively validated both for present-day data and future data and (b) they provide more direct - by design physically-plausible - links between historical observations and potential future climates compared to ECs and (c) they can take higher dimensional relationships into account that better characterize the still complex nature of large-scale emerging relationships. We highlight these advantages for three examples in the form of constraints on climate feedback mechanisms (clouds [1], stratospheric water vapour [2]) and forcings (aerosol-cloud interactions).

References:

1. Ceppi P. and Nowack P. Observational evidence that cloud feedback amplifies global warming, Proceedings of the National Academy of Sciences 118 (30), e2026290118 (2021). https://doi.org/10.1073/pnas.2026290118

2. Nowack P., Ceppi P., Davis S.M., Chiodo G., Ball W., Diallo M.A., Hassler B., Jia Y., Keeble J., and Joshi M. Response of stratospheric water vapour to warming constrained by satellite observations, Nature Geoscience 16, 577-583 (2023). https://doi.org/10.1038/s41561-023-01183-6

How to cite: Nowack, P. and Watson-Parris, D.: Why all emergent constraints are wrong but some are useful - a machine learning perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6750, https://doi.org/10.5194/egusphere-egu24-6750, 2024.

The solar forcing dataset prepared for the 6th round of the Coupled Model Intercomparison Project (CMIP6) has been used extensively in climate model experiments. Recently, an International Space Science Institute (ISSI) Working Group was established to revisit the solar forcing recommendations in order to define a roadmap for building a revised solar forcing dataset for the upcoming 7th round of CMIP (Funke et al., 2023). This new dataset will introduce changes in the radiative forcing of climate either directly, or indirectly via changes in atmospheric composition. In CMIP6, the solar forcing consisted of both a total solar irradiance (TSI), along with a spectrally resolved solar irradiance (SSI). The TSI for solar minimum was set to 1360.8±0.5Wm-2 and the SSI covered the 10nm to 100mm spectral region. A similar approach is proposed for CMIP7 except for two major aspects of the reconstruction: 1) the definition of the reference spectrum for the quite Sun; 2) the temporal variability. The major difference between the proposed CMIP7 SSI quite sun reference spectrum and that used for CMIP6 is the spectral shape. The new SSI spectrum has an irradiance that is 1-5% higher in the visible band and lower by 1-2% in the Near-IR wavelength range (1000-2000nm). The solar temporal variability in the CMIP6 and CMIP7 reconstructions are based on both the NRLSSI2 and SATIRE reconstructions. These reconstructions have been improved in preparation for CMIP7 and the aim is for both reconstructions to use the same reference spectrum and be driven by the same solar proxies. In this work we used the Whole Atmosphere Community Climate Model (WACCM) to examine the chemical and climate implications of the proposed CMIP7 solar forcing updates compared to the CMIP6 approach. WACCM is a chemistry-climate model that extends from the surface to 140km. The horizontal resolution is ~1degree. WACCM has a detailed representation of chemical and dynamical processes from the troposphere through the lower thermosphere. We examined the “chemical only” impacts of the solar forcing choice by running WACCM in the specified dynamics mode using NASA Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA2). The “climate” impacts were derived by running the model with interactive dynamics coupled to a deep ocean. Conclusions from this work will support the development of the next version of WACCM for participation in the CMIP7 assessment.

Funke, B., Dudok de Wit, T., Ermolli, I., Haberreiter, M., Kinnison, D., Marsh, D., Nesse, H., Seppälä, A., Sinnhuber, M., and Usoskin, I.: Towards the definition of a solar forcing dataset for CMIP7, Geosci. Model Dev. Discuss. https://doi.org/10.5194/gmd-2023-100.

 

How to cite: Kinnison, D., Marsh, D., and Tilmes, S.: Evaluation of the chemistry and climate impact of the new solar forcing dataset for CMIP7 using the Whole Atmosphere Community Climate Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6774, https://doi.org/10.5194/egusphere-egu24-6774, 2024.

EGU24-7042 | ECS | Orals | ITS1.10/CL0.1.9

The Competition Between Anthropogenic Aerosol and Greenhouse Gas Forcing is Revealed by North Pacific Water-mass Changes 

Jia-Rui Shi, Susan Wijffels, Young-Oh Kwon, Lynne Talley, and Sarah Gille

Modelled water-mass changes in the North Pacific thermocline from CMIP6, both in the subsurface and at the surface, reveal the impact of the competition between anthropogenic aerosols and greenhouse gases (GHGs) over the past 6 decades. The aerosol effect overwhelms the GHG effect during 1950-1985 in driving salinity changes on density surfaces, while after 1985 the GHG effect dominates. These subsurface water-mass changes are traced back to changes at the surface, of which ~70% stems from the migration of density surface outcrops, equatorward due to regional cooling by anthropogenic aerosols and subsequent poleward due to warming by GHGs. Ocean subduction connects these surface outcrop changes to the main thermocline. Both observations and models reveal this transition in climate forcing around 1985 and highlight the important role of anthropogenic aerosol climate forcing on our oceans’ water masses.

How to cite: Shi, J.-R., Wijffels, S., Kwon, Y.-O., Talley, L., and Gille, S.: The Competition Between Anthropogenic Aerosol and Greenhouse Gas Forcing is Revealed by North Pacific Water-mass Changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7042, https://doi.org/10.5194/egusphere-egu24-7042, 2024.

EGU24-7159 | Orals | ITS1.10/CL0.1.9

Unveiling the Subjectivity in Ranking of NEX-GDDP-CMIP6 Climate Models Over Munneru River Basin, India 

Venkata Reddy Keesara, Eswar Sai Buri, and Loukika Kotapati Narayanaswamy

Regional climate modelling has evolved significantly, offering versatile applications across various scales and resolutions. This study aims to provide a comprehensive framework for selecting top five Climate Models at each grid for climate variables in the Munneru River Basin, comes under Lower Krishna River Basin, India. Employing the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) datasets, which are derived from General Circulation Model (GCM) runs under the Coupled Model Intercomparison Project Phase 6 (CMIP6), is compared with the observed precipitation, maximum, and minimum temperature datasets obtained from the Indian Meteorological Department (IMD). These datasets have a spatial resolution of (0.25° × 0.25°) and available from 1970 to 2014. The methodology adopted in this study uses advanced statistical techniques to evaluate the performance of the CMIP6 models. The study incorporates Multicriterion Decision-Making Techniques (MCDM) and Group Decision-Making (GDM) methodologies within the Reliable-Ensemble Averaging (REA) framework. MIROC-ES2L, GISS-E2-1-G and TaiESM1 are the top ranked models for precipitation data. Whereas, BCC-CSM2-MR, ACCESS-ESM1-5 and GFDL-CM4_gr2 obtained as most suitable RCMs for maximum temperature data. For minimum temperature data, MIROC-ES2L, KIOST-ESM and MIROC6 obtained as top ranked CMIP6 models. The projected climate variables, including precipitation, maximum temperature and minimum temperatures, under three distinct Shared Socioeconomic Pathways (SSP) scenarios: SSP 245, SSP 370 and SSP 585 extending up to the year 2100. The spatio-temporal analysis encompasses key climate parameters, identifying trends, variations, and potential anomalies in the Munneru River Basin. This study contributes to the broader context of regional climate modelling research and enhances our understanding of the Munneru River Basin's climate dynamics. The research findings presented in this study aim to understand the methodological advancements in regional climate modelling, performance assessments of CMIP6 models and the application of CMIP6 models in regional process studies.

How to cite: Keesara, V. R., Buri, E. S., and Kotapati Narayanaswamy, L.: Unveiling the Subjectivity in Ranking of NEX-GDDP-CMIP6 Climate Models Over Munneru River Basin, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7159, https://doi.org/10.5194/egusphere-egu24-7159, 2024.

The influence of anthropogenic (ANT) activity and the other external factors on extreme temperature changes over the mid–high latitudes of Asia are analysed using the different forcing simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) models. The optimal fingerprinting technique and the probability ratio (PR) are employed to detect and quantify the influences of the external forcings on extreme temperature changes, which include annual maximum daily maximum temperature (TXx), annual minimum daily minimum temperature (TNn). Results indicate that TXx and TNn have increased from 1979 to 2014, and the simulations from historical (anthropogenic plus natural; ALL), greenhouse gas (GHG), and anthropogenic (ANT) experiments reasonably reproduce the spatiotemporal characteristics of extreme temperatures. Based on the optimal fingerprinting method, the impact of ANT forcing, in which GHG forcing is critical, can be detected in the changes of warm extremes and cold extremes. ANT and NAT forcings are separately detectable for warm extremes. GHG forcing can be separated from other ANT forcings for cold extremes but not warm extremes. Furthermore, the analysis applying the PR method shows that the probability of observed warm extremes that occur once in 20 years over the mid–high latitudes of Asia has risen by approximately three times owing to the anthropogenic influence, whereas the cold extremes became once in 50 years. Briefly, the increased anthropogenic activity has exacerbated the warm extremes and soothed the cold extremes over the mid–high latitudes of Asia during the past decades.

How to cite: Jiang, W. and Chen, H.: Anthropogenic influence on extreme temperature changes over the mid–high latitudes of Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7881, https://doi.org/10.5194/egusphere-egu24-7881, 2024.

EGU24-8659 | ECS | Posters on site | ITS1.10/CL0.1.9

Studying the pre-industrial to present-day radiative forcing from wildfire aerosols using EC-Earth 

Rafaila Nikola Mourgela, Eirini Boleti, Konstantinos Seiradakis, Klaus Wyser, Phillipe Le Sager, Angelos Gkouvousis, and Apostolos Voulgarakis

The occurrence of more frequent and extensive wildfires is a widely discussed potential consequence of climate change, stemming from a vicious cycle of cause and effect in which wildfires are taking part. Global and regional wildfire patterns and changes are driven by climate-related factors such as land cover, heat waves, and rainfall patterns. Wildfires can, in turn, cause climate perturbations through the emissions of greenhouse gases and aerosols, and through the alteration of landscapes. For these reasons, understanding wildfires and their interactions with the Earth’s atmosphere is crucial for assessing a potentially important climate feedback.

The current study focuses on the interconnection between wildfires and the atmosphere, and more precisely on the radiative effect of wildfire emissions on a global scale. To achieve this, simulations using the EC-Earth Earth System Model (ESM) were employed. More specifically, a 30-year atmosphere-only (fixed-SST) control simulation was performed for the pre-industrial period, and repeated with the wildfire aerosol emissions set to present-day values. Using the output of these simulations, we estimate the global effective radiative forcing (ERF) of wildfire-emitted aerosols from pre-industrial times to the present day. We also identify which regions experience stronger forcing from wildfire emissions, and separate the role of black carbon and organic carbon in driving this forcing. Finally, we identify mechanisms that lead to fast atmospheric adjustments following wildfire emissions, including changes in temperatures, humidity, precipitation, and clouds. This analysis contributes to the better understanding of the historical evolution of radiative forcing and the role of wildfires in the climate system.

 

How to cite: Mourgela, R. N., Boleti, E., Seiradakis, K., Wyser, K., Le Sager, P., Gkouvousis, A., and Voulgarakis, A.: Studying the pre-industrial to present-day radiative forcing from wildfire aerosols using EC-Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8659, https://doi.org/10.5194/egusphere-egu24-8659, 2024.

EGU24-8690 | ECS | Posters on site | ITS1.10/CL0.1.9

How your aerosol implementation choices affect your model’s climate system response 

Estela Monteiro and Nadine Mengis

Anthropogenic activities have disrupted the energy balance of the planet since preindustrial era through, among other drivers, the emission of various greenhouse gases and aerosols. The largest uncertainty to current climate forcing and future projections relates to the effect of aerosols. Their different impacts on the planet’s radiative balance, that is, with direct radiative and indirect cloud interaction forcing, need to be considered accurately in simple policy-informing climate models. Especially in the context of high ambition mitigation scenarios, variability in the future development of spatiotemporal aerosol forcing will have a relatively large impact on climate projections. Accordingly, an accurate inclusion of the relevant processes onto the modeling scheme, such as the spatiotemporal level of detail chosen when accounting for aerosol forcing in simple(r) climate models must be carefully considered.

Here we explore the impact of different aerosols implementation schemes in an intermediate complexity Earth system model configuration with an energy moisture balance model (UVic ESCM, version 2.10). While the global mean forcing is the same for all scenarios, we vary spatial and temporal resolution of optical depth maps or implement aerosol forcing as direct radiative forcing to the Earth system. These schemes are applied to relevant ambitious mitigation scenarios aiming at temperature stabilization, which will become especially relevant in the upcoming CMIP exercises. Using a newly developed assessment framework, we will provide insights into the impacts of this model implementation choice onto future temperature development, the carbon cycle and heat uptake processes. Ultimately these insights aim to improve, constrain and design better scenario simulations that are both applicable and relevant to the scientific and decision-making communities.

How to cite: Monteiro, E. and Mengis, N.: How your aerosol implementation choices affect your model’s climate system response, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8690, https://doi.org/10.5194/egusphere-egu24-8690, 2024.

EGU24-9312 | ECS | Posters on site | ITS1.10/CL0.1.9

Historical volcanic sulfur emissions and stratospheric sulfate aerosol optical properties for CMIP7 

Thomas Aubry, Anja Schmidt, Mahesh Kovilakam, Matthew Toohey, and Michael Sigl

Explosive volcanic eruptions injecting gases and aerosols into the stratosphere are a key natural driver of climate variability at annual to centennial timescales. They are thus one of the forcings considered by the Coupled Model Intercomparison Project (CMIP) Climate Forcings Task Team, in charge of identifying and implementing the next generation forcings for current and future generations of Earth System models. This presentation will provide an overview of ongoing work to produce volcanic forcing datasets for phase 7 of CMIP (CMIP7).

The datasets we produce will cover the period from 1750 to 2022 at version 1 to meet to the need of modelling groups who might run extended historical simulations starting in 1750 instead of 1850. We are producing one volcanic stratospheric sulfur emission dataset catering for the needs of models which have a prognostic interactive stratospheric aerosol scheme, as well as a stratospheric sulfate aerosol optical property dataset required by models that cannot interactively simulate stratospheric sufate aerosols. For the satellite era (from 1979 onwards), sulfur emissions and sufate aerosol optical properties are based on NASA’s MSVOLSO2L4 and GloSSAC datasets, respectively. For the pre-satellite era (1750-1978), the emission dataset is based on ice-core datasets complemented by the geological record, whereas the aerosol optical property dataset is directly derived from emissions using the latest version of the Easy Volcanic Aerosol (EVA) model. This ensures methodological consistency between our emission and optical property datasets, further enhanced by the fact that EVA is calibrated using the same datasets we use for the satellite era. Our choice of methods aims to maximize consistency with methodologies used in individual model intercomparison projects (e.g. PMIP and VolMIP). A major focus of our task team is to produce well-documented datasets, which includes extensive meta-data and flags, detailed documentation, and provision of open-access scripts used to create the datasets, which should facilitate future development and operationalization by the community. We also discuss the most critical challenges for providing accurate volcanic forcing datasets, including the under-recording of small-to-moderate magnitude eruptions before the satellite era, and the Hunga Tonga-Hunga Ha'apai 2022 eruptions, which injected relatively small amounts of sulfur, but 150 Tg of water into the stratosphere.

How to cite: Aubry, T., Schmidt, A., Kovilakam, M., Toohey, M., and Sigl, M.: Historical volcanic sulfur emissions and stratospheric sulfate aerosol optical properties for CMIP7, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9312, https://doi.org/10.5194/egusphere-egu24-9312, 2024.

EGU24-9994 | Orals | ITS1.10/CL0.1.9 | Highlight

Biomass burning emissions since the pre-industrial and into the future; progress and challenges 

Guido van der Werf and Margreet van Marle

Fires impact a suite of radiative forcing agents but fire is one of the most challenging sources of emissions to model due to a large degree of stochasticism and a wide range of climatic and human influences that can both increase and decrease the occurrence of fires. Although many Earth system models now account for fires, there is still a need for a coherent and consistent community dataset to intercompare and constrain models. We developed a historic dataset combining satellite data over the past two decades with proxy data and fire models for use in CMIP6. Since then, new satellite data has indicated that global burned area may be much higher than previously thought and several regional datasets have shed light on the question whether fire emissions are now higher or not than in the pre-industrial era. We show how the latest insight and developments will be used to construct an updated fire emissions dataset for CMIP7, and show which fire categories carry the largest uncertainty, both for the past and into the future.

How to cite: van der Werf, G. and van Marle, M.: Biomass burning emissions since the pre-industrial and into the future; progress and challenges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9994, https://doi.org/10.5194/egusphere-egu24-9994, 2024.

EGU24-10136 | ECS | Orals | ITS1.10/CL0.1.9

CMIP6 models evaluation using multi-resolution analysis and satellite observations : study of the atmospheric water vapor  

Cedric Gacial Ngoungue Langue, Hélène Brogniez, and Philippe Naveau

Water vapor is one of the fundamental atmospheric components, and as such, is one  Essential Climate Variable  (ECV) monitored by the Global Climate Observing System. In this work, the global water vapor Climate Data Record (CDR) generated within the ESA Water Vapor climate change initiative project (WV_cci) is used as reference (daily, 0.1°, 2003-2014) to evaluate a sample of the Coupled Model Intercomparison Project phase 6 (CMIP6) as well as the fifth generation ECMWF reanalysis (ERA5), with a focus on temporal signal decomposition. This temporal decomposition is performed using multi-resolution analysis (MRA). MRA is a mathematical tool which consists of decomposing a signal into its subcomponents on different time scales. Using this tool, the representation of the total column water vapor over the tropics in the CMIP6 models and ERA5 can be assessed separately from daily to annual and decadal time scales, including monthly and seasonal time scales. This approach is powerful for the  identification of  the relevant time scales for which CMIP6 predictions are most reliable. Hence, at the global-tropical scale, the MRA decomposition of the water vapor signal shows a good correlation between CMIP6 and WV_cci on both seasonal (2 - 8 months) and annual (1 - 1.4 year) time scales. Using a linear regression, we attempt to reconstruct the WV_cci signal using the CMIP6 models and ERA5 as explanatory variables based on the correlation found between the products and WV_cci at each level of decomposition. Such reconstruction highlights the scales of variability that are closest to the observed one. The presentation will detail the MRA approach and the most prominent results, as well as an extension to other parameters linked to atmospheric water vapor distribution, namely cloud cover and types and sea surface temperature. 

How to cite: Ngoungue Langue, C. G., Brogniez, H., and Naveau, P.: CMIP6 models evaluation using multi-resolution analysis and satellite observations : study of the atmospheric water vapor , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10136, https://doi.org/10.5194/egusphere-egu24-10136, 2024.

EGU24-10382 | ECS | Orals | ITS1.10/CL0.1.9

A key role of surface atmospheric circulation changes in setting global ocean warming magnitude 

Kwatra Sadhvi, Matthieu Lengaigne, Jérôme Vialard, Vincent Danielli, Gopika Suresh, and Suresh Iyyappan

Surface air-sea feedbacks play a pivotal role in modulating the amplitude of global ocean warming. Zhang and Li (2014, ZL14) introduced a simple theoretical framework to identify the driving processes responsible for the Sea Surface Temperature (SST) increase under global warming. This method involves decomposing changes in latent and upwelling longwave surface heat fluxes into two parts: one tied to direct atmospheric forcing and the other directly associated with local (SST) changes, termed feedback. Applying this heat budget equation across 53 CMIP5 and 6 models underscores the pivotal role of increased surface downwelling longwave radiation (DLR) in steering the amplitude of future global ocean warming. However, ZL14 solely considered DLR as a direct forcing, overlooking its substantial feedback response to surface warming.

In this study, we employ a novel methodology from Shakespeare and Roderick (2022, SR22) to decompose DLR changes into a direct radiative forcing and SST-related feedbacks, evaluating the implications of integrating the DLR feedback in the ZL14 framework. Our analysis is in line with SR22’s findings across 5 CMIP5 models, our results across 53 models indicate that roughly 90% of DLR increase emerges from feedbacks associated with the rising SST. The large ocean heat capacity transfers warming to the overlying atmosphere, increasing its DLR primarily through direct air temperature increase and the increasing greenhouse effect associated with increased water vapour.

Incorporating the DLR feedback in ZL14 framework yields a dominant effect of latent heat flux forcing on global ocean warming for both multi-model mean and intermodel diversity. This latent heat flux forcing is related to the evaporative cooling modulation associated with projected changes in the surface atmospheric circulation, and is highly correlated with the magnitude of the global average warming. This underscores the substantial influence of projected atmospheric circulation changes on the level of global average warming.

How to cite: Sadhvi, K., Lengaigne, M., Vialard, J., Danielli, V., Suresh, G., and Iyyappan, S.: A key role of surface atmospheric circulation changes in setting global ocean warming magnitude, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10382, https://doi.org/10.5194/egusphere-egu24-10382, 2024.

Large uncertainty in model predictions of land carbon responses to climate change has been ubiquitously demonstrated in model intercomparison projects (MIPs). The large uncertainty become a major impediment in advancing climate change prediction. Thus, it is imperative to identify sources of the uncertainty before we can fully understand and address the uncertainty issue. In this presentation, I show a novel matrix approach to analytically pin down the sources of model uncertainty in predicting carbon dynamics in response to rising atmospheric CO2 concentration and increasing temperature. We developed a matrix-based MIP by converting the carbon cycle module of eight land models (i.e., TEM, CENTURY4, DALEC2, TECO, FBDC, CASA, CLM5 and ORCHIDEE) into eight matrix models. In response to rising atmospheric CO2 concentration and increasing temperature, predicted ecosystem net primary production (NPP), net ecosystem production (NEP), and net ecosystem carbon storage spread among the eight models as simulations go over time. We applied the traceability analysis method to decompose simulated carbon dynamics to their traceable components according to the matrix equations. Our analysis indicates that the uncertainty among the eight models was mainly due to inter-model difference in baseline carbon residence time and environmental scalar. Once the sources of model uncertainty were identified, we sequentially standardized model parameters to shrink simulated ecosystem carbon storage and NEP to almost none. Our study demonstrates that the sources of uncertainty in carbon cycle modeling can be precisely traced to model structures and parameters, regardless of their complexity, so that the uncertainty issue for MIPs can be precisely understood and well addressed.

How to cite: Luo, Y.: Uncertainty spreading and shrinking among eight land carbon cycle models in response to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10567, https://doi.org/10.5194/egusphere-egu24-10567, 2024.

So-called “radiative" or "rapid" adjustments describe the surface-temperature-independent response of the climate state to an instantaneous radiative forcing. However, the term “rapid” can be misleading since various processes are considered adjustments, which appear on timescales of hours (e.g. aerosol-cloud-interactions) to month (e.g. stratospheric temperature change) or even longer timescales (e.g. adjustments of biosphere and cryosphere). On time scales of months and longer, differentiating between adjustments and feedbacks becomes increasingly difficult. Depending on the scientific method the definition of “adjustments” and which processes are considered can vary. Nevertheless, a good understanding of these processes is crucial for improving climate models and advance our general understanding of how the Earth climate system reacts to a forcing.

The abrupt-solm4p experiment from CFMIP (Cloud Forcing Model Intercomparison Project) from CMIP6 (Coupled Model Intercomparison Project phase 6) simulates an instantaneous reduction of the solar constant by 4% branching from a pre-industrial control run on 01/01/1850. We analysed changes in geographical distribution as well as global mean temporal development of various climate variables (e.g. surface and atmospheric temperature, precipitation, humidity), different cloud properties (e.g. cloud cover, column integrated liquid and ice water), as well as radiative fluxes at top of atmosphere and the cloud radiative effect. The different variables were evaluated on timescales of hours, days, months and up to 150 years after the onset of forcing, in order to learn more about the timing of different adjustment processes. Four different models participated in the abrupt-solm4p experiment. Their outputs were compared and possible source of differences discussed. During the first hours all models unanimously simulate decreasing surface and atmospheric temperature, especially strong in the Antarctica, which experiences 24hr irradiation at the onset of forcing. In the beginning, the stratospheric cooling is strongest. The moderate cooling of the troposphere leads to increased condensation and thereby increased cloud cover, even in Northern latitudes, that do not directly experience the forcing, and strengthened precipitation in the tropics. 

In a next step, we plan to compare the results from abrupt-solm4p (CFMIP) to simulations of a homogeneous stratospheric sulfate scattering-layer and to the volc-pinatubo-full-experiment (VolMIP). We expect some similarities between the simulated adjustments in these experiments, because in all three cases, incoming solar radiation is reduced in the troposphere and at surface level. However, more realistic experiments, like the volc-pinatubo experiment are expected to show more complex adjustments and the comparison to more simplified experiments like abrupt-solm4p might provide valuable insights to adjustment processes after volcanic eruptions.

How to cite: Lange, C. and Quaas, J.: Radiative adjustments after a 4%-reduction of the solar constant, based on data from the abrupt-solm4p experiment (CFMIP from CMIP6), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11255, https://doi.org/10.5194/egusphere-egu24-11255, 2024.

EGU24-12768 | Posters on site | ITS1.10/CL0.1.9

Revisiting the ‘transfer function’ of stratospheric sulfur loading from volcanic sulfate deposited on polar ice sheets 

Andrea Burke, Herman Fuglestvedt, Liz Thomas, Lauren Marshall, and Kirstin Krüger

Records of the volcanic forcing of climate prior to the satellite era depend on scaling the flux of sulfate deposited on polar ice sheets­ using a ‘transfer function’, a number calibrated based on radioactivity in Greenland from thermonuclear testing as well as Antarctic sulfate flux records from the 1991 Pinatubo eruption (e.g. Gao et al., 2007). For high latitude eruptions, this transfer function is based solely on model simulations of sulfate flux to Greenland from the Icelandic Laki eruption in 1783 and the Alaskan Katmai/Novarupta eruption in 1912 (Gao et al., 2007).  Since the initial determination of this transfer function, the number of ice cores containing sulfate from the Pinatubo eruption has increased eight-fold, and sulfur isotope measurements at high resolution over sulfate peaks in the ice has allowed for discrimination between stratospheric sulfate and sulfate transported at lower levels in the atmosphere from different sources (e.g. Burke et al., 2023). Here we revisit the estimation of the transfer function in light of these new data-based constraints from eruptions in the 20th century, and we reassess the uncertainty associated with the application of a single transfer function across volcanic eruptions in the past.

 

Gao, C., Oman, L., Robock, A. and Stenchikov, G.L., 2007. Atmospheric volcanic loading derived from bipolar ice cores: Accounting for the spatial distribution of volcanic deposition. Journal of Geophysical Research: Atmospheres112(D9).

Burke, A., Innes, H.M., Crick, L., Anchukaitis, K.J., Byrne, M.P., Hutchison, W., McConnell, J.R., Moore, K.A., Rae, J.W., Sigl, M. and Wilson, R., 2023. High sensitivity of summer temperatures to stratospheric sulfur loading from volcanoes in the Northern Hemisphere. Proceedings of the National Academy of Sciences120(47), p.e2221810120.

How to cite: Burke, A., Fuglestvedt, H., Thomas, L., Marshall, L., and Krüger, K.: Revisiting the ‘transfer function’ of stratospheric sulfur loading from volcanic sulfate deposited on polar ice sheets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12768, https://doi.org/10.5194/egusphere-egu24-12768, 2024.

EGU24-14596 | ECS | Orals | ITS1.10/CL0.1.9

Rapid development of systematic trend errors in seasonal forecasts and their connection to CMIP6 trend errors 

Jonathan Beverley, Matthew Newman, and Andrew Hoell

Questions regarding the uncertainty of trends in both historical and projected climate model simulations have been limited by uncertainty about the relative importance of internal variability and external forcing to trends over the relatively short observational record. For example, is the discrepancy between historically simulated tropical Pacific trends (El Niño-like) and observations (broadly, La Niña-like) over recent decades a reflection of sampling issues or model error in internal variability and/or forced global responses (either locally or remotely, such as from the Southern Ocean)? At the same time, it is known that systematic operational seasonal forecast errors (e.g., westward shift of ENSO) are dominated by model errors that develop quite quickly, on the order of a few months of forecast lead time.

Here, we suggest that climate model trend errors can be usefully investigated by examining their rapid development within seasonal hindcast datasets. We show that many apparent climate simulation trend discrepancies are evident in trends computed from monthly seasonal hindcasts over the 1994-2016 period for a suite of operational initialised forecast models from C3S and NMME, and in many cases are well developed even at short lead times. These hindcasts use models similar to CMIP-class models and include the same CMIP historical external forcings, but critically are initialised with observations, removing uncertainty related to internal variability. We find these trend errors in many different regions worldwide for several key variables, including sea surface temperature, precipitation and sea level pressure, and investigate their seasonal dependence as well. Notably, we find tropical Pacific "El Niño-like" SST trend errors in all seasons but spring, and related surface pressure, temperature, and precipitation errors in autumn and spring, especially in the North America region. We also find errors in Southern Ocean SSTs, which develop less rapidly than the tropical Pacific SST errors or their global teleconnections.

We suggest that these hindcast trend errors reflect sensitivity of the model mean biases to the changing radiative forcing, rather than a forced response. That is, similarity between errors in free running simulations and hindcasts is a result of the seasonal forecast models quickly transitioning from nature’s attractor to the climate model attractor, particularly in the atmospheric model component. This suggests that we might be able to better diagnose the climate model trend errors by looking at the early development of the forecast trend error in the seasonal forecast models.

How to cite: Beverley, J., Newman, M., and Hoell, A.: Rapid development of systematic trend errors in seasonal forecasts and their connection to CMIP6 trend errors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14596, https://doi.org/10.5194/egusphere-egu24-14596, 2024.

EGU24-14986 | ECS | Posters on site | ITS1.10/CL0.1.9

Assessing the Impact of Changing Warming Patterns on Transient Global Warming: A Multivariate Energy Budget Approach 

Robin Guillaume-Castel, Benoit Meyssignac, and Rémy Roca

The pattern of surface warming plays a significant role in determining the Earth's response to radiative forcing. Indeed, the Earth's radiative response is intricately linked to the intensity of climate feedbacks, which, in turn, are influenced by the regional distribution of surface warming. Distinct patterns of surface warming lead to divergent equilibrium and transient responses to identical forcing, emphasizing the need to analyse this pattern effect to understand the climate responses to external forcing.

While existing studies have primarily focused on assessing the influence of warming patterns on long-term warming, such as equilibrium climate sensitivity or committed warming, the role of warming patterns in shaping the transient trajectory of global warming remains poorly understood. In this study, we introduce a novel analytical method to quantify the importance of evolving warming patterns on transient global warming.

Our approach involves developing a multivariate global energy budget, which provides a unified framework for interpreting the sensitivity of the radiative response of the Earth to the warming pattern. This framework explicitly separates the radiative response caused by the global mean temperature increase, from the additional response induced by changing temperature patterns.

Using this new energy balance model, we assess the relative contributions of the direct radiative forcing and changing temperature patterns to the global mean temperature change in linearly increasing forcing experiments (1pctCO2) from nine CMIP6 models. We show that the pattern effect consistently dampens global warming in the first 100 years of all simulations studied. Specifically, we quantify that the transient climate response, reached after 70 years of simulations, would be 0.4±0.2K higher (equivalent to a 20±15% increase) if the warming was uniformly distributed (i.e. in the absence of changing warming patterns).

Furthermore, our study demonstrates that distinct models exhibit significantly divergent transient global warming patterns solely due to variations in the pattern effect. Overall, our results highlight the importance of changing warming patterns, specifically through the pattern effect, in influencing decadal-scale transient warming. These findings notably support recent suggestions to incorporate warming pattern uncertainties in future climate projections.

How to cite: Guillaume-Castel, R., Meyssignac, B., and Roca, R.: Assessing the Impact of Changing Warming Patterns on Transient Global Warming: A Multivariate Energy Budget Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14986, https://doi.org/10.5194/egusphere-egu24-14986, 2024.

EGU24-17153 | Posters on site | ITS1.10/CL0.1.9

NIMS/KMA Plans for Climate Change Projection Production and Utilization on CMIP7 

Chu-Yong Chung, Young-Hwa Byun, Hyun Min Sung, Jin-Uk Kim, and Sungbo Shim

The National Institute of Meteorological Sciences in the Korea Meteorological Administration (NIMS/KMA) has been actively contributing to the CMIP program since CMIP3. NIMS participated in CMIP6 through a collaborative effort with the UK Met Office Hadley Centre as part of a mutually agreed scientific plan. Within this collaboration, NIMS utilized the Earth System Model developed by the UK Met Office (UKESM) to generate future climate change scenarios for four distinct Shared Socio-economic Pathways (SSPs). NIMS also employed the KMA Advanced Community Earth (K-ACE) model, a modified version of HadGEM2-AO developed through in-house research, to analyze global climate projections. Five different regional climate models were used for the regional climate simulations: HadGEM3-RA, RegCM4, CCLM, GRIMs, and WRF, organized under the CORDEX-EA (East Asia) program. Furthermore, for the South Korean area, NIMS produced 1km resolution climate change scenario data using the statistical downscaling technique, the Parameter-elevation Relationships on Independent Slopes Model (PRISM)-based Dynamic downscaling Error correction (PRIDE). These projections played a pivotal role in contributing to the preparation of the Sixth Assessment Report (AR6) by the Intergovernmental Panel on Climate Change (IPCC) and provided crucial foundational data for national climate change adaptation efforts.

Currently, NIMS has initiated preparations for CMIP7 participation. In this program, K-ACE will be employed for producing global climate projections, having undergone improvements such as coupling with an ocean-biogeochemistry model, TOPAZ, and modifications to the cloud-aerosol process, among other enhancements. NIMS plans to use a reduced number of RCMs compared to the CMIP6 phase but intends to increase the ensemble members by combining physical processes. Currently under consideration as RCM candidates are WRF and WRF-ROMS. To comprehend the impact of climate change on local-scale heavy rain, a Convection Permitting Model (CPM) with a spatial resolution of about 2.5km can be employed. For the South Korean region, our objective is to produce more high-resolution, detailed climate scenarios through sensitivity experiments and reliability verification studies.

This presentation aims to introduce KMA's Earth System Models, aligning with recent trends and developments outlined in CMIP7, and presenting the overall plans for the generation and utilization of global-regional-local climate projections in line with CMIP7.

How to cite: Chung, C.-Y., Byun, Y.-H., Sung, H. M., Kim, J.-U., and Shim, S.: NIMS/KMA Plans for Climate Change Projection Production and Utilization on CMIP7, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17153, https://doi.org/10.5194/egusphere-egu24-17153, 2024.

Given the fact that many Icelandic volcanic systems are on the verge of an eruption, producing some of the largest volcanic eruptions over the past millennia, e.g., Öræfajökull, Bárðabunga, Grímsvötn and the Katla system, it is important to be able to predict potential changes in Northern Hemisphere (NH) climate variability in the following years after an NH eruption in due time. Recent volcanic activity in Iceland, e.g., Holuhraun 2014-2015 and Reykjanes/Geldingadalur 2021-2023, further demonstrates this urgency.

With the aim to contribute to improving the forcasting and adaptation strategies for the North Atlantic region we, as a first step, forced an Earth System Model (CESM1.2.2) with an idealized long-lasting high-latitude volcanic eruption to quantify i) the response within the stratospheric polar vortex and ii) the resulting response within the coupled climate system in the Northern Hemisphere (NH) by assessing the first 15 years following the eruption focusing on the winter (DJF) response. Here results will be presented showing evidence of sudden stratospheric warming events and a deceleration of the stratospheric polar vortex occurring in the second and third post-volcanic winter. This is identified in the temperature and zonal winds at 50hPa as a result of the large modelled surface cooling in the NH where Eliassen-Palmer wave flux calculations further support these findings. The strong stratospheric response identified further influences surface climate throughout the continental NH in the first 5 years following this event via the NAO. Our result suggest that two competing mechanisms are at work during these first years, partly explaining this long-lasting short-term response. The long-term impact is identified as a change in regional surface temperature and sea ice variability as well as a general strengthening of the AMOC, reaching a maximum in winter 2 and remaining positive throughout the run.

How to cite: Guðlaugsdóttir, H., Peings, Y., Zanchettin, D., and Magnúsdóttir, G.: Modelling the climate response following idealized long-lasting high latitude volcanic eruptions: The stratospheric response and resulting implications for North Atlantic surface weather, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19839, https://doi.org/10.5194/egusphere-egu24-19839, 2024.

EGU24-20254 | Orals | ITS1.10/CL0.1.9

Uncertainties of past volcanic forcing - Modelling the impacts of eruption parameters and atmospheric background conditions 

Kirstin Krüger, Herman Fuglestvedt, Zhihong Zhuo, and Andrea Burke

Reconstructions of past volcanic forcing rely on the assumption that the stratospheric sulphur loading from eruptions in the pre-satellite era is directly proportional to the sulphate flux recorded in polar ice sheets. The scaling factors, known as "transfer functions," used for this calculation are currently based on the Antarctic sulphate flux following the 1991 Pinatubo eruption, radioactivity in Greenland ice from nuclear weapon tests, and model simulations of two high-latitude eruptions. However, recent studies have shown that ice sheet deposition of volcanic sulphate varies significantly as a function of both eruptive parameters and the background atmospheric state, presenting an opportunity to enhance the accuracy and reliability of volcanic forcing reconstructions through improving the use of transfer functions.

 

Here, we investigate how the transfer function depends on eruption parameters and background conditions. Using simulations with the Earth system model CESM2-WACCM6, we explore a wide range of parameters, including eruption magnitude, latitude, plume composition, season, and plume height. By understanding the relationships between eruption parameters and resulting polar sulphate fluxes, we aim to improve the transfer function estimate used in the volcanic forcing for CMIP6 and shed light on the associated uncertainties.

How to cite: Krüger, K., Fuglestvedt, H., Zhuo, Z., and Burke, A.: Uncertainties of past volcanic forcing - Modelling the impacts of eruption parameters and atmospheric background conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20254, https://doi.org/10.5194/egusphere-egu24-20254, 2024.

EGU24-365 | Orals | ITS2.9/CL0.1.10

Spatio-temporal patterns of hydrological processes on non-floodplain wetlands in an upstream basin of Pampa Plain (Argentina) during present wet conditions  

Pablo Augusto Cello, Daniela M. Kröhling, Ernesto Brunetto, María Cecilia Zalazar, Reinaldo García, Mauro Nalesso, Jacinto Artigas, and José Rafaél Córdova

This work aims at deepening the knowledge of the mechanisms that govern the response of small temporary non-floodplain wetlands (NFWs) of neotectonic origin in the North Pampa under wet conditions. The study focuses on the Vila-Cululú upstream sub-basin (973 km2), a tributary of the Salado River belonging to the Paraná River basin. The Pampa Plain has been affected by more frequent high-intensity rainfall events during the last five decades giving rise to a steady increase in the water table and a decrease in soil infiltration, leading to flood events that impact both rural and urban environments. Under wet conditions, a flat landscape alters the surface runoff and favors the development of temporary NFWs, increasing flood vulnerability and jeopardizing human activities. Structural depressions with polygonal patterns and a network of Late Pleistocene (ca. 100 ka. BP) parallel ENE-trending fluvial palaeochannels characterize the study area. These palaeochannels were deactivated by neotectonics and covered by loess, Last Glacial Maximum in age. In some sectors, the palaeochannels intercept the small tectonic depressions and significantly restrict the present drainage network (low-order streams and artificial channels).  The research involved an integrated approach, including geomorphic and morphometric analyses based on remotely sensed satellite imagery in a GIS platform and fieldworks, and 2D hydrologic-hydraulic simulations using HydroBID Flood (hydrobidlac.org) to capture the system behavior for an extraordinary rainfall event (December 2016-March 2017). Simulation results show that the model represents hydrodynamics fairly well. The flooded areas were comparable to those obtained from the analysis of satellite images. The dendritic runoff pattern towards the tectonic depressions, the water storage evolution, and the hydraulic connectivity were numerically replicated. In particular, the Vila-Cululú sub-basin points out a significant delay in the hydraulic response downstream since the system must first satisfy groundwater and surface water storage. Once storage capacity is exceeded, the hydraulic behavior results in a dynamic process that involves the spilling and merging of ponds generated in small deflation hollows, generally nested within fluvial palaeochannels. Such a hierarchical structure controls surface runoff towards the shallow tectonic depressions. This mechanism gives rise to the development of NFWs as simulation time evolves. Besides, the surface runoff flow pattern also highlights the poor capacity of both natural and artificial drainage networks, displaying highly lateral mobility and scarce connectivity downstream. However, these NFWs eventually might connect to a more hierarchical drainage network downstream at the final stage of the storm event. The dense network of artificial channels started to develop in the 1940s to evacuate water excess to the outlet. Despite the anthropic interventions, geomorphologic thresholds finally control hydrodynamics adding to surface water storage and limiting channel conveyance. This work is one of the first studies in North Pampa that combines hydrological and geomorphological data to explain the present hydrodynamics. These could be applied to palaeoflood hydrology. Identifying critical geomorphological thresholds adds to the knowledge of different levels of hydrologic connectivity, providing a better assessment of flood hazards on large plains.

How to cite: Cello, P. A., Kröhling, D. M., Brunetto, E., Zalazar, M. C., García, R., Nalesso, M., Artigas, J., and Córdova, J. R.: Spatio-temporal patterns of hydrological processes on non-floodplain wetlands in an upstream basin of Pampa Plain (Argentina) during present wet conditions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-365, https://doi.org/10.5194/egusphere-egu24-365, 2024.

EGU24-3989 | Orals | ITS2.9/CL0.1.10

Groundwater effects on flood dynamics  

Wouter Berghuijs, Louise Slater, Ross Woods, and Markus Hrachowitz

Fluvial floods are typically the result of large precipitation or snowmelt events, often conditioned by high pre-event soil moisture levels. However, soil moisture represents only a small fraction of the water stored in landscapes. Groundwater, often a much larger water store, may also contribute a significant proportion of river flow but its role in large-scale flood assessments often remains understudied. Here I discuss how (ground)water storage conditions can shape multi-year variability and long-term trends of river flow and flooding across thousands of catchments worldwide. Since often relatively slow groundwater dynamics can affect the much faster and more erratic flood responses, incorporating groundwater may be important to accurately model and analyze these hydrological extremes.

How to cite: Berghuijs, W., Slater, L., Woods, R., and Hrachowitz, M.: Groundwater effects on flood dynamics , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3989, https://doi.org/10.5194/egusphere-egu24-3989, 2024.

EGU24-4382 | ECS | Posters on site | ITS2.9/CL0.1.10

Effects of Long-Term Wetland Variations on Flood Risks in the Yangtze River Basin  

Ziying Guo, Xiaogang Shi, and Qunshan Zhao

In the Yangtze River Basin (YRB), flooding is the most frequent natural disaster with enormous socio-economic damages. As a critical component in the hydrological cycle, the wetlands along the YRB have been changing during recent decades because of urbanization, intensive farming (e.g., aquaculture and agriculture) and climate change. Due to the lack of a long-term wetland classification dataset with comprehensive wetland categories, however, there’s a noticeable gap in the YRB water management regarding the relative roles of different wetland categories on flood resilience. Therefore, this study aimed to generate a long-term wetland classification dataset for the YRB and further investigate the long-term wetland variations on the YRB flood risk assessments for the period from 1985 to 2021. The dataset named Long-Term Wetland Classification Dataset for YRB (LTWCD_YRB) was created using a Random Forest machine learning classifier on Google Earth Engine with 30m resolution Landsat 5, 7, 8 muti-spectral images. The maps of LTWCD_YRB demonstrated the spatial distribution, annual variability, and seasonal cycle of nine wetland categories in the extent, and the total validation accuracy can reach 85%. The LTWCD_YRB indicated that the total wetland area of the YRB in 2021 was larger than that in 1985, with constantly increased human-made wetlands and fluctuated natural wetlands. Aquaculture ponds expanded the most (4,987 km2); inland marsh in the source region was the wetland category with the most fluctuations. Seasonal changes in wetlands were prominent in the Poyang Lake Basin, Dongting Lake Basin, and YRB source region. The LTWCD_YRB can offer a consistent agreement of wetland area variations with the other satellite-based wetland datasets in the YRB, which is valuable for researchers and stakeholders to better understand the YRB wetlands and would support sustainable wetland management practices. With the LTWCD_YRB data as modelling inputs, a GIS-based spatial multi-index flooding risk assessment model was applied for investigating the long-term implications of wetland variations on flood risks in the YRB. The model results indicate that in the year with large floods and extremely high precipitation, flood risk level increased obviously after adding the wetland factor. For the years with normal precipitation, flood risk level decreased with wetlands expansion and increased with wetlands shrinkage in the YRB. The long-term expansion of aquaculture ponds contributed to a lower flood risk in the Taihu Lake Basin. In contrast, the Poyang Lake Basin experienced an increasing flood risk due to the long-term shrinkage in lake areas resulting from soil erosion and urbanization along the lakeside. This study would be helpful for stakeholders to develop feasible wetland management practices, and to improve flood risk resilience in the YRB.

How to cite: Guo, Z., Shi, X., and Zhao, Q.: Effects of Long-Term Wetland Variations on Flood Risks in the Yangtze River Basin , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4382, https://doi.org/10.5194/egusphere-egu24-4382, 2024.

EGU24-4543 | ECS | Posters on site | ITS2.9/CL0.1.10

Flood frequency elasticity to extreme precipitation: a practical approach for Climate Change projection of flood probabilities 

Luigi Cafiero, Paola Mazzoglio, Alberto Viglione, and Francesco Laio

Flood risk management institutions and practitioners need  innovative and easy-to-use approaches that incorporate the changing climate conditions into flood predictions in ungauged basins. The traditional approach to regional flood frequency analysis enables the estimation of hydrological variables under stationary conditions. However, it is nowadays crucial to develop innovative techniques that consider the non-stationarity of climate variables. The present work aims at implementing an operative procedure to include the expected variation in precipitation extremes into regional analysis. We compare the Flood Frequency Curves (FFC) and the Intensity-Duration-Frequency (IDF) curves defining a relation between them through the elasticity, an indication of the sensitivity of floods to precipitation extremes. Under the assumption that this relation does not change in time, we obtain modified FFC according to the projections of an ensemble mean of 25 Cordex simulations of CMIP5. This methodology was applied to 227 catchments of the Po River basin in northern Italy. Elasticity values range between 0.5 and 2: the lowest values were found in Valle d'Aosta region, and the highest in the south-western part of Piemonte. Over the Po river basin, the percentage increase of the 100-year floods ranges between 15% and 40%. The most relevant increase of flood discharge is found in the area between Liguria and Emilia-Romagna in the southern part of the Po River basin, where the projected increase of precipitation extremes is the highest.

How to cite: Cafiero, L., Mazzoglio, P., Viglione, A., and Laio, F.: Flood frequency elasticity to extreme precipitation: a practical approach for Climate Change projection of flood probabilities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4543, https://doi.org/10.5194/egusphere-egu24-4543, 2024.

Existing research has provided evidence on how culture mediates disasters and exacerbates or mitigates their impact in various contexts but is often concentrated among popular cultural heritage or large scale culture phenomena. The significance of culture belonging to indigenous communities is less studied in mainstream climate change adaptation, despite its importance in helping build local social resilience to climate impacts. An Achang indigenous settlement located in the western part of China's Yunnan Province, where intense flash floods occurred frequently in its history, was used as a case study. The study aims to excavate the flood culture within the Achang community and examine how culture, particularly religion, blood-related organization, indigenous knowledge, and customary law have helped Achang communities for generations to build coping strategies to flood events. Data was gathered using participant observations in community activities, semi-structured interviews, more open thematic conversations, and document review in July 2023. Respondents included survivors for the storytelling, households for the semi-structured interview, and officers of the local authorities for the key informant interviews. The study found that the Achang community has a rich flood culture, which profoundly influences the behavior of the local people during flood events. First, the Achang people are culturally rooted in Buddhist tradition of nature worship and an equanimity view of living, forming an environmentally friendly community and providing a refuge for the spirit. Second, self-organization forms based on geography and kinship plays an important role in responding swiftly and maintaining long-term collaboration in times of flood. Thirdly, the Achang people's acquisition of ecological knowledge from nature has heightened their sensitivity to natural phenomena, enabling them to skillfully leverage their environment for home transformation and effective flood response. Finally, The Achang community is governed by a number of customary laws concerning flood prevention, which call on villagers to preserve forests, conserve soil and water, and contribute to post-disaster reconstruction for the common good. All of above provides an adaptable culture system from values-knowledge-institutions-practice with a strong ecological view and that is flexible enough to accommodate the adjustments needed to respond to changes. The relocation case in the Achang community illustrates that scientific disaster reduction decisions need to consider local flood culture to establish effective interventions in indigenous flood hotspots, further becoming the foundation for community resilience. As such, greater effort should be made by the State to full-scale investigations of these cultural, and the participation of indigenous flood culture in the planning and implementation of disaster risk reduction intervention.

How to cite: Ai, M., Yang, L. E., and Zhou, Q.: Culture system and social resilience to flood impacts - An investigation of Achang communities in Yunnan, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4720, https://doi.org/10.5194/egusphere-egu24-4720, 2024.

EGU24-5195 | Orals | ITS2.9/CL0.1.10 | Highlight

The unique 1432–2013 flood marks from the Děčín Castle Rock, Czech Republic, are scanned in 3D and utilized 

Libor Elleder, Tomáš Kabelka, and Jolana Šírová

Our contribution presents an example of archiving of an invaluable collection of flood marks. With respect to the height of the object carrying these flood marks exceeding 12 metres it is not possible to explore all flood marks in detail in situ. 3D scan, however, offers an excellent possibility how to solve this task. We have analysed the Děčín Castle Rock (further DCR) flood marks in context of their importance, history, recent scanning, reliability check and utilization.  The DCR ranks amongst the most important epigraphic hydrological objects in Europe. Three major reasons for that can be listed as follows: (i) the Děčín town geographical position represents the outflow of the whole Bohemia concentrating the water volume from the upper part of the Elbe river catchment, (ii) the presence of ancient flood marks (the oldest one representing the 1432 flood event) engraved in the sandstone Castle Rock, (iii) the striking relation between the DCR flood marks and the Děčín Hungerstone drought marks situated in its close vicinity  (only some 200 metres apart). It is not the number of flood marks but joint placement of both the flood and drought (low) marks which makes Děčín truly a unique place in European context. The whole flood and drought mark system served as a tool for ancient safe navigation for boats and rafts, and later ships and steamers. We place all these Děčín flood and drought marks in context of other important records in Prague, Litoměřice, and German Pirna, Dresden and Meissen. Furthermore, the oldest water level gauge – estimated to be at least 200 years old - is situated in the same place allowing for direct and easy reading of flood mark heights. Altogether, the Hungerstone drought marks and  DCR flood marks with the old water level  gauge in the Czech town of Děčín  represent an unparalleled complementary system of centennial information for extremely  low and extremely high water levels. Our Map of Extreme Floods (MEF, 2024) application currently offers selected floods the culmination water levels of which are engraved on the DCR, such as July 1432, August 1501, February 1595, February 1682, August 2002 and June 2013, the other will be available sooner (1824, 1890) or later (1771, 1784, 1799, 1830, 1845 and 1862).

 

Reference:

MEF, 2024.  Available at:

https://chmi.maps.arcgis.com/apps/MapSeries/index.html?appid=dc50b65b4483465cb98c50d4b55df75d.

 

How to cite: Elleder, L., Kabelka, T., and Šírová, J.: The unique 1432–2013 flood marks from the Děčín Castle Rock, Czech Republic, are scanned in 3D and utilized, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5195, https://doi.org/10.5194/egusphere-egu24-5195, 2024.

EGU24-9242 | Posters on site | ITS2.9/CL0.1.10

Contextualizing recent extreme floods in the Western Mediterranean region: insights from historical records and paleoflood hydrology 

Juan Antonio Ballesteros-Canovas, Tamir Grodek, Carlos Naharro, Josep Barriendos, Mariano Barriendos, Alicia Medialdea, Alberto Muñoz-Torrero, and Gerardo Benito

The Mediterranean region is expected to experience more extreme rainfall events due to climate change. These extreme weather events, together with the ever-increasing human occupation, could lead to an increase in the risk of flash floods. This situation could be worrying, as wildfires may occur during hotter and drier summers, which might increase the hydrological response. Adaptation and mitigation strategies need to be put in place at the level of water and civil protection authorities. However, this is challenging due to the widely recognised lack of data, the high variability of the Mediterranean hydroclimate, and previous shortcomings in the performance of climate-based models for the region. Here, we combine historical, geological and tree-ring data to provide a compressive multi-century reconstruction of flood frequency and magnitude for the Clariano River, a medium-sized (265 km2) Mediterranean catchment in the Province of Alicante (Spain). A historical flood database was collected from published compilations, documentary sources, photographic archives and newspapers. The Municipal Archive at Ontinyent provided flood evidence since CE 1320 with a continuous flood record since 1500. Slackwater flood deposits were studied in ten stratigraphic profiles on three river reaches, and flood units were dated by radiocarbon and optically stimulated luminescence. Finally, thirty-five scarred trees growing on floodplains in three different river reaches were sampled to record the occurrence of recent floods. In three river reaches, 1D and 2D hydraulic models were implemented on high-resolution topographies to convert palaeostages and historical levels into flood discharge. The multi-source data compilation provides evidence of at least 47 major floods since the 13th Century. Apart from the flood caused by the dam break in 1689, the magnitude of the most recent floods caused by mesoscale convective cells in 2016 and 2019 were similar to or slightly below in magnitude to those experienced during the rich flood period (1850-1895) following the end of the Little Ice Age. This implies that the information on past extreme floods could be used as a scenario-based approach to quantify expectations of recent extreme floods under climate change scenarios. Furthermore, our records have allowed a more accurate estimation of flood frequency in Ontinyent city, which could be used to provide a more robust flood hazard zonation. Throughout this comprehensive study, we show that quantitative historical and palaeoflood hydrology allows the determination of past and recent flood magnitude response to climate variability, reducing the uncertainties in flood hazard and risk assessment in the Mediterranean region.

How to cite: Ballesteros-Canovas, J. A., Grodek, T., Naharro, C., Barriendos, J., Barriendos, M., Medialdea, A., Muñoz-Torrero, A., and Benito, G.: Contextualizing recent extreme floods in the Western Mediterranean region: insights from historical records and paleoflood hydrology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9242, https://doi.org/10.5194/egusphere-egu24-9242, 2024.

EGU24-11182 | ECS | Posters on site | ITS2.9/CL0.1.10

Spatial signatures of flooding and blocking are related on the long-term scale 

Diego Hernandez, David Lun, Miriam Bertola, Bodo Ahrens, and Günter Blöschl

Process-based explanations of flood controls have increasingly advanced in the last years along with comprehensive datasets availability. However, the relationship on the long-term scale between floods and large-scale atmospheric drivers remains unclear, hindering the understanding of flood-prone periods and the projections of flood change. The translation of atmospheric blocking (i.e., a persistent mid-latitude high-pressure system that blocks westerly flows) into flooding has not been raised for large samples due to the spatiotemporal complexity of the atmospheric and hydrological response. For the 1950-2010 period, this study analyzes summer flood events from a pan-European database, a gridded binary blocking index derived from ERA20C, and hemispheric fields of four meteorological variables from ERA5. By defining a window of days with flooding (dF) related to precipitation surpluses in central Europe, days with blocking (dB) at three different regions namely North Atlantic (NATL), Europe (EU) and Scandinavia (SCAN), and days with simultaneous flooding and blocking (dFxB), our results indicate spatially similar meteorological signatures for dF and dFxB at NATL, but different patterns between dB and dFxB at NATL, suggesting there is a subset of blocking events at NATL controlling the meteorological signature of flood events in central Europe. Patterns for dB and dFxB at SCAN are similar implying that blocking in the SCAN region has the most direct effect on floods in central Europe. Hence, this research could provide new insights into large-scale atmospheric controls and sources of predictability regarding floods.

How to cite: Hernandez, D., Lun, D., Bertola, M., Ahrens, B., and Blöschl, G.: Spatial signatures of flooding and blocking are related on the long-term scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11182, https://doi.org/10.5194/egusphere-egu24-11182, 2024.

EGU24-11746 | Posters on site | ITS2.9/CL0.1.10

The October 1787 Ebro flood: the biggest flood event of NE Iberian Peninsula in the last 500 years 

Josep Carles Balasch Solanes, Josep Barriendos, Mariano Barriendos, Jordi Tuset, and David Pino

The reconstruction of past flood episodes is of vital importance in the study of river dynamics for assessing the impact of climatic and environmental changes, and evaluating the risk of these disasters on current populations. The main objective of this study is to present a multidisciplinary analysis of the catastrophic flood episode that occurred in the Ebro River basin (85,000 km2) on 8th-9th October 1787.

The methodology includes an extensive research from documentary sources of the damaged locations. By using this data, maps of the extent of the affected area and the temporal evolution of the event have been reconstructed. Then, utilizing the maximum water height (3 flood marks), numerical simulations of hydraulic and hydrological reconstructions have been carried out to obtain the peak flows and the amount of precipitation. The meteorological reconstruction utilizes daily barometric information collected at that time from different observatories in Western Europe to plot surface pressure maps to estimate wind direction and the location of the cyclonic centers.

The results show that this is the most serious episode that has occurred in the northeast of the Iberian Peninsula the last 500 years. There were more than 500 fatalities in the Lower Ebro area, numerous homes and structures were destroyed and the regional economy was damaged for several decades. The affected area was mainly the eastern Ebro basin (with 31 documented points), but it also extended to small areas of coastal basins of the Llobregat and Júcar Rivers (9 affected points). After about 10-12 consecutive days of rain caused by two active low-pressure centers combined with an influx of moist air from the Mediterranean Sea, some of the largest peak flows that the Ebro River has experienced since the beginning of the 16th century occurred. These flows reach to 12,900 m3·s-1 of the Ebro River in Tortosa (mean flow: 428 m3·s-1), 4,500 m3·s-1 of the Ebro in Zaragoza (mean flow: 231 m3·s-1), 4,500 m3·s-1 of the Segre River in Lleida (mean flow: 80 m3·s-1) and about 2,500 m3·s-1 of the Cinca River in Fraga (mean flow: 78 m3·s-1). According to historical accounts, the origin of the flood is purely pluvial without contributions of snow melting in the Pyrenees.

The specific peak flow of the Ebro in Tortosa (0.15 m3·s-1·km-2) exceed the flows of any large European river of the same basin size (Po, Danube, Rhine, Rhône). Therefore, we are facing an event of extreme magnitude that is essential to study and to explain fluvial variability and risk analysis.

How to cite: Balasch Solanes, J. C., Barriendos, J., Barriendos, M., Tuset, J., and Pino, D.: The October 1787 Ebro flood: the biggest flood event of NE Iberian Peninsula in the last 500 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11746, https://doi.org/10.5194/egusphere-egu24-11746, 2024.

EGU24-13047 | Posters on site | ITS2.9/CL0.1.10

Storm Daniel and the timing and magnitude of floods in Northeast Libya 

Chris Hunt, Hwedi El-Rishi, David Brown, and Jon Dick

Storm Daniel caused major flooding throughout much of the Jebel al-Akhdar massif in Northeast Libya, leading to huge damage and loss of life in the city of Derna and widespread damage to infrastructure through the region in September 2023. There is little historical record of significant floods in the region. We conducted dendrogeomorphological and palaeohydrological research in the wadis Kouf and Bottamsa in the Jebel al-Akhdar. Radiocarbon- and tree-ring dated flood return and flood magnitude sequences suggest three major floods during the 17th to 19th centuries AD in the Wadi Kouf and one major flood during the 18th Century in the Wadi Bottamsa, with major flood return intervals of about one per 100 years. The timing of the major floods in these two catchments seem to be different, suggesting the storms that caused them were localised. The major floods in the Wadi Kouf would have been large enough to have caused considerable damage to modern infrastructure, which seems to have been designed to cope with the much smaller floods of the mid-20th Century. Storm Daniel, however, was the product of a much larger weather system than the storms that gave rise to the earlier floods and it caused the largest floods in these wadis in the last 400 years.

How to cite: Hunt, C., El-Rishi, H., Brown, D., and Dick, J.: Storm Daniel and the timing and magnitude of floods in Northeast Libya, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13047, https://doi.org/10.5194/egusphere-egu24-13047, 2024.

Streamflow has a crucial role in the global water cycle. The demand for long-term daily streamflow observations becomes essential for robust water resources planning, hydroclimatic extremes analysis, and informed ecological assessments. However, there is a lack of availability of this type of dataset, particularly concerning the river basins of South Asia daily. The hydrologic-hydrodynamic model can simulate the streamflow over the domain. However, these models are not well calibrated to provide the locally relevant streamflow simulation daily. In response to this crucial knowledge deficit, in this study, we developed a state-of-the-art hydrological-hydrodynamic model to simulate daily streamflow spanning the years 1949 to 2022 across river basins South Asia by calibrating the model with observed daily streamflow. Leveraging meteorological observations meticulously gathered by the India Meteorological Department (IMD) inside India, and Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA2) outside domain, our model integrates the Noah MP as the land surface model and the HyMAP routing model to generate intricate daily streamflow dynamics within the South Asian sub-continental river basins. We calibrated the model at the 173-gauge stations against observed streamflow over South Asia. The calibration and validation time periods were 3 and 5 years respectively. This process ensures the adaptability and relevance to the local nuances of Basins in the model, aligning the simulated daily streamflow patterns with observed data. A comprehensive examination of the model's performance provides good results, with key metrics such as Kling-Gupta Model Efficiency (KGE), coefficient of determination (R2), and Nash-Sutcliffe efficiency (NSE) consistently exceeding a median threshold of 0.34. Taking our analysis further, we calculated the KGE skill score of the dataset, we found that 83/173 in calibration and 72/173 in validation showed KGE skill score more than 0.08. This extensive reconstruction and evaluation of streamflow dynamics not only contribute significantly to filling the knowledge gap but also lay the foundation for more precise and informed water management strategies in the dynamic landscape of South Asia's river basins.

How to cite: Prakash, V. and Saharia, M.: India Water Model: A Transboundary Water Modeling System Over South Asia and a 75-year Daily Streamflow Reanalysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15063, https://doi.org/10.5194/egusphere-egu24-15063, 2024.

Fluvial ecosystems are among the environments most significantly modified by human activities. Channelization, levee construction, floodplain disconnection from the riverbed, alteration of the fluvial regime and ecosystem, interruption of the sediment dynamics and alteration or destruction of the shape and morphology of the riverbed, are among the main effects of such interventions. Restoring or rehabilitating fluvial environments, including hydrological and geomorphological processes, is currently being undertaken in many river systems of the world given the benefits that these environments provide to mankind. However, depending on the magnitude of the human interventions and their impacts on the river system, reaching a restoration stage before human intervention cannot be fully achieved. In this context, the Congost River is a representative example of the evolution of the morphology of a river channel in the metropolitan area of Barcelona during the 20th and 21st century. The river flows through Granollers, a city of 60,000 inhabitants exposed to flood risk. During the 70s and 80’s the Congost river was channelized, narrowed and disconnected from its floodplain to promote urban and industrial growth.  The river channel was then fixed to avoid lateral migration by constructing sleepers (transversal structures), and fluvial landforms such as secondary channels and gravel bars were intentionally removed from the riverbed to create a drainage channel. However, to recover green riverine areas, sleepers in the peri-urban area of Granollers were demolished, whereas in the urban core area sleepers were conserved.

Analysis of aerial images of 1945, 1956, 1986, 1998, 2009 and 2022 shows the following transformation: the natural braided channel, adapted to slope, flood frequency and sediment load changed after the human intervention to a restrained channel. The result of the restored river stretches showed higher hydro-morphological characteristics than the urban section, but they are still far from the expected outcomes of a fully successful restoration of a braided river. Yet, the channel morphology improves natural river processes. At this point, however, it is not known how the riverbed will evolve in terms of incision or avulsion, and whether further river management measures will be necessary to implement. Monitoring of channel evolution is required to fully understand the human impacts on partially restored urban fluvial systems through time. 

How to cite: Farguell, J., Ferreira, F., Moreno, M., Barriocanal, C., and Schulte, L.: Human-induced alterations to the morphology of an urban Mediterranean watercourse from 1945 to 2022: transitioning from its natural state to phases of correction and restoration. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16354, https://doi.org/10.5194/egusphere-egu24-16354, 2024.

EGU24-17027 | ECS | Posters on site | ITS2.9/CL0.1.10

A comprehensive framework for the application of IF and TCIF theoretically derived distributions in Southern Italy 

Martina Ciccone, Andrea Gioia, Vincenzo Totaro, Federica Mesto, Maria Rosaria Margiotta, Salvatore Manfreda, Mauro Fiorentino, and Vito Iacobellis

An increasing amount of evidence is now available for demonstrating how flood series often incorporate data coming from different populations, thus emphasizing the need to understand the physical nature of floods before carrying out their probabilistic analysis. Theoretically derived distributions of floods were introduced by Eagleson (1972) as an alternative, probabilistic and physically based modelling of processes responsible for flood generation. Based on this framework, Iacobellis and Fiorentino (2000) proposed the IF probability model in which the direct contribution to peak flow is obtained as the product of partial contributing area and the discharge per unit of area, both considered as random mutually dependent variables. Moving from the consideration that floods can be triggered by different runoff productions mechanisms, Gioia et al. (2008) introduced the TCIF probability model.  IF and TCIF distributions were successfully applied on a wide area of Southern Italy, which includes Puglia, Basilicata and Calabria regions, providing advances in the understanding of physical phenomenology of flood generation in these areas. In our research we revisited the parametric structure of these theoretically derived distributions applied in the entire Southern Italy, exploiting, among other, the availability of updated rainfall data and previous knowledge developed within the framework of VAPI project. Results showed the good performances of both distributions in fitting annual maxima of flood data, highlighting how IF and TCIF distributions possess a solid background for interpreting the actual underlying flood generation processes. Findings of the study can represent a reliable source of information for supporting model selection activities at both local and regional scales.

How to cite: Ciccone, M., Gioia, A., Totaro, V., Mesto, F., Margiotta, M. R., Manfreda, S., Fiorentino, M., and Iacobellis, V.: A comprehensive framework for the application of IF and TCIF theoretically derived distributions in Southern Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17027, https://doi.org/10.5194/egusphere-egu24-17027, 2024.

EGU24-17145 | Orals | ITS2.9/CL0.1.10 | Highlight

Can reservoirs and dams effectively reduce flood runoff in river basins? A case study of the Rhine basin 

Ralf Merz, Gustavo Andrei Speckhann, Viet Dung Nguyen, and Bruno Merz

Flood retention basins constitute a pivotal component of flood protection measures. Local studies have unequivocally demonstrated their efficacy in significantly mitigating flood discharges, thereby minimizing potential downstream damage. However, the impact of these retention basins on the reduction of flood discharges at the large river basin scale remains ambiguous.

This study delves into the assessment of the influence wielded by reservoirs and dams on the reduction of flood discharges within the Rhine basin. Employing a spatially distributed version of the HBV model and Nash-cascade routing, daily discharges from 912 sub-catchments spanning the period 1951-2020 were simulated. The modeling approach comprehensively incorporates the influence of 192 reservoirs in the Rhine catchment on daily runoff volumes. Calibration at 200 gauging stations, facilitates a regional parameterization of the model, based on the PASS method.

Through various scenarios, the study explores how large-scale flood discharges would evolve in the absence of reserves for flood protection or if there were alterations to the storage capacity and function of individual reservoirs. Beyond merely assessing the reduction of runoff peaks, the research scrutinizes alterations in the duration of individual flood events and their spatial expansion, taking into account the intricate network of the 192 reservoirs.

In essence, this study not only contributes to the ongoing discourse on the efficacy of flood retention basins but also sheds light on the nuanced dynamics of reservoirs and dams in shaping the hydrological landscape of the Rhine basin. The findings provide valuable insights for optimizing flood protection strategies, encompassing considerations of storage capacities, operational functions, and the broader spatial and temporal dimensions of flood events.

How to cite: Merz, R., Speckhann, G. A., Nguyen, V. D., and Merz, B.: Can reservoirs and dams effectively reduce flood runoff in river basins? A case study of the Rhine basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17145, https://doi.org/10.5194/egusphere-egu24-17145, 2024.

EGU24-17170 | ECS | Posters on site | ITS2.9/CL0.1.10

Decoding spatiotemporal pattern of flood episodes and climatic variability in western and eastern catchments of the Southern Alps, New Zealand. 

Alexander Schulte, Lothar Schulte, Juan Carlos Peña, Ian C. Fuller, Filipe Carvalho, and Sebastian Schulte

In the Northern Hemisphere, the PAGES Floods Working Group database documents 345 paleoflood studies, while in the humid temperate zones of the Southern Hemisphere, studies are limited due to differences in i) continent and ocean distribution, ii) population density, iii) settlement history, and iv) documentary sources. Assessing Southern Hemisphere flood trends becomes a significant goal in the context of Global Change. Our study focuses on spatial-temporal reconstruction and climatic characterization of floods in New Zealand's southern regions (43° – 47°S) from 1862 to 2020 CE.

Due to limitations in generating continuous flood series from the number of flood fatalities or economic losses over the past 160 years, we opted to reconstruct regional indices of historical flood severity and spatial incidence. To accomplish this, we compiled three regional synthetic flood databases from the New Zealand National Institute of Water and Atmospheric Research's catalogue of historical meteorological events. The flood severity matrix integrates various parameters, including numbers of fatalities, witness descriptions of peak flows, flooded areas, geomorphological impacts, losses of livestock, properties, and infrastructure, as well as information on evacuation and mitigation measures. We reanalyzed information from more than 8,000 data entries and reviewed 903 impact points to characterize a total of 295 floods. Additionally, the influence of climatic variability, as inferred from the Principal EOF of the Sea Level Pressure monthly anomalies, was reconstructed using data from the 20th Century Reanalysis Project.

The three flood damage series, comprising 295 floods, reveal several synchronous flood pulses around the years 1878, 1905, 1913, 1957, 1968, 1978, 1999, and 2008 CE. However, other flood pulses are out of phase due to different physiographic settings, catchment size, location on the western (West Coast) or eastern slope of the Southern Alps (Otago and Southland), and exposure to oceans and paths of weather systems.

Notably, in the West Coast Region with very high relief and steep slopes, the most severe floods occurred in spring and summer. Seven out of ten flood pulses recorded from 1862 to 2020 correlate with positive Southern Annular Mode, higher sea surface temperatures (SST), blocking weather types in summer, and lows over the Tasman Sea, resulting in increased humid airflows from the north and northwest.

The larger Otago catchments, comprising humid alpine relief in the northwest, dry basins and ranges in the central area, and humid lowlands in the east, experienced the maximum number of severe floods during summer. Ten out of fourteen pulses occurred during the positive phase of the Southern Oscillation Index (La Niña), characterized by higher SST, blocking types in summer and autumn, and an increase in northeasterly winds.

In contrast, the landforms of Southland, featuring lower ridges, gentler slopes, and large floodplains, saw floods primarily in summer and autumn. Ten out of fourteen pulses in this region correlated with negative phases of the Southern Oscillation Index (El Niño), characterized by lower sea surface temperatures, more zonal flow, and troughs with stronger and more frequent winds from the west in summer and the south in winter.

How to cite: Schulte, A., Schulte, L., Peña, J. C., Fuller, I. C., Carvalho, F., and Schulte, S.: Decoding spatiotemporal pattern of flood episodes and climatic variability in western and eastern catchments of the Southern Alps, New Zealand., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17170, https://doi.org/10.5194/egusphere-egu24-17170, 2024.

Written mainly in German and partly in Latin, the chamberlain accounts of historical Pozsony/Pressburg (present-day Bratislava), almost continuously available between 1434 and 1595 and 1595, contain daily/weekly resolution data on Danube floods, low flows, ice cover and various weather phenomena. Analysed and presented for the first time, the 176 volumes of the accounts provide systematic, annual accounts of incomes and expenses, with only occasional gaps: flood- and weather-related reports are mainly included in the bridge masters’, the ferrymen’s, the ice-cutters’, the town messengers’, and the road and wall maintenance accounts. Furthermore, water-level related information occasionally was also identified in other sections of the accounts, regarding smaller bridges, river transportation, fishing, meadows and hayfields, woods, and other utilities of the nearby island area. With applying additional information available in the broader Bratislava area and the Carpathian Basin in other contemporary sources such as charters, letters, diaries and other narratives, it is possible to provide unusually high resolution, (quasi-)systematic three-scaled index-based quantitative reconstructions of the frequency, intensity, types (incl. ice-jam floods) and seasonality of Danube floods, and occasionally also of low water-levels.

The greatest floods usually occurred during flood-rich periods; unique great (ice-jam) floods outside of the flood-rich decades happened, for example, in 1454 and 1458. Flood-rich periods were identified during the 1430s-1440s, around the 1480s-1510s and in the mid- and late 16th century – while the first anomaly was also a period of a more frequent water-level variability including memorable low flows, the latter three periods coincide with major European flood-rich periods identified in the last 500 years (see Blöschl et al. 2020). As floods in Bratislava mainly reflect on the hydroclimatic conditions of the Upper-Danube and partly those of the Middle-Danube area, the dataset also provides exceptionally valuable, systematic information to the analysis of 15th-16th century (covering the famous, long Spörer solar minimum) climate variability in Central Europe. Furthermore, major groups of contemporary flood response, prevention and mitigation methods, especially detectable during flood-rich and low-flow periods, are also presented and analysed in the paper in comparison with the available other Middle-Danube (documentary and archaeological data based) evidence, in a broader Danube and Central European context.

How to cite: Kiss, A.: Danube floods, low flows and flood resilience at Bratislava in 1435-1595:Analysis of daily/weekly resolution flood-related evidence in a European context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18900, https://doi.org/10.5194/egusphere-egu24-18900, 2024.

EGU24-19193 | Posters virtual | ITS2.9/CL0.1.10 | Highlight

Shaping long-term human-environmental dynamics in a floodplain landscape of the Pannonian Plain (Central Europe) over the last millennium 

Zsolt Pinke, Balázs Pal, Beatrix F. Romhanyi, Csilla Zatyko, and Zsolt Kozma

Aiming at a deeper understanding of long-term feedback and interactions, here we reconstructed the changing socio-ecological system of a 9931 km2 wetland landscape over the last millennium. The study area is situated in the steppe-forest zone representing a major part of World Heritage inland salt grasslands in Europe.

Merging GIS-based historico-geographical and archaeo-topographical records from the 11th–mid-16th centuries, detailed spatiotemporal dynamics of settlement patterns, and random information on vegetation and economic activities were reconstructed. Testing the mean elevation of archaeological remains of settlements (sites) and the average soil agro-suitability in their buffer zones by non-parametric t-tests we found an extensive dispersion of settlements in the fertile deep floodplains at the turn of the 11th and 12th centuries but this reclaimed flood zone had been abandoned by the early 14th century. Statistical test results also suggested that the late medieval (LMA) (14th–mid-16th centuries) group was situated significantly higher than the high medieval (HMA) group (late 10th–13th centuries), and the deserted settlements were situated lower than the permanently settled group. Certain geomorphological formations, floodplain islands, and low fluvial ridges became scenes of settlement abandonment, while a dynamic concentration took place on high ridges. These outcomes suggest that the settlement pattern shrunk and vertically displaced significantly by the 14th-century beginning of the Little Ice Age (LIA) when hydrological challenges emerged all over Europe.

Testing the statistical-based settlement-indicated-flood-zone method in a 237 km2 area by an integrated hydrological model concerning the elevation of sites, we simulated the HMA, LMA, and late 18th-century extension of flood zones.

However, not only climatic conditions but anthropogenic transformation in runoff conditions of the upper catchment may also have triggered hydrological challenges in the low-lying plains. The reconstructed transformation of medieval settlement patterns in the Tisza basin (157000 km²) suggests that tens of thousands of square kilometers of virgin forests could have been destroyed in that age. Adapting to a changing hydro-climatic and socio-economic environment a complex community-based ‘livestock-water-crop farming’ trinity evolved, and livestock breeding and export became the strategic sector in the plain over the next centuries.

The socio-economic basis of mixed farming collapsed by the 18th century. As a response to chronic socio-economic backwardness and emerging hydro-climatic challenges, the aristocratic elite began the biggest river regulation in 19th-century Europe, which transformed the plain into a homogenous agricultural area (1950s cropland covering ~70 %).  However, this adaptation strategy failed, and the land use regime of the plain has fallen into a longstanding crisis today. To demonstrate this transformation between the late 18th century (water cover ~30 %) and today (water cover <5 %), we present a series of land cover reconstructions based on digitalized military maps (1782–1785, 1858, 1940–1944 and 1953–1959) and the Corine2018 dataset. Finally, we digitalized the first known flood map (2246 km²) of the region presenting the inundated areas during the catastrophic flood of 1879, the turning point of the century-long wetland reclamation, when the extension of inundated areas was essentially similar to that of the late 18th-century wetlands.

How to cite: Pinke, Z., Pal, B., F. Romhanyi, B., Zatyko, C., and Kozma, Z.: Shaping long-term human-environmental dynamics in a floodplain landscape of the Pannonian Plain (Central Europe) over the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19193, https://doi.org/10.5194/egusphere-egu24-19193, 2024.

EGU24-19865 | Orals | ITS2.9/CL0.1.10 | Highlight

What contradictory signals in flood trends can tell us about drivers of hydrological change 

Gregor Laaha, Johannes Laimighofer, Nur Banu Özcelik, and Juray Parajka

Flood trends are commonly assessed based on instantaneous peak flows on an hourly timescale, as these are most relevant for flood management. However, when hourly data are missing, it has been suggested to perform flood statistics on daily flood values instead, assuming a scaling relationship that depends on the shape of the flood hydrograph and applies over the entire observation period (e.g. Bartens & Haberlandt, 2021).

In an Austria-wide assessment, recent flood trends show diverging spatial patterns that contradict such a stationarity assumption. Interestingly, an aggravation of the flood situation is mainly observed for the peak flow (IPF), while the high values of the mean daily discharge (MDF) show much smaller and, importantly, less significant trends.

Rather than applying flood statistics corrections (e.g. Beylich et al. 2021), the aim of this contribution is to use flood divergence at different timescales as a mean of inferring likely drivers of flood trends. To this end, we combine several established and innovative indicators, such as a trend divergence index (peak versus daily flood scale), a seasonal trend index (to infer information about flood generation processes), and a seasonal shift index (to infer changes in the relevance of these processes). We show the extent to which these indices can inform us about likely drivers of change, i.e. climate-related vs. anthropogenic changes in the catchment. We discuss how these indicators perform in the light of existing flood scale indices, such as the flood timescale (Gaál et al., 2012) and the peak-volume ratio (Bartens & Haberlandt, 2021). The results suggest that the conflicting space-time patterns contain a wealth of information that is highly informative about changes in flood controls under global change.

References:

Bartens, A. and Haberlandt, U.: Flood frequency analysis using mean daily flows vs. instantaneous peak flows, HESS Discussions, https://doi.org/10.5194/hess-2021-466, 2021.

Beylich, M., Haberlandt, U., and Reinstorf, F.: Daily vs. hourly simulation for estimating future flood peaks in mesoscale catchments, Hydrology Research, 52, 821–833, https://doi.org/10.2166/nh.2021.152, 2021.

Gaál, L., Szolgay, J., Kohnová, S., Parajka, J., Merz, R., Viglione, A., and Blöschl, G.: Flood timescales: Understanding the interplay of climate and catchment processes through comparative hydrology, Water Resources Research, 48, W04511, https://doi.org/doi:10.1029/2011WR011509, 2012.

How to cite: Laaha, G., Laimighofer, J., Özcelik, N. B., and Parajka, J.: What contradictory signals in flood trends can tell us about drivers of hydrological change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19865, https://doi.org/10.5194/egusphere-egu24-19865, 2024.

Based on monthly resolved temperature and precipitation indices for Central Europe since 1500, which are derived from the virtual research environment tambora.org, statistical methods are presented to use the drought and moisture indices derived from tree ring data such as the scPDSI by Cook et al. (2015), long historical indexed flood series (Bloeschl et al (2020) as well as local and regional wine quality series to improve and refine periods of high and low water levels. Additionally, it will be demonstrated, how this approach can be used to interpolate climate parameters not only temporally but also spatially.

Therefore Bayesian methods are used to mutually verify and derive existing indices that are available on different scales. Furthermore, the references of indices to text quotes are mapped automatically. This not only makes the direct weather, weather and climate descriptions accessible, but also their immediate causes as well as the consequences and effects on the environment and societies. Overall, with this approach, new text quotes can be automatically analysed and integrated into the data pool. This also creates a bridge between historical and recent data and information.

How to cite: Kahle, M. and Glaser, R.: Statistical approaches to the integration of multi-proxy data for the reconstruction of high and low water episodes in Central Europe of the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20506, https://doi.org/10.5194/egusphere-egu24-20506, 2024.

EGU24-20773 | Orals | ITS2.9/CL0.1.10

Nationwide flood risk assessment using large ensemble climate change dataset and the Rainfall-Runoff-Inundation model 

Takahiro Sayama, Jiachao Chen, Yoshito Sugawara, and Masafumi Yamada

Floods pose significant threats, particularly in the context of climate change. This research focuses on a comprehensive analysis of river flooding nationwide in Japan. We utilize the latest dynamic downscaling data, d4PDF-5km, for the entire country, feeding this information into the Rainfall-Runoff-Inundation (RRI) model with a spatial resolution of 150 meters. The objective is to efficiently estimate the probability discharge of all rivers by developing a new method for extracting rainfall events from long-term ensemble data.

 The proposed method involves extracting heavy rainfall events from 720 years (12 ensembles of 60-year records) of downscaled data for each present, 2K and 4K scenarios and inputting them into the RRI model. This approach allows for the estimation of quantiles by analyzing peak flow as non-annual data with the peak-over-threshold method. When applied to the Shikoku region, the results demonstrate the effectiveness of the method, with the ability to estimate probability flows exhibiting a bias of 10% or less compared to a comprehensive calculation of all rainfall events.

 Furthermore, the research identifies variations in the increase of peak flow under climate change, particularly emphasizing differences between the main river and its tributaries. Notably, smaller rivers in the upper reaches are more significantly influenced by changes in rainfall patterns than the lower reaches of the main river.

 The implications of this research extend beyond hydrologic science. The estimated probability flows and corresponding hydrographs serve as crucial boundary conditions for assessing local flood risk. This information is fundamental for informed river management by governments and local authorities. Additionally, private companies, residents, and other stakeholders can utilize this data for robust risk assessments. In conclusion, our research provides valuable insights and a practical methodology for understanding and mitigating flood risks in Japan, taking into account the complexities introduced by climate change.

How to cite: Sayama, T., Chen, J., Sugawara, Y., and Yamada, M.: Nationwide flood risk assessment using large ensemble climate change dataset and the Rainfall-Runoff-Inundation model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20773, https://doi.org/10.5194/egusphere-egu24-20773, 2024.

EGU24-21588 | Posters on site | ITS2.9/CL0.1.10

A 1500-year flood history in Romania using multi-archive reconstructions 

Maria Rădoane, Ioana Perşoiu, Gabriela Florescu, and Aurel Perșoiu

This study integrates documentary, instrumental, archaeological and sedimentological data to reconstruct periods of increased flooding in present-day Romania over the last 1500 years.

We identified 22 flood-rich periods between AD 600-650, 830-930, 990 – 1020, 1060 – 1110, 1136 – 1165, 1195 - 1245, 1304 - 1317 and 1340 – 1373, 1400 – 1440, 1460 – 1470, 1490 – 1540, 1560 – 1580, 1592 – 1622, 1635 – 1657, 1667 - 1675, 1699 - 1731, 1771 - 1793, 1831 – 1864, 1890 - 1920, 1930s, 1970s - 1980s, 1990s – present. Our reconstructions show an increase in the incidence of floods during the Medieval Climate Anomaly and towards the end of the Little Ice Age.

In order to understand the potential causes behind these flooding events, we have used reconstructions of seasonally-distinct air temperature, precipitation amount and atmospheric circulation patterns based on an array of proxy records (e.g., cave ice and speleothem stable isotopes, tree ring-based proxies).

The most extensive floods were recorded between AD 1050-1250, mostly in the extra-Carpathian region, attributed to the advance of humid Eastern Mediterranean air masses. Currently, there is no conclusive information about their magnitude during the Migration Period, although the limited information of fluvial origin supports a reduced flood magnitude compared to the Medieval Climate Anomaly. Over the last 500 years, floods with maximum geomorphological effects occurred at the end of the 18th and 19th centuries (1770 – 1800 and 1880 – 1920) across the entire study area, against the background of an unstable climate, marked by the intensification of westerly Atlantic circulation and frequent northward incursions of Eastern Mediterranean cyclones. These were followed in magnitude by recent events (1990 - present), favored predominantly by warm and humid Eastern Mediterranean air masses, and the intensification of the westerly circulation of Atlantic origin at the onset of the Little Ice Age (1460 – 1470 and 1490 – 1530).

Alongside the climate signal, floods in the last 500 years also exhibit a strong anthropogenic component, accentuated in the last 250 years.

How to cite: Rădoane, M., Perşoiu, I., Florescu, G., and Perșoiu, A.: A 1500-year flood history in Romania using multi-archive reconstructions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21588, https://doi.org/10.5194/egusphere-egu24-21588, 2024.

EGU24-21845 | Orals | ITS2.9/CL0.1.10

Reconstructing historical flash flood events in South-Eastern Spain: An integrated approach with multiproxy records and hydrological modeling 

Filipe Carvalho, Lothar Schulte, Carlos Sánchez-García, Antonio Gómez-Bolea, and Juan Carlos Peña

Flash floods in Mediterranean catchments are a significant threat. Over the last decades, research in this area has normally focus on recent events, largely due to the absence of long-range instrumental data. However, alternative sources like historical records and natural archives can offer valuable insights and improve our knowledge of past events. In this study, we conduct a reconstruction of major flash flood events over the past century that have impacted several catchments in the South-Eastern Spain, specifically in the Almanzora, Antas and Aguas catchments.

Our study adopts a multidisciplinary approach for the reconstruction of flash floods. We integrate a variety of instrumental gauge data, historic water level indicators on buildings and bridges, and descriptions of inundated areas and flood heights from historical documents. Additionally, we incorporate biomarkers indicative of flood levels, identified through lichenometric analysis of rock surfaces affected by water flow. This combination of diverse proxy records enables us to estimate the peak flow heights at several crucial locations within the study area. For the reconstruction of the maximum flood discharge, we perform a one-dimensional hydrological model across all study sites and in select smaller areas requiring a detailed understanding of the hydraulic behavior, we apply two-dimensional models.

The findings of this study reveal that, despite the region's characteristic low annual precipitation (less than 300 mm), it is occasionally subjected to extreme rainfall events leading to significantly high peak discharges. Typically, these meteorological episodes are associated with atmospheric circulation patterns involving blocking systems along the Mediterranean coast. Hydraulic modeling has identified peak discharges exceeding 5000 m3 s-1 during a major flash flood event in October 1973. This event stands as the most devastating in the past century, resulting in loss of human lives and extensive damage to numerous settlements in all the studied catchments. While other notable flash flood events occurred in 1924 and 2012, they were of lesser magnitude compared to the 1973 flood. Post the 1973 disaster, various hydraulic modifications to the river system were implemented. These included for instance a channelization of significant portions of the Almanzora's main channel and some tributaries, as well as the construction of a large dam. These interventions have contributed to a reduced flood risk in certain areas of the catchment, particularly in the lower sections near the Mediterranean Sea outlet. Nevertheless, recent land use changes such as extensive agriculture and tourism could contribute to changes in flow regime and increased flood vulnerability.

How to cite: Carvalho, F., Schulte, L., Sánchez-García, C., Gómez-Bolea, A., and Peña, J. C.: Reconstructing historical flash flood events in South-Eastern Spain: An integrated approach with multiproxy records and hydrological modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21845, https://doi.org/10.5194/egusphere-egu24-21845, 2024.

EGU24-21886 | Posters on site | ITS2.9/CL0.1.10

Wetland restoration and its effects on the hydrological conditions and provisioning ecosystem services – a model-based case study at a Hungarian lowland catchment 

Zsolt Kozma, Tamás Ács, Bence Decsi, Máté Krisztián Kardos, Dóra Hidy, Mátyás Árvai, Péter Kalicz, Zoltán Kern, and Zsolt Pinke

The alluvial character of the Great Hungarian Plain has long determined its land use. Human-environmental interactions and landscale patterns were characterised by adaptation to frequent floods and high water availability. Different socio-economical factors in the 18-19th centuries initiated major drainage works and river regulations. These works aimed to adjust hydrological conditions in the floodplains to meet the demands of a new land use approach. This focused on maximizing crop production as the dominant provisioning ecosystem service (ES) instead of the previous land use practice (e.g utilization a broader range of various ES by adaptition).

Over time, this new land use-water management strategy led to a trajectory of constrains: 1) Water demands of the agricultural landscape are restricted to a much narrower range than natural hydrological conditions, leading to damages during extremely dry or wet conditions; 2) Artificial drainage attempts to ensure this narrow range during wet periods in the protected former floodplain areas; 3) However, drainage increases water scarcity and drought damage during consecutive dry periods, which cannot be compensated by the irrigation system due to its limited capacity.

As a result of this outdated strategy and contemporary processes, Hungarian landscape management is facing a crisis. Climate and hydrological changes, the aging farmer community, agricultural sector profitability, alterations in the land use subsities, preferring greening and afforestation are among the leading factors of this crisis. These factors are likely to drive current land use conditions into a significantly altered riverine landscape scenario in the coming decades. Among the current environmental-economic-regulatory conditions, one of the most feasible alternative scenario focuses on water retention and the corresponding adaptive land use. However, the hydrological impacts of such alternative water management-land use on crop yield remain poorly understood.

We examined this by using hydrological simulations at a 272 km2 study site located next to the River Tisza. Here, the morphology of the heterogeneous terrain offers a remarkable semi-natural storage capacity as it encompasses a deep floodplain area.

We defined six different water governance-land use scenarios. First, three water management scenarios were defined and simulated: reference, excess water retention, and flood retention. Along these scenarios inland excess water (a specific type of flooding) hazard maps were used as an indicator for potentially reclaimable floodplains. Next, an alternative land use map was derived following the prevailing Hungarian landscape planning logic, considering factors such as present location and proportion of current agricultural croplands, grasslands, forests, settlement; soil conditions, water availability (agricultural suitability), and nature conservation status.

An integrated hydrological model was set up with the MIKE SHE software to depict spatio-temporal variations in water resources under present conditions (with an operational drainage system) and for all described alternative cases (without a drainage system). Simulated groundwater levels were a key output used to estimate changes in crop yields at selected pointwise locations. The results indicate significant potential for nature-based hydrological adaptation and co-benefits for provisioning ES.

The project FK20-134547 has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary.

How to cite: Kozma, Z., Ács, T., Decsi, B., Kardos, M. K., Hidy, D., Árvai, M., Kalicz, P., Kern, Z., and Pinke, Z.: Wetland restoration and its effects on the hydrological conditions and provisioning ecosystem services – a model-based case study at a Hungarian lowland catchment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21886, https://doi.org/10.5194/egusphere-egu24-21886, 2024.

EGU24-493 | ECS | Orals | ITS5.12/CL0.1.11

Nitrogen removal and carbon mineralization under coastal salinity intrusion 

Ziyan Wang and Benoit Thibodeau

Rapid population growth and intensification of human activities have led to a massive increase in the release of nitrogen (N) to the environment, often ending up in aquatic ecosystems. Coastal wetlands, a transition ecosystem in the freshwater-to-marine continuum, play a vital role in reducing nitrogen through natural processes, including denitrification and anaerobic ammonium oxidation (anammox). Considering denitrification's risk of producing nitrous oxide—a potent greenhouse gas—and anammox's efficient co-removal of ammonium and nitrite, it's crucial to identify what controls the balance between these two key processes. However, the identity of the drivers controlling the relative abundance of these two N-removal processes and their respective interactions with carbon (C) and sulfur cycles are not well-documented, especially in coastal wetlands.

This study investigated salinity's role in N reduction with carbon remineralization in coastal wetlands facing salinity intrusion. Using air-dried mangrove sediments mixed with anoxic artificial seawater of contrasting salinities (0, 10, 20, and 30 ppt) over a 28-day period, we monitored N and C transformation by the concentration of NH4+, NO2-, NO3-, dissolved inorganic carbon (DIC) and total alkalinity in the supernatant, and microbial community adaptation in sediment by molecular analysis. We applied the revised 15N-paring isotope technique in slurry incubation to quantify the potential of N loss pathways.

Preliminary results indicate that significant N removal starts after a week of internal cycling between organic and inorganic N, with the maximum removal potential at 30 ppt salinity. Depletion of NO3- in the last week of incubation makes anammox stand out by utilizing NH4+ and NO2-. The rate of DIC release decreased with increasing salinity, displaying an inverse pattern to that of N species. This decoupling points to the co-existence of autotrophic anammox, heterotrophic denitrification, and sulfate reduction processes. The stoichiometric ratio of total alkalinity to DIC suggests a shift of the predominant carbon decomposition process as salinity increased, from denitrification to sulfate reduction. This shift could enhance the total nitrogen removal potential while slowing carbon remineralization, indicating a positive feedback loop for both nitrogen removal and blue carbon storage in response to salinity intrusion. We will further focus on 15N2 samples and microbial evidence to elucidate the interplay among nitrogen removal processes.

How to cite: Wang, Z. and Thibodeau, B.: Nitrogen removal and carbon mineralization under coastal salinity intrusion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-493, https://doi.org/10.5194/egusphere-egu24-493, 2024.

EGU24-516 | ECS | Posters on site | ITS5.12/CL0.1.11

The use of nature-based solutions (NbS) for coastal restoration actions and biodiversity protection: the A-AAgora project for Ireland. 

Melanie Biausque, Darragh O'Suilleabháin, Lee Wah-Pay, and Emma Verling

Nature-based solutions (NbS) at the coast are, by definition, methods developed to work with nature to sustainably protect, restore and/or manage the shore. They can be classified into 4 main categories such as fully natural solutions, managed natural solutions, hybrid solutions and ‘green’ engineering solutions. As part of the EU Mission: ‘Restore our ocean and waters by 2030’, the Horizon Europe-funded Atlantic-Arctic Agora (A-AAgora) project identifies innovative solutions, including NbS, to co-develop coastal restoration actions in association with nature and people, throughout 3 demonstration areas. In this context, Demo Ireland locally adapted the ‘living lab’ approach via community-led actions undertaken at Harper’s Island, Co. Cork. Managed and hybrid NbS, for instance livestock grazing, control of invasive species (Spartina), development of pollinator areas, etc…, were successfully tested, supporting coastal wetland restoration and significantly enhancing local biodiversity. NbS deployed by communities at Harper’s Island, with the support of Cork County Council, were then described and reported, allowing their replication to the whole island of Ireland, and overseas. Moreover, additional sites facing coastal erosion and tidal flooding issues were selected and monitored along the Co. Cork coastline. Preliminary results allowed us to identify the main coastal challenges for each site in association with local geomorphological patterns and hydrodynamics, in a context of climate change. The next step for the A-AAgora project in Ireland is to identify suitable NbS as sustainable solutions and long-term management actions, to tackle coastal challenges in those areas. Moreover, this ongoing work is carried-out with the collaboration of multiple stakeholders, such as scientists, decision makers and communities. While these methods have been developed at local scales in the south of Ireland, they can be reproduced and upscaled in other areas, further raising global awareness about coastal adaptation and coastal sustainable solutions/managements.

How to cite: Biausque, M., O'Suilleabháin, D., Wah-Pay, L., and Verling, E.: The use of nature-based solutions (NbS) for coastal restoration actions and biodiversity protection: the A-AAgora project for Ireland., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-516, https://doi.org/10.5194/egusphere-egu24-516, 2024.

EGU24-1790 | Posters on site | ITS5.12/CL0.1.11

Surface sediment permeability and reactivity in a shallow coastal environment 

Stefan Forster, Hanna Schade, and Werna Werna

Coastal sediments are frequently permeable due to their relatively large grains size. Knowledge on exchange processes across the sediment-water interface and metabolism in these sediments is limited however. We characterize permeable sediments at about 5 m water depth in a coastal stretch of ~3.5 km² at the southern Baltic coast off Germany. Permeability ranged from 1.4 .10-12 m² to 11.3 .10-11 m² (organic content: 0.1% - 0.2% dry mass). We determined total oxygen uptake, TOU, of 10 – 28 mmol O2 m² d-1 from in situ measurements in the dark. Benthic net primary production determined in situ varied between 1 - 14 mmol O2 m² d-1.
We observed an increase in volumetric oxygen uptake rates in flow-through experiments when highly reactive glucose was supplied as substrate, pointing to the pivotal role of reactive organic substrate availability. However, we could detect only marginally enhanced TOU (uptake doubled at one out of three locations) when applying stirring rates inducing pore water flow in benthic chambers under natural conditions. We conclude that stimulating effects of permeability associated with pore water flow are not detectable in benthic exchange rates below a threshold of 7 .10-11 m² under field conditions. This threshold is higher than previously reported.
Ex situ experiments demonstrated that the distribution of oxygen in the sediment was affected by photosynthetic activity of microphytobenthos and by pore water flow. Benthic primary production determined by the dark-light shift method exceeded the summed fluxes of oxygen into the water and into the sediment driven by concertation gradients, and increased with light intensity as well as with organic substrate availability. These findings indicate that calculated net ecosystem metabolism can shift from autotrophy to heterotrophy owed to an increased consumption within the sediment during advection. We argue that under advective conditions the export flux of photosynthetically produced oxygen may differ from the flux under diffusive conditions. This may seriously impair photosynthesis rate determinations obtained from incubation experiments.

How to cite: Forster, S., Schade, H., and Werna, W.: Surface sediment permeability and reactivity in a shallow coastal environment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1790, https://doi.org/10.5194/egusphere-egu24-1790, 2024.

Construction of coastal infrastructure, e.g. seaward port facilities, frequently calls for sediment removal (dredging). Deposition of the dredging spoil at designated offshore sites (dumping grounds) disturbs the dumping ground sedimentary system, including the biota. Assessment of environmental effects of dumping requires monitoring of the system’s responses to the disturbance severity and persistence. In 2011-2017, we followed changes in sediment characteristics and descriptors of benthic (meio- and macrofaunal) assemblages (abundance, biomass, composition) in a shallow southern Baltic coastal area serving as a dumping site for dredging waste from a new harbour under construction at the coast. At the initial phase of the disturbance, the benthos responded rapidly (abundance and biomass reduction, altered composition), and equally rapidly recovered when dumping was temporarily suspended. After the dumping operations were resumed, the responses intensified, although apparent colonizers (benthic copepods in the meiobenthos and juvenile molluscs in the macrobenthos) tended to appear intermittently in the disturbed areas. The benthos remained impoverished in the altered habitat after dumping was terminated, reflecting the severity of habitat change.

How to cite: Radziejewska, T., Wawrzyniak-Wydrowska, B., and Bieniek, B.: A human driver of change in the southern Baltic coastal sedimentary system: monitoring effects of dredging spoil dumping on benthic communities , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3213, https://doi.org/10.5194/egusphere-egu24-3213, 2024.

EGU24-3820 | Posters on site | ITS5.12/CL0.1.11

Collaborative Citizen Science to Support Coastal Management 

Joseph Earl, Suzana Ilic, Alexandra Gormally-Sutton, and Michael R. James

Coastal communities in North West England face numerous anthropogenic challenges, including high vulnerability to the impacts of climate change, namely enhanced coastal erosion and flooding from sea level rise (Sayers et al., 2022), and marine litter. To manage heightening climate impacts, Flood and Coastal Management has transitioned from a defence to risk-based management, including a focus on building coastal system resilience through Nature-based Solutions (NbS) rather than physical defences. Building the resilience of people, including coastal communities, is critical to this transition, whereby their voices are heard and they can better prepare for these risks (EA, 2020). However, despite the strategic intent to engage and involve people, public participation in practice has been restricted by numerous challenges, perpetuating a continued lack of public involvement in decision making or resilience building.

This interdisciplinary project investigates whether such a deficit in public engagement in decision making can be overcome through a case study citizen science project called Coast Watchers at Rossall on the North West coast, which aims to collaboratively engage people in monitoring and responding to coastal challenges. The research embarked on several study phases to iteratively design, test and evolve the citizen science project collaboratively, involving various coastal monitoring activities and social science investigations. Results suggest that it is important to account for people’s local coastal values, motivations and concerns (Earl et al., 2022) when designing a collaborative approach to public engagement.

Crucially, the work explores the extent to which coastal communities can be engaged beyond citizen science monitoring and become active participants in a resilient and collaborative coastal management. The talk will present outcomes from a series of interviews with coastal practitioners and community members in the North West, exploring the challenges and opportunities for communities to be more involved in a collaborative coastal management. Findings will be discussed within a wider context, whereby they are contributing towards a Flood and Coastal Resilience Innovation Project, Our Future Coast (EA, 2022), which seeks to engage people in adaptation planning and co-designing NbS to better protect coastal communities around the North West coast from current and future challenges.

 

References

Earl, J., Gormally-Sutton, A., Ilic, S. and James, M.R. (2022). ‘Best day since the bad germs came’: Exploring changing experiences in and the value of coastal blue space during the COVID-19 pandemic, a Fylde Coast case study. Coastal Studies & Society, 1(1), pp.97-119.

Environment Agency (2020) National Flood and Coastal Erosion Risk Management Strategy for England. https://www.gov.uk/government/publications/national-flood-and-coastal-erosion-risk-management-strategy-for-england--2. [14/9/23]

Environment Agency (2022) Flood and Coastal Resilience Innovation Programme. https://engageenvironmentagency.uk.engagementhq.com/innovation-programme. [7/2/23]

Sayers, P., Moss, C., Carr, S. and Payo Garcia, A. (2022) Responding to climate change around England's coast: the scale of the transformational challenge. Ocean & Coastal Management, 225.

How to cite: Earl, J., Ilic, S., Gormally-Sutton, A., and James, M. R.: Collaborative Citizen Science to Support Coastal Management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3820, https://doi.org/10.5194/egusphere-egu24-3820, 2024.

EGU24-4081 | Orals | ITS5.12/CL0.1.11

Variable effects of ecosystem restoration in a eutrophic coastal lagoon: reoxygenation by increasing water exchange 

Niels A.G.M. van Helmond, Olga M. Zygadlowska, Robin Klomp, Wytze K. Lenstra, Mike S.M. Jetten, and Caroline P. Slomp

Increased anthropogenic activities are affecting water quality, e.g. leading to eutrophication and deoxygenation, culminating in biodiversity loss in coastal ecosystems globally. In the Southwest Delta in the Netherlands, large scale engineering to protect coastal areas against storm surges has turned several tidal inlets and estuaries into coastal lagoons and (marine) lakes. The water quality in these ecosystems has strongly deteriorated as a result of stagnation of bottom waters in combination with eutrophication. One such ecosystem, Lake Veere, showed signs of recovery after restoration of water exchange with the adjacent tidal marine Eastern Scheldt in 2004. In recent years, regular water monitoring has revealed the return of low-oxygen conditions, however, along with other signs of worsening water quality such as fish kills and jellyfish blooms. Here, we assess the role of the sediments in the (re)occurrence of low-oxygen conditions in Lake Veere. During two sampling campaigns in 2022, water column and sediment samples were collected. Geochemical analysis, including direct in-situ flux measurements with a benthic lander, revealed an increasing sedimentary oxygen demand (SOD) from the western (sea-side) part of the lake to the east, from ~10 to >100 mmol O2 m-2 d-1. This gradient in SOD opposes the observed trend in water column deoxygenation, with low-oxygen conditions predominantly prevailing in the central and western part of the lake and not in the east. This indicates that, despite restoration efforts, large parts of the lake are still highly sensitive to deoxygenation. Sediment analyses show the near-absence of iron-oxides, hence little capacity to buffer toxic hydrogen sulfide, which indeed accumulated in pore waters, reaching concentrations of up to 10 mmol L-1. In the central part of the lake, hydrogen sulfide even accumulated in the bottom waters, pointing towards its potential involvement in the observed fish kills in the region. Our results illustrate the difficulty of improving water quality through changes in water exchange alone because of strong legacy effects of eutrophication and deoxygenation in the sediment.  

How to cite: van Helmond, N. A. G. M., Zygadlowska, O. M., Klomp, R., Lenstra, W. K., Jetten, M. S. M., and Slomp, C. P.: Variable effects of ecosystem restoration in a eutrophic coastal lagoon: reoxygenation by increasing water exchange, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4081, https://doi.org/10.5194/egusphere-egu24-4081, 2024.

EGU24-7418 | ECS | Posters on site | ITS5.12/CL0.1.11

Iron mediated organic matter cycling in permeable surface sediments 

Zhe Zhou and Shouye Yang

Coastal permeable sediments cover 50-60% of the continental shelves and are important filters and bioreactors that sitting between the land and ocean. In permeable surface sediments, the dynamic porewater advection can lead to frequent redox oscillation, which significantly affects the coupled cycling of organic matter (OM) and iron. In our study, we focused on the most redox active iron fraction (extractable by 0.5 M HCl), and investigated their effects on OM degradation and retention. During the transition of redox conditions, Fe(III) oxyhydroxides were quantitatively found as the dominant electron acceptors for anaerobic OM remineralization. However, the release of reduced Fe was significantly delayed, with most Fe(II) (~96%) remaining in the solid phase either through adsorption or formation of authigenic Fe(II)-bearing minerals. Under frequent redox oscillation as typically observed in natural coastal permeable sediments, Fe(II) in the solid phase can be re-oxidized and repetitively used as electron acceptor for anaerobic OM remineralization (Iron “redox battery”). In addition, based on our field study along near- to offshore transect in the North Sea, we found that the most redox active iron trapped abundant of dissolved OM (54±20 times than DOM in porewater) that enriched in aromatic and oxygen-rich compounds. It indicates that iron may preferentially promote the retention of terrigenous and aromatic DOM in permeable sediments, thus serving as an important temporal storage for terrigenous OM in the coastal ocean. Further investigations of the dynamic Fe-OM interactions in coastal sediments are warranted to better understand carbon cycling in the coastal area. 

How to cite: Zhou, Z. and Yang, S.: Iron mediated organic matter cycling in permeable surface sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7418, https://doi.org/10.5194/egusphere-egu24-7418, 2024.

EGU24-8832 | Posters on site | ITS5.12/CL0.1.11

Dynamics of carbon pools and fluxes in the Don River Delta, Southern (European) Russia, and the estuary under the conditions of increasing marine factors 

Sergey Venevsky, Sergey Berdnikov, Victoria Gerasjuk, Vera Sorokina, Aleksey Kleshchenkov, Igor Sheverdyaev, Valerii Kulygin, and Natalia Lichtanskaia

The Don River Delta, bordering the Taganrog Bay in the Sea of Azov, is one of the major deltas of Europe, providing important ecological and economic services. The Sea of Azov is an enclosed sea, which is also the shallowest sea on the globe (the mean depth is 7 meters) with rich biological productivity.

It was indicated recently that both the Sea of Azov (Berdnikov et al, 2023) and the Don Delta (Venevsky et al, 2023), as well as the estuary area have undergone significant environmental transformations in the last four decades. The water temperature and salinity in the sea and the estuary increased to the never observed values mostly due to climate change (Berdnikov et al, 2023) and the prevailing wind directions changed to the westerlies bringing strong upward surges to the delta. Meanwhile, the Don River runoff significantly dropped started from 2007, while fluvial sediments delivery to the Don Delta were steadily diminishing already during 70 years due to the constructions of dams, human land use and runoff regulation (Venevsky  et al, 2023). Significant amount of suspended sediments from the Taganrog Bay enters the delta and salty waters intrusions to the delta are frequent during surges driven by the westerlies. Thus, the role of marine factors in the delta and estuary area of the Don increased in the last few decades in comparison with fluvial factors. Carbon sequestration in coastal areas considered to be the so-named natural solution for climate change mitigation. Thus, it is important to estimate the past, present and future carbon balance of the Don Delta and the estuary, especially accounting that the delta undergoes changes from being fluvial dominated to marine (wave and surge) dominated one.

We are currently involved in the study focusing on the quantification of carbon pools and fluxes in the Don Delta and the estuary. The study combines modelling approach with field observations and remote sensing data. Our field data included seasonal observations for 2006-2020 of total suspended solids, salinity, concentration of dissolved and suspended organic matter, and chlorophyll-a concentration in the river-delta-estuary continuum (the Lower Don River -Delta-Taganrog Bay). Remote sensing included Landsat and Sentinel images for upward surges episodes for the same period.  We use three combined models:  a hydrological model of the Don estuary area (DonDeltaHECRAS) for simulation of the river flow and water levels during surges; model of suspended matter dynamics (DonDeltaBalanceModel), which allows us to calculate the suspended matter dynamics in the Don estuary area; and model of vegetation and soil dynamics (DonDeltaEcoModel), which is aimed at estimating the carbon accumulation in vegetation and soil in the delta. We found out that with the recent frequency of surges on average 20% of organic chemicals transported with the river runoff is deposited in the delta. Thus, marine factors affect accretion of soil within the delta and change both the carbon pools and fluxes in the delta and the estuary.

How to cite: Venevsky, S., Berdnikov, S., Gerasjuk, V., Sorokina, V., Kleshchenkov, A., Sheverdyaev, I., Kulygin, V., and Lichtanskaia, N.: Dynamics of carbon pools and fluxes in the Don River Delta, Southern (European) Russia, and the estuary under the conditions of increasing marine factors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8832, https://doi.org/10.5194/egusphere-egu24-8832, 2024.

EGU24-9443 | ECS | Posters on site | ITS5.12/CL0.1.11

Salinity influence on plant traits and photosynthesis in selected peatland macrophytes 

Amabelle Go, Hendrik Schubert, and Gerald Jurasinski

Coastal peatlands, despite their ecological importance are at risk from a range of disturbances that render this habitat vulnerable, affecting their productivity and could potentially trigger ecosystem shift. Salinity is one of the factors affecting the structural and functional aspects of macrophytes in peatland environments. This study aims to assess the impacts of different salinity levels on the growth, biomass, and photosynthetic performance of peatland plants using a mesocosm approach. Four treatments of varying salinity were implemented: Saline (C+) with salinity of 20 ppt, Freshwater (C-) with salinity of 0 ppt, 22 and 55 pulses where the plants were exposed alternately to water with salinities of 20 ppt and 0 ppt every 2 and 5 days, respectively.  Two macrophyte species, Phragmites australis and Typha latifolia, were planted in mesocosm tanks. Over a 16-week period, various parameters including leaf length, leaf area, plant height, growth, biomass, and photosynthetic responses were monitored to evaluate the extent of salinity-induced stress. Results indicate that P. australis exhibited no significant difference in growth rates and biomass across treatments. Growth monitoring showed peak observed at the 8th week post-transplanting. Leaf area and leaf production also showed no significant variations. While shoot production increased initially, peaked at the 8th week, and declined thereafter. T. latifolia on the other hand, displayed growth rate variations favoring the freshwater (C-) and less frequent water change (55) treatments. The 55 pulses exhibited the highest absolute growth rate, but growth regressed after 8th week in treatments exposed to salinity changes. Leaf production in saline (C+) and higher frequency of water changes (22) showed a steep decline from 10th week onward. Saline treatment resulted in the lowest leaf production, leaf area, and biomass. This study contributes insights on the varying responses of macrophytes to salinity stress, demonstrating acclimation kinetics, and identifying salinity limits. 

How to cite: Go, A., Schubert, H., and Jurasinski, G.: Salinity influence on plant traits and photosynthesis in selected peatland macrophytes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9443, https://doi.org/10.5194/egusphere-egu24-9443, 2024.

EGU24-10491 | ECS | Posters on site | ITS5.12/CL0.1.11

Stratification in non-tidal shallow coastal lagoons during extreme summer heatwaves  

Lloyd Reese, Ulf Gräwe, Xaver Lange, and Hans Burchard

Due to their shallow depth, coastal lagoons are often considered to be vertically well-mixed. However, past studies have shown that, depending on forcing conditions, vertical density stratification may in fact occur even in lagoons of only a few meters depth. Further, many coastal lagoons are faced with a multitude of anthropogenically caused pressures, including eutrophication as well as a likely increasing occurrence of summer heatwaves and other extreme atmospheric conditions due to climate change. While eutrophication leads to increased biological productivity and a subsequently increased oxygen demand, high water temperatures during heatwaves lead to reduced oxygen solubility, thus aggravating the risk of anoxic conditions within the water body. As vertical stratification acts to suppress vertical mixing, it may facilitate the occurrence of bottom oxygen depletion in such waters. Since coastal lagoons are of great ecological and economical interest due to their multiple ecosystem services, e.g., as spawning grounds for fish, it is of utmost importance to assess the conditions under which vertical stratification may occur. Only with such knowledge it will be possible to estimate the future development of coastal lagoon ecosystems. While many past studies have covered stratification of freshwater lakes during heatwaves, there is a significant gap of research covering coastal lagoons under the same conditions, where an additional forcing is added via the connection to the open sea. In particular, non-tidal, non-choked lagoons are currently understudied with respect to summer heatwaves. In our study, we therefore aim to assess the conditions under which stratification may occur in such lagoons during a mid-latitude summer heatwave. To this end, we have applied a non-dimensional parameter space analysis to a numerical, one-dimensional water column simulation of such a lagoon. Here, we present first results from this analysis.

How to cite: Reese, L., Gräwe, U., Lange, X., and Burchard, H.: Stratification in non-tidal shallow coastal lagoons during extreme summer heatwaves , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10491, https://doi.org/10.5194/egusphere-egu24-10491, 2024.

EGU24-11191 | ECS | Posters on site | ITS5.12/CL0.1.11

Seagrass meadows provide essential coastal protection against future marine storms 

Julia Jaca Estepa and Gabriel Jordà Sánchez

Climate change is already modifying the marine environment, and these alterations will presumably increase in the coming decades. Some of the most significant changes expected during this period include ocean warming, rise of sea level, and modifications to circulation and wind wave patterns. For instance, in the Mediterranean, ocean surface temperatures are projected to increase by 1-4 ºC by the end of the century, triggering a chain of impacts on marine ecosystems, such as species migration, significant mortality in some species, and an increase in harmful algal blooms.
Furthermore, sea levels are expected to rise, reaching values ranging from 30 cm to over 1 m by the end of the century. The consequences include the increased permanent flooding of low-lying areas, the salinization of coastal water reservoirs, and damage caused by marine storms.

In this context, despite ongoing efforts to reduce greenhouse gas emissions, it is crucial to develop realistic and effective plans for adapting to climate change. Nature-based solutions (NBS) present a particularly interesting approach to addressing climate change impacts. One NBS option suitable for reducing the impacts of climate change in coastal areas is to increase seagrass meadows through restoration interventions. The interaction of seagrasses with water flow leads to a reduction in flow energy, thereby limiting the impact of waves reaching the coast.
However, ocean warming poses a threat to seagrass meadows, as some species are particularly vulnerable to marine heatwaves. Therefore, the primary goal of the SEAFRONT project is to quantify the potential benefits of seagrass meadows in protecting the coast from future marine storms under different scenarios of global warming and seagrass evolution. SEAFRONT focuses on Spanish coastal areas, which exhibit a variety of hydrodynamical situations and seagrass coverages.
Specifically, SEAFRONT aims to 1) assess the impacts of marine storms over the last decades, evaluating the role of seagrasses; and 2) generate future scenarios of physical and economic impacts.

In this presentation, we share the results of numerical simulations focused on measuring the total water level at the shore under various scenarios. These simulations account for sea level changes, wave patterns, coastal shapes, and seagrass coverage. Additionally, we discuss the economic impacts of marine storms based on information from insurance companies.
Our initial analyses suggest that restoring seagrass meadows is a highly effective way to adapt to marine storms, countering the effects of rising sea levels. However, in areas where seagrasses already exist, losing them could lead to severe consequences, increasing the impact of marine storms.

How to cite: Jaca Estepa, J. and Jordà Sánchez, G.: Seagrass meadows provide essential coastal protection against future marine storms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11191, https://doi.org/10.5194/egusphere-egu24-11191, 2024.

EGU24-11676 | Posters on site | ITS5.12/CL0.1.11

Estuaries under pressure – surveying the extreme shallow water environments  

Aarno T. Kotilainen, Mia M. Kotilainen, Sami Jokinen, Meri Sahiluoto, Joonas J. Virtasalo, and Anu M. Kaskela

River estuaries are diverse coastal ecosystems that have significant ecological, social, cultural and economic value. Estuaries worldwide are stressed by increasingly intensive human activities, also in the Baltic Sea, a European inland sea. Human pressures include e.g., dredging, port constructions, river water acidification and pollutants. In the latest assessment of threatened habitat types in Finland, coastal estuaries were assessed as an Endangered (EN) habitat complex due to historical abiotic and biotic quality changes.

As estuaries are often very shallow environments with turbid water column, it is not easy to acquire detailed seabed information from those areas. In the ongoing SeaMoreEco project we use remote sensing methods such as shipborne acoustic surveys, floating drones, flying drones and satellites, as well as seabed sampling and underwater video observations to map and monitor shallow water areas of the Gulf of Bothnia (GoB), northern Baltic Sea. We provide information e.g., on seabed geology and underwater vegetation. Here, we focus on seabed sediment data produced in the SeaMoreEco and in some other projects.

Anthropogenic radionuclides and heavy metal pollution are typical pressures widely affecting river estuaries and other marine ecosystems. For example, the fallout from the April 1986 Chernobyl nuclear power plant accident has rendered the Baltic Sea as the most polluted marine body in the world with respect to 137Caesium (137Cs). In the present study we determined the levels of 137Cs activity and heavy metal content in the bottom sediments, and their spatial and vertical distribution in the subsurface sediments of the GoB.

Activity contents of 137Cs and heavy metal contents in seabed surface sediments of the GoB have generally declined over the last decades. In some estuaries however, 137Cs values in subsurface sediments remain at elevated levels relative to values measured from other areas of the Baltic Sea. In some areas, also the contents of heavy metals (e.g., cadmium, lead, zinc) in the subsurface sediments are quite high. This is typical for areas close to e.g., the metal industry and the areas affected by the loading from acid sulfate soils.

Data on harmful substances (e.g., radionuclides) in seabed sediments is important for coastal management and marine spatial planning while assessing risks associated with dredging and other operations. Dredging in areas where bottom sediments contain a lot of harmful substances can cause the re-mobilization and transport of these contaminants. Increasing anthropogenic pressures in coastal and marine areas will likely increase risk associated with polluted bottom sediments. Climate change might also shift many of the parameters (precipitation,  river discharge) that affect sediment distribution and pollution in the coastal and marine areas, also in the GoB.

This study is part of the Interreg Aurora funded SeaMoreEco project, the EMODnet Geology project funded by The European Climate, Environment, and Infrastructure Executive Agency (CINEA) through contract EASME/EMFF/2020/3.1.11/Lot 2/SI2.853812 - EMODnet Geology, the EMODnet Ingestion 3 project funded by the CINEA through contract CINEA/EMFAF/2021/3.4.10/02/SI2.868290, and the MAAMERI project funded by the Ministry of Environment, Finland. The study utilized research infrastructure facilities provided by FINMARI (Finnish Marine Research Infrastructure network).

How to cite: Kotilainen, A. T., Kotilainen, M. M., Jokinen, S., Sahiluoto, M., Virtasalo, J. J., and Kaskela, A. M.: Estuaries under pressure – surveying the extreme shallow water environments , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11676, https://doi.org/10.5194/egusphere-egu24-11676, 2024.

Coastal waters worldwide are increasingly affected by oxygen loss due to human-induced eutrophication and global warming. This coastal deoxygenation has dramatically altered biogeochemical processes with major consequences for marine life. Prominent examples of large anthropogenic coastal “dead zones” include the Gulf of Mexico, Baltic Sea and Chesapeake Bay but numerous small coastal systems are also strongly affected. Many efforts are currently underway to restore the water quality of these coastal waters, but these are not always effective. In this presentation, I will discuss how the interplay of biogeochemical processes and hydrodynamics may affect present-day restoration efforts in coastal systems. Using examples from a range of field and modelling studies performed by my group, I will specifically discuss legacy effects resulting from accumulation of organic-rich sediments, the potential for reoxygenation of coastal waters through increased water column mixing and/or lateral water exchange and the expected short-term and long-term effects of nutrient load reductions. Taken together, our results highlight that there is no one-size-fits-all approach to rapidly improve water quality in coastal waters suffering from eutrophication and deoxygenation.

 

How to cite: Slomp, C. P.: Eutrophication and deoxygenation of coastal waters: how to improve water quality? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12502, https://doi.org/10.5194/egusphere-egu24-12502, 2024.

EGU24-12654 | ECS | Orals | ITS5.12/CL0.1.11

Brackish water rewetting of a temperate coastal peatland: Effects on biogeochemistry, microorganisms and greenhouse gas emissions 

Cordula Gutekunst, Susanne Liebner, Anna-Kathrina Jenner, Erwin Don Racasa, Klaus-Holger Knorr, Sara E. Anthony, Daniel Lars Pönisch, Michael Ernst Böttcher, Manon Janssen, Jens Kallmeyer, Franziska Koebsch, Gregor Rehder, and Gerald Jurasinski

Around 4 % of global greenhouse gas (GHG) emissions originate from drained peatlands. Unlike rewetting drained peatlands with freshwater, brackish water rewetting of coastal peatlands might not only reduce CO2 emissions, but also keep methane (CH4) emissions low. The re-establishment of the natural brackish water regime of coastal peatlands with high sulfate levels should favor sulfate reducing bacteria as well as sulfate-driven anaerobic methane oxidizers and therefore limit CH4 production and/or lead to increased CH4 consumption. Here, we compared CO2 and CH4 fluxes, pore water geochemistry, and associated microbial communities of a coastal fen along a moisture gradient before, and a water level gradient after rewetting.

Brackish water rewetting increased the abundances of CH4 producing archaea (methanogens) as well as the abundances of sulfate reducing bacteria (SRB) in most of the study site, except at former ditch areas, where methanogenic and SRB abundances had been high before. At the same time, the aerobic methanotroph community was less present, indicating lower aerobic CH4 oxidation potentials after rewetting. Pore water CH4 and CO2 concentrations along with δ13C records suggest that both, methanogenesis and CH4 oxidation, increased after rewetting. Brackish water rewetting raised average CH4 emissions from 2 to 25 mg CH4 m-2 d-1 at locations that were previously drained, which is lower than CH4 emissions reported from most freshwater peatlands. Net CO2 emissions remained high after rewetting with values around 4 g CO2 m-2 d-1. However, since ecosystem respiration strongly decreased from on average 19 to 6 g CO2 m-2 d-1, the remaining net CO2 emissions were mostly associated with low CO2 uptake due to extensive die-back of the vegetation. Hence, brackish water rewetting can keep CH4 emissions relatively low, but, as in freshwater peatlands, hydrological management must allow for the re-establishment of site-specific vegetation to sustain net CO2 uptake.

How to cite: Gutekunst, C., Liebner, S., Jenner, A.-K., Racasa, E. D., Knorr, K.-H., Anthony, S. E., Pönisch, D. L., Böttcher, M. E., Janssen, M., Kallmeyer, J., Koebsch, F., Rehder, G., and Jurasinski, G.: Brackish water rewetting of a temperate coastal peatland: Effects on biogeochemistry, microorganisms and greenhouse gas emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12654, https://doi.org/10.5194/egusphere-egu24-12654, 2024.

EGU24-12994 | ECS | Posters on site | ITS5.12/CL0.1.11

Oxygen dynamics in the Baltic Sea under reduced nutrient input 

Lev Naumov, H.E. Markus Meier, and Thomas Neumann

The Baltic Sea is a semi-enclosed sea located in the Northern Europe. Due to the limited exchange with the Global Ocean, which leads to the long residence time (approx. 30 years), and permanent halocline, the Baltic Sea is naturally prone to hypoxic conditions, especially in the deep basins. However, the hypoxic area in the deep Baltic Sea has been rapidly increasing since the second half of the 20th century following the elevated nutrient input caused by human activity. To mitigate the eutrophication of the Baltic Sea, countries surrounding it started to reduce their nutrient loads following the Baltic Sea Action Plan. Despite the substantial nutrient input reduction, no significant decrease in the hypoxic area has yet been observed. In addition, climate change might promote deoxygenation of the Baltic Sea, further hampering nutrient load reduction efforts. The non-linear response to changes in nutrient input raises the question of when to expect the robust reduction of the hypoxic area, whether it is possible for the Baltic Sea to return to its natural state with a limited hypoxic area, and how the composition of the oxygen budget will change following the reduction of hypoxia.

To answer those questions, we conducted two sensitivity simulations utilizing a 3-dimensional coupled physical-biogeochemical model. The simulations followed the two nutrient reduction pathways – Baltic Sea Action Plan Maximum Allowable Input (BSAP) and the more radical half of the BSAP MAI (0.5 BSAP). Both simulations spanned 71 years and were compared to the reference scenario (Ref.) employing observed nutrient loads from 1948 to 2018. The lowering of the hypoxic area was observed in both scenarios. Most rapid re-oxidation was observed in the remote northern and western Gotland Basins, especially in the 0.5 BSAP scenario. The redistribution of the biggest oxygen consumption from the water column to the sediments followed it. Changes in nutrient loads explain more than 60% of the oxygen sources and sinks variability, making it the dominant driver of changes in the oxygen budget of the Baltic Sea, at least in the near future. The Baltic Sea could return to its initial state (1948) within the simulation period, but only following the radical 0.5 BSAP scenario.

How to cite: Naumov, L., Meier, H. E. M., and Neumann, T.: Oxygen dynamics in the Baltic Sea under reduced nutrient input, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12994, https://doi.org/10.5194/egusphere-egu24-12994, 2024.

Nearshore strategic placement—in addition to direct placement—has been proposed as a nature-based solution to reuse dredged sediment in support of mitigating the effects of sea level rise in the San Francisco Bay Area. The success of nearshore strategic placement relies on hydrodynamic forces moving sediment from the placement site to mudflats and marshes over time. Sediment transport and pathway models can be used to evaluate and prioritize potential placement sites, placement methods, transport rates (informing amount and frequency of sediment placement), sediment fate, and longevity. Models can also be used to predict the evolution of sites after initial placement and as sea level and sediment supply conditions evolve. This model-based information is needed to design wetland restoration and maintenance operations, inform the permitting approval process, and evaluate the costs and benefits of using strategic placement techniques to restore and maintain Bayland habitats in San Francisco Bay. This talk will focus on the estuarine process modeling as well as in-situ observation efforts that are being undertaken to assess sediment fate, sediment transport rates and sediment transport dynamics associated with nearshore strategic placement.

How to cite: Savant, G.: Modeling the San Francisco Bay Estuary to Inform Nature-Based Sediment and Baylands Management , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13084, https://doi.org/10.5194/egusphere-egu24-13084, 2024.

EGU24-15787 | Posters on site | ITS5.12/CL0.1.11

Assessing the spatial and temporal trophic properties of the Marano and Grado Lagoon, Italy with the coupled physical-biogeochemical model SHYFEM-BFM  

Isabella Scroccaro, Celia Laurent, Leslie Aveytua, Cosimo Solidoro, and Donata Canu

Coastal and transitional areas worldwide are affected by a range of human pressures and are subjected to high natural variability. In the Marano and Grado lagoon, located in the densely anthropized north-eastern coastal area of Italy, the conservation of biodiversity and the presence of important socio-economic activities require planning and management tools and measures. Coupled physical and biogeochemical models are useful tools to support trophic studies in complex systems such as the Marano and Grado lagoon by integrating field information with relevant hydrodynamic and biogeochemical processes shaping the system. The coupled SHYFEM–BFM model was applied to the Marano-Grado lagoon, adding new features to account for the contribution of macrophytes (such as seagrasses). Results were validated against available in situ observations, and trophic properties were investigated using trophic state indices that allow to reproduce spatial and temporal variability under different scenarios.

How to cite: Scroccaro, I., Laurent, C., Aveytua, L., Solidoro, C., and Canu, D.: Assessing the spatial and temporal trophic properties of the Marano and Grado Lagoon, Italy with the coupled physical-biogeochemical model SHYFEM-BFM , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15787, https://doi.org/10.5194/egusphere-egu24-15787, 2024.

EGU24-15795 | ECS | Orals | ITS5.12/CL0.1.11

Step-by-Step Strategies to Tackle Coastal Erosion: Insights from Calabaia Beach (Calabria, Italy) 

Guglielmo Federico Antonio Brunetti, Manuela Carini, Maria Antonietta Scarcella, Francisco Xavier Pilier, and Mario Maiolo

Coastal areas globally are invaluable assets and strategic resources from both environmental and social perspectives, as well as for the sustainable development of the marine economy, often referred to as “Blue Growth”. This understanding highlights the crucial need to protect coastal areas from climate change phenomena such as sea-level rise, flooding, and erosion. Previous research has shown the high vulnerability of the Mediterranean Sea's coasts to these phenomena, with ecosystems and biodiversity increasingly under threat. Despite past efforts to address these issues, many aspects still require further investigation, and solutions necessitate a holistic approach and a step-by-step strategy. Our research contributes to this context by providing valuable insights from Calabaia Beach (Calabria, Italy), where specific step-by-step strategies were implemented to mitigate erosion processes and restore the coastal and marine environment. The research site, located within the Marine Experimental Station of Capo Tirone (Belvedere Marittimo, Calabria, Italy), is of significant relevance as it has experienced various sea-defense interventions over the years, ranging from hard defenses to soft defenses, to the adoption of nature-based solutions. This study highlights that investigating the efficacy of these interventions over time can offer essential insights into the potential of each to sustainably curb erosion processes. From this standpoint, practitioners can establish a solid foundation to predict how future interventions for tackling erosion could effectively impact the entire coastal ecosystem of the area. Moreover, our research suggests that a step-by-step approach could be implemented also for aspects related to local hydrodynamics, pollutant dispersion, seawater intrusion, and marine biology. The case study of Calabaia Beach clearly illustrates that a time-dependent strategy could be successfully applied when there is a need to balance coastal environmental protection with social interests and the development of “Blue Growth”. This approach could be further explored in other case studies, keeping in mind that the specific characteristics of the area represent a determining factor.

Acknowledgements. This research was supported by ”NAUTILOS” project (GA 101000825) and by the Next Generation EU - Italian NRRP, Mission 4, Component 2, Investment 1.5, call for the creation and strengthening of ’Innovation Ecosystems’, building ’Territorial R&D Leaders’ (D. D. 2021/3277) - project Tech4You, n. ECS0000009. This work reflects only the authors’ views and opinions, neither the Ministry for University and Research nor the European Commission can be considered responsible for them.

How to cite: Brunetti, G. F. A., Carini, M., Scarcella, M. A., Xavier Pilier, F., and Maiolo, M.: Step-by-Step Strategies to Tackle Coastal Erosion: Insights from Calabaia Beach (Calabria, Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15795, https://doi.org/10.5194/egusphere-egu24-15795, 2024.

EGU24-15930 | Posters on site | ITS5.12/CL0.1.11

Pore-Size-Class Dependent Carbon Turnover in Peat Soils 

Bernd Lennartz, Rosa Cambinda, Haojie Liu, and Fereidoun Rezanezhad

Carbon loss from peatlands involves both gaseous emissions and a significant contribution from the water-bound fraction, specifically dissolved organic carbon (DOC), during mineralization and degradation processes. Our hypothesis proposes that DOC production is dependent on pore size, with elevated concentrations occurring in finer pores. To test this hypothesis, we extracted pore water at well-defined pressure heads (-60 and -600 hPa), representing macro- and mid-size pore domains, in degraded peat samples. Topsoil and subsoil samples exhibited soil organic matter contents of 34wt% and 57wt%, respectively. Remarkably, the more degraded topsoil consistently displayed significantly higher average DOC concentrations than the subsoil, with 1.5 times greater levels at -60 hPa and 2.4 times higher at -600 hPa. This trend suggests that more degraded peat soils are prone to releasing higher amounts of DOC. Furthermore, in topsoil samples, DOC concentrations were consistently higher at the -600 hPa pressure head compared to -60 hPa. To enhance our understanding, we computed hydraulic conductivities at -60 and -600 hPa using Van Genuchten parameter values, subsequently estimating the DOC load under unit gradient conditions. This calculation is particularly relevant for real-field situations, especially in partially saturated (degraded) peat soils. The hydraulic conductivity at -600 hPa was nearly a hundred times lower than at -60 hPa, leading to the conclusion that macro-pores serve as the primary pathways for DOC release in peat soils, irrespective of higher DOC concentrations in the fine pore domain.

How to cite: Lennartz, B., Cambinda, R., Liu, H., and Rezanezhad, F.: Pore-Size-Class Dependent Carbon Turnover in Peat Soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15930, https://doi.org/10.5194/egusphere-egu24-15930, 2024.

EGU24-16829 | Orals | ITS5.12/CL0.1.11

Climate change and islands’ ecosystem services: a global meta-analysis  

George Zittis, Shiri Zemah-Shamir, Mirela Tase, Savvas Zotos, Nazli Demirel, Christos Zoumides, Tamer Albayrak, Cigdem Kaptan Ayhan, Irene Christoforidi, Turgay Dindaroglu, Mauro Fois, Paraskevi Manolaki, Attila Sandor, Ina Sieber, Stamatiadou Valentini, Elli Tzirkalli, Ioannis Vogiatzakis, Ziv Zemah-Shamir, and Aristides Moustakas

Islands are hotspots of biological and cultural diversity, which, compared to mainlands, are more vulnerable to environmental degradation, climate change, uncontrolled land use changes and financial or societal crises. Particularly when combined, these factors can increasingly impact the environmental and socioeconomic services in many of such isolated ecosystems and communities. Atmospheric warming, ocean acidification or other abrupt climate changes can directly impact the biodiversity of islands and surrounding water bodies, the associated Ecosystem Services and, in turn, the well-being of islanders. Although existing techniques can adequately predict climate-induced ecological changes over the continents or in the larger islands, this is not the case for smaller islands, where refined climate information is typically not available. The primary objective of the present review is to better understand the linkages between Ecosystem Services and climate change on islands from the global to regional and local scales. This is not limited to the direct positive or negative impacts of changes in environmental and climate conditions but also includes the potential of ecosystem services to provide nature-based solutions for climate change mitigation and adaptation. Non-climatic drivers, e.g., land use changes, that may augment or alleviate the effects of climate change on islands’ Ecosystem Services are also explored.

How to cite: Zittis, G., Zemah-Shamir, S., Tase, M., Zotos, S., Demirel, N., Zoumides, C., Albayrak, T., Kaptan Ayhan, C., Christoforidi, I., Dindaroglu, T., Fois, M., Manolaki, P., Sandor, A., Sieber, I., Valentini, S., Tzirkalli, E., Vogiatzakis, I., Zemah-Shamir, Z., and Moustakas, A.: Climate change and islands’ ecosystem services: a global meta-analysis , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16829, https://doi.org/10.5194/egusphere-egu24-16829, 2024.

EGU24-18394 | ECS | Posters on site | ITS5.12/CL0.1.11

Groundwater quality in two coastal fens and the influence of storm surge flooding and rewetting with seawater 

Erwin Don Racasa, Haojie Liu, Miriam Toro, and Manon Janssen

Coastal peatlands are unique ecosystems situated at the interface of land and sea. Past human activities, specifically drainage, have turned these carbon sink coastal regions into carbon sources. To mitigate climate change, recent management strategies focus on rewetting drained coastal peatlands. In this study, we aimed at characterizing surface and groundwaters in two coastal fens and examine the impacts of seawater input events caused by a storm surge (freshwater-rewetted) and rewetting with seawater (seawater-rewetted). Prior to the events, our findings reveal variable marine influence on surface and groundwater in the past which depends on distance from the coast, peat thickness, and possibly, drainage networks. After the storm surge, increases in specific conductivity (SC), chloride, and sulfate concentrations in surface waters persisted for up to a year. Increases in surface water dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) concentrations were also observed. In peat groundwater, a sustained increase in DOC concentrations that reached 526 mg DOC L-1 was observed at a shallower depth (max: -0.59 masl) while a delayed increase was observed at a deeper depth (max: -1.41 masl). High dissolved carbon concentrations were still observed in peat groundwater until the end of the observation period, three years after the storm surge. For the seawater-rewetted fen, significant changes in surface water properties were observed, which included SC, chloride, pH, DOC, DIC. The initial DOC concentrations in peat groundwater decreased, but later, showed the same high concentrations similar to the storm surge flooded fen. No apparent impacts to deeper sandy aquifers from both sites were observed. Overall, storm surge flooding impact on surface water properties lasted for a limited time while rewetting with seawater significantly and drastically changed the surface waters as the peatland was transformed into a lagoon-like environment. Peat groundwater properties in both sites did not change significantly, however, depth-dependent variable increases in DOC concentrations could be expected. The increases in DOC concentrations in peat groundwater were accompanied by increased SC and decreased pH conditions. Lastly, the ongoing salinization of seawater-rewetted fens may lead to brackish-rewetted environments with higher concentrations of seawater salts and potentially create new biogeochemical reactive mixing zones of ground- and seawater.

How to cite: Racasa, E. D., Liu, H., Toro, M., and Janssen, M.: Groundwater quality in two coastal fens and the influence of storm surge flooding and rewetting with seawater, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18394, https://doi.org/10.5194/egusphere-egu24-18394, 2024.

EGU24-18426 | ECS | Posters virtual | ITS5.12/CL0.1.11

The influence of microtopography on soil carbon accumulation and nutrient release from a rewetted coastal peatland 

Miaorun Wang, Haojie Liu, Fereidoun Rezanezhad, Dominik Zak, and Bernd Lennartz

Coastal peatlands have been frequently blocked from the sea and artificially drained for agriculture. With an increasing awareness of ecosystem functions, several of these coastal peatlands have been rewetted through dike removal, allowing seawater flooding. In this study, we investigated a recently rewetted peatland on the Baltic Sea coast to characterize the prevailing soils/sediments with respect to organic matter accumulation and the potential release of nutrients upon seawater flooding. Eighty disturbed soil samples were collected from two depths at different elevations (–0.90 to 0.97 m compared to sea level) and analyzed for soil organic matter (SOM) content and carbon:nitrogen (C:N) ratio. Additionally, nine undisturbed soil cores were collected from three distinct elevation groups and used in leaching experiments with alternating freshwater and Baltic Sea water. The results demonstrated a moderate to strong spatial dependence of surface elevation, SOM content, and C:N ratio. SOM content and C:N ratio were strongly negatively correlated with elevation, indicating that organic matter mineralization was restricted in low-lying areas. The results also showed that the soils at low elevations release more dissolved organic carbon (DOC) and ammonium (NH4+) than soils at high elevations. For soils at low elevations, higher DOC concentrations were observed when flushing with freshwater, whereas higher NH4+ concentrations were found when flushing with brackish water. Recorded NH4+ concentrations in organic-rich peat reached 14.82 ± 9.25 mg L–1, exceeding Baltic seawater (e.g., 0.03 mg L–1) by two orders of magnitude. A potential sea level rise may increase the export of NH4+ from low-lying and rewetted peat soils to the sea, impacting adjacent marine ecosystems. Overall, in coastal peatlands, geochemical processes (e.g., C and N cycling and release) are closely linked to microtopography and related patterns of organic matter content of the soil and sediments.

(The original article has been published in Geoderma, Volume 438, 116637; DOI: 10.1016/j.geoderma.2023.116637)

How to cite: Wang, M., Liu, H., Rezanezhad, F., Zak, D., and Lennartz, B.: The influence of microtopography on soil carbon accumulation and nutrient release from a rewetted coastal peatland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18426, https://doi.org/10.5194/egusphere-egu24-18426, 2024.

EGU24-18677 | ECS | Orals | ITS5.12/CL0.1.11

Geochemistry of tropical coastal lagoon sediments from Sungai Kilim, Langkawi, Malaysia: Implications for provenance and weathering 

Nur Sakinah Abdul Razak, Yang Shouye, Hasrizal Shaari, Vasquez Ana Cristina, Guo Junjie, and Wu Xuechao

The interaction between land and sea in the coastal zone is dynamic and highly sensitive. It not only records past transgression history, coastal environmental evolution, and sea level changes, but also provides information on climate fluctuations, ocean and river changes, ecological environmental evolution, and human-induced environmental impacts. Coastal zone deposition plays a crucial role in preserving records of paleoenvironment changes and is therefore a key component larger ‘source to sink’ systems at continental margin. Therefore, it has attracted great academic interest in the field of geoscience in recent years. In this study, we measured trace elements and rare earth elements (REEs) in 20 surface sediment samples and a core (LKC 2) collected from the coastal lagoon of Sungai Kilim, Langkawi, Malaysia, to determine the possible sources and to reveal the variations in response to climate change and human activities. The distribution of trace elements (e.g., Li, Ti, Cr, Co, Ni, Cu, Zn, and Mn) was enriched in surface sediments, indicating those elements are affected by human activities. Besides, the concentrations of trace element in LKC 2, combined with AMS dating further confirmed the anthropogenic provenance in the uppermost core layers as a result of deforestation and urbanization in recent decades. However, the low Rb/Sr ratios in surface sediments and LKC 2 corresponds to higher intensity chemical weathering, resulting in higher concentrations of dissolved Sr in the sediments. The enrichment of REEs in surface sediments and LKC 2 indicates typical minerals present in the study area. Overall, the elemental flux patterns observed in this study are responses to complex interactions between intensified human activities and natural climate variability.

How to cite: Abdul Razak, N. S., Shouye, Y., Shaari, H., Ana Cristina, V., Junjie, G., and Xuechao, W.: Geochemistry of tropical coastal lagoon sediments from Sungai Kilim, Langkawi, Malaysia: Implications for provenance and weathering, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18677, https://doi.org/10.5194/egusphere-egu24-18677, 2024.

EGU24-18697 | Posters on site | ITS5.12/CL0.1.11

Nitrogen fixation in the shallow waters off a coastal wetland with outcropping peat 

Angelina Klett, Iris Liskow, and Maren Voss

Biological nitrogen (N) fixation is the microbial transformation of atmospheric N2 to ammonia, which is carried out by various groups of microorganisms and in all environments. The organisms, called diazotrophs, do not rely on bioavailable combined N such as nitrate or ammonium, which are often limiting ecosystem productivity. On the other hand, their activity provides nutrients to the otherwise N-limited ocean. In the central Baltic Sea high nitrogen fixation occurs each summer in surface waters introducing up to 792 000 t N per year, but was also identified in the deep and anoxic waters. In coastal waters the heterotrophic and autotrophic N2 fixation is not well studied and even less is known about the annual cycle and its regulation by the environment. Since coastal environments are considered to act as a filter for nutrients and organic matter, knowledge on an additional N source through N2 fixation is of great importance.

Here, we present N2 fixation rates for bulk water and sediment slurries (upper 5 cm), incubated for 24 hours in the dark and during a daily light cycle. We selected three stations near a peatland with outcropping peat layers and sandy sediments. Monthly sampling over the course of one year was done together with in-situ measurements of temperature, salinity, pH, nutrient concentrations and dissolved organic substances. Incubations were spiked with 15N2 gas and incubated in the lab. The fixation rates ranged from our detection limit up to 285 nmol N L-1 d-1 in water and 2 nmol N gdw-1 d-1 in sediments with a mean fixation rate of 11.2 nmol N L-1 d-1 and 0.1 nmol N gdw-1 d-1 for water and sediment, respectively. We could not find significant difference between stations and overall, the rates were much lower than in the surface waters of the central Baltic Sea. Though the rates in the water observed in June 2022 agree well with the rates of a cyanobacterial bloom in late summer (4.3 – 7.8 µmol N m-3 h-1). The rates for the water as for the sediment showed significant positive correlation (Spearman, sig. level 0.05) with variables affected by the seasonal change as temperature, daylength, pH and oxygen saturation. during winter and spring, the rates in the water were low to non-detectable and highest in summer. Also, in the sediment the lowest rates were found during winter and highest rates in spring. In general, the light cycle treatment showed higher rates than the dark incubation, with the exception of spring where the dark incubated sediments had higher rates than the ones in a daily light cycle. The outcropping peat layer seemed to induce some variability in N2 fixation rates, reflecting the heterogeneity of substrate which was sometimes covered with sand layers of different thickness.

Even though the rates in this study are comparably low for both water and sediment, a seasonal pattern became visible. Sediments and shallow waters clearly deserve more attention to better understand the process and the potential role as food and nitrogen source.

How to cite: Klett, A., Liskow, I., and Voss, M.: Nitrogen fixation in the shallow waters off a coastal wetland with outcropping peat, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18697, https://doi.org/10.5194/egusphere-egu24-18697, 2024.

EGU24-19197 | ECS | Orals | ITS5.12/CL0.1.11

The importance of Seasonality for Seagrass as Coastal Protection 

Veronika Mohr, Wenyan Zhang, Corinna Schrum, and Tobias Dolch

Seagrass is regarded with great expectations when it comes to nature-based coastal protection measures. Seagrass meadows dampen waves, reduce currents, and stabilize sediments in the coastal environment. However, most modeling studies estimating the magnitude of the coastal protection effect by seagrass assume a constant seagrass cover throughout the year. In temperate climates such as Northern and Central Europe the seagrass cover has considerable annual and interannual variations. The seagrass cover is highest in late summer and autumn and lowest in winter and early spring. At the same time, the physical forcing of waves and currents is at its maximum in winter, indicating a discrepancy between the seasons with the highest benefits of seagrass to coastal protection and the seasons with the most threat to the stability of the coast. In this study, we use a 3D baroclinic circulation model (SCHISM) coupled with a sediment model and a model of seagrass growth dynamics for estimating the significance of seasonality for coastal protection. A case study of a tidal basin in the northern Wadden Sea indicates that disregarding the seasonality can lead to substantial overestimations of the effectivity of seagrass for coastal protection.

How to cite: Mohr, V., Zhang, W., Schrum, C., and Dolch, T.: The importance of Seasonality for Seagrass as Coastal Protection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19197, https://doi.org/10.5194/egusphere-egu24-19197, 2024.

EGU24-19604 | Posters on site | ITS5.12/CL0.1.11

AI classification of marine birds and mammals based on aerial imagery of the German North and Baltic Seas 

Christian Sommer, Mathias Seuret, Nora Gourmelon, Vincent Christlein, and Matthias Braun

Following the current expansion of offshore constructions for the production of renewable energy as well as shipping traffic, assessments of impacts on marine ecosystems are becoming increasingly important. Thus, accurate knowledge of the spatial and temporal distribution of animal species is mandatory regarding the preservation of biodiversity and management of offshore wind farms and further economic activities. High-resolution optical imagery of airborne remote sensing sensors enables the observation of marine birds and mammals within large ocean areas. However, the identification of features at the ocean surface as well as the separation of animals and further objects, such as wave structures, ships or buoys, requires time-consuming visual inspection of the acquired image sequences by trained personnel. Here, we apply an AI-based approach to automatically detect and classify various features above the sea surface based on aerial imagery of the German North Sea and Baltic Sea. A large number of optical images at a spatial resolution of 2 cm have been acquired by the German Federal Agency for Nature Conservation (BfN) during repeated monitoring flights since 2018. These images are preprocessed and geolocated by assigning respective auxillary informations to create an extensive database on marine animal observations. The AI method which we are developing has to be responsible both for detecting birds in images, and for tracking instances of a same element present on multiple frames in order to avoid counting an individual multiple times. Some of the main challenges which will have to be dealt with are the following. First, luminosity conditions cannot be controled and might be suboptimal in a large fraction of the images, rendering animals completely white or black, or difficult to distinguish from the background. Second, smaller animals might consist only of little pixel blobs, and thus be difficult to distinguish. Third, flying birds might have shadows, which, while bird-shaped, must not be classified as birds. Fourth, in bird flocks overlapping tricks the AI into detecting one bird instead of several ones, which renders tracking significantly more challenging. We aim at tackling the third and fourth issues by incorporating cinematic estimation of the plane‘s and animal‘s movements, and estimating the direction of the sun in each frame, into the tracking system. In the future, our system will be used by the German Federal Agency for Nature Conservation (BfN) to monitor bird and mammal populations, and evaluate the effectiveness of preservation measures. 

How to cite: Sommer, C., Seuret, M., Gourmelon, N., Christlein, V., and Braun, M.: AI classification of marine birds and mammals based on aerial imagery of the German North and Baltic Seas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19604, https://doi.org/10.5194/egusphere-egu24-19604, 2024.

EGU24-5814 | PICO | ITS4.18/CL0.1.12

Climatic Zones Classification and Building Energy Efficiency in Spain. 

Blanca Arellano, Qianhui Zheng, and Josep Roca

In Spain, the adaptation of the European Directive on energy performance of buildings (2010) has been implemented through the Technical Building Code (TBC), which divides the territory into climate zones and evaluates the energy performance of buildings based on them (2013). The TBC segments Spain according to seasons, differentiating winter months (from October to May), which correspond to those where heating is necessary, and summer months (from June to September), those where air conditioning is necessary. Resulting in a characterization according to the climate severity of summer (SCS) or winter (WCS) to evaluate their energy efficiency. However, this classification methodology could be improved if taking into account the warming process of recent decades.

Between 1971-2022 in Spain, the maximum temperatures increased on average, 3.54°C, as well as the minimum temperatures, 2.73°C; as well as an exponential increase in heat waves over the last decades (Roca et al., 2023). "Summer" has increased by almost two more months, with a corresponding reduction in the "winter months”. For this reason, the research proposes a modification of the SCS and WCS, considering that “summer” runs from May to October and “winter” from November to April. Therefore, the research aims to study the limitations of the BTC climate zones classification, and propose a new climatic classification that allows a more accurate energy performance certification of buildings.

The study uses the E-OBS dataset, with a spatial resolution of 0.1°x 0.1°. Its continuity over time helps to track and analyze long-term climate change trends. For this purpose, the paper obtained daily data of average (tg), maximum (tx) and minimum (tn) temperature, and solar radiation (qq) from 1991 to 2020. At the same time, the study incorporates a series of climatic indices into the analysis to differentiate more precisely the different climates. For warm season, we introduce thermal indices such as CD25 and CN20 through 'Summer Days' (tx>25) and 'Tropical Nights' (tn>20). These outdoor temperatures, tx>25 and tn>20, indicate the thresholds above which the indoor environment of homes should be cooled. On the other hand, for the cold season, were calculated the cold indices HD15 and HD0 through 'Winter Days' (tg<15) and the 'Frost Days' (tn<0).

Through Principal Component Analysis (PCA), the determining factors of the climatic severities of "summer" and "winter" are extracted. These factors allow, through K-means classification, the delimitation of the different climatic zones that, require cooling (SCS) or heating (WCS). To obtain higher resolution climate data, the climate classification obtained by E-OBS has been downscaled to 1000 meters using multiple regression analysis (OLS), considering longitude, latitude, altitude and sea distance as independent variables, and SCS and WCS as dependent variables.

Finally, the research proposes an improved climatic zones classification, and, therefore, establish a more accurate energy efficiency valuation of buildings. This improved methodology not only reflects regional climate variations more accurately, but can also serve as a key tool for urban planners and building designers, allowing them to implement more effective strategies based on local climate.

How to cite: Arellano, B., Zheng, Q., and Roca, J.: Climatic Zones Classification and Building Energy Efficiency in Spain., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5814, https://doi.org/10.5194/egusphere-egu24-5814, 2024.

EGU24-6000 | ECS | PICO | ITS4.18/CL0.1.12

Enhancing the Design of Climate Service Training Programs: Identifying Targeted Audiences for the User Learning Services for the Copernicus Program 

Maria del Pozo, Bregje van der Bolt, Judith Gulikers, Perry den Brok, and Fulco Ludwig

This research tackles the multifaceted challenges inherent in the design of climate service training programs, with a specific focus on the context of C3S User Learning Services. The heterogeneity of actors involved, including producers, providers, intermediaries, and users, often leads to misalignments attributable to overlooked nuances in learning needs. The primary objective is to establish consensus among trainers involved in the C3S User Learning Services regarding the identification of targeted audiences, their associated knowledge and skills, and the interests pivotal for the success of capacity-building initiatives. Utilizing the Delphi method, trainers participate in iterative rounds of questionnaires, wherein statistical measures and qualitative assessments guide the refinement process. The study introduces specific levels of agreement, distinguishing between poor, average, and strong agreement based on percentage evaluations. The structured yet flexible approach incorporates a pre-testing stage involving external experts to ensure survey clarity. With the potential inclusion of a fourth round in cases of low consensus, the research aspires to comprehensively address the diverse learning needs within the climate service domain, ultimately enhancing the efficacy of training programs, exemplified by C3S User Learning Services

How to cite: del Pozo, M., van der Bolt, B., Gulikers, J., den Brok, P., and Ludwig, F.: Enhancing the Design of Climate Service Training Programs: Identifying Targeted Audiences for the User Learning Services for the Copernicus Program, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6000, https://doi.org/10.5194/egusphere-egu24-6000, 2024.

EGU24-7472 | ECS | PICO | ITS4.18/CL0.1.12

Climate and Weather Information Services for better governance and risk reduction of wildfires in North Western Europe 

Hugo Lambrechts, Cathelijne Stoof, Carolien Kroeze, Fulco Ludwig, and Spyros Papa

Wildfires are an emerging risk in NW Europe, primarily due to increasingly conducive weather conditions resulting from climate change. This work examines the vital role of climate adaptation services to contribute to knowledge sharing and network building among professional stakeholders on a national level and within the region. Based on online survey responses from land managers/owners, forest managers/owners, fire services, and governments, we explore the intricacies of wildfire risk perception and the necessity of tailored climate and weather information for effective wildfire governance.

Our research investigates how climate information services can bolster wildfire risk reduction, emphasizing the development of these services as a knowledge-sharing and network-building approach. We explore how tailored, locally relevant solutions and a thorough process of knowledge exchange and learning can build networks, ultimately delivering actionable knowledge that fosters an awareness culture among stakeholders.

The work delves into the current perception and awareness of wildfire risks among professional stakeholders. We examined their risk awareness, preparedness, and responsibility perceptions, questioning whether experience with wildfires correlates with higher awareness or if stakeholders outside civil protection have lower preparedness perceptions. Additionally, we investigated the specific information stakeholders utilize for wildfire risk reduction, discerning whether weather, climate, or risk reduction information is more beneficial. This exploration includes an analysis of how this information correlates with preparedness, awareness, and responsibility perceptions and whether discrepancies exist between the use and needs of stakeholders.

Preliminary result indicate that the development of a wildfire weather annd climate infomration service may contribute to wildfire governance and risk reduction in North Western Europe. Currently there is high awareness among most wildfire professionals, but that stakeholders do not feel prepared for future wildfire conditions. More than half of the respondents didn't know about the Copernicus EFFIS wildfire services, indicating that marketing and usibility of these products need to be increased. Stakeholders prioritised short-term weather forecasts and risk reduction information above other information.

In conclusion, we argue for the strategic use of climate information services as a means of enhancing the governance of wildfires in NW Europe. By identifying the climate and weather information needs of professionals and examining their perceptions and awareness of wildfire risks, we aim to contribute to the development of more effective, informed strategies for wildfire prevention and management in the face of changing climatic conditions.

How to cite: Lambrechts, H., Stoof, C., Kroeze, C., Ludwig, F., and Papa, S.: Climate and Weather Information Services for better governance and risk reduction of wildfires in North Western Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7472, https://doi.org/10.5194/egusphere-egu24-7472, 2024.

EGU24-12624 | ECS | PICO | ITS4.18/CL0.1.12

Data2Resilience: Data-driven Urban Climate Adaption – A Biometeorological Sensor Network for Dortmund, Germany 

Charlotte Hüser, Luise Weickhmann, Panagiotis Sismanidis, Jonas Kittner, and Benjamin Bechtel

Extreme heat endangers human health and well-being and impairs the use of public spaces. Dortmund’s Integrated Climate Adaption Master Plan prioritizes actions and measures to improve heat resilience. This project supports the city of Dortmund (Germany) in attaining this goal, by deploying a state-of-the-art biometeorological sensor network and developing a nowcasting service for monitoring thermal comfort across the city. The project aims to pioneer the integration of thermal comfort data in smart-city ecosystems and provide actionable insights for the development of Dortmund’s Heat Action Plan. Modeled, remotely sensed, and in-situ data will be used to provide near-real-time information regarding the outdoor thermal conditions. City-officials of Dortmund are involved in the design of the dashboard, and the weather station network, ensuring they meet their needs. The collected data will be used in a series of on-ground actions, supporting the evaluation of existing climate adaption measures, and the design of new ones. These actions include the mapping of areas with high potential for planting trees , the investigation of changes in human behavior during hot days, and the assessment of backyard greening strategies. To engage with the local stakeholders, promote the role of citizen scientists, and disseminate the project, a series of workshops and on-site events are planned, such as climate comfort labs, mobile measurement campaigns, or climate walks with citizens. The overall goal of the project is for the city of Dortmund to adopt and integrate the developed network and nowcasting service into its smart-city ecosystem.

How to cite: Hüser, C., Weickhmann, L., Sismanidis, P., Kittner, J., and Bechtel, B.: Data2Resilience: Data-driven Urban Climate Adaption – A Biometeorological Sensor Network for Dortmund, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12624, https://doi.org/10.5194/egusphere-egu24-12624, 2024.

EGU24-17230 | PICO | ITS4.18/CL0.1.12

Snow load climatology for design working lives of the greenhouse structures in Croatia 

Ksenija Cindric Kalin, Ivan Lukacevic, irena Nimac, and Melita Percec Tadic

The climatic loads should be considered in the structural design and construction of the greenhouses to ensure their overall stability and durability. The snow load (SL), defined as the weight of snow on a surface area per square meter, is particularly important because it can cause structure collapse and consequently significant economic damages. Characteristic snow load for different constructions is usually 50 years, however, greenhouse structures are usually designed for shorter periods. The classification and design of greenhouses are based on the European standard EN 13031–1 which also provides the procedure for snow load adjustments to appropriate return values. In this study, characteristic snow loads are analysed for Croatia. First, the general climatology of maximum snow load is prepared according to snow depth data from 117 stations across the country covering the period from 1968 to 2020. The results revealed four main climate snow regions in Croatia: mainland, mountainous, coastal hinterland, and Adriatic. The trend analysis showed a decreasing trend in maximum snow load data for the highest elevation stations, while a slight increase was detected for central continental and middle Adriatic areas, however, the trend is statistically significant only at two stations in the highlands. For calculating the characteristic snow load, the value associated with a 50-year return period, the Gumbel distribution was used. Non-stationarity of snow load data was tested by the likelihood ratio method which revealed no significant changes in the Gumbel distribution parameters. This led to the conclusion that a stationary model is sufficient to describe data at most stations. Besides the characteristic SL, the return values of maximum SL associated with the return periods of 5, 10, 15 and 50 years were estimated. Moving to the engineering perspective, the adjustment factors for the design of greenhouse structures given in the standard are also discussed.

How to cite: Cindric Kalin, K., Lukacevic, I., Nimac, I., and Percec Tadic, M.: Snow load climatology for design working lives of the greenhouse structures in Croatia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17230, https://doi.org/10.5194/egusphere-egu24-17230, 2024.

EGU24-17708 | PICO | ITS4.18/CL0.1.12

Modelling and forecasting of water resources availability in mountainous Mediterranean springs 

Raquel Gómez-Beas, Eva Contreras, María José Polo, and Cristina Aguilar

The amount of water available for the production of natural mineral water is affected by the variability of the flow regime in the springs from which the water is extracted. This variability occurs at different time scales (seasonal and inter-annual), being more pronounced in mountainous Mediterranean areas. Since water quality remains constant in the aquifers throughout the hydrological year, the main uncertainty in the plant's production lies in the springs flow regime. In snow dominated areas it is necessary to analyse both the influence of snow dynamics on the springs flow regime, and to establish the response time between the rainfall events and the increase in the subsurface flow regime.

A forecasting model has been developed for several springs within the Guadalfeo river basin (southern Spain), where a bottling plant is operated by an international company. The model combines two approaches: a conceptual model (MCAL); and a seasonal forecast model (MPEL).

MCAL is based on linear adjustments between measured monthly mean flow data at the different locations of the springs, and measured series of rainfall and snowfall from two meteorological stations in the area, as well as adjustments with the mean monthly flow in the antecedent months. The best results were obtained between mean monthly flow and the mean monthly flow of antecedent months, with low relative errors (0,2%-10%) in all the locations for twelve months ahead.

MPEL allows to forecast groundwater supplies six months ahead in the different locations, from two products generated by the European Centre for Medium-Range Weather Forecasts (ECMWF): Multi-model seasonal reforecasts of river discharge for Europe and Multi-model seasonal forecasts of river discharge for Europe from January 2021 to present. The hydrological model WiMMed (Watershed Integrated Model in Mediterranean Areas) has been implemented and calibrated, to generate historical simulations in periods when there are no flow measurements at the springs. Using the ECMWF products and performing a bias-adjustment, the forecasts of the groundwater supplies are obtained for several possible future scenarios.

The results obtained showed the lowest mean relative error values with the MCAL forecasts from May to October (0.8%-8%), whereas the mean monthly flow from November to January was better predicted with the MPEL forecasts (1.3%-12%). The relative errors were similar with both models between February and April (3%-20%).

How to cite: Gómez-Beas, R., Contreras, E., Polo, M. J., and Aguilar, C.: Modelling and forecasting of water resources availability in mountainous Mediterranean springs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17708, https://doi.org/10.5194/egusphere-egu24-17708, 2024.

Successful adaptation to climate change worldwide will require many local climate change risk assessments. To this end, societies need access to usable climate change information to better prepare and adapt to future risks as well as opportunities. Co-produced, user-driven climate services are a recognized means of improving the effective generation and utilization of climate information to inform decision-making and support adaptation to climate change. However, there is a structural lack of appropriate, tailored climate services and tools, particularly in developing countries. In addition, there has been limited evaluation of the process of co-developing climate service products.

This study describes and evaluates the steps and methods used to co-develop a global hydrological climate service (in the frame of the CO-MICC project), specifically, a knowledge portal on global freshwater-related hazards of climate change, in a transdisciplinary, participative process jointly with providers, local to regional users, and water experts. This comprised the co-production of (i) the relevant hydrological indicators (to be both user-relevant and scientifically sound concerning the global multi-model information basis), (ii) the integration of uncertainty in the provided visual representations of these indicators, and (iii) the necessary supporting information that guides and enables utilization of the provided hazard information. Participants from seven workshops with stakeholders from focus regions in Europe and Northern Africa included local researchers, experts from meteorological services and decision-makers from regional and national hydrological agencies. Together, we co-produced relevant model output variables and appropriate end-user products encompassing static and dynamically generated information in a web portal. The global-scale information products include interactive maps, diagrams, time series graphs, and suitably co-developed statistics, with appropriate visualization of uncertainty.

In addition, the integration of local needs into new co-developed indicators was necessary where standard indicators are not scientifically suitable with respect to the information basis. Specifically based on understanding the underlying need of the stakeholder and the capabilities of the global hydrological model output, an alternative indicator “consecutive dry years” was co-developed to integrate freshwater deficit information for water managers. Lessons learned will be discussed with a particular focus on the challenges of the participatory process in the context of the climate service co-development.

The CO-MICC knowledge portal (www.co-micc.eu) enables access to this information to a broad range of stakeholders from around the world (policy makers, NGOs, the private sector, the research community, the public in general) for their region of interest, enabling them to account for climate change in their risk portfolios. In addition, it provides information on the optimal design and methods of co-development processes.

How to cite: Kneier, F., Woltersdorf, L., and Döll, P.: Co-developing a global hydrological service to support climate change risk assessment and adaptation: providing stakeholder-elicited hazard information processed from uncertain multi-model ensemble output, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19228, https://doi.org/10.5194/egusphere-egu24-19228, 2024.

The escalating challenge of climate change, notably the changes in rainfall patterns, poses a significant threat to agricultural practices in Brazil, particularly in regions like Novo Progresso, Para, notorious for extensive deforestation and the annual "Day of Fire". We introduce an innovative mobile Augmented Reality (AR) application designed to aid farmers and local communities in adapting to these shifting rainfall patterns.

 

Our AR climate service application, developed for smartphones running the iOS and Android platforms using Unity 3D and ARKit/ARCore libraries, offers an interactive visualization of the study area. Users can view a detailed map, including administrative boundaries, protected zones, and geographical features, to explore various land uses and simulate potential changes in rainfall and crop yield. By selecting a specific plot of land within the app, users gain the capability to tailor the land's usage parameters, including the type of crops cultivated (if any) and the agricultural management strategies employed. Combining their input of local knowledge with climatic and agricultural models, the tool is able to provide them with projections of the rainfall change for the selected plot as well as the anticipated effect on crop yields. Stakeholders can experiment with different crops and management strategies and observe simulated outcomes on crop yields under different climate scenarios. Additionally, the tool supports multi-user simulations to enable effective community planning. This interactive approach is aimed at improving local decision-making regarding land use, highlighting the potential consequences of various agricultural strategies.

 

The content and features of the AR tool are grounded in interviews conducted in Para, Brazil, with a focus on incorporating local insights regarding crops, soil types, and existing management strategies. The initial phase of this project included pre-interviews which revealed a general lack of urgency among farmers regarding climate change. Our application aims to visually demonstrate the significance of climate change, linking the farmers’ perceived changes in rainfall with larger environmental trends.

 

The first iteration of the application was presented to a diverse group of stakeholders in the town of Santa Julia, including farmers, local government officials, and agricultural experts. Their engagement with the tool was followed by semi-structured interviews to gather feedback on usability and effectiveness. The response was highly encouraging, with stakeholders unanimously supporting further development and recognizing the application's potential in visualizing and combating the impacts of climate change.

 

Our presentation will discuss the iterative development process of the AR application, insights from stakeholder pre-surveys and testing sessions, and plans for further development. Emphasis will be placed on the tool's role in facilitating community-scale decision-making in a region marked by complex power dynamics and environmental challenges. Through this climate service tool, we aim to bridge the gap between scientific research and practical, community-led climate adaptation strategies.

How to cite: Metelitsa, V. and Máñez Costa, M.: Visualizing change, cultivating resilience: An augmented reality driven approach to climate adaptation planning in Brazilian agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19822, https://doi.org/10.5194/egusphere-egu24-19822, 2024.

EGU24-19874 | PICO | ITS4.18/CL0.1.12

From weather forcing to economic losses: an integrated climate service for long term projections on water availability. 

Elisa Delpiazzo, Guido Rianna, Roberta Padulano, Alfredo Reder, and Francesco Bosello

Long term projections suggest the Mediterranean area as a hotspot for increasing drought and extreme heat events with remarkable cascading effects on several economic sectors, such as agriculture, energy production, urban uses and on ecosystem services. The adoption of climate services designed to aid near real time operational choices, including seasonal forecasts, could help in better planning the use of a scarce resource, as water, both at the local (e.g., farm) and the basin level.

These short-term tools may have positive feedback also in a longer run. The PRIMA Project ACQUAOUNT (https://www.acquaount.eu/) aims to produce climate services to support robust decision making for water resource allocation at an operational time scale, and an off-line tool to evaluate how the adoption of such tools together with innovative management policies will affect water availability in a longer perspective. It will integrate the hydrological, climatological, and economic dimensions to provide information on long term sustainability of water availability to decision makers and water users in four pilot sites, namely the Tirso basin (Sardinia), Zarqa river basin (Jordan), Jeffara basin (Tunisia), and Upper Litani River basin (Lebanon). They are characterized by remarkable differences in terms of water availability, water sources, users, and management options; thus, the off-line tool will combine users’ needs and a simplified framework to be applied both in information rich and scarce contexts.

 

The tool is forced by weather observations available in-situ (where available) and complemented/replaced by authoritative data sources freely available (e.g., Copernicus Regional Reanalysis, CERRA); over the future time horizons up to 2100, an ensemble of global climate projections is adopted, which included in 6th Coupled Model Intercomparison Project (CMIP6) informing the most update cycle of IPCC Assessment Reports. The main weather outputs regulating soil water budget are statistically downscaled by exploiting a non-parametric quantile mapping approach calibrated by using CERRA reanalysis under two concentration scenarios (Shared Socio-Economic Pathway, SSP): SSP2_4.5 and SSP5_8.5, a “mid-way” and “pessimistic” scenario, respectively.

Finally, the physical effects, (i.e., water anomalies), are translated into economic terms using a simplified avoided losses approach, evaluating changes in co-designed indicators for water uses according to different scenarios. Future water availability is compared with a management rule for water provisioning, such that there will be a connection between physical water availability and restrictions that affect the amount of water available for different uses in the pilot site. Finally, water restrictions impact the economic, social, and environmental performance of selected sectors. Primarily, the socio-economic part will assess changes in economic, social, and environmental indicators to evaluate and compare costs in each scenario.

 

The final aim of the integrated service is to compare alternative future pathways of water availability. These pathways are co-developed with local stakeholders and include a status quo scenario, where current management rules for water distribution are supposed, an ACQUAOUNT integrated scenario, where the water resource is supposed to be deployed using the AQUAOUNT short term tools, and site-specific scenarios e.g. inclusion of new management rules or new water sources.

How to cite: Delpiazzo, E., Rianna, G., Padulano, R., Reder, A., and Bosello, F.: From weather forcing to economic losses: an integrated climate service for long term projections on water availability., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19874, https://doi.org/10.5194/egusphere-egu24-19874, 2024.

EGU24-22171 | ECS | PICO | ITS4.18/CL0.1.12

Hydro-climate information services for smallholder farmers: DROP app design, implementation, and evaluation 

Lisanne Nauta, Samuel Sutanto, Iwan Supit, Gordana Kranjac-Berisavljevic, Richard Dogbey, Baba Jamaldeen, and Spyridon Paparrizos

Rainfed agriculture constitutes the backbone of the economy in many regions of the Global South. Historically, smallholder farmers used their local knowledge to forecast the weather. However, with the increase in climatic variability, they can no longer solely rely on their experience to accurately forecast the weather. DROP App is a hydro-climate information service developed through a co-production approach to address the weather and climate information needs of farmers. The app gathers weather forecast from both local farmers and scientific sources, and presents this information to users to enable them to make informed decisions regarding agriculture. To test its proof-of-concept, the DROP app was implemented in five rice communities in northern Ghana. The app was introduced to farmers, who received training on it use, as well as built their capacity on weather and climate-related phenomena and the use of Information and Communication Technologies (ICT). Following the end of the cropping season, farmers evaluated the app and the results revealed that co-production of information played a crucial role to its adoption in relation to other similar platforms. Farmers consider the app as a relatively accurate and reliable source of information for planning agricultural activities. Using forecasts obtained from the app, farmers adjusted their farming activities, such as time of sowing, planting and weeding dates, fertilizer and herbicide application, and harvesting. They additionally demonstrated a significant level of knowledge about weather phenomena as a result to their engagement and capacity building. Although some limitations exist, the DROP app has potential to deliver actionable knowledge for climate-smart farm decision-making and thus, facilitate effective agriculture management.

How to cite: Nauta, L., Sutanto, S., Supit, I., Kranjac-Berisavljevic, G., Dogbey, R., Jamaldeen, B., and Paparrizos, S.: Hydro-climate information services for smallholder farmers: DROP app design, implementation, and evaluation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22171, https://doi.org/10.5194/egusphere-egu24-22171, 2024.

Attitudes on climate change and the protection of the environment have been found to relate in different ways to the current economic and social situation of the respondents. This presentation will describe people's attitudes by analyzing surveys on the topic of climate change and the protection of the environment, including the recent International Social Survey Programme (ISSP) and the Swiss Environmental Panel Study. A closer look will be taken at the economic opinions and willingness to pay higher prices or taxes and their relationship to climate change attitudes. In addition, respondent's trust in people and different institutions will be analyzed. A structural equation analysis is performed to highlight the relations between those concepts. The results will show that support for a better economy and private enterprises are related to lower environmental and climate change concerns, support for paying higher prices or taxes is related to more environmental concerns and higher trust in people and institutions is related to deeper environmental concerns. After that, several demographic characteristics will be used to show if the results are stable when controlling for these. Demographic variables used are age, gender, education level, employment status, income, and political left-right placement. It can be shown that the factors of economic opinions, willingness to pay, and trust in people and institutions all relate to the environmental and climate change attitudes. 

How to cite: Zenk-Möltgen, W.: Attitudes on climate change and their relations to opinions about the economy, willingness to pay, and social trust, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3191, https://doi.org/10.5194/egusphere-egu24-3191, 2024.

Payment for ecosystem services (PES) is a compensation concept used to incentivize landowners to improve land management practices in order to maintain and provide ecosystem services. Examples of such services include river basin protection, forest conservation, flood control, or carbon sequestration. Since the early 1990s, hundreds of PES schemes have been implemented worldwide, with varying degrees of success and has only become a new trend in Asia for the last decade. While analyzing PES cases can identify the factors that contribute to specific outcomes, given the high cost of implementing such schemes and the range of stakeholders involved, our study aims to compare PES cases in Europe where historically the human-nature relationship is more balanced and progressively protected with cases in Asia under rapid industrialization and urbanization. Methodologically, we employ a systematic literature review approach to include a total of 134 articles in Scopus database between 2009 and 2023 for systematic scrutiny. The study analyzes different aspects of the literature growth over the past decade, including project types, beneficiaries, who pays for activities (in USD), spatial scale and current size, and implementation barriers. Our analysis provides insights into the factors that contribute to the success of PES schemes for the goal of improving future research agenda and generating policy recommendations for Asian PES in the near future. In particular, we emphasize the importance of considering the environmental, socio-economic, political, and dynamic contexts of PES policies when designing and implementing such schemes.

How to cite: Jiang, T. and Chien, H.: Comparing Payments for Ecosystem Services in Europe and Asia: A Systematic Literature Review Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3312, https://doi.org/10.5194/egusphere-egu24-3312, 2024.

EGU24-3581 | ECS | Posters on site | ITS3.11/CL0.1.13 | Highlight

A Systems based approach to understanding the role of co-benefits in encouraging urban air quality interventions  

Nicole Cowell, Aoife Kirk, Gabriel Okello, Natasha O'Sullivan, Audrey de Nazelle, and Roderick Weller

There is untapped potential in urban planning behaviour change policies that can simultaneously improve air quality, support net-zero targets, and benefit communities and public and planetary health more broadly. There is evidence  siloed thinking restricts the policy making process in optimising air quality interventions for co-beneficial outcomes. Systems-based approaches create holistic insights and solutions which can address  complex cross-cutting issues by bringing together context-specific evidence, an array of expertise and perspectives whilst merging social and environmental sciences to engage in action. 

Horizon scanning academic and non-academic literature can  generate insight into the current state of play of air quality interventions, their related outcomes and co-benefits including pathways to healthier cities. It also allows  insight into the gaps between science and policy for an evaluation of how to  generate science-to-policy discussions.  Structured decision-making is a systems approach in which stakeholders are engaged throughout a decision-making process to identify and co-create shared objectives and values around a complex issue, such as urban air quality. 

This work brings together systems-based approaches to assess the state of play and optimal next steps for addressing urban air quality, investigating the role that co-benefits could play in inciting ambitious change for sustainable cities. The poster will present initial findings from horizon scanning air quality interventions, co-benefits and pathways to healthy cities, which will inform the next steps of generating a structured decision-making tool for assessing the opportunities and challenges of co-created and co-beneficial actions for air quality change.

This work is carried out in collaboration with the World Economic Forum Global Future Council on the Future of Clean Air, where academics and stakeholders are working together to address air pollution globally. 

 

How to cite: Cowell, N., Kirk, A., Okello, G., O'Sullivan, N., de Nazelle, A., and Weller, R.: A Systems based approach to understanding the role of co-benefits in encouraging urban air quality interventions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3581, https://doi.org/10.5194/egusphere-egu24-3581, 2024.

The role of cultural ecosystem services (CES) is vital to consider when developing ecological sustainable
development policies that can improve the well-being of humans. Research on CES has increased in recent years;
however, few studies have explored the complex mechanisms driving perceptions of CES and the factors influ
encing those perceptions. In areas with unique landforms and fragile ecological environments, this type of
research is difficult and rare. To address this research gap, this focuses on a typical karst area Guilin Xingping in
China, evaluating residents’ perceptions of local CES, and applying qualitative comparative analysis (QCA) to
explore the driving mechanism behind those perceptions. We found that the satisfaction of material needs is a
prerequisite and basis for further improving residents’ spiritual perceptions and pursuits. Residents’ socio
economic level, understanding of resource importance, and economic value determine whether residents can
fully perceive the value of CES. Optimizing the ability of managers, improving relevant systems, and improving
the experience with and understanding of ecosystems have a more than 50% probability of improving percep
tions related to CES. The research shows that the combination of multiple antecedents can achieve a high level of
perceptions related to CES. Managers can refer to the best path for policy regulation based on the actual situ
ation. Finally, this study provides a new policy scheme for promoting ecological sustainable development and
improving residents’ well-being, and can provide insights to inform the sustainable development of other karst
areas.

How to cite: Wang, Q.: Effectively enhancing perceptions of cultural ecosystem services: A case study of a karst cultural ecosystem , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3787, https://doi.org/10.5194/egusphere-egu24-3787, 2024.

EGU24-6058 | ECS | Posters on site | ITS3.11/CL0.1.13

Impacts of receiving international industrial transfer on China’s air quality and health exceed those of export trade 

Lu Liu, Yu Zhao, Hongyan Zhao, Yifei Wang, and Chris P. Nielsen

Benefiting from international economic cooperation on income, technology diffusion, and employment, China also suffers its environmental and health impacts, from both international trade (IT), as is now widely understood, and international industrial transfer (IIT), which has been largely unrecognized. Here, we develop a comprehensive framework to estimate the impacts of exporting IT and receiving IIT. We find that China’s emissions of CO2 and almost all air pollutants associated with IIT and IT together grew after 1997 but then declined after 2010, with the peak shares of national total emissions ranging 18–31% for different species. These sources further accounted for 3.8% of nationwide PM2.5 concentrations and 94,610 (76,000–112,040) premature deaths in 2012, and the values declined to 2.6% and 67,370 (52,390–81,810), respectively, for 2017. Separated, the contribution of IIT to those impacts was more than twice that of IT. Scenario analyses suggest that improving emission controls in its less-developed regions would effectively reduce the impact of economic globalization, but such a benefit could be largely offset by strengthened international economic cooperation. The outcomes provide a scientific basis for adjusting China’s strategic roles in the international distribution of industrial production and its formulation of relevant environmental policies from a comprehensive perspective.

How to cite: Liu, L., Zhao, Y., Zhao, H., Wang, Y., and Nielsen, C. P.: Impacts of receiving international industrial transfer on China’s air quality and health exceed those of export trade, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6058, https://doi.org/10.5194/egusphere-egu24-6058, 2024.

Science and society recognise the climate crisis as a serious problem; humankind is, nevertheless, still pursuing a path with high greenhouse gas, esp. carbon dioxide, CO2 emissions to the atmosphere. Barriers to effective reductions exist at political, institutional and individual levels. Incentives, trading and enforcement mechanisms are weak or not in place, and large-scale lifestyle changes towards sustainable development are out of sight. In such a wicked situation, the characteristics of carbon capture and storage, CCS seem attractive, negative emission paths even seem indispensable to reach the 1.5°C goal. In their “Special report on global warming of 1.5˚C”, the Intergovernmental Panel on Climate Change, IPCC found that three out of the four pathways to reaching net-zero by 2050 involve the use of CCS (IPCC 2018). It promises a – relatively – quick and technical, narrowly located but high-potential solution with no need for extensive efficiency improvement in dispersed facilities, equipment, appliances or “software” such as institutions and behaviour. The involved dimensions are manifold – there is no “one” method for analysis. Instead, cross-disciplinary investigations allow drawing lessons from various controversial long-term environmental issues – vital before fully embarking on this route. IPCC themselves admitted in their recent mitigation report in climate change that the “[i]mplementation of CCS currently faces technological, economic, institutional, ecological-environmental and socio-cultural barriers” (IPCC 2022, 28).

In order to become an efficient, effective and sustainable jigsaw piece of a low-carbon system transition, CCS has to prove its suitability. CCS embodies the tension between the advantage of a short-term “quick fix” and the disadvantages posed by the risk of long-term leakage and, from a technology policy perspective, the danger of perpetuating carbon lock-in. The present approach to scrutinise this question, laid out in Flüeler 2023, is a combination of disciplines and perspectives from systems theory, risk assessment, technology assessment and management. Six criteria address issues proven to be crucial in technology policy debates: 1. Need for deployment and benefits compared to competing technological options, 2. Total-system analysis and safety concept, 3. Internationally harmonised regulation and control, 4. Economic aspects, 5. Implementation along technology readiness levels, and 6. Societal issues. It conceptually and analytically serves to tackle the question raised 16 years ago whether CCS indeed is a “Trojan horse or a horn of plenty” (de Coninck 2008).

____________________

IPCC, 2018. Summary for policymakers [Masson-Delmotte, V. et al. (eds.)]. In: Global warming of 1.5°C. An IPCC special report. Cambridge Univ. Press, Cambridge, UK/New York, NY, USA. 24 pp. https://doi.org/10.1017/9781009157940.001.

IPCC 2022. Summary for policymakers [Shukla, P.R. et al. (eds.)]. In: Climate change 2022. Mitigation of climate change. Contribution of Working Group III to the Sixth Assessment Report. Cambridge Univ. Press, Cambridge, UK/New York, NY, USA. 48 pp. https://doi.org/10.1017/9781009157926.001.

Flüeler, T. 2023. Governance of radioactive waste, special waste and carbon storage. Literacy in dealing with long-term controversial sociotechnical issues. Springer Nature Switzerland, Cham. 145 pp. Chapter 2: https://doi.org/10.1007/978-3-031-03902-7_2.

de Coninck, H. 2008. Trojan horse or horn of plenty? Reflections on allowing CCS in the CDM. Energy Policy. 36/3. 929-936 https://doi.org/10.1016/j.enpol.2007.11.013.

How to cite: Flüeler, T.: “Trojan horse or horn of plenty”? Integrative technology assessment to analyse impacts, benefits and trade-offs of Carbon Capture and Storage, CCS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6674, https://doi.org/10.5194/egusphere-egu24-6674, 2024.

EGU24-6733 | ECS | Orals | ITS3.11/CL0.1.13

Interdisciplinary Insights into Urban Climate Governance: Navigating Complexities Through Collaborative Strategies 

Barbara Dias Carneiro, Ana María Isidoro Losada, Miranda Schreurs, and Kaayin Kee

The research presented in this paper underscores the profound importance of interdisciplinary collaboration, particularly between the realms of social sciences and natural sciences, in addressing the complex challenges of urban climate governance. The study, focused on the experiences of Paris, Munich, and Zurich, highlights the intricate multi-level governance structures inherent in these cities and the interactions between diverse stakeholders involved in shaping and implementing climate strategies. By employing a combination of interviews, document analysis, and event visits, the research not only illuminates the increasing complexity of interactions between different stakeholders but also accentuates the necessity for collaboration between social scientists and natural scientists. These collaborations extend beyond traditional relationships with higher levels of government, encompassing intra-city collaborations and engagements with science, businesses, and civil society.

In the context of the broader theme of environmental issues, the paper contributes to the discourse by emphasizing that effective solutions require a comprehensive and holistic understanding. It underscores that the integration of social science expertise with environmental research, and vice versa, is essential for developing innovative and sustainable solutions. The challenges faced by the cities in achieving ambitious climate goals stress the urgency of bridging the gap between disciplines.

In conclusion, this research contributes to the broader discourse on interdisciplinary collaboration by highlighting the evolving nature of urban climate governance and the importance of effective interaction among various stakeholders. It reaffirms the need for a comprehensive understanding of environmental problems and their solutions, emphasizing the significance of multi-level governance in contributing positively to the attainment of climate goals. The insights presented here align with the call for contributions that explore the synergy between social science and environmental research, fostering meaningful discussions and exchange of ideas across different perspectives and domains.

How to cite: Dias Carneiro, B., Isidoro Losada, A. M., Schreurs, M., and Kee, K.: Interdisciplinary Insights into Urban Climate Governance: Navigating Complexities Through Collaborative Strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6733, https://doi.org/10.5194/egusphere-egu24-6733, 2024.

EGU24-6958 | Posters on site | ITS3.11/CL0.1.13

Linking social and scientific efforts to address arsenic and heavy metals pollution in a mining area in Central Mexico 

M. Aurora Armienta, Luz Maria Del Razo, Juan Manuel Ledón, Israel Labastida, Margarita Beltrán, Antonio Sosa, Ivan Morales-Arredondo, Alejandra Aguayo, Olivia Cruz, and Omar Neri

For many years, the high concentration of arsenic (As) in deep groundwater, up to 1.2 mg/L, has posed a health risk to the residents of Zimapán, a mining town in Mexico with a population of about 40,000. Additionally, ore processing, mainly through selective flotation, has resulted in the production of thousands of tons of tailings, which have accumulated in the outskirts of the town, causing damage to soils and shallow wells. To address this environmental issue, Mexican and international scientists have conducted studies focused on various environmental compartments. Since the earliest studies, whose aim was to identify the source of As pollution, the local authorities and people of Zimapán have been involved in the research activities.

Three years ago, a collaborative working group was formed, including local authorities, scientific and social researchers from various universities, local social organizations, and individuals who were committed to the environment (Environmental Research Network, REA). Their participation has included support for field activities, communication and exchange of knowledge, and the promotion of alternatives identified by scientific and social efforts to high-level authorities.

The outcomes of their work have been significant. They have rehabilitated the As removal treatment plant, which was installed about 15 years earlier as a result of this science-social collaboration. Additionally, they have identified local limestone as an option to treat tainted water and acid mine drainage. They have also supported the municipality in building rain harvesting systems in two schools to provide safe water to students. Moreover, they have interacted with miners to propose alternatives to minimize the impact of the tailings, among other achievements. The quality of drinking water supplied to downtown Zimapán is not yet in line with the national As drinking water standards, which require the arsenic level to be below 0.025 mg/L. The current level of arsenic in the water varies between 0.2 and 0.4 mg/L, which is a significant improvement from the previous level of 1.2 mg/L. However, efforts are still underway to achieve a safe water supply that meets the national standards. The REA has been effective in reducing the arsenic concentration in the water and has proven to be a viable social-scientific method for creating a healthier environment in the locality. It is also a model for other areas in Mexico that are impacted by arsenic contamination.

How to cite: Armienta, M. A., Del Razo, L. M., Ledón, J. M., Labastida, I., Beltrán, M., Sosa, A., Morales-Arredondo, I., Aguayo, A., Cruz, O., and Neri, O.: Linking social and scientific efforts to address arsenic and heavy metals pollution in a mining area in Central Mexico, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6958, https://doi.org/10.5194/egusphere-egu24-6958, 2024.

Idea and objectives: Urban citizens are key beneficiaries of benefits delivered by urban green-blue infrastructure as nature-based solutions. However, the delivery as well as the utilization of ecosystem services is tied to local context and therefore, depending, e.g., on the types of locally relevant societal or environmental issues, urban morphology, socio-demographic characteristics of potential beneficiaries and resulting demands for ecosystem services, or conditions of urban nature inclusive of the state of health of green elements. In this regard, citizens may not only act as beneficiaries of benefits provided by nature, but also as knowledge holders regarding local conditions in the broadest sense. Tapping into this body of knowledge, e.g., through citizen science and/or participatory mapping approaches, is considered crucial for achieving resilient, sustainable, and locally relevant as well as more widely accepted nature-based solutions that promote human health and well-being. From a set of diverse cases, the application of a trait-based framework showcases how citizen science and participatory mapping may support urban planning and the promotion, management and/or monitoring of urban green-blue infrastructure as nature-based solutions at the local level.

Background: Traits are understood as aggregate features of individual elements of the green-blue infrastructure, including, e.g., spatial, structural, functional, sensory, institutional or contextual qualities. In line with the social-ecological traits concept, these characteristics are seen to shape human experiences, knowledge and affordances, thus linking qualities of urban nature with ecosystem services and therefore, potential (co-)benefits. However, traits may also help to uncover local social-environmental issues including potentials and concerns, thus challenging urban policy-making. The implemented citizen science framework that is being presented adopts social-ecological traits as research theme-related boundary objects, e.g., to explore citizens’ awareness, perceptions and ideas of locally-specific traits. In so-doing, first, potential feedback loops that may shape compatibility of urban green-blue infrastructure elements for specific purposes, uses, and/or users may be uncovered. Second, potential pathways for local action may be identified to support a more holistic and more inclusive management and planning of nature-based solutions.

How to cite: Scheuer, S., Basnou, C., Sumfleth, L., and Haase, D.: How do we perceive green spaces? Trait-based citizen science to support the monitoring and management of nature-based solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8008, https://doi.org/10.5194/egusphere-egu24-8008, 2024.

Carbon emissions are closely related to climate change and sustainable development. Despite the existence of a large amount of research on carbon emissions, previous studies have focused more on regional analysis and lacked building-level research. When it comes to building-level carbon emissions, it usually involves a limited number of buildings, or collects a large amount of survey data within a specific region, which cannot be extended to large areas. This study takes buildings in Bao'an District, Shenzhen as the basic unit and uses statistical yearbooks, population density and nighttime light images to allocate total carbon emissions into each building through a top-down approach, to gain a more comprehensive understanding of the distribution of carbon emissions and their relationship with human activities. The findings of this study are expected to promote energy conservation and emission reduction and provide data support for achieving the goals of carbon peak and carbon neutrality.

How to cite: Lin, Z. and Huang, B.: Research on Building-level Operational Carbon Emissions in Shenzhen Based on Multi-Source Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8236, https://doi.org/10.5194/egusphere-egu24-8236, 2024.

The aviation industry, among the transportation sector, has come under heightened scrutiny as it is a major contributor to global carbon emissions and one of the most challenging industries to decarbonize. In response to the overwhelming calls for climate actions, the aviation industry has turned to a market-based approach - voluntary carbon offsetting - showcasing their dedication to carbon reduction. Investing in high-quality carbon offset projects holds great significance and contributes to the global efforts aimed at reducing carbon emissions. However, the corporate communication of airlines, crucial in influencing public perception and comprehension regarding voluntary carbon offsetting, has faced criticism for its lack of transparency and accuracy. This research therefore investigates the communication practices of voluntary carbon offsetting in the aviation industry, focusing on accessibility, clarity and transparency, and operational aspects. The study employs a multi-faceted approach, including a literature review on greenwashing, a case study of five Asian-based airlines, and the development of a coding scheme for content analysis. By examining the airlines’ official websites and sustainability reports, we seek to identify patterns and variations in their communication strategies on voluntary carbon offsetting. Preliminary results from the literature review and ongoing case study analysis showcase the importance of accessibility, transparency, and clarity in voluntary carbon offsetting communication. As the research progresses, further content analysis will unveil the potential instances of misleading tactics and highlights of best practices, fostering a more informed and transparent approach to voluntary carbon offsetting communication in the aviation industry. 

How to cite: Tsoi, H. N.: Corporate Communication on Voluntary Carbon Offsetting in the Aviation Industry: A Case Study of Asian Airlines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8593, https://doi.org/10.5194/egusphere-egu24-8593, 2024.

EGU24-9999 | Orals | ITS3.11/CL0.1.13 | Highlight

FAIR to Enable Cross-Domain Research 

Simon Hodson

The major global scientific and human challenges of the 21st century (including climate mitigation and adaptation, environmental sustainability, biodiversity and ecosystem management, disaster risk reduction, the interplay of society, the economy and energy policy) can only be addressed through cross-domain research that seeks to understand complex systems through machine-assisted analysis at scale.  Our capacity for such analysis is currently constrained by the limitations in our ability to access and combine heterogenous data within and across domains.  The FAIR principles and the frameworks set by Open Science provide a significant part of the solution.  Attention needs to be paid to the interfaces where data is used between disciplines: the geosciences have a vital role to play in this work.

To help address these issues, CODATA has been entrusted by the International Science Council (ISC) to develop a programme of activity: ‘Making Data Work for Cross-Domain Grand Challenges’.  After some exploratory work, the flagship activity is the WorldFAIR project which focuses on the implementation of the FAIR principles both within and across 11 different domain and cross-domain case studies, with a central effort to understand and guide cross-domain FAIR. It is the first broad-based effort to understand the issues around cross-domain and cross-infrastructure FAIR implementation through a case study driven methodology. Ultimately, WorldFAIR will provide guidance for FAIR implementation both within specific domains and infrastructures and across them.  The necessity, affordances and opportunities for cross-domain research are often overlooked, partly due to entrenched academic disciplines.  This presentation will outline a number of concrete examples of work to advance cross-domain interoperability of relevance to the geosciences community.

The I and the R of FAIR pose considerable challenges but are fundamental to addressing complex issues where datasets need to be combined and in enhancing scientific rigour and reproducibility.  Consequently, increasing attention is being paid to semantics, the maintenance of referenceable vocabularies and ontologies and to metadata profiles—and to tools that facilitate the tracking of provenance and process, or that use variable level metadata and semantics to facilitate data integration.  The semantics of space are particularly important in data linking and combination.  WorldFAIR is also developing the Cross-Domain Interoperability Framework (CDIF) which identifies a set of functional requirements for interoperability, particularly for steps in data combination, and recommends good practices for each of these requirements, in relation to the use of existing or emerging standards and specifications.  The CDIF is categorically not a new standard, but is intended to act as a lingua franca across domain data practices and encourage the incorporation of a number of standards that perform important and specific functions across domains.  We are keen to test this approach with colleagues from as many disciplines and application areas as possible.

This talk will explore these developments in detail, make a case for the importance of further work on the I and the R of FAIR, and invite the geosciences research community to participate in the wider WorldFAIR initiative.

How to cite: Hodson, S.: FAIR to Enable Cross-Domain Research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9999, https://doi.org/10.5194/egusphere-egu24-9999, 2024.

EGU24-10601 | ECS | Orals | ITS3.11/CL0.1.13

The Climate Potential of Garden Management: A Socio-Ecological Perspective 

Janne Teerlinck, Kelly Wittemans, Valerie Dewaelheyns, Trui Steen, and Ben Somers

Despite being one of the most densely populated and urbanized regions of Europe, 84% of Flanders' citizens have a garden, covering 12% of its territory. Research has shown that the collective network of domestic gardens could make a substantial contribution to climate change adaptation and mitigation, emphasizing their spatial and ecological importance as an integral part of the urban green infrastructure. Nevertheless, these private outdoor spaces are autonomously managed by many individual gardeners, often prioritizing aesthetics rather than environmental considerations. Understanding how people manage their gardens, and why, is thus crucial for unlocking the climate potential of gardens. This understanding can shed light on the current situation and identify opportunities for change. Unfortunately, limited research has been conducted on both garden management practices and the social drivers behind the decision-making process of individual gardeners. Therefore, our research aimed at unveiling current management practices and examining their variations across the urban gradient of Flanders. Through an online citizen science survey with a substantial sample size (n = 827) of Flemish domestic garden owners, we assessed garden management practices, as well as, motivations and self-reported knowledge. Potential cofounding factors such as personal, socio-economic and spatial context were also taken into account. Using a mixed model approach, we researched to what extent motivations, self-reported knowledge and context influence garden management decisions. Simultaneously, our analysis focused on variations of garden management practices across different urbanization levels, highlighting the intricate relationship between local contexts and the diverse ecological and social drivers influencing individual gardeners' decisions. By recognizing this interconnectedness, our findings offer insights that can inform urban planning and policy strategies to harness the untapped potential within these private green spaces. Ultimately, integrating social science into environmental studies is crucial for a comprehensive approach to addressing climate change and encouraging individual gardeners to adopt more climate-resilient practices.

How to cite: Teerlinck, J., Wittemans, K., Dewaelheyns, V., Steen, T., and Somers, B.: The Climate Potential of Garden Management: A Socio-Ecological Perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10601, https://doi.org/10.5194/egusphere-egu24-10601, 2024.

Integrating social science into environmental research is essential in order to reduce people’s climate anxiety and assist human beings adapt in the low-carbon transition process. The concept of a just transition, emphasizing dignified work contributing to environmental sustainability, has gained prominence in socio-environmental discussions, seeking a balanced and equitable transition process that incorporates considerations of environmental justice, labor relations, and social inequality. However, the application of just transition in the commercial sphere remains underexplored.  This research aims to investigate decent work and just transition at the micro-level, centering on the financial industry in Taiwan, currently actively adopting advanced strategies for a low-carbon transition. In the transition to a low-carbon economy, workers frequently encounter the challenge of insufficient knowledge to shift towards more sustainable practices, along with the adverse effects of unemployment. The study emphasizes the pivotal role of social dialogue among corporate decision-makers and employees, urging the decision makers to consider the wider impact of their actions on stakeholders and society from a bottom-up perspective. The methodology involves a comprehensive investigation, including literature reviews on decent work, social dialogue, and just transition. A structured social dialogue framework is formulated to ensure the inclusion of workers' voices in decision-making. Social indicators, drawn from the literature review, are utilized to assess the effectiveness of corporate practices, labor conditions, and social sustainability. The initial findings highlight challenges in implementing environmental practices, gaps in salary ratios, inclusivity in decision-making, and the impact of extended working hours on employee well-being. These identified factors not only present alternative perspectives from workers in the decision-making process but also contribute to shaping inclusive adaptation strategies to enhance climate resilience during the low-carbon transition. As Taiwan progresses in this direction, the findings and approach outlined in this study could serve as a model for other nations with similiar systems, facilitating broader discussions on the adaptation of just transition into a sustainable society.

How to cite: Hsu, Y. and Tung, C.-P.: Socio-Environmental Integration in Taiwan's Financial Industry: A Path to Low-Carbon Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10989, https://doi.org/10.5194/egusphere-egu24-10989, 2024.

EGU24-11458 | Orals | ITS3.11/CL0.1.13

Developing Energy Communities with Intelligent and Sustainable Technologies – First Results 

Alexander Los, Rebecca Moody, Charalampos Andriotis, Seyran Khademi, and Pablo G. Morato

In a recently started scientific project aiming at “Developing Energy Communities with Intelligent and Sustainable Technologies” (DE-CIST), we combine physical data on buildings in Rotterdam (The Netherlands) with socio-economic data from neighbourhoods and input from citizens and communities. Individual building data, together with meteorological, air quality, and GHG emission data, are processed by a novel AI solution classifying neighbourhoods and buildings based on their current status of energy sustainability, and their energy saving and emission reduction potential. This, in turn, informs measures that fit best per building and per neighborhood. Yet, to reveal which buildings or neighbourhoods are the worst off, we approach the problem using a socio-technological transitions perspective, which takes into account the needs and concerns of all citizens, notably the ones of the most vulnerable populations to reveal energy poverty and injustice. Using this approach, we will show which neighbourhoods can benefit the most, technically as well as socially.

Our presentation will start with an overview of the DE-CIST project and demonstrate how the combination of environmental and social information can make the energy transition process more efficient, economically viable, equitable, and more human. From recent analysis we conclude that energy communities have a strong effect on trust and engagement, fostering environmental awareness and motivation to save energy. In our presentation we will provide further insights into energy efficiency and renovations of buildings, and into how we can realize a fair, coherent energy transition process using a combination of results from AI-based methods, environmental modelling (of air pollution), and our analysis of the interviews with stakeholders and survey data.

 

How to cite: Los, A., Moody, R., Andriotis, C., Khademi, S., and Morato, P. G.: Developing Energy Communities with Intelligent and Sustainable Technologies – First Results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11458, https://doi.org/10.5194/egusphere-egu24-11458, 2024.

The use of data across disiplinary boundaries is a challenge at many levels, but in order for researchers to make sense of often-unfamiliar data, they must be provided with a wealth of information regarding the provenance, methodology, structure, and semantics of data. Historically, such information has been modelled and implemented in different ways within different scientific domains. Approaches to geo-spatial data are especially problematic when we consider disiplines such as Environmental Science and Social Science. Recent work on cross-domain exchange of such metadata suggests that there are ways to improve this situation, making it far easier to support collaborative research. 

The EOSC "Climate Neutral and Smart Cities" project has demonstrated how improved tools for describing provenance and data processing could be developed for researchers, based on existing metadata standards such as DDI Lifecycle and DDI Cross-Domain Integration (DDI-CDI). Some of the same standards - notably DDI-CDI - are also at the core of an emerging framework designed to address the needs of cross-domain FAIR data exchange. This framework, the Cross-Domain Inteoperability Framework (CDIF) , is being developed through the WorldFAIR project, which looks at eleven different domain use cases. It exemplifies the kind of interoperability framework recommended by the EC's "Turning FAIR into Reality" report (doi: 10.2777/1524).

Collaborative research involving environmental, climate, and social data is increasingly relevant as we try to understand how our world is changing, and what policies will best help us to address these changes. Aligning our data management and documentation systems on emerging best practice will make this collaborative research easier and more effective, helping us to understand the issues we face. 

How to cite: Gregory, A.: Cross-Domain Standards, Tools, and Technical Approaches: EOSC "Climate Neutral and Smart Cities" and the WorldFAIR CDIF Framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11938, https://doi.org/10.5194/egusphere-egu24-11938, 2024.

EGU24-15639 | ECS | Orals | ITS3.11/CL0.1.13

Transdisciplinary assessment of social-ecological vulnerability to Climate Change in Southwest Madagascar 

Estelle Razanatsoa, Lindsey Gillson, and Malika Virah-Sawmy

Climate models have shown that there will be an increasing susceptibility to drought in the future for semi-arid regions. However, the impact of these droughts depends on the sensitivity of landscapes and the adaptive capacity of communities. Using a vulnerability framework, and a mixed-methods approach, this paper assesses the vulnerability of the social-ecological systems along a rainfall gradient transect in southwest (SW) Madagascar at multiple timescales. We used a transdisciplinary approach, that combines synthesized regional climate records to assess the exposure to drought, and fossil pollen data from four sites ranging from wetter to drier areas to assess the sensitivity of landscapes over the last 2000 years. Local ecological knowledge (LEK) from household surveys from the driest sites in the Plateau Mahafaly was then conducted to infer adaptive capacity of local communities. Results show that over time, changes in climate linked to drought increase the vulnerability of the social ecological systems in Southwestern Madagascar particularly to the communities’ livelihoods in the driest regions, where there were fewer adaptation options, their need to migrate, and also on biodiversity. Although some coping and adaptation strategies including migration are in place for the communities, these might create feedback loop leading to further degradation and impacts on biodiversity and its conservation, especially in the driest regions where degradation is most likely to occur due to lower adaptive capacity. 

How to cite: Razanatsoa, E., Gillson, L., and Virah-Sawmy, M.: Transdisciplinary assessment of social-ecological vulnerability to Climate Change in Southwest Madagascar, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15639, https://doi.org/10.5194/egusphere-egu24-15639, 2024.

We delve into the comprehensive approach employed by the CAMS PL - Copernicus Atmosphere Monitoring Service National Collaboration Program for disseminating air quality knowledge to society. The initiative encompasses outreach through various channels, primarily leveraging social media platforms and the organization's website. A crucial aspect of this dissemination strategy is rooted in insights from surveys conducted among diverse stakeholders, including non-profit organizations, local administration units, the scientific community, secondary school teachers and students.

Specifically, this presentation sheds light on the program's utilization of Instagram and Facebook profiles as dynamic tools for engagement. The nuances of connecting with various demographics through these popular social media platforms are explored, emphasizing the adaptability and responsiveness required to convey air quality information effectively.

This presentation aims to contribute to the broader discourse on effective science communication strategies, particularly in environmental awareness and education.

How to cite: Drzewiecki, P. and Gienibor, A.: Disemination of air quality knowledge to the society through CAMS PL - Copernicus Atmosphere Monitoring Service National Colaboration Program., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16646, https://doi.org/10.5194/egusphere-egu24-16646, 2024.

EGU24-17770 | Orals | ITS3.11/CL0.1.13 | Highlight

Bringing the human dimension into the measurement of greenhouse gases emissions 

Diana Zavala-Rojas and Agustin Blanco Bosco

Given the growing concern about climate change and its impact on the lives of citizens, it is more necessary than ever to study their attitudes towards the environment and policies to mitigate it, especially in more polluted places such as cities. The Pilot Application in Urban Landscapes (PAUL) project, within the Integrated Carbon Observation System (ICOS Cities) network and in collaboration with the European Social Survey European Research Infrastructure Consortium (ESS ERIC), aims to introduce the social aspect of pollution measurement by conducting a three-wave panel survey in Paris and Munich to explore citizens' attitudes towards public policies to mitigate climate change, urban air quality, energy use and transport, among other topics. The presentation will cover the design of the survey, preliminary results from the first two waves, and how survey data can be mixed with environmental data to improve the findings and help understand social perceptions of climate change in cities.

How to cite: Zavala-Rojas, D. and Blanco Bosco, A.: Bringing the human dimension into the measurement of greenhouse gases emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17770, https://doi.org/10.5194/egusphere-egu24-17770, 2024.

EGU24-18487 | Orals | ITS3.11/CL0.1.13 | Highlight

Real-time Data Using Services: A Co-design Opportunity in ICOS Cities Project  

Tatu Marttila, Idil Gaziulusoy, Katie Berns, and Liisa Ikonen

ICOS Cities is an EU-funded project that aims to develop a systematic greenhouse gas measurement system for urban areas. The Work Package (WP) 1 of the project investigates economic, societal, and political dimensions that influence how city decision-makers use and will use emission data. The two main aims of WP1 are to: 1) Collect, unlock and harmonise prior information on city climate infrastructures and emissions, and 2) Investigate relevant services the city observatory should provide to answer the needs of cities in terms of estimation of their GHG emissions and implementation of their climate policies. Stakeholder engagement is facilitated in WP1 to map the information, service and policy needs of the city administrations, as well as by conducting social surveys and semi-structured interviews with the citizens. The authors are responsible for WP1 Task 1.4, which aims to co-design a number of service prototypes demonstrating the potential of the project in the pilot cities context and develop a general methodology for service development for the use of other cities. 

In the initial phase of our research, we conducted a benchmarking study to develop an in-depth understanding of existing services used by the cities to display and make sense of emission data and feed into policy processes from the perspective of their intended users. To achieve this, first, a number of stakeholders in different European cities have been surveyed to collect data on the existing services. Then, the technological constraints and the situation in three selected pilot cities of the project (Zurich, Munich, Paris) have been further explored in selected in-depth interviews with pilot city representatives or other topical experts. As a result, we developed an initial typology of existing services targeting different users of GHG emissions data, including but not limited to city-level policymakers. Several service types related to GHG monitoring were found, focusing on interactive carbon impact data, emission reduction monitoring, and services for estimating emissions of different types. These services have also been targeted at different actor groups and geographical resolutions and have different design realisations. 

Our findings indicate that services that connect real-time measurements (or even periodic measurements) to activities in municipal planning currently do not exist. Despite the availability of real-time data, the practices and standards on how such data is processed and used are only emerging, and the data is scattered amongst several actors. There also exist major challenges to moving assessments further from scope 1 (the direct impacts of energy and fuel use), and the process depends on many types of supplementary data. These gaps, amongst other elements of the service system, indicate significant opportunities for new service development, which we will focus on in the next phase of the project.

How to cite: Marttila, T., Gaziulusoy, I., Berns, K., and Ikonen, L.: Real-time Data Using Services: A Co-design Opportunity in ICOS Cities Project , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18487, https://doi.org/10.5194/egusphere-egu24-18487, 2024.

Ambiguity is a unique form of uncertainty that goes beyond merely indicating knowledge deficits or gaps; rather, it represents a state of confusion among decision actors. This confusion arises within a group due to the coexistence of diverse, and at times, conflicting meanings and interpretations concerning a situation. In the presence of ambiguity, it may not be clear what the main issues of concern are, who hold responsibility over them, what needs to be done. As an inherent characteristic of a collective, ambiguity is tightly linked with diversity and plurality, and the processes and procedures that underlie group dynamics. Here, I argue that ambiguity plays a pivotal role in adapting to climate change.

To investigate the functioning of ambiguity, I draw upon (uncertainty) relational theory and analyse different study cases of water management. The results suggest that ambiguity can yield significant benefits in adaptation. It enhances flexibility in managing unknown conditions, enables the anticipation of conflicts and avoids maladaptation, and creates opportunities for establishing new supportive relationships and alternative solutions. These insights contribute to a nuanced understanding of the role of ambiguity in climate change adaptation, offering valuable guidance for policymakers, water managers, and stakeholders engaged in crafting resilient and sustainable water management strategies.

How to cite: Brugnach, M.: Ambiguity: Why does it hold a key role in the adaptation to climate change?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18518, https://doi.org/10.5194/egusphere-egu24-18518, 2024.

Through our work in Science Project 9 of EOSC Future WP6.3 we demonstrate that relevant environmental data and data on citizens' values, attitudes, behaviors and involvement can be combined for social, political and scientific analysis.

In the project we are combining data from the European Social Survey with air quality data from the European Environmental Agency and climate related data from Copernicus ERA5. Over 50 indicator variables have been produced by social scientists and environmental specialists in collaboration, allowing researchers to study the impact of similar environmental factors on urban citizens attitudes and behaviors.

The project uses the metadata standards DDI-Lifecycle and DDI-Cross domain integration to document data from the project and make them FAIR.

Particular focus has been put on the provenance of the integrated data we provide through the project, showing how the data were computed. A provenance description prototype application has been developed to make the processes used to fully transparent and understandable for people and computers.

This poster presentation will give an overview of the work done in the project and the related deliverables.

How to cite: Orten, H. and Beuster, B.: Data from the European Social Survey in the Context of Climate and Air Quality in Cities , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18735, https://doi.org/10.5194/egusphere-egu24-18735, 2024.

EGU24-19180 | Orals | ITS3.11/CL0.1.13

Participatory modelling and knowledge integration in LTSER platforms 

Veronika Gaube, Claudine Egger, Bastian Bertsch-Hörmann, Andrea Stocker-Kiss, and Barbara Smetschka

Improving sustainability in local socio-ecological systems needs implementation of regionally adapted policies for sustainable development, which are based on place-based knowledge production and engaged stakeholder collaboration. One such approach is the Long-Term Socio-Ecological Research (LTSER) platform. The LTSER network emerged as a bottom-up process where existing local and national initiatives formed a network and were recognised as research infrastructures at European level. Conditions for joining the LTSER network include (usually): support from the local, regional and national authorities of the platform; the existence of long-term data sets (especially biodiversity indicators, but also abiotic variables); and the inclusion and integration of socio-economic data. One of these LTSER platforms is the Eisenwurzen in Austria, which has a long tradition in cooperating in inter- and transdisciplinary social-ecological research.

With the proposed presentation we would like to give an insight into the organisation of the LTSER platform Eisenwurzen and the challenges and successes it faces in promoting inter- and transdisciplinary research. We will present participatory modelling projects carried out in the region. The key challenge for transdisciplinary research, which aims to integrate diverse societal and scientific knowledge systems, is to produce both societal and scientific impacts at the same time. Participatory modelling is a method that uses models in three ways: as a means to generate knowledge, to achieve knowledge integration and to enable societal impact. Agent-based modelling is a computer simulation technique that allows the simulation of different actors as agents, the socio-economic and natural environment in which they are embedded, and the interactions between agents and between agents and their environment. The models with individual farm households as agents simulate how changes in socio-economic and political conditions affect patterns of land use, agricultural production and the socio-economic situation within that region.

We discuss how and why participatory modelling can help to enhance the impact potential of transdisciplinary research, as well as the limitations of different types of models. We show that participatory modelling allows for the integration of relevant societal and environmental knowledge into the models and for the development of scenarios and strategies in collaboration with stakeholders. Participatory modelling shows its strength in structuring communication about future scenarios and recommendations for action to achieve the goals of the different groups involved in transdisciplinary research. Stakeholders can use the model for effective discussion and education processes to find sustainable ways of land use development.

How to cite: Gaube, V., Egger, C., Bertsch-Hörmann, B., Stocker-Kiss, A., and Smetschka, B.: Participatory modelling and knowledge integration in LTSER platforms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19180, https://doi.org/10.5194/egusphere-egu24-19180, 2024.

EGU24-19474 | Posters on site | ITS3.11/CL0.1.13

Impact of the 2021 Flood Disasters on human social and mental health, focusing on elderly people in Germany 

Chen Song, Funda Atun, Justine Ianthe Blanford, and Carmen Anthonj

Flooding is one of the most common environmental disasters that cause mental and physical health problems. Flooding can cause loss of life and damage to personal property and critical public health infrastructure. Elderly people are at particular risk of the effects of floods, and their implications on social and mental health. This study is being conducted in the Ahr Valley, Germany which was heavily flooded in July 2021 (Figure 1). This flood destroyed towns and villages in the valley, causing more than 180 casualties and huge material damage (Silvia et al., 2021). The sudden-onset flood disaster caught the Ahr basin residents by surprise and had an impact on the mental and social health of the affected people. This study addresses the mental and social health effects of the 2021 flooding in the Ahr Valley, Germany, on elderly people. Preliminary findings, the research approach to data collection, survey, challenges faced, and their implications on the progress of the project will be introduced. 

How to cite: Song, C., Atun, F., Blanford, J. I., and Anthonj, C.: Impact of the 2021 Flood Disasters on human social and mental health, focusing on elderly people in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19474, https://doi.org/10.5194/egusphere-egu24-19474, 2024.

EGU24-19646 | ECS | Posters on site | ITS3.11/CL0.1.13

Fostering Cultural Ecosystem Services: The Impact of Social Media and Online Intermediaries in Promoting Payment for Ecosystem Services  

mona nazari, Nicolas Bilot, Julia Ramsauer, and Harald Vacik

Cultural ecosystem services, encompassing intangible benefits like spiritual enrichment, cognitive development, and aesthetic experiences, play a crucial role in enhancing individual well-being. Despite their profound impact, these services often face limited economic recognition and marketability, highlighting the importance of improved acknowledgment in future ecosystem assessments. The emergence of Payments for Ecosystem Services (PES) as a market-based mechanism offers compensation to landowners for managing their land to deliver various ecosystem services.

While PES provides incentives for conservation, challenges such as the lack of market information, participation avoidance, and mistrust hinder its widespread adoption, especially concerning the physical, emotional, and mental benefits derived from ecosystem services. Bridging this gap requires a focus on education and outreach, emphasizing not only the provisioning and regulating ecosystem services but also the cultural ones. PES programs, being information-intensive, demand a comprehensive understanding of ecosystem services and their management impacts.

To address these challenges, we propose leveraging social media, specifically through local social media influencers (LSMIs), as online intermediaries in PES initiatives. In the modern world, social media has proven to be a potent solution for boosting awareness, trust, and promotion for various businesses, making it a viable avenue for PES. Unlike traditional offline intermediaries, LSMIs on social media platforms can effectively engage with local communities, fostering awareness and trust-building.

Our research focuses on the European context, exploring the role of LSMIs in the preparatory phase of PES programs. Through a literature review, we identified a framework of potential key indicators of social media (SM) and LSMIs. To gain comprehensive perspectives from PES buyers and sellers in online social networks, we conducted a survey involving three PES case studies in Spain, France, and Austria.

The findings underscore YouTube and Instagram's popularity as the preferred social media platforms among both buyers and sellers of ecosystem services within the cultural context. Photos and videos emerged as captivating mediums, with more than 50% expressing the affirmative impact of this contemporary tool in advancing cultural ecosystem services. Geographically, Spain led in leveraging social media for the promotion of cultural ecosystem services, followed by France and Austria.

By understanding the dynamics between LSMIs, social media platforms, and PES initiation, our research contributes to a more comprehensive understanding of social media's role in promoting ecosystem services and sustainable environmental practices.

How to cite: nazari, M., Bilot, N., Ramsauer, J., and Vacik, H.: Fostering Cultural Ecosystem Services: The Impact of Social Media and Online Intermediaries in Promoting Payment for Ecosystem Services , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19646, https://doi.org/10.5194/egusphere-egu24-19646, 2024.

EGU24-19756 | Posters on site | ITS3.11/CL0.1.13

Towards Sustainable Agriculture: Classifying the Environmental Impact of Italian Wheat Farming 

Gianfranco Giulioni, Concetta Cardillo, Antonella Del Signore, Edmondo Di Giuseppe, Arianna Di Paola, Antonio Gattone, Massimiliano Pasqui, Sara Quaresima, Marco Simonetti, and Piero Toscano

Reducing the environmental impact of food production represents one of the most significant challenges to increase sustainability.

The ECOWHEATALY project - Evaluation of policies for enhancing sustainable wheat production in Italy - aims at tackling the issue of environmental impacts of the wheat production system in a dynamic socio-economic and environmental interaction setting by analyzing the changes in farmers' behavior after the adoption of green policies by the national authorities and in combination with the level of price in the main worldwide markets.

 

In the context of the ECOWHEATALY project, the behavior of farmers operating in Italy is classified into a few macro-typologies according to the farm environmental impact in terms of pesticides, fertilizers, and fossil fuel uses, with their costs and revenue profiled in alignment. To this end, ECOWHEATALY will take advantage of the Farm Accountancy Data Network (FADN), an extensive database of national surveys providing harmonized micro-economic data, including resource uses and costs, for farms in the European Union (EU). Specifically, data on farms' uses of pesticides, fertilizers, and usage time of agricultural machinery (as a proxy of fossil fuel consumption) are fed into the Agglomerative Hierarchical Clustering (HC) algorithm, an unsupervised state-of-the-art machine learning technique widely employed for clustering purposes. The cluster analysis, configured with the cluster number set to 5 based on the corresponding HC dendrogram, yields five distinctive groups, each briefly characterized as follows: G1) Farms exhibiting a pronounced inclination for excessive pesticide use. This group also records the highest quantity of nitrogen per hectare. Notably, these farms utilize few hours of agricultural machinery, suggesting concentrated applications of chemicals; G2) Farms applying a significant amount of nitrogen per hectare but minimal or no phosphorus and potassium, indicating unbalanced fertilizer use tilted towards nitrogen; G3) Farms displaying a high usage of agricultural machinery, accompanied by substantial doses of phosphorus-based fertilizer, moderate quantities of nitrogen, and minimal pesticide use; G4) Farms with a relatively medium to low environmental impact, identified by fertilizer use dominated by phosphorus and followed by potassium; G5) Farms with a relatively low environmental impact, distinguished by lower and balanced use of fertilizers and pesticides.

The resultant groups are characterized using FADN micro-economic variables, including current costs, net farm income, subsidies, and salable gross production. This profiling will enable the ECOWHEATALY project to undertake additional activities to identify green incentives capable of steering farm practices toward greater sustainability. The transformation of the Italian wheat production system, resulting from firms transitioning between different types due to agricultural and environmental policies, will be assessed through the development of an agent-based model at the national level. Moreover, ECOWHEATALY will proceed to gauge the environmental impact of policies by implementing the Life Cycle Assessment (LCA) methodology using the model's outputs, introducing a novelty in the field of green policy evaluations.

 

How to cite: Giulioni, G., Cardillo, C., Del Signore, A., Di Giuseppe, E., Di Paola, A., Gattone, A., Pasqui, M., Quaresima, S., Simonetti, M., and Toscano, P.: Towards Sustainable Agriculture: Classifying the Environmental Impact of Italian Wheat Farming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19756, https://doi.org/10.5194/egusphere-egu24-19756, 2024.

EGU24-20080 | ECS | Orals | ITS3.11/CL0.1.13

Assessing the role of stakeholder communication in agricultural adaptation and land-use decision-making 

Bastian Bertsch-Hörmann, Veronika Gaube, Lubos Halada, Ines Rosario, and Karlheinz Erb

In the face of climate change, land users worldwide must adapt their farming practices to increasing abiotic and biotic pressures. This requires acquisition of new knowledge and technologies and farmers have to navigate local-to-global, complex systems with diverse stakeholders. The concept of Agricultural Knowledge and Innovation Systems (AKIS) emerged to better understand and govern knowledge production and innovation uptake in agriculture. Network science principles enable the characterization and assessment of land-use-related communication, its influence on decision-making, and socio-cultural phenomena in natural resource systems.

To contribute to this field, a network survey and analysis was conducted in three Long-Term Socio-Ecological Research (LTSER) Platforms in Austria (Eisenwurzen, EW), Portugal (Montado, MT), and Slovakia (Trnava, TR) to investigate the state of local climate change adaptation and land-users’ communication. Respondents were prompted on socio-demographic, agronomic, and network variables, covering the structure of agricultural/forestry holdings, management intensities, adaptation measures, primary contact persons, and communication characteristics. Local land-users and other stakeholders were surveyed using a snowball approach. Primary data collection occurred between July 2022 and April 2023 via the online open-source application LimeSurvey© (in-person interviews for TR). Datasets were processed and analyzed using Microsoft Excel©, IBM SPSS©, and Gephi© software.

For social network analysis, node-and-edge tables were created, allocating respondents and their contacts to predefined stakeholder groups. Duplicate edges were merged by summing communication frequency values and averaging communication influence values, leading to the creation of farmer-centric and de-centralized land-use networks.

Preliminary results reveal differences and commonalities in the social land-use networks across the study regions. In all three regions, land users communicate most frequently and influentially with fellow land-users, the chambers of agriculture (in EW and TR) and farmers’/foresters’ associations (in MT). EW exhibited more frequent and influential communication with authorities, political representatives, and protected areas than the other regions. The scientific community, however, was prominently rated in MT and TR but not even mentioned in EW. In TR, economic and market actors were among the most frequent/influential contact persons, unlike in MT and EW. MT's land-use network highlights the prominent role of Portuguese land-user associations and private consultants, with a subordinate role for economic and environmental actors.

Calculations of the average degree of influence of the communication on the decision-making varied, with MT having the highest, EW medium, and TR the lowest overall influence. MT also displayed the highest density of actor groups and frequency values, indicating a more coherent network and stronger use of information by Portuguese farmers. Conversely, Slovakian farmers (in TR) appear more reluctant regarding external communication and advice.

In conclusion, network studies prove valuable insights for assessing and analysing AKIS and associated actors, providing a deeper understanding for designing and governing sustainable land-use and climate change adaptation strategies.

How to cite: Bertsch-Hörmann, B., Gaube, V., Halada, L., Rosario, I., and Erb, K.: Assessing the role of stakeholder communication in agricultural adaptation and land-use decision-making, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20080, https://doi.org/10.5194/egusphere-egu24-20080, 2024.

EGU24-20468 | Orals | ITS3.11/CL0.1.13

Integrating environmental modelling and qualitative social science to evaluate BECCS from abandoned cropland 

Jan Sandstad Næss, Ida Marie Henriksen, and Tomas Moe Skjølsvold

Bioenergy with carbon capture and storage (BECCS) is essential in most climate change mitigation pathways, but the deployment of dedicated bioenergy crops risks enhancing land use competition. Recultivating recently abandoned cropland to produce perennial grasses has been highlighted as an option for near-term bioenergy deployment with reduced sustainability trade-offs. However, the real-world feasibility of utilizing abandoned cropland for bioenergy and BECCS is still unclear.

We used a combination of natural science and qualitative social science methods to assess near-term recultivation opportunities for bioenergy, considering biophysical potentials, future biomass demand, and sociotechnical conditions. Focusing on Norway, we processed high-resolution global gridded land use projections from integrated assessment to unravel how global drivers may affect Norwegian land use with future global climate action. We mapped recently abandoned cropland using satellite data and quantified bioenergy and BECCS resource potentials using a crop yield model. We interviewed local farmers and stakeholders and performed a policy document analysis in the region with the highest resoure potential. Applying the multi-level perspective, we investigated the interplay between technical aspects and social aspects.

Land use projections showed major near-term bioenergy crop deployment in SSP-RCP2.6 scenarios and Trøndelag had the highest Norwegian near-term bioenergy resource potentials from abandoned cropland. While we found a theoretical potential for bioenergy crop expansion, the sociotechnical analysis showed a lack of real-world feasibility of achieving the modelled pace of bioenergy expansion from SSP-RCP2.6 scenarios. Remote sensing insufficiently captured actual local land availability for bioenergy. New policies are needed if BECCS from abandoned cropland is to deliver a meaningful contribution to climate change mitigation. Increased integration of social science perspectives into large-scale modelling exercises is key to better understand the role of BECCS in climate change mitigation.

How to cite: Næss, J. S., Henriksen, I. M., and Skjølsvold, T. M.: Integrating environmental modelling and qualitative social science to evaluate BECCS from abandoned cropland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20468, https://doi.org/10.5194/egusphere-egu24-20468, 2024.

The term “ESG” began with UN Global Compact’s (IFC, 2004) initiative “Who Cares Wins-Connecting Financial Markets to a Changing World.” Since then, capital markets have become a key facilitator of the corporate ESG movement. Today, due to the climate change, ESG movement is drawing unprecedented attention from corporations and their stakeholders, among which investors of capital markets also exert unprecedented pressures on corporations’ ESG efforts and performance. However, while every corporation now seems to or claims to strive for corporate ESG, many corporations are performing “greenwashing” instead of true ESG. Some studies showed that greenwashing did enhance corporations' financial performance (Li et al., 2023). Although research results on the relationship between greenwashing and corporate financial performance are inconsistent, it is clear that greenwashing at least helps corporations to escape from the direct pressures from capital markets, in addition to the pressures from other stakeholders. This brings a question: Why should corporations proactively invest in ESG? If we think that stakeholder theory and legitimacy theory have answered this question, we are assuming that corporate greenwashing is not possible, which is just the opposite of the fact. 

To answer the above question, we must come back to a fundamental question: Can true ESG generate competitive advantages? If the answer is no, logically, we may conclude that the corporate ESG movement is not sustainable and vice versa. To answer the second question, we focus on consumers, whose purchasing behavior determines whether true ESG can generate corporations' competitive advantage and the resulting excess profit. Therefore, in the current study, we developed a consumer behavior model of corporate ESG, which models how corporate true ESG may affect consumers’ behavior and hypothesizes a positive relationship between the purchase and the true corporate ESG. Furthermore, we conducted an empirical study to evaluate the hypothesis. The results of the current study have crucial implications on what motivates the consumers' sustainability (or green) purchases and whether corporations should invest in true ESG. Fortunately, the empirical results support our hypothesis on the positive impact of true corporate ESG on the purchase. Based on the consumer behavior model, strategy implications for corporations’ ESG investment were derived. 

How to cite: Ho, S. P. and Hsu, Y.: Is the Corporate ESG Movement Sustainable? A Consumer Behavior View and Evidence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22034, https://doi.org/10.5194/egusphere-egu24-22034, 2024.

EGU24-1556 | ECS | Posters on site | ITS4.8/CL0.1.16

Vulnerability functions based on insurance data for wind, precipitation, hail and flood damages for residential and commercial buildings in the Netherlands 

Daan van Ederen, Wouter Botzen, Jeroen Aerts, Veronica Lupi, Paolo Scussolini, Hans de Moel, and Koos Gubbels

Global warming is changing the climate and causing more frequent extreme weather events, such as floods and precipitation extremes. Future financial losses are expected to rise further due to a continued increase in economic exposure to intensifying extremes. As a result, climate change is recognized as an important source of risk for financial institutions. Insurance companies use natural catastrophe models to estimate the expected climate-related risk (in terms of losses) of their non-life insurance portfolios. Within these models, the vulnerability function describes the susceptibility of objects to  damages from natural hazards, which is of fundamental importance to the sound estimation of natural catastrophe losses. This paper constructs empirically based vulnerability functions for natural catastrophe models that estimate wind, precipitation, hail and flood damages for distinct object classes (i.e., residential and multiple commercial building types). For this, we leverage a unique insurance dataset from Achmea with high quality damage claims for different perils. This dataset contains the claim amount, building reconstruction value, location and multiple building characteristics (e.g., building use and material) at the object level for more than half a million claims over the past 40 years in the Netherlands. The vulnerability functions describe multivariate relationships between the damage ratio of objects and one or multiple natural hazard intensity measures (e.g. wind speeds and direction), primary and secondary modifiers (i.e., building characteristics). In addition, both confidence and prediction intervals are constructed. This study innovates upon the literature by using large samples of high quality damage claims data to estimate vulnerability functions for multiple natural catastrophes and object classes in the Netherlands. Our analysis pays special attention to model assumptions, the goodness-of-fit and uncertainty intervals. The results can serve as inputs for public, academic and open-source natural catastrophe models to facilitate the estimation of accurate natural catastrophe damages now and in the future.

 

How to cite: van Ederen, D., Botzen, W., Aerts, J., Lupi, V., Scussolini, P., de Moel, H., and Gubbels, K.: Vulnerability functions based on insurance data for wind, precipitation, hail and flood damages for residential and commercial buildings in the Netherlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1556, https://doi.org/10.5194/egusphere-egu24-1556, 2024.

EGU24-1637 | ECS | Posters on site | ITS4.8/CL0.1.16

Climate Risk Assessment Framework for Real Estate Investments 

Thijs Endendijk, Daan van Ederen, Wouter Botzen, Hans de Moel, and Jeroen Aerts

Climate change is forming an increasingly larger risk for the financial sector, although climate-related financial risks may be underestimated by financial institutions and markets. Financial institutions, such as banks, pension funds, and insurers are mainly exposed to physical climate risks through their investments in real estate. In the absence of any adaptation actions, physical climate risks for these real estate investments are expected to increase because of the higher frequency and intensity of natural disasters in a changing climate. In response to the increasing financial risks associated with climate change, regulatory bodies have been actively shaping new legislation over the past years (e.g. TCFD, CSRD, EU Green Taxonomy).

One of the main channels through which the financial sector is affected by flood risk is through physical damage to real estate. After this physical damage, housing prices decrease, and houses located in flood-prone regions sell with a discount compared to similar houses in other areas. Additionally, the credit standing of households diminishes, making mortgages more likely to default, increasing mortgage credit risks for lenders. The 2008 global financial crisis has shown that real estate and its underlying values are a pivotal part of the modern financial system. For this reason, it is imperative to monitor and assess how flood risk affects real estate markets and investors through both direct and indirect channels.

These impacts from flooding are currently not yet fully integrated within the risk assessment framework of institutional investors. Dynamic integrated models for insurance markets do exist in the literature, where standard catastrophe flood risk models are matched with insurance sector outcomes. There is currently no clear overview of how physical climate risks affect the balance sheets and profitability of (institutional) real estate investors. This study provides a structured integrated framework for evaluating both the direct and indirect flood-related risks associated with investments in both residential and commercial real estate. Although our bottom-up Dynamic Integrated Flood Real Estate Impacts (DIFREI) model can be applied to other international contexts, we use a real estate portfolio from one of the largest financial service providers in the Netherlands to illustrate the framework’s use and outputs. The DIFREI models can be used to draw lessons for applications on real estate investment portfolios.

How to cite: Endendijk, T., van Ederen, D., Botzen, W., de Moel, H., and Aerts, J.: Climate Risk Assessment Framework for Real Estate Investments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1637, https://doi.org/10.5194/egusphere-egu24-1637, 2024.

EGU24-2056 | Orals | ITS4.8/CL0.1.16 | Highlight

Assessing the risk of climate change to a business 

Andy Pitman, Ed Saribatir, Catherine Greenhill, Sam Green, and Samuel Pitman

The realisation that climate change threatens economic systems has led investors, standard-setters and regulators to call on businesses to assess their exposure to climate-related risks, and to disclose the financial impact of these in their annual reports and financial statements where material. Indeed, mandatory disclosure requirements have already been implemented in some jurisdictions and are being proposed elsewhere. Mandatory disclosure of physical climate risk by a single business predisposes that the business can reasonably assess this risk. Here, we use the analogy of a spider’s web to examine how changes in the frequency and magnitude of extremes, that break parts of the web, combine to affect the efficiency of a hypothetical business. We demonstrate that the precise location of an extreme event, the precise characteristics of the event, and whether a subsequent event occurs close to or distant from an earlier event strongly influences vulnerability. In short, to estimate the impact of climate change induced extremes on a business requires not merely the general frequency of events, but the precise geolocation of the event mapped on the vulnerabilities of the business. We conclude that mandatory disclosure of future climate risk by a business cannot be other than deeply uncertain and this is not resolvable via foreseeable advances in global or regional climate modelling.

How to cite: Pitman, A., Saribatir, E., Greenhill, C., Green, S., and Pitman, S.: Assessing the risk of climate change to a business, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2056, https://doi.org/10.5194/egusphere-egu24-2056, 2024.

EGU24-2381 | ECS | Orals | ITS4.8/CL0.1.16 | Highlight

Asset-level assessment of climate physical risk matters for adaptation finance 

Giacomo Bressan, Anja Duranovic, Irene Monasterolo, and Stefano Battiston

Climate physical risk assessment is crucial to inform adaptation policies and finance. However, science-based and transparent solutions to assess climate physical risks are still missing. This is a main limitation to fill the adaptation gap. We provide a methodology that quantifies physical risks on geolocalized productive assets, considering their exposure to both chronic and acute impacts (hurricanes) across the scenarios of the Intergovernmental Panel on Climate Change. Then, we translate asset-level shocks into economic and financial losses. We illustrate the methodology in an application to Mexico, a country that is highly exposed to physical risks, and attracts adaptation finance and foreign investments. We find that investor losses are underestimated up to 70% when neglecting asset-level information, and up to 82% when neglecting acute risks. Therefore, neglecting the asset-level and acute dimensions of physical risks can lead to large errors in the identification of the relevant adaptation policy response, investments and finance tools aimed to build resilience to climate change.

How to cite: Bressan, G., Duranovic, A., Monasterolo, I., and Battiston, S.: Asset-level assessment of climate physical risk matters for adaptation finance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2381, https://doi.org/10.5194/egusphere-egu24-2381, 2024.

EGU24-3055 | ECS | Orals | ITS4.8/CL0.1.16

Choose Your Model Wisely: Navigating Uncertainties in Future Global Tropical Cyclone Risks 

Simona Meiler, Chahan Kropf, Kerry Emanuel, and David N. Bresch

Future tropical cyclone risks will evolve depending on climate change and socio-economic development, entailing significant uncertainties. A comprehensive uncertainty and sensitivity analysis of future tropical cyclone risk changes is thus vital for robust decision-making not least in the context of physical climate risk disclosure. However, the outcomes of such uncertainty and sensitivity analyses are closely tied to the chosen model setup, warranting caution in interpretation and extrapolation. Our study investigates how four distinct tropical cyclone hazard models as well as alternate representations of socio-economic development influence future tropical cyclone risks. We find that average tropical cyclone risk increases 1-5% by 2050 across all models and global study region. But the estimated maximum risk increases by the end of the century range from 10-400% depending on the hazard model choice. Such diverging results are critically relevant for climate risk assessment in the financial and insurance sectors where usually model choices are made a priori and uncertainties are not quantified systematically. Additionally, socio-economic factors drive risk increase more strongly across all models, while the uncertainty in these risk drivers is hazard model-specific. For instance, the MIT model-based results are sensitive to the choice of global climate model, while estimates from CHAZ, STORM, and climate-conditioned IBTrACS are mainly influenced by exposure scaling based on Shared Socio-economic Pathways. Finally, we assert that quantitative estimates of uncertainty and sensitivity to model parameters greatly enhance the value and depth of climate risk assessments, which are essential for robust decision-making in the financial and insurance sector.

How to cite: Meiler, S., Kropf, C., Emanuel, K., and Bresch, D. N.: Choose Your Model Wisely: Navigating Uncertainties in Future Global Tropical Cyclone Risks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3055, https://doi.org/10.5194/egusphere-egu24-3055, 2024.

In the ECB top-down, economy-wide climate stress test, we developed novel damage functions to measure damages to physical capital from different natural hazards at granular firm-level. Combining address-level, forward-looking physical risk scores from Moody’ Four Twenty Seven with projected damages from acute and chronic physical risk from NGFS, we translated firms’ exposure towards floods, wildfire and sea level rise risk to future losses on their physical capital. Using loan-level information from the euro area credit registry, we assessed the deterioration in firms' profitability and indebtness due to physical damages and subsequently the change in default probabilities and expected losses on banks' corporate loan portfolios.  The dataset is unprecedented in terms of coverage, integrating both regulatory and private data sources and comprising financial and climate risk data for a total of 2.6 million European firms and 1,600 euro area banks, covering around 80% of total loan exposures of the euro area regulatory credit registry.  

Losses from physical risk were calculated as the product of firms’ future exposure towards the frequency and intensity of wildfire risk, flood risk and sea level rise and combining this with the expected physical damages as a share of GDP from the NGFS scenarios. Annual firm-level losses from physical risk were calculated between 2020 and 2050 and for three different scenarios, i.e. the NGFS Net Zero 2050, Delayed Transition and Current Policies scenarios. The results show that acute physical risk will lead to moderate to high damages on firms’ physical capital in the long term, depending on the expected temperature increase of the scenario in question. By 2050, damages will be disproportionately higher in a Current Policy scenario relative to the other scenarios, leading to a maximum deterioration of 3% of firms’ assets compared to a maximum deterioration of 1% in a Net Zero 2050 scenario. The results show that until 2050, the credit risk of borrowers most vulnerable to physical risk is around 25% higher in a Current Policy scenario relative to a Net Zero 2050 scenario.

How to cite: Emambakhsh, T.: Measuring physical damages from natural hazards in the ECB top-down, economy-wide climate stress test , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4075, https://doi.org/10.5194/egusphere-egu24-4075, 2024.

EGU24-5217 | ECS | Orals | ITS4.8/CL0.1.16 | Highlight

The risks of climate tipping points for financial investors 

Paul Waidelich, Lena Klaaßen, Stefano Battiston, and Bjarne Steffen

While financial investors are increasingly alert to the economic threats of climate change, most academic and regulatory assessments of financial risk have not accounted for climate tipping points. Here, we combine recent advances in the integrated assessment modeling of tipping points with return projections for major stock indices to assess index-specific risk exposures to climate change damages. We find that for the MSCI World, a globally diversified stock index, tipping points increase the expected loss due to climate change damages under SSP2-4.5 by 62% (USD 0.2 trillion)—a magnitude comparable to moving from meeting the Paris targets to the "hothouse world" scenario RCP8.5. The reason is that investment horizons are more affected by near-term risks of tipping points than by long-term differences in mitigation outcomes. Risk increases are driven by methane-related tipping points (permafrost thaw and ocean methane hydrates) and ice sheet disintegration, with the highest increases for investments in emerging markets with extensive coastal areas, such as India or Indonesia. The absolute magnitude of financial risks varies substantially across damage functions and assumptions regarding damage persistence. However, the relative importance of tipping points is robust across different damage specifications and investor discount rates. Therefore, our results call for integrating tipping points into climate scenario analyses in the financial sector and climate risk stress tests by regulators.

How to cite: Waidelich, P., Klaaßen, L., Battiston, S., and Steffen, B.: The risks of climate tipping points for financial investors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5217, https://doi.org/10.5194/egusphere-egu24-5217, 2024.

EGU24-6194 | Posters on site | ITS4.8/CL0.1.16

Estimating Flood Risk under Global Warming: An Approach from the Insurance Industry 

Sumeet Kulkarni, Shubham Choudhary, Francesco Zuccarello, Marie Ekström, and Giulia Giani

The (re)insurance sector has established methods and tools to assess historical and current risk for several weather driven hazards in many geographical regions. Using those same methods to estimate risk under global warming is fraught with challenges as one may expect complex changes to all four risk components (hazard, exposure, vulnerability, and disaster response capability).

Nevertheless, despite much uncertainty about how weather hazards may change under climate change, the insurance sector is increasingly expected to include risk estimates for future-looking business strategies. Supervisors (across different regulatory domains) are currently working with the insurance sector to better understand the transmission channels for climate risk and provide guidance on how to meaningfully estimate future risk due to weather driven hazards.

To encourage discussion and transparency on methodology used to assess risk for insurance purposes (such as developing underwriting layers, or portfolio management) we demonstrate a recent approach developed by the global (re)insurance broker Gallagher Re to estimate risk scores of future floods aligned, and therefore comparable, with current flood risk estimates. We demonstrate the approach for both pluvial and fluvial flood and discuss how challenges (such as those detailed above) were addressed to derive a methodology that can be deployed globally, given access to robust and credible projections of extreme precipitation and streamflow.

How to cite: Kulkarni, S., Choudhary, S., Zuccarello, F., Ekström, M., and Giani, G.: Estimating Flood Risk under Global Warming: An Approach from the Insurance Industry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6194, https://doi.org/10.5194/egusphere-egu24-6194, 2024.

Climate change induced extreme precipitation poses a significant threat to agricultural production. Such impacts extend beyond local agricultural production regions, generating remote and cross-sector impacts that disrupt global supply chains (GSCs). While the direct impacts of extreme precipitation on agricultural production have been widely studied, how such local impacts cascade through supply chain networks to remote places remains elusive, partly because of the complex interdependencies within the global trade systems. To address this, we propose a Resilience Enhancement in Supply Chains Under Environmental Shocks (RESCUES) framework. RESCUES couples an agricultural production loss model with a dynamic recursive economic network model. It allows us to identify channels through which the impacts of climate change on agricultural production propagate along GSCs to interconnected sectors and regions. We design nine climate shock scenarios (i.e., dry, wet, and compound precipitation anomalies with extreme, severe, and moderate levels of severity) using the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) under two Shared Socioeconomic Pathways (SSPs) scenarios (SSP126 and SSP585). We then use RESCUES to simulate the GSCs dynamics over 2016-2050 under these nine scenarios. We find that direct agricultural losses driven by local precipitation anomalies can spread through GSCs to a wider range of countries and regions across the globe, creating large spatial spillover effects with direct and indirect economic losses. We estimate that the averaged per event total value-added (VA) losses caused by compound extremes is around $20.4/22.6 billion under SSP126/585, followed by dry extremes ($16.4/15.0 billion) and wet extremes ($8.7/11.6 billion). Moreover, the global distribution of direct and indirect losses exhibits high spatial heterogeneity. Countries with large agricultural outputs tend to have both high direct and indirect VA losses, especially in China, India, the United States, Russia, and Brazil. In contrast, poorer countries, such as Tanzania, Sudan, Myanmar, Yemen, Afghanistan, and Nepal, experience relatively larger direct losses, while rich regions heavily dependent on agricultural imports, including Hong Kong, Qatar, and Singapore, suffer relatively larger indirect losses. Considering that nations frequently implement export restrictions to ensure food self-sufficiency, we further design a hypothetical scenario to assess the global trade and economic impacts of near-term (2025-2030) agricultural export restrictions in four key food production regions (China, India, the United States, and Indonesia) under extreme precipitation anomalies. Our study highlights the importance of an integrated and comprehensive assessment of the risk footprint of climate change-related shocks, encompassing both direct and indirect impacts on GSCs. 

How to cite: Zhang, S. and He, X.: Vulnerabilities of Global Supply Chains to Agricultural Production Disruptions Caused by Individual and Compound Climate Shocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6973, https://doi.org/10.5194/egusphere-egu24-6973, 2024.

In today's global economy, the importance of transparent and quantitative sustainability reporting is escalating, reshaping corporate disclosure standards. This evolving landscape presents challenges to traditional business models and management tools, necessitating innovative approaches for effective adaptation. The development of standards such as IFRS S2, a set of global standards for climate-related disclosures that mandates companies to report on their environmental impact and climate risks, further complicates the reporting and compliance environment. This study explores the utility of the Sustainable Balanced Scorecard (SBSC) as a strategic instrument to enhance environmental, social, and governance (ESG) performance in light of heightened compliance demands. Utilizing the SBSC framework, the research begins with the development of a sustainability strategy map for a Taiwanese port logistics company, outlining its sustainability objectives and providing a foundation for analyzing the impact of IFRS S2. The research also employ the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method to analyze the causations among strategy goals, enriching the understanding of their interconnections and influence. The study then delves into the specifics of IFRS S2, assessing how these standards affect the company's financial disclosures, strategic planning, and governance framework. This dual approach highlights the intricate relationship between corporate strategy, sustainability integration, and IFRS S2 requirements. It identifies key areas where these elements intersect, offering insights into potential improvement areas and gaps. This research is particularly relevant for entities in the port logistics sector and related industries, emphasizing the critical role of innovative management tools like the SBSC in aligning business strategies with global sustainability goals and managing climate risks effectively.

How to cite: Wu, H.: Advancing Corporate Governance through SBSC: Navigating Compliance with IFRS S2 in Port Logistics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6989, https://doi.org/10.5194/egusphere-egu24-6989, 2024.

EGU24-7412 | ECS | Orals | ITS4.8/CL0.1.16

The Impact of Compound Hot-and-Dry Events on Household Well-being 

Jessie Ruth Schleypen

The socioeconomic impacts of compound extremes are sudden, severe, and multidimensional. Without precautionary measures, social and economic safety nets including community support and insurance, the negative effects of a single, short-run shock on households can extend to the long-run and persist over many years. Studies on the impacts of compound extremes have focused on objective measurements of well-being, including income, health, education; with much fewer studies on subjective well-being. Looking into subjective well-being takes an evaluative perspective on the quality of life, wherein the recovery from a disaster takes more than just the return to employment, for instance. Previous studies have shown that subjective well-being is also a good predictor of life expectancy, productivity, educational performance, and voting behaviour. Using econometric methods on sub-national, household panel data from the EU Survey of Income and Living Conditions (EU-SILC) and a composite index for the simultaneous occurrence of droughts and heatwaves, I quantify and compare the impacts of compound dry-and-hot events (CDHE) in Europe on objective and subjective measurements of well-being. The results of this study provide new information on the magnitude, as well as, the persistence of effects from CDHE, based on both the traditional income-based measurements versus the self-reported measurements of well-being.

How to cite: Schleypen, J. R.: The Impact of Compound Hot-and-Dry Events on Household Well-being, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7412, https://doi.org/10.5194/egusphere-egu24-7412, 2024.

EGU24-10342 | Orals | ITS4.8/CL0.1.16

Navigating Nature and Climate Risks: An Integrated Framework for Economic Assessment 

Miodrag Stevanovic, Patrick José von Jeetze, Justin Andrew Johnson, Andrej Ceglar, and Alexander Popp

Biodiversity loss and ecosystem degradation could pose a substantial threat to financial stability and the wider economy. Despite scientific evidence of the ongoing ecosystem degradation, methodological and data challenges have so far prevented a detailed assessment of the economic and financial risks.  While progress has been made in assessing climate change related risks, our understanding of the linkages between the economy and ecosystem service degradation is still limited. Here we pioneer a nuanced approach to understanding the emerging financial risks of ecosystem change.  Using the LPLmL-MAgPIE-SEALS modeling framework, we assess physical, transition and financial risks considering feedbacks from climate change, land use, and degrading ecosystem services. Focusing mainly on the EU, we also assess interconnectedness with other global regions where loss of ecosystem services is more pervasive. Our framework includes climate-sensitive spatially explicitly biophysical data within a partial equilibrium land-system model. Modelled land-use patterns are downscaled to derive fine-scale changes in ecosystem service supply and associated economic feedbacks. We assess various scenarios that build on the existing NGFS (Network for Greening the Financial System) framework. These scenarios range from a degraded world without policy interventions, to an integrated climate-nature scenario, with ambitious policies to mitigate both climate and ecosystem service change. The results indicate diverging biodiversity response based on varying climate and nature policy ambition, emphasizing the need to extend biodiversity safeguarding beyond exclusive reliance on climate mitigation policies. Financial risks are assessed through an analysis of sectoral dependencies on various ecosystem services, laying out the basis for a comprehensive framework that supports informed decision-making facing emerging climate and nature-related risks.

How to cite: Stevanovic, M., von Jeetze, P. J., Johnson, J. A., Ceglar, A., and Popp, A.: Navigating Nature and Climate Risks: An Integrated Framework for Economic Assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10342, https://doi.org/10.5194/egusphere-egu24-10342, 2024.

EGU24-11080 | Posters on site | ITS4.8/CL0.1.16

Beyond Single Company Risk Disclosure – Exploring the Efficient Frontier in Physical Risk Reporting 

Victor Wattin Håkansson, Sarah Hülsen, Simona Meiler, Leonie Villiger, Chahan M. Kropf, Jamie W. McCaughey, and David N. Bresch

Climate change is intensifying natural hazards, significantly increasing financial risks for businesses and stakeholders. This shift in physical risk is transforming companies' risk-return profiles and driving the need for transparent risk disclosure, in line with the guidelines from the Task Force on Climate-Related Financial Disclosure (TCFD; now further developed as IFRS S2). Despite many companies beginning to disclose risks, standardization efforts by regulatory bodies are still evolving. The varied and proprietary nature of climate risk information from commercial providers has hindered transparency and accessibility in risk scoring. This complicates the comparison and evaluation of risks, as well as the aggregation of risks at the portfolio level. Additionally, the scarcity of natural catastrophe models in non-OECD countries and the need for a globally consistent framework incorporating future climate scenarios pose further challenges.

Our study introduces an event-based reporting approach to address these challenges in climate risk disclosure. Companies are required to report modeled financial impacts of standardized hazard sets, including both gross and net risks due to their insurance protection. This method offers a solid foundation for risk metrics, risk-return profiling, and inter-comparison of risks at both individual company and portfolio levels. Leveraging CLIMADA (CLIMate ADAptation), an open-source climate risk assessment platform, we create a globally consistent, interoperable framework with reference hazard event sets for main perils under current and future climate conditions, accessible through a data API. 

By applying this method to the balance sheets of hypothetical multinational companies, we effectively assess financial risks and perform risk-return analyses, demonstrating the approach's practicality and potential in climate risk management and disclosure. We show, for instance, the potential for evaluating sectoral and cross-sectoral risk, which is only visible in the cross-company risk profile, and how portfolio risks due to spatial correlations can be captured.

How to cite: Wattin Håkansson, V., Hülsen, S., Meiler, S., Villiger, L., Kropf, C. M., McCaughey, J. W., and Bresch, D. N.: Beyond Single Company Risk Disclosure – Exploring the Efficient Frontier in Physical Risk Reporting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11080, https://doi.org/10.5194/egusphere-egu24-11080, 2024.

EGU24-11284 | Orals | ITS4.8/CL0.1.16 | Highlight

Exploring the efficient frontier in physical risk reporting 

David N. Bresch

An increasing number of countries request large companies to disclose their physical climate-related risks based on regulations inspired by work of the Task Force for Climate-related Financial Disclosure (TCFD). Current reports do not lend themselves to direct comparison of physical risks across companies and by no means allow investors to build a portfolio optimised with respect to physical risks. Methods such as event-based probabilistic natural catastrophe risk assessment exist and would allow for aggregation of pertinent information, taking into account global diversification of risk. Convergence of TCFD-reporting towards such methods would enable investors and financial intermediaries to construct portfolios with respect to an efficient frontier in terms of physical risks. In the true spirit of TCFD, this would allocate capital towards companies best positioned to cope with the impacts of climate change and hence incentivise economic actors to strategically embrace climate adaptation. We present a fully transparent and easily replicable open-source and -access approach to construct such an efficient frontier and will discuss resulting risk-reward profiles and implications for corporate strategy development in the context of climate change.

How to cite: Bresch, D. N.: Exploring the efficient frontier in physical risk reporting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11284, https://doi.org/10.5194/egusphere-egu24-11284, 2024.

EGU24-11412 | Orals | ITS4.8/CL0.1.16

Indirect impacts of region-specific heat extremes along the global supply network  

Xudong Wu, Lennart Quante, and Anders Levermann

The last decade has witnessed a surging occurrence of extreme heat worldwide. This can directly dampen local production capacity and also induce indirect repercussions through the global supply network. Yet, the cascading effect of region-specific extreme heat may differ greatly, which is by far poorly understood. By combining temperature observations with Acclimate—a dynamic agent-based model, we identify the region-specific temperature threshold for dampening local production and investigate the response of the global supply network to extreme heat in a region-by-region manner. Economic agents with significant repercussions on the globe are identified and indirect benefits along the global supply network from local heat adaptation are revealed. The outcome of this study supports common but differentiated adaptation strategies towards extreme heat.

How to cite: Wu, X., Quante, L., and Levermann, A.: Indirect impacts of region-specific heat extremes along the global supply network , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11412, https://doi.org/10.5194/egusphere-egu24-11412, 2024.

EGU24-11534 | Posters on site | ITS4.8/CL0.1.16

Financial risk management needs to integrate compound events in physical climate risk assessment 

Andrej Ceglar, Nicola Ranger, Kai Kornhuber, Michaela Dolk, and Olivier Mahul

The world has recently witnessed many unprecedented climate disasters, often coinciding with other crises such as pandemics, socio-economic instabilities and ecosystem degradation (closely linked to biodiversity loss). These compound shocks exert profound effects on human, environmental, and economic dimensions, presenting substantial implications also from a financial risk standpoint. Consequently, it becomes imperative to transcend the isolated assessment of individual events and associated risks and progress towards an integrated evaluation of interconnected crises. Compound shocks exhibit characteristics marked by non-linear, intricate, and often unpredictable effects on both society and the economy. Consequently, discerning their impacts cannot be simplified to a mere summation of the effects of their individual shocks. The intricate nonlinearities have the potential to amplify the repercussions of climate-related shocks, presenting considerable challenges to financial stability. Recent advancements in the fields of climate impact modelling, catastrophe risk modeling, machine learning, and macroeconomic modeling hold promise in addressing the existing gaps in modeling compound risks. Our study builds on a survey we conducted among twenty-six central banks and supervisory bodies, revealing a consensus on the crucial importance of considering compound shocks in climate change scenario analyses, specifically pertaining to physical. Leveraging the insights garnered from this survey, we set up a research direction towards integration of compound risks into the development of scenario narratives, storylines and (macro-)economic models capable of effectively capturing compound shocks.

How to cite: Ceglar, A., Ranger, N., Kornhuber, K., Dolk, M., and Mahul, O.: Financial risk management needs to integrate compound events in physical climate risk assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11534, https://doi.org/10.5194/egusphere-egu24-11534, 2024.

EGU24-12089 | ECS | Orals | ITS4.8/CL0.1.16

The Green-Scorpion: a preliminary study on the potential amplification of physical climate financial risks by nature-related risks and feedbacks 

Jimena Alvarez, Nicola Ranger, Anna Freeman, Thomas Harwood, Michael Obersteiner, Estelle Paulus, and Juan Sabuco

Climate change and biodiversity loss are not happening in isolation. The erosion of natural capital by human activities will compound and amplify physical climate risks, and vice versa. We present new analyses that demonstrates that ignoring nature in physical climate financial risk assessment will lead to significant underestimates of the scale of the risks. This has implications for financial institutions and for the prudential policies of Central Banks and supervisors. We develop the first set of integrated climate-nature scenarios to explore the potential scale of physical risks, building upon the NGFS conceptual framework, alongside a global risk assessment approach that combines the ENCORE tool with global natural capital datasets and a multi-regional input-output modelling approach. We produce estimates of risks for five ecosystem services - surface water, ground water, pollination, air quality and water quality - across 7 sectors and 44 countries and 5 rest of world regions. Our analysis suggests that nature-related risks are material in scale, exceeding $7 trillion value at risk. Based on analyses of historical analogues and risk transmission channels we show that nature and climate risks are strongly interconnected and share characteristics in their potential for non-linear, cascading impacts. We propose a set of principles for scenario analysis and a framework for developing decision-relevant scenarios, including an inventory of almost eighty potential nature-related physical risk shocks (hazard-primary economic receptor pairs) that can form the basis to scenario development.

How to cite: Alvarez, J., Ranger, N., Freeman, A., Harwood, T., Obersteiner, M., Paulus, E., and Sabuco, J.: The Green-Scorpion: a preliminary study on the potential amplification of physical climate financial risks by nature-related risks and feedbacks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12089, https://doi.org/10.5194/egusphere-egu24-12089, 2024.

EGU24-12339 | ECS | Orals | ITS4.8/CL0.1.16 | Highlight

Physical climate risk, sovereign credit ratings, and the benefits of adaptation 

Mark Bernhofen, Matt Burke, Nicola Ranger, and Gireesh Shrimali

Climate change is a risk to the financial stability of countries. The economic impacts of rising temperatures, increasingly frequent and intense extreme events, as well as the costs of adapting to these risks have the potential to significantly strain government (sovereign) finances. Perceived national climate risk hotspots may also discourage investment, reduce economic growth, and increase global inequality. To gauge sovereign financial risk, investors rely on sovereign credit ratings that assess a nation’s ability to repay its debt. A country’s credit rating determines its borrowing costs, influences investor confidence, and has impacts on economic stability and growth.

Recent estimates show that climate-induced sovereign credit downgrades could materialize for nearly 60 countries by 2030 (Klusak et al, 2023) because of the labour productivity impacts of increasing temperatures (Kahn et al, 2021). These sovereign climate risk estimates are severe, yet likely still an underestimate, as they do not consider the materialization of extreme events (acute climate risk) (Stern, 2016).

In this study, we provide new estimates of climate-induced sovereign credit downgrades by combining the sovereign climate risk model developed by Klusak et al. (2023) with models of acute climate risk. We focus on countries in south-east Asia and calculate the extreme losses from river floods and tropical cyclones under different future warming scenarios and the implications for sovereign credit risk. We also explore different options to adapt to these risks nationally, their associated costs, and model the risk reduction benefits of their implementation.

There is a failure to integrate extreme climate risk into economic and financial assessments (Stern et al, 2022). Many of these risks are underestimated in the current financial assessment of climate change (Trust et al, 2023) and may support more credible assessments of short-term risk. Our findings add to the growing body of work highlighting the importance of considering acute climate risk in estimates of climate financial risk (Pittman et al, 2022). We also show that adaptation can significantly reduce future losses and resultant sovereign credit risk, which serves as evidence against divestment from risk-prone countries and for investment in adaptation. We conclude by exploring the fiscal policy implications of our analysis for Thailand.

 

Kahn, M. E., Mohaddes, K., Ng, R. N., Pesaran, M. H., Raissi, M., & Yang, J. C. (2021). Long-term macroeconomic effects of climate change: A cross-country analysis. Energy Economics

Klusak, P., Agarwala, M., Burke, M., Kraemer, M., Mohaddes, K. (2023). Rising Temperatures, Falling Ratings: The Effect of Climate Change on Sovereign Creditworthiness. Management Science

Pitman, AJ., Fiedler, T., Ranger, N., Jakob, C., Ridder, N., Perkins-Kirpatrick, S., Wood, N., Abramowitz G. (2022). Acute climate risks in the financial system: examining the utility of climate model projections. Environmental Research: Climate

Stern, N. (2016). Economics: Current climate models are grossly misleading. Nature 

Stern, N., Stiglitz, J., & Taylor, C. (2022). The economics of immense risk, urgent action and radical change: towards new approaches to the economics of climate change. Journal of Economic Methodology

Trust, S., Joshi, S., Lenton, T., Oliver, J. (2023). The Emperor's New Climate Scenarios. Institute and Faculty of Actuaries and University of Exeter.

How to cite: Bernhofen, M., Burke, M., Ranger, N., and Shrimali, G.: Physical climate risk, sovereign credit ratings, and the benefits of adaptation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12339, https://doi.org/10.5194/egusphere-egu24-12339, 2024.

EGU24-13865 | Orals | ITS4.8/CL0.1.16

NGFS scenarios: Scope, design limitations and gaps 

Sebastian Werner, Alex Pui, and Motoshi Tomita

There has been increasing focus on climate risk disclosure within the industry, evidenced by a shift from guidance (TCFD) to standards (ISSB) based approach.  However, surveys show that climate scenario modelling remains challenging, with high complexity and lack of expertise cited as key reasons.

While there are global scenarios such as NGFS to support practitioners by providing key analytical foundations and parameters, concerns have been raised regarding the robustness of physical and transition risk assessment methodologies, and hence the fitness for such scenarios.  Given that the primary aim of climate scenario analysis at an entity level is to inform prudent risk management and business strategy, it is instructive to explore fundamental questions and context around the design of these scenarios, leading to an improved interpretation of end results.

To this end, we aim to critically review the fourth iteration of NGFS scenarios that have recently been released, with a particular focus on 3 areas: First, the evolution of scenarios since the first vintage in 2020. Secondly, the design limitations of IAMs which do not feature frictions that could allow for misprinting and price bubbles. Thirdly, we discuss how the scenario design could benefit from incorporating uncertainty into its variable projections.

How to cite: Werner, S., Pui, A., and Tomita, M.: NGFS scenarios: Scope, design limitations and gaps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13865, https://doi.org/10.5194/egusphere-egu24-13865, 2024.

EGU24-15905 | ECS | Orals | ITS4.8/CL0.1.16 | Highlight

Climate services for finance, lessons learned and feedback for the public sector 

Graham Reveley, James Brennan, Sally Woodhouse, Laura Ramsamy, Nicholas Leach, Patricia Sullivan, Jonathan Davies, and Joe Stables

Driven by regulations to understand and attempt to mitigate risk from climate change there is an increase in demand for climate risk data from the financial sector. This has led to the generation of 3rd party data providers, such as Climate X, who aim to bridge the gap between academic research and the requirements of the financial sector. This requires a multi-disciplinary team bringing together hazard, remote sensing, and climate scientists which allows us to combine open-source earth observations and climate model data with in-house hazard modelling to generate metrics and losses that are useful and useable for our clients.

In this talk we will cover the key requirements of our clients: asset-level and global intelligence, multi-hazard and loss information and multiple scenarios. We will outline how we address these, and how academic researchers can engage with the private sector to make their work as relevant as possible.

How to cite: Reveley, G., Brennan, J., Woodhouse, S., Ramsamy, L., Leach, N., Sullivan, P., Davies, J., and Stables, J.: Climate services for finance, lessons learned and feedback for the public sector, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15905, https://doi.org/10.5194/egusphere-egu24-15905, 2024.

EGU24-17148 | ECS | Posters on site | ITS4.8/CL0.1.16

How do interest rates affect decarbonisation pathways? A stakeholder-driven multi-model analysis. 

Natasha Frilingou, Dirk-Jan van de Ven, Shivika Mittal, Karamaneas Anastasios, Thomas Nikolakakis, Francesco Gardumi, Konstantinos Koasidis, and Alexandros Nikas

Decarbonisation of the energy sector is a critical task in the efforts to mitigate climate change. As sectoral emissions cuts in modelled pathways aligned with the Paris Agreement are projected to come from at-scale diffusion of emerging or new technologies as well as further development of existing solutions, energy-sector decarbonisation entails major investments in low-carbon technologies. At the same time, a significant chunk of these investments must be made in emerging and developing economies, which currently receive just one-fifth of global energy investments. This underinvestment is, at least partly, due to the large disparities in financing conditions and higher-risk profiles in said countries. Models used to assess decarbonisation pathways typically assume a uniform cost of capital; such assumption, however, does not do justice to real-world conditions and may therefore lead to inaccurate policy recommendations. Moreover, there is considerable uncertainty over how these costs may evolve in the future. In this study, we apply an empirical dataset of estimated cost of capital differentiated by technology and country and explore stakeholder-driven pathways of (de-)risking investments in clean energy vs. fossil-fuel technologies, using an ensemble of two global integrated assessment models and one electricity-system model. Furthermore, we attempt to incorporate a corrective justice dimension in our narratives by assessing the impacts of risk underwriting for low-carbon investments through taxing corporate windfall profits for 2022 and distributing the revenue as subsidies towards high-risk regions.

How to cite: Frilingou, N., van de Ven, D.-J., Mittal, S., Anastasios, K., Nikolakakis, T., Gardumi, F., Koasidis, K., and Nikas, A.: How do interest rates affect decarbonisation pathways? A stakeholder-driven multi-model analysis., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17148, https://doi.org/10.5194/egusphere-egu24-17148, 2024.

EGU24-17265 | ECS | Posters on site | ITS4.8/CL0.1.16

Modelled Multidecadal Trends in (Very) Large Hail in Europe, the United States and Globally 

Francesco Battaglioli, Pieter Groenemeijer, Mateusz Taszarek, Tomas Pucik, and Anja Rädler

Large hail events worldwide result in extensive damage, with individual events occasionally exceeding USD 1 billion in losses. Addressing the lack of comprehensive global observational networks, we developed Additive Logistic Regression Models for mapping the frequency of large and very large hail. These models were trained with data from lightning observations, hail reports, and convective parameters from the ERA5 reanalysis. Applying these models to ERA5 data spanning from 1950 to 2021, we reconstructed the probability of large and very large hail events across Europe and the United States. In the United States, hail trends during this period were generally weak and statistically non-significant. In Europe, trends were predominantly positive and significant with northern Italy standing out as a hotspot. Here, the convective activity has seen an abrupt increase with very large hail being 3 times more likely in recent years (2012-2021) than it was in the 1950s. This trend was corroborated by recent observations in the region, including the establishment of a new European hail record with hailstones measuring 19 cm in north-eastern Italy in July 2023. To create a globally applicable hail model, we used a training dataset of hail reports from Europe, the United States, and Australia combined. This effort resulted in the development of a comprehensive global climatology for very large hail. Additionally, we compared the modelled changes in hail frequency to observed changes in insured losses to better understand the complex relationship between hail frequency and hail risk across different regions worldwide.

How to cite: Battaglioli, F., Groenemeijer, P., Taszarek, M., Pucik, T., and Rädler, A.: Modelled Multidecadal Trends in (Very) Large Hail in Europe, the United States and Globally, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17265, https://doi.org/10.5194/egusphere-egu24-17265, 2024.

EGU24-17399 | Orals | ITS4.8/CL0.1.16 | Highlight

The Tipping Point Modelling Intercomparison Project (TIPMIP) 

Ricarda Winkelmann, Donovan Dennis, Jonathan Donges, Sina Loriani, Boris Sakschewski, and Johan Rockström

While tipping points in the Earth system are recognized in the public and policy debate as one of the major risks of anthropogenic climate change, our current knowledge of their dynamics involves a broad range of uncertainties, and so far there is no systematic risk assessment quantifying the likelihood as well as the impacts of exceeding tipping points in the Earth system. 

Here we introduce the Tipping Point Modelling Intercomparison Project (TIPMIP, www.tipmip.org), a major international initiative setting out to fill this gap in a multi-model approach: Based on ensembles of simulations with Earth system models as well as offline models combined with current observations, the experiments will serve to assess (1) the risk of crossing critical thresholds in the Greenland and Antarctic ice sheets, the Atlantic Meridional Overturning Circulation, tropical and boreal forests as well as high-latitude permafrost; (2) the short- and long-term (committed) impacts of crossing individual tipping points; (3) the (ir)reversibility of impacts on different timescales; and (4) the role of the forcing rate. TIPMIP also sheds light on potential model shortcomings when it comes to such highly-nonlinear dynamics in the Earth system which may significantly change projections for the 21st century and beyond. 

The TIPMIP outcome will serve to generate a risk map, highlighting regions in the world which are most vulnerable to tipping transitions, which will be an important basis for forward-looking policy decisions. 

How to cite: Winkelmann, R., Dennis, D., Donges, J., Loriani, S., Sakschewski, B., and Rockström, J.: The Tipping Point Modelling Intercomparison Project (TIPMIP), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17399, https://doi.org/10.5194/egusphere-egu24-17399, 2024.

EGU24-18055 | Orals | ITS4.8/CL0.1.16

Countries with future highest exposure to unprecedented climate extremes  

Jonathan Spinoni, Leonardo Chiani, Alessandro Dosio, Johannes Emmerling, Jacopo Ghirri, Marta Mastropietro, and Massimo Tavoni

In the last decades, the World experienced an increasing frequency and severity of weather-related extremes. Such events can remarkably affect multiple sectors as food, energy, and biosphere. In the framework of the activities of the ERC project EUNICE, and in order to understand the possible future impacts caused by climate extremes on population and socio-economic indicators, we firstly constructed a global database of climate indicators including eleven hazards (e.g., heatwaves, droughts, rainfall extremes, and windstorms), ranging from 1881 to 2100. For each grid point (0.5°), we provided different metrics as frequency, intensity, and number of unprecedented events at annual scale, dividing the future into five SSPs (plus two including temperature overshoot), and using the bias-adjusted CMIP6-based ISIMIP3b dataset as input. We therefore aggregated the parameters at country-scale - for each hazard - and we focused on the exposure of population and GDP to unprecedented future climate extremes, i.e. events never recorded in the past. We performed the analyses for two 30-year periods (2041-2070 and 2071-2100) and four Global Warming Levels (GWLs from 1.5 °C to 4 °C). Depending on the selected SSP and period, we present a structured ranking of countries that show the highest socioeconomic exposure to single or combined climate impact drivers. In this presentation, we also discuss the cost, in terms of cumulated events, of temperature overshoot above the 1.5 °C level to comply with Paris Agreement's goals. At a later stage, this new set of climate indicators will be also used to quantify the added value of including climate extremes in dedicated damage functions.

How to cite: Spinoni, J., Chiani, L., Dosio, A., Emmerling, J., Ghirri, J., Mastropietro, M., and Tavoni, M.: Countries with future highest exposure to unprecedented climate extremes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18055, https://doi.org/10.5194/egusphere-egu24-18055, 2024.

Overall uncertainty in climate model projections is composed of scenario, model, and internal variability components. While scenario uncertainty is expressed by considering different climate scenarios, model uncertainty and internal variability components are largely ignored by climate information service providers. Instead, model projections are often expressed through the ensemble mean, which may lead to both overly optimistic assessments of risk, or on the other hand misinformed maladaptation strategies.

Here, we propose a new uncertainty quantification approach that better informs end users of climate projections, showing that the multi-model internal variability, owing to its chaotic nature, is in fact virtually irreducible, and that model uncertainty grows moderately throughout the 21st century. For three future scenarios, we quantified the global internal variability of two metrics: annual precipitation (PRCP) and boreal summer average maximum daily temperature (TXJJA), by employing a single realization of each CMIP6 climate model. Our results showed that observed internal variability of the 1981-2010 period for the TXJJA metric has a negligible variation throughout the 21st century for all three scenarios. For the PRCP metric, small changes of internal variability were detected towards the end of the 21st century in the most adverse scenario (SSP3-7.0). Importantly, we observed that characterizing uncertainty in such manner produced a nuanced, and non-misleading results compared to that of the ensemble mean approach. Furthermore, the proposed uncertainty quantification approach can be expanded to similarly evaluate the uncertainty in indices of extreme weather.

How to cite: Gomez-Garcia, M. and Pui, A.: Demystifying model uncertainty and internal variability in climate change projections over the 21st century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18103, https://doi.org/10.5194/egusphere-egu24-18103, 2024.

EGU24-18139 | ECS | Orals | ITS4.8/CL0.1.16

Climate damage projections beyond annual temperature 

Jarmo Kikstra, Paul Waidelich, Fulden Batibeniz, James Rising, and Sonia Seneviratne

Projections of economic damages from climate change are key for evaluating the benefits of climate mitigation and informing discussions around adaptation needs. So far, global and country-level top-down assessments of GDP damages have focused on annual mean temperature changes and annual precipitation. Recent backward-looking studies have identified further impacts of variability and extremes in precipitation and temperatures on income growth.

Here, we examine GDP impacts and uncertainties under different global warming levels by combining empirical dose-response functions for temperature variability, rainfall deviations, and extreme precipitation with climate projections of 33 CMIP6 models. The main contribution of this work is to understand the projected relative contributions of multiple climate variables under many possible future climates.

We find that at a +3°C global warming level, global average losses reach 10% of GDP, with worst effects (up to 17%) in poorer, low-latitude countries. Relative to annual temperature damages, which find to seemingly capture heat wave impacts, the additional GDP impacts of projecting variability and extremes are relatively small and dominated by inter-annual variability, especially in lower latitudes. However, accounting for variability and extremes when estimating the temperature dose-response function still raises global GDP losses by nearly 2%-pts and exacerbates tail risks for economic growth.

Our results call for region-specific risk assessments and complementary research into climatic extremes not considered here, including their indirect effects on temperature dose-response functions. Additionally, it will be very important to further the work on understanding historical and future persistence and adaptive capacities for these different impact channels.

How to cite: Kikstra, J., Waidelich, P., Batibeniz, F., Rising, J., and Seneviratne, S.: Climate damage projections beyond annual temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18139, https://doi.org/10.5194/egusphere-egu24-18139, 2024.

EGU24-18364 | Orals | ITS4.8/CL0.1.16 | Highlight

Multi-hazards risk indicators for climate risk reporting 

Benoît Guillod, Alessio Ciullo, Quentin Bourgeois, Lukas Bodenmann, Jere Lehtomaa, and Sebastian Glink

In recent years, it has become more and more clear that climate change and its impacts do severely affect companies’ business. For example, acute climate risks driven by e.g. floods and tropical cyclones can impact physical assets and halt productions, whereas chronic climate risks such as droughts and temperature increases can have severe impacts on e.g. crop production, labour productivity and water availability. This increased understanding of climate risk on companies’ performances led to the establishment of the Task Force on Climate-related Financial Disclosure (TCFD) which provides a framework for disclosing and reporting climate-related risks and opportunities.

As TCFD requires businesses to quantify, rate and manage climate risks across various perils and regions, there is the need to develop climate risk indicators which comply with its recommendations. In this talk, we will introduce the indicators developed by CLIMADA Technologies - an open-core ETH spin-off company - for multiple hazards, incl. tropical cyclones, floods, winter storms, wildfires, droughts, heat waves, and cold spells. The indicators allow assessing and coherently summarising climate risk information in line with TCFD recommendations and thus support companies in taking resilient actions.

How to cite: Guillod, B., Ciullo, A., Bourgeois, Q., Bodenmann, L., Lehtomaa, J., and Glink, S.: Multi-hazards risk indicators for climate risk reporting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18364, https://doi.org/10.5194/egusphere-egu24-18364, 2024.

As our knowledge of the physical impacts associated with climate change develops, translating those insights into accurate estimates of societal and financial repercussions has become a key concern for a variety of decision-makers, including policymakers, insurance specialists, investors and regulators. Although this task is daunting, it can leverage the deep knowledge of the financial impacts of extreme natural events amassed over the past decades in the (re)insurance industry, where detailed assessments of location-level and portfolio-level risk are now commonly used.

In particular, Moody’s RMS has been at the forefront of catastrophe modelling for over 30 years, developing and supporting models for the US$2.5 trillion global (re)insurance market. These granular, bottom-up models bring together carefully calibrated stochastic simulations of extreme events, together with detailed regional assessments of the vulnerability of a wide range of building and infrastructure types, which are then converted into loss distributions that incorporate local market considerations, such as repair/replacement costs and business interruption costs. Those models have been validated not only against extensive geophysical observations, but also against hundreds of billions of dollars of granular damage and building-specific claims data.

In this context, Moody’s RMS has developed a novel bottom-up approach to assess the financial impacts of climate change, which leverages the respective strengths of catastrophe models and general circulation models. The ‘Climate on Demand Pro’ platform provides damage estimates at both location- and portfolio-levels, and incorporates an aggregation methodology that reflects the impacts of portfolio concentration or diversification. Those metrics are provided globally across the 21st century for various climate scenarios, across a suite of six acute and chronic climate perils (tropical cyclones, wildfires, inland floods, coastal floods, heat stress and water stress), as well as earthquake risk.

This presentation will include an overview of the models, showcase some key results and discuss various use cases across the financial sector. The importance of such detailed loss-based climate risk metrics for present and future regulatory requirements will be emphasized, together with the need for increased collaboration between academia, industry and regulators in addressing the challenges ahead.

How to cite: Roy, K. and Khare, S.: Leveraging Catastrophe Modelling Insights for Bottom-Up Assessments of Climate Change Physical Risk: The ‘Climate on Demand Pro’ Platform, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19069, https://doi.org/10.5194/egusphere-egu24-19069, 2024.

In the realm of finance for loss and damage, new funding mechanisms are emerging, yet the task of identifying and quantifying the losses and damages from extreme weather events attributable to climate change remains a complex challenge. Impact attribution, which extends beyond traditional attribution analyses of extreme weather events, is gaining more attention and methods are improving. However, their systematic integration into the loss and damage finance architecture will not be possible any time soon. With the rapidly escalating impacts of climate change, financial solutions designed to support affected communities and countries must align with the real-world necessity for predictability and swiftness of disaster risk finance.

Insurance, while not a panacea, has traditionally been envisioned as an important player in the domain of loss and damage finance. Nonetheless, insurance premia become prohibitively expensive in many regions and specific risks inch towards becoming uninsurable. Increasing the uptake of insurance and making it more affordable, e.g. through subsidies, can relieve some of the impacts and support affected communities with reliable financial flows. Here, parametric insurance is posited as a generally suitable solution with advantages over traditional indemnity insurance. It provides transparent and quick financial responses after extreme weather events, is less exposed to moral hazard and adverse selection.  

This research develops a scalable, objective, transparent, and pragmatic framework for the quantification and attribution of payout and premium increases of parametric insurance due to climate change. Apt for incorporation into new solutions such as the loss and damage fund and the Global Shield initiative, the framework would allow to mobilise substantial funding by blending public and private funds and leveraging the infrastructure of insurance companies. Employing this framework within a loss and damage finance architecture not only capitalizes on the inherent benefits of parametric insurance but also ensures that the allocation of resources is more closely aligned with changes in weather patterns, and therefore impacts, that are attributable to climate change.

The framework is applied to the context of tropical cyclone parametric insurance in various locations, as well as to heatwave parametric insurance in India. The results illustrate the alterations in payouts and premia attributable to climate change and quantify the loss and damage finance required to compensate for the climate-change related risk increases, whether as direct payments to policyholders/insurance companies affected by the insured events or as subsidies for insurance premia.

How to cite: Fabian, F.: Quantifying and attributing pay-out and premia increases of parametric insurance to climate change – A framework for scalable, objective, transparent and pragmatic integration into a loss and damage finance architecture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19327, https://doi.org/10.5194/egusphere-egu24-19327, 2024.

EGU24-21474 * | Posters on site | ITS4.8/CL0.1.16 | Highlight

Greening the financial system: How can national meteorological services drive the transition? 

Elizabeth Wright and Niall Robinson

Financial markets are key catalysts for a net-zero future by 2050, with trillions of capital and resources ready to be unlocked. So what is holding them back? Green finance is pushing to be at the forefront of any structured financial activity, however the lack of clear definitions, standards, and regulations, misaligned incentives and interests, scarce data and information, and a gap between the demand and supply of green finance is slowing down its impact and implementation. This talk examines the role of government agencies, such as the UK Met Office, in helping markets to address climate risk. By aligning the financial system with the Paris Agreement and Sustainable Development Goals, green finance can reduce the exposure of financial institutions to climate-related risks, such as stranded assets, physical damages, and transition costs and help to address some of the key challenges they are facing. 

How to cite: Wright, E. and Robinson, N.: Greening the financial system: How can national meteorological services drive the transition?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21474, https://doi.org/10.5194/egusphere-egu24-21474, 2024.

EGU24-1101 | ECS | Orals | ITS1.1/CL0.1.17

Monitoring The Development Of Land Heatwaves Using Spatiotemporal Models 

Swarnalee Mazumder, Sebastian Hahn, and Wolfgang Wagner

This study introduces an approach for land heatwave forecasting, using spatiotemporal machine learning models trained with ERA5 reanalysis data. We focused on key environmental variables like soil moisture, vegetation, and meteorological factors for modelling. The study utilized linear regression as a base model, augmented by more complex algorithms such as Random Forest (RF), XGBoost, and Graph Neural Networks (GNN). We defined heatwaves using temperature data from 1970-2000, and the training phase involved data from 2000 to 2020, focusing on predictive accuracy for 2021-2023. This methodology enabled a detailed exploration of heatwave trends and dynamics over an extended period. Finally, we used explainable AI methods to further deepen our understanding of the complex interplay between environmental variables and heatwave occurrences.

How to cite: Mazumder, S., Hahn, S., and Wagner, W.: Monitoring The Development Of Land Heatwaves Using Spatiotemporal Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1101, https://doi.org/10.5194/egusphere-egu24-1101, 2024.

Deep learning methods have emerged as a potential alternative for the complex problem of climate data downscaling. Precipitation downscaling is challenging due to its stochasticity, skewness, and sparse extreme values. Also, the extreme values are essential to preserve during downscaling and extrapolating future climate projections, as they serve as trivial signals for impact assessments. This research looks into the usefulness of a deep learning method designed for gridded precipitation downscaling, focusing on how well it can generalize and transfer what it learns. This study configures and evaluates a deep learning-based super-resolution neural network called the Super-Resolution Deep Residual Network (SRDRN). Several synthetic experiments are designed to assess its performance over four geographically and climatologically distinct domain boxes over the Indian subcontinent. Domain boxes over Central India (CI), Southern Peninsula (SP), Northwest (NW), and Northeast (NE), exhibiting diverse geographical and climatological characteristics, are chosen to assess the generalization and transferability of SRDRN. Following the training on a set of samples from CI, SP and NW, the performance of the models is evaluated in comparison to the Bias Correction and Spatial Disaggregation (BCSD), a renowned statistical downscaling method. NE is a transfer domain where the trained SRDRN models are directly applied without additional training or fine-tuning. Several objective evaluation metrics, like the Kling-Gupta Efficiency (KGE) score, root mean squared error, mean absolute relative error, and percentage bias, are chosen for the evaluation of SRDRN. The systematic assessment of SRDRN models (KGE~0.9) across these distinct regions reveals a substantial superiority of SRDRN over the BCSD method (KGE~0.7) in downscaling and reconstructing precipitation rates during the test period, along with preserving extreme values with high precision. In conclusion, SRDRN proves to be a promising alternative for the statistical downscaling of gridded precipitation.

Keywords: Precipitation, Statistical downscaling, Deep learning, Transfer learning, SRDRN

How to cite: Murukesh, M. and Kumar, P.: Downscaling and reconstruction of high-resolution precipitation fields using a deep residual neural network: An assessment over Indian subcontinent, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2552, https://doi.org/10.5194/egusphere-egu24-2552, 2024.

EGU24-2819 | ECS | Orals | ITS1.1/CL0.1.17

Hybrid-Modeling of Land-Atmosphere Fluxes Using Integrated Machine Learning in the ICON-ESM Modeling Framework 

Reda ElGhawi, Christian Reimers, Reiner Schnur, Markus Reichstein, Marco Körner, Nuno Carvalhais, and Alexander J. Winkler

The exchange of water and carbon between the land-surface and the atmosphere is regulated by meteorological conditions as well as plant physiological processes. Accurate modeling of the coupled system is not only crucial for understanding local feedback loops but also for global-scale carbon and water cycle interactions. Traditional mechanistic modeling approaches, e.g., the Earth system model ICON-ESM with the land component JSBACH4, have long been used to study the land-atmosphere coupling. However, these models are hampered by relatively rigid functional representations of terrestrial biospheric processes, e.g., semi-empirical parametrizations for stomatal conductance.

Here, we develop data-driven, flexible parametrizations controlling terrestrial carbon-water coupling based on eddy-covariance flux measurements using machine learning (ML). Specifically, we introduce a hybrid modeling approach (integration of data-driven and mechanistic modeling), that aims to replace specific empirical parametrizations of the coupled photosynthesis (GPP ) and transpiration (Etr ) modules with ML models pre-trained on observations. First, as a proof-of-concept, we train parametrizations based on original JSBACH4 output to showcase that our approach succeeds in reconstructing the original parametrizations, namely latent dynamic features for stomatal (gs) and aerodynamic (ga) conductance, the carboxylation rate of RuBisCO (Vcmax), and the photosynthetic electron transport rate for RuBisCO regeneration (Jmax). Second, we replace JSBACH4’s original parametrizations by dynamically calling the emulator parameterizations trained on the original JSBACH4 output using a Python-FORTRAN bridge. This allows us to assess the impact of data-driven parametrizations on the output in the coupled land-surface model. In the last step, we adopt the approach to infer these parametrizations from FLUXNET observations to construct an observation-informed model of water and carbon fluxes in JSBACH4.

Preliminary results in emulating JSBACH4 parametrizations reveal R2 ranging between 0.91-0.99 and 0.92-0.97 for GPP, Etr, and the sensible heat flux QH  at half-hourly scale for forest and grassland sites, respectively. JSBACH4 with the plugged-in ML-emulator parametrizations provides very similar, but not identical predictions as the original JSBACH4. For example, R2 for Etr (gs) amounts to 0.91 (0.84) and 0.93 (0.86) at grassland and forest sites, respectively. These differences in the transpiration flux between original predictions and JSBACH4 with emulating parametrizations only result in minor changes in the system, e.g., the soil-water budget in the two models is almost the same (R2 of ~0.99). Based on these promising results of our proof-of-concept, we are now preparing the hybrid JSBACH4 model with parametrizations trained on FLUXNET observations.

This modeling framework will then serve as the foundation for coupled land-atmosphere simulations using ICON-ESM, where key biospheric processes are represented by our hybrid observation-informed land-surface model.

How to cite: ElGhawi, R., Reimers, C., Schnur, R., Reichstein, M., Körner, M., Carvalhais, N., and Winkler, A. J.: Hybrid-Modeling of Land-Atmosphere Fluxes Using Integrated Machine Learning in the ICON-ESM Modeling Framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2819, https://doi.org/10.5194/egusphere-egu24-2819, 2024.

EGU24-3272 | ECS | Orals | ITS1.1/CL0.1.17

Reconstructing total water storage changes in the Yangtze River Basin based on deep learning models 

Jielong Wang, Yunzhong Shen, Joseph Awange, Ling Yang, and Qiujie Chen

Understanding long-term total water storage (TWS) changes in the Yangtze River Basin (YRB) is essential for optimizing water resource management and mitigating hydrological extremes. While the Gravity Recovery and Climate Experiment (GRACE) and its follow-on (GRACE-FO) mission have provided valuable observations for investigating global or regional TWS changes, the approximately one-year data gap between these missions and their relatively short 20-year data record limits our ability to study the continuous and long-term variability of YRB's TWS. In this study, two deep learning models are employed to bridge the data gap and reconstruct the historical TWS changes within YRB, respectively. For the data gap filling task, a noise-augmented u-shaped network (NA-UNet) is presented to address UNet's overfitting issues associated with training on limited GRACE observations. Results show that NA-UNet can accurately bridge the data gap, exhibiting favourable and stable performance at both the basin and grid scales. Subsequently, we introduce another deep learning model named RecNet, specifically designed to reconstruct the climate-driven TWS changes in YRB from 1923 to 2022. RecNet is trained on precipitation, temperature, and GRACE observations using a weighted mean square error (WMSE) loss function. We show that RecNet can successfully reconstruct the historical TWS changes, achieving strong correlations with GRACE, water budget estimates, hydrological models, drought indices, and existing reconstruction datasets. We also observe superior performance in RecNet when trained with WMSE compared to its non-weighted counterpart. In addition, the reconstructed datasets reveal a recurring occurrence of diverse hydrological extremes over the past century within YRB, influenced by major climate patterns. Together, NA-UNet and RecNet provide valuable observations for studying long-term climate variability and projecting future hydrological extremes in YRB, which can inform effective water resource management and contribute to the development of adaptive strategies for climate change.

How to cite: Wang, J., Shen, Y., Awange, J., Yang, L., and Chen, Q.: Reconstructing total water storage changes in the Yangtze River Basin based on deep learning models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3272, https://doi.org/10.5194/egusphere-egu24-3272, 2024.

EGU24-3307 | ECS | Posters virtual | ITS1.1/CL0.1.17

Comparative Study of Supervised Learning Algorithms on Rainfall Prediction using NEX-GDDP-CMIP6 Data 

Ratih Prasetya, Adhi Harmoko Saputro, Donaldi Sukma Permana, and Nelly Florida Riama

This study explores the transformative potential of supervised machine learning algorithms in improving rainfall prediction models for Indonesia. Leveraging the NEX-GDDP-CMIP6 dataset's high-resolution, global, and bias-corrected data, we compare various machine learning regression algorithms. Focusing on the EC Earth3 model, our approach involves an in-depth analysis of five weather variables closely tied to daily rainfall. We employed a diverse set of algorithms, including linear regression, K-nearest neighbor regression (KNN), random forest regression, decision tree regression, AdaBoost, extra tree regression, extreme gradient boosting regression (XGBoost), support vector regression (SVR), gradient boosting decision tree regression (GBDT), and multi-layer perceptron. Performance evaluation highlights the superior predictive capabilities of Gradient Boosting Decision Tree and KNN, achieving an impressive RMSE score of 0.04 and an accuracy score of 0.99. In contrast, XGBoost exhibits lower performance metrics, with an RMSE score of 5.1 and an accuracy score of 0.49, indicating poor rainfall prediction. This study contributes in advancing rainfall prediction models, hence emphasizing the improvement of methodological choices in harnessing machine learning for climate research.

How to cite: Prasetya, R., Harmoko Saputro, A., Sukma Permana, D., and Florida Riama, N.: Comparative Study of Supervised Learning Algorithms on Rainfall Prediction using NEX-GDDP-CMIP6 Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3307, https://doi.org/10.5194/egusphere-egu24-3307, 2024.

EGU24-3499 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

A Hybrid Machine Learning Climate Simulation Using High Resolution Convection Modelling 

James Briant, Dan Giles, Cyril Morcrette, and Serge Guillas

Underrepresentation of cloud formation is a known failing in current climate simulations. The coarse grid resolution required by the computational constraint of integrating over long time scales does not permit the inclusion of underlying cloud generating physical processes. This work employs a multi-output Gaussian Process (MOGP) trained on high resolution Unified Model (UM) simulation data to predict the variability of temperature and specific humidity fields within the climate model. A proof-of-concept study has been carried out where a trained MOGP model is coupled in-situ with a simplified Atmospheric General Circulation Model (AGCM) named SPEEDY. The temperature and specific humidity profiles of the SPEEDY model outputs are perturbed at each timestep according to the predicted high resolution informed variability. 10-year forecasts are generated for both default SPEEDY and ML-hybrid SPEEDY models and output fields are compared ensuring hybrid model predictions remain representative of Earth's atmosphere. Some changes in the precipitation, outgoing longwave and shortwave radiation patterns are observed indicating modelling improvements in the complex region surrounding India and the Indian sea.

How to cite: Briant, J., Giles, D., Morcrette, C., and Guillas, S.: A Hybrid Machine Learning Climate Simulation Using High Resolution Convection Modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3499, https://doi.org/10.5194/egusphere-egu24-3499, 2024.

EGU24-3614 | Orals | ITS1.1/CL0.1.17

From climate to weather reconstruction with inexpensive neural networks 

Martin Wegmann and Fernando Jaume-Santero

Understanding atmospheric variability is essential for adapting to future climate extremes. Key ways to do this are through analysing climate field reconstructions and reanalyses. However, producing such reconstructions can be limited by high production costs, unrealistic linearity assumptions, or uneven distribution of local climate records. 

Here, we present a machine learning-based non-linear climate variability reconstruction method using a Recurrent Neural Network that is able to learn from existing model outputs and reanalysis data. As a proof-of-concept, we reconstructed more than 400 years of global, monthly temperature anomalies based on sparse, realistically distributed pseudo-station data.

Our reconstructions show realistic temperature patterns and magnitude reproduction costing about 1 hour on a middle-class laptop. We highlight the method’s capability in terms of mean statistics compared to more established methods and find that it is also suited to reconstruct specific climate events. This approach can easily be adapted for a wide range of regions, periods and variables. As additional work-in-progress we show output of this approach for reconstructing European weather in 1807, including the extreme summer heatwave of that year.

How to cite: Wegmann, M. and Jaume-Santero, F.: From climate to weather reconstruction with inexpensive neural networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3614, https://doi.org/10.5194/egusphere-egu24-3614, 2024.

EGU24-3640 | ECS | Posters on site | ITS1.1/CL0.1.17

Exploiting Pseudo Wells in a Synthetic Sedimentary Basin: a simulation in the Santos Off-Shore Basin in the Southeast Atlantic portion of Brazil, using synthetic TOC for k-means classification. 

Victor Carreira, Milena Silva, Igor Venancio, André Belem, Igor Viegas, André Spigolon, Ana Luiza Albuquerque, and Pedro Vitor

Shales are important rocks that store a significant amount of Organic Content. In this work, we present applications of realistic synthetic simulations using real-scaled geological sections. The case of the study is Santos Sedimentary Basin, a well-known and well-studied Geologic Basin. This synthetic data improves the performance of our IA for TOC estimators. Besides, it reduces costs and resources concerning data acquisition for IA simulations. The work consists of reconstructing a pseudo-well formed in a fracture zone modelled through an accurate 2D geological section. To simulate the effects of a fracture zone on geophysical logging data, we present the law of mixtures based on well-drilling concepts, whose objective is to impose geometric conditions on the set of subsurface rock packages. We generated four rock packs belonging to two mixed classes. Tests with noisy synthetic data produced by an accurate geological section were developed and classified using the proposed method (Carreira et al., 2024). Firstly, we go for a more controlled problem and simulate well-log data directly from an interpreted geologic cross-section. We then define two specific training data sets composed of density (RHOB), sonic (DT), spontaneous potential (SP) and gamma-ray (GR) logs,  and  Total Organic Carbon (TOC), spontaneous potential (SP), density (RHOB) and photoelectric effect (PE) all simulated through a Gaussian distribution function per lithology. Acquiring the sonic profile is essential not only for estimating the porosity of the rocks but also for in-depth simulations of the Total Organic Content (TOC) with the geological units cut by the synthetic wells. Since most wells Exploitation does not have this profile well and it is not economically viable to make a new acquisition, resorting to the nonlinear regression models to estimate the sonic profile showed that it is an important feature. We estimate the observed Total Organic Carbon (TOC) measurements using Passey and Wang's (2016) methodology to input data into the k-means classification model. The synthetic model proposed showed promissory results indicating that linear dependency may underscore k-means shale classification. 

How to cite: Carreira, V., Silva, M., Venancio, I., Belem, A., Viegas, I., Spigolon, A., Albuquerque, A. L., and Vitor, P.: Exploiting Pseudo Wells in a Synthetic Sedimentary Basin: a simulation in the Santos Off-Shore Basin in the Southeast Atlantic portion of Brazil, using synthetic TOC for k-means classification., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3640, https://doi.org/10.5194/egusphere-egu24-3640, 2024.

EGU24-4460 | Orals | ITS1.1/CL0.1.17 | Highlight

Huge Ensembles of Weather Extremes using the Fourier Forecasting Neural Network 

William Collins, Michael Pritchard, Noah Brenowitz, Yair Cohen, Peter Harrington, Karthik Kashinath, Ankur Mahesh, and Shashank Subramanian

Studying low-likelihood high-impact extreme weather and climate events in a warming world requires massive
ensembles to capture long tails of multi-variate distributions. In combination, it is simply impossible to generate
massive ensembles, of say 10,000 members, using traditional numerical simulations of climate models at high
resolution. We describe how to bring the power of machine learning (ML) to replace traditional numerical
simulations for short week-long hindcasts of massive ensembles, where ML has proven to be successful in terms of
accuracy and fidelity, at five orders-of-magnitude lower computational cost than numerical methods. Because
the ensembles are reproducible to machine precision, ML also provides a data compression mechanism to
avoid storing the data produced from massive ensembles. The machine learning algorithm FourCastNet (FCN) is
based on Fourier Neural Operators and Transformers, proven to be efficient and powerful in modeling a wide
range of chaotic dynamical systems, including turbulent flows and atmospheric dynamics. FCN has already been
proven to be highly scalable on GPU-based HPC systems. 

We discuss our progress using statistics metrics for extremes adopted from operational NWP centers to show
that FCN is sufficiently accurate as an emulator of these phenomena. We also show how to construct huge
ensembles through a combination of perturbed-parameter techniques and a variant of bred vectors to generate a
large suite of initial conditions that maximize growth rates of ensemble spread. We demonstrate that these
ensembles exhibit a ratio of ensemble spread relative to RMSE that is nearly identical to one, a key metric of
successful near-term NWP systems. We conclude by applying FCN to severe heat waves in the recent climate
record.

How to cite: Collins, W., Pritchard, M., Brenowitz, N., Cohen, Y., Harrington, P., Kashinath, K., Mahesh, A., and Subramanian, S.: Huge Ensembles of Weather Extremes using the Fourier Forecasting Neural Network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4460, https://doi.org/10.5194/egusphere-egu24-4460, 2024.

As communities observe recurring regional weather patterns they will often ascribe colloquial names to them such as the Meiyu in East Asia or the Santa Ana winds of California. However, attaching quantitative characterizations to these same names often proves challenging. Classically heuristics have been developed for particular locations and climate phenomena, but their inherent subjectivity undermine the robustness of any subsequent quantitative analysis. To develop a neutral universal mesoscale metric we start by observing that the spatial distribution of rain in a given region is controlled by the interplay between the meteorological parameters (humidity, wind, pressure etc.) and the Earth’s topography. As a result, each recurring climactic phenomena exhibits a unique regional signature/distribution. Unlike at the synoptic scale, mesoscale climate patterns are largely stationary and an accumulation of two decades of high resolution satellite observations means that these patterns can now be reliably numerically extracted. The key additional observation is that at the mesoscale climate phenomena typically have either one or two non-co-occurring stationary states. This allows us to isolate patterns by a simple bifurcating of the subspace of the first two singular vectors. The end result behaves like a trivial Empirical Orthogonal Function (EOF) rotation that has a clear interpretation. It isolates the climate patterns as basis vectors and allows us to subsequently estimate the presence of the climate phenomena at arbitrary timescales. As a case study we use gridded precipitation data from NASA’s Global Precipitation Measurement (GPM) mission (compiled in to the IMERG dataset) in several regions and timescales of particular interest

How to cite: Kontsevich, G. and Löwemark, L.: Using IMERG precipitation patterns to index climate at the mesoscale: A basis rotation method based on climate bistability - an update, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4507, https://doi.org/10.5194/egusphere-egu24-4507, 2024.

EGU24-5033 | ECS | Posters on site | ITS1.1/CL0.1.17

Causal inference of the CO2 fertilisation effect from ecosystem flux measurements 

Samantha Biegel, Konrad Schindler, and Benjamin Stocker

Land ecosystems play an important role in the carbon cycle, and hence the climate system. The engine of this cycle is Gross Primary Production (GPP), the assimilation of CO2 via photosynthesis at the ecosystem scale. Photosynthesis is directly affected by rising CO2 levels which, in turn, is expected to increase GPP and alter the dynamics of the carbon cycle. However, there is substantial uncertainty about the magnitude and geographical variability of the CO2 fertilisation effect (CFE) on GPP.

We use a large collection of eddy covariance measurements (317 sites, 2226 site-years), paired with remotely sensed information of vegetation greenness to estimate the effect of rising CO2 levels on GPP. We propose a hybrid modelling architecture, combining a physically-grounded process model based on eco-evolutionary optimality theory and a deep learning model. The intuition is that the process model represents the current understanding of the CFE, whereas the deep learning model does not implement explicit physical relations but has a higher capacity to learn effects of large and fast variations in the light, temperature, and moisture environment. The hybrid model is set up to learn a correction on the theoretically expected CFE. This makes it more effective in distilling the relatively small and gradual CFE. 

Our study investigates inherent limitations of different models when it comes to drawing conclusions about the CO2 fertilisation effect. Often, these limitations are due to the presence of latent confounders that give rise to spurious correlations. A promising avenue to address them is therefore the use of causal inference techniques. We show that one way to investigate causality is to test whether the trained hybrid model and its estimate of the CFE is stable across different ecosystems, as expected for a causal physical relation. 

In summary, we study how causal inference, based on a combination of physics-informed and statistical modelling, can contribute to more reliable estimates of the CO2 fertilisation effect, derived from ecosystem flux measurements.

How to cite: Biegel, S., Schindler, K., and Stocker, B.: Causal inference of the CO2 fertilisation effect from ecosystem flux measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5033, https://doi.org/10.5194/egusphere-egu24-5033, 2024.

EGU24-5103 | ECS | Orals | ITS1.1/CL0.1.17

Reconstructing Historical Climate Fields With Deep Learning 

Nils Bochow, Anna Poltronieri, Martin Rypdal, and Niklas Boers

Historical records of climate fields are often sparse due to missing measurements, especially before the introduction of large-scale satellite missions. Several statistical and model-based methods have been introduced to fill gaps and reconstruct historical records. Here, we employ a recently introduced deep-learning approach based on Fourier convolutions, trained on numerical climate model output, to reconstruct historical climate fields. Using this approach we are able to realistically reconstruct large and irregular areas of missing data, as well as reconstruct known historical events such as strong El Niño and La Niña with very little given information. Our method outperforms the widely used statistical kriging method as well as other recent machine learning approaches. The model generalizes to higher resolutions than the ones it was trained on and can be used on a variety of climate fields. Moreover, it allows inpainting of masks never seen before during the model training.

How to cite: Bochow, N., Poltronieri, A., Rypdal, M., and Boers, N.: Reconstructing Historical Climate Fields With Deep Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5103, https://doi.org/10.5194/egusphere-egu24-5103, 2024.

EGU24-5611 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

Advances and Prospects of Deep Learning for Medium-Range Extreme Weather Forecasting 

Leonardo Olivetti and Gabriele Messori

In recent years, deep learning models have rapidly emerged as a standalone alternative to physics-based numerical models for medium-range weather forecasting. Several independent research groups claim to have developed deep learning weather forecasts which outperform those from state-of-the-art physics-basics models, and operational implementation of data-driven forecasts appears to be drawing near. Yet, questions remain about the capabilities of deep learning models to provide robust forecasts of extreme weather.

Our current work aims to provide an overview of recent developments in the field of deep learning weather forecasting, and highlight the challenges that extreme weather events pose to leading deep learning models. Specifically, we problematise the fact that predictions generated by many deep learning models appear to be oversmooth, tending to underestimate the magnitude of wind and temperature extremes. To address these challenges, we argue for the need to tailor data-driven models to forecast extreme events, and develop models aiming to maximise the skill in the tails rather than in the mean of the distribution. Lastly, we propose a foundational workflow to develop robust models for extreme weather, which may function as a blueprint for future research on the topic.

How to cite: Olivetti, L. and Messori, G.: Advances and Prospects of Deep Learning for Medium-Range Extreme Weather Forecasting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5611, https://doi.org/10.5194/egusphere-egu24-5611, 2024.

EGU24-5616 | ECS | Posters on site | ITS1.1/CL0.1.17

Rethinking Tropical Cyclone Genesis Potential Indices via Feature Selection 

Filippo Dainelli, Guido Ascenso, Enrico Scoccimarro, Matteo Giuliani, and Andrea Castelletti

Tropical Cyclones (TCs) are synoptic-scale, rapidly rotating storm systems primarily driven by air-sea heat and moisture exchanges. They are among the deadliest geophysical hazards, causing substantial economic losses and several fatalities due to their associated strong winds, heavy precipitation, and storm surges, leading to coastal and inland flooding. Because of the severe consequences of their impacts, accurately predicting the occurrence, intensity, and trajectory of TCs is of crucial socio-economic importance. Over the past few decades, advancements in Numerical Weather Prediction models, coupled with the availability of high-quality observational data from past events, have increased the accuracy of short-term forecasts of TC tracks and intensities. However, this level of improvement has not yet been mirrored in long-term climate predictions and projections. This can be attributed to the substantial computational resources required for running high-resolution climate models with numerous ensemble members over long periods. Additionally, the physical processes underlying TC formation are still poorly understood. To overcome these challenges, the future occurrence of TCs can instead be studied using indices, known as Genesis Potential Indices (GPIs), which correlate the likelihood of Tropical Cyclone Genesis (TCG) with large-scale environmental factors instrumental in their formation. GPIs are generally constructed as a product of atmospheric and oceanic variables accounting both for dynamic and thermodynamic processes. The variables are combined with coefficients and exponents numerically determined from past TC observations. Despite reproducing the spatial pattern and the seasonal cycle of observed TCs, GPIs fail to capture the inter-annual variability and exhibit inconsistent long-term trends.

In this work, we propose a new way to formulate these indices by using Machine Learning. Specifically, we forego all previously empirically determined coefficients and exponents and consider all the dynamic and thermodynamic factors incorporated into various indices documented in the literature. Then, using feature selection algorithms, we identify the most significant variables to explain TCG. Our analysis incorporates atmospheric variables as candidate factors to discern whether they inherently possess predictive signals for TCG. Furthermore, we also consider several climate indices that have been demonstrated to be related to TCG at the ocean basin scale. Recognizing that each factor and teleconnection has a distinct impact on TCG, we tailored our analysis to individual ocean basins. Consequently, our final model comprises a series of sub-models, each corresponding to a different tropical region. These sub-models estimate the distribution of TCG using distinct inputs, which are determined based on the outcomes of the basin-specific feature selection process. Preliminary findings indicate that the feature selection process yields distinct inputs for each ocean basin.

How to cite: Dainelli, F., Ascenso, G., Scoccimarro, E., Giuliani, M., and Castelletti, A.: Rethinking Tropical Cyclone Genesis Potential Indices via Feature Selection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5616, https://doi.org/10.5194/egusphere-egu24-5616, 2024.

In the context of global warming, changes in extreme weather events may pose a larger threat to society. Therefore, it is particularly important to improve our climatological understanding of high impact precipitation types (PTs), and how their frequency may change under warming. In this study, we use MIDAS (the Met Office Integrated Data Archive System) observational data to provide our best estimate of historical PTs (e.g. liquid rain, freezing rain, snow etc.) over China. We use machine learning (ML) techniques and meteorological analysis methods applied to data from the ERA5 historical climate reanalysis data to find the best variables for diagnosing PTs, and formed training and testing sets, which were input into ML training. We evaluate the diagnostic ability of the Random Forest Classifier (RFC) for different PTs. The results show that using meteorological variables such as temperature, relative humidity, and winds to determine different PTs, ERA5 grid data and MIDAS station data have good matching ability. Comparing the feature selection results with Kernel Density Estimation, it was found that the two methods have consistent results in evaluating the ability of variables to distinguish different PTs. RFC shows strong robustness in predicting different PTs by learning the differences in meteorological variables between 1990 and 2014. It can capture the frequency and spatial distribution of different PTs well, but this capture ability is sensitive to the training methods of the algorithm. In addition, the algorithm finds it difficult to identify events such as hail that are very low frequency in observations. According to the results of testing for different regions and seasons in China, models trained using seasonal data samples have relatively good performance, especially in winter. These results show the potential for combining a RFC with state-of-the-art climate models to effectively project the possible response of different PT frequencies to climate warming in the future. However, the training method of ML algorithm should be selected with caution.

How to cite: Wang, Y.: Identifying precipitation types over China using a machine learning algorithm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6282, https://doi.org/10.5194/egusphere-egu24-6282, 2024.

EGU24-6655 | ECS | Orals | ITS1.1/CL0.1.17

Detecting spatio-temporal dynamics of western European heatwaves using deep learning 

Tamara Happe, Jasper Wijnands, Miguel Ángel Fernández-Torres, Paolo Scussolini, Laura Muntjewerf, and Dim Coumou

Heatwaves over western Europe are increasing faster than elsewhere, which recent studies have attributed at least partly to changes in atmospheric dynamics. To increase our understanding of the dynamical drivers of western European heatwaves, we developed a heatwave classification method taking into account the spatio-temporal atmospheric dynamics. Our deep learning approach consists of several steps: 1) heatwave detection using the Generalized Density-based Spatial Clustering of Applications with Noise (GDBSCAN) algorithm; 2) dimensionality reduction of the spatio-temporal heatwave samples using a 3D Variational Autoencoder (VAE); and 3) a clustering of heatwaves using K-means, a Gaussian Mixture Model, and opt-SNE. We show that a VAE can extract meaningful features from high-dimensional climate data. Furthermore, we find four physically distinct clusters of heatwaves that are interpretable with known circulation patterns, i.e. UK High, Scandinavian High, Atlantic High, and Atlantic Low. Our results indicate that the heatwave phase space, as found with opt-SNE, is continuous with soft boundaries between these circulation regimes, indicating that heatwaves are best categorized in a probabilistic way.

How to cite: Happe, T., Wijnands, J., Fernández-Torres, M. Á., Scussolini, P., Muntjewerf, L., and Coumou, D.: Detecting spatio-temporal dynamics of western European heatwaves using deep learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6655, https://doi.org/10.5194/egusphere-egu24-6655, 2024.

The tropical Pacific experienced triple La Nina conditions during 2020-22, and the future evolution of the climate condition in the region has received extensive attention. Recent observations and studies indicate that an El Nino condition is developing with its peak stage in late 2023, but large uncertainties still exist. Here, a transformer-based deep learning model is adopted to make predictions of the 2023-24 climate condition in the tropical Pacific. This purely data driven model is configured in such a way that upper-ocean temperature at seven depths and zonal and meridional wind stress fields are used as input predictors and output predictands, representing ocean-atmosphere interactions that participate in the form of the Bjerknes feedback and providing physical basis for predictability. In the same way as dynamical models, the prediction procedure is executed in a rolling manner; multi-month 3D temperature fields as well as surface winds are simultaneously preconditioned as input predictors in the prediction. This transformer model has been demonstrated to outperform other state-of-the-art dynamical models in retrospective prediction cases. Real-time predictions indicate that El Nino conditions in the tropical Pacific peak in late 2023. The underlying processes are further analyzed by conducting sensitivity experiments using this transformer model, in which initial fields of surface winds and upper-ocean temperature fields can be purposely adjusted to illustrate the changes to prediction skills. A comparison with other dynamical coupled model is also made.

How to cite: Zhang, R.: A purely data-driven transformer model for real-time predictions of the 2023-24 climate condition in the tropical Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6924, https://doi.org/10.5194/egusphere-egu24-6924, 2024.

EGU24-8010 | ECS | Posters on site | ITS1.1/CL0.1.17

Statistical Downscaling for urban meteorology at hectometric scale 

Julia Garcia Cristobal, Jean Wurtz, and Valéry Masson

Predicting the weather in urban environments is a complex task because of the highly heterogeneous nature of the urban structure. However, there are many issues inherent in urban meteorology, such as thermal comfort and building’s energy consumption. Those stakes are linked to highly heterogeneous meteorological variables within the city such as temperature, humidity, wind, net radiative flux and city characteristics such as building uses and characteristics. State-of-the-art meteorological models with hectometric resolution, such as the Meso-NH (Lac et al. 2018) research model, can provide accurate forecasts of urban meteorology. However, they require too much computing power to be deployed operationally. Statistical downscaling techniques are machine learning methods enabling the estimation of a fine resolution field based on one or several lower resolution fields. ARPEGE is the operational planetary model of Météo-France and operates at a resolution of 5km on France. Using Meso-NH simulations covering Paris and the Île-de-France region, a statistical downscaling has been carried out to obtain a temperature field at 300m resolution using simulation outputs from the ARPEGE planetary model at 5km. The deduced temperature reproduces the urban heat island and the temperature heterogeneity simulated in Meso-NH. The estimated temperature field is able to represent the links between temperature and topography as well as the sharp gradients between the city and the urban parks.

 

Lac et al. 2018 : https://doi.org/10.5194/gmd-11-1929-2018

How to cite: Garcia Cristobal, J., Wurtz, J., and Masson, V.: Statistical Downscaling for urban meteorology at hectometric scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8010, https://doi.org/10.5194/egusphere-egu24-8010, 2024.

EGU24-8955 | ECS | Posters on site | ITS1.1/CL0.1.17

A Systematic Framework for Data Augmentation for Tropical Cyclone Intensity Estimation Using Deep Learning 

Guido Ascenso, Giulio Palcic, Enrico Scoccimarro, Matteo Giuliani, and Andrea Castelletti

Tropical cyclones (TCs) are among the costliest and deadliest natural disasters worldwide. The destructive potential of a TC is usually modelled as a power of its maximum sustained wind speed, making the estimation of the intensity of TCs (TCIE) an active area of research. Indeed, TCIE has improved steadily in recent years, especially as researchers moved from subjective methods based on hand-crafted features to methods based on deep learning, which are now solidly established as the state of the art.

However, the datasets used for TCIE, which are typically collections of satellite images of TCs, often have two major issues: they are relatively small (usually ≤ 40,000 samples), and they are highly imbalanced, with orders of magnitude more samples for weak TCs than for intense ones. Together, these issues make it hard for deep learning models to estimate the intensity of the strongest TCs. To mitigate these issues, researchers often use a family of Computer Vision techniques known as “data augmentation”—transformations (e.g., rotations) applied to the images in the dataset that create similar, synthetic samples. The way these techniques have been used in TCIE studies has been largely unexamined and potentially problematic. For instance, some authors flip images horizontally to generate new samples, while others avoid doing so because it would cause images from the Northern Hemisphere to look like images from the Southern Hemisphere, which they argue would confuse the model. The effectiveness or potentially detrimental effects of this and other data augmentation techniques for TCIE have never been examined, as authors typically borrow their data augmentation strategies from established fields of Computer Vision. However, data augmentation techniques are highly sensitive to the task for which they are used and should be optimized accordingly. Furthermore, it remains unclear how to properly use data augmentation for TCIE to alleviate the imbalance of the datasets.

In our work, we explore how best to perform data augmentation for TCIE using an off-the-shelf deep learning model, focusing on two objectives:

  • Determining how much augmentation is needed and how to distribute it across the various classes of TC intensity. To do so, we use a modified Gini coefficient to guide the amount of augmentation to be done. Specifically, we aim to augment the dataset more for more intense (and therefore less represented) TCs. Our goal is to obtain a dataset that, when binned according to the Saffir Simpson scale, is as close to a normal distribution as possible (i.e., all classes of intensity are equally represented). 
  • Evaluating which augmentation techniques are best for deep learning-based TCIE. To achieve this, we use a simple feature selection algorithm called backwards elimination, which leads us to find an optimal set of data augmentations to be used. Furthermore, we explore the optimal parameter space for each augmentation technique (e.g., by what angles images should be rotated).

Overall, our work provides the first in-depth analysis of the effects of data augmentation for deep learning-based TCIE, establishing a framework to use these techniques in a way that directly addresses highly imbalanced datasets.

How to cite: Ascenso, G., Palcic, G., Scoccimarro, E., Giuliani, M., and Castelletti, A.: A Systematic Framework for Data Augmentation for Tropical Cyclone Intensity Estimation Using Deep Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8955, https://doi.org/10.5194/egusphere-egu24-8955, 2024.

EGU24-9110 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

Explainable AI for distinguishing future climate change scenarios 

Zachary Labe, Thomas Delworth, Nathaniel Johnson, and William Cooke

To account for uncertainties in future projections associated with the level of greenhouse gas emissions, most climate models are run using different forcing scenarios, like the Shared Socioeconomic Pathways (SSPs). Although it is possible to compare real-world greenhouse gas concentrations with these hypothetical scenarios, it is less clear how to determine whether observed patterns of weather and climate anomalies align with individual scenarios, especially at the interannual timescale. As a result, this study designs a data-driven approach utilizing artificial neural networks (ANNs) that learn to classify global maps of annual-mean temperature or precipitation with a matching emission scenario using a high-resolution, single model initial-condition large ensemble. Here we construct our ANN framework to consider whether a climate map is from SSP1-1.9, SSP2-4.5, SSP5-8.5, a historical forcing scenario, or a natural forcing scenario using the Seamless System for Prediction and EArth System Research (SPEAR) by the NOAA Geophysical Fluid Dynamics Laboratory. A local attribution technique from explainable AI is then applied to identify the most relevant temperature and precipitation patterns used for each ANN prediction. The explainability results reveal that some of the most important geographic regions for distinguishing each climate scenario include anomalies over the subpolar North Atlantic, Central Africa, and East Asia. Lastly, we evaluate data from two overshoot simulations that begin in either 2031 or 2040, which are a set of future simulations that were excluded from the ANN training process. For the rapid mitigation experiment that starts a decade earlier, we find that the ANN links its climate maps to the lowest emission scenario by the end of the 21st century (SSP1-1.9) in comparison to the more moderate scenario (SSP2-4.5) that is selected for the later mitigation experiment. Overall, this framework suggests that explainable machine learning could provide one possible strategy for assessing observations with future climate change pathways.

How to cite: Labe, Z., Delworth, T., Johnson, N., and Cooke, W.: Explainable AI for distinguishing future climate change scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9110, https://doi.org/10.5194/egusphere-egu24-9110, 2024.

EGU24-10129 | ECS | Orals | ITS1.1/CL0.1.17

Subseasonal to seasonal forecasts using Masked Autoencoders 

Jannik Thümmel, Jakob Schlör, Felix Strnad, and Bedartha Goswami

Subseasonal to seasonal (S2S) weather forecasts play an important role as a decision making tool in several sectors of modern society. However, the time scale on which these forecasts are skillful is strongly dependent on atmospheric and oceanic background conditions. While deep learning-based weather prediction models have shown impressive results in the short- to medium range, S2S forecasts from such models are currently limited, partly due to fewer available training data and larger fluctuations in predictability. In order to develop more reliable S2S predictions we leverage Masked Autoencoders, a state-of-the-art deep learning framework, to extract large-scale representations of tropical precipitation and sea-surface temperature data.  We show that the learned representations are highly predictive for the El Niño Southern Oscillation and the Madden-Julian Oscillation, and can thus serve as a foundation for identifying windows of opportunity and generating skillful S2S forecasts.

How to cite: Thümmel, J., Schlör, J., Strnad, F., and Goswami, B.: Subseasonal to seasonal forecasts using Masked Autoencoders, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10129, https://doi.org/10.5194/egusphere-egu24-10129, 2024.

EGU24-10156 | Posters on site | ITS1.1/CL0.1.17

Heat wave vulnerability maps of Naples (Italy) from Landsat images and machine learning 

Daniela Flocco, Ester Piegari, and Nicola Scafetta

Maps of land surface temperature of the area of Naples (Southern Italy) show large spatial variation of temperature anomalies. In particular, the metropolitan area of Naples is generally characterized by higher temperatures than the rest of the area considered.

Since heat waves have become more frequent in the last decade, the creation of heat maps helps to understand the location where a town’s population may be more affected by them. Ideally, this kind of maps would provide residents with accurate information about the health problems they may face.

Large temperature anomalies variations are caused by multiple or competing factors, leaving uncertainty in identifying vulnerable areas at this time.

To overcome this limitation and identify areas more vulnerable to the effects of heat waves, not only in the city of Naples but also in its suburbs, we combine the use of Landsat data with unsupervised machine learning algorithms to provide detailed heat wave vulnerability maps. In particular, we develop a procedure based on a combined use of hierarchical and partitional cluster analyses that allows us to better identify areas characterized by temperature anomalies that are more similar to each other than to any other all over the year. This has important implications allowing discrimination between locations that potentially would be impacted higher or lower energy consumption.

How to cite: Flocco, D., Piegari, E., and Scafetta, N.: Heat wave vulnerability maps of Naples (Italy) from Landsat images and machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10156, https://doi.org/10.5194/egusphere-egu24-10156, 2024.

EGU24-10262 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

Machine learning-based emulation of a km-scale UK climate model 

Henry Addison, Elizabeth Kendon, Suman Ravuri, Laurence Aitchison, and Peter Watson

High resolution projections are useful for planning climate change adaptation [1] but are expensive to produce using physical simulations. We make use of a state-of-the-art generative machine learning (ML) method, a diffusion model [2], to predict variables from a km-scale model over England and Wales. This is trained to emulate daily mean output from the Met Office 2.2km UK convection-permitting model (CPM) [3], averaged to 8.8km scale for initial testing, given coarse-scale (60km) weather states from the Met Office HadGEM3 general circulation model. This achieves downscaling at much lower computational cost than is required to run the CPM and when trained to predict precipitation the emulator produces samples with realistic spatial structure [4, 5]. We show the emulator learns to represent climate change over the 21st century. We present some diagnostics indicating that there is skill for extreme events with ~100 year return periods, as is necessary to inform decision-making. This is made possible by training the model on ~500 years of CPM data (48 years from each of 12 ensemble members). We also show the method can be useful in scenarios with limited high-resolution data. The method is stochastic and we find that it produces a well-calibrated spread of high resolution precipitation samples for given large-scale conditions, which is highly important for correctly representing extreme events.

Furthermore, we are extending this method to generate coherent multivariate samples including other impact-relevant variables (e.g. 2m temperature, 2m humidity and 10m wind). We will show the model’s performance at producing samples with coherent structure across all the different variables and its ability to represent extremes in multivariate climate impact indices.

References

[1] Kendon, E. J. et al. (2021). Update to the UKCP Local (2.2km) projections. Science report, Met Office Hadley Centre, Exeter, UK. [Online]. Available: https://www.metoffice.gov.uk/pub/data/weather/uk/ukcp18/science-reports/ukcp18_local_update_report_2021.pdf

[2] Song, Y. et al. (2021). Score-Based Generative Modeling through Stochastic Differential Equations. ICLR.

[3] Kendon EJ, E Fischer, CJ Short (2023) Variability conceals emerging trend in 100yr projections of UK local hourly rainfall extremes, Nature Comms, doi: 10.1038/s41467-023-36499-9

[4] Addison, Henry, Elizabeth Kendon, Suman Ravuri, Laurence Aitchison, and Peter AG Watson. (2022). Machine learning emulation of a local-scale UK climate model. arXiv preprint arXiv:2211.16116.

[5] Addison, H., Kendon, E., Ravuri, S., Aitchison, L., and Watson, P. (2023). Downscaling with a machine learning-based emulator of a local-scale UK climate model, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14253, https://doi.org/10.5194/egusphere-egu23-14253

How to cite: Addison, H., Kendon, E., Ravuri, S., Aitchison, L., and Watson, P.: Machine learning-based emulation of a km-scale UK climate model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10262, https://doi.org/10.5194/egusphere-egu24-10262, 2024.

EGU24-10298 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

Downscaling precipitation simulations from Earth system models with generative deep learning 

Philipp Hess, Maximilian Gelbrecht, Michael Aich, Baoxiang Pan, Sebastian Bathiany, and Niklas Boers

Accurately assessing precipitation impacts due to anthropogenic global warming relies on numerical Earth system model (ESM) simulations. However, the discretized formulation of ESMs, where unresolved small-scale processes are included as semi-empirical parameterizations, can introduce systematic errors in the simulations. These can, for example, lead to an underestimation of spatial intermittency and extreme events.
 Generative deep learning has recently been shown to skillfully bias-correct and downscale precipitation fields from numerical simulations [1,2]. Using spatial context, these methods can jointly correct spatial patterns and summary statistics, outperforming established statistical approaches.
However, these approaches require separate training for each Earth system model individually, making corrections of large ESM ensembles computationally costly. Moreover, they only allow for limited control over the spatial scale at which biases are corrected and may suffer from training instabilities.
Here, we follow a novel diffusion-based generative approach [3, 4] by training an unconditional foundation model on the high-resolution target ERA5 dataset only. Using fully coupled ESM simulations of precipitation, we investigate the controllability of the generative process during inference to preserve spatial patterns of a given ESM field on different spatial scales.

[1] Hess, P., Drüke, M., Petri, S., Strnad, F. M., & Boers, N. (2022). Physically constrained generative adversarial networks for improving precipitation fields from Earth system models. Nature Machine Intelligence, 4(10), 828-839.

[2] Harris, L., McRae, A. T., Chantry, M., Dueben, P. D., & Palmer, T. N. (2022).A generative deep learning approach to stochastic downscaling of precipitation forecasts. Journal of Advances in Modeling Earth Systems, 14(10), e2022MS003120.

[3] Meng, C., He, Y., Song, Y., Song, J., Wu, J., Zhu, J. Y., & Ermon, S. (2021).  Sdedit: Guided image synthesis and editing with stochastic differential equations. arXiv preprint arXiv:2108.01073.

[4] Bischoff, T., & Deck, K. (2023). Unpaired Downscaling of Fluid Flows with Diffusion Bridges. arXiv preprint arXiv:2305.01822.

How to cite: Hess, P., Gelbrecht, M., Aich, M., Pan, B., Bathiany, S., and Boers, N.: Downscaling precipitation simulations from Earth system models with generative deep learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10298, https://doi.org/10.5194/egusphere-egu24-10298, 2024.

EGU24-10325 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

Interpretable multiscale Machine Learning-Based Parameterizations of Convection for ICON 

Helge Heuer, Mierk Schwabe, Pierre Gentine, Marco A. Giorgetta, and Veronika Eyring

In order to improve climate projections, machine learning (ML)-based parameterizations have been developed for Earth System Models (ESMs) with the goal to better represent subgrid-scale processes or to accelerate computations by emulating existent parameterizations. These data-driven models have shown success in approximating subgrid-scale processes based on high-resolution storm-resolving simulations. However, most studies have used a particular machine learning method such as simple Multilayer Perceptrons (MLPs) or Random Forest (RFs) to parameterize the subgrid tendencies or fluxes originating from the compound effect of various small-scale processes (e.g., turbulence, radiation, convection, gravity waves). Here, we use a filtering technique to explicitly separate convection from these processes in data produced by the Icosahedral Non-hydrostatic modelling framework (ICON) in a realistic setting. We use a method improved by incorporating density fluctuations for computing the subgrid fluxes and compare a variety of different machine learning algorithms on their ability to predict the subgrid fluxes. We further examine the predictions of the best performing non-deep learning model (Gradient Boosted Tree regression) and the U-Net. We discover that the U-Net can learn non-causal relations between convective precipitation and convective subgrid fluxes and develop an ablated model excluding precipitating tracer species. We connect the learned relations of the U-Net to physical processes in contrast to non-deep learning-based algorithms. Our results suggest that architectures such as a U-Net are particularly well suited to parameterize multiscale problems like convection, paying attention to the plausibility of the learned relations, thus providing a significant advance upon existing ML subgrid representation in ESMs.

How to cite: Heuer, H., Schwabe, M., Gentine, P., Giorgetta, M. A., and Eyring, V.: Interpretable multiscale Machine Learning-Based Parameterizations of Convection for ICON, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10325, https://doi.org/10.5194/egusphere-egu24-10325, 2024.

EGU24-10328 | ECS | Posters on site | ITS1.1/CL0.1.17 | Highlight

Emulating Land-Processes in Climate Models Using Generative Machine Learning 

Graham Clyne

Recent advances in climate model emulation have been shown to accurately represent atmospheric variables from large general circulation models, but little investigation has been done into emulating land-related variables. The land-carbon sink absorbs around a third of the fossil fuel anthropogenic emissions every year, yet there is significant uncertainty around this prediction. We aim to reduce this uncertainty by first investigating the predictability of several land-related variables that drive land-atmospheric carbon exchange. We use data from the IPSL-CM6A-LR submission to the Decadal Climate Prediction Project (DCPP). The DCPP is initialized from observed data and explores decadal trends in relationships between various climatic variables. The land-component of the IPSL-CM6A-LR, ORCHIDEE, represents various land-carbon interactions and we target these processes for emulation. As a first step, we attempt to predict the target land variables from ORCHIDEE using a vision transformer. We then investigate the impacts of different feature selection on the target variables - by including atmospheric and oceanic variables, how does this improve the short and medium term predictions of land-related processes? In a second step, we apply generative modeling (with diffusion models) to emulate land processes. The diffusion model can be used to generate several unseen scenarios based on the DCPP and provides a tool to investigate a wider range of climatic scenarios that would be otherwise computationally expensive. 

How to cite: Clyne, G.: Emulating Land-Processes in Climate Models Using Generative Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10328, https://doi.org/10.5194/egusphere-egu24-10328, 2024.

EGU24-10692 | ECS | Posters on site | ITS1.1/CL0.1.17

Down-scaling and bias correction of precipitation with generative machine learning models  

Michael Aich, Baoxiang Pan, Philipp Hess, Sebastian Bathiany, Yu Huang, and Niklas Boers

Earth system models (ESMs) are crucial for understanding and predicting the behaviour of the Earth’s climate system. Understanding and accurately simulating precipitation is particularly important for assessing the impacts of climate change, predicting extreme weather events, and developing sustainable strategies to manage water resources and mitigate associated risks. However, earth system models are prone to large precipitation biases because the relevant processes occur on a large range of scales and involve substantial uncertainties. In this work, we aim to correct such model biases by training generative machine learning models that map between model data and observational data. We address the challenge that the datasets are not paired, meaning that there is no sample-related ground truth to compare the model output to, due to the chaotic nature of geophysical flows. This challenge renders many machine learning approach unsuitable, and also implies a lack of performance metrics.

Our main contribution is the construction of a proxy variable that overcomes this problem and allows for supervised training and evaluation of a bias correction model. We show that a generative model is then able to correct spatial patterns and remove statistical biases in the South American domain. The approach successfully preserves large scale structures in the climate model fields while correcting small scale biases in the model data’s spatio-temporal structure and frequency distribution.

How to cite: Aich, M., Pan, B., Hess, P., Bathiany, S., Huang, Y., and Boers, N.: Down-scaling and bias correction of precipitation with generative machine learning models , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10692, https://doi.org/10.5194/egusphere-egu24-10692, 2024.

EGU24-10759 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

Is linear regression all you need? Clarifying use-cases for deep learning in climate emulation 

Björn Lütjens, Noelle Selin, Andre Souza, Gosha Geogdzhayev, Dava Newman, Paolo Giani, Claudia Tebaldi, Duncan Watson-Parris, and Raffaele Ferrari

Motivation. Climate models are computationally so expensive that each model is only run for a very selected set of assumptions. In policy making, this computational complexity makes it difficult to rapidly explore the comparative impact of climate policies, such as quantifying the projected difference of local climate impacts with a 30 vs. 45€ price on carbon (Lütjens et al., 2023). Recently however, machine learning (ML) models have been used to emulate climate models that can rapidly interpolate within existing climate dataset.

Related Works. Several deep learning models have been developed to emulate the impact of greenhouse gas emissions onto climate variables such as temperature and precipitation. Currently, the foundation model ClimaX with O(100M-1B) parameters is considered the best performer according to the benchmark datasets, ClimateSet and ClimateBenchv1.0 (Kaltenborn et al., 2023; Nguyen et al., 2023; Watson-Parris et al., 2022).

Results. We show that linear pattern scaling, a simple method with O(10K) parameters, is at least on par with the best models for some climate variables, as shown in Fig 1. In particular, the ClimateBenchv1.0 annually-averaged and locally-resolved surface temperatures, precipitation, and 90th percentile precipitation can be well estimated with linear pattern scaling. Our research resurfaces that temperature-dependent climate variables have a mostly linear relationship to cumulative CO2 emissions.

As a next step, we will identify the complex climate emulation tasks that are not addressed by linear models and might benefit from deep learning research. To do so, we will plot the data complexity per climate variable and discuss the ML difficulties in multiple spatiotemporal scales, irreversible dynamics, and internal variability. We will conclude with a list of tasks that demand more advanced ML models.

Conclusion. Most of the ML-based climate emulation efforts have focused on variables that can be well approximated by linear regression models. Our study reveals the solved and unsolved problems in climate emulation and provides guidance for future research directions.

Data and Methods. We use the ClimateBenchv1.0 dataset and will show additional results on ClimateSet and a CMIP climate model that contains many ensemble members. Our model fits one linear regression to map cumulative CO2 emissions, co2(t), to globally- and annually-averaged surface temperature, tas(t). Our model then fits one linear regression model per grid cell to map tas(t) onto 2.5° local surface temperature. Our model is time-independent and uses only co2(t) as input. Our analysis will be available at github.com/blutjens/climate-emulator-tutorial

References.

Kaltenborn, J. et al., (2023). ClimateSet: A Large-Scale Climate Model Dataset for Machine Learning, in NeurIPS Datasets and Benchmarks

Lütjens, B. (2023). Deep Learning Emulators for Accessible Climate Projections, Thesis, Massachusetts Institute of Technology.

Nguyen, T. et al., (2023). ClimaX: A foundation model for weather and climate, in ICML

Watson-Parris, D. et al. (2022). ClimateBenchv1.0: A Benchmark for Data-Driven Climate Projections, in JAMES

How to cite: Lütjens, B., Selin, N., Souza, A., Geogdzhayev, G., Newman, D., Giani, P., Tebaldi, C., Watson-Parris, D., and Ferrari, R.: Is linear regression all you need? Clarifying use-cases for deep learning in climate emulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10759, https://doi.org/10.5194/egusphere-egu24-10759, 2024.

EGU24-10876 | ECS | Posters on site | ITS1.1/CL0.1.17 | Highlight

Physics-aware Machine Learning to Estimate Ice Thickness of Glaciers in West Svalbard 

Viola Steidl, Jonathan Bamber, and Xiao Xiang Zhu

Glacier ice thickness is a fundamental variable required for modelling flow and mass balance. However, direct measurements of ice thickness are scarce. Physics-based and data-driven approaches aim to reconstruct glacier ice thicknesses from the limited in-situ data. Farinotti et al. compared 17 models and found that their ice thickness estimates differ considerably on test glaciers.[1] Following these results, Farinotti et al. created an ensemble of models to develop the so-called consensus estimate of the ice thickness for the world’s glaciers in 2019.[2] Later, Millan et al. derived ice thickness estimates for the world’s glaciers using ice motion as the primary constraint. However, these results differ considerably from existing estimates and the 2019 consensus estimates.[3] It is evident, therefore, that significant uncertainty remains in ice thickness estimates.

Deep learning approaches are flexible and adapt well to complex structures and non-linear behaviour. However, they do not guarantee physical correctness of the predicted quantities. Therefore, we employ a physics-informed neural network (PINN), which integrates physical laws into their training process and is not purely data-driven. We include, for example, the conservation of mass in the loss function and estimate the depth-averaged flow velocity. Teisberg et al. also employed a mass-conserving PINN to interpolate the ice thickness of the well-studied Byrd glacier in Antarctica.[4] In this work, we extend the methodology by integrating the ratio between slope and surface flow velocities in estimating the depth-averaged flow velocity and mapping the coordinate variables to higher dimensional Fourier Features.[5] This allows to encompass glaciers in western Svalbard, addressing challenges posed by basal sliding, surface melting, and complex glacier geometries. Using surface velocity data from Millan et al. and topographical data from Copernicus DEM GLO-90[6] gathered through OGGM[7],  the model predicts ice thickness on glaciers with limited measurements. We are extending it to perform as a predictor of thickness for glaciers with no observations. Here, we present the machine learning pipeline, including the physical constraints employed and preliminary results for glaciers in western Svalbard.


[1] Daniel Farinotti et al., ‘How Accurate Are Estimates of Glacier Ice Thickness? Results from ITMIX, the Ice Thickness Models Intercomparison eXperiment’, The Cryosphere 11, no. 2 (April 2017): 949–70, https://doi.org/10.5194/tc-11-949-2017.

[2] Daniel Farinotti et al., ‘A Consensus Estimate for the Ice Thickness Distribution of All Glaciers on Earth’, Nature Geoscience 12, no. 3 (March 2019): 168–73, https://doi.org/10.1038/s41561-019-0300-3.

[3] Romain Millan et al., ‘Ice Velocity and Thickness of the World’s Glaciers’, Nature Geoscience 15, no. 2 (February 2022): 124–29, https://doi.org/10.1038/s41561-021-00885-z.

[4] Thomas O. Teisberg, Dustin M. Schroeder, and Emma J. MacKie, ‘A Machine Learning Approach to Mass-Conserving Ice Thickness Interpolation’, in 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021, 8664–67, https://doi.org/10.1109/IGARSS47720.2021.9555002.

[5] Matthew Tancik et al., ‘Fourier Features Let Networks Learn High Frequency Functions in Low Dimensional Domains’, (arXiv, 18 June 2020), https://doi.org/10.48550/arXiv.2006.10739.

[6] {https://doi.org/10.5270/ESA-c5d3d65}

[7] Fabien Maussion et al., ‘The Open Global Glacier Model (OGGM) v1.1’, Geoscientific Model Development 12, no. 3 (March 2019): 909–31, https://doi.org/10.5194/gmd-12-909-2019.

How to cite: Steidl, V., Bamber, J., and Zhu, X. X.: Physics-aware Machine Learning to Estimate Ice Thickness of Glaciers in West Svalbard, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10876, https://doi.org/10.5194/egusphere-egu24-10876, 2024.

EGU24-10922 | ECS | Orals | ITS1.1/CL0.1.17

Graph Neural Networks for Atmospheric Transport Modeling of CO2  

Vitus Benson, Ana Bastos, Christian Reimers, Alexander J. Winkler, Fanny Yang, and Markus Reichstein

Large deep neural network emulators are poised to revolutionize numerical weather prediction (NWP). Recent models like GraphCast or NeuralGCM can now compete and sometimes outperform traditional NWP systems, all at much lower computational cost. Yet to be explored is the applicability of large deep neural network emulators to other dense prediction tasks such as the modeling of 3D atmospheric composition. For instance the inverse modeling of carbon fluxes essential for estimating carbon budgets relies on fast CO2 transport models.

Here, we present a novel approach to atmospheric transport modeling of CO2 and other inert trace gases. Existing Eulerian transport modeling approaches rely on numerical solvers applied to the continuity equation, which are expensive: short time steps are required for numerical stability at the poles, and the loading of driving meteorological fields is IO-intensive. We learn high-fidelity transport in latent space by training graph neural networks, analogous to approaches used in weather forecasting, including an approach that conserves the CO2 mass. For this, we prepare the CarbonBench dataset, a deep learning ready dataset based on Jena Carboscope CO2 inversion data and NCEP NCAR meteorological reanalysis data together with ObsPack station observations for model evaluation.

Qualitative and quantitative experiments demonstrate the superior performance of our approach over a baseline U-Net for short-term (<40 days) atmospheric transport modeling of carbon dioxide. While the original GraphCast architecture achieves a similar speed to the TM3 transport model used to generate the training data, we show how various architectural changes introduced by us contribute to a reduced IO load (>4x) of our model, thereby speeding up forward runs. This is especially useful when applied multiple times with the same driving wind fields, e.g. in an inverse modeling framework. Thus, we pave the way towards integrating not only atmospheric observations (as is done in current CO2 inversions), but also ecosystem surface fluxes (not yet done) into carbon cycle inversions. The latter requires backpropagating through a transport operator to optimize a flux model with many more parameters (e.g. a deep neural network) than those currently used in CO2 inversions – which becomes feasible if the transport operator is fast enough. To the best of our knowledge, this work presents the first emulator of global Eulerian atmospheric transport, thereby providing an initial step towards next-gen inverse modeling of the carbon cycle with deep learning.

 

How to cite: Benson, V., Bastos, A., Reimers, C., Winkler, A. J., Yang, F., and Reichstein, M.: Graph Neural Networks for Atmospheric Transport Modeling of CO2 , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10922, https://doi.org/10.5194/egusphere-egu24-10922, 2024.

EGU24-11831 | ECS | Orals | ITS1.1/CL0.1.17

Analyzing Climate Scenarios Using Dynamic Mode Decomposition With Control 

Nathan Mankovich, Shahine Bouabid, and Gustau Camps-Valls

Analyzing climate scenarios is crucial for quantifying uncertainties, identifying trends, and validating models. Objective statistical methods provide decision support for policymakers, optimize resource allocation, and enhance our understanding of complex climate dynamics. These tools offer a systematic and quantitative framework for effective decision-making and policy formulation amid climate change, including accurate projections of extreme events—a fundamental requirement for Earth system modeling and actionable future predictions. 

This study applies dynamic mode decomposition with control (DMDc) to assess temperature and precipitation variability in climate model projections under various future shared socioeconomic pathways (SSPs). We leverage global greenhouse gas emissions and local aerosol emissions as control parameters to unveil nuanced insights into climate dynamics.Our approach involves fitting distinct DMDc models over a high-ambition/low-forcing scenario (SSP126), a medium-forcing scenario (SSP245) and a high-forcing scenario (SSP585). By scrutinizing the eigenvalues and dynamic modes of each DMDc model, we uncover crucial patterns and trends that extend beyond traditional climate analysis methods. Preliminary findings reveal that temporal modes effectively highlight variations in global warming trends under different emissions scenarios. Moreover, the spatial modes generated by DMDc offer a refined understanding of temperature disparities across latitudes, effectively capturing large-scale oscillations such as the El Niño Southern Oscillation. 

The proposed data-driven analytical framework not only enriches our comprehension of climate dynamics but also enhances our ability to anticipate and adapt to the multifaceted impacts of climate change. Integrating DMDc into climate scenario analysis may help formulate more effective strategies for mitigation and adaptation.

References

Allen, Myles R., et al. "Warming caused by cumulative carbon emissions towards the trillionth tonne." Nature 458.7242 (2009): 1163-1166.

Zelinka, Mark D., et al. "Causes of higher climate sensitivity in CMIP6 models." Geophysical Research Letters 47.1 (2020): e2019GL085782.

Proctor, Joshua L., Steven L. Brunton, and J. Nathan Kutz. "Dynamic mode decomposition with control." SIAM Journal on Applied Dynamical Systems 15.1 (2016): 142-161.

How to cite: Mankovich, N., Bouabid, S., and Camps-Valls, G.: Analyzing Climate Scenarios Using Dynamic Mode Decomposition With Control, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11831, https://doi.org/10.5194/egusphere-egu24-11831, 2024.

This study focuses on the application of machine learning techniques to better characterize predictability of the spatiotemporal variability of sea surface temperature (SST) on the basin scale. Both, sub-seasonal variability including extreme events (cf. marine heatwaves) and interannual variability are considered. 

We rely on dimensionality reduction techniques---linear principal component analysis (PCA)  and nonlinear autoencoders and their variants---to then perform the actual prediction tasks in the corresponding latent space using disparate methodologies ranging from linear inverse modeling (LIM) to reservoir computing (RC), and attention-based transformers. 

After comparing performance, we examine various issues including the role of generalized synchronization in RC and implicit memory of RC vs. explicit long-term memory of transformers with the broad aim of shedding light on the effectiveness of these techniques in the context of data-driven climate prediction.

How to cite: Nadiga, B. and Srinivasan, K.: Climate Prediction in Reduced Dimensions: A Comparative Analysis of Linear Inverse Modeling, Reservoir Computing and Attention-based Transformers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12141, https://doi.org/10.5194/egusphere-egu24-12141, 2024.

EGU24-12495 | Orals | ITS1.1/CL0.1.17

Hybrid neural differential equation models for atmospheric dynamics 

Maximilian Gelbrecht and Niklas Boers

Combining process-based models in Earth system science with data-driven machine learning methods holds tremendous promise. Can we harness the best of both approaches? In our study, we integrate components of atmospheric models into artificial neural networks (ANN). The resulting hybrid atmospheric model can learn atmospheric dynamics from short trajectories while ensuring robust generalization and stability. We achieve this using the neural differential equations framework, combining ANNs with a differentiable, GPU-enabled version of the well-studied Marshall Molteni Quasigeostrophic Model (QG3). Similar to the approach of many atmospheric models, part of the model is computed in the spherical harmonics domain, and other parts in the grid domain. In our model, ANNs are used as parametrizations in both domains, and form together with the components of the QG3 model the right-hand side of our hybrid model. We showcase the capabilities of our model by demonstrating how it generalizes from the QG3 model to the significantly more complex primitive equation model of SpeedyWeather.jl. 

How to cite: Gelbrecht, M. and Boers, N.: Hybrid neural differential equation models for atmospheric dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12495, https://doi.org/10.5194/egusphere-egu24-12495, 2024.

EGU24-12600 | Posters on site | ITS1.1/CL0.1.17

Autoencoder-based model for improving  reconstruction of heat waves using the analogue method 

Jorge Pérez-Aracil, Cosmin M. Marina, Pedro Gutiérrez, David Barriopedro, Ricardo García-Herrera, Matteo Giuliani, Ronan McAdam, Enrico Scoccimarro, Eduardo Zorita, Andrea Castelletti, and Sancho Salcedo-Sanz

The Analogue Method (AM) is a classical statistical downscaling technique applied to field reconstruction. It is widely used for prediction and attribution tasks. The method is based on the principle that two similar atmospheric states cause similar local effects. The core of the AM method is a K-nearest neighbor methodology. Thus, two different states have similarities according to the analogy criterion. The method has remained unchanged since its definition, although some attempts have been made to improve its performance. Machine learning (ML) techniques have recently been used to improve AM performance, however, it remains very similar. An ML-based hybrid approach for heatwave (HW) analysis based on the AM is presented here. It is based on a two-step procedure: in the first step, a non-supervised task is developed, where an autoencoder (AE) model is trained to reconstruct the predictor variable, i.e. the pressure field. Second, an HW event is selected, and then the AM method is applied to the latent space of the trained AE. Thus, the analogy between the fields is searched in the encoded data of the input variable, instead of on the original field. Experiments show that the meaningful features extracted by the AE lead to a better reconstruction of the target field when pressure variables are used as input. In addition, the analysis of the latent space allows for interpreting the results, since HW occurrence can be easily distinguished. Further research can be done on including multiple input variables. 

How to cite: Pérez-Aracil, J., Marina, C. M., Gutiérrez, P., Barriopedro, D., García-Herrera, R., Giuliani, M., McAdam, R., Scoccimarro, E., Zorita, E., Castelletti, A., and Salcedo-Sanz, S.: Autoencoder-based model for improving  reconstruction of heat waves using the analogue method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12600, https://doi.org/10.5194/egusphere-egu24-12600, 2024.

EGU24-12826 | ECS | Orals | ITS1.1/CL0.1.17

Comparing Machine Learning Methods for Dynamical Systems 

Christof Schötz, Alistair White, and Niklas Boers

We explore the task of learning the dynamics of a system from observed data without prior knowledge of the laws governing the system. Our extensive simulation study focuses on ordinary differential equation (ODE) problems that are specifically designed to reflect key aspects of various machine learning tasks for dynamical systems - namely, chaos, complexity, measurement uncertainty, and variability in measurement intervals. The study evaluates a variety of methods, including neural ODEs, transformers, Gaussian processes, echo state networks, and spline-based estimators. Our results show that the relative performance of the methods tested varies widely depending on the specific task, highlighting that no single method is universally superior. Although our research is predominantly in low-dimensional settings, in contrast to the high-dimensional nature of many climate science challenges, it provides insightful comparisons and understanding of how different approaches perform in learning the dynamics of complex systems.

How to cite: Schötz, C., White, A., and Boers, N.: Comparing Machine Learning Methods for Dynamical Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12826, https://doi.org/10.5194/egusphere-egu24-12826, 2024.

EGU24-13138 | ECS | Posters on site | ITS1.1/CL0.1.17

Neural Network Driven Early Warning System for Groundwater Flooding: A Comprehensive Approach in Lowland Karst Areas 

Ruhhee Tabbussum, Bidroha Basu, and Laurence Gill

Enhancing flood prediction is imperative given the profound socio-economic impacts of flooding and the projected increase in its frequency due to the impacts of climate change. In this context, artificial intelligence (AI) models have emerged as valuable tools, offering enhanced accuracy and cost-effective solutions to simulate physical flood processes. This study addresses the development of an early warning system for groundwater flooding in the lowland karst area of south Galway, Ireland, employing neural network models with Bayesian regularization and scaled conjugate gradient training algorithms. The lowland karst area is characterised by several groundwater fed, intermittent lakes, known as turloughs that fill when the underlying karst system becomes surcharged during periods of high rainfall. The training datasets incorporate several years of field data from the study area and outputs from a highly calibrated semi-distributed hydraulic/hydrological model of the karst network. Inputs for training the models include flood volume data from the past 5 days, rainfall data, and tidal amplitude data over the preceding 4 days. Both daily and hourly models were developed to facilitate real-time flood predictions. Results indicate strong performance by both Bayesian and Scaled Conjugate Gradient models in real-time flood forecasting. The Bayesian model shows forecasting capabilities extending up to 45 days into the future, with a Nash-Sutcliffe Efficiency (NSE) of 1.00 up to 7 days ahead and 0.95 for predictions up to 45 days ahead. The Scaled Conjugate Gradient model offers the best performance up to 60 days into the future with NSE of 0.98 up to 20 days ahead and 0.95 for predictions up to 60 days ahead, coupled with the advantage of significantly reduced training time compared to the Bayesian model. Additionally, both models exhibit a Co-efficient of Correlation (r) value of 0.98 up to 60 days ahead. Evaluation measures such as Kling Gupta Efficiency reveal high performance, with values of 0.96 up to 15 days ahead for both Bayesian and Scaled Conjugate Gradient models, and 0.90 up to 45 days ahead in the future. The integration of diverse data sources and consideration of both daily and hourly models enhance the resilience and reliability of such an early warning system. In particular, the Scaled Conjugate Gradient model emerges as a versatile tool. It balances predictive accuracy with reduced computational demands, thereby offering practical insights for real-time flood prediction, and aiding in proactive flood management and response efforts.

How to cite: Tabbussum, R., Basu, B., and Gill, L.: Neural Network Driven Early Warning System for Groundwater Flooding: A Comprehensive Approach in Lowland Karst Areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13138, https://doi.org/10.5194/egusphere-egu24-13138, 2024.

EGU24-15144 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

A Graph Neural Network emulator for greenhouse gas emissions inference 

Elena Fillola, Raul Santos-Rodriguez, and Matt Rigby

Inverse modelling systems relying on Lagrangian Particle Dispersion Models (LPDMs) are a popular way to quantify greenhouse gas emissions using atmospheric observations, providing independent evaluation of countries' self-reported emissions. For each GHG measurement, the LPDM performs backward-running simulations of particle transport in the atmosphere, calculating source-receptor relationships (“footprints”). These reflect the upwind areas where emissions would contribute to the measurement. However, the increased volume of satellite measurements from high-resolution instruments like TROPOMI cause computational bottlenecks, limiting the amount of data that can be processed for inference. Previous approaches to speed up footprint generation revolve around interpolation, therefore still requiring expensive new runs. In this work, we present the first machine learning-driven LPDM emulator that once trained, can approximate satellite footprints using only meteorology and topography. The emulator uses Graph Neural Networks in an Encode-Process-Decode structure, similar to Google’s Graphcast [1], representing latitude-longitude coordinates as nodes in a graph. We apply the model for GOSAT measurements over Brazil to emulate footprints produced by the UK Met Office’s NAME LPDM, training on data for 2014 and 2015 on a domain of size approximately 1600x1200km at a resolution of 0.352x0.234 degrees. Once trained, the emulator can produce footprints for a domain of up to approximately 6500x5000km, leveraging the flexibility of GNNs. We evaluate the emulator for footprints produced across 2016 on the 6500x5000km domain size, achieving intersection-over-union scores of over 40% and normalised mean absolute errors of under 30% for simulated CH4 concentrations. As well as demonstrating the emulator as a standalone AI application, we show how to integrate it with the full GHG emissions pipeline to quantify Brazil’s emissions. This method demonstrates the potential of GNNs for atmospheric dispersion applications and paves the way for large-scale near-real time emissions emulation.

 [1] Remi Lam et al.,Learning skillful medium-range global weather forecasting. Science 382,1416-1421 (2023). DOI:10.1126/science.adi2336

How to cite: Fillola, E., Santos-Rodriguez, R., and Rigby, M.: A Graph Neural Network emulator for greenhouse gas emissions inference, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15144, https://doi.org/10.5194/egusphere-egu24-15144, 2024.

EGU24-15174 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

Using spatio-temporal neural networks to investigating teleconnections and enhance S2S forecasts of european extreme weather  

Philine L. Bommer, Marlene Kretschmer, Paul Boehnke, and Marina M.-C. Hoehne née Vidovic

Decision making and efficient early warning systems for extreme weather rely on subseasonal-to-seasonal (S2S) forecasts. However, the chaotic nature of the atmosphere impedes predictions by dynamical forecast systems on the S2S time scale. Improved predictability may arise due to remote drivers and corresponding teleconnections in so-called windows of opportunities, but using knowledge of such drivers to boost S2S forecast skill is challenging. Here, we present a spatio-temporal deep neural network (DNN), predicting a time series of weekly North Atlantic European (NAE) weather regimes on lead-times of one to six weeks during boreal winter. The spatio-temporal architecture combines a convolutional Long-short-term-memory (convLSTM) encoder with an Long-short-term-memory (LSTM) decoder and was built to consider both short and medium-range variability as information. As predictors it uses 2D (image) time series input data of expected drivers of European winter weather, including the stratospheric polar vortex  and tropical sea surface temperatures, alongside the 1D time series of NAE regimes. Our results indicate that additional information provided in the image time series yield a skill score improvement for longer lead times. In addition, by analysing periods of enhanced or decreased predictability of the DNN, we can infer further information regarding prevalent teleconnections.

How to cite: Bommer, P. L., Kretschmer, M., Boehnke, P., and Hoehne née Vidovic, M. M.-C.: Using spatio-temporal neural networks to investigating teleconnections and enhance S2S forecasts of european extreme weather , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15174, https://doi.org/10.5194/egusphere-egu24-15174, 2024.

EGU24-15586 | ECS | Posters on site | ITS1.1/CL0.1.17 | Highlight

Identifying Windows of Opportunity in Deep Learning Weather Models 

Daniel Banciu, Jannik Thuemmel, and Bedartha Goswami

Deep learning-based weather prediction models have gained popularity in recent years and are effective in forecasting weather over short to medium time scales with models such as FourCastNet being competitive with Numerical Weather Prediction models. 
However, on longer timescales, the complexity and interplay of different weather and climate variables leads to increasingly inaccurate predictions. 

Large-scale climate phenomena, such as the active periods of the Madden-Julian Oscillation (MJO), are known to provide higher predictability for longer forecast times.
These so called Windows of Opportunity thus hold promise as strategic tools for enhancing S2S forecasts.

In this work, we evaluate the capability of FourCastNet to represent and utilize the presence of (active) MJO phases.
First, we analyze the correlation between the feature space of FourCastNet and different MJO indices.
We further conduct a comparative analysis of prediction accuracy within the South East Asia region during active and inactive MJO phases.

How to cite: Banciu, D., Thuemmel, J., and Goswami, B.: Identifying Windows of Opportunity in Deep Learning Weather Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15586, https://doi.org/10.5194/egusphere-egu24-15586, 2024.

EGU24-16513 | ECS | Orals | ITS1.1/CL0.1.17

Hybrid Modelling: Bridging Neural Networks and Physics-Based Approaches in Terrestrial Biogeochemical Ecosystems 

Lazaro Alonso, Sujan Koirala, Nuno Carvalhais, Fabian Gans, Bernhard Ahrens, Felix Cremer, Thomas Wutzler, Mohammed Ayoub Chettouh, and Markus Reichstein

The application of automatic differentiation and deep learning approaches to tackle current challenges is now a widespread practice. The biogeosciences community is no stranger to this trend; however, quite often, previously known physical model abstractions are discarded.

In this study, we model the ecosystem dynamics of vegetation, water, and carbon cycles adopting a hybrid approach. This methodology involves preserving the physical model representations for simulating the targeted processes while utilizing neural networks to learn the spatial variability of their parameters. These models have historically posed challenges due to their complex process representations, varied spatial scales, and parametrizations.

We show that a hybrid approach effectively predicts model parameters with a single neural network, compared with the site-level optimized set of parameters. This approach demonstrates its capability to generate predictions consistent with in-situ parameter calibrations across various spatial locations, showcasing its versatility and reliability in modelling coupled systems.
Here, the physics-based process models undergo evaluation across several FLUXNET sites. Various observations—such as gross primary productivity, net ecosystem exchange, evapotranspiration, transpiration, the normalized difference vegetation index, above-ground biomass, and ecosystem respiration—are utilized as targets to assess the model's performance. Simultaneously, a neural network (NN) is trained to predict the model parameters, using input features(to the NN) such as plant functional types, climate types, bioclimatic variables, atmospheric nitrogen and phosphorus deposition, and soil properties. The model simulation is executed within our internal framework Sindbad.jl (to be open-sourced), designed to ensure compatibility with gradient-based optimization methods.

This work serves as a stepping stone, demonstrating that incorporating neural networks into a broad collection of physics-based models holds significant promise and has the potential to leverage the abundance of current Earth observations, enabling the application of these methods on a larger scale.

How to cite: Alonso, L., Koirala, S., Carvalhais, N., Gans, F., Ahrens, B., Cremer, F., Wutzler, T., Ayoub Chettouh, M., and Reichstein, M.: Hybrid Modelling: Bridging Neural Networks and Physics-Based Approaches in Terrestrial Biogeochemical Ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16513, https://doi.org/10.5194/egusphere-egu24-16513, 2024.

EGU24-17165 | ECS | Posters on site | ITS1.1/CL0.1.17

Conditioning Deep Learning Weather Prediction Models On Exogenous Fields 

Sebastian Hoffmann, Jannik Thümmel, and Bedartha Goswami

Deep learning weather prediction (DLWP) models have recently proven to be a viable alternative to classical numerical integration. Often, the skill of these models can be improved further by providing additional exogenous fields such as time of day, orography, or sea surface temperatures stemming from an independent ocean model. These merely serve as information sources and are not predicted by the model.

In this study, we explore how such exogenous fields can be utilized by DLWP models most optimally and find that the de facto standard way of concatenating them to the input is suboptimal. Instead, we suggest leveraging existing conditioning techniques from the broader deep learning community that modulate the mean and variance of normalized feature vectors in latent space. These, so called, style-based techniques lead to consistently smaller forecast errors and, at the same time, can be integrated with relative ease into existing forecasting architectures. This makes them an attractive avenue to improve deep learning weather prediction in the future.

How to cite: Hoffmann, S., Thümmel, J., and Goswami, B.: Conditioning Deep Learning Weather Prediction Models On Exogenous Fields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17165, https://doi.org/10.5194/egusphere-egu24-17165, 2024.

EGU24-17389 | ECS | Orals | ITS1.1/CL0.1.17

Analyzing Spatio-Temporal Machine Learning Models through Input Perturbation 

Claire Robin, Vitus Benson, Christan Requena-Mesa, Lazaro Alonso, Jeran Poehls, Marc Russwurm, Nuno Carvalhais, and Markus Reichstein

The biogeoscience community has increasingly embraced the application of machine learning models across various domains from fire prediction to vegetation forecasting. Yet, as these models become more widely used, there is sometimes a gap in understanding between what we assume the model learns and what the model actually learns. For example, Long-short Term Memory (LSTM) models are applied to long time series, hoping they benefit from access to more information, despite their tendency to rapidly forget information. This can lead to erroneous conclusions, misinterpretation of results, and an overestimation of the models, ultimately eroding trust in their reliability. 

To address this issue, we employ an explainable artificial intelligence (XAI) post hoc perturbation technique that is task-agnostic and model-agnostic. We aim to examine the extent to which the model leverages information for its predictions, both in terms of time and space. In other words, we want to observe the actual receptive field utilized by the model. We introduce a methodology designed to quantify both the spatial impact of neighboring pixels on predicting a specific pixel and the temporal periods contributing to predictions in time series models. The experiments take place after training the model, during inference. In the spatial domain, we define ground-truth pixels to predict, then examine the increase in prediction error, caused by shuffling their neighboring pixels at various distances from the selection. In the temporal domain, we investigate how shuffling a sequence of frames within the context period at different intervals relative to the target period affects the increase in prediction loss. This method can be applied across a broad spectrum of spatio-temporal tasks. Importantly, the method is easy-to-implement, as it only relies on the inference of predictions at test time and the shuffling of the perturbation area. 

For our experiments, we focus on the vegetation forecasting task, i.e., forecasting the evolution of the Vegetation Index (VI) based on Sentinel-2 imagery using previous Sentinel-2 sequences and weather information to guide the prediction. This task involves both spatial non-linear dependencies arising from the spatial context (e.g., the surrounding area, such as a river or a slope, directly influencing the VI) and non-linear temporal dependencies such as the gradual onset of drought conditions and the rapid influence of precipitation events. We compare several models for spatio-temporal tasks, including ConvLSTM and transformer-based architectures on their usage of neighboring pixels in space, and context period in time. We demonstrate that the ConvLSTM relies on a  restricted spatial area in its predictions, indicating a limited utilization of the spatial context up to 50m (5 pixels). Furthermore, it utilizes the global order of the time series sequence to capture the seasonal cycle but loses sensitivity to the local order after 15 days (3 frames). The introduced XAI method allows us to quantify spatial and temporal behavior exhibited by machine learning methods.

How to cite: Robin, C., Benson, V., Requena-Mesa, C., Alonso, L., Poehls, J., Russwurm, M., Carvalhais, N., and Reichstein, M.: Analyzing Spatio-Temporal Machine Learning Models through Input Perturbation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17389, https://doi.org/10.5194/egusphere-egu24-17389, 2024.

EGU24-17554 | ECS | Posters on site | ITS1.1/CL0.1.17

Using Cascaded Diffusion Models and Multi-Channel Data Integration for High-Resolution Statistical Downscaling of ERA5 over Denmark 

Thea Quistgaard, Peter L. Langen, Tanja Denager, Raphael Schneider, and Simon Stisen

Central to understanding climate change impacts and mitigation strategies is the generation of high-resolution, local-scale projections from global climate models. This study focuses on Danish hydrology, developing models finely tuned to generate essential climate fields such as temperature, precipitation, evaporation, and water vapor flux.

Employing advancements in computer science and deep learning, we introduce a pioneering Cascaded Diffusion Model for high-resolution image generation. This model utilizes our understanding of climate dynamics in a hydrological context by integrating multiple climate variable fields across an expanded North Atlantic domain to produce a model for stable and realistic generation. In our approach, 30 years of low-resolution daily conditioning data (ERA5) are re-gridded to match the 2.5x2.5 km 'ground truth' data (30 years of DANRA), and preprocessed by shifting a 128x128 image within a larger 180x180 pixel area, ensuring varied geographic coverage. This data, along with land-sea masks and topography, is fed as channels into the model. A novel aspect of our model is its specialized loss function, weighted by a signed distance function to reduce the emphasis on errors over sea areas, aligning with our focus on land-based hydrological modeling.

This research is part of a larger project aimed at bridging the gap between CMIP data models and ERA5 and DANRA analysis. It represents the first phase in a three-step process, with future stages focusing on downscaling from CMIP6 to CORDEX-EUROPE models, and ultimately integrating model and analysis work to form a complete pipeline from global projections to localized daily climate statistics.

How to cite: Quistgaard, T., Langen, P. L., Denager, T., Schneider, R., and Stisen, S.: Using Cascaded Diffusion Models and Multi-Channel Data Integration for High-Resolution Statistical Downscaling of ERA5 over Denmark, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17554, https://doi.org/10.5194/egusphere-egu24-17554, 2024.

EGU24-17601 | ECS | Orals | ITS1.1/CL0.1.17

Machine learning aerosol impacts on regional climate change. 

Maura Dewey, Annica Ekman, Duncan Watson-Parris, and Hans Christen Hansson

Here we develop a machine learning emulator based on the Norwegian Earth System Model (NorESM) to predict regional climate responses to aerosol emissions and use it to study the sensitivity of surface temperature to anthropogenic emission changes in key policy regions. Aerosol emissions have both an immediate local effect on air quality, and regional effects on climate in terms of changes to temperature and precipitation distributions via direct radiative impacts and indirect cloud-aerosol interactions. Regional climate change depends on a balance between aerosol and greenhouse gas forcing, and in particular extreme events are very sensitive to changes in aerosol emissions. Our goal is to provide a tool which can be used to test the impacts of policy-driven emission changes efficiently and accurately, while retaining the spatio-temporal complexity of the larger physics-based Earth System Model.

How to cite: Dewey, M., Ekman, A., Watson-Parris, D., and Hansson, H. C.: Machine learning aerosol impacts on regional climate change., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17601, https://doi.org/10.5194/egusphere-egu24-17601, 2024.

EGU24-17694 | ECS | Orals | ITS1.1/CL0.1.17

Spatio-temporal Nonlinear Quantile Regression for Heatwave Prediction and Understanding 

Deborah Bassotto, Emiliano Diaz, and Gustau Camps-Valls

In recent years, the intersection of machine learning (ML) and climate science has yielded profound insights into understanding and predicting extreme climate events, particularly heatwaves and droughts. Various approaches have been suggested to define and model extreme events, including extreme value theory (Sura, 2011), random forests (e.g., (Weirich-Benet et al., 2023) and, more recently, deep learning (e.g., (Jacques-Dumas et al., 2022)). Within this context, quantile regression (QR) is valuable for modelling the relationship between variables by estimating the conditional quantiles of the response variable. This provides insights into the entire distribution rather than just the mean but also aids in unravelling the complex relationships among climate variables (Barbosa et al., 2011; Franzke, 2015). QR has been extended in many ways to address critical issues such as nonlinear relations, nonstationary processes, compound events, and the complexities of handling spatio-temporal data. 

This study presents a novel approach for predicting and better understanding heatwaves. We introduce an interpretable, nonlinear, non-parametric, and structured Spatio-Temporal Quantile Regression (STQR) method that incorporates the QR check function, commonly known as pinball loss, into machine learning models. We focus on analysing how the importance of predictors changes as the quantile being modelled increases. This allows us to circumvent arbitrary definitions of what constitutes a heatwave and instead observe if a natural definition of a heatwave emerges in predictor space. By analysing European heatwaves over recent decades using reanalysis and weather data, we demonstrate the advantages of our methodology over traditional extreme event modelling methods.

References

Barbosa, S.M., Scotto, M.G., Alonso, A.M., 2011. Summarising changes in air temperature over Central Europe by quantile regression and clustering. Nat. Hazards Earth Syst. Sci. 11, 3227–3233. https://doi.org/10.5194/nhess-11-3227-2011

Franzke, C.L.E., 2015. Local trend disparities of European minimum and maximum temperature extremes. Geophys. Res. Lett. 42, 6479–6484. https://doi.org/10.1002/2015GL065011

Jacques-Dumas, V., Ragone, F., Borgnat, P., Abry, P., Bouchet, F., 2022. Deep Learning-based Extreme Heatwave Forecast. Front. Clim. 4, 789641. https://doi.org/10.3389/fclim.2022.789641

Sura, P., 2011. A general perspective of extreme events in weather and climate. Atmospheric Res. 101, 1–21. https://doi.org/10.1016/j.atmosres.2011.01.012

Weirich-Benet, E., Pyrina, M., Jiménez-Esteve, B., Fraenkel, E., Cohen, J., Domeisen, D.I.V., 2023. Subseasonal Prediction of Central European Summer Heatwaves with Linear and Random Forest Machine Learning Models. Artif. Intell. Earth Syst. 2. https://doi.org/10.1175/AIES-D-22-0038.1

How to cite: Bassotto, D., Diaz, E., and Camps-Valls, G.: Spatio-temporal Nonlinear Quantile Regression for Heatwave Prediction and Understanding, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17694, https://doi.org/10.5194/egusphere-egu24-17694, 2024.

EGU24-19460 | ECS | Orals | ITS1.1/CL0.1.17 | Highlight

Earth Observation Applications through Neural Embedding Compression from Foundation Models 

Carlos Gomes and Thomas Brunschwiler

Earth observation (EO) repositories comprise Petabytes of data. Due to their widespread use, these repositories experience extremely large volumes of data transfers. For example, users of the Sentinel Data Access System downloaded 78.6 PiB of data in 2022 alone. The transfer of such data volumes between data producers and consumers causes substantial latency and requires significant amounts of energy and vast storage capacities. This work introduces Neural Embedding Compression (NEC), a method that transmits compressed embeddings to users instead of raw data, greatly reducing transfer and storage costs. The approach uses general purpose embeddings from Foundation Models (FM), which can serve multiple downstream tasks and neural compression, which balances between compression rate and the utility of the embeddings. We implemented the method by updating a minor portion of the FM’s parameters (approximately 10%) for a short training period of about 1% of the original pre-training iterations. NEC’s effectiveness is assessed through two EO tasks: scene classification and semantic segmentation. When compared to traditional compression methods applied to raw data, NEC maintains similar accuracy levels while reducing data by 75% to 90%. Notably, even with a compression rate of 99.7%, there’s only a 5% decrease in accuracy for scene classification. In summary, NEC offers a resource-efficient yet effective solution for multi-task EO modeling with minimal transfer of data volumes.

How to cite: Gomes, C. and Brunschwiler, T.: Earth Observation Applications through Neural Embedding Compression from Foundation Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19460, https://doi.org/10.5194/egusphere-egu24-19460, 2024.

EGU24-20342 | ECS | Posters on site | ITS1.1/CL0.1.17

Building A Machine Learning Model To Predict Sample Pesticide Content Utilizing Thermal Desorption MION-CIMS Analysis 

Federica Bortolussi, Hilda Sandström, Fariba Partovi, Joona Mikkilä, Patrick Rinke, and Matti Rissanen

Pests significantly impact crop yields, leading to food insecurity. Pesticides are substances, or a mixture of substances, made to eliminate or control pests, or to regulate the growth of crops.
Currently, more than 1000 pesticides are available in the market. However, their long-lasting environmental impact necessitates strict regulation, especially regarding their presence in food (FAO, 2022). Pesticides play also a role in the atmosphere as their volatilization can produce oxidized products through photolysis or OH reactions and they can be transported over large distances.
The fundamental properties and behaviours of these compounds are still not well understood. Because of their complex structure, even low DFT level computations can be extremely expensive. 
This project applies machine learning (ML) tools to chemical ionization mass spectra to ultimately develop a technique capable of predicting spectra’s peak intensities and the chemical ionization mass spectrometry (CIMS) sensitivity to pesticides. The primary challenge is to develop a ML model that comprehensively explains ion-molecule interactions while minimizing computational costs.

Our data set comprises different standard mixtures containing, in total, 716 pesticides measured with an orbitrap atmospheric pressure CIMS, with a multi-scheme chemical ionization inlet (MION) and five different concentrations (Rissanen et al, 2019; Partovi et al, 2023). The reagents of the ionization methods are CH2Br2, H2O, O2 and (CH3)2CO, generating respectively Br- , H3O+, O2- and [(CH3)2 CO + H]+ ions.

The project follows a general ML workflow: after an exploratory analysis, the data are preprocessed and fed to the ML algorithm, which classifies the ionization method able to detect the molecule, and, therefore, predicts the peak intensity of each pesticide; the accuracy of the prediction can be retrieved after measuring the performance of the model.
A random forest classifier was chosen to perform the classification of the ionization methods, to predict which one was able to detect each pesticide. The regression was performed with a kernel ridge regressor. Each algorithm was run with different types of molecular descriptors (topological fingerprint, MACCS keys and many-body tensor representation), to test which one was able to represent the molecular structure most accurately.

The results of the exploratory analysis highlight different trends between the positive and negative ionization methods, suggesting that different ion-molecule mechanisms are involved (Figure 1). The classification reaches around 80% accuracy for each ionization method with all four molecular descriptors tested, while the regression can predict fairly well the logarithm of the intensities of each ionization method, reaching 0.5 of error with MACCS keys for (CH3)2CO reagent (Figure 2).

Figure 1: Distribution of pesticide peak intensities for each reagent ion at five different concentrations.

Figure 2: Comparison of the KRR performance on (CH3)2CO reagent data with four different molecular descriptors.

 

 

How to cite: Bortolussi, F., Sandström, H., Partovi, F., Mikkilä, J., Rinke, P., and Rissanen, M.: Building A Machine Learning Model To Predict Sample Pesticide Content Utilizing Thermal Desorption MION-CIMS Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20342, https://doi.org/10.5194/egusphere-egu24-20342, 2024.

Leveraging Machine Learning (ML) models, particularly Convolutional Neural Networks (CNNs), Recurrent Neural Networks (RNNs) like Long-Short Term Memory (LSTM), and Artificial Neural Networks (ANN), has become pivotal in addressing the escalating frequency and severity of extreme events such as heatwaves, hurricanes, floods, and droughts. In climate modeling, ML proves invaluable for analyzing diverse datasets, including climate data and satellite imagery, outperforming traditional methods by adeptly handling vast information and identifying intricate patterns. Focusing on the study's emphasis on extreme precipitation events, the urgency arises from climate change, demanding more accurate and timely methods to predict and manage the impacts of these events.

In this study, we completed two main experiments to understand if ML algorithms can detect the extreme events. In both experiment the predictors that have been used are eastern and northern wind (u,v), geopotential height (z), specific humidity (q) and temperature (t) at four pressure levels, which are 1000hpa, 850hpa, 700hpa, and 500hpa. The frequency for the predictors is 3 hours, while the predictand being the precipitation accumulated over 3 hours. The data used in this study are the Re-Analysis -5th generation- (ERA5) produced by European Center for Medium-Range Weather Forecast (ECMWF), which provides global hourly estimates of large number of atmospheric, land and oceanic climate variables with a resolution of 25 km at different pressure levels and for the surface (precipitation in our case).

In this study, two main architectures have been applied. The first emulator, ERA-Emulator, contains 14 layers, divided in 4 blocks (input, convolutional, dense, output). In the convolutional block we have 6 convolutional layers, one layer of type ConvLSTM2D, that combines a 2D Convolutional layer and an LSTM layer, and five simple 2D convolutional layers, with two of them followed by a MaxPooling layer. In the Dense block there are three fully connected Dense layers followed by one Flatten layer and one Dropout layer. Then, we have the output layer, also a Dense layer. We used the same architecture for the second emulator, GRIPHO-Emulator, with one extra MaxPooling in the convolutional block, for a total of 15 layers. The first emulator uses variables from ERA5 both as input and output at 25 km resolution, while the second one uses variables from ERA5 as input, and the Gridded Italian Precipitation Hourly Observations dataset (GRIPHO) as output at 3 km resolution.

The ERA-Emulator is designed to approximate the downscaling function by utilizing low-resolution simulations to generate equivalent low resolution precipitation fields. ERA-Emulator resulted in a viable approach to address this challenge. The emulator demonstrates the capability to derive precipitation fields that align with ERA5 low-resolution simulations.  GRIPHO-emulator aims to downscale high resolution precipitation from low-resolution large-scale predictors. The emulator aims to estimate the downscaling function. GRIPHO-Emulator is able to create realistic high-resolution precipitation fields that well represent the observed precipitation distribution from the high resolution GRIPHO dataset.

How to cite: Abed, W. and Coppola, E.: Detection of High Convective Precipitation Events Using Machine Learning Methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21760, https://doi.org/10.5194/egusphere-egu24-21760, 2024.

EGU24-2443 | ECS | Posters on site | ITS1.3/CL0.1.18

Deep learning generative strategies to enhance 3D physics-based seismic wave propagation: from diffusive super-resolution to 3D Fourier Neural Operators. 

Filippo Gatti, Fanny Lehmann, Hugo Gabrielidis, Michaël Bertin, Didier Clouteau, and Stéphane Vialle

Estimating the seismic hazard in earthquake-prone regions, in order to assess the risk associated to nuclear facilities, must take into account a large number of uncertainties, and in particular our limited knowledge of the geology. And yet, we know that certain geological features can create site effects that considerably amplify earthquake ground motion. In this work, we provide a quantitative assessment of how largely can earthquake ground motion simulation benefit from deep learning approaches, quantifying the influence of geological heterogeneities on the spatio-temporal nature of the earthquake-induced site response. Two main frameworks are addressed: conditional generative approaches with diffusion models and neural operators. On one hand, generative adversarial learning and diffusions models are compared in a time-series super-resolution context [1]. The main task is to improve the outcome of 3D fault-to-site earthquake numerical simulations (accurate up to 5 Hz [2, 3]) at higher frequencies (5-30 Hz), by learning the low-to-high frequency mapping from seismograms recorded worldwide [1]. The generation is conditioned by the numerical simulation synthetic time-histories, in a one-to-many setup that enables site-specific probabilistic hazard assessment. On the other hand, the successful use of Factorized Fourier Neural Operator (F-FNO) to entirely replace cumbersome 3D elastodynamic numerical simulations is described [4], showing how this approach can pave the way to real-time large-scale digital twins of earthquake prone regions. The trained neural operator learns the relationship between 3D heterogeneous geologies and surface ground motions generated by the propagation of seismic wave through these geologies. The F-FNO is trained on the HEMEW-3D (https://github.com/lehmannfa/HEMEW3D/releases) database, comprising 30000 high-fidelity numerical simulations of earthquake ground motion through generic geologies, performed by employing the high-performance code SEM3D [4]. Next, a smaller database was built specifically for the Teil region (Ardèche, France), where a MW 4.9 moderate shallow earthquake occurred in November 2019 [4]. The F-FNO is then specialized on this database database with just 250 examples. Transfer learning improved the prediction error by 22 %. According to seismological Goodness-of-Fit (GoF) metrics, 91% of predictions have an excellent GoF for the phase (and 62% for the envelope). Ground motion intensity measurements are, on average, slightly underestimated.

[1] Gatti, F.; Clouteau, D. Towards Blending Physics-Based Numerical Simulations and Seismic Databases Using Generative Adversarial Network. Computer Methods in Applied Mechanics and Engineering 2020, 372, 113421.
https://doi.org/10.1016/j.cma.2020.113421.

[2] Touhami, S.; Gatti, F.; Lopez-Caballero, F.; Cottereau, R.; de Abreu Corrêa, L.;Aubry, L.; Clouteau, D. SEM3D: A 3D High-Fidelity Numerical Earthquake Sim-ulator for Broadband (0–10 Hz) Seismic Response Prediction at a Regional Scale.Geosciences 2022, 12 (3), 112. https://doi.org/10.3390/geosciences12030112. https://github.com/sem3d/SEM

[3] Gatti, F.; Carvalho Paludo, L. D.; Svay, A.; Lopez-Caballero, F.-; Cottereau, R.;Clouteau, D. Investigation of the Earthquake Ground Motion Coherence in Het-erogeneous Non-Linear Soil Deposits. Procedia Engineering 2017, 199, 2354–2359.https://doi.org/10.1016/j.proeng.2017.09.232.[4] Lehmann, F.; Gatti, F.; Bertin, M.; Clouteau, D. Machine Learning Opportunities to Conduct High-Fidelity Earthquake Simulations in Multi-Scale Heterogeneous Geology.Front. Earth Sci. 2022, 10, 1029160. https://doi.org/10.3389/feart.2022.1029160.

[4] Lehmann, F.; Gatti, F.; Bertin, M.; Clouteau, D. Fourier Neural Operator Sur-rogate Model to Predict 3D Seismic Waves Propagation. arXiv April 20, 2023.http://arxiv.org/abs/2304.10242 (accessed 2023-04-21).

How to cite: Gatti, F., Lehmann, F., Gabrielidis, H., Bertin, M., Clouteau, D., and Vialle, S.: Deep learning generative strategies to enhance 3D physics-based seismic wave propagation: from diffusive super-resolution to 3D Fourier Neural Operators., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2443, https://doi.org/10.5194/egusphere-egu24-2443, 2024.

EGU24-2691 | Orals | ITS1.3/CL0.1.18 | Highlight

Grand designs: quantifying many kinds of model uncertainty to improve projections of sea level rise  

Tamsin Edwards, Fiona Turner, Jonathan Rougier, and Jeremy Rohmer and the EU PROTECT project

In the EU Horizon 2020 project PROTECT, we have performed around 5000 simulations of the Greenland and Antarctic ice sheets and the world’s glaciers to predict the land ice contribution to sea level rise up to 2300. Unlike previous international model intercomparison projects (Edwards et al., 2021; IPCC Sixth Assessment Report, 2021), this is a "grand ensemble" sampling every type of model uncertainty – plausible structures, parameters and initial conditions – and is performed under many possible boundary conditions (climate change projected by multiple global and regional climate models). The simulations also start in the past, unlike the previous projects, to assess the impact of these uncertainties on historical changes.

We use probabilistic machine learning to emulate the relationships between model inputs (climate change; ice sheet and glacier model choices) and outputs (sea level contribution), so we can make predictions for any climate scenario and sample model uncertainties more thoroughly than with the original physical models. We try multiple machine learning methods that have different strengths in terms of speed, smoothness, interpretability, and performance for categorical uncertainties (Gaussian Processes, random forests).

The design of the grand ensemble allows the influence of all these uncertainties to be captured explicitly, rather than treating them as simple noise, and the earlier start date allows formal calibration (Bayesian or history matching) with observed ice sheet and glacier changes, to improve confidence (and typically reduce uncertainties) in the projections. Here we show preliminary projections for global mean sea level rise up to 2300 using these advances, and describe challenges and solutions found along the way.

How to cite: Edwards, T., Turner, F., Rougier, J., and Rohmer, J. and the EU PROTECT project: Grand designs: quantifying many kinds of model uncertainty to improve projections of sea level rise , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2691, https://doi.org/10.5194/egusphere-egu24-2691, 2024.

EGU24-3520 | Orals | ITS1.3/CL0.1.18

Machine Learning for Nonorographic Gravity Waves in a Climate Model 

Steven Hardiman, Adam Scaife, Annelize van Niekerk, Rachel Prudden, Aled Owen, Samantha Adams, Tom Dunstan, Nick Dunstone, and Sam Madge

Use of machine learning algorithms in climate simulations requires such algorithms to replicate certain aspects of the physics in general circulation models.  In this study, a neural network is used to mimic the behavior of one of the subgrid parameterization schemes used in global climate models, the nonorographic gravity wave scheme.  Use of a one-dimensional mechanistic model is advocated, allowing neural network hyperparameters to be chosen based on emergent features of the coupled system with minimal computational cost, and providing a testbed prior to coupling to a climate model. A climate model simulation, using the neural network in place of the existing parameterization scheme, is found to accurately generate a quasi-biennial oscillation of the tropical stratospheric winds, and correctly simulate the nonorographic gravity wave variability associated with the El Niño–Southern Oscillation and stratospheric polar vortex variability. These internal sources of variability are essential for providing seasonal forecast skill, and the gravity wave forcing associated with them is reproduced without explicit training for these patterns.

How to cite: Hardiman, S., Scaife, A., van Niekerk, A., Prudden, R., Owen, A., Adams, S., Dunstan, T., Dunstone, N., and Madge, S.: Machine Learning for Nonorographic Gravity Waves in a Climate Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3520, https://doi.org/10.5194/egusphere-egu24-3520, 2024.

EGU24-5048 | Orals | ITS1.3/CL0.1.18

Emulators for Predicting Tsunami Inundation Maps at High Resolution 

Steven J. Gibbons, Erlend Briseid Storrøsten, Naveen Ramalingam, Stefano Lorito, Manuela Volpe, Carlos Sánchez-Linares, and Finn Løvholt

Predicting coastal tsunami impact requires the computation of inundation metrics such as maximum inundation height or momentum flux at all locations of interest. The high computational cost of inundation modelling, in both long term tsunami hazard assessment and urgent tsunami computing, comes from two major factors: (1) the high number of simulations needed to capture the source uncertainty and (2) the need to solve the nonlinear shallow water equations on high-resolution grids. We seek to mitigate the second of these factors using machine learning. The offshore tsunami wave is far cheaper to calculate than the full inundation map, and an emulator able to predict an inundation map with acceptable accuracy from simulated offshore wave height time-series would allow both more rapid hazard estimates and the processing of greater numbers of scenarios. The procedure would necessarily be specific to one stretch of coastline and a complete numerical simulation is needed for each member of the training set. Success of an inundation emulator would demand an acceptable reduction in time-to-solution, a modest number of training scenarios, an acceptable accuracy in inundation predictions, and good performance for high impact, low probability, scenarios. We have developed a convolutional encoder-decoder based neural network and applied it to a dataset of high-resolution inundation simulations for the Bay of Catania in Sicily, calculated for almost 28000 subduction earthquake scenarios in the Mediterranean Sea. We demonstrate encouraging performance in this case study for relatively small training sets (of the order of several hundred scenarios) provided that appropriate choices are made in the setting of model parameters, the loss function, and training sets. Scenarios with severe inundation need to be very well represented in the training sets for the ML-models to perform sufficiently well for the most tsunamigenic earthquakes. The importance of regularization and model parameter choices increases as the size of the training sets decrease.

How to cite: Gibbons, S. J., Briseid Storrøsten, E., Ramalingam, N., Lorito, S., Volpe, M., Sánchez-Linares, C., and Løvholt, F.: Emulators for Predicting Tsunami Inundation Maps at High Resolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5048, https://doi.org/10.5194/egusphere-egu24-5048, 2024.

EGU24-5852 | Posters on site | ITS1.3/CL0.1.18

CROMES - A fast and efficient machine learning emulator pipeline for gridded crop models 

Christian Folberth, Artem Baklanov, Nikolay Khabarov, Thomas Oberleitner, Juraj Balkovic, and Rastislav Skalsky

Global gridded crop models (GGCMs) have become state-of-the-art tools in large-scale climate impact and adaptation assessments. Yet, these combinations of large-scale spatial data frameworks and plant growth models have limitations in the volume of scenarios they can address due to computational demand and complex software structures. Emulators mimicking such models have therefore become an attractive option to produce reasonable predictions of GGCMs’ crop productivity estimates at much lower computational costs. However, such emulators’ flexibility is thus far typically limited in terms of crop management flexibility and spatial resolutions among others. Here we present a new emulator pipeline CROp model Machine learning Emulator Suite (CROMES) that serves for processing climate features from netCDF input files, combining these with site-specific features (soil, topography), and crop management specifications (planting dates, cultivars, irrigation) to train machine learning emulators and subsequently produce predictions. Presently built around the GGCM EPIC-IIASA and employing a boosting algorithm, CROMES is capable of producing predictions for EPIC-IIASA’s crop yield estimates with high accuracy and very high computational efficiency. Predictions require for a first used climate dataset about 45 min and 10 min for any subsequent scenario based on the same climate forcing in a single thread compared to approx. 14h for a GGCM simulation on the same system.

Prediction accuracy is highest if modeling the case when crops receive sufficient nutrients and are consequently most sensitive to climate. When training an emulator on crop model simulations for rainfed maize and a single global climate model (GCM), the yield prediction accuracy for out-of-bag GCMs is R2=0.93-0.97, RMSE=0.5-0.7, and rRMSE=8-10% in space and time. Globally, the best agreement between predictions and crop model simulations occurs in (sub-)tropical regions, the poorest is in cold, arid climates where both growing season length and water availability limit crop growth. The performance slightly deteriorates if fertilizer supply is considered, more so at low levels of nutrient inputs than at the higher end.

Importantly, emulators produced by CROMES are virtually scale-free as all training samples, i.e., pixels, are pooled and hence treated as individual locations solely based on features provided without geo-referencing. This allows for applications on increasingly available high-resolution climate datasets or in regional studies for which more granular data may be available than at global scales. Using climate features based on crop growing seasons and cardinal growth stages enables also adaptation studies including growing season and cultivar shifts. We expect CROMES to facilitate explorations of comprehensive climate projection ensembles, studies of dynamic climate adaptation scenarios, and cross-scale impact and adaptation assessments.

 

How to cite: Folberth, C., Baklanov, A., Khabarov, N., Oberleitner, T., Balkovic, J., and Skalsky, R.: CROMES - A fast and efficient machine learning emulator pipeline for gridded crop models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5852, https://doi.org/10.5194/egusphere-egu24-5852, 2024.

EGU24-6622 | ECS | Posters virtual | ITS1.3/CL0.1.18

Comparison of SWAT and a deep learning model in nitrate load simulation at the Tuckahoe creek watershed in the United States 

Jiye Lee, Dongho Kim, Seokmin Hong, Daeun Yun, Dohyuck Kwon, Robert Hill, Yakov Pachepsky, Feng Gao, Xuesong Zhang, Sangchul Lee, and KyungHwa Cho

Simulating nitrate fate and transport in freshwater is an essential part in water quality management. Numerical and data-driven models have been used for it. The numerical model SWAT simulates daily nitrate loads using simulated flow rate. Data-driven models are more flexible compared to SWAT as they can simulate nitrate load and flow rate independently. The objective of this work was evaluating the performance of SWAT and a deep learning model in terms of nutrient loads in cases when deep learning model is used in (a) simulating flow rate and nitrate concentration independently and (b) simulating both flow rate and nitrate concentration. The deep learning model was built using long-short-term-memory and three-dimensional convolutional networks. The input data, weather data and image data including leaf area index and land use, were acquired at the Tuckahoe Creek watershed in Maryland, United States. The SWAT model was calibrated with data over the training period (2014-2017) and validated with data over the testing period (2019) to simulate flow rate and nitrate load. The Nash-Sutcliffe efficiency was 0.31 and 0.40 for flow rate and -0.26 and -0.18 for the nitrate load over training and testing periods, respectively. Three data-driven modeling scenarios were generated for nitrate load. Scenario 1 included the flow rate observation and nitrate concentration simulation, scenario 2 included the flow rate simulation and nitrate concentration observation, and scenario 3 included the flow rate and nitrate concentration simulations. The deep learning model outperformed SWAT in all three scenarios with NSE from 0.49 to 0.58 over the training period and from 0.28 to 0.80 over the testing period. Scenario 1 showed the best results for nitrate load. The performance difference between SWAT and the deep learning model was most noticeable in fall and winter seasons. The deep learning modeling can be an efficient alternative to numerical watershed-scale models when the regular high frequency data collection is provided.

How to cite: Lee, J., Kim, D., Hong, S., Yun, D., Kwon, D., Hill, R., Pachepsky, Y., Gao, F., Zhang, X., Lee, S., and Cho, K.: Comparison of SWAT and a deep learning model in nitrate load simulation at the Tuckahoe creek watershed in the United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6622, https://doi.org/10.5194/egusphere-egu24-6622, 2024.

EGU24-7455 | ECS | Orals | ITS1.3/CL0.1.18

Assessment of ARPEGE-Climat using a neural network convection parameterization based upon data from SPCAM 5 

Blanka Balogh, David Saint-Martin, Olivier Geoffroy, Mohamed Aziz Bhouri, and Pierre Gentine

Interfacing challenges continue to impede the implementation of neural network-based parameterizations into numerical models of the atmosphere, particularly those written in Fortran. In this study, we leverage a specialized interfacing tool to successfully implement a neural network-based parameterization for both deep and shallow convection within the General Circulation Model, ARPEGE-Climat. Our primary objective is to not only evaluate the performance of this data-driven parameterization but also assess the numerical stability of ARPEGE-Climat when coupled with a convection parameterization trained on data from a different high-resolution model, namely SPCAM 5. 

The performance evaluation encompasses both offline and online assessments of the data-driven parameterization within this framework. The data-driven parameterization for convection is designed using a multi-fidelity approach and is adaptable for use in a stochastic configuration. Challenges associated with this approach include ensuring consistency between variables in ARPEGE-Climat and the parameterization based on data from SPCAM 5, as well as managing disparities in geometry (e.g., horizontal and vertical resolutions), which are crucial factors affecting the intermodel parameterization transferability.

How to cite: Balogh, B., Saint-Martin, D., Geoffroy, O., Bhouri, M. A., and Gentine, P.: Assessment of ARPEGE-Climat using a neural network convection parameterization based upon data from SPCAM 5, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7455, https://doi.org/10.5194/egusphere-egu24-7455, 2024.

EGU24-7581 | Posters on site | ITS1.3/CL0.1.18

Blending machine-learning and mesoscale numerical weather prediction models to quantify city-scale heat mitigation 

Yongling Zhao, Zhi Wang, Dominik Strebel, and Jan Carmeliet

Urban warming in cities is increasingly exacerbated by the escalation of more frequent and severe heat extremes. Effectively mitigating overheating necessitates the adoption of a comprehensive, whole-system approach that integrates various heat mitigation measures to generate rapid and sustained efficacy in mitigation efforts. However, there remains a significant gap in the exploration of how to quantify the efficacy of mitigation strategies at the city-scale.

We address this research question by leveraging mesoscale Weather Research Forecasting (WRF) models alongside machine-learning (ML) techniques. As a showcase, ML models have been established for Zurich and Basel, Switzerland, utilizing seven WRF-output-based features, including shortwave downward radiation (SWDNB), hour of the day (HOUR), zenith angle (COSZEN), rain mix ratio (QRAIN), longwave downward radiation (LWDNB), canopy water content (CANWAT), and planetary boundary layer height (PBLH). Impressively, the resultant median R2 values for T2 (2m temperature) predictions during heatwave and non-heatwave periods are notably high at 0.94 and 0.91 respectively.

Within the perspective of the whole-system approach, we quantify the impacts of reducing shortwave radiation absorption at ground surfaces, a potential result of a combination of both shading and reflective coating-based mitigation measures, through the utilization of ML models. Remarkably, a 5% reduction in the absorption of radiation at ground surfaces in Zurich could lead to a reduction in T2 by as much as 3.5 °C in the city center. During a heatwave in Basel, the potential for cooling is even more pronounced, with temperature decreases of up to 5 °C. These case studies in Zurich and Basel underscore the efficacy of utilizing WRF feature-trained ML models to quantify heat mitigation strategies at the city-scale.

How to cite: Zhao, Y., Wang, Z., Strebel, D., and Carmeliet, J.: Blending machine-learning and mesoscale numerical weather prediction models to quantify city-scale heat mitigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7581, https://doi.org/10.5194/egusphere-egu24-7581, 2024.

EGU24-7681 | ECS | Posters on site | ITS1.3/CL0.1.18

Multi-scale hydraulic-based graph neural networks: generalizing spatial flood mapping to irregular meshes and time-varying boundary condition 

Roberto Bentivoglio, Elvin Isufi, Sebastian Nicolaas Jonkman, and Riccardo Taormina

Deep learning models emerged as viable alternatives to rapid and accurate flood mapping, overcoming the computational burden of numerical methods. In particular, hydraulic-based graph neural networks present a promising avenue, offering enhanced transferability to domains not used for the model training. These models exploit the analogy between finite-volume methods and graph neural networks to describe how water moves in space and time across neighbouring cells. However, existing models face limitations, having been exclusively tested on regular meshes and necessitating initial conditions from numerical solvers. This study proposes an extension of hydraulic-based graph neural networks to accommodate time-varying boundary conditions, showcasing its efficacy on irregular meshes. For this, we employ multi-scale methods that jointly model the flood at different scales. To remove the necessity of initial conditions, we leverage ghost cells that enforce the solutions at the boundaries. Our approach is validated on a dataset featuring irregular meshes, diverse topographies, and varying input hydrograph discharges. Results highlight the model's capacity to replicate flood dynamics across unseen scenarios, without any input from the numerical model, emphasizing its potential for realistic case studies.

How to cite: Bentivoglio, R., Isufi, E., Jonkman, S. N., and Taormina, R.: Multi-scale hydraulic-based graph neural networks: generalizing spatial flood mapping to irregular meshes and time-varying boundary condition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7681, https://doi.org/10.5194/egusphere-egu24-7681, 2024.

EGU24-10087 | ECS | Orals | ITS1.3/CL0.1.18

Contribution of latent variables to emulate the physics of the IPSL model 

Ségolène Crossouard, Masa Kageyama, Mathieu Vrac, Thomas Dubos, Soulivanh Thao, and Yann Meurdesoif

Atmospheric general circulation models include two main distinct components: the dynamical one solves the Navier-Stokes equations to provide a mathematical representation of atmospheric movements while the physical one includes parameterizations representing small-scale phenomena such as turbulence and convection (Balaji et al., 2022). However, computational demands of the parameterizations limit the numerical efficiency of the models. The burgeoning field of machine learning techniques opens new horizons by producing accurate, robust and fast emulators of parts of a climate model. In particular, they can reliably reproduce physical processes, thus providing an efficient alternative to traditional process representation. Indeed, some pioneering studies (Gentine et al., 2018; Rasp et al., 2018) have shown that these emulators can replace one or more parameterizations that are computationally expensive and so, have the potential to enhance numerical efficiency.

Our research work aligns with these perspectives, since it involves exploiting the potential of developing an emulator of the physical parameterizations of the IPSL climate model, and more specifically of the ICOLMDZOR atmospheric model (for DYNAMICO, the dynamic solver using an icosahedral grid - LMDZ, the atmospheric component - ORCHIDEE, the surface component). The emulator could improve performance, as currently almost half of the total computing time is given to the physical part of the model.

We have developed two initial offline emulators of the physical parameterizations of our standard model, in an idealized aquaplanet configuration, to reproduce profiles of tendencies of the key variables - zonal wind, meridional wind, temperature, humidity and water tracers - for each atmospheric column. The results of these emulators, based on a dense neural network or a convolutional neural network, have begun to show their potential for use, since we easily obtain good performances in terms of the mean of the predicted tendencies. Nevertheless, their variability is not well captured, and the variance is underestimated, posing challenges for our application. A study of physical processes has revealed that turbulence was at the root of the problem. Knowing how turbulence is parameterized in the model, we show that incorporating physical knowledge through latent variables as predictors into the learning process, leading to a significant improvement of the variability.

Future plans involve an online physics emulator, coupled with the atmospheric model to provide a better assessment of the learning process (Yuval et al., 2021).

How to cite: Crossouard, S., Kageyama, M., Vrac, M., Dubos, T., Thao, S., and Meurdesoif, Y.: Contribution of latent variables to emulate the physics of the IPSL model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10087, https://doi.org/10.5194/egusphere-egu24-10087, 2024.

EGU24-10749 | ECS | Orals | ITS1.3/CL0.1.18

Replacing parametrisations of melt ponds on sea ice with machine learning emulators 

Simon Driscoll, Alberto Carrassi, Julien Brajard, Laurent Bertino, Marc Bocquet, Einar Olason, and Amos Lawless

Sea ice plays an essential role in global ocean circulation and in regulating Earth's climate and weather, and melt ponds that form on the ice have a profound impact on the Arctic's climate by altering the ice albedo. Melt pond evolution is complex, sub grid scale and poorly understood - and melt ponds are represented in sea ice models as parametrisations. Parametrisations of these physical processes are based on a number of assumptions and can include many uncertain parameters that have a substantial effect on the simulated evolution of the melt ponds. 

We have shown, using Sobol sensitivity analysis and through investigating perturbed parameter ensembles (PPEs), that a state-of-the-art sea ice column model, Icepack, demonstrates substantial sensitivity to its uncertain melt pond parameters. These PPEs demonstrate that perturbing melt pond parameters (within known ranges of uncertainty) cause predicted sea ice thickness over the Arctic Ocean to differ by many metres after only a decade of simulation. Understanding the sources of uncertainty, improving parametrisations and fine tuning the parameters is a paramount, but usually very complex and difficult task. Given this uncertainty, we propose to replace the sub grid scale melt pond parametrisation (MPP) in Icepack with a machine learning emulator. 

Building and replacing the MPP with a machine learning emulator has been done in two broad steps that contain multiple computational challenges. The first is generating a melt pond emulator using 'perfect' or 'model' data. Here we demonstrate a proof of concept and show how we achieve numerically stable simulations of Icepack when embedding an emulator in place of the MPP - with Icepack running stably for the whole length of the simulations (over a decade) across the Arctic. 

Secondly, we develop offline an emulator from observational data that faithfully predicts observed sea ice albedo and melt pond fraction given climatological input variables. Embedding an observational emulator can require different challenges as compared to using model data, such as not all variables needed by the host model being observable/observed for an emulator to predict. We discuss how we achieve online simulations interfacing this emulator with the Icepack model.

Our focus on using column models ensures that our observational emulator of sea ice albedo and melt pond fraction can readily be used in sea ice models around the world, irrespective of grid resolutions and mesh specifications, and offers one approach for creating general emulators that can be used by many climate models. 

How to cite: Driscoll, S., Carrassi, A., Brajard, J., Bertino, L., Bocquet, M., Olason, E., and Lawless, A.: Replacing parametrisations of melt ponds on sea ice with machine learning emulators, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10749, https://doi.org/10.5194/egusphere-egu24-10749, 2024.

EGU24-11880 | ECS | Posters on site | ITS1.3/CL0.1.18

Understanding geoscientific system behaviour from machine learning surrogates 

Oriol Pomarol Moya, Derek Karssenberg, Walter Immerzeel, Madlene Nussbaum, and Siamak Mehrkanoon

Machine learning (ML) models have become popular in the Earth Sciences for improving predictions based on observations. Beyond pure prediction, though, ML has a large potential to create surrogates that emulate complex numerical simulation models, considerably reducing run time, hence facilitating their analysis.

The behaviour of eco-geomorphological systems is often examined using minimal models, simple equation-based expressions derived from expert knowledge. From them, one can identify complex system characteristics such as equilibria, tipping points, and transients. However, model formulation is largely subjective, thus disputable. Here, we propose an alternative approach where a ML surrogate of a high-fidelity numerical model is used instead, conserving suitability for analysis while incorporating the higher-order physics of its parent model. The complexities of developing such an ML surrogate for understanding the co-evolution of vegetation, hydrology, and geomorphology on a geological time scale are presented, highlighting the potential of this approach to capture novel, data-driven scientific insights.

To obtain the surrogate, the ML models were trained on a data set simulating a coupled hydrological-vegetation-soil system. The rate of change of the two variables describing the system, soil depth and biomass, was used as output, taking their value at the previous time step and the pre-defined grazing pressure as inputs. Two popular ML methods, random forest (RF) and fully connected neural network (NN), were used. As proof of concept and to configure the model setup, we first trained the ML models on the output of the minimal model described in [1], comparing the ML responses at gridded inputs with the derivative values predicted by the minimal model. While RF required less tuning to achieve competitive results, a relative root mean squared error (rRMSE) of 5.8% and 0.04% for biomass and soil depth respectively, NN produced better-behaved outcome, reaching a rRMSE of 2.2% and 0.01%. Using the same setup, the ML surrogates were trained on a high-resolution numerical model describing the same system. The study of the response from this surrogate provided a more accurate description of the dynamics and equilibria of the hillslope ecosystem, depicting, for example, a much more complex process of hillslope desertification than captured by the minimal model.

It is thus concluded that the use of ML models instead of expert-based minimal models may lead to considerably different findings, where ML models have the advantage that they directly rely on system functioning embedded in their parent numerical simulation model.

How to cite: Pomarol Moya, O., Karssenberg, D., Immerzeel, W., Nussbaum, M., and Mehrkanoon, S.: Understanding geoscientific system behaviour from machine learning surrogates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11880, https://doi.org/10.5194/egusphere-egu24-11880, 2024.

EGU24-14744 | ECS | Orals | ITS1.3/CL0.1.18 | Highlight

End-to-end Learning in Hybrid Modeling Systems: How to Deal with Backpropagation Through Numerical Solvers 

Said Ouala, Bertrand Chapron, Fabrice Collard, Lucile Gaultier, and Ronan Fablet

Artificial intelligence and deep learning are currently reshaping numerical simulation frameworks by introducing new modeling capabilities. These frameworks are extensively investigated in the context of model correction and parameterization where they demonstrate great potential and often outperform traditional physical models. Most of these efforts in defining hybrid dynamical systems follow offline learning strategies in which the neural parameterization (called here sub-model) is trained to output an ideal correction. Yet, these hybrid models can face hard limitations when defining what should be a relevant sub-model response that would translate into a good forecasting performance. End-to-end learning schemes, also referred to as online learning, could address such a shortcoming by allowing the deep learning sub-models to train on historical data. However, defining end-to-end training schemes for the calibration of neural sub-models in hybrid systems requires working with an optimization problem that involves the solver of the physical equations. Online learning methodologies thus require the numerical model to be differentiable, which is not the case for most modeling systems. To overcome this difficulty and bypass the differentiability challenge of physical models, we present an efficient and practical online learning approach for hybrid systems. The method, called EGA for Euler Gradient Approximation, assumes an additive neural correction to the physical model, and an explicit Euler approximation of the gradients. We demonstrate that the EGA converges to the exact gradients in the limit of infinitely small time steps. Numerical experiments are performed on various case studies, including prototypical ocean-atmosphere dynamics. Results show significant improvements over offline learning, highlighting the potential of end-to-end online learning for hybrid modeling.

How to cite: Ouala, S., Chapron, B., Collard, F., Gaultier, L., and Fablet, R.: End-to-end Learning in Hybrid Modeling Systems: How to Deal with Backpropagation Through Numerical Solvers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14744, https://doi.org/10.5194/egusphere-egu24-14744, 2024.

EGU24-14957 | ECS | Posters on site | ITS1.3/CL0.1.18

Exploring data-driven emulators for snow on sea ice  

Ayush Prasad, Ioanna Merkouriadi, and Aleksi Nummelin

Snow is a crucial element of the sea ice system, impacting various environmental and climatic processes. SnowModel is a numerical model that is developed to simulate the evolution of snow depth and density, blowing-snow redistribution and sublimation, snow grain size, and thermal conductivity, in a spatially distributed, multi-layer snowpack framework. However, SnowModel faces challenges with slow processing speeds and the need for high computational resources. To address these common issues in high-resolution numerical modeling, data-driven emulators are often used. They aim to replicate the output of complex numerical models like SnowModel but with greater efficiency. However, these emulators often face their own set of problems, primarily a lack of generalizability and inconsistency with physical laws. A significant issue related to this is the phenomenon of concept drift, which may arise when an emulator is used in a region or under conditions that differ from its training environment. For instance, an emulator trained on data from one Arctic region might not yield accurate results if applied in another region with distinct snow properties or climatic conditions. In our study, we address these challenges with a physics-guided approach in developing our emulator. By integrating physical laws that govern changes in snow density due to compaction, we aim to create an emulator that is efficient while also adhering to essential physical principles. We evaluated this approach by comparing four machine learning models: Long Short-Term Memory (LSTM), Physics-Guided LSTM, Gradient Boosting Machines, and Random Forest, across five distinct Arctic regions. Our evaluations indicate that all models achieved high accuracy, with the Physics-Guided LSTM model demonstrating the most promising results in terms of accuracy and generalizability. This approach offers a computationally faster way to emulate the SnowModel with high fidelity. 

How to cite: Prasad, A., Merkouriadi, I., and Nummelin, A.: Exploring data-driven emulators for snow on sea ice , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14957, https://doi.org/10.5194/egusphere-egu24-14957, 2024.

EGU24-15914 | Posters on site | ITS1.3/CL0.1.18

Machine Learning Estimator for Ground-Shaking maps 

Marisol Monterrubio-Velasco, Rut Blanco, Scott Callaghan, Cedric Bhihe, Marta Pienkowska, Jorge Ejarque, and Josep de la Puente

The Machine Learning Estimator for Ground Shaking Maps (MLESmaps) harnesses the ground shaking inference capability of Machine Learning (ML) models trained on physics-informed earthquake simulations. It infers intensity measures, such as RotD50, seconds after a significant earthquake has occurred given its magnitude and location. 

Our methodology incorporates both offline and online phases in a comprehensive workflow. It begins with the generation of a synthetic training data set, progresses through the extraction of predictor characteristics, proceeds to the validation and learning stages, and yields a learned inference model. 

MLESmap results can complement empirical Ground Motion Models (GMMs), in particular in data-poor areas, to assess post-earthquake hazards rapidly and accurately, potentially improving disaster response in earthquake-prone regions. Learned models incorporate physical features such as directivity, topography, or resonance at a speed comparable to that of the empirical GMMs. 

In this work, we present an overview of the MLESmap methodology and its application to two distinct study areas: southern California and southern Iceland

 

How to cite: Monterrubio-Velasco, M., Blanco, R., Callaghan, S., Bhihe, C., Pienkowska, M., Ejarque, J., and de la Puente, J.: Machine Learning Estimator for Ground-Shaking maps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15914, https://doi.org/10.5194/egusphere-egu24-15914, 2024.

The combination of Machine Learning (ML) with geoscientific models is an active area of research with a wide variety of applications. A key practical question for those models is to define how high level languages ML components can be encoded and maintained into pre-existing legacy solvers, written in low level abstraction languages (as Fortran). We address this question through the strategy of creating pipes between a geoscientific code and ML components executed in their own separate scripts. The main advantage of this approach is the possibility to easily share the inference models within the community without keeping them bound to one code with its specific numerical methods. Here, we chose to focus on OASIS (https://oasis.cerfacs.fr/en/), which is a Fortran coupling library that performs field exchanges between coupled executables. It is commonly used in the numerical geoscientific community to couple different codes and assemble earth-system models. Last releases of OASIS provided C and Python APIs, which enable coupling between non-homogeneously written codes. We seek to take advantage of those new features and the presence of OASIS in the community codes, and propose a Python library (named Eophis) that facilitates the deployment of inference models for coupled execution. Basically, Eophis allows to: (i) wrap an OASIS interface to exchange data with a coupled earth-system code, (ii) wrap inference models into a simple in/out interface, and (iii) emulate time evolution to synchronize connexions between earth-system and models. We set up a demonstration case with the European numerical code NEMO in which the pre-existing OASIS interface has been slightly modified. A forced global ocean model simulation is performed with regular exchanges of 2D and 3D fields with Eophis. Received data are then sent to inference models that are not implemented in NEMO. Performances of the solution will finally be assessed with references.

How to cite: Barge, A. and Le Sommer, J.: Online deployment of pre-trained machine learning components within Earth System models via OASIS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16148, https://doi.org/10.5194/egusphere-egu24-16148, 2024.

EGU24-16149 | ECS | Orals | ITS1.3/CL0.1.18

Two Methods for Constraining Neural Differential Equations 

Alistair White, Niki Kilbertus, Maximilian Gelbrecht, and Niklas Boers

Neural differential equations (NDEs) provide a powerful and general framework for interfacing machine learning with numerical modeling. However, constraining NDE solutions to obey known physical priors, such as conservation laws or restrictions on the allowed state of the system, has been a challenging problem in general. We present stabilized NDEs (SNDEs) [1], the first method for imposing arbitrary explicit constraints in NDE models. Alongside robust theoretical guarantees, we demonstrate the effectiveness of SNDEs across a variety of settings and using diverse classes of constraints. In particular, SNDEs exhibit vastly improved generalization and stability compared to unconstrained baselines. Building on this work, we also present constrained NDEs (CNDEs), a novel and complementary method with fewer hyperparameters and stricter constraints. We compare and contrast the two methods, highlighting their relative merits and offering an intuitive guide to choosing the best method for a given application.

[1] Alistair White, Niki Kilbertus, Maximilian Gelbrecht, Niklas Boers. Stabilized neural differential equations for learning dynamics with explicit constraints. In Advances in Neural Information Processing Systems, 2023.

How to cite: White, A., Kilbertus, N., Gelbrecht, M., and Boers, N.: Two Methods for Constraining Neural Differential Equations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16149, https://doi.org/10.5194/egusphere-egu24-16149, 2024.

EGU24-17852 | Orals | ITS1.3/CL0.1.18 | Highlight

FTorch - lowering the technical barrier of incorporating ML into Fortran models 

Dominic Orchard, Elliott Kasoar, Jack Atkinson, Thomas Meltzer, Simon Clifford, and Athena Elafrou

Across geoscience, numerical models are used for understanding, experimentation, and prediction of complex systems. Many of these models are computationally intensive and involve sub-models for certain processes, often known as parameterisations. Such parameterisations may capture unresolved sub-grid processes, such as turbulence, or represent fast-moving dynamics, such as gravity waves, or provide a combination of the two, such as microphysics schemes.

Recently there has been significant interest in incorporating machine learning (ML) methods
into these parameterisations. Two of the main drivers are the emulation of computationally intensive processes, thereby reducing computational resources required, and the development of data-driven parameterisation schemes that could improve accuracy through capturing ‘additional physics’.

Integrating ML sub-models in the context of numerical modelling brings a number of challenges, some of which are scientific, others computational. For example, many numerical models are written in Fortran, whilst the majority of machine learning is conducted using Python-based frameworks such as PyTorch that provide advanced ML modelling capabilities. As such there is a need to leverage ML models developed externally to Fortran, rather than the error-prone approach of writing neural networks directly in Fortran, missing the benefits of highly-developed libraries.

Interoperation of the two languages requires care, and increases the burden on researchers and developers. To reduce these barriers we have developed the open-source FTorch library [1] for coupling PyTorch models to Fortran. The library is designed to streamline the development process, offering a Fortran interface mimicking the style of the Python library whilst abstracting away the complex details of interoperability to provide a computationally efficient interface.

A significant benefit of this approach is that it enables inference to be performed on either CPU or GPU, enabling deployment on a variety of architectures with low programmer effort. We will report on the performance characteristics of our approach, both in the CPU and GPU settings and include a comparison with alternative approaches.

This approach has been deployed on two relevant case studies in the geoscience context: a gravity-wave parameterisation in an intermediate complexity atmospheric model (MiMA) based on Espinosa et al. [2], and a convection parameterisation in a GCM (CAM/CESM) based on Yuval et al. [3]. We will report on these applications and lessons learned from their development. 

[1] FTorch https://github.com/Cambridge-ICCS/FTorch
[2] Espinosa et al., Machine Learning Gravity Wave Parameterization Generalizes to Capture the QBO and Response to Increased CO2, GRL 2022 https://doi.org/10.1029/2022GL098174
[3] Yuval et al., Use of Neural Networks for Stable, Accurate and Physically Consistent Parameterization of Subgrid Atmospheric Processes With Good Performance at Reduced Precision, GRL 2021 https://doi.org/10.1029/2020GL091363

How to cite: Orchard, D., Kasoar, E., Atkinson, J., Meltzer, T., Clifford, S., and Elafrou, A.: FTorch - lowering the technical barrier of incorporating ML into Fortran models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17852, https://doi.org/10.5194/egusphere-egu24-17852, 2024.

EGU24-18444 | ECS | Posters on site | ITS1.3/CL0.1.18

Rapid Computation of Physics-Based Ground Motions in the Spectral Domain using Neural Networks 

Fatme Ramadan, Bill Fry, and Tarje Nissen-Meyer

Physics-based simulations of earthquake ground motions prove invaluable, particularly in regions where strong ground motion recordings remain scarce. However, the computational demands associated with these simulations limit their applicability in tasks that necessitate large-scale computations of a wide range of possible earthquake scenarios, such as those required in physics-based probabilistic seismic hazard analyses. To address this challenge, we propose a neural-network approach that enables the rapid computation of earthquake ground motions in the spectral domain, alleviating a significant portion of the computational burden. To illustrate our approach, we generate a database of ground motion simulations in the San Francisco Bay Area using AxiSEM3D, a 3D seismic wave simulator. The database includes 30 double-couple sources with varying depths and horizontal locations. Our simulations explicitly incorporate the effects of topography and viscoelastic attenuation and are accurate up to frequencies of 0.5 Hz. Preliminary results demonstrate that the trained neural network almost instantaneously produces estimates of peak ground displacements as well as displacement waveforms in the spectral domain that align closely with those obtained from the wave propagation simulations. Our approach also extends to predicting ground motions for ‘unsimulated’ source locations, ultimately providing a comprehensive resolution of the source space in our chosen physical domain. This advancement paves the way for a cost-effective simulation of numerous seismic sources, and enhances the feasibility of physics-based probabilistic seismic hazard analyses. 

How to cite: Ramadan, F., Fry, B., and Nissen-Meyer, T.: Rapid Computation of Physics-Based Ground Motions in the Spectral Domain using Neural Networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18444, https://doi.org/10.5194/egusphere-egu24-18444, 2024.

EGU24-19255 | Posters on site | ITS1.3/CL0.1.18

A digital twin for volcanic deformation merging 3D numerical simulations and AI 

Chiara P Montagna, Deepak Garg, Martina Allegra, Flavio Cannavò, Gilda Currenti, Rebecca Bruni, and Paolo Papale

At active volcanoes, surface deformation is often a reflection of subsurface magma activity that is associated with pressure variations in magma sources. Magma dynamics cause a change of stress in the surrounding rocks. Consequently, the deformation signals propagate through the rocks and arrive at the surface where the monitoring network records them.

It is invaluable to have an automated tool that can instantly analyze the surface signals and give information about the evolution of the location and magnitude of pressure variations in case of volcanic unrest. Inverse methods employed for this often suffer from ill-posedness of the problem and non-uniqueness of solutions.

To this end, we are developing a digital twin to use on Mount Etna volcano, combining the capability of numerical simulations and AI. Our digital twin is composed of two AI models: the first AI model (AI1) will be trained on multi-parametric data to recognize unrest situations, and the second AI model (AI2) will be trained on a large number (order 10^5 - 10^6) of 3D elastostatic numerical simulations for dike intrusions with the real topography and best available heterogeneous elastic rock properties of Mount Etna Volcano using a forward modeling approach. Numerical simulations will be performed on Fenix HPC resources using the advanced open-source multi-physics finite element software Gales.

Both AI modules will be developed and trained independently and then put into use together. After activation, AI1 will analyze the streaming of monitoring data and activate AI2 in case of a volcanic crisis. AI2 will provide information about the acting volcanic source.

The software will be provided as an open-source package to allow replication on other volcanoes. The tool will serve as an unprecedented prototype for civil protection authorities to manage volcanic crises.

How to cite: Montagna, C. P., Garg, D., Allegra, M., Cannavò, F., Currenti, G., Bruni, R., and Papale, P.: A digital twin for volcanic deformation merging 3D numerical simulations and AI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19255, https://doi.org/10.5194/egusphere-egu24-19255, 2024.

EGU24-19352 | ECS | Posters on site | ITS1.3/CL0.1.18

Learning phytoplankton bloom patterns - A long and rocky road from data to equations  

Pascal Nieters, Maximilian Berthold, and Rahel Vortmeyer-Kley

Non-linear, dynamic patterns are the rule rather than the exception in ecosystems. Predicting such patterns would allow an improved understanding of energy and nutrient flows in such systems. The Scientific Machine Learning approach Universal Differential Equation (UDE) by Rackauckas et al. (2020) tries to extract the underlying dynamical relations of state variables directly from their time series in combination with some knowledge on the dynamics of the system. This approach makes this kind of tool a promising approach to support classical modeling when precise knowledge of dynamical relationships is lacking, but measurement data of the phenomenon to be modeled is available.

We applied the UDE approach to a 22-year data set of the southern Baltic Sea coast, which constituted six different phytoplankton bloom types. The data set contained the state variables chlorophyll and different dissolved and total nutrients. We learned the chlorophyll:nutrient interactions from the data with additional forcing of external temperature, salinity and light attenuation dynamics as drivers. We used a neural network as a universal function approximator that provided time series of the state variables and their derivatives.

Finally, we recovered algebraic relationships between the variables chlorophyll, dissolved and total nutrients and the external drivers temperature, salinity and light attenuation using Sparse Identification of nonlinear Dynamics (SinDy) by Brunton et al. (2016).

The gained algebraic relationships differed in their importance of the different state variables and drivers for the six phytoplankton bloom types in accordance with general mechanisms reported in literature for the southern Baltic Sea coast. Our approach may be a viable option to guide ecosystem management decisions based on those algebraic relationships.

Rackauckas et al. (2020), arXiv preprint arXiv:2001.04385.

Brunton et al. (2016), PNAS 113.15: 3932-3937.

How to cite: Nieters, P., Berthold, M., and Vortmeyer-Kley, R.: Learning phytoplankton bloom patterns - A long and rocky road from data to equations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19352, https://doi.org/10.5194/egusphere-egu24-19352, 2024.

EGU24-19502 | ECS | Posters on site | ITS1.3/CL0.1.18

SAIPy: A Python Package for single station Earthquake Monitoring using Deep Learning 

Nishtha Srivastava, Wei Li, Megha Chakraborty, Claudia Quinteros Cartaya, Jonas Köhler, Johannes Faber, and Georg Rümpker

Seismology has witnessed significant advancements in recent years with the application of deep
learning methods to address a broad range of problems. These techniques have demonstrated their
remarkable ability to effectively extract statistical properties from extensive datasets, surpassing the
capabilities of traditional approaches to an extent. In this study, we present SAIPy, an open-source
Python package specifically developed for fast data processing by implementing deep learning.
SAIPy offers solutions for multiple seismological tasks, including earthquake detection, magnitude
estimation, seismic phase picking, and polarity identification. We introduce upgraded versions
of previously published models such as CREIME_RT capable of identifying earthquakes with an
accuracy above 99.8% and a root mean squared error of 0.38 unit in magnitude estimation. These
upgraded models outperform state-of-the-art approaches like the Vision Transformer network. SAIPy
provides an API that simplifies the integration of these advanced models, including CREIME_RT,
DynaPicker_v2, and PolarCAP, along with benchmark datasets. The package has the potential to be
used for real-time earthquake monitoring to enable timely actions to mitigate the impact of seismic
events.

How to cite: Srivastava, N., Li, W., Chakraborty, M., Cartaya, C. Q., Köhler, J., Faber, J., and Rümpker, G.: SAIPy: A Python Package for single station Earthquake Monitoring using Deep Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19502, https://doi.org/10.5194/egusphere-egu24-19502, 2024.

EGU24-20863 | ECS | Posters on site | ITS1.3/CL0.1.18

Partial land surface emulator forecasts ecosystem states at verified horizons 

Marieke Wesselkamp, Matthew Chantry, Maria Kalweit, Ewan Pinnington, Margarita Choulga, Joschka Boedecker, Carsten Dormann, Florian Pappenberger, and Gianpaolo Balsamo

While forecasting of climate and earth system processes has long been a task for numerical models, the rapid development of deep learning applications has recently brought forth competitive AI systems for weather prediction. Earth system models (ESMs), even though being an integral part of numerical weather prediction have not yet caught that same attention. ESMs forecast water, carbon and energy fluxes and in the coupling with an atmospheric model, provide boundary and initial conditions. We set up a comparison of different deep learning approaches for improving short-term forecasts of land surface and ecosystem states on a regional scale. Using simulations from the numerical model and combining them with observations, we will partially emulate an existing land surface scheme, conduct a probabilistic forecasts of core ecosystem processes and determine forecast horizons for all variables.

How to cite: Wesselkamp, M., Chantry, M., Kalweit, M., Pinnington, E., Choulga, M., Boedecker, J., Dormann, C., Pappenberger, F., and Balsamo, G.: Partial land surface emulator forecasts ecosystem states at verified horizons, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20863, https://doi.org/10.5194/egusphere-egu24-20863, 2024.

Thanks to the recent progress in numerical methods, the application fields of artificial intelligence (AI) and machine learning methods (ML) are growing at a very fast pace. The EURAD (European Joint Programme on Radioactive Waste Management) community has recently started using ML for a) acceleration of numerical simulations, b) improvement of multiscale and multiphysics couplings efficiency, c) uncertainty quantification and sensitivity analysis. A number of case studies indicate that use of ML based approaches leads to overall acceleration of geochemical and reactive transport simulations from one to four orders of magnitude. The achieved speed-up depends on the chemical system, simulation code, problem formulation and the research question to be answered. Within EURAD-DONUT (Development and Improvement Of Numerical methods and Tools for modelling coupled processes), a benchmark is on-going to coordinate the relevant activities and to test a variety of ML techniques for geochemistry and reactive transport simulations in the framework of radioactive waste disposal. It aims at benchmarking several widely used geochemical codes, at generating high-quality geochemical data for training/validation of existing/new methodologies, and at providing basic guidelines about the benefits, drawbacks, and current limitations of using ML techniques.

A joint effort has resulted in the definition of benchmarks of which one is presented here. The benchmark system is relevant to the sorption of U in claystone formations (e.g. Callovo-Oxfordian, Opalinus or Boom clay). Regarding the chemical complexity, a system containing Na-Cl-U-H-O is considered as the base case, and a more complex system with the addition of calcium and carbonate (CO2) to change aqueous speciation of U. Parameters of interest, among others, are the resulting concentrations of U sorbed on edges (surface complexes), of U on ion exchange sites, and the amount of metaSchoepite, with the resulting Kd’s. Following aspects are discussed: (i) Streamline the production of high-quality consistent training datasets, using the most popular geochemical solvers (PHREEQC, ORCHESTRA and GEMS). (ii) The use of different methods (e.g. Deep Neural Networks, Polynomial Chaos Expansion, Gaussian Processes, Active Learning, and other techniques to learn from the generated data. (iii) Setup appropriate metrics for the critical evaluation of the accuracy of ML models. (iv) Testing the accuracy of predictions for geochemical and reactive transport calculations. 

How to cite: Laloy, E. and Montoya, V. and the EURAD-DONUT Team: Machine learning based metamodels for geochemical calculations in reactive transport models: Benchmark within the EURAD Joint Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21545, https://doi.org/10.5194/egusphere-egu24-21545, 2024.

CL1.1 – Past Climate - Deep Time

EGU24-475 | ECS | Orals | CL1.1.1

Modelled asymmetric Antarctic glaciation during the Eocene-Oligocene Transition 

Hanna Knahl, Gerrit Lohmann, Johann Philipp Klages, Lu Niu, and Paul Gierz

The evolution from greenhouse to icehouse climate during the Eocene-Oligocene Transition (EOT) (~34.4–33.7 Ma) is associated with a drastic cooling of global climate and significant ice sheet build-up. However, extent and location of the such early permanent ice masses are still largely unknown. Here, we coupled the AWI-Earth System Model with the Parallel Ice Sheet Model to draw a bigger picture of the relationship between Antarctic ice sheet presence and global climate dynamics during the EOT and the Early Oligocene Glacial Maximum (EOGM) just afterwards.

Our model results reveal an asymmetric ice sheet cover, and notably, identify a CO2-threshold necessary for initiating marine-terminating ice sheet advance onto West Antarctic continental shelves—one major component in Earth's paleoclimatic puzzle. We identify the Southern Ocean dynamics as a direct result of Southern gateway configurations to be a key driver of East Antarctic ice sheet growth. Our Antarctic climate and vegetation simulations match available proxy data well for this period of fundamental change. Therefore, our new simulations significantly contribute to a much deeper understanding of Antarctic ice sheet growth during the EOT and subsequent EOGM, thereby highlighting the importance of Southern high latitude environmental change for controlling Earth’s climate dynamics.

How to cite: Knahl, H., Lohmann, G., Klages, J. P., Niu, L., and Gierz, P.: Modelled asymmetric Antarctic glaciation during the Eocene-Oligocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-475, https://doi.org/10.5194/egusphere-egu24-475, 2024.

EGU24-988 | ECS | Posters on site | CL1.1.1

Opportunistic Model Intercomparison of the Miocene Ocean Circulation – MioMIP1 

Trusha Naik, Agatha de Boer, Helen Coxall, Natalie Burls, Catherine Bradshaw, Yannick Donnadieu, Alexander Farnsworth, Amanda Frigola, Nicholas Herold, Matthew Huber, Pasha Karami, Gregor Knorr, Allegra LeGrande, Daniel Lunt, Matthias Prange, and Yurui Zhang

During the Miocene epoch (~23-5 Ma), the Earth experienced a notably warmer climate, with global surface temperatures ranging approximately 4°C to 8°C higher than pre-industrial levels, accompanied by atmospheric CO2 concentrations in the range of 400-800 ppm. Throughout this period, tropical ocean gateways underwent constriction or closure, while high-latitude gateways expanded. These developments likely played a pivotal role in shaping the modern ocean circulation structure, with strong bipolar hemispheric overturning in the Atlantic, although the precise mechanisms remain poorly understood. This study explores Miocene ocean circulation through an opportunistic climate model intercomparison (MioMIP1), encompassing 14 simulations that use different paleogeographies, CO2 levels, and vegetation distributions. A consistent feature across all models is the fresher-than-modern Arctic and a resulting increased freshwater export to the North Atlantic. Consequently, the Atlantic Meridional Overturning Circulation (AMOC) appears markedly weaker than its modern counterpart in all simulations, ranging from approximately 1 to 16 Sv. However, there is no discernible correlation between the transport of Arctic freshwater to the Atlantic and the strength of the AMOC across the simulations. Similarly, contrary to earlier suggestions, our analysis reveals that neither Panama nor the Tethys gateway exerts a consistent impact on circulation across the simulations. This implies that the influence of these three straits on circulation dynamics also depends on other factors such as background palaeogeography, CO2 levels, vegetation, or model physics and requires further study. In three out of the 13 simulations, deep overturning in the North Pacific (PMOC) is observed, ranging from approximately 5 to 10 Sv. Notably, in the North Atlantic, the simulations with a higher salinity have a stronger AMOC, and although this is not observed as distinctly in the North Pacific, the simulations with a PMOC exhibit a reduced salinity contrast between the North Pacific and North Atlantic and highlight the salinity feedback in play. A proto-AMOC appears to be developing in most of the simulations, albeit weak. This indicates that while the AMOC began to take shape during the Miocene, it likely attained its modern strength during the late Miocene.

How to cite: Naik, T., de Boer, A., Coxall, H., Burls, N., Bradshaw, C., Donnadieu, Y., Farnsworth, A., Frigola, A., Herold, N., Huber, M., Karami, P., Knorr, G., LeGrande, A., Lunt, D., Prange, M., and Zhang, Y.: Opportunistic Model Intercomparison of the Miocene Ocean Circulation – MioMIP1, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-988, https://doi.org/10.5194/egusphere-egu24-988, 2024.

The Cenozoic era reflects a discernible global cooling trend attributed to the prolonged decrease in atmospheric pCO2. Various theories have been proposed to elucidate the mechanisms behind this reduction, with a focus on the substantial carbon exchange between the atmosphere and the global ocean. However, the carbon storage dynamics in the abyssal ocean during the geological past remain enigmatic. Employing a state-of-the-art ocean-biogeochemical model and leveraging recently published paleoceanographic records, this study unveils distinct basin-scale carbon storage patterns in the Pacific and Atlantic in a hypothetical no-Tibetan-Plateau scenario. Through sensitivity experiments, our findings suggest that orographic forcing, specifically the absence of the Tibetan Plateau, may have triggered a significant carbon transition from the Atlantic to the Pacific. This transition appears to be driven by a substantial reorganization of deep ocean overturning circulation. Importantly, this observed phenomenon could be a contributing factor to the long-term reduction in atmospheric pCO2.

How to cite: Du, J. and Tian, J.: Dramatic transition of abyssal oceanic carbon reservoir driven by deep ocean overturning circulation during the Cenozoic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2334, https://doi.org/10.5194/egusphere-egu24-2334, 2024.

EGU24-3209 | ECS | Orals | CL1.1.1 | Highlight

A unique look into European middle Eocene weather; Comparing a new synoptic-scale proxy record to simulated daily conditions. 

Michiel Baatsen, Nick van Horebeek, Martin Ziegler, Niels de Winter, Robert Speijer, and Johan Vellekoop

In addition to improving our general understanding of the climate system, the study of past warm climates is often stated relevant due to the possible resemblances to various future scnenarios. The comparison between proxy records and climate model simulations offers opportunities for validation beyond the boundaries of present climatic conditions. Besides their scarcity in both spatial and temporal coverage, existing proxies pre-dating the Pleistocene only provide an integrated signal typically over 1000 years or more. Climate model simulations provide much more data beyond that which can be validated using proxies, that is therefore often not considered in palaeoclimate studies.
A unique opportunity presents itself with a new ultra-high resolution record of the middle Eocene, obtained from the giant marine gastropod Campanile giganteum. Found in the Paris Basin (palaeolatitude 40-45N), these gastropods lived in a shallow marine environment and reached growth rates of over 600mm/year. Well-preserved fossils, in combination with such high growth rates, provide the first record to our knowledge resolving weather-timescale variability in the Eocene.
In this study, we interpret this snapshot of European middle Eocene weather and compare our findings to daily model fields using the CESM 1.0.5. We continued existing 38Ma simulations using 4 times pre-industrial CO2 and CH4, which were shown previously to be a good match with the middle Eocene climate (see: Baatsen et al. 2020, Climate of the Past, doi: 10.5194/cp-16-2573-2020). The proxy record shows distinctly different seasonalities of temperature and salinity over central Europe in the middle Eocene. We can interpret these patterns as indications of a monsoonal climate with notably high variability in summer precipitation. Such a climatic regime is supported by the model, which also shows monsoonal conditions over central Europe as well as northern Africa. The agreement between the proxy record and the simulations, on both seasonal and synoptic scales, thus promotes further interpretation of these model results on an entirely new scale.

How to cite: Baatsen, M., van Horebeek, N., Ziegler, M., de Winter, N., Speijer, R., and Vellekoop, J.: A unique look into European middle Eocene weather; Comparing a new synoptic-scale proxy record to simulated daily conditions., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3209, https://doi.org/10.5194/egusphere-egu24-3209, 2024.

EGU24-4363 | ECS | Posters on site | CL1.1.1

Global impacts of a subaerial Barents Sea on the mid-Pliocene climate 

Siqi Li, Xu Zhang, Yong Sun, Øyvind Lien, Berit Hjelsturn, Christian Stepanek, Evan Gowan, and Yongqiang Yu

A long-standing challenge for mid-Pliocene climate simulations is large underestimation of simulated surface warming in the Nordic Seas in comparison to sea surface temperature (SST) proxy records (Dowsett et al., 2013; McClymont et al., 2020). Previous modelling studies have proposed that geographic changes in the Barents-Kara Sea are of great importance for surface temperature change in the Nordic Seas (Hill, 2015). That is, changing the Barents Sea from a marine to a subaerial setting can give rise to evident warming in the Nordic Seas (Hill, 2015). Nevertheless, this geographic change has so far not been well considered in the Pliocene Modelling Intercomparison Project (Dowsett et al., 2016; Haywood et al., 2016 a, b), potentially due to the lack of quantitative reconstruction of this paleogeographic change. Recently, Lien et al. (2022) provided such reconstruction, which enables a test of the impact of a subaerial Barents Sea on mid-Pliocene climate. Based on iCESM1.2, we accordingly conducted sensitivity experiments where we changed bathymetry in the eastern Nordic Sea and topography in the Barents-Kara Sea region in a setup of otherwise unaltered PRISM4 mid-Pliocene boundary conditions. We demonstrate that the sea surface temperatures were warmer than pre-industrial values and Nordic Seas had warmed significantly. Our results hint that a subaerial Barents-Kara Sea might contribute to the data-model SST mismatch during the mid-Pliocene.

References:

Dowsett, H., Dolan, A., Rowley, D., Moucha, R., Forte, A. M., Mitrovica, J. X., . . . Haywood, A. (2016). The PRISM4 (mid-Piacenzian) paleoenvironmental reconstruction. Climate of the Past, 12(7), 1519-1538. doi:10.5194/cp-12-1519-2016

Dowsett, H. J., Foley, K. M., Stoll, D. K., Chandler, M. A., Sohl, L. E., Bentsen, M., . . . Zhang, Z. S. (2013). Sea Surface Temperature of the mid-Piacenzian Ocean: A Data-Model Comparison. Scientific Reports, 3. doi:ARTN 2013 10.1038/srep02013

Haywood, A. M., Dowsett, H. J., & Dolan, A. M. (2016). Integrating geological archives and climate models for the mid-Pliocene warm period. Nature Communications, 7. doi:ARTN 1064610.1038/ncomms10646

Haywood, A. M., Dowsett, H. J., Dolan, A. M., Rowley, D., Abe-Ouchi, A., Otto-Bliesner, B., . . . Salzmann, U. (2016). The Pliocene Model Intercomparison Project (PlioMIP) Phase 2: scientific objectives and experimental design. Climate of the Past, 12(3), 663-675. doi:10.5194/cp-12-663-2016

Hill, D. J. (2015). The non-analogue nature of Pliocene temperature gradients. Earth and Planetary Science Letters, 425, 232-241. doi:10.1016/j.epsl.2015.05.044

Lien, O. F., Hjelstuen, B. O., Zhang, X., & Sejrup, H. P. (2022). Late Plio-Pleistocene evolution of the Eurasian Ice Sheets inferred from sediment input along the northeastern Atlantic continental margin. Quaternary Science Reviews, 282. doi:ARTN 10743310.1016/j.quascirev.2022.107433

McClymont, E. L., Ford, H. L., Ho, S. L., Tindall, J. C., Haywood, A. M., Alonso-Garcia, M., . . . Zhang, Z. S. (2020). Lessons from a high-CO2 world: an ocean view from ∼ 3 million years ago. Climate of the Past, 16(4), 1599-1615. doi:10.5194/cp-16-1599-2020

How to cite: Li, S., Zhang, X., Sun, Y., Lien, Ø., Hjelsturn, B., Stepanek, C., Gowan, E., and Yu, Y.: Global impacts of a subaerial Barents Sea on the mid-Pliocene climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4363, https://doi.org/10.5194/egusphere-egu24-4363, 2024.

The Indo-Pacific warm pool plays a crucial role in regulating heat and water vapor exchange between low and high latitudes. Since the late Miocene epoch, the tectonic evolution of the Indonesian seaway, particularly its gradual closure, has controlled the development of the Indo-Pacific warm pool, leading to altered current patterns between the western Pacific and eastern Indian Oceans. Reconstructed palaeoceanographic records along with numerical simulation experiments have revealed that during the Pliocene period, there was a shift in water source for Indonesian throughflow from high temperature and high salinity South Equatorial Pacific waters to low temperature and low salinity North Equatorial Pacific waters. The closure of the Indonesian Seaway may have shifted the atmospheric convective center from the east Indian Ocean to the West Pacific Ocean, leading to the gradual strengthening of the Western Pacific Warm Pool while reducing surface temperatures and subsurface salinity in the eastern Indian Ocean. The synchronous evolution between the Indonesian Seaway closure and the throughflow not only impacts arid climates in northwest Australia and East Africa but also reduces heat transport towards higher latitudes in the Northern Hemisphere. Previous studies have indicated that changes in meridional heat transport caused by the closure of the Indonesian seaway may contribute to the formation of the Arctic ice sheet; however, further study of the influence of this process and the degree of influence is still weak.

Here, we analyzed the Mg/Ca ratio of surface and subsurface foraminifera shells of ODP (Ocean Drilling Program) sites 807 and 762 in the western Equatorial Pacific and Eastern Indian Ocean, and reconstructed changes in Sea Surface Temperature (SST) and Thermocline Water Temperature (TWT) between 6-3.8Ma. It was observed that ODP site 807 experienced a rise in surface water temperature from 5.2 to 4.9Ma, while ODP site 762 witnessed a drop in surface seawater temperature during this period. Additionally, both sites exhibited a deepening thermocline between 5-4.5Ma. These findings indicate that there was a contraction of the Indonesian seaway during 5.2-4.9Ma, leading to warm water accumulation within the Western Pacific Warm Pool, which subsequently increased surface water temperature in this region while decreasing it in the eastern Indian Ocean, thereby strengthening the Western Pacific Warm Pool. We performed a group of numerical simulation sensitivity experiments on the opening and closing of the Indonesian Seaway. The results showed that when the Indonesian Seaway is closed, the sea surface temperature of the Pacific Ocean and the Indian Ocean will both increase. However, for the subsurface layer, the temperature of the subsurface water in the Pacific Ocean increased, while that of the Indian Ocean decreased. At the same time, the West Pacific Warm Pool strengthening caused by the closure of the Indonesian Seaway was observed clearly.

Keywords: Indonesian Seaway, Indonesian Throughflow, Indo-Pacific Warm Pool, Mg/Ca ratio.

How to cite: Ding, Y., Tian, J., and Wei, J.: Upper ocean temperature change caused by the closing of the Indonesian Seaway from the late Miocene to early Pliocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4920, https://doi.org/10.5194/egusphere-egu24-4920, 2024.

EGU24-4931 | ECS | Posters on site | CL1.1.1

Influence of Tropical Seaways on the Climate and Vegetation in Tropical Africa and South America  

Ning Tan, Huan Li, Zhongshi Zhang, Haibin Wu, Gilles Ramstein, Yong Sun, Zhilin He, Baohuang Su, Zijian Zhang, and Zhengtang Guo

The tectonically induced closure/constriction of the Central American Seaway (CAS) and Indonesian Seaway (Indo) during the early to mid-Pliocene has been associated with many climatic events, such as the onset of Northern Hemisphere glaciation, the intensification of the Atlantic meridional overturning circulation (AMOC) and Australian aridification. However, studies on how the closure/constriction of tropical seaways affects the tropical climate system are still sparse and not systematic. Previous studies have linked the constriction of Indo to the aridification over East Africa and discussed the role of CAS closure in affecting the moisture supply over South America, but the underlying mechanism and combined effect of both tropical seaways are not well studied. In this study, we evaluate the impacts of tropical seaways' closure/constriction and distinguish the relative roles of CAS and Indo on climate in tropical Africa and South America using the NorESM-L Atmosphere-Ocean General Circulation Model (AOGCM) and a dynamic vegetation model (LPJ-GUESS). Our results show that the closure of the CAS leads mainly to aridification in northeastern Brazil, resulting in an expansion of tropical xerophytic shrubland and savanna in this region. The narrowing of the Indo mainly leads to enhanced aridification in eastern tropical Africa and reduces the extent of tropical forests in eastern and northern tropical Africa, which is generally consistent with the data. The closure/narrowing of the two tropical seaways results in a superposition of the individual seaway's effect, particularly over the northeastern Brazil region, which exhibits enhanced aridification compared to the closure of the individual CAS. The seaways’ changes are shown to be pivotal for the evolution of climate and vegetation over East Africa and northeastern South America to contemporary conditions.

How to cite: Tan, N., Li, H., Zhang, Z., Wu, H., Ramstein, G., Sun, Y., He, Z., Su, B., Zhang, Z., and Guo, Z.: Influence of Tropical Seaways on the Climate and Vegetation in Tropical Africa and South America , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4931, https://doi.org/10.5194/egusphere-egu24-4931, 2024.

EGU24-5006 | Orals | CL1.1.1 | Highlight

Origin and Evolution of the North Atlantic Oscillation 

Ji Nie and Zhihong Song

The North Atlantic Oscillation (NAO) is the dominant variability mode in the North Atlantic region and plays important roles in weather and climate. When did the NAO first emerge in the past, and how did it evolve over geological timescales? To answer these questions, we examined a set of time-slice paleoclimate simulations with varying continental configurations from ~160 million years ago (Ma). We show that the present-day-like NAO mode emerges stably at around 80 Ma when the North Atlantic Ocean is wide enough to form a high-pressure system that separates the North Atlantic jet from the Euro-Asia jet. A set of idealized simulations confirms that a robust NAO mode will emerge when the width of the ocean basin is greater than 40°. This study depicts the evolutionary history of NAO over geological time and reveals the essential nature of NAO and its relationship with topography.

How to cite: Nie, J. and Song, Z.: Origin and Evolution of the North Atlantic Oscillation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5006, https://doi.org/10.5194/egusphere-egu24-5006, 2024.

EGU24-5826 | ECS | Posters on site | CL1.1.1

Response of Late-Eocene warmth to incipient glaciation on Antarctica 

Dennis Vermeulen, Michiel Baatsen, and Anna von der Heydt

The Eocene-Oligocene Transition is marked by a sudden δ18O excursion occurring in two distinct phases: a precursor event at 34.15±0.04 Ma and the Earliest Oligocene oxygen Isotope Step at 33.65±0.04 Ma. These events signal a shift from the warm Late-Eocene greenhouse climate to cooler conditions, with temperature decreases of 3-5 °C, and the emergence of the first continent-wide Antarctic Ice Sheet (AIS). Despite clear evidence from proxy data, general circulation models (GCMs) struggle to replicate this Antarctic transition accurately, failing to capture the shift from warm, ice-free to cold, glaciated conditions. Even with unrealistically low pCO2 levels, Late-Eocene Antarctic summers in GCMs remain too warm and moist for snow or ice to survive. This study evaluates CESM1.0.5 simulations conducted by Baatsen et al. (2020), using a 38 Ma geo- and topographical reconstruction, considering different radiative (4 pre-industrial carbon levels (PIC) and 2 PIC) and orbital (present-day insolation and low Antarctic summer insolation) forcings. The climate is found to be highly seasonal, characterised by hot and wet summers and cold and dry winters. While reduced radiative and summer insolation forcing weaken this seasonality, the persistent atmospheric circulation still impedes ice sheet growth by limiting summer snow survival. For that reason, a new simulation is conducted with regional, moderately-sized ice sheets imposed on the continent, in order to investigate their stability and their influence on the atmospheric circulation. These ice sheets demonstrate self-sustaining and even expansion potential under 2 PIC and low summer insolation conditions. However, correlating resulting temperature and precipitation patterns with proxy data proves challenging, given the absence of terrestrial proxies. Extended simulations with coupled GCM-ISM models are therefore recommended, allowing for more dynamic atmosphere-ice-ocean-vegetation feedback mechanisms and dynamic radiative and orbital forcing.

How to cite: Vermeulen, D., Baatsen, M., and von der Heydt, A.: Response of Late-Eocene warmth to incipient glaciation on Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5826, https://doi.org/10.5194/egusphere-egu24-5826, 2024.

EGU24-6286 | ECS | Orals | CL1.1.1 | Highlight

A wet or dry European and Northern African climate during the Miocene Climatic Optimum 

R. Paul Acosta, Natalie Burls, Matthew Pound, Catherine Bradshaw, and Sarah Feakins

End-of 21st Century hydroclimate projections suggest an expansion of the subtropical dry zone, with Europe and Northern Africa becoming drier. However, paleoclimate evidence primarily from paleobotanical assemblages from a past warm climate period, the Miocene Climatic Optimum (MCO) ~14-17 Ma, suggests both regions were instead wet and humid environments. Here, we simulate the MCO with the Community Earth System Model (CESM 1.2) forced by compiled sea surface temperature (SST) proxy data that are 5-6°C warmer than Preindustrial in the North Atlantic (NA). Given these boundary conditions, the climate model better matches paleobotanical proxy evidence for wetter continents relative to coupled simulations. The prescribed SST simulations show enhanced ocean evaporation and integrated water vapor flux that overrides any drying effects associated with warming, increasing evaporation on land. The vegetation model (BIOME4) forced by the climatologies from our simulations predicts a mixed forested landscape dominated Europe and Northern Africa during the MCO, with largely consistent paleobotanical evidence. This proxy-model study of MCO climate reveals the potential for wetter Mediterranean climates associated with warming and presents an alternative scenario from future drying projections. The critical difference identified in our MCO simulations is localized SST warming governing regional climate.

How to cite: Acosta, R. P., Burls, N., Pound, M., Bradshaw, C., and Feakins, S.: A wet or dry European and Northern African climate during the Miocene Climatic Optimum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6286, https://doi.org/10.5194/egusphere-egu24-6286, 2024.

EGU24-6305 | ECS | Posters on site | CL1.1.1

Tropical cloud feedback in near-Snowball Earth waterbelt states 

Johannes Hörner and Aiko Voigt

Waterbelt states are an alternative scenario for Snowball Earth, where a narrow strip of ocean remains ice-free at the equator, providing a robust solution for the survival of life. Recent studies have shown that waterbelt states can be stabilised by subtropical low-level clouds, because they weaken the ice-albedo feedback created by the expanding sea ice beneath the clouds. Thick subtropical clouds are therefore needed to stabilise the waterbelt state.

However, clouds also have the opposite effect over the open ocean equatorward of the ice margin. Here they provide a destabilising cloud feedback that supports the ice-albedo feedback in favour of a Snowball Earth. When sea ice enters the subtropics, this effect becomes particularly strong, as the vertical structure and the phase partitioning of tropical clouds begin to change. As a result, tropical clouds can ultimately determine the stability of the waterbelt state.

Here we show a preliminary analysis of simulations with two versions of the atmospheric ICON model using the same setup, a slab-ocean aquaplanet with a thermodynamic sea-ice model and over a broad range of atmospheric CO2 concentrations. While waterbelt states are easily found in ICON-A, they are absent in ICON-ESM due to a difference in tropical clouds. The tropical cloud feedback will be analysed by means of cloud controlling factors, and simulations with the cloud locking method will be employed to demonstrate the critical role of tropical cloud feedback for waterbelt states. 

How to cite: Hörner, J. and Voigt, A.: Tropical cloud feedback in near-Snowball Earth waterbelt states, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6305, https://doi.org/10.5194/egusphere-egu24-6305, 2024.

EGU24-6581 | ECS | Orals | CL1.1.1

Early Paleogene Climate: A Glimpse of Extreme Warming 

Jacob Slawson and Piret Plink-Bjorklund

As the world warms, the Earth system moves towards a climate state without societal precedent. This challenges predictions of the future, as climate models need to be tested and calibrated with real-world data from high carbon dioxide climates. Despite the many advances in climate modeling, predictions of precipitation have particularly high uncertainties. Earth history provides an opportunity to observe how the Earth system responded to high greenhouse gas emissions, enabling us to better predict how it may do so in the future. Here, we compile global terrestrial proxy data from the Early Paleogene (66-49 Ma), a period with a warm climate overprinted by multiple rapid global warming events and suggested as a possible analogue for future worst-case scenarios. We show surprising results in the timing and duration of dramatic shifts in the hydrologic cycle occurring well prior to maximum temperatures and persisting well beyond. We provide a glimpse of an extremely warm Earth with ever-wet or monsoonal conditions in the northern and southern polar regions, and sustained aridity interrupted by extreme rainfall events at mid-latitudes. Our results indicate inconsistencies between proxy data and state-of-the-art paleoclimate models that are commonly used to predict and understand future climate change. Our focus on precipitation intermittency and intensity provides new data on long-term precipitation trends in high greenhouse gas climates to help address large uncertainties in future precipitation trends. A high-resolution focus on mid-latitude proxy data produces trends where some locations become drier during the PETM, while others become wetter, indicating dynamically-driven changes that differ from the “wet-gets-wetter, dry-gets-dryer" thermodynamic response on a regional scale.  

How to cite: Slawson, J. and Plink-Bjorklund, P.: Early Paleogene Climate: A Glimpse of Extreme Warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6581, https://doi.org/10.5194/egusphere-egu24-6581, 2024.

Tropical precipitation is profoundly influenced by continental evolution across geological time scales. However, the effects of Australia’s drift on warm pool precipitation remains poorly understood. Using a fully coupled climate model with realistic geography, our results reveal a significant amplification of the seasonal migrations of warm pool precipitation in longitude and latitude due to the equatorward drift of Australia. Notably, the observed feature aligns with paleoclimate simulations over the past 40 million years, highlighting the dominant role of Australia’s drift in comparison to the other continental drifts. This study provides insight into how Australia’s drift has shaped the characteristics of warm pool precipitation over the geological timescales.

How to cite: Yin, Z. and Nie, J.: Australia’s drift as a pacemaker for the seasonal variability of warm pool precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7113, https://doi.org/10.5194/egusphere-egu24-7113, 2024.

EGU24-7232 | ECS | Posters on site | CL1.1.1

North Pacific ENSO Teleconnection to Mediterranean Climates of North America in Late Cretaceous Greenhouse 

Jianming Qin, Yuan Gao, Xiaojing Du, and Chengshan Wang

The El Niño-Southern Oscillation (ENSO) influences the world through its teleconnection. Forced by global warming and rising atmospheric CO2 levels, the evolution of ENSO is still under debate. ENSO records in deep-time greenhouse climates can enhance the understanding of ENSO and its teleconnection under global warming.

This research analyzes Earth System Model (ESM) outputs of Late Cretaceous to show ENSO teleconnection between North Pacific and Mediterranean Climate region of North America (MCNA) under greenhouse gas and paleogeographic forcing. ESM outputs show 2.1-3.2-year ENSO-band cycles in both sea surface temperature (SST) and precipitation in MCNA, which are consistent with records from high-resolution sedimentary archives. The simulated ENSO teleconnection to Late Cretaceous MCNA is more influenced by the Subtropical High than the Aleutian Low. This is thought to be related to paleogeographic forcing, where a closed polar-ward seaway results in a warmer sub-polar Pacific and a more robust Aleutian Low over it. Consequently, under the remote forcing of ENSO, the Subtropical High shifts the Westerlies longitudinally, leading to alterations in both moisture and thermal transportation, which in turn changes the winter precipitation of MCNA.

This study reveals that ENSO teleconnections remain robust under Late Cretaceous greenhouse climates, and in comparison with today, forcing from the subtropics played a more significant role in affecting the evolution of North American climate.

How to cite: Qin, J., Gao, Y., Du, X., and Wang, C.: North Pacific ENSO Teleconnection to Mediterranean Climates of North America in Late Cretaceous Greenhouse, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7232, https://doi.org/10.5194/egusphere-egu24-7232, 2024.

Maintaining global freshwater conservation in climate models is crucial for accurately simulating Earth's hydrological cycle. This property particularly deserves specific attention in the deep-time paleoclimate simulations for the different geographies that changes the river route to the ocean. Changes in the volume of runoff directly exert significant impact on the ocean circulation. Large uncertainties in paleo-topography causes the uncertainties in runoff, but the latter receives less attention in the model simulations. To investigate the effects of the uncertainties on the model simulations, climate simulations of the Pre-Industrial (PI) and the Middle Miocene Climatic Optimum (MMCO) are compared by two sets of experiments —— freshwater conservative and non-conservative experiments that with sufficient and insufficient runoff import to the ocean model, respectively. Responses of the differences between the MMCO and the PI to the runoff changes are investigated. For the mean state, large qualitive and quantitative differences appear in the North Atlantic. Compared to the non-conservative experiments, the conservative experiments show the reduced salinity in the North Atlantic and collapsed Atlantic Meridional Overturning Circulation (AMOC), in contrast to the high salinity distribution and much strong AMOC in the non-conservative experiments. These differences lead to the discrepancies in volume transport through the oceanic seaway, as well as contribute to the temperature, sea ice and surface albedo changes in different amplitude in the North Atlantic. Although the climatic variabilities are affected by the runoff changes, enhanced Atlantic Multidecadal Oscillation (AMO) and reduced El Niño–Southern Oscillation (ENSO) are simulated in the MMCO regardless of the quality of freshwater conservation. Besides, the MMCO simulations show that the intensity of the Asian monsoon is greater in the South Asia and lower in the East Asia compared to PI. The study suggests that runoff changes have great effect on the climate change in the North Atlantic and need extra attention in the paleoclimate study.

How to cite: Wei, J.: Effects of Runoff Changes on the Climate Simulations of the Middle Miocene Climate Optimum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7590, https://doi.org/10.5194/egusphere-egu24-7590, 2024.

EGU24-8512 | ECS | Orals | CL1.1.1

The role of paleogeography and CO2 on Eocene deep-sea temperatures: A model-proxy comparison study 

Eivind Olavson Straume, Aleksi Nummelin, Victoria Taylor, Anna Nele Meckler, Zijian Zhang, and Zhongshi Zhang

We present new analysis of climate model simulations for the Eocene (~56 – 34 Ma) and investigate the relative role of atmospheric pCO2 and changes in paleogeography on ocean circulation and deep-sea temperatures. The Early Eocene experienced warm greenhouse conditions, followed by cooling towards the Late Eocene, leading to the formation of land-based ice sheets near the Eocene–Oligocene Transition. The cooling was largely controlled by decreasing atmospheric pCO2 but was also likely influenced by changes in ocean circulation caused by paleogeographic changes, including the opening and closing of oceanic gateways. Changes in ocean circulation influence the distribution of heat in the surface ocean but also the storage of heat in the deep ocean and are crucial to account for in order to reproduce the Eocene climatology. Reconstructed deep-sea temperatures can thereby provide crucial benchmark constraints on ocean circulation simulated by climate models.
In this study, we analyze a series of simulations using the Norwegian Earth System Model (NorESM-F), run with different paleogeographies, pCO2, and realistic oceanic gateway configurations. Our results show that changes in deep sea temperatures caused by CO2 perturbations are sensitive to oceanic gateway configurations and corresponding ocean circulation patterns. Specifically, reducing pCO2 in simulations where the paleogeography allow for an active AMOC yields less changes in mean deep-sea temperature than simulations without AMOC, which show significant mean deep-sea cooling. This is related to changes in ventilation and deep-water formation. The modelled changes vary on regional and basin scale, and we compare the model simulations to new clumped isotope temperature reconstructions from a variety of drill sites in the global ocean with the aim to understand the mechanisms causing the observed deep sea temperature changes.

How to cite: Straume, E. O., Nummelin, A., Taylor, V., Meckler, A. N., Zhang, Z., and Zhang, Z.: The role of paleogeography and CO2 on Eocene deep-sea temperatures: A model-proxy comparison study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8512, https://doi.org/10.5194/egusphere-egu24-8512, 2024.

Oceanic Anoxic Event 2 (OAE2) is one of the largest disruptions for the global carbon cycle in the mid-Cretaceous, which was linked to global warming and nutrient release from continental weathering. However, their respective contributions to the seafloor anoxia remain unclear. Here we perform transient numerical simulations using an intermediate-complexity Earth system model to study their influences on the mid-Cretaceous OAE2. The modeling results show that global warming due to carbon dioxide degassing could influence the seafloor oxygen contents distinctly through the ocean circulation change, but has a minor influence on the seafloor anoxia during the OAE2. The phosphate due to continental weathering associated with global warming added to the ocean further decreases the seafloor oxygen content, especially leading to the North Atlantic seafloor anoxic area expansion and the anoxia of the Southeastern Pacific Basin. When different continental weathering rates are taken into account, the modeled anoxic area from simulations with an increase of approximately 1.3 to 1.7 times the pre-OAE2 level is comparable with the estimate based on proxies, which tentatively constrains the continental weathering rate during the OAE2. This simulation would enhance our understanding of the intricate biological and geochemical processes in the oceans as the increasing atmospheric carbon dioxide concentrations.

How to cite: Cui, Q., Zhang, J., and Hu, Y.: Transient modeling for the ocean redox condition during the mid-Cretaceous oceanic anoxic event 2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9441, https://doi.org/10.5194/egusphere-egu24-9441, 2024.

EGU24-9688 | ECS | Posters on site | CL1.1.1

Sensitivity of mid-Miocene simulations to different continental configurations 

Martin Renoult and Agatha de Boer

The Langhian (15.98 - 13.82 Ma) was a stage of the mid-Miocene characterized by higher atmospheric CO2 concentrations than modern days and substantially warmer surface temperatures. The mid-Miocene has garnered growing attention as a potential analog for future climate change. Several climate models have assessed the influence of CO2 and geography on the Miocene warmth. In this study, we simulated the Langhian using a new unpublished paleogeography. This configuration notably features shallower and narrower access to the Arctic Ocean than has been previously documented. Despite CO2 concentrations equivalent to three times the pre-industrial levels (840 ppm) and the absence of ice sheets, we observe persistent sea ice in the Arctic Ocean and cooling of the Northern Atlantic Ocean. This cooling is related to the collapse of the Atlantic meridional ocean circulation. Conversely, a robust Pacific meridional ocean circulation emerges, which is less frequently observed in Miocene simulations. We investigate the reasons behind such behavior, by notably widening and deepening the Fram Strait; forcing a fixed, warmer vegetation; using a more recent atmospheric model with improvement to the physics. These adjustments underscore the critical role of geography in achieving an accurate simulation of the Miocene and facilitating more precise data-model comparisons.

How to cite: Renoult, M. and de Boer, A.: Sensitivity of mid-Miocene simulations to different continental configurations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9688, https://doi.org/10.5194/egusphere-egu24-9688, 2024.

EGU24-10037 | Orals | CL1.1.1

Reassessing Paleocene CO2 and Carbon Cycling using Process-Informed Joint Proxy Inversion 

Gabriel Bowen, Dustin Harper, Jiawei Da, and Julia Kelson

The Paleocene Epoch represents a transitional Earth system state featuring climatic relaxation between the extreme warmth of the Late Cretaceous and Early Eocene. Carbon isotope and sedimentological data have been invoked as evidence for elevated organic carbon burial and CO2 drawdown throughout the early Paleocene, constituting a potential driver of and/or feedback on climate change. Despite this, quantitative proxy reconstructions of Paleocene atmospheric CO2 concentrations have remained sparse, limiting our ability to test hypotheses for the role of carbon cycle change in Paleocene Earth system change.

Here we produce quantitative CO2 reconstructions spanning the Paleocene by combining data from marine (foraminiferal calcite) and terrestrial (pedogenic carbonate) proxy systems. We integrate data from these proxy systems, together with complementary paleo-environmental proxy data, using newly developed proxy system models implemented within the Bayesian Joint Proxy Inversion (JPI) framework. Although each individual proxy system is under-constrained, the combination of information from distinct systems and constraints provided by ancillary data produces a coherent, well-resolved paleo-CO2 reconstruction. The record suggests strong coupling between carbon cycle processes, atmospheric CO2 levels, and climate throughout the Paleocene. Integration of a simple carbon cycle model driven by changing sedimentary organic carbon burial within the JPI analysis provides additional constraints on the CO2 reconstruction and demonstrates that this process is generally consistent with the available proxy evidence.

How to cite: Bowen, G., Harper, D., Da, J., and Kelson, J.: Reassessing Paleocene CO2 and Carbon Cycling using Process-Informed Joint Proxy Inversion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10037, https://doi.org/10.5194/egusphere-egu24-10037, 2024.

EGU24-10054 | ECS | Orals | CL1.1.1 | Highlight

Retaining Detail In Cenozoic CO2 Curves 

Ross Whiteford, James Rae, and Timothy Heaton

Palaeo CO2 concentration data has very variable density across the Cenozoic. Some events (such as the PETM) and intervals (such as glacial-interglacial cycles) are covered by high resolution datasets, whereas at other times the spacing between datapoints is much greater. Because of this variable data density, combining the datapoints into a line describing the evolution of palaeo CO2 usually focusses on either a short interval or on the long term trend (by blurring short term detail). We present a new approach which uses basis splines to produce a Cenozoic CO2 curve. The spline approach allows us to produce a curve which retains details in times where we have the requisite data density without introducing problematic artefacts at times with lower data density. The spline method makes it possible for the first time to produce a single curve which is sensible regardless of the timespan of interest.

How to cite: Whiteford, R., Rae, J., and Heaton, T.: Retaining Detail In Cenozoic CO2 Curves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10054, https://doi.org/10.5194/egusphere-egu24-10054, 2024.

EGU24-10538 | ECS | Posters on site | CL1.1.1

Impact of marine gateways on oceanic circulation and carbon cycle in the Late Eocene 

Emma Fabre, Jean-Baptiste Ladant, Yannick Donnadieu, and Pierre Sepulchre

The Late Eocene is a period of global cooling and high-latitude tectonic changes culminating in the Eocene Oligocene Transition (34 Ma ago), one of the major climatic shifts of the Cenozoic. Across the Late Eocene, the Earth went from a largely ice-free greenhouse during the early Eocene climatic optimum to an icehouse with the ice sheet inception over Antarctica. This long-term cooling happened simultaneously with a decrease in the atmospheric content in carbon dioxide whose causes are still unclear.

During the same period, marine gateways surrounding Antarctica (Drake Passage and Tasman Gateway) opened and deepened and Atlantic-Artic gateways changed configurations, thereby allowing the onset of oceanic currents such as the circumpolar current isolating Antarctica.

Here, we investigate how coupled changes in the configuration of these gateways may impact oceanic circulation and carbon cycle using climate simulations performed with the IPSL-CM5A2 model, an Earth System Model equipped with the biogeochemical model PISCES. Our reference simulation uses the paleogeography from Poblete et al (2021), based on the paleobathymetry of Straume et al (2020). Several sensitivity experiments with different gateway configurations are then presented and discussed, with specific focus on global ocean circulation changes and implications for the carbon cycle.

How to cite: Fabre, E., Ladant, J.-B., Donnadieu, Y., and Sepulchre, P.: Impact of marine gateways on oceanic circulation and carbon cycle in the Late Eocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10538, https://doi.org/10.5194/egusphere-egu24-10538, 2024.

EGU24-11160 | ECS | Posters on site | CL1.1.1

Emergence of North Atlantic Deep Water during the Cenozoic: A Tale of Geological and Climatic Forcings 

Erwan Pineau, Yannick Donnadieu, Pierre Maffre, Camille Lique, Thierry Huck, and Jean-Baptiste Ladant

The modern thermohaline circulation in the Atlantic Ocean plays a crucial role in shaping the climates of Europe and North America. It also significantly influences ocean carbon storage and biological productivity through processes such as deep ocean ventilation and nutrient advection. A pivotal element of this intricate circulation system is the deep convection in the North Atlantic, which is essential for the Atlantic meridional overturning circulation. Paleogeographic studies based on data from the Cenozoic era propose that the establishment of this ocean conveyor belt occurred between the Middle Eocene (approximately 48 to 38 million years ago) and the Late Miocene (around 11 to 5 million years ago). This period witnessed significant climate fluctuations, notably exemplified by the Eocene-Oligocene transition (34 million years ago), marked by a sudden global temperature cooling and the emergence of the Antarctic Ice Sheet (AIS). Did these changes have a significant impact on the stability of the North Atlantic Ocean? To address this question, we investigate the mechanisms behind the initiation of deep water in the North Atlantic during the Eocene to Miocene transition, using the Earth System model IPSL-CM5A2. Our Eocene simulation indicates an absence of convective instabilities in the North Atlantic, whereas deep convection is evident in our Miocene simulation, enabling the presence of a proto-Atlantic Meridional Overturning Circulation (AMOC) cell. In order to investigate the processes triggering North Atlantic Deep Water (NADW) initiation under Miocene conditions, we conducted sensitivity tests involving a reduction in atmospheric CO2 concentration from 1,120 ppmv to 560 ppmv and the introduction of AIS for Eocene conditions. Our findings reveal that halving the CO2 concentration and initiating AIS during the Eocene is insufficient to destabilize the water column in the North Atlantic and instigate the formation of NADW. The Eocene paleogeography emerges as a key factor, contributing to an inflow of fresh water into the Atlantic Ocean, resulting in low surface water density. This process reinforces stratification, hindering the onset of convection.

How to cite: Pineau, E., Donnadieu, Y., Maffre, P., Lique, C., Huck, T., and Ladant, J.-B.: Emergence of North Atlantic Deep Water during the Cenozoic: A Tale of Geological and Climatic Forcings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11160, https://doi.org/10.5194/egusphere-egu24-11160, 2024.

EGU24-11229 | ECS | Orals | CL1.1.1

Vegetation recovery and adaptation shapes the post-Large Igneous Province carbon-climate regulation system 

Julian Rogger, Emily J. Judd, Benjamin J.W. Mills, Yves Goddéris, Taras V. Gerya, and Loïc Pellissier

Earth’s long-term climate evolution is regulated by feedback mechanisms that keep carbon inputs from geologic reservoirs by magmatic or metamorphic degassing in balance with carbon sink fluxes, such as silicate mineral weathering and organic carbon burial. Abrupt imbalances in the carbon cycle, for example due to the release of carbon during the emplacement of Large Igneous Provinces (LIP), potentially result in catastrophic climatic disruptions, biotic crises, and mass extinctions in the oceans and on land. However, it remains enigmatic what climatic, geologic, and biologic variables determine the resilience of Earth’s compartments to such carbon injections. Here, we evaluate how the evolutionary adaptation and dispersal capacity of terrestrial vegetation affect the temperature anomaly following a massive release of CO2 to Earth’s atmosphere and oceans. To do so, we develop an eco-evolutionary vegetation model that is coupled to a geologic carbon cycle model and a look up structure of intermediate complexity climate simulations, which we apply to different LIP degassing events during the Phanerozoic. In the model, the vegetation’s impact on global carbon fluxes (i.e., organic carbon production and plant-mediated enhancement of silicate rock weathering) depends on the vegetation’s capacity and speed of responding to LIP-induced climatic changes. We observe a strong sensitivity of both, the intensity and duration of climatic changes following a LIP emplacement to the vegetation’s climate adaptation capacity by evolutionary adaptation or by migration in geographic space. The interaction between the continental configuration (e.g., supercontinent vs. distributed continents) and the distribution of dispersal barriers for the terrestrial vegetation further result in the emergence of new, long-term climatic steady states by inducing a new balance between global organic and inorganic carbon fluxes. Modelled trajectories of bio-climatic disruption and recovery agree well with paleotemperature reconstructions from geochemical proxies for selected LIPs. A better understanding of biologically driven climate regulation mechanisms may help to explain unresolved changes in temperature over Earth’s history.

How to cite: Rogger, J., Judd, E. J., Mills, B. J. W., Goddéris, Y., Gerya, T. V., and Pellissier, L.: Vegetation recovery and adaptation shapes the post-Large Igneous Province carbon-climate regulation system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11229, https://doi.org/10.5194/egusphere-egu24-11229, 2024.

EGU24-11330 | ECS | Posters on site | CL1.1.1

Modelling the Ocean Circulation during the mid-Cretaceous using an Energetically Consistent Internal Wave Model in the Community Earth System Model 

Siva Kattamuri, André Paul, Friederike Pollmann, Mattias Green, and Michael Schulz

Deep-time climate simulations typically disregard tidal dynamics while trying to reconstruct the paleoclimate. Tidally induced mixing is a dominant part of vertical mixing in the deep ocean, which is key for maintaining ocean stratification and influences the strength of the Meridional Ocean Circulation (MOC). We add this missing tidal mixing component to the Community Earth System Model (CESM) and try to reconstruct the mid-Cretaceous (~90Ma) climate, which is known for its warm, equable climate and low meridional temperature gradient. In the next step, as an improvement over the default tidal mixing scheme, an energetically consistent internal wave model IDEMIX is used in CESM to get the vertical diffusivity coefficients in simulating the mid-Cretaceous climate. 

Initially, 90Ma simulations were performed in the conventional method with enhanced constant background diffusivity coefficients for the default vertical mixing scheme and then with the tidal mixing component enabled. Preliminary results from the simulations with tidal mixing show that there is a considerable reduction in the global ocean mean temperature and a change in the strength of MOC in the deep ocean when compared to the simulations without the tidal mixing component. We will be also presenting results from additional experiments that are being performed with the internal wave model IDEMIX as the tidal mixing parameterization in the model. IDEMIX is forced by the dissipated barotropic tidal energy, which is modelled from the mid-Cretaceous bathymetry. With the IDEMIX parameterization, we expect more realistic results for ocean circulation hoping to reduce the disagreements between proxy data and model simulations.

How to cite: Kattamuri, S., Paul, A., Pollmann, F., Green, M., and Schulz, M.: Modelling the Ocean Circulation during the mid-Cretaceous using an Energetically Consistent Internal Wave Model in the Community Earth System Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11330, https://doi.org/10.5194/egusphere-egu24-11330, 2024.

EGU24-11818 | ECS | Orals | CL1.1.1

Orbitally driven bottom-water dynamics during the Maastrichtian  

Alexa Fischer, Oliver Friedrich, Andre Bahr, Silke Voigt, and Sietske Batenburg

The long-term global cooling trend during the latest Cretaceous was interrupted by an intense global warming episode at ~69 Ma known as the mid-Maastrichtian event (MME). The MME is characterised by two positive 13C excursions with an overall magnitude of 0.6‰ to 1.5‰, separated by a negative inflection. The 13C excursions are accompanied by the extinction of inoceramid bivalves, an abrupt increase in deep-sea and sea-surface temperatures as well as high terrestrial mean annual temperatures between 21 and 23 °C at a paleolatitude of ~35° N. Changes in oceanic circulation, particularly a change in thermohaline circulation patterns, have been suggested to be one of the main drivers of the MME. In this study, we aim to test this hypothesis by the generation of new high-resolution d13C and d18O analyses, Mg/Ca-derived bottom-water temperatures and CaCO3 wt% records from IODP Site U1403 (J-Anomaly Ridge, North Atlantic). Rhythmic variations in these geochemical records reflect an imprint of Earth´s astronomical parameters. Our results point towards a combination of Large Igneous Province (LIP) volcanism and simultaneous changes in deep-ocean circulation as triggers for the MME. For the North Atlantic, we observe an interplay between warmer and colder bottom-waters in combination with CaCO3 dissolution events. This hints toward a switch in bottom-water source regions between a high- and a low-latitude source region, likely controlled by orbital forcing. With the termination of the MME, bottom-water temperatures started to decrease, and the d13C record indicates an abrupt reorganization of the ocean circulation system towards a solely high-latitude North Atlantic source region for bottom-water.

How to cite: Fischer, A., Friedrich, O., Bahr, A., Voigt, S., and Batenburg, S.: Orbitally driven bottom-water dynamics during the Maastrichtian , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11818, https://doi.org/10.5194/egusphere-egu24-11818, 2024.

EGU24-11853 | ECS | Posters on site | CL1.1.1

Exploring Radiative Forcing from Pliocene Boundary Conditions and CO2 

Noah Kravette, Ran Feng, and Michelle Dvorak

Past climate states hold valuable insights into future climate change. Among those states, mid-Pliocene (3.3 - 3.0 Ma) is often studied as an important analog to near future climate change following an intermediate warming pathway. This time interval featured topography and geography like present-day, yet with retreated polar ice sheets and expanded boreal forests, potentially reflecting equilibrium earth system responses to CO2 forcing at a centennial to millennial time scale.  

Despite the prolific research on Pliocene climate, little is known about the amount of radiative forcing, especially from changing boundary conditions, that drives the Pliocene climate. Existing constraints mainly focused on well-mixed greenhouse gases and aerosols. Here, we applied the methodology commonly used to quantify radiative forcing of future climate and its sources to constrain radiative forcing of the mid-Pliocene climate using three generations of Community Earth System Models (CCSM4, CESM1.2, and CESM2).   

To calculate ERF, the difference in net top of the atmosphere radiative fluxes is computed between a pre-industrial control and a mid-Pliocene simulation. Both are carried out with prescribed pre-industrial sea surface temperature. The three mid-Pliocene simulations separately feature a 400 ppm CO2 (the level of mid-Pliocene), mid-Pliocene geography and topography, and mid-Pliocene ice and vegetation. Changing atmospheric temperature, water vapor, surface albedo, and clear vs total sky radiative fluxes are further extracted from these simulations to calculate radiative adjustments with published radiative kernels for CESM.  

In our preliminary results with CESM1.2, we found that ERF is 1.754 W m-2 for CO2 forcings, 1.143 W m-2 for vegetation and ice sheet forcing, and -0.339 W m-2 for geographic and topographic forcing. Further, ERF from boundary condition changes mostly arises from changing surface albedo with 1.626 W m-2 for vegetation and ice sheet changes and –0.54 W m-2 for geographic and topographic changes respectively. Radiative adjustments from water vapor responses tend to amplify the instantaneous forcing with the most profound effect induced by vegetation and ice sheet changes. These results underscore the importance of constraining radiative forcing from changes in boundary conditions, which is potentially key to understanding drivers of past climate warmth and inter-model spread in simulated past climate states.  

How to cite: Kravette, N., Feng, R., and Dvorak, M.: Exploring Radiative Forcing from Pliocene Boundary Conditions and CO2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11853, https://doi.org/10.5194/egusphere-egu24-11853, 2024.

EGU24-12543 | Orals | CL1.1.1

Comparison of plant fossil assemblages across the Permian–Triassic Boundary with simulated biomes in alternative climatic states 

Maura Brunetti, Charline Ragon, Christian Vérard, Jérôme Kasparian, Hendrik Nowak, and Evelyn Kustatscher

Terrestrial floras underwent major changes across the Permian–Triassic Boundary (PTB), as observed in the distribution of plant fossil assemblages before (Wuchiapingian, Changhsingian) and after (Induan, Olenekian, Anisian) the PTB [1]. While marine animals suffered the most severe mass extinction event at the Permian–Triassic transition, terrestrial plants were marked by extreme shifts in their distribution and composition which can arise when abiotic drivers reach a critical threshold or tipping point [2]. 

Interestingly, using a coupled atmosphere-ocean-sea ice-land configuration of the MIT general circulation model, three alternative climatic states have been found for the Permian–Triassic paleogeography [3], namely a cold state with perennial ice in the northern hemisphere reaching 40°N and global mean surface air temperature (SAT) of 16–18 °C, a hot state without ice and SAT larger than 30 °C, and an intermediate warm state. These states turn out to be stable over a common range of atmospheric CO2 content, thus allowing for hysteresis paths and tipping points in abiotic drivers, such as the global surface air temperature. Through asynchronous coupling with the vegetation model BIOME4, the distribution of the biomes corresponding to each climatic state has been obtained.

Here, we perform a detailed comparison between the biomes corresponding to the alternative climatic states and the distribution of plant fossil assemblages from the Wuchiapingian to the Anisian. For each observed assemblage, the geodetic distance to the closest simulation grid point with the same biome is calculated. This allows us to quantify, through statistical significance tests, the resemblance between the simulated biomes and the observed distribution of plant fossil assemblages, and thus to determine the climatic state which minimizes the mean distance at each geological period. We find a clear signature of climatic shifts from a cold state in the Changhsingian to a hot state in the Olenekian, whereas during the earliest Triassic (Induan) the attribution to a particular climatic state is not univocal, strong climatic oscillations being still present in the aftermath of the PTB.   

References

[1] H. Nowak, C. Vérard, E. Kustatscher, Frontiers in Earth Science 8, 613350 (2020)

[2] E. Schneebeli-Hermann, Frontiers in Earth Science 8, 588696 (2020)

[3] C. Ragon, C. Vérard, J. Kasparian, M. Brunetti, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-1808, 2023

 

How to cite: Brunetti, M., Ragon, C., Vérard, C., Kasparian, J., Nowak, H., and Kustatscher, E.: Comparison of plant fossil assemblages across the Permian–Triassic Boundary with simulated biomes in alternative climatic states, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12543, https://doi.org/10.5194/egusphere-egu24-12543, 2024.

Changes in climate feedback processes drive fluctuations in equilibrium climate sensitivity (ECS), the measure of global warming associated with a doubling of atmospheric CO2. Warming in different past climates resulted in various responses in ECS that can be explored to further understand how distinct feedbacks and forcings control CO2-induced warming. Previous studies generally agree that ECS increases with increases in the CO2 background state. We investigate this further through simulations of different time slices from ~100 million years ago to present, all run with the same model version. We will use Community Earth System Model (CESM1.2) simulations to study Earth’s response to an increase in CO2 radiative forcing under past greenhouse and icehouse climates. We compare time slices that have differences in geography, vegetation, and ice, which affect feedbacks that drive ECS. We will use slab ocean model and fully-coupled CESM1.2 simulations of the late Cretaceous, early Eocene, late Oligocene, mid Miocene, and preindustrial (PI) all at modern orbital parameters, with greenhouse climate simulations at 840 ppm and 1680 ppm CO2 and icehouse climate simulations at 280 ppm and 560 ppm CO2, in order to compare changes in temperature resulting from changes in albedo, ocean heat flux, and nonlinearities in atmospheric water vapor and cloud feedbacks. We will compare simulations of greenhouse and icehouse climates, past climates to the PI climate, and our CESM1.2 simulations to previously published simulations run on other earth system models, like the Hadley Centre Coupled Model, to study the degree of model-dependence in ECS. Analyzing ECS in past climates, with a control on model version, and comparing differences in climate feedbacks will help constrain the sensitivity of ECS to boundary conditions and the range of ECS through Earth’s history. 

How to cite: Campbell, J. and Poulsen, C. J.: Changes in equilibrium climate sensitivity and associated feedbacks through past greenhouse and icehouse climate simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12923, https://doi.org/10.5194/egusphere-egu24-12923, 2024.

EGU24-13051 | Orals | CL1.1.1 | Highlight

Connecting warming patterns of the paleo-ocean to our future 

Yige Zhang, Xiaoqing Liu, Matthew Huber, Ping Chang, and Lei Wang

Evolution of the spatial pattern of ocean surface warming impacts global radiative feedbacks, but different climate models have yielded different estimates of the spatial pattern in future climate change. Paleoclimate data, particularly those from past warm climates can help constrain the future, equilibrium warming pattern. Here, employing a novel regression-based technique, we eliminated the temporal domain in sea surface temperature (SST) over the past 10 million years to reveal the underlying spatial pattern of SST changes during global warming, facilitating direct comparisons between past climate data and present/future climates. Long and globally distributed paleo-SSTs are regressed onto records from the Western Pacific Warm Pool (WPWP), the warmest endmember of the global ocean, and the resulting regression slope is used to quantify the SST change of non-WPWP regions relative to the WPWP. We thereby identify a distinct spatial pattern of amplified warming that aligns with the patterns observed in certain equilibrated model simulations under high CO2 conditions. The agreement between paleoclimate records and model outputs showcases the convergence of efforts to understand Earth's past and predict its future climates. Collectively they help us to define an equilibrium warming pattern that substantially differs from the transient pattern observed over the past 160 years, illuminating our potential future path of “pattern effect” and its impact on global mean surface temperature change.

How to cite: Zhang, Y., Liu, X., Huber, M., Chang, P., and Wang, L.: Connecting warming patterns of the paleo-ocean to our future, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13051, https://doi.org/10.5194/egusphere-egu24-13051, 2024.

EGU24-16065 | ECS | Posters on site | CL1.1.1 | Highlight

Modelling the consequences of the Siberian traps 

Antonin Pierron, Guillaume Le Hir, Frédéric Fluteau, Yves Goddéris, and Pierre Maffre

The temporal synchronism between large igneous provinces (LIP) emplacements and mass extinction all along the Phanerozoic reveals a possible link between the two. The release of huge amount of gases during the LIP emplacement is considered to cause major climate and environmental perturbations possibly leading to a biodiversity crisis. However no clear correlation can be drawn between LIP’s properties i.e. the LIP size, the amount of gas released, etc… and the mass extinction severity.

Our primary focus was on investigating the consequences of the Siberian traps emplacement which is considered to be responsible of the end-Permian mass extinction. This biodiversity crisis lead to the disappearance of 90% of the marine species and 75% of the terrestrial species. The Siberian volcanism has produced 3 to 5 millions km3 of magma over a period not exceeding 1 Myr according to U-Pb dating. This volcanism is accompanied by the release of huge amount of gases within the atmosphere, notably CO2 and SO2.
These gases have two sources : the magmatic degassing and the thermogenic degassing generated by the intrusion of magmas in carbonate-rich or evaporite-rich sediments deposited within the Siberian basin. We propose to explicitly model volcanism by considering both short-term and long-term scale processes along the entire LIP emplacement with different scenarios to mimic the sequence of volcanic and thermogenic gas emissions. For this purpose, we employed the biogeochemical model GEOCLIM to simulate the changes of the ocean in term of temperature and pH caused by the LIP emplacement. This approach enables a detailed exploration of the impact of LIP emplacement on the climate and geochemical cycles.

How to cite: Pierron, A., Le Hir, G., Fluteau, F., Goddéris, Y., and Maffre, P.: Modelling the consequences of the Siberian traps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16065, https://doi.org/10.5194/egusphere-egu24-16065, 2024.

EGU24-17106 | ECS | Orals | CL1.1.1 | Highlight

Is the ocean losing its breath? Insights into ocean oxygenation from Cenozoic warm periods. 

Alexandra Auderset, Anya Hess, Simone Moretti, Daniel Sigman, and Alfredo Martínez-García

The continuous expansion of oxygen-deficient zones (ODZs) poses risks to marine ecosystems and societies dependent on fisheries for income and sustenance. However, the trajectory of this deoxygenation in response to 21st-century climate change remains uncertain. To gain a clearer understanding of future oxygen dynamics and processes leading to deoxygenation, we investigate the response of ODZs during Cenozoic global warming periods in the Miocene and Early Eocene, using a combination of oxygen-sensitive proxies including foraminifer-bound nitrogen isotopes (FB-δ15N) and iodine-to-calcium ratios in planktic foraminifer shells (I/Ca). Our findings reveal contracted, rather than expanded, tropical Pacific ODZs during all studied warm intervals. The increased oxygenation closely aligns with high-latitude warming and reduced meridional sea surface temperature gradients, indicating a climatic driver behind these observed changes. We discuss potential causes for the contraction of ODZs, including (i) diminished wind-driven equatorial upwelling and primary productivity, and/or (ii) increased deep-ocean ventilation. Finally, we compare the behaviour of Pacific vs. Indian Ocean ODZs during the Miocene and investigate potential teleconnections between these two wind-driven ODZs.

How to cite: Auderset, A., Hess, A., Moretti, S., Sigman, D., and Martínez-García, A.: Is the ocean losing its breath? Insights into ocean oxygenation from Cenozoic warm periods., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17106, https://doi.org/10.5194/egusphere-egu24-17106, 2024.

EGU24-18824 | Orals | CL1.1.1

Can CO2 degassing explain the climate and biogeochemical perturbations during Cretaceous OAE2? 

Chiara Krewer, Benjamin J. W. Mills, Mingyu Zhao, and Simon W. Poulton

The Late Cretaceous is characterized by extreme greenhouse conditions with high temperatures and high atmospheric pCO2 that have been proposed to be directly linked to the emplacement of large igneous provinces (Caribbean and Madagascar LIP). As a result of these extreme conditions, an increase in organic carbon burial has been recorded on a global scale during Oceanic Anoxic Event 2 (OAE2, ~94.5 Ma), which has been linked to amplified continental weathering1,2 and increased marine nutrient availability. However, despite the event being well studied, a model that directly estimates the combined biogeochemical effects of LIP-derived CO2 input – and compares this to the combined geological record –is lacking.

Here we use a new biogeochemical ocean-atmosphere-sediment multi-box model3 which produces a self-consistent estimate of the global C, O, Fe, S and P cycles across the marginal and deep ocean, and we explore the outputs of this model for carbon isotope excursions (CIEs) in carbonates and organic carbon as well as for high and low latitude paleo-sea-surface temperatures (SSTs) under a LIP CO2 degassing scenario for OAE2.

The model results indicate that in order to reproduce both the global SST records and CIEs, the annual rate of volcanic input of CO2 must be higher than the estimated range from previously published research. Furthermore, to reproduce the magnitude of the positive CIEs, the model requires an additional source of bioavailable iron beyond that which is liberated through global weathering enhancement under high CO2. We investigate the possibility that hydrothermal input of Fe to the deep ocean during LIP activity helped boost productivity during OAE2, and suggest that the balance between tectonic inputs of CO2 and limiting nutrients may help explain why some OAEs are accompanied by positive carbon isotope excursions and some by negative excursions.

References:

1 Pogge von Strandmann et al., 2013, Nature Geoscience

2 Nana Yobo et al., 2021, GCA

3 Zhao et al., 2023, Nature Geoscience

How to cite: Krewer, C., Mills, B. J. W., Zhao, M., and Poulton, S. W.: Can CO2 degassing explain the climate and biogeochemical perturbations during Cretaceous OAE2?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18824, https://doi.org/10.5194/egusphere-egu24-18824, 2024.

EGU24-18842 | ECS | Orals | CL1.1.1

Unveiling the deep-time Earth dust emissions: Modelling and Diagnosing control factors 

Yixuan Xie, Daniel Lunt, Paul Valdes, and Fanny Monteiro

Desert dust is a vital component of the Earth's climate system. The climate system regulates dust emission processes, such as sediment availability and wind entrainment, in various ways. Dust modulates the Earth's radiation balance, and wind-carried dust deposition provides essential nutrient iron to land and marine ecosystems.  While dust science is well-developed for the modern and the Quaternary (the last 2.6 Ma), little investigation has been done for the Earth's deep time.

Here, we present for the first time a continuous reconstruction of dust emissions throughout the Phanerozoic era (since 540 Ma ago), simulated by a newly developed dust emission model DUSTY, which is forced by the paleoclimate fields from the General Circulation Model HadCM3L. Our results show how dust emissions fluctuated over time with a stage-level resolution (approximately 5 Ma). We then diagnosed the controls of these fluctuations, highlighting that the non-vegetated area is the main contributor, which is controlled through precipitation levels. The ultimate dominating forcing is the paleogeography changes, whereas CO2 plays a marginal role. We compare our results with sediment evidence and find good agreement. Finally, we present ongoing work investigating further how dust deposition might have impacted ocean production and biogeochemistry through deep-geologic time.

How to cite: Xie, Y., Lunt, D., Valdes, P., and Monteiro, F.: Unveiling the deep-time Earth dust emissions: Modelling and Diagnosing control factors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18842, https://doi.org/10.5194/egusphere-egu24-18842, 2024.

EGU24-19857 | Posters on site | CL1.1.1

Impacts of tidally driven internal mixing in the Early Eocene Ocean 

Jean-Baptiste Ladant, Jeanne Millot-Weil, Casimir de Lavergne, J. A. Mattias Green, Sébastien Nguyen, and Yannick Donnadieu

Diapycnal mixing in the ocean interior is largely fueled by internal tides. Mixing schemes that represent the breaking of internal tides are now routinely included in ocean and earth system models applied to the modern and future. However, this is more rarely the case in climate simulations of deep-time intervals of the Earth, for which estimates of the energy dissipated by the tides are not always available. Here, we present and analyze two IPSL-CM5A2 earth system model simulations of the Early Eocene made under the framework of DeepMIP. One simulation includes mixing by locally dissipating internal tides, while the other does not. We show how the inclusion of tidal mixing alters the shape of the deep ocean circulation, and thereby of large-scale biogeochemical patterns, in particular dioxygen distributions. In our simulations, the absence of tidal mixing leads to a deep North Atlantic basin mostly disconnected from the global ocean circulation, which promotes the development of a basin-scale pool of oxygen-deficient waters, at the limit of complete anoxia. The absence of large-scale anoxic records in the deep ocean posterior to the Cretaceous anoxic events suggests that such an ocean state most likely did not occur at any time across the Paleogene. This highlights how crucial it is for climate models applied to the deep-time to integrate the spatial variability of tidally-driven mixing as well as the potential of using biogeochemical models to exclude aberrant dynamical model states for which direct proxies do not exist.

How to cite: Ladant, J.-B., Millot-Weil, J., de Lavergne, C., Green, J. A. M., Nguyen, S., and Donnadieu, Y.: Impacts of tidally driven internal mixing in the Early Eocene Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19857, https://doi.org/10.5194/egusphere-egu24-19857, 2024.

EGU24-624 | ECS | Posters on site | CL1.1.2

Hydrodynamic changes in the Gulf of Cadiz during the Early-Middle Pleistocene Transition revealed by benthic foraminifera and radiogenic isotope data 

Giulia Molina, Leopoldo D. Pena, Ester Garcia-Solsona, Eduardo Paredes, Aline Mega, and Antje Voelker

The Early-Middle Pleistocene Transition (EMPT), a global climate event that occurred between 700-1250 thousand years (kyr) ago, was characterized by a drastic change in the deep thermohaline circulation, resulting in more intense and longer-lasting interglacial periods. High-resolution records documenting environmental changes on the ocean seafloor associated with the EMPT in the North Atlantic are still limited. This knowledge is crucial for evaluating and modeling climate variability in the near future. The Gulf of Cadiz (Iberian Margin) is a key region as a gateway between the Mediterranean Sea and the North Atlantic Ocean, being affected at intermediate depths by the Mediterranean Outflow Water (MOW). The MOW plays an important role in modulating the North Atlantic salt budget. Therefore, past climate variability in the Mediterranean region may have affected the MOW intensity and global thermohaline circulation. Thus, the present study aims to understand the environmental parameters influencing the distribution of benthic foraminifera species and their significance in regional oceanographic dynamics. 

Benthic foraminifera inhabit diverse (sub)seafloor environments and respond to factors such as oxygen levels, as well as the quantity and quality of food. Although other factors might influence the assemblage, strong bottom current regimes favor abundances of a group known as the “elevated epifauna”. Previous studies in the Gulf of Cadiz have found that elevated epifauna abundance correlates with MOW intensity in the modern ocean, suggesting it as a potential indicator of MOW intensity in the past.

Here we present results from a high-resolution study of benthic foraminifera assemblage of the period from Marine Isotope Stages (MIS) 26 to 19 at IODP Site U1387 (559 m water depth), drilled into the Faro drift on the southern Portuguese margin. Our study identifies two distinct phases: the first phase (MISs 25 to 22, 959–866 kyr) experienced persistent and intensified MOW flow, as evidenced by an increase in the abundance of elevated epifauna. This phase also exhibits an increase in the abundance such as Globobulimina spp., species that live under oxygen and trophic conditions prevailing at the boundary between dysoxic and anoxic environments, suggesting stronger influence of relatively low oxygen Mediterranean waters. As soon as the MOW intensity declines in the second phase (MIS 21 to MIS 19, 866 – 761 kyr), there is a decrease in the Globobulimina spp. abundance, and an increase in oxygenated-preferred species abundance. We hypothesize that phase I is highly influenced by Mediterranean-sourced waters, whereas phase II improved oxygen conditions indicate potential dominance of Atlantic-sourced waters due to a lesser Mediterranean water contribution. To validate these results, Neodymium isotope analyses (εNd) are being conducted to help distinguishing between the prevailing water masses. Following our hypothesis, we are expecting more positive values during phase I, indicating stronger MOW influence, and more negative values for phase II, suggesting weaker MOW influence and dominantly Atlantic-sourced waters. These findings will further contribute to our understanding of the interplay between climate change and oceanographic dynamics in the Gulf of Cadiz during the EMPT.

How to cite: Molina, G., D. Pena, L., Garcia-Solsona, E., Paredes, E., Mega, A., and Voelker, A.: Hydrodynamic changes in the Gulf of Cadiz during the Early-Middle Pleistocene Transition revealed by benthic foraminifera and radiogenic isotope data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-624, https://doi.org/10.5194/egusphere-egu24-624, 2024.

EGU24-722 | ECS | Posters on site | CL1.1.2

 pH variations during the last and current interglacial stages at the western Iberian margin 

Aline Mega, Eva Calvo, Leopoldo D. Pena, Emília Salgueiro, Andreia Rebotim, Antje Voelker, Joana Cruz, and Fátima Abrantes

The intricate interplay among atmospheric CO2 concentrations, surface ocean pH dynamics, and their profound impact on marine ecosystems is of paramount importance in the context of contemporary climate change. Pre-industrial atmospheric CO2 concentrations oscillated in phase with glacial-interglacial cycles, showcasing low levels during glacial periods and elevated concentrations during interglacial periods. Nevertheless, this natural variability has been significantly disrupted due to the surge in anthropogenic CO2 emissions over recent decades. According to the Intergovernmental Panel on Climate Change, if global atmospheric CO2 concentrations persist in rising at the current rate, it is anticipated that the average ocean pH will decrease by 0.3 pH units in surface waters by the conclusion of this century. This scenario could exacerbate the impacts already observed in marine calcifying organisms, including in marine calcifying organisms such as planktonic foraminifera, affecting their diversity, abundance, and calcification. The main objective of this study is to understand the surface ocean pH evolution in a seasonal upwelling region, during two distinct interglacial periods in Earth's history: the Marine Isotopic Stage 5e (MIS 5e), the last interglacial without anthropogenic influence; and the Holocene, the present interglacial but subjected to anthropogenic influence. In upwelling regions, the upwelling of aged and CO2-rich subsurface waters together with high rates of primary production and respiration, is expected to regionally amplify ocean acidification. This study concentrates on the reconstruction of surface ocean pH using boron isotopes in a surface planktonic foraminifera species, Globogerinoides bulloides. This species is typically found in upwelling regions and was preserved in the marine sediment corer MD03-2699 (39°02.20′N, 10°39.63′W). Our preliminary findings indicate a pH difference between MIS 5e and the Holocene, with lower pH values during the Holocene.  It is argued that during the Holocene, a potential increase in wind intensity may have triggered a strong and persistent upwelling increasing productivity and respiration, consequently leading to lower pH. Additionally, the increase of atmospheric CO2, reconstructed from Antarctic ice cores during this period could also contribute to the ocean pH reduction. These variations in upwelling and/or atmospheric CO2 could be a pivotal factor influencing the observed pH differences, contributing to our comprehension of natural pH variations on the western Iberian margin through advanced pH reconstruction techniques and other multi-proxy environmental data integration for both periods in the region.

How to cite: Mega, A., Calvo, E., D. Pena, L., Salgueiro, E., Rebotim, A., Voelker, A., Cruz, J., and Abrantes, F.:  pH variations during the last and current interglacial stages at the western Iberian margin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-722, https://doi.org/10.5194/egusphere-egu24-722, 2024.

The pacing of the global climate system by orbital variations is clearly demonstrated in the timing of e.g. glacial-interglacial cycles. However, due to the complexity and internal nonlinearity of the Earth’s climate system, the mechanisms that translate this forcing into geoarchives and climate changes continue to be debated. A 609-m-thick, continuous lacustrine mudstone and sandstone succession in Chezhen Sag (eastern China) provides an ideal middle Eocene sedimentary record for establishing a high-resolution stratigraphic chronology framework. Based on spectrum analysis and sliding window spectrum analysis of the natural gamma (GR) logging data of well Che 271 (C271) in Chezhen Sag, the periods of 405 kyr and 40.1 kyr were filtered by a Gaussian bandpass filter, and a “floating”astrochronological time scale (ATS) was established. The total number of 405 kyr eccentricity cycles were 13.6 and 40.1 kyr obliquity cycles were 138 which recorded from the upper member 4 (Es4U) to the member 3 (Es3) of the Eocene Shahejie Formation, and the depositional duration was 5.53 Myr. Correlation Coefficient (COCO) analysis and evolutionary Correlation Coefficient (eCoCo) analysis found that the optimal sedimentary rate of different strata. Sedimentary noise simulation revealed the history of paleolake water changes in the Middle Eocene in the Chezhen Sag, according to which four sequences are divided. The study show that the lake level change of Chezhen Sag in the middle Eocene shows prominent 1.2 Myr cycles and an antiphase well-coupled relationship with obliquity modulation. Finally, we propose a model to explain the relationship between orbital cycle and lake level change in continental lake basin. When the obliquity of the earth increases, the middle and high latitudes of the earth will be closer to the sun, the direct sunlight will be higher, and the meridional sunshine will increase, thus accelerating the evaporation process of lake basin water. When the seasonal changes are obvious (Maximum period of 1.2 Myr ultra-long obliquity), this effect is more significant. Our results strengthen knowledge of the connection of Myr-scale lake-level variations to astronomically induced climate change during the middle Eocene under obliquity forcing.

How to cite: Luan, X. and Zhang, J.: Astronomical forcing and sedimentary noise modeling of lake-level changes in the Middle Eocene Chezhen Sag, Bohai Bay Basin, eastern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2995, https://doi.org/10.5194/egusphere-egu24-2995, 2024.

Water vapor is the essential substance for precipitation and a crucial component of the global hydrological cycle. Quantifying the contributions of terrestrial and oceanic moisture sources is crucial for comprehending regional precipitation and hydroclimate changes. Previous studies have extensively investigated the East Asian summer monsoon and its precipitation changes using geological climate records, but it remains unclear how water vapor from different source regions affects the orbital-scale precipitation change in East Asia. In this study, a long-term transient simulation using a water vapor tracking climate model was conducted for the past 300 kyr to investigate the contributions of terrestrial and oceanic moisture sources to precipitation changes in the northern East Asian monsoon region (NEA, 35-45°N, 105-120°E). The results showed that for the climatologically annual NEA precipitation, the global land source was the primary moisture source, accounting for approximately 57.6% of the total precipitation, followed by Pacific Ocean source contributing 20.9%, while other sources had a minor contribution. The orbital-scale changes of annual NEA precipitation, dominated by the precipitation of the rainy season from May to September, were mainly characterized by a significant 23-kyr cycle and a weak 100-kyr cycle. Analyses of water vapor sources found that the significant 23-kyr cycle in NEA precipitation was caused by the superposition of the synchronous 23-kyr cycles of precipitations from the land and Pacific Ocean sources, while the nonsynchronous 100-kyr cyclic changes of precipitations from the land and Pacific Ocean sources led to the weak 100-kyr cycle of NEA total precipitation. The dominant 23-kyr cycle of NEA precipitation reflects the effect of precession forcing, while the weak 100-kyr cycle implies the impact of the high-latitude ice sheet forcing, which triggers the antiphase change in the moisture contribution rates of the land and Pacific sources in the glacial-interglacial cycle. This study highlights the importance of terrestrial and oceanic moisture sources associated with external forcings in understanding the orbital-scale East Asian monsoon precipitation changes. As a preliminary attempt to track the orbital-scale variations of the terrestrial and oceanic moisture sources of East Asian monsoon precipitation by conducting a water vapor tracking transient simulation, this study provides new insights into the temporal-frequency characteristics and physical mechanisms of orbital-scale East Asian monsoon precipitation variations from the perspective of water vapor sources.

How to cite: Xie, X. and Liu, X.: Deciphering orbital-scale precipitation changes in the northern East Asian monsoon region: insights into the roles of terrestrial and oceanic moisture sources, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2999, https://doi.org/10.5194/egusphere-egu24-2999, 2024.

EGU24-3705 | ECS | Orals | CL1.1.2

Detection of orbital signals in the sedimentary record through stochastic statistical modeling 

Meng Wang, Mingsong Li, Elizabeth A. Hajek, David B. Kemp, Yujing Wu, Hanyu Zhu, and Zhijun Jin

The preservation of orbital signals in sedimentary records, a crucial aspect for the reliability of astronomical time scales, has been insufficiently explored, presenting challenges in interpretation. In this study, we focus on the effect of inconsistent sedimentation rates on the preservation of these orbital signals from a modeling perspective. We delve into how inconsistent sedimentation rates influence the retention of these orbital signals. Employing stochastic statistical models, our research simulates diverse sedimentary environments, we show that 405-kyr eccentricity tuning is the most reliable approach for constructing ATS among different tuning strategies, particularly in environments characterized by high energy conditions and unsteady sedimentation such as fluvial or deltaic settings. This discovery holds substantial importance in refining geological time scales. We introduce an innovative approach to evaluate sedimentation rates within these records. Our study demonstrates the robustness of the cyclostratigraphic method and deepens our understanding of the preservation of sedimentary records, thereby enriching our grasp of Earth's intricate geological past.

How to cite: Wang, M., Li, M., Hajek, E. A., Kemp, D. B., Wu, Y., Zhu, H., and Jin, Z.: Detection of orbital signals in the sedimentary record through stochastic statistical modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3705, https://doi.org/10.5194/egusphere-egu24-3705, 2024.

The Qiangtang Basin, situated on the Tibetan Plateau, is a basin that contains hydrocarbons and has significant potential for hydrocarbon exploration. However, reconstructing sea-level changes and understanding the sedimentary evolution of the Qiangtang Basin has been hindered by the lack of robust high-resolution geochronology. Meanwhile, the Late Triassic stratigraphy of the Qiangtang Basin has also reported the Carnian pluvial episode, the driving mechanism of which is controversial. In this study, the cyclostratigraphy of the Late Triassic Boli La and Bagong Formations in the Qiangtang Basin was analyzed using high-resolution gamma-ray data. Time series analysis shows that there are 405 kyr eccentricity cycles in the gamma-ray data series. The gamma-ray series was tuned to 405 kyr. Then, we establish a floating astronomical timescale with a length of 17.04 Myr. This astronomical time scale establishes an anchored astronomical time scale using the age of the volcanic rocks found in the top of the Bagong Formation in the drill core as an anchor point. Using the anchored astronomical chronology, we reconstructed the Late Triassic sea level change in the Qiangtang Basin using a recently developed sediment noise model. The reconstructed sea level change is generally consistent with the global sea level curve. The antiphase relationship between the filtered long-term obliquity cycles and the sea-level curves reconstructed from the sedimentary noise model suggests that the long-term obliquity cycles may have been the main driver of the Late Triassic greenhouse sea-level change. Meanwhile, the modulation maxima of the long-term obliquity-modulated cycles correlate well with high sea level, episodic negative carbon isotope excursions, global warming, and marine biotic crises, suggesting that obliquity forcing may have played a prominent role during the Carnian Pluvial Episode. Our results suggest that orbital forcing enhanced the hydrological cycle during the Carnian Pluvial Episode. Our study provides a precise, high-resolution time scale for studying the sedimentary evolution of the Qiangtang Basin, as well as a broader perspective on the relationship between the Carnian Pluvial Episode and astronomical forcing.

How to cite: Zhang, Q., Fu, X., and Wang, J.: The cyclostratigraphy of the Late Triassic Qiangtang Basin in Tibet and the orbital forcing for the Carnian Pluvial Episode, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4352, https://doi.org/10.5194/egusphere-egu24-4352, 2024.

EGU24-5931 | ECS | Orals | CL1.1.2 | Highlight

The Precession Cycles in East Asian Stalagmite Records Before the MPT Constrained by Carbonate U-Pb Dating  

Le Kang, Cheng Hai, Jian Wang, Xiaowen Niu, Haiwei Zhang, Jiaoyang Ruan, Youfeng Ning, Jingyao Zhao, and Youwei Li

The U-Pb geochronology of carbonates holds significant application value and potential in the field of geoscience. The Isotope Laboratory at Xi'an Jiaotong University has pioneered the development of Carbonate Laser Ablation and Dilution (LA&ID-MC-ICPMS) U-Pb dating techniques, based on research into Quaternary cave secondary carbonate geochronology. By combining the high spatial resolution and rapid analysis speed of the laser method with the controllable sample volume and high testing accuracy of the dilution method, a comprehensive system for Carbonate U-Pb geochronology testing has been established.

 

Moreover, with advancements in in-situ laser and isotopic dilution techniques for Carbonate U-Pb dating, we conducted tests using the laser method on various carbonate standards, both domestic and international, achieving U-Pb age results consistent with standard values within the error range. This laboratory also reported, for the first time in China, high-precision laser U-Pb dating results for Quaternary cave secondary carbonates, in alignment with ages obtained via dilution methods in foreign laboratories. Furthermore, our laboratory's entire Pb background is currently at a world-class level (~10 pg), and the testing results for cave secondary carbonates are consistent within the error range with dilution methods abroad and the laser method in our laboratory, validating its accuracy.

 

The laboratory has developed robust, high-precision laser and isotopic dilution techniques for Carbonate U-Pb dating, surpassing the limitations of U-Th dating. Through U-Pb dating and oxygen isotope analysis of stalagmite SB20 obtained from Sanbao Cave in Shennongjia, Hubei, our investigation reveals that SB20's growth period spans from 1.25 to 1.50 million years ago, depicting roughly 10 orbital cycles in δ18O. Consequently, we have established East Asia's inaugural δ18O record within the monsoon region, preceding the Mid-Pleistocene Transition (MPT). This novel stalagmite record affirms the predominant influence of low-latitude monsoons, driven by solar radiation forcing, on the East Asian region, showcasing discernible precession cycles. The current emphasis on global climate change research is substantial. By amalgamating prior scientific accomplishments, the interplay between the thermodynamic circulation system governed by ice volume in higher latitudes and the dynamic circulation system regulated by low-latitude monsoons shapes a multifaceted Earth scientific framework. This study furnishes pivotal evidence for the comprehensive exploration of a "high-low latitude" climate circulation theory in the context of climate orbital dynamics.

 

Keywords: Carbonate U-Pb geochronology; MPT; Stalagmite records; precession cycles

How to cite: Kang, L., Hai, C., Wang, J., Niu, X., Zhang, H., Ruan, J., Ning, Y., Zhao, J., and Li, Y.: The Precession Cycles in East Asian Stalagmite Records Before the MPT Constrained by Carbonate U-Pb Dating , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5931, https://doi.org/10.5194/egusphere-egu24-5931, 2024.

EGU24-6679 | ECS | Posters virtual | CL1.1.2 | Highlight

Investigating North Atlantic Deep-Water Ventilation Changes: Preliminary Results from IODP Expedition 397 Hole U1586A 

Lauren Haygood, Natascha Riedinger, David Hodell, Fatima Abrantes, and Carlos Alvarez Zarikian and the Expedition 397 Scientific Party

Although valuable information of North Atlantic circulation paleo-reconstructions by the measurement of oxygen isotopes of benthic and planktonic foraminifera exists, it is still not well-understood how deep-water currents changed over the last ~800,000 years. Moreover, recent studies have shown that some species of microfossils can adapt to low oxygen concentrations, which consequently can impact the reliability of the paleo-reconstructions that are based on these fossils. Marine sediments off the Portuguese Margin have been shown to play a pivotal role in paleoclimate research, and studies have suggested that climate shifts at Mediterranean latitudes are interconnected to changes in deep-water circulation patterns. Changes in bottom-water oxygenation (ventilation) can provide information about changes in deep-water circulation patterns, which can be measured by the enrichment versus depletion of redox-sensitive trace metals. Here we provide the results of a low-resolution geochemical analysis of redox-sensitive trace metals (for example, molybdenum (Mo), vanadium (V), and uranium (U)) to investigate deep-water ventilation changes in the North Atlantic over the last ~800,000 years at Hole U1586A drilled during IODP Expedition 397. Sediment samples underwent a multi-acid digestion technique and were analyzed via an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for redox-sensitive trace metals. Additionally, sequential iron (Fe) extractions were carried out to differentiate between labile versus mineral Fe phases. Preliminary results suggest minor changes in deep-water ventilation that correspond to glacial-interglacial cycles since the mid-Pleistocene. Future work will involve high-resolution geochemical analyses to better understand the interconnection of deep-water circulation and climate change.

How to cite: Haygood, L., Riedinger, N., Hodell, D., Abrantes, F., and Alvarez Zarikian, C. and the Expedition 397 Scientific Party: Investigating North Atlantic Deep-Water Ventilation Changes: Preliminary Results from IODP Expedition 397 Hole U1586A, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6679, https://doi.org/10.5194/egusphere-egu24-6679, 2024.

EGU24-6745 | Posters on site | CL1.1.2

Using lipid biomarker signatures to reconstruct marine primary production in the Iberian Margin over the last millennium 

Lívia Gebara M.S. Cordeiro, Renato S. Carreira, Fernanda Ferreira, Teresa A. Rodrigues, and Fátima F. Abrantes

Despite efforts to understand the response of marine ecosystems to the impact of climate variability in the Iberian Margin [1-6], the effects of warming on phytoplankton community composition and total primary production remain an open question. Here, we present a high-resolution record of sediment-preserved lipids from the Iberian Margin (IM) over the last millennium, with special attention to the modern rise in atmospheric CO2. To address the temporal variation of marine primary production and terrestrial organic matter input, we studied GC-MS/FID-determined lipid compounds from cores PO287-06-2G (off the Douro River in the northern IM), PO287-26-3G (off the Tagus River in the central IM) and POPEI-VC2B (on the Algarve continental shelf in the southern IM). Lipids of typical marine origin (C27, C28, and C30 sterols, phytol, and C37 and C38 alkenones) and of typical terrestrial origin (odd long-chain n-alkanes nC21-nC35 and even long-chain n-alcohols C22OH-C32OH) were evaluated. As proxies for specific phytoplankton groups, we used the signatures of 4α-23,24-trimethyl-5α-cholest-22(E)-en-3β-ol (30d22 sterol) for dinoflagellates, 24-methylcholesta-5,22-dien-3β-ol (28d5,22 sterol) for diatoms and heptatriaconta-15E,22E-diene-2-one (C37:2 alkenone) for coccolithophores. The results showed a significant difference between the northern, central, and southern sites of the Iberian Margin, caused by the different regional environmental factors in each area. Higher concentrations of lipids are observed off Douro River, there is a higher relative contribution of cholesterol off Tagus River, suggesting the importance of zooplanktonic production in the central area, and there is a higher contribution of coccolithophores lipid signatures in the Algarve continental shelf. In terms of temporal variability, there is an alternation between coccolithophores and dinoflagellates lipid signatures over the millennium, with significant diatom sterol signatures at specific ages of the Industrial Era (since 1850 CE) and in the early MCA (900-1100 CE) for all sites. The temporal variability is most likely driven by changes in local and hemispheric ocean circulation and coastal upwelling conditions in the Iberian Margin.

References: [1] Abrantes et al., 2017; [2] Abrantes et al., 2011; [3] Salgueiro et al, 2008; [4] Ribeiro and Amorim 2008; [5] Abrantes 2000; [6] Rodrigues et al., 2009

How to cite: Gebara M.S. Cordeiro, L., S. Carreira, R., Ferreira, F., A. Rodrigues, T., and F. Abrantes, F.: Using lipid biomarker signatures to reconstruct marine primary production in the Iberian Margin over the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6745, https://doi.org/10.5194/egusphere-egu24-6745, 2024.

The last glacial cycle provides the opportunity to investigate large changes in the Atlantic Meridional Overturning Circulation (AMOC) beyond the small fluctuations evidenced from modern measurements. Paleotemperature records from Greenland and the North Atlantic, including the Iberian Margin, show an abrupt variability, called Dansgaard–Oeschger (DO) events, which is associated with abrupt changes of the AMOC. These DO events also have Southern Hemisphere counterparts via the thermal bipolar seesaw, a concept describing the meridional heat transport leading to asynchronous temperature changes between both hemispheres. However, temperature records from the North Atlantic, notably the Iberian Margin, show more pronounced DO cooling events during massive releases of icebergs known as Heinrich (H) events, contrary to ice-core–based temperature records from Greenland.

We present high-resolution temperature records over the last 160 kyr using several independent organic proxies (e.g., RI-OH′, TEX86, and UK′37) from three deep-sea sediment cores located in a north-south transect along the Iberian Margin (cores MD99-2331, MD95-2040, and MD95-2042). Over the 160–45 ka BP period, the recent RI-OH′ proxy yields faithful temperature records along the Iberian Margin in comparison with established paleotemperature proxies (e.g., TEX86 and UK′37; Davtian et al., 2021 Paleoceano. Paleoclim. https://doi.org/10.1029/2020PA004077). In the southern Iberian Margin (core MD95-2042), the RI-OH′ and UK′37 proxies faithfully reflect the contrasting DO cooling amplitudes with and without H events over the last glacial cycle (Davtian et al., 2021; Davtian and Bard, 2023 PNAS https://doi.org/10.1073/pnas.2209558120).

We also revisit the thermal bipolar seesaw model using two independent temperature records (RI-OH′ and UK′37) from the southern Iberian Margin (core MD95-2042; Davtian and Bard, 2023). We show that temperature records from the southern Iberian Margin better support the classical thermal bipolar seesaw model than do ice-core–based temperature records from Greenland. We also introduce an extended thermal bipolar seesaw model that considers the contrasting DO cooling amplitudes with and without H events in the southern Iberian Margin, and a Bipolar Seesaw Index to distinguish DO cooling events with and without H events. Our data-model comparison emphasizes the role of the thermal bipolar seesaw in the abrupt temperature variability of both hemispheres with a clear enhancement during DO cooling events with H events, implying a relationship that is more complex than a simple flip-flop between two climate states linked to a tipping point threshold.

How to cite: Davtian, N. and Bard, E.: The value of Iberian Margin paleotemperature records with a novel organic proxy to revisit the bipolar seesaw model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6757, https://doi.org/10.5194/egusphere-egu24-6757, 2024.

EGU24-8238 | ECS | Orals | CL1.1.2 | Highlight

Astronomical pacing and abrupt changes in North Atlantic biogenic sedimentation during the latest Miocene and Early Pliocene: the IODP Site U1562 case study 

Boris Theofanis Karatsolis, Matthias Sinnesael, and Expedition 395/395C scientists

The latest Miocene and Early Pliocene (7-3.6 Ma) include key paleoclimatic and paleoceanographic events such as the Messinian Salinity Crisis (MSC), the late Miocene to Pliocene biogenic bloom (hereafter referred as “biogenic bloom”) and its potential termination, as well as the warm early Pliocene, a commonly used analogue for future global warming. Limited information exists regarding how these events impacted North Atlantic ocean circulation and carbonate sedimentation, mainly due to the lack of continuous, high-resolution records in high latitudes. During the summers of 2021 and 2023, the International Ocean Discovery Program (IODP) Expeditions 395C and 395 drilled a transect of five sites in the North Atlantic (at ~60°N). Preliminary results indicate that IODP Site U1562 has continuous sediment recovery, significant variations in carbonate content, as well as good preservation of calcareous fossils across the latest Miocene to Pliocene, making it a suitable candidate for high-resolution paleoclimatic reconstructions. Here, we estimate carbonate sedimentation and paleoproductivity for this site using high-resolution X-Ray fluorescence (XRF) records, derived from elemental intensities measured in core half-sections. Ratios between biogenically derived and detrital elements reveal the orbitally controlled pacing of carbonate production/deposition, as well as a stepwise, sustained decrease in biogenic sedimentation that occurred during the early Pliocene. The latter shift could have been linked to ocean current reorganizations related to the termination of the MSC or the “biogenic bloom”. Finally, we use a cyclostratigraphic approach to explore the possibility of building an astronomically tuned age model for this site using the XRF records.

How to cite: Karatsolis, B. T., Sinnesael, M., and 395/395C scientists, E.: Astronomical pacing and abrupt changes in North Atlantic biogenic sedimentation during the latest Miocene and Early Pliocene: the IODP Site U1562 case study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8238, https://doi.org/10.5194/egusphere-egu24-8238, 2024.

EGU24-9579 | ECS | Orals | CL1.1.2

High-Resolution Sea and Lake Level Reconstructions of the Late Cretaceous: Evidence for a 'Seesaw' Ocean-Land Water Circulation Model 

Kaixuan Ji, Mingsong Li, Fanhao Gong, Haotian Zhang, Shuai Yuan, and Dejun Zhang

The investigation into water circulation mechanisms within greenhouse environments, particularly their link to orbital forcing and consequent impacts on organism-environment coevolution, is garnering increased attention. A key uncertainty is the nature of variations in continental and oceanic water reservoirs on an ice-free Earth and the primary factors driving sea level changes. Traditional approaches like sequence stratigraphy and sedimentology have provided rough and limited insights, hindering a detailed and comprehensive understanding of water circulation in deep time. Therefore, high-resolution inversion of sea and lake level changes is vital for studying global hydrological cycle. Employing advanced sedimentary noise models (DYNOT and ρ1), based on astrochronology and time-series analysis, this research reconstructs detailed water-level variations in key regions: the continental Songliao Basin of Northeast China, the marine Basque-Cantabric Basin in Spain, and the marine Espírito Santo Basin in the western South Atlantic, covering the entire Maastrichtian Stage to the Cretaceous-Paleogene (K-Pg) boundary. These reconstructions, corroborated by sedimentary facies analysis and paleosol studies, reveal 1.2 Myr and 2.4 Myr periodic variations in sea and lake levels, exhibiting a 'seesaw' pattern of opposite trends. This indicates that sea level fluctuations might be influenced by changes in continental water reservoir content, providing new insights into the complex interplay between terrestrial and marine hydrological systems.

How to cite: Ji, K., Li, M., Gong, F., Zhang, H., Yuan, S., and Zhang, D.: High-Resolution Sea and Lake Level Reconstructions of the Late Cretaceous: Evidence for a 'Seesaw' Ocean-Land Water Circulation Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9579, https://doi.org/10.5194/egusphere-egu24-9579, 2024.

EGU24-12155 | ECS | Posters on site | CL1.1.2

Linear and non-linear Time Series Analysis of pan-African Hydroclimate spanning the past 1,200 kyr 

Markus L. Fischer, Norbert Marwan, Verena Foerster, Frank Schaebitz, Eleanor M.L. Scerri, Wolfgang Schwanghart, Stefanie Kaboth-Bahr, and Martin H. Trauth

The time between 1,200 kyr BP and today includes the Mid-Pleistocene Transition, the Mid-Bruhnes Event, and the late Pleistocene. The Early-Mid Pleistocene Transition (~920 kyrs BP) is one of the most dramatic shifts in high-latitude climate and marked by the onset of the strong 100 kyr glacial-interglacial cycles. The Mid-Bruhnes Event marks a significant increase in the amplitude of the glacial-interglacial cycles. It has been identified mostly in marine sediments and Antarctic ice cores, but it is currently discussed whether it was a globally synchronous phenomenon, including the African continent. Marine records suggest a shift towards increased aridity in parts of Africa, and terrestrial records from eastern Africa indicate a generally wet climate, possibly with a transition from stable to unstable, as suggested by the Olorgesailie record. 
At this time, robust Australopithecines went extinct, and only the genus Homo survived as H. ergaster, which ultimately led to the emergence of our own species, H. sapiens. The time vector also includes the second major expansion wave of H. ergaster out of Africa (1.39–0.9 Ma, after the first wave at ~1.9–1.4 Ma), possibly through the Sinai land bridge, but expansions through the Gibraltar strait and via the Bab el- Mandeb strait and into the southern Arabian Peninsula are also subject to lively discussed.
Here, we present the first insights into a comprehensive linear and non-linear analysis of five prominent records, which are (1) the dust record from ODP site 659 from western Africa, (2) the dust record from the Arabian Sea from ODP site 721/722, (3) the river runoff record from MD96-2048, (4) the combined dust and river runoff wetness index from ODP site 967, and (5) the south-western European ICDP record from Lake Ohrid. We use correlation metrics, such as the windowed Spearman correlation coefficient, to test for spatiotemporal synchronicity, asynchronicity, and possible interferences with the hominin fossil record. Furthermore, we use non-linear analysis, such as recurrence plots and recurrence quantification analysis, to test whether prominent climate transitions or spatiotemporal shifts in the fossil record are in temporal alignment with recurrence-based insights.

How to cite: Fischer, M. L., Marwan, N., Foerster, V., Schaebitz, F., Scerri, E. M. L., Schwanghart, W., Kaboth-Bahr, S., and Trauth, M. H.: Linear and non-linear Time Series Analysis of pan-African Hydroclimate spanning the past 1,200 kyr, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12155, https://doi.org/10.5194/egusphere-egu24-12155, 2024.

The climate variations in the past are strongly connected with the cycles of orbital forcing. The orbital forcing redistributes incoming solar energy on the Earth surface, especially over different latitudes. These cycles affect significantly seasons on millennial time scales. The most important influence on climate is provided by the variations of orbit eccentricity, obliquity and precession of Earth axis of rotation. The so-called Milankovitch cycles of eccentricity and obliquity are connected with the processes of glaciations during the last 3 Ma. Actually, all orbital cycles affect paleoclimate, where the effects of eccentricity dominate. The influence of orbital forcing on paleoclimate variations is investigated by two long time series of eccentricity from Laskar’s solution and sea level variations, reconstructed for the last 65 Ma. Common cycles of eccentricity and sea level in 18 different frequency bands are extracted by the Method of Partial Fourier Approximation. The short-periodical cycles, whose periods are below 400 kyr, have relatively good agreement for the last 3 to 7 Ma. The long-term oscillations of sea level and orbit eccentricity with periodicities between 0.8 Myr and 10.8 Myr have excellent agreement in 4 frequency bands, whose duration is 65 Myr. In other 5 frequency bands a good correlation exists for the last 35 – 40 Ma. The estimated amplitudes of sea level cycles are between 2 and 5 m with accuracy of about 0.4 m. The jumps inside of sea level time series are determined by a high-sensitive Method of Jump Detection, based on numerical integration of the time series. The detected jumps determine various data segments, whose duration is below 2.8 Myr and the rate of their linear trends is between 0.3 cm/kyr and 3 cm/kyr. The remarkable result is that all detected jumps occur during the extrema of eccentricity, while the jumps of sea level during glacial cycles in the last 3 Ma occur only in eccentricity minima. These results can help better understanding of climate response to orbital forcing. 

How to cite: Chapanov, Y.: Climate Variations Connected with Earth Orbit Eccentricity , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12267, https://doi.org/10.5194/egusphere-egu24-12267, 2024.

EGU24-13153 | ECS | Posters on site | CL1.1.2 | Highlight

Late Pliocene onset of millennial climate variability during the intensification of Northern Hemisphere Glaciation 

Mengyao Du, Simon Crowhurst, Maryline Mleneck-Vautravers, David Hodell, Fatima Abrantes, Carlos Alvarez Zarikian, and Expedition 397 Scientific Party

The retrieval of sediment cores from Site U1385 during Expedition IODP 397 off the Iberian Margin has yielded a high-fidelity record extending back to the base of Pliocene. This record provides an unprecedented opportunity to investigate the onset of millennial climate variability associated with the intensification of Northern Hemisphere Glaciation (iNHG) during the late Pliocene. Elemental ratios, specifically Ca/Ti and Zr/Sr, measured by core scanning X-ray fluorescence (XRF) have uncovered four distinct millennial climate events in Marine Isotope Stages (MIS) G6, G4, G2 and 104. These single ‘precursor events’ precede the onset of pronounced millennial climate variability marked by multiple events beginning with MIS 100 (2.54 Ma).

The planktic δ18O record of Globigerina bulloides exhibits an increase associated with the peak in Zr/Sr and minimum in Ca/Ti, indicating colder temperatures during the stadial event in MIS G4 (2.69 Ma). A comparison with the δ18O record of mixed benthic foraminifera (Cibicidoides wuellerstorfi and Uvigerina peregrina) indicates that the identified cold stadial in MIS G4 coincided with the end of MIS G4 just before the deglaciation to MIS G3. We therefore suggest it represents a terminal stadial event, which is common during the latest part of glacial stages during the Quaternary. Moreover, the precursor stadial events of MIS G6, G4, G2 and 104 at Site U1385 can be correlated 1:1 to peaks in ice-rafted debris (IRD) in the high-latitude North Atlantic, indicating a connection to iceberg calving and freshwater forcing. Our results indicate that ice sheets had grown large enough during the glacial stages of the latest Pliocene to induce a significant response to freshwater forcing upon deglaciation.

How to cite: Du, M., Crowhurst, S., Mleneck-Vautravers, M., Hodell, D., Abrantes, F., Alvarez Zarikian, C., and 397 Scientific Party, E.: Late Pliocene onset of millennial climate variability during the intensification of Northern Hemisphere Glaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13153, https://doi.org/10.5194/egusphere-egu24-13153, 2024.

EGU24-13215 | Orals | CL1.1.2

Decoding major Climate Mysteries over the last 1.5 million years: Sea Surface Temperature Reconstruction at IODP Site U1385, Iberian Margin. 

Teresa Rodrigues, Joan O. Grimalt, Marta Casado, Yolanda Gonzalez, Simon J. Crowhurst, Fátima Abrantes, and David Hodell

The Iberian Margin provides a remarkably accurate record of millennial-scale climate variability, making it an invaluable site for deciphering historical changes in climate and oceanography. This region’s exceptional sensitivity to high latitude processes, such as meltwater discharges into the Northeast Atlantic, significantly influence ocean dynamics, nutrient supply, and climate change impacts. These processes play a pivotal role in understanding the complex interplay between the ocean, ice, and climate systems. IODP 339 Site U1385, also known as the “Shackleton site”, drilled at a water depth of 2582 mbsl, reaching a total depth of 155.9 m below the seafloor. The oxygen isotope and carbon isotope records confirm that Site U1385 contains a continuous hemipelagic sedimentation from the Holocene to 1.45 million years (MIS 47), providing a reference record of millennial-scale climate variability. Here, we present a high-resolution Sea Surface Temperature (SST) record that unveils the climate variability over the last 1.45 million years.  This record provides a comprehensive interpretation of the millennial climate variability of major climatic disruptions, namely the Mid Brunhes Event and Mid Pleistocene Transition (MPT). SST data reveals a clear change on the orbital-driven forcing on the MPT time interval 1200 to 800 ka, thereby contributing to our understanding the underlying mechanisms on glacial/interglacial and centennial to millennial scales. Furthermore the SST record shows extreme cold events occurred not only after the MPT but also during and after this enigmatic period. The highest temperatures were recorded during Interglacial periods, overall the record and coincident with maximum insolation (precession minimum), suggesting an orbital dependence of the Sea Surface Temperature (SST) over the past 1.45 million years. This SST record significantly contribute to documenting the major climate shifts and their relation to global climate change. This becomes particularly crucial as the IODP Expedition 397 enables the extension of this exceptional sediment record into the Pliocene.

How to cite: Rodrigues, T., O. Grimalt, J., Casado, M., Gonzalez, Y., J. Crowhurst, S., Abrantes, F., and Hodell, D.: Decoding major Climate Mysteries over the last 1.5 million years: Sea Surface Temperature Reconstruction at IODP Site U1385, Iberian Margin., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13215, https://doi.org/10.5194/egusphere-egu24-13215, 2024.

EGU24-13997 | ECS | Posters on site | CL1.1.2

Body size variability of North Atlantic benthic fauna driven by bottom-water temperature and oxygen during late Quaternary glacial-interglacial cycles 

Huai-Hsuan May Huang, Curtis Deutsch, Thomas Cronin, Carlos Alvarez Zarikian, Fatima Guedes Abrantes, and David Hodell and the Expedition 397 Scientists

Organism body size is a critical aspect of marine ecosystems and is influenced by climate change on seasonal to geologic time scales. Recent integration of mechanistic models of metabolism, laboratory experiments, and fossil records has opened a new avenue for understanding the roles of thermal sensitivity and hypoxia tolerance in body-size evolution. Here we explore climatic factors driving intraspecific body size variability of benthic ostracods in the central and eastern North Atlantic Ocean. We analyzed over 300 adult shell sizes of multiple ostracod species in the genus Krithe at Sites Chain 84-24-4PC (42°N, 33°W, 3427 m water depth) for the past ~50,000 years and IODP U1588 (37°N, 9°W, 1139 m water depth) for the past ~700,000 years. Chain 84-24-4PC and U1588 are predominantly influenced by North Atlantic Deep Water (NADW) and Mediterranean Outflow Water (MOW) today, respectively. Results show that size reduction corresponded to up to 5 °C deglacial warming during the interval 22-14 ka (MIS 2-1) at the Chain 84-24-4PC core site. Even more striking, size varies 60-70% during major glacial-interglacial transitions (MIS6-5, MIS12-11, and MIS16-15) at Site U1588. The differences observed in the magnitude of size reduction between the two sites are likely influenced by the varying ranges of temperature and, potentially, oxygen variability at their respective water depths. We discuss the potential of using body size changes to reconstruct variability in temperature and oxygen across glacial-interglacial cycles.

How to cite: Huang, H.-H. M., Deutsch, C., Cronin, T., Alvarez Zarikian, C., Guedes Abrantes, F., and Hodell, D. and the Expedition 397 Scientists: Body size variability of North Atlantic benthic fauna driven by bottom-water temperature and oxygen during late Quaternary glacial-interglacial cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13997, https://doi.org/10.5194/egusphere-egu24-13997, 2024.

EGU24-15130 | ECS | Posters on site | CL1.1.2 | Highlight

On the impact of astronomical forcing on ocean anoxia 

Justin Gérard, Jarno Huygh, Loïc Sablon, Michel Crucifix, and Anne-Christine Da Silva

The Devonian is a warmer-than-present geological period spanning from 419 to 359 million years ago (Ma) characterized by 29 identified ocean anoxic/hypoxic events. Despite decades of extensive investigation, no consensus regarding the mechanisms responsible for ocean anoxia has been achieved. Our study contributes to this general research effort, focuses on the astronomical pacing of anoxia throughout the Devonian and is substantiated by growing geologic records suggesting a link between astronomical forcing and anoxic events during this period. To investigate the role of the astronomical forcing we used the Earth system Model of Intermediate Complexity (EMIC) cGENIE, which has proven to be a reliable choice to simulate ocean oxygen spatial patterns and values. In this project, we first tested the impact of continental configuration and ocean biogeochemistry (pCO$_2$, PO$_4$ and pO$_2$) on the equilibrium of the system and the related dissolved ocean oxygen concentration. Then, we produced an in-depth analysis of the astronomical forcing contribution to ocean anoxia for well-chosen continental reconstruction and biogeochemical quantities values. Our results indicate that variations in continental configuration, even small, can exert a strong impact on ocean anoxia, underscoring the influence of paleoreconstructions uncertainties on the biogeochemical tracers of cGENIE. The astronomical forcing reveals to be able to modify the nature of the equilibrium of the system, going from a single-state value solution to an oscillatory behaviour. Our findings also offer insights into potential ocean lockdown mechanisms, providing plausible explanations for the prolonged persistence of certain anoxic events over several hundred thousand years.

How to cite: Gérard, J., Huygh, J., Sablon, L., Crucifix, M., and Da Silva, A.-C.: On the impact of astronomical forcing on ocean anoxia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15130, https://doi.org/10.5194/egusphere-egu24-15130, 2024.

EGU24-15648 | Orals | CL1.1.2

Paleoproductivity and surface water dynamics evolution during the MIS 31 in the Shackleton Site as revealed Coccolithophores 

Jose-Abel Flores, Barbara Balestra, William Clark, Francisco José Jiménez-Espejo, Junichiro Kuroda, Emilia Salgueiro, Joan Grimalt, Timothy Herbert, Maria Angeles Bárcena, Fatima Abrantes, David Hodell, Carlos Alvarez Zarikian, and Expedition 397 Scientific Party

Marine Isotope 31 Stage (MIS-31) records one of the highest high-latitude precession-paced insolation values of the last 5 million years (Laskar et al., 2004). According to this configuration, some studies (e.g. Raymo et al., 2006) predicts a +20 m eustatic sea-level rise for this time interval, reflecting significant retreat of some combination of the West Antarctic Ice Sheet, marginal East Antarctic ice, and the Greenland Ice Sheet, and consequently significant variations in the ocean and climate dynamics at global scale.

In this study we show data of variability in the coccolithophore assemblage from IODP Site 1385 (Shackleton Site, IODP 339 and IODP 397) in the interval ca. 1 Ma (close to the Jaramillo event). These sediments are sensitive recorders of North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) oscillations, which makes this site a significant location to test the interhemispheric connection hypotheses.

Peaks in abundance of Gephyrocapsa (<3mm), as well as in other Noelarhaddaceae such as Reticulofenestra asanoi and other morphotypes (equivalent with minimum differences at total coccoliths recorded), were interpreted as a signal of paleoproductivity, revealing strong changes during MIS 31. Alternatively, cold water indicators (Coccolithus pelagicus ) or the census of Helicosphaera carteri l(inked to stratification processes) are considered, showing an alternative pattern along the studied interval. After the refinement of the age-model, these data should be compared with other records in close or remote areas (e.g. Flores and Sierro, 2007, Maiorano et al., 2009), to understand the relevance of this interval, particularly sensible in the Antarctic environment, where a potential relevant melting peak was suggested (Scherer et al., 2009).

Preliminary results (Jiménez Espejo et al., 2013) reveal a distinct turnover during MIS 31 and different evolution of surface and bottom-waters that could be linked with enhanced circulation of NADW during warm periods. This scenario is consistent with stratification pulses interpreted at the top of MIS 32, where cold and stratified water pulses are influenced by and increase in reworked material coming from proximal regions as a result of eustatic sea-level drops.

 

Laskar, J., Robutel, P., Joutel, F., Gastineau, M., Correia, A.C.M., & Levrard, B. Astrophys. 428, 261-285 (2004).

Raymo, M., Lisiecki, L., Nisancioglu, K. Science. 313, 492-495 (2006).

Maiorano, P., Marino, M., Flores, J.A. Mar. Micropaleontol. 71, 166–175 (2009).

Flores, J.A., Sierro, F.J. Deep-Sea Res. II 54 (21–22), 2432–2442. (2007)

Scherer, R. P., Bohaty, S., Dunbar, R., Esper, O., Flores, J., Gersonde, R., Harwood, D., Roberts, A., and Taviani, M. Geophysical Research Letters. 35, (2009)

Jiménez Espejo et al., 11th INTERNATIONAL CONFERENCE ON PALEOCEANOGRAPHY

1-6 September, 2013. Sitges - Barcelona (2013)

 

How to cite: Flores, J.-A., Balestra, B., Clark, W., Jiménez-Espejo, F. J., Kuroda, J., Salgueiro, E., Grimalt, J., Herbert, T., Bárcena, M. A., Abrantes, F., Hodell, D., Alvarez Zarikian, C., and 397 Scientific Party, E.: Paleoproductivity and surface water dynamics evolution during the MIS 31 in the Shackleton Site as revealed Coccolithophores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15648, https://doi.org/10.5194/egusphere-egu24-15648, 2024.

The lower Carboniferous is marked by the onset of the Late Paleozoic Ice Age (LPIA), one of the most severe and longest in Earth history, with a duration of nearly 100 million years [1]. The onset of the glaciation is associated with bursts of anoxia of different magnitudes through the Tournaisian and Visean stages (in the lower Carboniferous). These anoxic events are the Lower Alum Shale (LASE [2]) at the base of the middle Tournaisian, The Tournaisian Carbon Isotope Excursion (TICE, also called KOBE [3]) in the middle Tournaisian, and the Visean Carbon Isotope Excursion (VICE [4]). The particularity of these anoxic events is their development during a relatively cold period and their longer durations (5-10 Myr) compared to most other anoxic events. Clues have been accumulated pointing to the possibility that anoxia and glaciation may have been paced by changes in Earth’s orbit parameters ([5], [6], [7], [8]). These changes are the astronomical (Milankovitch) cycles (Eccentricity, Obliquity, and Precession) with specific durations. They impact the incoming solar radiation and seasonal contrasts, hence global climate. Cyclostratigraphy (The identification of astronomical cycles in the geological record) is the tool to establish a chronological framework (ATS) of the lower Carboniferous in order to reach precise estimates for the duration of these anoxic events. This precise timing is essential to get a better understanding of the climate response to astronomical forcing in the early Carboniferous. We also intend to delve into Milankovitch forcing related to ice age evolution and to understand the connection of anoxic events with climate dynamics and orbital forcing. In addition, precession and obliquity cycles are directly related to the Earth-Moon distance (and the length of the day). Through our study, we will provide a duration of precession and obliquity cycles which would allow to provide the Earth-Moon distance and length of the day for this period. Therefore, five geologic sections have been selected in the Namur-Dinant basin in Belgium and one section in Germany. Sections will undergo a high-resolution sampling then multiple analyses will be applied (major and trace elements, total organic carbon (TOC), and stable carbon isotopes(δ13C)). Different cyclostratigraphic techniques will be applied (e.g., MTM, ASM, TimeOpt, COCO, EHA) on specific paleoclimate proxies to build the chronostratigraphic framework. In fine, precession and obliquity cycles are directly related to the Earth-Moon distance (and the paleo-length of the day). Through our study we will provide a duration of precession and obliquity cycles which would allow us to provide the Earth-Moon distance and length of the day for this period, marked by a period of resonance of oceanic dissipation [9]. The study aims to deepen our understanding of the carboniferous ice age, its triggers, and Earth’s intricate climatic mechanisms.

[1]Crowley & Baum 1991. [2] Rakociński et al., 2021. [3] Yao et al., 2015. [4] Liu et al., 2019.  [5] Batenburg et al., 2019. [6] Batenburg et al., 2023. [7] Christine et al., 2020. [8] De Vleeschouwer et al., 2017. [9] Farhat et al., 2022.

How to cite: Boukhalfa, D. and Da Silva, A.-C.: Transition to glacial state through the lower Carboniferous and impact of orbital forcing on sedimentary records and anoxia expansion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16072, https://doi.org/10.5194/egusphere-egu24-16072, 2024.

EGU24-16409 | ECS | Posters on site | CL1.1.2

Paleoceanographic and paleoclimatic analyses throughout the MIS 5 interval: preliminary results from calcareous nannoplankton 

Carmen Argenio, José-Abel Flores, Barbara Balestra, Filomena Ornella Amore, David Hodell, Fatima Abrantes, Carlos Alvarez Zarikian, and Expedition Scientific Party

New insights about the Marine Isotope Stage (MIS) 5 over the North Atlantic area are presented in this study. The MIS 5 interval covers a timeframe from  ̴130 ka to 70 ka and it has been the last major interglacial interval occurred on Earth. In particular, the MIS 5e sub-interval, is a key period to study the possible evolution for human induced climate changes. It also represents an opportunity to interpret the natural climate evolution beyond the anthropic impact being interested by global temperatures assumed to be warmer than the pre-anthropogenic ones (e.g. Kopp et al., 2009). Likewise, the North Atlantic region is interesting for climatic studies being involved in the modulation of the global climate and in particular the Iberian margin is a well-known source of rapidly accumulating sediment offering a high-fidelity record of millennial climate variability.

With this contribution we show preliminary results concerning changes in hydrography and coccolithophores productivity from two sites recovered on the Promontorio dos Principes de Avis, SW Iberian Margin: U1385 (37°34.285’N; 10°7.562’W – 2585 meters below sea level), drilled during the Integrated Ocean Drilling Program Expedition 339, and U1586 (37º37.283’N; 10º42.628’W - 4691 meters below sea level), drilled during the International Ocean Discovery Program Expedition 397.

The phytoplankton group of coccolithophores has proved to be a high-quality environmental proxy since their geographic distribution and abundance is strongly influenced by parameters such as sea-surface temperature, salinity, sunlight and nutrient availability. Accordingly, coccolithophores are here used to describe paleoproductivity fluctuations in surface waters and upwelling strength as well as paleoceanographic changes linked to global climate evolution.

 

References

Kopp, R.E., Simons, F.J., Mitrovica, J.X., Maloof, A.C. & Oppenheimer, M. (2009). Probabilistic assessment of sea level during the last interglacial stage. Nature, 462 (863-867)

How to cite: Argenio, C., Flores, J.-A., Balestra, B., Amore, F. O., Hodell, D., Abrantes, F., Alvarez Zarikian, C., and Scientific Party, E.: Paleoceanographic and paleoclimatic analyses throughout the MIS 5 interval: preliminary results from calcareous nannoplankton, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16409, https://doi.org/10.5194/egusphere-egu24-16409, 2024.

EGU24-16488 | ECS | Orals | CL1.1.2

Understanding Astronomically Forced Carbon Cycle Feedbacks Through the Lens of an Earth System Model  

Pam Vervoort, Sandra Kirtland Turner, Dominik Hulse, Sarah Greene, and Andy Ridgwell

Milankovitch cycles recorded in marine sediments demonstrate the influence of astronomical forcing on Earth’s climate-carbon dynamics. Proxies suggest that during greenhouse climates, isotopically light carbon is released during episodic warm intervals (at eccentricity maxima) and re-sequestered during the following cooling (at eccentricity minima). However, the dominant carbon sources and sinks at play on orbital timescales remain unclear-- particularly when large dynamic ice sheets are absent as during the early Cenozoic. Methods: In an Earth system model (ESM), we apply 4-Myr-long transient astronomical forcing to examine how various climate-sensitive physical and (bio)geochemical processes respond and how this forcing is recorded in key oceanographic variables (temperature, pCO2, δ13C of DIC, and wt% CaCO3). Among others, we assess the impact of marine productivity, CaCO3 compensation, terrestrial weathering, organic matter burial, and phosphorus cycling. Results: Most processes are driven by changes in local conditions -controlled by obliquity and precession, but these high-frequency changes are converted to low-frequency eccentricity cycles expressed in pCO2, benthic δ13C, and wt% CaCO3 as a result of the lowpass filtering effect of the ocean reservoir. While the magnitude of early Cenozoic δ13C variability can be explained by astronomically forced input and burial fluxes of marine organic carbon alone, the dominant frequency and relative phasing of proxies highly depend on the geographic distribution of landmasses that control organic carbon fluxes. For example, only short eccentricity cycles of 100 kyr periodicity (as opposed to long 400 kyr cycles) are simulated in benthic δ13C under favorable paleogeographic configurations. In our model, the pCO2 and temperature response to orbital forcing is minimal, and eccentricity maxima coincide with enhanced preservation of CaCO3. In contrast, early Cenozoic proxies suggest a stronger temperature response and reduced CaCO3 preservation during warm intervals. Implication: Our results support the hypothesis that additional feedbacks that are not yet included here (e.g., terrestrial carbon or methane) were likely important controls during orbital-scale climate variability in greenhouse climates.

How to cite: Vervoort, P., Kirtland Turner, S., Hulse, D., Greene, S., and Ridgwell, A.: Understanding Astronomically Forced Carbon Cycle Feedbacks Through the Lens of an Earth System Model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16488, https://doi.org/10.5194/egusphere-egu24-16488, 2024.

EGU24-16683 | ECS | Orals | CL1.1.2

Intensification of the Indonesian Throughflow in a Coupled GCM During the Last Interglacial 

Sihua Wei, Weipeng Zheng, Jinlong Du, Yongqiang Yu, and Jun Tian

       The Indonesian Throughflow (ITF) plays a pivotal role in large-scale ocean-atmosphere interactions in the tropics, regulating the heat and freshwater budget between the Pacific and Indian Oceans. In the context of global warming in the 21st century, The Indonesian Throughflow are projected to be weaken (medium confidence) by CMIP6 simulations. As an analog of possible future warming, the Last Interglacial (LIG, Marine Isotope Stage 5e or Eemian), with global surface temperature reached about 2 °C above present, serves as an outstanding period to explore the climate response to the external forcing and the mechanisms behind it.

       We use the model outputs from a set of Last Interglacial snapshot simulations carried out by CAS-FGOALS (the Chinese Academy of Sciences Flexible Global Ocean–Atmosphere–Land System model) under the protocol of PMIP for four time periods at 130, 128, 125, and 115 ka. Compared to the piControl simulations (the annual mean ITF flux is 18.46Sv), an annual mean ITF flux increase of about 30.6% - 35.9% was found in the LIG snapshot simulations (24.11 - 25.08Sv). During the LIG, the tropical western Pacific Ocean thermocline was deepened while the tropical eastern Indian Ocean thermocline was relatively shallowed, which was closely tied to the strengthening of the surface easterlies above the tropical western Pacific. Correspondingly, the gradient of the sea surface height between the tropical western Pacific and the tropical eastern Indian Ocean increased, causing pressure contrast between the two basins and probably contribute to the ITF strengthening. We also find that the thermocline gradient between the tropical western Pacific and tropical eastern Pacific was increased, suggesting a La Niña-like state during the LIG. Comparisons of models and proxies further support our conclusions. An examination of the changes in the thermocline water temperature (TWT) record from the eastern Indian Ocean found an enhancement of ITF during MIS 5. Besides, the Maritime Continent was supposed to be more humid by pollen records from west Java and sediment composition from Halmahera Sea.

       Further analysis suggested that the strengthened ITF during the LIG is inconsistent with the weakened one in the 21st century. While the future global warming is primarily driven by increased CO2 levels, the climate changes during the LIG were principally caused by changes in orbital parameters.

How to cite: Wei, S., Zheng, W., Du, J., Yu, Y., and Tian, J.: Intensification of the Indonesian Throughflow in a Coupled GCM During the Last Interglacial, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16683, https://doi.org/10.5194/egusphere-egu24-16683, 2024.

EGU24-17195 | Orals | CL1.1.2 | Highlight

Pre-Cenozoic cyclostratigraphy and paleoclimate responses to astronomical forcing 

David De Vleeschouwer, Lawrence M.E. Percival, Nina M.A. Wichern, and Sietske J. Batenburg

Astronomical insolation forcing is well established as the underlying metronome of Quaternary ice ages and Cenozoic climate changes. Yet its effects on earlier eras (Mesozoic, Palaeozoic and pre-Cambrian) are less understood. In this Review, we explore how cyclostratigraphy can help to distinguish climate modes over the pre-Cenozoic era and aid our understanding of climate responses to astronomical forcing over geological time. The growing uncertainties with geologic age mean that pre-Cenozoic astronomical solutions cannot be used as tuning targets. However, they can be used as metronomes to identify the pacing of distinct climate states. Throughout the pre-Cenozoic, global average temperature differences between climate states were even more extreme (5–32 °C) than in the Cenozoic (14–27 °C), and these, combined with an evolving biosphere and changing plate tectonics, led to distinct Earth-system responses to astronomical forcing. The late Palaeozoic icehouse, for example, is characterized by a pronounced response to eccentricity, caused by nonlinear cryosphere and carbon-cycle behaviour. By contrast, the Devonian warmhouse and the Late Cretaceous hothouse featured recurrent episodes of marine anoxia that may have been paced by astronomical forcing. Formally defining 405,000-year eccentricity cycles as chronostratigraphic units (astrochronozones) throughout the Phanerozoic eon will enable a more comprehensive understanding of how astronomical forcing has shaped Earth’s climate over geologic time.

How to cite: De Vleeschouwer, D., Percival, L. M. E., Wichern, N. M. A., and Batenburg, S. J.: Pre-Cenozoic cyclostratigraphy and paleoclimate responses to astronomical forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17195, https://doi.org/10.5194/egusphere-egu24-17195, 2024.

EGU24-17892 | Posters on site | CL1.1.2

Testing the deep water source variations in the Atlantic Iberian margin over the last deglaciation 

Susana M. Lebreiro, Laura Antón, Silvia Nave, Claire Waelbroeck, Edouard Bard, Luke Skinner, Isabel Reguera, Elisabeth Michel, Natalia Bravo, Jordi F. Lopez, Belen Martrat, Teresa Rodrigues, Eva Bellido, and Francisco Sierro

The reservoir age of waters and carbon sequestration increased in the deep Atlantic Ocean during the last glacial period. The glacial northern deep water (GNADW) formation reached shallower depths than during the ensuing interglacial, and the underlying southern-sourced bottom water (GAABW) was filling the basin, generally poorly ventilated. The mechanisms within the deep ocean that facilitate the flip from glacial-to-interglacial modes are as yet to be understood.  

Here we present analysis performed on foraminifera (benthic δ13C, abundance of oxygen-tolerant benthic species and 14C age difference between benthic and planktonic species), together with the n-hexacosan-1-ol index (biomarker of the oxygenation of the deep-sea floor) in three deep cores at the Atlantic Iberian margin (ca. -5,000 m depth; 40°N). The locations selected follow the pathway of the Northeast Atlantic Deep Water (NEADW): MD03-2698 (Tagus Iberian margin), D219 (Rincão da Pomba) and MD13-3473 (Tore inner basin). Additionally, results of polar northern and southern sites (U1308 and TN057-21 respectively) are discussed as a reference for evaluating long-distance connections. 

The hypothesis to be tested is whether the deep waters off Iberia were northern- or southern-sourced during the deglaciation within the Tore seamount, a crater-shaped geological structure, 300 km off the Iberian continental shelf. It includes an inner basin down to -5,500 m, isolated from the oceanic basin by a summit rim at -2,200 m. The external connection with the Atlantic is by two narrow NW and NE gateways down to –4,300 m. This makes the area a singular spot to decipher the NEADW-end member of the Atlantic deep circulation. 

We find benthic (Cibicidoides wuellerstorfi) δ13C values around 0 ‰ in the interior of the Tore before 18 ky, slightly heavier than those known from shallower Iberian sites (ca. -3,500 m). This points to isolation of the Tore basin from the influence of GAABW. This contrasts with the other sites MD03-2698 and D219 which record δ13C around -0.6 ‰, similarly to TN057-21 values. Inside the Tore, benthic foraminifera species grouped according to their oxygen tolerance are oligotrophic during the glacial (oxygen-rich, more ventilated conditions) and mesotrophic over the Holocene (intermediate ventilation).

The carbon residence time measured in MD03-2698 and D219, as estimated from the 14C age difference between benthic and planktonic foraminifera, confirms previous reservoir ages in the deep Iberian margin (MD99-2334K; JC89-SHAK03-6K, JC89-SHAK05-3K). In the inner basin (MD13-3473), the estimation is not valid, probably due to increased bioturbation, lower sedimentation rates and mixing turbiditic flow. 

The hexacosanol index marks the lowest ventilation pattern culminating around 16 ky (MD03-2698, D219), an apparent inflection point from when the ventilation shifts from southern to northern sourced deep waters, the former not registered in the inner Tore (MD13-3473). This occurs in line with a large reduction in the Atlantic meridional overturning circulation (AMOC) and maximum extent of ice sheets. Taken together, interactions between atmospheric, marine, cryosphere and terrestrial climate elements, as recorded by different proxies during the stadial multi-step structure associated within Heinrich event 1 (H1.1) are giving clues to the processes bringing about deglaciation.

How to cite: Lebreiro, S. M., Antón, L., Nave, S., Waelbroeck, C., Bard, E., Skinner, L., Reguera, I., Michel, E., Bravo, N., Lopez, J. F., Martrat, B., Rodrigues, T., Bellido, E., and Sierro, F.: Testing the deep water source variations in the Atlantic Iberian margin over the last deglaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17892, https://doi.org/10.5194/egusphere-egu24-17892, 2024.

EGU24-18468 | ECS | Orals | CL1.1.2

Changes in the response of the carbon cycle to astronomical forcing during the Silurian Ireviken biogeochemical event 

Michiel Arts, Brad Cramer, Mikael Calner, Christian M. Ø Rasmussen, and Anne-Christine Da silva

The Silurian Ireviken Event is a biogeochemical event characterised by extinctions among several marine groups and a major perturbation to the global carbon cycle. In the Altajme core from Gotland, Sweden, the associated Ireviken Carbon Isotope Excursion (ICIE) reaches peak values of ~6‰. Within the ICIE, the main peak of -6‰ (δ13Ccarb) is superimposed by multiple short-term and small amplitude positive peaks (+1.00 ‰ δ13Ccarb), while the tail of the main peak is superimposed by multiple small amplitude negative peaks (-1.55 ‰ δ13Ccarb). To understand the processes behind these recurrent small amplitude peaks, the high-resolution XRF scanning data of the Altajme core were used to identify astronomical cycles to put astrochronological constraints on the δ13Ccarb curve. Based on the XRF data and its resulting astrochronology, the small amplitude positive and negative δ13Ccarb peaks occur during insolation minima in intervals enriched in carbonate relative to the surrounding lithology. The XRF proxy data indicates that during times when elevated carbonate content coincides with elevated δ13Ccarb values, insolation minima induced an arid environmental state in the basin. This led to decreasing runoff and a strong anti-estuarine circulation, which in turn lowered pelagic productivity and increased photozoan carbonate production, resulting in the deposition of carbonates with elevated δ13Ccarb values. This contrasts to the concomitant insolation maximum, which induced a semi-arid state in the basin, resulting in some runoff, a (sluggish) anti-estuarine circulation in the basin, some pelagic productivity and carbonates being primarily produced by heterozoans, resulting in the deposition of marly carbonates with low δ13Ccarb values. The XRF proxy data indicates that during times when carbonate-rich intervals coincide with more negative δ13Ccarb values, insolation minima induce a semi-arid state in the basin, resulting in some runoff, a (sluggish) estuarine circulation in the basin, some pelagic productivity and carbonates being primarily produced by heterozoans resulting in the deposition of marly carbonates with low δ13Ccarb values. This contrasts with the concomitant insolation maximum which induced humid conditions in the basin, resulting in increased runoff, a (strong) estuarine circulation and high primary productivity, leading to the deposition of marly shales with higher δ13Ccarb values. The shifting baseline climatic conditions during the Ireviken Event are inferred to have changed the response of the depositional environments to astronomical forcing, in changing (carbonate) productivity and circulation, which in terms modulated the carbon cycle, resulting in an imprint of astronomical cycles in the ICIE.

How to cite: Arts, M., Cramer, B., Calner, M., Rasmussen, C. M. Ø., and Da silva, A.-C.: Changes in the response of the carbon cycle to astronomical forcing during the Silurian Ireviken biogeochemical event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18468, https://doi.org/10.5194/egusphere-egu24-18468, 2024.

EGU24-18823 | Posters on site | CL1.1.2

Exploring the Plio/Pleistocene stratigraphy of the Upper Rhine Graben from a core taken at a Riedstadt/Hesse 

Christian Zeeden, Mohammad Paknia, Stephanie Scheidt, Stefanie Kaboth-Bahr, Mathias Vinnepand, and Christian Hoselmann

The past subsidence episodes of the northern Upper Rhine Graben allowed the accumulation of thick sedimentary sequences that can function as excellent data source for paleoclimate reconstructions. A 323 m long sediment core drilled in 2020-2021 near Riedstadt-Erfelden (~14 km WSW of Darmstadt) is therefore likely a high-resolution geoarchive documenting climate dynamics during the Plio-Pleistocene epochs. So far, the chronostratigraphic framework is based only on lithostratigraphic assignments. This study presents inclination values and magnetic susceptibility obtained from whole-core measurements and discusses initial stratigraphic ideas based on the resulting preliminary magnetic polarity stratigraphy and cyclostratigraphic assessments of the ‘Riedstadt-Erfelden’ core.

Here, we highlight on the quasi-cyclic components of the core, and provide an interpretation in the light of paleomagnetic dating.

How to cite: Zeeden, C., Paknia, M., Scheidt, S., Kaboth-Bahr, S., Vinnepand, M., and Hoselmann, C.: Exploring the Plio/Pleistocene stratigraphy of the Upper Rhine Graben from a core taken at a Riedstadt/Hesse, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18823, https://doi.org/10.5194/egusphere-egu24-18823, 2024.

EGU24-19442 | Orals | CL1.1.2

Strength variability of the Mediterranean Outflow Water during late Quaternary: Preliminary results from IODP Site U1588 

Jiawang Wu, Xinyang Chen, Zongxian He, Qin Deng, Lifeng Zhong, Xiaolei Pang, David Hodell, Fatima Abrantes, and Carlos Alvarez Zarikian and the Expedition 397 Scientific Party

The Mediterranean Sea is thought to play a role in changing past ocean circulation and North Atlantic climate, through the outflow of warm, saline intermediate waters (Mediterranean Outflow Water; MOW) into the North Atlantic. Previous studies mostly focused on the Gulf of Cádiz, immediately after the MOW existing the Mediterranean, but how the MOW varied along the northward transport is still unclear. Fine grain-size parameters have been widely employed to infer paleo-flow speeds of near-bottom currents in the deep sea, in particular the terrigenous non-cohesive “sortable silt” (denoted as SS) controlled by selective deposition. Here we present terrigenous sediment grain size results on IODP Site U1588 (37°57.61′N, 9°30.99′W, 1339 m water depth), which was retrieved from the Iberian Margin during the IODP Expedition 397. Our aim is to reconstruct strength variations in the lower branch of the MOW over the past ~250,000 years. After removing organic matter (leached with 10% H2O2 at 85 ℃) and marine carbonates (leached with 0.5 M HCl), the terrigenous detrital component of about 100 samples were measured on a Malvern Mastersizer 3000 instrument. Our grain-size results show a bimodal distribution, with a small peak near 1 μm and the main mode between 5–8 μm. The correlation between the percentage and mean of the sortable silt fraction (10–63 μm) is significant (R2=0.43, P<0.01), permitting the use of SS-mean as a reliable indicator of the deep-sea current strength. The calculated SS-mean is from ~14.2 to 18.2 μm, corresponding to the flow speed of ~3.3 to 10.2 cm/s. Based on the shipboard age model, our results show a persistent low-latitude forcing of MOW flow speed over the past 250,000 years, with strong precessional and glacial cycles.

How to cite: Wu, J., Chen, X., He, Z., Deng, Q., Zhong, L., Pang, X., Hodell, D., Abrantes, F., and Zarikian, C. A. and the Expedition 397 Scientific Party: Strength variability of the Mediterranean Outflow Water during late Quaternary: Preliminary results from IODP Site U1588, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19442, https://doi.org/10.5194/egusphere-egu24-19442, 2024.

EGU24-19840 | Orals | CL1.1.2 | Highlight

Precessional Climate Cyclicity on the Iberian margin: Miocene-recent 

Timothy Herbert, Fatima Abrantes, Hannah Brooks, Jose-Abel Flores, David Hodell, Jerry McManus, Bryce Mitsunaga, Celeste Palone, Xioalei Pang, Jiawang Wu, Jimin Yu, and Carlos Zarikian and the Expeditiion 397 Scientific Party

IODP Expedition 397 recovered a continuous record of precessionally-paced lithological cycles to the base of the recovered section (~9.55 Ma) at Site U1587.  On board ship, three intervals were selected for multi-disciplinary dissection of the cycles in time windows comprising three precessional cycles each ((early Pleistocene 2.284-2.345 Ma, late Pliocene 3.427-3.496 Ma, and late Miocene 5.638-5.5707 Ma).  These three intervals are grounded in continuous XRF scanning that allows for a reliable astrochronology based largely on precessional variability. Carbonate cyclicity follows northern hemisphere precession throughout high carbonate content associated with high northern hemisphere summer insolation.  The cycles cannot be explained solely by changes in carbonate production or preservation, as the clay-rich phases of the cycles are often expanded relative to the carbonate-rich phases.  Sea surface temperature (SST) recorded by alkenone biomarkers shows fluctuations in tandem with the carbonate cycles.  For the Pliocene and Pleistocene, higher carbonate correlates to warmer SST and interglacial conditions as inferred from stable isotope measurements.  The pattern flips in the Messinian test interval, with high carbonate associated with colder and more glacial climate.  Clay mineralogy shows cyclic fluctuations associated with changes in riverine and eolian inputs.  High illite (high dust?) corresponds to high carbonate content in the Miocene and Pleistocene test intervals, while the opposite is observed for the Pliocene.   An abrupt change in cycle spacing near the terminal Messinian likely records a tectonic event that perhaps influenced transport and deposition of the detrital components.

How to cite: Herbert, T., Abrantes, F., Brooks, H., Flores, J.-A., Hodell, D., McManus, J., Mitsunaga, B., Palone, C., Pang, X., Wu, J., Yu, J., and Zarikian, C. and the Expeditiion 397 Scientific Party: Precessional Climate Cyclicity on the Iberian margin: Miocene-recent, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19840, https://doi.org/10.5194/egusphere-egu24-19840, 2024.

EGU24-21881 | Orals | CL1.1.2

Combined high-and low-latitude forcing of orbital East Asian hydroclimate 

Hongbin Zhang, Michael L. Griffiths, Hai Cheng, Gaowen Dai, Jiaoyang Ruan, Yunping Sun, Ling Lu, Wei Guo, Junhua Huang, and Shucheng Xie

Speleothem oxygen isotope records from China have provided the most detailed insights into the past Asian summer monsoon variability of any paleoclimate archive (“proxy”) to date in the past 640 ka, showing the dominance of the orbital precession rhythm. However, fundamental disagreement exists on what the oxygen isotope records represent in terms of the hydroclimate changes, in particular on the orbital scale. Based on the oxygen isotope records and other hydroclimate proxies from 15 speleothems at Haozhu Cave in central-eastern China, as well as the model simulations for the periods of Marine Isotope Stages 6 and 11, we show the orbital-scale ‘dipole’ hydroclimate in monsoonal eastern China, with wetter (drier) conditions in the central but drier (wet) conditions in the north when summer insolation was low (high) and East Asian summer monsoon was weak (strong). Of significance is the finding that the hydroclimate contrast in East China was greatly enhanced during glacial-interglacial transitions, with the wettest hydroclimate in the north but widespread drought in the central, when the heat content of both the global ocean and the Indo-Pacific Warm Pool upper ocean reached the maximum. We propose that the orbital-scale westerly jet transition affects the East Asian summer rainband position and thus the orbital hydroclimate pattern in eastern China, and the low latitude tropical Indo-Pacific ocean moisture transport amplifies the hydroclimate contrast during glacial-interglacial transitions

How to cite: Zhang, H., Griffiths, M. L., Cheng, H., Dai, G., Ruan, J., Sun, Y., Lu, L., Guo, W., Huang, J., and Xie, S.: Combined high-and low-latitude forcing of orbital East Asian hydroclimate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21881, https://doi.org/10.5194/egusphere-egu24-21881, 2024.

Since the middle Miocene climatic transition, Earth’s climate has steadily cooled. The Late Miocene Global Cooling (LMGC) and the Northern Hemisphere Glaciation (NHG) were key cooling events. I analyzed changes of radiolarian microfossil assemblages to try to reconstruct the paleoceanographic changes during the last 10 million years at Ocean Drilling Program (ODP) Site 1208 to better understand the climate-cooling mechanism. I reconstructed sea surface temperatures (SSTs) based on extant radiolarian species from 0 to 10 million years ago to verify the suitability of radiolarian-based SSTs. A comparison with previously published alkenone-based SSTs at Site 1208 indicated that radiolarian-based SSTs for the Miocene based on only extant species are satisfactory. However, large discrepancies were observed between radiolarian-based and alkenone-based SSTs during the LMGC and NHG. I attributed these discrepancies to a sustained influence of subsurface water (~50 to 100 m) on assemblages of radiolarians during extreme cooling events. Relative abundances of other radiolarian groups indicated that during the LMGC there was a reorganization of regional paleoceanography that probably weakened the Pacific Meridional Overturning Circulation, increased meridional temperature gradient, and caused a southward migration of the subtropical front.  It is probable that North Pacific Intermediate Water expanded southeastward during the NHG.

How to cite: Matsuzaki, K.: Evolution of the Central Northwest Pacific paleoceanography over the past 10 million years focusing on the Late Miocene Global Cooling (ODP Site 1208), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21, https://doi.org/10.5194/egusphere-egu24-21, 2024.

EGU24-1093 | ECS | Posters on site | CL1.1.4 | Highlight

Midges’ marks – what chironomid head capsules tell us about Eemian and Early Vistulian palaeoenvironment – results from Bispingen , northern Germany 

Tomasz Polkowski, Agnieszka Mroczkowska, Stefan Lauterbach, Frank Neumann, Rik Tjallingii, Michał Słowiński, and Achim Brauer

Understanding the nature of past climatic changes is essential to assess human impact on current and future climate and environment. One of the means to achieve this goal is conducting past climate reconstructions based on subfossil Chironomidae remains. Using this method allows to estimate past summer temperatures and other palaeoecological parameters such as lake trophy and pH. Although Chironomidae analysis is very useful for reconstructing past climatic and ecological conditions, not many high resolution reconstructions have been conducted for periods prior to significant human impact, e.g. during the Eemian interglacial and Early Vistulian glacial. The present study is part of a larger project that applies a multi-proxy approach to the partially annually laminated sediments of the Eemian paleolake of Bispingen in northern Germany. The analysed sediment sequence consists of around 12 meters of diatomitic, calcitic-diatomitic and clastic-organic material and was sampled continuously at 2 cm resolution. The aim of this research is to reconstruct summer temperature changes throughout the Early Vistulian glacial and Eemian interglacial and draw conclusions with respect to the climatic gradient between northern and southern Europe. Chironomids’ head capsules analysis is supported by palaeoecological and palynological data, allowing to extract distinct palaeoecological phases on the basis of trophy and thermal conditions during the period considered.

 

This project is funded by the Polish National Science Centre (No. 2019/34/E/ST10/00275).

How to cite: Polkowski, T., Mroczkowska, A., Lauterbach, S., Neumann, F., Tjallingii, R., Słowiński, M., and Brauer, A.: Midges’ marks – what chironomid head capsules tell us about Eemian and Early Vistulian palaeoenvironment – results from Bispingen , northern Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1093, https://doi.org/10.5194/egusphere-egu24-1093, 2024.

EGU24-1163 | Posters on site | CL1.1.4

Effects of PETM in SouthWestern Anatolia: preliminarily results 

Füsun Danacı, Erhan Karakuş, Dilek Tokatlı, and Banu Türkmen Bozkurt

Paleocene - early Eocene units within the Isparta Bend where located in the west of the Taurus mountain belt consist of reddish-gray micritic limestones, silty mudstones, mudstones and sandstones. The sediments in question contain a late Tantian (NP9 according to Martini 1971 Nannoplankton zoning) aged nannofossil assemblage. In the samples taken from these sediments, many nannofossil species belonging to the Discoaster and Fasciculithus genera, which have oligotrophic hot environmental conditions, were identified. In the quantitative analyses made on the nanofossil contents of the samples taken from the study area, the abundance of species belonging to the Discoaster and Fasciculithus genera shows remarkable increases at upper levels. This situation can be interpreted as a change in oligotrophic-hot environmental conditions. This possibly be an indication of an increase in sea surface water temperature within the early PETM, possibly in the period just before the Paleocene-Eocene transition, which corresponds to the NP9-NP10 boundary in nannoplankton biozonation. The samples taken from the corresponding sediments on these samples contain nannofossil assemblages (Clausicoccus norrisii Bown & Newsam, Sphenolithus radians Deflandre, Ellipsolithus macellus (Bramlette & Sullivan)) giving an early Ypresian age (NP11). According to the results of the quantitative analysis, the diversity of nannofossil species and A significant decrease in the number of species has been observed, and Fasciculithus species are also very rare. This may be signs that the environmental conditions that existed in the late Thanetian changed greatly in the early Ypresian. Planktonic foraminifera, oxygen isotope and carbon isotope analyses in the samples continuing.

How to cite: Danacı, F., Karakuş, E., Tokatlı, D., and Türkmen Bozkurt, B.: Effects of PETM in SouthWestern Anatolia: preliminarily results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1163, https://doi.org/10.5194/egusphere-egu24-1163, 2024.

EGU24-2148 | ECS | Orals | CL1.1.4

The cessation of North Pacific Deep Water formation over Northern Hemisphere Glaciation. 

Friso de Graaf, David Thornalley, Natalie Burls, Gavin Foster, Rachel Brown, and Heather Ford

Global ocean circulation is controlled by deep water formation in the high latitude Atlantic and Southern Oceans. There is no deep water formation in the modern North Pacific due to a strong salinity gradient (or halocline) which makes the deep Pacific relatively homogenous. There is evidence to suggest that this halocline was weaker in the Late Pliocene (3.3 – 2.6 Ma) which allowed for active deep water formation. Coupled stable isotope and trace element records from benthic foraminifera at the Northwest Pacific ODP Sites 1208 (3346 m depth) and 1209 (2387 m depth) indicate deep water formation in the North Pacific during the Late Pliocene. Heavier oxygen isotopes at the shallower site 1209 require that the two sites were bathed in deep waters formed in different locations. Trace metal analysis (Mg/Ca) shows that there was a marginally colder, and thus fresher, water mass at the shallower site 1209 which is partially consistent with modelling results showing a fresher North Pacific Deep Water reaching intermediate depths in the Late Pliocene, while the deeper site was bathed in southern sourced waters. The benthic isotope values at the two sites converged during the glacials of the Early Pleistocene after the intensification of Northern Hemisphere Glaciation (iNHG, c. 2.7 Ma). This convergence was coincident with a global drop in sea levels suggesting that sea level changes, potentially by constricting water mass transport through the Indonesian Gateway, may have modulated the strength of North Pacific Deep Water formation in the Pliocene. This would mean that the complete cessation of North Pacific Deep Water does not occur until considerably after the iNHG.

How to cite: de Graaf, F., Thornalley, D., Burls, N., Foster, G., Brown, R., and Ford, H.: The cessation of North Pacific Deep Water formation over Northern Hemisphere Glaciation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2148, https://doi.org/10.5194/egusphere-egu24-2148, 2024.

The larger-scale oceanic gyre circulation regulates temperature, salinity and nutrient flow throughout the ocean, profoundly influencing the biological environment and climate. Here, we investigate the response of the Pacific gyre circulation during the warm climate of the early Eocene in eight models from the Deep-Time model intercomparsion project (DeepMIP). Our DeepMIP results suggest a northward expansion of the North Pacific subtropical gyre by up to 10 degrees latitude in the Eocene, maintaining a similar strength to the present day. This simulated poleward expansion of the North Pacific gyre circulation is corroborated by proxy evidence, including poleward shifts in low sedimentation rate and high clay concentration during the Eocene. In the southern Pacific, the super subtropical gyre is much stronger during the Eocene due to the southward position of Australia that leads to a wide-open Indonesian gateway. The poleward shifted boundary between the subtropical and subpolar gyre in North Pacific occurs as a result of the northward shifted westerly winds maxima, as also corroborated by an analysis of the Sverdrup transport. The Sverdrup transports describes the upper circulation during the Eocene further poleward than modern day mainly due to their continental differences. The upper circulation corresponds to Sverdrup transport up to ~53°N for the North Pacific, slightly further north than modern day of 50°N, and up to ~55°S for the South Pacific that is much further south than in the modern ocean and continents (~45°S).

How to cite: Zhang, Y. and M. de Boer, A.: Poleward expansion of North Pacific gyres circulation during the warm early Eocene inferred from inter-model comparisons, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2206, https://doi.org/10.5194/egusphere-egu24-2206, 2024.

EGU24-2429 | Posters on site | CL1.1.4 | Highlight

Patterns and drivers of Holocene moisture variability in mid-latitude eastern North America 

J. Sakari Salonen, Frederik Schenk, John W. Williams, Bryan Shuman, Ana L. Lindroth Dauner, and Miska Luoto

Proxy data for North American hydroclimate (e.g., pollen and other microfossils, sedimentological data, and stable isotopes) indicate major variations in moisture balance including persistent multimillennial droughts during the Holocene. When synthesised with paleoclimate model simulations, the proxies also allow the testing of hypotheses about the drivers and feedbacks involved in the past moisture variations. Recently, advances in (A) the availability of high-resolution proxy records, (B) the numerical methods used to extract the hydroclimate signal from the proxies, and (C) the transient Earth system model simulations of the Holocene, have opened exciting new avenues in unraveling the spatiotemporal progress, magnitudes, and causes of Holocene North American droughts.

Here, we apply new machine-learning based (boosted regression tree) pollen–climate calibrations to reconstruct annual water balance and July temperature from 66 fossil pollen sequences from the eastern North American mid-latitudes. Based on these data, we prepare synthesis paleoclimate reconstructions for three regions, spanning from the prairie–forest ecotone to the eastern seaboard, designated as Midwest (MW), Great Lakes (GL), and Northeast (NE). The proxy reconstructions are complemented by state-of-the-art model simulations, including the EC-Earth and MPI-ESM transient runs for 8–0 ka and CESM1 equilibrium runs for 12, 11, and 9 ka.

Our water balance reconstructions confirm the major regional offset in drought timing suggested by earlier proxy data, with NE reaching peak drought by 11 ka but with a progressively later timing seen westward in GL (~10 ka) and MW (~7 ka). This spatiotemporal pattern is also reproduced in the model simulations. In the early Holocene simulations, the dipole of wet conditions in MW vs. dry in NE can be clearly linked to dynamical changes in atmospheric circulation, linked to anticyclonic blocking over the residual Laurentide Ice Sheet. This confluence between our water balance reconstructions and the new-generation model simulations gives strong support to the hypothesis that the broadscale drought progress can be explained by the combination of decreasing summer insolation and the waning of the Laurentide glacial anticyclone, which diverted the northward moisture advection from the mid-continent towards the eastern seaboard. Beyond these multimillennial patterns, our proxy reconstructions show coherent centennial events in moisture and temperature. Wavelet analyses of the reconstructions and the transient simulations reveal significant periodicities in both water balance and July temperature, most commonly in the 0.2–0.6 ka wavelength range in the reconstructions and at 0.1–0.2 ka in the simulations.

In the MPI-ESM and EC-Earth simulations, the mid-Holocene drought is driven by a combination of lower-than-preindustrial precipitation together with increased potential evapotranspiration due to warmer summer temperatures. The relative drought through most of the Holocene, seen in both the reconstructions and the simulations, suggests that the recent and modern climate is unusually wet while drier conditions seem to be the norm during the Holocene. Looking towards the future, it is hence plausible that reverting the natural neoglacial cooling of the recent millennia with anthropogenic global warming might cause a return of drier conditions due to a higher evaporative demand that is not compensated by higher precipitation.

How to cite: Salonen, J. S., Schenk, F., Williams, J. W., Shuman, B., Lindroth Dauner, A. L., and Luoto, M.: Patterns and drivers of Holocene moisture variability in mid-latitude eastern North America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2429, https://doi.org/10.5194/egusphere-egu24-2429, 2024.

EGU24-2571 | ECS | Orals | CL1.1.4

Iron fertilization-induced deoxygenation of Eastern Equatorial Pacific intermediate waters during the Paleocene-Eocene Thermal Maximum 

xiaodong jiang, weiqi Yao, Xiangyu zhao, Xiaoming sun, Andrew Roberts, and Appy Sluijs

Thousands of gigatons (~2500-4500 Gt) of carbon were released into the ocean and atmosphere system over several thousand years during the Paleocene-Eocene Thermal Maximum (PETM, ca. 56 Ma), a transient period of global warming, is considered an important analog for future greenhouse conditions. It was accompanied by a significant carbon cycle perturbation, intensified weathering and hydrological cycling, and ocean deoxygenation. Although ocean deoxygenation across the PETM is reported widely, its mechanism in the open ocean remains uncertain. We here present magnetic and geochemical analyses of sediments from the Eastern Equatorial Pacific (EEP) Ocean. We find that iron fertilization during the PETM by eolian dust and volcanic eruptions fueled EEP ocean productivity. This process led to increased organic matter degradation and oxygen consumption in intermediate waters, leading to deoxygenation. Our findings suggest that iron fertilization could be an important driver of open ocean oxygen loss, as a side effect of global warming. Our observation is important in the emerging discussion of how global warming will reduce dissolved oxygen in the open ocean and, in turn, affect the marine fishery industry and future food security.

How to cite: jiang, X., Yao, W., zhao, X., sun, X., Roberts, A., and Sluijs, A.: Iron fertilization-induced deoxygenation of Eastern Equatorial Pacific intermediate waters during the Paleocene-Eocene Thermal Maximum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2571, https://doi.org/10.5194/egusphere-egu24-2571, 2024.

EGU24-2886 | Posters on site | CL1.1.4

Expanding PlioVAR to PlioMioVAR: Updates and Future Directions 

Heather L. Ford, Sindia Sosdian, Erin McClymont, Sevi Modestou, Sze Ling Ho, Natalie Burls, Aisling Dolan, and Tamara Fletcher and the PlioMioVAR

The Pliocene (~2.6-5.3 million years ago), and increasingly the Miocene (~23-5.3 million years ago), are used by the climate community as pseudo-analogs of future climate change. Relative to modern, the Plio-Miocene was globally warmer with reduced continental ice volume and reconstructed atmospheric carbon dioxide concentrations similar to or higher than present-day. The Past Global Changes (PAGES) PlioMioVAR working group expands on the previous PAGES PlioVAR working group aims to create a synthesis of marine and terrestrial data to characterise spatial and temporal reconstructions of Plio-Miocene climate. Major outputs from PlioVAR include a synthesis and evaluation of multi-proxy sea surface temperatures (SSTs) during the KM5c interglacial (~3.2 million years ago) and Pliocene-Pleistocene intensification of Northern Hemisphere Glaciation. In coordination with the Pliocene model intercomparison project Phase 3 (PlioMIP3), our Pliocene efforts are to 1) continuously update the existing mid-Pliocene database, 2) expanding our data synthesis to the early Pliocene (~4.5 and ~4.9 million years ago) and 3) synthesise terrestrial records. In coordination with the Miocene Model Intercomparison Project (MioMIP), our Miocene efforts are to 1) synthesise surface and deep temperatures and 2) identify Miocene time slices for data-model comparison. From workshop discussions, we’ve identified future research directions including 1) refining site-specific chronologies to ensure robust comparison of temperature records at short (i.e. glacial-interglacial) and longer time scales, 2) constraining seawater chemistry changes, 3) comparing multi-proxies with sufficient temporal and spatial coverage, and 4) reconstructing high-latitude regions (temperature and ice margin records) to improve our ability to to assess meridional temperature gradients, polar amplification, and ice sheet volume and stability. Focusing our efforts on these research directions could be community themes in the next incarnation of IODP. These databases and data-model comparisons are critical for navigating future climate change. This presentation outlines our current state of synthesis, assessment and analysis, and we welcome discussions on new data sets and approaches.

How to cite: Ford, H. L., Sosdian, S., McClymont, E., Modestou, S., Ho, S. L., Burls, N., Dolan, A., and Fletcher, T. and the PlioMioVAR: Expanding PlioVAR to PlioMioVAR: Updates and Future Directions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2886, https://doi.org/10.5194/egusphere-egu24-2886, 2024.

EGU24-3742 | Orals | CL1.1.4

Did monsoon govern the Asian rainy season in the early Eocene? An ensemble paleoclimate simulation perspective. 

Abhik Santra, Fabio A. Capitanio, Dietmar Dommenget, Bhupendranath Goswami, Alex Farnsworth, David K. Hutchinson, Julie M. Arblaster, Daniel J. Lunt, and Sebastian Steinig

The Asian summer monsoon (ASM) is a seasonal response of the coupled land-ocean-atmospheric system, which influences more than 60% of the world’s population. Although progress has been made in understanding the ASM variability and its prediction, the timing and governing factors for the ASM initiation are still debatable as recent proxy evidence and modeling studies suggested the initiation of a wet-dry monsoonal climate from the Cretaceous period (145 million years ago, Ma) to the early Miocene or late Oligocene epoch, ∼25-22 Ma. Capitalizing on an ensemble of paleoclimate simulations for the early Eocene (56-48 Ma), we show that the Asian wet season was considerably weaker and shorter than present in the absence of an elevated heat source like the Tibetan Plateau in the early Eocene. The deficient upper tropospheric meridional temperature gradient couldn’t drive the seasonal northward migration of the precipitation band over South Asia. Additionally, the weaker cross-equatorial moisture flow was mechanically blocked by the Gangdese mountain along the southern edge of Asia, leading to significantly dry conditions in South Asia. The enhanced atmospheric greenhouse gases were inadequate to strengthen the seasonal circulation and precipitation variability to the present level. We argue that an altered wet and dry seasonality over South Asia was not necessarily qualified as the Eocene ‘monsoon’.

How to cite: Santra, A., Capitanio, F. A., Dommenget, D., Goswami, B., Farnsworth, A., Hutchinson, D. K., Arblaster, J. M., Lunt, D. J., and Steinig, S.: Did monsoon govern the Asian rainy season in the early Eocene? An ensemble paleoclimate simulation perspective., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3742, https://doi.org/10.5194/egusphere-egu24-3742, 2024.

EGU24-3844 | Orals | CL1.1.4

Decomposition of Monsoon Dynamics: Reconciling Data and Model Comparison for Geological Time Periods 

Yong Sun, Haibin Wu, Lin Ding, and Gilles Ramstein

Understanding past climate informs our future scenarios. Proxy data and climate models are vital for studying past climate change, but discrepancies often arise between these approaches. This study introduces an innovative approach that reconciles proxy data with models by decomposing the physical processes driving monsoon precipitation changes. Focusing on East Asian Summer Monsoon (EASM) precipitation across significant periods in the PMIP, our analysis highlights: 1) the dominance of dynamic effects over thermodynamic effects during the mid-Holocene, 2) contrasting impacts of thermodynamic and dynamical processes during the Last Glacial Maximum, and 3) distinct regional controls of thermodynamic and dynamical processes in the mid-Piacenzian warm period, reflecting diverse water vapor sources. The study concludes that decomposing the physical processes of precipitation aids in reconciling records and simulations. It asserts that simulations consistently yield a decomposed process that spatially aligns with the records. The mismatch between records and simulations primarily arises from simulation biases in the relative contributions of the decomposed physical processes to precipitation changes, suggesting a need for improvement in simulations.

How to cite: Sun, Y., Wu, H., Ding, L., and Ramstein, G.: Decomposition of Monsoon Dynamics: Reconciling Data and Model Comparison for Geological Time Periods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3844, https://doi.org/10.5194/egusphere-egu24-3844, 2024.

EGU24-3889 | ECS | Posters on site | CL1.1.4

Light and temperature limitation of poleward coral reef expansion during past warm climates 

Anne Kruijt, Thomas Brachert, Jack Middelburg, and Appy Sluijs

The latitudinal range of shallow-water tropical corals is controlled by temperature, and presently limited to waters warmer than 16-18 °C yearround. However, even during Cenozoic climates with such temperatures in polar regions, coral reefs are not found beyond >50° latitude. Here, we test the hypothesis that daily available solar radiation limited poleward expansion of coral reefs during warm climates, using a new box model of shallow marine coral calcification. Our results show that calcification rates start to decline beyond 40° and more quickly beyond 50°, suggesting that winter light intensity and day length prohibits further poleward expansion. This implies that fossil coral reef distribution is not a robust proxy for water temperatures and that poleward expansion of reefs is not an expected carbon cycle feedback of climate warming.

How to cite: Kruijt, A., Brachert, T., Middelburg, J., and Sluijs, A.: Light and temperature limitation of poleward coral reef expansion during past warm climates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3889, https://doi.org/10.5194/egusphere-egu24-3889, 2024.

EGU24-4746 | Orals | CL1.1.4 | Highlight

An ice free Arctic during the Last Interglacial: CMIP6-PMIP4 progress on Arctic sea ice  

Louise Sime, Rachel Diamond, David Schroeder, Rahul Sivankutty, and Maria Vittoria Guarino

The Arctic was around 4-5C warmer in summer during peak Last Interglacial (LIG), compared to the preindustrial. However this summer warming was not accurately captured by CMIP models until 2020. Before then the lack of LIG Arctic warmth in CMIP models was most commonly postulated to be due to a lack of dynamic vegetation feedbacks. However in 2020 a UK CMIP6 model accurately captured the summer warming (Guarino et al., 2020). The warming in this model is due to a complete summertime loss of Arctic sea ice, rather than dynamic vegetation feedbacks. Whilst marine data, until 2023,  were not adequate for assessing the accuracy of this modelled LIG Arctic sea ice loss (Kagayama et al., 2021), this has now been rectified by valuable new marine core evidence from the Arctic (Vermassen et al., 2023). Here, we show firstly why we are confident that melt pond physics (albedo feedbacks) are sufficient to melt LIG sea ice, raise the Arctic temperature, and also why they are important for the accurate projection of Arctic sea ice loss during warm climate – including the future (Diamond et al., 2021; 2024). Secondly, we quantify the Arctic warmth, and discuss the nature of polar amplification in CMIP models, during the LIG (Sime et al., 2023). We find an Arctic-wide warming of 3.7±1.5 K at the LIG, alongside a climatological minimum sea ice area of 1.3 to 1.5 million km2, i.e that the peak LIG Arctic likely experienced a mixture of ice-free and near-ice-free summers.

How to cite: Sime, L., Diamond, R., Schroeder, D., Sivankutty, R., and Guarino, M. V.: An ice free Arctic during the Last Interglacial: CMIP6-PMIP4 progress on Arctic sea ice , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4746, https://doi.org/10.5194/egusphere-egu24-4746, 2024.

EGU24-5212 | Posters on site | CL1.1.4

Rates of Change in Past Warm Periods, Part 1 

Manfred Mudelsee

Since the publication of the IPCC's Fifth Assessment Report in 2013, there has been increasing evidence that the social and ecological impacts of global warming depend more on seasonal extremes (e.g. peak summer temperatures) than on trends in annual averages. This is particularly true in the tropics, where extremes have become the greatest threat to ecosystems. However, little is known about the current and future rates of change in means and extremes. Lack of high-resolution data from past warm climates (which serve as analogues) and lack of advanced data analysis methods explain this knowledge deficit.

The SEARCH project (Seasonal Extremes and Rates of Change in Past Warm Climates: Insights from Advanced Statistical Estimations on High-Resolution Coral Proxy Records) aims to advance our knowledge by means of (1) using a database of high-resolution coral proxy records and (2) applying advanced simulation techniques from statistical science. SEARCH uses a database of about 50 existing and new (bi-)monthly resolved coral proxy records during the (a) Anthropocene, (b) Medieval Climate Anomaly-Medieval Warm Period, (c) Holocene Thermal Maximum, (d) Last Interglacial and (e) Mid-Pliocene Warm Period.

In the first part of our presentation series, we explain the methodological foundations (Mudelsee 2014, 2023): proxy calibration, nonparametric kernel estimation of the first derivative of the climate proxy series and linear regression. The methods take into account typical peculiarities of paleoclimate time series: non-Gaussian distributions, autocorrelation, uneven spacing and uncertain timescales. We present some initial results. Based on the (preliminary) results of SEARCH, we also consider the lessons for navigating the climate future within the framework of the GreenSCENT project (Smart Citizen Education for a Green Future).

Acknowledgements:

This work has been funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), project number 468589022 (SEARCH), within the SPP 2299, project number 441832482; and by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101036480 (GreenSCENT).

References:

Mudelsee M (2014) Climate Time Series Analysis: Classical Statistical and Bootstrap Methods. Second Edition. Springer, Cham. xxxii + 454 pp [https://www.manfredmudelsee.com/book/index.htm]

Mudelsee M (2023) Unbiased proxy calibration. Mathematical Geosciences. (doi:10.1007/s11004-023-10122-5).

How to cite: Mudelsee, M.: Rates of Change in Past Warm Periods, Part 1, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5212, https://doi.org/10.5194/egusphere-egu24-5212, 2024.

EGU24-5510 | Posters on site | CL1.1.4

Scanning the Ocean’s sedimentary barcode: optimising digital archives towards a deeper understanding of Earth Climate 

Anna Joy Drury, Nina Rohlfs, Roy Wilkens, Beth Christensen, Mitchell Lyle, Heiko Pälike, and Thomas Westerhold

Scientific ocean drilling (SOD) has played an important role in revealing much about Earth’s climate history through 50+ years of international programmes such as the International Ocean Discovery Programme (IODP) and its predecessors. The sedimentary records retrieved from below the ocean floor captures the evolution of Earth’s oceans and climate system, documenting both rapid climate change and long-term trends spanning at least the last 145 million years to the emergence of our modern world. All this was accomplished with a relatively traditional set of ocean drilling tools and approaches. Now with technological advances and the advent of data science, SOD is in a unique position to make similarly fundamental advances at a time when decision-makers are grappling with the effects of unprecedented rapid climate change.

Given the present need to understand the processes and capture the consequences of our changing climate, we need to employ all possible tools to achieve this. Here we present what ocean drilling material is available through geological time, summarised in easily accessible databases utilising Code for Ocean Drilling Data (CODD; www.CODD-home.net; Wilkens et al., 2017). We also highlight approaches to optimise the use of legacy SOD material and data by targeting locations with  stratigraphic continuity (e.g., locations with composite splices) combined with advances in digital capabilities, such as CODD. This includes presenting an archive of CODD core image tracks for all sites with continuous sedimentary sections based on composite splices. Together, we aim to highlight how this information can be used to develop a multifaceted approach further utilising digital archives derived from scientific ocean drilling material to read the subsurface barcode of past climate change stored in our deep-sea sediments.

How to cite: Drury, A. J., Rohlfs, N., Wilkens, R., Christensen, B., Lyle, M., Pälike, H., and Westerhold, T.: Scanning the Ocean’s sedimentary barcode: optimising digital archives towards a deeper understanding of Earth Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5510, https://doi.org/10.5194/egusphere-egu24-5510, 2024.

EGU24-5580 | ECS | Posters on site | CL1.1.4

Revisiting the physical processes controlling the tropical atmospheric circulation changes during the Mid-Piacenzian Warm Period 

Ke Zhang, Yong Sun, and Xu Zhang and the Team of co-authors of this work

The Mid-Piacenzian Warm Period (MPWP; 3.0-3.3Ma), a warm geological period about three million years ago, has been deemed as a good past analog for understanding the current and future climate change. Based on 12 climate model outputs from Pliocene Model Intercomparison Project Phase 2 (PlioMIP2), we investigate tropical atmospheric circulation (TAC) changes under the warm MPWP and associated underlying mechanisms by diagnosing both atmospheric static stability and diabatic processes. Our findings underscore the advantage of analyzing atmospheric diabatic processes in elucidating seasonal variations of TAC compared to static stability assessments. Specifically, by diagnosing alterations in diabatic processes, we achieve a quantitative understanding and explanation the following TAC changes (incl. strength and edge) during the MPWP: the weakened (annual, DJF, JJA) Northern Hemisphere and (DJF) Southern Hemisphere Hadley circulation (HC), reduced (annual, DJF) Pacific Walker circulation (PWC) and enhanced (annual, JJA) Southern Hemisphere HC and (JJA) PWC, and westward shifted (annual, DJF, JJA) PWC. We further addressed that the increasing bulk subtropical static stability and/or decreasing vertical shear of subtropical zonal wind - two crucial control factors for changes in subtropical baroclinicity - may promote HC widening, and vice versa.  Consequently, our study of spatial diabatic heating and cooling, corresponding to upward and downward motions within the TAC, respectively, provides a new perspective for understanding the processes controlling seasonal TAC changes in response to surface warming.

How to cite: Zhang, K., Sun, Y., and Zhang, X. and the Team of co-authors of this work: Revisiting the physical processes controlling the tropical atmospheric circulation changes during the Mid-Piacenzian Warm Period, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5580, https://doi.org/10.5194/egusphere-egu24-5580, 2024.

EGU24-5639 | Posters on site | CL1.1.4 | Highlight

Surface Ocean Cooling in the Eocene North Atlantic Coincides With Declining Atmospheric CO2 

Gordon Inglis, Rehemat Bhatia, David Evans, Jiang Zhu, Wolfgang Muller, David Mattey, David Thornalley, Richard Stockey, and Bridget Wade

The Eocene (56–34 million years ago) is characterized by declining sea surface temperatures (SSTs) in the low latitudes (∼4°C) and high southern latitudes (∼8–11°C), in accord with decreasing CO2 estimates. However, in the mid-to-high northern latitudes there is no evidence for surface water cooling, suggesting thermal decoupling between northern and southern hemispheres and additional non-CO2 controls. To explore this further, we present a multi-proxy (Mg/Ca, δ18O, TEX86) SST record from Bass River in the western North Atlantic. Our compiled multi-proxy SST record confirms a net decline in SSTs (∼4°C) between the early Eocene Climatic Optimum (53.3–49.1 Ma) and mid-Eocene (∼44–41 Ma). However, from the mid-Eocene onwards, east-west North Atlantic temperature gradients exhibit different trends. This is attributed to inception of Northern Component Water during the early-middle Eocene transition and incursion of warmer waters into the eastern North Atlantic, but additional data sets are required to test this further. We also demonstrate that the onset of long-term Eocene cooling in the western North Atlantic (∼49–48 Ma) occurs synchronously in other ocean basins (e.g., N. Atlantic vs. SW Pacific) and across different latitudinal bands, implying that CO2 was likely responsible for the onset of long-term Eocene cooling.

How to cite: Inglis, G., Bhatia, R., Evans, D., Zhu, J., Muller, W., Mattey, D., Thornalley, D., Stockey, R., and Wade, B.: Surface Ocean Cooling in the Eocene North Atlantic Coincides With Declining Atmospheric CO2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5639, https://doi.org/10.5194/egusphere-egu24-5639, 2024.

EGU24-5765 | ECS | Posters on site | CL1.1.4

Early Eocene Climatic Optimum Pacific deep ocean temperatures from clumped isotope thermometry 

Johanna Marquardt, Ismini Lypiridou, Victoria E. Taylor, Philip F. Sexton, Thomas Westerhold, James C. Zachos, and A. Nele Meckler

Past greenhouse climates provide crucial insights into how the climate system operates under conditions with high atmospheric carbon dioxide concentrations and smaller or absent continental ice sheets, and thus inform projections of future climate. When studying past greenhouse climate states, deep ocean temperatures are often used to estimate global mean temperature (Westerhold et al., 2020), which is needed to determine climate sensitivity and assess the performance of climate models. Additionally, deep ocean temperatures provide insights into past ocean circulation patterns.

The Early Eocene Climatic Optimum (EECO; 53.3 to 49.1 Ma) was characterized by extreme global warmth and elevated atmospheric CO2 concentrations (Hollis et al., 2019a). Currently, our understanding of deep ocean temperatures during the EECO relies primarily on benthic foraminiferal stable oxygen isotopes and Mg/Ca records. These proxies, however, are influenced by factors other than temperature, making robust deep-time temperature reconstructions challenging. Carbonate clumped isotope thermometry, on the other hand, is largely independent of past seawater chemistry and can therefore provide essential new constraints.

Recent clumped isotope-based deep ocean temperature reconstructions from the Atlantic Ocean are substantially warmer during the peak EECO than previous estimates based on stable oxygen isotopes and Mg/Ca records (Meckler et al., 2022). However, it remains to be tested whether these warmer temperatures are a regional signal restricted to the Atlantic Ocean or found globally in the deep ocean. Here we present a record of deep ocean temperatures using clumped isotopes in benthic foraminifera from the Pacific Ocean (ODP Site 1209, ~2300 m paleo-water depth). Our new record spans the interval between 52 Ma to 50.3 Ma, covering the peak EECO and the major shift in benthic foraminiferal stable carbon isotopes around 51 Ma which is observed globally in the deep ocean. Warmer than expected Atlantic as well as Pacific deep ocean temperatures could indicate that EECO global mean temperature was warmer than previously assumed, which would have implications for existing estimates of climate sensitivity.

References

Hollis, C. J., Dunkley Jones, T., Anagnostou, E., Bijl, P. K., Cramwinckel, M. J., Cui, Y., ... & Lunt, D. J. (2019a). The DeepMIP contribution to PMIP4: Methodologies for selection, compilation and analysis of latest Paleocene and early Eocene climate proxy data, incorporating version 0.1 of the DeepMIP database. Geoscientific Model Development, 12(7), 3149-3206.

Meckler, A. N., Sexton, P. F., Piasecki, A. M., Leutert, T. J., Marquardt, J., Ziegler, M., ... & Bernasconi, S. M. (2022). Cenozoic evolution of deep ocean temperature from clumped isotope thermometry. Science377(6601), 86-90.

Westerhold, T., Marwan, N., Drury, A. J., Liebrand, D., Agnini, C., Anagnostou, E., ... & Zachos, J. C. (2020). An astronomically dated record of Earth’s climate and its predictability over the last 66 million years. Science369(6509), 1383-1387.

How to cite: Marquardt, J., Lypiridou, I., Taylor, V. E., Sexton, P. F., Westerhold, T., Zachos, J. C., and Meckler, A. N.: Early Eocene Climatic Optimum Pacific deep ocean temperatures from clumped isotope thermometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5765, https://doi.org/10.5194/egusphere-egu24-5765, 2024.

EGU24-5915 | ECS | Orals | CL1.1.4

Response of the Hydrological Cycle to Early Eocene Warmth: Insights from DeepMIP-Eocene 

Marlow Cramwinckel and the DeepMIP-Hydrology Team

Investigating how the early Eocene (∼56–48 million years ago) hydrological cycle operated under elevated atmospheric CO2 concentrations and globally higher temperatures can provide important insights into understanding of current climate change and projects of future climate. Here, we investigate the global and zonal-mean rainfall patterns during the early Eocene using an integrated data-model approach. We leverage insights from the DeepMIP-Eocene suite of model simulations in combination with a compilation of paleobotanical proxies of precipitation. In short, the mid- and high latitudes, as well as the tropical band, are characterized by a thermodynamically-dominated hydrological response to warming, and overall wetter conditions (“wet-gets-wetter”). A more complex picture is painted for the subtropics. Although these are overall characterized by negative precipitation-evaporation anomalies (“dry-gets-drier”) in the DeepMIP models, there is surprisingly large inter-model variability in mean annual precipitation. Intriguingly, we find that models with weaker meridional temperature gradients (e.g., CESM, GFDL) are characterized by a reduction in subtropical moisture divergence, leading to an increase in MAP. These model simulations agree more closely with our new proxy-derived precipitation reconstructions and other key climate metrics and imply that the early Eocene was characterized by reduced subtropical moisture divergence. If the meridional temperature gradient was even weaker than suggested by those DeepMIP models, circulation-induced changes may have outcompeted thermodynamic changes, leading to wetter subtropics, thus going against the “wet-gets-wetter, dry-gets-drier” paradigm. This highlights the importance of evaluating multiple climate metrics against sets of simulations and can provide food for thought for DeepMIP phase two.

How to cite: Cramwinckel, M. and the DeepMIP-Hydrology Team: Response of the Hydrological Cycle to Early Eocene Warmth: Insights from DeepMIP-Eocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5915, https://doi.org/10.5194/egusphere-egu24-5915, 2024.

EGU24-7500 | ECS | Posters on site | CL1.1.4

Micro XRF elemental mapping for paleoclimate reconstruction in the Indian Ocean -to find exact timings of climate change- 

Arisa Seki, Gerald Auer, and David De Vleeschouwer

Non-destructive, high-resolution measurement of sediment cores are useful to reveal sediment feature which reflect climatic or oceanographic changes. Such non-destructive measurement (e.g. XRF core scanner measurement) could be reveal sediment feature in finer scale than discrete sample measurement. Although elemental mapping is also useful to reveal 2-dimentional structure of half split core surface, elemental mapping of large materials such as archive half core sections were usually difficult.

In this study, we utilize recently released micro-XRF (M6 JETSTREAM provided by Bruker Corporation) which could measure archive half core directly and could make high-resolution element maps. The fine scale sediment feature which reflecting exact timings of drastic climate changes were revealed by micro-XRF using sediments obtained by following two Sites.

Using the Neogene sediments obtained from DSDP Site 266, located at the high-latitude of Indian ocean close to the Antarctica, the distinctive chemical markers of IRD were observed in specific sections of Site 266. IRD is primarily distinguished by its characteristic iron-rich signature, and the identified fragments measure between 4.2 and 6.4 millimeters in length along their longest axis. Traditionally, these individual particles could only be discerned through destructive analysis. The large-scale micro-XRF capabilities of the JETSTREAM now enable us to non-destructively quantify and fingerprint IRD. The drastic changes of primary producer from the calcareous plankton to the siliceous plankton was also suggested from elemental mapping results.

The sediments obtained from ODP Site 752, located on an isolated ridge in the Indian Ocean contained concretion at Paleogene age when hiatus or lower sedimentation rate was suggested by age model. We measured the concretion and the surrounding sediments together using specialized method of JETSTREAM, and revealed high-resolution elemental maps of concretion and surroundings sediments. The maps clearly shows that each element (Ca, Fe, Mn) is concentrated on different part on and around the concretion. The Ca concentration is higher at an interval above a concretion, which may suggest high calcareous productivity during the sedimentation period.

In this study, we used legacy cores (archive halves) stored at Kochi Core Center (KCC), as the member of ReCoRD program (ReC23-01). Our measurement clearly shows reanalysis of previously obtained core materials by new technics reveals new feature of sediments which is useful to reconstruct past climate changes.

How to cite: Seki, A., Auer, G., and De Vleeschouwer, D.: Micro XRF elemental mapping for paleoclimate reconstruction in the Indian Ocean -to find exact timings of climate change-, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7500, https://doi.org/10.5194/egusphere-egu24-7500, 2024.

Nearly 100 million people live in and depend on the Sahel for agriculture and natural resources. The region is sensitive to natural climate and environment variations caused by the seasonal movement of the tropical rainbelt. In the paleoclimate record, insolation plays a clear role on West African Monsoon strength, but responses to other forcings like temperature, greenhouse gases, ice volume, and land surface cover are unclear due to the lack of highly resolved, terrestrial records that span major global and regional shifts through time. Here we present leaf wax precipitation and vegetation records from five targeted study windows throughout the last 25 million years, derived from long-chain n-alkane hydrogen (δDwax) and carbon (δ13Cwax) isotopes, respectively, in a sediment core from ODP Site 959 in the Gulf of Guinea, where westerly winds and major river systems transport Western Sahel-sourced material. Analyses of trend and variability document a range of rainfall and vegetation responses to orbital forcings in different boundary conditions in the Oligocene, Miocene, Pliocene, and Pleistocene. We find that both the climate and environment was more variable in times of higher CO2 and global temperatures, suggesting an increase in ecosystem instability moving forward into the future. Because of the high resolution and temporal coverage of these new biomarker isotope records, we can examine relationships between precipitation and vegetation fluctuations, even prior to C4-expansion when there was a strong correlation despite minimal variation in δ13Cwax in a C3 world. Further, we find a drying trend throughout the record, demonstrating that vegetation on long timescales was decoupled from hydroclimate and was like driven by global CO2, advancing our understanding of climate and ecosystem relationships across the Cenozoic.

How to cite: Lupien, R., Uno, K., and de Menocal, P.: Orbital-scale climate and environmental responses of the Western Sahel to shifts in Cenozoic boundary conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7676, https://doi.org/10.5194/egusphere-egu24-7676, 2024.

EGU24-7727 | ECS | Orals | CL1.1.4

The oxygen and carbon isotope records of East Asian climate variations during the Eocene warm periods from Weihe Basin, central China 

Kexin Wang, Huayu Lu, Wenfeng Sun, Chenghong Liang, Hongyan Zhang, Yichao Wang, Hengzhi Lv, Jingjing Wang, Hanzhi Zhang, and Wen Lai

Eocene warmth has been used as one of the best analogues for future anthropogenic warming. How East Asian hydroclimate responds to the increased temperature during the Eocene is still elusive. Here, we present a combined element and isotopic geochemistry study of an Eocene lacustrine sequence covering the period 46-33 Ma from Weihe Basin, central China. Based on the formation process of lake carbonate and the paleosol CO2 barometer equation, a calculation model of lake carbonate carbon isotope (δ13Ccarb) that is suitable for open lake basins with low productivity is proposed. The sensitivity analysis of the Eocene lacustrine carbonate δ13Ccarb  show that the SRF is the main influencing factor of the carbon isotope fractionation. The reconstructed SRF of the Eocene is generally high, with an average value of ~215 g C/m2/yr, revealing a relatively warm and humid environment in the Weihe Basin. After ~41 Ma, the SRF gradually decreased, indicating that the climate in the Weihe Basin gradually became colder and drier. This trend is consistent with the global cooling, especially at ~36 Ma, ~33 Ma (the Eocene-Oligocene transition EOT) showing the most significant reduction. The reconstructed precipitation oxygen isotope (δ18Op) in the Eocene warmth is characterized by a positive value (~-6 ‰) in the northwest inland region, and relatively negative  values in the central region such as the Weihe Basin and Lanzhou Basin (~-10 ‰), and the Qinghai-Tibetan Plateau area (~-11 ‰). This kind of distribution is similar to modern precipitation δ18Op, indicating that a prototype of the East Asian summer monsoon circulation has probably formed in the Middle Eocene.

How to cite: Wang, K., Lu, H., Sun, W., Liang, C., Zhang, H., Wang, Y., Lv, H., Wang, J., Zhang, H., and Lai, W.: The oxygen and carbon isotope records of East Asian climate variations during the Eocene warm periods from Weihe Basin, central China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7727, https://doi.org/10.5194/egusphere-egu24-7727, 2024.

EGU24-7824 | Posters on site | CL1.1.4

Effect of cloud feedbacks to CO2 level rise on the summer Arctic climate within the Eocene Deep-Time Model Intercomparison Project 

Igor Niezgodzki, Gregor Knorr, Dan Lunt, and Gerrit Lohmann

Warmer-than-today and ice-free early Eocene Arctic region serves as a testbed for possible future climate changes in the northern polar region dominated by increasing CO2 forcing and associated shrinking sea ice. It is essential for our understanding of recent climate changes to investigate short wave (SW) cloud effects on the SAT rise in the Arctic region in the high CO2 worlds as well as to separate the temperature changes in cloud-free from all-sky conditions in the same region. Here we present the first results of the boreal summer SW cloud feedbacks to atmospheric CO2 level rise from 1x to 3x pre-industrial level of 280 ppm across the ensemble of models participating in the Eocene Deep Time Model Intercomparison Project (DeepMIP). We use a relatively novel approximate partial radiative perturbation (APRP) method to decompose the cloud feedback into the contribution from changes in cloud fraction, absorption and scattering (including cloud albedo feedback) as well as to separate the radiative effects of cloud changes from surface albedo changes. Our first results show discrepancies between the models regarding the effects of clouds on surface air temperature changes. Most of the models show that the net effect of clouds has a relatively modest positive effect (warming) on surface temperature changes however one of the models shows a cooling effect. These differences are due to different effects of cloud fraction and scattering across the ensemble. Furthermore, all models show warming due to surface albedo changes and moderate warming due to atmospheric non-cloud effects. However, surface albedo changes show big discrepancies in magnitudes between the models that result from particularly big differences in the overcast conditions.

How to cite: Niezgodzki, I., Knorr, G., Lunt, D., and Lohmann, G.: Effect of cloud feedbacks to CO2 level rise on the summer Arctic climate within the Eocene Deep-Time Model Intercomparison Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7824, https://doi.org/10.5194/egusphere-egu24-7824, 2024.

EGU24-8156 | ECS | Orals | CL1.1.4

The sensitivity of the PETM carbon cycle perturbation to orbital configurations 

Nina M. Papadomanolaki and David De Vleeschouwer

It is generally postulated that climatic change during the Paleocene – Eocene Thermal Maximum (PETM) was paced and/or caused by astronomical forcing, particularly eccentricity-modulated precession. Possible causal links include intermediate water warming and subsequent methane hydrate destabilization, increased climate sensitivity due to a warmer background state, and changes in hydrology and weathering. Current astrochronology places the PETM near a 405-kyr eccentricity maximum (Zeebe and Lourens, 2019), likely following a prolonged 2.25-Myr eccentricity minimum (Lourens et al., 2005). Similar orbital configuration sequences have been proposed for the Devonian Upper Kellwasser event (De Vleeschouwer et al., 2017) and the Cretaceous Oceanic Anoxic Event 2 (Batenburg et al., 2016). To understand how eccentricity could have made the Late Paleocene Earth System sensitive to a carbon-cycle perturbation with the amplitude of the PETM, we investigate both the equilibrium and transient climate response to changes in insolation. Specifically, our experimental set-up is to identify how rapid climate change events may unfold differently under high eccentricity (PETM) and low eccentricity (modern) regimes. We present results from equilibrium climate state simulations and transient climate responses to PETM emission scenarios, using the cGENIE Earth system model under a comprehensive set of eccentricity/precession configurations. Based on the outcomes of these simulations, we describe the differences in PETM expression in terms of climate and weathering regimes, depending on the astronomical configuration.

How to cite: Papadomanolaki, N. M. and De Vleeschouwer, D.: The sensitivity of the PETM carbon cycle perturbation to orbital configurations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8156, https://doi.org/10.5194/egusphere-egu24-8156, 2024.

EGU24-9094 | ECS | Posters on site | CL1.1.4

Late Paleocene-Early Eocene Climate Warming and Its Influence on Organic Matter Enrichment: Insights from the Kongdian Formation, Bohai Bay Basin, China 

Bixiao Xin, Fang Hao, Weidong Sun, Jinqiang Tian, Qilu Xu, and Guanlin Li

The late Paleocene to early Eocene was an interval of globally warm climate, during which organic-rich shales were developed in multiple basins. However, the impact of this climate warming on the mechanisms of organic matter enrichment remains unclear, primarily due to a scarcity of precise chronological data and continuous stratigraphic records from terrestrial basins. This study presents a continuous 400 m lacustrine core record from the GD-X borehole spanning the late Paleocene in the Bohai Bay Basin, East China. To reconstruct the palaeoenvironmental conditions and elucidate the mechanisms of organic matter enrichment of Paleocene shales, a series of analyses including total organic carbon (TOC), Rock-Eval pyrolysis, X-ray diffraction (XRD), major and trace elements testing, carbon and oxygen isotopes testing, and Gas Chromatography-Mass Spectrometry (GC-MS) were performed. The results indicate a high abundance of thermally mature Type I and II kerogen in the shales, with most samples exhibiting good to excellent generative potential. The mineralogical compositions are primarily comprised of quartz, feldspar, and dolomite, supplemented by calcite, clay minerals, and analcime. Vertical shifts in paleoenvironmental indicators suggest a climatic transition from semi-humid to arid conditions during the late Paleocene sedimentary period, characterized by reduced input of terrigenous detritus and increased water salinity. These findings indicate that rapid global warming from the late Paleocene to the early Eocene significantly altered precipitation patterns, leading to intensified lake evaporation, diminished surface runoff, and decreased inflow of terrigenous debris into lakes. Consequently, the organic matter enrichment model transitioned from a high productivity-dominated regime to one primarily driven by preservation conditions. Investigating the interplay between environment and biological evolution elucidates the enrichment mechanism of terrestrial organic matter against a backdrop of global climate warming. This research not only provides a scientific basis for predicting the distribution of continental organic-rich shale, but also offers geological insights into the carbon cycle under extreme climatic conditions in Earth's history.

How to cite: Xin, B., Hao, F., Sun, W., Tian, J., Xu, Q., and Li, G.: Late Paleocene-Early Eocene Climate Warming and Its Influence on Organic Matter Enrichment: Insights from the Kongdian Formation, Bohai Bay Basin, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9094, https://doi.org/10.5194/egusphere-egu24-9094, 2024.

EGU24-9148 | ECS | Posters on site | CL1.1.4

Pliocene-Pleistocene orbital cycle transition of summer sea surface temperature in the mid-latitude North Atlantic 

Xiaolei Pang, Antje Voelker, and Xuan Ding

The Pliocene-Pleistocene transition marks a significant period in Earth’s climate history. During this period, the climate shifted from the relatively stable and warm unipolar cool-house climate to the bipolar glaciated climate states of the ice-house associated with the gradual development of the Northern Hemisphere Glaciation (NHG) . The onset of the NHG (oNHG) is traced back to approximately 3.6 million years ago (Ma). This was followed by an intensification of the NHG (iNHG) around 2.7 Ma, coinciding with a substantial reorganization of oceanic and atmospheric circulation in the North Atlantic. Despite these shifts, reconstructed alkenone-based sea surface temperature (SST) records from the mid- to high-latitude North Atlantic indicate persistent obliquity-dominated cycles, with a noticeable absence of the precession cycle.

 In this study, we present new high resolution Globigerinoides ruber (white) Mg/Ca-based summer SST records from the early Late Pliocene spanning from 3650 – 3370 thousand years ago (ka) at the IODP Site U1313 (41°N, 33°W, 3412m) in the mid-latitude North Atlantic. Contrary to the previous alkenone-based SST records, our Mg/Ca-based SST records reveal a dominant precession cycle. When compared with early Pleistocene G. ruber Mg/Ca-based SST records, we observed a notable transition in the dominant cycle from precession to obliquity, accompanied by a doubling increase in amplitude. These results indicate a progressively amplified effect on the obliquity cycle, correlated with the progressive growth of the Northern Hemisphere ice sheets.

How to cite: Pang, X., Voelker, A., and Ding, X.: Pliocene-Pleistocene orbital cycle transition of summer sea surface temperature in the mid-latitude North Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9148, https://doi.org/10.5194/egusphere-egu24-9148, 2024.

EGU24-10082 | Orals | CL1.1.4

Soil carbonate Δ47 paleotemperatures across the Paleocene-Eocene boundary: the Esplugafreda terrestrial record, Spain 

Gábor Újvári, Sándor Kele, László Rinyu, Aitor Payros, Victoriano Pujalte, Birger Schmitz, and Stefano M. Bernasconi

Massive additions of 13C-depleted carbon to the atmosphere-ocean system at 55.9 Myr ago led to global warming of 5–8 °C, profound floral/faunal turnovers and alteration of the global hydrological cycle at the Paleocene-Eocene boundary. Climate and environmental changes over the late Paleocene and Paleocene-Eocene Thermal Maximum (PETM) are well-preserved in continental deposits, formed in the subtropical zone (paleolatitude ~35 °N), in the Tremp-Graus Basin, northern Spain. One of the key exposures is the Esplugafreda section, which is made up of ~250 m of red mudstones with abundant paleosols and contains numerous multi-episodic channel-like bodies of calcareous conglomerates and calcarenites. The paleosols contain abundant centimeter-sized soil nodules and gypsum indicating a semi-arid to arid paleoenvironment. The Paleocene-Eocene (P-E) boundary is located near the top of the continental section, based on a 6‰ negative carbon isotope excursion (CIE). The CIE spans more than 15–20 m of yellow cumulate paleosols formed during the Paleocene-Eocene Thermal Maximum (PETM). The post-PETM interval in the Esplugafreda section comprises 20 m of red paleosols rich in gypsum and characterized by normal soil nodule δ13C values.

Here, we report the first carbonate clumped isotope thermometry data of selected soil carbonate bearing paleosol layers of the Esplugafreda sequence to quantify the magnitude of warming recorded in the sediments of this terrestrial subtropical site across the Paleocene-Eocene boundary. Soil nodules originated from red mudstone paleosols making up the upper part of the upper Paleocene Esplugafreda Formation and PETM yellow soils collected at two nearby sites. The nodules were sampled with a hand driller for Δ47 measurements, which were done using a Kiel IV carbonate device coupled to a Thermo Scientific 253 Plus IRMS at the Institute for Nuclear Research, Debrecen, Hungary. Stable carbon, oxygen isotope and clumped isotope compositions were calculated as the average of 8–16 replicate analyses of 100–150 μg of carbonate. The carbon and oxygen isotope ratios are reported in δ notation in per mil (‰) relative to the Vienna Pee Dee Belemnite (VPDB), while the temperature-dependent mass 47 anomaly on the I-CDES90°C scale. Temperatures were calculated using the Kele et al. (2015) calibration modified by Bernasconi et al. (2018) and the Anderson et al. (2021) calibrations.

Soil carbonates of the Esplugafreda formation yield δ13Ccarb values between –8.55 and –5.85 ‰, while the PETM yellow soil carbonates are significantly more negative (–13.84 to –10.12 ‰), in good agreement with previous measurements. A much smaller, ~1.2 ‰ difference can be observed in the oxygen isotope compositions between these carbonates (δ18Ocarb: –5.46 to –4.13 versus –6.35 to –4.47 ‰). The Δ47-based paleotemperatures (T47carb) indicate mean soil carbonate formation of 33.8±9.5 °C during the late Paleocene, which are close to modern summer temperatures of subtropical regions. By contrast, a much higher mean temperature was recorded by soil carbonates of the PETM yellow soils (39±8.5 °C) with extreme (>40 °C) temperatures occurring 4 times more frequently than over the late Paleocene.

This study was supported by the NKFIH through the OTKA K-137767 project.

How to cite: Újvári, G., Kele, S., Rinyu, L., Payros, A., Pujalte, V., Schmitz, B., and Bernasconi, S. M.: Soil carbonate Δ47 paleotemperatures across the Paleocene-Eocene boundary: the Esplugafreda terrestrial record, Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10082, https://doi.org/10.5194/egusphere-egu24-10082, 2024.

EGU24-10701 | ECS | Posters on site | CL1.1.4

Impact of the Early Eocene Climatic Optimum (EECO; ~53-49 Ma) on planktic foraminiferal assemblage (Pacific Ocean, sites 1209-1210).  

Giulia Filippi, Ruby Barrett, Daniela N. Schmidt, Roberta D'Onofrio, Thomas Westerhold, Valentina Brombin, and Valeria Luciani

Past warm events offer windows into the biotic response to extreme warmth. The early Eocene interval records the highest global average temperature and CO2 levels of the Cenozoic. Several transient global warming events occur within the Early Eocene Climatic Optimum (EECO, 53-49 Ma), offering an opportunity to investigate the impact of both long term and transient warm climatic conditions on planktic foraminifera. We analyse the planktic foraminiferal record across the EECO obtained from tropical Pacific ODP sites 1209-1210 (Shatsky Rise). These sites have an excellent age model and stable isotope ratios enabling linkage of the biotic data with the climate and carbon cycle spanning the EECO.

We combine indicators of carbonate production and preservation [fragmentation index (FI) as a dissolution proxy, weight percent coarse fraction (CF) as foraminiferal production and preservation index, and Foraminiferal Mass Accumulation Rate (FMAR) as foraminiferal production proxy] with changes in planktic foraminiferal assemblages and test-size.

At the EECO onset, the abundance of the genus Morozovella (53.28 Ma) and Chiloguembelina (52.85 Ma) decreased at Shatsky Rise sites, confirming previous Atlantic Ocean data and thus pointing towards global decline of these genera. We hypothesise that a reduction in foraminiferal mass accumulation and assemblage test-size would follow the drop in Morozovellids abundance, given their dominance and large size in early Eocene tropical assemblages. In contrast, we record a slight increase in test-size within assemblages and a relatively stable FMAR. These changes may be controlled by growing dominance of the genus Acarinina indicating an ability of this species to benefit from the environmental conditions. In addition, we observe a relatively stable FMAR at decreasing CF which may be linked to either increased carbonate dissolution or enhanced calcareous nannofossil productivity (or a combination of both) reducing foraminiferal relative contribution to the sediment.

Even though the pronounced warming during the EECO strongly altered the planktic foraminiferal assemblage composition resulting in the decrease in abundance of some genera, species replacement within communities highlights the resilience of pelagic carbonate production.

How to cite: Filippi, G., Barrett, R., Schmidt, D. N., D'Onofrio, R., Westerhold, T., Brombin, V., and Luciani, V.: Impact of the Early Eocene Climatic Optimum (EECO; ~53-49 Ma) on planktic foraminiferal assemblage (Pacific Ocean, sites 1209-1210). , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10701, https://doi.org/10.5194/egusphere-egu24-10701, 2024.

The Early Eocene Climatic Optimum (EECO) was the warmest sustained episode of global warming during the Cenozoic, accompanied by major alterations in land-based and marine biota. Initially identified through stable oxygen isotope minimum values between ~52—50 Ma (herein labelled ‘peak-EECO phase’) and later extended to a broader timeframe (53—49 Ma) anchored on stable carbon isotope excursions, the EECO provides a crucial window for exploring the long-term, macroevolutionary consequences of warm climates on marine primary producers. The fossil remains of coccolithophores and other calcareous nannoplankton have been studied previously in the mid- and high latitudes, where the EECO is characterized by a transition from assemblages dominated by the genus Toweius (Prinsiaceae) to the enduring presence of the genus Reticulofenestra (Noelaerhabdaceae), as is still the case for their descendants in modern assemblages (Gephyrocapsa spp. and Emiliania huxleyi).

Using a newly collected nannofossil record from the equatorial Atlantic (ODP Site 1258), we detail changes in low-latitude calcareous nannofossil assemblages throughout the various stages of the EECO and the subsequent early to middle Eocene cooling transition (EMET). The decline in Toweius spp. occurred in two steps: first, at the start of the peak-EECO phase (~52 Ma), with abundance plummeting to about one-third of previous levels, followed by its final and permanent decline and the first continuous occurrence of Reticulofenestra spp. at the end of the peak-EECO phase (~50 Ma). The EECO is also marked by a broad acme of Discoaster spp., as previously reported at several sites. Here we also report on distinct abundance increases in Campylosphaera, Umbilicosphaera and Calcidiscus. These genera declined in abundance by the conclusion of the EECO (~49 Ma) in conjunction with the rapid and sustained expansion of Reticulofenestra, marking the EMET.

Multivariate statistical analysis of nannofossil datasets at Site 1258 and sites from higher latitudes highlights the occurrence and prevalence of specialist taxa exclusively in the tropics, revealing a distinct tropical signature atop the previously identified latitudinal expansion of (sub)tropical taxa during the EECO. Compositional contrasts between the tropical and higher-latitude sites diminished significantly after the EECO, coinciding with the decline of taxa with inferred high thermal optima in the tropics. Our combined results suggest the highest biogeographical differentiation of tropical nannoplankton assemblages from the subtropics (e.g., ODP Sites 1263 and 1210) during the EECO, contrary to some expectations related to a much flatter meridional thermal gradient. The restructuring of the nannoplankton communities after the EECO, however, points to increased connectivity and dispersal between the two regions. It is important to explore the regional driving forcings (e.g., ocean circulation, temperature, nutrient availability, and biotic interactions) on local phytoplankton community structures in the tropics in order to understand broadscale changes in biogeographical and macroevolutionary patterns.

How to cite: Asanbe, J. and Henderiks, J.: Major shifts in low-latitude calcareous nannofossil assemblages across the Early Eocene Climatic Optimum (~53—49 Ma), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10705, https://doi.org/10.5194/egusphere-egu24-10705, 2024.

EGU24-12390 | ECS | Posters on site | CL1.1.4

Inter-basin comparison of deep ocean temperature change at the Eocene-Oligocene Transition 

Victoria E. Taylor, Alison M. Piasecki, Steven M. Bohaty, Paul A. Wilson, Helen K. Coxall, and A. Nele Meckler

The abrupt onset of large-scale Antarctic glaciation approximately 34 million years ago, at the Eocene-Oligocene Transition (EOT), was the pivot point in Cenozoic climate history between greenhouse and icehouse climate states. Our understanding of this event relies heavily on benthic foraminiferal oxygen isotope (δ18Ob) records but the paucity of independent temperature reconstructions prevents an assessment of the contributions of temperature and ice volume to the rapid δ18Ob increase which is interpreted to mark the onset of large-scale Antarctic glaciation. Here we present records of deep-sea temperature change for the EOT using clumped isotope thermometry which permits explicit temperature reconstructions independent of seawater chemistry and ice volume. Recently published benthic foraminiferal clumped isotope records from the eastern equatorial Pacific (Taylor et al. 2023) and a low-resolution long-term record from the northwest Atlantic Ocean (Meckler et al. 2022) hint at a possible thermal decoupling of these two major deep ocean basins at the EOT. To investigate this further, we present new temperature records from the Newfoundland margin in the northwest North Atlantic Ocean (IODP Exp. 342 Sites U1406 and U1411). In addition, we supplement the previously published records from the eastern equatorial Pacific (Taylor et al. 2023) with additional data (ODP Leg 199 Site 1218 and IODP Exp. 320 Sites U1334 and U1333) to better constrain the timing of the onset of deep ocean cooling relative to the onset of large-scale Antarctic glaciation. These new detailed records from both ocean basins enable an assessment of potential divergences in the evolution of deep ocean temperatures in the North Atlantic and Pacific at the EOT, and thus changes in ocean circulation prior to and/or in response to the onset of Antarctic glaciation.   

 

Meckler, A. N. et al., (2022). Cenozoic evolution of deep ocean temperature from clumped isotope thermometry. Science377 (6601), 86-90.

Taylor, V. E., Wilson, P. A., Bohaty, S. M., Meckler, A. N., (2023). Transient deep ocean cooling in the eastern equatorial Pacific Ocean at the Eocene-Oligocene Transition. Paleoceanography and Paleoclimatology, 38, e2023PA004650. https://doi. org/10.1029/2023PA004650

How to cite: Taylor, V. E., Piasecki, A. M., Bohaty, S. M., Wilson, P. A., Coxall, H. K., and Meckler, A. N.: Inter-basin comparison of deep ocean temperature change at the Eocene-Oligocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12390, https://doi.org/10.5194/egusphere-egu24-12390, 2024.

EGU24-12593 | Posters on site | CL1.1.4

Temperature reconstructions of euphotic oceans via coccolith clumped isotopes 

Luz Maria Mejia, Victoria Emma Taylor, Anna Nele Meckler, Heather Stoll, Stefano Bernasconi, Alvaro Fernández, Hongrui Zhang, José Guitián, Henrik Sadatzki, Iván Hernández-Almeida, and Heiko Pälike

Clumped isotope thermometry applied to carbonate fossils is a promising technique to derive independent and accurate reconstructions of absolute ocean temperatures, a key parameter in understanding past Earth Climate Sensitivity. Other more commonly used temperature proxies have several disadvantages, including requiring assumptions of seawater chemistry compositions (e.g. foraminifera Mg/Ca and δ18O), or being based on empirical correlations without a complete understanding of its controlling mechanisms (e.g. TEX86 and Uk'37). Conversely, clumped isotope thermometry is based on thermodynamics, and is independent from seawater chemistry. Here we present clumped isotopes (Δ47) in coccolith separations from globally distributed Holocene core tops, a monospecific Coccolithus pelagicus sediment trap in the Iceland Sea, downcore sediments from the North Atlantic during the last 16 Ma, and downcore sediments from tropical (Equatorial Pacific) and high latitudes (South Tasman Rise) spanning the Cenozoic. 

Calcification temperatures of the sediment trap agree with satellite derived temperatures, further supporting a lack of or small vital effects in coccolith clumped isotopes. Temperatures derived from Δ47 of tropical Holocene coccoliths are colder than modern Sea Surface Temperatures (SSTs). This suggests that coccolithophores may inhabit deeper than surface waters in these areas, which if proven to be true, would have implications for how other proxies, such as Uk'37, are calibrated to SSTs. At higher latitudes, calcification temperatures from Holocene coccolith separations are more similar to SSTs, and we suggest they are indicators of mixed layer depth temperatures in these regions.

Pure coccoliths from the North Atlantic during the last 16 Ma show Δ47-derived temperatures that are 10 °C colder than those derived with alkenones from the same samples. This suggests a modest, rather than an extreme polar amplification, which agrees better with climate models. Scanning Electron Microscopy (SEM) and trace elements show no evidence of significant recrystalization and therefore cannot explain such large differences in reconstructed temperatures with both proxies.

Preliminary low resolution Δ47 calcification temperatures of pure coccolith separations from the Equatorial Pacific throughout the Cenozoic show similar trends to the overall climate pattern expected from foraminiferal δ18O, but with colder absolute values. For example, published core top Δ47 coccoliths indicate warmer temperatures compared to our 2 My sample in core U1338, and may suggest potential early recrystalization effects, different sources or strength of upwelling in the past oceans, latitudinal movement of upwelling, or depth of production. Conversely, high latitude temperatures (ODP 1170) from our youngest coccolith separation (2 My) agrees better with modern SSTs and alkenone temperatures. The general expected climatic trend is also observed in our high latitude record, although the magnitude of cooling through time is less marked compared to that shown in the Equatorial Pacific. Trace element and SEM imaging could give insights on whether there is evidence of some recrystalization, or other interfering material in the analyzed pure coccolith fractions, despite the careful separation process that limited the presence of non-coccolith carbonate. Our results show that coccolith Δ47 has the promising potential to derive reconstructions of temperatures of euphotic oceans over the Cenozoic.

How to cite: Mejia, L. M., Taylor, V. E., Meckler, A. N., Stoll, H., Bernasconi, S., Fernández, A., Zhang, H., Guitián, J., Sadatzki, H., Hernández-Almeida, I., and Pälike, H.: Temperature reconstructions of euphotic oceans via coccolith clumped isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12593, https://doi.org/10.5194/egusphere-egu24-12593, 2024.

EGU24-13009 | Orals | CL1.1.4

Eocene CO2 on orbital to million year timescales 

James Rae, Sarah Greene, Philip Sexton, Markus Adloff, James Barnet, Andrea Burke, Gavin Foster, William Gray, Michael Henehan, Jo Holo, Hana Jurikova, Sandra Kirtland-Turner, Johanna Marquardt, Nele Meckler, Andy Ridgwell, Victoria Taylor, Thomas Westerhold, Ross Whiteford, and James Zachos

The early Eocene features distinctive coupling between biogeochemical cycles and climate, raising fundamental questions about Earth system functioning during major climate transitions and on orbital timescales. For instance, the transition to peak Eocene warmth is ushered in by a major shift in redox conditions and deep ocean circulation, while orbitally-paced hyperthermal events are associated with substantial carbon injections of uncertain origin.  CO2 change is thought to play a key role in these events, yet despite recent progress, resolution is still lacking for most shorter time intervals.  Here we present new, high-resolution boron isotope data from both benthic and planktic foraminifera that shed new light on Eocene carbon cycling. Using new approaches for conversion of boron isotope data to pH and CO2, we improve estimates of absolute CO2 concentrations and the change in CO2 over key events.  Our data demonstrate a pervasive link between CO2 and climate in the Eocene hothouse over a range of timescales and provide novel constraints on carbon sources and climate sensitivity.

How to cite: Rae, J., Greene, S., Sexton, P., Adloff, M., Barnet, J., Burke, A., Foster, G., Gray, W., Henehan, M., Holo, J., Jurikova, H., Kirtland-Turner, S., Marquardt, J., Meckler, N., Ridgwell, A., Taylor, V., Westerhold, T., Whiteford, R., and Zachos, J.: Eocene CO2 on orbital to million year timescales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13009, https://doi.org/10.5194/egusphere-egu24-13009, 2024.

EGU24-13057 | Orals | CL1.1.4 | Highlight

Continuous records of δ11B-CO2 covering the Plio-Pleistocene boundary and the Mid Pleistocene Transition show orbital carbon-climate coupling. 

Thomas Chalk, Rachel Brown, Sophie Nuber, Mathis Hain, Jimin Yu, James Rae, and Gavin Foster

The Pliocene-Pleistocene transition and Middle Pleistocene Transition (3.4–2.5 million years ago and ~1.2-0.6 million years ago respectively) represent major shifts in the Earth’s climate, with both being associated with global cooling, sustained and transient changes in ocean circulation, and the development and stabilization of large ice sheets in the northern hemi- sphere. These ice sheets waxed and waned over the last 2.5 million years and are the key mode of climate variability in this ice house world. Knowledge of the relationship of climate and CO2 on this timescale has to date been hampered by low resolution and imprecise records of CO2 once beyond the reach of the ice core records. Here we show orbitally resolved and multisite records of CO2 from boron isotopes across both transitions, and progress towards a highly resolved multi-basin stack of records. We find a persistent relationship between CO2 and climate state, which implicates CO2 decrease as a major contributor to both climate transitions, but also highlights non-linear responses in temperature and sea level as well as significant leads and lags on orbital timescales. Our findings confirm that changes in atmospheric CO2 play a key role in long-term Plio-Pleistocene climate and implicate the repeating transfer of carbon from the atmosphere to the ocean as a key mechanism in major climate transitions of the last 3 million years.

 

How to cite: Chalk, T., Brown, R., Nuber, S., Hain, M., Yu, J., Rae, J., and Foster, G.: Continuous records of δ11B-CO2 covering the Plio-Pleistocene boundary and the Mid Pleistocene Transition show orbital carbon-climate coupling., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13057, https://doi.org/10.5194/egusphere-egu24-13057, 2024.

EGU24-13307 | ECS | Orals | CL1.1.4

Quantifying the State Dependency of Climate Sensitivity Across Cenozoic Warm Intervals 

Mary Grace Albright, Nils Weitzel, Gordon N. Inglis, Sebastian Steinig, Martin Renoult, Tammo Reichgelt, Tamara Fletcher, Julia Tindall, and Ran Feng

Equilibrium climate sensitivity (ECS) quantifies the amount of warming resulting from a doubling of the atmospheric CO2 forcing. Despite recent advancements in climate simulation capabilities and global observations, there remains large uncertainty on the degree of future warming. To help alleviate this uncertainty, past climates provide a valuable insight into how the Earth will respond to elevated atmospheric CO2. However, there is evidence to suggest that ECS is dependent on background climate warmth, which may interfere with the direct utilization of paleo-ECS to understand present-day ECS. Thus, it is important that a range of different climate states are considered to better understand the factors modulating the relationship between CO2 and temperature. In this study, we focus on three time intervals: the mid-Pliocene Warm Period (3.3 – 3.0 Ma), the mid-Miocene (16.75 – 14.5 Ma), and the early Eocene (~50 Ma), in order to sample ECS from Cenozoic coolhouse to hothouse climates. Here, we combine the Bayesian framework of constraining the ECS and its uncertainty with several published methods to estimate the global mean surface temperature (GMST) from sparse proxy records. This framework utilizes an emergent constraint between the simulated GMST changes and climate sensitivities across the model ensemble. For each time interval, we employ a combination of parametric and non-parametric functions, coupled with a probabilistic approach to derive a refined estimate. Preliminary results for the Pliocene indicate a GMST reconstruction of approximately 19.3°C, which is higher than previous estimates that were derived using only marine records. Using this estimate, we calculate an ECS that is also higher than previously published values, especially due to the inclusion of high-latitude terrestrial temperature records into our estimates. Intriguingly, using the consistent methodology, our calculated ECS for the early Eocene is lower than that of the mid-Pliocene. This result does not support an amplified ECS in hothouse climate, and points to a potentially important role of ice albedo feedback in amplifying the ECS in coolhouse climate. Ongoing work will apply the same methodology to the mid-Miocene and further investigate the source for the estimated ECS state dependency between these climate intervals.

How to cite: Albright, M. G., Weitzel, N., Inglis, G. N., Steinig, S., Renoult, M., Reichgelt, T., Fletcher, T., Tindall, J., and Feng, R.: Quantifying the State Dependency of Climate Sensitivity Across Cenozoic Warm Intervals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13307, https://doi.org/10.5194/egusphere-egu24-13307, 2024.

EGU24-14193 | Orals | CL1.1.4

Instability in upper-ocean structure and its implications for Deep Water formation during marine isotope stage 11 

Benoit Thibodeau, John Doherty, Montserrat Alonso-García, Shraddha Band, Alba Gonazalez-Lanchas, Christelle Not, and Haojia Ren

The marine isotope stage (MIS) 11 interglacial, which occurred approximately 424 to 374 thousand years ago, is a period of significant climatological interest due to its unusual duration and intensity of warm conditions under relatively subdued orbital forcing, a phenomenon often referred to as the “MIS 11 paradox”. This study focuses on understanding the factors behind this paradox and its implications for the formation of Deep Water in the North Atlantic.

We examined the upper-ocean structure in the Iceland Basin during MIS 11, a key region for modern deep-water formation. By analyzing geochemical measurements, including stable nitrogen isotopic ratios and carbon and oxygen isotopic ratios of planktic foraminifera, we reconstructed the upper-ocean structure and its potential role in driving the Atlantic Meridional Overturning Circulation (AMOC) during MIS 11.

The findings reveal that MIS 11 experienced an initial AMOC intensification, followed by a secondary strengthening prior to the onset of the climatic optimum. The secondary intensification was attributed to the gradual reduction of northern-hemisphere sea ice, allowing for a northward extension of surface-ocean currents. This resulted in the maintenance of an anomalously deep summer mixed layer in the polar Nordic Seas during MIS 11 compared to the Holocene. The deep-water formation in the Nordic Seas played a crucial role in extending the enhanced warming of the northern hemisphere and delaying the onset of the next glacial interval.

While the contemporary Atlantic Ocean primarily relies on deep-water formation in the eastern subpolar region, the study suggests that the relative importance of deep-water formation in polar regions may increase under extreme scenarios of anthropogenic warming. By studying MIS 11 as a potential analog for Earth's contemporary climate system, we provide valuable insights into the long-term fate of the AMOC and its implications for global climate.

This study also highlights the significance of understanding the convective behavior of the subpolar Atlantic for a comprehensive understanding of the AMOC during MIS 11. We present new geochemical measurements and reconstructions of upper-ocean structure in the Iceland Basin, shedding light on the potential link between summer mixed-layer depth and deep-water formation.

How to cite: Thibodeau, B., Doherty, J., Alonso-García, M., Band, S., Gonazalez-Lanchas, A., Not, C., and Ren, H.: Instability in upper-ocean structure and its implications for Deep Water formation during marine isotope stage 11, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14193, https://doi.org/10.5194/egusphere-egu24-14193, 2024.

EGU24-15368 | ECS | Posters on site | CL1.1.4 | Highlight

Pattern of early-stage of global warming emerged in satellite measurements 

Hu Yang, Gerrit Lohmann, Christian Stepanek, Qiang Wang, Rui Xin Huang, Xiaoxu Shi, Jiping Liu, Dake Chen, Xulong Wang, Yi Zhong, Qinghua Yang, and Juliane Muller

The satellite-observed sea surface temperature (SST) provides an unprecedented opportunity to evaluate the ongoing global warming and has recently reached a milestone of 40-year temporal coverage. One of the major spatial features captured by satellites is strong subtropical (weak subpolar) ocean warming. In contrast, studies of past climate changes suggest that the greatest ocean warming should occur, however, at higher latitudes. Here, by comparing satellite observations with reconstructed mid-Pliocene SST and simulated SST evolution driven by abrupt increase in CO2, we find that the currently observed warming pattern is an expression of an early and temporary stage of planetary warming under the forcing of rapidly increasing greenhouse gas. The enhanced subtropical ocean warming, sharing similar spatial structure with the subtropical ocean gyres, is likely attributed to the background subtropical convergence of surface water. In a long-term perspective, the warming of the oceans at higher latitudes is expected to overtake the temporally strong subtropical ocean warming. This delayed but amplified subpolar ocean warming has the potential to reshape the ocean-atmosphere circulation and threaten the stability of marine-terminating ice sheets.

How to cite: Yang, H., Lohmann, G., Stepanek, C., Wang, Q., Huang, R. X., Shi, X., Liu, J., Chen, D., Wang, X., Zhong, Y., Yang, Q., and Muller, J.: Pattern of early-stage of global warming emerged in satellite measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15368, https://doi.org/10.5194/egusphere-egu24-15368, 2024.

EGU24-16204 | ECS | Orals | CL1.1.4

A framework for assessing paleoclimate analogy 

Arthur Oldeman, Lauren Burton, Julia Tindall, Aisling Dolan, Daniel Hill, Alan Haywood, Michiel Baatsen, Anna von der Heydt, and Henk Dijkstra

Our climate is changing due to anthropogenic influences, and we are heading into climate conditions that are largely unknown to modern humans. Considering the great threat that anthropogenic climate change is, there is a need to accurately project how our climate will respond to warmer conditions in the future. Reconstructions of the Earth’s past show that many climatic features that we observe today have – to some extent – been present in the geological archive. So, we can study paleoclimate to advance our understanding of dynamics and processes in warm climates, as well as to explore responses and sensitivities of the Earth’s climate to forcing changes. Given the similarities between the past and the projected future, researchers have been trying to establish analogy between paleoclimate and future climate. This could include analogy in terms of elevated or rising CO2 concentrations, elevated surface temperatures, and specific processes such as ice sheet melt or an AMOC weakening. However, often paleoclimate – future climate analogies are difficult to interpret, since conditions for analogy are not properly defined, or implications of the analogy are unclear or overstated.

In this work, we propose a practical methodological framework to assess paleoclimate analogy, for general use in the climate research community. The framework consists of five main steps: (1) stating the purpose (e.g. which processes are considered) and relevance of the analogy, (2) assessing feasibility of finding an analogy, (3) a detailed description of the followed methodology, (4) assessment of confidence in the analogue, and (5) clear communication regarding the potential as well as limitations of the analogy. As part of the framework, we identify three main types of analogy: (a) analogy in terms of forcing (e.g. CO2 concentration), (b) in terms of response (e.g. surface temperatures) and (c) in terms of processes (e.g. tipping behavior). We will briefly treat example applications of the framework to highlight its potential, for different types of analogues on different time scales.

How to cite: Oldeman, A., Burton, L., Tindall, J., Dolan, A., Hill, D., Haywood, A., Baatsen, M., von der Heydt, A., and Dijkstra, H.: A framework for assessing paleoclimate analogy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16204, https://doi.org/10.5194/egusphere-egu24-16204, 2024.

EGU24-16298 | ECS | Posters on site | CL1.1.4

Mg/Ca surface-water paleotemperatures during the Early Eocene Climatic Optimum from the Pacific Ocean: impact on planktic foraminiferal assemblages 

Silvia Sigismondi, Giulia Filippi, David Evans, Roberta D'Onofrio, Massimo Tiepolo, Enrico Cannaò, Thomas Westerhold, Bridget Wade, and Valeria Luciani

The Early Eocene Climatic Optimum (EECO; ~53–49 million years ago, Ma), that represents the Cenozoic peak of temperature and atmospheric CO2 concentrations, significantly affected planktic foraminiferal (PF) assemblages. The main change documented is the permanent decline in abundance and diversity of the symbiont-bearing mixed-layer dweller genus Morozovella, coupled with an increase in abundance and diversity of the genus Acarinina at the beginning of the EECO in the tropical Pacific Ocean (Sites 1209-1210), similar to the previously documented record from the Atlantic Ocean. A second significant variation is the change in coiling direction of morozovellids that moved from dominantly dextral to sinistral close to the K/X event (52.85 Ma), in contrast to Acarinina which does not show any preferential coiling direction throughout. In addition, the deep-dweller genus Chiloguembelina virtually disappeared at the K/X event. Even though a link between these PF changes and EECO climatic change appears evident, the driving causes are still unknown. With the aim of evaluating whether a possible temperature increase may have impacted the observed PF changes, we performed Mg/Ca analysis to derive paleotemperatures from diverse species of Morozovella and Acarinina, and on the thermocline-dweller Subbotina from tropical Pacific sites 1209-1210 using laser ablation (LA)-ICP-MS. Our B/Ca and Sr/Ca results in all the examined samples/species, along with the observed low PF test-fragmentation allow us to exclude a significant influence of contamination or diagenesis on the reconstructed temperatures. As uncertainties in the interpretation of Mg/Ca data remain when working with extinct species, the temperatures were evaluated with both a ‘Trilobatus sacculifer-like’ calibration (no pH correction) and with a ‘Globigerinoides ruber-like’ calibration (pH-correction).In both cases a mixed-layer mean temperature increase of at least 1°C is recorded, with much warmer absolute temperature resulting from the former calibration approach.We hypothesize that the temperature rise may have impacted the morozovellid symbiotic relationship that, in turn, can represent a reason for their decline in abundance, given the many examples of the evolutionary benefits of symbiosis in modern oligotrophic mixed-layer habitats. Although there may have been several contributing factors resulting in photosymbiont bleaching at this time, increased temperature is considered a primary factor of bleaching in modern tropical larger benthic foraminifera. Our assumption appears supported by the lower δ13C values exhibited by the surviving sinistral morozovellids (Luciani et al. 2021 GloPlaCha) while the new dominant genus, Acarinina that does not record lower δ13C values displays greater ecological adaptability. Our evidence appears in line with the hypothesis of Davis et al. (2022 PlosOne) that acarininids changed their symbiotic associations in response to the extreme warming of the PETM (~56 Ma) (but not the subsequent smaller hyperthermals), resulting in long term evolutionary success.

How to cite: Sigismondi, S., Filippi, G., Evans, D., D'Onofrio, R., Tiepolo, M., Cannaò, E., Westerhold, T., Wade, B., and Luciani, V.: Mg/Ca surface-water paleotemperatures during the Early Eocene Climatic Optimum from the Pacific Ocean: impact on planktic foraminiferal assemblages, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16298, https://doi.org/10.5194/egusphere-egu24-16298, 2024.

EGU24-16960 | ECS | Posters on site | CL1.1.4

Developing the coupled climate model ACCESS-ESM1.5 for the early Eocene 

David Hutchinson, Katrin Meissner, and Laurie Menviel

We are currently developing the Australian community climate model ACCESS-ESM1.5 for deep time paleoclimate simulations. We are currently targeting the early Eocene (~55 Ma) and the Miocene climate optimum (~15 Ma); two warm intervals with high CO2 concentrations and strong polar amplification. The major challenge in adapting this model is to implement extensive changes to surface boundary conditions, including topography, vegetation, river runoff and ice sheets. The model has never previously been run outside of modern boundary conditions. We have developed new prototype simulations for each time period, and will present preliminary results for the Eocene and Miocene using ACCESS-ESM1.5. These simulations will be developed in parallel with simulations using the GFDL CM2.1 coupled climate model, which has been established as an efficient tool for reaching equilibrium paleoclimate scenarios. 

How to cite: Hutchinson, D., Meissner, K., and Menviel, L.: Developing the coupled climate model ACCESS-ESM1.5 for the early Eocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16960, https://doi.org/10.5194/egusphere-egu24-16960, 2024.

The earliest Eocene (~ 56 to 52 Ma) is generally considered to be a reasonable geologic analog for modern climatic change, albeit with the important caveat that current carbon dioxide emissions are increasing at unprecedentedly high rates. In addition, the series of carbon cycle perturbations (also known as hyperthermals) that characterize the early Eocene, present an ideal opportunity to explore how ancient marine ecosystems responded to different magnitudes of warming in the past. However, before such paleoecological analyses can be conducted, reliable age models with robust biostratigraphic frameworks are required.

Currently, high-resolution orbital age models for the early Eocene are predominantly based on low-or mid-latitude sites (e.g., Walvis Ridge, Shatsky Rise and Demerara Rise). In comparison, high-latitude early Eocene age models are usually only based on shipboard biostratigraphic and/or low-resolution chemostratigraphic data. Furthermore, correlation of the calcareous nannofossil biostratigraphic events at Walvis Ridge and Demerara Rise to southern high-latitude site International Ocean Discovery Program (IODP) Site U1553 (Campbell Plateau, South Pacific Ocean), reveals ~1 Myr discrepancies for many of the commonly-used biohorizons (Niederbockstruck et al., in review). However, it is uncertain whether this apparent latitudinal diachroneity is unique to Site U1553, or whether it is a typical feature of all early Eocene high-latitude sites.

This presentation introduces a new Deutsche Forschungsgemeinschaft (DFG)-funded project that aims to further explore this apparent latitudinal diachroneity. The project will generate new high-resolution bulk stable isotope records and biostratigraphic frameworks for several high-latitude, legacy Ocean Drilling Program (ODP) and IODP sites. These data will then be correlated to existing low- and mid-latitude orbital age models to determine whether early Eocene nannofossil biozones are truly latitudinally diachronous.

How to cite: Jones, H.: Exploring apparent calcareous nannofossil biozone diachroneity at the southern high-latitudes during the early Eocene , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17069, https://doi.org/10.5194/egusphere-egu24-17069, 2024.

EGU24-17733 | ECS | Orals | CL1.1.4

Reconstructing Early to Mid-Cretaceous Climate Dynamics: A Continuous Marine pCO2 Record  

Olivia A. Graham, Caitlyn R. Witkowski, and B. David A. Naafs

The Cretaceous period (145-66 Ma) experienced dramatic changes in climate, biogeochemistry, and biotic innovation. Climate varied between a super greenhouse and coolhouse world (O'Brien et al., 2017), multiple ocean anoxic events (OAEs) drove major changes in ocean chemistry and biodiversity (Jenkyns, 2010), and angiosperms became the most dominant land plant group on Earth (Lidgard and Crane, 1988, Condamine et al., 2020). However, we are unable to assess the role of pCO2 in driving these climatic, biogeochemical, and biotic changes because there is no continuous, marine based, pCO2 record for this period, mainly due to the lack of established marine-based proxies able to span this time interval.

To address this issue, we measured the carbon isotopic composition of the general phytoplankton biomarker, phytane, in ~50 sediment samples from Deep Sea Drilling Project Site 398 that span the early and middle Cretaceous (Hauterivian to Cenomanian). Additionally, we reconstruct sea surface temperature (SST) using the TEX86 paleothermometer in the same sediments, providing a long continuous temperature record from a single site and thus bridging multiple important ‘gaps’ in the current record (O'Brien et al., 2017). Together, our findings provide the first continuous marine pCO2 and temperature record of the early to mid-Cretaceous, spanning the Hauterivian to Cenomanian.

Our results indicate SSTs around 30-35 °C for most of the Hauterivian to Albian. There is a transient warming during OAE 1a (~120 Myr) followed by a more gradual warming into the Cenomanian. During the Cenomanian SSTs reach maxima of ~40 °C at this mid-latitude site, consistent with other SST records from this period that indicate extreme warmth. pCO2 values during the Hauterivian to Albian vary between 1000 and 2000 ppmv, consistent with the elevated SSTs at this time. However, unexpectedly, we do not observe a rise in pCO2 during the Cenomanian when SSTs reach their maxima. These results suggest that pCO2 was not the main driver of the Cenomanian super hothouse.

 

References:

CONDAMINE, F. L., SILVESTRO, D., KOPPELHUS, E. B. & ANTONELLI, A. 2020. The rise of angiosperms pushed conifers to decline during global cooling. Proceedings of the National Academy of Sciences, 117, 28867-28875.

JENKYNS, H. C. 2010. Geochemistry of oceanic anoxic events. Geochemistry, Geophysics, Geosystems, 11.

LIDGARD, S. & CRANE, P. R. 1988. Quantitative analyses of the early angiosperm radiation. Nature, 331, 344-346.

O'BRIEN, C. L., ROBINSON, S. A., PANCOST, R. D., SINNINGHE DAMSTÉ, J. S., SCHOUTEN, S., LUNT, D. J., ALSENZ, H., BORNEMANN, A., BOTTINI, C., BRASSELL, S. C., FARNSWORTH, A., FORSTER, A., HUBER, B. T., INGLIS, G. N., JENKYNS, H. C., LINNERT, C., LITTLER, K., MARKWICK, P., MCANENA, A., MUTTERLOSE, J., NAAFS, B. D. A., PÜTTMANN, W., SLUIJS, A., VAN HELMOND, N. A. G. M., VELLEKOOP, J., WAGNER, T. & WROBEL, N. E. 2017. Cretaceous sea-surface temperature evolution: Constraints from TEX86 and planktonic foraminiferal oxygen isotopes. Earth-Science Reviews, 172, 224-247.

How to cite: Graham, O. A., Witkowski, C. R., and Naafs, B. D. A.: Reconstructing Early to Mid-Cretaceous Climate Dynamics: A Continuous Marine pCO2 Record , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17733, https://doi.org/10.5194/egusphere-egu24-17733, 2024.

EGU24-19216 | Orals | CL1.1.4 | Highlight

Nile Basin vegetation and Mediterranean water column ecology during Sapropel formation  

Lars Wörmer, Antonio Fernández-Guerra, Raphaël Morard, Marina Zure, Mikkel Winther Pedersen, Christiane Hassenrück, Michal Kucera, Eske Willerslev, and Kai-Uwe Hinrichs

For millions of years, the Mediterranean Sea has regularly experienced episodes of disrupted thermohaline circulation and increased primary productivity that resulted in a largely anoxic water column. These anoxic episodes are typically related to a more humid climate over Northern Africa and are captured in the sedimentary record as organic-rich sapropel layers. Given the excellent preservation of organic molecules in them, sapropels are extraordinary archives for the marine and continental ecosystems associated with the unique conditions that prevailed during their formation. We applied metagenomic environmental DNA (eDNA) analysis to recent sapropels (< 175 kyr) from the Eastern Mediterranean, including Sapropel S5 deposited during the Last Interglacial, and benchmarked obtained results with high resolution geochemical and molecular biomarker records. Ancient eDNA analysis enables reconstructions across all domains of life, including those components of the ecosystem that do not leave fossils or are not recorded in the fossil record. In the case of Mediterranean sapropels, this approach reveals information on both terrestrial and marine ecosystems. We provide detailed insight into vegetation changes in the Nile River Basin during the different, climatically diverse episodes of sapropel deposition. On the marine side, we reveal how water column ecology and major elemental cycles adapted to this massive ecosystem overhaul.

How to cite: Wörmer, L., Fernández-Guerra, A., Morard, R., Zure, M., Pedersen, M. W., Hassenrück, C., Kucera, M., Willerslev, E., and Hinrichs, K.-U.: Nile Basin vegetation and Mediterranean water column ecology during Sapropel formation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19216, https://doi.org/10.5194/egusphere-egu24-19216, 2024.

EGU24-19919 | Orals | CL1.1.4

The temperature of the deep ocean is a robust proxy for global mean surface temperature during the Cenozoic 

David Evans, Julia Brugger, Gordon Inglis, and Paul Valdes

Reconstructions of global mean surface temperature (GMST) are one of the key contributions that palaeoclimate science can make to societally-relevant questions, for example, by providing the information required to derive equilibrium climate sensitivity from the geologic record and as a means of testing climate model performance under warmer-than-present conditions. One relatively simple method of doing so is to parameterize GMST as a function of the temperature of the deep ocean, which has the advantage that deep ocean temperature is relatively well constrained for much of the Cenozoic. A commonly-used transformation approach is based on a 1:1 deep ocean-GMST scaling factor prior to the Pliocene, which is a simple assumption, but to our knowledge, without a firm mechanistic basis. Here, we test the reliability of this assumption using output from a suite of climate model simulations, including those from the DeepMIP project, as well as curated data compilations for well-studied intervals throughout the Cenozoic. Our analysis demonstrates that a simple 1:1 scaling factor is likely to be a good approximation for much of the Cenozoic, possibly mechanistically rooted in an increasing winter bias in deep water formation offsetting an increase in polar amplification/stratification during intervals of global warmth. Building on this, we reevaluate the Cenozoic records of deep ocean temperature and derive a new, continuous record of GMST. Our record is substantially warmer than the most common previous approach for much of the Cenozoic, from which we derive GMST during the early Eocene Climatic Optimum of 31.3±1.3°C, supporting the notion of a greater-than-modern ECS in this past warm climate state.

How to cite: Evans, D., Brugger, J., Inglis, G., and Valdes, P.: The temperature of the deep ocean is a robust proxy for global mean surface temperature during the Cenozoic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19919, https://doi.org/10.5194/egusphere-egu24-19919, 2024.

EGU24-20177 | ECS | Orals | CL1.1.4

The ETM2 in the Tethys Realm: Extreme Planktic Foraminiferal Dwarfism 

Roberta D’Onofrio, Ruby Barrett, Daniela N. Schmidt, Eliana Fornaciari, Luca Giusberti, Gianluca Frijia, Thierry Adatte, Nadia Sabatino, Adebowale Monsuru, Valentina Brombin, and Valeria Luciani

Pronounced warming in the geological record negatively impacts ecosystems. To show the impact on different parts of the marine calcareous plankton, we present an integrated record, from two Tethyan sections, Madeago and Terche (northeastern Italy), of the planktic foraminiferal and calcareous nannofossils response to the Eocene Thermal Maximum 2 hyperthermal (ETM2, ~54 Ma). The main result of our study is the striking planktic foraminiferal dwarfism (up to ~40% decrease in test-size compared to pre-event values) recorded at the ETM2 impacting both surface and deeper dwelling species. To a lesser extent, calcareous nannofossils exhibited a size reduction as documented by an increase of ‘small placoliths’. 
Causes to explain the dwarfism can be manifold. Enhanced metabolic rate in response to warming requires more food to support growth, thus a strategy to optimize resource uptake is to enlarge surface area/volume ratio by reducing the cell mass and therefore the test-size. Deoxygenation is not likely a driver as the dwarfing occurred in both mixed layer than deeper dwelling taxa, which oxygen limitation typically limited to the thermocline.  Our foraminiferal size data from Site 1263 (Atlantic Ocean) and Site 1209 (Pacific Ocean) highlight that the pronounced dwarfism is restricted to the Tethyan area. We record local increase in productivity in our sections not observed in the open ocean sites. This could have limited the growth of symbiont bearing taxa, as in modern ocean the size of symbiont bearing taxa decreases towards to shore due to increases in productivity reducing light availability. Reduced symbiosis though cannot be the only factors as it cannot explain the dwarfing of the deep-dweller taxa in our Tethyan sections. The warming at our site is similar to open ocean sections and cannot explain this different response. Therefore, we hypothesise that local drivers could have acted additively to warming such as the input of biolimiting/toxic metals from the volcanic emissions of the Veneto Volcanic Province, which was active during the ETM2. We find the smallest size in close temporal association with peaks in magmatic derived Hg/Th-Hg/Rb recorded just before and at the ETM2 which cannot be brought into our sections through weathering. The lack of dwarfisms associated with Hg peak above the ETM2 at Terche, when warming would have ended, suggests that the volcanic input by itself was not sufficient to cause dwarfism. We speculate that volcanism could have acted synergistically causing the uniqueness of dwarfism in the global context of warming. The size reduction lasted several thousand years thus implying long term impacts of such additive drivers.

How to cite: D’Onofrio, R., Barrett, R., Schmidt, D. N., Fornaciari, E., Giusberti, L., Frijia, G., Adatte, T., Sabatino, N., Monsuru, A., Brombin, V., and Luciani, V.: The ETM2 in the Tethys Realm: Extreme Planktic Foraminiferal Dwarfism, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20177, https://doi.org/10.5194/egusphere-egu24-20177, 2024.

EGU24-344 | ECS | Posters on site | CL1.1.5

Paleoenvironmental and paleoecological changes during the early GABI in the Argentine Pampas: a stable isotope approach 

Dánae Sanz Pérez, Claudia I. Montalvo, Adriana E. Mehl, Rodrigo L. Tomassini, Manuel Hernández Fernández, and Laura Domingo

The analysis of stable isotopes in fossil mammals is a powerful tool to reconstruct paleoenvironmental and paleoecological conditions. Nevertheless, there are few works of this type focused on the Neogene of South America, specifically, on the Argentine Pampas. In this context, we perform an integrative approach for the Late Miocene-Early Pliocene of this region combining new U-Pb zircon dating and carbon and oxygen stable isotope analysis, to contextualize the paleoenvironmental and paleoecological evolution of the region. The δ13C values are used to reconstruct the diets and preferred habitats of the taxa, while changes in the δ18O values of animals forced to drink reflect variations in δ18O of meteoric water, controlled by temperature and evaporation rate. We selected a total of 270 bioapatite samples of δ13CCO3 and δ18OCO3 from eight localities of La Pampa and Buenos Aires provinces. Radioisotopic ages for six of them allowed us to pin down maximum deposition ages and a time interval of ca. 5 million years for our study (from 9.7±0.3 Ma at Arroyo Chasicó to 4.5±0.2 Ma at Farola Monte Hermoso), including the Chasicoan, Huayquerian, and Montehermosan stages/ages. We studied genera of Litopterna, Notoungulata, Rodentia, Pilosa, and Cingulata orders. During the Chasicoan Stage/Age, herbivore δ13C values point to mixed C3–C4 diets, evidencing the existence of favorable habitats for C4 plants before their great expansion. By contrast, during the Huayquerian Stage/Age, taxa show values indicative of feeding preferentially on C3 plants, except for some rodents that continued including C4 plants in their diets (possibly related to an early specialization of this group). In the latest Huayquerian-Montehermosan stages/ages, herbivorous taxa incorporated a higher percentage of C4 plants in their diets, coinciding with the global expansion of this type of vegetation. This change in δ13C values also reflects an increase in aridity and/or temperature since the Late Miocene-Early Pliocene in the area, coincident with results of other proxies. The δ18O values of the notoungulates support these interpretations, evidenced by higher δ18O values during the Chasicoan and latest Huayquerian–Montehermosan stages/ages; on the contrary, there is no trend recorded in litopterns, while only a slight decrease in δ18O values was obtained in rodents. These differences are possibly linked to the fact that each order records conditions at different scales; litopterns might register global hydrological conditions, notoungulates regional conditions, and rodents more local conditions. In addition, the difference with rodents is probably due to the fact that they obtained part of the water to cover their physiological needs by eating, in contrast to the notoungulates which needed to drink to meet these requirements.

This study was financed by the projects: PGC2018–094955–A–I00 and PID2022-138275NB-I00 (Ministerio de Ciencia e Innovación, Spain), 13G and 21G (FCEyN, UNLPam, Argentina), PGI 24 H/154 (Secretaría de Ciencia y Tecnología, UNS, Argentina). DSP acknowledges a predoctoral grant PRE2019–089848 and AEM and RLT funding from LA. TE. Andes – CONICET (2020-2021). This is a contribution of the research group UCM 910607 on Evolution of Cenozoic Mammals and Continental Palaeoenvironments.

How to cite: Sanz Pérez, D., Montalvo, C. I., Mehl, A. E., Tomassini, R. L., Hernández Fernández, M., and Domingo, L.: Paleoenvironmental and paleoecological changes during the early GABI in the Argentine Pampas: a stable isotope approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-344, https://doi.org/10.5194/egusphere-egu24-344, 2024.

This study examines marine sediment samples from Ocean Drilling Program Site 1195, Hole B (Lat 20°24.28'S; Long 152°40.24'E; water depth 420 m), located beneath the present-day pathway of the East Australian Current (EAC) on the shelf of Northeast Australia. The EAC represents the western boundary current of the South Pacific subtropical gyre. It originates from the bifurcation of the southern arm of the South Equatorial Current between 15°S and 20°S. The East Australian Current's evolution is linked to the tectonic reorganization of the Indonesian Gateway and the expansion of the West Pacific Warm Pool over geological time. Our analysis of foraminiferal relative abundance data revealed the existence of high surface productivity and reduced subsurface productivity during the 7.5–6.4 Ma Our findings suggest that the northward movement of Papua New Guinea may have commenced after 6.4 Ma, inferred from the consistent thinning of the mixed layer and shallowing of the thermocline. This aligns with the hypothesis proposing the formation of the New Guinea Coastal Undercurrent, potentially caused by the entrapment of a significant portion of the South Equatorial Current against the Papua boundaries, directing it northward. Additionally, we observe a significant decline in the relative abundance of Globigerinoides ruber and a shoaling of the thermocline during the Mid-Pleistocene Transition, coinciding with high surface productivity.

How to cite: Palei, R. R. and Gupta, A.: Paleoceanographic reconstruction of the NE shelf of Australia: Insights from surface and subsurface dynamics of the East Australian Current, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-462, https://doi.org/10.5194/egusphere-egu24-462, 2024.

Given its stance as the harbinger of modern-day climatic conditions 1, the Miocene epoch (23.03 – 5.33 Ma) is perhaps, climatologically, the most important epoch in the Cenozoic era. Within this epoch, the Middle to Late Miocene transition offers a time window to study the effects of plummeting atmospheric CO2 levels and consequent global cooling on ecosystems. Currently, we are witnessing a reversal of this scenario, namely global warming, which makes studying this transition crucial for verifying the model predictions regarding the future of our ecosystems. Herein, such a study documenting the paleoclimatic record preserved in the fossiliferous section of the Kutch region (India), a hitherto unexplored area, is presented. It spans two localities: Palasava (~14 Ma) & Tappar (~10 Ma), one each from the Middle and Late Miocene sub-epoch and utilises the carbonate phase from enamel remains of megafaunal herbivore mammals (Proboscideans & Rhinocerotids) as the investigatory tool. Enamel δ13C signature is indicative of ambient vegetation type due to the differential assimilation of C isotopes in diet plant tissue as a function of different carbon fixing mechanisms in C3 and C4 plants 2. δ18O signal, on the other hand, is reflective of the environmental rainfall intensity and seasonality because the rainfall isotopic composition is a function of temperature and amount effect during precipitation. Large-bodied obligate drinker mammals are most efficient for these reconstructions 3, which justifies the choice of mammals in this study.

The Palasava and Tappar samples have ranges of +0.20‰ to +4.24‰ and -3.97‰ to +5.47‰, respectively, for δ18O values. The larger scatter within the latter indicates higher seasonality in the Late Miocene relative to the Middle Miocene, which aligns well with the idea of intensification of the Indian summer monsoon regime during the younger sub-epoch4. Parallelly, the δ13C signature for Palasava samples ranges from -11.23‰ to -9.42‰ while the Tappar ones are between -12.95‰ and -10.64‰. The former represents woodland browsing, whereas the latter indicates forest-woodland browsing. Both localities imply C3-dominated environments. Since Tappar straddles the beginning of the Late Miocene, it is acceptable to think that C3-dominated habitats must have persisted up till this time, and it was only much later and perhaps fuelled by enhanced rainfall seasonality that C4 grasses became abundant and eventually, grassland expansion took place.

Conclusively, the observed trends agree with the ones seen for contemporaneous Siwalik samples and comply with the hypothesis of increasing rainfall seasonality towards the Late Miocene sub-epoch followed by eventual, and perhaps consequential, expansion of C4 grasses during the later part of Late Miocene.

References:

  • Steinthorsdottir, M. et al. The Miocene: The Future of the Past. Paleoceanography. Paleoclimatology 36, (2021).
  • Patnaik, R., Singh, N. P., Paul, D. & Sukumar, R. Dietary and habitat shifts in relation to climate of Neogene-Quaternary proboscideans and associated mammals of the Indian subcontinent. Quat. Sci. Rev. 224, 105968 (2019).
  • Daniel Bryant, J. & Froelich, P. N. A model of oxygen isotope fractionation in body water of large mammals. Geochim. Cosmochim. Acta 59, 4523–4537 (1995).
  • Raymo M.E. & Ruddiman W.F. Tectonic Forcing of Late Cenozoic Climate. Nature 359, 117–122 (1992).

How to cite: Priya, B., Patnaik, R., and Ghosh, P.: A stable isotope record documenting the Middle to Late Miocene climate transition from the Kutch Tertiary group, Gujarat (India), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1393, https://doi.org/10.5194/egusphere-egu24-1393, 2024.

EGU24-2807 | ECS | Posters virtual | CL1.1.5

Stable isotopes and palaeo-hydrological implications of Tunisian laminar calcretes during the late Pliocene - early Pleistocene 

Farah Jarraya, Barbara Mauz, Mike Rogerson, Nejib Kallel, Nouredidne Elmejdoub, and Abdeljalil Sghari

During the late Pliocene-early Pleistocene Tunisian calcretes were formed in a soil environment. Fabrics at the macro and micro scale show that these deposits are similar to rhizogenic modern analogue systems forming in Spain. We infer that a similar climate prevailed in Tunisia in the past, specifically winter-season rainfall and a dry summer with annual rainfall close to 430 mm/year in the center of Tunisia. Here, we provide further constraints on the climate under which the Tunisian calcrete formed by looking at vegetation structure, water advection and amount of seasonal rainfall.

To investigate (1) the palaeo-vegetation type(s) if they are C3 or C4 plants and (2) the source(s) of meteoric water of Tunisian calcretes during that era, stable isotopes of C and O were analysed in 25 samples taken from 5 horizontal laminar calcretes cores, from 3 sites: North (N36º.43.713; E10º.06.681’), Center (N35º.07.077’; E10º.14.545’), South (N33º.28.898’; E10º.23.602’). Results are expressed relative to the VPDB reference.
In the North, the δ18O samples show values varying from – 4.78 ‰ to -6.91 ‰. Likewise, central site cores are characterised by δ18O values ranging from -5.32 ‰ to -6.97 ‰. In contrast, the δ18O values from the South are more depleted (-8.82 ‰ to -7.20 ‰). Concerning the carbon isotope results, both central and southern sites show similarly enriched δ13C values with an average of -6 ‰, while the North site shows more depleted values (-11.3 ‰ to -9.6 ‰). The δ18O values are similar to those determined in the last deglaciation/early Holocene speleothem carbonates from caves in the Tunisian Atlas Mountains, indicating a North Atlantic source. The north-to-south difference in both isotope systems reveals a decoupling between precipitation δ18O and vegetation effects. The southern site shows more depleted water isotopes (a consequence of internal water recycling effects) and more enriched δ13C, consistent with C4 vegetation and/or lower soil respiration. The central site shows low water recycling, but southern-like dryland vegetation. The northern site shows low water recycling and C3 vegetation and/ or higher soil respiration. Consequently, although there is enhanced humidity in all three sites, the sites do not record the same amount of rainfall and the same response of the landscape to form calcretes.

How to cite: Jarraya, F., Mauz, B., Rogerson, M., Kallel, N., Elmejdoub, N., and Sghari, A.: Stable isotopes and palaeo-hydrological implications of Tunisian laminar calcretes during the late Pliocene - early Pleistocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2807, https://doi.org/10.5194/egusphere-egu24-2807, 2024.

The Middle Miocene Climatic Optima (MMCO; 17–14.5 Ma) is warmest over the last 23 Myrs, with higher pCO2 (400–500 ppmv; Foster et al., 2012, Super et al., 2018), ~6 °C warming in a mid-latitude compared to the present (Flower and Kennett, 1994), and a large reduction (30–36 m) in Antarctic ice volume (Gasson et al., 2016). The eruption of CO2 from the Columbia River flood basalt has been suggested as a primary cause of the MMCO. However, the mechanisms of the progressive global cooling after the MMCO remain highly controversial. Here, we provide novel paleoceanographic information on the Antarctic Intermediate Water (AAIW) in the Pacific sector of the Southern Ocean to improve our understanding of climate–ocean conditions during the MMCO. In this study, we analyzed the middle Miocene biopelagic sediments (> 90% CaCO3 contents) from ODP Site 1120 (50°3.8′S, 173°22.3′E), located on the central Campbell Plateau off the South Island of New Zealand (Ando et al., 2011). Because the middle Miocene paleo-water depth at Site 1120 is estimated to be similar to the present water depth (~600 m), analyses of oxygen and carbon isotopic compositions of benthic foraminifer and neodymium (Nd) isotopes of fossil fish teeth/debris allow us to characterize the AAIW during the deposition. We present newly measured 17.5–8.5 Myr records of Nd isotopes of fossil fish teeth/debris, planktonic foraminiferal δ18O, δ13C, Mg/Ca, and Ba/Ca from Site 1120. The εNd values ranged from -7.5 to -3.2 at 17.5–8.5 Ma. In contrast, during the Middle Miocene Climate Transition (MMCT, 14.5–13.5 Ma), εNd values shifted rapidly toward more radiogenic values (~-3.2) and then gradually returned to less radiogenic values (-7 to -6). Such a large long-term variation of εNd values has not been reported in previous datasets, which is the first records to represent the characteristics of the AAIW in the Pacific sector of the Southern Ocean during the MMCT. We argue for the two possible causes of these εNd changes in the AAIW: 1) there might have been an anomalous supply of radiogenic Nd due to the intense physical weathering in West Antarctica caused by the onset of glaciation and 2) the equatorial surface water, characterized by high εNd values, might have expanded toward the high latitudes and a part of the water mass was incorporated into the intermediate layer in the Southern Hemisphere.

How to cite: Khim, B.-K., Horikawa, K., and Asahara, Y.: Anomalous eNd change of the Antarctic Intermediate Water in the Pacific sector of the Southern Ocean during the Middle Miocene Climate Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3364, https://doi.org/10.5194/egusphere-egu24-3364, 2024.

EGU24-6785 | ECS | Orals | CL1.1.5 | Highlight

High-resolution multi proxy records across the Plio-Pleistocene boundary: a central Mediterranean perspective 

Elena Zanola, Sergio Bonomo, Patrizia Ferretti, Eliana Fornaciari, Alessandro Incarbona, Teresa Rodrigues, and Luca Capraro

The central Mediterranean region is traditionally acknowledged as a key reference area for investigating the Northern Hemisphere climate variability over the last few million years.

Specifically, the expanded and highly fossiliferous open-marine succession currently exposed along the shoreline of Southern Italy and Sicily offers a pristine sedimentary record of the Neogene to Quaternary interval, which can be tightly constrained in time and deeply investigated by means of a manifold array of paleoenvironmental and paleoclimatic proxies (e.g., Cita et al., 2008; Capraro et al., 2017, 2022).

In this context, the Monte San Nicola (MSN) section, located in Southern Sicily, provides an exceptional stratigraphic record for studying the climate evolution throughout the Piacenzian to Gelasian interval. The MSN succession hosts the GSSP for the Gelasian Stage (ca. 2.58 Ma; Rio et al., 1998), which presently marks the base of both the Pleistocene Serie and the Quaternary System (Head et al., 2008). The section is currently under revision, especially in the interval straddling the Gelasian GSSP, which includes the definitive establishment of the Northern Hemisphere Glaciation (NHG), at around 2.6 Ma. This cooling event is marked by a triplet of glacial stages (i.e., MIS 100, 98 and 96) that are found just above the Piacenzian-Gelasian boundary.

In the wake of the emerging interest towards the MSN section, we are currently committed to reconstructing a high-resolution multi-proxy record (foraminiferal δ18O and δ13C, Alkenones-derived SSTs, C37total and Alcoholic index) in the lower part of the “Mandorlo” section at MSN (Capraro et al., 2022; Zanola et al., 2024). Results achieved so far provide new insights on the paleoceanographic and paleoclimatic evolution of the central Mediterranean at the sub-orbital scale at the beginning of the NHG.

How to cite: Zanola, E., Bonomo, S., Ferretti, P., Fornaciari, E., Incarbona, A., Rodrigues, T., and Capraro, L.: High-resolution multi proxy records across the Plio-Pleistocene boundary: a central Mediterranean perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6785, https://doi.org/10.5194/egusphere-egu24-6785, 2024.

EGU24-7348 | ECS | Orals | CL1.1.5

Multicellular eukaryotes followed:MOE or life stagnation 

Ruihan Duan, Pengchen Ju, Ruliang He, Jinlong Yao, and Guochun Zhao

The discovery of the fossils of decimetre-scale multicellular eukaryotes in the Mesoproterozoic from the 1.56-Gyr-old Gaoyuzhuang Formation in the North China Craton indicates that eukaryotes have evolved to a high level, but the evolution of life after it is still unclear due to the lack of definitive fossil evidence. Multi-proxies suggests that a pulsed oxygenation event was recorded during1.56-1.57 Ga, but the subsequent ocean oxygen levels are unequivocal. Here we report I/(Ca+Mg) ratios, carbonate C-O isotopes, and Ce anomaly across the ca. 1.56-1.50 Ga in the North China Platform. The results showed that the evolution of ocean oxygen content could be divided into four stages: (1)The δ13Ccarb values remained stable at 0‰ , and the I/(Ca+Mg) ratios was near detection limit, with no Ce anomaly from 1.56 to 1.53Ga, indicating that the ocean was anoxic; (2)The I/(Ca+Mg) ratios increased to 1.2μmol/mol with an excursion from 0‰ to -2.6‰ negative δ13Ccarb anomaly, and a negative Ce anomaly to 0.56 in 1.52Ga, which may be the result of the oxidation of the dissolved organic carbon(DOC) in the ocean, and the ocean changed from anoxic to oxic;(3) The C isotope composition 0‰ , with I/(Ca+Mg) ratios maintained at 0μmol/mol-0.5μmol/mol, and there was no Ce anomaly in 1.51Ga. Oxygen consumption through oxidation of DOC may have quickly lowered marine O2 levels to suboxic.(4) A positive shift in  δ13Ccarb from 0 ‰ to +2.1‰, and the I/(Ca+Mg) increased to 1μmol/mol, without obvious Ce anomaly, which may be a certain degree of biological flourishing leading to the increase of oxygen content in the ocean. Although the ocean in 1.52Ga was oxic, the oxygen levels were low, which may be a key factor restricting the evolution of eukaryotes.

How to cite: Duan, R., Ju, P., He, R., Yao, J., and Zhao, G.: Multicellular eukaryotes followed:MOE or life stagnation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7348, https://doi.org/10.5194/egusphere-egu24-7348, 2024.

EGU24-7606 | Posters on site | CL1.1.5 | Highlight

Spring distribution in Quaternary deposits, South Carpathians, Romania: isotope composition, chemistry and radiocarbon dating 

Ana-Voica Bojar, Stanislaw Chmiel, Hans-Peter Bojar, Carmen Varlam, Victor Barbu, and Andrzej Pelc

The investigated area is part of a plateau situated at around 350m elevation in the south-western part of the South Carpathians. The area is crossed from north-west to south-east by dry valleys, which cut Pleistocene and Quaternary clastic deposits. Water is flowing across these valleys temporarily, after strong storms or during rainy periods. A groundwater geochemistry study was carried out on water samples collected from different springs and wells. The study was motivated by the fact that springs have represented the only source of potable water in the region, only recently completed by a few wells.

Spring distributions and geological data reveal the presence of a multi-layered system situated in the Lower Quaternary deposits. Precipitations and meteorological parameters were monitored in the region for a period over 10 years. The mean δ18O and δD values of groundwater reflect the yearly weighted mean of the isotopic composition of precipitation, demonstrating locally derived recharge. The aquifers are situated at different depths in clastic deposits; the shallower aquifers are affected by evaporations during the drought periods of the summer.

The water samples have concentrations of 157 to 852 mg/l for anion and 55 to 308 mg/l for cations, with TDS between 212 and 1157 mg/l. The total dissolved salts limit proposed in the guideline of WHO is 1200 mg/l, above the limit water having a bad taste, all the measured samples are below this limit.

The Piper ternary diagrams for spring water indicate that the dominant hydrochemical types is HCO3--Ca+2-Mg+2 with transition toward higher SO4-2 and Mg+2  contents to the deeper aquifer. The anions vary from HCO3- with transition to no dominant- and with Cl- contents higher for the shallower aquifer. The sequence of abundance of cations is generally Ca2+>Mg+2>K+>Na+ and for anions: HCO3->SO4-2>Cl->NO3->F-. The Gibbs diagrams indicate rock weathering as a major driving force for driving the groundwater ionic chemistry in the study area. Radiocarbon dating of DIC (dissolved inorganic carbon) indicates a sub recent recharge of the aquifers.

The vertical and lateral variations in groundwater chemistry may vary, and are influenced by lateral lithologic variation of the Quaternary clastic deposits. This is an unpredictable quality factor when taking the decision for the drinking water drill locations.

How to cite: Bojar, A.-V., Chmiel, S., Bojar, H.-P., Varlam, C., Barbu, V., and Pelc, A.: Spring distribution in Quaternary deposits, South Carpathians, Romania: isotope composition, chemistry and radiocarbon dating, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7606, https://doi.org/10.5194/egusphere-egu24-7606, 2024.

EGU24-7711 | Orals | CL1.1.5 | Highlight

A Versatile Water Vapor Generation Module for Vapor Isotope Calibration and Liquid Isotope Measurements 

Hans Christian Steen-Larsen and Daniele Zannoni

A versatile vapor generation module has been developed for the purpose of both field water vapor isotope calibrations and laboratory liquid water isotope measurements. The vapor generation module is fully scalable allowing in principle an unlimited number of standards or samples to be connected, opening up the possibility for calibrating with multiple standards during field deployment. Compared to a standard autosampler system, the vapor generation module has a more than 2 times lower memory effect. The vapor generation module can in principle generate a constant stream of vapor with constant isotopic composition indefinitely. We document an Allan Deviation for 17O-excess (Δ17O) of less than 2 per meg for an approximate 3 hour averaging time. For similar averaging time the Allan Deviation for 𝛿17O, 𝛿18O, 𝛿D, d-excess is 0.004, 0.006, 0.01, 0.03 ‰. Measuring unknown samples for Δ17O show that it is possible to obtain an average standard deviation of 3 per meg leading to an average standard error (95 % confidence limit) using 4-5 replicates of 5 per meg.

Using the vapor generation module we document that an enhancement in the Allan Deviation above the white noise level for integration times between 10 minutes and 1 hour is caused by cyclic variations in the cavity temperature. We further argue that increases in Allan Deviation for longer averaging times could be a result of memory effects and not only driven by instrumental drifts as it is often interpreted as.

The vapor generation module as a calibration system have been document to generate a constant water vapor stream for a period of more than 90 hours showing the feasibility of being used as an autonomous field vapor isotope calibration unit for more than 3 months.

How to cite: Steen-Larsen, H. C. and Zannoni, D.: A Versatile Water Vapor Generation Module for Vapor Isotope Calibration and Liquid Isotope Measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7711, https://doi.org/10.5194/egusphere-egu24-7711, 2024.

EGU24-8232 | Posters on site | CL1.1.5 | Highlight

On the radiocesium distribution on the Romanian territory 30 years after the Chernobyl disasters 

Octavian G. Duliu, Ana-Maria Blebea-Apostu, Romul Mircea Margineanau, Diana Persa, and Maria-Claudia Gomoiu

The Chernobyl 1986 accident, considered one of the worst of its kind, occupies the highest 7th position on the seven levels IAEA International Nuclear and Radiological Event Scale. Following the thermal explosions which took parts, an impressive amount of new and spent nuclear fuel, rich in fission and neutron activation products was dispersed into the atmosphere at an altitude up to a few km, but without reaching the stratosphere. In this way, about 20 to 40 % of the total radiocesium inventory estimated to be 280 PBq of 137Cs was transported by the atmospheric circulation contaminating significant areas of Ukraine, Belarus, Russia, Scandinavian countries, Central and Eastern Europe. Its presence was signaled also in Japan, Canada, and the United States.

Due to the geographical position of Romania in the vicinity of Ukraine, the total 137Cs contamination of Romanian territory was estimated immediately after the Chernobyl accident at 51 ± 2 TBq, an estimation based on more detailed measurements performed during the 1993 y on 62 locations.

Under these circumstances, and for a more accurate estimation of the 137Cs contamination, 747 soil samples covering the entire Romanian territory were collected, and the radiocesium inventory was measured by gamma-ray high-resolution spectroscopy performed in the low backgrounder laboratory located in the Slanic-Prahova former salt mine. Soil sampling and radiometric measurements were performed between 2016 and 2018 years, all data being recalculated for May 2016, i.e. 30 years after the Chernobyl accident.

The results showed for the 2016 radiocesium distribution an irregular pattern containing four maxima of which positions were quite different from the 1993 ones. Concerning the 137Cs inventory, its total value decreased from 43 ± 2 TBq in May 1993 to 14.1± 0.7 TBq in May 2016, i.e. by a factor of 3 ± 0.3, twice of natural disintegration. This finding could be explained by taking into account that a significant amount of radiocesium was washed out by precipitation and, in a lower measure, was incorporated into plants.

The same data permitted evaluation of the total contribution of 137Cs to the population exposure. Accordingly, in 1993 and even more so in 2016, the average supplementary annual effective dose did not exceed 1 mSv, i.e. the maximum annual effective dose considered not harmful for the unexposed population.

How to cite: Duliu, O. G., Blebea-Apostu, A.-M., Margineanau, R. M., Persa, D., and Gomoiu, M.-C.: On the radiocesium distribution on the Romanian territory 30 years after the Chernobyl disasters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8232, https://doi.org/10.5194/egusphere-egu24-8232, 2024.

EGU24-8530 | ECS | Orals | CL1.1.5

Isotopic signatures from the weathering of ophiolitic massifs and volcanic deposits in the Zambales region, Philippines. 

Chris Tsz Long Cheung, Ryan McKenzie, Juan Miguel Guotana, Brian Beaty, Yonghui Qin, Giancarlo DeFrancesco, Bianca Maria Laureanna Pedrezuela, Dan Asael, Noah Planavsky, and Decibel V. Faustino-Eslava

Lithium isotopes (d7Li) are a useful proxy to track silicate weathering, the fundamental process in which carbon is removed from Earth’s surface. Here we present d7Li and elemental data from 14 riverine localities in the Zambales region, Philippines. The warm, humid climate coupled with monolithic rivers draining ophiolitic massifs and volcanic deposits (from the major 1991 Pinatubo eruption) allows for the comparison of silicate weathering and riverine geochemistry across different lithologies. The most striking part of our dataset is that all rivers draining ophiolitic terranes have heavier d7Lidiss values (range from 22.8 to 37.1‰) than those draining Pinatubo volcanic deposits (range from 8.9 to 18.4‰). As all rivers feature similar topographic relief and hydrological conditions, this suggests a strong lithological influence on d7Lidiss values despite both bedrock lithologies being highly weatherable. We postulate that the mafic and ultramafic composition of the ophiolite terrain significantly enhances incongruent weathering and clay mineral formation, increasing Li fractionation, and leading to the heavier d7Lidiss values. Conversely, the lighter d7Lidiss values for the Pinatubo rivers could be explained by the more felsic composition and unconsolidated nature of the volcanic deposits leading to increased congruent weathering and low clay formation, and thus low Li fractionation. Notable differences in major element concentrations are also observed. The Mg2+ is the dominant cation in ophiolitic-draining rivers reflecting the weathering of Mg-rich mafic and ultramafic minerals. Meanwhile, Na+ and Ca2+ dominate in rivers flowing off the Pinatubo volcanic deposits. The ophiolitic-draining rivers also have total major cation concentrations ([Na+] + [Mg2+] + [K+] + [Ca2+]) almost 3.5 times lower than those draining the volcanic deposits (~1600 vs ~5600 µM). Despite the composition of the ophiolites consisting of highly weatherable mafic and ultramafic minerals, the volcanic deposits are seemingly even more favorably weathered. This is interpreted to be caused by the freshness of the material deposited from the recent eruption. Overall, our study shows that despite all rivers in this study draining highly weatherable lithologies, their intrinsic lithological differences can lead to significantly contrasting d7Lidiss and major cation signatures. New clay mineralogical data from riverine sediments will further inform us on silicate weathering processes in the region.

How to cite: Cheung, C. T. L., McKenzie, R., Guotana, J. M., Beaty, B., Qin, Y., DeFrancesco, G., Pedrezuela, B. M. L., Asael, D., Planavsky, N., and Faustino-Eslava, D. V.: Isotopic signatures from the weathering of ophiolitic massifs and volcanic deposits in the Zambales region, Philippines., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8530, https://doi.org/10.5194/egusphere-egu24-8530, 2024.

EGU24-9747 | ECS | Orals | CL1.1.5

Westerly jet shifts over the last glacial cycle revealed by provenance of Japan Sea dust   

Lingle Chen, Chuang Xuan, Anya J. Crocker, and Paul A. Wilson

Asian deserts are major sources of dust loading to the atmosphere, second only to those of North Africa. Today, dust activation in central and eastern Asia and convective rainfall over eastern China are preconditioned by the seasonal weakening of the Siberian High-Pressure system and migration of the Westerly Jet (WJ) northwards of the Tibetan Plateau during spring. Once activated, East Asian dust is transported over long distances to the North Pacific Ocean and to Greenland. Downcore records from locations on the dust transportation pathway provide valuable information about changes in past aridity and wind systems. Recent studies suggest that the westerlies were weaker and shifted towards more poleward latitudes than today during the warm Pliocene. However, the available data are too sparse to evaluate variability on glacial-interglacial timescales and often of questionable attribution (uncertain provenance). Here we report new downcore radiogenic isotope (Nd, Sr) records of dust provenance change over the last glacial cycle (150 kyrs to present) from the Japan Sea. Our records benefit from a thorough treatment protocol to remove the imprint of contaminating marine phases (including barite) and non-dust material and show remarkably clean glacial-interglacial structure. We report a marked shift in East Asian dust sources from glacial to interglacial conditions that has important implications for our understanding of the behaviour of the Siberian High-Pressure system and the westerly jet in response to changes in atmospheric carbon dioxide concentrations and ice sheet extent on geological timescales.

How to cite: Chen, L., Xuan, C., J. Crocker, A., and A. Wilson, P.: Westerly jet shifts over the last glacial cycle revealed by provenance of Japan Sea dust  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9747, https://doi.org/10.5194/egusphere-egu24-9747, 2024.

EGU24-9896 | ECS | Posters on site | CL1.1.5

Testing the efficacy of grain size-sorted sediment for biomarker analysis to reconstruct palaeoclimate 

Joe Hingley, P. Sargent Bray, Gavin Foster, Jessica Whiteside, Bridget Wade, and Gordon Inglis

Following the announcement of the retirement of the JOIDES Resolution drilling platform, it has become even more important to efficiently utilise the finite resource of marine sediment stored in IODP repositories. Marine sediments processed for inorganic geochemical analysis are often separated into fine (<0.63 µm) and coarse (>0.63 µm) fractions to help isolate benthic and planktonic foraminifera. However, organic matter can be associated with different particle size fractions and may have experienced different transport and diagenetic processes. Previous studies have suggested that sieving sediments into different size fractions does not affect the distribution of isoprenoidal [1,2] and branched glycerol dialkyl glycerol tetraethers (GDGTs) [3]. However, this has never been systematically investigated across a wide range of sample types (e.g., age, depositional environment, thermal maturity). It is also unclear whether size processing affects other lipid biomarker proxies (e.g., leaf waxes, alkenones).

Here we test whether processing marine sediments into different size fractions influences lipid distributions by separating sediments into fine (<0.63 µm) and coarse (> 0.63 µm) fractions and comparing these to corresponding bulk un-sieved sediments. Temperature reconstruction using the marine sea surface temperature proxy TEX86 shows relatively minimal deviation (average ±0.12 TEX86 units, or ~2-3 °C) between the bulk un-sieved sediment (i.e,. control) and fine (<63 µm) fraction, suggesting isoGDGTs are well preserved in the fine fraction. In contrast, relatively more variation is seen in the coarse fraction (±0.25 TEX86 units, or >10 °C). We also analysed leaf wax derived n-alkanes extracted from the marine sediment to evaluate the impact on terrestrial biomarkers. The average chain length shows similar deviation in both the fine (±0.21 units) and coarse (±0.21 units) fractions relative to the bulk sediment, suggesting that either fraction is suitable for interpreting first-order changes in vegetation type.  Moving forward, our results suggest that the fine fraction of grain size-sorted sediment yield similar lipid distributions compared to the bulk un-washed sediment. However, coarse fractions often show large deviations from the bulk sediment across different proxies, perhaps making these unsuitable for biomarker-based climate reconstruction.

References
[1] Zachos et al., Geology, 34, 9, pp 737-740 (2006)
[2] Xiao et al., Global Biogeochemical Cycles, 37, e2022GB007648 (2023)
[3] Peterse and Eglinton, Frontiers in Earth Science, 5, 49 (2017)

How to cite: Hingley, J., Bray, P. S., Foster, G., Whiteside, J., Wade, B., and Inglis, G.: Testing the efficacy of grain size-sorted sediment for biomarker analysis to reconstruct palaeoclimate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9896, https://doi.org/10.5194/egusphere-egu24-9896, 2024.

EGU24-12864 | ECS | Posters on site | CL1.1.5

A radiogenic isotope framework to study palaeoaridity in the Middle East 

Kai Zhang, Tereza Kunkelova, Anya J. Crocker, Amelia Gale, Chuang Xuan, and Paul A. Wilson

Dust plays a vital role in global climate and environmental change by influencing the Earth’s radiation budget and providing nutrients to marine and terrestrial ecosystems. Modern dust emissions are dominated by North Africa, the Middle East and West Asia, which together provide ~80% of total global atmospheric dust. Geological deposits of dust can also act as valuable archives to study hydroclimate variability across a range of global states, with marine sediments in particular able to preserve high resolution and continuous records of past dust emissions. For example, dust preserved in Arabian Sea sediments has been used to provide climatic context for hominin evolution in East Africa, however, there is little understanding of where the deposited sediments originate and hence whether they truly record an African signal. Tracing the provenance of the lithogenic fraction in marine sediments is made particularly challenging by the lack of geochemical data in key potential source areas such as Mesopotamia, one of the most active dust emission regions in the Middle East. Here we present new radiogenic isotope data (Sr and Nd) from surface sediment samples, integrated with the satellite-derived dust source activation frequency (DSAF) maps and other published radiogenic data to characterise the geochemical fingerprint of dust-producing regions in the circum Arabian Sea. Our results provide a framework to trace sources of dust in geological archives including marine sediments, speleothems and ice cores and to identify the provenance of archaeological artefacts. We exemplify the utility of our approach by comparing our data to strategically positioned marine cores in the Arabian Sea to shed new light on key regional palaeoclimate reconstructions.

How to cite: Zhang, K., Kunkelova, T., Crocker, A. J., Gale, A., Xuan, C., and Wilson, P. A.: A radiogenic isotope framework to study palaeoaridity in the Middle East, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12864, https://doi.org/10.5194/egusphere-egu24-12864, 2024.

EGU24-13265 | ECS | Orals | CL1.1.5 | Highlight

Climate, fire, and vegetation history from loess-palaeosol sequences in Southern Tajikistan, Central Asia during early Palaeolithic: Reconstruction using organic biomarkers and stable isotopes 

Aljasil Chirakkal, David K Wright, Calin Constantin Stiendal, Jago Jonathan Birk, Redzhep Kurbanov, and Jan-Pieter Buylaert

We reconstruct palaeoenvironmental conditions with multi-proxy records from loess-palaeosol settings in Tajikistan, Central Asia. Landscape conditions in this area are poorly characterised, ambiguous, and difficult to determine, which confounds models of human dispersal out of Africa. This region has been the focus of Russian-Tajik archaeological projects since the 1970s, as it contains evidence of some of the earliest (~600-400 ka) hominin occupations in Central Asia and has yielded numerous Lower Palaeolithic artifacts. In the present study, fire and vegetation biomarkers and stable isotopes have been used to reconstruct fire and vegetation histories in loess-palaeosol samples of early Palaeolithic sites in the vicinities of the Obi-Mazar River in the Khovaling district of southern Tajikistan. Samples from four loess-palaeosol documented profiles were analysed for linear chain alkanes (n-alkanes) and polycyclic aromatic hydrocarbons (PAHs) together with soil stable isotopes (δ13C, δ15N). The fluctuations in the values of n-alkane derived indices showed vegetation changes in concert with glacial-interglacial variability. The δ13C values fell between -20‰ and -25‰ (vs. PDB) and revealed mixed input of C3 and C4 plant organic matter into loess-palaeosol sediments, while δ15N values varied between 3.5‰ and 6.5‰ (vs. AIR) indicating high litter content and tree abundance. The fluctuations in total PAH abundance and increased low to high molecular weight ratio values revealed fire activity and lower temperature burning events during interglacial periods relative to glacial periods.  Moreover, the strong positive correlation between PAHs and deposits that hosted the densest artifact assemblages signals early hominin use of fire in the catchment during MIS 11, 13, and 15. Therefore, our study demonstrates substantial hominin influences on the environment dating to over 500 ka indicating human-ecological processes far predate the modern era.

How to cite: Chirakkal, A., K Wright, D., Constantin Stiendal, C., Jonathan Birk, J., Kurbanov, R., and Buylaert, J.-P.: Climate, fire, and vegetation history from loess-palaeosol sequences in Southern Tajikistan, Central Asia during early Palaeolithic: Reconstruction using organic biomarkers and stable isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13265, https://doi.org/10.5194/egusphere-egu24-13265, 2024.

EGU24-15805 | ECS | Orals | CL1.1.5

Investigating ophiolite weathering via lithium isotopes in the Indo-Burma range of northeast India 

Giancarlo DeFrancesco, Ryan McKenzie, Chris Tsz Long Cheung, Nongmaithem Lakhan Singh, Yengkhom Raghumani Singh, Brian Beaty, Dan Asael, Jed Oliver Kaplan, and Noah Planavsky

The weathering of silicate minerals regulates climate on million-year timescales. Some silicate bedrock, particularly ophiolites, are more susceptible to enhanced weathering than other lithologies. Lithium isotopes (δ7Li) are a proxy that can be used to help track weathering processes due to the fractionation of Li during secondary clay mineral formation. Here we present data collected from tributaries that source the Nagaland-Manipur Ophiolite Complexes in northeastern India, which ultimately flow into the Irrawaddy River in Myanmar, to test the hypothesis that the weathering of ultramafic terrains generated by arc-continent collisions can drive rapid atmospheric carbon drawdown. Major cations, anions, trace elements, δ7Li, and clay mineralogical compositions were measured from river water, bedload, and suspended sediment to gain insight into silicate weathering processes in the region. Our results show streams and rivers in this region contain δ7Li values that range from 20.6 to 31.2‰, with the ophiolitic-sourced tributaries being heavier than the global riverine average of ~23‰. This indicates that rivers draining ultramafic lithologies in warm humid climates are experiencing higher degrees of weathering intensity than other drainages comprised of more felsic lithologies. Additionally, XRD results show that most river bedload contains smectite clays, which may help promote organic carbon burial. These data combined highlight new pathways toward understanding silicate weathering as it relates to atmospheric CO2 drawdown.

How to cite: DeFrancesco, G., McKenzie, R., Cheung, C. T. L., Singh, N. L., Singh, Y. R., Beaty, B., Asael, D., Kaplan, J. O., and Planavsky, N.: Investigating ophiolite weathering via lithium isotopes in the Indo-Burma range of northeast India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15805, https://doi.org/10.5194/egusphere-egu24-15805, 2024.

EGU24-18475 | ECS | Posters on site | CL1.1.5 | Highlight

Chromium isotope compositions of sediments from the global oceans 

Sylvie Bruggmann, Patrick Blaser, and Samuel Jaccard

The chromium (Cr) isotope system (δ53Cr) is a promising tool to reconstruct changes in marine redox conditions and biological productivity through geological time, but uncertainties remain regarding the pathway of Cr from the water column to the sediment record (Janssen, 2021; Huang et al., 2021; Bruggmann et al., 2023). While sediment Cr concentration and isotope data are available from continental margin sites and oxygen minimum zones (e.g., Gueguen et al., 2016; Bruggmann et al., 2019), modern sediments from open marine settings are understudied. Such sediments can provide key information to understand how Cr from the water column or across the sediment-water interface accumulates in the sediment.

We will investigate the response of Cr concentrations and isotope compositions (i) in the authigenic fraction of different types of pelagic sediments (carbonate-rich versus clay-rich) (ii) from the North Atlantic to the North Pacific to complement published seawater δ53Cr values, and (iii) their changes during well-characterised climate changes in the Quaternary, specifically the Last Glacial Maximum (LGM). The database of Cr isotope compositions in the modern global oceans resulting from this study will significantly enhance the interpretation of Cr isotope changes in sediments from the geological record.

 

References

Bruggmann S., Severmann S. and McManus J. (2023) Geochemical conditions regulating chromium preservation in marine sediments. Geochimica et Cosmochimica Acta 348, 239–257.

Gueguen B., Reinhard C. T., Algeo T. J., Peterson L. C., Nielsen S. G., Wang X., Rowe H. and Planavsky N. J. (2016) The chromium isotope composition of reducing and oxic marine sediments. Geochimica et Cosmochimica Acta 184, 1–19.

Huang T., Moos S. B. and Boyle E. A. (2021) Trivalent chromium isotopes in the eastern tropical North Pacific oxygen-deficient zone. Proc. Natl. Acad. Sci. U.S.A. 118.

Janssen D. J. (2021) Release from biogenic particles, benthic fluxes, and deep water circulation control Cr and δ53Cr distributions in the ocean interior. Earth and Planetary Science Letters 574,117163.

How to cite: Bruggmann, S., Blaser, P., and Jaccard, S.: Chromium isotope compositions of sediments from the global oceans, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18475, https://doi.org/10.5194/egusphere-egu24-18475, 2024.

EGU24-18743 | ECS | Posters on site | CL1.1.5

Interpolating proxy observations to high-resolution XRF data 

Patrick Blaser, Jörg Lippold, Sylvie Bruggmann, Michael Bollen, Xavier Crosta, and Samuel Jaccard

Proxy observations are the fundament for many insights in geosciences, such as the reconstruction of past environmental conditions from sediment cores. However, the labor-intensive nature of producing proxy data often renders high-resolution records prohibitively expensive. In contrast, state-of-the-art XRF analyses offer an efficient means of generating high-quality and very high-resolution elemental concentration data. Although these data initially provide only qualitative information about the bulk sample composition, their high-resolution renders them invaluable as a foundation for subsequent studies.

Here we explore the potential utility of high-resolution XRF data as a foundation for interpolating more scarce sedimentological, geochemical, and environmental analyses to the same high-resolution. We base the investigation on a long sediment core obtained from the Crozet Plateau in the Indian sector of the Southern Ocean, where changes in surface productivity, dust influx, and delivery of detritus from the nearby island dominate the sedimentological and geochemical signals.

We test different statistical methods for sediment classification and the interpolation of proxy data and discuss their reliability and limitations. For instance, application of a random forest model for the interpolation of carbonate and opal concentration conspicuously reveals the presence of distinct detrital layers. These layers are not readily discernible in the original XRF data or the sparse original opal and carbonate measurements.

We propose these straight-forward statistical methods have potential to be used on many other sediment records for which high-quality and high-resolution XRF data and certain proxy observations are available. Such an approach can streamline the interpretation of XRF data and enhance the investigation of specific environmental proxy observations at a high-resolution.

How to cite: Blaser, P., Lippold, J., Bruggmann, S., Bollen, M., Crosta, X., and Jaccard, S.: Interpolating proxy observations to high-resolution XRF data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18743, https://doi.org/10.5194/egusphere-egu24-18743, 2024.

Sun-climate connection is a well-documented expression of earth´s climate system. Higher sensitivity to solar forcing is evident in many paleoclimate records, ranging from decadal to millennial time scales. Considering the Indian monsoon domain, Summer Monsoon show asynchronous variations with energy output of the Sun throughout Holocene, however the response of its winter counterpart is not well understood. This study aims to explore the variability of the Indian Winter Monsoon in association with solar activity during Holocene. Monsoon reconstruction was based on trace elements and lanthanide geochemistry of lagoon sediments from south-eastern Sri Lanka.  A 5.1 m sediment core acquired from Pottuvil Lagoon was logged for concentrations of K, Rb, Mg, Al, Ti and rare earth elements at a 5cm interval using ICP-MS. The chronology of the core was established by Bacon 2.2 age-depth modelling based on calibrated AMS 14C dates. Reconstructed monsoon signal was compared with Holocene records of 14C and 10Be nuclide production rates which are considered as proxies for solar activity. Results revealed a distinct millennial scale variability of Indian Winter Monsoon during mid-late Holocene with three strong monsoon activity phases at 2553-2984 yrs BP, 3899-5021 yrs BP, and at 5244-5507 yrs BP. Further, the millennial-bands detected in Pottuvil monsoon record are closely matched with shifts in cosmogenic nuclide production rates, showing coherence with solar output. The existence of millennial scale variability is further reinforced by occurrence of dominant 1600 and 1000-year periodicities in Lomb-Scargle power spectra of element proxies. In particular, 1000-year periodic band is consistent with Eddy solar cycle. Thus, this study suggests a possible link to solar influence on millennial scale variability of Indian winter monsoon from mid to late Holocene.

How to cite: Premaratne, K. M. and Chandrajith, R.: Solar influence on Millennial-scale variability of Indian Winter Monsoon during mid-late Holocene: Evidence from coastal sediments from Southeastern Sri Lanka , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18843, https://doi.org/10.5194/egusphere-egu24-18843, 2024.

EGU24-19482 | ECS | Posters on site | CL1.1.5

Deciphering the Central African Copperbelt sedimentary succession: Chemostratigraphy of the Neoproterozoic metasedimentary sequences at Lubambe, Zambia 

Aileen Doran, Jon Stacey, Koen Torremans, Murray Hitzman, Victor Vincent, Laura Hepburn, and Adrian J. Boyce

A +1.6 km borehole, southeast of the Lubambe Copper Mine, Zambia has intersected a seemingly continuous sedimentary sequence spanning the Neoproterozoic Kantanga Supergroup sedimentary succession within the Central African Copperbelt. This extensive sequence encompasses the Mindola Clastics Formation of the Lower Roan Subgroup, through the Upper Roan Subgroup, and the lower Nguba Group (including the Grand Conglomérat of the Mwale Formation and overlying Kakontwe Limestone). Lithofacies and mineralogical studies of this drillcore have revealed numerous sedimentary cycles, with clear evidence for evaporite formation during sedimentation and diagenetic processes throughout (e.g., bedded/vein anhydrite, chicken-wire textures, relic cements & pseudomorphs). Siliciclastic red-bed lithologies at the base transition into repeated cycles of shales/siltstones-dolostone-evaporite, succeeded by deeper water carbonate and siltstone intervals. Diamictites of the Mwale Formation (Grand Conglomérat unit) cap these cycles at the base of Nguba Group, interbedded with several thick carbonate beds (peloidal grainstones, dolostones +/- bioherm textures).

To explore the Upper Roan to Nguba Group carbonate successions, detailed mineral chemistry mapping (Tescan TIGER MIRA3 FEG-SEM, µXRF, pXRF) and C-O isotopic analysis were undertaken, with a focus on understanding global trends associated with the onset of diamictite formation. Mineral chemistry analysis revealed the influence of post-depositional processes on the sequence, including dolomite and silica alteration. Silicification selectively preserved peloids above the first diamictite occurrence while the original carbonate matrix dissolved, with later cement formation (hydrothermal?) associated with elevated Mn-Fe relative to earlier carbonates. However, most of the carbonate units from the upper successions are composed of dolomite grains/cement, with original textures often preserved (e.g., stromatolites, disrupted reefs).

Isotope sampling targeted the ‘least-altered’ carbonates from the upper Roan to lower Nguba Group, to minimize post-depositional alternation effects. The initial analysis revealed variable δ13C isotopic values, with ~negative trending excursions below the main diamictite body. The lack of notable covariance with corresponding O isotope values suggests representation of the original seawater composition, not impacted by local diagenetic/hydrothermal alterations. Further, the largest negative excursion is associated with a lithofacies change from non-stromatolite- to stromatolite-bearing dolomitic siltstones, suggesting local lithofacies changes may influence the isotope profile. Specifically, δ13C isotopic values drop from ~+4.2 ‰ to +0.37 ‰, before returning to ~+4.7 ‰ below the diamictite contact. While these units do not record the more extreme negative excursion (<-5 ‰) typically associated with the Sturtian glaciation recorded elsewhere, the overall curve may represent the Islay anomaly recorded globally in Cryogenic sections beneath the Sturtian diamictite. This negative excursion, in line with global C isotope trends (<-5 ‰) has also been identified within Copperbelt on both the Zambian and Democratic Republic of Congo sides (ongoing work), but with a more significant decrease in C isotope values, in line with global trends. The lack of exact duplication may be the result of local sedimentological factors, as shown by the association in lithofacies variation, an incomplete sample record, or perhaps the influence of the Sturtian is not fully recorded in the stratigraphy underlying these diamictites.

How to cite: Doran, A., Stacey, J., Torremans, K., Hitzman, M., Vincent, V., Hepburn, L., and Boyce, A. J.: Deciphering the Central African Copperbelt sedimentary succession: Chemostratigraphy of the Neoproterozoic metasedimentary sequences at Lubambe, Zambia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19482, https://doi.org/10.5194/egusphere-egu24-19482, 2024.

EGU24-20288 | Posters virtual | CL1.1.5 | Highlight

From an Ocean-like to Methanogenesis-dominated carbon cycle in the Dziani Dzaha Lake 

Pierre Cadeau, Magali Ader, Pierre Cartigny, Ivan Jovovic, Pierre Adam, and Vincent Grossi

Over geological times, the evolution of carbon isotope composition of carbonates (δ13Ccarb) in the sedimentary record is punctuated by numerous positive isotopic excursions (CIEs), which reflect significant perturbations of the carbon cycle on Earth surface environments. Such isotopic events are mainly interpreted as a consequence of an increase of organic carbon burial in sediments. However, the significant spatial and temporal variability observed in many Proterozoic sedimentary successions recording positive CIEs still challenge this postulate. Among others, the potential influence of methanogenesis has been raised to explain at least a part of the variability observed during CIEs.

The Dziani Dzaha is a shallow tropical volcanic crater lake located on the Petite Terre Island of Mayotte (Comoros Archipelago, Indian Ocean). Its water most likely originate from the nearby ocean through bedrock seepage thanks to the fracturation associated with the phreatomagmatic eruption at that formed the crater 7 to 4 Kyr ago. Based on numerous analogies, this atypical modern lacustrine system was considered as an analogue of Proterozoic environments, and more specifically of those having recorded strongly positive δ13C values, such as for example the Lomagundi-Jatuli event. A previous study demonstrated the significant role of methane in the Dziani Dzaha carbon cycle through an intense organic matter degradation by methanogenesis associated with methane degassing into the atmosphere. Here, in order to investigate the processes responsible for the onset of this methanogenic activity, we present coupled C and S isotope records in a sediment core of the lake.

Based on geochemical and sedimentological evidences, four different units have been identified in the sediment core. From the bottom to the top, carbon and sulfur isotopic signatures in the first unit are similar to modern oceanic values (δ13Corg ~ -25‰, δ13Ccarb ~ 0‰ and δ34Spy ~ -20‰), which is consistent with a marine origin of the lake water. In the second unit, the δ34Spy increases progressively from -20‰ to -10‰ while the δ13C of organic and inorganic carbon remain constant, which is consistent with a progressive consumption of the sulfate pool through the degradation of organic matter by sulfatoreduction in a restricted environment. The δ34Spy shifts sharply to 35‰ at the transition with the third unit where it remains constant up to the top, while both organic and inorganic carbon isotopic signatures increase progressively from -25‰ to -14‰ and from 0‰ to almost 20‰, respectively. This turning point most likely results from a depletion of the initial sulfate pool to a point allowing part of the organic matter to be remineralized through methanogenesis with a degassing of methane into the atmosphere. These results highlight the potential of C-S-isotope coupling to identify a potential impact of methanogenesis on the carbon-isotope signatures observed in the sedimentary record through geological times.

How to cite: Cadeau, P., Ader, M., Cartigny, P., Jovovic, I., Adam, P., and Grossi, V.: From an Ocean-like to Methanogenesis-dominated carbon cycle in the Dziani Dzaha Lake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20288, https://doi.org/10.5194/egusphere-egu24-20288, 2024.

Reconstruction of the history of bottom-water redox conditions in the climatically sensitive Southern Ocean can provide comprehensive information regarding oceanic circulation, global carbon cycling, and global climate changes. Here we present high-resolution sedimentary redox records over the last ~35 ka in the deep Protector Basin (~4,100 m water depth) of the southern Scotia Sea. Sedimentary δ34S and redox-sensitive trace metals were comprehensively analyzed and compared with 230Th-normalized Ba- and opal-based export fluxes to constrain bottom-water or sedimentary redox and bottom-water oxygenation conditions. The results demonstrate tight coupling of redox state proxies (sulfur isotopes and trace metals) over the glacial–interglacial cycle; the presence of oxidizing conditions during glacial periods rapidly transitions to reducing conditions during interglacial periods. Our findings indicate that absolute control of sedimentary redox variability in the study area involves climate-forced primary production, rather than the deep circulation and ventilation dynamics previously highlighted in the Antarctic Zone. Signs of climate-driven redox changes are also evident in two episodic cold events superimposed on the warm Holocene climate. The glacial–interglacial pattern of redox changes observed in this study contrasts with previous observations in the Southern Ocean, including the Antarctic Zone, suggesting spatial heterogeneity of bottom-water and sediment conditions during orbital-scale climate cycles. This study may help to elucidate paleoenvironmental changes in the Southern Ocean, such as changes in the dynamics of Antarctic Bottom Water production and Holocene climate instability.

How to cite: Kim, J., Lim, D., and Yoo, K.: Climate-driven redox changes in the Antarctic region: New insights from sedimentary sulfur isotopes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21485, https://doi.org/10.5194/egusphere-egu24-21485, 2024.

EGU24-547 | ECS | Posters on site | BG5.3

Revisiting depositional models for the Ediacara Member of the Rawnsley Quartzite in South Australia 

Karol Faehnrich, Diego C. García-Bellido, Mary L. Droser, and Robert R. Gaines

The Ediacara Member of the Rawnsley Quartzite hosts one of the best preserved and most diverse assemblages of the Ediacara Biota. In it, soft-bodied organisms are preserved across various depositional environments, with a proposed connection between sedimentary facies and fossil assemblages. Recent studies have questioned previously-established facies models, undermining links between paleoenvironment, paleoecology, and taphonomy. Here, we revisit these models using field observations from across the central Flinders Ranges, supplemented by two new cores drilled through the Ediacara Member at the Nilpena fossil site. The two drill sites are 2 km apart and span strata from the top of the underlying Chace Member through the overlying fossiliferous facies of the Ediacara Member. These two cores are easily correlated to surface outcrops and provide the most complete record of the deposition of the Ediacara Member thus far. The core drilled at “One Tree Hill” (OTH-1) reaches a depth of 65 m and records characteristic “petee laminations” below the erosional contact with the Ediacara Member, which is marked by a breccia horizon. The basal breccia of the Ediacara Member gradationally passes into thinly laminated planar to slightly wavy siltstone that then transitions into alternating thin beds of siltstone and thick beds of massive sandstone often affected by soft-sediment deformation. These beds grade into wavy-laminated siltstone interbedded with thin beds of arenite. Forming the top of the core are thick beds of massive arenite. The second drill core (MR-1) spanning 75.8 m records analogous facies with changing thickness and siltstone/sandstone ratio but lacks a breccia horizon at the base of the Ediacara Member. Both cores highlight repeated cycles of alternating deposition of sandstone and siltstone often obscured in the surface exposure. We investigate an array of sedimentary structures observed in the cores and surface exposures in thin sections, exploring the role of microbial matgrounds and silica cementation in sediment binding and transport. Both are critical for any depositional model developed for the Ediacara Member across the Nilpena site and central Flinders Ranges, its accumulation rate, sediment sources and potential triggers for repeated channelized flows observed throughout the unit. A unified depositional model built across this basin will be critical to further untangle the complex interplay between time, changing taxonomic diversity, water depth, and paleoenvironment at the dawn of animal life.

How to cite: Faehnrich, K., García-Bellido, D. C., Droser, M. L., and Gaines, R. R.: Revisiting depositional models for the Ediacara Member of the Rawnsley Quartzite in South Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-547, https://doi.org/10.5194/egusphere-egu24-547, 2024.

EGU24-620 | ECS | Orals | BG5.3

Numerical modelling of magmatic CO2 emissions from the Neo-Tethyan margin during the Early Cenozoic 

Bram Vaes, Pietro Sternai, Léa Ostorero, Luca Castrogiovanni, Christopher Gonzalez, and Yannick Donnadieu

Identifying the geological drivers of long-term climate change is key to improve our understanding of the interactions between the deep Earth and the Earth’s surface. Long-term Cenozoic climate cooling has been largely attributed to an increase in atmospheric carbon consumption by enhanced silicate weathering linked to the uplift of the Tethyan orogenic belt. Alternatively, this cooling trend has been explained by decreasing magmatic CO2 outgassing during the progressive closure of Neo-Tethys Ocean. However, the outgassing rates associated with Neo-Tethyan magmatism remain poorly constrained, making it difficult to assess its contribution to Cenozoic climate change. Here, we present the first results of numerical geodynamic experiments aimed at obtaining improved quantitative estimates of the magmatic CO2 outflux along the Neo-Tethyan margins. To this end, we use 2D numerical petrological-thermomechanical models of oceanic subduction and continental collision that account for partial melting and slab decarbonation. Calibrating these numerical experiments on available geological constraints from the Neo-Tethyan margin, we estimate the Neo-Tethyan magma production volumes through the Early Cenozoic. We discuss how these results are sensitive to changes in model setup and input parameters such as convergence rates, rheology, and crustal composition. To quantify the time-dependent magmatic CO2 emissions, we combine the magma production histories with both modelling- and observation-based quantifications of the volatile contents of pre- and post-eruptive igneous rocks. Finally, we discuss the potential Neo-Tethyan magmatic forcing of Early Cenozoic climate change in light of our new results and its implications for the global carbon cycle and surface-deep Earth feedbacks.

How to cite: Vaes, B., Sternai, P., Ostorero, L., Castrogiovanni, L., Gonzalez, C., and Donnadieu, Y.: Numerical modelling of magmatic CO2 emissions from the Neo-Tethyan margin during the Early Cenozoic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-620, https://doi.org/10.5194/egusphere-egu24-620, 2024.

The Permian section of the Paraná-Etendeka basin is represented by the Palermo and Irati formations, comprising a shallow sea that occupied ca. 5 million km2 of southern Gondwana before completely drying out around 277 million years ago (Irati-Whitehill ocean). This is broadly coincident with the uprising of the Cape Fold Belt of southern Africa and the San Rafael orogeny of the paleo-Pacific margin of South America, leading to the interpretation that basin restriction and the major ecosystem changes that followed were ultimately caused by uprising of mountainous domains surrounding the shallow sea. We combine new iron speciation, organic carbon isotope and trace element data with previous biomarker, organic carbon and nitrogen isotope data to unravel the biogeochemical and redox changes during this transition from an open marine realm to a restricted setting, and to test the hypothesis of external controls on the biogeochemical cycles of southern Gondwana. Mudstones and shales of the Palermo Formation yielded FeHR/FeT around or below 0.2, suggesting oxic bottom water conditions, reinforced by muted redox-sensitive element (RSE) concentrations and overall low Total Organic Carbon (TOC) contents, with δ13Corg around -25‰. Black shales of the overlying Irati Formation, on the other hand, record an abrupt shift to anoxic conditions, with FeHR/FeT between 0.3 and 0.9, representing mostly ferruginous conditions with sporadic euxinic incursions (FePy/FeHR > 0.8), higher concentrations of RSE such as Mo, higher TOC contents and d13Corg rapidly oscillating from ca. -29 up to ca. -19‰. The euxinic intervals are associated with the Assistência Member, containing tephra layers dated at 277 Ma and thus coeval to the Cape and San Rafael orogenies. Our results reinforce the hypothesis of mountain belt formation as the main external driver of biogeochemical changes, leading to toxic conditions for complex life forms in the Permian internal basins and to the accumulation of important organic-rich source rocks in the shallow seas of southern Gondwana.

How to cite: Caxito, F., Sperling, E., Bastos, L., and Pereira, E.: Anoxia in the Permian Irati-Whitehill Ocean of southern Gondwana: A possible link with uprising of the Cape and San Rafael mountain belts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1345, https://doi.org/10.5194/egusphere-egu24-1345, 2024.

EGU24-1446 | Orals | BG5.3

Plant diversification is associated with habitat disruption in the transient Hengduan Mountains 

Yaquan Chang, Wenna Ding, Junqing He, Sean Willett, Katrina Gelwick, Niklaus Zimmermann, and Loic Pellissier

Mountain regions harbor disproportionally high biodiversity levels on Earth, which can hardly be explained solely by contemporary climate and heterogeneity. The complex interactions between the geological and climate dynamics in the mountain system could provide a unique substrate for species to diversify, leading both to higher diversity and higher endemism in the mountains. The Hengduan Mountains region is a unique biodiversity hotspot outside of the tropics. It is characterized by complex geological and climate histories associated with the Indian-Eurasia plate collision and monsoon intensification shaping intense geomorphic processes. These unique and complex histories are expected to have shaped landscapes across millions of years, fostering the emergence of lineages. Using the clade level of phylogenies and species range maps, we generated the spatial pattern of diversification rate for 33 highly diversified clades in the Hengduan Mountains. These spatial clade diversification rate patterns are spatially associated with active deformation history in the past 15 Ma. In this talk, I will present hotspots of diversification rate and potential linkage to geological and climate processes. I will demonstrate that the diversification rate hotspots are concentrated in the Three Rivers Region, Dadu River, and Shangri-La Plateau in the Hengduan Mountains. Then I will show the elevational gradient of the diversification rate within these hotspots and link them to specific geological processes. Specifically, long-term erosion from low-temperature thermochronology indicates the deformation process in the recent 15 Ma associated with new habitat and high diversification speciation process in the Three Rivers region and Dadu River in the Hengduan Mountains. Moreover, the landscape transience characterized by divides migration and low relief surface formation may create habitat disruption and range fragmentation to increase allopatric speciation. Taken together, the high plant diversity of Hengduan Mountain may be caused by intense focalized geological processes generating new species from habitat disruption.

How to cite: Chang, Y., Ding, W., He, J., Willett, S., Gelwick, K., Zimmermann, N., and Pellissier, L.: Plant diversification is associated with habitat disruption in the transient Hengduan Mountains, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1446, https://doi.org/10.5194/egusphere-egu24-1446, 2024.

EGU24-3508 | ECS | Posters on site | BG5.3

Geogenomics and biogeodynamics in the Northern Apennines and Ligurian Alps (Italy)  

Gabrielle Vance, Dominik Kirschner, Sean D. Willett, and Loïc Pellissier

Complex interactions between tectonics and surface processes influence the evolution of aquatic species across orogens. These processes are likely to be important in tectonically active areas where faulting and uplift lead to drainage reorganization. The Northern Apennines are an active orogenic wedge, where horizontal shortening and topographic advection lead to river capture and drainage divide migration, which can separate or connect ecological domains and thus isolate or mix aquatic populations. In contrast, the adjacent Ligurian Alps are a remnant of the Alpine orogen with little modern deformation. In this study, we combine geomorphic analysis with environmental DNA (eDNA) collected from rivers in the Northern Apennines and Ligurian Alps to assess the influence of tectonic advection and subsequent drainage reorganization on the genetic diversity of native freshwater fish. Geomorphic metrics are asymmetric across the main drainage divide (MDD) in both orogens, and divide asymmetry indices based on these metrics suggest an MDD migration direction from Ligurian (coast) to Adriatic (Po Plain), accompanied by river captures. In the Northern Apennines, this suggested drainage divide migration direction is towards the NE, opposite that of the tectonic advection of topography. Geomorphic metrics show greater contrast across the MDD in the Northern Apennines than in the Ligurian Alps. Five native freshwater fish species show statistically significant correlations between genetic distance and divide asymmetry indices across the MDD. Genetic distance is greater across the MDD in the Northern Apennines than in the Ligurian Alps. Endemic species such as Telestes muticellus exhibit greater amplicon sequence variant (ASV) richness on the Ligurian than the Adriatic side of the MDD in both orogens; greater ASV richness in the Northern Apennines than in the Ligurian Alps; and greater ASV richness on the retrowedge of the Northern Apennines than on the prowedge.  Tectonically driven drainage reorganization may promote greater genetic diversity in coastal basins, although we can not rule out anthropogenic population transfer in some cases.

How to cite: Vance, G., Kirschner, D., Willett, S. D., and Pellissier, L.: Geogenomics and biogeodynamics in the Northern Apennines and Ligurian Alps (Italy) , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3508, https://doi.org/10.5194/egusphere-egu24-3508, 2024.

EGU24-4614 | Orals | BG5.3

Greenalite provides a snapshot of metal availability in an Archean shelf environment. 

Rosalie Tostevin, Ansahmbom Y. Nke, Harilaos Tsikos, Xolane Mhlanga, and Paul R. D. Mason

Thermodynamic models predict that marine metal availability has changed over geological time, particularly in the Archean Eon (4.0 – 2.5 billion years ago), when seawater was anoxic and Fe2+-rich. Since metals are essential micronutrients required to build metalloproteins, changes in metal availability in seawater would have influenced evolving microbial ecosystems. Recent work on Archean rocks has highlighted the role of greenalite as an abundant, primary precipitate in Archean seawater, and its potential as a faithful geochemical archive. Greenalite can be exceptionally well preserved in early diagenetic chert, providing protection from diagenesis and metamorphic alteration. Furthermore, experimental work has demonstrated that several key metals enter the greenalite precursor phase during precipitation, and the associated partition coefficients are consistent under a range of conditions. Furthermore, most metals are retained in the structure during heating and crystallisation, suggesting that greenalite could represent a robust archive of the metal content of early oceans. Here, we present mineral-specific laser ablation ICP-MS data for natural greenalite from the ~2.5 Ga Transvaal Supergroup, South Africa. Petrographic relationships and rare earth element patterns suggest this greenalite precipitated from seawater in a shelf environment. We place metal abundance into a quantitative framework to predict metal availability in Archean seawater. Our calculations suggest that V and Zn were depleted, Ni was similar, Co was enriched, and Mn was super-enriched in this setting compared to modern marine environments. These results are consistent with predictions based on marine chemistry and proteomics, as well as some bulk geochemical records.

How to cite: Tostevin, R., Nke, A. Y., Tsikos, H., Mhlanga, X., and Mason, P. R. D.: Greenalite provides a snapshot of metal availability in an Archean shelf environment., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4614, https://doi.org/10.5194/egusphere-egu24-4614, 2024.

Evidence for the co-evolution of Earth and life is abundantly preserved in the minerals, which are the oldest objects you can hold in your hand. Each information-rich specimen is a time capsule waiting to be opened and to tell the stories of Earth and other worlds. The emerging field of “mineral evolution” considers changes in the diversity and distribution of minerals through billions of years of planetary history [1-5], and reveals dramatic episodes of the co-evolution of minerals and life, including stages of life's origins, microbial biomineralization, influences of global oxygenation, and the rise of the terrestrial biosphere. 

Traditional approaches to classifying minerals ignore this history. The International Mineralogical Association (IMA) has catalogued >6000 mineral species, each with a unique combination of idealized chemical composition and crystal structure. This essential scheme allows the confident identification of different condensed crystalline building blocks of planets and moons. However, lacking perspectives of time and process, this system is limited in its ability to address the evolution of planets, much less the co-evolution of the geosphere and biosphere.

We have introduced, and are now completing, a new complementary approach to mineral classification called the “evolutionary system of mineralogy.” Our system differs from IMA's in three ways. First, it splits IMA species that form in more than one way; for example, pyrite forms by both abiotic and microbial processes. Second, it lumps IMA species that form continuous solid solutions through the same process; i.e., we lump many different species of the tourmaline group into a single kind. Third, we include varied amorphous or poorly crystalline solids, such as obsidian, kerogen, and limonite, which are important in crustal processes and were included in mineral inventories before the application of x-ray diffraction.

The resulting evolutionary system of mineralogy is being released in 12 parts, 8 of which are now published or in press [6-13]. These works underscore the close connections between mineral and biological evolution. We find that while minerals played key roles in life’s origins and evolution, life changed near-surface environments in ways that led to the formation of approximately half of all known mineral species, most of which are only known to form through biological mediation.

References: 1. Hazen R.M. et al. (2008) Am.Min., 93, 1693-1720; 2. Hazen R. & Morrison S. (2022) Am.Min., 107, 1262-1287; 3. Hazen, R. et al. (2023) In: Bindi and Cruciani [Eds.], Celebrating the International Year of Mineralogy. NY: Springer, pp.15-37; 4. Hazen R. et al. (2023) JGR Planets, 128, e2023JE007865; 5. Hazen R. et al. (2022) Am.Min., 107, 1288-1301; 6. Hazen R. (2019) Am.Min., 104, 468-470; 7. Hazen R. & Morrison S. (2020) Min., 105, 627-651; 8. Morrison S. & Hazen R. (2020) Am.Min., 105, 1508-1535; 9. Hazen R. et al. (2021) Am.Min., 106, 325-350; 10. Morrison S. & Hazen R. (2021) Am.Min., 106, 730-761; 11. Hazen R. & Morrison S. (2021) Am.Min., 106, 1388-1419; 12. Morison S. et al. (2023) Am.Min., 108, 42-58; 13. Hazen R. et al. (2023) Am.Min., 108, 1620-1641; 14. Morrison et al. (2024) Am.Min., 109, in press.

How to cite: Hazen, R.: Documenting the Co-Evolution of Earth and Life: A Mineral Evolution Approach , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4723, https://doi.org/10.5194/egusphere-egu24-4723, 2024.

EGU24-5478 | ECS | Posters on site | BG5.3

Towards integrated models of mantle convection, surface dynamics and climate evolution  

Niklas Werner, Christian Verard, Maura Brunetti, Paul Tackley, and Taras Gerya

The long-term evolution of the biosphere on Earth is tightly coupled to changes in the geosphere and climate. Investigating the evolution of Earth’s climate over the course of the Phanerozoic and beyond requires extensive numerical modelling efforts. Classically, this has been done using Earth System Models of varying complexity. While these models are well-suited to simulate a majority of processes in the ocean, the atmosphere and on the land surface, they lack a key component of the Earth system ―  the interior. Processes in the mantle drive plate tectonics on Earth and by means of degassing are a key factor in determining the atmospheric CO2 concentration, influencing biological evolution. Both, the position of continents as dictated by plate tectonics as well as the concentration of greenhouse gases in the atmosphere are known to be crucial in shaping Earth’s climate. An important suite of mechanisms that influences both climate and mantle can be found in silicate weathering, the erosion of weathered material and its transport and sedimentation in subduction zones. The influx of sediments into subduction zones has been shown to alter the rheology of the subduction slab, influencing the speed of subduction and chemistry of the slab and thereby impacting mantle convection processes (e.g. Bello et al., 2015). Here, we present a framework for coupling the new PANALESIS paleogeographic reconstruction (Vérard, 2019) to an Earth System Model of Intermediate Complexity (EMIC) and the mantle convection model with plate tectonics based on StagYY code. This is done using climate output from the EMIC to force a landscape evolution model that is used to compute sediment influx into subduction zones. Degassing rates obtained from the mantle convection simulations are then used to assess atmospheric CO2 levels and create climate lookup tables for different degassing scenarios. These data can then be used to force a temporally continuous carbon cycle model to update previous pCO2 curves for the Phanerozoic and beyond. Given the new paleogeographic reconstruction and the more sophisticated modelling framework, this approach may give new insights into the long-term interactions between mantle and climate and the consequences for biological evolution.

References

Bello, L., Coltice, N., Tackley, P. J., Müller, R. D., & Cannon, J. (2015). Assessing the role of slab rheology in coupled plate-mantle convection models. Earth and Planetary Science Letters, 430, 191-201.

Vérard, C. (2019). PANALESIS: Towards global synthetic palaeogeographies using integration and coupling of manifold models. Geological Magazine, 156(2), 320-330.

How to cite: Werner, N., Verard, C., Brunetti, M., Tackley, P., and Gerya, T.: Towards integrated models of mantle convection, surface dynamics and climate evolution , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5478, https://doi.org/10.5194/egusphere-egu24-5478, 2024.

EGU24-5524 | ECS | Posters on site | BG5.3

Whence the demise and fall of the RNA World? 

Anna Medvegy and Stephen Mojzsis

A widely promulgated concept for the fundamental ancestor-descendent relationship at life’s origin, and thus the onset of Darwinian evolution, is the RNA World hypothesis. If Darwinian evolution on Earth began with a simple RNA molecule which had the ability to replicate itself, in the long run this must have given way to DNA perhaps via an intermediate RNA(±Peptide) World. This could happen once DNA appeared and became the preferred informational molecule for all extant biology. Yet, making sense of this transition is confounded both by the intervening 4 billion years of biological evolution, and a scarce ancient (pre-3.2 Gyr) geologic record. Here, we explore whether the relative instability of RNA to thermal stresses, salt content, pH, variable UV sensitivity and an overall narrow available suite of metabolic styles, strictly limited the range of suitable habitats for RNA World organisms; they were susceptible to marginalization, assimilation and effective extinction. We propose that main factors responsible for the transition from the RNA±Peptide to DNA+Peptide World included (i) overall changes in the geosphere (e.g. heat flow, crustal type, nutrient availability); (ii) transient global heating of the hydrosphere by late accretion bombardment viz. “thermal bottlenecks”; and, (iii) competition from, and perhaps predation by, metabolically diverse and genomically nimble emergent DNA+Peptide organisms. 

How to cite: Medvegy, A. and Mojzsis, S.: Whence the demise and fall of the RNA World?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5524, https://doi.org/10.5194/egusphere-egu24-5524, 2024.

Plants have been a key interface in the global carbon and water cycles for nearly 475 million years. The magnitude of vegetational effects has waxed and waned dynamically because plant abundance and community composition have changed over time. Unravelling how plant communities have shaped, and been shaped by, global biogeochemical cycles relies upon reconstructing the paleoecology and paleoecophysiology of plants, and this process can be challenging in deep time, when plant communities contained organisms with traits that are rare in—or absent from—present-day ecosystems. Fortunately, the archive of how plants have shaped and responded to environmental change is preserved in the fossil record, because the traits and properties of extinct plants can be interpreted from fossilized anatomy in a qualitative, semi-quantitative, and quantitative way. Traits related to water transport in plants. including drought resistance and hydraulic supply to leaves, are particularly useful and important because these traits link individual plant performance to the water and carbon cycles.

The collapse of tropical everwet rainforests end of the Carboniferous Period (~300 Ma) provides an illustration of how plant water transport traits influenced, and were shaped by, the water and carbon cycles. These traits are quantified by combining mathematical models of stem hydraulic conductivity and drought resistance with anatomical measurements from scanning electron and light microscopy images of fossilized plant water transport cells, called xylem. Analysis of stem hydraulic traits in five lineages of extinct Carboniferous plants—arborescent lycophytes, stem group seed plants, stem group tree ferns, coniferophytes, and sphenophytes—reveals differential hydraulic capacity and drought resistance among these plants, despite their simultaneous presence in tropical everwet ecosystems. Significant differences in these two traits are not only present between these five lineages, but can also be observed within several of these plant groups: for example, key parameters may vary by more than an order of magnitude in related plants. High hydraulic capacity and low drought resistance traits were associated with a decline in relative abundance toward the close of the Carboniferous Period, whereas plants with lower hydraulic capacity and higher drought resistance traits increased in relative abundance and survived this floral transition. This change in relative abundance within these communities shaped the hydrologic and carbon cycles which, in turn, amplified environmental stress that, consequently, further altered plant community composition. Implementing this analysis in trait-aware paleoecosystem models illustrates the effect of plant traits on global environments, and vice versa, yielding insight into plant performance during extreme environmental change that is analogous to anthropogenic impacts predicted for the late 21st century and beyond.

How to cite: Wilson, J.: Plant paleoecophysiology traits in deep time: hydraulic conductivity and drought resistance in late Carboniferous Period plants, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6891, https://doi.org/10.5194/egusphere-egu24-6891, 2024.

EGU24-7442 | Orals | BG5.3

Functional traits and trait diversity of leaves: palaeoecological perspectives 

Anita Roth-Nebelsick and Christopher Traiser

Functional traits were originally defined as any characteristic of an organism that contributes to fitness. From this autecological perspective, trait-based research has considerably expanded into approaches of ecosystem analysis that also have high potential for palaeoecological research. In the ecosystem context, the meaning of “trait” has become much broader, encompassing all sorts of measurable quantities carrying ecological information that are themselves categorized into different “trait classes”. For instance, “response traits” are organismal traits responding to environmental parameters whereas “effect traits” act upon the environment.

As primary producers, plants represent a crucial part of ecosystem functioning. Basic ecophysiological processes of plants, particularly gas exchange and photosynthesis, are key elements in the carbon and water cycle and can thereby be understood as “effect traits”. Fossil anatomical traits, such as from fossil leaves, allow for deriving basic ecophysiological parameters from physical laws (such as calculating leaf gas conductance from the diffusion equation). Biochemical parameters, however, are not provided by fossil material and require therefore estimation based on extant plants (such as kinetic properties of the enzyme apparatus of photosynthesis) which adds a certain error margin to the results. Nevertheless, these “mixed” approaches to fossil plant ecophysiology allow for obtaining crucial benchmark data on various ecosystem characteristics, such as primary productivity or evapotranspiration.

            Another branch of trait-based ecosystem research is the study of functional diversity which can be roughly described as the richness and distribution of functions expressed by organisms coexisting within a habitat. Functional diversity is less frequently considered for fossil vegetation compared to the study of autecological effect traits. One reason may be that various approaches for studying extant functional diversity are difficult or even impossible to apply to fossil plants, requiring the development of novel methods suitable for fossil remains.

As a recent example, the Shannon Diversity of leaf architecture based on functional leaf traits identifiable from fossil leaf material was shown to be related to environmental parameters for extant as well as fossil angiosperms.  Devising trait-based approaches to functional diversity suitable for fossil organisms can offer additional fruitful research perspectives for studying environments of the past.

How to cite: Roth-Nebelsick, A. and Traiser, C.: Functional traits and trait diversity of leaves: palaeoecological perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7442, https://doi.org/10.5194/egusphere-egu24-7442, 2024.

EGU24-8733 | Orals | BG5.3

Biogeodynamics of narrow orogenic arcs and their biodiversity hotspots 

Guillermo Booth Rea, Paloma Mas Peinado, Jorge Pedro Galve, Octavio Jiménez Robles, and Jose Miguel Azañón

Narrow Orogenic Arcs (NOA) on Earth are oftenly biodiversity hotspots, where biogeographic evolution is influenced by tectonic forcing. However, the relationships between tectonic mechanisms intrinsic to NOA, landscape evolution and speciation forming biodiversity hotspots have not been dwelt with. Different mechanisms inherent to NOA, such as slab roll back, slab tearing, edge delamination, mantle upwelling and flow around subducted slabs, basin and archipelago migration and volcanic arc growth drive a dynamic landscape evolution that fosters processes of dispersal and allopatric-speciation. Here, we show this with examples from the Western Mediterranean and Caribbean. Slab tearing drives migrating waves of tectonic uplift and subsidence at the edges of orogenic arcs, coupled with crustal thickening followed by heterogeneous extension, forming endorheic basins and marine gateways among high-elevation ranges. Furthermore, vicariant events by isolation in high-elevation mountain ranges, internal drainage basins, stranded back-arc and volcanic arc archipelagos- seem to have driven the distribution and diversification of many taxa. Dispersal events would have been promoted by- drifting forearc archipelagos, changes of river courses (captures) and land bridges between continents, where ancient lineage dispersal followed by allopatric speciation-multiple diversification resulted in the current complex biological assemblages. The characteristic time and space migration of NOA, fosters recurrent processes of dispersal and vicariance, including in situ diversification through time. In this setting, long-time emerged parts of both drifting-forearc or stranded-backarc archipelagos represent both refuge and diversification centers where insular fauna may relate to distant, previously- attached land masses or islands. This is the case of drifting islands like the late Miocene Alboran archipelago in the Gibraltar arc or the Present Margarita island in the Caribbean, bearing biota with most common recent ancestors in the Balearic islands or the Central Coastal Range of Venezuela, respectively. Insular lineages may disperse by the closure of marine gateways between the mainland continents and drifting archipelagos, a process that may also drive the isolation of confined seaways, like the Mediterranean during the Messinian Salinity Crisis. Topographic uplift closing marine gateways or restricting seaways may occur by lithospheric rejuvenation, following delamination or detachment of subducted subcontinental mantle slabs and also by the growth of a volcanic arc. The emergence of new land and islands in the forearc domain, results in speciation and less species-rich communities in the direction of slab retreat. 

How to cite: Booth Rea, G., Mas Peinado, P., Galve, J. P., Jiménez Robles, O., and Azañón, J. M.: Biogeodynamics of narrow orogenic arcs and their biodiversity hotspots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8733, https://doi.org/10.5194/egusphere-egu24-8733, 2024.

EGU24-9713 | Orals | BG5.3

Primary producers during the early Earth  

Patricia Sanchez-Baracaldo

Primary producers convert light energy from the sun into chemical energy in the form of sugars, a fundamental process that has enabled life on Earth. Once ancestral cyanobacteria evolved, they played a crucial role in Earth's history by facilitating the rise of atmospheric oxygen, paving the way for the development of complex life forms. Despite its significance, the origins of photosynthesis are still not fully understood. During the talk, I will highlight key evolutionary events in the history of Cyanobacteria: 1) the Archean origin of PSII,  photochemical reaction centre that catalyses the light-driven oxidation of water to molecular oxygen; 2) the emergence of the crown group of Cyanobacteria; 3) the appearance of filamentous forms around the Great Oxidation Event at 2.32 Ga; and 4) the late emergence of marine planktonic groups between 800-600 Mya. Molecular evolution analyses reveal a significant time gap between the Archean origin of oxygenic photosynthesis and the appearance of planktonic forms at the end of the Precambrian era. By studying the 'genomic record,' we can now unravel how oxygenic phototrophs co-evolved with the Earth's biosphere, contributing to the habitability of our planet.

How to cite: Sanchez-Baracaldo, P.: Primary producers during the early Earth , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9713, https://doi.org/10.5194/egusphere-egu24-9713, 2024.

EGU24-10412 | ECS | Orals | BG5.3

Escarpment Retreat Drives Diversification of Eastern Madagascar through Allopatric Speciation 

Yanyan Wang, Sean Willett, Yi Liu, Loïc Pellissier, and Niklaus Zimmerman

Madagascar, as a biodiversity hotspot on Earth, exhibits a high level of endemism as observed from the prevalent vicariant speciation of terrestrial mammals, amphibians, and flora. Species richness of the island is uneven, with the highest species richness and endemism found on the steep great escarpment of the eastern margin. The unevenness is further observed within the escarpment region in that phylogenic turnover shows both latitudinal and altitudinal variations. Madagascar has remained almost tectonically inactive since the last rifting with Seychelles-India in the late Cretaceous. The high diversity and endemism of Madagascar challenge the conventional notion of uplift-driven speciation, which argues that speciation is driven by the formation of diverse habitat types from tectonic uplift.

Although the fundamental topographic framework of Madagascar has been in place since the late Cretaceous, it is modified in the Cenozoic by multiple processes including island-wide mantle-driven dynamic uplift, erosion-driven landward retreat of the escarpment at the eastern margin, localized volcanic and faulting activities. Our topographic reconstruction reveals that the dominant correlation is between the escarpment and species richness. To investigate the causal mechanisms of the diversity at the eastern escarpment, we constructed landscape evolution models, tracing the dynamics of habitable land surface patches throughout model simulations.

We investigated two distinct landscape scenarios: an escarpment retreat model simulating river incision into a pre-existing plateau with negligible tectonic uplift, and a tectonic uplift model featuring spatially and temporally constant uplift with river incision into the resulting mountain range. The steady-state topographic height of the tectonic uplift model is calibrated to match the plateau elevation of the escarpment model to ensure the same number of habitat types between models. The landscape of a great escarpment is highly dynamic and the heterogenous retreat of the escarpment and the water divide makes the geographically isolated drainage basins expand landward at different rates during the retreat process. Within the escarpment region, habitat patches dynamically appear, disappear, fragment, or merge at a frequency that scales with the retreat rate. In contrast, the tectonic uplift model only exhibits similar dynamic landscape change during the transient phase with habitat patches stabilizing spatially and temporally once a steady state topography was achieved.

The models predict that escarpment retreat fosters habitat patch dynamics such that patches isolate, or reconnect with a frequency on the order of a million years, appropriate for allopatric speciation. The habitat patch dynamics are a consequence of processes of catchment expansion, river captures, isolation of highland remnants, and formation of topographic barriers during the retreat. We conclude that the spatially heterogeneous but temporally steady retreat of the Madagascar escarpment since rifting has sustained allopatric speciation over evolutionary timescales resulting in the observed high diversity and its spatial pattern of eastern Madagascar.

How to cite: Wang, Y., Willett, S., Liu, Y., Pellissier, L., and Zimmerman, N.: Escarpment Retreat Drives Diversification of Eastern Madagascar through Allopatric Speciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10412, https://doi.org/10.5194/egusphere-egu24-10412, 2024.

EGU24-10608 | Orals | BG5.3

On the time and space scales of geological, climatic, and biological changes 

Laurent Husson, Manon Lorcery, and Tristan Salles


It is commonplace to claim that the geo-, atmo-, and bio- spheres of the Earth are coupled, or that biodiversity depends on their interplays, but the implicit hypothesis on the time and space scales at which coupling holds are seldom envisioned. For instance, "deep time" is a convenient shortcut that loosely conveys the ideas of steady state and large spatial scales, but what are the limits? Observations often fall short because the geological record is fragmentary, but also because it is uncommon to access crucial informations such as rates of speciation, extinction, or migration. Recent advances in numerical landscape evolution models permit to explore the dynamic equilibrium between the spheres of the Earth. Based on a few examples at different time and space scales, we will browse settings where steady state holds (where biodiversity depends on the instantaneous states of the geology and climate, as for instance set by the Wilson cycle), where transient state prevails (where considering the time derivative of their states is needed, as for instance when the pace of landscape reshaping promotes biodiversification), and where dynamic equilibrium breaks down in some sort of metastable situations (as in the press-pulse theory that well applies to the mass extinction events). 

How to cite: Husson, L., Lorcery, M., and Salles, T.: On the time and space scales of geological, climatic, and biological changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10608, https://doi.org/10.5194/egusphere-egu24-10608, 2024.

EGU24-12430 | Posters on site | BG5.3

Tectonic “quakes”, scaling and the turbulence of solids 

Shaun Lovejoy, Andrej Spiridonov, and Lauras Balakauskas

Over thirty years ago, Y. Kagan proposed that seismicity is “the turbulence of solids”.  Indeed, fluid turbulence and seismicity have many common features: they are both highly nonlinear with huge numbers of degrees of freedom.  Beyond that, Kagan recognized that they are both riddled with scaling laws in space and in time as well as displaying power law extreme variability and – we could add – multifractal statistics.

Kagan was referring to seismicity as usually conceived, as a sudden rupture process  occurring over very short time periods.  We argue that even at million year time scales, that the movement of tectonic plates is “quake-like” and is quantitatively close to seismicity, yet caused by relatively smooth mantle convection fluid. 

To demonstrate this, we analyse the GPlates data base of 1000 point trajectories over the last 200 Myrs, analyzing the statistics of the dynamically important vector velocity differences where Dr is the great circle distance between two points and Dt is the corresponding time lag.  The longitudinal and transverse velocity components are analysed separately.  The longitudinal scaling of the mean longitudinal difference follows the scaling law <Dv(Dr)> ≈ Dr^H with H close to the theoretically predicted value  H = 1.  This high value implies that  mean fluctuations vary relatively smoothly with distance.  Yet at the same time,  the intermittency exponent C1 is extremely high (C1 ≈ 0.5) implying that from time to time there are enormous “jumps” in velocity. For comparison, laminar (nonturbulent) flow has H = 1 and is not intermittent (C1 = 0), fully developed isotropic fluid turbulence has the (less smooth) value H = 1/3 (Kolmolgorov) but with non-negligible intermittency C1 ≈ 0.07 and seismicity has very large C1 ≈ 1.3.  Our study thus quantitatively shows how smooth fluid-like behaviour can co-exist with highly intermittent quake-like behaviour.

We find that the outer spatial scale is near the size of the Earth (≈15000km) whereas the outer time scale is ≈60Myrs.  We show that the statistics are multifractal with a very large intermittency parameter that is close to that of seismicity determined at sub-decadal time scales.  The transverse scale function is the 2/3 power of the longitudinal scale function,  the transverse intermittency exponent (C1 ) is reduced by this factor.  The temporal scaling of the mean fluctuations of both the longitudinal and transverse components is close to a ½ power of the time lag: Dr≈Dt^(1/2).  However since the spatial scaling of the longitudinal and transverse components are different, we obtain two somewhat different space-time diagrams.  We link the parameter estimates to fundamental mantle convection parameters, and we make corresponding multifractal simulations.

Finally, we discuss the implications for the megaclimate regime, including macro-evolution. Both megaclimate and macroevolution of global diversity are scaling processes with H>0 characterized by intermittent — climate “events”, such as P-Tr hyperthermal, in the case of former, and mass extinctions and originations in the case of latter. The tectonic scaling, and the extreme multifractal behavior grounds both—the long-term climate, and the biological evolution on the first principles of scaling in macroscopic physical systems.

How to cite: Lovejoy, S., Spiridonov, A., and Balakauskas, L.: Tectonic “quakes”, scaling and the turbulence of solids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12430, https://doi.org/10.5194/egusphere-egu24-12430, 2024.

EGU24-12706 | Orals | BG5.3

Ediacaran ultra-weak geomagnetic field, oxygen rise, and the diversification of macroscopic animals 

Rory Cottrell, John Tarduno, Wentao Huang, Shuhai Xiao, Eric Blackman, Tinghong Zhou, Jack Schneider, Richard Bono, and Mauricio Ibañez-Mejia

A major discovery in the last 5 years has been the recognition that the geomagnetic field was at ultralow field strengths, some ten times weaker than the present-day, during the Ediacaran Period. These ultralow values were first reported from single crystal paleointensity analyses of 565 Ma rocks of the Sept Îles Mafic Intrusion Suite (Bono et al., Nature Geosci., 2019), and were later confirmed by studies of dikes and lavas from other sites in Ukraine and Canada (e.g., Thallner et al., EPSL, 2021). The ultralow values are followed by a rapid increase in field strength in the early Cambrian (Zhou et al., Nature Commun., 2022) and together these signals are consistent with initial nucleation of Earth’s inner core, as predicted by thermal models and geodynamo simulations (Davies et al., GJI, 2022). An updated timeline incorporating new paleointensity data from several localities in North America, South America and Africa highlights a striking temporal correspondence between the ultralow field, the Ediacaran diversification of macroscopic animals, and some geochemical indicators for the rise of oxygenation. The onset of inner core growth and unusual state of the geomagnetic field should not correspond with animal evolution or oxygenation unless changes in the Ediacaran magnetosphere attendant with the ultralow field somehow affected the atmosphere, oceans and/or biosphere. We will consider these possibilities. 

How to cite: Cottrell, R., Tarduno, J., Huang, W., Xiao, S., Blackman, E., Zhou, T., Schneider, J., Bono, R., and Ibañez-Mejia, M.: Ediacaran ultra-weak geomagnetic field, oxygen rise, and the diversification of macroscopic animals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12706, https://doi.org/10.5194/egusphere-egu24-12706, 2024.

EGU24-13629 | ECS | Orals | BG5.3

Ecosystem engineers impact marine biodiversity during the Phanerozoic 

Alison Cribb, Simon Darroch, and Thomas Ezard

Ecosystem engineers are keystone taxa whose behaviours alter the habitability of their environments for themselves and other organisms by directly influencing the availability of resources in their ecosystems. From a deep time perspective, ecosystem engineers are hypothesized to have played a major role in the co-evolution of life and the Earth systems, as many major ecosystem engineering activities directly modulate the cycling of key nutrients. Moreover, ecosystem engineers are thought to have impacted diversity by increasing environmental heterogeneity, and so their evolution may drive some of the biodiversity dynamics observed in the fossil record. Here, we investigate the impact of two groups of marine ecosystem engineers – bioturbators and reef-builders – on biodiversity through the Phanerozoic. Using fossil occurrence data from the Paleobiology Database, we calculate the effect size of bioturbating and reef-building ecosystem engineers on various biodiversity metrics for each stage through the Phanerozoic. Most broadly, we find that ecosystem engineers had a positive impact on biodiversity within the environments where they live during the Phanerozoic. We also find clear taxonomic differences between environments with and without ecosystem engineers, suggesting ecosystem engineers create a unique set of environmental characteristics to which taxa of specific ecological characteristics become adapted. These results emphasize the important role of ecosystem engineers in influencing key aspects of the Earth systems on a variety of scales that manifest in changes in biodiversity.

How to cite: Cribb, A., Darroch, S., and Ezard, T.: Ecosystem engineers impact marine biodiversity during the Phanerozoic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13629, https://doi.org/10.5194/egusphere-egu24-13629, 2024.

EGU24-13765 | Posters on site | BG5.3

Antifeedant biomarkers in Cretaceous sediments from the North Sudetic Basin, Poland 

Magdalena Goryl, Leszek Marynowski, and Bernd R.T. Simoneit

The Late Cretaceous succession of siliciclastic sediment from the Czerna Formation in the North Sudetic Basin (SW Poland) consists of sandstones, dark grey mudstones and shales with coal intercalations. Samples of dark grey mudstone with lignite fragments from the inoperative sandstone quarry in Rakowice Małe, and samples of coals and siltstones from the sandstone quarry in Wartowice, were selected for gas chromatography-mass spectrometry analyses. All samples were thermally immature (the mean vitrinite reflectance (Rr) values did not exceed 0.45%).

The samples contained phenolic abietans, including ferruginol and chamaecidin, which act as a defence mechanism against insect and microbial attack in coniferous trees (e.g., Gonzalez, 2015). Therefore, these compounds are widespread in extant coniferous trees (Simoneit et al., 2021) and can be identified in the geological record through their primary and diagenetic products. For instance, ferruginol (natural product), along with its derivatives: simonellite and retene, are present in the Cretaceous sedimentary rocks of the North Sudetic Basin. Another compound identified in the investigated samples is bergamotan. Perry et al. (2003) found that two derivatives of this compound were responsible for the insect antifeedant activity. Moreover, some of the identified compounds, such as chamazulene, are known in medical science for their anti-inflammatory properties (Safayhi et al., 1994).

The presence of natural products with antifeedant activity against insects in Cretaceous samples suggests that plants had developed host defence mechanisms tens of millions of years ago.

 

Acknowledgements

The authors acknowledge financial support from the Polish National Science Centre (grant 2018/31/N/ST10/01646 to MG).

 

References

Gonzalez, M.A., 2015. Aromatic abietane diterpenoids: Their biological activity and synthesis. Natural Product Reports 32, 684–704.

Perry, N. B., Burgess, E. J., Foster, L. M., Gerard, P. J. (2003). Insect antifeedant sesquiterpene acetals from the liverwort Lepidolaena clavigera. Tetrahedron Letters 44(8), 1651–1653.

Safayhi, H., Sabieraj, J., Sailer, E. R., Ammon, H. P. (1994). Chamazulene: An antioxidant-type inhibitor of leukotriene B4 formation. Planta Medica. 60 (5), 410–3. 

Simoneit, B. R. T., Rybicki, M., Goryl, M., Bucha, M., Otto, A., Marynowski, L. (2021). Monoterpenylabietenoids, novel biomarkers from extant and fossil Taxodioideae and rocks. Organic Geochemistry, 154, 104172.

How to cite: Goryl, M., Marynowski, L., and Simoneit, B. R. T.: Antifeedant biomarkers in Cretaceous sediments from the North Sudetic Basin, Poland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13765, https://doi.org/10.5194/egusphere-egu24-13765, 2024.

Mercenaria stimpsoni is a new paleoclimatic archive in the mid- to high-latitude western Pacific coastal area. This species is a cold-water bivalve with a long life span (>100 years old), and shell growth patterns and oxygen isotope ratios are useful tools as paleoenvironmental proxies. So far it is known that the shells of M. stimpsoni have distinct annual lines with microincrements between each annual line. However, the relationship between microgrowth patterns and marine environment is not understood. Fossil shells of this species are often found in interglacial marine sediments in Central Japan. Thus, understanding the relationship between microgrowth patterns and marine environment is key to reconstruct paleoclimate with high temporal resolution in this region.

The purpose of this study was to evaluate the usefulness of the microgrowth patterns in this species as a paleoenvironmental proxy. Sample shells were collected from the coasts of Hokkaido and Iwate Prefecture, Japan. Shells were then cut into thick sections along the maximum growth axis. The surfaces of the thick sections were polished. Photographs were taken with a Keyence VHX2000 at 300x to 1000x magnification. Photomosaics were created with Adobe Photoshop CC. Then, the number of microincrements and microincrement widths were measured with ImageJ. Then, 120 to 150 μg of carbonate powder was collected from the outer outer layer along the growth direction and provided for oxygen isotope analysis. Finally, we compared microgrowth patterns with marine environmental data. Growth line observations confirmed that approximately 100 microgrowth lines were formed per year in the shells, and that the micorogrowth patterns might reflect mainly seawater temperatures and planktonic blooms. In the poster presentation, we will report the relationship between microgrowth patterns and marine environment. By clarifying the relationship between them, the temporal resolution of paleoclimate reconstruction using this species can be improved to less than the annual scale.

How to cite: Miki, S. and Shirai, K.: Evaluation of the microgrowth patterns of shells of long-lived bivalve, Mercenaria stimpsoni as a paleoenvironmental proxy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14316, https://doi.org/10.5194/egusphere-egu24-14316, 2024.

EGU24-15098 | ECS | Orals | BG5.3

Climatic controls on dinosaur evolution, diversity and biogeography 

Emma Dunne, Lisa Schnetz, Alexander Farnsworth, Stephan Lautenschlager, Pedro Godoy, Eren Tasimov, Richard Butler, and Sarah Greene

Dinosaurs were dominant members of terrestrial ecosystems throughout the Mesozoic, yet only recently are studies beginning to illuminate the key role of global climate variation in controlling dinosaur biodiversity, global distribution, and macroevolution. Our work uses statistical, biogeographic, and phylogenetic comparative approaches with comprehensive fossil occurrence data and paleoclimate data from general circulation models to quantitatively examine key hypotheses connecting patterns of dinosaur diversity and evolution with climatic conditions. We examined the impact of climate change in driving early dinosaur evolution across the end-Triassic mass extinction (ETME). Our results demonstrate that the geographic distribution of early sauropodomorphs was constrained by climate and following the ETME, the expansion of climate zones facilitated the geographic expansion of sauropodomorphs and other dinosaurs. Evolutionary model-fitting analyses provide evidence for an important evolutionary shift from cooler to warmer climatic niches during the origin of Sauropoda. This same approach is also revealing the relationship between climatic conditions and dinosaur diversity in the Jurassic to Cretaceous, with implications for our understanding of the origins of sauropod gigantism and the evolution of herbivory. Our results suggest that primary productivity was a key climatic factor in driving sauropod evolution and promoting the evolution of larger body sizes, supporting the hypothesis that gigantism was facilitated by the increasing availability of high quality vegetation. Analyses of dinosaur paleoclimatic niche space show evidence of niche partitioning between herbivorous theropods and ‘traditional’ herbivorous dinosaurs (e.g. sauropods), indicating that climatic changes may have influenced evolutionary innovations related to dinosaur diet. Further work examining the relationship between dinosaur diversity and changes in vegetation using state-of-the-art vegetation models will illuminate the key role played by environmental change in controlling dinosaur diversity and evolution throughout the Mesozoic.

How to cite: Dunne, E., Schnetz, L., Farnsworth, A., Lautenschlager, S., Godoy, P., Tasimov, E., Butler, R., and Greene, S.: Climatic controls on dinosaur evolution, diversity and biogeography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15098, https://doi.org/10.5194/egusphere-egu24-15098, 2024.

EGU24-15732 | ECS | Posters on site | BG5.3

Deciphering the dynamics of the Mulde Event—Bayesian ultra-high-resolution ostracod paleocommunity analysis  

Liudas Daumantas, Simona Rinkevičiūtė, Sigitas Radzevičius, and Andrej Spiridonov

Silurian period witnessed a series of global extinction events, such as the Mulde/lundgreni Event during of the late Wenlock epoch.  These events triggered complex and abrupt changes in Earth's biota. The brief nature of these events requires a high sampling resolution for paleontological studies, a feat seldom achieved. By integrating published data with new samples from the Gėluva-118 core, we have attained resolution of ≈ 10 Ka in examining ostracod paleocommunities during the Mulde/lundgreni Event.

Our approach involved a custom-made binary recursive segmentation algorithm for the hierarchical subdivision of stratigraphically contiguous segments. This algorithm was applied to the ostracod taxonomic compositional time series data from the Gėluva-118 core (Lithuania). The results revealed significant changes in ostracod community composition, enabling us to delineate the event's stages. We employed a Bayesian Age-Depth model to assess the timing of these changes. The median and 95% Highest Density Interval (HDI) durations for each stage, as well as for the entire event, are as follows: Collapse – 50 Ka (11 – 171 Ka), Maximal Stress – 120 Ka (31 – 601 Ka), Recovery – 80 Ka (21 – 576 Ka), and the entire Mulde/lundgreni Event – 260 Ka (100 – 1,136 Ka). Our analysis of bootstrapped sample averages of diversity indices revealed that the Maximal Stress stage, marked by a severe scarcity of ostracods, signified a distinct shift in community diversity state. Prior to this stage, ostracod communities were less diverse, yet exhibited higher increases in evenness with growing diversity, indicating distinct community assembly and community structure patterns. Ostracod communities from the Collapse and Recovery stages resembled those adjacent to the Mulde/lundgreni Event interval but showed significantly reduced abundances, lower inverse Simpson index, and higher evenness. Furthermore, our findings suggest a nonlinear recovery stage, punctuated by setbacks and stabilization phases.

These insights demonstrate the potential of high-resolution paleontological studies in deciphering the chronology and pace of intermittent global events.

This research was supported by S-MIP-21- 9 “The role of spatial structuring in major transitions in macroevolution”.

How to cite: Daumantas, L., Rinkevičiūtė, S., Radzevičius, S., and Spiridonov, A.: Deciphering the dynamics of the Mulde Event—Bayesian ultra-high-resolution ostracod paleocommunity analysis , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15732, https://doi.org/10.5194/egusphere-egu24-15732, 2024.

EGU24-15917 | ECS | Orals | BG5.3

Stress, strain and crustal flow patterns in a corner collision: insights from coupled 3D numerical models 

Luuk van Agtmaal, Attila Balazs, Dave May, and Taras Gerya

Large and fast collisional systems such as the Eastern Tibetan-Himalayan orogenic system can have distinct corner structures. Away from the corners, plate convergence is accommodated primarily by convergence-parallel processes such as (continental) subduction, crustal thickening and buckling. Around the corners, oblique and convergence-perpendicular processes become more important, such as strike-slip, transpressional and transtensional faults. The strike of the subduction front itself can also vary in space, as tomographic images show for the case of the Indian slab beneath Tibet and Burma. At the corners themselves, a peculiar syntaxis structure may form which is characterised by effective strain localisation and high rates of exhumation and erosion. However, our understanding of the temporal evolution of orogenic syntaxis formation is still elusive. 

Here, we use high-resolution, three-dimensional thermomechanical models to investigate principal stress orientations, strain rate patterns and upper versus lower crustal flow patterns within a continental corner collision setting loosely resembling the Eastern Tibetan-Himalayan orogenic system. We use a 1000 x 200 x 1000 (x * y * z) model domain with a permeable lower boundary and a 2 km grid resolution in each dimension. Each grid cell has 8 markers. The models are carried out using I3ELVIS (Gerya and Yuen, 2007) coupled to the surface process model FDSPM (Munch et al., 2022). Our numerical experiments highlight that i) significant lateral variability occurs despite prescribing orthogonal kinematic boundary conditions; ii) a high variability of stress states and deformation styles occur within the modelled orogen and plateau; iii) Lower crust beneath the plateau escapes later than upper crust, but around 3-4 times faster. Lastly, we examine the sensitivity of the model evolution to different degrees of strain weakening, intracrustal layering, and the diffusion coefficient of the surface process model.

Gerya, T. V., & Yuen, D. A. (2007). Robust characteristics method for modelling multiphase visco-elasto-plastic thermo-mechanical problems. Physics of the Earth and Planetary Interiors, 163(1), 83–105. https://doi.org/10.1016/j.pepi.2007.04.015

Munch, J., Ueda, K., Schnydrig, S., May, D. A., & Gerya, T. V. (2022). Contrasting influence of sediments vs surface processes on retreating subduction zones dynamics. Tectonophysics, 836, 229410. https://doi.org/10.1016/j.tecto.2022.229410

How to cite: van Agtmaal, L., Balazs, A., May, D., and Gerya, T.: Stress, strain and crustal flow patterns in a corner collision: insights from coupled 3D numerical models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15917, https://doi.org/10.5194/egusphere-egu24-15917, 2024.

EGU24-17160 | Orals | BG5.3

Uncovering life and planetary co-evolution through the genomic record 

Cara Magnabosco, Paula Rodriguez, Fatima Husain, Maddie Paoletti, Chris Parsons, Jack Payette, Sarah Swartz, Erik Tamre, and Greg Fournier

The maintenance of Earth’s habitability over geologic timescales is largely driven by the metabolisms and ecologies of bacteria and archaea. In this context, the role that microorganisms have played throughout major environmental transitions during the Archean and Proterozoic Eons are especially noteworthy. The “genomic record” represents the accumulated adaptations to planetary change maintained within the collective genetic pool of life. In this presentation, we will describe how the genomic record can be used to improve our understanding of microbial natural history and present six broadly applicable principles to aid in the investigation these complex questions. This framework will then be used to guide a a meta-analysis of microbial genomes derived from collections large metagenomic databases across diverse environments to illustrate how specific environmental variables drive the microbial diversity patterns we see today.

How to cite: Magnabosco, C., Rodriguez, P., Husain, F., Paoletti, M., Parsons, C., Payette, J., Swartz, S., Tamre, E., and Fournier, G.: Uncovering life and planetary co-evolution through the genomic record, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17160, https://doi.org/10.5194/egusphere-egu24-17160, 2024.

EGU24-17379 | ECS | Orals | BG5.3

125 Ma of physiographic changes and mammal macroevolution 

Manon Lorcery, Laurent Husson, Tristan Salles, Oskar Hagen, Alexander Skeels, and Sébastien Lavergne

Changes in the physical environment, whether geological or climatic, are known to be major drivers of biodiversity. At the interface between the solid Earth and the climate lies the physiography, and landscape complexity and variety may control biodiversity mechanisms at a finer scale that the large scale patterns of plate tectonics and global climate. To test whether variation of physiography through time and space can explain the current richness pattern of biodiversity and understand the impact of landscape complexity evolution on specific mechanistic processes, we simulated the diversification of terrestrial mammals at global scale, over 125 Ma of geological and climatic changes, using a spatially explicit eco-evolutionary simulation model (genesis). We designed four evolutionary scenarios in which evolution was only dependent on climate and plate tectonics (M0), and scenarios where physiographic diversity was implemented in speciation (M1), dispersion (M2) and niche ecology (M3). To assess whether model predictions are consistent with the empirical distribution of terrestrial mammals, we statistically identify general emergent patterns of biodiversity within and across spatial and temporal scales. 

How to cite: Lorcery, M., Husson, L., Salles, T., Hagen, O., Skeels, A., and Lavergne, S.: 125 Ma of physiographic changes and mammal macroevolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17379, https://doi.org/10.5194/egusphere-egu24-17379, 2024.

EGU24-18509 | Orals | BG5.3

Exploring the Links between Testate Amoeba Traits and Eutrophication in Lakes 

Helen Roe, Andrew Macumber, Stephen Prentice, Timothy Patterson, Carl Sayer, and David Emson

There is considerable potential to apply traits-based approaches to the subfossil remains of shell-forming micro-organisms which preserve well in sediments and whose short generation times make it possible to achieve high-temporal resolution in palaeoecological studies.  In this paper we review progress in applying traits-based approaches to freshwater testate amoebae (Arcellinida), a diverse group of protists which are abundant in lakes and are valuable palaeoecological indicators.  Drawing on published studies from the last ~10 years, we describe the methodologies which have been applied to delimit testate amoeba (TA) traits and review the challenges associated with their measurement and interpretation.  We also showcase the results of ongoing work in seven lakes (UK, Canada) which aims to (i) examine the character and causes of trait-based variability in palaeolimnological settings; (ii) apply novel biometric approaches to aid in trait delimitation; and (iii) explore the potential for combining phylogenetic with advanced morphometric approaches to better understand the ecological and evolutionary significance of TA traits.

            We applied geometric morphometric analysis to define test size and shape indices and summarise testate amoeba community dynamics along a temporal gradient of eutrophication in a large shallow lake in Scotland, UK.  Cluster analysis of test size and shape indices yielded three assemblages, each dominated by a single shape: elongate, spherical and ovoid. When plotted stratigraphically, we observed increases in spherical tests, decreases in elongate tests and shrinking of test size coeval with eutrophication. Decreases in the elongate cluster may reflect benthic conditions with reduced oxygen levels, while increases in the spherical cluster are likely associated with an expanding macrophyte community that promoted pelagic and epibiotic life habits.  Shrinking of test size may be a stress response to eutrophication and/or warming temperatures. Tracking community dynamics using test size and shape indices was found to be as effective as using traditional species-based approaches to summarize key palaeolimnological changes, with the added benefit of being free of taxonomic bias.  The approach thus shows significant potential for future studies of aquatic community change in nutrient-impacted lakes.

            To further investigate the functional significance of the Arcellinida shape groups, we examined the phylogenetic signal of morphological traits in elongate Difflugia species which occur in eutrophic and mesotrophic lakes.  Previous phylogenetic work has shown that whilst overall test morphology (e.g., spherical or elongate) is generally conserved in Arcellinida lineages, the taxonomic significance of other traits (e.g., size, ornamentation, mixotrophy/heterotrophy metabolism type) is not well understood.  Our analyses revealed two clades which could be reliably separated by test size and the presence/absence of mixotrophy.  This suggests that test size may reflect trophic level, with smaller taxa occupying lower trophic levels.  In addition to having larger tests, elongate mixotrophic Difflugia are characterised by wide, flat bases and inflation of the lower part of the test.  These morphological traits may provide additional space for endosymbionts and/or increased surface area to aid light transmission.  Continued research into the ecological and evolutionary significance of morphological traits will serve to strengthen palaeoecological inferences, increasing the importance of lacustrine testate Arcellinida as environmental proxies.

How to cite: Roe, H., Macumber, A., Prentice, S., Patterson, T., Sayer, C., and Emson, D.: Exploring the Links between Testate Amoeba Traits and Eutrophication in Lakes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18509, https://doi.org/10.5194/egusphere-egu24-18509, 2024.

EGU24-18542 | Posters on site | BG5.3

Continuous 3D modelling over deep time – the SCION Earth Evolution Model 

Benjamin Mills, Dongyu Zheng, Khushboo Gurung, Andrew Merdith, Alexander Krause, Zhen Xu, Fred Bowyer, and Stephen Hunter

Earth system models for deep time have typically been unable to represent geological timespans in 3D because climate and ocean circulation plays a key role in global biogeochemistry and generating a 3D physical climate simulation is extremely computationally expensive. This means that Earth System Modelling for periods of over 1 Myr has been exclusively carried out in nondimensional box models, which leads to oversimplification of spatially heterogeneous processes like continental weathering and marine carbon burial. This simplification may be a key reason why so many climate questions over deep time remain unresolved. The SCION (Spatial Continuous IntegratiON) project aims to produce a 3D and self-consistent climate and biogeochemical system that can be run over billion-year timeframes. To do this, it employs a physical climate emulator which is developed using a Deep Learning method trained on hundreds of General Circulation Model runs over different paleogeographies and CO2 levels. The SCION development project – SIM-EARTH – also includes a new process-based reconstruction of paleotopography using the GPlates kinematic plate model, development of a long-term dynamic global vegetation module and ocean biogeochemical module, and databasing projects to establish 3D datasets for marine and terrestrial palaeontology and geochemistry that can be compared to model outputs at the local scale to test hypotheses. We hope that new model frameworks like this can help us better understand the evolution of Earth’s surface conditions over time, assess the contribution of the biosphere to global environmental change, and help determine what fundamental characteristics are required for a planet to be habitable for complex life.

How to cite: Mills, B., Zheng, D., Gurung, K., Merdith, A., Krause, A., Xu, Z., Bowyer, F., and Hunter, S.: Continuous 3D modelling over deep time – the SCION Earth Evolution Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18542, https://doi.org/10.5194/egusphere-egu24-18542, 2024.

EGU24-18738 | ECS | Orals | BG5.3

How did the Permian-Triassic hot house climate shape the vegetation landscape and how did the land plant fight back? 

Zhen Xu, Jianxin Yu, Jason Hilton, Barry H. Lomax, Paul B. Wignall, and Benjamin Mills

During the Permian-Triassic Mass Extinction (PTME) ~252Ma, diverse lowland forests were replaced by low diversity pioneer herbaceous lycopod communities that proceeded to dominate the Early and Middle Triassic landscape. The flourishing of Early-Middle Triassic herbaceous lycopods was coincident with data that suggests lethally warm surface temperatures (>40ºC) occurred across large regions of the planet. To explore how these plants were able to thrive during this interval of enhanced climatic stress, we collected data from over 400 fossil plant specimens from South China, supplemented by additional data from literature reviews from other regions and geological ages. Our studies on their morphology indicate that among all Phanerozoic lycopods the transitional Permian-Triassic genus Tomiostrobus (=Annalepis) has the closest morphological relationship with the recent lycopod Isoetes.

Extant Isoetes are renowned for their flexibility with regard to the photosynthetic pathway they use and their capacity to absorb CO2 through their roots. To evaluate whether this photosynthetic flexibility was linked to their Early-Middle Triassic ecosystem dominance, we undertook carbon isotope and sedimentary facies analysis including plant taphonomy to test for the presence of the Crassulacean Acid Metabolism (CAM) photosynthetic pathway. Plants capable of CAM pathway growing in stressful environment typically have heavier isotopic signatures while show typical C3 plant signatures in hospitable environment. Our carbon isotope data shows that Permian Triassic Transition Tomiostrobus isotopic signature is on average ~2‰ less negative when compared to contemporary non lycophyte vegetation. Furthermore, the carbon isotope of the Middle Triassic lycopods ~1.07‰ heavier than the other plants, while Late Permian Lepidodendron exhibits a similar δ13C value with other contemporary plants. These findings suggest that CAM photosynthesis may have played a role in the dominance of the Triassic herbaceous lycopods. The dominance of CAM plants following the PTME has implications from an Earth Systems standpoint due to their diminished productivity and a lower capacity for biotic weathering, features that likely suppressed negative feedback loops important in driving climate stabilization during the ~5Ma PTME recovery phase.

How to cite: Xu, Z., Yu, J., Hilton, J., Lomax, B. H., Wignall, P. B., and Mills, B.: How did the Permian-Triassic hot house climate shape the vegetation landscape and how did the land plant fight back?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18738, https://doi.org/10.5194/egusphere-egu24-18738, 2024.

EGU24-19816 | ECS | Posters on site | BG5.3

Modelling the life-environment interface in ancient shelf seas 

Sara Sjosten, Stuart Daines, and Tim Lenton

The co-evolution of life and environment is a dynamic system of feedbacks. Much of the evolution of life took place in localized shelf sea environments where evolving biota and redox conditions created feedbacks which are hypothesized to have increased the ecospace for life to radiate - and sometimes perhaps brought about its own demise. Models can suggest hypotheses to test ecosystem dynamics and the effects of changes to life or the environment on the other. A particular modelling challenge is to connect these localized environments to global Earth system dynamics over long timescales. A hierarchy of models is needed to separate spatial and temporal scales and allow for the construction of models specific enough to be supported by limited geological data. We introduce a 1D column model of an ocean shelf sea in the PALEO framework to represent the ecological dynamics of important early life forms such as plankton, sponges and early burrowers and their effects on redox conditions, sediment burial and diagenesis. This model demonstrates that ecological dynamics and nutrient cycling can be modelled at the finest scales, while remaining computationally viable over geological timescales. Ongoing work integrating this model with data from critical time intervals in the Ediacaran and Cambrian can provide specific hypotheses for the local behavior of the life-environment interface and can be connected to broader models for global investigations.

How to cite: Sjosten, S., Daines, S., and Lenton, T.: Modelling the life-environment interface in ancient shelf seas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19816, https://doi.org/10.5194/egusphere-egu24-19816, 2024.

EGU24-19830 | ECS | Posters on site | BG5.3

Exploring the role of weathering dynamics, nutrient input and palaeoredox conditions on the origin of biomineralization and ecosystem habitability in the late Ediacaran Nama Group, Namibia   

Fred Bowyer, Gustavo Paula-Santos, Collen-Issia Uahengo, Kavevaza Kaputuaza, Junias Ndeunyema, Mariana Yilales, Ruaridh Alexander, Andrew Curtis, Simon Poulton, Simone Kasemann, and Rachel Wood

     The first animals (metazoans) with skeletons belong to the tubular ‘cloudinid’ morphogroup, the lowest occurrence of which marks the base of the Nama biotic assemblage (ca. 551–550 Million years ago, Ma). This evolutionary first appearance coincided with, or immediately post-dated, a major faunal turnover event associated with the loss of many soft-bodied White Sea assemblage taxa that dominated the preceding ca. 6–10 Myrs. At present, there is no evidence that the majority of cloudinid skeletons were biomineralized under strong biological control. Instead, these early biomineralizing metazoans may have acquired their skeletons with relative ease in response to ambient seawater chemistry in carbonate settings. The trigger for the origin of metazoan biomineralization remains unknown, but may have been linked to changes in seawater Mg/Ca and/or environmental oxygen concentration.  

     Weathering-derived nutrient input can fuel marine productivity and regional deoxygenation on short-medium timescales, leading to organic carbon and pyrite burial and atmospheric oxygenation on longer timescales. Changes to the intensity and style of weathering on the global scale can also alter the flux of dissolved cations (e.g., Ca and Mg) and alkalinity to the oceans. Despite their importance, global weathering dynamics at the dawn of animal biomineralization remain poorly understood. Carbonate-hosted Sr and Li isotopes have the potential to track the degree and style of weathering, and temporal trends in both datasets may therefore provide meaningful insights into the dynamics of associated elemental fluxes to regional palaeoenvironments. 

     Late Ediacaran sedimentary rocks of the Nama Group (ca. 551–538 Ma) host a rich fossil assemblage that includes impressions of both soft-bodied organisms and the lowest known occurrence of the skeletal cloudinid, Cloudina. Here we present new Sr and Li isotope data from carbonates in four outcrop sections, and new data of carbonate carbon isotopes, major and trace element concentrations, and Fe speciation from two cores drilled as part of the ICDP GRIND-ECT project, which together span the entire Ediacaran portion of the Nama Group succession. The combination of these data, when considered within a sequence stratigraphic framework, clearly reveals the influence of changes in regional weathering intensity/style on marine palaeoredox dynamics. Furthermore, calibration of these new data within a global chronostratigraphic age model reveals cyclicity in weathering proxies from multiple cratons that respond directly to changes in eustatic sea level. The implications of these new time-calibrated geochemical and stratigraphic data are considered relative to the timing of the earliest metazoan biomineralization, and major faunal turnover events that preceded and coincided with deposition of the Nama Group succession. 

How to cite: Bowyer, F., Paula-Santos, G., Uahengo, C.-I., Kaputuaza, K., Ndeunyema, J., Yilales, M., Alexander, R., Curtis, A., Poulton, S., Kasemann, S., and Wood, R.: Exploring the role of weathering dynamics, nutrient input and palaeoredox conditions on the origin of biomineralization and ecosystem habitability in the late Ediacaran Nama Group, Namibia  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19830, https://doi.org/10.5194/egusphere-egu24-19830, 2024.

EGU24-21627 | ECS | Orals | BG5.3

Regional tectonics shaped plant biodiversity in Colombian Andes 

Yi Liu, Richard Ott, Loïc Pellissier, and Niklaus Zimmermann

Northern South America, particularly the geologically dynamic Colombian Andes, stands as a region of highest plant biodiversity. While the influence of mountain uplift in the tropical Andes on biodiversity patterns is well-recognized, the repercussions of these landscape changes on the evolutionary dynamics of the local flora have been understudied. Here, we aim to fill this gap by investigating the role of uplift history and landscape evolution in driving the assembly and maintenance of plant biodiversity in the Colombian Andes. We integrate a comprehensive reconstruction of individual geological blocks with plant phylogenies, distribution patterns, and the resulting biogeographic structuring of the endemic flora. Our comparative analysis reveals a substantial agreement between the geological blocks and biogeographic realms instead of climate, indicating the fundamental role of regional tectonics shapes the observed pattern of biodiversity. Notably, the northern segments of the Western and Central Cordillera and Eastern Cordillera, representing the two most-recent fast uplift blocks, exhibit a higher prevalence of endemic species and a significant accumulation of in situ speciation events over the last 10 million years. Our findings provide a detailed perspective on how landscape changes have driven the diversification of flora in the Colombian Andes and contribute to a broader understanding of the intricate interplay between geological processes and plant evolution, emphasizing the importance of considering regional tectonic dynamics in unraveling the heterogeneous biodiversity patterns on Earth.

How to cite: Liu, Y., Ott, R., Pellissier, L., and Zimmermann, N.: Regional tectonics shaped plant biodiversity in Colombian Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21627, https://doi.org/10.5194/egusphere-egu24-21627, 2024.

The depleted mantle and the continental crust are largely geochemically and isotopically complementary. However, the question of when the depleted mantle reservoirs developed on Earth remains a topic of considerable debate. In this study, we report the existence of a ca. 3.8 Ga detrital zircon from the quartzite of the Paleoproterozoic Songshan Group in the southern North China Craton. In situ zircon hafnium isotopic characteristics of the 3.8–3.2 Ga detrital zircons indicate the presence of source rocks as old as ca. 4.5 Ga in the southern North China Craton. Together with the global zircon U-Pb-Hf isotope dataset from the North China Craton, Jack Hills, Acasta as well as available μ142Nd values of ancient rocks from Archean craton worldwide, the new results indicate that the silicate Earth has differentiated at 4.5–4.4 Ga almost immediately after accretion, developing continental crust and a complementary depleted mantle reservoir at that same time.

How to cite: Si, B., Diwu, C., and Si, R.: Eoarchean-Paleoarchean crustal material in the southern North China Craton and possible mantle reservoir of early Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-406, https://doi.org/10.5194/egusphere-egu24-406, 2024.

EGU24-1479 | Orals | GD3.1 | Highlight

Recipes for a Hadean Earth 

Stephen J. Mojzsis and Anna Medvegy

Silicate+metal worlds like Earth form hot owing to gravitational heating from accretion and differentiation, and intrinsic radioactive decay. Concurrent cooling sets off a chemical and mechanical cascade wherein siderophile elements (Fe+Ni) form a metallic core, and lithophile elements (Mg, Si, Al, Ca, Na, etc.) partition into mantle and siliceous crust. The outcome is a rocky surface beneath an outgassed fluid envelope composed of atmophile elements and compounds (CO2, H2O, H2, etc.). In its first 500 Myr (q.v. Hadean eon), Earth’s crust co-existed with liquid water; it was molded by volcanism, affected by late accretion bombardments and harbored diverse hydrothermal systems. Volcanism and differential buoyancy of the crust mandates the presence of scattered emergent landmasses. Such Hadean surfaces could host diverse (sub-)aqueous where organic chemical ingredients became concentrated to reactivity beneath a dense atmosphere bathed by the active young Sun. Soon after planet formation, it seems proto-biochemical reactions led to full-fledged living biochemistry. We do not know whether the earliest environments for life were ideally suited for its origin, or merely just good enough to accomplish the task. The inferred complexity for even the minimum biological entity means that operative and persistent biochemistry are the most difficult developmental stages to reach.

How to cite: Mojzsis, S. J. and Medvegy, A.: Recipes for a Hadean Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1479, https://doi.org/10.5194/egusphere-egu24-1479, 2024.

EGU24-1792 | ECS | Orals | GD3.1

Litho-structural framework of the Eoarchean Tussaap supracrustal belt, Itsaq gneiss complex, southwestern Greenland 

Peter Haproff, Alexander Webb, Chit Yan Eunice Leung, Christoph Hauzenberger, Jiawei Zuo, and Anthony Ramírez-Salazar

The Isua and Tussaap supracrustal belts of the Itsaq gneiss complex, southwestern Greenland, form the largest and best-preserved exposure of Eoarchean supracrustal materials on Earth. Previous studies have almost exclusively focused on the ∼35-km-long, arc-shaped Isua supracrustal belt and adjacent ca. 3.8–3.7 Ga meta-tonalite bodies, which are the basis for competing Archean tectonic regime interpretations (i.e., plate versus heat-pipe tectonics). In this study, we performed geologic field mapping of the seldom-explored Tussaap supracrustal belt, located ~11 km south of the Isua supracrustal belt, to better constrain its litho-structural framework and test the predictions of existing Eoarchean tectonic models. Observations from this study and previous works show that the Tussaap supracrustal belt consists of a east-northeast-striking, ~12-km-long and <1-km-wide, mostly continuous belt of greenstone rocks flanked to the north and south by ca. 3.8 Ga meta-tonalite. Lithologies of the Tussaap supracrustal belt consist of interlayered garnet ± staurolite ± sillimanite paragneiss, felsic schist, garnet mafic schist, amphibole-rich garbenschiefer, and minor pegmatite bodies and meta-ultramafic rocks. The northern and southern contacts between the Tussaap supracrustal belt and meta-tonalite are ~100-m-wide transitional zones featuring interlayered and folded meta-tonalite and greenstone rocks that increase in abundance towards each lithologic unit. Both the Tussaap supracrustal belt and adjacent meta-tonalite feature well-developed, southeast-dipping foliation and southeast-plunging stretching lineation (average 162° trend, 40° plunge). Macroscopic sheath and often rootless, disharmonic folds with hinges parallel to stretching lineation occur throughout the study area. In contrast with previous interpretations, no discrete tectonic discontinuities (i.e., brittle faults and ductile shear zones) were observed within the Tussaap supracrustal belt and meta-tonalite. Similarly, no apparent metamorphic field gradient was observed in the study area. This litho-structural framework is consistent with that of the Isua supracrustal belt and meta-tonalite bodies to the north, indicative of spatially-uniform strain and metamorphism. Based on our preliminary observations, the Archean development of the region can be explained by uniform subvertical shearing and folding of an interlayered volcanic-intrusive sequence (i.e., heat-pipe tectonics). Additional structural, geochronologic, and geochemical analyses of the Tussaap supracrustal belt and meta-tonalite are required to further elucidate their emplacement and metamorphic histories and differentiate end-member models of Archean tectonics.

How to cite: Haproff, P., Webb, A., Leung, C. Y. E., Hauzenberger, C., Zuo, J., and Ramírez-Salazar, A.: Litho-structural framework of the Eoarchean Tussaap supracrustal belt, Itsaq gneiss complex, southwestern Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1792, https://doi.org/10.5194/egusphere-egu24-1792, 2024.

An Archean ancestral landmass of Columbia supercontinent is a matter of concern to geologists. A single supercontinent called “Kenorland” or several supercratons have been mainly proposed, but more evidence from geological records and palaeomagnetism argue for the latter supercraton solution, in which two long-lived supercratons Sclavia and Superior were recently reconstructed. Studies has shown that the Northern China blocks, including the North China and Tarim cratons, the Alxa, Quanji blocks, were involved in the reconstruction of Columbia. However, their affinity in Archean supercratons remained little constrained. Owe to the lack of reliable palaeomagnetic data old than 1.8 Ga, the geological piercing points in these blocks could allow us to figure out the question. Then, compilation and comparison of Neoarchean–early Paleoproterozoic magmatism, metamorphism, and sedimentary records, have been conducted among these blocks. As a result, 2.4-2.2 Ga magmatism and khondalite-like sedimentary sequence may be used as indicators of the affinity of these blocks in northern China. Consequently, the Kuruktag Block, Quanji Block, Alxa Block, TNCO, Khondalite Belt have similar evolutionary history during the Neoarchean-Paleoproterozoic, suggesting their close affinity at that period. Besides, the North China craton and Dharwar craton of India shield were proved to be connected during the Archean-Proterozoic. And latest study indicate the Dharwar craton was one of the Sclavia supercraton. Therefore, we speculate that during the Neoarchean–early Paleoproterozoic, the Kuruktag-Quanji-Alxa-TNCO-Khondalite Belt link was close to the Dharwar craton in Sclavia supercraton. The absence of Siderian glacial event (ca. 2.4 Ga) in the Alxa, Quanji, Kuruktag blocks and TNCO, Khondalite Belt of the North China craton rule out the link with Superia, which is common in Superia supercraton. Further geological and paleomagnetic studies are required to constrain the above hypothesis, the relation between these blocks clusters and other cratons, which is crucial to understand the origins of blocks in northern China.

How to cite: Zhang, Q. and Yao, J.: Paleogeographic affinity of Northern China block clusters in Archean-Paleoproterozoic supercraton solution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2507, https://doi.org/10.5194/egusphere-egu24-2507, 2024.

1 Deep Space Exploration Laboratory / School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China.

2Department of Earth Sciences, The University of Hong Kong, Hong Kong, Hong Kong.

3Department of Geology, State Key Laboratory of Continental Dynamics, Northwest University, Xi'an, China.

* Corresponding author: wuzq10@ustc.edu.cn.

The origins of the Archean cratons were most important events in the early Earth and crucial for understanding how the early Earth worked. The mechanisms for the origins of the Archean cratons remain unclear. It is widely accepted that Archean tonalite-trondhjemite-granodiorite (TTG) plutons were derived from hydrous mafic magmas in the garnet/ amphibole stability field. Although the subduction can bring water to the mantle to produce granitic magma, the island Arc Model for the origin of continents meets fundamental challenges. The growing evidences support the plume-driven oceanic plateau models for the origin of continents. However, the lower parts of the oceanic plateau have been thought to be dry. How to generate the hydrous meta-basalt at the base of the oceanic plateau remain an open question.

Here we show that the Archean cratons resulted from the evolution of the hydrous magma ocean (Wu et al., 2023). The whole-mantle magma ocean created by the moon-forming giant impact likely evolved into an outer magma ocean and a basal magma ocean because the magma ocean would initially crystallize in the mid mantle and the basal magma ocean is denser than the overlying solid mantle. The basal MO at the beginning should contain a certain amount of water since extensive studies suggest substantial accretion of water-rich bodies during core formation. The major lower-mantle minerals have limited water storage capacity. Therefore, with progressive crystallization, the basal magma ocean becomes increasingly enriched in water. The basal magma ocean eventually becomes gravitationally unstable because of the enrichment of water. The triggered massive mantle overturns transported a large amount of water upward to the shallow part of the Earth and resulted in the major pulses of the crust and thick SCLM generations. The model can account for many observations including the source of water needed for generation of the continental crust, the major pulse of crustal growth around the end of the Archean, why the TTG and thick SCLM basically occurred in the Archean, and why only the Earth among inner planets was covered with the continental crust.

 

Wu, Z., Song, J., Zhao, G., & Pan, Z. (2023). Water-induced mantle overturns leading to the origins of Archean continents and subcontinental lithospheric mantle. Geophysical Research Letters, 50, e2023GL105178. https://doi.org/10.1029/2023GL105178

How to cite: Wu1, Z.: Water-induced mantle overturns and the origins of Archean cratons, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2870, https://doi.org/10.5194/egusphere-egu24-2870, 2024.

The BIFs in Bundelkhand Craton occurred as a discontinuous unit within the east-west trending Bundelkhand Tectonic Zone (BTZ). The BIFs were associated with amphibolite, calcsilicate rocks, and quartzite. The BIFs were massif in appearance in the Mauranipur (east of Bundelkhand Tectonic Zone, BTZ) that graded to layered variety in the Babina area (west of the BTZ).

The Bundelkhand BIFs were characterized by 45 to 55 wt.% SiO2 and 44 to 55 wt.% Fe2O3 content. The Al2O3 content was usually low and varied between > 1 to 3 wt%. Barring a few samples, the MnO and CaO contents are < 1 wt.%. The higher MnO (~ 3.70 wt.%) and CaO (~ 1 wt.%) implied a different redox condition and involvement of CaCO3 in the early stages of BIF formations. The ΣREE content of Bundelkhand BIFs varied between 10 – 38 ppm, with Eu/Eu*SN values between 1.1 to 1.5. Geochemically, the BIFs were classified as Algoma-type BIFs deposited by low-temperature hydrothermal fluids. Monoclinic amphiboles, quartz and garnet were the dominant silicate phase for Mauranipur BIFs. Hornblende was present with monoclinic amphibole in the garnet-absent BIFs. Isolated grains of magnetite were dispersed throughout the Mauranipur BIFs. In contrast, alternate hematite and SiO2-rich layers with locally developed low-T amphiboles characterized Babina BIFs. The Fe-rich oxides were mostly hematite. Mineral microstructure and P-T pseudo-section modeling implied Minnesotaite and Fe-Ca carbonate phases were the primary minerals in BIFs, deposited at temperature ~ 200°C at 0.05 to 0.1 GPa. The primary minerals experienced dehydration and decarbonization reactions, leading to the stabilization of amphibole and garnet at a temperature of ~450°C and pressure of 0.1—0.2 GPa. When plotted in a P-T diagram, the increase in temperature corresponds to tectonic activity and plutonism, leading to micro-bock accretion and growth of Bundelkhand Craton.

How to cite: Raza, M. B. and Nasipuri, P.: Mineralogy and P-T condition of Algoma type Banded Iron Formation from Bundelkhand Craton, North-Central India and their implications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2992, https://doi.org/10.5194/egusphere-egu24-2992, 2024.

Iron Formations (IF) are economically significant sedimentary rocks primarily formed in the Precambrian evolutionary history of the Earth. In the Precambrian period, Iron Formations were deposited within marine sediments on stable continental margins (superior-type) and in association with volcanic rocks and many volcanic Massive Sulphide (VMS) deposits (Algoma-type). Most scientists agree that for BIF to form, photosynthesis and changing ferrous iron from seawater into mixed-valence iron (oxy-hydroxide) oxides and carbonate phases during oxidation are needed.
The present study is based on the Superior-type BIFs from the Girar Supracrustal Belt of Southern Bundelkhand terrane, which mainly consists of Neoarchean K-rich granitoids with a minor volume of a schist complex, TTG, sanukitoids, and mafic-ultramafic layered intrusion. The Girar schist (metasedimentary) belt is mostly made up of two types of rocks: (i) quartzite and (ii) BIFs. There are also some dolomitic marble and chlorite schist lenses close to the quartzite/BIF boundary. The BIFs consist of thick-bedded quartz and hematite with magnetite. The quartzites display low-grade metamorphism of fuchsite- and hematite-bearing quartz arenite with thick meta-argillite (schist) laminae and lesser quartz pebble conglomerates.
P-T pseudosection modelling indicates that Fe-carbonates and iron-oxyhydroxides (minnesotaite) are the primary phases that stabilize at 200 – 250 O C, 0.1–0.15 GPa. Subsequently, the low-temperature phases experienced dehydration and decarbonisation reactions with an increase in temperature, leading to the stabilisation of hematite and magnetite. The absence of orthopyroxene in the BIFs suggests these rocks suffer amphibolite facies
metamorphism, which is uncommon in generally undeformed superior-type BIFs.

How to cite: Bisht, B. P. S.: Mineralogy and P-T conditions of Superior- type Iron Formation fromBundelkhand Craton, North Central India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3109, https://doi.org/10.5194/egusphere-egu24-3109, 2024.

EGU24-3114 | ECS | Orals | GD3.1

Reconstruction of the Tarim craton within Rodinia: constraints from magmatic- orogenic records in the Altyn belt 

Wei Li, Jinlong Yao, Guochun Zhao, and Yigui Han

The position of the Tarim craton within the Rodinia supercontinent has long been the focus of scientific debate, with competing models varying from internal to external positions. The Altyn belt in the southeast Tarim margin records an extensive Neoproterozoic magmatic-sedimentary successions which likely recorded the convergence of Tarim to Rodinia. Thus, we here investigated the granitoids exposed in the Kuoshi-Kalaqiaoka and Tula areas in the eastern and western segment of the South Altyn belt. We present new field geology, zircon U–Pb–Hf–O isotopes and H2O, and whole rock geochemistry data from these granitoids. Zircon U–Pb data yielded ages of 914 ± 3.9 Ma for the Tula granite, 919 ± 5.2 Ma and 932 ± 6.5 Ma for the Kuoshi granite. The Tula and Kalaqiaoka granite samples mostly display high ACNK values that are typical of S-type granitoids, consistent with the presence of Al-rich minerals, such as garnet and muscovite. In addition, the Tula granite have higher zircon δ18O (7.62 to 10.85‰, peaked at 8.9‰) and lower εHf(t) (-4.0 to +0.3) values, along with lower H2O content (medium values at 102 and 251 ppmw), indicating that the primary magmas were generated from recycled ancient crust in a water-deficient syn-collisional setting, with minor juvenile contribution. On the other hand, the Kuoshi granite have high Sr (169–259 ppm), Sr/Y (17.85–19.33) and (La/Yb)N (30–49) ratios that are indicating of adakitic affinity. The Kuoshi granite are also characterized by lower δ18O (4.15 to 9.81‰, peaked at 8.2‰) and εHf(t) values(−2.4 to 0.6), along with higher H2O content (medium values at 255 and 795 ppmw) and MgO. These signatures suggest that the Kuoshi pluton was formed by recycling ancient crust and subducted continental crust. Overall, the granitoids across the South Altyn belt reflect a transformation of tectonic regime from water-enriched subduction setting to water-deficient syn-collisional setting. Moreover, the Hf isotopes evolution tend of the early Neoproterozoic granitoids and Suoerkuli Group across the South Altyn belt also suggest a transformation from slab retreat to syn-collision in the early Neoproterozoic. Therefore, overall data and field relations across the Altyn belt indicate an early Neoproterozoic magmatic-sedimentary successions that are similar to that of the Eastern Ghats Belt in India. Given the available paleomagnetic data and detrital zircon age patterns, we conclude a position of the Tarim craton between Australian and North India block in the periphery of Rodinia, close to East Antarctica as well. This research was supported by NSFC Projects (42322208 and 41972238), National Key Research and Development Programs of China (2022YFF0802700 and 2023YFF0803604) and Hong Kong RGC GRF (17308023).

How to cite: Li, W., Yao, J., Zhao, G., and Han, Y.: Reconstruction of the Tarim craton within Rodinia: constraints from magmatic- orogenic records in the Altyn belt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3114, https://doi.org/10.5194/egusphere-egu24-3114, 2024.

EGU24-3303 | ECS | Orals | GD3.1

Redox state of Archean surface environments: Insights from the Banded Iron Formations (BIFs) of the Western Dharwar Craton, Southern India  

Aindrila Mukherjee, Jayananda Mudlappa, Pritam Nasipuri, and Aadhiseshan Krishnasamy Raveendran

The interplay of geological, chemical and biological processes that drive the oxygenation of the oceans-atmosphere of the early earth are spatially linked to the emergence of biosphere. Banded Iron Formations (BIFs) from the Archean greenstone belts form important archives for understanding the redox conditions of Archean surface environments. The Archean Dharwar craton preserves BIFs in the volcano-sedimentary greenstone belts of two distinct stratigraphic units (older Sargur Group and younger Dharwar Supergroup) corresponding to a time span of 3300-2600 Ma.  These BIFs are confined to the highest stratigraphic levels forming summits of greenstone belts.  They show alternate layers of chert and iron oxides, and petrographic data reveal diverse mineralogy including oxides, carbonate, sulphide and silicate facies. The occurrence of riebeckite and stilpnomelane in BIFs of younger Dharwar Supergroup indicates recrystallization under low-grade metamorphism. Slightly higher abundances of CaO and Al2O3 reveal significant influence of crustal source and precipitation of CaCO3 during BIFs formation. Mesoscopic layers of chert and iron oxide with variable thickness suggest fluctuating redox state of surface environments. The higher enrichment of Ni (6-26 ppm) than the Cr content (3-19 ppm) with variable Sr concentrations may be attributed to feldspar breakdown during hydrothermal fluid acceleration. Trace element ratios (Y/Ho, Sm/Yb, Eu/Sm) coupled with positive Eu anomalies of the BIFs from both older Sargur Group and younger Dharwar Supergroup BIFs reveal dominant hydrothermal input in BIFs origin. The PAAS normalized REE data preclude major continental input in the origin of BIFs. The variable negative Ce anomalies imply periodic fluctuating surface environments (oxic to anoxic) at the dawn of the Great Oxidation Event close to 2340 Ma. This is consistent with the published Fe, N, and S isotope data on the BIFs of the Western Dharwar craton.

 

How to cite: Mukherjee, A., Mudlappa, J., Nasipuri, P., and Krishnasamy Raveendran, A.: Redox state of Archean surface environments: Insights from the Banded Iron Formations (BIFs) of the Western Dharwar Craton, Southern India , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3303, https://doi.org/10.5194/egusphere-egu24-3303, 2024.

EGU24-3394 | Orals | GD3.1

Paleoarchean volcanic stratigraphy and geochemistry of the mafic-ultramafic Kromberg Formation type-section, Barberton greenstone belt, South Africa. 

Eugene Grosch, Sibu Ndlela, David Murphy, Nicola McLoughlin, Jakub Trubac, and Jiri Slama

In this study, the c. 3.334 Ga Kromberg Formation of the Onverwacht Group, in the south-eastern limb of the Onverwacht Anticline in the Barberton greenstone belt (South Africa) is investigated. Various geodynamic models have been proposed for the evolution of the Kromberg Formation, but detailed geochemical constraints on the mafic-ultramafic sequence are sparse. The objectives are to constrain the Paleoarchean mantle source characteristics and geodynamic setting for the Kromberg mafic-ultramafic rocks, placed in the context of recent high-resolution field mapping data. To study the protolith volcanic rocks, sampling has been conducted to avoid areas affected by deformation-related alteration. In addition, screening for alteration due to Archean seawater silicification has also been conducted. In conjunction with major, trace and rare earth element data, this study presents the first whole-rock Lu-Hf isotope analyses of mafic-ultramafic rocks of the Paleoarchean Kromberg Formation type-section in the Barberton greenstone belt (Grosch et al., 2022). Three compositionally distinct volcanic rock types are identified namely Group 1 metabasalts, Group 2 metabasalts and komatiitic metabasalts. The geochemistry of these rock types will be presented, and a possible geodynamic setting on the early Earth will be explored.  

Grosch, E.G., Ndlela S., Murphy D., McLoughlin N., Trubac J., Slama J., (2022) Geochemistry of mafic-ultramafic rocks of the 3.33 Ga Kromberg type-section, Barberton greenstone belt, South Africa: Implications for early Earth geodynamic processes. Chemical Geology 605, 120947

How to cite: Grosch, E., Ndlela, S., Murphy, D., McLoughlin, N., Trubac, J., and Slama, J.: Paleoarchean volcanic stratigraphy and geochemistry of the mafic-ultramafic Kromberg Formation type-section, Barberton greenstone belt, South Africa., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3394, https://doi.org/10.5194/egusphere-egu24-3394, 2024.

EGU24-3563 | ECS | Orals | GD3.1

The geological record of H2 production in the Archean 

Renée Tamblyn and Jörg Hermann

The oxidation of iron from rocks during subaqueous alteration is a key source of the molecular hydrogen (H2) used as an energy source by chemosynthetic organisms, which may represent some of the earliest forms of life on Earth. In the Archean, a potential source of ultramafic material available for serpentinisation reactions that release H2 are komatiites. Komatiites are highly magnesian lavas, which contain evidence of extensive serpentinisation and magnetite (Fe2+Fe3+2O4) production close to the Archean seafloor. H2 production in komatiitic compositions has been modelled and experimentally investigated; however, the natural rock record has remained unexplored. Here, we examine the geological evidence of H2 production from the basaltic to komatiitic rock record held in Archean cratons. From the petrological investigation of thirty-eight samples of komatiitic basalt to komatiite, we identify the unique serpentinisation reaction responsible for H2 production from these lithologies. With support from over 1100 bulk rock geochemical analyses, we directly quantify Fe3+ and therefore H2 production of komatiites in the Archean. The chemical (high Mg) and physical (low viscosity flow) characteristics of komatiite flows allowed for extensive hydration and serpentinisation in oceanic plateaus, and therefore high H2 production available to chemosynthetic early life.

How to cite: Tamblyn, R. and Hermann, J.: The geological record of H2 production in the Archean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3563, https://doi.org/10.5194/egusphere-egu24-3563, 2024.

EGU24-4334 | Orals | GD3.1

Earth's evolution over time revealed by the Nb/U, Ce/Pb and Nb/Th ratios in the sources of mantle plumes. 

Alexander Sobolev, Adrien Vezinet, Aleksandr Chugunov, Mateo Esteban, Valentina Batanova, Nicholas Arndt, Charitra Jain, Stephan Sobolev, Evgeny Asafov, and John Valley

Magmas from mantle plumes are potentially the best monitors of Earth's compositional and thermal evolution over time. However, their erupted products are commonly modified by syn- and post-magmatic processes and thus do not fully retain original information about their mantle sources. Such data can be recovered from melt inclusions in olivine phenocrysts in the most primitive magmas from mantle plumes. Such inclusions, shielded by host olivine, retain original isotopic and critical trace element signatures of deep mantle sources even for Archean and Hadean Eons.

We will present the results of a study of chemical and Rb-Sr isotope composition (EPMA, LA-ICP-MS and RAMAN) of melt inclusions and chemical (EPMA, LA-ICP-MS) compositions of host olivines for komatiites and plume-related picrites with eruption age from 3.3 Ga to 1 Ka.

Recent advances in in-situ split stream LA-ICP-MS measurements of 87Sr/86Sr ratios and trace element contents of olivine-hosted melt inclusions revealed significant mantle source heterogeneities of magmas from individual plumes. The results are confirmed by geodynamic modelling (Jain et al., this meeting).

We show that the melt inclusions of most studied mantle plumes display heterogeneous populations in age-corrected 87Sr/86Sr ratios and include groups with model ages more than 1 Ga older than the emplacement age. The oldest inclusion groups found in Archean komatiites correspond to Hadean (4.3±0.2Ga, Vezinet et al., in review) and Eo-Paleoarchean (3.6±0.2 Ga) model ages. These and most inclusions from studied komatiites and picrites display Nb/U, Nb/Th and Ce/Pb significantly higher than in BSE.

Evolution over time of canonical proxies of continental crust generation (Nb/U, Th/U and Ce/Pb, Hofmann et al., 1986) in mantle plumes, combined with geodynamic modelling, suggests:

  • Most of the continental crust was generated in several Hadean and Archean pulses by plume-induced subduction and melting of the hydrated mafic/ultramafic crust or mantle. Hadean continental crust was subducted or/and reworked.
  • Restites left after extraction of continental crust were continuously subducted to the core-mantle boundary from the mid-Hadean and later recycled in Archean mantle plumes.
  • Active formation of both continental and oceanic crust in Hadean was governed by plume-induced subduction, which ceased after cold subducted material hindered the propagation of large plumes at the core-mantle boundary. After heating the recycled lithosphere at the core-mantle boundary, the process repeats, producing oscillating subduction and crustal formation in Hadean-Archean.

How to cite: Sobolev, A., Vezinet, A., Chugunov, A., Esteban, M., Batanova, V., Arndt, N., Jain, C., Sobolev, S., Asafov, E., and Valley, J.: Earth's evolution over time revealed by the Nb/U, Ce/Pb and Nb/Th ratios in the sources of mantle plumes., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4334, https://doi.org/10.5194/egusphere-egu24-4334, 2024.

The results of the U-Pb-Hf-O isotope study of zircon from (meta)igneous rocks sampled in all domains of the Ukrainian Shield allow recognition of the four main stages of continental crust formation:

1. The Eoarchean stage (ca. 4000-3600 Ma). Rocks of this stage occur in the Dniester-Bouh and Azov domains. In the former, they are represented by heavily metamorphosed enderbites and mafic schists reaching an age of 3.8 Ga. In contrast, tonalites with an age of 3.67 Ga were identified in the Azov Domain. The oldest zircon reaching an age of 3970 Ma was found in the Mesoarchean metadacite in the Azov Domain. The Eoarchean rocks are rare, but their presence indicates that crust-forming processes have started already in the Eoarchean, or even in Hadean, time.

2. The second major event took place between c. 3.2 and 2.7 Ma. Rocks, formed during this age interval, compose around half of the Ukrainian Shield. Considering the long duration of this event, it may have consisted of several separate episodes. The whole set of rock associations typical for the Archean continental crust, including TTG series, greenstone belts and sedimentary basins, has been formed. Hafnium isotope composition in zircon reveals the juvenile nature of this event. Some remobilization of the older crust is also recorded from several samples.

3. Nearly half of the rock assemblages were dated at ca. 2.15-1.90 Ga. In contrast to the Archean events that resulted in the formation of apparently more or less equant terranes, the Paleoproterozoic events led to the formation of orogenic belts. These belts comprise metamorphosed in amphibolite or epidote-amphibolite facies supercrustal sequences, and abundant granitic intrusions. According to the existing models, the formation of the orogenic belts was related to the assembly of Baltica as a part of the Columbia/Nuna supercontinent. Hafnium-in-zircon and whole-rock Nd isotopes indicate the predominantly juvenile nature of these rocks, with some contamination by the Archean crust.

4. The last major stage of the Ukrainian Shield evolution was linked to the formation of the Prutivka-Novohol large igneous province, which between 1.8 and 1.72 Ga affected the whole Shield. It resulted in the emplacement of numerous mafic dykes and layered massifs, alkaline intrusions, and huge anorthosite-mangerite-charnockite-granite complexes. All igneous rocks formed during this stage reveal signs of crustal contamination, although input of moderately depleted mantle material is also evident.

Obtained isotope and geochronological data demonstrate that the growth of the continental crust in the Ukrainian Shield was episodic. The mechanisms of the crustal growth were different at different times. During both Archean events, the main mechanism was mafic underplating with further remelting and generation of TTG series, whereas greenstone belts represent the results of mantle plume activity. In the Paleoproterozoic, the main mechanism of crustal growth was the subduction of the oceanic lithosphere that led to the formation of volcanic arcs. Mantle plumes remained an important mechanism of the input of mantle-derived material into the continental crust.

How to cite: Shumlyanskyy, L.: The main stages of the Ukrainian Shield evolution and plate tectonics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4724, https://doi.org/10.5194/egusphere-egu24-4724, 2024.

EGU24-4875 | ECS | Posters on site | GD3.1

Plume-induced continental crust growth rate in Early Earth:Insight from numerical modeling 

Xinyi Zhong, Zhong-Hai Li, and Yang Wang

The origin of Earth’s felsic continental crust is still a mystery. The continental crust requires two-steps partial melting of mantle rocks. There are two proposed hypotheses for the continental crust growth in the Early Earth. One is the subduction-related magmatism, e.g. island arc, that produces intermediate to felsic magma which constitutes the early buoyant continental crust. The other is that the magmatism induced by mantle plume creates the thick basaltic crust, and which partially melts into continental crust. However, both two models have their deficiencies. It is still a controversial topic that when plate tectonics begins, which is an obstacle for applying the subduction-induced model in the Early Earth. On the other hand, the plume-induced model seems to be inefficient to support the continental crust growth. The previous numerical studies haves generally focused on the mechanisms of the continental crust formation, while efficiency of the model remains unknown. Thus, we simulated the melt transport process and integrated petrological model in our numerical model to evaluate the efficiency and the plausibility of continental crust production by mantle plume in the Earth’s history. The comparison between our model results and the reconstruction model of continental crust growth provides a new insight for the problem. The results indicates that the mantle plume is an efficient and possible way to support rapid continental crust growth in the Archean. Other mechanisms, e.g. subduction, may take dominant role since the Proterozoic because of low efficiency of plume-induced continental crust production.

How to cite: Zhong, X., Li, Z.-H., and Wang, Y.: Plume-induced continental crust growth rate in Early Earth:Insight from numerical modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4875, https://doi.org/10.5194/egusphere-egu24-4875, 2024.

EGU24-5245 | Orals | GD3.1

Elemental fluxes into 3.0-billion-year-old marine environments: evidence from trace elements and Nd isotopes in banded iron formations from the Murchison Greenstone Belt, South Africa 

Johanna Krayer, Sebastian Viehmann, Alina Mayer, Toni Schulz, Christian Koeberl, Axel Hofmann, Jaganmoy Jodder, Matthias Willbold, and Stefan Weyer

Banded Iron Formations (BIFs) are authigenic, marine sediments directly reflecting the chemical composition of ancient seawater. BIFs serve as prime geochemical archives for the reconstruction of Precambrian marine environments. However, due to the scarcity of well preserved Archean rocks, atmospheric and hydrospheric environmental conditions within this time frame are still incompletely understood. In particular, elemental fluxes derived from continental weathering and submarine hydrothermal fluxes that affected ancient seawater chemistry are cornerstones for our understanding of the evolution of marine habitats through time. Here we present major- and trace element concentrations in combination with Nd isotopic compositions of 13 samples of Mesoarchean Algoma-type greenschist-facies BIFs from the ca 3.0 Ga old Murchison Greenstone Belt, South Africa. Individual Fe- and Si-rich layers are monitored for sample purity based on their chemical composition. Neodymium isotope compositions, in combination with trace element contents of BIF samples with varying amounts of clastic detritus, are further used to reconstruct the Murchison depositional environment and identify the origin of dissolved and detrital components entering the ancient ocean around 3.0 Ga ago.

Eight samples with low immobile element concentrations display typical shale-normalized Archean seawater-like rare earth and yttrium (REYSN) patterns with positive LaSN, EuCN, and GdSN anomalies, super-chondritic Y/Ho ratios, and an enrichment of heavy REYSN over light REYSN, implying an open marine-dominated depositional setting with contributions from submarine high-temperature, hydrothermal systems. A Sm-Nd regression line yields an age of 2.98 ± 0.19 Ga that overlaps with the proposed depositional age, suggesting negligible post-depositional alteration on the REY composition of the pure BIF layers. In contrast, higher concentrations of immobile elements (e.g., Zr) and/or non-seawater-like REYSN patterns are characteristic for the remaining five BIF samples, indicating elevated detrital input or post-depositional alteration. A regression line of the impure BIF layers yields an age of 2.49 ± 0.15 Ga, reflecting a potential post-depositional overprinting event such as the 2.6 Ga old Limpopo orogeny. The Nd isotopic compositions of pure and impure BIF samples cover a wide range of ca. two epsilon units suggesting a mixture of weathered mafic and felsic sources for the dissolved and suspended fluxes into the Murchison ocean.

How to cite: Krayer, J., Viehmann, S., Mayer, A., Schulz, T., Koeberl, C., Hofmann, A., Jodder, J., Willbold, M., and Weyer, S.: Elemental fluxes into 3.0-billion-year-old marine environments: evidence from trace elements and Nd isotopes in banded iron formations from the Murchison Greenstone Belt, South Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5245, https://doi.org/10.5194/egusphere-egu24-5245, 2024.

EGU24-5391 | ECS | Posters on site | GD3.1

Diverse P-T-t paths within the Neoarchean sagduction regime of North China Craton: insights from field data and numerical modeling 

Chenying Yu, Ting Yang, Jian Zhang*, Guochun Zhao, Peter A. Cawood, Changqing Yin, Jiahui Qian, Peng Gao, and Chen Zhao

The Neoarchean greenstone-granite rock association preserved in the Eastern Block of the North China Craton exhibits distinctive dome-and-keel structures. Although the metamorphic data from these rock assemblages provide valuable insights into the tectonic evolution of this region, the interpretation of the clockwise paths with nearly isothermal decompression (ITD) and the anticlockwise P–T paths involving near-isobaric cooling (IBC) remain inconsistent and controversial. By conducting 2D numerical models with the initial and boundary conditions similar to those of the Neoarchean Eastern Block, we investigated the coexistence of diverse P-T paths and determined their possible geodynamic regime. The model results demonstrate that the combination of crustal density inversion and heat from the high-temperature lower boundary initiates a crustal-scale sagduction process, leading to the formation of dome-and-keel structures. Additionally, we identified four primary types of P-T-t paths. Firstly, an anticlockwise IBC-type P-T-t path reveals the supracrustal rocks gradually subside to a deep crustal level, where they experience a prolonged residence period characterized by ambient mantle cooling without significant exhumation. Secondly, a clockwise ITD-type P-T-t path suggests the supracrustal rocks descend to the deep crust and are partly entrained by upwelling TTG magmas, leading to their rapid ascent to a middle crustal level. Thirdly, a newly identified crescent-type P-T-t path indicates an integrated burial-exhumation cycle, consisting of an initial burial stage with high dT/dP, followed by a rapid exhumation stage and a subsequent cooling stage exhibiting low dT/dP. Lastly, a hairpin-type P-T-t path highlights the slow exhumation rate experienced by deeply buried supracrustal rocks. The dome-and-keel structure and P-T-t paths observed in the numerical model are consistent with the geochronological, metamorphic and structural data of the Eastern Block. Based on these observations, we propose that the crustal-scale sagduction involving a mantle plume could responsible for the geological complexity of eastern China.

This work was financially supported by the National Natural Science Foundation of China (42025204) and National Key Research and Development Program of China (No. 2023YFF0803804).

How to cite: Yu, C., Yang, T., Zhang*, J., Zhao, G., Cawood, P. A., Yin, C., Qian, J., Gao, P., and Zhao, C.: Diverse P-T-t paths within the Neoarchean sagduction regime of North China Craton: insights from field data and numerical modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5391, https://doi.org/10.5194/egusphere-egu24-5391, 2024.

EGU24-6614 | Orals | GD3.1

Evolving Chemistry of Lithospheric Mantle Based on Oxygen Isotope and Trace Element Analyses of Olivines from Mantle Xenoliths across Earth’s History 

Ilya Bindeman, Valentina Batanova, Alexander Sobolev, Dmitri Ionov, and Leonid Danyushevsky

Oxygen is the most abundant element in the terrestrial mantle and crust. We have recently reported on a 0.2‰ δ18O decrease of continental mantle peridotites from the original primary Bulk Silicate Earth-Moon value of 5.57‰ [1] in the mid-Archean to the Phanerozoic explained by the initiation of surface recycling (linked to intensity and style of plate tectonics) sometime in the Archean. Even small variations in the volatile mass balance are critical in explaining phenomena such as the Great Oxidation Event at ~2.4 Ga that may have mantle origin. As low-δ18O subduction fluids are derived by the dehydration (and potentially oxidation) of low-δ18O interiors of subducted slabs, this work further explores this process to observe temporal changes related to the progressive input of volatile elements and potential lithospheric mantle oxidation. This study presents a record of trace elements measured in same olivines (Li, Na, Al, P, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Ga, Y, Zr) including oxidation-sensitive elemental ratios V/Sc and Zn/Fe for this collection. Prior melt-depletion of mantle peridotites, estimated using bulk Al2O3 content of the xenoliths, increases with age from ~25 to 35%, leading to depletion of Yb, Y, Co, Mn, Ca, P, with smaller effects on the elemental ratios.  We observe significant ranges of V/Sc (0.2-14), Li/Y and other ratios, not related to prior melt depletion that may be linked to subduction-related re-distribution of incompatible elements by subduction [2], and scattered correlation with age and δ18O values. Further trends will be analyzed during the talk after considering craton-specific domains and global trends. This work can potentially contribute to constraining a global mass balance of crustal growth and recycling based on co-variations of isotopes of a major element oxygen and trace elements in the predominant lithospheric reservoir of subcontinental mantle.

[1]Bindeman ea, (2022) Nat Comm 13, 3779; [2] Doucet ea, (2020) NatGeosci 13, 511.

How to cite: Bindeman, I., Batanova, V., Sobolev, A., Ionov, D., and Danyushevsky, L.: Evolving Chemistry of Lithospheric Mantle Based on Oxygen Isotope and Trace Element Analyses of Olivines from Mantle Xenoliths across Earth’s History, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6614, https://doi.org/10.5194/egusphere-egu24-6614, 2024.

EGU24-7106 | ECS | Orals | GD3.1 | Highlight

Fresh water on Earth four billion years ago 

Hamed Gamaleldien, Li-Guang Wu, Hugo K.H. Olierook, Christopher L. Kirkland, Uwe Kirsche, Zheng-Xiang Li, Tim Johnson, Sean Makin, Qiu-Li Li, Qiang Jiang, Simon A. Wilde, and Xian-Hua Li

The operation of a hydrological cycle (i.e., exchange of water between the land, oceans, and atmosphere) has significant implications for the emergence of life. The oldest confirmed single-celled organisms at ~3.48 billion years ago (Ga) (Pilbara Craton, Western Australia) are thought to have formed in the presence of meteoric (fresh) water on emerged (subaerial) land in a hot spring environment. However, when widespread interaction between fresh water and emerged continental crust first began is poorly constrained. In this study, we use >1000 oxygen isotope analyses of Jack Hills detrital zircon to track fluid-rock interactions from the Hadean to the Paleoarchean (~4.4–3.1 Ga). We identify extreme isotopically light O (i.e., δ18O < 4.0 ‰) values older than 3.5 Ga. The data define two periods of magmatism with extreme isotopically-light O as low as 2.0 ‰ and –0.1 ‰ at around 4.0 and 3.4 Ga, respectively. Using Monte Carlo simulations, we demonstrate that such values can only be generated by the interaction of crustal magmatic systems with meteoric water. Our data constrains the earliest emergence of continental crust on Earth, the presence of fresh water, and the start of the hydrological cycle that likely provided the environmental niches required for a life less than 600 million years after Earth’s accretion.

How to cite: Gamaleldien, H., Wu, L.-G., Olierook, H. K. H., Kirkland, C. L., Kirsche, U., Li, Z.-X., Johnson, T., Makin, S., Li, Q.-L., Jiang, Q., Wilde, S. A., and Li, X.-H.: Fresh water on Earth four billion years ago, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7106, https://doi.org/10.5194/egusphere-egu24-7106, 2024.

Several studies have already concluded the presence of 7-8 ocean equivalent water (OCE) in the mantle of earth, structurally occurring as H+/OH. This can affect the seismic anomaly, mechanical strength, ionic diffusion, etc. of the mantle. The upper mantle is primarily composed of olivine, which first transforms to wadsleyite and then to ringwoodite at ~13 and ~18 GPa, respectively. Petrological and mineralogical experiments have demonstrated that H, occurring as point defects can act as a source of water in the upper mantle. Being the abundant mineral in upper mantle, it is very important to investigate the ability of olivine to act as a potential mineral phase to house water. Incorporation of water in mantle minerals has been a burning topic for many theoretical and experimental works. Even a trace amount of water in mineral structure can significantly alter their physical (e.g., elastic behaviour, seismic velocities, etc.) and chemical properties (e.g., ionic diffusion, electrical conductivity, etc.). FT-IR studies suggested that a rapid diffusion of H+ in olivine makes it a better candidate for point defects compared to larger and heavier OH ions. Karato & Jung (2003)  showed that increment of H concentration in olivine decreases its strength. Later, Mao et al. (2008) and Panero et al. (2010) observed qualitatively similar trend in high pressure olivine polymorphs. They observed drastic reduction in selective elastic constants of C11compared to C12 and C44 as H content increases in ringwoodite. Huang et al. (2005) found that temperature and water increases electrical conductivity in both the polymorphs. Yoshino et al. (2009) reported that a hike in temperature switches H-diffusion mechanism in olivine from proton conduction to small polaron conduction. The H diffusion in Fe-bearing olivine is experimentally shown to be dictated by (i) Proton-polaron (PP) mechanism and (ii) Proton-vacancy (PV) mechanism in <1 GPa. The PV is found to be valid for incorporating more water in olivine compared to PP. However, the second method, despite being strongly anisotropic, allows a faster diffusion. Much of the existing studies deals with temperature and water content as the key physical factors in controlling proton diffusivity. The fact that most of these studies have not carried out in the exact pressure (p) and temperature (T) conditions of mantle of Earth demand further studies on the same. Present study involves the study of H diffusion in lattice structure of olivine and wadsleyite; their mechanical stability, physical and chemical properties under mantle p–T conditions. Our results suggest a drop in seismic velocities in both olivine and wadsleyite phases. This can explain few outstanding geological events such as, weakening of upper mantle etc. This study will also provide a water budget in these mantle minerals. Therefore, the proposed research embarks on advancing theoretical understanding of hydrous mineral phases, which have a stability under extreme thermo-mechanical conditions.

How to cite: Das, P. K. and Karangara, A.: First principle investigations on the water budget in olivine phases: Implications towards the behavior of hydrous mantle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7388, https://doi.org/10.5194/egusphere-egu24-7388, 2024.

EGU24-9476 | Orals | GD3.1

Spatially explicit simulations of the effect of tidal energy dissipation on the climate on early Earth 

Georg Feulner, Benjamin Biewald, J. A. Mattias Green, Matthias Hofmann, and Stefan Petri

The potential impact of the increased rates of tidal energy dissipation on the climate on early Earth is usually assessed in terms of the global contribution to the energy balance which is small compared to the incoming solar radiation. However, tidal energy dissipation depends strongly on the distribution of landmasses, and regional energy input could, in principle, impact the local and global climate state via changes in circulation patterns and feedbacks in the Earth system. Here we investigate these effects by calculating tidal energy dissipation for a randomly generated continental distribution representative of early Earth, and three different rotation rates, and feeding it into a coupled climate model. Despite marginal global impacts, tidal energy dissipation can have significant regional effects caused by changes in ocean circulation and amplified by the ice-albedo feedback. These effects are strongest in climate states and regions where meridional heat transport close to the sea-ice margin is altered. This suggests that tidal heating could have contributed to sustaining regions with no significant ice cover.

How to cite: Feulner, G., Biewald, B., Green, J. A. M., Hofmann, M., and Petri, S.: Spatially explicit simulations of the effect of tidal energy dissipation on the climate on early Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9476, https://doi.org/10.5194/egusphere-egu24-9476, 2024.

EGU24-10677 | Posters on site | GD3.1

Geochemical and Nd isotopic constraints on the evolution of Neoarchean continental crust underlying the central Deccan Traps 

Marc C. Halfar, Bradley J. Peters, James M.D. Day, and Maria Schönbächler

Ancient rocks documenting early silicate Earth processes are only sparsely preserved on its modern surface. Some of the oldest known crustal lithologies (≤3.7 Ga) can be found within the Indian Shield. However, a substantial area of the western and central Indian basement has been covered by the ~66 Ma old Deccan flood basalts. Some Deccan-related mafic dykes in the Nandurbar-Dhule region of the Narmada-Tapi rift zone host xenolithic crustal material, which can be used to study the otherwise inaccessible basement. Textural and mineralogical heterogeneity amongst these xenoliths implies that they derive from different depths of a single column of crust and represent randomly sampled crustal rock types with possibly distinct heritages. Well studied examples of these dykes are the adjacent Rajmane and Talwade dykes south of Duhle, which host Neoarchean-aged [1] crustal xenoliths with highly variable 87Sr/86Sr ratios between 0.70935 and 0.78479 [2]. This led previous researchers to infer a genetic relationship of these xenoliths with rocks from the Dharwar Craton [1, 2].

In this study, xenolith samples are used to investigate the evolution of sub-Deccan continental crust and evaluate whether randomly sampled crustal lithologies share a common Hadean heritage that is similar to published data for Dharwar granitic rocks. Our samples (n = 17) originate from two mafic dykes near Talwade and Ranala in the Nandurbar-Dhule region. We report major and trace element abundances and 142Nd isotopic compositions. The CIPW norms of xenoliths define a nearly continuous petrological evolution trend from tonalites to reworked, orthoclase-rich granites, with subordinate trondhjemitic compositions. The vertical cross-section of crust underlying the dykes therefore provides an opportunity to study the geochemistry of evolving primitive continental crust. Trace element abundance data also conform to a tonalite-trondhjemite-granodiorite-like (TTG) composition for a subset of the xenoliths, whereas others resemble younger granitoids, which might represent reworked TTG equivalents, or younger intrusions.

The short-lived (t1/2 = 103 Ma) 146Sm-142Nd decay system is particularly sensitive to magmatic fractionation processes that occurred within the first ca. 500 Ma of Earth’s history. Heterogeneous 142Nd/144Nd compositions (expressed as μ142Nd = [(142Nd/144Nd)sample/(142Nd/144Nd)JNdi – 1] * 106) are typically restricted to Archean-aged rocks and reveal information about the preservation of mantle heterogeneity over geological timescales. The μ142Nd of dyke host lavas (n = 3) are heterogeneous (μ142Nd = -2.0 ±5.1 to +6.1 ±5.1) but unresolved from the terrestrial standard. Such heterogeneity suggests that the parental magmas to the dykes experienced complex lithospheric and crustal assimilation during their ascent. Felsic xenoliths have homogeneous μ142Nd compositions (μ142Nd = -0.9 ±2.3, 95% c.i., n = 7). Combined with the major and trace element data, this implies an extensively reworked crust underneath the Deccan Traps. The lack of recognizable μ142Nd anomalies is consistent with data of younger Dharwar granitoids [3] and may reflect regional overprinting of mantle μ142Nd heterogeneity at or before the Neoarchean emplacement age of the xenoliths.

 

[1] Upadhyay et al. (2015) J. Geol. 123(3), 295–307.

[2] Ray et al. (2008) Gondwana Res. 13, 375–385.

[3] Ravindran et al. (2022) Goldschmidt Abst. 10986.

How to cite: Halfar, M. C., Peters, B. J., Day, J. M. D., and Schönbächler, M.: Geochemical and Nd isotopic constraints on the evolution of Neoarchean continental crust underlying the central Deccan Traps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10677, https://doi.org/10.5194/egusphere-egu24-10677, 2024.

EGU24-10889 | Orals | GD3.1

Archaean record of the Singhbhum Craton, India: new insights from greenstone belts and cratonic cover sequences.  

Jaganmoy Jodder, Axel Hofmann, Marlina Elburg, and Rebeun Ngobeli

In recent times, the Archaean geological record of the Singhbhum Craton has been scrutinized regarding early Earth crustal processes, tectonics, magmatic-detrital zircon geochronology, early life research, and Fe-Mn mineralization associated with volcano-sedimentary successions. However, many of these studies are hampered by a lack of a basic stratigraphic framework of the various litho-stratigraphic units, complicating our understanding of the overall Archaean geology of the Singhbhum Craton. Here, we share first-hand information on the Palaeoarchaean greenstone belts and Meso-Neoarchaean intracontinental volcano-sedimentary sequence of the Singhbhum Craton.

New magmatic zircon U-Pb ages determined from felsic volcanic rocks of the Badampahar Group are represented by their crystallization age at c. 3.51 Ga. Intrusive granitoids exposed in the Daitari and Gorumahisani greenstone belts yield crystallization ages ranging from 3.38 to 3.29 Ga and having inherited zircons being 3.58, 3.55, and 3.51 Ga old. A granitoid intrusive into iron formation of the Gorumahisani greenstone belt has an age of c. 3.29 Ga.  Detrital zircons recovered from Koira Group sandstone intercalated with iron formation yield a maximum depositional age of 2.63 Ga. 

We demonstrate that Palaeoarchaean greenstones exposed in the northern and southern parts of the Singhbhum Craton consists largely of sub-marine mafic-ultramafic volcanic rocks interlayered with minor felsic volcanic and chemical sedimentary rocks. Importantly, the ca. 3.51 Ga felsic volcanic rocks from the Badampahar Group permit comparison with co-eval felsic volcanic units reported from the lower part of the Onverwacht, Nondweni, Warrawoona groups of the Kaapvaal and Pilbara cratons. Otherwise, new age constraints of the Koira Group allow for better correlations with Meso-Neoarchaean cratonic cover successions elsewhere. 

How to cite: Jodder, J., Hofmann, A., Elburg, M., and Ngobeli, R.: Archaean record of the Singhbhum Craton, India: new insights from greenstone belts and cratonic cover sequences. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10889, https://doi.org/10.5194/egusphere-egu24-10889, 2024.

EGU24-12762 | ECS | Orals | GD3.1

Boron isotopes in global TTGs trace the increase in deep crustal recycling in the Mesoarchean   

Jeroen Goumans, Matthijs Smit, and Kira Musiyachenko

Granitoids of the Tonalite-Trondhjemite-Granodiorite (TTG) group are a prime constituent of Archean cratons. Differences in the composition of these rocks relative to modern-day, more potassic granitoids have been proposed to reflect changes in the conditions and mechanisms of crust generation. By extension, these differences may indicate changes in the tectonic regime through geological time. Despite a continuously growing body of TTG research, consensus on TTG generation and Archean tectonic settings has not yet been reached. A remaining open question regarding TTGs is whether a reworked crustal component is present. Silicon and O isotopes have been previously employed to address this question and both isotope systems suggest that at least some TTGs indeed contain reworked material. Boron provides an alternative isotope system that can trace surface-altered material in magmatic rocks because B isotopes fractionate significantly at Earth’s surface but remain relatively unaltered at high temperatures. On modern-day Earth, the deep recycling of isotopically heavy seawater-derived B through subduction results in a diverse, but on average heavy, B isotope composition in arc granitoids. Conversely, juvenile granitoids formed in settings unrelated to subduction typically have mantle B-isotope values. These systematics are likely uniform and would apply to the Archean as well, given that Archean seawater also appears to exhibit isotopically heavy B. The B isotope system may thus be used to investigate the presence of subducted or otherwise surface-derived material in Archean granitoids. To this end, B isotopes were analyzed for a geographically and temporally spread sample set of pristine TTGs and related granitoids (n=45, from 9 different Archean terranes covering an age range of 3.78 to 2.68 Ga). This is a considerably larger and more geographically spread sample set than a B-isotope pilot study on TTGs (Smit et al., 2019), and may as such provide more globally representative results. The B isotope signature of TTGs seem to diversify over time, diverging more from mantle-derived values starting between 3.3 and 2.9 Ga. TTGs younger than 2.9 Ga exhibit up to δ11B = +10.5 ± 0.2‰, and 48% of the samples have δ11B values heavier than depleted mantle, whereas this is 18% for TTGs older than 3.3 Ga. The B isotope signature additionally diversifies with decreasing K2O/Na2O and La/Sm. Boron isotope compositions do not correlate with geochemical or petrological proxies for (post-)magmatic processes, such as weathering, metamorphism, hydrothermal alteration, or the loss of magmatic fluids, and therefore seem to be at least not significantly altered by these processes. Instead, isotopically heavy B in TTGs may be explained by the addition of a sodic and 11B-rich contaminant into the TTG source. These contaminant characteristics point to seawater-altered oceanic crust, possibly introduced to the TTG source through subduction. If this is correct, the temporal trend observed in the δ11B values in TTGs may reflect a shift from local and episodic to global and systematic subduction of oceanic crust in the Mesoarchean.

Smit, M.A. et al., 2019, Formation of Archean continental crust constrained by boron isotopes: Geochemical Perspectives Letters, doi:10.7185/geochemlet.1930.

How to cite: Goumans, J., Smit, M., and Musiyachenko, K.: Boron isotopes in global TTGs trace the increase in deep crustal recycling in the Mesoarchean  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12762, https://doi.org/10.5194/egusphere-egu24-12762, 2024.

EGU24-12921 | Posters on site | GD3.1 | Highlight

Earth’s early tectonic modes and implications for habitability 

Peter Cawood and Priyadarshi Chowdhury

Tectonic mode manifests how a planet’s interior is cooling, and it encompasses all the geological activities (e.g., magmatism, deformation, metamorphism, sedimentation) that characterize the planetary body. Tectonic processes exert first-order control on factors key to planetary habitability (e.g., Southam et al., 2015). For example, tectonic mode controls the long-term prevalence of surface oceans, the sustenance of physicochemical conditions (e.g., temperature) favourable for metabolic activity, fluxing of elements in and out of the planet’s interior and thereby, the availability of bio-essential nutrients (e.g., C, O, H, N, P, S) (Cockell et al., 2016). However, all tectonic modes do not regulate these processes efficiently. For example, stagnant-lid mode restricts heat and material exchange between a planet’s interior and surficial reservoirs compared to plate tectonics. Further, certain factors determining a planet’s tectonic mode – like internal heat budget, mechanical behaviour of rocks, and volatile content – can vary with time, leading to the prevalence of different tectonic modes during planetary evolution. Thus, a planet’s habitability is critically intertwined with its tectonic evolution.

Modern Earth is the only known planet with plate tectonics, felsic crust, and life. Plate tectonics has resulted in a Goldilocks environment for long-term habitability via chemical cycling across the Earth system, regulating temperature through the carbonate-silicate cycle, sustaining oceans at the surface, and developing bimodal hypsometry with emergent felsic crust releasing bio-essential minerals through weathering and erosion. This has resulted in diverse habitats facilitating life’s complex phylogenetic tree. However, life initiated on Earth in the Hadean or early Archean when non-plate-tectonic modes like the stagnant- or squishy-lid modes are inferred to be prevalent (e.g., Cawood et al., 2022). Their potential to promote habitability is unknown, with few studies suggesting that they may lead to habitable conditions (e.g., Tosi et al., 2017). Nevertheless, our terrestrial planetary neighbours’ records suggest that such modes are unlikely to provide the environmental stability necessary to develop a long-term phylogenetic landscape. The geochemical cycling of elements through these modes may occur (e.g., via magmatism and episodic recycling of lithosphere) but is likely to be spatially and temporally discontinuous and limited, thereby limiting the supply of bio-essential nutrients and longevity of oceans on a planetary surface. As such, these modes inhibit a surficial environment in long-term dynamic equilibrium, leading to inhospitable habitats either through the development of a run-away greenhouse (e.g., Venus) or the loss of early atmosphere and oceans to space (e.g., Mars).

Thus, the tectonic evolution of Earth and its resultant habitability are a predictable consequence of its position, composition, size, and heat energy within the solar system. These conditions may serve as a template to search for exoplanet habitability; however, a degree of unpredictability will remain in knowing whether a similar set of planetary criteria would produce the same outcome.

References:

Cawood et al., 2022. Reviews of Geophysics, 60, e2022RG000789

Cockell et al., 2016. Astrobiology, 16(1), pp.89-117.

Southam et al., 2015. Planets and Moons, 10, pp.473-486.

Tosi et al., 2017. Astronomy & Astrophysics, 605, p.A71.

How to cite: Cawood, P. and Chowdhury, P.: Earth’s early tectonic modes and implications for habitability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12921, https://doi.org/10.5194/egusphere-egu24-12921, 2024.

The Limpopo Belt of southern Africa is a classical Paleoproterozoic orogenic belt that is believed to have resulted from the collision between the Kaapvaal and Zimbabwe Cratons. Previous studies have primarily focused on geochronology, petrology, and geochemistry of different rock assemblages, resulting in a general tectonic framework indicating at least two significant tectonothermal events from Mesoarchean to Paleoproterozoic. However, the spatial and temporal relationships between these events, as well as their overall structural patterns in the field, are poorly understood. The Central Limpopo Belt contains the best lithological exposures of different ages, making it the most promising area for detailed structural mapping and analysis, and for gaining a better understanding of these issues.
Based on the detailed field-based structural analyses, four generations of deformation were identified. The earliest D1 deformation is characterized by the penetrative S1 foliations only preserved within the 3.6-3.4 Ga anorthosites that now occur sporadically as xenoliths or boudins in the highly deformed 2.9-3.3 Ga Sand River gneiss. S2 are penetrative gneissic foliations that were extensively developed in the Sand River gneiss and were intensively superimposed by subsequent deformations into tight to isoclinal folds. After restoration of their attitude, S2 foliations strike NW-SE and dip steeply to SW at high angles, indicating that the D2 deformation experienced a roughly NE-SW-oriented compression between 2.9-2.6 Ga. D3 deformation resulted from significant NW-SE-oriented compression that intensively superimposed the earlier S2 fabrics into vertically inclined isoclinal folds and tectonites S3-L3. Strain measurements on these tectonites indicate that all pre-existing rock assemblages were stretched or sheared along the vertical orientation, resulting in the development of numerous sheath folds in the Sand River gneiss and 2.6-2.7 Grey gneiss. Associated with the zircon ages from anatexis melts, the D3 deformation most likely occurred at 2.1-2.0 Ga. SHRIMP U-Pb zircon age dating recorded these two metamorphic ages of ~2.6 Ga and 2.0 Ga on a single zircon of the foliated Sand River gneiss. A regional large scale inclined open fold F4 gently refolded the D1-D3 fabrics and marked the final deformation of the Central Limpopo Belt, occurring sometime after ~2.0 Ga. 
Detailed structural data of this study, in combination of available geochronological and metamorphic data lead us to propose that the ~2.65 Ga and ~2.0 Ga tectonothermal events occurred under different tectonic environments. The ~2.65 Ga tectonothermal event developed coevally with D2 deformation and high-grade metamorphism during the NE-SW collisional event. In contrast, the ~2.0 Ga tectonothermal event occurred during a NW-SE-oriented collisional event between the Kaapvaal and Zimbabwe Cratons, resulting in the formation of the major Limpopo tectonic linear belt seen today.

Acknowledgement
This work was financially supported by the National Natural Science Foundation of China (42025204) and National Key Research and Development Program of China (No. 2023YFF0803804).

 

How to cite: Zhang, J., Brandl, G., Zhao, G., Liu, J., and Zhao, C.: Deciphering a complex Neoarchean-Paleoproterozoic collisional history between the Kaapvaal and Zimbabwe Cratons: new constraints from polyphase deformation of the Central Limpopo Belt, southern Africa , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14565, https://doi.org/10.5194/egusphere-egu24-14565, 2024.

EGU24-16380 | ECS | Orals | GD3.1

Linking early Earth’s internal and external reservoirs: a change in oxygen fugacity of sub-arc magmas across the Great Oxidation Event 

Hugo Moreira, Craig Storey, Emilie Bruand, James Darling, Mike Fowler, Marine Cotte, Edgar E. Villalobos-Portillo, Fleurice Parat, Luís Seixas, Pascal Philippot, and Bruno Dhuime

Plate tectonics exerts a first-order control on the interaction between Earth’s reservoirs. Atmospherically-altered surface materials are recycled to the mantle via subduction, while volatiles from the mantle are liberated to the atmosphere via volcanism. This cycle regulates much of Earth’s climate, ocean levels and metallogenetic processes within the continental crust. However, the interplay between Earth’s atmospheric changes and the geochemical evolution of mantle-derived magmas has remained obscure for the ancient geological history. This has led to multiple conflicting models for the crustal evolution in the early Earth.

A time-integrated evolution of the mantle-crust-atmosphere-hydrosphere interaction is yet to be fully established. For instance, secular change of the ocean and atmosphere system is evident from several proxies but the feedback of these changes to magmatic and geochemical processes in the lithosphere remain unclear. Moreover, no clear consensus has been reached on the timing of modern-style plate tectonic initiation and the evolution of net growth of the continental crust.

To explain overt and cryptic global trends in the geochemistry of magmatic rocks, a better understanding of mineral reactions and how these control trace element evolution in magmas at the lithosphere-scale is paramount. For example, the elemental and isotopic composition of apatite inclusions hosted by zircon offers a way to better understand the evolution of magmas and, to some extent, the nature of magma sources. These proxies rely on the robust data acquisition of other isotope systems with different geochemical behaviour, such as U-Pb and Lu-Hf analyses in the host zircon crystal.

A combination of methods and proxies including the elemental composition of apatite via EPMA and the oxygen fugacity based on sulphur speciation via μ-XANES of apatite inclusions was applied to ancient sub-arc magmas formed in regions akin to modern subduction zones. These magmas share a common mantle source but crystallised more than 200 million years apart (at 2.35 and 2.13 billion years ago). Importantly, they bracket the Great Oxidation Event, when atmospheric oxygen levels increased by five orders of magnitude, causing a permanent and dramatic change in Earth’s surface chemistry. As such, these sub-arc magmas were investigated as potential tracers of the interaction between Earth’s atmosphere and the mantle.

The information from several inclusions from co-magmatic rocks can then be interpreted in the light of U-Pb, Lu-Hf, trace elements and oxygen isotope analyses of the host zircon grains. Altogether, the results show a shift in oxygen fugacity of sub-arc magmas across the Great Oxidation Event. The change in oxygen fugacity is thought to be caused by recycling into the mantle of sediments that had been geochemically altered at the surface by the increase in atmospheric oxygen levels. This study opens a wide window of opportunities for the time-integrated investigation of the interaction between atmosphere and oceans with the evolving terrestrial mantle.

How to cite: Moreira, H., Storey, C., Bruand, E., Darling, J., Fowler, M., Cotte, M., Villalobos-Portillo, E. E., Parat, F., Seixas, L., Philippot, P., and Dhuime, B.: Linking early Earth’s internal and external reservoirs: a change in oxygen fugacity of sub-arc magmas across the Great Oxidation Event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16380, https://doi.org/10.5194/egusphere-egu24-16380, 2024.

EGU24-18408 | Orals | GD3.1

Archean continental crust formed by melting mafic cumulates 

Matthijs Smit, Kira Musiyachenko, and Jeroen Goumans

Large swaths of juvenile crust with tonalite-trondhjemite-granodiorite (TTG) composition were added to the continental crust from about 3.5 billion years ago. Although TTG magmatism marked a pivotal step in early crustal growth and cratonisation, the petrogenetic processes, tectonic setting and sources of TTGs are not well known. Part of this issue is the general difficulty in disentangling the chemical effects of fractional crystallization and partial melting, which impedes constraining primitive melt compositions and, by extension, investigating source-rock lithology and composition. To investigate these aspects, we assessed the composition and petrogenesis of Archaean TTGs using high field-strength elements that are fluid immobile, uniformly incompatible, but differently compatible between various residual minerals. The Nb concentrations and Ti anomalies of TTGs show the overwhelming effects of amphibole and plagioclase fractionation and permit constraints on the composition of primary TTGs. The latter are relatively incompatible element-poor and characterised by variably high La/Sm, Sm/Yb and Sr/Y, and positive Eu anomalies. Differences in these parameters do not represent differences in melting depth, but instead indicate differences in the degree of melting and fractional crystallisation. Primary TTGs formed by the melting of rutile- and garnet-bearing plagioclase-cumulate rocks that resided in the roots of mafic proto-continents. The partial melting of these rocks likely was part of a causal chain that linked TTG magmatism to the formation of sanukitoids and K-rich granites. These processes explain the growth and differentiation of the Archean continental crust, without requiring external forcing such as meteorite impact or the start of global plate tectonics.

How to cite: Smit, M., Musiyachenko, K., and Goumans, J.: Archean continental crust formed by melting mafic cumulates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18408, https://doi.org/10.5194/egusphere-egu24-18408, 2024.

EGU24-19222 | ECS | Posters on site | GD3.1

Petrogenetic and Geochemical studies of Sittampundi Anorthosite Complex, Southern Granulite Terrain, India. 

Amandeep Kaur, Rajagopal Krishnamurthi, and Nachiketa Rai

The Sittampundi Anorthosite complex (SAC), in the Southern Granulite terrain of Peninsular India, is a layered Archean anorthosite comprising gabbroic rocks at the base overlain by leucogabbros and anorthosites interlayered with well-developed massive chromitites. The complex has been subjected to high-pressure granulite facies (800-900°C and 11-14 Kbar) metamorphism and later retrogressed to amphibolite-facies metamorphism (550-480°C and 5.5-4.5Kbar) during exhumation (Chatterjee et al., 2022). Detailed petrography, mineral chemistry as well as major and trace element geochemistry have been used to constrain its petrogenesis and geodynamic setting.

The presence of highly calcic plagioclase and igneous amphibole indicates that magma was quite hydrous in nature. Chromites are Fe-Al rich in nature, and on the differentiation diagram, they plot near to podiform chromites and supra-subduction zone setting. Geochemical trends in major and trace elements indicate that the gabbro, leucogabbro and anorthosites were derived from the fractionated magma. However, the mineral assemblage and chromite chemistry in chromitite indicate they formed due to magma mixing.  Based on experimental studies, the composition of plagioclase limits the pressure to 2-3kb and depth of crystallization to approximately 7-11 kilometres. The findings of this study indicate the hydrous magma parental to SAC originated in a subduction zone setting in the Neoarchean.

How to cite: Kaur, A., Krishnamurthi, R., and Rai, N.: Petrogenetic and Geochemical studies of Sittampundi Anorthosite Complex, Southern Granulite Terrain, India., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19222, https://doi.org/10.5194/egusphere-egu24-19222, 2024.

EGU24-19385 | Orals | GD3.1 | Highlight

The conceptual model of the formation of Earth’s habitability 

Yun Liu

The difficulty in direct differentiation of the felsic crustal components from Earth’s mantle peridotite leads to a requirement for the presence of a large amount of hydrated mafic precursor of TTG in Earth’s proto-crust, the origin of which, however, remains elusive. The mafic proto-crust may have formed as early as  4.4 Ga ago as reflected by the Hf and Nd isotopic signals from Earth’s oldest geological records, i.e., zircons. The Archean continents, primarily composed of the felsic tonalite–trondhjemite–granodiorite (TTG) suite, were formed or conserved since  3.8 Ga, with significant growth of the continental crust since  2.7 Ga. Such a significant time lag between the formation of the mafic proto-crust and the occurrence of felsic continental crust is not easily reconciled with a single-stage scenario of Earth’s early differentiation. 
Here, inspired by the volcanism-dominated heat-pipe tectonics witnessed on Jupiter’s moon Io and the resemblances of the intensive internal heating and active magmatism between the early Earth and the present-day Io, we present a conceptual model of Earth’s early crust-mantle differentiation and the formation of habitability, which involves the tremendous heat obtained by the Moon-forming giant impact. It  forces Earth to choose an Io-like tectonics, which can efficiently dissipate heat and extract a mafic proto-crust from the early mantle, then followed by an intrusion-dominating regime that could account for the subsequent formation of the felsic continents as Earth cools. The episodic heat-pipe tectonics destroy most of rocks formed during Hadean era. The cool and hard rock layer formed due to the heat-pipe tectonics is essential for the formation of habitability of the earth. By this way, the required conditions by a habitable Earth, e.g., adequate surface temperature, aqueous sphere, and towering mountains, etc., would be appeared within a surprisingly short time. Therefore, the Moon-forming giant impact is the most important reason to make a habitable Earth. It not only brought tremendous heat into Earth and forced Earth to choose the volcanism-dominated heat-pipe tectonics but also completely destroyed the proto-atmosphere to avoid over-heated situations occurred like that of Venus at present. 

How to cite: Liu, Y.: The conceptual model of the formation of Earth’s habitability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19385, https://doi.org/10.5194/egusphere-egu24-19385, 2024.

EGU24-21184 | Orals | GD3.1

A widespread, short-lived, off-craton subduction source for hidden crustal growth in Earth’s infancy 

Eric Vandenburg, Oliver Nebel, Peter Cawood, Fabio Capitanio, Laura Miller, Marc-Alban Millet, and Hugh Smithies

The scarce geological record of Earth’s infancy, particularly before 3 billion years ago (Ga), is restricted to cratons, many of which likely originated as volcano-plutonic plateaus in a non-mobile lid geodynamic regime. However, this scarcity is at odds with the significant volumes of continental crust at 3 Ga that multi-proxy models of mantle depletion and crustal growth predict. This challenges the notion that plateau-type cratonic nuclei represent the predominant tectonomagmatic settings operating on the early Earth. Reconciling this paradox necessitates a “silent majority” of missing off-craton Archean crust of an uncharacterized affinity.

To investigate a potential rare remnant example of an Archean crust constructed away from cratonic nuclei, we report major and trace-element chemostratigraphic data from the 3.1 Ga Whundo Group of the Pilbara Craton, investigating the petrogenetic processes related to its formation. These data reveal three magmatic cycles of intercalated supracrustal successions comprising six groups: tholeiites, boninites, calc-alkaline BADR (basalt-andesite-dacite-rhyolite), high-magnesium ADR (including a subset of transitionally adakitic affinity), Nb-enriched basalts (NEB), and boninite-calc-alkaline hybrids. Th/Yb-Nb/Yb, Gd/YbN-Al/TiN, and Nd isotope systematics are inconsistent with contamination by felsic basement characteristic of cratonic cores, suggesting eruption onto thin, juvenile lithosphere that was only later incorporated into the Pilbara Craton.

How to cite: Vandenburg, E., Nebel, O., Cawood, P., Capitanio, F., Miller, L., Millet, M.-A., and Smithies, H.: A widespread, short-lived, off-craton subduction source for hidden crustal growth in Earth’s infancy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21184, https://doi.org/10.5194/egusphere-egu24-21184, 2024.

CL1.2 – Past Climate - Last ~2.6 Ma

EGU24-4 | ECS | Orals | CL1.2.1

Australian Precipitation Extremes over the last Millenia: How do Ephemeral Lake Records Compare Against Climate Models? 

Sophie Grunau, Tim Cohen, Helen McGregor, and Caroline Ummenhofer

The flooding in Queensland and NSW over the last years has affirmed the impacts that extreme precipitation has on peoples lives and their livelihood. To be better prepared for such extremes in the future we need to know how often and under which climatic circumstances they occur. However, climate models for Australia still involve high uncertainty in predicting the likelihood of precipitation extremes that lead to large flooding events. This is attributed to the limited record of hydro-climatic paleo data across Australia. Though efforts have been made to improve the record of past precipitation extremes, previous studies have focused on high resolution at specific locations rather than a large spacial coverage.

Our project tackles this challenge by utilising the strongly link between precipitation and filling events of ephemeral lakes. The paleoenvironmental evidence collected from various ephemeral lakes in key quadrants of the country allows the establishment of a hydro-climatic paleo record on a large spatial scale. A timeframe of the last thousand years permits the comparison of frequency and magnitude to inter-annual variability of precipitation extremes in different regions across Australia. Ultimately, a comparison of the established record against other paleo data and an analysis of global climate simulations will result in an improved understanding of past precipitation extremes and the importance varying climatic drivers have in different regions across Australia.

How to cite: Grunau, S., Cohen, T., McGregor, H., and Ummenhofer, C.: Australian Precipitation Extremes over the last Millenia: How do Ephemeral Lake Records Compare Against Climate Models?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4, https://doi.org/10.5194/egusphere-egu24-4, 2024.

EGU24-99 | ECS | Orals | CL1.2.1 | Highlight

Reconstruction of floods in Poland in the pre-instrumental period (1001-1800) 

Babak Ghazi, Rajmund Przybylak, Piotr Oliński, and Aleksandra Pospieszyńska

A reconstruction of historical floods in Poland in the 11th–18th centuries was carried out based on a comprehensive database of documentary evidence. For this period, we collected more than 1700 weather notes describing floods. The quality of each source containing weather notes was estimated. Only the most reliable sources were used for the analysis of flood occurrences and their characteristics. For the classification of flood intensity, the two most commonly used propositions for European rivers (Barriendos and Coeur 2004; Brázdil et al. 2006) were used. The origins of floods were evaluated based on the classification presented by Lambor (1954). The results showed that the highest number of floods in Poland in the study period occurred in the 16th century (294 cases). The number of floods in the 11th–15th, 17th, and 18th centuries were 166, 284, and 272, respectively. Most of the floods were recorded in the Oder River basin and Silesia region (western and south-western Poland). The evaluation of the intensity of floods revealed that most of the floods belong to the “above-average, or supra-regional flood” category according to the Brázdil et al. (2006) classification and the “extraordinary” category for the Barriendos and Coeur (2004) classification. The assessment of the main origin of floods demonstrated that rain and its sub-types (torrential, frontal, long-lasting, territorially widespread) constituted the main cause of floods in Poland in the 11th–18th centuries. The findings of this study will improve existing knowledge of historical hydrology in Europe and Poland before the 19th century. 

The work was supported by the National Science Centre, Poland, project No. 2020/37/B/ST10/00710. 

References:

Barriendos, M., Coeur, D, 2004: Flood data reconstruction in historical times from non-instrumental sources in Spain and France. Systematic, Palaeoflood and Historical Data for the Improvement of Flood Risk Estimation. Methodological Guidelines. 

Brázdil, R., Kundzewicz, Z. W., & Benito, G., 2006: Historical hydrology for studying flood risk in Europe. Hydrological Sciences Journal, 51(5), 739–764.

Lambor, J., 1954: Klasyfikacja typów powodzi i ich przewidywanie. Gospodarka Wodna, 4, 129–131.

How to cite: Ghazi, B., Przybylak, R., Oliński, P., and Pospieszyńska, A.: Reconstruction of floods in Poland in the pre-instrumental period (1001-1800), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-99, https://doi.org/10.5194/egusphere-egu24-99, 2024.

EGU24-1255 | ECS | Posters on site | CL1.2.1 | Highlight

Bridging History and Climate Science - ClimeApp: Data processing tool for the ModE-RA Global Climate Reanalysis 

Richard Warren, Niklaus Bartlome, and Noémie Wellinger

ClimeApp is a newly developed web-based processing tool for the state-of-the-art ModE-RA climate reanalysis. It presents temperature, precipitation and pressure reconstructions with global coverage and monthly resolution over the last 600 years. The app allows integration of historical information with climate data through composite, correlation and regression functions. The ModE project itself contains not one, but three experiments - ModE-RA, ModE-Sim and ModE-RAclim – all accessible through the app. These integrate a huge array of source material and allow the separation of the effects of external and internal forcing on the climate system in unprecedented ways. The app is designed to allow quick data processing for climatologists and easy use for non-climatologists. Specifically, it aims to help bring climate into history, where climatological data still has huge potential to advance historical research. This poster demonstrates the functions and applications of ClimeApp and the ModE-RA reanalysis. It also summarises opportunities for creating similar interfaces in other disciplines. 

ClimeApp is available at http://climeapp-modera.unibe.ch:3838/

How to cite: Warren, R., Bartlome, N., and Wellinger, N.: Bridging History and Climate Science - ClimeApp: Data processing tool for the ModE-RA Global Climate Reanalysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1255, https://doi.org/10.5194/egusphere-egu24-1255, 2024.

EGU24-1378 | ECS | Posters on site | CL1.2.1

Assimilation of Written Climate and Weather Records into Paleoclimate Reanalysis using a Non-Linear Forward Model 

Patrick Cho, Marc Müller, and Diogo Bolster

Recent reanalysis products offer unprecedented insights on past climates, but the paleoclimatic proxies that they assimilate are unevenly distributed in space leading to substantial simulation uncertainties over certain regions. In that context, written climate and weather records -- or docu proxies --  covering the past 2,000 years offer promising insights to complement natural proxies. However, docu proxies are also subject to a range of biases and error sources, for instance related to the cultural, technological background of the author and the prevailing need to convert qualitative observation to quantitative data assimilation input. These challenges require careful consideration when assimilating docu proxy into climate products, many of which employ a Bayesian Hierarchical approach with a forward model intended to translate climate models' initial estimates into a space that is compatible with the (natural or docu) proxy. Currently, docu proxy assimilation uses multivariate linear models for this transition, but the presence of perception biases within docu proxies suggests that linearity assumptions may not be suitable. To address this, we propose a non-linear forward model that better replicates docu proxy characteristics, aiming for more accurate assimilation. Leveraging the DOCUCLIM database and Last Millennium Reanalysis, we assess the efficacy of this non-linear approach.

How to cite: Cho, P., Müller, M., and Bolster, D.: Assimilation of Written Climate and Weather Records into Paleoclimate Reanalysis using a Non-Linear Forward Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1378, https://doi.org/10.5194/egusphere-egu24-1378, 2024.

EGU24-1508 | Posters on site | CL1.2.1

Late Holocene lake ecosystem change and the Southern Hemisphere Westerlies on sub-Antarctic Macquarie Island 

Yuqiao Natalie Deng, Stephen J. Roberts, Krystyna M. Saunders, and Bianca Perren

The Southern Hemisphere Westerlies (SHW) are the world’s strongest zonal surface winds, and they profoundly influence ocean-atmospheric CO2 exchange, southern mid-latitude precipitation patterns and ocean-cryosphere dynamics. Stronger and more poleward-shifted SHW over the last few decades have been linked to anthropogenic warming and increased Southern Ocean ventilation and CO2 outgassing. A more in-depth understanding of past natural SHW variability is required to investigate the SHW response to future, anthropogenically impacted climate change scenarios (e.g., IPCC2023). Macquarie Island (54°30’S, 158°57’E) is located in the Southern Ocean within the SHW core belt, providing an ideal location for reconstructing past changes in the SHW. A strong and decreasing west-east conductivity gradient exists in lakes across the island due to the input of westerly wind-blown sea spray. Moreover, since diatom species present in surface sediments from these lakes are strongly determined by conductivity, we reconstructed variations in the SHW over the last 3000 years using a sediment record from Lake Tiobunga on the west coast. Decreases in the sediment accumulation rate and the dominant, low-conductivity Psammothidium taxa imply that the SHW over Macquarie Island were relatively stronger between ~3000–2300 cal BP and in the last thousand years. Conversely, an increase in Psammothidium taxa implies weaker SHW ~2300–1000 cal BP. Superimposed on these longer-term trends are centennial-scale fluctuations and a dramatic increase in diatom production after 1900 CE, which we associate with the well-documented invasive rabbit infestation. Our results provide a record and improve the understanding of the complex SHW atmospheric system for the last few millennia in the Pacific sector of the Southern Ocean.

How to cite: Deng, Y. N., Roberts, S. J., Saunders, K. M., and Perren, B.: Late Holocene lake ecosystem change and the Southern Hemisphere Westerlies on sub-Antarctic Macquarie Island, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1508, https://doi.org/10.5194/egusphere-egu24-1508, 2024.

EGU24-2450 | Orals | CL1.2.1

Climate and environmental changes during the past 1,500 years in Altai, Western Siberia, Russia: elemental geochemistry from four lake cores 

Hong-Chun Li, Dilyara Kuzina, Larisa Frolova, Tzu-Tsen Shen, Satabdi Misra, Gulnara Nigamatzyanova, Anastasiya Yusupova, Niyaz Nigmatullin, Vera Strakhovenko, and Danis Nurgaliev

Gravity cores of four lakes along a NE to SW transect in Altai Mountains, from Shira Lake to Manzherok Lake, to Beloye Lake and Kolyvanskoye Lake, have been precisely dated by 210Pb, 137Cs and AMS 14C methods. High-resolution measurements of TOC and TON by EA, and 0.5N HCl leaching (AL) and Aqua Regia dissolved (AR) elemental concentrations by ICPOES reveal lake productivity, salinity, pH, redox condition and surface runoff under climate change and human impact over the past 1500 years. All of the lake sediments contain high sedimentary organic matter (average TOC >5%). However, 14C dating on the TOC as well as aquatic plants show old carbon influence (OCI). In order to obtain correct chronology of the cores, it is necessary to make high-resolution 14C dating. Using the least OCI 14C ages and combing 210Pb/137Cs dating results, a reliable chronology of the sediment core can be established. The AL fraction reflects mainly changes in lake chemistry, whereas the AR fraction represents chiefly variations in terrigenous input. The AL Ca and Sr are indicators of lake salinity, alkalinity and pH, whereas the AL Mo, Fe and Al are indicators of redox condition of the lake. TOC% and C/N are proxies for lake productivity and exogenous/endogenous TOC ratio. The AL Zn and Pb concentrations shows human impact. Based on the four lake records, the climatic conditions during the past 1500 years can be identified: warm and wet during 1500~1100 cal yr BP; warm and wet during 1100~900 cal yr BP (Medieval Warm Period -- MWP); fast sedimentation rate due to strong surface runoff during 900~700 cal yr BP; cooling and drying climates during 700~500 cal yr BP; very slow sedimentation due to longer frozen surface under cold climates during 500~50 cal yr BP (Little Ice Age -- LIA).  Since AD1900, the lakes were started to resume lake productivity under warming climate with the smaller lake first, being Manzherok (0.4 km2) in AD1900, Beloye (2.97 km2) in AD1920, Kolyvanskoye (4.5 km2) in AD1940, and Shira (39 km2) in AD1950.

This study is supported by the Russian Science Foundation (RSF) (grant No.22-47-08001) to Kazan Federal University (KFU).

How to cite: Li, H.-C., Kuzina, D., Frolova, L., Shen, T.-T., Misra, S., Nigamatzyanova, G., Yusupova, A., Nigmatullin, N., Strakhovenko, V., and Nurgaliev, D.: Climate and environmental changes during the past 1,500 years in Altai, Western Siberia, Russia: elemental geochemistry from four lake cores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2450, https://doi.org/10.5194/egusphere-egu24-2450, 2024.

The project ROPEWALK, funded by the AP Møller Mærsk Fund, is a joint initiative of the Danish National Archive and the Danish Meteorological Institute over the period 2023-2026. The aim of the project is to digitize and transcribe all weather observations in ship journals and logbooks stored in the Danish National Archive.

A huge amount of data (more than 750 shelf metres) is stored in the archive, beginning as early as the 1680s. With the exception of the Napoleonic wars and the Danish state bankruptcy in 1814, the data is complete. In the archive, logbooks from Danish ships over large parts of Northern Hemisphere are found. Of particular interest are observations from two regions, the Øresund and Greenland:

In connection with the Sound duties which every ship passing the sound or belts had to pay between 1426 and 1857, weather observations were made on board of war ships placed at strategic locations near Copenhagen, Helsingør and Nyborg. These ships had to ensure that no one passed without paying the duties. Weather observations on board of these ships were tabulated starting as early as the first half of the 18th century,  and in several cases, observations were conducted every time the ship bell was struck, resulting in as many as 48 observations in the course of one day. For the oldest logbooks, which are in free text rather than in tabular form and go back to the Little Ice Age, we could locate transcriptions which are much easier to read than the original data.

The other group of logbooks which are of particular interest are from voyages to the colonies, in particular to (western) Greenland. The Greenlandic Trade Company had a monopoly for commerce with Greenland for nearly 200 years, and foreign ships would not be allowed to call a port. These "Greenland Voyages" were conducted several times per year.

In many cases, detailed sea ice observations, both from the Øresund region and the Greenland voyages, have been conducted.

The scanning of the original logbooks and journals by the National Archive in highest possible resolution is now almost complete. We have therefore initiated the transcription of the scanned documents by means of machine learning. We will present first results of this analysis.

All transcribed data will be made publicly available and can be used for future research or as input for reanalysis projects. 

How to cite: Stendel, M., Kronegh, A. J., and Skov, E. H.: ROPEWALK (Rescuing Old data with People's Efforts: Weather and climate Archives from LogbooK records) - a digitization project for three centuries of weather observations on board of Danish ships  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2830, https://doi.org/10.5194/egusphere-egu24-2830, 2024.

Some classic approaches to climate reconstruction, such as employing transfer functions, have stringent requirements for the quality and continuity of historical records. As a result of limited data sources and complex topography, it’s hard to estimate the winter temperature in southwest China. However, the Bayesian approach allows integrating probabilities into the temperature indices and assimilating documentary information with different uncertainties with climate modeling data. Some gap years with less or even absent information in narrative sources could also be evaluated.

Based on Bayes’ theory, a large-scale simulation ensemble containing 20 members called ModE-Sim serves for the estimate of prior atmospheric states. The documentary data, including abnormal phenomena records in the local history and official reports of precipitation, contain various information on snow, rainfall, flower phenomena, and personal feelings. They are used to generate Indices from extremely cold to warm as well as the associated likelihood of each winter and contribute to the reconstruction of the posterior probability. Finally, a series of winter temperature with uncertainty in southwest China during the 18th-19th century is generated from the prior and posterior probability.

This new 200-yr reconstruction in this study fits well with an independent dataset called ModE-RA, which is a global monthly reanalysis also employing ModE-Sim as the background state of the atmosphere. The cold winters of 1700/1701, 1783/1784, 1809/1810, and 1892/1893 and the cold late 19th century are expressed in this reconstruction. This study presents a new application of the Bayesian approach in the historical climatology field and has the potential to contribute to the analysis of large-scale circulation in past winters in China.

How to cite: Chen, S. and Brönnimann, S.: A winter temperature reconstruction based on the Bayesian approach in southwest China during the 18th-19th century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4774, https://doi.org/10.5194/egusphere-egu24-4774, 2024.

EGU24-5249 | Posters on site | CL1.2.1

The Pacific Decadal Oscillation modulates global temperature trends since the mid-18th century 

Tao Han, Zhiang Xie, Jianglin Wang, Jun Hu, Zhe Wang, and Hong Yan

The Pacific Decadal Oscillation (PDO) plays a crucial role in global decadal climate variability. However, large discrepancies persist in the determination of pre-industrial PDO variability derived from terrestrial proxy records. Here we reconstruct the PDO variability for the period 1746–2003 using a network of annually resolved marine proxy records from the extratropical North Pacific. Our PDO reconstruction (PDOrec) provides evidences for the persistent decadal variability and tropical-extratropical interactions over the North Pacific. Superposed epoch analysis does not detect a significant response of PDOrec to major volcanic eruptions, underscoring the dominant role of internal variability. Decadal changes in global temperature trends were found to correspond to PDOrec for the period 1746–2003, indicating that the decadal changes in global temperature trends do not arise solely from external forcing, and may be instead modulated by internal variability.

How to cite: Han, T., Xie, Z., Wang, J., Hu, J., Wang, Z., and Yan, H.: The Pacific Decadal Oscillation modulates global temperature trends since the mid-18th century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5249, https://doi.org/10.5194/egusphere-egu24-5249, 2024.

EGU24-5908 | Posters on site | CL1.2.1

Surface Mass Balance of the Antarctic Megadune Plateau 

Jacek Bursztynowicz, Joel Savarino, Benjamin Daviet, Patrick Ginot, Emmanuel Le Meur, Elsa Gautier, Julien Witwicky, Lenneke Jong, Andrea Spolaor, and Barbara Stenni

The East Antarctic Plateau contains particular areas with megadunes and wind-glazed surfaces, exhibiting distinct patterns of snow accumulation and its variability over time and space. Despite its significance for sea levels, ocean circulation, and weather patterns, knowledge about snow accumulation in these areas remains limited. Several ice cores, coming from diffrent parts of Plateau, were drilled during the East Antarctic International Traverse (EAIIST).

Using volcanic horizons as time markers, coupled with ground-penetrating radar (GPR) measurements, we intend to reconstruct the surface mass balance (SMB) of the megadune plateau in both time and space for the last ca. 2000 years where accumulation is largely unknown. In a first step, geochemical profiles of the different cores were analyzed. A critical analysis is first conducted to find the best marker of the volcanic eruptions between the electrical conductivity, the total sulfur concentration and the sulfate profile. Based on this critical analysis, a common volcanic-dating scale is proposed for the different drilling sites. However, the megadune areas show a strong disturbed layering accumulation with clearly visible ablated layers, making the volcanic identification a true challenge.  Work is currently underway to use volcanic cryptotephra and electron microprobe analysis to unambiguous determine the volcanic tie-point identification. In a subsequent step, GPR data will be process to spatialize the accumulation information. Matching radar internal layers with well-dated ice core reference layers will allow for dating and deducing the surface mass balance over time for the entire EAIIST transect.

How to cite: Bursztynowicz, J., Savarino, J., Daviet, B., Ginot, P., Le Meur, E., Gautier, E., Witwicky, J., Jong, L., Spolaor, A., and Stenni, B.: Surface Mass Balance of the Antarctic Megadune Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5908, https://doi.org/10.5194/egusphere-egu24-5908, 2024.

Reconstructing and analysing the climate of the past millennium has traditionally involved using statistical methods to calibrate annually resolved proxies. It also increasingly requires analysing large data sets from ensembles of long climate simulations and paleoclimate reanalysis. The accurate annual dating of most proxies and the increasingly large data sets make machine-learning methods an attractive tool to re-calibrate proxy records and investigate the causality of past climate variability, e.g. extreme events. The available log climate simulations also offer a pre-training data set for other machine-learning applications in climate research, for which the observational records are usually too short.

 

In this talk, I will present a few examples of the application of machine-learning methods to these goals.  Climate reconstructions based on annually resolved proxies can now be produced with methods (Gaussian Process Regression or Long Short Term Memory Networks) that can better preserve the statistical properties of the target variable, like the past amplitude of variations and serial autocorrelation. Causality analysis of past variability episodes, including extremes, can be investigated in climate simulations with  Random Forest and Layerwise Relevance Propagation in neural networks. Finally, data assimilation methods, which blend proxy and model data into a single reconstruction, can be augmented with methods of the family of K-Nearest-Neighbour, thereby also providing an attribution of past climate episodes to one external forcing.  

How to cite: Zorita, E.: Application of machine-learning methods to the climate of the past millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6471, https://doi.org/10.5194/egusphere-egu24-6471, 2024.

EGU24-6686 | ECS | Posters on site | CL1.2.1

Shedding light on the devastating floods in June 1897 in Romania: early instrumental observations and synoptic analysis 

Viorica Nagavciuc, Monica Ionita, Marius Beudean, and Irina Nagavciuc

Information about past floods and historical precipitation records is fundamental to the management of water resources, but observational records usually cover only 100–150 years. Using several different data sources, such as newly digitized meteorological data from several stations in the south-eastern part of Romania, historical newspapers of that time, and daily reanalysis of large-scale data, here we provide a detailed analysis of the atmospheric circulation conditions associated with one of the most devastating flood events which took place in June 1897. The floods in June 1897 were one of the most devastating natural disasters in Romania's history and they were caused by heavy rainfall that started at the beginning of May and continued for several weeks, resulting in widespread flooding, especially in the eastern part of the country. The most affected areas were the cities of Braila of Galati, located on the main course of the Danube River, where the floods caused extensive damage to infrastructure, including homes, bridges, and roads, and disrupted transportation and communication networks. The heavy rainfall events occurring in June 1897 and the associated flood peak were triggered by intrusions of high Potential Vorticity (PV) anomalies toward the southeastern part of Europe, persistent and pivotal cut-off lows over the analyzed region, and increased water vapor transport over the south-eastern part of Romania. We argue that digitizing and analyzing old meteorological records enables researchers to better understand the Earth's climate system and make more accurate predictions about future climate change. 

How to cite: Nagavciuc, V., Ionita, M., Beudean, M., and Nagavciuc, I.: Shedding light on the devastating floods in June 1897 in Romania: early instrumental observations and synoptic analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6686, https://doi.org/10.5194/egusphere-egu24-6686, 2024.

The transitional zone of the Mexican Pacific is a complex region in terms of its oceanographic conditions. This leads to changes in primary and exported productivity over various time scales. This study employs geochemical tracers—organic carbon (CO), biogenic opal, and calcium carbonate—to assess sedimentary records' primary and exported productivity. Analyzing responses to past warm periods is crucial for understanding marine productivity in future climate change scenarios. The objective of the present study was to quantify organic carbon content and to infer changes in primary and exported productivity in the transitional zone of the Mexican Pacific for the late Holocene and the final part of the middle Holocene. The sediment core, collected at a depth of 680 meters on the southwestern margin of Baja California Sur. It has a length of 137 cm and was sectioned at intervals of 1 cm, representing 137 samples. The estimated age from ¹⁴C was 5466 years. Each one-centimeter interval denotes 33 years. CO analysis used a COSTECH 4010 elemental analyzer with 0.2% analytical accuracy, employing BBOT and Urea certified standards. Biogenic opal determination follows the molybdenum blue spectrophotometric method by Mortlock and Froelich (1989). CO content ranged from 8% and 14%, showing periodic changes at ~300, ~170, and ~100 years. Biogenic opal ranged from 0.2 to 19.3%, with abrupt changes at ~310, ~270, and ~70 years. Organic carbon and biogenic opal exhibited a positive correlation, indicating increased productivity during warm periods like the Roman Warm Period (1800 to 2200 years ago) and the Medieval Warming Period (700 to 1100 years ago). This suggests responsiveness to oceanographic conditions across various time scales.

How to cite: Acevedo, T. and Sánchez, A.: Analysis of Primary Productivity Variability in the Transitional Zone of the Mexican Pacific during the Late and Middle Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6704, https://doi.org/10.5194/egusphere-egu24-6704, 2024.

EGU24-6923 | Orals | CL1.2.1

Stability of ENSO teleconnections during the last millennium in CESM 

Xue Han, Yanjie Li, Fei Liu, Jinbao Li, Xiaotong Zheng, Yan Li, and Licheng Feng

The El Niño-Southern Oscillation (ENSO) has a significant impact on the global climate through atmospheric teleconnections. It is important to understand the stability of ENSO teleconnections, not only for future weather forecasting and climate projection, but also for ENSO reconstructions based on paleo-proxies. In this study, we investigate the decadal variations of ENSO teleconnections in global land surface temperature (LST) from 850 to 2005 AD using 13 ensemble members of the Community Earth System Model-Last Millennium Ensemble (CESM-LME). The CESM can simulate the main Eurasian cooling and Arctic warming, known as the warm Arctic-cold Eurasia (WACE) pattern, during the boreal winter of an El Niño. Furthermore, it can also capture the western Antarctic warming during the developing and decaying summers of an El Niño. There is a dominant decadal variation in the ENSO-LST teleconnections, expressed as anomalous LST patterns that closely resemble those seen in the WACE pattern during boreal winter and the western Antarctic warming pattern during summer. This decadal variation of ENSO-LST teleconnections is primarily due to the varying positions of Rossby wave sources associated with distinct ENSO patterns, which are located either to the west or to the east of Hawaii. The LST response to ENSO over South Siberia, as well as the associated precipitation response over North Eurasia, even show opposite patterns at different phases of the decadal variation. The decadal variation in CESM is found to be related to the interdecadal Pacific oscillation (IPO) and is likely attributed to internal variability rather than external forcing. Our findings suggest that the decadal variation in ENSO teleconnections should be considered when using proxies from Eurasian regions to reconstruct ENSO variability.

How to cite: Han, X., Li, Y., Liu, F., Li, J., Zheng, X., Li, Y., and Feng, L.: Stability of ENSO teleconnections during the last millennium in CESM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6923, https://doi.org/10.5194/egusphere-egu24-6923, 2024.

EGU24-7024 | ECS | Posters on site | CL1.2.1

Dryland hydroclimatic response to large tropical volcanic eruptions during the last millennium 

Shangrong zhou, Fei Liu, Aiguo Dai, and Tianbao Zhao

Drylands are highly vulnerable to climate change due to their fragile ecosystems and limited ability to adapt. In contrast to the global drying after tropical volcanic eruptions shown previously, we utilize the last millennium simulations to demonstrate that large tropical volcanic eruptions can induce significant two-year hydroclimatic wetting over drylands. During this wetting period, which extends from the first to the third boreal winter after the eruption, several hydroclimatic indicators, such as self-calibrating Palmer Drought Severity Index based on the Penman-Monteith equation for potential evapotranspiration (scPDSIpm), standard precipitation evapotranspiration index (SPEI), aridity index (AI), top-10cm soil standard precipitation evapotranspiration index (SPEI), aridity index (AI), top-10cm soil drylands. The primary contribution to the wetting response is the potential evapotranspiration (PET) reduction resulting from dryland surface cooling and reduced solar radiation, as well as a weak contribution from increased precipitation. The latter is due to the wind convergence into drylands caused by slower tropical cooling. This dryland wetting response to volcanic eruptions is encouraging news for stratospheric sulfur aerosol injection, which mimics the cooling effect of volcanic eruptions for combating global warming.

How to cite: zhou, S., Liu, F., Dai, A., and Zhao, T.: Dryland hydroclimatic response to large tropical volcanic eruptions during the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7024, https://doi.org/10.5194/egusphere-egu24-7024, 2024.

Historically, climate change has played an important role in shaping human societies. Understanding past climate change is essential for human adaptation to future changes. Solar radiation, a key factor in Earth’s energy balance, hydrological cycle, and agricultural productivity, is crucial for understanding these changes. Our study focuses on reconstructing solar radiation from historical documents, shedding light on the historical impacts of climate variation and how past societies were influenced by and adapted to changing climate conditions.

In Japan, many historical documents, including daily weather records from the 17th to 19th centuries, have been key to understanding historical climate variations. Utilizing these descriptions, we developed a method for reconstructing solar radiation. This method enabled us to analyze solar radiation patterns from 1821 to 1850, providing valuable insights into climate variations and their socio-economic impacts during this period.

Our analysis, which focused on the 1830s Tempo Famine, revealed a clear relationship between climate variations and economic fluctuations. We found that the decrease in solar radiation during the summers of 1833, 1836, and 1838 corresponded with rising rice prices in Osaka, underscoring the impact on agricultural productivity and market dynamics.

These findings suggest that the solar radiation pattern in the summer of 1836 dramatically influenced the severe famine, as evidenced by the unusual rise in rice prices. This study refines the understanding of the historical climate impacts on society and highlights the broader effects of climate variation on agriculture and market economies. This emphasizes the need to integrate climate information into economic analyses and could provide valuable insights for developing contemporary climate change policies and adaptation strategies.

How to cite: Ichino, M., Masuda, K., Mikami, T., and Takatsuki, Y.: Abnormal Climate and the Market Economy: the Relationship between Reconstructed Solar Radiation and Rice Price during the Famine of 1830s in Japan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7122, https://doi.org/10.5194/egusphere-egu24-7122, 2024.

Although the influence of Sun on climate variability is largely investigated its contribution to extreme weather and climate change remains widely questioned. Because the sample sizes of observed weather and climate extremes are typically too small, we used seasonal resolution paleo-reanalysis data as predictors to extend back in time the field of observed climate extreme indices to reliably identify the solar signal. We reconstructed the field of a two-dimensional atmospheric blocking frequency indicator in the North Atlantic region as well as the field of the frequency of extreme cold temperature and extremely high precipitation days over Europe back to the year 1600. Based on these reconstructions, we show that low (high) solar irradiance winters are associated with more (less) frequent blocking in the Atlantic-European region. This pattern was particularly strong during Maunder and Dalton solar minima. Consistent anomaly patterns are identified for the frequency of extreme low temperature and extremely high precipitation days over Europe. A numerical experiment reveals a significant increase in the blocking frequency in the Atlantic-European region during a Grand Solar Minimum relative to the 1850s solar irradiance levels. This suggests that blocking anomaly patterns associated with total solar irradiance forcing during winter, as derived from observational data, are robust in the perspective of the last four hundred years of blocking and associated weather extreme variability in the North Atlantic region. Therefore, these patterns are useful to estimate the blocking and related weather extremes under various scenarios/predictions of total solar irradiance change during next decades/centuries.

How to cite: Rimbu, N., Spiegl, T., and Lohmann, G.: Atmospheric blocking and extreme weather frequency patterns associated with solar irradiance forcing during the last 400 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7818, https://doi.org/10.5194/egusphere-egu24-7818, 2024.

EGU24-8123 | Orals | CL1.2.1

Using a last 2k baseline to derive a first comprehensive assessment of industrial era land heat uptake 

Fidel González-Rouco, Félix García-Pereira, Camilo Melo-Aguilar, Norman Julius Steinert, Elena García-Bustamante, Philip de Vrese, Johann Jungclaus, Stephan Lorenz, Stefan Hagemann, Francisco José Cuesta-Valero, Almudena García-García, and Hugo Beltrami

The anthropogenically-intensified greenhouse effect causes a radiative imbalance at the top of the atmosphere. This in turn leads to an energy surplus of the Earth system, with the ocean component absorbing the greatest part and the land the second largest. The latest observational estimates based on borehole temperature profiles quantify the land contribution to the terrestrial energy surplus to be 6 % in the last five decades, whereas studies based on state-of-the-art climate models scale it down to 2 %. This underestimation stems from land surface models (LSMs) having a too shallow representation of the subsurface, which severely constrains the land heat uptake simulated by Earth System Models (ESMs). A forced simulation of the last 2000 years with the Max Planck Institute ESM (MPI-ESM) using a deep LSM captures about 4 times more heat than the standard shallow MPI-ESM simulations in the historical period, well above the estimates provided by other ESMs. However, deepening the MPI-ESM LSM does not affect the simulated temperature at the ground surface. As a consequence, it is shown that the land heat uptake values of ESMs with shallow LSM components can be corrected considering their simulated surface temperatures and propagating them with a standalone heat conduction forward model. This result is extended to all available ground surface temperature sources, such as observational data, reanalyses, and the latest generation of ESMs. This new approach yields values of 10-16 ZJ for 1971-2018, which are in close agreement with the values derived from the MPI-ESM deep simulation (12 ZJ), and relatively close to the latest borehole-based estimates (ca. 18 ZJ).

How to cite: González-Rouco, F., García-Pereira, F., Melo-Aguilar, C., Steinert, N. J., García-Bustamante, E., de Vrese, P., Jungclaus, J., Lorenz, S., Hagemann, S., Cuesta-Valero, F. J., García-García, A., and Beltrami, H.: Using a last 2k baseline to derive a first comprehensive assessment of industrial era land heat uptake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8123, https://doi.org/10.5194/egusphere-egu24-8123, 2024.

EGU24-9558 | ECS | Orals | CL1.2.1

Multiproxy analyses for a network of firn cores covering the last 40 years from coastal Adélie Land  

Titouan Tcheng, Elise Fourré, Léa Baubant, Coralie Lassalle-Bernard, Roxanne Jacob, Frédéric Parrenin, Olivier Jossoud, Frédéric Prié, Bénédicte Minster, Cécile Agosta, Christophe Leroy-Dos-Santos, Mathieu Casado, Marie Bouchet, Vincent Favier, Olivier Magand, Emmanuel Lemeur, Ghislain Picard, Alexandre Cauquoin, Martin Werner, and Amaelle Landais and the ASUMA RAID team

Water stable isotopes signals recorded in snow, firn and ice cores were successfully used to investigate past temperatures on glacial/interglacial scales (Jouzel and Masson-Delmotte 2010, Dansgaard, 1964). However, as evidenced by Goursaud et al. (2018) in coastal Adélie Land, many uncertainties hampered the interpretation of water isotope records at sub-annual to decadal resolution as a proxy of past temperature variations only (Goursaud et al. 2018). Condensation, sublimation and/or redistribution of snow triggered by strong katabatic winds as well as precipitation intermittencies, origin of moist air masses bringing precipitation and diffusion within firn lessen the representativity of a single isotopic profile to reconstruct past temperature in this region (Grazioli et al. 2017, Khale et al. 2018, Picard et al. 2019, Casado et al. 2020, Hirsch et al. 2023). In order to mitigate the non-representativity of a single isotopic profile, a solution consists in averaging several records to increase signal to noise ratios. However, to do so, it is necessary to provide a good correspondence between the different cores of interest.

In this study, we make good use of water stable isotopes and major chemistry records from 9 firn core (20 to 40m deep) drilled at 3 sites (so called D47, Stop5 and Stop0) during the ASUMA campaign. These sites display a high mean accumulation rate of about 250 mm.weq/year and a wide range of environmental conditions with elevation ranging from 1550m to 2460m, distance from coast ranging from 103km to 423km and different katabatic winds influence. In particular, we use the Paleochrono probabilistic model with water stable isotopes signal and major chemistry records coupled with beta-gamma and RADAR data to obtain the best correspondence between the different cores. We then quantify to what extent the stacking of several cores enable to increase the signal to noise ratio at the different sites and can provide a faithful record to document variations of the temperature and/or atmospheric water cycle over the last decades in this region.

How to cite: Tcheng, T., Fourré, E., Baubant, L., Lassalle-Bernard, C., Jacob, R., Parrenin, F., Jossoud, O., Prié, F., Minster, B., Agosta, C., Leroy-Dos-Santos, C., Casado, M., Bouchet, M., Favier, V., Magand, O., Lemeur, E., Picard, G., Cauquoin, A., Werner, M., and Landais, A. and the ASUMA RAID team: Multiproxy analyses for a network of firn cores covering the last 40 years from coastal Adélie Land , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9558, https://doi.org/10.5194/egusphere-egu24-9558, 2024.

EGU24-10475 | ECS | Posters on site | CL1.2.1 | Highlight

An assessment of long-term variability in the NAO, Azores High, and Iceland Low using North Atlantic winds from historical whaling ship logbooks and reanalyses 

Neele Sander, Caroline C. Ummenhofer, Bastian Münch, Tessa Giacoppo, Martin Visbeck, and Timothy D. Walker

The variability of climate and weather conditions in the North Atlantic and adjacent regions is dominated by multiple modes of climate variability, such as the Atlantic Multidecadal Variability and the North Atlantic Oscillation (NAO). The NAO is one of the region’s most recurrent patterns on interannual to decadal time scales and is often calculated as the pressure difference between the Iceland Low and the Azores High. However, few studies have focused on its centres of action independently, and uncertainties remain about the variations in the associated wind patterns prior to the 20th century. Here, we demonstrate that wind patterns obtained from US whaling ship logbooks from the 19th century from various New England archives align with the predominant wind patterns over the Atlantic region, thus providing invaluable insights into past North Atlantic climate. The logbook data reveals changes in wind speeds that correspond with shifts in the NAO phase and are also seen in reanalysis products. To better understand the NAO’s implications for the winds over the North Atlantic and the individual influences of the Azores High and Iceland Low, we created separate indices for their respective size and positions, allowing us to evaluate their individual behaviour and interactions. Those influences are again compared to the wind patterns provided by the whaling ship logbook data covering the period 1790-1910 CE. There is overall good agreement between the historical data and the reanalysis product, and all differences stay within the variability seen in the individual ensemble members of the reanalysis. Hence, the whaling ship logbook data could be a valuable source to further improve climate indices and thus lead to a better understanding of the long-term context of North Atlantic climate variability.

How to cite: Sander, N., Ummenhofer, C. C., Münch, B., Giacoppo, T., Visbeck, M., and Walker, T. D.: An assessment of long-term variability in the NAO, Azores High, and Iceland Low using North Atlantic winds from historical whaling ship logbooks and reanalyses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10475, https://doi.org/10.5194/egusphere-egu24-10475, 2024.

EGU24-10661 | ECS | Posters on site | CL1.2.1

Ice Borehole Thermometry: Paleo-Climate reconstruction using Bayesian modeling 

Kshema Shaju, Thomas Laepple, and Peter Zaspel

In the quest of understanding the past and present climate system, we aim to reconstruct paleo-climate using Bayesian inversion from Antarctic borehole temperature profiles. We aim to develop a refined process for reconstructing the temperature evolution of Antarctica over the last century and millennia. Initially, a forward heat transfer model is implemented that simulates borehole temperature profiles for time-dependent surface temperatures. The forward model provides an approximate notion of the borehole depth at which a signal from the past may be obtained. Using forward simulations, a greedy approach is employed for the optimal placement of temperature sensors in the borehole to record temperature effectively. We invert the forward model to reconstruct past surface temperature evolution from borehole temperature measurements. For this, we apply Bayesian inference to optimally account for the uncertainty in the various influencing quantities. We model known uncertainties as priors and obtain the reconstructed surface temperatures with connected uncertainty information.

How to cite: Shaju, K., Laepple, T., and Zaspel, P.: Ice Borehole Thermometry: Paleo-Climate reconstruction using Bayesian modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10661, https://doi.org/10.5194/egusphere-egu24-10661, 2024.

EGU24-10796 | ECS | Orals | CL1.2.1 | Highlight

The Use of a New Paleoclimate Archive to Reconstruct Holocene Sea-Ice Variability in the eastern Weddell Sea, Antarctica 

Claire Penny, Michael Bentley, Dominic Hodgson, and Erin McClymont

Proxies of paleoclimate are essential tools in reconstructing past Antarctic climates, understanding its natural climate variability, and providing context for change under future warming. Constraining past changes in Antarctic sea ice is particularly challenging, and current proxy records have significant temporal and spatial limitations1. Here, we report use of a new sea-ice proxy, namely the geochemical signature of prey remains preserved in snow petrel (Pagodroma nivea) stomach oil deposits.  

Antarctica’s relatively stable Holocene climate provided a backdrop for the establishment and development of modern ecosystems. Close to the margin of the East Antarctic Ice Sheet, the Theron Mountains provided one such ecological niche in the form of a snow petrel colony, estimated to have established approximately 6,000 years ago2. During each summer breeding season, snow petrel adults travelled towards the retreating sea-ice edge to hunt for food for their young, or towards areas of open water (polynyas). Prey species varied in proportion according to proximity to the continental shelf, whether proximal (fish), distal (krill) or within a polynya (increased proportion of fish)3. These dietary signatures are preserved in the form of lipid biomarkers within their fossilised stomach oil deposits, accumulated outside nest crevices during defensive regurgitation. The presence of this colony in the Holocene therefore offers a unique lens to examine the response of the Antarctic environment to fluctuating sea-ice conditions4. A multi-proxy methodology is employed here, comparing key elements and trace metals, fatty acid profiles and bulk isotopic (δ13C and δ15N) compositions. This study aims to address the uncertainties current paleoclimate proxies have, and our results show centennial-scale dietary fluctuations across the last 2,000 years in response to retreating sea-ice. We therefore offer a more comprehensive insight into reconstructing Holocene climate variability within the eastern Weddell Sea region of Antarctica.

1Collins, M., Knutti, R., Arblaster, J., Dufresne, J.-L., Fichefet, T., Friedlingstein, P., Gao, X., Gutowski, W. J., Johns, T., Krinner, G., Shongwe, M., Tebaldi, C., Weaver, A. J., and Wehner, M.: Long-term Climate Change: Projections, Commitments, and Irreversibility, in: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to 735 the Fifth Assessment Report of the Intergovernmental Panel on Climate Change edited by: Stocker, T. F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S. K., Boschung, J., Nauels, A., Xia, Y., Bex, V., and Midgley, P. M., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA., 2013.

2Berg, S., Melles, M., Hermichen, W.-D., McClymont, E. L., Bentley, M. J., Hodgson, D. A., & Kuhn, G. (2019). Evaluation of mumiyo deposits from East Antarctica as archives for the Late Quaternary environmental and climatic history. Geochemistry, Geophysics, Geosystems, 20(1), 260– 276.

3Barbraud, C., & Weimerskirch, H. (2001). Contrasting effects of the extent of sea-ice on the breeding performance of an Antarctic top predator, the snow petrel, Pagodroma nivea. Journal of Avian Biology, 32(4), 297– 302.

4Delord, K., Pinet, P., Pinaud, D., Barbraud, C., De Grissac, S., Lewden, A., et al. (2016). Species-specific foraging strategies and segregation mechanisms of sympatric Antarctic fulmarine petrels throughout the annual cycle. Ibis, 158(3), 569– 586.

How to cite: Penny, C., Bentley, M., Hodgson, D., and McClymont, E.: The Use of a New Paleoclimate Archive to Reconstruct Holocene Sea-Ice Variability in the eastern Weddell Sea, Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10796, https://doi.org/10.5194/egusphere-egu24-10796, 2024.

EGU24-11470 | Posters on site | CL1.2.1

An evaluation of the Southern Annular Mode in the Twentieth Century Reanalysis 

Julie Jones, Andrew Lorrey, Ryan Fogt, Laura Slivinski, Gilbert Compo, Phillip Brohan, and Gareth Marshall

We explore whether improvements to the Twentieth Century Reanalysis (20CR) in the most recent version (v3) have improved representation of the Southern Annular Mode (SAM).  The negative SAM index bias in the first half of the 20th century compared to instrumental SAM reconstructions in previous 20CR versions (due to a systematic high latitude high pressure bias) is still present. It is reduced in summer and autumn, but not in winter and spring.  Correlations between reanalysis and reconstructed SAM indices through the full series in all seasons do show improvements in v3 compared to previous versions.  

A reduction in SAM index ensemble spread is evident during periods with higher numbers of assimilated observations, in particular in summer and autumn.  Analysis of the spatial distribution of assimilated observations shows clear improvement in years/periods with greater numbers of ships observations in the Southern Ocean and Antarctic observations (e.g. early 20th century Antarctic expeditions).  However it is not until the advent of greater numbers of ships observations in the Southern Ocean and regular data from Antarctic meteorological stations in the late 1940s that there are enough high latitude observations to realistically constrain the reanalysis.  

Enhancements have been enough to improve how the reanalysis follows the observations temporally, highlighting the benefit of data rescue, but due to the bias, we recommend that the 20CR should still not be used for the analysis of long-term SAM trends, and caution should be exerted when using SLP data from the high latitude Southern Hemisphere from all 20CR versions prior to 1957.

How to cite: Jones, J., Lorrey, A., Fogt, R., Slivinski, L., Compo, G., Brohan, P., and Marshall, G.: An evaluation of the Southern Annular Mode in the Twentieth Century Reanalysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11470, https://doi.org/10.5194/egusphere-egu24-11470, 2024.

EGU24-12241 | Orals | CL1.2.1

New England whaling ship logbooks and reanalyses reveal shifts in global wind patterns since the late 1700s 

Caroline Ummenhofer, Neele Sander, Bastian Muench, Tessa Giacoppo, Tyson George, Milon Miah, and Timothy Walker

Maritime weather data contained in U.S. whaling ship logbooks are used to assess historical changes in global wind patterns. We focus on unexploited caches of archival documentation, namely U.S. whaling logbooks of voyages spanning the period 1790 to 1910 from New England archives housed by the New Bedford Whaling Museum, Nantucket Historical Association, and Providence Public Library. The logbooks, often covering multi-year voyages around the globe, contain systematic weather observations (e.g., wind strength/direction, sea state, precipitation) at daily to sub-daily temporal resolution. The qualitative, descriptive wind recordings of wind strength and direction by the whalers are quantified and compared with reanalysis products where applicable.

Following extensive quality control, we find overall good agreement in wind strength and direction for the whaling logbook wind records with reanalysis products for mean and seasonal climatologies. Variations in wind fields associated with modes of variability, such as the North Atlantic Oscillation or El Niño-Southern Oscillation, are also captured by the whaling ship recordings for North Atlantic and Pacific surface wind patterns. The quantified wind recordings are also employed to help address contemporary questions in climate science, such as long-term shifts in position and strength of the Southern Hemisphere westerlies since the late 1700s, strengthening of the Pacific equatorial trade winds since the 19th century, as well as changes in South Asian monsoon characteristics. Our results demonstrate that the historical records provide an important long-term context for changing maritime wind patterns in remote ocean regions lacking observational records during the 19th century.

How to cite: Ummenhofer, C., Sander, N., Muench, B., Giacoppo, T., George, T., Miah, M., and Walker, T.: New England whaling ship logbooks and reanalyses reveal shifts in global wind patterns since the late 1700s, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12241, https://doi.org/10.5194/egusphere-egu24-12241, 2024.

EGU24-12244 | Posters on site | CL1.2.1

Sensitivity and linearity of surface temperature response to solar irradiation changes 

Jan Sedlacek, Timofei Sukhodolov, Tatiana Egorova, and Eugene Rozanov

During the last millennia, prior to the industrialization, long-term climatic variations correlate with low-frequency total solar irradiance (TSI) changes. This long-term correlation does, however, not prove or disapprove a causal relationship. An additional natural forcing is the volcanic activity. The exact magnitudes of these two natural forcings are not known because reconstructions are based on proxy data which include substantial uncertainty. The Maunder Minimum, a period between roughly 1600 and 1700 A.D., is characterized by lower temperatures, low solar activity, and relatively high volcanic activity. There is still a debate on how forcing, i.e., solar vs. volcanic, influenced the climate and to which extend during that time. The amplitude of the TSI decrease is especially uncertain and suggestions range from a few W/m2 to a few tens of W/m2 lower than today’s value. Here we present simulations with the chemistry-climate model SOCOL where different solar forcings ranging from +10 W/m2 to -20 W/m2 in TSI terms are applied. On a global scale, changes in temperature are linear with changes in TSI. On a regional scale, however, the temperature response can be non-linear especially at high latitudes. The mechanisms leading to the non-linear behavior are explored.

 

How to cite: Sedlacek, J., Sukhodolov, T., Egorova, T., and Rozanov, E.: Sensitivity and linearity of surface temperature response to solar irradiation changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12244, https://doi.org/10.5194/egusphere-egu24-12244, 2024.

EGU24-12462 | ECS | Posters on site | CL1.2.1

Characterization and socioeconomic impacts of the late 19th Century drought episodes in Catalonia (NE Iberian Peninsula)   

Josep Barriendos, Mariano Barriendos, Salvador Gil-Guirado, Santiago Gorostiza, Juan Pedro Montávez Gómez, and Laia Andreu-Hayles

Recent droughts in the Mediterranean region are increasing concerns on the current and future water resources availability in this region. For this reason, studying the most severe droughts of the recent past and their associated societal responses is key to better characterise the current drought episode ongoing in Catalonia since 2021, as well as to properly define future adaptation strategies. One of these episodes of great magnitude and significant impact on economic and social activity were the droughts that occurred in Catalonia (North-East of the Iberian Peninsula) during the last third of the 19th century (1860-1890). Here, we analyse these droughts using data obtained from administrative documentary sources and instrumental meteorological records. Administrative sources were obtained from local civil and ecclesiastical authorities of eight different locations, as well as from one large irrigation community (Urgell’s Channel Irrigator’s Guild, since 1862). These historical documentary sources provide qualitative information at a daily resolution about drought impacts on the society. Together with the historical data, we also analyse different instrumental precipitation series using the Standardized Precipitation Index (SPI). This data provides a wider spatio-temporal perspective of drought behaviour for the entire Spanish territory during the study period. This study uses existing instrumental precipitation series for Spanish territory spanning from the mid-late 19th Century, with a total of 18 instrumental precipitation series obtained from INM (Spanish National Meteorology Institute). Additionally, we use 66 precipitation series in Spain obtained from the AEMET (Spanish Agency for Meteorology). This joint use of historical and instrumental data allows us to perform a spatio-temporal clustering of drought events to contextualize the intensity and persistence of the severe droughts occurring from1860 to 1890 in Catalonia. Finally, we complete the analysis of drought episodes examining their social impact, we also explore statistical data (Spanish State Statistical Year Books) from economic activities and other social variables.

How to cite: Barriendos, J., Barriendos, M., Gil-Guirado, S., Gorostiza, S., Montávez Gómez, J. P., and Andreu-Hayles, L.: Characterization and socioeconomic impacts of the late 19th Century drought episodes in Catalonia (NE Iberian Peninsula)  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12462, https://doi.org/10.5194/egusphere-egu24-12462, 2024.

EGU24-12754 | ECS | Posters on site | CL1.2.1

Regional effects of paleoclimate history on the subsurface temperature distribution in Germany 

Eskil Salis Gross, Maximilian Frick, Ben Norden, Sebastian G. Mutz, and Sven Fuchs

Knowledge of the underground temperature distribution is crucial for evaluating geothermal potential and ensuring the long-term safety of heat-producing waste in repositories. Previous research, mainly conducted in Northern Europe and Canada, has shown that the Pleistocene Glaciations have an additive effect, resulting in a cooling of several degrees Celsius at depths of up to two kilometers. Recent studies indicate that the Last Glacial Period and the recent warming of the past 100–150 years have the greatest paleoclimatic impact on the current shallow to medium depth subsurface temperature distribution in Germany. If thermophysical properties of the subsurface are known, the distribution of underground temperatures can also be used to reconstruct the local ground surface temperature history using borehole climatology. Ground surface temperature reconstructions have low temporal resolutions, but they are directly reconstructed from temperature measurements without the use of climate proxies. Observations of the subsurface temperature distribution are limited to boreholes that are undisturbed by drilling or operations like production tests. Furthermore, the coupling of ground surface temperatures and surface air temperatures presents a significant challenge due to complex and transient surface processes associated with soil types, precipitation, vegetation, and the distribution of water bodies and glaciers. A systematic study of the paleoclimatic impact on the subsurface temperature distribution in sedimentary regions in Germany has not yet been conducted. Moreover, borehole climatology studies in Canada and Northern Europe has mainly concentrated on local reconstructions of ground surface temperatures, focusing on single or a limited number of boreholes. The aim of this study is to investigate the paleoclimatic effect of the Holocene on the subsurface temperature distribution in Germany and to quantify regional variations in the ground surface temperature histories. To achieve this, we have identified wells in sedimentary regions across the country that satisfy the prerequisites for borehole climatology. By using geophysical well logs, we derive the thermophysical characterization of the subsurface. We are examining the continuous temperature profiles to determine the magnitude, and regional variability of the Holocene paleoclimatic signal in borehole temperature profiles throughout Germany.

How to cite: Salis Gross, E., Frick, M., Norden, B., Mutz, S. G., and Fuchs, S.: Regional effects of paleoclimate history on the subsurface temperature distribution in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12754, https://doi.org/10.5194/egusphere-egu24-12754, 2024.

EGU24-13168 | ECS | Orals | CL1.2.1 | Highlight

Absence of Winter Warming in Eurasia following large, tropical volcanic eruptions during the Last Millennium 

Ernesto Tejedor, Lorenzo Polvani, Nathan Steiger, Mathias Vuille, and Jason Smerdon

In this investigation, we reassess the hypothesis that volcanic eruptions lead to surface warming in Eurasia during winter. This reevaluation is grounded in contemporary modeling studies that propose internal climatic variations might dominate over the volcanic-forced responses. Our analysis is centered on the Last Millennium (LM), where we combine model output, instrumental observations, tree-ring records, and ice cores, and build a new temperature reconstruction that specifically targets the boreal winter season. Utilizing the latest advancements in volcanic forcing reconstructions, we pinpoint 20 volcanic events over the LM with volcanic stratospheric sulfur injections (VSSI) exceeding those of the 1991 Pinatubo eruption.

Our analysis indicates that among the 20 major volcanic events identified, only seven resulted in warmer surface temperature anomalies in Eurasia during the initial winter following the eruption. In scrutinizing the 13 occurrences that exhibit cold post-eruption anomalies, we observe no direct correlation between the extent of winter cooling and the mass of volcanic stratospheric sulfur injections (VSSI), suggesting that significant internal climatic variability is the probable driver of these cold anomalies.

Moreover, we compare our new temperature reconstruction with two independent reconstructions, and successfully harmonize our results with those of prior research. Moving beyond the observational uncertainties and the conflation of eruptions from different latitudes and different post-eruption winters, our study challenges previous assertions of post-eruption winter warming that largely stemmed from the superposed epoch analysis, which involved averaging the effects of smaller eruptions with larger ones. Our comprehensive observational findings, encompassing the entire LM and corroborating many recent climate modeling studies, suggest that substantial low-latitude volcanic eruptions, such as the 1991 Mount Pinatubo eruption, do not lead to any notable surface warming during the winter months in Eurasia.

How to cite: Tejedor, E., Polvani, L., Steiger, N., Vuille, M., and Smerdon, J.: Absence of Winter Warming in Eurasia following large, tropical volcanic eruptions during the Last Millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13168, https://doi.org/10.5194/egusphere-egu24-13168, 2024.

This study used Reconstructed East Asian Climate Historical Encoded Series (REACHES) database (Wang et al. 2018) to reconstruct historical tropical cyclone (TC) series documented in 1368-1911. Records documented with ‘typhoon’ (Chinese character颱) or ‘hurricane’ (颶) were retrieved, with descriptions of other compounding effects such as strong wind, torrential rain and storm surge to consist of the data set. To avoid repetition and duplicate counting of the same TC event, records that have temporal (± 1 days) and spatial (±2∘degree latitude/longitude) proximity were combined accounting for one single TC event. The method was based on a systematic database approach and data quality was checked and validated through comparison with other independent reconstructed series and IBTrACS (Tropical Cyclone Best Track Data) 1884-2020. The REACHES TC series was then merged with the IBTrACS data to form a l368-2020 long TC series for Northwestern Pacific region. The reconstructed TC series demonstrates clear multi-decadal to centennial variabilities. In the last six hundred years, there were in average 3 TC documented in every year. 1600s was the most TC active period (8 TC in 1627, 7 in 1640, 7 in 1652, 6 in 1662, 7 in 1664, 9 in 1668, 12 in 1669, 10 in 1671, and 8 in 1672). The TC series was then compared with other forcings (volcanic eruption, solar, and SST) and ENSO.  All of the forcings may have a role in the frequent TC activities during Maunder Minimum. Further research from model-data comparison and simulations will shed lights on TC behaviors in the warming climate.

How to cite: Lin, K.-H. E., Tseng, W.-L., Hsu, H.-H., and Wang, P. K.: Annually resolved Northwestern Pacific tropical cyclone series since the mid-14th century: intensified activities during the Maunder Minimum , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14200, https://doi.org/10.5194/egusphere-egu24-14200, 2024.

Quantitative assessment of natural internal variability and externally forced responses of Northern Hemisphere (NH) temperatures is necessary for understanding and attributing climate change signals during past warm and cold periods. However, it remains a challenge to distinguish the robust internally generated variability from the observed variability. Here, large-ensemble (70 member) simulations, Energy Balance Model simulation, temperature ensemble reconstruction, and three dominant external forcings (volcanic, solar, and greenhouse gas) were combined to estimate the internal variability of NH summer (June–August) temperatures over the past 2000 years (1–2000 CE). Results indicate that the Medieval Climate Anomaly was predominantly attributed to centennial-scale internal oscillation, accounting for an estimated 104% of the warming anomaly. In contrast, the Current Warm Period is influenced mainly by external forcing, contributing up to 90% of the warming anomaly. Internal temperature variability offsets cooling by volcanic eruptions during the Late Antique Little Ice Age. Ultimately, this study indicates that the dominant internal climate factor driving centennial-scale fluctuations in NH summer temperatures over the last two millennia has been the AMOC, and that the primary external forcing agent is volcanic activity. These findings have important implications for the attribution of past climate variability and improvement of future climate projections.

How to cite: Shi, F.: Quantitative attribution of Northern Hemisphere summer temperaturesover the past 2000 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14263, https://doi.org/10.5194/egusphere-egu24-14263, 2024.

EGU24-14408 | ECS | Posters on site | CL1.2.1

A glimpse into the Hydroclimate and environmental trends of the past two millennia in Southern Transylvania, Romania 

Agnes Ruskal, Roxana Grindean, Andrei-Cosmin Diaconu, and Ioan Tanțău

Considering the importance of hydroclimate conditions in the development of both natural and anthropic environments, a better understanding of past conditions is imperative. Keeping this as a main trajectory, the objective of our study is the reconstruction of the past hydroclimate and environmental conditions in Central Romania over the last two millennia, by a high-resolution analysis of a peat sequence from Arpaşu de Sus (Făgăraș Depression, Southern Transylvania). We used biotic proxies (testate amoebae, pollen and spores) to quantitatively reconstruct the water level depth fluctuations in the peat bog and abiotic (lithology, AMS radiocarbon dating, organic matter content, bulk density, magnetic susceptibility) to reconstruct the vegetation dynamics and the human impact in the studied area.

The peat bog had ombrotrophic characteristics throughout the studied period, with organic matter percentages ranging from 85 to 95%. The pollen analysis results show that the vegetation of this interval was characterized by extensive forests dominated by Fagus sylvatica, accompanied by Carpinus betulus and Alnus sp. The reconstructed water table depth values, based on testate amoeba assemblages, fluctuated between 32.9 and 11.8 cm.

Our findings are in good agreement with other results from Romania and Central-Eastern Europe, bringing valuable insight to a better understanding of the hydroclimate changes that occurred in Europe in the last two millennia.

How to cite: Ruskal, A., Grindean, R., Diaconu, A.-C., and Tanțău, I.: A glimpse into the Hydroclimate and environmental trends of the past two millennia in Southern Transylvania, Romania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14408, https://doi.org/10.5194/egusphere-egu24-14408, 2024.

EGU24-14496 | ECS | Posters on site | CL1.2.1

Climate Impacts of The Millennium Eruption of The Changbaishan Volcano 

Yuanyuan Yang and Feng Shi

The Millennium Eruption (ME) of Changbaishan Tianchi Volcano is heralded as one of the largest explosive eruptions in the Late Holocene. The geochemistry method estimated that the ME not only produced huge quantities of volcanic debris and lava flows but also emitted up to 45 Tg of sulfur into the atmosphere. The sulfate emissions are higher than the Tambora eruption in 1815 CE, which caused a year without a summer in Europe. Despite such massive emissions, evidence for this eruption's climatic impact in East Asia remains elusive. To explain this contradiction, this study evaluated currently available high-resolution proxy records from the Northern Hemisphere spanning the past two millennia and conducted a volcanic sensitivity experiment using the Community Earth System Model (CESM). Results show that the high-resolution proxy records demonstrate an overall muted negative response during the period of the dating uncertainties, with 945 CE marking the most notable negative anomaly. The sensitivity experiment shows that ME caused significant negative anomalies in both temperatures and precipitation rates in East Asia. Based on the results, we infer that the contradiction between the high Sulfur emissions and a slight glacial sulfate signal may originate from the fact that the ME occurred in 945 CE instead of 946 CE, and the volcanic climatic effects were mitigated by the combined effects of the 945 CE El Niño-like Sea-surface temperatures (SSTs) and the Brewer–Dobson circulation. This study offers a novel perspective on the ME's climatic influence, reconciling previous discrepancies regarding its climatic impact.

How to cite: Yang, Y. and Shi, F.: Climate Impacts of The Millennium Eruption of The Changbaishan Volcano, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14496, https://doi.org/10.5194/egusphere-egu24-14496, 2024.

While most past millennium high-resolution temperature reconstructions rely on tree-ring data, there is a notable scarcity of detailed winter-spring temperature records covering the pre-instrumental period in Europe. This gap is evident in central Scandinavia, a region otherwise well covered by tree-ring data. Although tree-ring records in this area have demonstrated a correlation with spring temperatures, the climate signal is dominated by summer temperatures. Achieving a comprehensive understanding of seasonal variations is essential for understanding climate change and variability in the past. This study employs two different sets of sources to reconstruct late-winter and spring temperatures in central Scandinavia since 1697. First, agro-phenological data, covering barley sowing dates in the central agricultural district around lake Storsjön in Jämtland, central Scandinavia, are employed. These sowing dates have been shown to correlate with spring temperatures and cover most of the period since 1699. Second, previously unpublished data are employed in the form of ice-break up dates for Lake Storsjön, extending back to 1697. While each type of data cover most of the study period (1697–2021), combined they present an almost continuous time-series of phenological dates, enabling an attempt at reconstructing late-winter and spring temperatures in central Scandinavia back to 1697.

How to cite: Skoglund, M.: Barley to Ice: Investigating late-winter and spring temperatures in Central Scandinavia for the last 300 years through agro- and cryophenological proxies , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14523, https://doi.org/10.5194/egusphere-egu24-14523, 2024.

EGU24-14618 | Posters on site | CL1.2.1 | Highlight

The Atlantic Jet and European Hydroclimate Extremes During the Past 600 Years 

Stefan Bronnimann, Jörg Franke, Veronika Valler, Ralf Hand, Eric Samakinwa, Elin Lindstad, Angela-Maria Burgdorf, and Laura Lipfert

The jet stream over the Atlantic-European sector is relevant for weather and climate in Europe. It generates temperature extremes, steers moisture and flood-propelling weather systems to Europe or allows blocks to develop and persist leading to drought. Climate change might alter the jet characteristics affecting weather extremes. However, little is known about its interannual-to-decadal variability in the past. In this contribution we present an analysis of strength, tilt, and latitude of the Atlantic-European jet during the past 600 years in a comprehensive monthly climate reconstruction and compare their variability with drought and flood reconstructions in Europe. Summer drought is enhanced in Central Europe in periods with a poleward-shifted jet. An analysis of decadal flood variability shows that flood-rich periods in the warm season in the Alps coincide with an equatorward-shifted jet. In the cold season, a strong jet increases precipitation in Northern Europe, whereas an equatorward-shifted jet leads to frequent floods in Western Europe. Jet position, tilt, and strength are significantly influenced by El Niño and volcanic eruptions, but overall, the forced component is weak. The jet characteristics provide both a mechanism and a diagnostic to analyse decadal hydroclimate variability in Europe. Our 600-year perspective shows that recent changes in the jet are still within the past variability when considering ensemble members separately.  

How to cite: Bronnimann, S., Franke, J., Valler, V., Hand, R., Samakinwa, E., Lindstad, E., Burgdorf, A.-M., and Lipfert, L.: The Atlantic Jet and European Hydroclimate Extremes During the Past 600 Years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14618, https://doi.org/10.5194/egusphere-egu24-14618, 2024.

EGU24-14935 | ECS | Orals | CL1.2.1 | Highlight

Climate of the eastern Mediterranean and Middle East in the 6th century CE with COSMO-CLM  

Eva Hartmann, Elena Xoplaki, and Sebastian Wagner

The climate of the eastern Mediterranean and the Middle East is well documented in natural (speleothems, tree rings, sediments and pollen) and human-historical archives. The 6th century CE is of particular interest from both a historical and climatic perspective. It is a period of prosperity for the Eastern Byzantine Empire and political stability, but also a time when there was a heavily debated plague pandemic and significant climate variability associated with a major cluster of volcanic eruptions. Dynamical downscaling can bridge the gap between palaeo-records and climate reconstructions, which can be affected by various sources of uncertainty, and the coarsely resolved Earth System Models (ESMs) with 200 km or more horizontal resolution. A transient paleo-simulation with the appropriately adjusted regional climate model COSMO-CLM (CCLM, COSMO 5.0 clm16) is carried out to investigate possible links and feedbacks between the socio-political and economic conditions and the climate variability of that period in more detail.

The state-of-the-art and CMIP6 compliant forcing reconstructions of volcanic (stratospheric aerosol optical depth), orbital (eccentricity, obliquity, precession), solar (irradiance), land-use and greenhouse-gas changes used for the MPI-ESM-LR (Jungclaus et al. 2017) are therefore implemented in the regional climate model. The simulated temperature and precipitation are compared with those of other CMIP6 models as well as with proxy records and reconstructions. In connection with the two successive volcanic eruptions in 536 and 540 CE, the annual temperature of the entire region dropped noticeably until about 550 CE. The signal for precipitation is not as clear, but the years of the eruptions are the driest of the century in the eastern Sahara and Arabian Peninsula and the wettest in the eastern Mediterranean.

How to cite: Hartmann, E., Xoplaki, E., and Wagner, S.: Climate of the eastern Mediterranean and Middle East in the 6th century CE with COSMO-CLM , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14935, https://doi.org/10.5194/egusphere-egu24-14935, 2024.

EGU24-15410 | Orals | CL1.2.1

Imprint of solar and Atlantic Multidecadal Oscillation variability in a 1000 year-long water temperature record from the varved sediments of Lake Czechowskie (northern Poland) 

Jerome Kaiser, Oliver Rach, Michał Słowiński, Mirosław Błaszkiewicz, Helge Arz, and Achim Brauer

Temperature records with a high temporal resolution and spanning the last millennium are of primordial importance to understand climate variability beyond the instrumental period at multi-decadal to multi-centennial timescales. However, such records are rare and absolute values often suffer from large uncertainties. While tree-ring records provide excellent temperature records in the mid-latitudes at an annual timescale, they are generally not well-suited for understanding centennial to multi-millennial climate variability due to biologic age trends. Here, we provide a precisely dated, 1000 year-long temperature record with a decadal resolution from varved Lake Czechowskie located in northern Poland (Europe). The reconstruction is derived from a temperature proxy, which is based on glycerol dialkyl glycerol (GDGT) membrane lipids from bacteria thriving in the lake. The temperature record presents a trend very similar to observed June to November air temperatures for the period 1840 to 1975. However, absolute values are about 2 °C colder than observed air temperature because the estimates reflect temperature near the thermocline as suggested by lake monitoring data. The temperature reconstruction indicates that temperatures were 0.5±0.5 °C warmer and 0.8±0.5 °C colder than AD 1900–1975 during the Medieval Climate Anomaly and the Little Ice Age, respectively. A frequency analysis of Lake Czechowskie record as well as other temperature records from the Northern Hemisphere mid-latitudes reveals three main periodicity bands at 55–90, 110–190 and 210–300 years. These bands are most likely related to both solar variability (80–90-year Gleissberg and 200–210-year Suess/de Vries cycles) and to the Atlantic Multidecadal Variability/Oscillation (60–90 and 140–180-year periodicities), which is known to modulate temperature in the Baltic Sea region. Lake Czechowskie record represents a unique reconstruction of temperature decadal variability in the southern Baltic lowlands and Northern Europe during the last millennium.

How to cite: Kaiser, J., Rach, O., Słowiński, M., Błaszkiewicz, M., Arz, H., and Brauer, A.: Imprint of solar and Atlantic Multidecadal Oscillation variability in a 1000 year-long water temperature record from the varved sediments of Lake Czechowskie (northern Poland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15410, https://doi.org/10.5194/egusphere-egu24-15410, 2024.

EGU24-16569 | ECS | Posters on site | CL1.2.1

Reconstructing the Sea-Surface Temperature at the Equatorial Pacific using tree-ring proxies from the Peruvian central Andes.  

Clara Rodriguez Morata, Edilson Jimmy Requena Rojas, Ginette Ticse Otalora, Mariano Morales, Doris Crispín DeLaCruz, and Laia Andreu hayles

Some El Niño events are characterized by very warm conditions in the far-eastern Equatorial Pacific (FEP), but cool conditions elsewhere in the central Equatorial Pacific (CEP). The impact of these so called Coastal El Niño (CEN) events is particularly strong, associated with extreme rainfall events over the coastal northern Peru, Ecuador and adjacent Andean slopes. Despite the fact CEN events represent a high cost for social and economic development of these countries, little is known in terms of frequency, mechanisms and predictability and only very recently science and society are paying attention to these episodes. Here we use the tree-ring width (TRW), as well as stable oxygen (δ18O) and carbon (δ13C) isotopes measured in tree rings to reconstruct Sea-Surface Temperature (SST) in the Equatorial Pacific Ocean described by the two first Empirical Orthogonal Function (EOF). While EOF1 corresponds to the CEP region, EOF2 represents the FEP region.

The newly developed TRW and isotopic records span from 1890 to 2007 and were built from Polylepis rodolfovasquezii trees located at 4,360 m a.s.l in an Andean forest in Peru (11.72°S, 75.14°W). Our results show significant (-) correlation between tree-ring δ13C and temperature during the previous growing season peak, while non climatic signal was found in TRW and δ18O records. During the current growing season tree-ring δ18O is the proxy that exhibits the highest sensitivity to both, precipitation (-) and temperature (+) compared with the two other tree-ring parameters. In addition, the δ18O record displays more consistent correlation patterns with both EOFs, suggesting that δ18O may contain stronger climate signals than TRW and tree-ring δ13C. Lastly, the use of a sequential leave-20-out calibration-validation technique for reconstructing the variability of EOFs indicated that the δ18O record was effective to reconstruct EOF1. However, incorporating a multi-proxy strategy, which includes TRW, δ18O, and δ13C, enhanced the overall quality of the reconstruction. In contrast, the multi-proxy approach was not enough to reconstruct EOF2. We conclude that expanding the geographical distribution of proxy records into new in-land areas around the FEP, where SST variability has a local impact on hydroclimate, it is a priority in order to reconstruct CEN. Tree-ring stable isotopic records are valuable to complement existing TRW chronology to overcome the inherent difficulties on using tropical Andean species for paleoclimate research.

How to cite: Rodriguez Morata, C., Requena Rojas, E. J., Ticse Otalora, G., Morales, M., Crispín DeLaCruz, D., and Andreu hayles, L.: Reconstructing the Sea-Surface Temperature at the Equatorial Pacific using tree-ring proxies from the Peruvian central Andes. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16569, https://doi.org/10.5194/egusphere-egu24-16569, 2024.

EGU24-17740 | Orals | CL1.2.1

Bristlecone Pine Maximum Latewood Density as a Superior Proxy for Millennial Temperature Reconstructions  

Vladimir Matskovsky, Tom de Mil, Charlotte Pearson, Lode Corluy, Louis Verschuren, Matthew Salzer, Valerie Trouet, Jan Van den Bulcke, and Luc Van Hoorebeke

Great Basin Bristlecone pine (Pinus longaeva) (PILO) trees are known for their old age. The longest tree-ring width (TRW) chronology covers a large part of the Holocene, and the temperature-sensitive upper treeline chronology extends back to 2575 BC. The TRW of upper treeline PILO trees is influenced by temperature variability, but the moderate strength and temporal instability of the signal is making it hard to use for reliable temperature reconstructions. Maximum Latewood Density (MXD) of conifers is known to be a good summer temperature proxy in the northern hemisphere. However, there are no PILO MXD records due to various reasons, including its location in semi-arid lower latitudes, as well as due to methodological difficulties such as narrow rings and a varying grain angle. Here, we used an X-ray Computed Tomography (X-ray CT) of 69 cross-dated cores to construct an MXD chronology of PILO from the upper treeline sites covering the last millennium, and to investigate its temperature signal. The chronology correlates significantly (r=0.63) with warm season (April to September) temperature for the period 1895-2005 and the signal is stable throughout the instrumental period. Our results demonstrate that MXD from the bristlecone pine archive can be used as a robust proxy for western North American warm season temperature variability at an unprecedented multi-millennial scale.

How to cite: Matskovsky, V., de Mil, T., Pearson, C., Corluy, L., Verschuren, L., Salzer, M., Trouet, V., Van den Bulcke, J., and Van Hoorebeke, L.: Bristlecone Pine Maximum Latewood Density as a Superior Proxy for Millennial Temperature Reconstructions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17740, https://doi.org/10.5194/egusphere-egu24-17740, 2024.

EGU24-19162 | ECS | Posters on site | CL1.2.1

Extreme precipitation variations in the northeastern Tibetan Plateau during the last millennium 

Duo Wu, Weifeng Kong, Yuan Liang, Shilong Guo, Tao Wang, Jinghua Huang, and Lili Pan

With the background of global warming, the hydrological cycle has accelerated and the occurrence of extreme precipitation events has also increased, bringing significant impact on agriculture, transportation, and human safety. The investigation of the frequency of historical or ancient extreme precipitation events is helpful for a better management of modern hydrological disasters and a reasonable prediction of future precipitation variations. The present study focuses on Lake Dalzong, an alpine lake located in Xiahe County, Gansu Province, northeastern Tibetan Plateau, and provides a lacustrine record of extreme precipitation variations during the last millennium in the study region.

Considering that Lake Dalzong is a varve lake, we monthly and seasonally collected modern surface sediment samples, lake water samples, and precipitation samples from June 2020 to October 2023. By analyzing the hydrogen and oxygen isotopes of water samples, we found that the lake is a hydrology open system and the lake water is mainly supplied by precipitation. From the measurements of the surface sediments and typical laminated samples, annual lamination was successfully identified. It is found that the coarse-grained dark layer was formed under increased precipitation from the summer to the early autumn, as heavy rainfall can bring exogenous detrital materials into the lake. And the fine-grained light layer was deposited during the freezing period of the lake from mid-November to mid-April of the following year when lake water was still and tiny dead organisms deposited slowly. Therefore, the varve layers are ideal archive of extreme precipitation variations in the region.

Furthermore, a continuous sediment core reaching the bedrock, with a total length of 457.5 cm, was obtained from the center of the lake, and a reliable chronological framework for the past thousand years was established by using 137Cs and AMS14C dating, as well as the varve counting. Based on the analysis of grain size, XRF elemental data with high resolution, and the extreme precipitation variations was reconstructed. The coarse-grained dark layer with a thickness of 0.3~1.2 cm was extracted and defined as the varve event layer. It matched well with the peak percentage of coarse grain and the relative content of Ti elements, indicating that there was a corresponding relationship between the varve event layers and the extreme precipitation events. The results show that the frequency and intensity of extreme precipitation events increased during the Little Ice Age but decreased since the Industrial revolution. A further investigation shows that the extreme precipitation variations in the northeastern Tibetan Plateau was controlled by the external-driven factors and the ocean-atmosphere interactions in the Earth system.

How to cite: Wu, D., Kong, W., Liang, Y., Guo, S., Wang, T., Huang, J., and Pan, L.: Extreme precipitation variations in the northeastern Tibetan Plateau during the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19162, https://doi.org/10.5194/egusphere-egu24-19162, 2024.

EGU24-19884 | ECS | Posters on site | CL1.2.1

Atlantic inflow insights from sediment core reconstructions of the Norwegian Atlantic Current over the past 1000 years 

Aidan Starr, Francesco Muschitiello, Margit Simon, Amandine Tisserand, Carin Andersson Dahl, Trond Dokken, and Matthew Osman

The North Atlantic Current and its extensions, including the Norwegian Atlantic Current (NwAC), transport warm and saline upper ocean waters from the North Atlantic north-eastward into the Nordic Seas. The interaction between this saline inflow versus freshwater runoff into the Arctic is important in modulating the response of the Atlantic Meridional Overturning Circulation to climate change. To better understand variability in the strength and character of this inflow and the closely linked North Atlantic Subpolar Gyre, paleoceanographic reconstructions aim to extend the limited temporal scope of existing instrumental records. Here, we present high-resolution reconstructions of temperature and salinity from coupled d18O – Mg/Ca measurements on two species of planktonic foraminifera, as well as estimates of upper-ocean radiocarbon ages from a rapidly accumulating marine sediment core located under the NwAC (GS06-144-22; 62.5ºN, 4.1ºE, 921m). Using a novel, robust chronology for this core, we determine changes in the surface radiocarbon reservoir effect at the site, which - along with the seasonal temperature and salinity reconstructions - provide new insights into NwAC and Subpolar Gyre dynamics over the last millennium.

How to cite: Starr, A., Muschitiello, F., Simon, M., Tisserand, A., Andersson Dahl, C., Dokken, T., and Osman, M.: Atlantic inflow insights from sediment core reconstructions of the Norwegian Atlantic Current over the past 1000 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19884, https://doi.org/10.5194/egusphere-egu24-19884, 2024.

EGU24-21057 | Posters on site | CL1.2.1

Observations of Greenland Ice Sheet mass loss over the past 2ka 

Camilla S. Andresen, Jens Hesselbjerg Christensen, Mikkel Lauritzen, Inda Brinkmann, Christine Schøtt Hvidberg, Larissa van der Laan, Kerim Nisancioglu, Natalya Gomez, and Hendrik Grotheer

This study aims to contribute data, that will improve understanding on the role of Greenland ice sheet melt in modulating midlatitude climate.

A great hamper to our understanding of the influence from Greenland ice sheet melt on European climate variability comes from the lack of high-resolution observations of dynamic mass loss from the from Greenland Ice Sheet extending beyond the instrumental time scale. Building on a large repository of sediment cores taken from fjords by some of Greenland’s largest marine terminating glaciers, we aim to reconstruct multi-decadal to centennial scale changes in the iceberg production (solid ice mass loss) over the past 2ka. The IRD proxy method has conventionally been used in deep sea cores to elucidate major instability events of glacial ice sheets but has shown potential as a glacier proxy through the correspondence of the 20th century IRD records with historical and instrumental records of glacier margin positions of Sermeq Kujalleqand Upernavik Glacier in West Greenland, and Helheimand Kangerlussuaq Glaciers in Southeast Greenland.

Here we show reconstructions of dynamic mass loss from from Sermeq Kujalleqand Helheim Glacier over the past 2ka. The data indicate marked melt variability at the multidecadal to centennial time scales from West Greenland during the Roman Warm Period, whereas SE Greenland Glaciers may have been buffered by sea ice at this time.

How to cite: Andresen, C. S., Hesselbjerg Christensen, J., Lauritzen, M., Brinkmann, I., Schøtt Hvidberg, C., van der Laan, L., Nisancioglu, K., Gomez, N., and Grotheer, H.: Observations of Greenland Ice Sheet mass loss over the past 2ka, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21057, https://doi.org/10.5194/egusphere-egu24-21057, 2024.

EGU24-22252 | Orals | CL1.2.1 | Highlight

The tree-ring d18O network from southernmost Patagonia: A recorder of large-scale climate modes and their spatial-temporal variability 

Wolfgang Jens-Henrik Meier, Jussi Grießinger, Juan Carlos Aravena, and Pamela Soto-Rogel

The Southern Patagonian Andes are located within the core zone of the Southern Hemispheric Westerlies (SHW). The North-South orientated Andean Cordillera is perpendicular to the main flow of moist airmasses triggered by different large-scale atmospheric circulation patterns like the Antarctic Oscillation (AAO). In recent decades, especially southernmost South America (50–56◦ S) has experienced a profound climate change resulting in rising temperatures, an increase in the variation of precipitation, and increased severe droughts (e.g. the recent Chilean Megadrought) that can be related to variations in atmospheric circulation over varied timescales. Up to now, a quantification of these changes in a context pre-1950´s stays difficult, due to scarce and fragmentated available climate station data. In combination with a complex regional topography and resulting scetchy ecoclimatic zones the impacts of the current environmental change are yet not well assessed. Within this study we present the up to date most dense network of d18Otree-ring series for southern South America based on two Nothofagus tree species. We can demonstrate, that the inherent climate signals in our proxy series is a highly suitable annual resolved archive to capture variations in the AAO and therefore can capture the long-term and short-term geographical migration (North-South) of the SHW. In addition, combined analyses of large-scale synoptic weather patterns (mean weather types; Grosswetterlagen, GWL) and backward trajectory modeling clearly reveal a highly significant influence of the moisture origin on the variations of the d18Otree-ring series.

How to cite: Meier, W. J.-H., Grießinger, J., Aravena, J. C., and Soto-Rogel, P.: The tree-ring d18O network from southernmost Patagonia: A recorder of large-scale climate modes and their spatial-temporal variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22252, https://doi.org/10.5194/egusphere-egu24-22252, 2024.

Purpose Climate extremes, such as droughts and floods, have become intensified and more frequent due to intensifying climate change. Increased atmospheric carbon dioxide (CO2) and warming-induced water limitation, as well as climate extremes, may alter carbon (C) and nitrogen (N) cycling in forest ecosystems. This provides a brief review of stable nitrogen

isotopic composition (δ15N) in tree ring in relation to climate extremes and bushfires in context of N availability and losses in forest ecosystems.

Material and methods Tree rings were extracted from four Pinus sylvestris and four Larix gmelinii sample trees, located in a boreal plantation forest of Mohe City, Heilongjiang Province, China. Tree rings were measured to obtain mean annual basal area increment (BAI), while tree ring δ15N and total N concentrations were measured on mass spectrometer at 3-year intervals. The tree ring δ15N data were related to possible climate extremes and bushfires. A brief review of the relevant literature was also undertaken to support our preliminary research findings.

Results and discussion Globally, increasing atmospheric CO2 concentration and water limitations have led to a warmer-drier climate. This has also been associated with increases of climate extremes such as drought and floods as well as bushfires. These extremes have been recorded with detrimental effects on plant and soil structures within forest ecosystems and play an important role in regulating N availability and losses in forest ecosystems. Studies of N deposition within forest ecosystems using soil and plant δ15N also showed that N losses under various climate extremes can occur through direct changes in N cycling, such as increasing soil nitrification and denitrification or leaching. It is highlighted that tree rings δ15N has the potential to fingerprint the intensity and frequency of climate extremes and bushfires in the forest ecosystems, but more such tree ring δ15N research needs to be done in diversified forest ecosystems to confirm the potential of using tree ring δ15N for quantifying the frequency and intensity of climate extremes and bushfires at both regional and global scale.

Conclusion The variation and trend of δ15N in the soil–plant-climate systems are closely linked to the N cycling in forest ecosystems, and tree ring δ15N has the great potential to fingerprint both intensity and frequency of climate extremes such as drought and floods as well as bushfires.

How to cite: succarie, A.: On the variation and trends of nitrogen isotope composition in tree rings: the potential for fingerprinting climate extremes and bushfires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2772, https://doi.org/10.5194/egusphere-egu24-2772, 2024.

EGU24-4030 | Orals | CL1.2.2 | Highlight

Natural variability has dominated the movement of High Asia Polar Jet over the past six centuries 

Wenling An, Kerstin Treydte, Chenxi Xu, Qiuzhen Yin, Flurin Babst, Laibao Liu, Qiong Zhang, Raphael Neukom, Zhenqian Wang, and Zhengtang Guo

Recent northward movement of polar jet has been linked with mid-latitude weather and climate anomalies, but distinguishing the natural variability and anthropogenic activity is hindered by a lack of long-term observations. Here we use tree ring oxygen records from the High Asia to reconstruct variability in the movement of the late spring High Asia Polar Jet (HAPJ) over the past six centuries. We find that the HAPJ has shown a gradually northward trend since 1600s, which have resulted in relatively wet conditions in the High Asia and southern west Asia from 1600s to late 1800s and recent decades. Combined with model results, we find the HAPJ is dominated by the phase changes of North Atlantic Oscillation and volcanic eruption at decadal to multi-decadal scales. At multi-decadal to centurial scales, solar activity is the largest contributor to HAPJ movement, while the contribution of increasing greenhouse gas is relatively small. These results highlight the importance of natural variability in HAPJ movements under the context of global warming.

How to cite: An, W., Treydte, K., Xu, C., Yin, Q., Babst, F., Liu, L., Zhang, Q., Neukom, R., Wang, Z., and Guo, Z.: Natural variability has dominated the movement of High Asia Polar Jet over the past six centuries, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4030, https://doi.org/10.5194/egusphere-egu24-4030, 2024.

EGU24-4356 | ECS | Orals | CL1.2.2

Dwarf shrub δ18O from the Top of the World / Everest region record large-scale climate signals 

Jussi Grießinger, Wolfgang Jens-Henrik Meier, Haifeng Zhu, Huang Ru, and Eryuan Liang

Oxygen isotopes (δ18O) derived from tree-rings are an excellent and frequently utilized annually resolved climate proxy. Above the tree-line, woody (dwarf) shrubs can further densify the still fragmentary global paleoclimatic network, which is particularly relevant for the high altitudes of the Himalayan Arc. Still, few studies have investigated the suitability of δ18O from shrubs for climate reconstructions, specifically on the windward southern slopes of the Central Himalayan Arc. In this study, we evaluated the climate imprints on juniper dwarf shrubs located above 4,000 m asl in the Mount Everest region, Nepal. Three gridded climate data sets (CRU TS, ERA-5 and CHELSA) with a spatial resolution between 0.5° and 0.08° were used to evaluate the respective climate-proxy relationships. The strong influence of variations in temperatures and moisture (precipitation, rH, VPD) on our δ18O time series are most evident during the summer monsoon season. Spatial correlation analyses further confirm a strong supra-regional representativity of our proxy across large parts of the Himalaya and northern India. The dependency on large-scale atmospheric circulation is underlined by significant correlations between δ18O, various monsoon indices and more complex and coupled (tropical) ocean-atmospheric oscillation patterns such as the Southern Oscillation Index and the Madden-Julian Oscillation. By analyzing synoptic weather patterns of the Indian Subcontinent we can further demonstrate, that our δ18O series is strongly influenced by climate conditions during the break monsoon periods than to conditions during the active monsoon period. During the breaking periods, two weather patterns are predominantly influencing our δ18O series when i) air masses are increasingly originating from (North)West, leading to a sharp decrease in precipitation and higher temperatures or when ii) a shift of the monsoon trough towards the North results in a decrease of rainfall over the India subcontinent and an increase in precipitation over the Himalayan region.

How to cite: Grießinger, J., Meier, W. J.-H., Zhu, H., Ru, H., and Liang, E.: Dwarf shrub δ18O from the Top of the World / Everest region record large-scale climate signals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4356, https://doi.org/10.5194/egusphere-egu24-4356, 2024.

EGU24-5939 | Posters on site | CL1.2.2

Growth and drought resilience of planted conifers and broadleaves in the semi-arid Northern China. 

Jitang Li, Yuyang Xie, Jesús Julio Camarero, Antonio Gazol, Ester González de Andrés, Lingxiao Ying, and Zehao Shen

Under warmer and drier climate scenarios, the growth and resilience of forests will be critically affected by more frequent and severe droughts. Since the 1970s, China has launched several afforestation programs aimed at regional ecological protection, playing an important role for reaching carbon neutrality by 2060.

This study provided a detailed analysis of the growth suitability of the main planted conifers (Pinus sylvestris var. mongolica, Pinus tabulaeformis) and broadleaves (Populus spp., Robina pseudoacacia) in the semi-arid northern China. We compared the radial growth trends of plantations and their responses to extreme droughts from 1980 to 2018.

Growth of most plantations has significantly increased, but broadleaves showed recent growth reductions in the past decade, which may be related to tree age and reduced soil water content. Nevertheless, under warmer climate scenarios, growth of plantations is forecasted to continue increasing. Broadleaves showed a better post-drought recovery, probably linked to their anisohydric behavior, than conifers, which presented a better resistance to drought. Growth of conifers depended more on warmer temperature and better precipitation conditions during the growing season, whereas broadleaves mainly reacted to warm temperature. Additionally, pre-drought growth levels weakened resilience components, while post-drought precipitation compensated drought-induced growth deficit. Growth and resilience were negatively related to tree age, whilst higher stand density reduced growth. This assessment and projections of growth and drought resilience indicate the sustainability of most plantations in semi-arid regions, but future warmer and drier conditions may lead to an uncertain future regarding forest health and reduce their carbon sink potential.

Keywords: Growth trends; Drought resilience; Tree-ring analysis; Plantations; Three-North Shelter Forests Program.

How to cite: Li, J., Xie, Y., Julio Camarero, J., Gazol, A., González de Andrés, E., Ying, L., and Shen, Z.: Growth and drought resilience of planted conifers and broadleaves in the semi-arid Northern China., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5939, https://doi.org/10.5194/egusphere-egu24-5939, 2024.

EGU24-5970 | ECS | Orals | CL1.2.2

Impacts of recurrent extreme drought events on the dynamics of radial growth, wood anatomy and stable isotopes in beech trees from 2013 to 2022 in northeastern France 

Guangqi Zhang, Nathalie Breda, Nicolas Steil, Pierre-Antoine Gaertner, Julien Ruelle, and Catherine Massonnet

Extreme drought events are responsible for widespread forest dieback and large-scale tree mortality events across the globe, which can have detrimental effects on both short-term forest functioning and long-term ecosystem dynamics. An unprecedented decline of European beech (Fagus sylvatica L.) has been observed in central Europe following the 2018-2020 drought event, and beech trees may have reached a tipping point where many individuals are no longer able to survive. A better understanding of the physiological mechanisms that allow beech trees to resist and to cope with severe water deficits and those that lead to the tree death is essential.

The main objective of this study is to gain insight into the physiological properties involved in the resilience or death trajectories of the beech trees in response to an extreme and prolonged drought episode. We retrospectively analysed multi-proxy traits including tree ring width, a proxy for tree cambial growth, wood anatomical traits, a proxy for the xylem hydraulic performance, and tree ring isotopic composition, a proxy for water use efficiency (WUE).

A total of 60 trees were selected which are distributed in four stands in North-eastern France with different levels of soil water deficit which were quantified retrospectively by the BILJOU© water balance model. Tree cores at 1.3m were taken for radial growth analysis and retrospective xylem anatomical measurements in the last 10 tree rings (rings before, during and after drought). Stable carbon (δ13C) and oxygen (δ18O) isotopes were also measured in these rings to determine, respectively, the annual WUE and the water and carbon constrains on WUE variation. Tree resistance, recovery and resilience to drought were quantified for cambial growth, specific hydraulic conductivity and WUE.

Over the past 10 years, we determined that 2015 and 2018-2020 were drought years by calculating annual soil water deficits at the stand level. Decreased tree growth and increased WUE were observed due to soil water shortage, whereas xylem vessel size and specific hydraulic conductivity did not show obvious changes. Vessel density was negatively correlated with annual ring width and was highly sensitive to drought. In severe drought sites, recurrent drought severely affected resistance of tree growth and the post-drought recovery of hydraulic conductivity and water use efficiency. Furthermore, growth resilience of beech trees could not be explained by vessel-related anatomical traits and isotopic composition. Overall, our study shows that beech xylem structure responds to drought by adjusting the number, rather than the size, of vessels, and highlights the impact of prolonged or recurrent drought on xylem hydraulic and WUE recovery. This work contributes to the understanding of how drought-sensitive trees cope with extreme drought events in terms of their carbon-water relations in the context of climate change.

How to cite: Zhang, G., Breda, N., Steil, N., Gaertner, P.-A., Ruelle, J., and Massonnet, C.: Impacts of recurrent extreme drought events on the dynamics of radial growth, wood anatomy and stable isotopes in beech trees from 2013 to 2022 in northeastern France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5970, https://doi.org/10.5194/egusphere-egu24-5970, 2024.

EGU24-6784 | ECS | Posters on site | CL1.2.2

Shifting potential for high-resolution climate reconstructions under global warming 

Jernej Jevšenak, Allan Buras, and Flurin Babst

Tree-ring based reconstructions of climate in pre-instrumental times render a cornerstone of earth-system science and critically rely on statistical relationships between meteorological observations and natural proxy archives. Recent studies have frequently reported that these relationships are not stable in time (non-stationarity), possibly caused by global change (climate, atmospheric CO2), data resolution and quality, and statistical methods applied. Here, we assess the elusive impacts of these factors on the palaeoclimatological potential across the Northern Hemisphere. Scrutinizing spatiotemporal patterns in widely applied validation metrics derived from 3,781 tree-ring chronologies and 517 published dendroclimatic studies, we show that temperature and precipitation sensitivity have increased in the late 20th century. This increase was consistent with trends derived from our meta-analysis. Projecting our results into climate scenarios for the 2021-2040 period indicated further expansion of areas with strong water limitation (+5±2%), whereas the areas with strong temperature limitation were projected to shrink by 8±3% (tree-ring width proxy) and 3±2% (maximum latewood density proxy). Moreover, under increased atmospheric CO2 concentrations and consequently water-use efficiency, water limitation on tree growth may weaken and so the sensitivity to precipitation with consequences for corresponding reconstructions. These spatiotemporal shifts in the climate response of tree growth indicate that continued climate change over the next decades will substantially alter our capacity to establish a robust historical baseline for climate change research. However, our assessment of 517 published climate reconstructions revealed that scientists have, so far, successfully conserved climate signals in trees through refined statistical approaches. But we deem it unlikely that methodological advances will continue to compensate for projected weakening temperature correlations, which will pose a daunting challenge for future temperature reconstructions based on TRW records. Encouragingly, despite minor decreases in projected climate sensitivity, MXD is expected to remain a strong temperature proxy. High-resolution paleoclimatology will thus need new innovations to ensure its continued support of earth system science. Lastly, a better understanding of tree growth response to environmental changes is crucial for accurately addressing non-stationarity in climate reconstructions.

Jevšenak, J., Buras, A., Babst, F., 2024. Shifting potential for high-resolution climate reconstructions under global warming. Quaternary Science Reviews 325, 108486.

How to cite: Jevšenak, J., Buras, A., and Babst, F.: Shifting potential for high-resolution climate reconstructions under global warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6784, https://doi.org/10.5194/egusphere-egu24-6784, 2024.

EGU24-8541 | ECS | Orals | CL1.2.2

Divergent temporal shifts in climate sensitivity of Norway spruce along an elevational and continentality gradient in the Carpathians 

Andrei Popa, Jernej Jevšenak, Ionel Popa, Ovidiu Badea, and Allan Buras

Climate change is affecting forest ecosystems all around the globe, through warming as well as increased drought frequency and intensity. Across much of Europe, climate change has caused a major dieback of Norway spruce (Picea abies L.), an economically important tree species. However, the southeasternmost fringe of this tree species – the Eastern Carpathians – has not yet suffered large-scale dieback. In recent decades, temporal shifts of climate sensitivity (TSCS) have been observed on a global scale. Thus, studying TSCS over time may elucidate the degree to which Norway spruce may be vulnerable to climate-change induced decline in upcoming decades.

Under this framework, we analyzed a regional tree-ring network comprising more than 3,000 trees, with the aim of quantifying TSCS since 1950. We mathematically defined TSCS as the slope parameter of the regression of climate sensitivity (the correlation coefficient) over time. Given the often-observed contrasting shift of climate sensitivity at low versus high elevations, we were particularly interested in studying potentially divergent TSCS along elevational and spatial gradients. Our results revealed several indications of TSCS for Norway spruce in the Eastern Carpathians. First, at high elevations (>1,100 m a.s.l.), we found that the positive link between summer temperature and spruce growth decreased significantly over the study period. In turn, these trees, over time, featured an increasing positive relationship with late winter temperatures. At low elevations (<800 m a.s.l.), the signal of positive summer Standardised Precipitation-Evapotranspiration Index (SPEI) correlation became more frequent among sites. Our results revealed that TSCS was driven significantly by an elevational climate gradient and a longitudinal continentality gradient. Overall, our findings indicate that Norway spruce is increasingly affected by water limitations under climate change at low elevations, highlighting a potentially rising risk of decline of this species in the Eastern Carpathians.

How to cite: Popa, A., Jevšenak, J., Popa, I., Badea, O., and Buras, A.: Divergent temporal shifts in climate sensitivity of Norway spruce along an elevational and continentality gradient in the Carpathians, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8541, https://doi.org/10.5194/egusphere-egu24-8541, 2024.

EGU24-8585 | Posters on site | CL1.2.2 | Highlight

Legacy of last millennium timber use on plant cover in Central Europe: insights from tree rings and pollen 

Andrea Seim, Emma Antoine, and Laurent Marquer and the dendro-pollen team

Throughout history, humans have relied on wood for constructions, tool production or as an energy source. How and to what extent these human activities have impacted plant abundance and composition over a long-term perspective is, however, not well known. To address this knowledge gap, we combined 44 239 precisely dated tree-ring samples from economically and ecologically important tree species (spruce, fir, pine, oak) from historical buildings, and pollen-based plant cover estimates using the REVEALS model from 169 records for a total of 34 1° x 1° grid cells for Central Europe. Building activity and REVEALS estimates were compared for the entire study region (4–15° E, 46–51°N), and for low (< 500m asl) and mid/ high elevations (≥ 500m asl) in 100-year time windows over the 1150–1850 period. Spruce and oak were more widely used in wooden constructions, amounting to 35% and 32%, respectively, compared to pine and fir. Besides wood properties and species abundance, tree diameters of harvested individuals, being similar for all four species, were found to be the most crucial criterion for timber selection throughout the last millennium. Regarding land use changes, from the 1150-1250’s onwards, the forest cover generally decreased due to deforestation until 1850, especially at lower elevations, resulting in a more heterogeneous landscape. The period 1650‒1750 marks a distinct change in the environmental history of Central Europe; increasing agriculture and intense forest management practices were introduced to meet the high demands of an increasing population and intensifying industrialization, causing a decrease in plant/palynological diversity, in particular at low elevations. Likely the present Central European landscapes originated from that period. Our results further show that land use has impacted vegetation composition and diversity at an increasing speed leading to a general homogenization of landscapes through time, highlighting the limited environmental benefits of even-aged plantation forestry.

How to cite: Seim, A., Antoine, E., and Marquer, L. and the dendro-pollen team: Legacy of last millennium timber use on plant cover in Central Europe: insights from tree rings and pollen, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8585, https://doi.org/10.5194/egusphere-egu24-8585, 2024.

EGU24-8957 | Posters on site | CL1.2.2

Drivers of intra‐seasonal δ13C signal in tree‐rings of Pinus sylvestris as indicated by compound‐specific and laser ablation isotope analysis 

Katja Rinne-Garmston, Yu Tang, Elina Sahlstedt, Bartosz Adamczyk, Matthias Saurer, Yann Salmon, Maria del Rosario Domínguez Carrasco, Teemu Hölttä, Marco Lehmann, Lan Mo, and Giles Young

Carbon isotope composition of tree‐ring (δ13CRing) is a commonly used proxy for environmental change and ecophysiology. δ13CRing reconstructions are based on a solid knowledge of isotope fractionations during formation of primary photosynthates (δ13CP), such as sucrose. However, δ13CRing is not merely a record of δ13CP. Isotope fractionation processes, which are not yet fully understood, modify δ13CP during sucrose transport. We traced, how the environmental intra‐seasonal δ13CP signal changes from leaves to phloem, tree‐ring and roots, for 7 year old Pinus sylvestris, using δ13C analysis of
individual carbohydrates, δ13CRing laser ablation, leaf gas exchange and enzyme activity measurements. The intra‐seasonal δ13CP dynamics was clearly reflected by δ13CRing, suggesting negligible impact of reserve use on δ13CRing. However, δ13CP became increasingly 13C‐enriched during down‐stem transport, probably due to post‐photosynthetic fractionations such as sink organ catabolism. In contrast, δ13C of water‐soluble carbohydrates, analysed for the same extracts, did not reflect the same isotope dynamics and fractionations as δ13CP, but recorded intra‐seasonal δ13CP variability. The impact of environmental signals on δ13CRing, and the 0.5 and 1.7‰ depletion in photosynthates compared ring organic matter and tree‐ring cellulose, respectively, are useful pieces of information for studies exploiting δ13CRing.

How to cite: Rinne-Garmston, K., Tang, Y., Sahlstedt, E., Adamczyk, B., Saurer, M., Salmon, Y., del Rosario Domínguez Carrasco, M., Hölttä, T., Lehmann, M., Mo, L., and Young, G.: Drivers of intra‐seasonal δ13C signal in tree‐rings of Pinus sylvestris as indicated by compound‐specific and laser ablation isotope analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8957, https://doi.org/10.5194/egusphere-egu24-8957, 2024.

EGU24-9146 | Posters on site | CL1.2.2

Deep Learning-Based semantic segmentation for geomorphic processes signals in tree-ring records 

Joe David Zambrano Suárez, Jorge Pérez Martín, Alberto Muñoz Torrero Machado, and Juan Antonio Ballesteros-Cánovas

Trees encapsulate environmental changes in their growth through the records in the tree rings, but extracting this signal proves challenging and time consuming. These challenges persist in the study of geomorphic processes, requiring meticulous and prolonged efforts by a specialised technician to identify and date growth disturbances (GD). The presence of false annual rings adds another layer of complexity to the task. 

Today, many classical computer vision-based techniques have been developed for the automatic detection of annual rings. However, to the best of our knowledge, these techniques have not been applied to the detection of GD associated with geomorphic events, which are more challenging because they do not present as clear visual patterns as annual rings. Deep learning-based architectures have shown great capacity for automatic localisation of objects in images with complex shapes.

We have applied these systems to the segmentation of evidence of geomorphological processes (i) wounds (ii) callus tissue (iii) latewood (iv) traumatic resin ducts and (v) growth rings. The deep learning (DL) architectures used were Faster R-CNN with ResNet-101-FPN backbone, YOLOv8 and a U-Net architecture. For the application of the system, it is necessary divide the image into smaller patches, and post-processing techniques for the correct unification of the predictions of each image. Training and evaluation of the networks was performed in Google Colaboratory. The algorithm was tested on 150 cores taken ad hoc from a debris flow cone in the Pyrenees (Pineta Valley), where historical debris flows have occurred. The cores were subjected to a sanding process and the images were obtained using a Canon Eos8 camera. 120 were used to train and validate and 30 to test the architectures, comparing the results obtained by a classical approach and by DL. The evaluations were performed at the pixel level using the accuracy, precision and recall metrics. After post-processing the predictions, the pixels were converted into instances and the predictions were compared with the ground truth, and the metrics Intersection over Union (IoU), precision and recall per category were calculated.

Our preliminary results suggest that, with a sufficiently large dataset, deep learning-based models can capture sufficient information to identify the complex patterns to be classified. This implies that it is possible to achieve a model capable of automatically identifying geomorphological event signals, thereby speeding up the process of obtaining evidence. This opens the possibility of having proposals of event signals without subjective bias, obtaining in different studies, evidence datasets made with a homogeneous and systematised criterion.

How to cite: Zambrano Suárez, J. D., Pérez Martín, J., Muñoz Torrero Machado, A., and Ballesteros-Cánovas, J. A.: Deep Learning-Based semantic segmentation for geomorphic processes signals in tree-ring records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9146, https://doi.org/10.5194/egusphere-egu24-9146, 2024.

EGU24-12747 | Orals | CL1.2.2 | Highlight

Fennoscandian AND Yamalian tree-ring anatomy shows a warmer modern than medieval climate 

Jesper Björklund, Kristina Seftigen, Markus Stoffel, Marina V Fonti, David C Frank, Sven Kottlow, Jan Esper, Patrick Fonti, Hugues Goosse, Håkan Grudd, Björn E Gunnarson, Rashit Hantemirov, Stefan Klesse, Vladimir Kukarskih, Daniel Nievergelt, Elena Pellizzari, Marco Carrer, and Georg von Arx

Earth system models and various climate proxy sources indicate that global warming is unprecedented during at least the Common Era. However, tree-ring proxies often estimate temperatures during the Medieval Climate Anomaly (950–1250 CE) to be similar, or exceed, those recorded for the past century. This is in contrast to simulation experiments at regional scales. This not only calls into question the reliability of models as well as proxies, but also contributes to uncertainty in future climate projections. Here we show that the current climate of Fennoscandia is substantially warmer than during the medieval period. This indicates a dominant role of anthropogenic forcing in climate warming even at the regional scale, thereby reconciling differences between reconstructions and model simulations. These results were obtained using an annually resolved 1,170-year-long tree-ring record that relies exclusively on tracheid anatomical measurements from Pinus sylvestris trees. Now we can confirm these results using new tree-ring anatomy data developed from Larix Sibirica tree-ring samples from the Yamal Peninsula in North-western Siberia over the past millennia. Both these datasets provide exceptional high-fidelity measurements of instrumental temperature variability during the warm season. We call for the construction of more such millennia-long records to continue to improve our understanding and reduce uncertainties around historical and future climate change at increasingly larger scales.

How to cite: Björklund, J., Seftigen, K., Stoffel, M., Fonti, M. V., Frank, D. C., Kottlow, S., Esper, J., Fonti, P., Goosse, H., Grudd, H., Gunnarson, B. E., Hantemirov, R., Klesse, S., Kukarskih, V., Nievergelt, D., Pellizzari, E., Carrer, M., and von Arx, G.: Fennoscandian AND Yamalian tree-ring anatomy shows a warmer modern than medieval climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12747, https://doi.org/10.5194/egusphere-egu24-12747, 2024.

During the past decades, the Arctic has experienced a more rapid and pronounced temperature increase than most other parts of the world. However, to fully understand the mechanisms and consequences of contemporary and future climate change, it is necessary to study past natural changes in climate and the environment. There is a lack of comprehensive and complementary studies about past changes on a scale of hundreds of years, in which climatic conditions can be reconstructed with high-resolution and replication. Greenland, covered by approximately 90 % of the Greenland ice sheet, is particularly vulnerable to climate change. The Greenland temperature proxy reconstructions are mostly based on ice cores or varve sediments. Available early-instrumental observations reach the second half of the 18th century. The aim of our study was to explore the potential of juniper shrubs growing in multiple sites from hitherto unexplored locations in Greenland, to create and extend growth-ring chronologies back in time, and thus further our knowledge of regional climate variations in the past. Around 90 wood samples were collected from three sites in southern Greenland: Narsarsuaq, Kiattuut Sermiat and Qassiarsuk. From each site, both living and dry wood were available. In addition, we analysed 35 historical juniper discs collected during the Danish expeditions to Greenland at the turn of the 19th and 20th centuries. Data processing was extremely difficult due to very narrow growth rings as well as the occurrence of missing and false rings. Thus, we performed double-stained microscopic sections for each specimen. In addition, anomalies in the anatomy of wood were found, such as frost rings and density fluctuations, related to extreme climatic conditions. Most of the analysed juniper specimens were of similar biological age, i.e. 200-280 for living shrubs, up to 310 years for dead wood, and even 350 for historical discs. However, they have been dated to different time periods, enabling the construction of a 487-year-long growth-ring chronology (1536-2023). The combination of this unique dendrochronological material made it possible to develop a chronology of Juniperus communis dating back to the beginning of the Little Ice Age. Up to now, these juniper shrubs are the oldest ones found in Greenland. The possibilities of extending this record in time using archaeological wooden artefacts are being discussed. The newly developed dendrochronological data, as an important element within the Arctic dendrochronological network, will allow a better understanding of environmental changes and human interaction in Greenland.

The research was funded by a Polish National Science Centre project no. UMO-2019/35/D/ST10/03137.

How to cite: Opala-Owczarek, M. and Owczarek, P.: Old juniper shrubs from the area of Norse Greenlandic Settlements: toward a long growth-ring chronology and its climatic implications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13413, https://doi.org/10.5194/egusphere-egu24-13413, 2024.

EGU24-14763 | ECS | Posters on site | CL1.2.2

Rapid detection of elements' radial translocation and mobility in tree rings by iTrax core scanner 

Hsin-Lin Wei, Chuan-Chou Shen, Ludvig Löwemark, Chien-Yi Liao, Shu-Li Chen, and Chun-Kuang Hsieh

Dendrochemistry has been developed as a new environmental indicator in recent decades. Elements, such as Hg, Pb, and Cd, in tree rings were considered as new tracers for industrialization, air pollution, and soil contamination. However, the movement and diffusion of elements across the rings, called radial translocation, intensifies when the sapwood transforms into heartwood, which blurs the elemental records. Detecting the translocation of elements and their mobility in tree rings due to heartwood formation is crucial for the availability and confidence of applying dendrochemistry. We developed methods to evaluate radial translocation. 1. The iTrax core scanner was used to scan tree ring core slices of four conifers in Taiwan to evaluate the feasibility of applying the iTrax core scanner to analyze the elemental trends in tree ring cores and the scanning parameters. 2. The elemental distributions in tree ring cores of different species were measured. 3. The mobilities of elements were evaluated. Forty-second exposure was successful and reproducibly scanned K, Ca, V, Cr, Mn, Fe, Cu, Sr, and Pb contents. Results show that the levels of Ca and K in the tree ring of all four species and the levels of Mn of three species significantly differ between the heartwood and sapwood phases. For the remaining elements, including V, Cr, Fe, Cu, Sr, and Pb, there is no significant difference between phases. After treating with an extraction solution to remove soluble or mobile elements, the different levels of Ca, K, and Mn between phases were not observed, indicating the mobility of these elements. The effect of radial translocation should be considered when applying the three elements as environmental tracers.

How to cite: Wei, H.-L., Shen, C.-C., Löwemark, L., Liao, C.-Y., Chen, S.-L., and Hsieh, C.-K.: Rapid detection of elements' radial translocation and mobility in tree rings by iTrax core scanner, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14763, https://doi.org/10.5194/egusphere-egu24-14763, 2024.

EGU24-15959 | Posters on site | CL1.2.2

Detecting changes in industrial pollution through the analyses of heavy metals concentrations in tree-ring wood from Romanian conifer forests 

Cosmin Cuciurean, Cristian Gheorghe Sidor, J. Julio Camarero, Amelia Buculei, and Ovidiu Badea

The impact of air pollution on forests, especially in urban areas, has been an increasingly discussed topic in recent years. A number of pollutants, including heavy metals, are released into the atmosphere from various sources, such as mining activities, non-ferrous metal processing plants, fossil fuel combustion, and can have adverse effects on tree growth but also on vigor of other species including humans.

We compared the concentrations of several elements in tree-ring wood from two conifer species (Silver fir-Abies alba, and Norway spruce-Picea abies) growing in polluted and unpolluted areas. Two regions (Bicaz and Tarnița) subjected to historical changes in pollution and located in northern Romania were selected. Two methods of chemical analyses were used: inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence spectrometry (XRF).

Silver fir trees from the intensively polluted area in Tarnița region are negatively impacted by industrial pollution according to their Mn concentrations in wood which are, on average, three times higher than in the unpolluted areas (ca. 30 vs. 10 mg·kg-1). This finding is consistent with both ICP-MS and XRF analyses, but this difference was found in Norway spruce only in XRF data which detected 7 times higher Mn concentrations in trees from polluted areas than in those from unpolluted areas (ca. 700 vs. 100 mg·kg-1).

In the Tarnița region, Norway spruce was able to accumulate a higher quantity of heavy metals compared to Silver fir, but the most pronounced differences between polluted and unpolluted were found in Silver fir.

The two analysis methods complemented each other with ICP-MS being a qualitative method with a low detection limit of some elements, and XRF being a more quantitative method with high detection limit and satisfactory accuracy.

How to cite: Cuciurean, C., Sidor, C. G., Camarero, J. J., Buculei, A., and Badea, O.: Detecting changes in industrial pollution through the analyses of heavy metals concentrations in tree-ring wood from Romanian conifer forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15959, https://doi.org/10.5194/egusphere-egu24-15959, 2024.

EGU24-16465 | ECS | Posters on site | CL1.2.2

Forest inventory tree core archive reveals changes in boreal wood traits over seven decades 

Kelley R. Bassett, Lars Östlund, Michael J. Gundale, Jonas Fridman, and Sandra Jämtgård

Boreal forests play an important role in the global carbon cycle (C), and there is increasing interest in understanding how they react to environmental changes, including nitrogen (N) and water limitations, which may influence future forest growth and C storage. Utilizing tree cores archived by the Swedish National Forest Inventory, we measured stemwood traits, including stable N and C isotope composition, which provides information on N availability and water stress, respectively, as well as N and C content, and the C/N ratio over the period 1950–2017 in two central Swedish counties, Jämtland and Västernorrland, covering an area of ca. 55,000 sq. km (n = 1038). We tested the hypothesis that wood traits change over time and that temporal patterns would vary depending on alternative dendrochronological reconstruction methods, i.e. the established standard “single tree method” (STM) or a conceptually stronger “multiple tree method” (MTM). Averaged across all MTMs, our data showed that all five wood traits for Picea abies and Pinus sylvestris changed over time. Wood δ15N declined strongly, indicating progressive nitrogen limitation. The decline in δ13C followed the known atmospheric δ13CO2 signal, indicating there was no change in water stress. In addition, wood N increased significantly, while C and C/N ratios declined over time. Furthermore, wood trait patterns sometimes differed between dendrochronological methods. The most prominent difference was for δ15N, where the slope was much shallower for the STM compared to MTMs for both species, indicating that mobiity of contemporary N is problematic when the STM is used, leading to much less sensitivity to detect historical signals. Our study shows strong temporal changes in boreal wood traits and also indicates that the field of dendroecology should adopt new methods and archival protocols for studying highly mobile element cycles, such as nitrogen, which are critical for understanding environmental change in high latitude ecosystems.

How to cite: Bassett, K. R., Östlund, L., Gundale, M. J., Fridman, J., and Jämtgård, S.: Forest inventory tree core archive reveals changes in boreal wood traits over seven decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16465, https://doi.org/10.5194/egusphere-egu24-16465, 2024.

EGU24-16567 | Posters on site | CL1.2.2

804 years drought reconstruction based on oak tree rings for Eastern Europe 

Catalin-Constantin Roibu, Monica Ionita, Andrei Mursa, Alan Crivellaro, Tomasz Wazny, Viorica Nagavciuc, Mihai-Gabriel Cotos, Marian-Ionut Stirbu, Maria-Ecaterina Asandei, and Cosmin-Mihai Andriescu

In this study, we used the Suceava oak tree-ring width chronology to reconstruct the paleo hydroclimatic events in eastern Europe, a region for which high-resolution paleoclimatic evidence is broadly missing. Our regional oak chronology reflects July hydroclimate variability in the form of the twelve months Standardized Precipitation Index over large parts of Romania, Ukraine, and the Republic of Moldova, for which high-resolution paleoclimatic evidence is broadly missing. Most of the reconstructed hydroclimatic extremes back to 1216 CE are confirmed by documentary evidence, and a robust association is found with large-scale atmospheric circulation patterns in the Northern Hemisphere and sea surface temperatures over the North Atlantic. Reconstructed pluvials coincide with a high-pressure system over the North Atlantic Ocean and north-western Europe, and with a low-pressure system over south-western, central, and eastern Europe, whereas historical droughts coincide with a high-pressure system over Europe and a low-pressure system over the central part of the Atlantic Ocean.

How to cite: Roibu, C.-C., Ionita, M., Mursa, A., Crivellaro, A., Wazny, T., Nagavciuc, V., Cotos, M.-G., Stirbu, M.-I., Asandei, M.-E., and Andriescu, C.-M.: 804 years drought reconstruction based on oak tree rings for Eastern Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16567, https://doi.org/10.5194/egusphere-egu24-16567, 2024.

EGU24-17143 | ECS | Posters on site | CL1.2.2

A multiproxy comparison of Scots pine wood in western Norway  

Wendy Hlengiwe Khumalo, Helene Løvstrand Svarva, Marie-Josée Nadeau, Martin Seiler, Bente Philippsen, Matias Kallevik, and Dominik Collet

With the onset of anthropogenic climate change, the ClimateCultures project aims to tackle the question “What happened the last time we encountered rapid climate change?” using evidence from tree rings and historical records to paint a picture of the natural impacts and societal responses in Norway during the Little Ice Age. More specifically, we aim to investigate short-lived extreme cold events in the 1700’s. This calls for a more regional scale to account for complex climate drivers over a mountainous country with regional climatic differences and local communities’ responses. Here we present a case study of Scots pine wood collected in western Norway, a region known for mild temperatures and high precipitation (relative to average Norwegian climate), and compare various tree ring proxies including ring width, Blue Intensity and stable oxygen isotopes. While this record does not extend to the 1700’s, we can consider the merits and limitations of each proxy when compared to the instrumental records. This study will provide a basis for climate reconstructions, particularly focusing on hydroclimate signals in Norwegian chronologies. 

How to cite: Khumalo, W. H., Svarva, H. L., Nadeau, M.-J., Seiler, M., Philippsen, B., Kallevik, M., and Collet, D.: A multiproxy comparison of Scots pine wood in western Norway , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17143, https://doi.org/10.5194/egusphere-egu24-17143, 2024.

EGU24-17581 | ECS | Posters on site | CL1.2.2

Predisposition of European beech to drought-induced die-off along a climate gradient in Northern Bavaria 

Anja Žmegač and Christian S. Zang

Climate change is strongly influencing global shifts in forest ecosystem dynamics. There has been a twofold increase in canopy mortality within the temperate forests of Europe in the past thirty years. The trend has been further intensified by recent drought episodes occurring between 2018 and 2020, leading to increased instances of die-offs and reduced vitality among key tree species.

In central Europe, notably in Germany, European beech (Fagus sylvatica L.) stands out as a tree species with high ecological and economic significance. Recent severe drought conditions led to substantial vitality loss and mortality. Nevertheless, there was considerable diversity in how individual beech trees responded to drought, with some trees in the same location being heavily impacted while others remained seemingly unaffected. Factors influencing this uneven response are still not fully understood.

In this study, we gathered 600 beech tree-ring width series from 13 sites located across Northern Bavaria, along a climatic gradient. We explore the differences in growth between two groups of trees (damaged/vital) using a dendroecological approach. We evaluated loss of vitality through the implementation of mortality and critical slowdown indicators such as long-term growth decline or changes in climate memory, as well as climate/growth relations and growth synchrony indicative of changing growth limitations.

While we did not find significant differences between groups in terms of climate memory and drought sensitivity, our results showed a divergence in the growth patterns of vital and damaged trees following repetitive exposure to drought events. We detected higher growth rates of damaged trees prior to the last three decades, after which their growth rates declined stronger than vital trees. Our results suggest that faster-growing beech trees may be more susceptible to drought-induced mortality, which is in line with findings of higher vulnerability of faster-growing trees to environmental stressors.

How to cite: Žmegač, A. and Zang, C. S.: Predisposition of European beech to drought-induced die-off along a climate gradient in Northern Bavaria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17581, https://doi.org/10.5194/egusphere-egu24-17581, 2024.

EGU24-17582 | Orals | CL1.2.2

Increasing stem dimensions of European temperate tree species between 1990 and 2015 

Vaclav Treml, Jan Tumajer, Jan Altman, Vojtěch Čada, Jiří Doležal, Pavel Janda, Ryszard Kaczka, Jakub Kašpar, Tomáš Kolář, Jiří Mašek, Filip Oulehle, Michal Rybníček, Miloš Rydval, Miroslav Svoboda, Martin Šenfeldr, Pavel Šamonil, Ivana Vašíčková, and Monika Vejpustková

Increasing forest CO2 absorption is ensured by enhanced gross primary production (GPP) which exhibited increasing trends as documented by CO2 flux measurements or by global vegetation models. Considering the simultaneous increase in ecosystem respiration, it is, however, uncertain how the growing GPP imprints in tree stem biomass increase. There is still a certain discrepancy between estimates of forest biomass trends derived from standardized tree-ring series, information acquired from repeated re-measurements of stem biomass at permanent plots, and information derived from vegetation models or flux-tower measurements.  Standardization procedures of tree-ring series related to age/size trend removal make this data source unique for the assessment of climate-growth relationships and for climatic reconstruction, however it also increases uncertainty of this data source for biomass trends assessment. Here, we present an approach mimicking repeated data collection at permanent plots based on an extensive data set of tree-ring sites.  In this way, we connected two strong benefits of above-mentioned data – reliable age-independent estimates of stem biomass by repeated measurements at permanent plots and a dense network of highly replicated data covering wide environmental gradients provided by tree-ring time series. Our tree-ring network captures core parts of distribution ranges of five main European temperate tree species. Density of tree-ring network is roughly 1 site per 25 km2 of forested area in Central Europe namely Czech Republic (area of 78 000 km2) making this tree-ring network probably densest in the world.  We first manipulated original tree-ring data sets by their truncation in 1990 (data set mimicking sample collection in 1990) and then adapt the original data set so that it has similar age structure as the 1990 data set mainly by excluding old age classes (data set 2015) assuring age independency of our data. For both data sets and all sites included, we calculated mean stem diameter at breast height (DBH) of average 100-year old tree based on basal area increments. We then tested for differences in DBH between 1990 and 2015. We found that all species except Pinus sylvestris showed a significant increase in stem dimension as indicated by DBH between 1990 and 2015. The highest DBH increase exhibited Abies alba (+13.5%), followed by Fagus sylvatica (+5.5%), Quercus sp.(+5.2%) and Picea abies (+4.7%).  Differences in DBH between 2015 and 1990 were relatively homogenous across environmental gradients suggesting prevailing influence of large-scale factors independent on local conditions.  Picea abies and Fagus sylvatica exhibited lesser increase in stem dimensions in colder areas. Furthermore, Picea abies and Quercus sp. showed a significant enhancement of growth at productive sites with fast growing individuals. Quercus also significantly enlarged DBH at locations with more positive trends in SPEI, i.e. those experiencing a trend towards wetter climate. Our results corroborate the pervasive growth acceleration in core region of European temperate forests leading to presence of larger canopy-level trees in current forests than in the past. Increasing stem size makes trees more sensitive to disturbances and potentially leads to their shorter life spans as reported in other studies.

How to cite: Treml, V., Tumajer, J., Altman, J., Čada, V., Doležal, J., Janda, P., Kaczka, R., Kašpar, J., Kolář, T., Mašek, J., Oulehle, F., Rybníček, M., Rydval, M., Svoboda, M., Šenfeldr, M., Šamonil, P., Vašíčková, I., and Vejpustková, M.: Increasing stem dimensions of European temperate tree species between 1990 and 2015, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17582, https://doi.org/10.5194/egusphere-egu24-17582, 2024.

EGU24-18975 | Orals | CL1.2.2

Climate signal in Pericopsis elata tree rings d18O series and potential for precipitation reconstructions in the eastern Congo Basin 

Tom De Mil, Daniele Colombaroli, Nestor Luambua, Chadrack Kafuti, Paolo Cherubini, Matthias Saurer, Wannes Hubau, and Hans Beeckman

it is unclear whether pronounced droughts reaching the most remote regions of the Congo Basin are within a historical norm or have occurred only in the last decades. There is a growing evidence that a number of species with anatomically distinct rings can be used for dendroclimatological studies in the Congo Basin, such as Afrormosia (Pericopsis elata) (PEEL). Annual growth increments, i.e. Tree-Ring Width (TRW), are often co-determined by many environmental factors and yield low potential for reconstructions. Earlier work has shown that δ18O measured in PEEL tree rings holds a precipitation amount effect. Here we focus on new P. elata isotope series to estimate the isotope-precipitation relationship at the annual-scale and discuss its potential for reconstructing precipitation variability back to 1850 AD. δ18O values yielded better sensitivity as well as coherence between trees compared to TRW. Lower δ18O values (28-29‰) after 1960 reflect the anomalously wetter conditions between 1950 and 1970 recorded in the Congo Basin and neighbouring areas. Higher δ18O values after 1970 are in agreement with the reduction in precipitation reflected in gauges and satellite data. Further comparisons with instrumental data and other proxies can refine a precipitation reconstruction currently extending to 1850 AD.

How to cite: De Mil, T., Colombaroli, D., Luambua, N., Kafuti, C., Cherubini, P., Saurer, M., Hubau, W., and Beeckman, H.: Climate signal in Pericopsis elata tree rings d18O series and potential for precipitation reconstructions in the eastern Congo Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18975, https://doi.org/10.5194/egusphere-egu24-18975, 2024.

EGU24-20227 | ECS | Posters on site | CL1.2.2

Converging trends and strengthening climatic signal in the radial growth of Abies alba in Austria – between the legacies of “Waldsterben” and the era of climate change? 

Balázs Garamszegi, Michael Grabner, Elisabeth Wächter, Josef Gadermaier, and Klaus Katzensteiner

Silver fir (Abies alba) is a key forest tree species in Central Europe growing most commonly in its mixtures with Fagus sylvatica and Picea abies. It is also an important species to dendrochronology due to its longevity, historic timber utilization, and generally well-synchronized interannual growth series. However, a growing number of dendroecological studies focusing on climate change has left the species relatively underrepresented even compared to its lower abundance as a dominant forest tree species. It is also due to its weaker growth–climate relationship, compared to species growing in more climatically limited (first of all water-limited) environments. In forest sciences, the species has received wide attention during the complex forest decline phase after the late 1970s and during the 1980s, referred to as the “Waldsterben” in the German-speaking countries of Central Europe, highlighting the negative effects of air pollution of that time, particularly in the context of silver fir. In the era of climate change, the species is gaining renewed interest, especially for its further admixing potential to climatically more resilient forest stands.

In our study, we have investigated the long-term trends and the interannual climatic signal in the radial growth chronologies from monospecific stands of silver fir at seven sites representing a broad climatic and elevational gradient along the distribution of the species. The measured chronologies reveal an increasing low-frequency growth synchrony, starting with a periodic growth increase at the investigated sites since the 1980s, regardless of tree and stand age. Preliminary correlation results suggest that the water-balance related climatic signal has been introduced or has significantly increased between the periods 1961–1990 and 1991–2020. This has been partly associated with a shift or even clear change of sign in the temperature signal. Significant relationships, yet with varying sign, have been also found with the atmospheric water vapor content at each site.

The main research questions aim to focus on the pace and term of this change manifested in the climatic signal, namely (i) whether the growing conditions have changed over longer term or were rather influenced by specific years, (ii) if the change was abrupt or more gradual over time. To answer these questions, different climate data-driven models are fitted to the (detrended) growth series, and the error of the model fit is assessed by shorter windows. The temporal patterns of the change, together with the general growth trends identified, are compared to the climatic trends and the frequency of drier periods since the 1980s, with attention to the timescale of the “Waldsterben” phenomena. The interpretation of the results shall reflect a complex interplay of different drivers of forest conditions during the last decades of the 20th century and the inherent uncertainties thereof. Nevertheless, it can contribute to the dendroecological knowledge of an ecologically and silviculturally important species at the crossroads of past legacies, current and predicted challenges.

How to cite: Garamszegi, B., Grabner, M., Wächter, E., Gadermaier, J., and Katzensteiner, K.: Converging trends and strengthening climatic signal in the radial growth of Abies alba in Austria – between the legacies of “Waldsterben” and the era of climate change?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20227, https://doi.org/10.5194/egusphere-egu24-20227, 2024.

EGU24-20751 | ECS | Posters on site | CL1.2.2

Determining influencing factors of climate-growth relationships of European beech across its ecological amplitude 

Christopher Leifsson, Allan Buras, Anja Rammig, and Christian Zang and the Beech Network

The prospect for European beech forests (Fagus sylvatica L.) over the course of the 21st century is uncertain due to climate change. In context, climate sensitivity of growth is a valuable indicator of physiological integrity, but its natural variability is poorly understood in productive, closed canopy forests. Climate sensitivity may not only depend on temporal and spatial differences in climatic conditions, but also on trees’ rank progression in the course of forest maturation.

Here, we determine how the drought sensitivity of secondary growth in beech varies in space and time according to growth trends, growth variability and climatic conditions. The temporal variability of these variables is determined via a moving window approach using a network of tree-ring sites across the species’ geographical and climatological distribution. The moving window derived variables are applied to a linear mixed-effects model allowing for the estimation of linear, non-linear and interactive effects. Furthermore, dry and wet subsets of the data are supplied individually to determine differences between dry and wet site conditions.

Our results indicate considerable variability in climate sensitivity due to complex non-linear and interactive effects of all variables. Generally, drought sensitivity is strongly and positively coupled with growth variability and climatic aridity. The strong non-linear and interactive effects between all variables result in drought sensitivity changing considerably with changes in growth variability and growth trends when climatic conditions are average or wetter than average. However, during dry time-periods, drought sensitivity is consistently high and decoupled from changes in growth trends and growth variability. While these patterns remain relatively similar between dry and wet sites, dry sites show significantly higher drought sensitivity compared to wet sites overall.

In conclusion, we found beech’s drought sensitivity to be significantly affected by growth variability, growth trends and climatic conditions. Furthermore, the influence of each variable on drought sensitivity changes drastically as they interact, indicating all these factors need to be considered when interpreting beech’s climate sensitivity.

How to cite: Leifsson, C., Buras, A., Rammig, A., and Zang, C. and the Beech Network: Determining influencing factors of climate-growth relationships of European beech across its ecological amplitude, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20751, https://doi.org/10.5194/egusphere-egu24-20751, 2024.

EGU24-20980 | Posters on site | CL1.2.2

Contrasting water use strategies to climate warming in white birch and larch in a boreal permafrost region 

Xi Qi, Kerstin Treydte, Matthias Saurer, Keyan Fang, Wenling Ann, Marco Lehmann, Kuyuan Liu, Zhengfang Wu, Hong He, Haibo Du, and Mai-He Li

The effects of rising atmospheric CO2 concentrations (Ca) with climate warming on intrinsic water-use efficiency (iWUE) and radial growth in boreal forests are still poorly understood. We measured tree-ring cellulose δ13C,δ18O, and tree-ring width in Larix dahurica (larch) and Betula platyphylla (white birch), and analyzed their relationships with climate variables in a boreal permafrost region of northeast China over past 70 years covering a pre-warming period (1951-1979; base period) and a rapid-warming period (1980-2018; warming period). We found that white birch but not larch significantly increased their radial growth over the warming period. The increased iWUE in both species was mainly driven by elevated Ca but not climate. White birch but not larch showed significant positive correlations between tree-ring δ13C,δ18O and summer maximum temperature as well as vapor pressure deficit in the warming period, suggesting a strong stomatal response in the deciduous birch but not in the conifer larch to climate warming. The climate-warming induced radial growth enhancement in white birch is associated with a more ‘conservative’ (low gs, constant A) water use strategy than in larch (constant gs, high A), suggesting an advantage for the former than the latter in a warming world in the permafrost regions.

How to cite: Qi, X., Treydte, K., Saurer, M., Fang, K., Ann, W., Lehmann, M., Liu, K., Wu, Z., He, H., Du, H., and Li, M.-H.: Contrasting water use strategies to climate warming in white birch and larch in a boreal permafrost region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20980, https://doi.org/10.5194/egusphere-egu24-20980, 2024.

EGU24-22320 | Posters on site | CL1.2.2

Novel provenance approaches for tracing Cedrela timber in Bolivia 

Kathelyn Paredes Villanueva, Akira Kagawa, Hisashi Abe, Miho Kojima, Chunhua Zhang, Shinta Ohashi, Akiko Akita, Kanae Takahashi, Maria Uriarte, and Laia Andreu-Hayles

Illegal logging and its related timber trade is one of the major drivers of forest loss, species diversity and economic and social conflicts. Over the last decades, several international and national regulations have been implemented as an attempt to flight this practice. At the same time, different scientific approaches such as genetics, mass spectrometry, and wood anatomy show great potential for timber identification. Our objective was to assess the potential of Near Infrared Spectrometry (NIRS), chemical elements and stable isotopes as tools to increase accuracy of site of origin identification for Cedrela fissilis. Between 3 to 4 tree cores were collected at breast height from Cedrela trees from three sites in Southeastern Bolivia. For the isotopic analysis, annual tree rings were identified and dated. Cellulose extraction was extracted from the cores following the standard methodology of Jayme-Wise. Wood flakes without previous treatment were complementarily analyzed using a MATRIX-F spectrometer (Bruker Optics) for the NIR measurement and a Niton XL3t XRF Analyzer for the elemental analyses. We then used Principal Component Analyses (PCA) and Random Forest to assess the potential of these methods to discriminate among sampling sites. Random Forest on elemental raw data had a site discrimination accuracy about 84%, with strontium (Sr), copper (Cu) and Cadmium (Cd) as potential tracers. For NIRS spectra, PC1 explained 99% of the variance with mean site discrimination accuracy about 78%. Preliminary results of stable oxygen (δ18O) and carbon (δ13C) isotopes showed distinct patterns across the sites but accuracy is still under evaluation through the analyses of annual measurements. Although discrimination accuracies were similar among timber identification methods, each method has the potential to identify a different site. Our preliminary results suggest that site discrimination performance may be specific to each method and site.

How to cite: Paredes Villanueva, K., Kagawa, A., Abe, H., Kojima, M., Zhang, C., Ohashi, S., Akita, A., Takahashi, K., Uriarte, M., and Andreu-Hayles, L.: Novel provenance approaches for tracing Cedrela timber in Bolivia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22320, https://doi.org/10.5194/egusphere-egu24-22320, 2024.

EGU24-3704 | Orals | CL1.2.3 | Highlight

High-resolution reconstruction of infiltration in the South Pacific based on stalagmites fabrics and chemistry. 

Silvia Frisia, Mohammadali Faraji, Andrea Borsato, Adam Hartland, John Hellstrom, Danielle Verdon-Kidd, and Alan Greig

Annually laminated stalagmites provide hydroclimate proxy data extending well beyond the instrumental period. Calcite fabric, stable isotope ratios and trace element time series from stalagmites from Pouatea cave in the Southern Cook Islands were used to reconstruct the variability of effective infiltration over the past 350 years. The reconstruction was validated through cave monitoring, dripwater hydrochemistry, calcite farming experiments, and comparison with rainfall instrumental data and climate index records.  

 

Infiltration was found to modulate trace element variations at a seasonal scale, via dilution of marine aerosols contribution reduced rock–water interaction time and reduced prior calcite precipitation.  To quantify infiltration, trace elements were utilized to complement the C and O isotopes ratios and fabric-based reconstructions of wet/dry phases.  Through regression analysis Mg, Na, and P were identified as the elements most sensitive to infiltration, while Sr, Ba, U and Y display a more complex behaviour. Magnesium was found to be the most reliable element for hydroclimate reconstruction, superior to Na even though they both predominantly derive from marine aerosol. This difference can be attributed to the incorporation of Na+ in speleothems, which mostly depends on the availability of inter-crystalline sites and/or nano-porosity, whereas Mg2+ substitutes for Ca2+ in the calcite lattice and is mostly unaffected by crystal fabric.

 

Transmission Electron Microscope investigations and associated EDS-based elemental mapping allowed observing that the presence of Na inhibits pathways of calcite crystallization by particle attachment) which then result in more compact fabrics during dry periods when the influence of marine aerosols is enhanced. When crystallization by particle attachment is dominant, both micro- and nano-porosity characterize the resulting fabric. Consequently, a porous fabric would mark periods of more intense infiltration, most likely because of the dilution of inhibitors such as Na (and Mg).

 

Transfer functions were then established between Mg and effective infiltration. Overall, the O isotope ratios, trace elements and fabric-based reconstructed infiltration data indicate that the main driver of rainfall in the South Pacific is the location of the South Pacific Convergence Zone (SPCZ), which in turn is modulated by the El Nino Southern Oscillation (ENSO).

How to cite: Frisia, S., Faraji, M., Borsato, A., Hartland, A., Hellstrom, J., Verdon-Kidd, D., and Greig, A.: High-resolution reconstruction of infiltration in the South Pacific based on stalagmites fabrics and chemistry., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3704, https://doi.org/10.5194/egusphere-egu24-3704, 2024.

EGU24-4596 | Orals | CL1.2.3 | Highlight

A precipitation dipole between central Nepal and eastern India during the 4.2 ka event 

Rhawn Denniston, Benjamin Tiger, Ethan Wimmer, Caroline Ummenhofer, Yemane Asmerom, Alan Wanamaker, Victor Polyak, Diana Thatcher, Ashok Gurung, and Surya Thapa Magar

Over the late Holocene, a variety of hydroclimate-sensitive proxies have identified substantial, multidecadal changes in Indian summer monsoon (ISM) precipitation, the most prominent of which is the “4.2 ka event”. This interval, dated to ~4.2-3.9 ka, is associated with severe droughts across South Asia that are linked to societal change. Given the absence of the 4.2 ka event in polar records, the 4.2 ka event is generally associated with low latitude forcings, but no clear consensus on its origins has been reached.
We investigated the ISM response to the 4.2 ka event through analysis of aragonite stalagmites from Siddha cave, formed in the lower Paleozoic Dhading dolomite in the Pokhara Valley of central Nepal (28.0˚N, 84.1˚E; ~850 m.a.s.l.). The climate of this region is dominated by small monthly variations in air temperature (21±5˚C) but strong precipitation seasonality associated with the ISM: ~80% of the annual 3900 mm of rainfall occurs between June and September. High uranium and low detrital thorium abundances in these stalagmites yield precise U/Th ages that all fall within stratigraphic order. These dates reveal continuous growth from 4.30-2.26 ka, interrupted only by a hiatus from 3.27-3.10 ka. Overlap with coeval aragonite stalagmites reveals generally consistent trends in carbon and oxygen isotope ratios, suggesting that these stalagmites reflect environmental variability and not secondary (e.g., kinetic) effects.
Many stalagmite-based paleomonsoon reconstructions rely on oxygen isotope ratios, which track amount effects in regional rainfall. However, our on-going rainwater collection and analysis program, as well as a previous study conducted in Kathmandu, 120 km the east of Siddha cave, reveals that amount effects in precipitation are weak in this region, particularly during the monsoon season, and thus we rely instead on carbon isotope ratios, which have been demonstrated to track site-specific effective precipitation. Siddha cave stalagmite carbon isotopes, in contrast to other South Asian proxy records, indicate that ISM rainfall increased at Siddha cave from 4.13-3.91 ka. As a further test of this result, we analyzed uranium abundances in the section spanning 4.3-3.4 ka. Uranium serves as an indicator of prior aragonite precipitation and thus of hydroclimate, and like carbon isotopes, suggests increased ISM rainfall coincident with the 4.2 ka event.
This precipitation anomaly is nearly identical in timing and structure but anti-phased with stalagmites from Mawmluh cave, northeastern India. We investigated the climatic origins of this precipitation dipole using observational data from the Global Precipitation Climatology Centre (GPCC) and Hadley Center Sea Ice and Sea Surface Temperature (HadISST) products. Preliminary spatial composites suggest that large precipitation differences between Mawmluh and Siddha caves are associated with SST anomalies in the equatorial Pacific. Additionally, superposed Epoch Analysis shows relatively rapid eastern Indian Ocean cooling during the summer monsoon season coeval with large precipitation differences between these sites. Our findings lend support to a tropical Indo-Pacific origin of the 4.2 ka event.

How to cite: Denniston, R., Tiger, B., Wimmer, E., Ummenhofer, C., Asmerom, Y., Wanamaker, A., Polyak, V., Thatcher, D., Gurung, A., and Thapa Magar, S.: A precipitation dipole between central Nepal and eastern India during the 4.2 ka event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4596, https://doi.org/10.5194/egusphere-egu24-4596, 2024.

EGU24-5107 | ECS | Posters on site | CL1.2.3 | Highlight

Increased millennial-scale monsoonal circulation amplitude across the mid-Pleistocene transition revealed via speleothem records 

Xiaowen Niu, Jian Wang, Le Kang, Haiwei Zhang, Hai Cheng, and Youwei Li

The Asian summer monsoon (ASM) represents a significant and expansive element within the global climate system. While speleothem δ18O records offer robust characterization of millennial-scale ASM variations over the last 640 ka (thousand years), limited data exists regarding the ASM's behavior preceding the U-Th dating limit of approximately 640 ka. This includes periods such as the mid-Pleistocene Transition (MPT, ~800-1200 ka) and the pre-MPT era. In this study, we present two meticulously calibrated high-resolution speleothem δ18O records sourced from central China. These records span three distinct periods: 640–615, 690–660, and 1,360–1,310 ka BP ( thousand years before present, the present defined as 1950 CE). The absolute dating of these records is accomplished via laser ablation and isotope dilution U-Pb methods. Our meticulous tuning aligns these records with the summer insolation (690–660 and 1,360–1,310 ka BP) and the preceding record (640–615 ka BP). Our findings indicate a close association between millennial-scale weak ASM occurrences and North Atlantic stadials and Antarctic warming events within the period of 685–675 ka BP, similar to previously established connections within the last 640 ka. Furthermore, millennial-scale ASM variations occurred prior to the MPT, specifically during the period of 1360–1310 ka BP, albeit with relatively smaller amplitudes in comparison to those observed after the MPT in the last ~690 ka. We hypothesize that reduced freshwater forcing in the North Atlantic and/or altered freshwater routing to the Gulf of Mexico through the Mississippi drainage system might have resulted in a less pronounced weakening of the Atlantic Meridional Overturning Circulation (AMOC) before the MPT, thereby leading to smaller amplitudes in millennial-scale ASM variations observed during 1360–1310 ka BP.

How to cite: Niu, X., Wang, J., Kang, L., Zhang, H., Cheng, H., and Li, Y.: Increased millennial-scale monsoonal circulation amplitude across the mid-Pleistocene transition revealed via speleothem records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5107, https://doi.org/10.5194/egusphere-egu24-5107, 2024.

EGU24-5371 | ECS | Orals | CL1.2.3

The Impact of Ocean Circulation Changes on the Glacial-Interglacial Difference between EASM and ISM Speleothem Records 

Jian Wang, Hai Cheng, Haiwei Zhang, Yanjun Cai, Jingyao Zhao, and Lijuan Sha

The Asian summer monsoon is a highly complex system that comprises two distinct subsystems: the Indian summer monsoon (ISM) and the East Asian summer monsoon (EASM). A thorough understanding of the intricate change processes and inherent differences between these two subsystems is crucial for deciphering the mechanisms driving climate change and, ultimately, predicting future climate patterns. The Indonesian Throughflow (ITF), a critical component of the global thermohaline circulation, serves as the sole low-latitude channel transporting warm seawater from the tropical Pacific to the Indian Ocean. This circulation directly impacts the mass and heat balance of the Indo-Pacific region.

In this study, we utilized stalagmite samples from southwestern China and obtained high-resolution speleothem records dating back to ~18-9 ka BP. Through meticulous comparison and analysis of speleothem records from both the ISM and EASM regions, we observed significant disparities in the δ18O amplitude between glacial and interglacial, particularly around the Younger Dryas interval. Notably, the timing of this amplitude difference aligns with the flooding of the Karimata Strait, suggesting a potential linkage between the ocean circulation change and monsoon dynamics.

This study delves deeper into the potential impact of the Karimata Strait's flooding on δ18O within ISM and EASM speleothem records. We propose that this flooding redirected freshwater runoff away from the South China Sea, leading to comparatively heavier δ18O of surface seawater in the SCS. Furthermore, it is likely inhibited the surface flow of the ITF, subsequently curtailing heat transfer from the Pacific to the Indian Ocean, combined with an intensified Agulhas leakage during the deglacial, these factors contributed to relative cooling of the Indian Ocean, in turn, magnified the ISM strength relative to that of the EASM. The position of the Walker circulation's ascending branch was also influenced by these oceanic changes. In the early Holocene, this branch shifted eastward, leading to a reduction in distant moisture sources in the EASM region.

The above changes ultimately caused the δ18O of stalagmites in the EASM region to be relatively positive in comparison with that in the ISM region during interglacial, indicating the significance of ocean circulation changes for the evolution of climate system, and may help explaining the “missing” 100 ka signals in EASM speleothem records.

How to cite: Wang, J., Cheng, H., Zhang, H., Cai, Y., Zhao, J., and Sha, L.: The Impact of Ocean Circulation Changes on the Glacial-Interglacial Difference between EASM and ISM Speleothem Records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5371, https://doi.org/10.5194/egusphere-egu24-5371, 2024.

EGU24-6289 | ECS | Posters on site | CL1.2.3

Paleoclimate reconstruction based on speleothems from the Crimean Peninsula 

Yidong Li, Yuri Dublyansky, Christoph Spötl, Hai Cheng, Sergey Tokarev, and Gennady Amelichev

The paleoclimate and paleoenvironmental conditions of Crimea are scarcely known due to the lack of high-resolution archives in this area. Crimean speleothems have a high potential of providing valuable information and filling the knowledge gap on the paleoclimate in the northern part of the Black Sea area.

We acquired six well-dated stalagmite records from Crimean caves which grew during different intervals of the Holocene and MIS 3 with a good overlap, spanning from 2.7 (± 0.1) to 58.0 (± 0.0) ka BP. Records of δ18O and δ13C show some resemblance to the Sofular record from the southern Black Sea coast. However, based on our knowledge of the modern pathways of moisture supply to Crimea (with only ca. 14 % of moisture originating from the Black Sea surface[1]), it can be expected that the controls of stalagmite δ18O values may be different in the south and north of the Black Sea. δ13C records show larger shifts than the δ18O records on the millennial time scale (e.g., Heinrich events) especially during MIS 3. None of the speleothems grew during MIS 2, probably reflecting arid and cold climate conditions.

These records are being analyzed and compared with other paleoclimate records to better understand: (1) the local hydrological dynamics and climate history during the Holocene and MIS 3, (2) the differences in climate conditions between the southern and northern Black Sea regions, and (3) the spatio-temporal teleconnection between the North Atlantic realm and the study area.

 

[1] Langhammer et al. (2021) doi: 10.1029/2021EA001727

How to cite: Li, Y., Dublyansky, Y., Spötl, C., Cheng, H., Tokarev, S., and Amelichev, G.: Paleoclimate reconstruction based on speleothems from the Crimean Peninsula, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6289, https://doi.org/10.5194/egusphere-egu24-6289, 2024.

EGU24-6527 | Orals | CL1.2.3

Chemical weathering response to hydroclimate and soil erosion from Li isotopes in Brazilian speleothems 

David Wilson, Philip Pogge von Strandmann, Nicolas Strikis, Giselle Utida, and Francisco Cruz

Chemical weathering of rocks supplies nutrients to the ocean and draws down atmospheric carbon dioxide, making it a key process in the global carbon cycle. However, the response of chemical weathering to a range of climate variables is not well constrained, either for the past or the future. Obtaining better constraints on the past temporal variability in terrestrial weathering at a catchment scale could therefore help improve this understanding.

Recent studies have used lithium (Li) isotopes to explore the controls on chemical weathering processes over seasonal timescales, with measurements on cave drip-waters indicating an important control of fluid residence times [1], and similar findings being obtained on river waters [2]. These studies open the way for combining Li isotopes in speleothems [3] with multi-proxy reconstructions to assess the climatic controls on past weathering processes over centennial to orbital timescales.

Here, we present Li isotope records from a suite of well-characterised Late Pleistocene and Holocene speleothems from Central Eastern and Northeastern Brazil. These records allow us to assess the effects of millennial-scale precipitation changes during the deglaciation and Meghalayan soil erosion during the Holocene, which were independently reconstructed using other proxies [4,5]. Overall, a comparison of these records indicates a rapid coupling between local hydroclimate and chemical weathering processes in the overlying soils and karst, providing better constraints on the controls on weathering, as well as indicating the potential use of Li isotopes to help constrain the interpretations of other proxy records.

References

[1] Wilson et al. (2021) Seasonal variability in silicate weathering signatures recorded by Li isotopes in cave drip-waters. GCA 312, 194-216.

[2] Zhang et al. (2022) Hydrological control of river and seawater lithium isotopes. Nature Comms. 13, 3389.

[3] Pogge von Strandmann et al. (2017) Lithium isotopes in speleothems: Temperature-controlled variation in silicate weathering during glacial cycles. EPSL 469, 64-74.

[4] Strikis et al. (2018) South American monsoon response to iceberg discharge in the North Atlantic. PNAS 115, 3788-3793.

[5] Utida et al. (2020) Climate changes in Northeastern Brazil from deglacial to Meghalayan periods and related environmental impacts. QSR 250, 106655.

How to cite: Wilson, D., Pogge von Strandmann, P., Strikis, N., Utida, G., and Cruz, F.: Chemical weathering response to hydroclimate and soil erosion from Li isotopes in Brazilian speleothems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6527, https://doi.org/10.5194/egusphere-egu24-6527, 2024.

EGU24-7110 | ECS | Posters virtual | CL1.2.3

Holocene temperature changes in southeastern China reconstructed from stalagmite fluid inclusions 

Zeyuan Liang, Haiwei Zhang, Ye Tian, Hai Cheng, Christoph Spöt, Yanjun Cai, Rui Zhang, Baoyun Zong, and Youfeng Ning

The long-term trends of Holocene temperature obtained from reconstructions and simulations are inconsistent and have been controversial. Paleoclimate reconstructions suggest a gradual cooling after the Holocene climatic optimum, while model simulationss show continued warming. This is the long-standing Holocene conundrum. It is argued that some Holocene temperature reconstructions may be influenced by summer temperature bias. Therefore, finding proxy indicators less influenced by temperature seasonality is crucial in resolving the conundrum. Additionally, temperature reconstruction records in Southeast China are not yet comprehensive, the sensitivity of various proxies, uncertainties in chronology, and the uneven distribution of proxy records have led to significant differences in temperature reconstruction results. Stalagmites inside cave are in a relatively stable environment, and cave monitoring shows that the cave temperature is usually stable and represents the local annual mean temperature. Therefore, utilizing the water stable isotopes from stalagmite fluid inclusions can more accurately reconstruct local annual mean temperatures. This study used hydrogen and oxygen isotopes of three stalagmite samples (SN35, SN38, and SN42) from the Shennong Cave in Southeast China to reconstruct a temperature record for the Holocene (9 ka-0.8 ka). By employing a conversion function between calcite fluid inclusion water isotopes and annual mean temperature, we found the reconstructed cave temperature is ~19.1°C from 2-0.8 ka BP, consistent with the modern local annual mean temperature of 19.1°C, indicating these stalagmites could precisely record the local annual temperature changes. The reconstructed Holocene record shows a slight overall upward trend during the period of 9-0.8 ka BP, in agreement with model simulation results. The records also show a significant drop in temperature around 5.2 ka BP and a further abrupt change in temperature around 4.2ka BP, which may have had an important impact on the origin and decline of Liangzhu, a well-developed neolithic culture in the lower reaches of the Yangtze River.Our new record provides new evidence to resolve the Holocene temperature conundrum.

How to cite: Liang, Z., Zhang, H., Tian, Y., Cheng, H., Spöt, C., Cai, Y., Zhang, R., Zong, B., and Ning, Y.: Holocene temperature changes in southeastern China reconstructed from stalagmite fluid inclusions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7110, https://doi.org/10.5194/egusphere-egu24-7110, 2024.

EGU24-7289 | Posters on site | CL1.2.3 | Highlight

New insights of the Heinrich events inferred by speleothems from Northeast Brazil 

Haiwei Zhang, Hai Cheng, Francisco W. Cruz, Augusto S. Auler, Christoph Spötl, Xianfeng Wang, Nicolás M. Stríkis, Baoyun Zong, and R. Lawrence Edwards

Heinrich events (HEs), characterized by massive and rapid ice-rafted debris from Laurentide Ice Sheet into the Labrador Sea as far south as the Iberian Margin, are observed in some stadial periods during the last glacial, however, it is still unclear regarding to the trigger and response mechanism of the HEs. A landmark work by Wang et al. (2004) was one of the first studies to associate tropical rainfall in southern Hemisphere with HEs, showing wet periods in tropical northeastern Brazil, a region that is currently semi-arid but very sensitive to the hydroclimate changes related to the cold events occurred in the northern Hemisphere, are synchronous with HEs in the North Atlantic. After two decades, we have a new chance to study the relationship between hydroclimate in NE Brazil and cold events in the North Atlantic in the light of much more new speleothem records obtained from TBV and TBR caves, NE Brazil. Here we show evidence of stalagmite growth periods and δ18O records during the last 90 kyrs from NE Brazil, in addition to the HEs observed by Wang et al. (2004), we have newly found wet periods during the HE2 and HE3 and GS 5-8 that were not discovered before. It indicates that previous conclusions that the orbital insolation also modulated these events on millennial timescales need to be reinterpreted, and also provides new insights to understand the mechanisms of the HEs and why the HEs only occurred in some Heinrich Stadials. Additionally, we also compare detailed structures of each HE inferred from cave δ18O records in NE Brazil with sea surface temperature and other records in the Atlantic realm, which deepens our understanding of the trigger-response mechanisms of the HEs and its effect on the hydroclimate in the NE Brazil.

How to cite: Zhang, H., Cheng, H., Cruz, F. W., Auler, A. S., Spötl, C., Wang, X., Stríkis, N. M., Zong, B., and Edwards, R. L.: New insights of the Heinrich events inferred by speleothems from Northeast Brazil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7289, https://doi.org/10.5194/egusphere-egu24-7289, 2024.

EGU24-7716 | Orals | CL1.2.3

MIS 8 to MIS 7 sub-orbital-scale climate variability along the northern Mediterranean borderland recorded in a Macedonian mammillary speleothem 

Marjan Temovski, Kata Molnár, Danny Vargas, László Rinyu, and László Palcsu

The central parts of Southeastern Europe, located along the northern boundary of the Mediterranean region, represent a transient zone affected by both Mediterranean and continental atmospheric influences. An impressive record of past climate variations in this region has been obtained mainly from lacustrine sediments in the southern parts and loess deposits in the northern parts. Although radiometrically dated speleothems provide higher resolution records with superior chronological constrains, not many published speleothem records are available from this region, with none covering Marine Isotope Stage (MIS) 7.

We present here a record of MIS 8 – MIS 7 sub-orbital-scale climate variations obtained from a U-Th dated Macedonian subaqueous speleothem composed of mammillary calcite that deposited between 246.0±6.2 ka and 225.8±5.4 ka, covering Termination III (T-III), MIS 7e and MIS 7d. Proxy records were obtained from conventional and clumped isotopes, with an additional insight from uranium isotopes and petrography. The stable isotope data has relatively high resolution (60-310 yr) allowing identification of millennial-, and at sections centennial-scale climate variations.

The speleothem record reflects an increased Mediterranean influence, as suggested also by other proxy records from the region, especially during MIS 7e. However, periodically increased continental influences are also identified, especially during T-III and MIS 7d. The calcite δ18O values seem to reflect mainly temperature-controlled precipitation δ18O, with changes between Mediterranean and Atlantic moisture source also noticeable. The δ13C values mainly reflect the alternating influence of continental and Mediterranean climates, expressed by summer moisture availability, partly overprinted by temperatures. Increased winter precipitation during MIS 7e is identified, corresponding to Sapropel 9. The abrupt climate change during T-III is represented in the stable isotope record with an event that corresponds to the S8.1 stadial event, as identified in a speleothem from Ejulve Cave (NW Spain), and the Younger Dryas-III weak monsoon interval, as identified by Chinese speleothem records, considered analogous to either Heinrich 1 or Younger Dryas in Termination I, respectively.

How to cite: Temovski, M., Molnár, K., Vargas, D., Rinyu, L., and Palcsu, L.: MIS 8 to MIS 7 sub-orbital-scale climate variability along the northern Mediterranean borderland recorded in a Macedonian mammillary speleothem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7716, https://doi.org/10.5194/egusphere-egu24-7716, 2024.

EGU24-7735 | ECS | Posters on site | CL1.2.3

A history of storminess and flooding on the west coast of Scotland reconstructed from metamorphic cave-grown speleothems 

Kang Xie, Martin Lee, Cristina Persano, John Faithfull, Hai Cheng, and Tim Lawson

Speleothems are not only valuable archives for reconstructing paleoclimate but can also witness climatic events including storms and floods. Two speleothems have been collected from nearshore caves on the islands of Jura and Islay, on the west coast of Scotland. The Jura cave is ~62 km northeast of the one on Islay, yet intriguingly U/Th dating shows that both speleothems began to grow at ~2,400 yr BP. This simultaneous start in calcite deposition could be related to relative sea-level change. Both speleothems have a fine-scale colour banding, and these layers are of a similar age. The dark brown layers in the Islay speleothem correlate well with storm events identified from the island’s peat bogs (Kylander et al., 2020). The black layers in the Jura speleothem formed due to the presence of manganese oxides and are thought to be indicative of cave flooding (Belli et al., 2017). We therefore suggest that periodic changes to the chemical composition and oxygenation of dripwaters in the Jura and Islay caves reflect near-synchronous Late Holocene storm events and associated flooding on the west coast of Scotland.

 

Belli, R., et al. (2017). Investigating the hydrological significance of stalagmite geochemistry (Mg, Sr) using Sr isotope and particulate element records across the Late Glacial-to-Holocene transition. Geochimica et Cosmochimica Acta, 199, 247–263.

Kylander, M. E., et al. (2020). It’s in your glass: A history of sea level and storminess from the Laphroaig bog, Islay (southwestern Scotland). Boreas, 49(1), 152–167.

How to cite: Xie, K., Lee, M., Persano, C., Faithfull, J., Cheng, H., and Lawson, T.: A history of storminess and flooding on the west coast of Scotland reconstructed from metamorphic cave-grown speleothems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7735, https://doi.org/10.5194/egusphere-egu24-7735, 2024.

EGU24-8463 | ECS | Orals | CL1.2.3 | Highlight

A new insight of the MIS 3 Dansgaard-Oeschger climate oscillations in western Europe from the study of a Belgium isotopically equilibrated speleothem 

marion Peral, marta Marchegiano, sophie Verheyden, steven Goderis, tom Van Helden, frank Vanhaecke, thibaut Van Acker, xue Jia, hai Cheng, jens Fiebig, tiffanie Fourcade, christophe Snoeck, and philippe Claeys

The Marine Isotope Stage (MIS) 3 records abrupt transitions from cold stadial to temperate interstadial climate conditions, termed Dansgaard-Oeschger (DO) events. Reconstructing these rapid climate changes is crucial for documenting the prevailing climatic conditions in Europe. However, only few continental records are available to define the continental climatic responses to DO changes. Here, the elemental and stable isotope compositions of a flowstone speleothem in Belgium covering the MIS 3 are documented. This speleothem precipitated under equilibrium conditions based on Δ48 thermometry, allowing the use of Δ47 thermometry with confidence. The acquired unique thermometry paleoclimatic dataset enables the reconstruction of temperature based on the hydrological information (oxygen-18 of drip water; δ18Ow) and sheds new light on the DO climate variations. A temperature differential of ~7°C is associated with alternating temperate warm and wet Interstadials to cold and dry stadials. The DO-12 is the most pronounced MIS 3 interstadial in the record and appears to be marked by a delay of 1000 years between climate enhancement (warmer temperature) and water availability (moisture increase). By combining our speleothem record with other continental and marine archive, the spatial variability of DO changes in western Europe during the MIS 3 is defined. A gradual climate deterioration with colder and drier conditions, associated with the Heinrich 4 event, progressed southwards through Europe. Interestngly, this spatial climatic degradation occured during the last phase of Neanderthal populations occupation in Europe. Our data provides better understanding on proxy interpretation thanks to our clumped isotope measurement but also on environmental constraints for human mobility models.

How to cite: Peral, M., Marchegiano, M., Verheyden, S., Goderis, S., Van Helden, T., Vanhaecke, F., Van Acker, T., Jia, X., Cheng, H., Fiebig, J., Fourcade, T., Snoeck, C., and Claeys, P.: A new insight of the MIS 3 Dansgaard-Oeschger climate oscillations in western Europe from the study of a Belgium isotopically equilibrated speleothem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8463, https://doi.org/10.5194/egusphere-egu24-8463, 2024.

EGU24-8504 | ECS | Posters on site | CL1.2.3

A Bayesian framework to model speleothem oxygen isotope data with age uncertainties 

Josefine Axelsson, Andreas Nilsson, Neil Suttie, and Jesper Sjolte

Age-depth models are widely used to build chronologies from proxy records and are most often implemented for speleothems due to age uncertainties and lower resolutions. In this study, we use a variation of the accumulation rate method to perform a pseudo-proxy reconstruction of large-scale variability in monsoon precipitation using synthetic oxygen isotope records from speleothem sites and the isotope-enabled ECHAM/MPI-OM climate model. We present a probabilistic approach to synchronize speleothems by informative priors of oxygen isotope data and individual independent age constraints. This is achieved by co-estimating the regional δ18O variations through time, where δ18O variability is modeled using Gaussian processes and a Bayesian model is further used for the individual speleothem chronologies. The method is tested using synthetic speleothem data generated from the last millennium-long climate model simulation and corrupted through realistic noise from speleothems in the Indian Ocean region from the SISALv2 database. Through the creation of a millennium-long reconstruction, we aim to study the atmospheric dynamics from the reconstruction over the Asian region to help us further constrain the drivers, responses to, and changes in the variability of the monsoon. By synchronizing the time series of oxygen-isotope data through the incorporation of accurate and realistic depth-dependent age uncertainties, this modeling approach may lead to advancements in handling speleothem data and climate model simulations for regional to global evaluations of variability and past climate reconstructions.

How to cite: Axelsson, J., Nilsson, A., Suttie, N., and Sjolte, J.: A Bayesian framework to model speleothem oxygen isotope data with age uncertainties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8504, https://doi.org/10.5194/egusphere-egu24-8504, 2024.

EGU24-8998 | Posters on site | CL1.2.3

Unraveling anthropogenic impact on Mawmluh Cave Speleothems: Insights from high-resolution analysis of aragonite formations 

Dildi Dildi, Michael Weber, Hubert B. Vonhof, and Denis Scholz

Geochemical anomalies within speleothems serve as crucial indicators of environmental changes. While research predominantly focuses on calcite-dominated formations, understanding the significance of aragonite is essential for a comprehensive grasp of past climate dynamics. This study presents high-resolution records, based on 230Th/U dating, stable isotopes (δ13C) and trace elements analysis in recent aragonite growth lamina near the calcite top in three speleothems from Mawmluh Cave, Meghalaya, India. Covering a total of 163 years (2022 to 1859 CE), the research explores the environmental impact on the cave system, especially in relation to nearby industrial activities. Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was utilized to analyze trace elements (e.g., Mg, Sr, Ba, U, P, Y, Pb, Al, Th, etc.) in the recent aragonite growth lamina. Detected trace elements (Pb, Zn, Mn, etc.) at trace concentrations, alongside current δ13C values, may be linked to emissions from a nearby cement plant and open-cast mining activities, acting as potential indicators of anthropogenic influence. All three speleothems displayed transitions from calcite to aragonite near the top, suggesting a significant alteration in the cave system over time, potentially induced by human activities. Anthropogenic factors may contribute to this transition, with specific elements acting as key markers. Future studies on the geochemical signatures of aragonite formations promise to fill existing gaps, offering a nuanced perspective on paleoclimatic and paleoenvironmental conditions.

Keywords: speleothems, aragonite formations, trace elements, stable isotopes, anthropogenic impact, Mawmluh Cave.

How to cite: Dildi, D., Weber, M., Vonhof, H. B., and Scholz, D.: Unraveling anthropogenic impact on Mawmluh Cave Speleothems: Insights from high-resolution analysis of aragonite formations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8998, https://doi.org/10.5194/egusphere-egu24-8998, 2024.

EGU24-10458 | ECS | Posters on site | CL1.2.3

South Atlantic Convergence Zone impacts on climate and vegetation changes over the last 16,000 years in Central Brazil based on a speleothem multi-proxy record 

Marcela Eduarda Della Libera, Denis Scholz, Hubert Vonhof, Cintia Stumpf, Michael Weber, Julio Cauhy, Francisco William Cruz, Nicolás Stríkis, and Valdir Felipe Novello

The South American Monsoon System (SAMS) plays an important role in the hydroclimate variability and rainfall patterns across South America. Stemming from its convective core in the southwestern Amazon basin, the South Atlantic Convergence Zone (SACZ) is a southeastward convection band, being a critical component of SAMS responsible for large-scale moisture transport, particularly over Central Brazil. Previous paleoclimate studies suggest that SACZ has changed over time, usually associated with changes in the SAMS, and there are current debates regarding the nature of SACZ, shifts in position, size, and intensity, and their potential impacts on vegetation changes. Therefore, this study addresses these debates for the last 16,000 years based on a novel multi-proxy paleorecord of δ18O, δ13C, and Sr isotope ratios (87Sr/86Sr) from a stalagmite collected in São Mateus Cave at the northeast limits of SACZ in central Brazil. This site is therefore under the regime of SACZ, with a climate characterized as tropical semi-humid with a rainy summer season and a dry winter.

The inclusion of Sr isotope data enhances our interpretation of past local climate variability since changes in 87Sr/86Sr can provide valuable information about the water residence in the epikarst and changes in soil composition. Furthermore, as São Mateus Cave lies within the Cerrado biome, it offers a unique insight into the past climate and environmental changes in central Brazil due to its distinct floral compositions influenced by factors such as location, soil, rainfall distribution, and fire frequency. Comparisons with other paleoclimate data from SACZ-influenced sites are made to access climate and vegetation changes in different locations within this convective band, particularly over larger time scales, such as the transition from the Late-Pleistocene to the Holocene and longer trends. We demonstrate that even though there is a common change in the regional δ18O signal connected with SACZ variations, differences in vegetation and local moisture between northern and southern SACZ limits are evident albeit being in the same biome. This multi-proxy approach, combining traditional stalagmite proxies with high-resolution LA-MC-ICP-MS Sr isotope analysis, offers a better understanding of SACZ changes and their implications for Central Brazil's climate and environment. 

How to cite: Della Libera, M. E., Scholz, D., Vonhof, H., Stumpf, C., Weber, M., Cauhy, J., Cruz, F. W., Stríkis, N., and Novello, V. F.: South Atlantic Convergence Zone impacts on climate and vegetation changes over the last 16,000 years in Central Brazil based on a speleothem multi-proxy record, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10458, https://doi.org/10.5194/egusphere-egu24-10458, 2024.

EGU24-10607 | ECS | Posters on site | CL1.2.3 | Highlight

Variations in regional hydrological environment and human activities inferred from δ18O and δ2H of stalagmite fluid inclusions in southwest China 

Yao Wu, Sophie Warken, Jun-Yun Li, Ting-Yong Li, and Norbert Frank

The interpretation of δ18Oc and δ13Cc values of stalagmites within China is still complex, although numerous cave archives have been reported in this region. Present challenges include distinguishing between natural and anthropogenic influences on regional hydrological and environmental changes, in particular due to the increasing human activities during the mid-to late Holocene. Here, we report for the first time the δ18Ofi and δ2Hfi records of fluids entombed as inclusions during the Holocene (6290 to 690 yr BP) from a stalagmite from southwest China. We excluded measurement-induced artefacts using Rayleigh fractionation models and improved measurement methods, producing reliable results. We observed very high δ18Ofi and δ2Hfi values during a weak Asian summer monsoon (ASM). Our record reveals six drought events during the mid- and late-Holocene (~950, 1360, 2260, 3450, and 5600 yr BP), which coincide with the weakening of ASM intensity and variations in low latitude forcing, such as tropical sea surface temperature, El Niño/Southern Oscillation, and intertropical convergence zone. In 950-1100 A.D., the dramatic enrichment of δ18Ofi (magnitude ~7‰) corresponds with the increase in regional population density due to large-scale population migration at this time (historically known as the Jingkang event). The overall coefficient of variation (C.V = standard deviation/mean) of the δ18Ofi sequence is 125% compared to only 5% for δ18Oc. Hence, δ18Ofi seems to exhibit a greater sensitivity to regional environment wet/dry variations than traditional carbonate isotope proxies.

How to cite: Wu, Y., Warken, S., Li, J.-Y., Li, T.-Y., and Frank, N.: Variations in regional hydrological environment and human activities inferred from δ18O and δ2H of stalagmite fluid inclusions in southwest China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10607, https://doi.org/10.5194/egusphere-egu24-10607, 2024.

EGU24-11131 | ECS | Posters on site | CL1.2.3 | Highlight

Stalagmite-based cave flood records as a proxy for reconstruction of extreme rainfall frequency over the Holocene from two different cave sites in South-eastern Brazil 

Julio Cauhy, Denis Scholz, Hubert Vonhof, Nicolás Stríkis, Marcela Edaurda Della Libera, Valdir Felipe Novello, and Francisco William Cruz

Extreme rainfall events are expected to become more frequent and intense worldwide due to climate change, as indicated by the Sixth Assessment Report from the Intergovernmental Panel on Climate Change. This includes the most populated region in South America, southern and southeastern Brazil, where several studies document a consistent pattern of intense rainfall increases. The increasing intensity and frequency of these events have a direct impact on society, triggering natural disasters such as flash floods and landslides, accounting for 74% of natural disaster-related deaths and an impact of 6.2 billion dollars between 2010 and 2019.

The scarcity of available data and limitations to the instrumental period hamper assessments regarding the frequency and intensity of extreme rainfall events beyond this period. This limitation precludes the assessment of how larger-scale forcings, atmospheric circulation, and environmental changes can affect the frequency and magnitude of those events. Previous studies show that extreme rainfall events in the study area are caused by Extratropical Cyclones and Frontal Systems, as well as the South Atlantic Convergence Zone. Our 5-year cave flood monitoring indicates that extreme rainfall events are responsible for triggering the cave floods, therefore stalagmites subjected to those cave floodings can be used as a proxy for extreme rainfall events. In this context, we use a large set of Holocene stalagmites collected from two different caves (Lage Branca and Malfazido cave). Reconstructions are based on detrital layers within stalagmites identified using thin-section petrography.

Records from Malfazido cave exhibit a higher sensitivity to high-frequency cave flood events (subdecadal to decadal frequency), as demonstrated by reconstructions. In contrast, Lage Branca records are sensitive to high-magnitude events (multidecadal, centennial, or multi-centennial frequency) due to their high topographic position (20-50 m above the underground river) and slow growth rate. We present new cave flood records for Malfazido and Lage Branca caves, covering the last 7000 years and 10000 years, respectively. Periods of increased occurrence of flood layers in the stalagmites are observed for both caves around 4.1 kyr during the transition from the Middle to Late Holocene. For higher-frequency events, a remarkable increase in cave flood frequency is observed during the Little Ice Age. To assess the mean climate state in which the changes in frequency are observed, a high-resolution multiproxy record based on stalagmites (δ13C, δ18O, trace elements) is used to reconstruct paleohydrology and environmental conditions.

New paleoflood cave records from both caves are used to assess how the frequency of extreme rainfall events can vary over time, providing insights into how different forcings and climate changes, such as atmospheric circulation changes and variations in SSTs, can affect the frequency of those events.

How to cite: Cauhy, J., Scholz, D., Vonhof, H., Stríkis, N., Della Libera, M. E., Novello, V. F., and Cruz, F. W.: Stalagmite-based cave flood records as a proxy for reconstruction of extreme rainfall frequency over the Holocene from two different cave sites in South-eastern Brazil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11131, https://doi.org/10.5194/egusphere-egu24-11131, 2024.

EGU24-11252 | ECS | Posters on site | CL1.2.3 | Highlight

Examining the weakening of the AMOC using a Bermudan Stalagmite  

Edward Forman, James Baldini, Robert Jamieson, Franziska Lechleitner, Lisa Baldini, Sebastian Breitenbach, and Colin Macpherson

While the Atlantic Meridional Overturning Circulation (AMOC) is understood to be weakening as a consequence of anthropogenic climate change, the precise onset of this decline remains subject of debate. There are two principal hypotheses surrounding the initiation of the slowdown: (a) it began in the mid-twentieth century in response to escalating atmospheric carbon dioxide concentrations, and (b) the trend started in the mid-nineteenth century, resulting from the increased freshwater fluxes associated with the end of the Little Ice Age (LIA). Here, we present a monthly resolved record of magnesium concentration extending back to 1456 derived from a Bermudan stalagmite. We use this proxy record to reconstruct sea surface temperature (SST) by calibrating the data to a previously published SST record, and with it derive an AMOC fingerprint spanning more than 550 years. From this we aim to decipher an estimate for the initiation of the observed AMOC decline within the context of its subsequent manifestations. 

How to cite: Forman, E., Baldini, J., Jamieson, R., Lechleitner, F., Baldini, L., Breitenbach, S., and Macpherson, C.: Examining the weakening of the AMOC using a Bermudan Stalagmite , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11252, https://doi.org/10.5194/egusphere-egu24-11252, 2024.

EGU24-11806 | ECS | Orals | CL1.2.3 | Highlight

What drives vegetation changes in South Sulawesi during the MIS 5e transition? 

Alena Kimbrough, Michael Gagan, Gavin Dunbar, Pauline Treble, Wahyoe Hantoro, Jian-xin Zhao, R. Lawrence Edwards, Chuan-Chou Shen, Bambang Suwargadi, Henri Wong, and Hamdi Rifai

Sulawesi speleothem carbon isotopes (δ13C) are found to co-vary with deglacial warming and atmospheric CO2 measured from Antarctic ice cores. This co-variation has thus far been attributed to speleothem δ13C recording changes in vegetation productivity and microbial activity in the soils overlaying caves as vegetation and microbes respond to glacial-interglacial changes in temperature and atmospheric CO2 (Kimbrough et al., 2023; Krause & Kimbrough et al., in press). However, the relationship between speleothem δ13C and regional environmental change is complex and deconvolving the effect of different environmental drivers is difficult. To further investigate the ecosystem response in the Indo-Pacific Warm Pool to substantial warming and CO2 rise during the penultimate deglaciation/marine isotope stage 5e (~127 kyrs ago) we use complimentary geochemical proxies extracted from stalagmite CaCO3. These proxies include phosphorus and sulphur which respond to nutrient uptake by forest biomass above the cave (Treble et al., 2016). The relative abundance of metals such as copper, iron, zinc, and lead are assessed as another means to track biomass/soil regeneration via selective element delivery to the stalagmites by organic colloids flushed from the soil zone (Borsato et al., 2007). These vegetation proxies are compared with the speleothem δ13C and δ18O records and corresponding high-resolution fluorescence mapping of organics via confocal laser scanning (fluorescence) microscopy (Sliwinski & Stoll, 2021). The comparison of transition metals to stable isotopes (δ18O, δ13C) in the Sulawesi speleothem records makes it possible to distinguish between periods in the record where vegetation productivity increased in response to a rise in temperature and CO2 verses periods where changing hydroclimate played a more dominant role. Characterising the appropriate drivers and proxy response is critical to accurately interpret tropical paleoclimate records where interpretations rely on assumptions that rainfall is the primary driver of vegetation change.

 

Kimbrough, A.K., Gagan, M.K., Dunbar, G.B., Hantoro, W.S., Shen, C., Hu, H., Cheng, H., Edwards, R.L., Rifai, H., Suwargadi, B.W., 2023. Multi-proxy validation of glacial-interglacial rainfall variations in southwest Sulawesi. Communications Earth & Environment, 4(210), 1–13.

Krause*, C.E., Kimbroug*, A.K., Gagan, M.K., Hopcroft, P.O., Dunbar, G.B., Hantoro, W.S., Hellstrom, J.C., Cheng, H., Edwards, R.L., Wong, H., Suwargadi, B.W., Valdes, P.J., Rifai, H., in press. Tropical vegetation productivity and atmospheric methane over the last 40,000 years from model simulations and stalagmites in Sulawesi, Indonesia. Quaternary Research.

Treble, P.C., Fairchild, I.J., Baker, A., Meredith, K.T., Andersen, M.S., Salmon, S.U., Bradley, C., Wynn, P.M., Hankin, S.I., Wood, A., McGuire, E., 2016. Roles of forest bioproductivity, transpiration and fire in a nine-year record of cave dripwater chemistry from southwest Australia. Geochimica et Cosmochimica Acta, 184, 132–150.

Borsato, A., Frisia, S., Fairchild, I.J., Somogyi, A., Susini, J., 2007. Trace element distribution in annual stalagmite laminae mapped by micrometer-resolution X-ray fluorescence: Implications for incorporation of environmentally significant species. Geochimica et Cosmochimica Acta, 71(6), 1494–1512.

Sliwinski, J.T., Stoll, H.M., 2021. Combined fluorescence imaging and LA-ICP-MS trace element mapping of stalagmites: Microfabric identification and interpretation. Chemical Geology, 581, 120397.

How to cite: Kimbrough, A., Gagan, M., Dunbar, G., Treble, P., Hantoro, W., Zhao, J., Edwards, R. L., Shen, C.-C., Suwargadi, B., Wong, H., and Rifai, H.: What drives vegetation changes in South Sulawesi during the MIS 5e transition?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11806, https://doi.org/10.5194/egusphere-egu24-11806, 2024.

EGU24-12159 | ECS | Orals | CL1.2.3

An Electron Backscattered Diffraction (EBSD) study on the relationships between calcite fabric and fluid inclusions in cave stalagmites 

Leonardo Pasqualetto, Yves Krüger, Luca Menegon, Matteo Demurtas, Silvia Frisia, Andrea Borsato, and Anna Nele Meckler

Cave stalagmites serve as archives providing valuable information about climatic and environmental changes in the past. Their chemical proxy data have been found to bear relationship with their calcium carbonate crystal fabrics, as the crystallization pathways influence both chemical and physical properties in differing extents. For instance, crystallization pathways can affect the spatial distribution of chemical species and/or micro- and nano-particulate, resulting in inhomogeneities in the concentration of trace and major elements along the same growth layer, with consequences on interpretation drawn from line scans. Pathways of crystallization not only control the overall stalagmite fabrics, but also the occurrence of crystal growth defects and nano-porosity that might become nucleation sites for the formation of larger, water-filled fluid inclusions. The latter have recently acquired a growing scientific interest as they can be used as proxies for paleotemperature reconstruction by means of nucleation-assisted microthermometry, oxygen isotope thermometry, or noble gas thermometry (e.g., Meckler et al., 2015).

Here, we used Electron Backscattered Diffraction (EBSD) on stalagmites consisting of calcite from Borneo and New Zealand aimed to study the relationships between fabric and fluid inclusions by investigating crystallographic orientations, grain boundaries and growth features. The goal is to gain insight on the processes of formation of the fluid inclusions in stalagmites and if/how they can be affected by deformation or physical change over time.

The analysed samples consist of alternating compact and open columnar fabric, characterized by mm to cm-sized domains where the calcite crystal axis (i.e., the elongation axis) is almost perfectly iso-oriented. These domains show a further subdivision in smaller “sub-domains” with widths of tens to few hundreds of micrometres created by a rotation in the direction of the c axis in the order of 1-4°. Our preliminary results showed that most of the fluid inclusions are located at the boundaries between these “sub-domains”. An inverse correlation between the width of the "sub-domains" and the number of fluid inclusions was also observed. This suggests that fluid inclusions are significantly linked to the presence of intracrystalline defects. The latter are potential sources of internal stress in the calcite lattice and relaxation of these internal stress fields could potentially result in post-formation volume changes of fluid inclusions. The scatter and distribution of formation temperatures derived from microthermometric analyses of coeval fluid inclusions within a single stalagmite growth band could, at least partly, be explained by such non-thermal processes.

 

Meckler, A. Nele, et al., Glacial–interglacial temperature change in the tropical West Pacific: A comparison of stalagmite-based paleo-thermometers, Quaternary Science Reviews 127 (2015): 90-116. https://doi.org/10.1016/j.quascirev.2015.06.015

How to cite: Pasqualetto, L., Krüger, Y., Menegon, L., Demurtas, M., Frisia, S., Borsato, A., and Meckler, A. N.: An Electron Backscattered Diffraction (EBSD) study on the relationships between calcite fabric and fluid inclusions in cave stalagmites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12159, https://doi.org/10.5194/egusphere-egu24-12159, 2024.

EGU24-12206 | Orals | CL1.2.3

Trace elements in coastal Southa African speleothems as proxies for sea level change and distance to the coast  

Kerstin Braun, Yuval Burstyn, Nathaniel Miller, Lawrence Edwards, and Xianglei Li

The South African south coast is noteworthy for its rich record of archaeological sites. Cave deposits from the region record the first known evidence of hunter-gatherers using marine food resources ~165 ka ago. Between ~110 and 65ka the archaeological record also preserves worn seashells, complex stone and bone tools, shell beads and decorated ochre and ostrich eggshell. Such complex tools and decorated objects may be early examples of items that required the accumulation and dissemination of knowledge over several generations and culture. But our understanding of the environmental and climatic background of the evolution of such milestones in human history is still limited.

Here we present Mg/Ca, Sr/Ca, Ba/Ca and U/Ca records of speleothems from Pinnacle Point on the South African south coast. The records were measured by laser-ablation ICP-MS and cover the time interval between 88 and 58 ka. We compared our new records to a range of global and regional proxies using gaussian-kernel based cross correlation analyses. To understand larger scale patterns of correlation we included several proxies of global and regional temperature change as well as proxies of weathering and river runoff/rainfall amount, coastal upwelling, and orbital parameters/insolation. Our Mg/Ca and Ba/Ca records show a steep decrease at the transition from interglacial MIS 5 into glacial MIS 4 and a general positive relation with global and regional temperature proxies and sea level. We therefore interpret them in terms of changing contributions of sea spray to the caves trace element budget. Such changes are especially pronounced in this area due to the wide and gently sloping continental shelf. Sea level variations during the deposition of our speleothem samples meant that the coast was between ~500m and 30 km distant from the caves.

The Sr/Ca and U/Ca records of Pinnacle Point speleothems show only a short decrease near the MIS 5-4 transition followed by higher values in MIS 4. This also leads to negative correlation with most global and regional temperature proxies whereas correlation with proxies of rainfall/weathering and river runoff is varied. We therefore interpret the Sr/Ca and U/Ca records in terms of in-cave processes related to water availability, such as Prior carbonate precipitation and CO2 degassing and redox in the overlying soils, respectively. Higher values of Sr/Ca and U/Ca therefore would be associated with drier conditions and oxidizing conditions in the soil. Following this interpretation, the Sr/Ca and U/Ca records indicate drier conditions at Pinnacle Point in MIS 5 b and early a, wetter conditions at the MIS 5-4 transition and a shift towards drier conditions within MIS 4.

The changing distance to the coast means that hunter-gatherers in the region had variable access to its rich marine resources over time. Variable climate and soil oxidation would also indicate changing water availability and vegetation composition. The consistent use of archaeological sites at Pinnacle Point by hunter-gatherers, however, means that people were able to adapt to these changes.

How to cite: Braun, K., Burstyn, Y., Miller, N., Edwards, L., and Li, X.: Trace elements in coastal Southa African speleothems as proxies for sea level change and distance to the coast , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12206, https://doi.org/10.5194/egusphere-egu24-12206, 2024.

EGU24-13062 | ECS | Posters on site | CL1.2.3

Where do tropical land temperatures sit on the bipolar see-saw?  

Camille Afonso, Marit Løland, Stacy Carolin, Yves Krüger, and Nele Meckler

Low latitudes play a key role in the Earth's climate system, receiving the highest amount of solar energy that is redistributed across the globe through atmospheric and oceanic circulation. The last glacial cycle has been characterized by millennial-scale climate oscillations, marked by large and rapid temperature swings in the North Atlantic region accompanied with opposite and smaller temperature variations in the Southern Hemisphere. In the context of these millennial scale climate fluctuations, we seek to understand the tropical climate behaviour, determining whether it followed the Northern Hemisphere pattern or the Southern Hemisphere pattern and atmospheric CO2.

In this study, nucleation-assisted microthermometry (Krüger et al., 2011) was used to determine stalagmite formation temperatures based on fluid inclusion liquid-vapor homogenization. The method was applied to SC03, a stalagmite from Secret Cave (Gunung Mulu National Park, Northern Borneo), previously studied for changes in precipitation (Carolin et al., 2013). Here we reconstructed a quantitative land temperature record, covering selected Dansgaard-Oeschger cycles during MIS 3 (42-50 ka) as well as during MIS 5a and MIS 4 (60-81 ka). Our preliminary findings suggest that tropical temperature did not follow Northern Hemispheric patterns but there appears to be a relationship with atmospheric CO2 levels. This aligns with previous findings from the last glacial termination derived from another stalagmite from the same cave (Løland et al., 2022). Additionally, we investigated whether there is any evidence of a significant land temperature change in the period immediately following the Toba super eruption (Sumatra, Indonesia),  ca. 73.8 ka. Our study contributes to a broader understanding of the interplay between low and high latitude climate during millennial-scale reorganizations of the global climate system.

How to cite: Afonso, C., Løland, M., Carolin, S., Krüger, Y., and Meckler, N.: Where do tropical land temperatures sit on the bipolar see-saw? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13062, https://doi.org/10.5194/egusphere-egu24-13062, 2024.

EGU24-13102 | ECS | Posters on site | CL1.2.3

Deglacial temperature estimates from dual clumped-isotope measurements and fluid inclusion noble gas concentrations in a stalagmite from McLean’s Cave, western Sierra Nevada 

Cameron de Wet, Barbara Wortham, Daniel Stolper, Sujoy Mukhopadhyay, and Isabel Montañez

Clumped-isotope (Δ47) measurements from speleothem calcite have the potential to record formation temperatures with an uncertainty of ± 2°C but are strongly impacted by kinetic effects during mineral precipitation that lead to isotopic disequilibrium and erroneously high-temperature estimates. The application of dual clumped-isotope (Δ4748) measurements can identify the influence of kinetic effects and has the potential to provide temperature estimates that are corrected for the degree of isotopic disequilibrium, though this involves a decrease in precision (± 4.5°C). The concentration of noble gases in water that is trapped in fluid inclusions in speleothems is another independent estimate of paleo-temperatures that is based on the temperature dependence of noble gas solubility in freshwater systems.

 

We combine these two newly emerging techniques by applying dual-clumped isotope (n = 15) and fluid inclusion noble gas measurements (n = 3) to a speleothem from McLeans Cave, located in the western foothills of the Sierra Nevada, that grew during the last deglaciation (~11 to 19 ka). We obtain temperature estimates using the noble gas measurements as well as using the Δ47 measurements for samples that do not exhibit isotopic disequilibrium in dual clumped-isotope space and compare these estimates with other western US temperature records from proxy records and climate model simulations. Many of the dual clumped-isotope samples, however do exhibit isotopic disequilibrium. We assess the degree to which disequilibrium can be corrected for using dual clumped-isotopes and test the sensitivity of these isotopic relationships to different published corrections to assess the implications for estimates of paleo-temperatures. Additionally, we compare the new dual-clumped isotope data with coeval d18O and d13C measurements, as well we previously collected measurements of d18O and d2H from fluid inclusions in the sample to investigate what processes may be driving the isotopic variability in both speleothem calcite and fluid inclusion water in this sample.

How to cite: de Wet, C., Wortham, B., Stolper, D., Mukhopadhyay, S., and Montañez, I.: Deglacial temperature estimates from dual clumped-isotope measurements and fluid inclusion noble gas concentrations in a stalagmite from McLean’s Cave, western Sierra Nevada, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13102, https://doi.org/10.5194/egusphere-egu24-13102, 2024.

EGU24-13477 | ECS | Orals | CL1.2.3

Tropical Land Temperature Change across Termination II and the Last Interglacial 

Hao Ding, Yves Krüger, Stacy Carolin, and Anna Nele Meckler

The general sequence of a late Pleistocene glacial termination has been well portrayed, where the high latitude regions of the Northern and Southern Hemisphere play essential but significantly different roles. The role of low latitude regions, however, is less well constrained. This is particularly true for time intervals prior to the last glacial period, and for glacial inceptions where our current understanding hinges on marine proxy records that are prone to uncertainties regarding the season and water depth the signals represent, as well as non-thermal influences. Additional, precisely dated and accurate temperature records from the tropics are therefore essential to constrain the amplitude and timing of tropical temperature change in comparison with the high latitudes.

Here we provide a new record for tropical land temperature from Northern Borneo across Termination II, the Last Interglacial, and the glacial inception between marine isotope stages (MIS) 5e and 5d, spanning approximately from 145 to 107 ka. The temperatures are based on nucleation-assisted fluid inclusion microthermometry (Krüger et al., 2011), currently considered the most precise paleothermometer for stalagmites. This approach has the advantage that it does not rely on empirical calibration and that the resulting temperatures are not seasonally biased.

Our record shows that the temperature, which was corrected for sea-level induced cave altitude changes, increased from 19.6 ± 0.4 °C (2SEM) to 24.0 ± 0.3 °C (2SEM) over Termination II. Similar to what has previously been found for Termination I (Løland et al., 2022), temperature over Termination II follows the timing of increasing atmospheric CO2 concentration and Southern Hemisphere warming. However, our record decouples from CO2 during glacial inception into MIS 5d, where the sea-level corrected temperature started to decrease to 21.0 ± 0.3 °C (2SEM) at around 122 ka whereas CO2 remained stable for another 7 kyr. The amplitude and timing of this cooling is confirmed with a second stalagmite from another nearby cave. Our observation shows that early cooling into MIS 5d is not limited to the high southern latitudes (Jouzel et al., 2007) but instead appears to be a more global phenomenon that will be important to understand in order to shed light on the sequence of events leading to glacial inception.

References

Jouzel, Jean, et al. "Orbital and millennial Antarctic climate variability over the past 800,000 years." Science 317.5839 (2007): 793-796.

Krüger, Yves, et al. "Liquid–vapour homogenisation of fluid inclusions in stalagmites: Evaluation of a new thermometer for palaeoclimate research." Chemical geology 289.1-2 (2011): 39-47.

Løland, Marit Holten, et al. "Evolution of tropical land temperature across the last glacial termination." Nature Communications 13.1 (2022): 5158.

How to cite: Ding, H., Krüger, Y., Carolin, S., and Meckler, A. N.: Tropical Land Temperature Change across Termination II and the Last Interglacial, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13477, https://doi.org/10.5194/egusphere-egu24-13477, 2024.

EGU24-14277 | ECS | Orals | CL1.2.3

Hydroclimate Response to the 8.2ka Event Across California: Insights from A Southern Sierra Nevada Stalagmite 

Yuval Burstyn, Bangran Tang, Jocelyn Cziko, Mikayla Deigan, Cameron de Wet, Eliot Atekwana, Kesego Letshele, and Isabel Montañez

Climate simulations project an increasing “whiplash climate” or rapid oscillations of wet and dry extremes, for 21st century California, prompting the need for research into the Holocene climate volatility periods. Paleoclimate records from California (CA) suggest that the 8.2 ka event is experienced as a whiplash climate. A coastal stalagmite record from central CA indicates variable infiltration and overall wetter conditions above the cave. Fire biomarkers from the stalagmite support a link between whiplash climate and fire activity in Western North America, a similar relationship is also observed in tree rings and lake deposits. However, the spatial heterogeneity characterizing Mediterranean climates and the observed shifts of the north-to-south climate dipole in response to global climate change presents a challenge in forming a cohesive regional image of paleoclimate CA.

Crystal 67 Cave (C67) is situated in the Southern Sierra Nevada at an elevation of ~2000 meters amsl. Our study includes a geochemical monitoring campaign from soil to deposition site and a high resolution (30y to 5y) stalagmite proxy record covering the early to mid-Holocene. In 2020, a significant fire complex rampaged through the forest above the cave, followed by an exceptionally rainy winter season in 2022-2023, making C67 a prime candidate for studying the response of both extreme “whiplash” climate years (this study) and post-fire signal transport through the karst system (Hren et al., EGU 2024).

The 2022-2024 monitoring of C67 shows that drip rate data is inversely correlated with the cave CO2, suggesting seasonal ventilation and potential winter and spring bias in speleothem growth. Drip rate is also well synchronized with the high precipitation events and snowpack in the winter and early spring indicating high hydrologic connectivity between the cave and the surface. Drip water δ18O and δD values fall along the Local Meteoric Water Line in three distinct clusters: spring water, associated with summer drip water, and water sourced from sub-tropic and north-pacific storm tracks, associated with winter and early spring drip water, respectively. Trace Elements (TEs) highlight a rapid infiltration end-member dominant in winter and spring, and a second seepage end-member feeding the cave drips throughout the dry season.

The stalagmite geochemical data supports alternating wet and dry conditions during the 8.2 ka event. However, while the δ18O profile of C67 mimics that of the coastal cave, its δ13C values suggest that C67 experiences a shift from mean to drought conditions, supported by coinciding high TE/Ca. Additionally, P/Ca ratios increase during and after 8.2 ka, indicating increased colloidal influx into the cave, previously associated with enhanced fire activity.

Our results show that the C67 cave and stalagmites present a unique opportunity for a high-resolution investigation of the position of the CA climate dipole and whiplash seasonality.

How to cite: Burstyn, Y., Tang, B., Cziko, J., Deigan, M., de Wet, C., Atekwana, E., Letshele, K., and Montañez, I.: Hydroclimate Response to the 8.2ka Event Across California: Insights from A Southern Sierra Nevada Stalagmite, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14277, https://doi.org/10.5194/egusphere-egu24-14277, 2024.

EGU24-14529 | ECS | Posters on site | CL1.2.3

Multiproxy diagnostic criteria to identify subglacial speleothem growth: test cases from the European Alps and Western Caucasus 

Jonathan Baker, Alexander Honiat, Vanessa Skiba, and Christoph Spötl

            Conventional models of speleothem growth require percolation through a biologically active soil layer, uptake of soil-respired CO2, and resulting carbonic-acid dissolution of the host rock. Within this model, speleothem growth is inhibited when the mean temperature of the soil-karst-cave system falls below the freezing point of water. Hence, speleothem growth hiatuses have been interpreted at high-latitude sites to indicate permafrost conditions or glacial cover. Paradoxically, however, speleothem growth during presumably ice-covered intervals has been documented in studies of Alpine and North American caves. To explain how growth could proceed despite subzero mean annual air temperature and the absence of soil, previous work has proposed a mechanism that invokes: 1) the oxidation of sedimentary sulfides to promote sulfuric-acid dissolution of host rock; and 2) buffering of ground temperatures by a warm-based glacier above the cave site that maintains the epikarst and cave within the 0°C isotherm. In this scenario, infiltrating meteoric water is derived indirectly from basal glacial melt and seasonal moulin drainage, which act as a low-pass filter with respect to transference of the oxygen-isotope composition and associated climate signal.

            Although individual components of the proposed mechanism have been observed in modern analog settings, there has been no comprehensive attempt to elucidate or constrain these processes through geochemical proxy data. Here we present preliminary data from speleothems in the Western Alps (Austria, Switzerland, France) and Western Caucasus (Abkhazia) that grew subglacially or in close proximity to the ice margin, according to U-Th dating and glacier reconstructions. Based on these results, we attempt to define multiproxy diagnostic criteria to identify intervals of subglacial conditions. First, we investigate how a switch to predominantly sulfuric-acid dissolution impacts the carbon-isotope and trace-element composition of calcite. We find that enhanced host rock contributions to the dissolved inorganic carbon pool substantially raise δ13C and dead-carbon fraction, as well as increase the variance in prior calcite precipitation, as interpreted from trace-element data. We evaluate these data through proxy system modeling of a subglacial setting; however, information from these proxies is limited as they are impacted by a multitude of processes. Therefore, we test whether speleothem S/Ca and δ34S are more direct proxies for sulfide oxidation. Finally, we consider paleothermometric methods to test whether cave temperatures are near zero, as the proposed mechanism requires. If successful, the identification of subglacial speleothem archives may substantially improve glacial reconstructions by providing vital constraints on ice-sheet properties for paleomodeling, in addition to yielding proxy reconstructions of surface climate during glacial intervals, when most terrestrial archives are inactive.

How to cite: Baker, J., Honiat, A., Skiba, V., and Spötl, C.: Multiproxy diagnostic criteria to identify subglacial speleothem growth: test cases from the European Alps and Western Caucasus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14529, https://doi.org/10.5194/egusphere-egu24-14529, 2024.

EGU24-14861 | ECS | Posters on site | CL1.2.3 | Highlight

The first multi-proxy speleothem paleoclimate record from Georgia and calculations of temperature variations during the last ~ 13500 years  

Lasha Asanidze, Andrea Columbu, Dominik Fleitmann, Stephen Burns, Zaza Lezhava, Kukuri Tsikarishvili, Giovanni Zanchetta, Stefano Natali, and David McGee

The study of glacial to interglacial climate transitions is extremely important for understanding the full scale of climate variability from global to local scale. Unfortunately, there are large areas where multimillennial paleoclimate timeseries are unavailable. Southern Caucasus, is such a region as currently only a few continental climate time series extend beyond the short instrumental records. Importantly, temperature-related proxies are virtually absent here, thus impeding to evaluate how global-scale rapid climate instabilities propagate and impact this area. This work provides the first paleoclimate reconstruction from Georgia (Southern Caucasus) spanning approximately the last 13500 years. Four stalagmites named Zak-1, Zak-3, Zak-4 and Zak-6, measuring 46, 50, 55 and 102 cm respectively, were collected from the Zakariasklde Cave (42°10′ N; 43°20′ E). Dated by the U-Th method, Zak-1 was deposited between 3.1+0.04/-0.03 to 0.32+0.46/-0.44 ka (ka = kiloyears before 1950 AD); Zak-3 between 13.48+0.07/-0.08 to 10.11+0.05/-0.09 ka; Zak-4 between 12.01+0.08/-0.09 to 9.73+0.53/-0.61 ka; and Zak-6 between 8.77+0.07/-0.08 to 0.71+0.16/-0.13 ka, with a possible hiatus between 4.45+0.19/-1.49 and 3.27+1.35/- 0.34 ka. Timeseries of δ18O-δ13C from calcite show the main patterns of temperature variations during the last glacial-interglacial shift as well as throughout the Holocene, which mostly agree in pace and tempo with global records (i.e., Greenland ice and Atlantic/Mediterranean sediment cores). Then, δ18O-δ2H from speleothem fluid inclusions (FI) are preliminarily applied to quantitatively calculate temperatures. Conveniently, FI resulted well aligned with the modern meteoric water line in Georgia, thus indicating that isotopic fractionation occurred during the karst flow-path and calcite precipitation was negligible. FI-derived temperatures document the effects of climate warming in Southern Caucasus related to the last deglaciation, with a ca. 4.5ºC increase of average temperatures from ~12 to ~10 ka. Paleotemperatures during the Holocene instead presents a gradual decrease of around 2ºC from ~10 ka to ~3 ka. This potentially supports the existence of a Holocene thermal maximum during the Early Holocene, which is still a matter of debate. However, calculation uncertainties make this finding debatable. The interpretation of the record is refined by considering changes of rainfall (e.g., amount, provenance/source and seasonality) as well as soils (e.g., vegetation bioactivity). To comprehend the climate mechanisms of South Caucasus climate during rapid global instabilities, the Zak-timeseries is compared to the others from different climate regimes to advance the current characterization of regional climate shifts. Therefore, the results of this study certainly help to further investigate possible climatic teleconnections on a regional to global scale.

How to cite: Asanidze, L., Columbu, A., Fleitmann, D., Burns, S., Lezhava, Z., Tsikarishvili, K., Zanchetta, G., Natali, S., and McGee, D.: The first multi-proxy speleothem paleoclimate record from Georgia and calculations of temperature variations during the last ~ 13500 years , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14861, https://doi.org/10.5194/egusphere-egu24-14861, 2024.

EGU24-15117 | Orals | CL1.2.3 | Highlight

Towards a 500 kyr record of tropical land temperature from fluid inclusion microthermometry in Borneo speleothems 

Anna Nele Meckler, Yves Krüger, Marit H. Løland, Hao Ding, Camille Afonso, Verena Hof, Stacy Carolin, and Axel Timmermann

The advent of nucleation-assisted fluid inclusion microthermometry in speleothems (Krüger et al. 2011) opens new opportunities for accurate and precise reconstructions of land temperature in low latitudes. This physical approach, based on determination of liquid-vapor homogenization temperatures in fluid inclusions, does not need empirical calibration. Typical standard errors of the mean (2 SEM) resulting from measurements of 30-40 coeval fluid inclusions range between ~0.2 and 0.5 °C. In addition, the approach offers the rare opportunity to derive mean annual temperatures not affected by seasonal biases, due to year-round stable temperatures in the caves. However, the technique is limited to warm caves with temperatures above ~10°C and poses strict requirements on the samples in terms of calcite fabric and abundance and size of fluid inclusions.

Northern Borneo (4°N, 115°E) is situated in the heart of the Indo-Pacific Warm Pool, a major heat engine of the climate system. From this region, a set of well-dated speleothems covering the last half million years has previously been studied for hydroclimate reconstructions (Partin et al., 2007, Meckler et al., 2012, Carolin et al., 2013, Carolin et al. 2016). We are now revisiting these samples to generate a continuous land temperature record from this key area. Our data so far cover the last glacial termination (Løland et al., 2022) and several other terminations, interglacials, and glacials. We find glacial-interglacial changes in cave temperature of 4.4-5.4 °C, which reduce to 3.6-4.7 °C when correcting for sea-level induced changes in cave altitude. This amplitude is substantially larger than predicted by a transient Pleistocene simulation with CESM1.2 (Yun et al., 2023), suggesting either amplifying local factors not included in the model or a more general underestimation of the sensitivity of tropical temperatures to greenhouse and orbital forcing. The temporal evolution of Northern Borneo temperature for the most part follows the evolution of atmospheric CO2, as previously observed with marine records, but with notable exceptions where insolation forcing appears to be the dominant factor. Our evolving temperature record thus sheds new light on the role and response of one of the major players in the climate system during glacial-interglacial cycles.

 

References:

Carolin, S.A., et al., 2013. Science 340, 1564–1566.

Carolin, S.A., et al., 2016. EPSL 439, 182-193.

Krüger, Y., et al., 2011. Chem. Geol. 289, 39-47.

Løland, M.H., et al., 2022. Nature Communications 13: 5158.

Meckler, A.N., et al., 2012. Science 336, 1301–1304.

Partin, J.W., et al., 2007. Nature 449, 452–453.

Yun, K.-S., et al., 2023. Clim. Past, 19, 1951–1974.

 

How to cite: Meckler, A. N., Krüger, Y., Løland, M. H., Ding, H., Afonso, C., Hof, V., Carolin, S., and Timmermann, A.: Towards a 500 kyr record of tropical land temperature from fluid inclusion microthermometry in Borneo speleothems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15117, https://doi.org/10.5194/egusphere-egu24-15117, 2024.

EGU24-15402 | ECS | Orals | CL1.2.3

North Atlantic teleconnection reflected in a Mid-Holocene Ecuadorian speleothem 

Danny Vargas, László Palcsu, and Marjan Temovski

Paleoclimate reconstructions in northern tropical South America are scarce and hindered due to the small temperature fluctuations. In particular, the potential of records to study past climate variability close to the Equator (0° 0’ 0”) and at the periphery of the Amazon basin has been unexplored. The reason obeys to the complex orography of the Andes and the direct influence of the Intertropical Convergence Zone (ITCZ) and the South American Monsoon features (i.e., low level jets) which overlap at the so called “monsoon trough” and masks a clear annual seasonality.

In this contribution, we present a newly constructed speleothem record (Dino-1) from Central Ecuador based on 14 U-Th Ages from 6849±51 to 5469±62 yr (Mid-Holocene) for studying the evolution of the hydrology during centennial to millennial scales. For the calibration of the archive, we undertook a 4-year monthly monitoring of stable isotopes in precipitation (δ2H and δ18O) and temperature in the vicinity and inside the cave.

Results show that the rainfall lowest δ18O values occur during austral autumn (AMJ) and spring (ON), while higher values are found in summer (DJFM) and winter (JAS), displaying a strong negative correlation with the bimodal rainfall pattern. Lagrangian back trajectory analysis (2015-2022) indicates that moisture is seasonally advected from the Tropical North and South Atlantic. At centennial scale, the Dino-1 δ18O time series seems to capture the variability of Bond event 4 (abrupt cold ice-raft inputs from the North Atlantic), coherent with other paleoarchives (e.g., speleothems, lacustrine sediments, ice cores) in the same timeframe. On the other hand, at millennial scale, our record (although short) is in line with previous studies indicating that the ITCZ has been the main system modulating the climatology in Northern South America driven by the increment in the solar forcing input.

How to cite: Vargas, D., Palcsu, L., and Temovski, M.: North Atlantic teleconnection reflected in a Mid-Holocene Ecuadorian speleothem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15402, https://doi.org/10.5194/egusphere-egu24-15402, 2024.

EGU24-16895 | ECS | Orals | CL1.2.3

Palaeoclimate evolution over the last 10,000 years in Caumont cave in Normandy, France  

Ingrid Bejarano Arias, Carole Nehme, Sebastian F.M. Breitenbach, Isabelle Couchoud, Edwige Pons-Branchu, James Baldini, and Damase Mouralis

Speleothem-based palaeoclimate studies proliferate globally, but some regions remain poorly covered, including NW France. The cave and quarry system of Caumont, Normandy, develops in chalk limestone and contains speleothem formations that cover the Holocene. A new study on a recent stalagmite from the quarry (the last ca. 100 years) and detailed cave monitoring show that in this system speleothems form under near-equilibrium isotopic conditions (Bejarano et al. 2024). Monitoring shows that the δ13C signal in speleothems reflects summer prior carbonate precipitation as a response to infiltration dynamics while speleothem δ18O is mostly a signal of precipitation composition (with a bias towards winter). Thus, detailed study of stalagmite isotope records seems promising for the reconstruction of Holocene climate change in Normandy.

 

Here, we focus on 5 stalagmites collected from the Robots stream (SW) and La Jacqueline passages in the natural conduits of Caumont cave. All samples have been U-Th dated, yielding an age range of 10 to 0.3 ka for the two stalagmites from Robots stream, and 7 to 3 ka for the three stalagmites from La Jacqueline. We find several hiatuses and growth changes in the tested samples. All 5 stalagmites were sampled for stable isotopes (SI, δ18O and δ13C). In addition, and from one stalagmite from Robots was analysed for trace elements using laser ablation. We complement the SI and trace element data and discuss the evolution of the stalagmites growing periods and hiatuses for the last 10 ka. The stable isotope records reflect variations in palaeoclimate conditions that follow global patterns such as, increasing humid conditions during the Holocene optimum. The carbon isotope profile indicates drier conditions during early Holocene and wetter conditions between 8 and 5 ka. The oxygen isotope record also suggests more rain/snow infiltration during the mid-Holocene, with more negative values than in the early Holocene. These inferred changes are corroborated by Sr, Ba, Mg and Ca. We compare the new multi-proxy dataset with independent local studies and speleothem reconstructions from NW Europe to contextualise climate dynamics in Normandy within the broader Holocene development in Central Europe.

How to cite: Bejarano Arias, I., Nehme, C., Breitenbach, S. F. M., Couchoud, I., Pons-Branchu, E., Baldini, J., and Mouralis, D.: Palaeoclimate evolution over the last 10,000 years in Caumont cave in Normandy, France , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16895, https://doi.org/10.5194/egusphere-egu24-16895, 2024.

EGU24-17100 | ECS | Posters on site | CL1.2.3

Competing influence of the South American summer monsoon and the Southern Hemisphere westerlies on the mid-latitude Argentine Andes over the last 15,000 years as recorded in speleothems from Las Brujas Cave 

Angela Ampuero, Francisco Cruz, Nicolás Strikis, Hubert Vonhof, Fidel Roig, Julio Cauhy, Marcela Della Libera, Juan Pablo Bernal, Giselle Utida, Melissa Medina, Mathias Vuille, Ernesto Tejedor, Victor Mayta, Veronica Ramirez, Patricia Piacsek, Julian Schroeder, Lucas Cazelli, and Plinio Jaqueto

The Brujas cave is located in the eastern flank of the subtropical Andes, in the boundary between two major components of the climate system that drives precipitation variability over the South America: The South American monsoon system (SAMS) domain and the Southern hemisphere westerlies (SHW). As a result, the long-term hydroclimate variability in this region can be complex. Paleorecords from lake sediments and ice cores surrounding the area show meridional fluctuations of either the SAMS or the SHW, yet without long and high-resolution records, this area remains poorly constrained.

The deglacial and Holocene are interesting periods in this regard, providing valuable information about the atmospheric circulation in the western sector of SAMS in response to millennial-scale events of the last glacial. Moreover, changing climate forcings associated with ice volume and greenhouse gases can impact hydroclimate at these latitudes by reorganizing atmospheric circulation during the onset of the interglacial boundary conditions. For instance, the expansion of the Hadley cell under current global warming severely affects the regional hydroclimate of the mid-latitudes. Yet, our knowledge of this region is limited compared to what we know about the core SAMS region or the SHW in southernmost South America. New records from this transitional zone can provide clarity on the extent of variability in space and intensity of the SAMS and the SHW, serving as useful benchmarks to assess the performance of climate models in such a sensitive zone, right in interphase between two systems.

Here we present preliminary results from a stalagmite record (15,000 to 3,000 years) from Las Brujas cave, on the northern edge of the SHW domain. The westerlies transport moisture from the Pacific Ocean to the continent, where the Andes barrier induces orographic convection so that intense precipitation falls on the uphill side of the cordillera, over the Chilean Andes. The limited moisture that crosses the Andes and reaches the downslope area, produces precipitation over Las Brujas cave site during the cold months (April-September). Immediately north of Las Brujas cave, precipitation is concentrated in the warm season, produced by the South American low-level jet (SALLJ), a main component of the SAMS that transports moisture from the Amazon to northwestern Argentina. Given the proximity of both systems to our cave, precipitation contribution of either source is likely to have occurred in the past.  Our multiproxy record can potentially show periods of rainfall dominated by the SAMS or the westerlies and the relationship unveil local temperature variations. We find evidence of a slight trend from dryer to wetter conditions from the mid-Holocene onwards and a large shift from dry to wet from the deglacial to the early Holocene.

How to cite: Ampuero, A., Cruz, F., Strikis, N., Vonhof, H., Roig, F., Cauhy, J., Della Libera, M., Bernal, J. P., Utida, G., Medina, M., Vuille, M., Tejedor, E., Mayta, V., Ramirez, V., Piacsek, P., Schroeder, J., Cazelli, L., and Jaqueto, P.: Competing influence of the South American summer monsoon and the Southern Hemisphere westerlies on the mid-latitude Argentine Andes over the last 15,000 years as recorded in speleothems from Las Brujas Cave, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17100, https://doi.org/10.5194/egusphere-egu24-17100, 2024.

EGU24-17363 | Posters on site | CL1.2.3

Subaqueous carbonate speleothems as paleotemperature archives –clumped isotope thermometry and stable isotope compositions of inclusion-hosted water 

Attila Demény, Ágnes Berentés, László Rinyu, Ivett Kovács, Gergely Surányi, and Magdolna Virág

Clumped isotope measurements of carbonates and stable isotope analyses of water trapped in fluid inclusions are both promising techniques to determine carbonate formation temperatures. Cave-hosted carbonate deposits (speleothems) would be excellent targets for such studies, but kinetic fractionations and diagenetic influences frequently deteriorate the temperature data obtained with these methods. However, subaqueous carbonate deposits may provide reliable data as kinetic fractionations are less significant in underwater environment. In the present study subaqueous carbonate formations were investigated, whose formation temperatures were directly measured in the water. Additionally, temperatures calculated from oxygen isotope fractionations between calcite and fluid inclusion hosted water were compared with clumped isotope temperatures obtained for subaqueous carbonate formations in cave-hosted lakes. The clumped isotope temperatures fit the measured and calculated temperatures within the analytical precisions. Our study shows that subaqueous carbonate speleothems are useful targets for clumped isotope and inclusion water analyses, and therefore they are valuable paleotemperature archives.

How to cite: Demény, A., Berentés, Á., Rinyu, L., Kovács, I., Surányi, G., and Virág, M.: Subaqueous carbonate speleothems as paleotemperature archives –clumped isotope thermometry and stable isotope compositions of inclusion-hosted water, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17363, https://doi.org/10.5194/egusphere-egu24-17363, 2024.

EGU24-17584 | ECS | Orals | CL1.2.3

Classification of Phreatic Overgrowths on Speleothems (POS) from the Mallorca littoral caves 

Ana Entrena, Luis F. Auqué, María J. Gimeno, and Joan J. Fornós

Phreatic Overgrowth on Speleothems (POS) are a specific type of speleothem that growth at the surface of the brackish lakes in littoral caves. These lakes are direct or indirectly related to the height of the sea level, therefore, the POS precipitates at the height of the sea in the moment of their growth. This condition makes the POS a perfect marker of past sea level.

These speleothems are very unusual and have only been found in few caves around the world. Up to the present, most of these deposits have been located on the island of Mallorca, where the largest collection of this type of speleothems have been studied.

This study presents a complete classification of POS in hand-size scale and in thin section. The first one is based on the internal and external morphology of the POS and its acquired shape depending on the substrate on which these precipitates grow. The second one, related to the thin section study, allows to recognize a variety of crystalline fabrics: needle-like aragonite crystals (An), fibrous fascicular optic calcite (Ffo), columnar fascicular optic calcite (Cfo), columnar calcite (C), mosaic calcite (Mc), mosaic calcite with aragonite needles (MCan) and micrite (M) and microsparite calcite fabric (Ms). , Some of these fabrics were previously described in other speleothems (as stalactites or stalagmites) and others are new, not previously described in speleothems.

All this information shows several important ideas: 1) most of the POS precipitate around previous stalactite-type vadose speleothem; 2) aragonite POS are mainly globular and fan shaped in their external and internal morphology, respectively, and aragonite mineralogy only appears in needle-like crystal fabric; 3) calcite POS are related to branched internal and external morphology and present more variability in their crystal fabric, being the mosaic type the most common. The data obtained have been used to identify some relationships between the precipitation conditions of POS and the features of these precipitates. This classification and the conclusions of the precipitation conditions demonstrate the importance of POS as a proxy. Moreover, this study helps to understand the precipitation process of POS and can be implemented and reviewed in POS deposits of other parts of the world.

How to cite: Entrena, A., Auqué, L. F., Gimeno, M. J., and Fornós, J. J.: Classification of Phreatic Overgrowths on Speleothems (POS) from the Mallorca littoral caves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17584, https://doi.org/10.5194/egusphere-egu24-17584, 2024.

EGU24-17613 | ECS | Posters on site | CL1.2.3

Warm mean annual air temperatures during Miocene to Pleistocene central Arabian humid periods 

Julian Schroeder, Monika Markowska, Hubert Vonhof, Denis Scholz, Michael Weber, Nicole Boivin, Huw S. Groucutt, Michael D. Petraglia, Alfredo Martinez-Garcia, Yves Krüger, Anna Nele Meckler, Jens Fiebig, Samuel L. Nicholson, and Gerald Haug

The hydroclimate change in the hot and arid Arabian Desert under anthropogenic global warming is a subject of ongoing discussions. Climate models project rising mean annual temperatures coupled with decreasing precipitation averaged over Saudi Arabia with regional variance (Almazroui, 2020). Stable isotope analysis on a combined speleothem record from central Arabia revealed recurring local humid periods during globally warmer intervals over the past ~8 million years (Markowska et al., in review). The speleothem record showed a long-term drying trend towards present, which may potentially be controlled by temperature change. The present study aims to reconstruct mean annual air temperatures (MAATs) of central Arabia during humid periods. These temperatures provide valuable benchmark data for past and future climate models in a region where terrestrial climate archives are scarce. Recent advances in speleothem-based paleothermometry facilitate extracting robust MAATs. We present data from several independent paleothermometers: Fluid inclusion isotopes (de Graaf et al., 2020), TEX86 (Meckler et al., 2021; Wassenburg et al., 2021), fluid inclusion microthermometry (Krüger et al., 2011), and dual clumped isotopes (Bajnai et al., 2020). These reconstructions show that recurrent wet intervals during the Miocene to Pleistocene in the Arabian Peninsula occurred at warmer than modern MAATs. We note, however, that temperature is not the only driver of humidity in the Arabian Peninsula and that both dry and humid periods likely existed under a warmer than today’s climate. Therefore, these observations cannot directly be interpreted as indicator that anthropogenic global warming will lead to future wet conditions in Saudi Arabia. Overall, we provide novel quantitative paleoclimate parameters that can inform climate model experiments leading to improved predictions for future climate scenarios.

How to cite: Schroeder, J., Markowska, M., Vonhof, H., Scholz, D., Weber, M., Boivin, N., Groucutt, H. S., Petraglia, M. D., Martinez-Garcia, A., Krüger, Y., Meckler, A. N., Fiebig, J., Nicholson, S. L., and Haug, G.: Warm mean annual air temperatures during Miocene to Pleistocene central Arabian humid periods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17613, https://doi.org/10.5194/egusphere-egu24-17613, 2024.

EGU24-17753 | ECS | Posters on site | CL1.2.3 | Highlight

Central European lapse rate based on speleothem fluid inclusions 

Timon Kipfer, Dominik Fleitmann, Stéphane Affolter, Elisa Hofmeister, Anamaria Häuselmann, Marc Lütscher, and Hai Cheng

While the modern stable isotope lapse rate for precipitation shows a gradient of -0.19 ‰ per 100 meters elevation for Switzerland (Schotterer, 2010), there is only scarce information about the isotope lapse rate in the past and it is usually assumed that they remained constant through time. To investigate the lapse rate in the past, we use speleothems from caves along an altitudinal transect, which contain past drip water preserved in micrometric sized fluid inclusions (0.01 to 0.1 weight %). This drip water corresponds to precipitation water falling above the cave and thus constitutes an excellent archive of past precipitation, allowing us to determine lapse rates in the past. To extract and analyze this water, we used an improved speleothem fluid inclusion water extraction line available at the Quaternary Geology group of the University of Basel. The new design allows us to measure up to ten samples a day.

For this study, we measured more than 100 fluid inclusion samples from various stalagmites in a transect from the Jura mountains to the swiss alps with elevations ranging between 373 and 2’000 meters. These measurements enable us to obtain direct information on past precipitation as well as determine absolute paleotemperatures (Affolter et al., 2019). They allow us to determine the stable isotope and temperature lapse rates for different time intervals, such as Marine isotope stage 5a, the Younger Dryas and the Holocene.

Furthermore, to better understand the water isotopes in cave environments, we have launched (in 2023) the Citizen Science project “Cave Drip Water” in collaboration with various caving clubs in Switzerland and France (https://duw.unibas.ch/de/quartaergeologie/citizen-science/). The purpose of this program is to collect drip water samples and consequently monitor stable isotopes from numerous caves distributed at different elevations across Switzerland and in neighbouring regions. From this data, we will reconstruct a modern cave drip water lapse rate for Switzerland. In addition, it will allow us to investigate the spatial distribution of water isotopes in karst systems and compare it with the most recent water isotope patterns in precipitation from Switzerland. Moreover, these observations will set a baseline for the use of water isotopes analyzed in speleothem fluid inclusion measurements.

Here we present preliminary isotope and temperature lapse rates based on speleothem fluid inclusion water for the Holocene, Younger Dryas and the MIS 5a intervals as well as the first results from the Citizen science project “Cave Drip Water”.

REFERENCES

Schotterer U., Schürch M., Rickli R., Stichler W. (2010). “Wasserisotope in der Schweiz: Neue Ergebnisse und Erfahrungen aus dem nationalen Messnetz ISOT“ Gas, Wasser, Abwasser 2010

Affolter et al. (2019), Sci. Adv. 5 eaav3809, doi.org/10.1126/sciadv.aav3809

How to cite: Kipfer, T., Fleitmann, D., Affolter, S., Hofmeister, E., Häuselmann, A., Lütscher, M., and Cheng, H.: Central European lapse rate based on speleothem fluid inclusions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17753, https://doi.org/10.5194/egusphere-egu24-17753, 2024.

EGU24-17958 | ECS | Posters on site | CL1.2.3

A Late Holocene multi-proxy speleothem record from NW Türkiye 

Alistair Morgan, Hai Cheng, Lawrence R. Edwards, Albert Matter, Elisa Hofmeister, Okan Tüysüz, and Dominik Fleitmann

NW Türkiye is uniquely positioned between climatic influences from the North Atlantic, Mediterranean and Eurasia. Variability in climate systems through the Late Holocene is thought to have influenced major historical transitions, such as the ‘Bronze Age Collapse’, and during periods including the ‘Roman Climate Anomaly’ and the ‘Little Ice Age’. The region is noteworthy considering its geographical and historical significance over the last 4,000 years as a landscape for Ancient Greece Colonisation, the Roman Byzantine and Ottoman Empires and proximity to the common focal-point of modern-day Istanbul (Byzantium, Constantinople) which received much of its water from the cave’s locality. With the Eastern Mediterranean a hotspot for agricultural drought (Dabanlı et. al; 2017), which has impacted societies historically, the region warrants the study of spatio-temporal human-climate interactions.

Given the scarcity of sub-decadal palaeoclimate records regionally, and heterogeneity of Eastern Mediterranean climate generally (Jacobson et. al; 2021), stalagmite U-1 from Uzuntarla cave in Thrace helps fill this gap. Speleothem U-1 was dated using a combination of U/Th and 14C dates. The chronology is further refined by aligning distinct growth-shifts with well-dated and strong historical earthquakes. Using the combined evidence of calcite fabric and growth laminae changes, stable isotope (δ13C, δ18O), trace elements (Mg/Ca, Sr/Ca, P/Ca) and fluid-inclusion analysis, we find that U-1 is highly sensitive to changes in cold-season regional precipitation, seasonality and temperature. For example, increases in δ13C often coincide with narrowing of growth-laminae and increased Sr/Ca suggesting a unified influence by reduced drip-rate during poor recharge conditions. Effective infiltration is between Oct:Mar, making δ18O a combined indicator for Fall:Winter:Spring seasonality balance and temperature. Initial fluid inclusion temperature estimates are promising with work ongoing, however other factors are worth discussing such as aeolian oceanic Mg inputs. 

Initial results, often complimenting other regional palaeoclimate records, paints a picture of dynamic changes in climate over the last 3,900 years BP spanning key historical transitions. Speleothem U-1 describes a large shift in aquifer-recharge and seasonality preceding the Bronze Age Collapse impacting SW Asia around 1190 BCE. Recharge then peaks anomalously in 650-690 BCE during the Homeric Minimum, coinciding with the Greek Colonisation and Byzantium’s founding ~667 BCE. The acclaimed Roman Climate Anomaly (150 BCE-200 CE) is without wet-anomalies but stable for U-1, with later evidence of aridification. Wetter and stable conditions follow during 200-600 CE, a period encompassing defining historical events including the establishment of Constantinople as a powerhouse of the East Roman Empire and major infrastructure development including aqueduct expansion into Thrace. The Medieval Climate Anomaly (950-1250 CE) is defined by wet conditions during 760-1100 CE transitioning into lower aquifer recharge between 1100-1220 CE. Finally, the Little Ice Age (1400-1700 CE) shows highly variable conditions, but generally transitions from a wetter and colder period to lower aquifer recharge between 1220 and 1760 CE.

 

REFERENCES

Dabanlı et. al; 2017. Long-term spatio-temporal drought variability in Turkey. Journal of Hydrology, 552, pp.779-792.

Jacobson et. al; 2021. Heterogenous late Holocene climate in the Eastern Mediterranean—the Kocain Cave record from SW Turkey. Geophysical Research Letters, 48(20), p.e2021GL094733.

How to cite: Morgan, A., Cheng, H., Edwards, L. R., Matter, A., Hofmeister, E., Tüysüz, O., and Fleitmann, D.: A Late Holocene multi-proxy speleothem record from NW Türkiye, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17958, https://doi.org/10.5194/egusphere-egu24-17958, 2024.

EGU24-18292 | ECS | Orals | CL1.2.3

Climatic predictors of speleothem deposition in SW Asia 

Samuel Nicholson, Matthew Jacobson, Monika Markowska, Julian Schroeder, Hubert Vonhof, and Gerald Haug

Speleothems (stalagmites, stalactites and flowstones) are a powerful archive for reconstructing past climate conditions. These are secondary calcium-carbonate deposits that form in caves from the adequate supply of rainwater, soil CO2 and dissolved bicarbonate. They have been used extensively in arid regions, such as SW Asia, to reconstruct and benchmark past hydroclimatic conditions. Analysis of the distribution of active and inactive speleothem deposition across the Negev desert suggested a precipitation threshold of ~300-350 mm yr-1 is required for speleothems to deposit. This threshold has been applied to the broader SW Asia region to understand the minimum rainfall during periods of climate amelioration but has lacked specific region-wide analysis. Here, we apply logistic regression techniques and machine-learning methods to understand the climatic parameters which predict speleothem deposition across SW Asia. We show a gradual, rather than threshold response between speleothem deposition and rainfall amount, suggesting 1) precipitation over 300-350 mm yr is not a simple predictor of speleothem deposition across SW Asia, and 2) sites specific climates/environments and processes play an important role. We then apply a Random Forest machine-learning algorithm to our dataset to create a prediction of speleothem deposition. We show that minimum and maximum monthly rainfall, elevation, and a terrain roughness index are the most important variables, suggesting that water availability and topography are important predictors of speleothem deposition. Climate indices associated with temperature and evaporation contribute but play a less important role in the prediction. We emphasise the need for additional monitoring of external and internal cave environments to refine the climatic predictors of speleothem deposition in SW Asia and understand the site-specific processes that lead to the activation or cessation of speleothem growth. Importantly, our prediction provides a model which includes a range of climate-environmental data and may be used by researchers to locate new speleothem-bearing cave sites for study.

How to cite: Nicholson, S., Jacobson, M., Markowska, M., Schroeder, J., Vonhof, H., and Haug, G.: Climatic predictors of speleothem deposition in SW Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18292, https://doi.org/10.5194/egusphere-egu24-18292, 2024.

EGU24-18304 | Orals | CL1.2.3

Double negative peak of the 8.2 ky event and subsequent „overshoot” recorded in speleothems from Central Europe 

György Czuppon, Attila Demény, Szabolcs Leél-Össy, Mihály Óvári, Ke Lin, Mihály Molnár, Máté Karlik, Zoltán Siklósy, and Shen Shen Chuan-Chou

Several short-term climate anomalies occurred during the Holocene, of which the 8.2 k.y. event was the most pronounced. Several proxy records ranging from the North Atlantic to monsoonal regions indicate that this event had a semi-global impact. The release of large amounts of freshwater into the North Atlantic has been cited as a major cause of the slowing of oceanic thermohaline circulation (von Grafenstein et al., 1998; Barber et al., 1999), resulting in this climate perturbation. Despite the significance of this event, high-resolution speleothem records are relatively scarce (e.g. Duan et al., 2023; Wood et al., 2023). These high-resolution oxygen isotope records from eastern China to South America revealed the complex structure of the 8.2 ky event.

Here we present two high-resolution oxygen isotope records from Central Europe (Béke Cave, NE Hungary and Vacska Cave N Hungary), along with the chemical data of calcite and the hydrogen isotope composition of inclusion-hosted water. The high-resolution oxygen isotope time series reveals a double negative anomaly around 8.2 k.y., whereas a positive anomaly appears in the following period (8.1 k.y.). Similar patterns are also observed in the hydrogen isotope data series. Assuming that the temperature change was solely responsible for the observed systematics, this data is utilized to calculate the relative temperature increase/decrease. Apparently, a 1-1.5°C temperature decrease for the 8.2 k.y. event and a 2°C increase for the “overshoot” around 8.1 k.y. can be given. Moreover, the oxygen isotope composition may be affected not only by temperature but also by changes in the amount of precipitation and/or its seasonality, as well as by the shifting of the main route of moisture transportation (Atlantic vs. Mediterranean moisture sources). Calculated d-excess values might indicate some changes during these periods. Additionally, trace element composition suggests a shift in summer/winter precipitation amounts for the overshoot.

We are thankful for the support and permission of the Aggtelek National Park Directorate and the Duna-Ipoly National Park Directorate. The János Bolyai Research Scholarship of the Hungarian Academy of Sciences financially supported György Czuppon’s work.

Barber D.C, Dyke A., Hillaire-Marcel C., Jennings A. E., Andrews J. T., Kerwin M. W., Bilodeau G., McNeely R., Southon J., Morehead M. D., Gagnon J.-M. (1999) Forcing of the cold event of 8,200 years ago by catastrophic drainage of Laurentide lakes. Nature, 400, 344-348.

Duan, P., Li, H., Ma, Z., Zhao, J., Dong, X., Sinha, A., et al. (2023). Interdecadal to centennial climate variability surrounding the 8.2 ka event in North China revealed through an annually resolved speleothem record from Beijing. Geophysical Research Letters, 50(1), e2022GL101182.

von Grafenstein U., Erlenkeuser H., Müller J., Jouzel J. Johnsen S. (1998): The cold event 8200 years ago documented in oxygen isotope records of precipitation in Europe and Greenland. Climate Dynamics 14 : 73—81.

Wood, C. T., Johnson, K. R., Lewis, L. E., Wright, K., Wang, J. K., Borsato, A., et al. (2023). High-resolution, multiproxy speleothem record of the 8.2 ka event from Mainland Southeast Asia. Paleoceanography and Paleoclimatology, 38, e2023PA004675.

How to cite: Czuppon, G., Demény, A., Leél-Össy, S., Óvári, M., Lin, K., Molnár, M., Karlik, M., Siklósy, Z., and Shen Chuan-Chou, S.: Double negative peak of the 8.2 ky event and subsequent „overshoot” recorded in speleothems from Central Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18304, https://doi.org/10.5194/egusphere-egu24-18304, 2024.

EGU24-18609 | ECS | Posters on site | CL1.2.3 | Highlight

Central Europe paleotemperature estimates over the last 300,000 years inferred from speleothem fluid inclusion water isotopes from Milandre Cave (Switzerland)   

Elisa Hofmeister, Dominik Fleitmann, Hai Cheng, Timon Kipfer, Anamaria Häuselmann, and Stéphane Affolter

 

Speleothems are continental archive used to reconstruct paleoclimate and paleoenvironmental settings at a high resolution of time. One advantage is that they can be precisely dated using Uranium-Thorium dating methods. Speleothems usually contain small amounts of paleowater trapped in micrometer voids named fluid inclusions, which are sealed in the calcite fabric. This water constitutes a witness of past precipitation falling above the cave at the time the inclusion was sealed. To extract and analyze this water, we use a crushing and extraction line available at the Quaternary Geology group of the University of Basel, that allows the simultaneous analyses of fluid inclusion oxygen (δ18Ofi) and hydrogen (δDfi) water isotopes. In this study, we analyzed several stalagmites from Milandre Cave (Jura Mountains, Switzerland). Previous studies from this cave have already shown that δ18Ofi and δDfi can serve as key-proxies for paleotemperature reconstruction in central Europe (Affolter et al., 2019). For the temperature reconstruction, we use either the oxygen isotope fractionation between calcite and water as a paleothermometer or a transfer function based on the regional modern relationship between the water isotopes in precipitation and temperature. The resulting temperature estimates provide absolute mean annual cave and surface air temperatures, which, however, may be slightly biased towards the cold season. Stalagmites investigated in this study cover several glacial and interglacial periods, allowing us to reconstruct temperatures for the Holocene, Younger Dryas as well as for Marine Isotope Stages 5, 7, 8 and 9. Our preliminary results show absolute mean annual temperature in a plausible range with values ranging between 0°C and 9.6°C. To gain more information about glacial temperature change, we will use stalagmites coming from additional caves located in the western part of the Jura Mountains.

These quantitative paleotemperature snapshots obtained from Milandre Cave, together with those obtained from speleothems from neighboring caves in the Jura Mountains, will allow to document and enhance the comprehension of the temperature evolution of central Europe over the last 300,000 years before present.

 

Affolter et al. (2019), Sci. Adv. 5 eaav3809, doi.org/10.1126/sciadv.aav3809

How to cite: Hofmeister, E., Fleitmann, D., Cheng, H., Kipfer, T., Häuselmann, A., and Affolter, S.: Central Europe paleotemperature estimates over the last 300,000 years inferred from speleothem fluid inclusion water isotopes from Milandre Cave (Switzerland)  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18609, https://doi.org/10.5194/egusphere-egu24-18609, 2024.

EGU24-18793 | ECS | Posters on site | CL1.2.3

Fluid Inclusion Microthermometry in Borneo stalagmites: Investigating the role of fabric and open porosity on temperature reconstructions 

Marit H. Løland, Yves Krüger, Leonardo Pasqualetto, Silvia Frisia, Andrea Borsato, Judson W. Partin, Jess F. Adkins, Kim M. Cobb, and Anna N. Meckler

Fluid inclusion microthermometry has emerged as a powerful tool for reconstructing past land temperatures from speleothems. An implicit assumption of the method is that the closing age of the fluid inclusions is equal to the age of the surrounding calcite, and thus, that the reconstructed temperatures are representative of the cave temperature at which the calcite layers formed. The present study, however, demonstrates that this assumption does not hold true for all stalagmites.

Here we show as an example our results obtained from stalagmite SSC01 from Snail Shell Cave (Northern Borneo), that spans the last ~27,000 years, and that was previously investigated for hydroclimate reconstructions (Partin et al., 2007). A temperature record was reconstructed by means of nucleation-assisted microthermometry (Krüger et al., 2011) by analysing ~20 – 70 individual fluid inclusions in each of the 34 growth bands along the growth axis of SSC01. The Holocene part of the record yields near Gaussian-shaped distributions within coeval fluid inclusion assemblages, while the glacial and early deglacial part shows a considerable spread among seemingly co-eval inclusions, with bimodal distributions. When applying a Gaussian deconvolution routine, we find that the warmer part of these distributions consistently yields temperatures resembling late deglacial or Holocene temperatures. Temperatures of the colder mode of the distributions, in contrast, reflect glacial and deglacial conditions showing a clear deglacial warming trend that closely follows atmospheric CO2 and Southern Hemisphere warming.

We hypothesize that the warmer mode of these bimodal distributions is a result of open porosity, networks of interconnected cavities that sealed off from the environment towards the end of the glacial Termination, i.e., at a temperature that was significantly higher than the formation temperature of the surrounding calcite host. This interpretation is further supported by petrographic observations, revealing that the glacial and deglacial part of the stalagmite is characterized by frequent alterations of columnar open fabrics (Frisia et al., 2015) and organic-rich micritic layers with high porosity. We suppose that open porosity in stalagmites can occur both vertically along the columnar crystal boundaries and also laterally along specific growth layers.

Bimodal temperature distributions in seemingly coeval fluid inclusions can arise due to temporary open porosity, provided that the temperature difference between the different closing ages of the inclusions is large enough. Our findings emphasize the need for careful consideration of fabric-related factors that can affect the temperatures derived from fluid inclusions.

 

 

References:

Frisia, S (2015). Microstratigraphic logging of calcite fabrics in speleothems as tool for palaeoclimate studies. Int. J. Speleol. 44, 1–16.

Krüger, Y. et al. (2011). Liquid–vapour homogenisation of fluid inclusions in stalagmites: Evaluation of a new thermometer for palaeoclimate research. Chem. Geol. 289, 39–47.

Partin, J.W., et al (2007). Millennial-scale trends in west Pacific warm pool hydrology since the Last Glacial Maximum. Nature 449, 452.

How to cite: Løland, M. H., Krüger, Y., Pasqualetto, L., Frisia, S., Borsato, A., Partin, J. W., Adkins, J. F., Cobb, K. M., and Meckler, A. N.: Fluid Inclusion Microthermometry in Borneo stalagmites: Investigating the role of fabric and open porosity on temperature reconstructions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18793, https://doi.org/10.5194/egusphere-egu24-18793, 2024.

Hydrogen (δD) and oxygen (δ18O) stable isotopes contained in speleothem (cave carbonate) fluid inclusion water allow the quantitative reconstruction of past temperatures. Reconstructions can be based either on the use of a regional modern transfer function between isotopes in precipitation and temperatures (expressed in ‰ / °C) or based on the fractionation between the oxygen isotopes measured in the calcium carbonate and in the corresponding inclusion water. One advantage of this proxy is that temperature reconstruction is constrained by chemico-physical processes. Based on a δD gradient of 3.84‰ / 1°C, we reconstructed quantitative temperature variations occurring during the interval 9.0 ka to 7.8 ka BP for the central and western Europe area with a mean temporal resolution of approximately 25 years. The isotope profile shows that the 8.2 ka cold event is characterized by negative shifts in δD and δ18O consistent with numerous records from across the Northern Hemisphere such as for example Mondsee and Ammersee lake sediments in central Europe or at a larger scale in ice cores from Greenland. Across the 8.2 ka event, the new high-resolution Milandre Cave Fluid Inclusion Temperature (MC-FIT) shows a remarkable similarity with the physically constrained temperature reconstruction from Greenland ice cores that is based on nitrogen and argon isotopes of trapped air (Kobashi et al., 2017). This record, supported by additional speleothems from a neighboring cave, provides a better understanding of the continental temperature evolution across the 8.2 ka event.

Affolter S. et al.: Central Europe temperature constrained by speleothem fluid inclusion water isotopes over the past 14,000 years. Sci. Adv.5, eaav3809. DOI:10.1126/sciadv.aav3809, 2019

Kobashi, T., Menviel, L., Jeltsch-Thömmes, A. et al.: Volcanic influence on centennial to millennial Holocene Greenland temperature change. Sci Rep 7, 1441. https://doi.org/10.1038/s41598-017-01451-7, 2017

How to cite: Affolter, S., Cheng, H., and Fleitmann, D.: Temperature evolution across the 8.2 ka event based on speleothem fluid inclusion water isotopes from Milandre Cave (Switzerland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18882, https://doi.org/10.5194/egusphere-egu24-18882, 2024.

EGU24-19221 | ECS | Posters on site | CL1.2.3 | Highlight

Hydrological and temperature variations in the Black Sea region during the last 650’000 years recorded by speleothem fluid inclusions 

Frederick Held, Hai Cheng, R. Lawrence Edwards, Okan Tüysüz, and Dominik Fleitmann

The Eastern Mediterranean including the Black Sea region is influenced by subtropical Mediterranean, temperate European, and continental Asian air masses which make paleoclimate archives from the Black Sea region a valuable source of information about past climatic changes in temperature and rainfall. On glacial interglacial time scales, most information on climate variability in the Black Sea region comes almost entirely from marine/lake sediment cores (e.g. Wegwerth et al., 2015, 2020; Shumilovskikh et al., 2012). In contrast to these paleoclimate archives, oxygen isotope ratios of speleothem calcite (δ18O) and water isotope ratios (δDFI and δ18OFI) of speleothem fluid inclusions from Sofular Cave in northern Turkey can provide direct information on the isotopic composition of rainfall and, therefore, potentially identify the sources of moisture at the Black Sea coast. During the last 650’000 years most of the δDFI and δ18OFI values plot closer to the Local Meteoric Water Line (LMWL) than to the Eastern Mediterranean Water Line (EMWL). This indicates that the Black Sea was the dominant moisture source for Sofular Cave during glacial and interglacial periods (Fleitmann et al., 2009; Badertscher et al., 2011). In addition, isotope measurements on speleothem fluid inclusions enables us to reconstruct temperature changes. Holocene temperatures of ~15°C to ~20°C are within the range of modern cave air temperatures and proxy records from the Black Sea (Sanchi et al., 2014; Ménot and Bard, 2012). During the last glacial period fluid inclusions indicate a temperature increase associated with Dansgaard-Oeschger warming events.

 

REFERENCES

 

Badertscher, S., Fleitmann, D., Cheng, H., Edwards, R.L., Göktürk, O.M., Zumbühl, A., Leuenberger, M., Tüysüz, O. 2011: Pleistocene water intrusions from the mediterranean and caspian seas into the Black Sea, Nature Geoscience, 4 (4), 236–239.

 

Fleitmann, D., Cheng, H., Badertscher, S., Edwards, R.L., Mudelsee, M., Goktürk, O.M., Fankhauser, A., Pickering, R., Raible, C.C., Matter, A., Kramers, J., Tüysüz, O. 2009: Timing and climatic impact of Greenland interstadials recorded in stalagmites from northern Turkey, Geophysical Research Letters, 36 (19), L19707.

 

Menot, G., & Bard, E. 2012: A precise search for drastic temperature shifts of the past 40,000 years in southeastern Europe, Paleoceanography, 27(2).

 

Sanchi, L., Ménot, G., & Bard, E. 2014: Insights into continental temperatures in the northwestern Black Sea area during the Last Glacial period using branched tetraether lipids, Quaternary Science Reviews, 84, 98-108.

 

Shumilovskikh, L. S., Tarasov, P., Arz, H. W., Fleitmann, D., Marret, F., Nowaczyk, N., Plessen, B., Schlütz, F. & Behling, H. 2012: Vegetation and environmental dynamics in the southern Black Sea region since 18 kyr BP derived from the marine core 22-GC3, Palaeogeography, Palaeoclimatology, Palaeoecology, 337, 177-193.

 

Wegwerth, A., Ganopolski, A., Ménot, G., Kaiser, J., Dellwig, O., Bard, E., Lamy, F. & Arz, H. W. 2015: Black Sea temperature response to glacial millennial‐scale climate variability, Geophysical Research Letters, 42(19), 8147-8154.

 

Wegwerth, A., Kaiser, J., Dellwig, O., & Arz, H. W. 2020: Impact of Eurasian ice sheet and North Atlantic climate dynamics on Black Sea temperature variability during the penultimate glacial (MIS 6, 130–184 ka BP), Paleoceanography and Paleoclimatology, 35(8), e2020PA003882.

How to cite: Held, F., Cheng, H., Edwards, R. L., Tüysüz, O., and Fleitmann, D.: Hydrological and temperature variations in the Black Sea region during the last 650’000 years recorded by speleothem fluid inclusions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19221, https://doi.org/10.5194/egusphere-egu24-19221, 2024.

EGU24-19492 | Posters on site | CL1.2.3

Decoding the climatic signal recorded in speleothems from La Cova del Drac in Mallorca 

Judit Torner, Isabel Cacho, Joan Fornós, Albert Català, Mercè Cisneros, Ileana Bladé, Ana Moreno, and Heather Stoll

Cova del Drac, situated on Mallorca Island, is one of the most frequented caves in Europe. During the late 19th century, pioneering explorers developed initial naturalistic expeditions and topographic studies. Nevertheless, it was not until the period between 1922 and 1935 that adaptation work was developed, leading to the establishment of permanent pathways, including the installation of the first lighting system. The two speleothems presented in this study were growing beyond these anthropogenic structures allowing a geochronological control into their initial growth.

The examination of confocal laser scanning microscopy images of these two speleothems revealed distinct fluorescence banding, pointing to seasonal growth patterns. Additionally, high-resolution trace element profiles, acquired using LA-ICP-MS, reveal geochemical cycles reflecting the impact of seasonal cave ventilation on the trace element signatures within the speleothems. Through the combination of annual fluorescence layer counting, analysis of trace element cycles, and the adjustment with the 14C bomb peak as a tie point, well-resolved age models spanning certainly the past century have been achieved.

This study establishes a robust framework by correlating the speleothem geochemistry results with cave monitoring and meteorological data. This exercise discerns the influence of the cave atmosphere seasonality from the hydrological and regional climatic signal across longer time scales. Consequently, this study validates the geochemical signal recorded in Mallorca cave speleothems as a reliable indicator of climatic variability in the western Mediterranean region.

How to cite: Torner, J., Cacho, I., Fornós, J., Català, A., Cisneros, M., Bladé, I., Moreno, A., and Stoll, H.: Decoding the climatic signal recorded in speleothems from La Cova del Drac in Mallorca, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19492, https://doi.org/10.5194/egusphere-egu24-19492, 2024.

EGU24-20041 | ECS | Posters on site | CL1.2.3

Towards a comparison of interglacial climate variability in the tropics during the last 300.000 years 

Aaron Mielke, Sophie Warken, Noreen Garcia, Christopher Charles, Frank Keppler, Isabel Rivera Collazo, Angel Acosta Colon, and Amos Winter

To better estimate effects of current climate change on the water cycle in the highly variable tropical region, past periods of similarly warm climate conditions can provide unique insights. The interglacial phases of the past 800,000 years are promising targets for this purpose, since these provide a natural variety of different climate configurations. While several reconstructions of past interglacial periods are available, the terrestrial, and in particular tropical regions are still under-represented in the record. Speleothems can be used to observe changes and effects on the eco- and climate system as well as their coupling on seasonal to millennial time scales, which usually cannot be resolved by climate model simulations.

This project aims to further close the research gap of these regions with investigations of stalagmites from Cueva Larga, Puerto Rico. Cueva Larga is a well-monitored location1,2,, and speleothem records from this cave have demonstrated a high sensitivity to regional and global climatic variations, in particular changes in the position of the ITCZ, Atlantic sea surface temperatures and ocean circulation3,4. First precise 230Th/U ages on previously collected stalagmites show the potential to reconstruct climatic variations during parts of the past interglacials of the past 300,000 years, i.e., MIS1, MIS, 5, MIS7, and MIS9. In the next step, time series from high-resolution trace element and stable isotope measurements (δ18O and δ13C) from these interglacials will be conducted.

The multi-proxy speleothem time series will allow to improve the quantitative and qualitative understanding of precipitation intensity and variability during interglacials and also help to constrain both the sensitivity of the Earth system in the tropics to different climatic drivers and the extent of current climate change compared to natural variability.

References:

1 Vieten et al. (2017). Monitoring of Cueva Larga, Puerto Rico—A First Step to Decode Speleothem Climate Records. Advances in Karst Science, Springer International Publishing, p.319-331

2 Vieten et al. (2018). Hurricane Impact on Seepage Water in Larga Cave, Puerto Rico. Journal of Geophysical Research: Biogeosciences, Vol. 123, No. 3

3 Warken et al. (2020). Persistent Link Between Caribbean Precipitation and Atlantic Ocean Circulation During the Last Glacial Revealed by a Speleothem Record from Puerto Rico. Paleoceanography and Paleoclimatology, Vol. 35, No. 11

4 Warken et al. (2022). Last glacial millennial-scale hydro-climate and temperature changes in Puerto Rico constrained by speleothem fluid inclusion δ18O and δ2H values. Climate of the Past, Vol. 18, No. 1

How to cite: Mielke, A., Warken, S., Garcia, N., Charles, C., Keppler, F., Rivera Collazo, I., Acosta Colon, A., and Winter, A.: Towards a comparison of interglacial climate variability in the tropics during the last 300.000 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20041, https://doi.org/10.5194/egusphere-egu24-20041, 2024.

EGU24-20724 | ECS | Orals | CL1.2.3

Understanding the moisture source of orbitally controlled changes in northern Sahara rainfall: a multi-proxy speleothem approach 

Mahjoor Lone, Michael Rogerson, Dirk Hoffmann, Marc Luetscher, Christoph Spötl, Moez Mansoura, Nejib Kallel, Noureddine Elmejdoub, and Yury Dublyanski

The Sahara, the largest hot desert in the world, has witnessed green, humid phases in the past. It is clear that large areas of what is now arid/hyper-arid desert became vegetated, that currently fossil rivers flowed sufficiently to reach the Mediterranean, and that the African Monsoon is key in regulating this variance on the southern margin of the desert. However, what is happening on the northern margin, what regulates those changes and how the different northern and southern rainfall systems combine to affect the interior of the Saraha are poorly known. Closing this knowledge gap is an urgent priority, because climate models predict an enhanced drying under future global warming, but the IPCC give this forecast only “Medium” confidence and it contrasts strongly with those paleoclimatic records which indicate a greener Sahara during the warmer times through the Pleistocene. So, to understand what controlled the northern Sahara in the past, we use a multi-proxy approach using the longest absolute-dated speleothem records from Tunisia in central North Africa. This unique resource allows us to decipher periods of significant rainfall in this region through isotopic measurements and a direct indication of possible moisture sources through fluid inclusions.

The records indicate a strong orbital control on past hydroclimatic changes suggesting enhanced rainfall during MIS 3, 5, 7 and 9. The fluid inclusions are consistent with a Western Mediterranean source for most rainfall, with some derived from the Atlantic. For much of the record, deuterium excess is highest in the samples with the most depleted d18O and d2H, which is consistent with some rainfall being derived from Mediterranean-derived high-intensity events, analogous to modern “medicanes”. High deuterium excess is also found during MIS5e, which is the only time the fluid inclusions we report from Tunisia are similar in composition to those we have already published for Libya, indicating an enhanced Eastern Mediterranean source occurred during the Eemian which is not reflected during other times of MIS5.

How to cite: Lone, M., Rogerson, M., Hoffmann, D., Luetscher, M., Spötl, C., Mansoura, M., Kallel, N., Elmejdoub, N., and Dublyanski, Y.: Understanding the moisture source of orbitally controlled changes in northern Sahara rainfall: a multi-proxy speleothem approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20724, https://doi.org/10.5194/egusphere-egu24-20724, 2024.

EGU24-21841 | ECS | Posters on site | CL1.2.3

Speleothems in northeastern Namibia as archives of hydroclimatic changes 

Leonie Leitgeb, Gabriella Koltai, Yuri Dublyansky, Haiwei Zhang, Hai Cheng, and Christoph Spötl

The hydroclimatic variability of southern Africa during the Quaternary is comparatively poorly know, partly due to the scarcity of suitable terrestrial paleoclimate archives in this semi-arid to arid region. Speleothems offer great potential for filling these knowledge gaps, and carbonate units exhibiting karst features are present in several regions. One such area is the Otavi Mountains of northeastern Namibia, where caves have developed in Neoproterozoic carbonate rocks. However, despite encouraging early work, only two speleothems from one Otavi cave have so far been studied using state-of-the-at techniques.

As part of a research programme investigating the origin of caves in the Otavi Mountains, we were given permission to also sample speleothems, focusing on flowstones, which are locally abundant. Although most of these formations are currently inactive, there are local exceptions that allow to obtain proxy records covering also the Holocene. Most of the flowstones, however, were active during the late Pleistocene, with a marked growth pulse during the deglacial. Remarkably, none of the 70 dated subsamples formed during the Last Interglacial. The picture that emerges from this preliminary dataset suggests favoured speleothem growth (and higher average growth rates) during periods when the Intertropical Convergence Zone was shifted far to the south as a result of cold boreal conditions.

While other parts of Namibia, such as the Namib Desert, may be more sensitive to hydroclimate changes leading to complete growth stops during interglacials, the higher rainfall and cooler temperatures in the Otavi Mountains open the door to obtain longer proxy records characterized by fewer hiatuses.

How to cite: Leitgeb, L., Koltai, G., Dublyansky, Y., Zhang, H., Cheng, H., and Spötl, C.: Speleothems in northeastern Namibia as archives of hydroclimatic changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21841, https://doi.org/10.5194/egusphere-egu24-21841, 2024.

EGU24-177 | Orals | CL1.2.4

Effect of horizontal flow on the age field along the Dome C – Little Dome C flow line 

Ailsa Chung, Frédéric Parrenin, Robert Mulvaney, Luca Vittuari, Massimo Frezzotti, and Olaf Eisen

We present a 2.5D pseudo-steady state inverse model applied to the flow lines from Dome C to LDC and from Dome C to North Patch (an area ~10km NE of Dome C). The model is constrained by radar horizons dated from 10-476 ka using the EPICA Dome C (EDC) ice core. We interpolate and extrapolate the age-depth relationship using these horizons. The simplicity of our 2.5D numerical integration scheme results in an efficient computation time allowing us to use inverse methods to determine an average accumulation rate over the past 800 ka, a mechanical ice thickness and the thinning parameter which describes the shape of vertical velocity profile. The inverted mechanical ice thickness allows us to infer either the melt rate or the thickness of a layer of stagnant basal ice.

The model shows that the EDC-LDC flow line is dominated by melting on in the upstream sections, and further downstream, there is a thick layer of stagnant ice over the LDC mountainous bedrock relief. Our results show to what extent the Beyond EPICA - Oldest Ice drill site is affected by horizontal flow from upstream at the dome and the implications for the age-depth profile of the ice core currently being drilled. The deepest oldest ice at the drill site, comes from 10-15 km upstream. However, the differences between the model and observations cannot be fully explained by horizontal flow. We also show that North Patch is a promising potential oldest ice site but more high-resolution radar surveys would be required to constrain this. This model could be applied to other areas of Antarctica of Greenland such as the flow lines from Dome Fuji to EDML or at from Ridge B to lake Vostok or from GRIP to EGRIP.

This work is part of the network of DEEPICE PhD projects associated with the Beyond EPICA drilling project which aims to recover a continuous 1.5 million year old ice core from Little Dome C in Antarctica.

 

How to cite: Chung, A., Parrenin, F., Mulvaney, R., Vittuari, L., Frezzotti, M., and Eisen, O.: Effect of horizontal flow on the age field along the Dome C – Little Dome C flow line, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-177, https://doi.org/10.5194/egusphere-egu24-177, 2024.

Glaciochemical data sourced from ice cores in polar regions and the Alps have been extensively examined. However, quantitative studies on glaciochemical records of the Tibetan Plateau (TP) are scarce. To address this, we investigated annual variations in the major soluble ions (Ca2+, Mg2+, Na, K, NH++4+, Cl, NO3, and SO42−) in the Aru ice core on the northwestern TP from 1850 to 2016. Applying a positive matrix factorization model, the sources of the major soluble ions and three factors to evaluate natural and agricultural impacts were identified. Factor 1, crustal dust with high loadings of Mg2+ (81.9%) and Ca2+ (68.7%), significantly positively correlated with wind speed and significantly negatively correlated with δ18O and net accumulation recorded by the ice core, suggesting that strong winds contributed to crustal dust transport from arid and semi-arid regions of Central Asia and deposition in the Aru glacier. However, relatively warm and wet climate prevented the transport of crustal dust. Factor 2 comprised salt lakes with high dominant loadings of Na (75.3%), SO+42− (64.1%), Cl (60.8%), NO3 (52.2%), and K (49.4%). Declining lake water levels exposed salt lake minerals, which were carried to glaciers under the dynamic conditions of strong winds, whereas warming resulted in an expansion of glacial meltwater and lake water volume, which decreased the contribution of salt lake sediments. Therefore, the contribution of salt lake deposition decreased. Factor 3 was agricultural sources with a high loading of NH+4+ (82%), whose trend aligned closely with the population number and N productions from agricultural sources in South and Central Asia, suggesting that NH3 emissions from agricultural practices are a critical contributor to Factor 3. This study quantified the proportional contribution of natural and agricultural sources to glaciochemical composition, advancing our understanding of glaciochemical records in ice cores from source recognition to quantification.

How to cite: Yang, D., Yao, T., and Wu, G.: Identifying the natural and agricultural impacts on the glaciochemistry of the Aru ice core on the northwestern Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1813, https://doi.org/10.5194/egusphere-egu24-1813, 2024.

EGU24-2636 | Orals | CL1.2.4

Development of deformational regimes and microstructures in the deep sections and overall layered structures of the Dome Fuji ice core, Antarctica 

Shuji Fujita, Tomotaka Saruya, Atsushi Miyamoto, Kumiko Goto-Azuma, Motohiro Hirabayashi, Akira Hori, Makoto Igarashi, Yoshinori Iizuka, Takao Kameda, Hiroshi Ohno, Wataru Shigeyama, and Shun Tsutaki

An in-depth examination of rheology within the deep sections of polar ice sheets is essential for enhancing our understanding of glacial flow. In this study, we investigate the crystalline textural properties of the 3035-m-long Antarctic deep ice core, with a particular emphasis on its lowermost 20%. We examine the crystal orientation fabric (COF) and compare it with various other properties from the ice core. In the uppermost approximately 80% thickness zone (UP80%), the clustering strength of single pole COF steadily increased, reaching its possible maximum at the bottom of the UP80%. Below 1800 m in the UP80%, layers with more or fewer dusty impurities exhibit slower or faster growth of cluster strength. This situation continued until 2650 m. In the remaining lowermost approximately 20% thickness zone (LO20%), the trend of the COF clustering strength changed around 2650 m and exhibited substantial fluctuations below this depth. In more impurity-rich layers, stronger clustering is maintained. In impurity-poor layers, relaxation of the COF clustering occurred due to the emergence of new crystal grains with c-axis orientation distinctly offset from the existing cluster, and dynamic recrystallization related to this emergence. The less impure layers show apparent features of bulging and migrating grain boundaries. We argue that the substantial deformational regime of polar ice sheets involves dislocation creep in both UP80% and LO20%, with dynamic recrystallization playing a critical role in the LO20%, particularly in impurity-poor layers, to recover a potential of COF available for the continuation of dislocation-creep-based deformation. Furthermore, we observe that layers and cluster axes of COF rotate meridionally due to rigid-body rotation caused by simple shear strain above subglacial slopes. These features provide vital clues for the development of the 3D structure of polar ice sheets in the deeper part, leading to inhomogeneous deformation between layers in various thickness scales, and the formation of folds, faults and mixing depending on the layers.

How to cite: Fujita, S., Saruya, T., Miyamoto, A., Goto-Azuma, K., Hirabayashi, M., Hori, A., Igarashi, M., Iizuka, Y., Kameda, T., Ohno, H., Shigeyama, W., and Tsutaki, S.: Development of deformational regimes and microstructures in the deep sections and overall layered structures of the Dome Fuji ice core, Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2636, https://doi.org/10.5194/egusphere-egu24-2636, 2024.

EGU24-2650 | ECS | Posters on site | CL1.2.4

Evaluation of historical SO2 emissions based on an inversion of ice core records using atmospheric transport modeling 

Andreas Plach, Sabine Eckhardt, Ignacio Pisso, Nathan Chellman, Joseph R. McConnell, and Andreas Stohl

Sulfur dioxide (SO2) is an air pollutant which can have harmful effects on both human health and the environment. Furthermore, SO2 also contributes to climate change — SO2 emissions form sulfate aerosols that act as cloud condensation nuclei, increasing cloud formation and decreasing solar radiation reaching the surface. An accurate knowledge of past SO2 emissions is therefore essential to quantify and model the associated global climate forcing. Current bottom-up SO2 emission inventories used for historical Earth System Modeling (ESM) are poorly constrained by observations prior to the late 20th century.

Here we revisit and evaluate the historical SO2 emission inventories of the last 150 years used in the Coupled Model Intercomparison Project Phase 6 (CMIP6). Our emission reconstruction is based on an inversion technique employing an array of ice core records of deposited sulfur and atmospheric transport/deposition modeling. The inversion technique minimizes discrepancies between the spatial-temporal patterns of emission inventories and the observed deposition at the ice core sites.

We find substantial differences between reconstructed SO2 emissions and existing bottom-up inventories which do not fully capture the spatial-temporal emission patterns. Our results imply that changes to existing historical emission inventories might be necessary in order to ensure an accurate modeling of the Earth’s climate sensitivity within future ESM simulations.

How to cite: Plach, A., Eckhardt, S., Pisso, I., Chellman, N., McConnell, J. R., and Stohl, A.: Evaluation of historical SO2 emissions based on an inversion of ice core records using atmospheric transport modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2650, https://doi.org/10.5194/egusphere-egu24-2650, 2024.

Investigating climate change through the reconstruction and modeling of atmospheric CO2 provides valuable insights for scientists aiming to unravel climate-carbon cycle feedback. The correlation between temperature and greenhouse gases, as inferred from ice core records, holds the potential to improve the accuracy of simulating CO2 variations. This study sought to investigate modeling approaches for accurately simulating atmospheric CO2 concentrations. To address data gaps in CO2, CH4 concentration, and temperature proxies (δD and δ18O) from Antarctica ice cores were incorporated. The study utilized Artificial Neural Network (ANN) and Wavelet Transform (WT) techniques to enhance precision in these simulations. Three distinct ice cores were utilized in this study, specifically the EPICA Dronning Maud Land (EDML) core for 70-115 thousand years ago (ka), the Dome Fuji (DF) core spanning 9-120 ka, and the West Antarctic Ice Sheet (WAIS) Divide core covering the period of 9~70 ka. The findings affirmed that the implementation of the WT-ANN model proved to be a successful approach for simulating CO2 concentrations throughout the study timeframe. The results highlighted the notable impact of time resolution in influencing the outcomes of the AI model. Particularly, utilizing high-resolution data from the WAIS Divide spanning 9-70 ka resulted in an impressive R2 value of up to 0.96, indicating a strong correlation between the model predictions and the ice core records using the hybrid method. Applying the WT-ANN hybrid methodology, which integrated WAIS (training periods of 9-29 and 57-70 ka) and DF data (training periods of 9-29 and 57-120 ka), a simulation of CO2 concentrations spanning 29-57 thousand years ago (MIS3) was carried out. The model demonstrated superior performance during the MIS3 test phase for the WAIS, with an R2 value of 0.85 and an RMSE of 3.62 ppm, compared to the DF core, where the R2 was 0.74 and the RMSE was 6.91 ppm. In our future initiatives, we intend to broaden our modeling efforts by integrating diverse AI techniques and employing numerous ice core samples across various time periods. Through the pursuit of this strategy, we aim to create exceptionally accurate simulations of CO2 levels. This not only advances our comprehension of historical climate dynamics but also addresses research gaps, paving the way for future investigations.

How to cite: Salehnia, N. and Ahn, J.: Simulating Atmospheric CO2 Levels Using CH4 and Temperature Proxy Records by ANN-Wavelet technique, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3293, https://doi.org/10.5194/egusphere-egu24-3293, 2024.

EGU24-3852 | ECS | Orals | CL1.2.4 | Highlight

Origin of silty basal ice in Greenland 

Lisa Ardoin, Jean-Louis Tison, Paul Bierman, Pierre-Henry Blard, Dorthe Dahl-Jensen, Vasileios Gkinis, Catherine Larose, Jorge Peder Steffensen, Thomas Rockmann, and François Fripiat

Stratigraphically disturbed and debris-rich, the basal silty layers of Greenland ice sheet bear unique information on the environment prior to the ice sheet build up [1] and on the subglacial ecosystem [2]. Previous studies have shown that processes such as mixing, diffusion, melting and refreezing, gas expulsion, and in-situ production of CO2 and CH4 have disturbed the paleoclimatic signals within the ice silty layers of Greenland [2, 3, 4]. Analytical techniques commonly used in deep ice core studies encounter limitations when applied to the ice-bedrock interface layers due to embedded debris. As part of the DEEPICE project, we have revisited the paleoclimatic information preserved within the basal layers of Greenland updating gases measurement techniques suitable for analysing silty ice. We analysed the gas composition (N2, O2, Ar, CO2, CH4, N2O) of samples retrieved from the basal ice and underneath sediments of Camp Century (new data set) and from the basal ice of GRIP (new data set for N2O and improving previous resolution for other gases species). Our results show a large accumulation of greenhouse gases (up to 12% and 3% of CO2 and CH4) associated with O2 depletion (down to 5%), a relative accumulation of Ar (up to 1.5%) and a total gas loss (down to 5mL of gas per kg) within the last meters of ice above the bedrock. As the greenhouse gases probably have a biological origin, we performed genomic sequencing at different locations of the silty sequence to determine whether the genes required for potential biogeochemical cycling were present and whether they differed with depth. Differences are reported between Camp Century and GRIP.  In the light of these new measurements, we will discuss the processes at play in the silty layers.

 

[1] Christ et al., 2021, Proc. Nat. Acad. Sci. [2] Souchez et al., 2006, Geophys. Res. Lett., 33, L24503.

[3] Verbeke et al., 2002, Annals of Glaciology 35, 231-236. [4] Goossens et al., 2016, The Cryosphere, 10(2), 553-567.

How to cite: Ardoin, L., Tison, J.-L., Bierman, P., Blard, P.-H., Dahl-Jensen, D., Gkinis, V., Larose, C., Steffensen, J. P., Rockmann, T., and Fripiat, F.: Origin of silty basal ice in Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3852, https://doi.org/10.5194/egusphere-egu24-3852, 2024.

EGU24-4497 | Orals | CL1.2.4 | Highlight

Plio-Pleistocene ice cores from the Allan Hills Blue Ice Area, Antarctica: recent results and prospects for future work 

Ed Brook and the Center for Oldest Ice Exploration Allan Hills Research Team

The Center for Oldest Ice Exploration (COLDEX) is a US initiative to search for climate records covering the last 5 million years, including cores from blue ice regions where very old ice has been identified. Ice cores from the Allan Hills,  Antarctica contain discontinuous ice sections that date to as old as 4.6 Ma, and numerous samples with ages between 1 and 3 Ma, all dated with the 40Aratm technique. These samples provide constraints on a variety of past environmental variables, including greenhouse gases (Marks Peterson et al., this meeting) and mean ocean and Antarctic surface temperature (Shackleton et al., this meeting), and create opportunities to explore other properties of climate and the environment beyond the 800 ka limit of the existing ice core record (for example, Hudak et al., this meeting).

The Allan Hills cores and glaciological setting are unusual. Ice flow, likely from a relatively local depositional area, traps old ice at shallow depths near the ice margin, albeit in a poorly understood manner.  In most locations drilled so far, ice younger than 1 Ma is underlain by a relatively thin layer (20-40 m) of older material. In the “Cul-de-sac” region, ice older than 1 Ma is found within 15 m of the surface

Dating Allan Hills cores clearly shows age reversals indicative of folding. Deformation of dust and tephra bands at the surface, and deformation of bubbles at depth, also indicate complex ice flow. Dust mass concentrations are lower than expected for glacial periods, with anomalously high values at greater depth indicating incorporation of basal sediment. δ15N of N2 measurements indicate a relatively shallow firn column in the original deposition site.  Three-dimensional mapping of electrical conductivity and isotopic measurements in large, 24-cm diameter cores clearly shows inclined layers and folding. Phase-sensitive radar is being used to measure spatial variations in vertical velocity (with some repeat measurements completed), and polarimetry profiles.   Temperature measurements in Allan Hills boreholes suggest heating related to shear between the old ice and shallower layers.

Results from sections that date to 500-800 ka reproduce the long-term mean values of various parameters (CO2, CH4, δ18Oatm, MOT, δ18Oice) but not the entire glacial-interglacial range.  Small-scale folding, diffusion and hiatuses are all possible explanations for the muted variability. Detailed studies of large diameter cores are currently investigating these possibilities.

So far, five cores (ALHIC1502, 1503, 1901, 1902 and 2201) sample ice older than 1 million years. ALHIC1902 contains the oldest ice dated, at 4.6 Ma. Drilling in the 23/24 field season partly completed a 24-cm diameter core (2302) at the 1902 site, intended to provide large volumes of very old ice, A 90 m core in the Cul de Sac, (2301), at the location where old ice was found near the surface, was also completed.

COLDEX drilling will continue in the Allan Hills in 2024-25 and possibly in later seasons. Future work may also include an ~1250 m ice core in a region where modelling predicts continuous stratigraphy for ~1 Ma.

How to cite: Brook, E. and the Center for Oldest Ice Exploration Allan Hills Research Team: Plio-Pleistocene ice cores from the Allan Hills Blue Ice Area, Antarctica: recent results and prospects for future work, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4497, https://doi.org/10.5194/egusphere-egu24-4497, 2024.

Diffusion limits the survival of climate signals on ice-core isotope records. Diffusive smoothing acts not only on annual signals near the surface, but also on millennial signals in deep ice where they shorten to decimetres or centimetres. Short-circuiting of the slow diffusion in crystal grains by fast diffusion along liquid veins can explain the accelerated or “excess” diffusion found on some isotope records. But direct experimental evidence is lacking whether the short-circuiting mechanism really operates as theorised; current theories of it also neglect diffusion along grain boundaries. The pattern of isotope concentrations across crystal grains caused by short-circuiting provides a testable prediction of the mechanism. Here, we extend the theory for grain boundaries and calculate the pattern for different assumptions of grain-boundary diffusivity and thickness, and different temperature, vein and grain sizes, and vein-water flow velocity. Two isotopic patterns prevail in ice of millimetre grain sizes: (i) an axisymmetric pattern with isotopic excursions centred on triple junctions in the case of thin, low-diffusivity grain boundaries; (ii) a three-spoke pattern of excursions around triple junctions in the case of thick, highly-diffusive grain boundaries. Because these signatures have excursions potentially reaching several per mil and as thick as 10–25% of the mean grain radius, they should be detectable by LA-ICP-MS mapping on ice affected by excess diffusion. We further examine how the predicted patterns vary with depth (through a wavelength of the bulk isotopic signal) to formulate the procedure of testing for the occurrence of short-circuiting, such as applicable to ice-core samples from the EPICA Dome C and Beyond EPICA Oldest Ice projects. Because our model accounts for grain boundaries and veins, it also characterises the bulk-ice isotopic diffusivity more comprehensively than past studies.

How to cite: Ng, F. S. L.: Diffusive smoothing of isotopic signals in ice cores: the grain-scale signature of excess diffusion as a testable prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5175, https://doi.org/10.5194/egusphere-egu24-5175, 2024.

EGU24-5333 | ECS | Posters on site | CL1.2.4 | Highlight

Reconciling ice core CO2 and land-use change following New World-Old World contact 

Amy King, Thomas Bauska, Edward Brook, Michael Kalk, Eric Wolff, Ivo Strawson, Rachael Rhodes, Christoph Nehrbass-Ahles, and Matthew Osman

Ice core records of carbon dioxide (CO2) over the last 2000 years are critical to our understanding of global carbon cycle dynamics on centennial and multidecadal timescales. They also provide context for the unprecedented anthropogenic rise in atmospheric CO2. Yet for some time intervals throughout the period, the true atmospheric history of CO2 remains uncertain. One such example is the decrease in atmospheric CO2 after 1550 CE, for which the timing and magnitude is debated. To resolve this case, we measure CO2 and methane (CH4) in the new Skytrain Ice Rise ice core from 1450 to 1700 CE, presented alongside firn smoothing analysis and land carbon modelling. Our results suggest that a sudden decrease in ice core CO2 around 1610 CE in one widely used record is most likely an artefact of a small number of anomalously low values. Instead, we observe a more gradual decrease in CO2, with our analysis suggesting 0.5 ppm per decade between 1516 and 1670 CE. The resulting inferred land carbon sink of 2.6 PgC per decade agrees with modelled scenarios of large-scale reorganization of land use in the Americas following New World-Old World contact, for which a larger and more rapid CO2 decrease is incompatible.

How to cite: King, A., Bauska, T., Brook, E., Kalk, M., Wolff, E., Strawson, I., Rhodes, R., Nehrbass-Ahles, C., and Osman, M.: Reconciling ice core CO2 and land-use change following New World-Old World contact, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5333, https://doi.org/10.5194/egusphere-egu24-5333, 2024.

Innovative enhancements to the bioanalytical Orbitrap mass spectrometer now allow quantification of stable isotope ratios of soluble species. The novel technique, known as Orbitrap-iso, enables deeper-than-ever isotopic analysis of ice core oxyanions, including nitrate and sulfate.

On paper, the Orbitrap-iso methodology presents a compelling alternative to the established Isotope Ratio Mass Spectrometry (IRMS) approach for quantification of isotope ratios of ice core oxyanions. Unlike IRMS, which necessitates the conversion of nitrate samples into gases (N2, O2) for analysis, Orbitrap-iso directly measures isotopologue ratios on intact ions in liquid solution. This streamlined process significantly simplifies sample preparation and enables additional quantification of enrichments in multiply-substituted (clumped) isotopologues in ice core oxyanions. These enrichments can offer valuable insights into the historical oxidative environment of Earth's atmosphere.

Moreover, Orbitrap-iso boasts the capability to deliver simultaneous measurements of multiple isotopologue ratios from minuscule sample quantities, as low as nanomoles. This requirement represents a monumental reduction in sample size compared to IRMS, empowering the extraction of higher temporal resolution records from ice cores.

Despite these notable advantages of the Orbitrap-iso method, questions linger regarding its accuracy, reproducibility, and precision relative to the long-established industry standard, IRMS. In an effort to validate the quality of Orbitrap-iso isotopologue ratio measurements, our study rigorously compares the analysis of identical ice core nitrate samples using both systems, aiming to establish a ground truth for the Orbitrap-iso methodology.

How to cite: Saville, J., Gautier, E., Savarino, J., and Lamothe, A.: Ground-truthing the performance of Orbitrap-iso for ice core nitrate stable isotope ratios by comparison to traditional Isotope Ratio Mass Spectrometer (IRMS) measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5349, https://doi.org/10.5194/egusphere-egu24-5349, 2024.

EGU24-6585 | Posters on site | CL1.2.4

Isotopic and elemental ratios in the open and closed porosity for two Antarctic firn cores (D47 and Little Dome C) of very different surface characteristics.  

Amaelle Landais, Romilly Harris Stuart, Anais Orsi, Roxanne Jacob, Gregory Teste, Frédéric Prié, Louisa Brückner, Patricia Martinerie, Witrant Emmanuel, Fourré Elise, Capron Emilie, Baggenstos Daniel, Fischer Hubertus, and Schmitt Jochen

Understanding the processes during gas trapping in ice is essential to accurately interpret the gas records in ice cores. As a consequence, it is very desirable to have firn core and firn air sampling campaigns associated with deep ice coring. We know that elemental fractionation occurs during bubble close-off, hence largely affecting the δO2/N2 measurements further used to date the ice cores on orbital timescales. A recent study also suggested that this elemental fractionation can be linked to surface characteristics (i.e. temperature and / or accumulation rate). 

The aim of this study is to investigate the elemental and isotopic fractionation of N2 and O2 during bubbles close-off at two sites of very different characteristics (D47 located at the edge of the East Antarctic plateau with high temperature and accumulation rate and Little Dome C at the center of the East Antarctic plateau with low accumulation and accumulation rate). For this study, we did measurements both in the open and closed porosity of the firn in the lock-in zone. The D47 lock-in zone extends over nearly 20 m and, over these 20 m,  strong signals of increasing δO2/N2 (+ 7 permil) and decreasing δ15N (-0.05 permil) are observed with increasing depths. At Little Dome C, the site of the Beyond EPICA deep ice core, the lock-in depth is much thinner (a few meters thick only) and fractionation much smaller. We discuss how these signals relate to the signals measured in the closed porosity in both sites and present some perspectives for the interpretation of the gas records in the deep ice cores.   

How to cite: Landais, A., Harris Stuart, R., Orsi, A., Jacob, R., Teste, G., Prié, F., Brückner, L., Martinerie, P., Emmanuel, W., Elise, F., Emilie, C., Daniel, B., Hubertus, F., and Jochen, S.: Isotopic and elemental ratios in the open and closed porosity for two Antarctic firn cores (D47 and Little Dome C) of very different surface characteristics. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6585, https://doi.org/10.5194/egusphere-egu24-6585, 2024.

EGU24-6772 | ECS | Orals | CL1.2.4

Englacial shearing in the context of old ice preservation 

John-Morgan Manos, Dominik Gräff, and Brad Lipovsky

Old ice (>1 million years) has been discovered in blue ice areas in the Allan Hills, Antarctica, and ice cores have been retrieved from shallow boreholes less than 200 m depth (Higgins et al., 2015 and Yan et al., 2019). However, it remains unclear what ice properties, mechanisms, and conditions allow for the preservation of old ice in blue ice areas. A high-resolution distributed temperature sensing (DTS) deployment was carried out in the COLDEX 22/23 and 23/24 field seasons. A temperature sensitive fiber optic cable was deployed into five air-filled boreholes, one for two consecutive seasons. Temperature was recorded every ~25 cm along the fiber length at a temperature resolution of 10 mK. Borehole temperature profiles reveal both the seasonal temperature signal shallow in the ice column and recent climate temperature trends below the seasonal signal due to ground surface temperature diffusion. Discrete temperature anomalies, unrelated to ground surface temperature signals, were identified at multiple depths. The temperature anomalies appear to coincide with points of ice crystal c-axis transitions in the ice fabric, suggesting possible shear horizons at transitions between ice layers at these depths. 23/24 field season efforts aim to confirm the presence of transient shear heating events and elucidate the horizontal distribution of shear heating events as they relate to the presence of old ice.

How to cite: Manos, J.-M., Gräff, D., and Lipovsky, B.: Englacial shearing in the context of old ice preservation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6772, https://doi.org/10.5194/egusphere-egu24-6772, 2024.

EGU24-7115 | Orals | CL1.2.4

Variability of concentrations and size distributions of black carbon particles in Northeast Greenland since the Industrial Revolution 

Kumiko Goto-Azuma, Kaori Fukuda, Jun Ogata, Yuki Komuro, Motohiro Hirabayashi, Fumio Nakazawa, Ikumi Oyabu, Kyotaro Kitamura, Shuji Fujita, Nobuhiro Moteki, Tatsuhiro Mori, Sho Ohata, Yutaka Kondo, Makoto Koike, Naga Oshima, Ayaka Yonekura, Yoshimi Ogawa-Tsukagawa, Kenji Kawamura, Teruo Aoki, and Naoyuki Kurita and the University of Copenhagen team

Black carbon (BC) is a crucial component among light-absorbing aerosols, significantly impacting Earth's radiation budget. BC in the atmosphere absorbs sunlight and leads to atmospheric heating, while BC deposited on snow and ice surfaces reduces albedo, accelerating snowmelt. Additionally, BC can serve as cloud condensation nuclei and ice nucleating particles. Understanding the historical role of BC in pristine environments, particularly in the Arctic, where climate and environmental changes have been pronounced, is vital. However, data on preindustrial BC levels remain sparse, with limited observations unaffected by anthropogenic sources. Ice cores offer valuable proxy records of BC concentrations and size distributions since the preindustrial era.

In this study, we analyzed an ice core retrieved from the EastGRIP site in Northeast Greenland, reaching a depth of 133 meters, using a Continuous Flow Analysis (CFA) system at the National Institute of Polar Research. The CFA system facilitated high-resolution data collection on BC, stable isotopes of water, microparticles, and eight elements (Na, Mg, Al, Si, S, K, Ca, Fe). For BC analysis, we employed a recently developed Wide-range (WR) SP2 (Single Particle Soot Photometer) capable of detecting BC particles in the size range of 70 to 4000 nm. The combination of WR-SP2 and a high-efficiency nebulizer enabled precise measurements of BC concentrations and size distributions. The core was dated through annual layer counting primarily using Na concentrations, supplemented by microparticle and Ca concentrations. As reference horizons, we used volcanic sulfate peaks and tritium peaks from nuclear bomb testing. We present the EastGRIP BC record spanning the past 350 years and compare it with previously obtained BC records from Greenland.

Our findings reveal that both the number and mass concentrations of BC at EastGRIP began to increase around 1860, driven by the influx of anthropogenic BC. These concentrations peaked around 1920 and have since declined. While this temporal trend aligns with other Greenland sites, it differs slightly from that observed in southern Greenland, potentially reflecting variations in emission source contributions between northern and southern Greenland. Notably, anthropogenic BC at EastGRIP exhibited larger sizes than biomass-burning BC, consistent with previous findings for the SIGMA-D site in Northwest Greenland. In the preindustrial period, BC concentrations showed their peak during summer. However, the inflow of anthropogenic BC has shifted the peak season from summer to winter/early spring. Unlike SIGMA-D, the BC peak season did not revert to summer in the 1990s.

Our accurate, high temporal-resolution data on BC concentrations and sizes offer crucial insights into understanding BC sources, transport pathways, and deposition processes. Furthermore, this new dataset serves to constrain and validate aerosol and climate models, ultimately improving projections for future climate and environmental conditions.

How to cite: Goto-Azuma, K., Fukuda, K., Ogata, J., Komuro, Y., Hirabayashi, M., Nakazawa, F., Oyabu, I., Kitamura, K., Fujita, S., Moteki, N., Mori, T., Ohata, S., Kondo, Y., Koike, M., Oshima, N., Yonekura, A., Ogawa-Tsukagawa, Y., Kawamura, K., Aoki, T., and Kurita, N. and the University of Copenhagen team: Variability of concentrations and size distributions of black carbon particles in Northeast Greenland since the Industrial Revolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7115, https://doi.org/10.5194/egusphere-egu24-7115, 2024.

EGU24-8074 | Posters on site | CL1.2.4

Can the Electrospray Orbitrap be a new frontier for the stable isotope analysis of oxyanions in ice cores? A statistical study of its performances 

Joel Savarino, Jack Saville, Elsa Gautier, Nils Kuhlbusch, and Dieter Juchelka

Recently, the Orbitrap Exploris instrument, a mass spectrometer designed for molecular identification and classification, has been diverted from its original purpose and transformed into a new tool for quantifying the stable isotope ratios of water-soluble compounds such as nitrates, sulfates or phosphates. At first glance, this new Orbitrap IRMS system is very attractive because it requires 10 to 100 times less ice than current standard procedures, works directly with liquid solutions, quantifies isotope ratios directly on the molecule of interest, and provides a broader range of isotope ratios by moving from the elemental isotope ratio paradigm to that of molecular isotope ratios and thus challenge the regular isotope ratio mass spectrometers (IRMS or ICPMS). Moreover, by leaving the chemical bonds of the molecules of interest intact contrary to IRMS or ICPMS, the Orbitrap technology provides access to clumped isotopes, i.e. doubly substituted isotopic substances, thereby enriching our knowledge of matter. Extending the range of molecular isotope ratios opens up exciting new prospects, particularly for unravelling the mechanisms by which compounds are formed before being incorporated in ice. Such a radical change in the way isotope ratios are measured inevitably raises the question of the real capabilities of this new instrument. With a deeper look into statistics, can the Orbitrap-IRMS challenge the standard IRMS/ICPMS precision for analyzing soluble species? Does its performance live up to expectations? Preliminary results show that the Allan variance for a large variety of molecular isotope ratios of nitrate and sulfate are in the range of one per mil precision, including some of the clumped isotope ratios. However, the bootstrapping approach aimed at reducing acquisition time and thus the drift associated with the instrument appears to be ineffective in improving the Allan variance, indicating a possible limitation of sampling randomization, probably during the electrospray ionization (ESI) process. Other statistics, tests and performances are still in progress and will also be presented.

How to cite: Savarino, J., Saville, J., Gautier, E., Kuhlbusch, N., and Juchelka, D.: Can the Electrospray Orbitrap be a new frontier for the stable isotope analysis of oxyanions in ice cores? A statistical study of its performances, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8074, https://doi.org/10.5194/egusphere-egu24-8074, 2024.

EGU24-8294 | Posters on site | CL1.2.4

Past local summer temperature revealed by the total air content record from the Antarctic EPICA Dome C ice core 

Emilie Capron, Dominique Raynaud, Quizhen Yin, Zhipeng Wu, Frédéric Parrenin, André Berger, Vladimir Lipenkov, and Héloïse Guilluy

Seasonal temperature reconstructions from ice cores are missing over glacial-interglacial timescales, preventing a good understanding of the driving factors of Antarctic past climate changes. Here we present a new total air content (TAC) record from the Antarctic EPICA Dome C (EDC) ice core covering the last 800 thousand of years (ka).

We show that the TAC record is highly correlated with the mean insolation over the local astronomical half-year summer. Benefiting from new climate transient simulations from the Earth system model of intermediate complexity LOVECLIM covering the past 440 ka, we evidence that the EDC TAC record is correlated with the simulated local summer temperature changes. Hence, our new results suggest that the EDC TAC record could potentially be used as a proxy for local summer temperature changes. We present also preliminary results exploring this link between TAC and past summer local surface temperature at other ice core sites in Antarctica and in Greenland.

Finally, our simulations show that local summer insolation is the primary driver of Antarctic summer surface temperature variations while changes in atmospheric greenhouse gas concentrations and northern hemisphere ice sheet configurations play a more important role on Antarctic annual surface temperature changes.

How to cite: Capron, E., Raynaud, D., Yin, Q., Wu, Z., Parrenin, F., Berger, A., Lipenkov, V., and Guilluy, H.: Past local summer temperature revealed by the total air content record from the Antarctic EPICA Dome C ice core, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8294, https://doi.org/10.5194/egusphere-egu24-8294, 2024.

EGU24-8535 | Orals | CL1.2.4

Influence of the solar cycle and stratospheric intrusions to the tritium variation of continental ice layers (Colle Gnifetti, European Alps and EGRIP camp, Greenland) 

László Palcsu, Elemér László, Mihály Veres, Gergely Surányi, Danny Vargas, and Marjan Temovski

Examining continental ice layers accumulated before the nuclear era, when the artificial tritium component can be excluded, enables us to better understand the natural variation of cosmogenic tritium (3H). The extremely sensitive 3He-ingrowth method of 3H analysis allows us to determine low level tritium activities with high accuracy. Here we provide a detailed tritium profile of two shallow ice cores drilled in the European Alps and Greenland.

A sensitive tritium profile of the top 33.7 m of the ice accumulation at Colle Gnifetti (Swiss-Italian Alps) is provided. The tritium concentrations of annual ice layers before 1953 vary between 0.050 and 0.145 TU with uncertainties of 0.0019 to 0.0048 TU. The tritium values reconstructed for the time of accumulation are varying between 4 and 10 TU. The long-term pattern of tritium in the ice (mainly before 1940) is in anti-correlation with the sunspot numbers. As the ice is not contaminated with artificial tritium, this change can be strongly attributed to the 11-year cycle of solar magnetic activity. This confirms the existing link between the Solar cycle and the cosmogenic tritium of precipitation [1].

On the contrary, in Greenland at the EGRIP camp, the signal of the solar cycle is hardly visible. The natural level of tritium at around 20 TU is disturbed by large spikes (>400 TU). These spikes seem to be randomly distributed in time. There are annual layers which are unaffected. The reason of the high tritium concentration might be the stratospheric moisture input as shown by Fourré et al. (2018) [2]. Stratospheric moisture can be also identified by its 17O-excess pattern. Here we provide the correlation of tritium and 17O, as a hint of the origin of excess tritium. On the other hand, the evaluation of the first results shows that the strength of the stratospheric intrusions qualified by tritium amount seems to be weakening over the last 100 years.

[1] Palcsu, L., Morgenstern, U., Sültenfuss, J., Koltai, G., László, E., Temovski, M., Major, Z., Nagy, J.T., Papp, L., Varlam, C., Faurescu, I., Túri, M., Rinyu, L., Czuppon, G., Bottyán, E., Jull, A.J.T. Modulation of Cosmogenic Tritium in Meteoric Precipitation by the 11-year Cycle of Solar Magnetic Field Activity, Scientific Reports 8 (2018) 12813.

[2] Fourré, E., Landais, A., Cauquoin, A., Jean-Baptiste, P., Lipenkov, V., Petit J.-R. Tritium Records to Trace Stratospheric Moisture Inputs in Antarctica. Journal of Geophysical Research: Atmospheres 123 (2018), 3009-3018.

How to cite: Palcsu, L., László, E., Veres, M., Surányi, G., Vargas, D., and Temovski, M.: Influence of the solar cycle and stratospheric intrusions to the tritium variation of continental ice layers (Colle Gnifetti, European Alps and EGRIP camp, Greenland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8535, https://doi.org/10.5194/egusphere-egu24-8535, 2024.

EGU24-9440 | ECS | Posters on site | CL1.2.4

Recapturing sublimated ice core gas samples & implementing δ15N – N2 mass spectrometry measurements 

Henrique Traeger, Florian Krauss, Markus Grimmer, Jochen Schmitt, Remo Walther, Samuel Marending, Christoph Reinhard, and Hubertus Fischer

Ice cores represent invaluable tools for palaeoclimatic reconstructions. Of particular interest is the gas trapped in air bubbles and clathrates within the ice. It serves as a direct record of the changes to atmospheric composition over the last several 100kyrs. Recently, the University of Bern established joint high precision greenhouse gas (GHG) analyses (CO2, CH4 & N2O concentration, as well as δ13C – CO2) on small ice core samples (15g) thanks to sublimation extraction and multi-beam quantum cascade laser spectrometry.

Although gas bubbles form a direct record of past atmosphere, they are not an unbiased record of past atmosphere. Several processes take place prior and during bubble formation which fractionate gas concentration and gas isotopes, requiring several corrections to be applied (especially for δ13C – CO2 data). These corrections can be achieved by studying the isotope ratios of noble gases and N2. However, this requires a mass spectrometry analysis which would normally call for the use of additional samples. This is problematic for two reasons: first, the corrections applied are most accurate when comparing the various isotope ratios of the same gas sample. Even ice in close proximity is subject to small scale disruptions within the ice and can skew the results. Second, near the bottom of ice cores, glacial thinning – compression of the ice caused by the overlying material – causes thousands of years of ice to be compacted in only one metre, making two different samples, even if adjacent, incomparable.

Hence, the objective of this study is to reuse gas samples which have already undergone laser- spectrometric GHG analysis to implement δ15N – N2 & δ40Ar analysis. We outline the development and building of an apparatus which reuses the previously extracted and analysed air and captures it for mass spectrometry. Sample recapture is achieved using a helium cryostat to cool dip tubes down to approximately 10K. When connected, the gas samples are drawn from the laser spectrometer into said tubes, where they are cryogenically trapped. To avoid interferences from other gases, the samples go through a liquid nitrogen trap to remove the already measured CO2 and N2O. The sample tubes are then disconnected, warmed up to room temperature and brought to an isotope-ratio mass spectrometer for major gas isotope analysis.

Despite significant fractionation of the isotopic composition of major gas compounds (N2, O2, Ar) during the recapture process, the developed method achieves its initial objectives, with a >99% recapture efficiency. It features a δ15N – N2 reproducibility of standard gas measurements of ∼ 10 permeg and an offset of 0.1‰ and ∼ 30 permeg and 0.2‰ for δ40Ar. With this reproducibility, sufficiently precise corrections of the gravitational enrichment of isotopes in the firn column are possible, however temperature reconstructions using thermodiffusion thermometry are not yet possible. Further improvements are thought to be possible to reduce the signal to noise ratio, as well as reducing the offset.

How to cite: Traeger, H., Krauss, F., Grimmer, M., Schmitt, J., Walther, R., Marending, S., Reinhard, C., and Fischer, H.: Recapturing sublimated ice core gas samples & implementing δ15N – N2 mass spectrometry measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9440, https://doi.org/10.5194/egusphere-egu24-9440, 2024.

EGU24-9515 | ECS | Orals | CL1.2.4

Air clathrate hydrates of the Antarctic EPICA Dronning Maud Land ice core 

Florian Painer, Ilka Weikusat, Martyn Drury, and Sepp Kipfstuhl

Polar ice cores are a unique climate archive as they provide the most direct record of past atmospheric gas compositions. In the deeper part of polar ice sheets, most of the ancient air molecules are stored in the crystal lattice of clathrate hydrates (air hydrates). Continuous records of air hydrate number concentration, mean size and shape (geometric properties) exist for the Vostok and Dome Fuji ice cores in Antarctica and the GRIP ice core in Greenland. It was found that the geometric properties correlate with past climatic changes, but also evolve with depth due to physicochemical processes within the ice sheet.

The EPICA Dronning Maud Land (EDML) ice core is located on an ice divide in the Atlantic sector of East Antarctica which allows for a comparison to Greenland ice cores. Furthermore, it differs from other Antarctic deep ice cores by a higher accumulation rate and higher annual mean temperatures on site. This makes it possible to analyze air hydrates with a higher temporal resolution (compared to the Dome Fuji and Vostok ice cores). These factors make the EDML ice core interesting for studying air hydrates.

We use digital image analysis on ice thick section microphotographs to create a high-resolution record of air hydrate geometric properties below the bubble-hydrate transition zone. The image acquisition was done in the field, within a few days after the sample was drilled, in order to record information of the material before relaxation. Using traditional image analysis algorithms, we can confirm the correlation between climate and air hydrate geometrical properties. In addition, we examine the air hydrate spatial distribution and evolution via depth. Digital object segmentation and object analysis offer many advantages, such as fast and efficient analysis, improved statistical data, higher spatial resolution, over the traditionally used manual methods. We are excited to contribute to the future analysis of air hydrates in polar ice cores.

How to cite: Painer, F., Weikusat, I., Drury, M., and Kipfstuhl, S.: Air clathrate hydrates of the Antarctic EPICA Dronning Maud Land ice core, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9515, https://doi.org/10.5194/egusphere-egu24-9515, 2024.

EGU24-9596 | ECS | Posters on site | CL1.2.4

Characterising dust particles in the RECAP ice core with a multi-method approach to investigate abrupt climate changes 

Nicolas Stoll, Piers Larkman, David Clases, Raquel Gonzalez de Vega, Elena Di Stefano, Barbara Delmonte, Carlo Barbante, and Pascal Bohleber

Ice cores can supply high-resolution insights into abrupt changes within the climate system. The RECAP ice core from the Renland ice cap, East Greenland, contains a substantial variety in dust particle size throughout its record, reaching back to the Eemian. Changes in dust particle sizes have been shown to reflect smaller ice cap extent during interglacial periods. Thus, local dust sources are only periodically available and can be characterised by large dust particles. For abrupt changes during the last glacial period, it is necessary to disentangle the potential imprint of dust sources and the role of snow accumulation. To better understand dust chemistry and size changes at high resolution, we apply several analytical methods in an ongoing investigation: Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) 2D imaging, coulter counter (CC), time-of-flight single particle analysis (SP ICP-TOFMS), and Low- Background Instrumental Neutron Activation Analysis (LB-INAA). We show that high-resolution (10-40 µm) 2D chemical images, focusing on Na, Al, Mg, and Fe, reveal the clustering of particles in the microstructure and a species-dependent preferred localisation. Subsequent measurements, taken where possible on the same samples provide new insoluble particle size and concentration data (CC) and further in-depth elemental characterisation of the dust particles (LB-INAA). Furthermore, first results from SP analyses display their potential for ice core research regarding largely unexplored areas, such as the characterisation of rare earth elements of dust deposited in Greenland. The expertise and insight on high-resolution dust chemistry and size gained during this multi-method approach on ice with partly highly thinned annual layers will eventually be crucial for interpreting the dust signal stored in future Antarctic ice cores reaching back up to 1.5 Myr.

How to cite: Stoll, N., Larkman, P., Clases, D., Gonzalez de Vega, R., Di Stefano, E., Delmonte, B., Barbante, C., and Bohleber, P.: Characterising dust particles in the RECAP ice core with a multi-method approach to investigate abrupt climate changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9596, https://doi.org/10.5194/egusphere-egu24-9596, 2024.

EGU24-9695 | ECS | Posters on site | CL1.2.4

36Cl/10Be as a dating tool for old ice 

Niklas Kappelt, Eric Wolff, Marcus Christl, Christof Vockenhuber, and Raimund Muscheler

The 36Cl/10Be ratio has the potential to be a dating tool for old ice, as it decays with a combined half-life of  years and is thought to be independent of production changes, which affect the individual radionuclide concentrations in ice cores. However, when EDC samples with various ages between the Holocene and 887 kyr BP were analysed, the 36Cl/10Be ratio was found to vary significantly between samples instead of decaying smoothly over time. Due to the different physical and chemical properties of 36Cl and 10Be, different sensitivities to changes in climatic parameters, such as tropopause pressure and precipitation, are potentially the cause of the observed variability. Additionally, chlorine can be lost at low accumulation sites, such as EDC, as it can turn into hydrogen chloride and gas out from the firn. We present new measurements of the 36Cl/10Be ratio from the Skytrain ice core, which should be unaffected by chlorine loss, due to the higher accumulation rate at its drilling site. The measurement series extends below the dated sections of the ice core to test the decay dating and help extend the Skytrain age scale. To analyse differences in transport and deposition between radionuclides, the 36Cl/10Be ratio will also be determined with annual resolution in samples from 1982 – 2013 and compared to several climate parameters of the NOAA/CIRES/DOE 20th century reanalysis (V3) dataset. However, the data of this project are not yet available.

How to cite: Kappelt, N., Wolff, E., Christl, M., Vockenhuber, C., and Muscheler, R.: 36Cl/10Be as a dating tool for old ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9695, https://doi.org/10.5194/egusphere-egu24-9695, 2024.

EGU24-9894 | ECS | Orals | CL1.2.4

Climate controls on deuterium excess in Antarctic precipitation - insights from an isotope-enabled atmospheric GCM ECHAM6 

Qinggang Gao, Louise C. Sime, Alison J. McLaren, Thomas J. Bracegirdle, Emilie Capron, Rachael H. Rhodes, Hans Christian Steen-Larsen, Xiaoxu Shi, and Martin Werner

We present new work that improves our understanding of the controls on Antarctic precipitation and ice cores. This is critical for gaining insights into polar changes. The work relies on our implementation of innovative water tracing diagnostics in an atmospheric general circulation model. These tracers provide new precise information on moisture source locations and properties of Antarctic precipitation - and allow us to evaluate how one should interpret water isotopic profiles of Antarctic ice cores. Heavy precipitation in Antarctica is sourced by longer-range moisture transport: it comes from 2.9° (300 km, averaged over Antarctica) more equatorward (distant) sources compared to the rest of precipitation. Precipitation during negative phases of the Southern Annular Mode (SAM) also comes from more equatorward moisture sources (by 2.4°, averaged over Antarctica) than precipitation during positive SAM phases, likely due to amplified planetary waves during negative SAM phases. Our new, more precise information on moisture source properties also shows that the logarithmic definition of deuterium excess exhibits a stronger correlation with moisture source properties than the classical linear definition of deuterium excess. Results support the conventional practice of interpreting deuterium excess in terms of source sea surface temperature, without concerning source 2 m relative humidity and source 10 m wind speed. We find there is no added value to include δD for the reconstruction of source temperature in addition to deuterium excess, but including deuterium excess does bring some (small) added benefit in reconstructing site temperature in addition to δD. Nevertheless, it is arguable whether one should incorporate deuterium excess considering uncertainties in the transfer function and post-depositional effects on deuterium excess. Our results demonstrate that improving our understanding of the physics underlying supersaturation function could also help constrain the key uncertainties associated with these model results. Overall, our novel water tracing diagnostics enhance our understanding of the controlling factors of Antarctic precipitation and ice cores.

How to cite: Gao, Q., Sime, L. C., McLaren, A. J., Bracegirdle, T. J., Capron, E., Rhodes, R. H., Steen-Larsen, H. C., Shi, X., and Werner, M.: Climate controls on deuterium excess in Antarctic precipitation - insights from an isotope-enabled atmospheric GCM ECHAM6, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9894, https://doi.org/10.5194/egusphere-egu24-9894, 2024.

EGU24-9968 | Orals | CL1.2.4 | Highlight

Is temperate ice a good paleoclimatic archive? Insights from the Adamello temperate ice core (Italian Alps) 

Giovanni Baccolo, Elena Di Stefano, Sandra O. Brugger, Sabine Brütsch, Theo Jenk, Anja Eichler, Barbara Delmonte, Valter Maggi, and Margit Schwikowski

Glaciers are well known for providing valuable climatice and environmental information which are made available through the retrieval of ice cores. Not all glaciers are equal in this respect, however. The best sites to drill ice cores for paleoclimatic purposes are the cold portions of accumulation basins. The term cold, when referred to ice, indicates ice whose temperature is constantly below the pressure melting point. The importance of cold sites for ice core science is related to the fact that under cold conditions, the stratigraphic signals used for paleoclimatic reconstructions are best preserved because of the absence of meltwater.

Because of climate change, cold portions of mountain glaciers are rapidly changing. The rise of atmospheric temperature is impacting the thermal properties of ice and firn, leading to their warming. As a consequence of this, many cold accumulation basins of high-altitude glaciers are turning to temperate and their mass balances are approaching negative values. This is posing issues on the ability of glaciers to preserve climatic and environmental signals. This is related to two distinct processes. At first, temperate ice, by definition contains a fraction of liquid water which can interfere with the preservation of chemical and physical signals. Secondarily, negative mass balances related to increased melt rates, imply the loss of upper ice layers, obliterating the most recent stratigraphic signals normally used for calibration with instrumental data.

The possibility to retrieve reliable paleoclimatic records from mountain glaciers in the future, is thus questionable. This will only be possible if the ice core science community develops new methods and competencies to extract information from temperate ice addressing meltwater disturbances. To this aim, a 223 m long ice core was drilled in 2021 at the Adamello glacier, in the Italian Alps. At the drilling site (3100 m a.s.l.) the glacier has a negative mass balance and a temperate regime. Thus, the site is ideal to test to what extent temperate ice can be used as a paleoclimatic archive.

To this aim, a set of paleoclimatic proxies has been investigated in the upper part of the ice core. We present here preliminary results. They show that while most of the analytes are significantly affected by meltwater percolation and regelation, some of them, in particular the less soluble ones, still exhibit a detectable seasonality. This has allowed to develop a chronology, estimate the age of surface ice and identify what proxies are best preserved in temperate ice.

How to cite: Baccolo, G., Di Stefano, E., Brugger, S. O., Brütsch, S., Jenk, T., Eichler, A., Delmonte, B., Maggi, V., and Schwikowski, M.: Is temperate ice a good paleoclimatic archive? Insights from the Adamello temperate ice core (Italian Alps), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9968, https://doi.org/10.5194/egusphere-egu24-9968, 2024.

EGU24-10139 | ECS | Posters on site | CL1.2.4

Investigating deconvolution techniques for deep ice core water isotope profile reconstruction 

Fyntan Shaw, Andrew M. Dolman, and Thomas Laepple

Deconvolution has been frequently applied to measured water isotope records, enabling reconstructions of the timeseries before diffusion. The most commonly used method, Wiener deconvolution, aims to optimise the frequencies that are restored while minimising the amplification of the measurement noise, which dominates the high frequency variability in deep ice cores. We investigate the effectiveness of Wiener deconvolution, along with modified approaches, at recovering the original climate signal, with a focus on deep, old ice. We use both real data and surrogate timeseries and apply our methods to the bottom of the Dome C d18O record, with the aim of retrieving millennial timescale variability.

How to cite: Shaw, F., Dolman, A. M., and Laepple, T.: Investigating deconvolution techniques for deep ice core water isotope profile reconstruction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10139, https://doi.org/10.5194/egusphere-egu24-10139, 2024.

EGU24-10519 | ECS | Orals | CL1.2.4

Local climate influences δO2/N2 variability in ice core records 

Romilly Harris Stuart, Amaëlle Landais, Laurent Arnaud, Christo Buizert, Emilie Capron, Marie Dumont, Quentin Libois, Robert Mulvaney, Anaïs Orsi, Ghislain Picard, Frédéric Prié, Jeffrey Severinghaus, Barbara Stenni, and Patricia Martinerie

Orbital dating using δO2/N2 records is a powerful tool for constructing ice core chronologies in deep ice cores due a widely observed anti-correlation with summer solstice insolation (SSI). While understood to be linked to near-surface snow metamorphism, the physical mechanisms driving this process remain poorly constrained and the role of local accumulation rate and temperature have been scarcely considered. We primarily present the results of our new study which uses a compilation of records from 14 ice cores to show a significant dependence of mean δO2/N2 on local accumulation rate and temperature. Using EPICA Dome C as a case study, we then show that during rapid climatic changes, an accumulation/temperature signal may be superimposed on top of the SSI signal and therefore should be accounted for when using peak-matching techniques for future dating of deep ice cores, such as the EPICA or Beyond EPICA cores.Further to our study, we include new δO2/N2data measured in shallow, bubbly ice just below close-off from two newly drilled firn cores at sites with distinct close-off conditions; D-47 and Little Dome C (the Beyond EPICA site), which support our findings. Moreover, thanks to parallel firn air pumping campaigns, overlapping data from open and closed porosity at these two sites promise greater insight into the mechanisms driving close-off fractionation.

How to cite: Harris Stuart, R., Landais, A., Arnaud, L., Buizert, C., Capron, E., Dumont, M., Libois, Q., Mulvaney, R., Orsi, A., Picard, G., Prié, F., Severinghaus, J., Stenni, B., and Martinerie, P.: Local climate influences δO2/N2 variability in ice core records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10519, https://doi.org/10.5194/egusphere-egu24-10519, 2024.

EGU24-10772 | Orals | CL1.2.4 | Highlight

Constraining the timing and spatial extent of an early Holocene ungrounding in the Weddell Sea using ice cores: how fast and how far-reaching? 

Thomas Bauska, Amy King, Korina Chapman, Shaun Miller, Christoph Nehrbass-Ahles, Mackenzie Grieman, Xavier Fain, Emilie Capron, Robert Mulvaney, and Eric Wolff

During the Last Glacial Maximum, the Antarctic ice sheet was significantly larger than today, holding an additional 6 to 14 meters sea level equivalent. Although less than 10% of the total glacial-interglacial range in eustatic sea level change, understanding the “when and where” of how Antarctica reconfigures during a deglaciation is crucial to understanding how the ice sheet will behave in the future. Some models show that many areas of the Antarctic ice sheet are inherently unstable during the Last Glacial Maximum and, when forced by increasing temperatures and rising sea level during the last deglaciation, undergo a rapid retreat to their present-day grounding line configurations (if not beyond).  In particular, the Ross and Weddell Sea regions, which are now largely covered by floating ice shelves, were susceptible to this “tipping point” behaviour.  Recently, evidence from the Skytrain Ice Rise ice core (~79°S, 078°W, 784m altitude) using water isotopes and total air content (a proxy for elevation) provided strong evidence that the Weddell Sea underwent such a transition about 8,000 years before present (BP) (Grieman et al., in press).

Here we present new total air content data from the Fletcher Promontory ice core (~78°S, 082°W, 873m altitude) which also lies in the Weddell Sea region about 220 km from Skytrain Ice Rise site, with the fast-flowing Rutford Ice Stream situated in between. The data were measured with a novel, high-accuracy total air content system and span approximately 11,000 to 6,000 years BP with an average resolution of 150 years. The most notable feature is an 8.8 mmol/kg (+/-2.0) increase between 8,000 and 7,000 years BP. This confirms the shift observed in the Skytrain Ice Rise ice core (~6.6 mmol/kg) that has been attributed to a 430 ± 110 m drop in elevation. Using both Skytrain Ice Rise and Fletcher Promontory as the two independently derived elevation histories we will discuss the reliability of total air content as an elevation proxy as well as provide crucial constraints on state-the-art ice sheet model predictions of past “tipping point” behaviour.

Grieman, M., Nehrbass-Ahles, C., Hoffmann, H., Bauska, T. K., King, A. C. F., Mulvaney, R., Rhodes, R. H., Rowell, I. F., Thomas, E. R., and Wolff, E. W.: Abrupt Holocene ice loss due to thinning and ungrounding in the Weddell Sea Embayment, Nature Geoscience, In Press.

How to cite: Bauska, T., King, A., Chapman, K., Miller, S., Nehrbass-Ahles, C., Grieman, M., Fain, X., Capron, E., Mulvaney, R., and Wolff, E.: Constraining the timing and spatial extent of an early Holocene ungrounding in the Weddell Sea using ice cores: how fast and how far-reaching?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10772, https://doi.org/10.5194/egusphere-egu24-10772, 2024.

EGU24-10936 | Posters on site | CL1.2.4

The Air Mass Back-trajectories: A Key Factor in the Interpretation of Isotopic Depositional Processes on the East Antarctic Plateau 

Agnese Petteni, Mathieu Casado, Christophe Leroy-Dos Santos, Barbara Stenni, Giuliano Dreossi, Amaelle Landais, Joel Savarino, Andrea Spolaor, Barbara Delmonte, Silvia Becagli, and Massimo Frezzotti

The isotopic composition (δD and δ18O) of snow precipitation, archived in the Antarctic ice sheet every year, is an important proxy of climatic conditions. This signal is observed to be dependent on several parameters including temperature, altitude and distance from the coast. The well-established correlation between water stable isotopes and local temperature - commonly used in paleoclimate reconstructions - is strongly observed in the earlier dataset of Antarctic surface snow isotopic composition (Masson-Delmotte et al. 2008), and the spatial variability of this relationship across the distinct regions of the continent was investigated to improve the use of this proxy.

Here, we aim to explore the temperature vs water stable isotopes on the East Antarctic Plateau characterized by very low snow accumulation. The surface (a few cm average) and bulk (top 1 m average) snow samples were collected as a part of the East Antarctic International Ice Sheet Traverse (EAIIST) in the summer 2019-2020. Our sampling covers the area from Dumont D'Urville to Dome C and the unexplored area from Dome C towards the South Pole.The linear relationship between surface temperature and isotopic composition is completely lost in the latter part of the traverse. This area is subject to strong post-depositional processes such as wind redistribution and sublimation effect (Windcrust and Megadune sites). For this reason, ahead of evaluating the post-depositional effects able to modify surface snow composition, we decided to investigate a priori the snow depositional conditions and processes, which define the original isotope signal over 600 km on the Antarctic Plateau. While geographical parameters are constant, such as the altitude and the distance from the coast (increasing distance from the Indian Ocean but decreasing distance from the Pacific and Atlantic Ocean), we investigate the origin of the air masses for the different sampling sites, observing significant variations moving towards the Megadunes area. The 10-day back trajectories of the air masses were calculated for each sampling site at a 12-hour resolution, spanning from January 2016 to January 2020, using the FLEXPART - FLEXible PARTicle dispersion model. For each sampling site, we estimated the corresponding annual mean footprint. To assign greater weight to air masses responsible for precipitation on the Antarctic Plateau, those footprints are calculated through a weighted average of back-trajectories using the ERA5 precipitation rate.

The different origins can contribute to distinct isotopic signals, despite similar climatic and geographic factors on the East Antarctic Plateau. This divergence poses a challenge in the determination of the post-depositional processes affecting the isotopic composition of snow and in the reliable use of this proxy in reconstructing past temperatures in the context of Antarctic ice core science.

How to cite: Petteni, A., Casado, M., Leroy-Dos Santos, C., Stenni, B., Dreossi, G., Landais, A., Savarino, J., Spolaor, A., Delmonte, B., Becagli, S., and Frezzotti, M.: The Air Mass Back-trajectories: A Key Factor in the Interpretation of Isotopic Depositional Processes on the East Antarctic Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10936, https://doi.org/10.5194/egusphere-egu24-10936, 2024.

EGU24-10996 | ECS | Orals | CL1.2.4

High obliquity favours centennial-scale variations in the carbon cycle 

Etienne Legrain, Emilie Capron, Laurie Menviel, Axel Wohleber, Frédéric Parrenin, Grégory Teste, Amaëlle Landais, Marie Bouchet, Roberto Grilli, Christoph Nehrbass-Ahles, Lucas Silva, Hubertus Fischer, and Thomas F. Stocker

Antarctic ice cores are a preferred climate archive to study global carbon cycle changes at multi-centennial timescales as they provide the only direct reconstructions of past atmospheric CO2 changes. Here we present a new atmospheric CO2 record from the EPICA Dome C ice core spanning Termination III (TIII) and Marine Isotope Stage 7 (MIS 7) (~260-190 ka). 203 ice samples were measured using a ball mill dry extraction system and gas chromatography at IGE. With a temporal resolution of about 300 years on average, our new record improves by a factor of three the existing CO2 record that had been measured on the Vostok ice core over this time interval. Based on our new record, we identified seven centennial-scale releases of atmospheric CO2, also referred as Carbon Dioxide Jumps (CDJ). Combining these new results with previously published ones, we evidenced that 18 of the 22 CDJs identified over the past 500 thousand years occurred under a context of high obliquity. New simulations performed with the LOVECLIM model, an Earth system model of intermediate complexity, point toward both the continental biosphere and the Southern Ocean as the two main carbon sources during CDJs connected to Heinrich events. Notably, the continental biosphere appears to be the obliquity-dependent CO2 source for these rapid events. For the first time, we demonstrate that the long-term external forcing directly impacts past abrupt atmospheric CO2 variations.

How to cite: Legrain, E., Capron, E., Menviel, L., Wohleber, A., Parrenin, F., Teste, G., Landais, A., Bouchet, M., Grilli, R., Nehrbass-Ahles, C., Silva, L., Fischer, H., and Stocker, T. F.: High obliquity favours centennial-scale variations in the carbon cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10996, https://doi.org/10.5194/egusphere-egu24-10996, 2024.

EGU24-11175 | Posters on site | CL1.2.4

The Adamello Glacier: paleoenvironmental and paleoclimatic variations at subannual resolution 

Clara Mangili, Barbara Delmonte, Roberta Pini, Claudio Artoni, Giovanni Baccolo, Llorenç Cremonesi, Elena Di Stefano, Deborah Fiorini, and Valter Maggi

Paleoclimate and paleoenvironmental stratigraphic reconstructions from temperate glaciers are hindered by surface melting and ice metamorphism, which cause mobilization and concentration of impurities, as well as their interaction through englacial reactions.

Despite meltwater intrusions, other impurities such as pollen grains and other palynomorphs remain to their original depth of deposition thanks to their large grain-size. Temperate glaciers close to vegetated areas, therefore, can include palynomorphs of different types that i) can be reliable annual markers for ice-core dating and, ii) allow reconstructing paleoenvironmental changes through time.

The Adamello Glacier (Central Alps, Italy) is a temperate glacier that extends over ca 14.35 km2 (2020) at elevations ranging between 2560 and 3420 m a.s.l. In the framework of the CLIMADA Project, a 224 m long ice core (ADA 270) was recovered in 2021 from Pian di Neve, the summit plateau at about 3200 m a.s.l. in the accumulation area of the glacier. Preliminary estimates date the surface ice of the glacier to the 1980s while the bottom of the core might be Medieval in age. Radionuclide-based dating (3H, 14C, 137Cs, 210Pb) is in progress.

The multiproxy approach adopted in this study includes black carbon, dust grain size and mineralogy, oxygen and hydrogen stable isotopes and palynomorphs, these last being the main object of this work. Given the site location, the palaeoecological signal is believed to be of regional significance.

Despite the stratigraphy may not be preserved for some soluble chemical species, the core contains a high variety of palynomorphs, which allow the reconstruction of palaeoenvironmental and paleoclimatic variations at subannual resolution. The mean ice accumulation rate is about 0.9 m w.eq. yr-1. Consequently, the mean sampling resolution adopted for the palynomorph study is 0.1 m, increased to 0.01 m in specific intervals. Palynomorphs are mainly found in layers representing the spring-summer deposition while their concentration is very low during other periods of the year. Pollen grains, spores, diatom frustules, phytoliths and charcoals characterize the spring-summer layers; glass shards of volcanic origin and green algae have been observed in few intervals. Sporadic but massive Saharan dust events, carrying characteristic dust particles and pollen of African provenance, were identified throughout the core. The comparison between these intervals and the historical “red rain” events in Northern Italy will help better constraining the ice core dating.

At ca 66 m depth, an ice interval characterized by a high impurity content has been investigated at 0.01 m resolution. Different palynomorphs are recorded in this interval, implying a quasi-continuous presence of humans and animals on the glacier for few years. Preliminary results link these layers to World War I, intensively fought between Italians and Austro-Hungarians on the slopes surrounding the Pian di Neve. The comparison between historical, archeological and ice core data allow delineating, at subannual resolution, the climate and environmental changes that characterized those years.

How to cite: Mangili, C., Delmonte, B., Pini, R., Artoni, C., Baccolo, G., Cremonesi, L., Di Stefano, E., Fiorini, D., and Maggi, V.: The Adamello Glacier: paleoenvironmental and paleoclimatic variations at subannual resolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11175, https://doi.org/10.5194/egusphere-egu24-11175, 2024.

EGU24-11279 | Orals | CL1.2.4 | Highlight

Quantitative Insights on Impurities in Ice Cores at the Grain Scale 

Pascal Bohleber, Piers Larkman, Nicolas Stoll, David Clases, Raquel Gonzalez de Vega, Martin Šala, Marco Roman, and Carlo Barbante

Understanding the spatial variability of impurities in glacier ice on a quantitative level has importance for assessing the preservation of paleoclimatic signals and for the study of macroscopic deformational as well as dielectric ice properties. Two-dimensional imaging via laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS) can provide key insight into the localization of impurities in the ice matrix: Employing the relatively recent advances in LA-ICP-MS featuring fast wash-out devices and single laser shot resolution, state-of-the-art LA-ICP-MS imaging has revealed snapshots showing a close association between grain boundaries and some impurities as well as dispersed clusters in dust-rich ice. So far, these findings are mostly qualitative and gaining quantitative insights remains challenging. Accurate calibrations rely on matrix-matched standards which ideally show the same ablation behavior as the sample. Previous studies successfully prepared ice blocks on glass slides as calibration standards at a resolution of a few hundred microns. State-of-the-art LA-ICP-MS imaging fully reveals the imprint of the ice matrix on the impurity distribution at the grain scale, which also introduces the need for new adequate quantification strategies and consequently, the design of new calibration standards. Here, we present different quantification methods, which provide a high level of homogeneity at the scale of a few microns and, which are dedicated to imaging applications of ice core samples. For this purpose, we use small µL volumes and fast freezing techniques. One of the proposed methods has a second application, offering laboratory experiments to investigate the displacement of impurities by grain growth, with important future potential to study ice-impurity interactions. Standards were analyzed to enable an absolute quantification of impurities in selected ice core samples. Calibrated LA-ICP-MS maps indicate similar distributions of impurities in all samples, while impurity levels vary distinctly: Higher concentrations were calibrated in glacial periods and Greenland, and lower levels in interglacial periods and samples from central Antarctica. These results are consistent with known ranges from bulk meltwater analysis. Further comparison with bulk meltwater analysis calls for a more sophisticated representation of the ice chemistry across spatial scales, for which the calibrated LA-ICP-MS maps now also introduce the quantitative domain.

How to cite: Bohleber, P., Larkman, P., Stoll, N., Clases, D., Gonzalez de Vega, R., Šala, M., Roman, M., and Barbante, C.: Quantitative Insights on Impurities in Ice Cores at the Grain Scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11279, https://doi.org/10.5194/egusphere-egu24-11279, 2024.

EGU24-11478 | ECS | Posters on site | CL1.2.4

Non-target screening analysis on ice and snow samples: a new opportunity to enhance our understanding on past and present atmospheric aerosol composition. 

Francois Burgay, Thomas Singer, Daniil Salionov, Dmitrii Sharkov, Anja Eichler, Theo Jenk, Sabine Bruetsch, Carla Huber, Alexander Vogel, Elena Barbaro, Niccolo Maffezzoli, Federico Scoto, Elisabeth Isaksson, Librada Ramirez, Sasa Bjelic, and Margit Schwikowski

Organic aerosols make up to 70-90% of the total aerosol mass, yet ice-core studies have predominantly focused on a limited set of compounds or bulk fractions altogether. Previous investigations have centered on biomass burning tracers, marine phytoplankton oxidation products, low molecular weight carboxylic acids and persistent organic pollutants, leaving a large majority of molecules unidentified. Advances in high-resolution mass spectrometry (HRMS) have recently enabled the exploration of a wider chemical space through the development of non-target screening (NTS) workflows.

In this work, we present three applications of a novel NTS method. Designed to detect secondary organic aerosol compounds in ice-core and snow samples, the method has contributed to a more comprehensive characterization of past molecular aerosol composition and has supported the development of new molecular proxies. Initially, the method was applied to the Belukha ice core (Siberian Altai, 4072 m. a.s.l.) between 1830 and 1980 CE, providing the first NTS ice-core record that embraces both the pre-industrial and industrial periods. More than 400 compounds were identified, and a clear anthropogenic fingerprint was recognized over the industrial period. Subsequently, the ice core samples from Colle Gnifetti (Switzerland, 4500 m. a.s.l.) covering the period from 1750 to 2000 CE were analyzed. Here, a smaller number of molecules was detected (≈200), consistent with the lower concentrations of dissolved organic carbon observed at this site. In both cores, most of the molecules are composed of carbon (C), hydrogen (H) and oxygen (O) and are associated with atmospheric oxidation of monoterpenes and isoprenes (e.g., succinic acid, pinic acid, azelaic acid). The industrial onset was characterized by an increase in nitrogen and sulfur containing compounds, likely due to the atmospheric reactions with anthropogenic NOx and  SO2. The higher occurrence of compounds with higher O/C ratios during the industrial period observed at both locations, suggests an increase in the atmosphere oxidative capacity. Lastly, the method was applied to 56 snow samples collected in springtime close to Ny-Ålesund (Svalbard Archipelago) and covering both pre- and phytoplankton bloom periods. Together with marine observations of algal bloom, the NTS results suggest promising evidence towards new ice-core marine productivity proxies for long-term reconstructions.

How to cite: Burgay, F., Singer, T., Salionov, D., Sharkov, D., Eichler, A., Jenk, T., Bruetsch, S., Huber, C., Vogel, A., Barbaro, E., Maffezzoli, N., Scoto, F., Isaksson, E., Ramirez, L., Bjelic, S., and Schwikowski, M.: Non-target screening analysis on ice and snow samples: a new opportunity to enhance our understanding on past and present atmospheric aerosol composition., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11478, https://doi.org/10.5194/egusphere-egu24-11478, 2024.

EGU24-11741 | ECS | Orals | CL1.2.4

Investigation of physical properties of particles in the EastGRIP ice core gives new insights into climatic changes during the Last Glacial Termination 

Chantal Zeppenfeld, Tobias Erhardt, Camilla Marie Jensen, and Hubertus Fischer

Characterising insoluble particles in ice cores provides information needed to reconstruct past climatic changes, for example, in circulation patterns and radiative transfer. Concentration, size distribution, and mineralogy of particles are influenced by how the particles are deposited on the ice sheet, transported, and mobilised in their respective source regions.

To quantify the past changes in concentration and properties of insoluble particles, the Classizer One instrument, which is based on the novel single particle extinction and scattering (SPES) method, has been incorporated into the continuous flow analysis set-up in Bern. This allows for the first time high-resolution, continuous, and simultaneous measurements of particle number concentration, diameter, and refractive index in the size range of 0.2 to 2 µm. Thus, covering the full size range of the main mode in the particle number size distribution, which is crucial for the radiative effect of dust in the atmosphere.

Here we present the first study of continuous concentration and size distribution measurements of water insoluble particles in ice cores smaller than 1 µm. The SPES method was used to characterise particles in the EastGRIP ice core from 8000 to 16000 years BP, i.e., including the Bolling Allerød/Younger Dryas climate oscillation. On the one hand, results of previous studies on supramicron dust particles can be confirmed, including the observation that particle concentration is higher, and particles are larger during colder times. On the other hand, the high-resolution measurement in a smaller size range reveals features that were previously hidden.

Over the course of the Younger Dryas (GS-1) the concentration decreases by a factor of 3.5, while the geometric mean of the number size distribution increases by approximately 9%. This is also the case towards the end of the Oldest Dryas (GS-2.1), albeit to a lesser extent. In both instances, the concentration and the modal particle diameter are anti-correlated before they both rapidly decrease at the onset of the following warm phase. While the changes at the transition from the cold to the warm phase may be explained, at least to some degree, for supramicron aerosol by changes in transport efficiency, the opposing trends during the cold phases cannot. This is because a faster transport would lead to an increase in both concentration and particle size for particles larger than approximately 1 µm, where size fractionation by dry deposition occurs.

Additional information can be gained looking at the geometric standard deviation and the effective refractive index. The latter stays relatively constant over the investigated period, which indicates that there were probably no major changes in the mix of potential source regions. The geometric standard deviation does not change abruptly at the onset of a warm phase contrary to the concentration and geometric mean. Instead, it gradually increases already starting in the cold phase. This suggests that climatic changes, probably in the source regions or en route, start taking place prior to the rapid transition to the warm phase.

How to cite: Zeppenfeld, C., Erhardt, T., Jensen, C. M., and Fischer, H.: Investigation of physical properties of particles in the EastGRIP ice core gives new insights into climatic changes during the Last Glacial Termination, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11741, https://doi.org/10.5194/egusphere-egu24-11741, 2024.

In the history of Antarctica’s science, Ice Core Science (ICS) holds a special place. Since the 80s, it is one of the main research fields as it allows scientists to connect with our earth’s past and future climate with the unavoidable change our society will face. Beyond EPICA and the DEEPICE training programme are leading projects as they build a legacy for ICS in Antarctica. 
The purpose of this paper is to examine how ICS and its infrastructure participate in the maintenance of Antarctica as a place of science, as a territory-laboratory. 
I will be presenting the preliminary results of a multi-situated ethnography on scientific communities working in and on Antarctica. For this presentation, I will be focusing on a field work started in 2023 with DEEP-ICE’s PhD students. A first round of interviews led me to a participating observation in a glaciology laboratory, following a PhD candidate during their analysis. Early 2024, a series of follow-up interview is planned to complete my dataset and complete the history of DEEPICE. 
Once retrieved, the value of an ice core sample is directly connected to its possibility of collecting data from a specific time frame, and by that, making new scientific questions emerge. The value of Antarctica’s sample is shown by the constant care it has received. Gestures and technic are specifically tested and repeated in preparation of Antarctica’s sample, even if they later disappears from published papers. 
Communication surrounding Beyond EPICA and DEEPICE highlights the challenges faced by scientists to retrieved ice core, promoting ICS, the excellence of Antarctica’s research while securing funds. The ambition to form fifteen PhD candidates shows the necessity of transmission and heritage, and the excellence expected to perform the future analysis. The samples are valuable not only as an object of science, or because they contain unique data set. They allow our society to exist in different timescales and to overcome human temporalities. 
 With ICS, Antarctica enters in a new era : the heroic age of time exploration. ICS, with its heroic narrative and its possibility to understand past climate has protected Antarctica and its intrinsic value, a place of science and an object to be studied. The DEEPICE training program is an example of the politics of maintenance surrounding Antarctica. The increase of tourism, Ice Memory (where Antarctica is becoming a sanctuary, a living archive) and the development of drilling technic and a new era of research (blue ice) are displaying new questions about the future of ICS and its role in maintaining Antarctica as a place of science. Once the oldest ice will be reached, what new scientific quest will take part of Antarctica’s maintenance ?  

How to cite: Pillon, E.: Deep in Time : An Anthropologic Exploration of the Values of Antarctica’s Ice Core. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12664, https://doi.org/10.5194/egusphere-egu24-12664, 2024.

EGU24-12902 | ECS | Posters on site | CL1.2.4

Advancing towards high-quality water isotope measurements in ice cores: a micro-destructive approach using Laser Ablation coupled with Cavity Ring Down Spectroscopy 

Eirini Malegiannaki, Daniele Zannoni, Pascal Bohleber, Ciprian Stremtan, Agnese Petteni, Barbara Stenni, Carlo Barbante, Dorthe Dahl-Jensen, and Vasileios Gkinis

Addressing the intricate challenges of water isotope analysis in polar ice cores, especially in extracting detailed climate records from older and thinner ice layers, the innovative integration of Laser Ablation (LA) with Cavity Ring Down Spectroscopy (CRDS) is introduced. The micro-destructive LA technique, which employs a nanosecond excimer pulsed laser operating at 193 nm for ice surface irradiation, demonstrates potential in achieving continuous, high-resolution sampling and gas phase sample generation, complementing the CRDS analyzer's precision in measuring water isotopes in gaseous state. Recent advancements include the successful adaptation of an existing LA system, previously coupled with an Inductively Coupled Plasma - Mass Spectrometer (ICP-MS) for ice core impurity analysis, to establish a connection with the CRDS analyzer. This was accomplished by making adjustments to the coupling procedure and laser parameters, to ensure efficient gas sample generation and robust delivery for water isotope analysis. A method for creating ice standard samples by transforming liquid water standards into ice yielded ice isotope standards, crucial for setting up initial measurement protocols. Their implementation on both standard ice samples and sections of ice cores revealed valuable insights into areas for improvement. This represents a significant step towards establishing a reliable method for high-quality water isotope analysis in ice cores, aiming to significantly enrich our understanding of long-term climate trends.

How to cite: Malegiannaki, E., Zannoni, D., Bohleber, P., Stremtan, C., Petteni, A., Stenni, B., Barbante, C., Dahl-Jensen, D., and Gkinis, V.: Advancing towards high-quality water isotope measurements in ice cores: a micro-destructive approach using Laser Ablation coupled with Cavity Ring Down Spectroscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12902, https://doi.org/10.5194/egusphere-egu24-12902, 2024.

EGU24-13000 | Posters on site | CL1.2.4

Total Air Content measurements from the RECAP core 

Thomas Blunier, Sindhu Vudayagiri, Bo Vinther, Todd Sowers, Johannes Freitag, and Peter L. Langen

Total air content (TAC) from ice cores mainly reflects air pressure when the air is occluded and is therefore a proxy for elevation. However, there are several complications, such as melt, changes in firn structure and air pressure variability.  

We measured TAC in the RECAP ice core drilled in 2015 on the Renland Icecap in East Greenland, currently at an elevation of 2340 m. The upper 529 m of the 584 m core cover the Holocene. There is extensive melting in this part of the core, which is reflected in low air content values. Assuming constant altitude and air pressure, lower TACs at the beginning of the Holocene indicate more melting and therefore higher summer temperatures. Simulations with the regional climate model HIRHAM5 allow us to translate the observed melt fractions into summer temperatures. We conclude that summer temperatures in the early Holocene were ~2 to 3°C warmer than today, in agreement with previous findings in Greenland. The core extends into the Eemian. The air content is very low in this section, indicating excessive melting. Using the same metric as for the Holocene, we conclude that the temperature in the Eemian was at least 5°C higher than today.

The ~22m of glacial ice in RECAP from 11.7 to 119 kyr BP appear to be unaffected by melting. However, we observe large variations in total air content during periods of rapid climate change. In Greenland, similar effects have been found at NGRIP (Eicher et al., 2016). These effects cannot be due to changes in elevation. All the evidence points to a dynamic effect in the firn column that changes the pore volume. If we do not understand these effects, the interpretation of TAC in terms of elevation changes is questioned.

How to cite: Blunier, T., Vudayagiri, S., Vinther, B., Sowers, T., Freitag, J., and Langen, P. L.: Total Air Content measurements from the RECAP core, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13000, https://doi.org/10.5194/egusphere-egu24-13000, 2024.

A comprehensive understanding of what caused the repeated growth and decay of northern hemisphere ice sheets (otherwise known as glacial-interglacial cycles) during the Quaternary Period has remained allusive. The importance of changes in the Earth’s orbital parameters for ‘pacing’ these cycles is widely acknowledged. However, the transition from 41 kyr to quasi-100 kyr glacial-interglacial cycles at the Mid-Pleistocene Transition (MPT) occurs without any significant variations in the Earth’s changing orbit. Even the dominance of 41 kyr cycles in the Early Pleistocene is unusual, given the notable absence of strong 19 and 23 kyr precession cycles. Put simply, climatic precession is the orbital parameter that alters the time of the year when the Earth is closest to the Sun, which considerably influences the intensity of summer insolation. As summer insolation is considered critical for the growth and decay of northern hemisphere ice sheets according to Milankovitch Theory, it would be expected that precession cycles would strongly feature throughout the Quaternary. Explanations that account for this absence of strong precession cycles during the Early Pleistocene include an anti-correlation between summer insolation intensity and summer duration or the cancellation of out-of-phase precession cycles between the northern hemisphere ice sheets and Antarctica. Here, we introduce a zonally averaged energy and moisture balance climate model to investigate the response of the Quaternary climate system to changes in the Earth’s orbital parameters. The purpose of the model is to investigate these problems related to glacial-interglacial cycles of the Early Pleistocene. We present equilibrium simulations of the model for the pre-industrial period and the Last Glacial Maximum, to demonstrate the suitability of the model to study climate change on these large spatial and temporal scales of interest. In addition, we show the equilibrium and transient sensitivity of the model to changes in the Earth’s orbital parameters. Factors that influence the relative contributions of obliquity and precession on global temperatures and/or ice volume will be investigated in the context of the 41 kyr cycles of the Early Pleistocene.

How to cite: Gunning, D.: Investigating Quaternary climate sensitivity to orbital variations using an energy and moisture balance climate model., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13531, https://doi.org/10.5194/egusphere-egu24-13531, 2024.

The Brewer-Dobson circulation is the global atmospheric overturning circulation and regulates global mass and energy redistributions in the stratosphere as well as mass exchange between the troposphere and the stratosphere. Through transporting O3 to the troposphere and redistributing O3 in the stratosphere that influence surface UV-B radiation, the Brewer-Dobson circulation also plays an critical role in atmospheric oxidation capacity which matters for air quality, greenhouse gas removal and climate change. While many studies have assessed changes in the Brewer-Dobson circulation in the past few decades and in the future in response to greenhouse gas warming, that how Brewer-Dobson circulation has changed in the past climate is poorly constrained and limited modelling studies reached opposite results on the strength of the Brewer-Dobson circulation in the last glacial maximum (LGM). Atmospheric nitrate O-17 excess signal is sensitive to O3 abundance, and the latter is influenced by the strength of the Brewer-Dobson circulation especially during climate transitions (e.g., the glacial-interglacial cycle and the abrupt climate events). By comparing the nitrate O-17 excess records from the GISP2 and WAIS divide ice cores, we find a coherent changes in the O-17 excess signal from the LGM to the Holocene, suggesting a stronger Brewer-Dobson circulation in the LGM. In addition, during abrupt climate changes (i.e., the D-O events in Greenland and the corresponding AIM events in Antarctica), there is an apparent difference in the changes of O-17 excess in response to temperature in Greenland and Antarctica, a result implies that the Brewer-Dobson circulation should be enhanced when Greenland cools. These results are consistent with earlier model studies, but are in conflict with recent model work which predicts a weakened Brewer-Dobson circulation in the LGM. Specific mechanisms driving the response of the Brewer-Dobson circulation to past climate changes remains to be explored.

How to cite: Geng, L., Jiang, Z., and Alexander, B.: Bipolar ice core constraints on the variability of the Brewer-Dobson Circulation during climate transitions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13788, https://doi.org/10.5194/egusphere-egu24-13788, 2024.

EGU24-13878 | Posters on site | CL1.2.4

Hyperspectral imaging system for ice core studies 

Andrei Kurbatov, Edward Brook, Christo Buizert, Theodore Carr, John Fegyveresi, Tyler Fudge, Geoffrey Hargreaves, Todd Hoefen, Liam Kirkpatrick, Curtis Labombard, Richard Nunn, Lindsay Powers, Kevin Rock, and Mikhail Zhizhin

Hyperspectral imaging (HSI) technology has been increasingly used in Earth and planetary sciences. This imaging technique has been successfully tested on ice cores using VNIR (visible and near-infrared, 380-1000 nm) (Garzonio et al., 2018) and near-infrared (900 - 1700 nm) (McDowell et al, 2023)  line-scan cameras. Results show that  HSI data greatly expand ice core line-scan imaging capabilities, previously used with gray or RGB cameras (see summary in Dey et al., 2023). Combinations of selected HSI bands from the hyperspectral data cube improve feature detection in ice core stratigraphy, and map distribution of volcanic material, dust, air bubbles, fractures, and ice crystals in ice cores. Captured spectral information provides unique fingerprints for specific materials present in ice cores. This method helps to guide ice core sampling because it provides non-destructive, rapid visualization of microstructural properties, layering, bubble contents, increases in dust, or presence of  tephra material. Precise identification of these atmospheric components  is important for understanding past climate drivers reconstructed from ice cores. 

As part of the COLDEX project (Brook et al., this meeting) we adapted the SPECIM SisuSCS HSI system for ice core imaging. The ice core scanning system is housed inside the ca. -20ºC main NSF ICF freezer, and externally computer-controlled. The operator monitors scanning operations and communicates with personnel inside of the freezer via radio.  The system is equipped with a SPECIM FX10 camera that measures up to 224 bands in the VNIR range. We modified the ice core holder tray and installed a heated enclosure for the camera. The system uses SCHOTT DCR III Fiber Optic light sources with an OSL2BIR bulb from Thorlabs. IR filters are removed to extend the light spectral range beyond the 700 nm limit without heating the ice core surface during rapid (<5 minutes) scanning of an entire meter-long section. Emitted light enters ice at a 45º angle from two top and two bottom light sources. To calibrate absolute reflectance we use three Spectralon panels with 100, 50 and 20% reflectance values with every scan as well as several secondary reflective standards and USAF targets for geometric corrections. We are developing Python-based open source data processing routines and currently comparing HSI data with existing ice core physical and chemical measurements. The goal is to fully integrate the ice core HSI system with ice core processing at the NSF ICF. 

Dey et al., 2023. Application of Visual Stratigraphy from Line-Scan Images to Constrain Chronology and Melt Features of a Firn Core from Coastal Antarctica. Journal of Glaciology 69(273): 179–90. https://doi.org/10.1017/jog.2022.59.

Garzonio et al., 2018. A Novel Hyperspectral System for High Resolution Imaging of Ice Cores: Application to Light-Absorbing Impurities and Ice Structure. Cold Regions Science and Technology 155: 47–57. https://doi.org/10.1016/j.coldregions.2018.07.005.

McDowell et al., 2023. A Cold Laboratory Hyperspectral Imaging System to Map Grain Size and Ice Layer Distributions in Firn Cores. Preprint. Ice sheets/Instrumentation. https://doi.org/10.5194/egusphere-2023-2351.

How to cite: Kurbatov, A., Brook, E., Buizert, C., Carr, T., Fegyveresi, J., Fudge, T., Hargreaves, G., Hoefen, T., Kirkpatrick, L., Labombard, C., Nunn, R., Powers, L., Rock, K., and Zhizhin, M.: Hyperspectral imaging system for ice core studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13878, https://doi.org/10.5194/egusphere-egu24-13878, 2024.

EGU24-14084 | ECS | Posters on site | CL1.2.4

Atmospheric dust record preserved in an ice core from Trambau Glacier, Nepal Himalaya 

Nao Esashi, Akane Tsushima, Ryu Uemura, Sumito Matoba, Yoshinori Iizuka, Kouji Adachi, Takeshi Kinase, Rijan B. Kayastha, and Koji Fujita

Mineral dust affects climate through direct radiative forcing by scattering and absorbing solar radiation in the atmosphere and by accelerating snow and ice melting through reduced albedo when deposited on snow surfaces. The concentration and composition of dust deposited on glaciers reflect the surface conditions of the source regions and atmospheric conditions during transportation. Dust records in ice cores provide insights into historical atmospheric and land surface environments. However, ice cores drilled in high-altitude Himalayan glaciers are limited. To investigate historical variations in dust concentration in the Himalayas, we conducted ice core drilling at an elevation of 5862m on the Trambau Glacier in the Rolwaling region of the Nepal Himalaya. The ice core, covering 146 years (1874-2019), was dated using seasonal variations in NO3- and Ca2+. The 81-m ice core was divided into 1637 samples (~5 cm interval), and dust concentration (particle size ranging from 0.6 to 10.0 µm) was measured using the Coulter Counter Multisizer TM3. The Trambau ice core exhibits a higher dust concentration than the other Himalayan ice cores, particularly with an abundance of small particles (<2 µm in diameter). This suggests that the dust concentration in the Trambau ice core are mainly controlled by the supply of small particles from relatively distant regions. Furthermore, the dust concentration shows periodic fluctuations with a 20-30-year cycle, consistent with the Atlantic Multi-decadal Oscillation (AMO). This suggests a connection between the environmental changes (precipitation, temperature, and land surface conditions) in the dust source regions and AMO.

How to cite: Esashi, N., Tsushima, A., Uemura, R., Matoba, S., Iizuka, Y., Adachi, K., Kinase, T., Kayastha, R. B., and Fujita, K.: Atmospheric dust record preserved in an ice core from Trambau Glacier, Nepal Himalaya, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14084, https://doi.org/10.5194/egusphere-egu24-14084, 2024.

EGU24-14086 | Posters on site | CL1.2.4

Seasonally Resolved Age Scale based on Oxygen Isotope Record from SE-Dome II Ice Core, Greenland 

Saaya Hamamoto, Sumito Matoba, Kaoru Kawakami, Mahiro Sasage, Mai Matsumoto, Kei Yoshimura, Atsushi Okazaki, Hayoung Bong, Yoshinori Iizuka, and Ryu Uemura

Ice core ages have been typically determined by counting the layer boundaries of various proxies that represent annual cycles. Some studies in Greenland have identified winter and summer layers, but it is difficult to identify them at higher resolutions (several months resolution) in ice cores drilled at sites with low accumulation rates due to diffusion. Furukawa et al. (2017) proposed a precise age model by matching the oxygen isotope (δ18O) pattern of precipitation isotope between ice core record and isotope-incorporated general circulation models. They applied this dating method to the SE-Dome I (SE1) ice core drilled from a high snow accumulation area (1.02 m w.e. a-1) in southeast Greenland. However, the SE1 core covered for the past 60 years only. Here, we report the age scale based on δ18O data of the SE-Dome II (SE2) ice core (length: 250.79 m) drilled in 2021 in southeast Greenland. The δ18O was analyzed using a cavity ring-down spectrometer (L2130-i, Picarro) with a precision (1σ) of ±0.04‰. The SE2 core δ18O highly correlated with the SE1 core δ18O (r = 0.90), suggesting that the within-year peaks in the SE core are climatic signals. The age scale was created using the SE1 core method, but for this study, we used iso-GSM nudged to historical reanalysis data (20CRv2) for 1870-1979 and created a longer age scale. There was a high correlation between the ice core data and the model (r = 0.76), and by matching the within-year patterns (typically negative peaks during the warm season). Based on this age scale, we analyzed the day on which the maximum and minimum peaks of the mean H2O2 concentration data (Kawakami et al., 2023). The maximum and minimum of H2O2 concentrations for 1980-2020 were estimated on July 20 and January 7, respectively.

 

REFERENCES
Furukawa, R. et al. , Seasonal-Scale Dating of a Shallow Ice Core From Greenland Using Oxygen Isotope Matching Between Data and Simulation, Journal of Geophys. Res. Atmospheres, 122, 20, 10,873-10,887, 2017, https://doi.org/10.1002/2017JD026716
Kawakami, K., et al., SE-Dome II Ice Core Dating With Half-Year Precision: Increasing Melting Events From 1799 to 2020 in Southeastern Greenland, Journal of Geophys. Res.  Atmospheres, 128, 20, 2023, https://doi.org/10.1029/2023JD038874

How to cite: Hamamoto, S., Matoba, S., Kawakami, K., Sasage, M., Matsumoto, M., Yoshimura, K., Okazaki, A., Bong, H., Iizuka, Y., and Uemura, R.: Seasonally Resolved Age Scale based on Oxygen Isotope Record from SE-Dome II Ice Core, Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14086, https://doi.org/10.5194/egusphere-egu24-14086, 2024.

EGU24-15612 | ECS | Orals | CL1.2.4

Study of local accumulation patterns from a snow trench at Dome C 

Adrien Ooms, Mathieu Casado, Ghislain Picard, Laurent Arnaud, Maria Hörhold, Andrea Spolaor, Rita Traversi, Joel Savarino, and Valérie Masson-Delmotte

The center of Antarctica contains some of the oldest ice available on earth for paleo-climate reconstructions. This is due to very slow ice-flow and low accumulation. Yet, low accumulation comes with the drawback that annual snow layers are thin and subject to erosion and re-deposition by wind, inducing locally mixing and sometimes missing snow layers, leading to a highly variable time vs depth gradient at sub-decadal timescales. This greatly limits the interpretation of the climatic record in ice-cores at high temporal resolution. An important challenge thus consists in describing and quantifying these local accumulation patterns on the East Antarctic plateau.

In our study, we combine observations of accumulation rate (stake farm and laser scanner), with chemical and isotopic measurements of a 50-m long snow trench to address the problem of accumulation patterns at Dome C. We suggest that high resolution alignment of the chemistry data, typically used at longer timescales with volcanic eruption alignment in deep ice-cores, is a good method for inter-annual dating of the trench profiles and reconstruction of accumulation time-series up to a 2 year resolution. We find typical annually-varying roughness as well as more persistent patterns with timescales of years, highlighting the complex dynamics of the snow accumulation in central Antarctica. We then use this dataset to explore post-deposition noise in the isotopic record (δ18O and δD) and its local spatial variability.

How to cite: Ooms, A., Casado, M., Picard, G., Arnaud, L., Hörhold, M., Spolaor, A., Traversi, R., Savarino, J., and Masson-Delmotte, V.: Study of local accumulation patterns from a snow trench at Dome C, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15612, https://doi.org/10.5194/egusphere-egu24-15612, 2024.

EGU24-15771 | ECS | Posters on site | CL1.2.4

Duplex Structures in the EastGRIP Ice Core - the Loss of Stratigraphic Integrity 

Julien Westhoff, Paul Bons, Nicolas Stoll, Ilka Weikusat, Chantal Zeppenfeld, Tobias Erhardt, and Dorthe Dahl-Jensen

The EastGRIP ice core is drilled through the Northeast Greenland Ice Stream, which has a surface velocity of 55 m/yr towards NNE at the drill site. Deriving a better understanding of internal deformation and the rheology within an ice stream is crucial for ice flow models and projections of future solid ice discharge. We use the line scanner to make the stratigraphy visible and document disturbances in the layering in the depth region from 1375 to 2120 m covering a large part of the Glacial Period. Disturbances are visible in cuts perpendicular to the ice flow direction, and not in cuts parallel to flow. Between these two extremes, we have a gradual change in type and amount of disturbances. As with all other ice cores, the ice in the EastGRIP ice core is thinned vertically. Due to the advanced thinning of layers, it is clear that the visible structures are not the remnants of surface features, such as sastrugi.  However, the disturbances, or deformation structures, are the result of strain caused by the stress field at the EastGRIP site, which is described by a compressional component perpendicular to and an extensional component parallel to the ice flow direction. In most samples cut perpendicular to ice flow, i.e. with the compressional setting visible, we find structures, very similar to geological duplex structures. We identify duplex structures extending the width of the core by the sudden change of layer tilt within one bag at a time. Duplex structures are confined by layer parallel shear zones, with tilted layers in between them. The small-scale shear zones only become evident due to the deformation they cause and can extend well beyond these visible structures. We furthermore suggest, that shear zones are present parallel to layering, but do not show up, as a lateral displacement of layers, does not disrupt the vertical profiles. We discuss one example, from a depth of 1651 m (26 ky b2k), in detail. We further investigate approx. 30 m of chemical CFA data, mainly NH4+ and Ca++, from the same depth. We find peaks that double, in both the visual stratigraphy as well as the CFA data. These may be a result of the duplex structures that stack the stratigraphy and have the potential to disturb the climate record. Our results display the importance of understanding internal deformation when interpreting the climate record.

How to cite: Westhoff, J., Bons, P., Stoll, N., Weikusat, I., Zeppenfeld, C., Erhardt, T., and Dahl-Jensen, D.: Duplex Structures in the EastGRIP Ice Core - the Loss of Stratigraphic Integrity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15771, https://doi.org/10.5194/egusphere-egu24-15771, 2024.

EGU24-15921 | Posters on site | CL1.2.4 | Highlight

The March 2022 exceptional heatwave recorded in the isotopic composition of precipitation at Dome C, East Antarctica 

Giuliano Dreossi, Mauro Masiol, Daniele Zannoni, Claudio Scarchilli, Virginia Ciardini, Paolo Grigioni, Massimo Del Guasta, and Barbara Stenni

An exceptional heatwave impacted on East Antarctica between March 15 and 19, 2022, causing some of the highest temperature anomalies ever measured on Earth. The heat transport was associated to an atmospheric river bringing a moisture flux from lower latitudes to inner Antarctica. Several locations, from coastal sites to the high Antarctic Plateau, experienced record temperatures. The air temperature measured at Concordia Station by the automatic weather station of the Italian Antarctic national research program (PNRA) reached a maximum of -11.7°C.

The temperature signal is imprinted in the oxygen and hydrogen isotopic composition of precipitation: this is what allows paleoclimate reconstructions from the isotopic records in ice cores, although post-depositional processes such as the interactions between snow and atmosphere and within the snow column might affect the pristine isotopic signal.

Since 2008, precipitations have been collected daily at Concordia Station for δ18O and δD measurements; the activities have been carried out under the PNRA project WHETSTONE and will continue in the framework of the PNRA project AIR-FLOC. Isotopic values from 2008 to 2021 range between -82.63‰ and -26.97‰ for δ18O and between -595.1‰ and -223.0‰ for δD, while water stable isotope data from February to April 2022, show unprecedented high values (δ18O =-18.97‰, δD=-147.9‰), the highest recorded over the last 15 years, in correspondence to the exceptional temperatures and snow precipitations. Moreover, the daily snowfall collected during the same period reached a cumulative value of ~4.3 mm w.e. representing ~18% of the 2022 cumulative annual value (24.1 mm w.e.)

How to cite: Dreossi, G., Masiol, M., Zannoni, D., Scarchilli, C., Ciardini, V., Grigioni, P., Del Guasta, M., and Stenni, B.: The March 2022 exceptional heatwave recorded in the isotopic composition of precipitation at Dome C, East Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15921, https://doi.org/10.5194/egusphere-egu24-15921, 2024.

EGU24-15946 | ECS | Orals | CL1.2.4

Chemical Analysis of Organic Matter in Cloudwater and Aerosol in High-Altitude Alps 

Hanne Notø, Anne Kasper-Giebl, Bernadette Kirchsteiger, Daniela Kau, Felix Happenhofer, Thomas Riedelberger, Elke Ludewig, and Rupert Holzinger

Organic matter in ice cores holds important climatic information, such as the prevalence of wildfires, marine algae blooms, terrestrial biosphere productivity, and antarctic sea ice extent. While organic compounds are specific tracers of the biosphere in paleoclimatic records, very little is known about their transport and deposition onto glaciers and ice sheets. Factors such as atmospheric transport, scavenging in the atmosphere and deposition efficiency can have a substantial effect on the amount of organic matter measured in the snow and ice. To better understand the deposition of organic matter onto glaciers and ice sheets, we determined the presence of organic species in clouds versus particulate matter in the atmosphere.  

In this work we present data from a sampling campaign aimed at measuring organic matter in cloudwater and aerosol particles (PM1 and PM10). Samples were collected at the Sonnblick Observatory in the Austrian Alps (3106 m a.s.l.) across 10 days in November 2022. This site represents remote alpine atmospheric conditions. The samples were analyzed using a Thermal Desorption - Proton Transfer Reaction - Mass Spectrometer (TD-PTR-MS), which quantifies volatile and semi-volatile organic species. Further processing will reveal potential differences in organic composition between cloudwater and aerosol particles. This information can provide insight into the deposition of organic matter in the cryosphere, which affects the way ice core records are interpreted. 

How to cite: Notø, H., Kasper-Giebl, A., Kirchsteiger, B., Kau, D., Happenhofer, F., Riedelberger, T., Ludewig, E., and Holzinger, R.: Chemical Analysis of Organic Matter in Cloudwater and Aerosol in High-Altitude Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15946, https://doi.org/10.5194/egusphere-egu24-15946, 2024.

EGU24-15991 | Posters on site | CL1.2.4

Extreme precipitation events in firn core isotopic records: where to find the best drilling site? 

Cécile Agosta, Christophe Leroy-Dos Santos, Elise Fourré, Mathieu Casado, Alexandre Cauquoin, Martin Werner, and Amaëlle Landais

Extreme precipitation events (EPE), defined as the top 10% of daily precipitation amounts, play a major role in Antarctica surface mass balance as they account for more than 40% of the total annual precipitation across the continent. These EPEs are often associated with high temperatures and have major consequences on the Antarctic surface mass balance. Though, it is key to estimate their recent evolution in terms of frequency and intensity in the context of climate change. As water stable isotopic composition of firn cores is known to record the temperature signal modulated by precipitation intermittency, and to be imprinted as well as by the large-scale atmospheric circulation, we can ask if EPEs could be detected in firn cores thanks to a particular isotopic signature.

In this study we construct Virtual Firn Cores (VFC) across Antarctica to investigate how winter EPEs can be misinterpreted as summer maxima in firn cores. We create VFC using (1) temperature, precipitation rate and a linear temperature-d18O relationship from atmospheric regional model MAR, (2) d18O in precipitation from ECHAM6-wiso and (3) d18O in precipitation from LMDZ6-iso, for the period 1979-2022. Additionally to standard VFCs, we generate a second set of VFCs excluding each year the highest winter precipitation event (5-days period). We then run a detection algorithm to find local maxima for both sets of VFCs. We observe some regions with nearly 20% more “summer” detected in standard VFCs compared to VFCs without the winter maximum precipitation event. We argue that firn cores drilled in those regions are more likely to contain isotopic signals that could be used to detect EPEs temporal variability.

How to cite: Agosta, C., Leroy-Dos Santos, C., Fourré, E., Casado, M., Cauquoin, A., Werner, M., and Landais, A.: Extreme precipitation events in firn core isotopic records: where to find the best drilling site?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15991, https://doi.org/10.5194/egusphere-egu24-15991, 2024.

EGU24-16302 | ECS | Orals | CL1.2.4

Improving our Understanding of Melt-Affected Ice Cores Through In-Situ Percolation Tracer Experiments 

Dorothea Elisabeth Moser, Elizabeth R. Thomas, Andrea Spolaor, Jean-Charles Gallet, and Johannes Freitag

Rising global temperatures and accelerated melting cause glaciers across the globe to shrink, thereby hampering our ability to reconstruct past climate from ice cores across the globe. In this context, melt-induced alterations of chemical signals in ice cores are an increasing issue not only for researchers working on mid- and low-latitude glaciers but in coastal Antarctica, Greenland, and other (sub-)polar sites, too.

Aiming to contribute to a more comprehensive understanding of ice cores as environmental archives when affected by melt, Moser et al. (2023) have recently conducted an in-depth review of the existing literature regarding external drivers of melt events, physics of melt layer formation and behaviour during snow metamorphism, identification and quantification of melt, structural characteristics of melt features, effects of melting on records of chemical impurities, stable water isotopic signatures, and gas record, as well as applications of melt layers as environmental proxies. By briefly walking through formation, manifestation and potential interpretation of refrozen melt sections, we here provide an overview of those aspects of near-surface melting, which are important for ice-core record interpretation more widely.

Against this backdrop of existing research and gaps of knowledge, we present the setup and first results of percolation tracer experiments conducted during a field campaign near Ny-Ålesund, Svalbard, in March-April 2023. Showing the alteration of snowpack structure and chemistry through liquid water in-situ, the experiments have provided new insights into (1) meltwater flow and refreezing processes in the vicinity of Ny-Ålesund, and (2) the informational value of stable water isotope records before and after rain-on-snow induced melt events. Finally, we compare these in-situ observations to high-resolution structural scans of melt features in ice cores to explore further conclusions, which help to improve our understanding of melt-affected ice cores.

 

Moser, D. E., Thomas, E. R., Nehrbass-Ahles, C., Eichler, A., & Wolff, E. (2023). Melt-Affected Ice Cores for (Sub-)Polar Research in a Warming World. EGUsphere Preprint. https://doi.org/10.5194/egusphere-2023-1939

How to cite: Moser, D. E., Thomas, E. R., Spolaor, A., Gallet, J.-C., and Freitag, J.: Improving our Understanding of Melt-Affected Ice Cores Through In-Situ Percolation Tracer Experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16302, https://doi.org/10.5194/egusphere-egu24-16302, 2024.

EGU24-16598 | ECS | Orals | CL1.2.4

Re-assessment of methane cycle dynamics from the preindustrial to present-day  

Ivo Strawson, Rachael H. Rhodes, Thomas Bauska, Ben Riddell-Young, Julia Marks Peterson, Xavier Faïn, Frédéric Prié, Romilly Harris Stuart, Amaëlle Landais, Elizabeth R. Thomas, Christo Buizert, and Edward Brook

Ice core reconstructions of atmospheric methane (CH4) and its stable carbon isotope ratio (δ13CH4) provide important constraints for understanding the links between human activity, methane and climate. However, uncertainties in existing δ13CH4 records since the preindustrial (~1850 CE), reconstructed from measurements of polar firn air and a small number of high-accumulation ice core sites, limit the precise determination of the timing and rate of recent changes in source/sink evolution. To re-assess methane dynamics over the last two centuries, we present continuous multi-core records of atmospheric CH4 and carbon monoxide (CO) between 1824 and 1994 CE reconstructed from high snow accumulation Antarctic sites and supplement these data with new bubble ice measurements of δ13CH4 spanning 50-years from 1938 to 1988 CE at a < 5-year resolution. Across the 50-year record, atmospheric CH4 mixing ratios increase by > 580 ppb and each δ13CH4 measurement therefore requires a considerable correction for diffusive fractionation resulting from a sustained growth in the overlying atmospheric methane burden during firn transport. An overlap with direct atmospheric observations is used to validate corrections for this phenomenon. Source/sink dynamics necessary to drive the simultaneous temporal trends observed in CH4, CO and δ13CH4 since 1850 CE are then inferred using a 6-troposphere, multi-tracer box model. Isotopic corrections, their implications and subsequent modelling results will be discussed.

How to cite: Strawson, I., H. Rhodes, R., Bauska, T., Riddell-Young, B., Marks Peterson, J., Faïn, X., Prié, F., Harris Stuart, R., Landais, A., R. Thomas, E., Buizert, C., and Brook, E.: Re-assessment of methane cycle dynamics from the preindustrial to present-day , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16598, https://doi.org/10.5194/egusphere-egu24-16598, 2024.

EGU24-16768 | ECS | Posters on site | CL1.2.4

Microstructural insights during Abrupt events 

Miguel Sanchez Moreno, André Lamott, Sepp Kipfstuhl, and Dorthe Dahl-Jensen

The physical properties of ice crystals are strongly related to the flow and deformation of ice. This has been established by detecting crystal size and crystal orientation on 10cm x 10cm thin sections of ice through many of the deep ice cores by microstructure mapping. This method maps etch grooves on polished and sublimated surfaces at microscopic resolution generated by the Extra Large Area Scanning Microscope (xLASM) and allows for a detailed investigation of deformation-induced microstructural features. 

Here, we carry out a detailed examination of the microstructural features present along 25 meters of ice within the North Greenland Eemian Ice Drilling project (NEEM). The study analyzes ice from 2003 meters to 2028 meters in depth, covering three abrupt events (GI-19.2, GS-20, and GI-20) within the Last Glacial Maximum. In combination with fabric measurements and borehole logging data, we aim to understand shifts in ice rheology and flow dynamics during these abrupt events. 

How to cite: Sanchez Moreno, M., Lamott, A., Kipfstuhl, S., and Dahl-Jensen, D.: Microstructural insights during Abrupt events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16768, https://doi.org/10.5194/egusphere-egu24-16768, 2024.

EGU24-16818 | ECS | Posters on site | CL1.2.4

A new 3D approach to linking high-resolution analysis on impurities for application to deep ice 

Piers Larkman, Nicolas Stoll, Rachael Rhodes, Carlo Barbante, Barbara Stenni, Geunwoo Lee, Chantal Zeppenfeld, Hubertus Fischer, Martin Šala, and Pascal Bohleber

Ice that will be extracted from close to the bedrock of the Antarctic ice sheet during the Beyond EPICA Oldest Ice (BE-OI) project is expected to have more than 14,000 years of climatic information contained in a single vertical meter of ice. High-resolution analysis is required to extract meaningful climate signals from the impurities contained in this ice. This analysis should be comparable to the currently established continuous flow analysis (CFA) approach, which acquires a 1-dimensional impurity signal at approximately centimetre resolution. To date, it has been shown that smoothed high-resolution profiles taken using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are comparable to CFA signals. However, the physical origin of this link needs to be better understood, especially in view of the imprint of the impurities on the ice crystal matrix recently revealed by 2D imaging on the micron scale.

Here we present a framework to generate and explore 3-dimensional models mapping the location of soluble impurities within ice samples. This framework helps link experimentally acquired smoothed LA-ICP-MS profiles, 2-dimensional LA-ICP-MS maps of impurities, and CFA data. The conceptual step into 3-dimensions allows exploration of the distortions of the climate signal due to interactions of impurities with the ice matrix. In shallow ice with relatively small grains and well resolved stratigraphy, this distortion is likely not significant enough to compromise analysis that takes large sample volumes with large mixing, such as seen during CFA. In order to extract signals in deep ice with large crystal sizes and dense layering, where this distortion will be most relevant, we find that carefully designed LA-ICP-MS experiments coupled with post-processing upscaling techniques are required. For a test against experimental data, this work is now being applied to a comparative study involving Antarctic ice measured with both CFA and LA-ICP-MS systems to prove its application to shallower, better-understood ice intervals. Ultimately, the goal is to develop a combination of cm-scale CFA, micron-scale LA-ICP-MS imaging and 3D modelling that will provide key insight on the impurity-related climate signals in deep ice at the BEOI core and elsewhere.

How to cite: Larkman, P., Stoll, N., Rhodes, R., Barbante, C., Stenni, B., Lee, G., Zeppenfeld, C., Fischer, H., Šala, M., and Bohleber, P.: A new 3D approach to linking high-resolution analysis on impurities for application to deep ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16818, https://doi.org/10.5194/egusphere-egu24-16818, 2024.

EGU24-17285 | Posters on site | CL1.2.4

Comparison of effective diffusion rates in multiple ice cores 

Rachael Rhodes, Yvan Bollet-Quivogne, Daniel Clarke, Piers Barnes, and Eric Wolff

To extract climatically relevant chemical signals from the deepest, oldest ice in the polar ice sheets, we must first understand the degree to which chemical ions diffuse within solid ice. Volcanic sulfate peaks are the ideal target for such an investigation because they have a uniform peak shape at deposition. Processes of chemical diffusion and ice sheet thinning modify sulfate peak shapes with depth/age in an ice core. Our previous work developed a forward model, which simulates sulfate peak evolution in the ice sheet, and identifies the optimum effective diffusion rate for individual peaks. Analysis of the EPICA Dome C (EDC) sulfate record over the last 450 kyr suggests that the rate of sulfate diffusion is initially relatively rapid (2.4 ± 1.7 x 10-7 m2yr-1 median for Holocene ice) and slows down over time to rates on the order of 1 x 10-8 m2 yr-1 or less. We hypothesize this may result from a switch in the mechanism of diffusion resulting from the changing location of sulfate ions within the ice microstructure. Here we apply our forward model to three other ice cores: NGRIP (Greenland), EDML (East Antarctica) and WAIS Divide (West Antarctica) to determine sulfate diffusion rates and their evolution over depth/age. These ice cores are different to each other, and to EDC, in terms of their temperature profiles, ice grain size evolution and dust loading, all factors which may influence sulfate diffusion rates.

How to cite: Rhodes, R., Bollet-Quivogne, Y., Clarke, D., Barnes, P., and Wolff, E.: Comparison of effective diffusion rates in multiple ice cores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17285, https://doi.org/10.5194/egusphere-egu24-17285, 2024.

EGU24-17433 | ECS | Posters on site | CL1.2.4

Exploration of elemental details of single mineral dust particles in the EPICA Dome C ice core during interglacial and glacial periods 

Geunwoo Lee, Tobias Erhardt, Chantal Zeppenfeld, Piers Larkman, Pascal Bohleber, and Hubertus Fischer

The single particle inductively coupled plasma time-of-flight mass spectrometer (sp-ICP-TOFMS, model: icpTOF R from TOFWERK, Switzerland) coupled to the Bern continuous flow analysis (CFA) has demonstrated its ability to resolve signals of individual insoluble particles in the meltwater. This offers valuable insights into the characteristics of mineral dust obtained from the elemental composition of the mineral dust as - in contrast to bulk analyses - it allows deciphering of the complete elemental range of particle composition, which can be a mixture of different minerals (Erhardt et al. 2019). 

To apply this new technique for the first time to sections of an Antarctic ice core covering several glacial and interglacial stages, we conducted aerosol chemical CFA measurements on a selection of 18 Antarctic EPICA Dome C (EDC) 55 cm ice core sections, from both glacial and interglacial periods over the last 800 kyr using CFA-sp-ICP-TOFMS.

We present the new preliminary results of our CFA campaign with a nominal 55 cm bag mean resolution (or 110 cm where two consecutive bags were measured). The depth resolution corresponds to a time period in the range of 40 to 602 years of precipitation history in the Holocene, the last glacial period, and various marine isotope stages (MIS 9, 11, 15, 16, 17, and 18). Our goal is to extract detailed information about changes in climate and environmental conditions from individual elemental mineral dust particles. We compare the element-bearing particle number concentration (PNC) measured with sp-ICP-TOFMS for both major and minor crustal elements to the dust PNC optically measured with a laser absorption particle sensor (Abakus from Klotz, Germany), irrespective of its elemental composition, providing a complementary perspective. Furthermore, we examine the variability of dust composition using the elemental mass ratio of individual mineral dust particles during different warm and cold periods.

How to cite: Lee, G., Erhardt, T., Zeppenfeld, C., Larkman, P., Bohleber, P., and Fischer, H.: Exploration of elemental details of single mineral dust particles in the EPICA Dome C ice core during interglacial and glacial periods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17433, https://doi.org/10.5194/egusphere-egu24-17433, 2024.

EGU24-17500 | Posters on site | CL1.2.4

Digital twins – fast flyby-X-ray CT measurements of polar firn 

Johannes Freitag and Michael Salamon

In this study we report on the first continuous records of three dimensional firn structure reconstructions using archive pieces of firn cores that cover the whole depth range of firn starting from surface down to the transition to bubbly ice. The CT-measurements have been performed on 1m-core segments with the means of the AWI-X-ray-computer tomograph especially designed for ice applications. Flyby recording in helical mode under a time-optimized measurement protocol enabled us to reduce the scanning time to 25 minutes per meter firn. The reconstructed volumes have a spatial resolution of 120 µm, giving about 1 million cross-section images per firn core. The analytical work flow includes three steps of pre-processing with denoising, image segmentation and a manual check for outliers at break positions and a layer-wise (5.5 mm thick) calculation of several geometrical parameters like density, ice and pore cluster sizes, intercept lengths, autocorrelation functions, structural anisotropy, Euler number (connectivity), coordination number, bubble number density, closed and open porosity.

The method was applied to archive pieces of EGRIP-S6 (firn air pumping site, 2018, North-East-Greenland, 75.6°N ,35.9°W), B40 (Kohnen station, 2013, Dronning Maud Land, East Antarctica, 75.0°S, 0.1°E) and B51 (CoFi-Traverse 2013, Dronning Maud Land, East Antarctica, 75.1°S ,15.4°E). Temperature and accumulation rates at the different core sites vary between -30°C and -50°C and 130 mm w.eq./a and 40 mm w.eq./a respectively. The selected sites cover a wide range of recent environmental conditions of polar regions.

In this contribution we present several fundamental relationships between the derived geometrical parameters. The evolution of firn structure with depth will be discussed in respect to the dominant processes acting at different sintering/densification stages. The potential value for densification modelling, gas transport and enclosure modelling will be highlighted.

How to cite: Freitag, J. and Salamon, M.: Digital twins – fast flyby-X-ray CT measurements of polar firn, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17500, https://doi.org/10.5194/egusphere-egu24-17500, 2024.

EGU24-17885 | ECS | Posters on site | CL1.2.4

Surface processes and drivers of the snow water stable isotopic composition at Dome C, East Antarctica – a multi-datasets and modelling analysis 

Inès Ollivier, Hans Christian Steen-Larsen, Barbara Stenni, Giuliano Dreossi, Mathieu Casado, Ghislain Picard, Laurent Arnaud, Alexandre Cauquoin, Martin Werner, and Amaëlle Landais

The ability to infer past temperatures from ice core records has in the past relied on the assumption that after precipitation, the stable water isotopic composition of the snow surface layer is not modified before being buried deeper into the snowpack and transformed into ice. However, in extremely dry environments, such as the East Antarctic plateau, the precipitation is so sparse that the surface is exposed to the atmosphere for significant time before burial. Several processes have been recently identified as impacting the snow isotopic composition after snowfall, including moisture exchanges between the snow and the lower atmosphere, wind effects and diffusion inside the snowpack.

Here we present the result of a study that combines existing and new datasets of the precipitation, snow surface and subsurface isotopic compositions (δ18O and d-excess), meteorological parameters, ERA5 reanalysis products, outputs from the isotope-enabled climate model ECHAM6-wiso and a simple modelling approach to investigate the transfer function of water stable isotopes from precipitation to the snow surface and subsurface at Dome C, East Antarctica. We find that (i) moisture fluxes at the surface of the ice sheet lead to a net sublimation of snow throughout the year, from 3.1 to 3.7 mm water equivalent over the 2018-2021 period, (ii) the precipitation isotopic signal only cannot account for the intra-annual to seasonal variability observed in the snow isotopic composition and (iii) the cumulative impact of post-depositional processes at the surface over five years lead to an enrichment in δ18O of the snow surface by 3.3‰ and a lowering of the snow d-excess by 3.5‰ compared to the precipitation isotopic signal. This study reinforces previous findings about the complexity and multiple origin of the snow isotopic composition at Dome C and provides a first step toward a quantitative attribution of the different processes building up of the isotopic signal in the snow surface that is crucial for the interpretation of isotopic records from ice cores.

How to cite: Ollivier, I., Steen-Larsen, H. C., Stenni, B., Dreossi, G., Casado, M., Picard, G., Arnaud, L., Cauquoin, A., Werner, M., and Landais, A.: Surface processes and drivers of the snow water stable isotopic composition at Dome C, East Antarctica – a multi-datasets and modelling analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17885, https://doi.org/10.5194/egusphere-egu24-17885, 2024.

EGU24-18685 | Posters on site | CL1.2.4

Minimizing the uncertainty in shallow borehole-temperature logging 

Thomas Laepple, Nora Hirsch, Alexandra Zuhr, and Fyntan Shaw

The temperature distribution through the ice sheet is a record of past climate changes. This allows reconstructing the past surface temperature history from the vertical temperature profile measured in a borehole (‘borehole palaeothermometry’). Such a reconstruction from the inversion of the heat advection-diffusion equation is independent from the analysis of oxygen isotopes in the ice but requires high-precision measurements of the borehole-temperature on the milli-Kelvin level. 

The precision and accuracy of the measurements is influenced by the spatial and temporal (seasonal to multi-hour) variations of the borehole temperature, the influence of the measurement setup (disturbance of the temperature profile from the borehole or snow pit drilling), the heat transfer between the ice/snow and the sensor as well as the uncertainty of the measurements (depth uncertainty and sensor precision and accuracy).  

Here, we report on our efforts to quantify these uncertainties of near surface (10m) firn and shallow (~200m) borehole temperature measurements using a newly developed winch-based borehole measurement system as well as stationary chains of borehole/firn temperature sensors at replicate sites near the EDML drilling site, Antarctica.

How to cite: Laepple, T., Hirsch, N., Zuhr, A., and Shaw, F.: Minimizing the uncertainty in shallow borehole-temperature logging, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18685, https://doi.org/10.5194/egusphere-egu24-18685, 2024.

EGU24-19981 | ECS | Posters on site | CL1.2.4

Towards continuous ice core measurements of N2O and CO2 

Isobel Rowell, Thomas Bauska, Emma Fisher, Ivo Strawson, and Rachael Rhodes

Measurements of greenhouse gases (GHGs) in ice cores have provided invaluable data, offering insights into the role of GHGs in the climate system over millennia. While previous research has successfully employed continuous analysis techniques to achieve high resolution records of methane (CH4) variations, analyses of nitrous oxide (N2O) and carbon dioxide (CO2) concentrations have historically been limited to discrete, dry-extraction, measurements due to the gases’ high solubility. Obtaining records of centennial-scale (or finer) variability in N2O and CO2, akin to that of CH4, necessitates a new approach. In this work, we employ a new laser spectrometer designed for low flow rates, accompanied by a novel, custom-built gas extraction unit, to re-extract dissolved N2O and CO2 from a synthetic melt-stream. We modify physical parameters at the gas extraction site, controlling temperature, downstream pressure and flow rate. Through optimisation of these parameters, we aim to achieve a high and consistent rate of extraction. Our findings demonstrate the potential of these developments in improving re-extraction of N2O and CO2 to obtain more accurate concentrations from analysis of a mock continuous ice core melt stream. This work marks a step towards refining and applying the method to an Antarctic ice core, contributing to a more comprehensive understanding of the finer scale palaeoclimatic variations of all major GHGs.

How to cite: Rowell, I., Bauska, T., Fisher, E., Strawson, I., and Rhodes, R.: Towards continuous ice core measurements of N2O and CO2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19981, https://doi.org/10.5194/egusphere-egu24-19981, 2024.

EGU24-21625 | ECS | Posters on site | CL1.2.4

Sulfur isotope compositions of the NEEM ice core reveal glacial-interglacial and millennial-scale variability in the sources of sulfate aerosols  

Helena Pryer, Margareta Hansson, Hubertus Fischer, Rachael Rhodes, Andrea Burke, James Rae, Gabor Újvári, Alexandra Turchyn, Robert Mulvaney, and Eric Wolff

The sulfur (S) isotope composition of ice cores represents a novel proxy to quantify variability in the sources of atmospheric sulfate. Sulfate aerosols exert a crucial but highly uncertain feedback on the climate system, acting as cloud condensation nuclei and scattering incoming solar radiation. Ice cores from Antarctica indicate that the majority of sulfate aerosols are sourced from marine biogenic activity, with little variability in emissions between glacial and interglacial periods. However, there are currently no published S isotope studies from the Arctic extending beyond the Common Era, and it is unclear how processes could differ between hemispheres. We present a high-resolution S isotope record of the NEEM ice core from Greenland, covering an entire glacial cycle from 0-128 ka BP. S isotope values appear to co-vary with the climate, exhibiting far lighter isotopic compositions during the Last Glacial compared to the Holocene or Last Interglacial. Systematic variability of S isotope values across Dansgaard–Oeschger events and strong linear relationships with water isotope compositions and calcium concentrations of the ice are also observed. We interpret these trends to show climatically controlled changes in the key sources of sulfate reaching the NEEM ice core site. During peak glacial conditions, the budget is dominated by sulfate sourced from terrestrial dust and volcanic emissions, with a negligible marine biogenic component. This finding suggests that we can use S isotopes to identify time periods when the source region for marine biogenic emissions reaching Greenland may have been completely ice-covered. Overall, this study provides new insights into the processes controlling sulfate aerosols in the Arctic and how the S cycle interacts with the climate.

How to cite: Pryer, H., Hansson, M., Fischer, H., Rhodes, R., Burke, A., Rae, J., Újvári, G., Turchyn, A., Mulvaney, R., and Wolff, E.: Sulfur isotope compositions of the NEEM ice core reveal glacial-interglacial and millennial-scale variability in the sources of sulfate aerosols , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21625, https://doi.org/10.5194/egusphere-egu24-21625, 2024.

EGU24-64 | ECS | Orals | CL1.2.5

The Largely Linear Response of Earth’s Ice Volume to Orbital Forcing 

Liam Wheen, Thomas Gernon, Cameron Hall, Jerry Wright, and Oscar Benjamin

 

We investigate the effect of Earth’s orbitally governed incoming solar radiation on global ice volume over the past 800,000 years. It is well established that the orbital parameters play some role in the pacing of the glacial-interglacial cycles. However, due to limited data and enigmatic dynamics, the mechanics that could facilitate this relationship remain unresolved. We therefore consider a simple linear model of ice volume that imposes minimal assumptions about its dynamics. This model adequately reproduces the ice volume data for most of the 800,000 year period, with the exception of Marine Isotope Stage 11. This suggests that, aside from a few extrema, the ice volume dynamics primarily result from an approximately linear response to orbital forcing. We substantiate this finding by addressing some of the key criticisms of the orbitally forced hypothesis. In particular, we show that eccentricity can significantly vary the ocean temperature without the need for amplification on Earth. We also present a feasible mechanism to explain the absence of eccentricity’s 400,000 year period in the ice volume data. This requires part of the forcing from eccentricity to be lagged via a slow-reacting mechanism, resulting in a signal that closer approximates the change in eccentricity. A physical interpretation of our model is proposed, using bulk ocean and surface temperatures as intermediate mechanisms through which the orbital parameters affect ice volume. These show reasonable alignment with their relevant proxy data, though we acknowledge that these variables likely represent a combination of mechanisms.

How to cite: Wheen, L., Gernon, T., Hall, C., Wright, J., and Benjamin, O.: The Largely Linear Response of Earth’s Ice Volume to Orbital Forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-64, https://doi.org/10.5194/egusphere-egu24-64, 2024.

EGU24-113 | ECS | Posters on site | CL1.2.5

Development of a Continuous Flow Analysis system for studying Allan Hills, Antarctica ice cores 

Abigail Hudak, Asmita Banerjee, Edward Brook, Christo Buizert, Maciej Sliwinski, Lindsey Davidge, Eric Steig, Andy Schauer, Noah Brown, Miranda Miranda, and Eric Saltzman

Extending ice core records beyond 800 thousand years (kyr) is a pivotal goal in paleoclimate research. Allan Hills, East Antarctica, provides a unique opportunity to evaluate old ice and reconstruct climate well beyond 800 kyr with preliminary research uncovering ice ages up to 4.5 million years. Although old ice has been found and proven to be valuable, the ice in this area demonstrates several peculiarities—such as strong layer thinning, folding, and non-atmospheric CO2 – that warrant an in-depth investigation of the ice at this site and the climate record it holds. To address these challenges, we aim to initially conduct a high-resolution continuous flow analysis (CFA) of dust, water stable isotopes, water chemistry, and methane on the upper 70m of an ice core drilled in the 2022-2023 field season at the Allan Hills. A new CFA system has been developed at Oregon State University to analyze old ice, consisting of separate laser spectrometers for water stable isotopes and methane, an Abakus particle sensor for dust, and a fraction collector for sample analysis of melt-water chemistry.

Here, we aim to present preliminary data on dust and methane and demonstrate the newly developed CFA system. Preliminary analyses on this ice have revealed the surface ice to be ~400 kyr old, with the majority of the upper 70m likely in stratigraphic order. This enables meaningful comparisons to other Antarctic ice cores and strengthens our comprehension of the climate-recording behavior of the ice. A high-resolution investigation of this ice is a critical step in understanding the discrete records from the Allan Hills that extend beyond the Mid-Pleistocene Transition and into the Pliocene, pushing our ice core records into unique and enigmatic parts of Earth’s climate history.

How to cite: Hudak, A., Banerjee, A., Brook, E., Buizert, C., Sliwinski, M., Davidge, L., Steig, E., Schauer, A., Brown, N., Miranda, M., and Saltzman, E.: Development of a Continuous Flow Analysis system for studying Allan Hills, Antarctica ice cores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-113, https://doi.org/10.5194/egusphere-egu24-113, 2024.

During the early Pleistocene (prior to 1.25 Ma), obliquity dominated the cyclicity of climatic variations, resulting in glacial and interglacial cycles. A significant change occurred between 1.25 Ma and 0.7 Ma, which altered the dominant frequency from 41 kyr to 100 kyr. This transition period is known as the Mid-Pleistocene Transition (MPT). Although several climate models and records have focused on the MPT, our understanding of how climatic variations in the 41 kyr-world affected the planktonic foraminiferal fauna, and their response to the millennial-scale sea surface temperature (SST) oscillations remains limited. Here, we present a sub-millennial scale planktonic foraminiferal assemblage and G. bulloides stable isotope data from southern Iberian margin IODP Site U1387 (36°48.321´N 7°43.1321´W, 559 water depth), influenced by subtropical surface waters from the Azores current. The main goal is to reconstruct temporal trends in SST and to infer ecological changes during the interval from Marine Isotope Stage (MIS) 50 to MIS 40 (1.5-1.28 Ma).

Planktonic foraminifera assemblages show a distinct pattern between glacial and interglacial periods, correlating with changes in the mid-latitudinal North Atlantic's surface circulation. Interglacial periods (MIS 49, MIS 47, MIS 43) exhibit a strong influence of warm, oligotrophic waters. The abundances of subtropical species vary between 40% and 65%, whereas tropical species reach up to 10%. The SSTs were around 23.7°C during summer and 18.5°C during winter. In these periods, insolation appears to influence interglacial intensity, peaking at the onset of MIS 47 and MIS 43. In contrast, during cooler MIS 45, the subtropical species only reached values up to 20% and tropical species up to 2%, with temperatures about 21°C in summer and 16°C in winter. The expansion of the subtropical gyre during the interglacials, but also interstadial periods, could have played a significant role in those species’ assemblages and the SST fluctuations.

In contrast, during glacial periods (MIS 50, MIS 48, MIS 46, MIS 44), extreme cold events of short duration were documented, with MIS 50 and MIS 48 recording distinct terminal stadial events. Those short-term episodes were marked by abrupt abundance increases of polar species N. pachyderma up to 40% to 65%, respectively, and SSTs dropping down to 8°C in summer and 5°C in winter. The coldest temperatures were documented during the MIS 48 stadial terminal event and is consistent with alkenone-derived SST data, indicating colder deglacial conditions compared to MIS 46 and MIS 40. The SSTs, and the faunal data, including the increase in cold water calcareous nannofossil taxa, are consistent with evidence of the southward displacement of subpolar waters and the contraction of the subtropical gyre. In addition to the faunal data, changes in the G. bulloides δ18O record reveal a gradual increase of values during MIS 48 and abrupt oscillations during MIS 46, MIS 44, MIS 42, and MIS 40. Overall, we confirm the presence of millennial-scale climate variability during the 41 kyr-world with strong impacts on the planktonic foraminifera fauna and implications for the dimension of the subtropical gyre in the North Atlantic.

How to cite: Duque Castaño, M., Voelker, A. H. L., Rodrigues, T., and Trotta, S.: Millennial-scale climate variability in the 41 kyr world of MIS 50 to MIS 40 (1.5-1.28 Ma): Insights from planktonic foraminifera and sea surface temperature data from the southern Iberian margin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-439, https://doi.org/10.5194/egusphere-egu24-439, 2024.

EGU24-511 | ECS | Orals | CL1.2.5

Precisely dated climate records challenge the Southern Hemisphere glacial aridity paradigm 

Rieneke Weij, Kale Sniderman, Jon Woodhead, John Hellstrom, Josephine Brown, Russell Drysdale, Liz Reed, Steven Bourne, and Jay Gordon

While global changes in temperature during the last 1.5 Ma are well constrained, the terrestrial response to these changes is less understood, particularly in the Southern Hemisphere. Late Pleistocene ice-age climates are routinely characterised as having imposed moisture-stress on low/mid-latitude ecosystems. This idea is largely based on fossil pollen evidence for widespread, low-biomass glacial vegetation, interpreted as indicating climatic dryness. However, woody plant growth is inhibited under low atmospheric CO2, so understanding glacial environments requires the development of new palaeoclimate indicators that are independent of vegetation. Here, we present two new, well-dated speleothem records from subtropical, southern Australia, both spanning the last three glacial-interglacial cycles. We show that, contrary to expectations, over the past ~350 ka, peaks in southern Australian climatic moisture availability were largely confined to glacial periods, including the last glacial maximum, while warm interglacials were relatively dry. By measuring the timing of speleothem growth in the Southern Hemisphere subtropics, which today has a predominantly negative annual moisture balance, we developed a record of climatic moisture availability that is independent of vegetation and extends through multiple glacial-interglacial cycles. Our results demonstrate that a cool-moist response is consistent across the austral subtropics, and in part may result from reduced evaporation under cool glacial temperatures. Insofar as cold glacial environments in the Southern Hemisphere subtropics have been portrayed as uniformly arid, our findings suggest that their characterisation as evolutionary or physiological obstacles to movement and expansion of animal, plant and, potentially, human populations should be reconsidered.

How to cite: Weij, R., Sniderman, K., Woodhead, J., Hellstrom, J., Brown, J., Drysdale, R., Reed, L., Bourne, S., and Gordon, J.: Precisely dated climate records challenge the Southern Hemisphere glacial aridity paradigm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-511, https://doi.org/10.5194/egusphere-egu24-511, 2024.

EGU24-1845 | ECS | Orals | CL1.2.5

Variability of the North Atlantic westerlies during MIS 31-16 (1.1- 0.65 Ma) from SW Iberian margin records 

Xiaowen Quan, Maria Fernanda Sanchez Goñi, Paul Moal-Darrigade, Qiuzhen Yin, and Josue Polanco-Martinez

The driving mechanisms of the middle Pleistocene Transition (MPT) are still unclear but the most likely hypotheses are related to ice-sheet dynamic feedbacks, such as ice albedo, precipitation at the ice margins, elevation-temperature and the regoliths. Here we focus on the “precipitation at the ice margins” hypothesis. To test this hypothesis, we have analysed the pollen content of SW Iberian margin sedimentary sequences that document changes in the direction and intensity of the westerlies during the MPT. In my presentation I will show the pollen-based vegetation and winter rainfall changes in the adjacent landmasses of the southwestern Iberian margin during the MPT. Changes in the reconstructed vegetation from IODP Site U1386 (1.2-0.8 Ma), combined with IODP Site U1385 (0.8-0.67 Ma), and their comparison with changes in the North Atlantic Ocean thermal gradient reveal the variability in the intensity and position of the westerlies and in the position of the moisture source, respectively. Preliminary pollen results reveal a long-term decreasing trend in the Mediterranean forest cover during MIS 31-20 (1.1-0.8 Ma), associated with long-term southward migration of the thermocline water source. This trend abruptly shifted northward at 0.8 Ma, and probably was related to progressive northward shift of the westerlies that bring moisture to the margin of the ice sheets feeding the ice caps, and leading to the shift of the dominant ice sheet cyclicity from 41 kyrs to 100 kyrs.

How to cite: Quan, X., Sanchez Goñi, M. F., Moal-Darrigade, P., Yin, Q., and Polanco-Martinez, J.: Variability of the North Atlantic westerlies during MIS 31-16 (1.1- 0.65 Ma) from SW Iberian margin records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1845, https://doi.org/10.5194/egusphere-egu24-1845, 2024.

EGU24-2423 | ECS | Orals | CL1.2.5

The association of AMOC and Atlantic sea ice in a transient CGCM simulation for the past 2.6 million years. 

Gagan Mandal, Soon-Il An, Axel Timmermann, Kyung-Sook Yun, and Jae-Heung Park

The Quaternary period (0–2.58 million years) is an important time in the early evolution of our human ancestors. This period is featured by distinctive glacial-interglacial cycles, primarily caused by variations in orbital parameters (i.e., eccentricity (100 thousand years (kyr)), obliquity (41 kyr), and precession (23/19 kyr)), atmospheric CO2 concentration (GHG), and their feedbacks. Therefore, it is essential to understand the climate system, mainly focusing on the variability of the Atlantic Meridional Overturning Circulation (AMOC) due to its huge impact.

In this study, we have employed a quasi-continuous simulation to understand the AMOC variability in response to changes in orbital, GHG, and continental ice sheet forcings over the past 2.6 million years. It is found that the AMOC variability is associated with the sea ice coverage and mixed layer depths over the Labrador Sea and Irminger and Iceland basins. The overall mixed layer depth over the Labrador Sea, Irminger, and Iceland basins and the corresponding AMOC variability vary in precession and obliquity periodicity. Meanwhile, the mixed layer depth in the Labrador Sea exhibits a dominant precession, and the Irminger and Iceland basins exhibit a dominant obliquity periodicity. Further, we have divided the entire Quaternary period into three subsets based on the dominant periodicity of the climate state: 0ka–700ka (post-MPT; 100kyr dominant), 700ka–1200ka (MPT; 100–80kyr and 41kyr dominant), and 1200ka–2600ka (pre-MPT; 41kyr dominant). We have found that sea ice coverage and mixed layer depth in the Labrador Sea (Irminger and Iceland basins) are out of (in) phase with a Pearson correlation coefficient of −0.70 (0.42) during post-MPT, −0.78 (0.32) during MPT, and −0.85 (0.38) during pre-MPT periods. These results indicate that during glacial periods, the southward expansion of Labrador sea ice covered the deep convection sites, which impeded deep convection and weakened the AMOC strength. Therefore, the expansion and contraction of Labrador sea ice and its feedback contributed to AMOC variability over glacial‐interglacial cycles for the past 2.6 million years.

How to cite: Mandal, G., An, S.-I., Timmermann, A., Yun, K.-S., and Park, J.-H.: The association of AMOC and Atlantic sea ice in a transient CGCM simulation for the past 2.6 million years., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2423, https://doi.org/10.5194/egusphere-egu24-2423, 2024.

EGU24-3211 | Posters on site | CL1.2.5

The intensity of interglacials during the last 800 kyr 

Eric Wolff, Emilie Capron, Polychronis Tzedakis, Etienne Legrain, Takahito Mitsui, and Qiuzhen Yin

An ultimate target of Quaternary climate studies is to predict the strength and timing of glacial cycles using only the Milankovic forcing as input.  Here we consider just one aspect of this challenge, the intensity of interglacials. Previous work (PIGS Working Group, 2015) has identified 11 interglacials in the last 800 kyr. Are some of them globally strong or weak? Is there a step change at the mid-Brunhes (between MIS 13 and MIS11)? And what controls the observed intensity?

We first discuss what we mean by intensity.  Some datasets (such as mean global temperature or sea level) have a more global character and might be considered more robust indicators of interglacial strength, but are more difficult to estimate compared to simpler parameters such as CO2 concentration and Antarctic temperature.  Many records show “overshoots”, temporary maxima that are followed by longer plateaus of interglacial character.  Despite these complications, some patterns do emerge. In global scale records, MIS 5e, 11, 9, 1 stand out as particularly warm, with 13 and 17 particularly cold. Some terrestrial records show a different pattern with MIS 13 unusually strong in many Asian records.  There is a tendency to more intense interglacials after 450 ka, but MIS 7e and 7c would sit quite happily in the pre-mid-Brunhes pattern.

A first look at the astronomical/orbital context is not encouraging. We see the obvious MIS11 paradox, that weak precessional forcing leads to a strong interglacial (or the opposite, most clearly seen in MIS 15e and 7c). However two different approaches have been quite successful, and may point the way to a more satisfying conclusion. Yin and Berger (2010, 2012) predicted the strength of interglacials using Milankovic forcing plus CO2 concentration as inputs.  This approach suggests that the main cause of stronger interglacials after the mid-Brunhes is higher CO2 and pushes the problem into understanding the controls on the intensity of CO2 maxima. Mitsui et al (2022) used Milankovic forcing plus the strength of the previous glacial. In this model, the tendency to stronger interglacials after the mid-Brunhes arises essentially from a tendency to higher obliquity, as part of a 1.2 Myr cycle. Neither approach views the change across the mid-Brunhes as an ”event” and we propose it should rather be termed a mid-Brunhes “Shift” (MBS).

Here we discuss how we might approach a unified explanation that draws on both models, with periods of highest CO2 perhaps being related to the pattern and timing of AMOC strength during the termination. This is influenced by the size of glacial ice sheets and by orbital intensity through their influence on the amount of freshwater available and the rate at which it is delivered into the ocean.  Finally we consider whether the pattern of obliquity is enough to understand the MBS, i.e. is it part of a longer term oscillation.

How to cite: Wolff, E., Capron, E., Tzedakis, P., Legrain, E., Mitsui, T., and Yin, Q.: The intensity of interglacials during the last 800 kyr, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3211, https://doi.org/10.5194/egusphere-egu24-3211, 2024.

EGU24-3722 | Orals | CL1.2.5 | Milutin Milankovic Medal Lecture by Peter U. Clark

A Revisionist View of the Mid-Pleistocene Transition 

Peter U. Clark, Jeremy Shakun, Yair Rosenthal, David Pollard, Peter Köhler, Steven Hostetler, Patrick Bartlein, Zhengyu Liu, Chenyu Zhu, Daniel Schrag, and Nicklas Pisias

The Mid-Pleistocene Transition (MPT) is commonly characterized as a change in both temperature and ice volume from smaller amplitude, 41-kyr variability to higher amplitude, ~100-kyr variability in the absence of any significant change in orbital forcing. Here we reassess these characteristics based on our new reconstructions of changes in global mean surface temperature (DGMST) and global mean sea level over the last 2.5 Myr. Our reconstruction of DGMST includes an initial phase of long-term cooling through the early Pleistocene followed by a second phase of accelerated cooling during the MPT (1.5-0.9 Ma) that was accompanied by a transition from dominant 41-kyr low-amplitude periodicity to dominant ~100-kyr high-amplitude periodicity. Changes in rates of long-term cooling and variability are consistent with changes in the carbon cycle driven initially by geologic processes followed by additional changes during the MPT in the Southern Ocean carbon cycle. The spectrum of our sea-level reconstruction is dominated by 41-kyr variance until ~1.2 Ma with subsequent emergence of a ~100-kyr signal that, unlike global temperature, has nearly the same concentration of variance as the 41-kyr signal during this time. Moreover, our sea-level reconstruction is significantly different than all other reconstructions in showing fluctuations of large ice sheets throughout the Pleistocene as compared to a change from fluctuations in smaller to larger ice sheets during the MPT. We attribute their longer period variations after the MPT to modulation of obliquity forcing by the newly established low-frequency CO2 variability. Specifically, prior to reaching their maximum size at the end of each ~100-kyr interval, ice-sheet response to periods of lower CO2 was modulated by higher obliquity, and vice versa, with the times of maximum ice-sheet growth only occurring when low CO2 combined with the next obliquity low. Ice sheets then began to melt in response to the next increase in obliquity, with the subsequent sequence of events and feedbacks leading to a termination. High-resolution ice-core CO2 records that extend beyond 0.8 Ma are needed to test this hypothesis. Otherwise, large ice sheets shared a common size threshold throughout the Pleistocene equivalent to sea level below -80 m that, when exceeded, resulted in a termination that was paced by the next increase in obliquity.

How to cite: Clark, P. U., Shakun, J., Rosenthal, Y., Pollard, D., Köhler, P., Hostetler, S., Bartlein, P., Liu, Z., Zhu, C., Schrag, D., and Pisias, N.: A Revisionist View of the Mid-Pleistocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3722, https://doi.org/10.5194/egusphere-egu24-3722, 2024.

EGU24-3753 | Orals | CL1.2.5

Simulating Antarctic ice-sheet variability of the past 3 million years 

Kyung-Sook Yun and Axel Timmermann

Little is known about the evolution of the Antarctic ice-sheet (AIS) during the Pleistocene and its response to external drivers, such as CO2, orbital and sea-level forcing. Here, we apply realistic transient climate forcings generated by the 3Ma Community Earth System model (CESM, version 1.2) simulation [1],[2] to the bi-hemispheric Pen State University ice-sheet shelf model (PSUIM). The CESM-simulated surface air temperature, surface solar insolation, precipitation, and sub-surface ocean temperature serve as inputs for PSUIM. This application enables us to simulate a more reliable variability of the AIS over the past 3 million years ago (Ma). Our simulation reveals a more pronounced precessional modulation of early to mid-Pleistocene AIS variability than previously suggested. The results further show the mid-Pleistocene transition (MPT, ~ 1Ma) of AIS, with dominant frequencies changing  from 20-40 kyrs to 80-120 kyrs and a clear regime shift in its surface mass balance. We also find that the pre-MPT precessional variability is significant only in the marine (floating) ice-sheet, not in terrestrial (grounded) ice. This suggests the influence of competing ocean and atmospheric processes in controlling the AIS variability over the past 3Ma. We will further discuss the mechanisms of simulated AIS variability and its climate interactions on orbital timescales and compare our results with paleo reconstructions.

 

[1] 3Ma-Data: Transient CESM1.2 model simulation data over the 3 million years ago (Ma),   https://climatedata.ibs.re.kr/data/3ma-transient-climate-simulation, doi:10.22741/iccp.20230001.

[2] Yun, K.-S., Timmermann, A., et al. (2023), A transient coupled general circulation model (CGCM) simulation of the past 3 million years, Clim. Past, 19, 1951–1974, https://doi.org/10.5194/cp-19-1951-2023.

 

How to cite: Yun, K.-S. and Timmermann, A.: Simulating Antarctic ice-sheet variability of the past 3 million years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3753, https://doi.org/10.5194/egusphere-egu24-3753, 2024.

EGU24-4211 | ECS | Orals | CL1.2.5

CO2-forced change in glacial response to precession likely causes the Middle-Pleistocene Transition and ~100-kyr glacial cycles 

Zhifeng Zhang, Yongjian Huang, Chao Ma, Qiuzhen Yin, Hanfei Yang, Eun Young Lee, Hai Cheng, Benjamin Sames, Michael Wagreich, Qingping Liu, Tiantian Wang, and Chengshan Wang

Around ~800-1200 ka, the transition of glacial-interglacial cycles from earlier ~40-kyr into later ~100-kyr cyclicities without obvious changes in orbital parameters, known as the Middle-Pleistocene Transition (MPT), suggests that Earth’s internal factors, in addition to external astronomical forcing, are also essential for the glacial cycles. However, it is still unclear how internal and external factors interact to lead to the MPT and the ~100-kyr cycle. Here, we statistically analyzed the power spectral relationship between the ~21-kyr, ~41-kyr, and ~100-kyr components within 57 paleoclimate archives and reconstructed the astronomical phase relative to the maximal changing rate of benthic foraminifer oxygen isotopes (δ18O) over the past 2700 ka to explore the role of astronomical forcings in driving glacial cycles and their relationship with internal factors. The statistical results show that the ~21-kyr power ratio complements the ~100-kyr power ratio. The precession phase covaries with pCO2-modulated glacial dynamics and exhibits a contrasting correlation with the precession power ratio of benthic δ18O before and after ~1500 ka. These findings suggest that pCO2-modulated latitudinal extension of the icesheets determined the glacial response to precession. Around 1500 ka, the response apparently shifted into a nonlinear mode, enabling the gradual extension of glacial cycles into ~100-kyr periodicities at the expense of precession power, which signified the onset of the ~100-kyr glacial cycles. Our study confirms the nonlinear precession origin of ~100-kyr glacial cycles, featuring the possible low- and high-latitude interplay at the precession band.

How to cite: Zhang, Z., Huang, Y., Ma, C., Yin, Q., Yang, H., Lee, E. Y., Cheng, H., Sames, B., Wagreich, M., Liu, Q., Wang, T., and Wang, C.: CO2-forced change in glacial response to precession likely causes the Middle-Pleistocene Transition and ~100-kyr glacial cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4211, https://doi.org/10.5194/egusphere-egu24-4211, 2024.

EGU24-5365 | ECS | Orals | CL1.2.5

Temperature and salinity changes in the abyssal Atlantic and Pacific Oceans over the Middle Pleistocene Transition 

Nicola Thomas, David Hodell, Heather Ford, and Mervyn Greaves

Ocean thermohaline circulation (THC) is driven by temperature and salinity in source areas of deep-water formation. THC underwent a fundamental change ~950 to 860 thousand years ago (ka) during the Middle Pleistocene Transition (Pena and Goldstein, 2014). However, the relative contributions of temperature (‘thermo-’) versus salinity ('haline’) change to this fundamental THC reorganization remain unclear. Here we compiled North Atlantic and Pacific Ocean stacks of deep-water temperature (estimated using foraminiferal Mg/Ca) and salinity (estimated from δ18Oseawater) for the past 1.5-million-years (Myr). The deep North Atlantic became colder and the deep Pacific saltier during glacial periods younger than ~900 ka. Cooling of northern sourced water likely led to increased salinity of southern sourced water by decreasing the melting of land-based ice around Antarctica (Adkins, 2013) and increasing sea ice formation and associated brine rejection. With increased stratification the abyssal ocean became a more effective carbon trap lowering the concentration of atmospheric pCO2, thereby permitting ice sheets to grow larger and lengthening the glacial cycle. Expansion of Antarctic ice sheets would have also contributed to increasing the salinity of southern source areas as Antarctica shifted from dominantly terrestrial melting to marine-based calving margins (Raymo et al., 2006). Our temperature and salinity reconstructions support a fundamental reorganization of the density structure and stratification of the abyssal glacial ocean across the Middle Pleistocene Transition.

 

References:

Adkins, J.F. (2013) ‘The role of deep ocean circulation in setting glacial climates’, Paleoceanography, 28(3), pp. 539–561. Available at: https://doi.org/10.1002/palo.20046.

Pena, L.D. and Goldstein, S.L. (2014) ‘Thermohaline circulation crisis and impacts during the mid-Pleistocene transition’, Science, 345(6194), pp. 318–322. Available at: https://doi.org/10.1126/science.1249770.

Raymo, M.E. et al. (2006) ‘Plio-Pleistocene Ice Volume, Antarctic Climate, and the Global’, Nature, 313(July), pp. 492–495. Available at: https://doi.org/10.1126/science.1123296.

 

How to cite: Thomas, N., Hodell, D., Ford, H., and Greaves, M.: Temperature and salinity changes in the abyssal Atlantic and Pacific Oceans over the Middle Pleistocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5365, https://doi.org/10.5194/egusphere-egu24-5365, 2024.

EGU24-5630 | ECS | Orals | CL1.2.5

Inferring past temperature from δ15N measurements in air bubbles trapped in Antarctic ice 

Marie Bouchet, Amaëlle Landais, Frédéric Parrenin, Etienne Legrain, Emilie Capron, Antoine Grisart, Frédéric Prié, Thomas Extier, Roxanne Jacob, Aurélien Quiquet, Christophe Dumas, and Anna Klüssendorf

Ice cores are unique archives capturing records of past temperature (through the ice isotopic composition, e.g. δD) and past atmosphere composition over the last 800 kyr. In particular, their analysis revealed that glacial-interglacial transitions, altering the Earth's climate since the beginning of the Quaternary, are associated with significant variations in the atmospheric levels of CO2 and CH4. However, comparison of past temperatures imprinted in ice-phase and atmospheric composition records imprinted in the air-phase is difficult. Indeed, the air is trapped at a depth of 50-100 m, at the bottom of the firn, where snow transforms into ice. Therefore, at a given depth, the air is always younger than the ice and firn densification modeling is needed to estimate the age difference between the air and the ice at each level. Firn densification modeling is associated with large uncertainties when it is applied to low accumulation and low temperature drilling sites of the East Antarctic plateau.

An alternative approach to reconstruct air temperature directly in the air bubbles involves analyzing the isotopic composition of N2 (δ15N). Indeed, local temperature and accumulation rate evolutions affect firn thickness and hence modulated the δ15N in air bubbles trapped at the bottom of the firn via gravitational enrichment of δ15N over large glacial-interglacial transition on the East Antarctic plateau. The observation of a robust correlation between ice core records of δ15N and δD (Dreyfus et al., 2010) confirms the strong influence of local climate on the δ15N. δ15N measurements have already been applied to determine the phasing between CO2 and temperature increases over Antarctic temperature increase associated with glacial terminations. However, this strong relationship between δ15N and δD is not necessarily valid outside of glacial terminations. Here, we address the question to what extent the δ15N can be used to infer past temperatures and to study the CO2-temperature relationship, hence circumventing age uncertainties that arise when comparing ice and gas phase measurements.

We first examine the δ15N record from EPICA Dome C with respect to East Antarctic climate over the last eight glacial-interglacial cycles. We use the good agreement between δD and δ15N over Termination II as a satisfactory criterion to discern when the δ15N is a reliable proxy of past temperature. Using this criterion, we assert that the correlation between δ15N and δD is robust over the past eight terminations. Focusing on the 100-300 ka BP period, we note also three intervals characterized by a weak correlation: the glacial inceptions from MIS 7e to 7d and 7a to 6e, and the MIS 6 glacial period. To explain why δ15N and δD evolutions contrast over these periods, we connect water stable isotopes with new δ15N measurements from EDC ice core and explore various snow densification scenarios yielded by a firn model under different climate conditions at the ice sheet surface. Our study permits to identify a criterion to safely use δ15N as an indicator of the past temperature in the air bubbles of the EDC ice core to study the CO2-local temperature relationship.

How to cite: Bouchet, M., Landais, A., Parrenin, F., Legrain, E., Capron, E., Grisart, A., Prié, F., Extier, T., Jacob, R., Quiquet, A., Dumas, C., and Klüssendorf, A.: Inferring past temperature from δ15N measurements in air bubbles trapped in Antarctic ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5630, https://doi.org/10.5194/egusphere-egu24-5630, 2024.

EGU24-5995 | Orals | CL1.2.5

Little glacial/interglacial net change in Southern Ocean bioproductivity over termination II - an integrated sulfate isotope ice core perspective 

Hubertus Fischer, Andrea Burke, James Ray, Patrick Sugden, Eric Wolff, Helena Pryer, Emily Doyle, Mirko Severi, Bradley Markle, Maria Hörhold, Johannes Freitag, Birthe Twarloh, and Tobias Erhardt

Glacial export productivity in the glacial Southern Ocean may have been enhanced due to iron fertilization from aeolian dust input. Marine sediments indicate such a glacial increase north of the modern Antarctic Polar Front but reduced biogenic activity and reduced nitrogen supply by upwelled deep waters south of it. Due to the sparsity of Southern Ocean sediment data, deriving an overall estimate of marine productivity changes is, however, difficult to achieve. Due to their larger spatial footprint, additional information on basin-wide productivity changes can be obtained from marine biogenic aerosol tracers in Antarctic ice cores.

We use SO42- concentrations and its sulfur isotopic composition as well as other geochemical tracers in the EPICA Dronning Maud Land (EDML) ice core in the Atlantic Sector of the Southern Ocean (AS-SO) to provide the first complete glacial/interglacial source decomposition of total SO42- from the penultimate glacial to the last glacial inception. Our isotopic source decomposition shows that despite other (e.g. terrestrial) sources being significant contributors to total SO42- during glacial times, biogenic SO42- production is always the dominant source at EDML. Using information on recent dimethylsulfide emissions and aerosol forward modeling, we can show that biogenic sulfate recorded in the EDML ice core is derived from the AS-SO south of 35°S but the major source lies south of 50°S, i.e., mainly the seasonal sea ice zone. During the penultimate glacial these sources shifted about 4° northward in parallel to sea ice expansion.

Taking reduced wet deposition of biogenic sulfate aerosol during glacial times into account, we can show that the biogenic sulfate production during the Penultimate Glacial Maximum and the Last Interglacial integrated over the AS-SO may have been only slightly higher in the penultimate glacial and differed by less than 15%. We see millennial biogenic sulfur changes of the same order during the Last Interglacial, which we attribute to temporal changes in the seasonal sea ice zone. An early interglacial productivity minimum in our biogenic sulfate record parallels within age uncertainties features previously reported in the literature, i.e., a minimum in winter, thus seasonal, sea ice extent, a stagnation event in Antarctic Bottom Water and a maximum in summer surface temperature encountered during the early LIG.

How to cite: Fischer, H., Burke, A., Ray, J., Sugden, P., Wolff, E., Pryer, H., Doyle, E., Severi, M., Markle, B., Hörhold, M., Freitag, J., Twarloh, B., and Erhardt, T.: Little glacial/interglacial net change in Southern Ocean bioproductivity over termination II - an integrated sulfate isotope ice core perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5995, https://doi.org/10.5194/egusphere-egu24-5995, 2024.

EGU24-6781 | ECS | Orals | CL1.2.5

Late Pliocene and Early Pleistocene CO2 and CH4 from ice cores from the Allan Hills, Antarctica 

Julia Marks Peterson, Sarah Shackleton, Jeffrey Severinghaus, Edward Brook, John Higgins, Andrei Kurbatov, Yuzhen Yan, Christo Buizert, Michael Kalk, Ross Beaudette, Austin Carter, Jenna Epifanio, and Jacob Morgan

Currently, chronologically discontinuous ice cores from the Allan Hills Blue Ice Area (BIA), Antarctica, are our only direct insight into the atmospheric composition of periods beyond the continuous ice core record (800 ka BP). An accurate and precise greenhouse gas history beyond 800 ka would aid understanding of the mechanisms involved in the climatic transitions across the late Pliocene and early Pleistocene. Here we present carbon dioxide (CO2) and methane (CH4) results from a new core from the Allan Hills BIA (ALHIC1901). The bottom 25 m of ALHIC1901 contain 52 sampled depths with co-registered 40Aratm dates (Shackleton et al. in prep), measurements of δD of ice, δ18Oatm, and concentrations of CO2 and CH4 in trapped air. Of these samples, 25 are older than the continuous ice core record, with ages from 821 ± 80 ka to 2700 ± 270 ka. The bottom meter contains ice from the Pliocene with ages from 2700 ± 270 ka to 4000 ± 400 ka. The carbon isotope ratio of CO213C-CO2) was measured on 18 samples to examine the possibility of input of non-atmospheric CO2 from oxidation of organic matter. Our results indicate that CO2 and CH4 levels were similar in the early Pleistocene to those found for the last 800 ka. A small decline of approximately 20 ppm is seen in CO2 across the Pleistocene, and no secular trend is observed in CH4. Pliocene-aged samples appear to contain a mixture of atmospheric CO2 and CO2 derived from respiration of organic matter at the glacier bed. Using an isotope mixing model we estimate that atmospheric CO2 was lower than 350 ppm at ~3.1 Ma,

How to cite: Marks Peterson, J., Shackleton, S., Severinghaus, J., Brook, E., Higgins, J., Kurbatov, A., Yan, Y., Buizert, C., Kalk, M., Beaudette, R., Carter, A., Epifanio, J., and Morgan, J.: Late Pliocene and Early Pleistocene CO2 and CH4 from ice cores from the Allan Hills, Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6781, https://doi.org/10.5194/egusphere-egu24-6781, 2024.

EGU24-8041 | Orals | CL1.2.5

Progress report on Beyond EPICA – oldest ice (BE-OI) Little Dome C (LDC) activity 

Frank Wilhelms and the LDC field parties 2022/2023 & 2023/2024, drill & science workpackage, stable isotope field measurements group

The European Project for Ice Coring in Antarctica (EPICA) Beyond EPICA – oldest ice aims at retrieving a continuous ice core record of climate feedback and forcing spanning about 1.5 Ma back in time. After determining a suitable drill-site LDC during an extensive pre-site survey 35 km southwest of Concordia station, we are in the second deep drilling season. At the time of submission of this abstract, we penetrated beyond 1604.92 m, roughly spanning one glacial-interglacial cycle. We will report on the drilling and core processing activities and verify the prognostic age scale by comparison with dielectric profiling (DEP) and stable isotope saw dust measurements in the field.

How to cite: Wilhelms, F. and the LDC field parties 2022/2023 & 2023/2024, drill & science workpackage, stable isotope field measurements group: Progress report on Beyond EPICA – oldest ice (BE-OI) Little Dome C (LDC) activity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8041, https://doi.org/10.5194/egusphere-egu24-8041, 2024.

The Arctic Ocean is one of Earth's most dynamically evolving regions, especially for orbital timescale during the Quaternary marked by the waxing and waning of continental ice sheets in the circum-Arctic. The consequential environmental shifts have been imprinted in marine sedimentary deposits in the Arctic Ocean, rendering them invaluable for paleoclimatic and paleoceanographic subjects. Despite their potential significance, the accurate chronology of these sediment records remains debatable due to numerous uncertainties from different dating methods, resulting in difficulties in paleoenvironmental reconstruction. Even widely used absolute age measurement techniques, for example, such as radiocarbon dating using calcareous microfossils, have exhibited limitations in certain cases. To address these challenges and enhance the precision of age determination for Arctic Ocean marine sediments, this study aims to assess and compare various dating methods comprehensively. By critically examining their strengths and weaknesses, it can be sought to establish a more robust framework for constraining the ages of marine sedimentary sequences in the Arctic Ocean. Additionally, this research endeavors to explore the implications of improved chronological accuracy for reconstructing paleoenvironmental conditions in the Arctic Ocean. By refining the timeline of past events, it can be anticipated that a clearer picture of the interplay between ice sheet dynamics, oceanic circulation, and climatic variations will emerge.

How to cite: Park, K.: Stratigraphic correlation across the western to central Arctic Ocean for Quaternary Paleoenvironmental reconstruction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8220, https://doi.org/10.5194/egusphere-egu24-8220, 2024.

EGU24-8444 | Orals | CL1.2.5

A 1.4 Myr record of export production at the Pacific entrance of the Drake Passage considering syndepositional redistribution of sediments 

Maria H. Toyos Simon, Frank Lamy, Carina B. Lange, Jordan T. Abell, Lester Lembke-Jene, Helge W. Arz, and Gisela Winckler

Increased export production in the Subantarctic Zone of the Southern Ocean has been proposed as a key mechanism for explaining carbon drawdown during glacial times. Therefore, reconstructions of oceanic particle fluxes from the sedimentary record in this sector are vital. Traditionally, fluxes of various materials to the seafloor have been estimated from stratigraphy-based mass accumulation rates (MARs), which are calculated using a combination of sediment dry bulk density and linear sedimentation rates between dated sediment horizons. We refer to these MARs here as age model-derived bulk MAR (BMARs). However, BMARs and any resulting paleoceanographic interpretations may suffer from substantial errors if lateral redistribution of sediments is not considered. In fact, this is expected to be a common phenomenon in the Southern Ocean due to the strong bottom water circulation of the Antarctic Circumpolar Current. Here, using material from a marine sediment core recovered at the Pacific entrance of the Drake Passage, we evaluate export production and its drivers over the past 1.4 million years by applying several paleoproductivity indicators (biogenic barium, organic carbon, biogenic opal, calcium carbonate, and iron). Crucially, we determine MARs of these various sediment components that are corrected for the lateral movement of sediments that occurred simultaneously to or soon after initial deposition. The results show that the export production indicators varied according to some of the characteristic features of the main climatic events of Earth over the past 1.4 Ma. (The Mid-Pleistocene Transition and Mid-Brunhes Event). Additionally, the productivity response in the area was enhanced (weakened) during globally strong (faint) glacials or interglacials (e.g., MIS 16, MIS 11, MIS 5, and the Holocene for strong and MIS 15-12 for weak responses, respectively).

How to cite: Toyos Simon, M. H., Lamy, F., Lange, C. B., Abell, J. T., Lembke-Jene, L., Arz, H. W., and Winckler, G.: A 1.4 Myr record of export production at the Pacific entrance of the Drake Passage considering syndepositional redistribution of sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8444, https://doi.org/10.5194/egusphere-egu24-8444, 2024.

EGU24-9245 | ECS | Posters on site | CL1.2.5

Simulating ice sheets during Pleistocene glacial cycles: A dance of CO2, ice and orbital cycles 

Meike D.W. Scherrenberg, Roderik S.W. van de Wal, and Constantijn J. Berends

During the Mid Pleistocene Transition (MPT; 1.2-0.7 Ma) glacial cycle periodicity shifted from 40 thousand years (ka) to an average 100 ka. While orbital cycles have a large influence on glacial cycle periodicity, the MPT took place without any clear change in the power spectrum of the orbital forcing. This suggests that the MPT must have resulted from Earth system processes rather than a change in external forcing.

In this study, we use an ice-sheet model to simulate the evolution throughout the past 1.5 million years of the Laurentide, Eurasian, Greenland and Antarctic ice sheets. We force the model with last glacial maximum and pre-industrial climate time-slices from the PMIP4, which are interpolated according to prescribed CO2 and insolation reconstructions, as well as modelled ice-sheet geometry, thereby implicitly including the temperature-albedo and precipitation-topography feedbacks.

We show that forcing the model with the combination of CO2 and insolation can capture the 40 ka cycles before the MPT and the 100 ka cycles after the MPT, without requiring a change in the ice-sheet model set-up. Deglaciations are initiated when the combination of CO2 and insolation creates a warm enough climate. Before the MPT, these conditions are met in almost all 40 ka cycles, as interglacial CO2 levels are high enough to cause deglaciations. After the MPT, interstadial CO2 levels tend to be low enough not to trigger a deglaciation during orbital maxima, resulting in longer glacial cycles. Results are most sensitive to the parameterization of the basal friction. Increased basal friction leads to more merged cycles before the MPT. Decreased basal friction will result in an increased likelihood for interstadial CO2 and insolation levels to result in complete melt of the North American ice sheet.

How to cite: Scherrenberg, M. D. W., van de Wal, R. S. W., and Berends, C. J.: Simulating ice sheets during Pleistocene glacial cycles: A dance of CO2, ice and orbital cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9245, https://doi.org/10.5194/egusphere-egu24-9245, 2024.

EGU24-9485 | ECS | Orals | CL1.2.5

Late Pleistocene hydroclimatic and vegetation changes in Northeast Brazil: which role played the western tropical Atlantic? 

Louis Rouyer-Denimal, Aline Govin, Ioanna Bouloubassi, Ana Luiza Albuquerque, Thanh Thuy Nguyen Tu, Magloire Mandeng-Yogo, Christelle Anquetil, and Arnaud Huguet

   Nowadays, the hydroclimate of the semi-arid Northeast Brazil is tightly linked with, inter alia, temperature of the adjacent Atlantic Ocean and its interactions with the Atmosphere. The short humid season peaks in April while (i) the intertropical convergence zone (ITCZ) is at its southernmost position, (ii) the southern tropical Atlantic is warm and (iii) the southeast trade winds are weak. Uncertainties remain on past long-term hydroclimate changes and on the drivers controlling these variations in the NE Brazil region. One of the reasons is the lack of available long-term paleoclimate records.

   Very recently, we reconstructed ocean temperature changes in the western tropical Atlantic on glacial-interglacial time scales and highlighted relatively cold (warm) upper ocean waters during glacial (deglacial and interglacial) intervals over the last 300 000 kyr1. It remains unknown how these changes impacted the NE Brazilian hydroclimate on orbital time scales. This work aims at examining the response of continental vegetation to variations in the western tropical Atlantic heat content over the last two climatic cycles. We used the same sedimentary core (GL-1180) collected off the NE Brazilian margin on which temperature reconstructions were conducted.

   We developed a multi-proxy approach at a 2 kyr temporal resolution to reconstruct the sources and the composition of the sedimentary organic matter (OM) produced on-land and within the water column at both bulk and molecular scales. We first investigated the organic signature of present-day dry (caatinga) and humid (Atlantic tropical forest) vegetation in our study area using modern litter samples. After statistical investigations, we developed new local vegetation proxies based on the relative abundance of long-chain n-alkanes (n-C33/[n-C29+n-C31+n-C33]), n-alkenes (n-C27/[n-C27+n-C28]) and n-alkan-1-ols (n-C28/[n-C28+n-C30]). Secondly, we reconstructed vegetation dynamics and hydroclimate changes using these new proxies together with the bulk elemental (%Corg, %Ntot) and isotopic (δ13Corg, δ15Ntot) composition and the molecular isotopic composition (δ13C) of specific C29 and C31 n-alkanes. We found that a caatinga-like dry vegetation expanded during arid glacial periods while humid conditions prevailed over interglacial intervals in agreement with previous regional studies. Comparing our vegetation and upper ocean temperature records, we highlighted that continental humid (arid) conditions occured during intervals of warm (cold) western tropical Atlantic and weak (strong) southeast trade winds.

   In conclusion, our work highlights glacial-interglacial vegetation and hydroclimate changes in NE Brazil. It further shows that the heat content of the tropical Atlantic was a major driver of these changes over the last 300 000 kyr. In addition, we suggest that the three major features (Atlantic heat content – ITCZ – SE trades) were likely controlling together hydroclimate changes and vegetation dynamics over, at least, the last two climatic cycles.

1Rouyer-Denimal et al., 2023. QSR 321, DOI: 108370. 10.1016/j.quascirev.2023.108370

How to cite: Rouyer-Denimal, L., Govin, A., Bouloubassi, I., Albuquerque, A. L., Nguyen Tu, T. T., Mandeng-Yogo, M., Anquetil, C., and Huguet, A.: Late Pleistocene hydroclimatic and vegetation changes in Northeast Brazil: which role played the western tropical Atlantic?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9485, https://doi.org/10.5194/egusphere-egu24-9485, 2024.

EGU24-10240 | ECS | Posters on site | CL1.2.5

Signal Preservation in the Deepest Part of the EPICA Dome C Ice Core and Application to Palaeoclimate Reconstruction from 600,000 to 800,000 years ago 

Anna Klüssendorf, Amaëlle Landais, Mathieu Casado, Grégory Teste, Frédéric Prié, Marie Bouchet, and Romilly Harris Stuart

In the framework of the new ice core project Beyond EPICA an ice core is currently being drilled to provide a climate record extending over the past 1.5 million years. This ice core will cover the Mid-Pleistocene Transition (~1.2 − 0.8 million years before present) where the glacial-interglacial cycles shifted from following the obliquity to the eccentricity periodicity, as well as the Marine Isotope Stage 19 interglaciation which is considerably the best analogue for a natural Holocene climate regarding the orbital configuration. However, dating the old ice and the interpretation of the climate signal is hampered by extensive annual layer thinning at that depth, high basal temperatures close to melting point, and long residence time favouring diffusive exchanges leading to muted signals even if high-resolution data can be obtained. We are particularly concerned by the possible diffusion of the δ(O2/N2) and δ18O of O2 signals in the deepest part since these two parameters, measured in the air bubbles, are essential tools to provide dating of the deep part of the ice core. To investigate how these signals will be preserved in the bottom part of the ice core after diffusion, we present new high-resolution records of the elemental and isotopic composition of O2 and N2 from the deepest 200 m of the EPICA Dome C ice core spanning over the period from 600,000 to 800,000 years before present. We address the effect of diffusion by comparing the amplitude of the orbital scale variability of the δ(O2/N2) and δ18O of O2 signals in the deepest part of the EPICA Dome C ice core to the expected amplitude of these signals without diffusion and propose some perspectives for the analysis of the Beyond EPICA ice core.

How to cite: Klüssendorf, A., Landais, A., Casado, M., Teste, G., Prié, F., Bouchet, M., and Harris Stuart, R.: Signal Preservation in the Deepest Part of the EPICA Dome C Ice Core and Application to Palaeoclimate Reconstruction from 600,000 to 800,000 years ago, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10240, https://doi.org/10.5194/egusphere-egu24-10240, 2024.

EGU24-11250 | Orals | CL1.2.5

Reinforced precipitation in Eurasia as an important feedback mechanism contributing to the Middle Pleistocene Transition ice-sheet expansion 

Maria Fernanda Sanchez Goñi, Thomas Extier, Josué M. Polanco-Martinez, Coralie Zorzi, Teresa Rodrigues, and André Bahr

The late Middle Pleistocene Transition (MPT, ~ 800-670 thousand years before present, ka) was characterised by the emergence of large glacial ice-sheets associated with anomalously warm  mid North Atlantic sea surface temperatures (SST) enhancing moisture production. Still, the moisture transport across Eurasia towards high northern latitudes is poorly constrained despite its potential role as feedback mechanisms feeding the ice caps. To reconstruct late MPT moisture production and spreading, we combine records of upper ocean temperature and pollen-based Mediterranean forest cover, a tracer of westerlies and precipitation, from a subtropical drill-core collected off SW Iberia Margin, with records of East Asia summer monsoon (EASM) strength and West Pacific surface temperatures, and compare them with the iLOVECLIM model simulations. We observe that the strongest Mediterranean forest development occurred during Marine Isotope Stage (MIS) 17, centered at 700 ka, reflecting a high amount of regional winter precipitation. In contrast, MIS 19 (~785 ka), under the influence of both similar ice volume and higher atmospheric CO2 concentration, is marked by limited forest expansion indicating lower winter precipitation in SW Europe compared to MIS 17. More interestingly, the MIS 18 glacial was more forested, reflecting stronger winter rainfall, compared to the preceding MIS 19, despite that the latter interglacial was characterised by higher insolation, sea level, atmospheric CO2 concentrations and similar warm SST. The long-term increasing trend in winter precipitation in SW Europe parallels the trend of the EASM strength that reached high levels during MIS 18. The model results show high amount of winter rainfall in SW Europe and enhanced EASM (based on the modelled East Asian δ18Ocalcite and summer precipitation) for the three MISs. Similar SW European tree fraction percentages are also modelled during MIS 18 and MIS 19, as inferred from the pollen data. In contrast to the proxy data, the simulated tree fraction is the weakest during MIS 17. The simulated winter rainfall is the highest during MIS 17, but the simulated EASM is the lowest during MIS 18. This mismatch between model and proxy reconstructions could be explained by the difficulty in quantitatively estimating the forest cover from pollen data and/or the result of a feedback process that is not well reproduced in the model such as the poor prediction of the intensity and position of the oceanic moisture source despite a robust SST simulation. Here the data show that SW European winter precipitation and EASM strength reached high levels during the MIS 18 glacial. We explained that this anomalous situation was caused by nearly-continuous moisture supply from both Pacific and Atlantic oceans and its transport to higher latitudes through the westerlies, likely fueling the accelerated expansion of northern hemisphere ice-sheets during the late MPT.

How to cite: Sanchez Goñi, M. F., Extier, T., Polanco-Martinez, J. M., Zorzi, C., Rodrigues, T., and Bahr, A.: Reinforced precipitation in Eurasia as an important feedback mechanism contributing to the Middle Pleistocene Transition ice-sheet expansion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11250, https://doi.org/10.5194/egusphere-egu24-11250, 2024.

The Mid-Pleistocene Transition (MPT) is a period marked by significant changes in the LR04 benthic δ18O record. During this interval (ca. 1.25-0.65 Ma), glacial cycles shifted from symmetrical 41-thousand-year (kyr) cyclicity to asymmetrical 100-kyr cycles. This transition was characterized by a number of large-scale ice sheets, including terrestrial-based ice sheets in the northern hemisphere (e.g.,  the Laurentide and Greenland ice sheets) and a marine-based ice sheet in the southern hemisphere (e.g., the West Antarctic Ice Sheet). Since these different ice sheets respond to climate variability in unique ways, the LR04  stack may fail to capture certain aspects of regional cryospheric behavior across the MPT. Specifically, a potential lag in ice-rafted debris (IRD) fluxes, hinting at possible bipolarity in glacial terminations. This study aims to investigate glacial weathering fluxes from West Antarctica across the MPT by constructing an osmium isotope chemostratigraphic record in conjunction with published IRD records from IODP site U1536 in Iceberg Alley, in the Scotia Sea. This record will be compared to a previously published record from the IRD Belt in the North Atlantic. By examining glacial weathering products in regions with high accumulation of glacially-derived debris, these two records will provide a comprehensive comparison of cryospheric behavior in the North and South Atlantic across the MPT. This new dataset will offer a more detailed perspective of global cryospheric behavior during the MPT and may reveal synchronicity between the two hemispheres.

How to cite: Goss, G. and Rooney, A.: Investigating glacial weathering fluxes from West Antarctica across the Mid-Pleistocene: Insights from  Os isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11738, https://doi.org/10.5194/egusphere-egu24-11738, 2024.

EGU24-11973 | ECS | Posters on site | CL1.2.5

Sea-ice variability along the Antarctic continental margin since the Last Penultimate Glacial  

Wee Wei Khoo, Juliane Müller, Oliver Esper, Wenshen Xiao, Christian Stepanek, Paul Gierz, Gerrit Lohmann, Walter Geibert, and Gesine Mollenhauer

Antarctic sea ice plays a crucial role in buttressing ice shelves, enhancing their stability, and protecting them from potential catastrophic collapse – a significance underscored by recent calving events along the Antarctic Peninsula. Presence or absence of sea ice in the Southern Ocean, and details of its distribution patterns, therefore have relevance far beyond the realm of high latitudes of the Southern Hemisphere. Investigating past sea-ice conditions in proximity to ice shelves, and changes in sea ice distribution over time, particularly across glacial-interglacial cycles, is therefore essential. We may gain insights into the sea-ice’s response to a changing climate, and address gaps in our understanding of ocean-sea ice-ice shelf interactions and dynamics. In our study, we adopt a multiproxy approach to explore glacial-interglacial environmental variability since the Last Penultimate Glacial close to the Antarctic continental margin in the Weddell Sea. We analyze the novel sea-ice biomarker IPSO25 (a di-unsaturated highly branched isoprenoid (HBI)), open-water biomarkers z-/e-trienes (tri-unsaturated HBI), diatom assemblages and primary productivity proxies in a marine sediment core (PS118_63-1) retrieved from Powell Basin in the northwestern Weddell Sea. These biomarkers are reliable proxies for reconstructing near-coastal sea-ice conditions in the Southern Ocean, where the use of sea ice-related diatoms may be subject to bias due to silica dissolution. We present the first continuous record of ice-proximal Antarctic sea ice since the Last Penultimate Glacial. Our results unveil a highly dynamic environment, characterized by significant shifts from a climate with perennial (sea) ice cover to more seasonal sea-ice cover and open ocean conditions, over the last approximately 145 kyrs. Furthermore, to gain a better understanding of the spatial heterogeneity of sea-ice distribution and sea ice-ice shelf system dynamics in the Southern Ocean, we use numerical climate modeling to expand our view across the Southern Ocean, while comparing data from marine cores PS67/219-1 (southern Scotia Sea) and PS128_14 (eastern Weddell Sea) helps track latitudinal sea-ice changes and identify common forces driving sea ice-ice shelf system dynamics along continental margin, respectively.

How to cite: Khoo, W. W., Müller, J., Esper, O., Xiao, W., Stepanek, C., Gierz, P., Lohmann, G., Geibert, W., and Mollenhauer, G.: Sea-ice variability along the Antarctic continental margin since the Last Penultimate Glacial , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11973, https://doi.org/10.5194/egusphere-egu24-11973, 2024.

EGU24-13589 | ECS | Posters on site | CL1.2.5

Early Pleistocene Sediment Record from the Antarctic Zone of the Southern Ocean Dominated by Obliquity 

Bastian Muench, Bella Garrioch, Louisa Bradtmiller, and Katharina Billups

We present an orbital-scale record of percent biogenic silica (opal) at Ocean Drilling Program Site 745B situated in the Antarctic Zone of the Indian Ocean sector of the Southern Ocean spanning a majority of the early Pleistocene (1.1-2.6 Ma). By investigating the relative importance of obliquity versus precession-paced variability in our record, we seek to contextualize the apparent dominance of obliquity pacing in early Pleistocene d18O records. Notably, between 1.1 and 1.8 Ma, both the site’s shipboard magnetic susceptibility record and our biogenic silica record principally exhibit obliquity-related spectral peaks at a periodicity of 41 kyr, with relatively minor spectral power at precessional periodicities (23-19 kyr). During the older part of the record (1.8-2.6 Ma), only d18O and magnetic susceptibility vary at the 41 kyr obliquity periodicity, while the biogenic silica record does not show prominent orbital pacing at any of the major periodicities. We suggest that the surprising dominance of obliquity-paced variability in all records between 1.1 and 1.8 Ma indicate a lack of response of the proxies to precessional forcing during this period. The notable lack of orbital forcing in the opal record before 1.8 Ma may reflect both a more southerly location of the polar frontal zone with respect to the site and thus outside the region of wind-driven upwelling and waters undersaturated with respect to silica prior to the establishment of the opal belt at about 2 Ma.

How to cite: Muench, B., Garrioch, B., Bradtmiller, L., and Billups, K.: Early Pleistocene Sediment Record from the Antarctic Zone of the Southern Ocean Dominated by Obliquity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13589, https://doi.org/10.5194/egusphere-egu24-13589, 2024.

EGU24-14100 | Orals | CL1.2.5

Stability of interior East Antarctic wind scour and ice flow on glacial-interglacial timescales 

Tyler Fudge, Michelle Koutnik, Duncan Young, Shivangini Singh, Nicholas Holschuh, Shuai Yan, Don Blankenship, and Megan Kerr

The region between Dome A and South Pole has likely preserved ice older than the current 800-thousand-year limit of continuous ice core records; however, until now this region has been largely unexplored. The Center for Oldest Ice Exploration (COLDEX) is currently performing the second of two planned years of airborne geophysical surveys on the Southern flank of Dome A. These surveys are providing new geological and glaciological constraints that we combine with ice-flow models to help target suitable deep ice core sites with the goal of recovering a continuous ice-core record going back at least 1.5 million years.

 

Using the new airborne ice penetrating radar data from COLDEX, as well as existing data from the AGAP project, we investigate how local variations in surface conditions may affect the ice record over time. First, we trace englacial layers and date them at the intersection with the South Pole ice core to infer the rate and pattern of past accumulation averaged over different time intervals. Second, we assess the impact of local zones of wind scour that occur on the Southern flank of Dome A (Das et al, 2013), which is at the upstream edge of the COLDEX airborne survey. Local zones of wind scour that lead to ablation or no accumulation, create time-transgressive unconformities that can be mapped from ice penetrating radar data. While the unconformity is initiated due to a relatively local change in surface conditions, the unconformity trace is imaged for many tens of kilometers downstream as it is advected by ice flow. Because the airborne survey flight lines are oriented along flowlines, the unconformities act as particle trajectories.

 

We use an ice-flow model set up along a flowline to evaluate the surface and flow conditions that develop an unconformity similar to a well-imaged unconformity that is observed in the COLDEX data. The unconformity can be well matched with the simple ice-flow model using a fixed position of the scour zone, indicating that the scour zone has been a persistent feature for the past glacial-interglacial cycle (~100 ka). Consistent with previous work (Das et al, 2013), the scour zones are co-located with subglacial ridges that create steeper surface topography. Thus, the positions of the scour zones are likely independent of the climate state and permanent features on long timescales.

 

By modeling this unconformity trace we can constrain the modern horizontal velocity to ~1.5 m/yr near the scour zone that is located ~400 km from Dome A. The unconformity disrupts the continuity of all of the dated internal layers, which extend to 94 ka. Running the model back 1.5 Ma, we can evaluate where the climate record is disrupted at different positions along the flowline. The farther downstream a potential drill site is, the more problematic the unconformities become for obtaining a continuous climate record because the unconformity disrupts the continuity at deeper depths and older ages.

How to cite: Fudge, T., Koutnik, M., Young, D., Singh, S., Holschuh, N., Yan, S., Blankenship, D., and Kerr, M.: Stability of interior East Antarctic wind scour and ice flow on glacial-interglacial timescales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14100, https://doi.org/10.5194/egusphere-egu24-14100, 2024.

EGU24-14335 | ECS | Orals | CL1.2.5

Early-Mid Pleistocene ice core records of Antarctic and global cooling  

Sarah Shackleton and the Allan Hills Blue Ice Coring Team

Here we present water isotope and noble gas data from the Allan Hills, Antarctica, which provide insight into the local and global climate extending through the Mid Pleistocene Transition and beyond. The Allan Hills blue ice archive provides snapshots of climate that extend well beyond continuous ice core records, but their interpretation has challenges, including complex stratigraphy, potential preservation bias, and highly thinned records.  The water isotope and noble gas data (which come from the same ice samples) suggest a statistically significant correlation between Antarctic temperature and mean ocean temperature, consistent with previous studies. However, we observe subtle differences between these climate reconstructions, including within the mid-Pleistocene transition. We discuss these datasets in the context of broader global changes, and the nuances of the Allan Hills archives.

How to cite: Shackleton, S. and the Allan Hills Blue Ice Coring Team: Early-Mid Pleistocene ice core records of Antarctic and global cooling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14335, https://doi.org/10.5194/egusphere-egu24-14335, 2024.

The weakening or shutdown of Atlantic Meridional Overturning Circulation (AMOC) likely played a significant role in the glacial inception during the past million years. Previous modeling studies have shown that orbital forcing could have been triggered multiple AMOC weakening or shutdown, but it is still unclear which orbital parameter is the most essential trigger. In this study, we performed multiple long simulations with a fully coupled atmosphere-ocean general circulation model, CESM1.2.2, to investigate the influence precession on AMOC. It is found that precession is able to trigger a shutdown of AMOC. However, this happens only when the eccentricity is high and the atmospheric CO2 concentration is relatively low. The growth and expansion of Arctic sea ice is responsible for the shutdown. Therefore, the results may advance our understanding of the mechanisms driving the glacial-interglacial cycles of the Quaternary Period, and may be related to the mid-Pleistocene transition.

How to cite: Liu, Y. and Liu, H.: Shutdown of Atlantic Meridional Overturning Circulation Induced by Precession, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14755, https://doi.org/10.5194/egusphere-egu24-14755, 2024.

EGU24-15013 | Orals | CL1.2.5

A one-dimensional temperature and age modeling study for selecting the drill site of the oldest ice core near Dome Fuji, Antarctica 

Ayako Abe-Ouchi, Takashi Obase, Fuyuki Saito, Shun Tsutaki, Shuji Fujita, Kenji Kawamura, and Hideaki Motoyama

The recovery of a new Antarctic ice core spanning the past  1.5 million years will advance our understanding of climate system dynamics during the Quaternary. Recently, glaciological field surveys have been conducted to select the most suitable core location near Dome Fuji (DF), Antarctica. Specifically, ground-based radar-echo soundings have been used to acquire highly detailed images of bedrock topography and internal ice layers. In this study, we use a one-dimensional (1-D) ice-flow model to compute the temporal evolutions of age and temperature, in which the ice flow is linked with not only transient climate forcing associated with past glacial–interglacial cycles but also transient basal melting diagnosed along the evolving temperature profile. We investigated the influence of ice thickness, accumulation rate, and geothermal heat flux on the age and temperature profiles. The model was constrained by the observed temperature and age profiles reconstructed from the DF ice-core analysis. The results of sensitivity experiments indicate that ice thickness is the most crucial parameter influencing the computed age of the ice because it is critical to the history of basal temperature and basal melting, which can eliminate old ice. The 1-D model was applied to a 54 km long transect in the vicinity of DF and compared with radargram data. We found that the basal age of the ice is mostly controlled by the local ice thickness, demonstrating the importance of high-spatial-resolution surveys of bedrock topography for selecting ice-core drilling sites.

How to cite: Abe-Ouchi, A., Obase, T., Saito, F., Tsutaki, S., Fujita, S., Kawamura, K., and Motoyama, H.: A one-dimensional temperature and age modeling study for selecting the drill site of the oldest ice core near Dome Fuji, Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15013, https://doi.org/10.5194/egusphere-egu24-15013, 2024.

EGU24-16061 | Posters on site | CL1.2.5

Insolation triggered abrupt cooling at the end of interglacials and implication for the future  

Qiuzhen Yin, Zhipeng Wu, Ming-Qiang Liang, Andre Berger, Hugues Goosse, and David Hodell

Paleoclimate records show that the end of interglacials of the late Pleistocene was marked by abrupt cooling events. Strong abrupt cooling occurring when climate was still in a warm interglacial condition is puzzling. Our transient climate simulations for the eleven interglacial (sub)stages of the past 800,000 years show that, when summer insolation in the Northern Hemisphere (NH) high latitudes decreases to a critical value (a threshold), it triggers a strong, abrupt weakening of the Atlantic meridional overturning circulation and consequently an abrupt cooling in the NH. The mechanism involves sea ice-ocean feedbacks in the northern Nordic Sea and the Labrador Sea (Yin et al., 2021, doi: 10.1126/science.abg1737). The insolation-induced abrupt cooling is accompanied by abrupt changes in precipitation, vegetation from low to high latitudes and by abrupt snow accumulation in northern polar regions. The timing of the simulated abrupt events is highly consistent with those observed in marine and terrestrial records, especially with those observed in high-resolution, absolutely-dated speleothem records in Asia and Europe, which validates the model results and reveals that the astronomically-induced slow variations of insolation could trigger abrupt climate events.  Our results show that the insolation threshold occurred at the end of each interglacial of the past 800,000 years, suggesting its fundamental role in terminating the warm climate conditions of the interglacials. The next insolation threshold will occur in 50,000 years, implying an exceptionally long interglacial ahead naturally speaking, confirming earlier studies using other models. 

How to cite: Yin, Q., Wu, Z., Liang, M.-Q., Berger, A., Goosse, H., and Hodell, D.: Insolation triggered abrupt cooling at the end of interglacials and implication for the future , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16061, https://doi.org/10.5194/egusphere-egu24-16061, 2024.

EGU24-16073 | Posters on site | CL1.2.5

Ice sheet related glacial/interglacial cyclicity of granitic tetrafluoromethane (CF4) emissions before and after the Mid Brunhes 

Jochen Schmitt, Barbara Seth, Peter Köhler, Jane Willenbring, and Hubertus Fischer

CF4 is a long-lived atmospheric trace gas that was thought to be emitted only by anthropogenic processes. However, small quantities of CF4 are released from a natural source – chemical weathering of granitic rocks generate an atmospheric background concentration that is archived in polar ice. We measured CF4 concentrations over the last 800 kyr and used an inversion to calculate CF4 emission fluxes. We consistently found higher CF4 fluxes for each interglacial, resulting in an increase of atmospheric CF4 concentrations, while glacials show lower CF4 fluxes and declining CF4 concentrations. Different processes might be responsible for this pattern. First, higher CF4 fluxes during warm conditions are expected as chemical weathering rates are known to increase with temperature and precipitation. Second, granitic rocks are not randomly distributed but preferentially located in high northern latitudes which are largely covered by continental ice sheets and permafrost during glacials inhibiting CF4 release as weathering requires liquid water and a connection to the atmosphere. Thus, the waxing and waning of the northern hemispheric ice sheets has a larger leverage on CF4 fluxes than expected from the area alone. Interestingly, the peaks of the CF4 emission fluxes occurred at the starts of the interglacials. Our interpretation is that moraines left behind at the southern fringes of the retreating ice sheets provide easily weatherable material under already warm conditions. Conversely, from the late interglacials throughout the glacials we observe drops in CF4 concentration. The minima of both CF4 concentrations and CF4 fluxes are located at the end of the glacials, i.e. before the deglaciations started. This observation helps to assess the activity of glaciers via their erosional grinding of bedrock which produces suspended fine materials, so-called “glacier flour”.  Because the mineral fluorite, which is typically enclosing CF4 within the granite rock, is highly soluble in water, CF4 would be quickly released after grinding since it should occur in wet conditions. Our data suggest that this process is small compared to the suppression of granite weathering via ice coverage, otherwise the maxima in CF4 fluxes should have been found during glacial maxima.   

On the long-term, our record reveals a marked rise in CF4 fluxes after the Mid Brunhes event (MBE). Beginning with MIS 11, the first strong interglacial after a series of weak interglacials, the glacial/interglacial amplitudes in CF4 emissions but also for CO2 and ice volume increased. For the 430 kyr after the MBE the reconstructed CF4 fluxes increased by ca. 8%, predominantly due to increasing interglacial emissions, especially for MIS 5, 9, 11. We discuss three possible scenarios for this post-MBE rise in granite weathering: First, higher temperatures in northern high latitudes. Second, the exposure of granitic rocks that was ice covered during previous weak interglacials. Third, a remaining fraction of the former regolith covering large parts of North America was eroded during MIS 12 initiating the climatic changes associated with of MBE.        

How to cite: Schmitt, J., Seth, B., Köhler, P., Willenbring, J., and Fischer, H.: Ice sheet related glacial/interglacial cyclicity of granitic tetrafluoromethane (CF4) emissions before and after the Mid Brunhes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16073, https://doi.org/10.5194/egusphere-egu24-16073, 2024.

EGU24-16932 | Orals | CL1.2.5

Increase in strength and orbital variability of the South Pacific Antarctic Circumpolar Current across the Mid-Pleistocene Transition 

Frank Lamy, Gisela Winckler, Helge Arz, Jesse R. Farmer, Lester Lembke-Jene, Julia Gottschalk, and Maria Toyos

The Antarctic Circumpolar Current (ACC) represents the world’s largest ocean current system and impacts global ocean circulation, climate, and Antarctic ice sheet stability. Today, ACC dynamics are controlled by atmospheric forcing, Southern Ocean density gradients, and mesoscale eddy activity in the southern high latitudes. Yet, its role in driving the lengthening and intensification of glacial cycles is insufficiently studied. Here, we present a 1.5 Ma-record of changes in ACC strength based on bottom water flow reconstructions and sedimentary opal contents at IODP Sites U1540 and U1541 drilled in the Subantarctic Zone (SAZ) of the Pacific Southern Ocean. Our new data indicate that glacial and interglacial ACC strength gradually increased between ~1.3 and ~ 1 Ma coinciding with the early part of the MPT. This interval culminates in a pronounced ACC maximum during Marine Isotope Stage (MIS) 31 at ~1 Ma reaching ~160 % of the mean Holocene values. The increase in subantarctic ACC strength during the initial part of the MPT is paralleled by the emergence of stronger orbital-scale fluctuations in opal contents at both Sites U1540 and U1541 after MIS 31, suggesting a link between the onset of consistently higher amplitude glacial-interglacial fluctuations of ACC changes and latitudinal shifts of the ‘opal belt’ in the Southern Ocean. Specifically, higher opal contents correlate to decreased ACC strength, suggesting that the opal belt extended northward into the SAZ during glacials. We argue that the early change in ACC dynamics at the beginning of the MPT might be linked with sea surface temperature changes in the eastern subtropical and tropical Pacific, because surface cooling by ~2-3 °C at ODP Site 1237 off Peru between ~1.05 Ma and ~0.8 Ma parallels the reconstructed ACC strengthening at IODP Sites U1540 and U1541. This may result from enhanced advection of subantarctic water masses northward along the Humboldt Current system as a response to the intensification of the ACC starting during MIS 31. Our findings emphasize a contribution of Southern Ocean processes to the climate events causing intensification of glacial-interglacial climate variability during the MPT.

How to cite: Lamy, F., Winckler, G., Arz, H., Farmer, J. R., Lembke-Jene, L., Gottschalk, J., and Toyos, M.: Increase in strength and orbital variability of the South Pacific Antarctic Circumpolar Current across the Mid-Pleistocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16932, https://doi.org/10.5194/egusphere-egu24-16932, 2024.

The evolution of Earth’s climate during the Quaternary is characterized by glacial cycles with the periodic waxing and waning of large ice sheets most notably in the Northern Hemisphere. A fundamental transition in Earth climate occurred between 1250 and 650 kyr ago (ka) as the dominant glacial-interglacial variability shifted from ~40 to ~100-kyr cycles with more intense glacial climate. This is known as the Mid-Pleistocene Transition (MPT). The absence of appreciable change in the Milankovitch astronomical climate forcings during the MPT indicates that its occurrence might be a result of self-perpetuating climate feedback processes which would have been stimulated at ~900ka (i.e. Marine Isotope Stage 25-22) when global ice volume (e.g. Elderfield et al., 2012, Ford & Raymo, 2020), glacial ocean circulation (e.g. Pena &Goldstein 2014; Kim et al., 2021), deep ocean carbon reservoir (e.g. Lear et al., 2016; Farmer et al., 2019) and atmospheric CO2 levels (e.g. Hoenish et al., 2009; Chalk et al., 2017; Yamamoto et al., 2022) coherently experienced stepwise changes to post-MPT like glacial states from MIS22 onwards. Nevertheless, the triggering mechanism remains enigmatic because of the intertwined nature of these internal processes which precludes the disentanglement into their individual roles in the onset of post-MPT glacial ice volume and the pCO2 level at MIS22.

In this study, applying a combined climate – ice sheet – marine biogeochemical modeling approach, we investigate unidirectional impacts of changes in either atmospheric CO2 levels or northern hemisphere ice sheet (NHIS) volume on the other in transient simulations spanning two successive obliquity cycles. Our results show that the emergence of a 100-kyr glacial cycle is controlled by the interglacial rather than glacial CO2 levels. A lower glacial CO2 levels does increase NHIS volume and hence intensify the glacial climate. But only when the interglacial CO2 levels are below a threshold (~250ppm in our model) at the first obliquity peak, the developed glacial NHISs can skip the summer insolation maximum and reach a larger volume in the following glaciation, heralding the onset of 100-kyr glacial cycles. Meanwhile, the increased glacial NHISs, as a positive climate feedback process, promote atmospheric CO2 absorption in the subpolar North Atlantic via the strengthened upper cell of Atlantic Meridional Overturning Circulation. This, coupled with the enhanced formation of Antarctic Bottom Water, eventually sequesters the absorbed carbon in the North Pacific, further lowering glacial CO2 levels. Consistent with available proxy records, our results thus reconcile previously competing hypotheses for the occurrence of the MPT, providing a new and coherent dynamic framework accounting for the emergence of 100-kyr glacial cycles.

How to cite: Zhang, X., Stap, L. B., Du, J., and Nuber, S.: Control of subpar interglacial CO2 levels on the emergence of 100-kyr glacial cycles during the Mid-Pleistocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17220, https://doi.org/10.5194/egusphere-egu24-17220, 2024.

Qualitative faunal analyses of the Recent Antarctic glacjal fjordic cold-water bryozoans from the Admiralty Bay show the dominant ascophoran umbonulomorphs, mostly represented by the endemic species and accompanied by lepraliomorphs, schizoporellids, phidoloporoids, flustrinids, hippothoomorphs and cellaroids. The majority of the studied fauna form large-sized erect robust zoaria either bilamellar folded sheets or erect rigid cylindrical branches (Hara et al., 2010).

Four bryozoan assemblages (37 species) of cheilostomes dominated by ascophoran umbunulomorphs and lepraliomorphs, 4 cyclostomes and 1 ctenostome were analysed from a depth range of 15 to 280 m. The species richness (27 species), biomass and diversity were the greatest is the third assemblage from 120-200 m, where the fauna settled on the muddy substrate in the central part of the fjord. Dominant colony form was the adeoniform represented by erect, bilamellar plates, frondose or folded sheets, branched or lobate zoaria accompanied by numerous erect bugulids attached by chitinous rhizoids covered by epibionts.

The spatial variability in the bryozoan community structure, species richness and biomass are strongly associated with the number of environmental factors such as substrate type, water depth, location within the basin, hydrodynamic regime, influence of the suspended matter inflow or glacial disturbance (Pabis et al. 2014).

Mineralogically, the bryozoan skeletons from the Admiralty Bay are cheilostomes composed of intermediate magnesian calcite (IMC) where the Mg content ranges from ca. 4.3 to 6.5 wt% MgCO3. The bryozoans skeletons exhibit ẟ18O and ẟ13C values typical of cool marine waters (according to the aquition given by Friedman, O’Neil, 1977), see Hara, 2022. Their ẟ18O ranges from ca. 2.25 to 4.3% PBD, with most data clustering between 3 and 4 % PBD. The ẟ13C varies from ca. – 1 to + 1.5% PBD with most data plotted between + 0.5 and +1.5% PBD (Hara et al. 2010).

To add the Cenozoic evolution of the modern community structure occurred more recently, due to the factors such as further cooling and isolation of the continent leading to widespread glaciation, which resulted in a loss of shallow shelf habitats (see also Whittle et al., 2014).

Hara U. Jasinowski M. & Presler P. 2010. Geochemistry and mineralogy of bryozoan skeletons from Admiralty Bay (South Sheltland Islands, Antarctica: a preliminary account, p. 56. Terra Nostra, 15th International Conference IBA.

Hara U., 2022 – Geochemistry of the fossil and Recent bryozoan faunas in the natural diagenetic environments and their significance for the reconstruction of the biota and climatic regimes in Cenozoic. Archive of the Polish Geological Institute-National Research Institute, nr. 5210/2022.

Pabis K, Hara U. Presler P. & Siciński J. 2014. Structure of the bryozoans communities in an Antarctic glacjal fjord (Admiralty Bay), Polar Biology 37: 737-751.

Whittle R.J, Quaglio F., Griffiths H.J., Linse K., Crame J.A., 2014 – The Early Miocene Cape Melville Formation fossil assemblage and the evolution of modern Antarctic marine communities. Naturwissenschaften DOI 10.1007/s00114-013-1128-0.

How to cite: Hara, U.: Fjordic bryozoan community: (Admiralty Bay, King George Island, South Shetlands, West Antarctic) – biodiversity, distribution and geochemistry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18478, https://doi.org/10.5194/egusphere-egu24-18478, 2024.

EGU24-18691 | ECS | Orals | CL1.2.5

Environmental parameters affect palaeothermometry of Alkenones and GDGTs: A case study at the Southern Chilean Margin (46° S) 

Julia Rieke Hagemann, Alfredo Martínez-Garcia, Frank Lamy, Jérôme Kaiser, Lester Lembke-Jene, Helge W. Arz, Carina B. Lange, and Ralf Tiedemann

Isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGT) and alkenones are widely used tools for reconstructing past sea surface and subsurface temperatures. IsoGDGTs are membrane lipids synthesized by ammonia-oxidizing Nitrososphaerota and contain up to four cyclopentane moieties. Alkenones are unsaturated carbon chains, whose origin is mainly the coccolithophorid algae Emiliania huxleyi. The number of moieties of the isoGDGTs, as well as the degree of unsaturation of the alkenones depends on the ambient water temperature. Both biomarker-synthesizing organisms (Nitrososphaerota and E. huxleyi) are subject to several environmental influences, like nutrient availability, light conditions, salinity changes, changes in the biomarker-producing community, or terrigenous input, that can bias the temperature signal. In this study, we focus on the influence of terrigenous input and changes in salinity on both biomarkers. We use the 17 m-long piston core MR16-069 PC03, which is located at 46° S and ~150 km offshore the Chilean margin. This core covers a full glacial-interglacial cycle (140 ka) and shows recurring high inputs of terrigenous material and freshwater during the glacial period. This extreme contrast between interglacial and glacial is suitable for examining the influence of high terrigenous input on the temperature signal. Due to changes in the depositional setting, our results show a significant change in the expected temperature signal in both proxies during phases of high terrigenous input. We further discuss which temperature calibration is most appropriate for both biomarkers and conclude that for GDGT-based temperatures at this site, a calibration based on the TEXL86 index is more suitable, while for alkenone-based temperatures the UK37 index appears to be most accuracy.

How to cite: Hagemann, J. R., Martínez-Garcia, A., Lamy, F., Kaiser, J., Lembke-Jene, L., Arz, H. W., Lange, C. B., and Tiedemann, R.: Environmental parameters affect palaeothermometry of Alkenones and GDGTs: A case study at the Southern Chilean Margin (46° S), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18691, https://doi.org/10.5194/egusphere-egu24-18691, 2024.

EGU24-18813 | Orals | CL1.2.5

Continuous atmospheric CO2 across the Mid Pleistocene Transition from boron isotopes: decoupling of CO2 from insolation and temperature 

Thomas Chalk, Sophie Nuber, Lennert Stap, Meike Scherrenberg, Xu Zhang, Mathis Hain, Rachel Brown, Jimin Yu, Morten Anderson, Stephen Barker, James Rae, and Gavin Foster

Changes in atmospheric CO2 and global ice volume as a response to changes in insolation are one of the Earth’s most important feedback mechanisms during glacial-interglacial cycles. During the obliquity paced glacial-interglacial cycles of the 41kyr world prior to 1.2 million years ago (Ma), the response between insolation and the CO2-ice volume feedback is relatively linear. However, during the Mid-Pleistocene transition (0.6Ma – 1.2Ma), this linear response breaks down leading to a large increase in ice volume with a relatively modest decrease in CO2 during glacials in late Pleistocene. Here, we present atmospheric CO2 records derived from boron isotopes measured in the planktic foraminifera G. ruber sensu stricto from 3 ocean sediment cores, each well validated against ice records of CO2. We find two notable CO2 features during the MPT, an early de-coupling of CO2 and ice volume from insolation during MIS 36 (~1.05 Ma), where CO2 stays relatively constant despite multiple (but muted) orbital cycles. Secondly, during MIS 22 (0.9Ma), CO2 decreases step-wise, in combination with rising global ice volume, and recovers to “luke-warm style” interglacial levels in the following interglacial MIS 21. The periods of low CO2 and high ice volume occur in line with saltier Atlantic deep waters enriched in δ13C which we interpret as southern origin water masses, and increased ocean carbon storage. We therefore conclude that changes in ocean circulation may have caused an increased uptake of atmospheric carbon during these periods. In contrast, global sea surface temperatures during MIS36 follow insolation and not CO2 suggesting a de-coupling of the CO2/ice volume feedback from insolation and temperature. This may have prepositioned the climate system for the significant CO2 reduction and ice sheet expansion during and after 0.9Ma.

How to cite: Chalk, T., Nuber, S., Stap, L., Scherrenberg, M., Zhang, X., Hain, M., Brown, R., Yu, J., Anderson, M., Barker, S., Rae, J., and Foster, G.: Continuous atmospheric CO2 across the Mid Pleistocene Transition from boron isotopes: decoupling of CO2 from insolation and temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18813, https://doi.org/10.5194/egusphere-egu24-18813, 2024.

EGU24-18855 | ECS | Posters on site | CL1.2.5

Conceptual Model of Global Ice Volume during the Quaternary for the Mid-Pleistocene Transition 

Felix Pollak, Emilie Capron, Zanna Chase, Lenneke Jong, and Frédéric Parrenin

During the Quaternary, the dominant periodicity and amplitude of glacial-interglacial cycles underwent a transition from low-amplitude cycles of 41 kyr to high-amplitude 100 kyr cycles around 1.2-0.8 Myr ago. This transition is known as the Mid-Pleistocene Transition (MPT). The cause of the MPT is still unclear, as there was no change in the external orbital forcing during this time. Various hypotheses have been proposed to explain this phenomenon. Proposed hypotheses include scenarios of gradual and abrupt changes in the climate system over the Pleistocene, with ongoing debate about whether the MPT was triggered by an abrupt or gradual change.

Here, we utilize a conceptual model, which is a zero-dimensional representation of the climate system that simulates the global ice volume over the past 2 Myr. While the standard model is solely driven by orbital forcing namely obliquity and precession, it can be extended to take internal forcing into account, either caused by an abrupt or gradual change during the Pleistocene. Since the gradual setup has been shown to yield the best results, we focus on improving this model configuration by investigating different parameterizations and their influence on the model output. The model is fitted onto reconstructed global sea levels of the past 2 Myr, using a Monte Carlo random walk for tuning the parameters. Once properly tuned, the model can be used to simulate future glacial-interglacial cycles. The objective is to gain further insights into the underlying mechanisms that initiated the MPT and which mathematical features in this model are the most relevant. In future work, this conceptual model could be extended to include other paleoclimatic records like atmospheric CO2 or methane.

How to cite: Pollak, F., Capron, E., Chase, Z., Jong, L., and Parrenin, F.: Conceptual Model of Global Ice Volume during the Quaternary for the Mid-Pleistocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18855, https://doi.org/10.5194/egusphere-egu24-18855, 2024.

EGU24-20306 | Orals | CL1.2.5

A first step towards a complete Southern Ocean proxy compilation for the Last Glacial Cycle: glacial-interglacial changes in Sea Surface Temperature 

Lena Thöle, Karen Kohfeld, Zanna Chase, Xavier Crosta, Peter Bijl, and Nicholas McKay

Previous research has suggested that different processes in the Southern Ocean contributed to the drawdown and release of atmospheric carbon dioxide (CO2) during the last glacial cycle (0–130 ka), yet their dynamics and interplay are not fully understood. To unravel the interactions between different processes and to allow for more comprehensive analyses, we aim to compile all previously published proxy data and convert them into the Linked open Paleo Data (LiPD) format, overall increasing interoperability, reusability and impact.

The PAGES C-SIDE working group recently highlighted substantial open-ocean sea-ice extent changes during the mid-glacial period (Marine Isotope Stage 4, ~72 to 60 ka), coinciding with a significant drop in atmospheric CO2. However, sea-ice changes are notably absent during the early glaciation (Marine Isotope Stage 5d, ~115 to 105 ka), suggesting they cannot account for the early CO2 decrease (Chadwick et al., 2022).

As an initial step, we present our compilation of sea surface temperature (SST) reconstructions from marine sediment records across the Southern Ocean (Latitude > 30°S) for the last glacial cycle. This compilation assesses SST changes in different zones and basins, evaluates SST gradients, and explores the interplay between SST and sea ice.

Our findings reveal a consistent glacial-interglacial amplitude of 5-10°C across all basins and zones, with uniform timing. SST gradients from the Antarctic to Subantarctic Zone remain unchanged over time, eliminating them as a mechanism for early CO2 decrease. Additionally, we observe that 50% of the total MIS 5e-to-LGM cooling in Southern Ocean SST occurred from MIS 5e to MIS 5d, with a second drop from MIS 5a to MIS 4, essentially reaching LGM cooling. A distinct decoupling of SST cooling and sea ice expansion over MIS 5 suggests that circulation and/or subsurface temperatures may exert a stronger influence than SST on sea ice extent. This emphasizes the necessity for additional proxy compilations to further disentangle these complex relationships.

How to cite: Thöle, L., Kohfeld, K., Chase, Z., Crosta, X., Bijl, P., and McKay, N.: A first step towards a complete Southern Ocean proxy compilation for the Last Glacial Cycle: glacial-interglacial changes in Sea Surface Temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20306, https://doi.org/10.5194/egusphere-egu24-20306, 2024.

EGU24-1026 | ECS | Orals | CL1.2.6

Input and output fluxes of surface CO2 over the Late Quaternary 

Luca Castrogiovanni, Pietro Sternai, Claudia Pasquero, and Nicola Piana Agostinetti

Ice core archives allow us to retrieve the atmospheric CO2 concentration of the past 800,000 years characterized by periodically lower and higher CO2 levels corresponding to ice ages and interglacials, respectively. However, there is no broadly accepted consensus regarding the leading drivers of such variability. To a large extent, what prevents us from identifying the mechanisms that underlie changes in atmospheric CO2 concentrations is our inability to split the overall atmospheric CO2 budget into its sources and sinks terms, thereby assessing the fluxes of carbon among different reservoirs. Here, we use a reversible-jump Markov chain Monte Carlo (rj-McMC) algorithm to invert the atmospheric CO2 concentration dataset provided by the EPICA ice core based on a general forward formulation of the geological carbon cycle. We can quantify the most likely temporal variability of atmospheric carbon fluxes in ppm/yr throughout the last 800,000 years. Results suggest that temperature changes have been driving the variations of atmospheric CO2 until the Mid-Brunhes Event (MBE), when the onset of a progressive cyclic increase of  the atmospheric carbon fluxes marks a distinct behavioral change of the climate system. We ascribe such change to mechanisms internal to the Earth system, possibly related to the deglacial triggering of global volcanism and associated feedbacks on climate or a combination of geological, biological, and physical processes. Regardless, our unprecedented quantification of past atmospheric input and output CO2 fluxes provide (1) new constraints for climate carbon cycle and paleoclimate models to assess dominant climate-driving mechanisms, and (2) the benchmark for climate models intercomparison projects and better assessing the anthropogenic perturbation to the geological carbon cycle an associated climatic effect.

 

How to cite: Castrogiovanni, L., Sternai, P., Pasquero, C., and Piana Agostinetti, N.: Input and output fluxes of surface CO2 over the Late Quaternary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1026, https://doi.org/10.5194/egusphere-egu24-1026, 2024.

One of the critical features of deglaciations is the sudden increase in atmospheric CO2 levels. Regulating the Pleistocene atmospheric CO2 variations requires the involvement of oceanic carbon storage changes. However, the mechanisms and pathways for air-sea carbon exchanges remain elusive, partly resulting from the insufficiency of marine carbonate system proxy data with a robust age control beyond Termination I.

The deglacial CO2 rise toward Marine Isotope Stage (MIS) 9e (Termination IV) started from 197.1 ppm to 300.7 ppm[1], representing the highest natural atmospheric CO2 recorded in the Antarctic ice cores over the past 800 ka[2]. Our high-resolution carbonate system records from the Iberian Margin with a robust age control suggest an expansion of southern-sourced Glacial Antarctic Bottom Water at the onset of the deglaciation, followed by a net release of CO2 from the Atlantic sector of the Southern Ocean. However, our results indicate a different ocean circulation pattern during Termination III, when atmospheric CO2 increases by 85 ppm[2]. Unlike Termination III, the north-sourced water seems to take a large proportion of the deep Atlantic Ocean during this period.

References:

[1] Nehrbass-Ahles, C. et al. (2020), Science vol. 369 1000–1005.

[2] Bereiter, B. et al. (2015), Geophys. Res. Lett. 42, 542–549.

How to cite: Ji, X. and Yu, J.: The mechanism controlling air-sea CO2 exchange under different ocean circulation conditions, a case study from Iberian Margin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1157, https://doi.org/10.5194/egusphere-egu24-1157, 2024.

EGU24-3128 | Orals | CL1.2.6

Bølling-Allerød warming as a part of orbitally induced climate oscillation  

Yuchen Sun, Xu Zhang, Gregor Knorr, Martin Werner, Lev Tarasov, and Gerrit Lohmann

Deglacial abrupt warming event is a ubiquitous feature of deglaciations during the Late Pleistocene. Nevertheless, during the last deglaciation an unusually early onset of abrupt Northern Hemisphere warming event, known as Bølling/Allerød (B/A) warming, complicates our understanding of their underlying dynamics, especially due to the large uncertainty in histories of ice sheet retreat and meltwater distributions. Here applying the latest reconstruction of ice sheet and meltwater flux, we conduct a set of transient climate experiments to investigate the triggering mechanism of the B/A warming. We find that the realistic spatial distribution of meltwater flux can stimulate the warming even under a persistent meltwater background. Our sensitivity experiments further show that its occurrence is associated with an orbitally induced climate self-oscillation under the very deglacial climate background related to atmospheric CO2 level and ice sheet configurations. Furthermore, the continuous atmospheric CO2 rising and ice sheet retreating appear to mute the oscillation by freshening the North Atlantic via modulating moisture transport by the Westerly. 

How to cite: Sun, Y., Zhang, X., Knorr, G., Werner, M., Tarasov, L., and Lohmann, G.: Bølling-Allerød warming as a part of orbitally induced climate oscillation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3128, https://doi.org/10.5194/egusphere-egu24-3128, 2024.

EGU24-4269 | ECS | Posters on site | CL1.2.6

Impact of iron fertilisation on Southern Ocean ecosystems and global carbon cycle during the last glacial cycle 

Himadri Saini, Katrin Meissner, Laurie Menviel, and Karin Kvale

Rising atmospheric CO2 concentration is a major driver of climate change. One of the several processes proposed to explain the lower atmospheric CO2 concentration during the last glacial period is an increase in aeolian iron flux into the Southern Ocean. As the Southern Ocean is a high-nutrient-low-chlorophyll region, increased iron deposition can impact Southern Ocean marine ecosystems,  increase export production, and reduce surface Dissolved Inorganic Carbon (DIC) concentration. Here, we investigate the responses of Southern Ocean marine ecosystems to changes in iron flux and their impact on ocean biogeochemistry and atmospheric CO2 during the last glacial period. We use a recently developed complex ecosystem model that includes four different classes of phytoplankton functional types and fully incorporated iron, silica and calcium carbonate cycles. We show that the changes in atmospheric CO2 are more sensitive to the solubility of iron in the ocean than the regional distribution of the iron fluxes. If surface water iron solubility is considered constant through time, we find a CO2 drawdown of ∼4 to ∼8 ppm. However, there is evidence that iron solubility was higher during glacial times. A best estimate of solubility changing from 1 % during interglacials to 3 % to 5 % under glacial conditions yields a ∼9 to 11 ppm CO2 decrease at 70 ka, while a plausible range of CO2 drawdown between 4 to 16 ppm is obtained using the wider but possible range of 1 % to 10 %. We also show that the decrease in CO2 as a function of Southern Ocean iron input follows an exponential decay relationship, which arises due to the saturation of the biological pump efficiency and levels out at ∼21 ppm in our simulations.

We also investigate the role of iron flux changes on the abrupt atmospheric CO2 increase during Heinrich Stadials, which are associated with a near collapse of the Atlantic Meridional Overturning Circulation (AMOC), a sudden decrease in Greenland temperature and warming in the Southern Ocean. Previous modelling studies have investigated the role of the ocean circulation in driving changes in atmospheric CO2 concentration during these abrupt events, while the role of reduced aeolian iron input during Heinrich stadials remained poorly constrained. We show that a weakened iron fertilisation during Heinrich Stadials can lead to ~6 ppm rise in CO2 out of the total increase of 15 to 20ppm as observed. This is caused by a 5% reduction in nutrient utilisation in the Southern Ocean, leading to reduced export production and increased carbon outgassing from the Southern Ocean.

How to cite: Saini, H., Meissner, K., Menviel, L., and Kvale, K.: Impact of iron fertilisation on Southern Ocean ecosystems and global carbon cycle during the last glacial cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4269, https://doi.org/10.5194/egusphere-egu24-4269, 2024.

EGU24-4451 | Posters on site | CL1.2.6

Simulating glacial-interglacial CO2 variations: What's right with CLIMBER? 

Malte Heinemann, Victor Brovkin, Matteo Willeit, Joachim Segschneider, and Birgit Schneider

Despite intense efforts, current generation comprehensive Earth system models have, to our knowledge, not been able to simulate the full extent of the atmospheric pCO2 drawdown (as recorded in ice cores) during the Last Glacial Maximum (LGM). Yet, the intermediate complexity model CLIMBER-2 has successfully been used to simulate not only the LGM drawdown but also the transient evolution of CO2 concentrations during entire glacial–interglacial cycles. To better understand why this is the case, we compare the CLIMBER-2 results to pre-industrial and LGM simulations using two related models with increasing complexity, namely, the recently developed intermediate complexity model CLIMBER-X and the state-of-the-art comprehensive Earth system model MPI-ESM as used in the PalMod project, focusing on ocean carbon cycle changes.

How to cite: Heinemann, M., Brovkin, V., Willeit, M., Segschneider, J., and Schneider, B.: Simulating glacial-interglacial CO2 variations: What's right with CLIMBER?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4451, https://doi.org/10.5194/egusphere-egu24-4451, 2024.

EGU24-4464 | ECS | Posters on site | CL1.2.6

Polar Twins: Glacial CO2 outgassing reduced in the Southern Ocean by upwelling of well-ventilated waters from the North Pacific  

Madison Shankle, Graeme MacGilchrist, William Gray, Casimir de Lavergne, Laurie Menviel, Andrea Burke, and James Rae

The Southern Ocean is widely thought to have played a driving role in the atmospheric CO2 fluctuations of the ice ages, ventilating carbon-rich deep waters to the atmosphere during interglacial periods and limiting this CO2 leakage during glacial periods. A more efficient Southern Ocean biological pump during glacial periods is one of the leading hypotheses for how this “leak” might have been stemmed, but the exact dynamics responsible are still debated. Previous hypotheses have invoked reduced upwelling and/or enhanced stratification in reducing the carbon and nutrient supply to the glacial Southern Ocean surface, thus enhancing the net efficiency of its biological pump. Here we consider an alternative, complementary scenario in which the nutrient and carbon content of the upwelled water itself is reduced. Noting the striking similarity between proxy records from the North Pacific and Southern Ocean over the Last Glacial Cycle and given that carbon-rich waters upwelling in the Southern Ocean today are largely fed by the North Pacific, we propose that low-carbon/nutrient glacial Southern Ocean surface waters could have been sourced from a well-ventilated, low-carbon/nutrient glacial North Pacific. We then show in intermediate-complexity Earth system model simulations how a well-ventilated North Pacific can directly reduce the outgassing potential of waters upwelled in the Southern Ocean. While not precluding the possibility of changes to upwelling or mixing, our results demonstrate the ability of changes in the upwelled waters’ carbon content – outside of any changes to Southern Ocean physical dynamics (e.g., upwelling rate) – to change Southern Ocean carbon content and outgassing. This provides a novel mechanism linking Northern Hemisphere climate to Southern Ocean carbon cycling and may thus help explain the cyclic CO2 variations of the ice ages.

How to cite: Shankle, M., MacGilchrist, G., Gray, W., de Lavergne, C., Menviel, L., Burke, A., and Rae, J.: Polar Twins: Glacial CO2 outgassing reduced in the Southern Ocean by upwelling of well-ventilated waters from the North Pacific , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4464, https://doi.org/10.5194/egusphere-egu24-4464, 2024.

EGU24-5280 | ECS | Orals | CL1.2.6

Sensitivity of millennial-scale climate oscillations to boundary conditions in HadCM3 glacial simulations 

Brooke Snoll, Ruza Ivanovic, Lauren Gregoire, Yvan Rome, and Sam Sherriff-Tadano

Romé et al. (2022) present a new set of long-run Last Glacial Maximum experiments with millennial-scale climate oscillations between cold and warm modes. These oscillations are triggered by different snapshots of ice-sheet meltwater derived from the early stages of the last deglaciation. The overall characteristics of the oscillating events share similarities with δ18O records of the last glacial period. We test the robustness of these oscillations under different climate conditions, i.e., changes in atmospheric carbon dioxide concentration and orbital configuration. These experiments were run with intentions to better understand the range of conditions the oscillations can be sustained within the model and provide additional insight into the triggering mechanisms that control abrupt climate changes. The results of our sensitivity analysis show that small changes in carbon dioxide concentrations can impact the periodicity and existence of oscillations. A decrease in carbon dioxide concentration decreases periodicity, and an increase in carbon dioxide concentration increases periodicity, leading to an end of the oscillations. Our results also show that for changes in orbital configuration, an increase in Northern Hemisphere summer insolation decreases periodicity and potentially also amplitude. The results show that small changes in climate conditions can impact the shape and existence of oscillations and how this could relate to the changing periodicity and amplitude of observed Dansgaard-Oeschger events as well as transitions from glacial to interglacial states.

How to cite: Snoll, B., Ivanovic, R., Gregoire, L., Rome, Y., and Sherriff-Tadano, S.: Sensitivity of millennial-scale climate oscillations to boundary conditions in HadCM3 glacial simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5280, https://doi.org/10.5194/egusphere-egu24-5280, 2024.

Pleistocene temperatures correlate well with glacial-interglacial changes in global ice volume. While a discharge of ice-rafter debris (IRD) into the ocean directly reflects the rates of growth and decay (deglaciations) of glacial ice sheet margins at sea level, it is also the result of a rapidly changing global environment which affected both the meridional overturning in the ocean and the patterns in ocean-atmosphere circulation on a regional scale.  Circum-arctic land regions and adjacent ocean basins hold clues of varying ice sheet sizes through time. Understanding these records correctly is therefore an important asset to better appreciate Quaternary climate change also within a much broader global context. Marine sediment core data from the Nordic Seas show a stepwise trend of decreasing fluxes of IRD during major glaciations of the last 500 ka, i.e., marine isotope stages (MIS) 12, 6, and 2. Strongest IRD deposition occurred in MIS 12 (Elsterian), while it was lower in MIS 6 (Saalian) and 2 (Weichselian). These marine results of iceberg discharge rates from the western European margins, in particular, point to significant temporal changes in the ice-sheet coverage over northern Eurasia. Indeed, field data provide evidence for several major pre-Weichselian glaciations. Although their maximum limits were likely asynchronous in certain places, it seems evident that these ice sheets not only pre-date the Saalian time, they also extended much farther south (and east) than at any time later. The stepwise decreases in Eurasian ice-sheet extents during glacial maxima terminated in quite contrasting deglaciations and subsequent interglacial developments. It appears evident that such a systematic change in ice-sheet sizes were the result of specific ocean heat circulation, which influenced the pathways of atmospheric moisture transfer across northern Eurasia.

How to cite: Bauch, H.: Impact of waxing and waning of Northern Ice sheets on Pleistocene climate , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5426, https://doi.org/10.5194/egusphere-egu24-5426, 2024.

EGU24-5549 | Orals | CL1.2.6

Simulated radiocarbon cycle revisited by considering the bipolar seesaw and benthic 14C data 

Peter Köhler, Luke Skinner, and Florian Adolphi

Carbon cycle models used to interpret the IntCal20 compilation of atmospheric Δ14C have so far neglected a key aspect of the millennial-scale variability connected with the thermal bipolar seesaw: changes in the strength of the Atlantic meridional overturning circulation (AMOC) related to Dansgaard/Oeschger and Heinrich events. Here we implement such AMOC changes in the carbon cycle box model BICYCLE-SE to investigate how model performance over the last 55 kyr is affected, in particular with respect to available 14C and CO2 data. Constraints from deep ocean 14C suggest that the AMOC in the model during Heinrich stadial 1 needs to be highly reduced or even completely shutdown. Ocean circulation and sea ice coverage combined are the processes that almost completely explain modelled changes in deep ocean 14C age, and these are also responsible for a glacial drawdown of ~60 ppm of atmospheric CO2. A further CO2 drawdown of ~25 ppm is caused by the colder ocean surface at the last glacial maximum. We find that the implementation of AMOC changes in the model setup that was previously used for the calculation of the non-polar mean surface marine reservoir age, Marine20, leads to differences of less than ±100 14C years. The representation of AMOC changes therefore appears to be of minor importance for deriving mean ocean radiocarbon calibration products such as Marine20, where atmospheric carbon cycle variables are forced by reconstructions. However, simulated atmospheric CO2 exhibits minima during AMOC reductions in Heinrich stadials, in disagreement with ice core data. This mismatch supports previous suggestions that millennial-scale changes in CO2 were probably mainly driven by biological and physical processes in the Southern Ocean. By modifying the 14C production rate (Q), between one that varies so as to fit simulated atmospheric ∆14C to IntCal20 and an alternative constant Q, we can furthermore show that in our model setup the variability in deep ocean 14C age, especially during the Bølling/Allerød—Younger Dryas—Early Holocene climate transition, has its root cause in the carbon cycle, while a Q that achieves agreement with the IntCal20 atmospheric ∆14C record only enhances deep ocean age anomalies and thus optimizes agreement with the benthic 14C data.

How to cite: Köhler, P., Skinner, L., and Adolphi, F.: Simulated radiocarbon cycle revisited by considering the bipolar seesaw and benthic 14C data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5549, https://doi.org/10.5194/egusphere-egu24-5549, 2024.

EGU24-6271 | ECS | Orals | CL1.2.6

High-resolution sedimentological and palaeoceanographic investigation of the Last Glacial Termination (T1) recorded on the western margin of the Svalbard (Arctic) 

Fernando Sergio Gois Smith, Renata Giulia Lucchi, Monica Bini, Caterina Morigi, Patrizia Ferretti, Laura Bronzo, and Nessim Douss

The Last Glacial Maximum (LGM) was defined based on the low stand sea-level records from the most recent period when global ice sheets reached their maximum volume, between 26,500 and 19,000 years before present. The end of this cold period was the last glacial termination (T1), occurred between 20 and 11.7 ka BP marking the transition to the current interglacial. During T1, the sea level rise responded to a variety of processes although the melting of the world widely distributed ice sheets was initially the main contributor and responsible for abrupt relative sea level rises known as meltwater pulses (MWPs) that deeply changed the Earth’s physiography. MWPs are short-lived global acceleration in sea-level rise resulting from intense glacial melting, surge of large ice streams into oceans and intense iceberg discharge during ice sheet disintegration. Nowadays, the main concerns related to the present fast global climate change is the possibility that sudden drastic ice loss from the Greenland and/or in the West Antarctic Ice Sheet would lead to a new abrupt acceleration of the relative sea level with consequent inundation of vast coastal areas and/or to cause an abrupt slowdown of the Atlantic Meridional Overturning Circulation (i.e. Golledge et al., 2019). To better understand the dynamics and risks associated with the onset of those events, their impact on thermohaline ocean circulation and climate it is pivotal the study of the well-preserved polar marine sediment records of the events occurred during the T1. Here, we present the results of a high-resolution sedimentological, micropaleontological and geochemical investigation of 3 sediment cores collected on the western margin of Svalbard and eastern side of the Fram Strait (Artic). The sediment cores were collected between 1322 m and 1725 m of water depth, in correspondence of the southern IODP sites that will be drilled during the IODP Exp-403 (June-August 2024).

How to cite: Gois Smith, F. S., Lucchi, R. G., Bini, M., Morigi, C., Ferretti, P., Bronzo, L., and Douss, N.: High-resolution sedimentological and palaeoceanographic investigation of the Last Glacial Termination (T1) recorded on the western margin of the Svalbard (Arctic), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6271, https://doi.org/10.5194/egusphere-egu24-6271, 2024.

EGU24-6599 | ECS | Posters virtual | CL1.2.6

A two-phased Heinrich Stadial 11 as revealed by alkenone-based temperature record from the western tropical North Atlantic  

Anastasia Zhuravleva, Kirsten Fahl, and Henning A. Bauch

Paleo-data and models show that reductions in the strength of the Atlantic meridional overturning circulation (AMOC) lead to significant subsurface warming in the western tropical North Atlantic. The thermal response at the sea surface is less constrained due to the competing nature of the atmospheric and oceanic processes that produce opposite signs of temperature change. Here, we used alkenone unsaturation in sediments to reconstruct sea surface temperature (SST) evolution in the southeastern Caribbean (core MD99-2198, 1330 m water depth) during the last glacial-interglacial cycle, including Heinrich Stadial 11, which was a period of intense AMOC weakening. Our data show a 1 °C SST warming associated with the onset of Heinrich Stadial 11, and a 1 °C cooling during the late Heinrich, followed by a gradual 1 °C warming during the early last interglacial. Although stadial events are generally associated with wind-induced surface cooling in the tropical North Atlantic, the positive Caribbean SST anomaly during Heinrich Stadial 11 is consistent with previous findings. It likely originates from the upwelling of subsurface water that warmed in response to the initial AMOC weakening. Reduction in the Caribbean SST during the late Heinrich, associated with a particularly weak AMOC strength as suggested by our benthic d13C values, can indicate that the subsurface warming has diminished in the tropical North Atlantic possibly due to a general cooling in the source region (i.e., the subtropical gyre). A two-phased Heinrich is supported by the planktic foraminifera assemblage data, indicating that cooling occurred in the late Heinrich. In addition, this late phase is characterized by coarser sediments, which can be due to a strongly reduced outflow of the Orinoco and a particularly southern position of the intertropical convergence zone. For the last interglacial, our alkenone-derived SST record suggests stable conditions. However, the obtained interglacial values are characterized by very high alkenone unsaturation indexes that can incorporate large measurement and calibration errors due to the lack of Caribbean sediment traps and core-top data. These results, therefore, emphasize the need to better quantify the effectiveness of alkenones in reconstructing interglacial SST history in the Caribbean.

How to cite: Zhuravleva, A., Fahl, K., and Bauch, H. A.: A two-phased Heinrich Stadial 11 as revealed by alkenone-based temperature record from the western tropical North Atlantic , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6599, https://doi.org/10.5194/egusphere-egu24-6599, 2024.

Understanding the impact of freshwater discharge from the late Pleistocene Laurentide Ice Sheet (LIS) to the North Atlantic has been considered pivotal due to its direct regulating influence on the climate of the surrounding continents. Numerous studies using indirect paleo-proxies for iceberg discharge and fine-grained sediment supply have reconstructed the instabilities of the LIS. This study employs direct proxies for iceberg discharge and fine-grained sediment supply using the ice-rafted detritus (IRD) and X-ray fluorescence (XRF) scan combined with published X-ray diffraction (XRD) data from the same samples of the Integrated Ocean Drilling Program (IODP) Site U1313 (41°N; 32.57°W). Prominent Heinrich IRD events (H-events) of the last glacial cycle were accompanied by Ti/Ca and Fe/Ca peaks, consistent with the dolomite and calcite peaks, suggesting their Ordovician and Silurian carbonate rocks source that floor the Hudson Bay and Hudson Strait. However, despite the lack of an IRD/g peak, Ti/Ca and Fe/Ca peaks in H-event 3 suggest the arrival of fine-grained sediments in the southern edge of the IRD belt, most likely by sediment plume. In contrast to the last glacial cycle, IRD/g and Ti/Ca and Fe/Ca peaks, often assigned as Heinrich-like events, were only identified during the cold marine isotope stage (MIS) 6, 8, 10, and 12. The IRD/g, Ti/Ca, and Fe/Ca peaks, in addition to the dolomite and calcite peaks during the MIS 7, suggest a fundamentally different configuration of the LIS compared to the other warm MISs of the last 500 ka. Our data suggest that the LIS-sourced icebergs impacted the northern edge of the subtropical gyre (STG) by directly injecting meltwater and modifying the upper water masses, which most likely resulted in the southward movements of the Polar and Arctic fronts. These frontal movements were accompanied by frequent encroachment of the subpolar to transitional water masses to the STG. The polar water-dwelling planktonic foraminifera Neogloboquadrina pachyderma coupled to the IRD/g or Fe/Ca and Ti/Ca peaks support this hypothesis. The new sedimentological and micropaleontological data suggest that the instability and configuration of the LIS were not uniform during all the warm MISs of the last 500 ka.

How to cite: Rashid, H., Zeng, M., and Menke, M.: Impact of the Laurentide Ice Sheet instabilities on the mid-latitude North Atlantic and subtropical gyre during the last five glacial cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6815, https://doi.org/10.5194/egusphere-egu24-6815, 2024.

EGU24-7296 | Orals | CL1.2.6

The Southern Ocean’s role in the global carbon cycle over the last 800 kyr constrained using reconstructions of the CO2 system 

Chen Xu, Jessica Crumpton-Banks, Madison Shankle, Megan Pelly, Hana Jurikova, Jimin Yu, Bradley Opdyke, Claus-Dieter Hillenbrand, Andrea Burke, and James Rae

The critical role of the Southern Ocean in controlling the Pleistocene atmospheric CO2 oscillations is widely acknowledged. However, owing to sampling difficulties surrounding Antarctica, the underlying mechanism and associated pathway of ocean-atmosphere CO2 exchange in the Antarctic Zone (AZ) of the Southern Ocean remains mysterious. Here, we present a new planktonic δ11B record from sediment core PS1506 (68.73°S, 5.85°W) that tracks the pH and surface pCO2 of the AZ over the last 8 glacial cycles. These data are complemented by benthic B/Ca and carbonate preservation indices; due to the location of this core on the continental margin of the eastern Weddell Sea, these data allow us to track the source CO2 chemistry of the dense Antarctic waters that feed the ocean’s lower overturing cell. We find coherent CO2 change between surface and deep waters, indicating persistent formation of AABW that transfers Antarctic surface water signals to depth. Critically, we discover abrupt AZ CO2 decline during glacial onset conditions, coinciding with initial atmospheric CO2 drawdown, highlighting the AZ’s key control on glacial-interglacial CO2 change. After assessing proposed drivers, our findings implicate shifts in Southern Ocean circulation linked to changes in sea ice and/or the Southern Hemisphere westerlies in this glacial onset CO2 change, while productivity, solubility, and sea ice 'lid' effects appear insignificant or counterproductive in this region and time interval. Overall, these reconstructed CO2 system dynamics provide critical insights into Southern Ocean carbon cycling and the associated influence on the atmosphere.

How to cite: Xu, C., Crumpton-Banks, J., Shankle, M., Pelly, M., Jurikova, H., Yu, J., Opdyke, B., Hillenbrand, C.-D., Burke, A., and Rae, J.: The Southern Ocean’s role in the global carbon cycle over the last 800 kyr constrained using reconstructions of the CO2 system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7296, https://doi.org/10.5194/egusphere-egu24-7296, 2024.

Global sea-level changes are significantly associated with variations in Northern Hemisphere ice sheets (NHISs) during the last glacial cycle. However, their responses to glacial millennial-scale climate variability (also known as Dansgaard - Oeschger (DO) cycles), especially during the Marine Isotope Stage 3 (MIS3, ~30-65ka), remains poorly studied, in addition to the contrast lines of geological evidence regarding paleo-sea level changes. Instead of applying Glacial Index Method which overlooks potential tempo-spatial heterogeneity of temperature and precipitation in the northern high latitudes, in this study, we conducted transient PISM ice sheet modeling by imposing full climate forcing derived from fully coupled climate model experiments which are characterized by spontaneous millennial variability. Our results show that control factors of ice volume changes in Laurentide and Eurasian ice sheets are different due to spatially heterogenous climate forcing. During stadial periods, North American Ice sheets is growing because of increased precipitation especially along the margins of the ice sheets, despite spatially heterogenous but trivial changes in the surface air temperature. Meanwhile, dramatic cooling on the southern regions of Eurasian Ice sheets effectively reduces ice loss and hence promote the overall ice growth. In brief, NHIS ice volume grows during stadials while declines during interstadials. We hence propose that stadial-to-interstadial duration ratio is the key to the net change in NHIS volume in a signal DO cycle, providing dynamic understanding of accelerated sea level drop during 40-30ka.

How to cite: Zhang, Y. and Zhang, X.: Millennial-scale Northern Hemisphere ice sheet growth controlled by stadial-versus-interstadial duration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7339, https://doi.org/10.5194/egusphere-egu24-7339, 2024.

EGU24-8676 | Posters on site | CL1.2.6

Abrupt climate changes triggered with GLAC-1D ice sheet, but not with ICE-6G_C, in simulations of the Last Glacial Maximum/Deglaciation 

Ruza Ivanovic, Yvan Rome, Lauren Gregoire, Brooke Snoll, Oliver Pollard, and Jacob Perez

In the course of glacial terminations, the increases in greenhouse gas concentrations, summer insolation and the ice sheet demise can trigger episodes of millennial-scale variability. Such variability was observed during the last deglaciation, between 19 ka BP (thousand years ago) and 8 ka BP, in the form of  the abrupt North Atlantic temperature shifts of the Bølling–Allerød Warming (14.5 ka BP) and Younger Dryas (12.900 ka BP).

In some climate models, abrupt climate changes are generated by modifications to the boundary conditions and freshwater discharge. Despite much study, the sensitivity of climate simulations to ice sheet geometry and meltwater is complex and not fully understood, which is a caveat when considering the impact of the rapid demise of the Northern Hemisphere ice sheets during the last deglaciation. In a new set of last glacial maximum HadCM3 simulations that can produce millennial-scale variability, we studied the influence of two ice sheet reconstructions, ICE-6G_C and GLAC-1D, and their associated deglacial meltwater history, on the simulated chain of events of the last deglaciation.

In this experiment, our simulations using the GLAC-1D ice sheet reconstruction produced abrupt climate changes. Triggered by freshwater released close to the Nordic Seas and Iceland Basin deep water formation sites, these simulations display abrupt shifts in the Atlantic Meridional Overturning Circulation (AMOC) that are decoupled from the meltwater flux. In contrast, the reconstructed ICE-6_G ice sheet modifies the North Atlantic wind patterns in the model, preventing convection in the Nordic Seas and intensifying the Iceland Basin deep water formation. As a result, no abrupt climate changes are simulated with ICE-6G_C ice sheets and the AMOC decreases almost linearly with the introduction of freshwater.

The simulations do not capture the timing of the last deglaciation chain of events, but the modelled abrupt changes replicate the main Northern Hemisphere characteristics of the Bølling Warming/Younger Dryas transitions, and are very similar to Dansgaard-Oeschger events.

How to cite: Ivanovic, R., Rome, Y., Gregoire, L., Snoll, B., Pollard, O., and Perez, J.: Abrupt climate changes triggered with GLAC-1D ice sheet, but not with ICE-6G_C, in simulations of the Last Glacial Maximum/Deglaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8676, https://doi.org/10.5194/egusphere-egu24-8676, 2024.

EGU24-8715 | ECS | Orals | CL1.2.6

Tracking the fate of meltwater from different Northern ice sheet sectors over Heinrich Stadial 1 

Laura Endres, Ruza Ivanovic, Yvan Romé, Julia Tindall, and Heather Stoll

The addition of meltwater from continental ice sheets to the North Atlantic is thought to have played a pivotal role in the reorganization of climate and ocean circulation over the last deglaciation as well as during Heinrich events. This is supported by recent analysis of PMIP and CMIP results, which shows that meltwater addition into the North Atlantic can largely alter global climate, and remains a key uncertainty for both reconstruction and climate projections. 

To date, most model studies of freshwater “hosing” assume a relatively uniform distribution and apply meltwater to a large portion of the North Atlantic basin. However, AMOC weakening is sensitive to the actual input position of the typically cold and non-saline meltwater perturbation, and, on a centennial-millennial timescale, the resulting temperature and salt anomaly will only partially disperse over the entire North Atlantic surface ocean. In contrast, most proxy data sensitive to meltwater record the signal at a specific location. It is unclear if spatial heterogeneity of the ocean’s distribution of the meltwater anomaly may contribute to disagreements between freshwater proxy records and model simulations with freshwater additions tuned to reproduce the record of past AMOC weakenings.

To enhance understanding of the spatial distribution of meltwater anomalies during deglaciations, we present the results of a model sensitivity study using HadCM3 and artificial dye tracers to track the fate of meltwater originating from different Northern ice sheet sectors. We consider different meltwater scenarios consistent with Heinrich Stadial 1 ice sheet reconstructions and compare the results under different AMOC states. The results confirm that, on a centennial timescale, meltwater distribution is not uniform over the North Atlantic Ocean. The emerging patterns expose that the efficiency of a meltwater injection to produce a surface ocean anomaly (in, e.g., salinity or δ18Osw) at a given proxy location differs between different ice sheet sectors by orders of magnitudes. Further, besides the direct effect of meltwater, the sensitivity of climate indicators, such as temperature, to changes in AMOC strength also shows regional discrepancies. 

How to cite: Endres, L., Ivanovic, R., Romé, Y., Tindall, J., and Stoll, H.: Tracking the fate of meltwater from different Northern ice sheet sectors over Heinrich Stadial 1, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8715, https://doi.org/10.5194/egusphere-egu24-8715, 2024.

EGU24-9143 | Orals | CL1.2.6

Bipolar control on millennial atmospheric CO2 changes over the past glacial cycle 

Jimin Yu, Robert Anderson, Zhangdong Jin, Xuan Ji, David Thornalley, Lixin Wu, Nicolas Thouveny, Yanjun Cai, Liangcheng Tan, Fei Zhang, Laurie Menviel, Jun Tian, Xin Xie, Eelco Rohling, and Jerry McManus

Ice-core measurements show diverse atmospheric CO2 variations – increasing, decreasing or remaining stable – during millennial-scale North Atlantic cold periods called stadials. The reasons for these contrasting trends remain elusive. Ventilation of carbon-rich deep oceans can profoundly affect atmospheric CO2, but its millennial-scale history is poorly constrained. In this study, I will show a high-resolution deep-water acidity record from the Iberian Margin in the North Atlantic, a unique setting that allows us to construct a robust chronology for confident comparisons between marine and ice-core records. The new data combined with ice-core CO2 records reveal multiple ocean ventilation modes involving an interplay of the two polar regions, rather than by the Southern Ocean alone. These modes governed past deep-sea carbon storage and thereby atmospheric CO2 variations on millennial timescales. Overall, our record suggests a bipolar control on millennial atmospheric CO2 changes during the past glacial cycle.

How to cite: Yu, J., Anderson, R., Jin, Z., Ji, X., Thornalley, D., Wu, L., Thouveny, N., Cai, Y., Tan, L., Zhang, F., Menviel, L., Tian, J., Xie, X., Rohling, E., and McManus, J.: Bipolar control on millennial atmospheric CO2 changes over the past glacial cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9143, https://doi.org/10.5194/egusphere-egu24-9143, 2024.

EGU24-9411 | ECS | Orals | CL1.2.6

An Early Warming Over the Southern Ocean During the Last Deglaciation 

Peisong Zheng, Matthew Osman, and Thomas Bauska

The last deglaciation, spanning approximately 23 to 6 thousand years before present (ky BP), represents the most recent period in which Earth’s climate underwent large-scale reorganizations comparable (albeit not strictly analogous) to those projected under future climate changes. However, the precise sequence of events – in particular, the timing and spatial manifestation of the initial warming – remains uncertain. Here we present a new method using Gaussian Mixture Model clustering to objectively decompose a model and proxy-based climate reconstruction (LGMR; Osman et al., 2021) into four patterns of temperature change across the last deglaciation. Broadly speaking, the patterns allow us to delineate the impact of retreating Northern Hemisphere ice sheets, the rise in greenhouse gases, and the influence of the bipolar seesaw. Crucially, our analysis reveals that the high latitudes of the Southern Hemisphere exhibited the earliest signs of warming onset around 21 kyr BP, coincident with a retreat of sea ice across the Southern Ocean. A similar pattern is observed when decomposing a solely model-based climate reconstruction (TraCE-21k; He et al., 2013).  Using a combination of both highly-simplified energy balance-type models and fully-coupled climate models forced with insolation alone, we show that the early warming and sea ice retreat was likely linked to an initial rise in high latitude summertime energy that is dominated by enhanced obliquity-driven forcing. Our findings collectively suggest that insolation dynamics in the Southern Hemisphere were a critical trigger of the Last Deglacial onset and, further, may represent one of the key prerequisites for glacial terminations during the late Pleistocene.

How to cite: Zheng, P., Osman, M., and Bauska, T.: An Early Warming Over the Southern Ocean During the Last Deglaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9411, https://doi.org/10.5194/egusphere-egu24-9411, 2024.

EGU24-9419 | ECS | Orals | CL1.2.6

Assessing transient changes in the ocean carbon cycle during the last deglaciation through carbon isotope modeling  

Hidetaka Kobayashi, Akira Oka, Takashi Obase, and Ayako Abe-Ouchi

Atmospheric carbon dioxide concentrations (pCO2) have increases by approximately  from the Last Glacial Maximum (LGM) to the late Holocene (last deglaciation). These changes in atmospheric greenhouse gases are recognized as climate system responses to gradual changes in insolation. Previous modeling studies have suggested that the deglacial increases in atmospheric pCO2 are primarily attributed to the release of CO2 from the ocean. In addition, it has been suggested that abrupt changes in the Atlantic Meridional Overturning Circulation (AMOC) and associated interhemispheric climate changes are involved in the release of CO2. However, there is still limited understanding in oceanic circulation changes, factors responsible for changes in chemical tracers in the ocean of the last deglaciation and its impact on atmospheric pCO2.

In this study, we investigate the evolution of the ocean carbon cycle during the last deglaciation (21 to 11 ka BP) using three-dimensional ocean fields from the transient simulation of the MIROC 4m climate model, which exhibits abrupt AMOC changes as in reconstructions. We validate the simulated ocean carbon cycle changes and discuss possible biases and missing or underestimated processes in the model by comparing simulated carbon isotope ratios with sediment core data.

The qualitative changes in atmospheric pCO2 are consistent with ice core records: during Heinrich Stadial 1 (HS1), atmospheric  increases by . This is followed by a decrease of  during the Bølling–Allerød (BA) and an increase of  during the Younger Dryas (YD). However, the model underestimates the changes in atmospheric  during these events compared to ice core data. Radiocarbon and stable isotope signatures ( and ) indicate that the model underestimates the activated deep ocean ventilation and reduced efficiency of biological carbon export in the Southern Ocean, and active ventilation in the North Pacific Intermediate Water during HS1. The relatively small changes in simulated atmospheric  changes during HS1 may be attributed to these underestimations of ocean circulation changes. The changes in  associated with strengthening and weakening in the AMOC during the BA and YD are generally consistent with the sediment core record. On the other hand, while the data show a continuous  increase in the deep ocean throughout the YD, the model shows the opposite trend. This suggests that the model simulates excessive weakening of the AMOC during the YD, or limited representations in geochemical processes in the model including marine ecosystem responses and terrestrial carbon storage.

Decomposing the factors behind changes in ocean  reveals that changes in temperature and alkalinity have the main effects on atmospheric  changes. The compensation of the effects of temperature and alkalinity suggests the AMOC changes and associated bipolar climate changes contribute to a slight decrease or increase in atmospheric  during the BA and YD periods, respectively.

How to cite: Kobayashi, H., Oka, A., Obase, T., and Abe-Ouchi, A.: Assessing transient changes in the ocean carbon cycle during the last deglaciation through carbon isotope modeling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9419, https://doi.org/10.5194/egusphere-egu24-9419, 2024.

Be10 in ice cores provides a uniquely well resolved indication of past radionuclide production rates, with a direct bearing on past radiocarbon production.  In the absence of past carbon cycle perturbations (e.g. involving ocean-atmosphere carbon exchange), Be10-based radiocarbon production rate anomalies should correlate directly with atmospheric radiocarbon anomalies, as confirmed by models.  Over the past ~30ka, Be10-inferred radiocarbon production rates and atmospheric radiocarbon (i.e. Intcal20) both exhibit recurrent millennial anomalies, typically of ~5ka duration.  A correlation between these anomalies breaks down during the deglaciation.  This is intriguing and suggests a mix of millennial carbon cycle and radionuclide production influences. Here, global compilations of marine carbon isotope data (radiocarbon and 𝛿13C) are used to assess the potential contribution of ocean circulation and air-sea gas exchange to the apparent millennial component of variability in Intcal20, and atmospheric CO2. We find that existing marine 𝛿13C data provide strong support for a marine influence on atmospheric radiocarbon. Support from marine radiocarbon data is more complex, due to the influence of ‘attenuation biases’ (arising from radiocarbon production changes), and due to a distinct regionalism in the ocean’s impact on atmospheric radiocarbon, versus atmospheric CO2, with air-sea gas-exchange playing a significant role. Major differences in the long-term evolution of radiocarbon and 𝛿13C across the last deglaciation further point to distinct and independent controls on these isotopes systems, providing clues as to the nature and timing of different carbon cycle processes during deglaciation.

How to cite: Skinner, L.: Globally resolved marine carbon isotope data spanning the last 25ka: what do they tell us about the drivers of atmospheric radiocarbon and CO2 on millennial and deglacial timescales? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9678, https://doi.org/10.5194/egusphere-egu24-9678, 2024.

EGU24-9708 | ECS | Orals | CL1.2.6

Glacial-interglacial variability using a low-complexity, physically based model 

Sergio Pérez-Montero, Jorge Alvarez-Solas, Marisa Montoya, and Alexander Robinson

Pleistocene glacial-interglacial variability is still under debate, as the many hypotheses proposed are subject to the models used and assumptions made. The longer time scales involved in glacial cycles make it difficult to use comprehensive climate models because of its large computational cost. In this context, conceptual models are built to mimic complex processes in a simpler and more computationally efficient way. Here we present a conceptual climate-ice sheet model that aims to represent the state-of-the-art physical processes affecting glacial-interglacial variability. Our model was constructed using linear equations that explicitly represent ice-sheet modeling approaches. Preliminary results are consistent with Late Pleistocene variability and point to the existence of nonlinearities related to both ice dynamics and ice aging that determine the timing and shape of deglaciations.

How to cite: Pérez-Montero, S., Alvarez-Solas, J., Montoya, M., and Robinson, A.: Glacial-interglacial variability using a low-complexity, physically based model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9708, https://doi.org/10.5194/egusphere-egu24-9708, 2024.

EGU24-10190 | Orals | CL1.2.6

Perspective on ice age Terminations from absolute chronologies provided by global speleothem records 

Nikita Kaushal, Heather Stoll, and Carlos Pérez-Mejías

Glacial Terminations represent the largest amplitude climate changes of the last several million years.  Over ~ 10 ky timescale, large northern hemisphere ice sheets retreat and sea level rises, and atmospheric CO2 and global temperatures make a full transition from glacial to interglacial levels.  Several possible orbital-insolation triggers have been described to initiate and sustain glacial Terminations, and feedbacks between ice sheet retreat, ocean circulation and ocean carbon storage are invoked to explain the unstoppable progression. 

Because of the availability of radiocarbon dating, the most recent termination (TI) has been extensively characterized. Yet, it is widely discussed whether this sequence of feedbacks and millennial events, and rate of warming is recurrent over previous Terminations or is unique.  Beyond the limit of radiocarbon dating, the chronologies of climate records from ice and marine cores are often developed by tuning to orbital parameters which limits their use in understanding climate dynamics, particularly the response to orbital forcing.

Speleothems provide absolute age control and high-resolution proxy measurements. This archive therefore provides unique records of climate change across Terminations, and additionally may provide the opportunity to tune ice and marine core archives.  However, speleothem climate signals are encoded in a number of proxies. Unlike proxies in other archives like ice or marine cores, the climatic interpretation of a given proxy can vary quite significantly among different regions.

In this study, we

  • synthesize the available speleothem records providing climate information for Terminations: TII, TIII, TIV and TV.
  • present the records based on the aspect of climate encoded in the available records.
  • examine the effects of different ice volume corrections on the final climate proxy record.
  • evaluate whether there are leads and lags in the manifestation of Terminations across different aspects of the climate systems and different regions.
  • we speculate on suitable tuning targets among marine and ice core proxies, and discuss what model outputs maybe most suitable for comparison.

How to cite: Kaushal, N., Stoll, H., and Pérez-Mejías, C.: Perspective on ice age Terminations from absolute chronologies provided by global speleothem records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10190, https://doi.org/10.5194/egusphere-egu24-10190, 2024.

EGU24-10579 | Orals | CL1.2.6

A mechanism for reconciling the synchronisation of Heinrich events and Dansgaard-Oeschger cycles 

Clemens Schannwell, Uwe Mikolajewicz, Marie-Luise Kapsch, and Florian Ziemen

The evolution of the northern hemispheric climate during the last glacial period was shaped by two prominent signals of glacial climate variability known as Dansgaard-Oeschger cycles and Heinrich events. Dansgaard- Oeschger cycles are characterised by a period of rapid, decadal warming of up to 14°C in the high northern latitudes, followed by a more gradual cooling spanning several centuries. Temperature reconstructions from ice cores indicate a dominant recurrence interval of ∼1,500 years for Dansgaard-Oeschger cycles. Heinrich events are quasi-episodic iceberg discharge events from the Laurentide ice sheet into the North Atlantic. The paleo record places most Heinrich events into the cold phase of the millennial-scale Dansgaard-Oeschger cycles. However, not every Dansgaard-Oeschger cycle is accompanied by a Heinrich event, revealing a complex interplay between the two prominent modes of glacial variability that remains poorly understood to this day. Here, we present simulations with a coupled ice sheet-solid earth model to introduce a new mechanism that explains the synchronicity between Heinrich events and the cooling phase of the Dansgaard-Oeschger cycles. Unlike earlier studies, our proposed mechanism does not require a trigger mechanism during the cooling phase. Instead, the atmospheric warming signal associated with the interstadial phase of the Dansgaard-Oeschger cycle causes enhanced ice stream thickening such that a critical ice thickenss and temperature threshold is reached faster, triggering the Heinrich event during the early cooling phase of the Dansgaard-Oeschger cycle. An advantage of our mechanism in comparison to previous theories is that it is not restricted to marine-terminating ice streams, but applies equally to land-terminating ice streams that only become marine-terminating during the actual Heinrich event. Our simulations demonstrate that this mechanism is able to reproduce the Heinrich event characteristics as known from the paleo record under a wide range of forcing scenarios and provides a simple explanation for the observational evidence of synchronous Heinrich events from different ice streams within the Laurentide ice sheet.

How to cite: Schannwell, C., Mikolajewicz, U., Kapsch, M.-L., and Ziemen, F.: A mechanism for reconciling the synchronisation of Heinrich events and Dansgaard-Oeschger cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10579, https://doi.org/10.5194/egusphere-egu24-10579, 2024.

Despite decades of research, the cause of glacial-interglacial CO2 cycles is not fully understood, leaving a critical gap in our understanding of Earth’s climate system. One hypothesis is that shoaling of the boundary between Northern Source Water (NSW) and Southern Source Water (SSW) enhanced oceanic carbon sequestration during glacial intervals, resulting in lower atmospheric pCO2. To test this hypothesis, we generated vertical profiles of [CO32-], δ13C, and δ18O using a depth transect of cores from the Brazil Margin, focusing on the two major drops in atmospheric pCO2 during the last glacial cycle at ~115 ka and ~70 ka. Given that [CO32-] is inversely related to the concentration of dissolved inorganic carbon, [CO32-] should decrease if the Atlantic sequestered CO2. We observe no significant change in the [CO32-] across the first decrease in atmospheric pCO2 and no evidence for watermass boundary shoaling in the δ13C and δ18O profiles.  [CO32-] decreased only at ~3600 m, the core site most influenced by SSW.  During the second pCO2 decline at ~70 ka, [CO32-] decreased by ~30 µmol/kg below 2000 m water depth, coincident with marked shoaling in the δ13C and δ18O profiles. The lack of evidence for shoaling and deep Atlantic carbon sequestration at ~115 ka, a time of intermediate ice sheet extent and moderate global cooling, but the clear evidence for shoaling and carbon sequestration at ~70 ka, a time of near glacial maximum ice sheet extent, implies that the deep Atlantic’s capacity to store carbon depends on the Earth’s mean climate state. Our results highlight that distinct mechanisms are necessary to explain the two major drops in atmospheric pCO2 of the last glacial cycle. 

How to cite: Garity, M. and Lund, D.: Investigating oceanic carbon sequestration during glacial inception using vertical profiles of [CO32-], d13C, and d18O from the Southwest Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12112, https://doi.org/10.5194/egusphere-egu24-12112, 2024.

EGU24-12199 | ECS | Orals | CL1.2.6

Reconstructing the global mean surface temperature of the last 130 thousand years 

Jean-Philippe Baudouin, Nils Weitzel, Lukas Jonkers, Andrew M. Dolman, and Kira Rehfeld

Global mean surface temperature (GMST) is a fundamental measure of climate evolution in both past and present and a key quantity to evaluate climate simulations. However, for paleoclimate periods, its reconstruction hinges on uncertain and indirect observations which are distributed sparsely and non-uniformly in both space and time. Large datasets of homogenised proxy records help to reduce the sparsity. Then, the records can be aggregated in an algorithm retrieving the GMST signal. Here, we build on the algorithm designed in Snyder 2016, and on a recent database of ocean temperature proxy records to reconstruct the GMST evolution over the last glacial cycle (the last 130 thousand years). First, we evaluate the algorithm and quantify the sources of uncertainty. This analysis draws on pseudo-proxy experiments using a range of simulations of the last glacial cycle. We find that the over-representation of some regions (e.g. coasts, the Atlantic), to the detriment of others (e.g. the central Pacific) significantly impacts the reconstructed temperature anomaly and its variations. Additionally, millennial and shorter timescale variability cannot be reconstructed by the algorithm, due to bioturbation and age uncertainty. However, these experiments also demonstrate the ability of our algorithm to reconstruct the amplitude and timing of GMST variations occurring at orbital timescale (>10.000 years). Second, we reconstruct the GMST evolution during the last glacial cycle. We compare our result to previous studies, and discuss the improvements coming from the use of the recent proxy database. The high number of proxy records allow us to additionally investigate smaller regions (e.g. hemisphere) and overall further our understanding of the driver of orbital-scale GMST variability.

How to cite: Baudouin, J.-P., Weitzel, N., Jonkers, L., Dolman, A. M., and Rehfeld, K.: Reconstructing the global mean surface temperature of the last 130 thousand years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12199, https://doi.org/10.5194/egusphere-egu24-12199, 2024.

EGU24-13226 | Posters on site | CL1.2.6

Super-cooled glacial deep waters 

Miho Ishizu, Axel Timmermann, and Kyung-Sook Yun

Sea-ice formation in the Southern Ocean can generate supercooled waters, which can even remain below the in-situ freezing point at depths below 1,000 m. These water masses can play an important role in carbon transport to the abyssal ocean and may have therefore also played an important role in glacial-interglacial CO2 cycles.

To address this question, we examined model outputs from the transient 3 Ma simulation conducted with the CESM1.2 model (Community Earth System Model version 1.2, ~3.75 horizontal resolution. This simulation was driven by time-varying orbital forcing and estimates of atmospheric greenhouse gas concentrations and northern hemispheric ice-sheet orography and albedo. Our analysis shows the presence of large swaths of supercooled glacial deep waters mainly in the northern Pacific. This water is originally formed in the seasonal sea-ice formation regions in the subarctic North Pacific during periods of brine release and rapid mixed layer deepening. During interglacial periods, the volume of supercooled water decreases, which may hint towards a possible positive climate-carbon cycle feedback.

In climate models the freezing condition is usually only applied at the surface. Hence, they are incapable of simulating brinicles – vertical sea-ice structures that can extend from the surface to shallower depths, sometimes even reaching the ocean floor. In my presentation, I will address whether such structures may have played a more prominent role during glacial periods, and whether localized deep ocean freezing may have been a possibility.

How to cite: Ishizu, M., Timmermann, A., and Yun, K.-S.: Super-cooled glacial deep waters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13226, https://doi.org/10.5194/egusphere-egu24-13226, 2024.

EGU24-14346 | Orals | CL1.2.6

Weathering of shelf sediments exposed during a glacial period: Evidence from geochemistry and Sr-Nd isotopes 

Gyana Ranjan Tripathy, Priyasha Negi, Rakesh Kumar Rout, and Ravi Bhushan

Erosion of continental rocks controls nutrient and sediment supply, soil formation and global climate. Intensity of this land-surface process is driven by both climatic (runoff, and temperature) and non-climatic (vegetation, lithology and basin slope) factors. Additionally, climatic-driven fluctuations in sea-level may also influence the exposed land-area, which is available for weathering. The coupling between exposed shelf sediments and weathering, however, has received limited attention. In this contribution, geochemical and Sr-Nd isotopic compositions of a sediment core (VM29-17PC) from the western Bay of Bengal have been investigated to reconstruct weathering and climate interaction during last glacial-interglacial cycle. Radiocarbon dating of foraminifera samples establishes that the core preserves a continuous erosional record for last 35 kyr.  Average Sr-Nd isotopic data for the decarbonated sediments confirm dominant sediment supply from the Higher Himalaya to the core site, with sub-ordinate input from the Deccan region. Temporal changes in the isotopic data hint at a sudden increase in the Himalayan source around 15 kyr BP, which is synchronous with the Bølling-Allerød (B/A) warm phase and the strengthening of the south-west (SW) monsoon. Downcore variation of Chemical Index of Alteration (CIA) and K/Al ratios indicates intensification of chemical weathering around 25 kyr BP. This change in weathering intensity is synchronous to dropping of sea level due to onset of glaciation. This sea-level regression and sudden rise in CaCO3 concentration during this period point to weathering of additional surface exposed in the shelf regions. This enhanced weathering of the shelf sediments may have contributed to the atmospheric CO2 level during the glacial period.

How to cite: Tripathy, G. R., Negi, P., Rout, R. K., and Bhushan, R.: Weathering of shelf sediments exposed during a glacial period: Evidence from geochemistry and Sr-Nd isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14346, https://doi.org/10.5194/egusphere-egu24-14346, 2024.

EGU24-14882 | ECS | Orals | CL1.2.6

Impact of marine productivity on atmospheric pCO2 during the Last Glacial Maximum: a model-data comparison 

Pauline Depuydt, Stéphanie Duchamp-Alphonse, Nathaelle Bouttes, Chiara Guarnieri, Alice Karsenti, Ji-Woong Yang, Jean-Yves Peterschmitt, and Amaëlle Landais

Measurements of the air trapped in Antarctic ice cores reveal that atmospheric CO2 concentration (pCO2) during the Last Glacial Maximum (LGM) was about 80 ppmv lower than that recorded during the current Holocene interglacial (Bereiter et al., 2015). Studies also show a strong link between pCO2, ice volume and Antarctic temperature, suggesting pCO2 as a forcing or amplifying factor behind glacial/interglacial cycles (Petit et al., 1999; Parrenin et al., 2013). Despite such importance in the global climate changes, mechanisms behind rapid variations in pre-anthropic pCO2 remain elusive. Numerical models emphasized the crucial role of exported marine productivity Pexp, (namely, the Soft Tissue Pump) in such changes. In particular, they feature marine productivity patterns from the Southern Ocean and show that a decrease in Pexp in the Sub-Antarctic zone, linked to a reduction in iron inputs from aeolian dusts, could have increased pCO2 by 20 to 50 ppmv (Köhler and Fischer, 2006; Martínez-Garcia et al., 2009; Lambert et al., 2012). However, these studies are usually compared to proxy data from the Atlantic sector of the Subantarctic Zone i.e., an area under the direct influence of wind fields that makes it possible to test the “Fe-hypothesis” (Martin et al., 1990) but that is not necessarily representative of the entire ocean (e.g. Lambert et al., 2015). Due to a lack of recent Pexp data compilation but also of direct comparisons with model outputs integrating marine biogeochemistry­­, it remains difficult to understand the role marine biological productivity exerted on the carbon cycle and more specifically on the low pCO2 during the LGM.

The aim of this study is to explore Pexp patterns during the LGM compared to the pre-industrial Holocene and understand the mechanisms driving their global changes, in order to try and estimate the contribution of marine productivity to the pCO2 signalbased on (i) a new compilation of Pexp proxy data using the strategy previously proposed by Kohfeld et al. (2005) after Bopp et al., (2003), and (ii) a comparison of these data to outputs from the iLOVECLIM intermediate complexity.

Proxy data show that Pexp is generally higher during the LGM compared to the pre-industrial Holocene. This is particularly the case in the sub-Antarctic and sub-Arctic areas, in the equatorial Atlantic Ocean and in coastal upwelling settings i.e., regions that usually witness higher nutrient content due to revigorated ocean circulation and/or intensified surface winds. Simulations generally confirm such features except from the coastal upwelling and the Southern Ocean, due to a lack of spatial resolution and of aeolian inputs in the model, respectively. However, preliminary results from sensitivity tests show (i) net marine productivity fronts around ~40°N and 45°S due to extended sea ice cover and reduced global temperature, (ii) a decreased Pexp in the Pacific Ocean due to an overall thermohaline circulation slow down and (iii) an increase of Pexp in areas where fertilization by iron-rich dusts is expected (Lambert et al., 2021).

How to cite: Depuydt, P., Duchamp-Alphonse, S., Bouttes, N., Guarnieri, C., Karsenti, A., Yang, J.-W., Peterschmitt, J.-Y., and Landais, A.: Impact of marine productivity on atmospheric pCO2 during the Last Glacial Maximum: a model-data comparison, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14882, https://doi.org/10.5194/egusphere-egu24-14882, 2024.

EGU24-14929 | ECS | Orals | CL1.2.6

Significant change in the flow regime in the deep Southern Ocean through the MPT 

Eva M. Rückert and Norbert Frank

The deep Southern Ocean (SO) circulation is of major significance for the understanding of the ocean´s impact on Earth’s climate as uptake and release of CO2 strongly depend on the redistribution of well and poorly ventilated water masses.

Neodymium isotopes (εNd) preserved in deep sea sediment have proven useful to study the Deep Ocean Circulation and water mass provenance and are of special interest over major climate changes as the Mid Pleistocene Transition (MPT). The MPT marks the change from a 41 ka to a 100 ka glacial-interglacial cyclicity and goes along with a significant intrusion of southern sourced waters (SSW) in the deep North Atlantic.

Here, we present the first millennial resolved authigenic εNd data in the Southern Atlantic spanning across  the MPT of a deep sea sediment core positioned at the polar front. The pre-MPT εNd values of ODP 1093 show a small variability of approx. 2 ε-units around the modern AABW signature of -8. In contrast, the post-MPT εNd variability increases to 6 ε-units with glacial extremes of around -3 – εNd values that can not be found in any Atlantic sourced water mass today!

This supports not only the exsiting hypotesis of stonger SSW export to the North, but rather advocates for a radiogenic  watermass influencing the flow regime in the Atlantic south of the polar front. Increasing ice volume during post-MPT glacials has been argued to lead to a reduced AABW production. Due to continuity of flow, this opens up the possiblity of glacial intrusion through the Drake passage of a water masses likely originating in the Pacific, which would generate  the strongly radiogenic glacial εNd values. At present Pacific deep waters are enriched with respired carbon. Assuming this to hold true in the past, the intrusion of such carbon rich water masses into the deep South Atlantic could further reinforce the strong glacials and the overall global cooling trend after the MPT as suggested previously.

Hence, the SO south of the polar front played a leading role in  reinjecting respired CO2 into the deep Atlantic Ocean and the Atmosphere during climate transitions. 

How to cite: Rückert, E. M. and Frank, N.: Significant change in the flow regime in the deep Southern Ocean through the MPT, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14929, https://doi.org/10.5194/egusphere-egu24-14929, 2024.

EGU24-15214 | Orals | CL1.2.6

Exploring the differing CO2 response to Dansgaard-Oeschger and Heinrich events 

Matteo Willeit, Daniela Dalmonech, Bo Liu, Tatiana Ilyina, and Andrey Ganopolski

Dansgaard-Oeschger (DO) and Heinrich (H) events are ubiquitous features of glacial climates involving abrupt and large changes in climate over the North Atlantic region, extending also to the Southern Hemisphere through the bipolar seesaw mechanism. Ice core data also indicate that the DO and H events are accompanied by pronounced changes in atmospheric CO2 concentration, but their origin remains uncertain. Here, we use simulations with the fast Earth system model CLIMBER-X, which produces self-sustained DO events as internal variability, to explore the processes involved in the atmospheric CO2 response. While the DO events are internally generated in the model, the Heinrich events are mimicked by adding a freshwater flux of 0.05 Sv over 1000 years in the latitudinal belt between 40°N and 60°N in the North Atlantic.
The simulated Greenland temperature varies by ~7-8°C between stadials and interstadials, with only small differences between H and DO stadials, while Antarctic temperature responds substantially stronger to H than to DO events, broadly in agreement with observations. In the CLIMBER-X simulations, atmospheric CO2 varies by ~5 ppm during DO events, but by ~15 ppm during H events, comparable with ice core data. The peak in CO2 concentrations is delayed by several centuries relative to both the stadial-interstadial transition and the peak in Antarctic temperature. The CO2 rise during the H stadial is driven by ocean outgassing. In contrast, the rapid CO2 increase after the transition to the interstadial results from soil carbon release from high NH latitudes originating from substantial warming.

How to cite: Willeit, M., Dalmonech, D., Liu, B., Ilyina, T., and Ganopolski, A.: Exploring the differing CO2 response to Dansgaard-Oeschger and Heinrich events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15214, https://doi.org/10.5194/egusphere-egu24-15214, 2024.

EGU24-15672 | ECS | Orals | CL1.2.6

Carbon and nitrogen stable isotopes across the last deglaciation: perspectives from snow petrel stomach oil deposits 

Thale Damm-Johnsen, Michael J. Bentley, Darren R. Gröcke, Dominic Hodgson, and Erin L. McClymont

Evidence from both marine and ice cores strongly indicates that surface ocean processes influencing air-sea gas exchange of the Southern Ocean played a crucial role in the transition from a glacial to interglacial climate state. However, few archives have been able to reconstruct how high latitude surface ocean processes affected the biogeochemical changes occurring in nutrient utilization, primary productivity, and their effects on carbon sequestering in ecosystems. An opportunity to explore these processes is provided by accumulated snow petrel (Pagodroma nivea) stomach oil deposits, defensively regurgitated by snow petrels at their nest sites. These deposits provide a record of biogeochemical processes in the austral summer, at a high trophic level and integrated over a relatively wide area defined by snow petrel foraging range. Here, we present a joint carbon and nitrogen stable isotope record from stomach oil deposits from the Lake Untersee nunataks in Dronning Maud Land (DML) integrating data from a coastal area of 65-70°S. Our results show a 3‰ offset in δ13C and 4‰ offset in δ15N between LGM and Holocene, indicating that the coastal high latitudes underwent large changes over the deglaciation. The δ15N depletion into the Holocene shows strong similarity to changes occurring in nutrient utilization along the margin of the polar front, indicating that the Southern Ocean high latitudes were not an isolated oasis during the LGM but biogeochemically connected to the surface ocean beyond the summer sea-ice margin. In addition, the presence of stomach oil deposits indicates that open water was present in summer along the coast of DML over both the LGM and Holocene. Such highly productive, open water areas were potentially an important factor in the air-sea gas exchange contributing to the deglacial atmospheric CO2 -rise.

How to cite: Damm-Johnsen, T., Bentley, M. J., Gröcke, D. R., Hodgson, D., and McClymont, E. L.: Carbon and nitrogen stable isotopes across the last deglaciation: perspectives from snow petrel stomach oil deposits, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15672, https://doi.org/10.5194/egusphere-egu24-15672, 2024.

EGU24-16591 | Orals | CL1.2.6

Bridging Proxy Discrepancies: SST Reconstructions from the Alboran Sea During the Last Glacial Maximum and Deglaciation.  

Alvaro Fernandez, Laura Rodríguez-Sanz, Victoria Taylor, Nele Meckler, and Francisca Martínez-Ruiz

The last glacial maximum (LGM) is the most recent time period in Earth’s history with a climate that was much colder than the present. Robust temperature reconstructions from this period are needed to improve estimates of Earth's climate sensitivity and aid in future climate change projections. However, reconstructing sea surface temperatures (SSTs) during this period can be challenging due to the various limitations with the commonly used proxies. Here, we present new SST estimates from the Alboran Sea in the Western Mediterranean, an area where existing SST records for the LGM (derived from UK37, TEX86, planktic foraminiferal Mg/Ca) show large disagreements. Our new SST estimates are based on clumped isotope analyses of planktic foraminifera (G. bulloides), the same species as used for the Mg/Ca measurements in this area. Due to the insensitivity of the clumped isotope thermometer to changes in seawater chemistry, our results offer new independent constraints on the range of temperature shifts between glacial and interglacial periods in this area. Our findings are evaluated against existing SST estimates, highlighting the benefits and limitations of different proxy estimates. We find that while all proxies agree on the general millennial scale temperature trends during the period of deglaciation, they diverge in the magnitude of these temperature changes. Temperature reconstructions derived from clumped isotopes align more closely with those based on alkenone and Mg/Ca proxies than with those from TEX86, which show large differences. Our research demonstrates that clumped isotopes are a potentially effective tool to improve the accuracy of climate reconstructions from the LGM and the subsequent deglacial period.

 

 

How to cite: Fernandez, A., Rodríguez-Sanz, L., Taylor, V., Meckler, N., and Martínez-Ruiz, F.: Bridging Proxy Discrepancies: SST Reconstructions from the Alboran Sea During the Last Glacial Maximum and Deglaciation. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16591, https://doi.org/10.5194/egusphere-egu24-16591, 2024.

EGU24-17501 | ECS | Posters on site | CL1.2.6

Constraining glacial ocean carbon cycle – A multi-model study 

Bo Liu, Tatiana Ilyina, Victor Brovkin, Matteo Willeit, Ying Ye, Christoph Völker, Peter Köhler, Malte Heinemann, Takasumi Kurahashi-Nakamura, André Paul, Michael Schulz, Ute Merkel, and Fanny Lhardy

The ocean contained a larger carbon content at the Last Glacial Maximum (LGM, ~21kyr before present) compared to the late Holocene, making a considerable contribution to the deglacial atmospheric CO2 rise of about 90 ppm. Yet, there’s no consensus on the mechanisms controlling the glacial-interglacial changes in oceanic carbon storage due to uncertainties and sparseness of proxy data. Numerical simulations have been widely used to quantify the impact of key factors, such as changes in sea surface temperatures, ocean circulation and biological production, on glacial ocean carbon sequestration. However, the robustness of these findings is subject to further testing due to the differences in process representation, parameterization, model architecture, or external forcing employed by models.

Towards further constraining the LGM ocean carbon cycle, we conducted a multi-model comparison with three comprehensive Earth System Models (Alfred Wegener Institute Earth System Model, AWI-ESM; Community Earth System Model, CESM; Max Planck Institute Earth System Model, MPI-ESM) and one Earth system Model of Intermediate Complexity (CLIMBER-X). We carried out three coordinated experiments with each model: 1) PI (the pre-industrial control simulation), 2) LGM-PMIP (following PMIP4 LGM protocol) and 3) LGM-LowCO2 (as LGM-PMIP, but with boosted alkalinity inventory to lower atmospheric CO2 to about 190 ppm. All experiments were conducted with the prognostic CO2 for the carbon cycle, considering only the atmosphere and ocean reservoirs, and prescribed CO2 for radiative forcing.

All models consistently show that applying the PMIP4 LGM boundary conditions alone leads to only a 5-40 ppm decrease in atmospheric CO2. Globally, the glacial CO2 drawdown in LGM-PMIP is mainly controlled by the enhanced solubility pump. The spatial distribution of the increased glacial DIC depends on the ocean circulation state in each model. In MPI-ESM and CLIMBER-X, the shallower and weaker AMOC facilitates carbon storage in the deep Atlantic. An LGM atmospheric CO2 of 190 ppm can be achieved by boosting alkalinity by 5-8% in scenario LGM-LowCO2. In all models, boosting LGM alkalinity inventory increases DIC in the bottom water. However, comparison to proxy data reveals that the models lack respired carbon, particularly in the deep Pacific. This suggests a need to enhance the glacial biological carbon pump in the models.

How to cite: Liu, B., Ilyina, T., Brovkin, V., Willeit, M., Ye, Y., Völker, C., Köhler, P., Heinemann, M., Kurahashi-Nakamura, T., Paul, A., Schulz, M., Merkel, U., and Lhardy, F.: Constraining glacial ocean carbon cycle – A multi-model study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17501, https://doi.org/10.5194/egusphere-egu24-17501, 2024.

EGU24-17778 | ECS | Orals | CL1.2.6

Physical and biological controls on deep Pacific carbon storage over the last glacial cycle 

Megan Pelly, Madison Shankle, Molly Trudgill, Bruno Millet, Chen Xu, Gwyn Owens, Hermione Owen, Alan Foreman, Thomas Bauska, Andy Ridgwell, Elisabeth Michel, William Gray, Andrea Burke, and James Rae

The ability of the deep ocean to store and exchange large quantities of CO2 with the atmosphere on relatively short timescales means that it is thought to play a key role in dictating glacial-interglacial changes in atmospheric CO2, however records of deep ocean carbon storage and release remain sparse. The Pacific Ocean contains the largest store of carbon in the ocean-atmosphere system. As a result, changes in its circulation dynamics and biogeochemistry have the potential to significantly impact global climate. Despite this, changes in Pacific conditions and carbon storage over the last glacial cycle are poorly constrained.

Here we present new geochemical proxy records from abyssal, deep, and intermediate depths in the Southwestern Pacific to determine the changes in deep ocean carbon storage over the last glacial cycle and the mechanisms involved in driving these changes. Foraminiferal trace element and stable isotope data indicate that increased carbon storage occurred over the course of the last glaciation, promoting a drawdown in atmospheric CO2. The processes involved in driving glacial ocean carbon storage are debated, however proxy data from these sites indicate that changes in circulation dynamics promoting the isolation and expansion of deep Pacific waters was likely a key process involved. Comparison of δ13C data to box model and Earth system model output provides further insight into the physical as well as biogeochemical mechanisms involved and their relative contributions at different stages over the last glacial cycle. This includes the role of Southern Ocean sea-ice expansion, reduced ocean temperatures, and increased Southern Ocean stratification and biological productivity. We find that physical processes dominate the early in the glacial cycle, with biological processes promoting further drawdown as glacial conditions intensify. These results help to improve the understanding of deep ocean carbon cycling over the last glacial cycle and provide a new framework with which to interpret proxy δ13C data.

How to cite: Pelly, M., Shankle, M., Trudgill, M., Millet, B., Xu, C., Owens, G., Owen, H., Foreman, A., Bauska, T., Ridgwell, A., Michel, E., Gray, W., Burke, A., and Rae, J.: Physical and biological controls on deep Pacific carbon storage over the last glacial cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17778, https://doi.org/10.5194/egusphere-egu24-17778, 2024.

EGU24-17827 | ECS | Orals | CL1.2.6

A million-year reconstruction of global volcanism intensity: How does it link to glaciation? 

Jack Longman, Thomas M. Gernon, Thea K. Hincks, Sina Panitz, and Martin R. Palmer

Reduced ice volume during interglacials is hypothesized to amplify volcanic activity because ice-mass removal reduces pressure on magma chambers (Huybers & Langmuir, 2009). There is some evidence for this process occurring on regional (Maclennan et al., 2002) and perhaps semi-global scales (Kutterolf et al., 2019), but there is a lack of globally representative tephra production records. Therefore, our understanding of the global relationship between glacial-interglacial cycles and volcanism uncertain. As a result, we do not know whether deglaciation directly drives enhanced volcanism, or if the feedbacks are more complex. In this work we use a database of visible tephra layers in marine sediments, and a weighted bootstrap resampling method to develop a record of global tephra (the products of explosive volcanism) production which covers the past million years.

Our results show an intensification of global tephra production around 420 to 400 thousand years ago (ka), which coincides with Marine Isotope Stage (MIS) 11 – the warmest interglacial of the past million years. MIS11 was a period of high sea level (up to 10 m above present) and low ice cover, with Greenland likely largely ice free. We suggest the low ice levels drove enhanced volcanism, and consequently enhanced volcanic carbon dioxide degassing, which in turn drove further ice sheet ablation. This positive feedback may the explain this warmth, and in turn, the Mid-Brunhes transition, which heralded the arrival of generally warmer interglacials after 400 ka. Further, after 400 ka we begin to see cyclicity in the tephra record, mirroring eccentricity forcing seen in ice volume records. More pronounced ice-volcano feedbacks may therefore explain the stronger interglacials of the past 400,000 years.

References

Huybers, P., & Langmuir, C. (2009). Feedback between deglaciation, volcanism, and atmospheric CO2. Earth and Planetary Science Letters, 286(3–4), 479–491.

Kutterolf, S., Schindlbeck, J. C., Jegen, M., Freundt, A., & Straub, S. M. (2019). Milankovitch frequencies in tephra records at volcanic arcs: The relation of kyr-scale cyclic variations in volcanism to global climate changes. Quaternary Science Reviews, 204, 1–16.

Maclennan, J., Jull, M., McKenzie, D., Slater, L., & Grönvold, K. (2002). The link between volcanism and deglaciation in Iceland. Geochemistry, Geophysics, Geosystems, 3(11), 1–25.

 

How to cite: Longman, J., Gernon, T. M., Hincks, T. K., Panitz, S., and Palmer, M. R.: A million-year reconstruction of global volcanism intensity: How does it link to glaciation?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17827, https://doi.org/10.5194/egusphere-egu24-17827, 2024.

The ocean plays an essential role in the rise of atmospheric CO2 by about 90 ppmv during the last deglaciation. The deglacial oceanic CO2 outgassing is jointly controlled by the physical, biological and geochemical processes, which affect the variations in ocean circulation, biological carbon pump and alkalinity inventory. Transient simulations of climate-carbon feedback, particularly using the comprehensive Earth System Models, are instrumental tools to quantify the contribution of different processes and their interactions. Nonetheless, knowledge gaps still exist in the deglacial variations of oceanic carbon and nutrient cycling because considerable model uncertainties arise from the choices of model processes and parameters, and the proxy data is too sparse to fully constrain the model outcome.

We conduct transient simulations for the last deglaciation with the Max Planck Institute Earth System Model (MPI-ESM) and examine the impact of different model tuning of the global ocean biogeochemistry component and a sediment module on the deglacial CO2 outgassing. The atmospheric CO2 is prognostically computed for the carbon cycle, considering only the atmosphere and ocean compartments, and it is prescribed for radiation computation. We force the model with reconstructions of atmospheric greenhouse gas concentrations, orbital parameters, ice sheet and dust deposition. In line with the physical ocean component, we account for the automatic adjustment of marine biogeochemical tracers in response to changing bathymetry and coastlines related to deglacial meltwater discharge and isostatic adjustment.

We find the deglacial CO2 outgassing is mainly driven by the sea surface warming in MPI-ESM, whereas variations in surface alkalinity and DIC have a relatively small contribution (~18%). Furthermore, the parameterisation of organic debris remineralisation considerably affects the deglacial increase in the global NPP due to different recycling rates of nutrients in the upper ocean. When a longer lifetime of dissolved organic matter is prescribed, the dissolved organic carbon pool in the glacial ocean increases, further facilitating the glacial ocean carbon sequestration. Including an interactive sediment module strongly impacts surface alkalinity due to input-sedimentation imbalance, affecting air-ocean CO2 flux. Thus, attention has to be given to tuning and adjustments regarding the input-sedimentation imbalance of alkalinity in ESMs to better represent proxy data and the deglacial oceanic CO2 outgassing.

How to cite: Liu, B. and Ilyina, T.: Quantifying the role of ocean biogeochemistry on the deglacial atmospheric CO2 rise using transient simulations with MPI-ESM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18082, https://doi.org/10.5194/egusphere-egu24-18082, 2024.

EGU24-18786 | ECS | Posters on site | CL1.2.6

Mechanisms of atmospheric CO2 drawdown during Marine Isotope Stage 4 based on Atlantic deep-water temperature and bottom-water oxygenation reconstructions  

Svetlana Radionovskaya, Julia Gottschalk, David Thornalley, Mervyn Greaves, and Luke Skinner

Understanding the evolution of deep ocean circulation and chemistry over the last glacial cycle is key to elucidating the ocean’s role in modulating atmospheric CO2 changes on millennial and orbital timescales. MIS 4 is a key paleoclimatic interval of the last glacial inception for assessing the role of the deep-ocean carbon storage in driving atmospheric CO2 levels, because it is characterized by a large decrease of air temperature and a rapid atmospheric CO2 drop of ~40 ppmv, and includes several millennial climatic events, for example Heinrich Stadial 6. Although various paleo proxy records suggest a weakened Atlantic overturning during MIS 4, and particularly HS 6, changes in AMOC strength and the geometric extent of NADW shoaling remain poorly understood. Here, we present deep-water temperature reconstructions based on infaunal benthic foraminiferal Mg/Ca ratios and bottom water oxygen concentration reconstructions using redox-sensitive foraminiferal U/Ca, from the deep North (~2.65km) and South (~3.8km) Atlantic to assess the changes in deep water hydrography and by extension circulation.

Our reconstructed deep-water temperature changes from the Iberian Margin (~2.65 km water depth) suggest a stronger influence of colder southern sourced waters during MIS 4 and particularly during HS 6; and a clear subsurface warming during MIS 5a stadials. Meanwhile, changes in deep-water temperatures in the Atlantic Sector of the Southern Ocean (SO) closely follow variations in Antarctic temperature, atmospheric CO2 and the mean ocean temperature, likely mediated by buoyancy forcing in the SO, which is in turn likely linked to sea-ice expansion at the MIS 5a/4 transition. Together with (arguably smaller) contributions from reduced air-sea gas exchange efficiency in the SO, these combined changes would have lowered atmospheric CO2through more efficient carbon sequestration in an expanded deep Atlantic reservoir during MIS 4, through their impact on the solubility- and soft tissue “pumps” (i.e. the ocean’s disequilibrium and respired carbon budgets). Indeed, bottom water oxygenation reconstructions from the South Atlantic support the conclusion that the Southern Ocean appears to have represented a significant reservoir for sequestering CO2 away from the atmosphere during MIS 4.

How to cite: Radionovskaya, S., Gottschalk, J., Thornalley, D., Greaves, M., and Skinner, L.: Mechanisms of atmospheric CO2 drawdown during Marine Isotope Stage 4 based on Atlantic deep-water temperature and bottom-water oxygenation reconstructions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18786, https://doi.org/10.5194/egusphere-egu24-18786, 2024.

EGU24-19515 | Posters on site | CL1.2.6

Sea surface temperature variations in the Eastern Equatorial Pacific (ODP Site 1240) over the last 160 kyr from three lipid paleothermometers (UK'37, TEXH86 and LDI) 

Eva Calvo, Lucía Quirós-Collazos, Marta Rodrigo, Stefan Schouten, Jaap Sinninghe-Damsté, Leopoldo Pena, Isabel Cacho, and Carles Pelejero

The Pacific Ocean equatorial upwelling region is of great interest to understand climate dynamics within the context of current global change. It plays a key role in global biogeochemical cycles, especially in the carbon cycle, as it stands for being one of the areas with largest CO2 fluxes from the ocean to the atmosphere. Moreover, tropical regions play a key role in regulating global climate, since they control the transfer of thermal energy from low to high latitudes. In this context, and with the aim of reconstructing paleoclimate conditions at glacial-interglacial time scales in this region, we analysed selected molecular biomarkers in the marine sediment core ODP 1240, at the easternmost region of the Eastern Equatorial Pacific (EEP), covering the last 160 kyr. We focused on long-chain alkenones, glycerol dialkyl glycerol tetraethers (GDGTs) and long-chain alkyl diols (LCDs). Upon quantification of these lipids, we calculated the UK'37, TEXH86 and LDI indices, and discussed their suitability as paleotemperature proxies to reconstruct sea surface conditions in the study region. We found that UK'37 and TEXH86 derived-temperatures track the warming and cooling trends typical of glacial-interglacial variations. However, while they provide similar temperatures during the last two interglacial maxima, they disagree during glacial periods, when the TEXH86-based estimations display significantly cooler temperatures. The LDI-derived record also shows similar temperatures to those from the UK'37 and TEXH86during the more recent interglacial but, for the last glacial-interglacial period, LDI-derived temperatures remain colder than those of the UK’37 and even colder than those of the TEXH86 at some periods. Multiple factors could be behind this variability and disagreement between the three paleothermometers: depth dwelling, production or exportation of the different biological producers of each lipid, seasonality, diagenetic processes and changes in biogeochemistry conditions of the studied marine region, amongst others. In this presentation, the factors that we believe are most important in the study region will be presented and discussed, to improve our understanding of the biological dynamics of the precursors of each proxy and of their reconstructed marine temperatures in the EEP.

How to cite: Calvo, E., Quirós-Collazos, L., Rodrigo, M., Schouten, S., Sinninghe-Damsté, J., Pena, L., Cacho, I., and Pelejero, C.: Sea surface temperature variations in the Eastern Equatorial Pacific (ODP Site 1240) over the last 160 kyr from three lipid paleothermometers (UK'37, TEXH86 and LDI), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19515, https://doi.org/10.5194/egusphere-egu24-19515, 2024.

EGU24-19780 | Orals | CL1.2.6

The influence of proglacial lakes on climate and surface mass balance of retreating ice sheets: A study of the Laurentide and Fennoscandian ice sheets at 13 ka BP 

Uta Krebs-Kanzow, Lianne Sijbrandij, Gregor Knorr, Lars Ackermann, Lu Niu, and Gerrit Lohmann

During the last deglaciation large proglacial lakes formed at the base of the retreating northern hemisphere ice sheets. We assess the effect of these ice-contact lakes on regional climate and on the ice sheet surface mass balance components of the adjacent  Laurentide (LIS) and Fennoscandian (FIS) ice sheets,  using an atmosphere general circulation model with a novel extension for proglacial lakes in combination with a surface mass balance scheme for ice sheets, which, for the first time, allows to estimate the effect of the cold surface of these extensive lakes on the surface mass balance of the adjacent ice sheets. In a set of simulations inspired by the  Allerød interstadial around 13000 years before present, we demonstrate that the presence of proglacial lakes significantly reduces summer air temperatures in a larger area around the proglacial lakes and leads to reduced precipitation with increased snow/rain ratio. In consequence surface ablation reduces by 39% over the FIS and 28% over the LIS while accumulation only changes slightly by 1% and -3%  respectively. About one quarter of the response in surface ablation is related to the perennially cold surface of the proglacial lakes.

How to cite: Krebs-Kanzow, U., Sijbrandij, L., Knorr, G., Ackermann, L., Niu, L., and Lohmann, G.: The influence of proglacial lakes on climate and surface mass balance of retreating ice sheets: A study of the Laurentide and Fennoscandian ice sheets at 13 ka BP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19780, https://doi.org/10.5194/egusphere-egu24-19780, 2024.

EGU24-299 | ECS | PICO | CL1.2.7

Sea ice distribution in the northeastern Nordic Seas during the Dansgaard-Oeschger events 

Wanyee Wong, Bjørg Risebrobakken, Kirsten Fahl, Rüdiger Stein, Eystein Jansen, and Juliette Supiot Tessier

Sea ice conditions in the eastern Fram Strait during the Dansgaard-Oeschger (D-O) events are reconstructed using biomarkers. The role of the Nordic Seas sea ice has long been recognized as a significant factor influencing the D-O climate changes. Two full D-O cycles between 40 and 34 ka b2k, covering Greenland Stadial (GS) 9, also known as Heinrich Stadial (HS) 4, to Greenland Interstadial (GI) 7 are investigated in high resolution (20-40 yr/sample). Preliminary results suggest an extended sea ice cover in the eastern Fram Strait during both stadials. Repeated polynyas were present during GS-9/HS-4, but not during GS-8. The retreat of the extended sea ice cover in the eastern Fram Strait occurred later during the GS-9/HS-4 to GI-8 transition than during the GS-8 to GI-7 transition. Both interstadials were characterized by a seasonal sea ice cover, with the summer/fall sea ice edge occasionally moving farther north than the study site. Our findings provide new insights on the importance of ocean-ice processes in driving the D-O events.

How to cite: Wong, W., Risebrobakken, B., Fahl, K., Stein, R., Jansen, E., and Supiot Tessier, J.: Sea ice distribution in the northeastern Nordic Seas during the Dansgaard-Oeschger events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-299, https://doi.org/10.5194/egusphere-egu24-299, 2024.

EGU24-1337 | ECS | PICO | CL1.2.7

Changes in atmospheric dynamics over Dansgaard-Oeschger climate oscillations around 40 ka and its impact on Europe 

Kim Helen Stadelmaier, Patrick Ludwig, Joaquim G. Pinto, and Gábor Újvári

Dansgaard-Oeschger (D-O) climate variability during the last glaciation was first evidenced in ice cores and marine sediments, and is also recorded in various terrestrial paleoclimate archives in Europe. The relative synchronicity across Greenland, the North Atlantic and Europe implies a tight and fast coupling between those regions, most probably effectuated by an atmospheric transmission mechanism. In this study, we investigated the atmospheric changes during Greenland interstadial (GI) and stadial (GS) phases based on regional climate model simulations using two specific periods, GI-10 and GS-9 both around 40 ka, as boundary conditions. Our simulations accurately capture the changes in temperature and precipitation as reconstructed by the available proxy data. Moreover, the simulations depict an intensified and southward shifted eddy-driven jet during the stadial period. Ultimately, this affects the near-surface circulation towards more southwesterly and cyclonic flow in western Europe during the stadial period, explaining much of the seasonal climate variability recorded by the proxy data, including oxygen isotopes, at the considered proxy sites.

How to cite: Stadelmaier, K. H., Ludwig, P., Pinto, J. G., and Újvári, G.: Changes in atmospheric dynamics over Dansgaard-Oeschger climate oscillations around 40 ka and its impact on Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1337, https://doi.org/10.5194/egusphere-egu24-1337, 2024.

EGU24-1582 | PICO | CL1.2.7

Dansgaard-Oeschger events in a box ocean model 

Andrey Ganopolski

A generic nine-box ocean model (GNOM) is developed to study the stability and variability of the Atlantic Meridional Overturning Circulation (AMOC). Using this model, it is shown that centennial to millennial time scale self-sustained oscillations in AMOC strength and associated climate characteristics resembling temporal dynamics of observed Dansgaard-Oeschger events appear within a certain range of the boundary conditions (temperature and freshwater flux). Adding white noise to the system makes such oscillations more robust, i.e. they occur within a larger area in the phase space of temperature-freshwater forcing. However, regardless of the model’s parameters and boundary conditions, the typical periodicity of such oscillations is about 1000 years, which is much shorter than the typical recurrence time of observed  Dansgaard-Oeschger events. Only after adding an interaction with an additional component, which has a longer internal time scale and mimics the response of the surrounding ice sheets, do much longer self-sustained oscillations of AMOC arise.  

How to cite: Ganopolski, A.: Dansgaard-Oeschger events in a box ocean model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1582, https://doi.org/10.5194/egusphere-egu24-1582, 2024.

EGU24-5094 | ECS | PICO | CL1.2.7

Spontaneous Dansgaard–Oeschger type oscillations in three models: the impact of CO2 

Irene Malmierca Vallet, Louise C. Sime, Paul J. Valdes, Marlene Klockmann, Guido Vettoretti, and John Slattery

Greenland ice core records feature Dansgaard–Oeschger (D-O) events, which are abrupt warming episodes followed by gradual cooling during ice age climate. The three climate models used in this study (CCSM4, MPI-ESM, and HadCM3) show spontaneous self-sustained D-O-like oscillations (albeit with differences in amplitude, duration and shape) in a remarkably similar, narrow window of carbon dioxide (CO2) concentration, roughly 185-230 ppm. This range matches atmospheric CO2 during Marine Isotopic Stage 3 (MIS 3: between 27.8 – 59.4 thousand of years BP, hereafter ka), a period when D-O events were most frequent. Insights from the three climate models point to NA sea-ice coverage as a key ingredient behind D-O type oscillations, which acts as a tipping point. No other climate property (NA salinity, Atlantic Meridional Overturning Circulation, Global mean Ocean temperature and Global mean temperature) is found to directly determine whether D-O type behaviour can occur in all three models.

How to cite: Malmierca Vallet, I., Sime, L. C., Valdes, P. J., Klockmann, M., Vettoretti, G., and Slattery, J.: Spontaneous Dansgaard–Oeschger type oscillations in three models: the impact of CO2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5094, https://doi.org/10.5194/egusphere-egu24-5094, 2024.

EGU24-6161 | ECS | PICO | CL1.2.7

The Temporal Phasing of Rapid Dansgaard–Oeschger Warming Events Cannot Be Reliably Determined 

John Slattery, Louise C. Sime, Francesco Muschitiello, and Keno Riechers

Dansgaard–Oeschger (DO) warming events occurred throughout the last glacial period. Greenland ice cores show a rapid warming during each stadial to interstadial transition, alongside abrupt loss of sea ice and major reorganisation of the atmospheric circulation. Other records also indicate simultaneous abrupt changes to the oceanic circulation. Recently, an advanced Bayesian ramp fitting method has been developed and used to investigate time lags between transitions in these different climate elements, with a view to determining the relative order of these changes. Here, we subject this method to a critical review. Using ice core data, climate model output, and carefully synthesised data representing DO warming events, we demonstrate that the method suffers from noise-induced bias of up to 15 years. This bias means that the method will tend to yield transition onsets that are too early, and we find that the estimated timings of noisier transitions are more strongly biased. Further investigation of DO warming event records in climate models and ice core data reveals that the bias is on the same order of magnitude as potential timing differences between the abrupt transitions of different climate elements. Additionally, we find that higher-resolution records would not reduce this bias. We conclude that time lags of less than 20 years cannot be reliably detected, as we cannot exclude the possibility that they result solely from the bias. This prevents the unambiguous determination of the temporal phasing of DO warming events.

How to cite: Slattery, J., Sime, L. C., Muschitiello, F., and Riechers, K.: The Temporal Phasing of Rapid Dansgaard–Oeschger Warming Events Cannot Be Reliably Determined, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6161, https://doi.org/10.5194/egusphere-egu24-6161, 2024.

Dansgaard-Oeschger (DO) events are a dominant mode of millennial-scale climate variability during the last glacial period. While the influences of DO events are most pronounced in the North Atlantic region, their impacts are detectable on the global scale. In Antarctica, their imprint primarily manifests as a muted and anti-phased response, which can be explained by the bipolar seesaw mechanism. However, the ice core record revealed an additional in-phase component, suggesting the presence of atmospheric teleconnections.

Here, we study the propagation of DO-type signals from the North Atlantic to the Southern Hemisphere in a set of simulations with the general circulation model HadCM3, including an isotope-enabled run. The simulations show spontaneous DO-type oscillations under glacial boundary conditions, which allows studying the timing and interaction of atmospheric and oceanic processes under a continuously varying background state. Consistent with the ice core record, we find a muted and anti-phased temperature response over Antarctica that lags the North Atlantic by ~300 years, and global sea surface temperature patterns in agreement with the bipolar seesaw mechanism. Additionally, we identify a robust Southern Hemisphere mode in phase with the North Atlantic. This mode is associated with hydroclimate changes in the tropical Pacific, which modulate the Southern Hemisphere atmospheric circulation, and, thereby, impact Antarctic temperatures. Notably, the dominant millennial-scale circulation pattern exhibits zonal asymmetries that do not resemble the leading modes of inter-annual variability. Preliminary analyses indicate a good agreement of the simulated millennial-scale variability in oxygen isotopes with a global compilation of speleothem and ice core records.

How to cite: Trombini, I., Weitzel, N., Valdes, P., and Rehfeld, K.: Interhemispheric teleconnections as drivers of Southern Hemisphere climate in simulations of spontaneous Dansgaard-Oeschger-type events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9642, https://doi.org/10.5194/egusphere-egu24-9642, 2024.

The Dansgaard-Oeschger (DO) events are characteriszed by pronounced abrupt changes in climatic conditions in high northern latitudes. While they have first been discovered in Greenland ice core records, their imprints are global and can be deteced in proxy archives across the globe. They can be considered as the archetype of abrupt climate changes for which empirical evidence exists, but have not yet been fully explained. In this talk I will present some recent results from analyzing ice-core derived time series with a focus on dating uncertainties, from concentual models proposing unerling physical mechanisms, and from comparing spatial patterns of the impacts of the DO events on global atmospheric circulation patterns. 

How to cite: Boers, N.: Dansgaard-Oeschger events - time series analysis and modelling across the hierarchy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10896, https://doi.org/10.5194/egusphere-egu24-10896, 2024.

EGU24-12366 | PICO | CL1.2.7

Stadial to interstadial hydrographic changes in the northern Nordic Seas  

Bjørg Risebrobakken, Dang Inge Blindheim, Amandine Tisserand, Wanyee Wong, Adrian Kryk, and Małgorzata Bąk

New multiproxy records informing in unprecedented detail on hydrographic changes in the northernmost Nordic Seas during Dansgaard-Oechger events, will be presented. An extensive sea ice cover and a homogenous intermediate water mass have been suggested to characterize the Nordic Seas during stadials, based on records from the southern Nordic Seas. Combined planktic and benthic oxygen and carbon isotopes informing on water mass stratification and ventilation, supplemented by planktic Mg/Ca, planktic and benthic foraminiferal abundance, Ice Rafted Debris, diatom, and biomarker data suggests, however, less stable stadial water column conditions in the Fram Strait. The stadial to interstadial transitions are characterized by a series of short living changes in productivity, water mass characteristics and IRD deposition. The new records from the Fran Strait will be see in context of comparable records from other sites in the Nordic Seas. Implications of the new results will be discussed.

How to cite: Risebrobakken, B., Blindheim, D. I., Tisserand, A., Wong, W., Kryk, A., and Bąk, M.: Stadial to interstadial hydrographic changes in the northern Nordic Seas , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12366, https://doi.org/10.5194/egusphere-egu24-12366, 2024.

EGU24-17661 | PICO | CL1.2.7

Spatial patterns of DO events in Greenland ice core chemistry 

Helle Astrid Kjær, Bo Vinther, Anders Svensson, Sune Rasmussen, Thomas Blunier, Tobias Erhardt, margareth Harlan, Paul vallelonga, Niccolo Maffezoli, Vasileios Gkinis, Todd Sowers, Andy Menking, Aylin deCampo, Valerie Morris, Bruce Vaughn, Christo Buizert, and Jørgen Peder Steffensen
Deep ice core drilling efforts have been ongoing since the 1960’ and several records of Greenland impurities exist thanks to huge multiple nation efforts and the work of many dedicated people over the years and include Camp Century, Dye3, GRIP, GISP2, Renland, NGRIP, NEEM, RECAP and the new EGRIP ice core. 
The 25 Dansgaard-Oeschger (DO) events, first named in the Greenland ice core δ 18O signal from GRIP, are found in all deep Greenland ice cores with a significant corresponding signal also reflected in chemistry and impurities contained in the ice. 
 
Continuous flow analysis (CFA) is the preferred method  to investigate the long Greenland ice cores for their impurity content and often includes NH4+ , Ca2+ , and Na+ ions, while Ion Chromtography (IC) was previously utilized. The chemical impurities besides being influenced by transport and accumulation patterns, provide information about forest fires, wind-blown dust, and sea ice, respectively. 
 
We show here CFA measurements performed in Copenhagen in 2019 on the Dye3 old core at depths of 1753–1820m and 1865–1918m representing both Holocene, Younger Dryas and Glacial sections (GS 5 to 12) and the high accumulation RECAP ice core CFA profile. The ReCAP ice core extends 584.11m and while the glacial section is strongly thinned and covers just 20 meters of the ReCAP core, it nonetheless due to the high resolution of the CFA measurements done in 2015 and 2016, cover all 25 expected DO event.
 
Here we present these two datasets of Dye 3 and RECAP by CFA done at University of Copenhagen and compare for DO'swith other central Greenland ice cores with the aim to constrain spatial patterns of DO events in Greenland ice core chemistry records. 

How to cite: Kjær, H. A., Vinther, B., Svensson, A., Rasmussen, S., Blunier, T., Erhardt, T., Harlan, M., vallelonga, P., Maffezoli, N., Gkinis, V., Sowers, T., Menking, A., deCampo, A., Morris, V., Vaughn, B., Buizert, C., and Steffensen, J. P.: Spatial patterns of DO events in Greenland ice core chemistry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17661, https://doi.org/10.5194/egusphere-egu24-17661, 2024.

EGU24-19161 | ECS | PICO | CL1.2.7

Persistent shallow subsurface warming during North Atlantic Stadials drives ice-destabilisation and rapid climate change 

Eloise Littley, Andrea Burke, Madison Shankle, William Gray, Xu Zhang, Yuchen Sun, William Roberts, Yvan Rome, Ruza Ivanovic, and James Rae

The last ice age was repeatedly punctuated by millennial scale intervals of extreme cold in the Northern Hemisphere. These cold periods, known as stadials, are also times of ice calving and glacial melt, sending debris-laden icebergs into the North Atlantic Ocean, and raising questions about the mechanisms of ice sheet instability. Here, we provide new high resolution marine temperature reconstructions from the northeast north Atlantic (ODP 980 55°29.1’N 14°42.1’W) that show that, whilst persistent cold stadial temperatures might be inferred from abundances of the polar foraminifera Neogloboquadrina pachyderma (% N. pachyderma), Mg/Ca temperature reconstructions from the same planktic species and Globigerina bulloides indicate gradual subsurface warming by as much as 3ᵒC over the course of a stadial. We explain this apparent discrepancy by turning to the seasonal influences on these temperature proxies, suggesting that very high % N. pachyderma reflects preferential survival of this species in polar waters with extensive sea ice, while Mg/Ca reveals relatively mild subsurface conditions during the summer growing season. Modelling shows that warming summers in the high latitude subsurface may be explained by persistent influence of warm waters from lower latitudes, in combination with a lack of winter heat loss due to the insulating effect of sea ice and climbing atmospheric CO2. This accumulation of heat at critical depths for marine terminating glaciers underlines the influence of warming seawater on ice sheet stability and could provide an additional source of heat to trigger abrupt interstadial warming.

How to cite: Littley, E., Burke, A., Shankle, M., Gray, W., Zhang, X., Sun, Y., Roberts, W., Rome, Y., Ivanovic, R., and Rae, J.: Persistent shallow subsurface warming during North Atlantic Stadials drives ice-destabilisation and rapid climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19161, https://doi.org/10.5194/egusphere-egu24-19161, 2024.

EGU24-20201 | ECS | PICO | CL1.2.7

Causal drivers of North Atlantic glacial climate variability 

Tamas Kovacs, Evgenia Galytska, Matthias Prange, André Paul, and Michael Schulz

Terrestrial and marine proxy records suggest that climate variability was higher during the last glacial cycle than today. This is particularly true in the North Atlantic region where this enhanced variability is associated with changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) on different time scales. Despite prolonged efforts to explain an oscillatory behaviour of glacial AMOC strength, it is still not fully understood; moreover, studies often describe its mechanism qualitatively or attempt to identify its drivers using methods that do not imply causation.

In this study we use the isotope-enabled Earth system model iCESM1.2 to simulate the glacial climate under conditions representing the Marine Isotope Stage 3 (about 38 thousand years before present). Our results show the AMOC oscillating with a period of roughly 500 years and an amplitude of 4 Sv (1 Sv = 106 m3s-1). Surface air temperature varies by about 1-2°C in Northern Europe, 4°C in Greenland, and up to 15°C over the North Atlantic Ocean where sea ice cover varies the most. Based on a supervised machine learning method (causal discovery), we find causal links between AMOC and North Atlantic Ocean salinity and meridional salt transport. We show how changes in the salinity of water advected into key deep-water forming areas feed back to the AMOC, thus driving the oscillation.

Our findings from applying causal discovery outline the mechanism of a salt-oscillator in a fully coupled model, and indicate the potential of this method to identify causal drivers that trigger variations in AMOC strength on different time scales too.

How to cite: Kovacs, T., Galytska, E., Prange, M., Paul, A., and Schulz, M.: Causal drivers of North Atlantic glacial climate variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20201, https://doi.org/10.5194/egusphere-egu24-20201, 2024.

EGU24-20346 | PICO | CL1.2.7

Dansgaard Oeschger event and its dependence on background glacial climate condition simulated in a coupled Atmosphere-Ocean GCM, MIROC 

Ayako Abe-Ouchi, Wing-Le Chan, Sam Sherriff-Tadano, Takashi Obase, Yuta Kuniyoshi, Takahito Mitsui, and Christo Buizert

Glacial periods were punctuated by abrupt millennial scale climate changes, such as Dansgaard Oeschger events, Boeling-Allerod and Younger Dryas. Although glacial abrupt climate changes were shown to have a strong link to the Atlantic Meridional overturning circulation (AMOC) changes and the glacial background climate, simulating the stability and millennial change of AMOC and climate with fully coupled ocean-atmosphere GCM have been challenging. Here we present many cases of millennial scale climate variability with our Atmospheric Ocean coupled GCM, MIROC4m. A series of long transient experiments (> 10, 000 years) were performed systematically with different steady glacial conditions (CO2 level, obliquity, precession, meltwater, ice sheet size), to study the dependence of the sweet spot of millennial scale variability on the background climate and summarize the results as phase diagrams. We chose the model version which we simulate LGM AMOC weaker and shallower than the AMOC under Pre-Industrial condition. A reasonable sweet-spot of oscillation exists when the Northern Hemisphere ice sheets exist even without freshwater perturbation. In the sweet spot, self-sustained oscillation with bipolar seesaw pattern and shift between interstadial and stadial occur, with interval between abrupt events ranging from 1000 years to more than 5000 years depending on the background condition, while an abrupt shift from stadial to interstadial mode occurs in about 100 years. The sweet spot exists when the CO2 level is between 260ppm and 185ppm, depending largely on the obliquity but marginally on the precession and ice sheet size. When the obliquity or the CO2 amount is large (small), the AMOC is in a strong (weak) stable mode of about 18 (10) Sv (Sverdrup). Many aspects of the sweet spot, i.e., the duration of interstadial is longer systematically when the CO2 or obliquity is larger and the relation between the duration of interglacial and Antarctica air temperature, are very much in agreement with the ice core analysis and the deep-sea sediment.

How to cite: Abe-Ouchi, A., Chan, W.-L., Sherriff-Tadano, S., Obase, T., Kuniyoshi, Y., Mitsui, T., and Buizert, C.: Dansgaard Oeschger event and its dependence on background glacial climate condition simulated in a coupled Atmosphere-Ocean GCM, MIROC, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20346, https://doi.org/10.5194/egusphere-egu24-20346, 2024.

EGU24-22546 | PICO | CL1.2.7

Dansgaard-Oeschger events in climate models - criteria for model assessment 

Sudipta Goswami and Irene Malmierca-Vallet

Greenland ice core records feature Dansgaard–Oeschger (D-O) events; abrupt warming episodes followed by a gradual cooling phase during mid-glacial periods. Here, we analyse spontaneous self-sustained D-O type oscillations reproduced in four climate models: COSMOS, CCSM4, MPI-ESM and HadCM3. We assess model performance against several metrics: rate of Antarctic warming during D-O stadials, timing of change point in Antarctic temperature with respect to the mid-point of the Greenland transition, duration of the D-O event and Intertropical Convergence Zone (ITC) position. The four models suggest consistently that the amplitude and spatial expression of D-O event temperature anomalies are dominated by coupled changes in the Atlantic Meridional Overturning Circulation (AMOC) and North Atlantic sea ice extent.

How to cite: Goswami, S. and Malmierca-Vallet, I.: Dansgaard-Oeschger events in climate models - criteria for model assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22546, https://doi.org/10.5194/egusphere-egu24-22546, 2024.

EGU24-810 | ECS | Posters on site | CL1.2.9 | Highlight

Investigating the drivers of abrupt Antarctic sea ice decline 

Chun Yin Chan, Mark England, James Screen, Thomas Bracegirdle, and Ed Blockley

Antarctic sea ice cover experienced an abrupt decline in 2016, transitioning from a record maximum state to a record minimum state. However, the drivers of this rapid retreat are currently not well understood. Therefore, it is difficult to determine whether this signals the start of a long term melting trend, as has been long anticipated by climate models, or is an isolated episode of internal climate variability. In this study, we utilise the CMIP6 archive to understand if internal climate variability could be responsible for this Antarctic sea ice anomaly, and if so what the primary atmospheric and oceanic drivers are. This involves examining composites of the tropical teleconnections, subsurface ocean heat content, and high latitude atmospheric variability preceding extreme Antarctic sea ice anomalies in CMIP6 simulations. The primary objective is to elucidate the multifaceted factors influencing these extreme events, specifically addressing the 2016-2017 sea ice retreat, with lessons for 2023’s extreme Antarctic sea ice state. Initial results indicate that such events are possible in the absence of anthropogenic emissions in some climate models, although the occurrences are considered rare. We also show that that using the limited observed record alone will underestimate the interannual variability of the Antarctic sea ice cover and therefore overestimate how rare such an anomaly would be. In fact, if we extend the observed record further back using statistical reconstructions, rapid declines of sea ice extent occurred in the early and mid 20th century.  Our results highlight the importance of internal climate variability in the Southern high latitudes and advance our understanding of the drivers and predictability of Antarctic sea ice changes. We discuss the implications of this work for 2023’s record Antarctic sea ice anomaly.

How to cite: Chan, C. Y., England, M., Screen, J., Bracegirdle, T., and Blockley, E.: Investigating the drivers of abrupt Antarctic sea ice decline, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-810, https://doi.org/10.5194/egusphere-egu24-810, 2024.

EGU24-894 | ECS | Orals | CL1.2.9

On the atmospheric response to idealized freshwater input around Antarctica 

Xiaoqi Xu, Torge Martin, and Rebecca Beadling

The enhanced mass loss from the Antarctic ice sheet (AIS) and ice shelves has recently gained greater attention. Most climate models lack an interactive ice sheet and meltwater runoff is prescribed instead. The implications of AIS meltwater are studied most often with a focus on ocean and sea ice. We show that the changing surface conditions trigger an atmospheric response as well with consequences extending into the stratosphere. The release of meltwater into the Southern Ocean has important impacts on the ocean temperature, stratification, currents, and sea ice properties. Remote atmosphere responses tied to a shift in the ITCZ were reported as well, such as changes in (sub-)tropical precipitation.However, patterns and magnitudes of the various responses remain uncertain due to varying ways of freshwater forcing input and model uncertainty. Thus, the Southern Ocean Freshwater Input from Antarctica (SOFIA) initiative has been formed to demonstrate the robustness and quantify the uncertainty of such responses. About a dozen modeling groups participate in running the same 100-year freshwater-release experiment (0.1 Sv distributed uniformly to the ocean surface along the Antarctic coast under preindustrial forcing) with a range of state-of-the-art climate models (Swart et al., 2023, GMD, accepted).

Using the SOFIA multi-model ensemble, we study the atmospheric response to the additional freshwater. First results are based on an 8-member ensemble using GEOMAR’s Flexible Ocean and Climate Infrastructure (FOCI) model. Sea level pressure and surface air temperature over Antarctica and the Southern Ocean decline and westerly winds from 40°S to 60°S strengthen. Significant atmosphere cooling, with the maximum zonal-mean anomaly of up to 0.6oC near the surface, extends to 300 hPa. This is accompanied by a weak but significant warming in the lower stratosphere, which is likely associated with a slight lowering of the tropopause or enhanced wave propagation. The zonal winds strengthen on the southern flank of the westerlies belt with a maximum at 300 hPa, the level of the jet stream core. A corresponding intensification of the Ferrell cell is found as well. The circulation changes are caused by near-surface cooling and buoyancy reduction at polar latitudes, enhancing the meridional temperature and pressure gradients. These responses have strong seasonal patterns with strongest tropospheric imprints in austral winter and a stratosphere response in late winter/spring---despite the prescribed freshwater release being constant in time without seasonal cycle. We suggest that changing sea ice conditions play a key role in creating the seasonal response.

These first results have been confirmed by a parallel study using the GFDL climate model. We will expand our analysis to the SOFIA multi-model ensemble to further prove the robustness and estimate model uncertainty, which we will present in this session.

How to cite: Xu, X., Martin, T., and Beadling, R.: On the atmospheric response to idealized freshwater input around Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-894, https://doi.org/10.5194/egusphere-egu24-894, 2024.

Planktonic foraminifera tests are commonly used in geochronology and palaeoceanographic reconstructions as micropaleontological and geochemical proxies. In the high latitude North Atlantic and Arctic, the polar specialist Neogloboquadrina pachyderma is the most common planktonic foraminifera and is known for its morphological plasticity, resulting in the identification of at least 5 morphotypes within a single genotype. The significance of its morphological variability remains uncertain, with hypotheses linking it to ecological/environmental differences, and/or life history stages. However, N. pachyderma morphotype analysis has been largely limited to sediment studies, lacking a systematic exploration of water column populations. Here, we explore this question using a novel supervised machine learning (SML) and automated image processing (AutoMorph software) approach to acquire large morphometric data sets on populations of Central Arctic N. pachyderma from 8 paired plankton net and sediment (box-core) sample sets. This study addresses the ability of SML to discern the established morphotypes and whether alternative morphological models can better represent the morphological diversity. Additionally, this study explores how morphologic variability in living N. pachyderma populations compare with their sedimented counterpart.

The results, based on approximately 15.000 N. pachyderma morphotypes, represents the largest data set for a single planktonic foraminifer species and the largest study of this kind based on water column populations in the Arctic Ocean. The highest specimen abundance was found in the upper 100m. Preliminary findings indicate a dominance of small (55-120µm) N. pachyderma specimens, assumed to be juveniles, whereas the sediment assemblage is dominated by heavily encrusted, larger morphotypes. The water column and sediment assemblages are mismatched, potentially due to the much narrower time window recorded in the water column compared to the annual-millennial timescale in the sediments. This study provides new insights into how ecology and life history of N. pachyderma translates to test morphology – a crucial aspect for taxonomy and geological studies.

How to cite: Weitkamp, T., Hsiang, A., Bird, C., Vermassen, F., Darling, K., and Coxall, H.: Identifying modern Neogloboquadrina pachyderma morphotypes from the Central Arctic Ocean through supervised machine learning – a comparison between water column and seafloor sediment populations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-993, https://doi.org/10.5194/egusphere-egu24-993, 2024.

EGU24-1246 | Posters on site | CL1.2.9 | Highlight

The time of emergence of Arctic warming, wettening and sea ice melting 

Richard Bintanja, Nicoleta Tsakali, Nomikos Skyllas, and Marlen Kolbe

The strongly warming and wettening Arctic exhibits considerable temporal interannual and decadal variability. A conclusive transition point to a new climate state – the time of emergence (ToE) – occurs when the forced signal exceeds natural variability. Uncertainties in model-simulated climate trends and variability, as well as in methods, have thus far resulted in diverging estimates of Arctic ToE. Here we use a detailed, robust method applied to state-of-the-art climate model projections to show that in most seasons Arctic sea ice thickness emerges first (2038-2043), followed by surface air temperature (2037-2053) and sea ice cover (2050-2074). Since precipitation/rainfall variability is comparatively high, these variables emerge relatively late (after 2080). Autumn generally exhibits the earliest ToE-values due to strong sea ice retreat and associated warming and surface evaporation. Spatial variations in Arctic trends and variability cause ToE for temperature and sea ice thickness to emerge first in the Central Arctic, whereas for sea ice cover and rainfall this primarily occurs in the North Atlantic – Barents Sea region. Evidently, parts of the Arctic are close to entering a new climate state in terms of temperature and sea ice changes, with wide-ranging, long-term and possibly irreversible consequences for vulnerable Arctic ecosystems and human activities.

How to cite: Bintanja, R., Tsakali, N., Skyllas, N., and Kolbe, M.: The time of emergence of Arctic warming, wettening and sea ice melting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1246, https://doi.org/10.5194/egusphere-egu24-1246, 2024.

EGU24-2134 | Orals | CL1.2.9 | Highlight

Anomalous Arctic Warming Linked with Severe Winter Weather in Northern Hemisphere Continents 

Judah Cohen, Jennifer Francis, and Karl Pfeiffer

We have extended a recently developed index of accumulated winter season severity index (AWSSI), originally based on temperature and snowfall observations from weather stations in the United States only, to the entire Northern Hemisphere using reanalysis output. The expanded index (rAWSSI) is analyzed to reveal relationships between Arctic air temperatures/geopotential heights and the probability of severe winter weather across the midlatitudes. Cold temperatures dominate the index, while snowfall contributes mainly over high elevations.  We find a direct and linear relationship between anomalously high Arctic temperatures/geopotential heights and increased severe winter weather, especially in northern and eastern continental regions.  Positive temperature trends in specific Arctic regions are associated with increasing trends in severe winter weather in particular midlatitude areas. These trends are more robust during recent decades when Arctic warming has accelerated, exceeding the pace of global-average warming by a factor of two to four. We also explore trends in the variability of daily rAWSSI. During the era of rapid Arctic warming, variability has decreased over the Arctic Ocean and Europe – suggesting less volatile winter weather -- while it has increased along the United States (US)/Canadian border, western Canada, and northeast Asia, indicating more pronounced shifts in weather conditions. This finding suggests an increased tendency for volatile weather swings known as weather whiplash.  Finally, we find that when the stratospheric polar vortex is weak (anomalously warm stratosphere), the rAWSSI tends to increase, suggesting an association between disruptions in the polar vortex and severe winter weather across certain regions of the Northern Hemisphere continents.

How to cite: Cohen, J., Francis, J., and Pfeiffer, K.: Anomalous Arctic Warming Linked with Severe Winter Weather in Northern Hemisphere Continents, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2134, https://doi.org/10.5194/egusphere-egu24-2134, 2024.

EGU24-3767 | ECS | Posters on site | CL1.2.9

Different AMOC Stabilization between Past Interglacials and Future 

Wei Liu, Feng Shi, Xiao Zhang, and Qiuzhen Yin

The excess freshwater in the Arctic due to global warming is causing a weakening the Atlantic Meridional Overturning Circulation (AMOC). The question of how the climate change will impact the stability of the AMOC, however, remains unclear. We address this uncertainty through a series of ensemble simulations (100 members) using freshwater hysteresis experiments, aiming to elucidate potential changes in AMOC stability across different interglacials. Our findings suggest that future increases in anthropogenic CO2 emissions will bolster the AMOC's resistance to excess freshwater, though it exhibits less resilience compared to past interglacials. In future climate scenarios, warmer conditions lead to a notable delay in sea ice expansion, which aids in the preservation of deep water formation and AMOC strength. Concurrently, an intensification of freshwater convergence in the North Atlantic acts as a dampening factor during AMOC recovery under warmer climate background. The influence of orbital parameters on AMOC stability across different interglacials is found to be relatively minor. These results underscore the importance of considering background climate conditions, particularly CO2 concentrations, when investigating future AMOC changes and making comparisons to past AMOC dynamics.

How to cite: Liu, W., Shi, F., Zhang, X., and Yin, Q.: Different AMOC Stabilization between Past Interglacials and Future, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3767, https://doi.org/10.5194/egusphere-egu24-3767, 2024.

EGU24-4326 | ECS | Posters on site | CL1.2.9

Chronostratigraphy of glaciomarine sediments off the West Greenland Shelf: a key to the understanding of the Quaternary evolution of the Greenland ice sheet 

Yang Zhang, Johan Faust, Nikolas Römer-Stange, Tilo von Dobeneck, and Michal Kucera

Six gravity cores (GC) and four sea-floor drill rig (MeBo) cores from water depths of ~1800–1400 m have been successfully collected off the outer Disko Bay fan in eastern Central Baffin Bay during the research expedition MSM111 in 2022. These sediment cores provide an up to 125 m long (MeBo 14, 20 and 23) record potentially reflecting the late- and mid-Pleistocene dynamics of the Western Greenland ice sheet. Besides the presence of a few turbiditic sequences a continuous sedimentation is well supported by the parasound seismostratigraphy as well as by lithostratigraphic log correlation based on X-ray Fluorescence (XRF) and magnetic susceptibility (MS). Establishing a chronostratigraphy of the Baffin Bay glaciomarine sediments is, however, challenging as e.g., carbonate dissolution impedes reliable foraminiferal δ18O stratigraphy.

Here, we present our preliminary chronostratigraphic framework established by combining three stratigraphic tools: radiocarbon ages, relative paleointensity (RPI), and characteristic basin-wide detrital carbonate layers (BBDCs). BBDCs represent periods of elevated terrigenous deposition in response to increased meltwater discharge that can be well identified by XRF Ca/Ti. The GC 12&22 and MeBo 14&20 cores contain rhythmic alterations between sandy-rich detrital carbonate layers and clayish layers, which are clearly represented by Ca/Ti and MS data. Intriguingly, these cyclic alterations also display significant correlation with marine isotope stages (MIS), where higher Ca/Ti and MS values correspond to warmer periods. We thus estimated that our 125-m composite core lasts until MIS 16 or ~700 ka. This long duration is also partly supported by our RPI data from MeBo 20&23. Nevertheless, two major difficulties were encountered: (1) RPI data of GC 24&21 do not reveal an unambiguous match with global RPI reference stacks and/or regionally established RPI records, probably due to condensed sedimentation of these two deeper gravity cores; and (2) recurring BBDCs of the studied cores can be interpreted as high-frequency events reflecting the intrinsic dynamics of the North American Arctic-ice sheet complex, or, alternatively as glacial-interglacial cycles. In order to solve the current chronostratigraphy controversy between a Late Pleistocene age or of deeper mid-Pleistocene age, further carbon-14 ages from the condensed GC24 and collect RPI data from the more expanded MeBo 14 will be obtained.

How to cite: Zhang, Y., Faust, J., Römer-Stange, N., von Dobeneck, T., and Kucera, M.: Chronostratigraphy of glaciomarine sediments off the West Greenland Shelf: a key to the understanding of the Quaternary evolution of the Greenland ice sheet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4326, https://doi.org/10.5194/egusphere-egu24-4326, 2024.

The western Fram Strait, a critical gateway connecting the Arctic and Atlantic Oceans, is presently characterized by the dominance of cold, sea-ice-laden waters from the Arctic Ocean. Nevertheless, the dynamics of the Return Atlantic Current, facilitating direct east-west recirculation across the Fram Strait, contributes significantly to the southward flow along the East Greenland shelfbreak. This study delves into the influence of Atlantic Water (AW) in the western Fram Strait over the past ~35 thousand years, employing a comprehensive analysis of marine sediment cores, including two newly acquired records.

Our investigation utilizes planktic foraminiferal assemblages, stable isotopes, and X-ray fluorescence (XRF) data to unravel the historical patterns of AW advection. During late Marine Isotope Stage 3 and the Last Glacial Maximum, the findings reveal a noteworthy influx of AW, likely occurring beneath a substantial layer of surface Polar Water. The spatial extent of AW varied, reflecting the dynamic interplay with the Greenland Ice Sheet's expansion.

Throughout the deglaciation phase, the western Fram Strait experienced disruptions in AW inflow due to the influence of meltwater, further shaping the regional dynamics. The interplay between AW and environmental factors, such as the evolving Greenland Ice Sheet, emerges as a key driver influencing the spatial distribution of AW during this critical climatic transition.

Challenges arise in reconstructing the Holocene history of the western Fram Strait, marked by carbonate dissolution and low sedimentation rates. However, our data point towards persistent and robust AW advection to the region, extending at least since the onset of the present interglacial period. Despite limitations in the Holocene reconstruction, the cumulative evidence underscores the enduring influence of AW on the western Fram Strait, revealing a complex interplay of climatic and glacial dynamics.

This research sheds light on the intricate relationship between AW dynamics and regional environmental changes, offering valuable insights into the past variability of the western Fram Strait. The findings contribute to a deeper understanding of the factors driving oceanic circulation patterns in this pivotal gateway, with implications for comprehending broader climate dynamics and projecting future changes in the Arctic-Atlantic interface.

How to cite: Telesiński, M. and Zajączkowski, M.: Reconstructing Late Glacial Atlantic Water Advection in the Western Fram Strait: Insights from Marine Sediment Cores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5410, https://doi.org/10.5194/egusphere-egu24-5410, 2024.

EGU24-5768 | ECS | Posters on site | CL1.2.9 | Highlight

10Be/9Be in Arctic Ocean Sediments: Another clue towards a fresh Arctic hypothesis 

Agathe Ollive, Florian Adolphi, Walter Geibert, Jens Matthiessen, Johannes Lachner, and Konstanze Stübner

Marine sediments provide invaluable records of past climate variations. However, dating these sediments with classical dating methods is challenging in the Arctic Ocean because of the lack of foraminifera, their poor preservation, and the extremely low sedimentation rates. Yet, understanding the history of the Arctic Ocean is of great importance for assessing its potential response to the current fast warming of these high latitudes.

Recently, Geibert et al. (2021) proposed that during some glacial periods, the Arctic Ocean might have been filled with freshwater. This hypothesis, which has potentially far-reaching implications, can explain intervals of low 230Th-excess and low 10Be concentration in Arctic sediments but is strongly debated (Spielhagen et al., 2022; Hillaire-Marcel et al., 2022). This hypothesis posits that during these freshwater intervals, primary input fluxes originated from Arctic rivers rather than the North Atlantic.

To test this theory, we assess the 10Be/9Be ratio in sediments that correspond to the freshwater intervals. Since the 10Be/9Be ratio differs systematically between North Atlantic and riverine waters, this proxy used as a water mass tracer can give novel insights into the Quaternary history of the Arctic Ocean. We discuss our results in the light of the hypothesis by Geibert et al. and evaluate the use of 10Be/9Be as a dating and correlation tool of Arctic Ocean sediments contributing to the ongoing chronostratigraphic investigations in the Arctic Ocean.

 

Geibert, Walter, et al. "Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf." Nature 590.7844 (2021): 97-102.

Spielhagen, Robert F., et al. "No freshwater-filled glacial Arctic Ocean." Nature 602.7895 (2022): E1-E3.

HillaireMarcel, Claude, et al. "Challenging the hypothesis of an Arctic Ocean lake during recent glacial episodes." Journal of Quaternary Science 37.4 (2022): 559-567.

How to cite: Ollive, A., Adolphi, F., Geibert, W., Matthiessen, J., Lachner, J., and Stübner, K.: 10Be/9Be in Arctic Ocean Sediments: Another clue towards a fresh Arctic hypothesis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5768, https://doi.org/10.5194/egusphere-egu24-5768, 2024.

EGU24-6048 | ECS | Orals | CL1.2.9

Antarctic extreme high temperatures across seasons and their response to advection 

Min Xu, Felix Pithan, and Qinghua Yang

Antarctic extreme high temperatures impact the cryosphere, with very warm extremes driving surface melt on ice shelves. Here, we analyse temperatures exceeding the 90th percentile of the temperature distribution, focusing on the associated circulation patterns and radiation anomalies. ERA5 reanalysis data show high air pressure / positive geopotential height anomalies related to the occurrence of warm extremes. The highest temperature during warm extremes appears on the periphery of high-pressure systems, consistent with anticyclonic advection. Autumn and winter exhibit stronger warm extremes due to the transport of warm and moist air. In summer, the weak meridional gradients of TOA downward solar radiation flux and surface air temperature contribute to weak temperature anomalies by advection of anomalously warm air. Warm extremes are associated with positive longwave radiation anomalies in all seasons, but with negative shortwave radiation anomalies at the surface except during polar night. These relationships are verified by station observations. Our results confirm that Antarctic warm extremes are mostly driven by meridional advection of warm air, and suggest that these warm air masses are predominantly moist and cloudy.

How to cite: Xu, M., Pithan, F., and Yang, Q.: Antarctic extreme high temperatures across seasons and their response to advection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6048, https://doi.org/10.5194/egusphere-egu24-6048, 2024.

EGU24-6507 | ECS | Orals | CL1.2.9 | Highlight

Response of winter climate and extreme weather to projected Arctic sea-ice loss in very large-ensemble climate model simulations  

Kunhui Ye, Tim Woollings, Sarah Sparrow, Peter Watson, and James Screen

Arctic sea-ice loss and amplified Arctic warming have been one striking signature of climate change, which have important impacts on climate variability in the Arctic and mid-low latitudes. Climate modeling including the Polar Amplification Model Intercomparison Project (PAMIP) has been a powerful tool for investigating the effects of Arctic sea-ice loss in a changing climate. However, existing climate model simulations including individual climate models from the multi-model/ensemble PAMIP project have relatively small ensemble sizes that may not allow a robust separation of forced response, particularly the response of extremes, to Arctic sea-ice loss from internal variability. Therefore, our confidence in the response to projected Arctic sea-ice loss in climate change is reduced. This has led to two unanswered important questions: (1) what ensemble sizes are needed for robust detection of extremes, as well as seasonal-mean responses to projected Arctic sea-ice loss? and (2) is the response dependent on resolution?

To address the challenge, we have performed very large (~2000 members) initial-condition ensemble climate simulations, using both low (~90 km) and high (~60 km) resolutions, with prescribed boundary conditions (i.e., sea surface temperature and sea-ice concentration) taken from the PAMIP project, to advance understanding of mean climate and extreme weather responses to projected Arctic sea-ice loss under 2°C global warming above preindustrial levels. We have run these simulations with the Met Office Hadley Centre global atmospheric model Version 4 on the University of Oxford’s innovative distributed computing project (Climateprediction.net). These simulations better sample internal atmospheric variability and extremes for each model compared to those from the PAMIP, and also allow studying the resolution-dependence of the response to projected Arctic sea-ice using a larger ensemble. Analysis of these simulations suggests that the mean climate response is mostly consistent with that from the PAMIP multi-model ensemble, including tropospheric warming, reduced midlatitude westerlies and storm track activity, an equatorward shift of the eddy-driven jet and increased mid-to-high latitude blocking. The response of temperature and precipitation extremes largely follows the seasonal-mean response. However, East Asia is a notable exception in showing an increase in severe cold temperature extremes in response to the projected Arctic sea-ice loss. Two resolutions of the same model exhibit significant differences in the stratospheric circulation. This does suggest resolution-dependence of the response but we consider that the difference in the stratospheric response weakly modulates the tropospheric response.

We highlight that our very large-ensemble simulations have allowed rigorous sub-sampling to address the challenge of obtaining a robust forced response to projected Arctic sea-ice loss. The sub-sampling confirms that large ensembles (e.g. >=400) are needed to robustly estimate the seasonal-mean large-scale circulation response, and very large ensembles (e.g., >=1000) for regional climate and extremes. The reduction in uncertainty of the response with ensemble size is very well predicted by standard error analysis, guiding the design of future large ensembles. 

How to cite: Ye, K., Woollings, T., Sparrow, S., Watson, P., and Screen, J.: Response of winter climate and extreme weather to projected Arctic sea-ice loss in very large-ensemble climate model simulations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6507, https://doi.org/10.5194/egusphere-egu24-6507, 2024.

EGU24-6632 | ECS | Orals | CL1.2.9

Antarctic Bottom Water on Global Ocean General Circulation Model and Reanalysis outputs 

Daniel M. C. Santos and Olga T. Sato

The Antarctic Bottom Water (AABW) is the deepest, densest, and coldest water in the global ocean. Its distinctive properties and formation primarily result from the mixing between the colder and denser Antarctic Shelf Water and the lighter, warmer, and saltier Circumpolar Deep Water along the Antarctic slope. Past investigations have already demonstrated shifts in AABW characteristics over recent decades, with assessments of temperature, salinity, dissolved oxygen, and layer thickness trends conducted in various regions. These studies heavily relied on in situ data for AABW evaluation. However, measuring abyssal depths is a challenging task. Until now, the predominant data sources have been moorings and decadal hydrographic sections, yet the inherent limitations of in situ data from abyssal layers arise due to low sampling rates and restricted geographical coverage.

To address these temporal and spatial gaps, utilizing model and reanalysis outputs emerges as a logical solution. This study aims to investigate trends in AABW properties in high and mid latitudes at different basins worldwide using such outputs. In the initial phase of assessing AABW's properties variability, we evaluate the capability of two reanalyses and a model in accurately representing AABW, they are: 1. Estimating the Circulation and Climate of the Ocean (ECCO); 2. Copernicus Global Oceanic and Sea Ice GLORYS; 3. JAMSTEC OFES Ocean General Circulation Model for the Earth Simulator (OFES). To validate these outputs, we employ climatology from WOA18 and in situ data from the SAMBAR project.

The results indicate that ECCO has a problem with bathymetric representation, with larger values of AABW thickness (h) found in regions with greater depths, particularly in the southern portion of the Argentine Basin, in comparison to the reference WOA18. GLORYS, on the other hand, appears to misrepresent h by consistently underestimating it across all studied domains, from high to mid latitudes. On the contrary, OFES tends to overestimate h in the high latitudes but underestimate it in the mid latitudes.



How to cite: M. C. Santos, D. and T. Sato, O.: Antarctic Bottom Water on Global Ocean General Circulation Model and Reanalysis outputs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6632, https://doi.org/10.5194/egusphere-egu24-6632, 2024.

EGU24-7166 | ECS | Posters on site | CL1.2.9

An Open-Access Repository of Holocene Marine Limit and Relative Sea Level Data for all of Greenland 

Gregor Luetzenburg, Svend V. Funder, Sarah Woodroffe, and Kristian K. Kjeldsen

The Last Glacial Maximum (LGM) represents a critical period in Earth's history, and understanding the dynamics of the Greenland Ice Sheet (GrIS) during this time is pivotal for predicting its response to present and future climate change. Accurate reconstructions of the LGM ice sheet margin rely on marine limit and relative sea level data, which provide valuable insights into past ice sheet behavior. However, current databases of Greenland marine limits and relative sea levels are incomplete or not readily accessible, hindering scientific progress and impeding collaboration among researchers.

Here, we develop an online, open-access database hosted by the Geological Survey of Denmark and Greenland (GEUS) that consolidates all available information on the deglacial marine limit and relative sea level data from Greenland. The data is recorded in the HOLSEA format and includes realistic reporting of errors. The collected data comprises over 3,000 distinct data points, sourced from more than 120 publications and literature entries. These field observations span over 140 years, reflecting the evolution of measurement techniques and a growing comprehension of marine deposit and relative sea level features. By mining all existing databases, original publications, and unpublished data, this new database will provide researchers with a centralized and up-to-date resource for investigating the LGM ice sheet and subsequent deglaciation history.

In the future, the database will undergo regular updates to incorporate new findings and adhere to international standards for reporting marine limit and relative sea level data. This initiative forms the baseline for validating reconstructions of the past behavior of the GrIS contributing to more accurate predictions of its future response to changing climatic conditions.

How to cite: Luetzenburg, G., Funder, S. V., Woodroffe, S., and Kjeldsen, K. K.: An Open-Access Repository of Holocene Marine Limit and Relative Sea Level Data for all of Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7166, https://doi.org/10.5194/egusphere-egu24-7166, 2024.

EGU24-8688 | Posters on site | CL1.2.9

Arctic Ocean freshwater export events and possible linkages with AMOC weakenings in the last 200 ka 

Robert F. Spielhagen, Marc Zehnich, Henning A. Bauch, and Henning Kuhnert

Deep-sea sediment cores from the Arctic Ocean are excellent archives suitable for the reconstruction of deglacial events on circum-Arctic continents and the associated enhanced export of freshwater to the North Atlantic. Here we present new records from a long large-volume sediment core obtained on the NE Greenland continental margin at 81.2°N where the shelf is particularly narrow. The site is perfectly located to monitor the export of freshwater and ice from the Arctic Ocean to the Greenland Sea using data on ice-rafted debris (IRD) and the stable isotope composition of planktic and benthic foraminifers in the sediments. The records from our new core hold evidence of a number of strong freshwater export events in the last 200 ka. Several events correlate in time with extreme discharges from large lakes which had developed south of the ice sheets on northern Eurasian shelves in MIS 6, 5b and 4. Using published data from the Greenland Sea and the North Atlantic, we can show that freshening events in the Arctic and the Nordic Seas correlate with weakenings of the Atlantic meridional overturning circulation (AMOC). We propose that enhanced Arctic Ocean freshwater export triggered (or contributed to) decreased deepwater renewal in the Greenland Sea and had severe consequences for the strength of the global ocean circulation.

In addition to the Arctic Ocean freshwater events our new records reveal a number of probably minor events of iceberg melting and intermediate water freshening which we associate with the history of continental ice on North Greenland and in particular in the Wandel Sea. We propose that the repeated ice expansion and retreat in this area released dense plumes of fine-grained sediment and low d18O-water which spread along the continental slope. This may have happened in MIS 6, 5d, and 4. For the last 50 ka, our records suggest an ice retreat on North Greenland at 50-40 ka and a stepwise readvance of the ice front at 35-25 ka.

How to cite: Spielhagen, R. F., Zehnich, M., Bauch, H. A., and Kuhnert, H.: Arctic Ocean freshwater export events and possible linkages with AMOC weakenings in the last 200 ka, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8688, https://doi.org/10.5194/egusphere-egu24-8688, 2024.

EGU24-10074 | ECS | Posters on site | CL1.2.9

Atmospheric circulation sensitivity to changes in Arctic soil thermodynamics and hydrology 

Alex Martínez-Vila, J. Fidel Gonzalez-Rouco, Nagore Meabe-Yanguas, Felix García-Pereira, Johann Jungclaus, Stephan Lorenz, and Philipp de Vrese

Changes in modes of atmospheric circulation contribute to shape climate at regional scale by interacting with orography. Earth System Models (ESM) tackle the response of these modes to global warming. However, there exists considerable uncertainty regarding the magnitude and impact of the changes in modes of variability. This uncertainty is mainly due to internal variability, and inter-model variability related to the different resolution and parametrisation of physical processes in ESMs. One example of the latter is the representation of soil thermodynamics and hydrology in the Arctic. Different representations of Arctic dynamics have the potential to affect the circulation, not only locally in the Arctic, but also at mid-latitudes and the tropics via a series of teleconnections. The physical processes linking Arctic warming and sea-ice loss to lower latitude climate variability are still not well understood. This study addresses how changes in Arctic soil thermodynamics and hydrology affect the global atmospheric circulation. To do so, a modified version of the Max Plank Institute Earth System Model (MPI-ESM) was used to produce an ensemble of simulations with different set-ups of its Land Surface Model (JSBACH). These configurations consider different representation of the Arctic thermo-hydrodynamics leading to comparatively drier or wetter states. Preliminary analysis show sensitivity of atmospheric circulation to changes in the Arctic Amplification. Results are shown for a comparison of the response of extratropical (Arctic and Antarctic oscillations) and intertropical (monsoons and ENSO) modes across the ensemble of simulations.

How to cite: Martínez-Vila, A., Gonzalez-Rouco, J. F., Meabe-Yanguas, N., García-Pereira, F., Jungclaus, J., Lorenz, S., and de Vrese, P.: Atmospheric circulation sensitivity to changes in Arctic soil thermodynamics and hydrology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10074, https://doi.org/10.5194/egusphere-egu24-10074, 2024.

EGU24-10111 | ECS | Posters on site | CL1.2.9

Surface air temperature sensitibily to changes in land surface model thermodynamics and hydrology 

Nagore Meabe-Yanguas, Jesus Fidel González-Rouco, Félix García-Pereira, Norman Steinert, Phillip de Vrese, Johann Jungclaus, and Stephan Lorenz

The Arctic region is particularly sensitive to global warming due to snow and sea ice dynamics, as well as to the strong positive feedback mechanisms that amplify Arctic warming response to forcing, such as ice-snow-albedo feedback or lapse-rate feedback. The presence of permafrost makes the Arctic also relevant for global climate, since Arctic soils contain large quantities of carbon with radiative feedback implications. Improved representation of the physical processes in frozen soils  and considering different model variants allows for assesing uncertainties in permafrost related processes. In this study several experiments with different set-ups of the Arctic thermo-hydrodynamics will be analyzed in order to understand how different parametrizations in permafrost areas affect Earth’s climate and in particular the surface temperature in the Arctic. Those set-ups also account for different vertical discretizations of the land model. The different model configurations lead to relatively different climate background states in the Arctic, with the different vertical discretization set-ups playing a minor role. A positive sea-ice-snow-albedo feedback is shown to enhance the warming signal under a climate change scenario. The magnitude of the feedback depends on the background state and available snow and sea-ice. By assessing the Arctic amplification ratio (AA) we conclude that all configurations show considerable (internal) AA variabillity in the 20th and the first quarter of the 21st century, but end up converging to a factor of 2-3 times larger warming in the Arctic regions than globally by the end of the century. This suggests that high AA values recently found in observations are related to internal variability.

How to cite: Meabe-Yanguas, N., González-Rouco, J. F., García-Pereira, F., Steinert, N., de Vrese, P., Jungclaus, J., and Lorenz, S.: Surface air temperature sensitibily to changes in land surface model thermodynamics and hydrology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10111, https://doi.org/10.5194/egusphere-egu24-10111, 2024.

EGU24-12098 | ECS | Posters on site | CL1.2.9

The role of atmospheric circulation in extreme cold weather events over the Northern Hemisphere 

Morteza Babaei, Rune Grand Graversen, and Johannes Patrick Stoll

One significant and dangerous consequence of climate change is the growth in both the intensity and frequency of extreme weather events. The objective of this study is to examine the prevalent hypothesis that links Arctic amplification (AA) to the occurrence of cold weather extremes over the Northern Hemisphere (NH) in December–January–February (DJF). According to this hypothesis, AA alters the mid-latitude circulation, causing Rossby waves to become slower and wavier. More slow or wavy Rossby waves result in more persistent weather patterns in the mid-latitudes, potentially increasing the frequency and severity of extreme weather events.

We examine the link between AA and cold spells in the Northern Hemisphere by using idealized simulations with the Community Earth System Model (CESM) and the fifth-generation ECMWF reanalysis data (ERA5). We mimicked AA by adding a constant amount of downwelling longwave radiation (DLR) over the Arctic in the CESM slab-ocean model. Furthermore, we categorized ERA5 data into two separate periods: pre-Arctic amplification (1979–1999, Pre-AA) and post-Arctic amplification (2002–2022, Post-AA).

We computed the speed of planetary waves based on geopotential height using two different methodologies. In the first method, the speed of planetary wave zonal propagation was estimated through the utilization of a top-ridge and bottom-trough tracking algorithm. In the second method, we calculated the zonal propagation speed of planetary waves at each grid point following Takaya and Nakamura (2001). Both methods, although being fundamentally different, showed a significant reduction in DJF average zonal planetary wave speed over Northen-midlatitude during AA in both reanalysis data and idealized simulations.

The midlatitude extreme index (MEX) is used to identify cold weather extremes. On average, MEX showed a higher value for Pre-AA than Post-AA, consistent with a warmer climate in post-AA. However, the average wave speed during cold extremes is lower in Post-AA than Pre-AA.

As regard wave amplitude, based on the difference between the maximum peak and the minimum bottom of the waves in both the ERA5 data and the idealized simulations, we cannot confirm a change in the amplitude of planetary waves due to AA.

To summarize, Arctic amplification leads to a decrease in the speed of Rossby waves but little or no change in their amplitude. In addition, cold extremes are influenced by the deceleration of Rossby waves in response to warming conditions in the Arctic.

How to cite: Babaei, M., Graversen, R. G., and Stoll, J. P.: The role of atmospheric circulation in extreme cold weather events over the Northern Hemisphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12098, https://doi.org/10.5194/egusphere-egu24-12098, 2024.

EGU24-12738 | Posters on site | CL1.2.9

Evaluating the PolarRES regional models using tailor-made climate indices for Arctic reindeer herding communities 

Heidrun Matthes, Jussi T Eronen, Xavier Fettweis, Bruce C Forbes, Ella Gilbert, Joachim Otto Habeck, Tim Horstkotte, Kirill Istomin, Teresa Komu, Oskar Landgren, Jan Landwehrs, Roza Laptander, Priscilla Mooney, Ruth Mottram, Christiaan van Dalum, Willem Jan van den Berg, Sirpa Rasmus, Annette Rinke, and Hans Tømmervik

From a combination of the operational system of reindeer herding and meteorological seasonality, we developed a range of climate indices reflecting critical events in the reindeer herding year that influence the success of this livelihood. These critical events can be described as combinations of specific meteorological conditions, and therefor rendered as equations we can compute from climate model output, creating a capability for analysing different projections of the future and delivering relevant information on climate change to reindeer herding communities.

For this purpose, we can use a wealth of different global and regional climate projections, with distinct advantages and disadvantages (e.g. model resolution, different greenhouse gas futures, high number of models in the ensemble for uncertainty estimates, process representation, availability of variables). For example, the CMIP6 ensemble enables the analysis of a broad range of greenhouse gas futures from a wide variety of models, allowing us to assess scenario uncertainty, but it is limited by its coarse spatial resolution. On the other hand, the PolarRES ensemble has a higher spatial resolution but is only available for one RCP/greenhouse gas future. The PolarRES ensemble consists of regional climate simulations generated by multiple regional climate models that dynamically downscale CMIP6 global climate simulations selected using a novel storyline approach. Both ensembles provide hindcast simulations that allow us to evaluate the ensemble performance with regard to the climate indices we defined.

This study uses these simulations to evaluate and compare model performance to understand the potential and limitations of future projections of specific climate indices relevant for reindeer herding. We use in-situ based observations from the data set Global Summary of the Day to evaluate onset and end of the continuous freezing period, hot summer days, thawing days in autumn and freeze-thaw cycles in both spring and autumn.

How to cite: Matthes, H., Eronen, J. T., Fettweis, X., Forbes, B. C., Gilbert, E., Habeck, J. O., Horstkotte, T., Istomin, K., Komu, T., Landgren, O., Landwehrs, J., Laptander, R., Mooney, P., Mottram, R., van Dalum, C., van den Berg, W. J., Rasmus, S., Rinke, A., and Tømmervik, H.: Evaluating the PolarRES regional models using tailor-made climate indices for Arctic reindeer herding communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12738, https://doi.org/10.5194/egusphere-egu24-12738, 2024.

EGU24-13775 | Orals | CL1.2.9 | Highlight

Impacts of projected Arctic sea ice loss on daily weather patterns over North America 

Melissa Gervais, Lantao Sun, and Clara Deser

Future Arctic sea ice loss has a known impact on Arctic Amplification (AA) and mean atmospheric circulation. Furthermore, several studies have shown it leads to a decreased variance in temperature over North America. In this study, we analyze results from two fully-coupled Community Earth System Model (CESM) Whole Atmosphere Community Climate Model (WACCM4) simulations with sea ice nudged to either the ensemble mean of WACCM historical runs averaged over the 1980-1999 period for the control (CTL) or projected RCP8.5 values over the 2080-2099 period for the experiment (EXP). Dominant large-scale meteorological patterns (LSMPs) are then identified using self-organizing maps applied to winter daily 500 hPa geopotential height anomalies (𝑍′500) over North America. We investigate how sea ice loss (EXP-CTL) impacts the frequency of these LSMPs and, through composite analysis, the sensible weather associated with them. We find differences in LSMP frequency but no change in residency time indicating there is no stagnation of the flow with sea ice loss. Sea ice loss also acts to de-amplify and/or shift the 𝑍′500 that characterize these LSMPs and their associated anomalies in potential temperature  at 850hPa. Impacts on precipitation anomalies are more localized and consistent with changes in anomalous sea level pressure. With this LSMP framework we provide new mechanistic insights,  demonstrating a role for thermodynamic, dynamic and diabatic processes in sea ice impacts on atmospheric variability. Understanding these processes from a synoptic perspective is critical as some LSMPs play an outsized role in producing the mean response to Arctic sea ice loss.

How to cite: Gervais, M., Sun, L., and Deser, C.: Impacts of projected Arctic sea ice loss on daily weather patterns over North America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13775, https://doi.org/10.5194/egusphere-egu24-13775, 2024.

EGU24-13956 | Posters on site | CL1.2.9

Depositional and paleoenvironmental changes in Arctic Svalbard fjords during the last deglaciation: Insights from Grain Size End-Member Modeling 

Seung-Il Nam, youngkyu Ahn, Young Jin Joe, Kwangchul Jang, Dahae Kim, Jung-Hyun Kim, Yeong Ju Son, Matthias Forwick, Jochen Knies, and Sungmin Hong

Grain size end-member (EM) modeling is a statistical method employed to identify and quantify dominant grain size distributions in marine sediments, contributing to a comprehensive understanding of sediment transport and deposition mechanisms. Despite its utility in various marine sediments, the application of this modeling approach to glacimarine fjord sediments in polar regions remains relatively unexplored.

This study investigates the grain size distributions of glacimarine sediment cores collected from the Wijdefjorden and off Kongsfjorden in the Arctic Svalbard archipelago. By integrating grain-size EMs with lithologic and acoustic facies, we delineate distinct EM groups associated with specific depositional processes and environments. This study shows that Svalbard fjord systems underwent significant depositional changes influenced by glacial retreat during the last deglaciation to the early Holocene, coinciding with enhanced Atlantic Water inflow. Conversely, the late Holocene noticed reduced Atlantic Water inflow, aligning with glacial advances, and resulted in notable changes in depositional environments. This study underscores the efficiency of EM modeling as a valuable tool for comprehending grain size distributions and reconstructing depositional processes in glacimarine sediments within the fjord complex systems of Svalbard. Consequently, this approach enhances our understanding of the interconnected dynamics involving climate change, glacier dynamics, and oceanic forcing in glaciated polar environments throughout past glacial-interglacial climate changes.

How to cite: Nam, S.-I., Ahn, Y., Joe, Y. J., Jang, K., Kim, D., Kim, J.-H., Son, Y. J., Forwick, M., Knies, J., and Hong, S.: Depositional and paleoenvironmental changes in Arctic Svalbard fjords during the last deglaciation: Insights from Grain Size End-Member Modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13956, https://doi.org/10.5194/egusphere-egu24-13956, 2024.

EGU24-14159 | ECS | Orals | CL1.2.9

Sea-ice variability on the Southeast Greenland shelf during the Late Holocene 

Xiaotong Xiao, Xia Wan, Longbin Sha, and Camilla S. Andresen

Arctic sea ice is a critical element of the climate system by regulating the global heat budget due to the albedo effect and sensitive to changes in atmospheric and oceanic circulation. The Southeast Greenland Shelf is a climatologically sensitive area where sea ice changes are not only affected by local sea ice formation but also drift ice and cold freshwater outflow from the Arctic Ocean by East Greenland Current (EGC), which makes this area challenging for paleo-sea ice reconstruction. Here, we analyze biomarker concentrations from a sediment core located on the Southeast Greenland Shelf to reconstruct the sea-ice variability to capture the neoglacial climate change. The biomarker record shows a long-term cooling trend over last 3.5 kyr, and four centurial periods were established combined with terrigenous (glaciers) and oceanic (currents) variations. We suggest a north-south heterogeneous sea-ice variability on the East Greenland shelf from 3.5-1.2 kyr BP. Moreover, a widespread sea-ice expansion within North Atlantic regions, concurrent with the glacier advances prior to Little Ice Age, is proposed to be a pre-Little Ice Age cooling from 1.2 kyr BP. This predate cooling seemly ascribed to a swing to the negative Arctic Oscillation might be triggered by a drop of solar irradiation and a strong latitudinal insolation gradient and maintained by internal progresses.

How to cite: Xiao, X., Wan, X., Sha, L., and Andresen, C. S.: Sea-ice variability on the Southeast Greenland shelf during the Late Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14159, https://doi.org/10.5194/egusphere-egu24-14159, 2024.

EGU24-14192 | ECS | Posters on site | CL1.2.9

Tracing glacial weathering and pyrite oxidation using rare earth elements in sedimentary iron oxides 

Kwangchul Jang, Germain Bayon, Olivier Pourret, Young Jin Joe, Jung-Hyun Kim, Eunji Byun, Matthias Forwick, Rafael León, and Seung-Il Nam

Sulfide weathering plays a crucial role in driving the long-term carbon cycle on Earth, and thus its historical reconstruction is essential for a better understanding of the global carbon-climate feedback. In this study, we analyzed the abundance of rare earth elements (REE) within authigenic Fe-(oxyhydr)oxide phases in glacimarine sediments retrieved from the continental shelf offshore northern Svalbard, spanning over the last 16,300 years, to evaluate their potential as a novel tracer of sulfide weathering in source areas. The shale-normalized REE concentrations mostly showed strong mid-REE enrichment patterns over the entire period, characterized by a concavity index (CI) greater than 2.5. Such a high CI value distinctly deviates from typical measurements in authigenic phases of global marine/river sediments (1.0 < CI < 2.5) and exclusively occurs in acid mine drainage, minesoil leachates, or some authigenic river sediments known to be affected by intense sulfide weathering. In this context, we argue that the pronounced mid-REE enrichments with CI > 2.5 observed in northern Svalbard have resulted from prevailing sulfide oxidation linked to glacial weathering. This finding underscores a new approach of REE signatures in the authigenic phases of marine sediments for the past reconstruction of sulfide weathering over the geological time scale.

How to cite: Jang, K., Bayon, G., Pourret, O., Joe, Y. J., Kim, J.-H., Byun, E., Forwick, M., León, R., and Nam, S.-I.: Tracing glacial weathering and pyrite oxidation using rare earth elements in sedimentary iron oxides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14192, https://doi.org/10.5194/egusphere-egu24-14192, 2024.

EGU24-14777 | ECS | Posters on site | CL1.2.9

Holocene to Eemian sea ice and terrigenous influx variations in Baffin Bay – a lipid biomarker study 

Monika Mikler, Juliane Müller, Johan C. Faust, Christoph Vogt, and Michal Kucera

Sea ice and ice sheets are highly sensitive to climate change in the Arctic, which shows an amplified response to global warming. To better understand the environmental changes and feedback processes associated with Arctic sea-ice decline and continental ice mass loss in a warmer-than-present world, it is urgent to investigate records of past warm periods.

Here, we present the first results of two sediment cores from the Baffin Bay recovered during the Expedition MSM111 in 2022. A 43-cm-long multicore on top of a 17-m-long gravity core (GeoB25212-1 and -3) was recovered from the continental slope west of Greenland (68°47.621’, 59°59.426’, water depth: 1505 m). According to a first stratigraphic interpretation, these cores contain a Holocene sediment succession and a high-resolution record of the last glacial cycle including Marine Isotope Stage 5e (MIS 5e) (Kucera et al., 2023).

Sediment samples taken from the mentioned cores are investigated for lipid biomarkers. Variations in the concentration of IP25, a well-established proxy for seasonal sea ice in the Arctic Ocean (Belt et al., 2007), point to distinct changes in the presence of sea ice in Baffin Bay. The joint analysis of IP25 and open-ocean biomarkers, such as brassicasterol and dinosterol, allows to draw more quantitative conclusions on paleo sea-ice conditions (Müller et al., 2011). Furthermore, alkenones and glycerol dialkyl glycerol tetraethers enable the reconstruction of sea-surface temperatures, while changes in terrestrial influx are deduced from biomarkers such as n-alkanes, ß-sitosterol, and campesterol. The terrigenous biomarker data will be complemented by mineralogical investigations to gain more information on the provenance of the sediments. X-ray fluorescence scanning data further provides additional information on paleoproductivity changes, biogeochemical processes, etc.

The first results of our investigations show that sea-ice conditions were highly variable. Throughout the Holocene, the presence of IP25 demonstrates that seasonal sea ice was present in Baffin Bay. However, intervals with low open-water biomarker concentrations indicate that the relatively stable climate conditions were disrupted by three cold events leading to more severe sea-ice conditions. Most interestingly, we observe elevated IP25 and sterol concentrations during the stratigraphic youngest Baffin Bay Detrital Carbonate (BBDC) event, probably BBDC 0, that was identified based on elevated calcium, dolomite, and calcite contents. By contrast, the following BBDC layer, probably BBDC 1, does not show significant changes in biomarker concentrations, leading to the conclusion that conditions during BBDC 0 were special.

Ongoing analyses focus on the last interglacial (MIS 5e) and will provide information on similarities and differences in the sea-ice conditions compared to the Holocene warming.

References

Belt et al., 2007. Organic Geochemistry 38 (1), 16-27.

Kucera et al., 2023. MARIA S. MERIAN-Berichte.

Müller et al., 2011. EPSL 306 (3-4), 137-148.

How to cite: Mikler, M., Müller, J., Faust, J. C., Vogt, C., and Kucera, M.: Holocene to Eemian sea ice and terrigenous influx variations in Baffin Bay – a lipid biomarker study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14777, https://doi.org/10.5194/egusphere-egu24-14777, 2024.

EGU24-14848 | ECS | Posters on site | CL1.2.9

Sea-ice and subsurface temperatures in the outer Labrador Sea across four Heinrich events during MIS 3 

Henrieka Detlef, Mads Mørk Jensen, Rasmus Andreasen, Marianne Glasius, Marit-Solveig Seidenkrantz, and Christof Pearce

Heinrich events are characterised by the collapse of ice-sheets surrounding the North Atlantic, with Hudson Strait suggested as the prominent source region. Cryosphere-ocean interactions during stadial periods of the last glacial interval have been proposed as a potential trigger for ice-sheet collapse. Extensive sea-ice cover in the Labrador Sea, in combination with a reduced overturning circulation in the North Atlantic, might have caused the build-up of a subsurface heat reservoir by preventing the release and downward mixing of heat in the water column. Increased subsurface heat then caused/supported the destabilisation of the Laurentide ice sheet.

We present high-resolution records of sea-ice and subsurface temperatures in the outer Labrador Sea at IODP Site U1302/03 between 30 and 60 ka. The sea-ice record suggests that an extensive sea-ice cover established in the outer Labrador Sea around 0.8-0.9 kyr prior to the arrival of ice-rafted debris associated with Heinrich events. Subsurface temperatures also increase prior to the onset of Heinrich events, although the exact timing needs to be confirmed. As such, the sea-ice and subsurface temperatures support cryosphere-ocean interactions prior to the onset of Heinrich events.

How to cite: Detlef, H., Mørk Jensen, M., Andreasen, R., Glasius, M., Seidenkrantz, M.-S., and Pearce, C.: Sea-ice and subsurface temperatures in the outer Labrador Sea across four Heinrich events during MIS 3, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14848, https://doi.org/10.5194/egusphere-egu24-14848, 2024.

EGU24-15461 | ECS | Orals | CL1.2.9

High Arctic lacustrine biomarkers suggest warmer-than-present Early Holocene and Younger Dryas summers 

Sher-Rine Kong, Willem G.M. van der Bilt, William J. D`Andrea, and Pål Tore Mørkved

The Arctic warms faster than any other region on our planet (Rantanen et al., 2021). This amplified response has global consequences as the region`s melting glaciers and ice caps are dominant drivers of sea-level change. Despite these consequences, predictions remain uncertain as on-going change exceeds the range of observations used to calibrate climate models. By providing empirical constraints on this uncertain future, paleoclimate data from warmer-than-present intervals are well-suited to close this critical knowledge gap (Fischer et al., 2018). Previous studies suggest that the Arctic last experienced warmer-than-present conditions during the Early Holocene (~11.7-8.2 ka BP). However, the exact magnitude and pace of warming remain contested as data remain scarce, often complicated by site-specific factors, and hampered by methodological limitations (Axford et al., 2021).

Here, we present a sub-centennial resolution reconstruction of deglacial to Early Holocene surface temperatures from the Svalbard archipelago – an Arctic climate change hotspot. To capture atmospheric conditions, we target a closed basin lake unaffected by glacial meltwater input. To robustly determine past temperature change, we determine alkenone unsaturation indices from phylogenetically fingerprinted Group I haptophyte algae that have extensively been calibrated against Arctic air temperature measurements (D’Andrea et al., 2016), also on Svalbard (van der Bilt et al., 2019). Terrestrial plant macrofossil-derived radiocarbon ages reveal that our reconstruction covers the past 12.7 ka BP, extending the terrestrial temperature history of Svalbard by multiple millennia. Our findings do not only confirm that the Early Holocene was marked by warmer-than-present surface temperatures, but also reveal that Younger Dryas summers were at least as mild. This discovery complements mounting evidence that this stadial was shaped by extreme winters rather than year-round cooling (Bromley et al., 2023; Schenk et al., 2018). Finally, we find evidence that freshwater forcing from melting ice sheets lowered temperatures between 11.5 and 9.5 ka BP despite high radiative forcing. Facing a future shaped by similar conditions, this finding is of relevance to help understand the emerging new Arctic.

 

Axford, Y., ... & Osterberg, E. C. (2021). Past Warmth and Its Impacts During the Holocene Thermal Maximum in Greenland. Annual Review of Earth and Planetary Sciences, 49(1), 279-307. https://doi.org/10.1146/annurev-earth-081420-063858

Bromley, G., ... & Rice, D. (2023). Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals. Journal of Geophysical Research: Earth Surface, 128(1). https://doi.org/10.1029/2022jf006951

D’Andrea, W. J., Theroux, S., ... & Huang, X. (2016). Does phylogeny control U37K-temperature sensitivity? Implications for lacustrine alkenone paleothermometry. Geochimica et Cosmochimica Acta, 175, 168-180.

Fischer, H., Meissner, K. J., . . . & Zhou, L. (2018). Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond. Nature Geoscience, 11(7), 474-485. https://doi.org/10.1038/s41561-018-0146-0

Rantanen, M., Karpechko, A., ... & Laaksonen, A. (2021). The Arctic has warmed four times faster than the globe since 1980.

Schenk, F., Väliranta, M., ... & Wohlfarth, B. (2018). Warm summers during the Younger Dryas cold reversal. Nature Communications, 9(1). https://doi.org/10.1038/s41467-018-04071-5

van der Bilt, W. G., D'Andrea, W. J., ... & Bakke, J. (2019). Early Holocene temperature oscillations exceed amplitude of observed and projected warming in Svalbard lakes. Geophysical Research Letters, 46(24), 14732-14741.

How to cite: Kong, S.-R., G.M. van der Bilt, W., J. D`Andrea, W., and Tore Mørkved, P.: High Arctic lacustrine biomarkers suggest warmer-than-present Early Holocene and Younger Dryas summers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15461, https://doi.org/10.5194/egusphere-egu24-15461, 2024.

EGU24-16391 | ECS | Posters on site | CL1.2.9 | Highlight

A Physics-informed Deep Learning Based Clustering to Investigate the Impact of Regional European Radiative Forcing on Arctic Climate and Upper Atmospheric Dynamics 

Sina Mehrdad, Dörthe Handorf, Ines Höschel, Khalil Karami, Johannes Quaas, Sudhakar Dipu, and Christoph Jacobi

Heterogeneous radiative forcing in mid-latitudes, such as those caused by aerosols, has been observed to influence the Arctic climate, although the underlying mechanisms continue to be a subject of scientific discussion. In this research, we employed Deep Learning (DL) methodologies to explore the complex response of the Arctic climate system to localized radiative forcing over Europe. We performed sensitivity experiments using the Max Planck Institute Earth System Model (MPI-ESM1.2). By applying a DL-driven clustering approach, we classified atmospheric circulation patterns within a reduced-dimensional framework, with a particular focus on Poleward Moist Static Energy Transport (PMSET) as our primary parameter of interest. Additionally, we developed a new methodology to assess the contributions of these circulation patterns to anomalies in various climatic parameters.


Our results demonstrate that anomalous negative forcing over Europe alters existing circulation patterns and their occurrence frequency without leading to the emergence of new patterns. The clusters change between the Experiment and Control runs in two main ways: variations in their frequency of occurrence and seasonal shifts between the class mean characteristics in the Experiment and Control runs. While pronounced changes in seasonal occurrence frequency can substantially contribute to the observed seasonal anomaly, even subtle alterations in the seasonal differences between class mean characteristics can profoundly affect the class's contribution to the anomaly, especially if that cluster occurs with a high frequency.


We identify changes in the circulation pattern with the high-pressure system over Scandinavia as a key driver for reduced sea ice concentration (SIC) in the Barents-Kara Sea in autumn through enhancing the PMSET. The alterations in this circulation pattern also impact the dynamics of the middle atmosphere. However, its influence is relatively minor compared to other circulation patterns that are analogous to the various phases of the North Atlantic Oscillation (NAO). 


These results shed light on the complex interactions between diverse atmospheric circulation patterns and climatic variables, revealing the underlying mechanisms responsible for the anomalies observed across different seasons. Notably, a complex interplay of different circulation patterns, particularly those mirroring the distinct phases of the NAO, plays a crucial role in dictating wave propagation and the dynamics within the stratosphere. While our study did not specifically investigate the stratospheric pathway, our findings highlight that regional negative radiative forcing over Europe can lead to changes in both Arctic climatic parameters and the dynamics of the stratosphere.

How to cite: Mehrdad, S., Handorf, D., Höschel, I., Karami, K., Quaas, J., Dipu, S., and Jacobi, C.: A Physics-informed Deep Learning Based Clustering to Investigate the Impact of Regional European Radiative Forcing on Arctic Climate and Upper Atmospheric Dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16391, https://doi.org/10.5194/egusphere-egu24-16391, 2024.

EGU24-17517 | ECS | Orals | CL1.2.9 | Highlight

Impact of the Greenland Ice Sheet on the Atmosphere and Ocean 

Malena Andernach, Marie-Luise Kapsch, and Uwe Mikolajewicz

The accelerating mass loss of the Greenland Ice Sheet (GrIS) and its potential disappearance under high-emission scenarios, make the understanding of associated implications of a melted GrIS for the global climate paramount. Here, we present a comprehensive analysis of the effects of a disintegrated GrIS on the atmosphere and ocean. For this, a set of steady-state simulations with altered topography resembling an ice-free state was performed with the Max Planck Institute for Meteorology Earth System Model (MPI-ESM). The model consists of components for the atmosphere, ocean and land, and includes dynamic vegetation. Additional sensitivity experiments, allow for the first time to disentangle the individual contributions of changes in the GrIS surface elevation and properties (e.g., albedo, vegetation cover) to the simulated climate response. 

In a scenario with disintegrated GrIS, the atmospheric circulation is different. Reduced blocking and warmer air temperatures over Greenland induce differences in near-surface winds in the Arctic. In the ocean, the transport of sea ice and water masses changes in absence of the GrIS. Sea-ice export increases through the Norway-Svalbard section, the Nares Strait and the Canadian Archipelago, while it decreases through the Fram Strait. Further, water-mass export through the Fram Strait and import through the Norway-Svalbard section weakens, whereas export through the Nares Strait and the Canadian Archipelago increases. Due to the changed ocean-mass transports, the Arctic Ocean and Greenland-Iceland-Norwegian Seas freshen. The freshening in the Greenland-Iceland-Norwegian Seas increases the buoyancy, attenuating deep-water formation. In the Labrador Sea, a higher salt import via Davis Strait decreases vertical stability, allowing for enhanced deep-water formation. 

The sensitivity experiments show that the oceanic response can be predominantly attributed to the change in wind stress due to the lower surface elevation over Greenland, amplified by the change in Greenland’s surface-properties. Only in the Labrador Sea, changes in GrIS surface properties dominate the differences in the signal. Heat from a stronger summer warming over Greenland due to the reduced albedo and changes in vegetation is stored in the Labrador Sea and keeps ocean temperature warmer throughout the entire year, as compared to an experiment considering only a lower surface elevation. These findings suggest that both reduced mechanical blocking and changes in Greenland’s surface properties, due to a disintegration of the GrIS, are key for the atmospheric and oceanic response. Further, the simulations indicate that a disintegrated GrIS influences not only the local climate around Greenland but also the remote climate. This is a step forward in understanding the distinct effects of a changing GrIS on the full climate system.

How to cite: Andernach, M., Kapsch, M.-L., and Mikolajewicz, U.: Impact of the Greenland Ice Sheet on the Atmosphere and Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17517, https://doi.org/10.5194/egusphere-egu24-17517, 2024.

EGU24-521 | ECS | Posters on site | CL1.2.10

Geochemical signals from biogenic varves reflect hydroclimate and lake oxygen conditions in central Finland 

Mohib Billah, Saija Saarni, Rik Tjallingii, Birgit Schröder, Sylvia Pinkerneil, Timo Saarinen, and Achim Brauer

Annually laminated (varved) lacustrine sediments are sensitive recorders of climatic-induced variability in the catchment. In a Boreal setting, climatic information is usually extracted from clastic-biogenic varves, although the potential of biogenic varves remains almost unexplored. The organic-rich sublayers of Boreal biogenic varves usually include thicker growing season lamina enriched with amorphous organic matter and thinner winter lamina reinforced with fine-grained organic matter settled under ice cover during the winter season. This study explores the properties and controls of varve formation in Lake Kallio-Kourujärvi and their implications in understanding past hydroclimate and lake oxygen conditions using micro-XRF combined with stable carbon and nitrogen isotope analysis. Lake Kallio-Kourujärvi is located in central Finland and has organic-rich varves. The thickness of these varves is controlled by the accumulation of biogenic matter that originates from terrestrial sources and autochthonous production. The varve counting provides an age estimate for the 1,8 m long varved sediment sequence of approximately 3700 years before the present (BP). The results from major elemental data reveal that changes in iron and sulfur are consistent with the varve thickness data previously shown to be sensitive for precipitation, as well as decadal changes in North Atlantic Oscillations (NAO) forced winter precipitation. Precipitation likely increases the transport of soluble Iron(II) from the catchment, which settles into sediment as particulate Iron(III) after being oxidised in the water column. Strong changes of redox conditions by the elements iron, manganese, and sulphur are indicated between around 1600 BP and 3700 BP. The variation of redox-sensitive elements suggests that changes in hydroclimatic conditions and past water mixing conditions can be reconstructed from the biogenic varve records.

How to cite: Billah, M., Saarni, S., Tjallingii, R., Schröder, B., Pinkerneil, S., Saarinen, T., and Brauer, A.: Geochemical signals from biogenic varves reflect hydroclimate and lake oxygen conditions in central Finland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-521, https://doi.org/10.5194/egusphere-egu24-521, 2024.

EGU24-3414 | Orals | CL1.2.10

A Punctuated Equilibrium Analysis of the Climate Evolution of Cenozoic exhibits a Hierarchy of Abrupt Transitions 

Denis-Didier Rousseau, Witold Bagniewski, and Valerio Lucarini

The Earth’s climate has experienced numerous critical transitions during its history, which have often been accompanied by massive and rapid changes in the biosphere. Such transitions are evidenced in various proxy records covering different timescales. The goal is then to identify, date, characterize, and rank past critical transitions in terms of importance, thus possibly yielding a more thorough perspective on climatic history. To illustrate such an approach, which is inspired by the punctuated equilibrium perspective on the theory of evolution, we have analyzed 2 key high-resolution datasets: the CENOGRID marine compilation (past 66 Myr), and North Atlantic U1308 record (past 3.3 Myr). By combining recurrence analysis of the individual time series with a multivariate representation of the system based on the theory of the quasi-potential, we identify the key abrupt transitions associated with major regime changes that separate various clusters of climate variability. This allows interpreting the time-evolution of the system as a trajectory taking place in a dynamical landscape, whose multiscale features describe a hierarchy of metastable states and associated tipping points.

The analysis reveals that two major events out of the ten dominated the evolution of the Earth's climate system over the last 66 million years. The first event was the Chicxulub meteor impact in Mexico, which killed off the large dinosaurs approximately 65,5 million years ago. This catastrophe marked the beginning of a very warm period with high levels of CO2. For the following 30 million years this regime dictated which climatic changes were possible and kept it within the regime of hot and warm climates.

The second crucial event was the tipping point associated with the glaciation of the Southern hemisphere 34 million years ago when the Antarctic continent was isolated at the South Pole due to plate tectonics. The forming of the large ice sheet led to the glaciation of the North as well and marked the beginning of a considerably colder type of climate on Earth, again dictating the scope of future climate changes.

The analysis additionally suggests that our current global climate system still belongs to the latter climate regime and still depends on the existence of the gigantic ice bodies built within the Coolhouse/Icehouse era. In the event that the ice sheets should not withstand anthropogenic global warming, the deglaciation will therefore represent a landmark tipping point similar to the two that have dominated Earth's history leading to a new unknown climate landscape.

Rousseau, DD., Bagniewski, W. & Lucarini, V. A punctuated equilibrium analysis of the climate evolution of cenozoic exhibits a hierarchy of abrupt transitions. Sci Rep 13, 11290 (2023). doi: 10.1038/s41598-023-38454-6

How to cite: Rousseau, D.-D., Bagniewski, W., and Lucarini, V.: A Punctuated Equilibrium Analysis of the Climate Evolution of Cenozoic exhibits a Hierarchy of Abrupt Transitions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3414, https://doi.org/10.5194/egusphere-egu24-3414, 2024.

The study of centennial-scale events remains underdeveloped, with little knowledge of events timing, their inter-regional phasing, and the role played by the Atlantic Meridional Overturning Circulation (AMOC) during these events (1, 2). Here we present four high-precision speleothem δ18O records from Asian summer monsoon (ASM) and South American summer monsoon (SASM) domains, spanning a centennial-scale 55 ka event. These speleothem records are comparable to those previously published from Europe, indicates that the 55 ka event occurred simultaneously in the European and ASM domains. The synchronous timing during the centennial-sale events is consistent with what has previously been observed during millennial events (1). It is therefore likely that abrupt climate change teleconnections between North Atlantic and ASM hydroclimates would have pervasively persisted during the last glacial period. Additionally, the speleothem records were compared with the bipolar ice-core and marine sediment records of INTIMATE. The “monsoon seesaw” pattern between the ASM and SASM records over 55 ka event is consistent with a northward shift of the Intertropical Convergence Zone (ITCZ). Our study suggests that the 55 ka event was caused by AMOC reinvigoration.

 

Ref.

(1) Corrick, E C. et al. Synchronous timing of abrupt climate changes during the last glacial period. Science 369,963-969 (2020).

(2) Lynch-Stieglitz, J. The Atlantic Meridional Overturning Circulation and Abrupt Climate Change. Annual Review of Marine Science 9, 83-104 (2017).

 

How to cite: Dong, X.: Timing and climate dynamics of centennial-scale abrupt climate change during early Marine Isotope Stage 3 inferred from the INTIMATE network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4983, https://doi.org/10.5194/egusphere-egu24-4983, 2024.

EGU24-5356 | ECS | Orals | CL1.2.10 | Highlight

Climatic and environmental impacts of the ~74 ka Youngest Toba Tuff volcanic eruption in Indonesia as evidenced from the sediment record of Lake Chala (Tanzania/Kenya) 

Jinheum Park, Christian Wolff, Dirk Verschuren, Melanie J. Leng, Jack H. Lacey, Maarten Van Daele, Christine S. Lane, Catherine Martin-Jones, Céline M. Vidal, Clive Oppenheimer, and Philip A. Barker

The ~74 ka Youngest Toba Tuff (YTT) eruption of Mount Toba in Indonesia is considered to be the largest volcanic eruption during the last 2.6 Ma. Its impact on global climate regimes and ecosystems, especially in tropical regions, is important due to possible consequences for the evolution and dispersal of early modern humans. In this study, we utilise the high-quality lake-sediment record from Lake Chala (Tanzania/Kenya), recovered by the ICDP DeepCHALLA project, to reconstruct the climatic and environmental impacts of the YTT in eastern equatorial Africa. Previous work identified a cryptotephra layer that was geochemically correlated to the YTT. In this study, focusing on the section of finely laminated sediments lying directly below and above the YTT layer, we compile high-resolution data from thin-section optical microscopy, geochemistry and fossil diatom assemblages in order to trace changes in climatic, local lake-system and wider environmental conditions immediately before and after the YTT event. Most proxy analyses were conducted at annual or higher temporal resolution, which is rare for late-Pleistocene palaeo-records. Our results reveal changes in regional hydroclimate following the YTT eruption, possibly coupled with volcanically induced changes in the El Niño–Southern Oscillation dynamics. Further, the precise location of the YTT layer within varved Lake Chala sediments provides new information on the season of the YTT eruption.

How to cite: Park, J., Wolff, C., Verschuren, D., Leng, M. J., Lacey, J. H., Van Daele, M., Lane, C. S., Martin-Jones, C., Vidal, C. M., Oppenheimer, C., and Barker, P. A.: Climatic and environmental impacts of the ~74 ka Youngest Toba Tuff volcanic eruption in Indonesia as evidenced from the sediment record of Lake Chala (Tanzania/Kenya), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5356, https://doi.org/10.5194/egusphere-egu24-5356, 2024.

EGU24-5613 | ECS | Orals | CL1.2.10

Abrupt onset and termination of the Holocene Humid Period across Asia 

Yonaton Goldsmith, Hai Xu, Narantsetseg Ts, Adi Torfstein1, Mordechai Stein, and Yehouda Enzel

The termination of the Holocene Humid Period between 6-5 kyrs ago is relatively well-documented in Africa. By contrast, outside of Africa the spatial extent of this termination, the rate of change (gradual vs. abrupt) and the timing of this termination remain obscure. To assess whether such a termination occurred in Asia and to characterize the spatial and temporal evolution of this termination, we constructed lake-level histories of five closed-basin lakes, four of which are located along a north-south transect in East Asia (Lakes Khukh, Dali, Daihai and Chenghai from 50N to 25N) and the fifth is the Dead Sea in western Asia (33N). A closed-basin lake has no outlet, and therefore its size varies as a function of precipitation and evaporation. Distinct shoreline deposits form at the lake’s margin and are physical relict imprints of past lake-levels. These lake-level histories provide a powerful, first order, quantitative record of past water availability. For each lake, we developed a detailed lake-area history based on numerous radiocarbon, Optical Stimulated Luminescence and U/Th disequilibrium ages.

All five lakes show that substantial changes in lake-level (up to 60 m) and surface area (of up to six times that of modern area) occurred throughout the Holocene. The results indicate that in East Asia wet conditions were initiated during the Bølling-Allerød and weakened and dried during the Younger-Dryas. The onset of the Holocene Humid Period, at 11.5 kyrs, was rapid, with the lakes rising to their high-stands within a half millennium. In western Asia, the lake-level rise most likely occurred later, at ~10 kyrs. During the Holocene Humid Period the lakes were significantly larger than the modern lakes. The wet conditions in northeast Asia and western Asia prevailed until 6 kyrs, when the lakes dried out abruptly, within a few decades, and have not been restored to their pre-6 kyrs sizes since. In South China, the rapid drying occurred earlier, at ca. 8 kyrs. All five lakes show a substantial dry period between 6 – 4 kyrs. In northeast Asia the dry conditions prevail until today. However, in both South China and western Asia the lakes rose at 3 kyrs and remained mostly high until recently.

Our findings from the five Asian closed-basin lakes show that during the early Holocene, Asia was scattered with lakes that were much larger than today and that an abrupt onset and abrupt termination of the Holocene humid period occurred across Asia. We use the lake-level histories to quantify regional water availability, to discuss the migration of rain-belts in Asia, speleothem oxygen isotopes and pollen records, and the ability of transient climate models to capture the magnitude, extent and rapidness of these wet conditions and hydroclimatic transitions.

How to cite: Goldsmith, Y., Xu, H., Ts, N., Torfstein1, A., Stein, M., and Enzel, Y.: Abrupt onset and termination of the Holocene Humid Period across Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5613, https://doi.org/10.5194/egusphere-egu24-5613, 2024.

EGU24-7498 | ECS | Orals | CL1.2.10

Towards the construction of regional marine radiocarbon calibration curves: an unsupervised machine learning approach 

Ana-Cristina Mârza, Laurie Menviel, and Luke Skinner

Radiocarbon may serve as a powerful dating tool in palaeoceanography, but its accuracy is severely limited by the need to calibrate radiocarbon dates to calendar ages. A key problem is that marine radiocarbon dates must be corrected for past offsets from either the contemporary atmosphere (i.e. ‘reservoir age’ offsets) or a modelled estimate of the global average surface ocean (i.e. delta-R offsets). This presents a challenge because the spatial distribution of reservoir ages and delta-R offsets can vary significantly, particularly over periods of major marine hydrographic and/or carbon cycle change such as the last deglaciation. Modern reservoir age/delta-R estimates therefore have limited applicability.  The construction of regional marine calibration curves could provide a solution to this challenge, if coherent regions could be defined. Here, we use unsupervised machine learning techniques to define distinct regions of the surface ocean that exhibit coherent behaviour in terms of their radiocarbon age offsets from the contemporary atmosphere (R-ages). We investigate the performance of different clustering algorithms applied to outputs from different numerical models. Comparisons between the cluster assignments across model runs confirm some robust regional patterns that likely arise from constraints imposed by large-scale ocean and atmospheric physics. At the coarsest scale, regions of coherent R-age variability are associated with the major ocean basins. By further dividing basin-scale shape-based clusters into amplitude-based subclusters, we recover regional associations that cohere with known modern oceanographic processes, such as increased high latitude R-ages, or the propagation of R-age anomalies from the Southern Ocean to the Eastern Equatorial Pacific. We show that the medoids for these regional sub-clusters provide significantly better approximations of simulated local R-age variability than constant offsets from the global surface average. The proposed clusters are also found to be broadly consistent with existing reservoir age reconstructions that span the last ~30 ka. We therefore propose that machine learning provides a promising approach to the problem of defining regions for which marine radiocarbon calibration curves may eventually be generated.

How to cite: Mârza, A.-C., Menviel, L., and Skinner, L.: Towards the construction of regional marine radiocarbon calibration curves: an unsupervised machine learning approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7498, https://doi.org/10.5194/egusphere-egu24-7498, 2024.

EGU24-8105 | Posters on site | CL1.2.10

Rigorous Identification of Variations and Changepoints in the Observed Rates of Radiocarbon Samples Over Time  

Timothy J Heaton, Sara Al-assam, and Edouard Bard

A commonly-used approach to estimate changes in the frequency of past events or the size of populations looks at variations in the rate of archaeological and environmental samples (e.g., charcoal from fires, human/animal bones, or other evidence of occupation) found at a site over time. Time periods with large numbers of samples suggest increased activity, while those with few samples indicate a reduced level of activity. Variations and abrupt changes in the rate of observed samples might suggest the influence of important external environmental factors. This paradigm is known as “dates-as-data”.

The reliability of such a “dates-as-data” approach is highly dependent upon our ability to estimate the calendar ages of the discoveries. Most archaeological/environmental dates are obtained using radiocarbon (14C). All 14C determinations need to be calibrated in order that they can be understood on the calendar scale. This introduces considerable uncertainties in the resultant calendar ages and complicates the identification of changepoints in the calendar year rates at which samples occur.

In this talk, we provide a statistically rigorous approach to overcome these challenges. We model the occurrence of events (each assumed to leave a 14C sample in the archaeological/environmental record) as an inhomogeneous Poisson process, estimating the varying rate of samples using reversible-jump Markov Chain Monte Carlo. Given a set of radiocarbon samples, we aim to reconstruct how their occurrence rate varies over calendar time and identify if there are statistically significant changepoints in the rate at which the samples arise (i.e., specific times at which the rate of events abruptly changes).

We will demonstrate our approach on data exploring the expansion of humans, and the parallel disappearance of megafauna, in the Yukon and Alaska in the late Pleistocene and early Holocene: investigating both the timings of such migrations in comparison with the climatic changes known to have occurred during this period, and the potential interactions between humans and the various species in the region.

How to cite: Heaton, T. J., Al-assam, S., and Bard, E.: Rigorous Identification of Variations and Changepoints in the Observed Rates of Radiocarbon Samples Over Time , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8105, https://doi.org/10.5194/egusphere-egu24-8105, 2024.

EGU24-8147 | ECS | Orals | CL1.2.10

A unique preservation window capturing coastal-marine landscape evolution across the MIS5-4 cooling event (Late Pleistocene, North Sea Basin) 

Irene Waajen, Timme Donders, Freek Busschers, Frank Wesselingh, Friederieke Wagner-Cremer, Francien Peterse, Sytze van Heteren, and Ruth Plets

The Late Pleistocene MIS5 - MIS4 transition (ca. 80-70 ka) is globally known to correspond to a major cooling event accompanied by a large decline in eustatic sea level. This transition must have radically changed coastal landscapes worldwide, affecting basin shape, salinity regimes, river courses, as well as biota. Most existing records are from either local lacustrine, ice core or distal oceanic records, while dated and continuous records from coastal environments are lacking. Within the southern North Sea Basin a unique record of coupled terrestrial-marine signals exists in the deposits of the Brown Bank Formation, covering the MIS5-MIS4 transition. Here, we target the Brown Bank Formation to produce a new integrated palaeoenvironment and -climate framework for the MIS5-4 transition and show biotic and abiotic environmental response to rapid cooling in a coastal area.

Multi-proxy records of lipid biomarkers, pollen, mollusk and diatom assemblages for the MIS5-4 transition in the center of the southern North Sea are combined with seismic facies determinations. The Brown Bank Formation consists of multiple facies representing multiple depositional phases around the MIS5-4 transition, and provides insights into the cooling of the terrestrial and shallow marine environments. On land, the vegetation changed from boreal forests to more open, grassland vegetation, combined with an increase in soil erosion. At the same time the shallow marine environment of the southern North Sea experienced subarctic to arctic marine conditions with a high input of soil material. These continued cool marine conditions have not been described earlier for this region and show that sea level remained high and lagged local cooling, as inferred from lipid-biomarker palaeothermometry. Assuming that this lag between sea-level and temperature change is common during cooling events, it is a potential mechanism creating sediment preservation windows during the onset of glacial intervals in shallow marine environments. Preserved records like the one presented here are valuable because they capture both the unique changes in cold marine environments, as well as informative terrestrial signals that are rarely preserved onshore.

How to cite: Waajen, I., Donders, T., Busschers, F., Wesselingh, F., Wagner-Cremer, F., Peterse, F., van Heteren, S., and Plets, R.: A unique preservation window capturing coastal-marine landscape evolution across the MIS5-4 cooling event (Late Pleistocene, North Sea Basin), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8147, https://doi.org/10.5194/egusphere-egu24-8147, 2024.

EGU24-9635 | ECS | Posters on site | CL1.2.10

Is climate warming causing eutrophication and anoxia? Lessons learned from Late-Glacial sediments of Lakes Amsoldingen and Soppen, Switzerland.  

Stan J. Schouten, Petra Zahajská, Noé R.M.M. Schmidhauser, Andrea Lami, Paul D. Zander, Rik Tjallingii, Petra Boltshauser-Kaltenrieder, Jacqueline van Leeuwen, Luyao Tu, Hendrik Vogel, and Martin Grosjean

Many lakes nowadays experience eutrophication, which poses significant threats to ecosystem stability and people who depend on lakes for freshwater. Lake hypoxia is a state with low dissolved oxygen and often associated with external nutrient additions to the lake. Hypoxia typically deteriorates lake water quality by 1) changing the chemistry of the lake water, and 2) challenging heterotrophic organisms but promoting growth of bacterial autotrophs that are adapted to anoxia and may produce harmful toxins. Little is known about how external factors (e.g., nutrients, climate) and algal/bacterial community dynamics compounded into the chemical deterioration of lake water and shaped lake ecology. We hypothesize that, at times without human disturbance, trophicity and hypoxia may have been driven by rapid climatic shifts (e.g., Dansgaard-Oeschger Events, DOE) with a rate and extend comparable to or faster than current global warming.

To gain insights into the driving processes of natural eutrophication and recovery phases, we studied the sedimentary records of two comparable Swiss lakes (Soppensee and Amsoldingersee) focussing on their (bio-)geochemistry during the Last Glacial Maximum and Late Glacial (17.0-11.6 cal. kyr. BP). The chronology of the cores was obtained using the Laacher See Tephra, a set of C-14 dated macrofossils, and bio-stratigraphic markers. We combined sequentially extracted data on phosphorous (P), iron (Fe), and manganese (Mn) to elaborate on redox-induced changes within the P, Mn, and Fe cycles. We reconstructed the changes in past primary producer communities using coloured biomarkers – chloro-pigments and carotenoids inferred by HPLC – as proxies. Using hyperspectral imaging, we assessed bulk pigment groups for leads and lags between primary producer groups on a sub-millimetre resolution.

Both lakes experienced similar large-scale forcings and have similar catchment properties. According to our results, the lakes both record algal blooms and anoxia in the Late Glacial, yet there are, surprisingly, significant differences in the timing of these eutrophication phases and anoxia events between the lakes. The Soppensee pigment record responded to the initial Bølling warming (14.6 cal. kyr. BP) by developing eutrophic conditions in a stratified lake with hypolimnetic anoxia and redissolution of redox sensitive phosphorous, iron and manganese. In Amsoldingersee, pigment data shows clear anoxic events that pre-date the Bølling warming and relate consistently to the colder phases within the Late-Glacial (GS-2/Heinrich Event 1, GI-d, GI-c3, and GS-1). In contrast to Soppensee, total chlorophyll, and carotenoids peaked when the climate was cool and dry, advocating for substantial aquatic production during cold periods. However, the rate of compositional change (RoC) was highest during the three major climatic transitions (DOE-1, Onset Younger Dryas, Onset Holocene), and not during the anoxic phases. From ordination experiments, we further infer that algal/bacterial communities indeed recovered from their anoxic states. In addition, we noticed a surprisingly high pigment diversity throughout the Oldest Dryas (GS-2). Our data add to the view of a dynamic landscape evolution during the Oldest Dryas (Heinrich Event 1) which was previously assumed to be a stable cold phase in the peri-alpine area.

How to cite: Schouten, S. J., Zahajská, P., Schmidhauser, N. R. M. M., Lami, A., Zander, P. D., Tjallingii, R., Boltshauser-Kaltenrieder, P., van Leeuwen, J., Tu, L., Vogel, H., and Grosjean, M.: Is climate warming causing eutrophication and anoxia? Lessons learned from Late-Glacial sediments of Lakes Amsoldingen and Soppen, Switzerland. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9635, https://doi.org/10.5194/egusphere-egu24-9635, 2024.

EGU24-10704 | ECS | Posters on site | CL1.2.10

Millennial-scale changes in hydroclimate during the last glacial period in central Europe reconstructed from leaf wax δD 

Paul Zander, Frank Sirocko, Xiaojing Du, Chijun Sun, Florian Rubach, Sarah Britzius, Gerald Haug, and Alfredo Martínez-García

Millennial-scale climate events during the last glacial period, such as Dansgaard-Oeschger cycles and Heinrich events, are well-documented in ice cores and marine sediments. During Dansgaard-Oeschger cycles of the last glacial period, repeated rapid warming events of a similar magnitude to modern-day warming occurred over the North Atlantic region. However, the impacts of these fluctuations on hydroclimate in Europe remain poorly constrained, mainly due to a lack of high-resolution, well-dated paleoclimate records. Here, we use D/H ratios (δD) measured on n-alkanes derived from leaf waxes preserved in lacustrine sediments from Eifel maar crater basins to reconstruct changes in hydroclimate. Our record spans the past 60,000 years and is tied to the Greenland NGRIP ice core chronology using a high-resolution index of lake productivity. Initial results show that δDwax was more depleted during interstadial phases of the last glacial period. Multiple factors may influence δDwax; however, if an isotope “temperature effect” played a dominant role, the warmer interstadials would have been associated with more positive δDwax values, in contrast to the observations here.  Thus, we interpret low δD during interstadials as a signal of wetter, more humid conditions, possibly related to a shift towards more winter precipitation due to changes in the position of the westerlies. We compare our proxy measurements with an isotope-enabled transient climate simulation of the last deglaciation (iTRACE) to constrain the dynamical factors associated with changes in precipitation δD over stadial/interstadial changes. These results provide important constraints on past millennial-scale hydrological changes in Europe in response to changes in North Atlantic circulation.

How to cite: Zander, P., Sirocko, F., Du, X., Sun, C., Rubach, F., Britzius, S., Haug, G., and Martínez-García, A.: Millennial-scale changes in hydroclimate during the last glacial period in central Europe reconstructed from leaf wax δD, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10704, https://doi.org/10.5194/egusphere-egu24-10704, 2024.

EGU24-10736 | Posters on site | CL1.2.10

Marine radiocarbon reservoir age simulations for the past 50000 years revisited 

Martin Butzin and Gerrit Lohmann

Prior to about 14 ka BP, the most recent radiocarbon (14C) calibration curve IntCal20 is based on a combination of terrestrial and marine 14C archives. To gain insight into the spatio-temporal evolution of the involved marine 14C records and their systematic 14C concentration differences from the atmosphere, IntCal20 has considered marine reservoir age (MRA) simulations of the LSG ocean general circulation model. The LSG model was not fully coupled to the atmosphere and did not include a prognostic sea ice component. Instead, it applied various stadial and interstadial climate boundary conditions to assess upper and lower bounds of past climate variations and the associated effects on past MRAs. Here, we present results of new long-term MRA simulations which overcome this limitation. We apply the Earth system model of intermediate complexity CLIMBER-X which we have equipped with ∆14C and noble gas tracers. CLIMBER-X is forced with insolation, greenhouse gas concentrations, and continental ice sheets. Radiocarbon is prescribed in the atmosphere according to IntCal20. While the new simulations confirm some of the LSG model results at the global scale, there are considerable regional differences. For example, we find weaker inhibition of marine 14CO2 uptake in the presence of sea ice and hence lower polar MRAs than the LSG model. Moreover, we find that continental ice sheet forcing affects MRAs at the ocean-basin scale. This is particularly the case during the last deglaciation for which some meltwater discharge reconstructions could be questioned according to our results.

How to cite: Butzin, M. and Lohmann, G.: Marine radiocarbon reservoir age simulations for the past 50000 years revisited, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10736, https://doi.org/10.5194/egusphere-egu24-10736, 2024.

EGU24-11033 | ECS | Posters on site | CL1.2.10

Variations of the authigenic 10Be/9Be-ratio in marine sediments during the Laschamps event and their use for dating of marine sediments 

Julia Loftfield, Thomas Frederichs, Johannes Lachner, Lester Lembke-Jene, Jiabo Liu, Norbert Nowaczyk, Georg Rugel, Konstanze Stübner, and Florian Adolphi

The atmospheric production rate changes of cosmogenic 10Be are caused by variations of the Earth’s and Sun’s magnetic fields and are recorded worldwide in different climate archives (e.g. ice cores, marine/lacustrine sediments, speleothems). This makes 10Be a useful tool to synchronize them, thereby overcoming the limitations in precision and accuracy of their individual age models.

Here we present new 10Be/9Be data from a suite of marine sediment cores from the Scotia Sea, Drake Passage and South Pacific covering the Laschamps geomagnetic dipole minimum (~ 41 kaBP). Due to the reduction of the Earth’s magnetic shielding at this time, the 10Be-production rates roughly doubled, providing an ideal time marker for synchronization. We analyzed the cosmogenic 10Be and stable 9Be in the authigenic fraction of the sediments, which represents the 10Be/9Be signature of the surrounding water. Analyzing the 10Be/9Be ratio reduces the effect of variable particle scavenging rates on 10Be delivery to the sea floor. We compare our data to existing 10Be records from other marine sediment cores and ice cores, and to paleomagnetic field reconstructions. We discuss the potential and limitations of using 10Be/9Be ratios for dating marine sediments, and test whether using authigenic 10Be/9Be for synchronization is consistent with the traditional approach of matching climate records to reference sites.

How to cite: Loftfield, J., Frederichs, T., Lachner, J., Lembke-Jene, L., Liu, J., Nowaczyk, N., Rugel, G., Stübner, K., and Adolphi, F.: Variations of the authigenic 10Be/9Be-ratio in marine sediments during the Laschamps event and their use for dating of marine sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11033, https://doi.org/10.5194/egusphere-egu24-11033, 2024.

EGU24-12137 | Orals | CL1.2.10

14,700 years of climate and environmental change recorded in 17.8 meters of lake and peat deposits in the Nieuwe Veen pingo remnant, NE Netherlands 

Wim Hoek, Timme Donders, Stan Schouten, Vincent van Doorn, Jacqueline van Leeuwen, and Arjan van Eijk

Pingo remnants are the deep lakes that formed by melting of ice lenses during permafrost degradation at the end of the Last Glacial, and they are particularly abundant in the northern Netherlands. Most of these isolated circular depressions have a diameter of 100-200 meters and are filled with a 5-10 meters thick sequence of lake and peat deposits, making them valuable archives of climate and environmental change. These natural sediment- and pollen-traps record not only the rapid changes during the Last Glacial-Interglacial Transition but also reveal the Holocene forest development as well as traces of human impact in the surrounding landscape.

In this study, we report on the study of a continuous organic fill of nearly 18 meters in Nieuwe Veen, which may be the deepest pingo remnant in NW Europe. The pingo remnant fill is composed of a sequence of partly sand laminated lake and peat deposits containing fine and coarse detrital gyttjas, calcium- and iron-carbonate gyttjas and wood, sedge and moss peats with abundant macrofossils. A series of radiocarbon dates on selected terrestrial macrofossils provides a solid age model for the complete sequence starting 14,700 calendar years ago, coinciding with the first warming of the Late-Glacial Interstadial, corresponding to the onset of Greenland Interstadial 1 (GI-1). The results from 5-10 cm resolution palynological analyses reveal a complete picture of vegetation development while loss on ignition measurements at cm-resolution show the openness of the vegetation cover associated to colder periods as well as phases of human forest clearance.

A phase of particular interest is the cold Younger Dryas stadial corresponding to Greenland Stadial 1 (GS-1), which is represented by a more than 10 meters thick layer of sandy gyttjas. This allows for a reconstruction of environmental change in unprecedented detail with a resolution of potentially 1 cm/yr. The onset of the Younger Dryas stadial is abrupt and clearly visible in the core, as well as in the botanical and lithological proxies. There appear to be at least three distinct phases during the Younger Dryas stadial interval, especially reflected in the aquatic flora and lithological proxies, indicating shifting conditions in (hydro-)climate.

At the onset of the Holocene, also clearly visible, sand influx in the basin decreased rapidly due to an increasing vegetation cover in the surrounding landscape indicated by the botanical proxies. The lake system eventually changes into a fen and bog. In the Early Holocene, carbonate rich lake deposits indicate the influence of groundwater seepage. During the infilling, the source of the water changes towards atmospheric water, as evidenced by more oligotrophic species in the palynological record. Phases of forest opening related to human impact appear remarkably late in the record at about 5500 calendar years ago, with clear indications of agriculture only after 3000 calendar years ago. Final cultivation of the peatbog in the beginning of the 20th century caused the record younger than Medieval times to be destroyed.

How to cite: Hoek, W., Donders, T., Schouten, S., van Doorn, V., van Leeuwen, J., and van Eijk, A.: 14,700 years of climate and environmental change recorded in 17.8 meters of lake and peat deposits in the Nieuwe Veen pingo remnant, NE Netherlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12137, https://doi.org/10.5194/egusphere-egu24-12137, 2024.

EGU24-12386 | ECS | Orals | CL1.2.10 | Highlight

Speleothem sulfur spike confines timing and impact of late Glacial Laacher See eruption 

Sophie F Warken, Axel K Schmitt, Denis Scholz, Andreas Hertwig, Michael Weber, Regina Mertz-Kraus, Frederick Reinig, Jan Esper, and Michael Sigl

The Laacher See eruption (LSE) deposited a key tephra layer that synchronizes Late Glacial paleoclimate records across Europe, and thus provides the temporal framework to investigate the onset of the Younger Dryas cooling in the North Atlantic region. The absolute timing and climatic consequences of this event remain, however, still debated. Here, we present evidence from a high-resolution speleothem record from Herbstlabyrinth Cave, Central Germany, demonstrating distinct spikes in sulfur, fluorescent organic matter, and ash-leached trace elements assigned to the LSE and dating the event c. 13,047 BP1950, with an uncertainty of about 30–40 years. This age supports the recently published radiocarbon wiggle matching date of 13,006 ± 9 BP1950 (Reinig et al., 2021) and contradicts speculations about potential biases arising from volcanic CO2 emissions. The near-annually resolved speleothem calcite δ18O data further allows to assess the timing of the LSE and its impact on the regional climatology. Our findings exclude the LSE as a possible trigger of the Younger Dryas and indicate a regional climatic and environmental impact restricted to c. 20 years after the eruption. This unprecedented combination of stable isotopes, trace elements, annually resolved fluorescence, and radiometric dates for a single record provides independent evidence for the Late Glacial synchroneity of Atlantic-European climate relationships and opens new pathways toward a precise, absolutely dated time marker between European terrestrial and Greenland ice core records prior to the Holocene.

References

Reinig F, Wacker L, Jöris O, et al. (2021) Precise date for the Laacher See eruption synchronizes the Younger Dryas. Nature 595(7865): 66-69.

 

How to cite: Warken, S. F., Schmitt, A. K., Scholz, D., Hertwig, A., Weber, M., Mertz-Kraus, R., Reinig, F., Esper, J., and Sigl, M.: Speleothem sulfur spike confines timing and impact of late Glacial Laacher See eruption, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12386, https://doi.org/10.5194/egusphere-egu24-12386, 2024.

EGU24-12639 | Orals | CL1.2.10 | Highlight

Nordic Sea convection led abrupt North Atlantic warm events during Dansgaard-Oeschger cycles 

Margit Simon, Francesco Muschitiello, Henrik Sadatzki, Sarah Berben, Tobias Friedrich, Dag-Inge Blindheim, Lukas Wacker, Eystein Jansen, and Trond Dokken

During the last glacial period changes in the strength of ocean convection in the high-northern latitudes contributed to abrupt global climate changes known as Dansgaard–Oeschger (DO) cycles. However, the lack of high-resolution empirical evidence has yet precluded inferring the physical coupling between ocean and atmosphere. We examined Nordic Sea (NS) circulation changes by reconstructing radiocarbon ventilation ages across four DO cycles in a marine sediment core hinging on a precise multi-tephra-based synchronization to Greenland ice cores. Our results show that open ocean convection in the NS resumed ahead of the abrupt air-temperature increases recorded in ice cores by ∼400 years (95% range: 50-660 years). Thus, implying an active role of ocean dynamics where abrupt warming transitions are likely a nonlinear response to more gradual resumption of NS convection.

 

How to cite: Simon, M., Muschitiello, F., Sadatzki, H., Berben, S., Friedrich, T., Blindheim, D.-I., Wacker, L., Jansen, E., and Dokken, T.: Nordic Sea convection led abrupt North Atlantic warm events during Dansgaard-Oeschger cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12639, https://doi.org/10.5194/egusphere-egu24-12639, 2024.

EGU24-12672 | Orals | CL1.2.10

Human impacts on the environment in the preindustrial forest landscapes in Central Europe - an overview 

Michał Słowiński, Krzysztof Szewczyk, Jerzy Jonczak, Agnieszka Halaś, Agnieszka Mroczkowska, Dominika Łuców, Sandra Słowińska, Sebastian Tyszkowski, Anna Kowalska, Ewa Kołaczkowska, Paweł Swoboda, Aleksandra Chojnacka, Barbara Gumińska-Nowak, Mateusz Kramkowski, Cezary Kardasz, Vincenzo Barbarino, Agnieszka M. Noryśkiewicz, Bogusława Kruczkowska, Dariusz Brykała, and Tomasz Związek

Over the past few millennia, human activity has been one of the most unpredictable factors influencing environmental transformations. Human activities related to agriculture and land use are the primary forces driving the creation of new landscapes. Conversely, the influence of other factors on landscape transformation remains incompletely understood. In particular, forests have been exploited not only for timber but also for various wood-related products, including charcoal, potash, and tar. We consider that charcoal production, besides food production, which increased linearly with population growth, was a kind of turning point in human pressure on the forest environment. Particularly in the Middle Ages, when the demand for products such as glass, iron, and potash grew very rapidly, the production of these products required a higher temperature than that obtained by burning wood. However, the extent and impact of these activities on a spatial scale has not been fully recognized. Charcoal held significant economic and energy value in the pre-industrial era, evidenced by mapping over 600,000 remnants of charcoal hearths in Central Europe. Over time, the demand for energy escalated, leading to the widespread use of coal in the late 18th and early 19th centuries. Our aim is to provide a comprehensive understanding of the functioning of charcoal hearths and their role in shaping landscapes. To achieve this, we have combined research methods from biogeography, remote sensing, dendroecology, paleoecology, soil science, botany, onomastics, and art history. This interdisciplinary approach aims to capture not only the natural outcomes but also the social and economic consequences of charcoal production. Our paleoecological findings reveal an intermediate disturbance linked to the operation of charcoal hearths, influencing both short-term and long-term changes in ecosystems with a cascading effect. The production of charcoal has far-reaching consequences, exerting a substantial impact on vegetation composition, soil properties, microclimate, the water cycle, and ultimately leading to erosion, thereby affecting adjoining ecosystems. This research addresses the growing interest in the legacy of charcoal hearths in historical human activities and their pivotal role in shaping landscape transformations during the pre-industrial era.

The study is the result of research project No. 2018/31/B/ST10/02498 funded by the Polish National Science Centre.

How to cite: Słowiński, M., Szewczyk, K., Jonczak, J., Halaś, A., Mroczkowska, A., Łuców, D., Słowińska, S., Tyszkowski, S., Kowalska, A., Kołaczkowska, E., Swoboda, P., Chojnacka, A., Gumińska-Nowak, B., Kramkowski, M., Kardasz, C., Barbarino, V., Noryśkiewicz, A. M., Kruczkowska, B., Brykała, D., and Związek, T.: Human impacts on the environment in the preindustrial forest landscapes in Central Europe - an overview, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12672, https://doi.org/10.5194/egusphere-egu24-12672, 2024.

Ice sheet evolution profoundly influences the climate system through changes in orography, surface albedo, freshwater fluxes to the ocean, and ocean gateways. The changes to the climate system will, in turn, affect the ice sheets, leading to complex feedback loops. To date, the relative roles of these feedback loops have not been examined over a full glacial cycle. To address this, we employ the glacial earth system model of intermediate complexity LCice in transient simulations of the complete last glacial cycle. Through ensemble-based sensitivity experiments, we isolate the impact of individual ice sheet orography, albedo, meltwater input, Bering Strait opening/closure, and glacio-isostatic adjustment on the climate system and back onto the ice sheet evolution itself. To assess possible state dependencies, we compare the individual impact of ice-climate feedbacks on both the ice sheet growth and decay phase around MIS 5d (Last Glacial Inception) and MIS 2 (Last Glacial Maximum). 

The sensitivity of the North American and Eurasian ice sheets to some feedbacks changes from MIS 5d to MIS 2, suggesting a potential threshold behaviour and complex non-linear dynamics. Our analysis also examines which characteristics of last glacial cycle ice sheet evolution are relatively robust and which are more likely to be highly sensitive to incompletely resolved feedback loops. This work thereby not only improves our understanding of paleo ice/climate coupled dynamics but also identifies feedback pathways that are likely to generate the largest uncertainties in coupled ice and paleoclimate modelling.

How to cite: Geng, M. and Tarasov, L.: Exploring Ice Sheet-Climate Feedbacks Across the Last Glacial Cycle: Insights from a Transient Sensitivity Ensemble , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1135, https://doi.org/10.5194/egusphere-egu24-1135, 2024.

Using all available simulations performed by climate models participating in PMIP4 (Paleoclimate Modelling Intercomparison Project – Phase 4), we quantify the seasonality change of surface air temperature over China during the mid-Holocene (6000 years ago) and the associated physical mechanisms. Relative to the preindustrial period, all 16 models consistently show an enhanced temperature seasonality (i.e., summer minus winter temperature) across China during that interglacial period, with a nationally averaged enhancement of 2.44°C or 9% for the multimodel mean. The temperature seasonality change is closely related with the seasonal contrast variation of surface energy fluxes mainly due to the mid-Holocene orbital forcing. Specifically, the summer–winter increase in surface net shortwave radiation dominates the intensified temperature seasonality at the large scale of China during the mid-Holocene; the surface net longwave radiation has a minor positive contribution in most of the Tibetan Plateau and eastern China; and both the surface latent and sensible heat fluxes show partial offset effects in most of the country. There are uncertainties in the reconstructed temperature seasonality over China during the mid-Holocene based on the proxy data that can reflect seasonal signals.

How to cite: Tian, Z.: Enhanced seasonality of surface air temperature over China during the mid-Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1945, https://doi.org/10.5194/egusphere-egu24-1945, 2024.

EGU24-2362 | ECS | Posters on site | CL1.2.13

Response of large-scale Ocean Circulation to Global Internal Wave Parameterization IDEMIX under Last Glacial Maximum Conditions 

Heves Pilatin, André Paul, Friederike Pollmann, and Michael Schulz

As the most recent glacial period of Earth's history, the Last Glacial Maximum (~21,000 years before the present day, LGM) is an important and one of the most studied paleo times when the ice-sheet coverage was at the maximum extent, and the global average temperature was 6°C cooler than present day (PI). The large volume of ice caused an approximately 130 m drop in sea level and exposure of the continental shelves, shifting the tidal dissipation energy that sinks in the present-day shelf seas to the open ocean during the LGM. Regarding this hypothesis, the LGM ocean is expected to be more turbulent and well-ventilated in the abyssal and possibly have a much stronger overturning circulation in the North Atlantic compared to the present day. However, the paleo records of δ13C indicate a deoxygenated deep ocean for LGM. In this study, we test the LGM hypothesis on the global circulation and marine biogeochemical processes by implementing a new energetically consistent ocean mixing parameterization: Internal Wave Dissipation, Energy, and Mixing (IDEMIX) in the fully coupled isotope-enabled Community Earth System Model (iCESM1.2). For the scope of this study, we solely focus on baroclinic tidal-induced mixing by parameterizing dissipation from the internal wave breaking in IDEMIX. Our preliminary results illustrate the LGM ocean as more vigorous than the PI ocean only when the IDEMIX is used in the model since the diffusivities are enhanced by almost two orders of magnitude, especially over the rough bathymetry with IDEMIX coupling. Otherwise, no significant difference is observed between the vertical diffusivities of LGM and PI oceans without IDEMIX, despite the divergence in their tidal energy dissipation fields. The increase in the diffusivities with IDEMIX application can be seen not just at the ocean bottom but also along the entire water column near the internal wave generation sites where the tidal energy dissipation is strongest (e.g., the Mid-Atlantic Ridge, the Hawaiian Ridge, or high latitudes in Atlantic). Consistent with the hypothesis, the turbulence near the exposed shelves is boosted in the deep ocean and dispersed across different depth levels from here when the model uses IDEMIX for the LGM simulation. Additionally, the North Atlantic Deep Water (NADW) cell gets weaker and shallower by ∼ 2 Sv, and the Antarctic Bottom Water (AABW) cell enlarges based on the IDEMIX influence on the LGM ocean.

How to cite: Pilatin, H., Paul, A., Pollmann, F., and Schulz, M.: Response of large-scale Ocean Circulation to Global Internal Wave Parameterization IDEMIX under Last Glacial Maximum Conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2362, https://doi.org/10.5194/egusphere-egu24-2362, 2024.

EGU24-5380 | Posters on site | CL1.2.13

Indian Ocean variability changes in the Paleoclimate Modelling Intercomparison Project 

Chris Brierley, Kaustubh Thirumalai, Edward Grindrod, Harry Grosvenor, Jonathan Barnsley, Charles Williams, and Heather Ford

The Indian Ocean exhibits multiple modes of interannual climate variability, whose future behaviour is uncertain. Recent analysis of glacial climates has uncovered an additional El Niño-like equatorial mode in the Indian Ocean, which could also emerge in future warm states. Here we explore changes in the tropical Indian Ocean simulated by the Paleoclimate Model Intercomparison Project (PMIP4). These simulations are performed by an ensemble of models contributing to the Coupled Model Intercomparison Project 6 and over five coordinated experiments: four past periods (midHolocene, lgm, lig127k and midPliocene-eoi400) and an idealized forcing scenario to examine the impact of greenhouse forcing. The two interglacial experiments are used to characterize the role of orbital variations in the seasonal cycle, whilst the others are focused on responses to large changes in global temperature. The Indian Ocean Basin Mode (IOBM) is damped in both the mid-Holocene and last interglacial, with the amount related to the damping of the El Niño–Southern Oscillation in the Pacific. No coherent changes in the strength of the IOBM are seen with global temperature changes; neither are changes in the Indian Ocean Dipole (IOD) nor the Niño-like mode. Under orbital forcing, the IOD robustly weakens during the mid-Holocene experiment, with only minor reductions in amplitude during the last interglacial. Orbital changes do impact the SST pattern of the Indian Ocean Dipole, with the cold pole reaching up to the Equator and extending along it. Induced changes in the regional seasonality are hypothesized to be an important control on changes in the Indian Ocean variability.

How to cite: Brierley, C., Thirumalai, K., Grindrod, E., Grosvenor, H., Barnsley, J., Williams, C., and Ford, H.: Indian Ocean variability changes in the Paleoclimate Modelling Intercomparison Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5380, https://doi.org/10.5194/egusphere-egu24-5380, 2024.

EGU24-5474 | ECS | Orals | CL1.2.13 | Highlight

Arctic sea-ice loss: Is the Last Interglacial (127 ka BP) a good analog of our future? 

Marie Sicard, Agatha M. de Boer, Helen K. Coxall, Torben Koenigk, Mehdi Pasha Karami, Martin Jakobsson, and Matt O'Regan

Variations in sea-ice cover result from a combination of changes in external forcing, internal variability, and feedbacks. Because of the complex interconnections between the mechanisms involved, the long-term evolution of Arctic sea ice and its interaction with the ocean and atmosphere are not yet completely understood, leading to large uncertainties in climate projections.

In this study, we focus on patterns of sea-ice loss in the context of past and future Arctic warming. Using a 7-member global circulation model ensemble from CMIP6/PMIP4, we compare the spatial distribution of the Arctic sea ice in a time-slice simulation representing the climate of the Last Interglacial 127,000 years ago and an idealized CO2-forced experiment with a similar annual sea-ice volume.

The major differences between the two periods occur close to the sea-ice margins, due to variations in both oceanic and atmospheric circulation regimes. In particular, a positive sea level pressure anomaly forms over Greenland under CO2 forcing, enhancing the anticyclonic circulation around the island. Consequently, surface winds push more ice along the east coast of Greenland towards the Irminger Sea, where models generally simulate a higher sea-ice concentration in the CO2-forced experiment than in the Last Interglacial simulation. Analogously, on the western side, a weaker export of ice to the south leads to more ice accumulation in northern Baffin Bay. In the Bering and Barents Seas, the increased inflow of warm Pacific and Atlantic waters causes more ice to melt in the CO2-forced simulation. In this context, we explore the implication that Atlantification may be more pronounced in the future than during the Last Interglacial period. Finally, the oceanic region north of Greenland is most resilient to sea-ice loss under both the Last Interglacial solar forcing and future CO2 forcing. This would imply that this region, often referred to as the “Last Ice area,” could also have been the last to lose ice during the Last Interglacial period.

How to cite: Sicard, M., de Boer, A. M., Coxall, H. K., Koenigk, T., Karami, M. P., Jakobsson, M., and O'Regan, M.: Arctic sea-ice loss: Is the Last Interglacial (127 ka BP) a good analog of our future?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5474, https://doi.org/10.5194/egusphere-egu24-5474, 2024.

EGU24-7693 | Posters on site | CL1.2.13

Mechanisms of reduced mid-Holocene precipitation in arid central Asia as simulated by PMIP3/4 models 

Tao Wang, Hongna Xu, Dabang Jiang, and Junqiang Yao

We investigated the precipitation changes in mid-latitude arid central Asia (ACA, including Central Asia and Xinjiang) and the related mechanisms in the mid-Holocene using the output from the Paleoclimate Modelling Intercomparison Project phases 3 and 4 (PMIP3/4). The annual precipitation in ACA was decreased in the mid-Holocene compared with the pre-industrial period, consistent in direction with reconstruction records. Such change was mainly due to deficient winter and spring (December–May) precipitation in the mid-Holocene. The decrease in incoming solar radiation in the mid-Holocene winter and spring caused stronger surface and tropospheric cooling in the northern low latitudes. It reduced the meridional temperature gradient in the troposphere, thereby weakening the westerly winds and related transport of water vapor. More importantly, the cooling weakened the local water cycle in ACA. Finally, the precipitation decreased over almost all of ACA. In the mid-Holocene summer (June–August), the meridional temperature gradient and related westerly winds were also reduced. It was mainly caused by stronger surface and tropospheric warming in the northern mid- to high latitudes. The stronger warming was due to increased summer incoming solar radiation in the mid-Holocene. This process differed from that occurred in winter and spring. Therefore, the water vapor transport was weakened, and the summer precipitation was deficient in northern ACA. At the same time, strengthened descending motions contributed to the decrease in summer precipitation in most Central Asia. On the contrary, intensified ascending motions increased summer precipitation in southeastern Xinjiang. 

How to cite: Wang, T., Xu, H., Jiang, D., and Yao, J.: Mechanisms of reduced mid-Holocene precipitation in arid central Asia as simulated by PMIP3/4 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7693, https://doi.org/10.5194/egusphere-egu24-7693, 2024.

EGU24-8885 | Orals | CL1.2.13 | Highlight

Multidecadal to multicentennial variability in Holocene transient simulations  

Pascale Braconnot and Olivier Marti

Transient Holocene climate simulations with state-of-the-art Earth system models offers new opportunities to investigate the relationship between multidecadal to multicentennial variability, the long-term climate trends, and interannual to decadal variability (Braconnot et al. GRL, 2019). However, multidecadal to multicentennial variability is still poorly known, both because it is difficult to properly extract from proxy records and because it is at the limit of what can actually be done with Earth System models. In addition, the different feedbacks from ocean or land-surface properties that can shape its characteristics are still poorly understood. Different climate models seem to provide different centennial variability patterns between the different ocean basins that reflect either the chaotic nature of the climate system or a poor representation of these variability scales. 

In this presentation, we will consider new mid-to-late Holocene simulations with the IPSL Earth System model, one of which includes interactive dynamical vegetation. We will first investigate the characteristics of multidecadal to multicentenial variability in these new simulations, with reference to recent publications comparing different transient Holocene simulations and addressing temperature variability scales, the thermohaline circulation, or Atlantic Ocean patterns leading to a reduction of the African monsoon interannual variability. We will also focus on key variability events that appear in the simulations and have a substantial impact on rapid changes in the African monsoon or on Northern Europe climate and land surface conditions (snow, soil moisture or vegetation). This opens the way to new research directions as part of the Paleoclimate Modeling Intercomparison Project.

How to cite: Braconnot, P. and Marti, O.: Multidecadal to multicentennial variability in Holocene transient simulations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8885, https://doi.org/10.5194/egusphere-egu24-8885, 2024.

EGU24-9788 | ECS | Orals | CL1.2.13 | Highlight

Large scale atmospheric circulation patterns in DeepMIP simulations 

Fanni Dora Kelemen, Niels Meijer, and Bodo Ahrens

Paleoclimate models help us understand the complex influence of high CO2 concentration and other boundary conditions on large scale atmospheric circulation patterns. Based on meridional heat transport analysis we investigate different phenomena, such as the Hadley cell, the monsoon and extratropical cyclones, in simulations from the Deep-Time Model Intercomparison Project (DeepMIP). For the analysis we compare preindustrial and early Eocene simulations at a range of CO2 levels (1x, 3x and 6x preindustrial values), which are targeting the climate of the Early Eocene Climatic Optimum (EECO; 53-49 Ma).

Meridional heat transfer analysis shows asymmetric changes due to rising CO2 concentrations in the northern and southern Hadley cells’, which we investigate further. In the DeepMIP simulations, the global monsoon systems transport more latent heat from the subtropics to the higher latitudes, which shows a more intensive hydrological cycle than in present day climate.  Though, the global area influenced by monsoons is smaller in the early Eocene than today due to the differences in paleogeography. Fossil pollen and isotopic records from the Paleocene-Eocene Thermal Maximum (PETM) from arid Central Asia show that rainfall temporarily doubled and that monsoon expanded into the continental interior during these extreme hyperthermal conditions. This is not well captured in the DeepMIP simulations and suggests that even more mechanisms strengthened the development of East Asian monsoon, such as orbital forcing and vegetation feedbacks, that should be considered in future simulations. At the midlatitudes, cyclones’ climatology was also likely different in the Eocene, especially over Eurasia, which was more fragmented, and marginal seas influenced the cyclogenesis through land-sea thermal contrast. The analysis identifies the processes that are affected by the Eocene boundary conditions and that are sensitive to the CO2 increase, which has high relevance to our future climate projections.

How to cite: Kelemen, F. D., Meijer, N., and Ahrens, B.: Large scale atmospheric circulation patterns in DeepMIP simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9788, https://doi.org/10.5194/egusphere-egu24-9788, 2024.

EGU24-11263 | Orals | CL1.2.13

The impact of mid Holocene Saharan greening on the Euro-Atlantic climate variability 

Marco Gaetani, Gabriele Messori, Francesco S.R. Pausata, Shivangi Tiwari, M. Carmen Alvarez Castro, and Qiong Zhang

During the first half of the Holocene (11,000 to 5,000 years ago) the Northern Hemisphere experienced a strengthening of the monsoonal regime, with climate reconstructions robustly suggesting a greening of the Sahara region. Paleoclimate archives also show that this so-called African Humid Period (AHP) was accompanied by changes in the climate conditions at mid to high latitudes. However, inconsistencies still exist in reconstructions of the mid-Holocene (MH) climate at mid-latitudes, and model simulations provide limited support to reduce these discrepancies. In this study, a set of simulations performed with an Earth System Model is used to investigate the hitherto unexplored impact of the Saharan greening on mid-latitude atmospheric circulation during the MH. Numerical simulations show a year-round impact of the Saharan greening on the main circulation features in the Northern Hemisphere, especially during boreal summer when the African monsoon develops. In particular, a westward shift of the global Walker Circulation leads to a modification of the North Atlantic jet stream. The Saharan greening also modifies the atmospheric synoptic circulation over the North Atlantic, changing the North Atlantic Oscillation phase from prevailingly positive to neutral-to-negative, and significantly modifying the occurrence of blocking events. This study provides a first constraint on the Saharan greening influence on northern mid-latitudes, indicating new opportunities for understanding the MH climate anomalies in the Euro-Atlantic sector.

How to cite: Gaetani, M., Messori, G., Pausata, F. S. R., Tiwari, S., Alvarez Castro, M. C., and Zhang, Q.: The impact of mid Holocene Saharan greening on the Euro-Atlantic climate variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11263, https://doi.org/10.5194/egusphere-egu24-11263, 2024.

EGU24-11691 | ECS | Posters on site | CL1.2.13

Development of the Isotope-enabled Fully Coupled Model MIROC6-iso 

Yifan Li, Alexandre Cauquoin, Atsushi Okazaki, and Kei Yoshimura

  Understanding Earth's climate is more important than ever, as it allows us to anticipate future changes and their potential impact on human society. The study of paleoclimate is crucial for understanding the mechanisms that have driven past climate variations, including natural oscillations, external forcings, and feedback processes within the Earth's climate system. Stable water isotopes (H218O and HD16O) can serve as tracers to analyze the origins of water vapor, precipitation, and cloud formation, thereby enhancing our understanding of evaporation, condensation, and precipitation processes.

  In order to understand coupled dynamics process, such as such as atmospheric convection/cloud formation, land surface processes, and sea ice effects according isotope insight, we developed an isotope-enabled fully coupled model(atmosphere-land-ocean coupled model), MIROC6-iso.

  MIROC6 is the newest version of the Model for Interdisciplinary Research on Climate (MIROC) series. MIROC6 has updated the physical parameterizations in all sub-modules and vertical resolution. The overall reproducibility of mean climate, internal climate variability, midlatitude atmospheric circulation and tropical climate systems in MIROC6 is better than that in MIROC5.

  Based on the AGCM MIROC6-iso to which stable water isotopes are implemented into the atmosphere and land-surface component[1], we implemented the stable water isotopes into the ocean and sea-ice component at first. Then, we make the atmosphere, land-surface, ocean and sea-ice component coupled and enabled them to interacted with each other.

  We performed the simulation under the preindustrial period (PI), corresponding to the climate conditions at 1850 CE. In the ocean component, we employed a spin-up process by separately running the ocean model COCO-iso from the  ocean component of the CGCM MIROC6-iso for 4000 years. This was done to establish initial conditions for the ocean part of CGCM MIROC6-iso, ensuring that the ocean component operates directly under equilibrium conditions.

 CGCM MIROC6-iso shows a good performance in simulating isotope ratios in precipitation. Additionally, we compared the d-excess of precipitation, as well as the isotopic delta values of the ocean surface and deep ocean. We also examined the relationship between the isotopic delta values and both temperature and sea surface salinity.

 CGCM MIROC6-iso may has many potential applications in climate analysis, such as analyzing the monsoon wind fields in monsoon cycles, as well as the coupled mechanisms of the atmosphere and ocean in ENSO, monsoon and so on. Then it can be used to analyse the climate of the past. We hope this new model could contribute to CMIP6/PMIP4.

[1] Okazaki, A., Li, Y., Kino, K., Cauquoin, A., and Yoshimura, K., Evaluation of a newly developed isotope-enabled AGCM MIROC6-iso under the present climate, AGU 2023, San Francisco (USA), December 2023.

How to cite: Li, Y., Cauquoin, A., Okazaki, A., and Yoshimura, K.: Development of the Isotope-enabled Fully Coupled Model MIROC6-iso, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11691, https://doi.org/10.5194/egusphere-egu24-11691, 2024.

EGU24-12117 | ECS | Posters on site | CL1.2.13

Quantifying the Australian monsoon since the Last Glacial Maximum using downscaled models 

Andrew Lowry and Hamish McGowan

The Australian continent spans tropical to extra-tropical latitudes with corresponding variety of temperature and precipitation. In the tropical north of Australia, the monsoon and resultant precipitation is critical for agriculture and human habitation. The timing of monsoon onset and duration of the monsoon season is therefore an essential piece of information for understanding the hydroclimate of northern Australia. The present-day monsoon onset, defined as the reversal of lower tropospheric winds, occurs on 24 December ± 15 days, and the average duration of the monsoon season is 80 days. The areal extent of the monsoon is also a critical aspect of the hydroclimate, with a poleward penetration of monsoon precipitation improving agricultural and habitation conditions.

The present day northern Australian monsoon has been widely studied. The palaeo-monsoon, however, has rarely been studied and never using downscaled climate models. Here we present the first results from such modelling of the timing of monsoon onset, duration, and extent for three time slice simulations: 6000 BP, 12000 BP, and 21000 BP. These results are compared to a pre-industrial control simulation (1850) and NCEP data for 1991 – 2021. The simulations were performed using the Weather Research and Forecasting (WRF) model, with initial and boundary conditions taken from the Community Earth System Model (CESM). Both models were adjusted for the appropriate greenhouse gas concentrations, insolation, and land-sea distribution.

How to cite: Lowry, A. and McGowan, H.: Quantifying the Australian monsoon since the Last Glacial Maximum using downscaled models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12117, https://doi.org/10.5194/egusphere-egu24-12117, 2024.

EGU24-12827 | Posters on site | CL1.2.13 | Highlight

Palaeo-conditioning a coupled climate model to reproduce the Holocene greening of the Sahara and the warm poles of the Eocene 

Peter Hopcroft, Paul Wilson, Anya Crocker, Chuang Xuan, and Paul Valdes

General circulation models (GCMs) often fail to reproduce two key aspects of palaeoclimate states: the Holocene Greening of the Sahara and the warm poles of the Early Eocene. These biases are systematic across many generations of GCMs and appear to be largely independent of model complexity or resolution. Recently, solutions to both problems have been proposed through changes to the ‘physics’ parameterisations in GCMs. These parameterisations are employed to approximate aspects such as clouds, convection and turbulence that are too complex or fine-scale to be represented directly. In this work we employ a perturbed parameter ensemble of coupled GCM simulations that samples uncertainty in these aspects for the pre-industrial, mid-Holocene and early Eocene. Our aim is to evaluate whether one model can reproduce two independent palaeoclimate states satisfactorily and thereby improve the performance of the model for future and other times in the past. We use the coupled GCM HadCM3B and perturb 19 model parameters relating to atmospheric convection, clouds, the land-surface and ocean mixing across >1000 ensemble members. We then use a statistical emulator to learn from the ensemble and palaeo-condition the parameter values based on constraints from observed climatology and mid-Holocene and Eocene climate reconstructions. We examine the compatibility of the two palaeoclimate states in terms of their optimal parameter values and evaluate whether the model can produce the Holocene green Sahara given different assumptions on the contribution of summer (monsoon) and/or winter (stormtrack) rainfall increases. Our results constitute a step towards a fully palaeo-conditioned GCM which can more reliably simulate out-of-sample past or future climate states.

How to cite: Hopcroft, P., Wilson, P., Crocker, A., Xuan, C., and Valdes, P.: Palaeo-conditioning a coupled climate model to reproduce the Holocene greening of the Sahara and the warm poles of the Eocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12827, https://doi.org/10.5194/egusphere-egu24-12827, 2024.

EGU24-13543 | Posters on site | CL1.2.13

A multi-model analysis of the PMIP LGM AMOC 

Sam Sherriff-Tadano, Marlene Klockmann, Hidetaka Kobayashi, Marie Kapsch, Bo Liu, Ruza Ivanovic, and Ayako Abe-Ouchi

Simulating and reproducing the past Atlantic meridional overturning circulation (AMOC) with comprehensive climate models are essential to test the ability of models to simulate different climates. At the Last Glacial Maximum (LGM), reconstructions show a shoaling of the AMOC compared to modern climate. However, almost all state-of-the-art climate models simulate a deeper LGM AMOC. Here, we conduct a multi-model analysis using outputs from all PMIP phases (PMIP2 to PMIP4) to consistently explore the causes of this paleodata-model mismatch. The analysis focuses on the role of sea-surface temperature biases in the piControl simulation as well as changes in ocean temperature, salinity and density in each oceanic basin. We further compare the deepwater formation regions in each model and explore potential implications on the interpretation of paleodata-model comparison.

How to cite: Sherriff-Tadano, S., Klockmann, M., Kobayashi, H., Kapsch, M., Liu, B., Ivanovic, R., and Abe-Ouchi, A.: A multi-model analysis of the PMIP LGM AMOC, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13543, https://doi.org/10.5194/egusphere-egu24-13543, 2024.

EGU24-13780 | ECS | Posters on site | CL1.2.13

Multi-model assessment of the deglacial climatic evolution at high southern latitudes  

Takashi Obase, Laurie Menviel, Ayako Abe-Ouchi, Tristan Vadsaria, Ruza Ivanovic, Brooke Snoll, Sam Sherriff-Tadano, Paul Valdes, Lauren Gregoire, Marie-Luise Kapsch, Uwe Mikolajewicz, Nathaelle Bouttes, Didier Roche, Fanny Lhardy, Chengfei He, Bette Otto-Bliesner, Zhengyu Liu, and Wing-Le Chan

The quaternary climate is characterised by glacial-interglacial cycles, with the most recent transition from the last glacial maximum to the present interglacial (the last deglaciation) occurring between ~ 21 and 9 ka. While the deglacial warming at southern high latitudes is mostly in phase with atmospheric CO2 concentrations, some proxy records have suggested that the onset of the warming occurred before the CO2 increase. In addition, southern high latitudes exhibit a cooling event in the middle of the deglaciation (15–13 ka) known as the Antarctic Cold Reversal (ACR). In this study, we analyse transient simulations of the last deglaciation performed by six different climate models as part of the 4th phase of the Paleoclimate Modelling Intercomparison Project (PMIP4) to understand the processes driving southern high latitude surface temperature changes. While proxy records from West Antarctica and the Pacific sector of the Southern Ocean suggest the presence of an early warming before 18 ka, only half the models show a significant warming (~1 °C or ~10 % of the total deglacial warming). All models simulate a major warming during Heinrich stadial 1 (HS1, 18–15 ka), greater than the early warming, in response to the CO2 increase. Moreover, simulations in which the AMOC weakens show a more significant warming during HS1 as a result. During the ACR, simulations with an abrupt increase in the AMOC exhibit a cooling in southern high latitudes, while those with a reduction in the AMOC in response to rapid meltwater exhibit warming. We find that all climate models simulate a southern high latitude cooling in response to an AMOC increase with a response timescale of several hundred years, suggesting the model’s sensitivity of AMOC to meltwater, and the meltwater forcing in the North Atlantic and Southern Ocean affect southern high latitudes temperature changes. Thus, further work needs to be carried out to understand the deglacial AMOC evolution with the uncertainties in meltwater history. Finally, we do not find substantial changes in simulated Southern Hemisphere westerlies nor in the Southern Ocean meridional circulation during deglaciation, suggesting the need to better understand the processes leading to changes in southern high latitude atmospheric and oceanic circulation as well as the processes leading to the deglacial atmospheric CO2 increase.

How to cite: Obase, T., Menviel, L., Abe-Ouchi, A., Vadsaria, T., Ivanovic, R., Snoll, B., Sherriff-Tadano, S., Valdes, P., Gregoire, L., Kapsch, M.-L., Mikolajewicz, U., Bouttes, N., Roche, D., Lhardy, F., He, C., Otto-Bliesner, B., Liu, Z., and Chan, W.-L.: Multi-model assessment of the deglacial climatic evolution at high southern latitudes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13780, https://doi.org/10.5194/egusphere-egu24-13780, 2024.

EGU24-14156 | ECS | Orals | CL1.2.13

Detection of tropical Pacific Ocean mean state changes between the LGM and Holocene 

Alicia Hou, Lukas Jonkers, and Sze Ling Ho

The tropical Pacific Ocean can oscillate between different mean states, characterized by distinct upper ocean configurations. As these mean state shifts can have global climatic impacts, it is crucial to understand how they respond to global-scale forcing, particularly greenhouse gas (GHG) concentrations. Proxy- and model-based paleoclimate studies typically use a set of mean state indices, including the east-west sea surface temperature (SST) gradient, equatorial thermocline tilt, etc. for reconstructing orbital and glacial-interglacial tropical Pacific Ocean mean-state changes. However, it remains unclear whether these mean state diagnostics commonly adopted in paleoclimate studies are robust and can be observed in instrumental data. To this end, we first used ARGO data to critically examine how these indices behave in response to the shift from El Niño to La Niña conditions (i.e., two modern-day mean state end-members). Next, we used compiled proxy records and an ensemble of climate models from PMIP 3 and 4 to detect mean state changes between the LGM and Holocene, two past climate periods with markedly different GHG levels.  

The computed LGM and Holocene mean state diagnostics reveal numerous proxy-model discrepancies, most notably in the eastern equatorial cold tongue (EECT). While proxies suggest that LGM SST cooling in the EECT was minimal and subsurface temperatures (SubTs) warmed, models show no evidence of reduced SST cooling nor SubT warming. As such, the proxy-derived LGM tropical Pacific mean state is characterized by reduced zonal SST and SubT gradients compared to the Holocene, whereas models show no significant glacial-interglacial differences. In line with previous proxy-based studies, we attribute the subdued SST cooling and SubT warming signals in the proxy data as strong indications that the effects of radiative cooling in the EECT are counteracted by dynamic processes such as upwelling, Intertropical Convergence Zone migrations, etc. Since model results indicate a direct upper ocean response in the EECT to glacial GHG reduction, we suggest that none of the models are capable of realistically simulating the dynamic processes operating in the EECT.

Both proxies and models indicate that the shift from LGM to Holocene climatic conditions produced zonally symmetrical upper ocean changes in the tropical Pacific. This differs from the distinctive zonally asymmetrical upper ocean responses during the shift from El Niño to La Niña conditions. Thus, our findings demonstrate that it is inappropriate to use modern-day El Niño-Southern Oscillation dynamics to explain glacial-interglacial changes in tropical Pacific mean state. We note that the modelled regionally-averaged indices of tropical Pacific Ocean mean state are associated with exceptionally large spatial variabilities, such that it is nearly impossible to detect mean state differences between the LGM and Holocene. This indicates the need to use higher resolution regional models to elucidate regional-scale signals.

How to cite: Hou, A., Jonkers, L., and Ho, S. L.: Detection of tropical Pacific Ocean mean state changes between the LGM and Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14156, https://doi.org/10.5194/egusphere-egu24-14156, 2024.

EGU24-15867 | ECS | Posters on site | CL1.2.13

Objective tuning of an EMIC using present-day observations and Last Glacial Maximum climate reconstructions 

Muriel Racky, Felix Pollak, Elisa Ziegler, Nils Weitzel, and Kira Rehfeld

Climate models rely on parametrizations of unresolved Earth system processes. These often include uncertain parameters that are estimated in a procedure called tuning, where the model output is optimized with respect to selected climate observations. Most models are tuned against present-day observations. However, if the parametrizations robustly represent the underlying physics, a tuned set of model parameters should be valid independent of the simulated climate, including climate states very different from present-day such as the Last Glacial Maximum (LGM).

Here, we present the procedure for and the results of an iterative Bayesian tuning of PlaSim-LSG, an Earth system model of intermediate complexity (EMIC). Its low computational cost allows for long simulation periods and large ensembles. For a preliminary tuning restricted to observational information from recent decades, we find a less realistic LGM state of the Atlantic Meridional Overturning Circulation (AMOC) and sea ice distribution than in the default model version. This could imply that tuning based only on present-day observations might be insufficient to target significantly colder climates such as the LGM. However, prior sensitivity studies have shown that PlaSim-LSG is capable of simulating a wide range of AMOC states under varying ocean diffusivity parameters and handling of freshwater runoff. Therefore, we redefine tuning targets, combining present-day observations with LGM climate reconstructions. We investigate how the weighting of the different climate state metrics in the tuning target impacts the resulting present-day and LGM climates. The goal of this exploratory approach is to test parameter sensitivity and identify state-dependent parameters. This could be used in the future to inform model development decisions by focusing on improving parametrizations with highly state-dependent parameters.

How to cite: Racky, M., Pollak, F., Ziegler, E., Weitzel, N., and Rehfeld, K.: Objective tuning of an EMIC using present-day observations and Last Glacial Maximum climate reconstructions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15867, https://doi.org/10.5194/egusphere-egu24-15867, 2024.

EGU24-16340 | ECS | Posters on site | CL1.2.13

Deglacial AMOC sensitivity in freshwater hosing experiments using CESM 

Dragan Latinovic, Ute Merkel, and Matthias Prange

The last deglaciation is characterized by a sequence of abrupt climate events, with melting ice sheets as its most distinctive feature. By meltwater release, ice sheets affect the oceanic circulation and modulate the Atlantic Meridional Overturning Circulation (AMOC). Understanding the stability of the AMOC under deglacial boundary conditions is therefore of vital importance for a better understanding of the climate trajectory from the Last Glacial Maximum (LGM) to the Holocene. To this end, we explore the impact of different glacial/deglacial boundary conditions (greenhouse gas concentrations (GHG), orbital parameters, ice-sheet topography) on the stability of the AMOC in freshwater hosing experiments using the Earth system model CESM1.2. This study is part of coordinated activities within the German climate modeling initiative (PalMod). For this purpose, three different configurations with various combinations of boundary conditions are used: (i) Full 15.2 ka boundary conditions, (ii) 15.2 ka boundary conditions except for LGM GHG, and (iii) LGM boundary conditions with 15.2 ka ice-sheet topography. After initial spin-up model integrations (3000-4000 years), freshwater hosing (0.1 Sv and 0.2 Sv; 400-700 years) is performed to each experiment, in which the AMOC is perturbed in the ice-rafted debris belt in the Northern Atlantic Ocean (40°N–55°N, 45°W–20°W). We find that the AMOC is most stable with respect to hosing under full 15.2 ka boundary conditions. Under reduced (LGM) GHG forcing, the AMOC becomes more unstable and collapses with only 0.1 Sv of freshwater hosing. Under certain conditions (15.2 ka boundary conditions with 0.1 Sv hosing) the AMOC exhibits bistability. Abrupt recovery along with an overshoot of the AMOC after removal of the hosing resembles Bølling/Allerød (B/A) warming by its intensity and duration. Finally, spontaneous (unhosed) millennial-scale AMOC oscillations are found under LGM boundary conditions with 15.2 ka ice-sheet topography. In sum, our set of experiments indicates that the deglacial AMOC evolution was the result of a non-linear complex interplay between different forcing factors rather than a simple (linear) response to meltwater forcing.

How to cite: Latinovic, D., Merkel, U., and Prange, M.: Deglacial AMOC sensitivity in freshwater hosing experiments using CESM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16340, https://doi.org/10.5194/egusphere-egu24-16340, 2024.

EGU24-17050 | Orals | CL1.2.13

Impact of vegetation cover on interglacial climates 

Matthias Prange

Quaternary interglacials show varying amplitudes and different patterns of changes in climate and vegetation cover. A better understanding of these changes requires deeper insight into the mechanisms by which climate and vegetation interact. Using the Earth system model CESM1.2, the present study assesses the role of Northern Hemisphere vegetation changes in shaping the global climate for different interglacial warm intervals: the mid Holocene (MH; 6 ka), the Last Interglacial (LIG; 127 ka), and Marine Isotope Stage 11 (MIS 11; 409 ka). The model allows the prognostic and interactive simulation of leaf and stem area indices and vegetation height, while the vegetation biogeography is fixed (“semi-dynamic vegetation”). In accordance with previous studies, we find that the simulated interglacial climates turn out to be too cold compared to reconstructions. Relative to the pre-industrial (PI) control run, the annual global mean surface air temperature (SAT) is 0.3 K colder in the MH, 0.1 K colder at the LIG and unchanged at the MIS 11 time slice. Strongest warming is found above the Arctic Ocean, where the model simulates a mean annual SAT increase by up to 3 K for the MH, up to 7 K for the LIG, and up to 6 K for MIS 11. Applying changes in the vegetation cover, which more realistically represent the biogeography of the interglacial time slices (including expansion of vegetation over North Africa and in the northern hemisphere mid and high latitudes), has crucial impact on the global interglacial climates. Over Siberia, annual mean SAT increases by 2-3 K in all interglacial experiments compared to PI. Globally, the MH becomes 0.4 K warmer, the LIG becomes 0.6 K warmer, and the MIS 11 becomes 0.8 K warmer relative to PI. Polar amplification is much more pronounced after applying the vegetation changes, with an annual mean warming of 5-6 K over the Arctic Ocean at the MH, up to 9 K at the LIG, and 7-8 K at MIS 11. The large polar temperature changes during the LIG are associated with a seasonally ice-free Arctic Ocean. The vegetation changes also impact the interglacial atmospheric water cycles, most pronounced in Northern Hemisphere monsoon regions. In particular, the West African monsoon is substantially amplified in response to the expansion of vegetation. Physical processes causing these changes are analyzed. In summary, the results suggest that the intricate interplay between climate and vegetation stands as one of the fundamental mechanisms shaping the dynamics of past interglacials, which needs to be more carefully addressed in future model studies.

How to cite: Prange, M.: Impact of vegetation cover on interglacial climates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17050, https://doi.org/10.5194/egusphere-egu24-17050, 2024.

EGU24-17530 | ECS | Orals | CL1.2.13

Transient atmosphere-ocean-carbon simulations through the Penultimate Deglaciation and Last Interglacial 

Tim Cutler, Philip Holden, Neil Edwards, and Pallavi Anand

The Penultimate Deglaciation saw climatic warming from a glacial state into the Last Interglacial, which saw warmer-than-preindustrial temperatures and extreme northern hemisphere monsoons. Here a fast, intermediate-complexity 3D dynamic atmosphere-ocean model is used to study the Atlantic Meridional Overturning Circulation (AMOC), Indian and Southeast Asian Summer Monsoons and the carbon cycle during the Penultimate Deglaciation and Last Interglacial in steady state and transient simulations between 140,000 and 122,000 years before present. We find two weak phases of AMOC, the second longer than the first. Indian Summer Monsoon starts in a weak state and reaches a maximum around 127,000 years ago (where northern summer insolation is at a maximum) before declining. The Southeast Asian Monsoon displays smaller changes and an earlier peak. The timing of AMOC collapse and recovery is strongly affected by choice of freshwater forcing timeseries. Sensitivity experiments where individual forcings are varied, find that the timing of AMOC recovery is further influenced by precession, and by ice sheet retreat independent of meltwater flux. Indian monsoon strengthening is mainly driven by precession, with further contribution from CO2, obliquity and the timing of AMOC recovery. Transient simulations find later warming compared to steady state experiments. Experiments with freely evolving CO2 fail to replicate ice core-inferred deglacial CO2 increase.

How to cite: Cutler, T., Holden, P., Edwards, N., and Anand, P.: Transient atmosphere-ocean-carbon simulations through the Penultimate Deglaciation and Last Interglacial, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17530, https://doi.org/10.5194/egusphere-egu24-17530, 2024.

EGU24-17867 | ECS | Posters on site | CL1.2.13

Surface air temperature response to strong volcanic clusters in the Last Glacial Maximum 

Deepashree Dutta, Peter Hopcroft, Thomas Aubry, and Francesco Muschitiello

Stratospheric aerosol injection from volcanic eruptions results in a complex set of responses driving climate effects across various time and spatial scales. However, the physical mechanisms through which volcanic forcing causes long-term global and regional cooling remain insufficiently examined. In particular, the climate feedbacks and responses to a cluster of strong volcanic eruptions that occurred pre-Holocene are still poorly quantified. We examine the cooling potential of volcanic clusters and assess the short- and long-term memory of regional and global climatic variability using a suite of idealised volcanic forcing experiments with the Hadley Centre Coupled Model, version 3. We compare the responses to Northern Hemisphere high and low latitude volcanic clusters and the impact of different boundary conditions. We find a largely similar surface air temperature response to low and high latitude volcanic clusters. Individual volcanic eruptions lead to a global mean surface air temperature cooling of approximately 0.5°-1.5°C, and this cooling appears to increase after successive eruptions. We also investigate changes in the coupling between northward heat transport, Arctic sea ice, and the Atlantic Meridional Overturning Circulation caused by the volcanic forcing.

How to cite: Dutta, D., Hopcroft, P., Aubry, T., and Muschitiello, F.: Surface air temperature response to strong volcanic clusters in the Last Glacial Maximum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17867, https://doi.org/10.5194/egusphere-egu24-17867, 2024.

EGU24-19637 | ECS | Orals | CL1.2.13 | Highlight

Simulating high-resolution climate over East Asia for the Last Glacial Maximum utilising the pseudo-global warming approach 

Ruolan Xiang, Christian R. Steger, and Christoph Schär

To better understand the landscape dynamics and changes in habitat connectivity influenced by glacial and interglacial oscillations over the biodiversity-rich Hengduan Mountains (HM) region, located at the south-eastern edge of the Tibetan Plateau (TP), high-resolution climate data for past periods are essential. We apply the non-hydrostatic limited-area model COSMO with a resolution of 12 km over East Asia for the Last Glacial Maximum (LGM), a period characterized by a generally colder and dryer climate compared to present-day conditions. We perform the downscaling with a novel approach for paleoclimate modelling, the Pseudo-Global Warming (PGW) method. The PGW method minimizes Global Climate Models' (GCMs') inherent biases and reduces computational demands. Despite its widespread use in future climate downscaling, this study represents the first application of the PGW method for paleoclimate simulation to our knowledge. The COSMO PGW simulation for the LGM shows that the regional climate model (RCM) replicates the large-scale dynamics of the driving GCM simulation in the colder climate. Both models suggest weaker Asian summer monsoon systems for this period. Consequently, regions such as the Bay of Bengal, the South China Sea, and the coastal region of China, which typically receive substantial monsoon rainfall, experienced significantly reduced precipitation. However, besides these model similarities, the high-resolution COSMO simulation exhibits distinctive differences on a smaller scale for variables like near-surface wind and precipitation — particularly over land. For instance, COSMO suggests a more significant southward shift of the jet stream during the LGM winter, with more pronounced annual cooling and a prolonged Meiyu season in southern China. Moreover, the COSMO simulation features increased LGM precipitation amounts for the majority of the HM despite the overall weaker summer monsoon circulation. Regarding snowfall, which is a crucial factor for the glaciation extent of the TP during LGM, COSMO suggests increases for certain sub-areas (e.g., central TP) during all seasons, while in the GCM, the increase is primarily constrained to summer and limited to a smaller region near the Himalayas. Furthermore, evaluation with proxy data indicates an improved representation of local climate by COSMO for specific regions. Our study suggests that the resource-saving PGW approach is a suitable method to bridge the gap between coarser climate data and regional climate impacts, also for past periods like the LGM.

How to cite: Xiang, R., Steger, C. R., and Schär, C.: Simulating high-resolution climate over East Asia for the Last Glacial Maximum utilising the pseudo-global warming approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19637, https://doi.org/10.5194/egusphere-egu24-19637, 2024.

EGU24-19737 | Posters on site | CL1.2.13

Dynamic Lake Modelling for Coupled Climate Model Simulations of the Last Glacial Cycle 

Thomas Riddick and Thomas Kleinen

The continually evolving large ice sheets present in the Northern Hemisphere during the last glacial cycle caused significant changes to drainage pathways both through directly blocking rivers and through glacial isostatic adjustment. These changing drainage pathways drove the formation, evolution and (sometimes catastrophic) drainage of large glacial lakes such as Lake Agassiz. Studies have shown this changing hydrology had a significant impact on the ocean circulation through changing the pattern of freshwater discharge into the oceans. A coupled Earth system model simulation of the last glacial cycle thus requires a lake model that uses a set of river pathways and lakes that evolve with Earth's changing orography. Here, we present a method for dynamically modelling lakes (building on previous work on dynamically modelling rivers) by applying predefined corrections to an evolving fine-scale orography (accounting for the changing ice sheets and isostatic rebound) each time the river directions and lakes basins are recalculated. The lakes are delineated from this corrected fine scale orography and water level within each lake is modelled within the JSBACH land surface model. Lake inflow and outflow are linked to the existing river flow model within JSBACH while evaporation from the lake surface is linked to the ECHAM atmospheric general circulation model.

How to cite: Riddick, T. and Kleinen, T.: Dynamic Lake Modelling for Coupled Climate Model Simulations of the Last Glacial Cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19737, https://doi.org/10.5194/egusphere-egu24-19737, 2024.

EGU24-20074 | Posters on site | CL1.2.13

The water isotope signature for the Last interglacial in three water isotope enabled climate models. 

Rahul Sivankutty, Louise Sime, Alexandre Cauquoin, Martin Werner, Allegra N.LeGrande, Sentia Goursaud, and Irene Malmierca Vallet

The stable water isotope ratios of water trapped in polar ice cores have been used to make inferences about temperatures and precipitation of the past.  Coupled climate models with the capability to simulate these stable water isotopes and their distribution throughout the hydrological cycle, are a valuable tool to help us understand the relationship between the isotopic signature and the climate state.  Here we compare the Last interglacial (LIG) climate and the isotopic signature simulated by three models with embedded water isotope diagnostics (ECHAM6, NASA-GISS and HadCM3). We look at these model's ability to simulate polar climate, both Arctic and Antarctic, and show how the isotope signature compares with available ice core estimates. All the models simulate a warming and heavier precipitation in Arctic for the LIG, compared to their corresponding preindustrial control simulations. There are however differences in the magnitude and pattern of these changes. In Antarctica, there are considerable differences in PI to LIG warming and precipitation patterns between models. We decompose the δ18O changes, showing that the impact of seasonality changes in precipitation on δ18O are similar in the models. However, changes in δ18O due to other changes, particularly those driven by source impacts including sea ice changes, are more variable between the models. Finally, we analyse LIG North Atlantic water hosing experiments run using HadCM3. A 0.25Sv hosing in the North Atlantic leads to a shutdown of Atlantic meridional overturning circulation. This prevents North Atlantic heat loss and leads to a warmer Antarctica. The δ18O signature in these hosed runs has a closer match to the ice core observations, compared to the standard (non-hosed) LIG simulation.

How to cite: Sivankutty, R., Sime, L., Cauquoin, A., Werner, M., N.LeGrande, A., Goursaud, S., and Malmierca Vallet, I.: The water isotope signature for the Last interglacial in three water isotope enabled climate models., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20074, https://doi.org/10.5194/egusphere-egu24-20074, 2024.

EGU24-20613 | Posters on site | CL1.2.13

Precessional effects on West Africa summer monsoon intensity and duration 

Xiaoxu Shi, Hu Yang, Jiping Liu, Gerrit Lohmann, and Martin Werner

The changes of summer monsoon precipitation over West Africa has been well documented for the past climate. However, the specific changes in the onset, withdrawal, and duration of the WASM have not been explored extensively due to the lack of high temporal resolution reconstructions.

Solar insolation, which reaches its maximum during boreal summer, acts as the primary energy source for the monsoon system. The precession of Earth's orbit regulates the occurrence of perihelion and aphelion and the length of the summer season. To examine the role of precession on the WASM, we conducted 24 time-slice simulations, altering the precession angle from 0° to 345° with a 15° interval.

Using simulated daily precipitation for West Africa, we analyzed the intensity, onset, withdrawal, and duration of the summer monsoon in our model study. Our findings reveal that precession has a significant influence on the intensity and duration of the WASM. Generally, during the northern summer, if Earth is closer to perihelion, the WASM tends to be stronger but shorter. Conversely, if Earth is closer to aphelion, the WASM is weaker but has a longer duration.

These results emphasize the importance of considering the orbital effect on the WASM intensity and duration over a precessional cycle.

How to cite: Shi, X., Yang, H., Liu, J., Lohmann, G., and Werner, M.: Precessional effects on West Africa summer monsoon intensity and duration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20613, https://doi.org/10.5194/egusphere-egu24-20613, 2024.

The aim of this study is to analyze the past climate over the Arabian Peninsula and the changes which will influence the future climate change. This study will focus on the Holocene climate over the Arabian Peninsula, that began 11,700 years ago. In this study the ensemble simulations of the LOVECLIM coupled model is used considering that the model proven to be the best concurrence with the reconstructions. LOVECLIM 1.2 model includes the atmosphere component is ECBilt2, the ocean and see ice component is CLIO3, the continental biosphere component land surface VECODE, the oceanic carbon cycle component LOCH, and the polar ice sheet component AGISM. LOVECLIM 1.2 simulate the present climate conditions and the last 20 millennia, the Last Glacial Maximum and the Holocene climate. The model used to simulate temperatures and precipitations in the Last Glacial Maximum and the Holocene climate over the Arabian Peninsula. The model outcomes indicate that high amount of precipitation occurred over the central region of  the Arabian Peninsula during the mid Holocene. The fluctuation of the Indian monsoon and the shift of the intertropical convergence zone (ITCZ) plays huge part on participation over the Arabian Peninsula.

How to cite: Alsarraf, H.: Using Paleoclimate modeling to analyse the precipitations and temperatures during the Holocene over the Arabian Peninsula, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21638, https://doi.org/10.5194/egusphere-egu24-21638, 2024.

EGU24-892 | ECS | Orals | CL1.2.14 | Highlight

Mid-Holocene environmental change in the Central Highlands of Madagascar: pre- and post-human settlement 

Andriantsilavo Hery Isandratana Razafimanantsoa, William Bond, and Lindsey Gillson

The climate in the tropic is favourable for forest development and the presence of open and mosaic ecosystems in this region lead to confusion and controversies. The Central Highlands of Madagascar is dominated by a matrix of grassland with forest patches, but whether these open ecosystems are ancient or anthropogenically derived is still scientifically debated. Understanding the landscape history including vegetation history and its drivers of change is therefore required to identify the nature and origin of the vegetation particularly prior to and after human settlement to inform appropriate conservation and management plans in the region. Here we provide a high-resolution environmental reconstruction of the last 6300 years from a sediment core collected at a lake called Dangovavy from the Central Highlands. Pollen and stable carbon isotopes were used to reconstruct vegetation history, while charcoal and coprophilous spores were used for fire frequency and herbivory activities, respectively. The data showed that open and mosaic ecosystems comprising forest patches of variable extent in a matrix of open montane grassland and ericoid shrubland occupied the area surrounding the lake from at least 6000 years ago, i.e. 4000 years before human settlement suggested around 2 cal. ka BP. Variations in forest extent and montane possibly C3–dominated grassland were recorded until 1 cal. ka BP., associated with fluctuations in fire, herbivory and rainfall. However, an expansion of the grassland ecosystem supported by C4 plant dominance, as shown in the stable carbon isotopes (δ13C) results, was recorded in the last millennium. This change was also associated with highly increasing fire frequency and herbivory activities most likely linked to human influence. Based on these findings, the natural presence of open and mosaic ecosystems in the Central Highlands of Madagascar should be considered, as well as their validity as conservation targets other than closed forests.

How to cite: Razafimanantsoa, A. H. I., Bond, W., and Gillson, L.: Mid-Holocene environmental change in the Central Highlands of Madagascar: pre- and post-human settlement, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-892, https://doi.org/10.5194/egusphere-egu24-892, 2024.

The Holocene temperature conundrum, marked by inconsistencies between proxy-based reconstructions and transient model simulations, challenges our understanding of Holocene temperature evolution. Reconstructions suggest a cooling trend after the Holocene Thermal Maximum, while model simulations indicate a consistent warming trend due to ice-sheet retreat and rising greenhouse gas concentrations. Various factors, such as seasonal biases and overlooked feedback processes, have been proposed as potential causes for this discrepancy. In this study, we found the impact of vegetation-climate feedback on temperature anomaly patterns in East Asia during the mid-Holocene (6000 BP). By utilizing the fully coupled Earth system model EC-Earth and performing simulations with and without coupled dynamic vegetation, we aim to isolate the influence of vegetation changes on regional temperature patterns. Our findings reveal that vegetation-climate feedback contributed to warming across most of East Asia, resulting in spatially diverse temperature changes during the mid-Holocene and significantly enhanced the model-data agreement. These results highlight the crucial role of vegetation-climate feedback in addressing the Holocene temperature conundrum and emphasize its importance for simulating accurate climate scenarios.

How to cite: Chen, J.: Reconciling East Asia's mid-Holocene temperature discrepancy through vegetation-climate feedback, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4255, https://doi.org/10.5194/egusphere-egu24-4255, 2024.

EGU24-4602 | Orals | CL1.2.14 | Highlight

Fire's legacy: unraveling long-term fire regime and grass-tree interactions in European temperate grassy ecosystems 

Angelica Feurdean, Diana Hanganu, and Andrei Cosmin Diaconu

Grass-dominated ecosystems, encompassing steppe, forest-steppe, savanna, woodlands, and shrublands, cover approximately 40% of the global land surface and are critical for biodiversity, carbon storage, livelihoods, and culture. Grassland ecosystems are often assumed to be dominant in regions that are too cold or dry for tree growth and have limited soil development. Many grassy ecosystems are, however, found in warm and wet climates that could support forests. This pattern may be explained by grassy ecosystems also maintained by consumers of biomass, such as fire and herbivores, which tip the competitive balance in favor of grasses. Central Eastern Europe hosts some of the largest expanses of open ecosystems, notably steppe and forest-steppe woodlands, which humans have heavily impacted for millennia. Despite the critical roles fire may have had in these landscapes, our understanding of grassland fire frequency and intensity relies on contemporary ecological studies and remote sensing. The few long-term fire regime reconstructions worldwide based on charcoal records in grasslands have revealed that many assumptions about fires in grassy ecosystems rely on extrapolations from forested environments, revealing gaps in our knowledge regarding the natural occurrence and intensity of fires to climate, vegetation composition, and biomass dynamics in grassy ecosystems. To address these gaps, we conducted palaeoecological analyses, including pollen, charcoal morphologies, and morphometrics (L/W), in two contrasting grassy ecosystems in south-eastern Romania—Lake Oltina in the forest-steppe and Mangalia Herghelie in the steppe. Our research aims are to explore: i) the variation in biomass burning, fire frequency, and severity of fire over time in response to climate, vegetation changes, and human activities; ii) to compare trends in fire regime between ecosystems with (forest-steppe) and without (steppe) tree cover; and ii) to assess deviations in modern fire regimes from long-term trends. Additionally, we examine charcoal morphological and morphometrical assemblages as signals for reconstructing vegetation composition changes in regions with poor pollen preservation. Our analysis seeks to unravel the intricate interactions and feedback among fire, climate, and vegetation dynamics. Frequent fires in grass-dominated ecosystems act as a bottleneck for tree recruitment, sustaining the dominance of grasslands. We hypothesize that fire activity increases with decreasing rainfall but decreases with increasing rainfall, potentially influencing the transition from steppe to forest-steppe to woodland. The fire regime characteristics are expected to change during this transition, with decreasing fire frequency and increasing severity due to elevated fuel loads and reduced flammable grasses. In the long term, this may lead to a shift towards a landscape dominated by woody vegetation, accompanied by lower frequency but higher severity fires. Human ignitions and the use of fire for land management alter these dynamics. Insights from this feedback and interaction will guide us in identifying thresholds in tree cover as indicators for a fire regime shift and determining tipping points in the balance between vegetation and fire. This study adds valuable knowledge to refine our understanding of the nuanced interplay between fire, climate, and vegetation dynamics in temperate European grasslands.

How to cite: Feurdean, A., Hanganu, D., and Diaconu, A. C.: Fire's legacy: unraveling long-term fire regime and grass-tree interactions in European temperate grassy ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4602, https://doi.org/10.5194/egusphere-egu24-4602, 2024.

EGU24-6575 | ECS | Posters virtual | CL1.2.14

Vegetation and Climate Patterns of Western Türkiye since the Late Glacial Period Based on Pollen Records in the Aegean Sea 

Mesut Kolbüken, Demet Biltekin, Ali Engin Aksu, Richard Hiscott, Bülent Arıkan, and Nurettin Yakupoğlu

Pollen analysis of the MAR03-02 core from the Aegean Sea (38°03.97'N, 26°22.30'E), western Türkiye allows us to reconstruct paleo-vegetation patterns and paleo-climate dynamics of the surrounding territory since the Late Glacial Period. We present palynological record from the topmost 2.8 m of a sediment core (MAR03-02) collected in the Aegean Sea, covering the last 20.7 ka. Variation in Mediterranean/temperate forests and herb/step plants indicates major climatic shifts connected to Heinrich Stadial 1, Bølling-Allerød, Younger Dryas, and the Holocene Climatic Optimum as well as some Rapid Climate Changes such as the 9.4, 8.2 and 5.9 ka events, Medieval Warm Period and Little Ice Age during the Holocene. In the cold and dry periods, low Arboreal Pollen (AP) and high amounts of herbaceous and steppe plants, including Artemisia, Cyperaceae, and Asteraceae Chichorioideae were recorded.  In warmer periods, high AP which was mainly characterized by deciduous Quercus, and low herbaceous/steppe plants dominated in the region. A warm-temperate and Mediterranean trees, consisted of mainly deciduous Quercus and Quercus ilex-type, reached the maximum level from the onset of the Holocene to 6 ka, which corresponded to the Holocene Climate Optimum. The pollen records show similarities with regional proxy records. Anthropogenic impacts occurred clearly during the last 2 ka when cultivated plants become prominent in the pollen records (e.g. Olea europea and Pistacia).

How to cite: Kolbüken, M., Biltekin, D., Aksu, A. E., Hiscott, R., Arıkan, B., and Yakupoğlu, N.: Vegetation and Climate Patterns of Western Türkiye since the Late Glacial Period Based on Pollen Records in the Aegean Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6575, https://doi.org/10.5194/egusphere-egu24-6575, 2024.

EGU24-6612 | ECS | Orals | CL1.2.14 | Highlight

Eco-evolutionary Modelling of Global Vegetation Dynamics and the Impact of CO2 during the late Quaternary: Insights from Contrasting Periods  

Jierong Zhao, Sandy P.Harrison, and Iain Colin Prentice

Changes in climate have had a significant impact on global vegetation patterns during the Quaternary. However, variations in CO2 levels also play a key role in shaping vegetation dynamics by influencing plant water-use efficiency, and consequently, the competitive success of employing the C3 and C4 photosynthetic pathways. In this study, we use an eco-evolutionary optimality (EEO) based modelling approach to examine the respective impacts of climate fluctuations and CO2-induced alterations on vegetation shifts. We consider two distinct periods, the Last Glacial Maximum (LGM, 21,000 years before present) and the mid-Holocene (MH, 6,000 years before present) and compare these to contemporary conditions. The LGM, characterised by generally colder and drier climate, had a CO2 level close to the minimum threshold for effective C3 plant operation. In contrast, the MH had warmer summers, increased monsoonal rainfall in the northern hemisphere, with CO2 levels lower than the present day. We simulate vegetation changes at the LGM and the MH using a light-use efficiency model that simulates gross primary production (GPP) coupled to an EEO model that simulates leaf area index (LAI) and C3/C4 competition. We show that low CO2 at the LGM is as important as climate in reducing tree cover, increasing the abundance of C4 plants and lowering GPP. Global GPP is also lower than today in the MH (although increased compared to the LGM), reflecting CO2 constraints on plant growth despite the positive impacts of warmer and/or wetter climates experienced in the northern hemisphere and tropical regions on plant growth. These results emphasise the importance of taking account of impacts of changing CO2 levels on plant growth in order to simulate ecosystem changes correctly.

How to cite: Zhao, J., P.Harrison, S., and Prentice, I. C.: Eco-evolutionary Modelling of Global Vegetation Dynamics and the Impact of CO2 during the late Quaternary: Insights from Contrasting Periods , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6612, https://doi.org/10.5194/egusphere-egu24-6612, 2024.

EGU24-8157 | ECS | Posters on site | CL1.2.14 | Highlight

Impact of human activity and fire on vegetation, hydrology, and carbon accumulation in Mustjärve bog, Northwest Estonia (PEATFLAMES) 

Harry Roberts, Luke Andrews, Leeli Amon, Atko Heinsalu, Piotr Kołaczek, Katarzyna Marcisz, Michał Słowiński, Normunds Stivrins, Siim Veski, and Mariusz Lamentowicz

Peatlands are important ecosystems for carbon storage, storing an estimated 25-30% of global soil carbon despite covering just 3% of Earth’s terrestrial surface. These ecosystems are under increasing pressure due to human activity and climate change, which threaten to turn peatlands from being carbon stores to sources. Human activities such as peat draining are extremely damaging to peatland hydrology, and fire was often used by people as a tool for land management clearance in the past. Fire is one of the foremost forces impacting peatlands, as it destroys surface peat and the subsequent release of stored carbon. Fire frequency is predicted to increase due to more frequent and severe droughts in some areas, and increasing human activity in areas where peat can form (particularly in the Northern Hemisphere). These trends, if realised, can accelerate climate warming as previously stored carbon is released into the atmosphere.

The focus of this study, Mustjärve bog, is an ombrotrophic peat bog located in northwest Estonia. Our project aims to assess changes in peatland fire regimes, vegetation dynamics, and hydrology to evaluate how the resilience of the site has changed over time within the context of relative changes in climate and human activity. A peat core was analysed using multiple palaeoecological proxies at high resolution (1 cm contiguous samples), to reconstruct past fire frequency, vegetation, and hydrological change over the past ~2500 years at the site. We also used historical data (population, past climate, and archaeological records) to better understand the drivers of changes uncovered in the palaeoecological record.

Our data reveals a distinct anthropogenic signal from ~700 CE onwards, coincident with increasing population and expanding land exploitation. Human activity from ~700 CE to ~1800 CE causes an increase in local fire events, culminating in lowered carbon accumulation rates, lowered water tables and higher peat bulk density. This trend continued until ~1950 CE, when there was a recovery in carbon accumulation and water table depth. Mustjärve’s vegetation history was predominantly Sphagnum, with Sphagnum Sect. Acutifolia indicative of drier conditions becoming much more prevalent from ca. 200 BC onwards, possibly owing to changes in water table depth. In the last 150 years, arboreal taxa such as Pinus sylvestris and Betula nana have encroached onto the bog, reflecting a decreasing water table and increased human activity that has impacted hydrological conditions, such as peat draining. We find little evidence for a significant climate influence on Mustjärve bog, as anthropogenic pressures on the site appear to dominate over the palaeoclimatic signal.

How to cite: Roberts, H., Andrews, L., Amon, L., Heinsalu, A., Kołaczek, P., Marcisz, K., Słowiński, M., Stivrins, N., Veski, S., and Lamentowicz, M.: Impact of human activity and fire on vegetation, hydrology, and carbon accumulation in Mustjärve bog, Northwest Estonia (PEATFLAMES), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8157, https://doi.org/10.5194/egusphere-egu24-8157, 2024.

EGU24-9872 | ECS | Orals | CL1.2.14

Impact of atmospheric relative humidity on vegetation changes during the Late Holocene reconstructed using the 17O-excess of phytoliths from sediments of Lake Ngofouo (Republic of Congo, Central Africa)  

Charlotte Mention, Julie Aleman, Jean-Charles Mazur, David Au Yang, Corinne Sonzogni, Aude Gebelin, and Anne Alexandre

Vegetation changes during the late Holocene in central Africa, especially in the Republic of Congo, are characterized by transitions between forests and savannas. However, the variables (climatic, anthropogenic) behind these transitions are still poorly identified, leading to an ongoing debate around the drivers of the central African forest block opening. Moreover, in tropical regions, the vapour pressure deficit (VPD) that controls photosynthesis and transpiration, constitutes a primary driver of ecosystems primary production and dynamics. In this context, we use a new proxy of atmospheric relative humidity (RH), which coupled with temperature allow to estimate VPD, the 17O-excess (d’17O – 0.528 x d'18O) of phytoliths. A series of calibrations have shown that the 17O-excess of plant leaf water that, according to the Craig and Gordon model is controlled by RH during transpiration, is transferred to phytoliths. A quantitative relationship linking the 17O-excess of phytoliths and RH of the growing season applies to controlled and natural climatic conditions regardless of vegetation type and atmospheric temperature. We propose to combine this new proxy of past RH, with phytoliths morphology, a long-standing paleo-vegetation proxy, to compare past RH and vegetation changes at the same temporal and spatial scales. Phytoliths were extracted from the sediments of Lake Ngofouo, located in a forest-savanna mosaic zone and which record the last 2000 years. Phytoliths types were identified and the 17O-excess of bulk phytoliths samples were analysed. Our preliminary results show a decoupling between RH and vegetation changes. A transition from forest to savanna was identified between 1534-1505 BP, following an increase in fire activity ca. 1540 BP, which marks the beginning of the recurrence of fires in the landscape. During this period no change in RH was observed (high estimated RH ~80-90%). A forest-savanna mosaic thus emerged in the landscape at 1460 BP, characterized by high percentage of grass phytoliths, despite a still high RH (~80%). RH decreased after from 79 to 62% between 997-829 BP and then increased from 62 to 83% between 829-490 BP. During the same period, tree cover increased from 829 to 662 BP and then decreased from 662 to 490 BP which occurred at the same time as an increase in population density and fire activity. It seems that the RH increase probably triggered an increase in grass biomass and thus in available fuel sufficient for more frequent and/or larger fires, which might be responsible for the later decrease in tree cover. The transition from forest to savanna at lake Ngofouo was not associated with a change in RH and was probably the result of the fire regime change that happened before. Interestingly, the later increase in RH impacted the vegetation differently; first by an increase in tree cover, and then by an increase in fire activity that resulted in a lower tree cover. This highlights the potential and complicated feedback that might exist between climate, fire and vegetation.

This study is part of the PAST-17 and Thresholds projects funded by the ANR and the European Union’s Horizon 2020 research and innovation program.

How to cite: Mention, C., Aleman, J., Mazur, J.-C., Au Yang, D., Sonzogni, C., Gebelin, A., and Alexandre, A.: Impact of atmospheric relative humidity on vegetation changes during the Late Holocene reconstructed using the 17O-excess of phytoliths from sediments of Lake Ngofouo (Republic of Congo, Central Africa) , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9872, https://doi.org/10.5194/egusphere-egu24-9872, 2024.

The terrestrial vegetation plays a crucial role in co-regulating global energy, water, carbon, and nutrient cycles. Shifts in vegetation, including changes in forest and peatland areas as well as species distribution, contribute to the large uncertainties in terrestrial ecosystems and their services under increasing disturbances caused by anthropogenic climate change.

To comprehensively assess vegetation responses and feedback to perturbations, particularly regarding carbon-nitrogen cycles and greenhouse gas exchanges, modelling efforts are indispensable. For instance, dynamical vegetation models can be exploited to investigate the terrestrial biogeochemical processes under past climate changes, such as glacial-interglacial transitions. However, such efforts often remain limited by the computational demands of complex Earth system models that struggle to capture multi-millennial timescales, which is further exacerbated by the challenges associated with model validation, leaving the long-term terrestrial vegetation dynamics largely under-constrained.

Here we employ the LPX-Bern model, a cost-efficient Dynamic Global Vegetation Model of intermediate complexity with fully coupled water, carbon, and nitrogen cycles, and present the results for simulations since the last interglacial. We critically evaluate the current model configuration, validated for pre-industrial to present-day conditions, for the last glacial cycle. The challenges in applying the model to these past times, such as the knowledge gaps in process representation, limited data availability for validation, and the limitations in model parameterisations, are addressed. The implications from simulating such long timescales and potentials to enhance the terrestrial biogeochemical processes in DGVMs are discussed. This study thus aims to contribute to advancing model development in carbon-nitrogen cycles for improved future climate projections.

How to cite: Sun, Q. and Joos, F.: Modelling terrestrial vegetation dynamics and carbon-nitrogen cycles over the last glacial using LPX-Bern, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10571, https://doi.org/10.5194/egusphere-egu24-10571, 2024.

EGU24-11926 | ECS | Posters virtual | CL1.2.14

Variations of fire events and vegetation in the western Sierra Nevada archived in speleothems during Dansgaard–Oeschger (D–O) cycles  

Zhao Wang, Jonathan Smolen, Aida Zyba, Erica A. Scarpitti, Jessica L. Oster, Isabel P. Montañez, and Michael Hren

Dansgaard-Oeschger (D-O) cycles had profound impacts on climates of the northern hemisphere in the last glacial period. However, knowledge of terrestrial climatic responses in western North America and consequently vegetation responses to climatic extremes (e.g., highly variable paleohydroclimate and wildfire events) remains limited. Analysis of organic molecular traces (i.e., plant lipids and fire markers) in speleothems is one of the most promising ways to investigate feedbacks between climatic extremes and vegetation changes. Fire-derived markers, such as polyaromatic hydrocarbons (PAHs) and levoglucosan (LG), a derivative of plant cellulose burning, are increasingly applied as proxies of paleofires in speleothem records. Here, we present a new record of plant lipids, LG, and PAHs from a precisely dated and well-studied stalagmite (~55-67 ka) collected from McLean’s Cave (ML-2) in the Sierra Nevada foothills, CA (Oster et al. 2014). The variation of PAHs over the interval 62 to 67 ka corresponds with variations in stalagmite δ13C during the D-O stadials and interstadials 15-18. The highest concentration of low (≤ 4 rings) and high (≥ 5 rings) molecular weight PAHs as well as LG is found between ~64.25-63.75 ka, suggesting elevated wildfire events during D-O interstadial 18. Dehydroabietic acid (abietane-type acid) is predominantly produced from conifers, and its highest concentration occurs at 63.75 ka and then decreases from 63.5 to 62 ka. The study of modern plants (e.g., Kozłowska et al., 2022) shows that abietane-type acid accumulates at lower radiation and cooler climates and declines in heat and drought due to its antioxidative role in protecting cell membranes from stress-induced damage. The variation of dehydroabietic acid followed the changes in stalagmite δ13C between 64 and 62 ka (Oster et al., 2014), implying changes in coniferous input affected by the wet and dry cycles (D-O stadials and interstadial 18). This highlights the ability of organic molecular records archived in stalagmites to capture the links between wildfire activity, vegetation, and hydroclimate in central California during D-O cycles.   

Reference:

Kozłowska, W., Matkowski, A., Zielińska, S., 2022. Light Intensity and Temperature Effect on Salvia yangii (B. T. Drew) Metabolic Profile in vitro. Frontiers in Plant Science 13. https://doi.org/10.3389/fpls.2022.888509

Oster, J.L., Montañez, I.P., Mertz-Kraus, R., Sharp, W.D., Stock, G.M., Spero, H.J., Tinsley, J., Zachos, J.C., 2014. Millennial-scale variations in western Sierra Nevada precipitation during the last glacial cycle MIS 4/3 transition. Quaternary Research 82, 236–248. https://doi.org/10.1016/j.yqres.2014.04.010

How to cite: Wang, Z., Smolen, J., Zyba, A., Scarpitti, E. A., Oster, J. L., Montañez, I. P., and Hren, M.: Variations of fire events and vegetation in the western Sierra Nevada archived in speleothems during Dansgaard–Oeschger (D–O) cycles , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11926, https://doi.org/10.5194/egusphere-egu24-11926, 2024.

EGU24-12877 | Posters on site | CL1.2.14

Allerød interstadial vegetation and lacustrine palaeoenvironment of the central Mologa-Sheksna Lowland (East-European Plain) 

Dmitrii Sadokov, Natalia Kostromina, Natalia Mazei, Nikita Bobrov, Ping Ding, Alexey Petrov, Larisa Savelieva, Maksim Ruchkin, Andrey Kuznetsov, Andrey Tsyganov, and Yuri Mazei

Across the northern East-European Plain, and especially in the Mologa-Sheksna Lowland (MSL), short-term climate variability in the Late Glacial caused significant palaeohydrological alterations, which drove vegetation successions. The MSL is prominent for the dense river and lake network, which have evolved through multiple water level and sedimentation regime oscillations since the Last Glacial Maximum. Extensive bogs inherit morphology of the basins, which had been filled with paleolakes for several millennia until their ultimate drainage in the early Holocene. Correspondingly, intricate morphology of lakes and deltas conditioned mosaic distribution of vegetation across the MSL.

Continuous palaeoenvironmental record for the Holocene in the MSL has been derived from several peat and lacustrine sites. The data regarding the Late Glacial is much more scarce, due to the low abundance of the relevant deposits, and poor state of preservation. Except for the MSL bog plains, pronounced evidence for the short-term palaeoenvironmental offset was discovered in the section of the sand terraces in the Mologa River catchment. The onset of Allerød warming has been traced via an organomineral layer, which was confirmed to have a continuous bedding over the area of 100 km2 in the central MSL, as revealed by auger drilling and ground-penetrating radar survey at eight sites. This layer dates back to 13.4– 12.1 cal ka BP, and is represented by interbedding of fine sand with medium decomposed peat. Palynological and plant macrofossil studies of the buried peat from three boreholes reveal several inferences about the formation of this layer and the general palaeohydrology of the MSL in the Late Glacial.

The first palaeoclimatic evidence is provided by the high abundance of spruce pollen and bark pieces, supporting the hypothesis that the layer formation occurred during the Allerød interstadial, which was characterized by a rapid expansion of spruce in the region. Secondly, high abundances of pollen and remains of hydrophytes or hydrophilous lacustrine vascular plants (Cyperaceae, Poaceae, Potamogetonaceae), mosses (Sphagnum sp., Drepanocladus aduncus and Calliergonella cuspidatum) and chara algae indicate lentic shallow water environment or the proximity of the paleolake shoreline. In general, a transition from shallow lacustrine environments, surrounded by spruce-birch forests, to tundra steppes and bogged grasslands can be deduced, based on the pollen spectra and subfossils assemblages. Third, true altitude of the buried peat layer (96.5 – 102.5 m above sea level) may be considered as a limit for the paleolake water level in the Allerød, because it delineates the surface uncovered from water or proximate to the shoreline. Thus, its lowermost discovered position can trace the extent to which the paleolake level had dropped in the Allerød. The peat was rapidly formed and buried during the late Allerød, which makes it a reliable regional isochronous stratigraphic level for the poorly studied Late Glacial sedimentary successions. This level can be used as a reference point for tracing recent short-term climate-environment interactions and effects.

How to cite: Sadokov, D., Kostromina, N., Mazei, N., Bobrov, N., Ding, P., Petrov, A., Savelieva, L., Ruchkin, M., Kuznetsov, A., Tsyganov, A., and Mazei, Y.: Allerød interstadial vegetation and lacustrine palaeoenvironment of the central Mologa-Sheksna Lowland (East-European Plain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12877, https://doi.org/10.5194/egusphere-egu24-12877, 2024.

EGU24-12926 | ECS | Orals | CL1.2.14 | Highlight

Global biosphere productivity changes during Heinrich Stadial 4: Preliminary results from the triple isotope composition of air oxygen and numerical simulation using a coupled climate model 

Ji-Woong Yang, Jean-Baptiste Ladant, Amaëlle Landais, Masa Kageyama, Thomas Blunier, Samuel Jaccard, Stéphanie Duchamp-Alphonse, Pascale Braconnot, Nicolas Viovy, Louise Crinella-Morici, and Frédéric Prié

The slowdown of Atlantic meridional overturning circulation (AMOC) caused by accelerated climate change is one of the major concerns as it would have severe impacts at global scale (e.g., Rahmstorf, 1995; Ditlevsen and Ditlevsen, 2023). However, our knowledge on the potential impact of such an event on the global biosphere productivity is still limited, despite its important role in the global carbon cycle. The reasons for this lack of knowledge is mainly two folds: on the one hand, it is challenging to estimate the global biosphere productivity based on local reconstructions as they are often based on qualitative- and indirect micropaleontological or geochemical tracers and are characterized by large spatial heterogeneities (e.g., Averyt and Paytan, 2004; Kohfeld et al., 2005), and on the other hand, numerical experiments using Earth System Models (e.g., Mariotti et al., 2012; Reutenauer et al., 2015) have yet failed to capture the response of global biosphere productivity in its entirety as they do not take into account important forcing factors such as changes in CO2, dust deposition or vegetation cover.  

To address these issues, we present here a preliminary reconstruction of the global biosphere productivity using the triple isotopic composition of air oxygen (Δ17O-O2) trapped in NEEM (North Greenland Eemian Ice Drilling) ice core samples over 42 to 37 ka covering Heinrich Stadial (HS) 4, a period marked by the weak intensity of the AMOC. Local reconstructions such as European pollen assemblages (e.g., Sánchez Goñi et al., 2020), Antarctic ice-core non-sea-salt Na and Ca (e.g., Fischer et al., 2007), or marine sediment core opal flux records from sub-Antarctic zone of Southern Ocean (Gottschalk et al., 2016) and previous model studies (e.g., Mariotti et al., 2012; Reutenauer et al., 2015) indicate a weak global biosphere productivity during HS4. However, our preliminary result from ice-core Δ17O-O2 measurements shows little evidence of reduced global biosphere productivity during HS 4. Idealized Heinrich-like freshwater hosing experiments using IPSL-CM5A2-VLR Earth System Model support our findings. In this presentation, the potential role of different forcing factors in regulating the global biosphere productivity will be discussed.

How to cite: Yang, J.-W., Ladant, J.-B., Landais, A., Kageyama, M., Blunier, T., Jaccard, S., Duchamp-Alphonse, S., Braconnot, P., Viovy, N., Crinella-Morici, L., and Prié, F.: Global biosphere productivity changes during Heinrich Stadial 4: Preliminary results from the triple isotope composition of air oxygen and numerical simulation using a coupled climate model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12926, https://doi.org/10.5194/egusphere-egu24-12926, 2024.

EGU24-13457 | Posters on site | CL1.2.14 | Highlight

StalFire Consortium: Defining the paleoclimate-fire relationship in California across temporal and spatial scales  

Isabel P. Montañez, Jessica L. Oster, Eliot A. Atekwana, Gabriel Bowen, Yuval Burstyn, Cameron de Wet, Elizabeth M. Griffith, Michael Hren, Kesego P. Letshele, Sarah Pederzani, Erica A. Scarpitti, Jonathan Smolen, Zhao Wang, and Aida Zyba

Global climate change is projected to lead to an expansion of wildfire-prone regions coupled with increase in fire frequency and intensity. In the Western US the characteristic fire season has changed considerably in recent years. Notably, there has been an observed doubling of autumn fire activity, an increase in the occurrence and duration of extreme fire weather conditions, and an intensification of wildfire severity. This trend is expected to persist and intensify with increased warming. For California (CA), climate models predict minimal changes to mean annual precipitation, but a substantial increase in climate volatility on the decadal and sub-centennial scale. This volatility manifests as persistent droughts interrupted by pluvial episodes, creating what is referred to as a 'whiplash climate.' However, predicting how the wildfire regime in CA will evolve with increased climate volatility remains a challenging task.

StalFire is multi-lab collaborative framework (consortium) established to facilitate research focused on utilizing paleoclimate data archived in stalagmites. The primary goal is to provide new insights into paleo-wildfires, with a specific emphasis on assessing the paleoclimate-wildfire relationship in CA across multiple timescales and under different climate states. Drawing upon over a decade of monitoring and stalagmite record development in CA caves exposed to significant fires, this consortium project is guided four research objectives: (1) Monitoring tracer evolution across karst systems to improve conventional proxies and expand the understanding and application of promising new qualitative hydroclimate proxies and fire tracers. (2) Developing aquantified representation  — a forward proxy system model — of the conditions and processes that govern the different proxy signals of past hydroclimate and fire behavior in stalagmites. (3) Expanding and improving existing CA multi-proxy records for stalagmites representing transects of the north-south climate dipole extending from coastal to Sierra Nevada regions. 4) Conducting site-specific to regional proxy-model comparisons and providing quantitative reconstructions of hydroclimate and fire activity in CA over the past 70,000 years. 

We provide a summary of initial results of the StalFire Consortium that focus on developing a 'surface-to-stalagmite' understanding of hydroclimate and fire tracers through monitoring coupled with proxy development (d44Ca, fluid inclusion water isotopes, dual clumped isotope, and plant/microbial biomarkers, biomass burning-derived organic molecules like anhydrosugars and polycyclic aromatic hydrocarbons). Finally, we aim for this presentation to encourage discussion among researchers, labs, and work groups involved in paleo-fire coupled with hydroclimate research, from method development to paleorecord analysis.

How to cite: Montañez, I. P., Oster, J. L., Atekwana, E. A., Bowen, G., Burstyn, Y., de Wet, C., Griffith, E. M., Hren, M., Letshele, K. P., Pederzani, S., Scarpitti, E. A., Smolen, J., Wang, Z., and Zyba, A.: StalFire Consortium: Defining the paleoclimate-fire relationship in California across temporal and spatial scales , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13457, https://doi.org/10.5194/egusphere-egu24-13457, 2024.

EGU24-13877 | Orals | CL1.2.14

Reconstructing Paleofire-Climate Connections in Speleothems Using Organic Molecules: A Source to Sink Perspective  

Michael Hren, Zhao Wang, Jonathan Smolen, Yuval Burstyn, Kesego Letshele, Aida Zyba, Erica Scarpitti, Jessica Oster, Cameron De Wet, and Isabel Montañez

Records of past fire frequency and intensity are critical for understanding the links between atmospheric pCO2, climate and ecosystem change. In terrestrial settings, stalagmites provide one of the most precise, multi-proxy, and high-resolution archives of climate information. Yet, records of past fire occurrence or fire intensity, which are commonly derived from charcoal abundances in sediments, are generally not available within the same archive or at comparable time resolution.

Sedimentary organic molecular biomarkers are increasingly utilized as proxies for past fire, environment and climate, and there is considerable potential for past fire activity to be archived in stalagmites1,2,3. Recent analytical and methodologic advances now allow measurement of molecular markers of climate and fire at trace abundances, and surface-generated, plant-derived biomolecules and fire markers, including polycyclic aromatic hydrocarbons (PAHs), lignin oxidation products (LOPs), and anhydrosugars such as levoglucosan (LG) and its isomers mannosan (MA) and galactosan (GA), have been documented in stalagmites older than 100 ka1.

Fire markers are preserved in stalagmites at multiple caves across the fire-prone landscape of California, USA, and recent study of LG and LOPs in a California Coast Range stalagmite provides evidence for a strong connection between fire activity and climate whiplash2, while measurements of PAHs from a well-studied stalagmite in McLean’s Cave located in the central Sierran foothills (ML-1) captures a link between increased fire intensity and climate change during Heinrich Stadial-13. Despite clear preservation of fire-derived molecules in stalagmites, results from modern California cave systems and surface environments show that fire markers produced from recent fire events have variable mobility through soils and the epikarst system, while plant lipids produced by surface vegetation record significant degradation during transit from the surface to cave drip water.

Here, we discuss the promises and pitfalls of producing organic molecular records of climate and fire from speleothems. Specifically, we present modern surface to cave organic molecular data from several sites in California, USA to review: 1) factors that influence the terrestrial production of organic molecular markers of ecosystem, fire and climate; 2) mobilization of organic markers through the soil, epikarst and cave environment; 3) alteration of surface-generated molecular signatures due microbial activity or preferential mobilization of different molecular classes; and 4) incorporation of organic markers of fire and climate in stalagmites.

 

1Blyth, A.J., Baker, A., Collins, M.J., Penkman, K.E.H., Gilmour, M.A., Moss, J.S., Genty, D. & Drysdale, R.N. (2008) Molecular organic matter in speleothems and its potential as an environmental proxy. Quat. Sci. Rev., 27, 905-921.

2Homann, J., Oster, J. L., de Wet, C. B., Breitenbach, S. F. M., & Hoffmann, T. (2022). Linked fire activity and climate whiplash in California during the early Holocene. Nature Communications, 13(1), 7175.

3Smolen, J., Montañez, I., and Hren, M.: Fire, Work with Me: A PAH record from a Southwestern US speleothem , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16912, https://doi.org/10.5194/egusphere-egu23-16912, 2023.

How to cite: Hren, M., Wang, Z., Smolen, J., Burstyn, Y., Letshele, K., Zyba, A., Scarpitti, E., Oster, J., De Wet, C., and Montañez, I.: Reconstructing Paleofire-Climate Connections in Speleothems Using Organic Molecules: A Source to Sink Perspective , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13877, https://doi.org/10.5194/egusphere-egu24-13877, 2024.

EGU24-14386 | Orals | CL1.2.14 | Highlight

Holocene Land Cover Change in North America:  Trends, Drivers, and Feedbacks 

Andria Dawson, John W. Williams, Marie-José Gaillard, Simon Goring, Behnaz Pirzamanbein, Johan Lindstrom, R. Scott Anderson, Andrea Brunelle, David Foster, Konrad Gajewski, Daniel G. Gavin, Terri Lacourse, Thomas A. Minckley, Wyatt Oswald, Bryan Shuman, and Cathy Whitlock

Land cover governs biogeophysical and biogeochemical feedbacks between the land surface and atmosphere. Holocene vegetation-atmosphere interactions are of particular interest, both to understand the climate effects of intensifying human land use and as a possible explanation for the Holocene Conundrum, a widely studied mismatch between simulated and reconstructed temperatures. Progress addressing the Conundrum has been limited by a lack of data-constrained, quantified, and consistent reconstructions of Holocene land cover change. Following protocols from PAGES LandCover6k, a network of 1445 sedimentary pollen records from the Neotoma Paleoecology Database, and the REVEALS pollen-vegetation model coupled with a Bayesian spatial model, we developed land cover reconstructions with uncertainty for North America for 25 time intervals spanning the Holocene. We use these spatially comprehensive land cover maps to determine the pattern and magnitude of land cover changes at continental to regional scales and discuss underlying ecological, climatic, and anthropogenic drivers. Finally, we infer Holocene radiative forcing from these land cover shifts.

Major land cover changes in North America include: 1) Early Holocene afforestation is attributed to rising temperatures and deglaciation, which likely amplified early Holocene warming via the albedo effect; 2) A continental-scale mid-Holocene peak in summergreen trees and shrubs (8.5 to 4 ka) may have been caused by a positive and understudied feedback loop among insolation, temperature, and phenological seasonality.  3) A  last-millennium decrease in summergreen trees and shrubs with corresponding increases in open land, likely driven by intensifying land use and neoglacial cooling. 

Land cover trends vary within and across regions due to individualistic taxon-level responses to environmental change.  Major species-level events, such as the mid-Holocene decline of eastern hemlock, may have altered regional climates. The substantial land-cover changes reconstructed here underscore the importance of biogeophysical vegetation feedbacks to Holocene climate dynamics. Continental-scale radiative forcing inferred from land cover change indicates early and late pre-industrial Holocene warming interrupted by a mid-Holocene period of cooling and followed by cooling in the recent millenia. These forcings from natural vegetation change are of the same order of magnitude as global forcings resulting from changes in atmospheric greenhouse gas concentrations from 1750 to 2019.

These Holocene reconstructions for North America serve the Earth system modeling community by providing better-constrained land cover scenarios and benchmarks for model evaluation, that improve the understanding of regional- to global-scale processes driving Holocene land cover dynamics.

How to cite: Dawson, A., Williams, J. W., Gaillard, M.-J., Goring, S., Pirzamanbein, B., Lindstrom, J., Anderson, R. S., Brunelle, A., Foster, D., Gajewski, K., Gavin, D. G., Lacourse, T., Minckley, T. A., Oswald, W., Shuman, B., and Whitlock, C.: Holocene Land Cover Change in North America:  Trends, Drivers, and Feedbacks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14386, https://doi.org/10.5194/egusphere-egu24-14386, 2024.

EGU24-14667 | ECS | Orals | CL1.2.14

Wildfire, vegetation, and climate history of central Taiwan from the end of the last glaciation to the late Holocene 

Abdur Rahman, Yuan-Pin Chang, Hong-Chun Li, Ling-Ho Chung, and Liang-Chi Wang

Climate change is expected to lead to an increased frequency of wildfires within forest ecosystems. To accurately anticipate the ramifications of climate change on forests, a comprehensive understanding of the ecological processes governing fire dynamics—specifically intensity, size, and type—is essential. However, the scarcity of long-term data on the intricate relationship between climate, fire, and vegetation dynamics presents a considerable challenge. In this study, a long-term relationship between wildfire, vegetation has been investigated, and climate in the central Taiwan region, spanning from the late glacial period to the late Holocene. For this, multiple proxy approach, including charcoal (CHAR and fire frequency), pollen data, and the carbon isotopic composition of total organic carbon, have been followed. The current study revealed that wildfire largely occurred during the drier climate conditions in the Taiwan region, which attributed to El-Nino like situation in region. Furthermore, it has been observed that from the late glacial period to the late Holocene, there was a shift in biofuel sources from woody plants to herbaceous plants, with a sharp change at the beginning of the Holocene. High fire frequency and intense wildfires were observed during the late glacial period, attributed to a drier climate. On the other hand, higher fire frequency and more intense wildfires during the late Holocene were attributed to human-induced wildfires in the central Taiwan region. 

How to cite: Rahman, A., Chang, Y.-P., Li, H.-C., Chung, L.-H., and Wang, L.-C.: Wildfire, vegetation, and climate history of central Taiwan from the end of the last glaciation to the late Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14667, https://doi.org/10.5194/egusphere-egu24-14667, 2024.

EGU24-14971 | ECS | Orals | CL1.2.14

Northern African vegetation and land cover changes led to increased Arctic warming during the mid-Holocene 

Shivangi Tiwari, Francesco S. R. Pausata, Anne de Vernal, Hugo Beltrami, Allegra N. LeGrande, and Michael L. Griffiths

The mid-Holocene (MH) was characterized by substantial vegetation changes over northern Africa, termed the Green Sahara. Concurrently, several proxy reconstructions have indicated anomalous warmth over some Arctic regions during the MH, with some records also indicating an abrupt cooling coinciding with the Saharan desertification. This has prompted studies into a potential teleconnection between the MH Green Sahara and the Arctic, leading to conflicting hypotheses regarding the dominant direction and mechanism for this teleconnection.

In this study, we analysed outputs from four fully coupled global climate models to identify the impact of the Green Sahara on the Arctic region. Through the difference of two sets of mid-Holocene simulations – with and without the Green Sahara – we isolated the effect of the northern African vegetation and land cover changes on Arctic temperatures. We show that simulations incorporating the Green Sahara yield considerably higher Arctic warming relative to simulations without explicit prescriptions of vegetation changes. We also conducted atmosphere-only global climate model simulations to identify whether or not Arctic temperature changes impacted northern African precipitation. Our results suggest that while the Arctic temperature changes induced changes to the atmospheric circulation over northern Africa, they were too weak to substantially contribute to Saharan desertification.

How to cite: Tiwari, S., Pausata, F. S. R., de Vernal, A., Beltrami, H., LeGrande, A. N., and Griffiths, M. L.: Northern African vegetation and land cover changes led to increased Arctic warming during the mid-Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14971, https://doi.org/10.5194/egusphere-egu24-14971, 2024.

EGU24-15781 | ECS | Posters on site | CL1.2.14

An 8 ka record of drought and fire dynamics in the southern European Alps based on biomarker analyses  

Lisa Danius, Paul Strobel, Maximilian Prochnow, Roland Zech, and Marcel Bliedtner

The southern European Alps are currently suffering from serious drought conditions and wildfires due to climate change. For this reason, paleoenvironmental research is fundamental in this vulnerable region to better understand the interactions between climate, humans, and landscape in the past, which are still largely unknown. Therefore, we established an 8 ka sediment record from Lago di Pusiano in the Brianza region (northern Italy) to reconstruct previous drought and wildfire dynamics since the Neolithic period using biomarker analyses. Specifically, besides well-established geochemical analyses, we use compound-specific hydrogen isotope analyses (δ2H) of n-alkanes to reconstruct hydroclimatic conditions and polycyclic aromatic hydrocarbons (PAHs) to reconstruct fire activities.

Our results show that δ2Hof the terrestrial n‑C29 and n-C31, which both reflect the δ2H signal of the growing season precipitation, is enriched during the Mid Holocene (~8 to 4.2 cal. ka BP), depleted from ~4.2 to 2.5 cal. ka BP and enriched from ~2.5 to 0.4 cal. ka BP. On longer timescales, we interpret our terrestrial δ2H to reflect the isolation-driven temperature change due to northern hemispheric cooling, showing an ongoing depletion in δ2H from the Mid to Late Holocene. However, on shorter timescales, especially during the Late Holocene, terrestrial δ2H can be overprinted by changes in the moisture source of precipitation, which are mostly related to the North Atlantic Oscillation (NAO) and the position of the Westerlies. Compared to the terrestrial n-alkanes, δ2H of the aquatic n‑C25, which reflects the δ2H signal of lake water, is generally more enriched due to lake water evaporation. Consequently, the offset between aquatic and terrestrial δ2H gives a valuable indication about evaporation at Lago di Pusiano and indicates wetter conditions during phases of enriched terrestrial δ2H and dryer conditions during depleted terrestrial δ2H.

PAHs are abundant throughout the sediment core and increase during periods of higher regional human activity (e.g., Bronze Age pile dwellings ~4 cal. ka, Roman settlements ~2 cal. ka, and during Medieval times ~1 cal. ka), especially strongly during industrialization. The occurrence of PAHs in the Pusiano sediments, especially the large amount of high molecular PAHs, indicates significant local fire episodes with biomass combustion at high burning temperatures. The comparison of PAHs and δ2H of n‑alkanes suggests the presence of increased fire activities during wetter periods, possibly due to higher biomass availability as fuel for more extensive wildfires, and/or increased anthropogenic burning due to increased human presence during wetter periods.

How to cite: Danius, L., Strobel, P., Prochnow, M., Zech, R., and Bliedtner, M.: An 8 ka record of drought and fire dynamics in the southern European Alps based on biomarker analyses , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15781, https://doi.org/10.5194/egusphere-egu24-15781, 2024.

Investigations of past biotic responses to rapid climate shifts are useful for developing biological scenarios that may result from future climate change. Vegetation responses to the Younger Dryas (YD) cold climatic reversal, the 8.2 ka cooling event, and the 4.2 ka event are of considerable interest. In this paper, we conduct model simulations of vegetation responses to these rapid climate changes over East Asia, and compare them with pollen-based vegetation records. Our aims were to investigate the vegetation responses to rapid climate changes with different magnitudes and to analyze dominant impact factors on vegetation in East Asia. Our results reveal that all major Plant Functional Types responded to the climate changes, but the magnitude, timing, and impact of their responses varied, with most changes in vegetation composition rather than vegetation type succession. In addition, it was found that after the abrupt cooling events the vegetation did not always recover to the state simulated before the perturbation, suggesting that different vegetation compositions may occur under similar climate conditions. Notably, there was a latitudinal gradient in the magnitude of these cold events in East Asia and in the resulting vegetation response, indicating a more pronounced vegetation responses to the severe cooling in the north and weaker responses to less cooling in the south. Changes in temperature exerted a major influence on the vegetation dynamics in the most high latitude regions, and changes in both temperature and precipitation were responsible for the vegetation changes at mid-to-high-latitudes. Vegetation compositions show a long-lasting effect of abrupt climate changes through eco-physiological and ecosystem demographic processes.

How to cite: Li, H., Chen, C., Zhao, W., and Zhao, Y.: Vegetation responses in East Asia to rapid climate changes: comparisons among the Younger Dryas event, the 8.2ka event, and the 4.2ka event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15834, https://doi.org/10.5194/egusphere-egu24-15834, 2024.

EGU24-15920 | ECS | Posters on site | CL1.2.14

Vegetation response in SE France to the millennial-scale climate variability of the last glacial period 

Tiffanie Fourcade, Maria Fernanda Sanchez Goñi, Jonathan Lesven, Christelle Lahaye, and Anne Philippe

Deep-sea pollen records from the Western European margin indicate that regional vegetation oscillated between open forest and steppe during the Last Glacial period (ca. 115-27 ka), in response to the millennial scale climate variability, specifically the Dansgaard-Oeschger, (D-O) cycles and Heinrich events (HE). The magnitude of the forest expansions during D-O warming events was modulated by orbital parameters. However, the vegetation response in the north-western Mediterranean region during this period remains poorly understood due to the fragmentary nature of the available sequences.

In this study, we present a new well-chronologically constrained high-resolution marine pollen record from the Gulf of Lion (MD99-2343, 40°29'N, 4°01'E) documenting the vegetation response in southeastern France during Marine Isotope Stages (MIS) 4 to 2 (ca. 73-27 ka). Initial findings highlight that the extent of the temperate forest expansions in SE France, i.e. the forest colonizing the Rhône valley, in response to D-Os warming events is modulated by precession, as previously indicated by Western European margin pollen records located in the Mediterranean region below 40°N. In Western Europe, the HEs are all characterized by steppe expansions, but the new pollen analysis documents another scenario with an increase in forest cover during HE 6. We hypothesize that the combination of minima in precession and local atmospheric and marine processes in the Gulf of Lion allowed the development of the temperate forest in SE France during HE 6, while the expansion of open environments occurred in Western Europe.

How to cite: Fourcade, T., Sanchez Goñi, M. F., Lesven, J., Lahaye, C., and Philippe, A.: Vegetation response in SE France to the millennial-scale climate variability of the last glacial period, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15920, https://doi.org/10.5194/egusphere-egu24-15920, 2024.

EGU24-16394 | ECS | Posters on site | CL1.2.14

Holocene Integrative Vegetation Evolution (HIVE) : dynamical modelling under transient climate conditions in Europe 

Isabeau Aurore Bertrix, Nicolas Viovy, Hisashi Sato, and Didier M Roche

European landscapes have known a variety of transformations through the Holocene as a consequence of large-scale climate changes and anthropogenic impact. Recent evolution of the European area has seen a recession of agriculture in several regions (e.g. Navarro & Pereira, 2012, Ecosystems ; Perpiña Castillo et al, 2018, European Commission) putting into question what is to happen to the land so abandoned (Fayet et al, 2022 Environmental Science & Policy), for example if more « natural » conditions are to be implemented.

During the Holocene, European forests evolved in response to both climatic and human pressure. This joint evolution makes it hard to understand what the rôle of each factor is. Recent simulations at the global scale show that there could be significant delay between the natural vegetation evolution as computed in climate models and the observed evolution as recorded in palynological assemblages (Dallmeyer et al., 2023).

We aim at exploring the effect of human and climatic impacts on the vegetation evolution in Europe during the Holocene by means of high spatial resolution modelling.

To better understand how human pressure impacted vegetation cover in Europe, initial DGVM simulations were conducted using SEIB model, and were compared to pollen-based reconstruction from the REVEALS database. That way, the difference between simulations (representing european vegetation cover without homo sapiens presence) and data (representing real european vegetation cover) are a mean to evaluate the extent of the human impact. The simulations were running using climatic inputs from the intermediate complexity climatic model iLOVECLIM, using a downscaling approach to increase the spatial resolution and a bias correction method to improve the climate representation over the european area. Using steps of 300 years time windows periods from the begining of the Holocene to the preindustrial period, we present the results of those simulations and the comparaison with the pollen database as well as comparison with another vegetation model to assess the inter-model dispertion. The outcome could help us understand how our species has shaped the lands even before agricultural times as well as the extent of the climate induced vegetation evolution.

 

References

 

Navarro, L.M., Pereira, H.M. Rewilding Abandoned Landscapes in Europe. Ecosystems 15, 900–912 (2012). https://doi.org/10.1007/s10021-012-9558-7

Perpiña Castillo, C., Kavalov, B., Diogo, V., Jacobs-Crisioni, C., Batista e Silva, F., Lavalle, C, Agricultural land abandonment in the EU within 2015-2030, JRC113718, European Commission 2018

Fayet, C., Reilly, K., Van Ham, C., Verburg, P. H. (2022) The potential of European abandoned agricultural lands to contribute to the Green Deal objectives: Policy perspectives, Environmental Science & Policy, Volume 133, pages 44-53.

Dallmeyer, A, Kleinen, T, et al The deglacial forest conundrum, Nature Communications, 2022 https://doi.org/10.1038/s41467-022-33646-6

How to cite: Bertrix, I. A., Viovy, N., Sato, H., and Roche, D. M.: Holocene Integrative Vegetation Evolution (HIVE) : dynamical modelling under transient climate conditions in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16394, https://doi.org/10.5194/egusphere-egu24-16394, 2024.

EGU24-16656 | Posters on site | CL1.2.14

Refining Holocene environmental change and human impacts at Moossee, Switzerland, by exploring polycyclic aromatic hydrocarbons as innovative proxies for paleofire 

Line Rittmeier, Maximilian Prochnow, Paul Strobel, Marcel Bliedtner, Fabian Rey, Willy Tinner, and Roland Zech

Charcoal has been the first choice when studying paleofire and related ecosystem disturbances over decades, because it can be easily obtained, for example, together with pollen. It is used to track changes in local versus regional fire activity (e.g., Vachula et al., 2018; Vachula, 2021, Paleo3). However, despite many progresses in charcoal analyses, specific information about paleofires such as fire intensity partly remains elusive, although such information is highly interesting particularly for archaeological sites where human impacts are expected.

Moossee is a small lake located near Bern (Switzerland) and is a key site to study past interactions between environment and human impacts because the presence of humans is documented at the site by lake pile dwellings since the Neolithic ~7 kyr ago. Moreover, the sedimentary record of this lake covers the last 19 kyr, has an excellent chronological control, and was already extensively studied by pollen and charcoal analyses at high temporal resolution.

We present first results of polycyclic aromatic hydrocarbons (PAHs) in the Moossee sediments covering the Mid and Late Holocene in 30-year resolution. PAHs are a relatively new, innovative proxy showing great potential to investigate fire characteristics and to corroborate charcoal data, since their composition varies depending on multiple factors, such as combustion temperature, intensity, and distance.

Our newly obtained PAH dataset generally agrees with the existing charcoal record from Moossee, although the PAH concentrations reveal a stronger variability in paleofires especially during pre-Roman times (i.e., prior to ~2500 cal. yr BP) where charcoal concentrations are low. However, we find high PAH concentrations during Late Iron Age (~2200 cal. yr BP) coinciding with higher charcoal concentrations related to the founding of a settlement at Bern. PAHs are dominated by low molecular weight compounds (molecular mass 152 to 202) until ~1300 cal. yr BP. The predominance of light PAHs together with low microscopic charcoal concentrations likely indicates local fire activity. This is also supported by new spatial calibrations suggesting that the distribution of light PAHs is spatially rather limited (Vachula et al., 2022, Paleo3). With the beginning of the Middle Ages (~1300 cal. yr BP), high molecular weight PAHs (molecular mass 252 to 278) are dominant documenting higher burning temperatures and increasing regional fire intensity, which is in line with increased charcoal influx. This coincides with increasing human impact across the Swiss Plateau. A massive increase of PAHs with a simultaneous drop in charcoal concentrations since 150 cal. yr BP can be attributed to the industrialization and the combustion of fossil fuels.

In conclusion, our preliminary high-resolution PAH dataset from Moossee provides valuable new information that are only partly recorded by the already existing charcoal and pollen data. Thus, PAHs have great potential for studying paleofire history at Moossee, although more evaluation of the PAHs and their differences to charcoal is necessary. During the upcoming months, we will extend this PAH dataset with high-resolution compound-specific deuterium analyses on leaf waxes to further investigate links between hydroclimatic dynamics, environmental changes and the presence of paleofires at Moossee.

How to cite: Rittmeier, L., Prochnow, M., Strobel, P., Bliedtner, M., Rey, F., Tinner, W., and Zech, R.: Refining Holocene environmental change and human impacts at Moossee, Switzerland, by exploring polycyclic aromatic hydrocarbons as innovative proxies for paleofire, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16656, https://doi.org/10.5194/egusphere-egu24-16656, 2024.

EGU24-19277 | ECS | Posters on site | CL1.2.14

Impacts of forest cover and disturbance on Holocene forest biodiversity 

Laura Schild and Ulrike Herzschuh

Forests play a critical role in carbon storage and actively mitigate climate change. By fostering biodiversity they offer further intrinsic and economic value through ecosystem functions and services. However, logging and the increasing frequency and intensity of wildfires and pest outbreaks pose significant disturbances to forests. Understanding the interactions between forest cover, biodiversity, and disturbance is essential for determining effective strategies for forest management and conservation. 

To investigate past dynamics in diversity and forest cover, we utilized pollen-based vegetation reconstructions for the Northern Hemisphere over the past 10 000 years. We derived richness and forest cover and computed metrics for forest cover trends, centennial forest cover variability, and disturbance frequency and intensity. We analyzed the relationship of these potential drivers and forest cover and richness using loess models and explored spatio-temporal patterns.

Our findings reveal a negative relationship of richness with forest cover, with maximum richness observed at low to intermediate forest cover values.This indicates a potential tradeoff between high forest cover for optimal carbon storage and high biodiversity. Richness also demonstrates a normal response to centennial forest cover variability, supporting the intermediate disturbance hypothesis. Interestingly, we also find that increasing the cumulative disturbance intensity increases richness. This indicates a positive effect on forest richness from both many small and few large disturbances. This highlights the potential of disturbances to increase and maintain biodiversity in temperate and boreal forest.
These findings could help with designing forest management and conservation measures that align with carbon storage and biodiversity goals.

How to cite: Schild, L. and Herzschuh, U.: Impacts of forest cover and disturbance on Holocene forest biodiversity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19277, https://doi.org/10.5194/egusphere-egu24-19277, 2024.

EGU24-574 | ECS | Orals | GM10.4

Using sediment facies & ground penetrating radar profiles to investigate the internal architecture and genesis of De Geer moraines 

Gwyneth Rivers, Robert Storrar, Joni Mäkinen, Antti Ojala, Naomi Holmes, and Camilla Holmroos

De Geer moraines (DGMs) have the potential to generate very high-resolution spatial and temporal ice margin reconstructions (~annual in contrast to 100-500 years, the current state-of-the-art). Existing studies suggest that DGMs likely form annually in a sub-aqueous, ice-marginal environment whereby basal sediments are advected and deposited at the grounding-line during seasonal advances. However, there have also been suggestions of a crevasse-fill origin that challenges this temporal regularity. Whilst the spatiotemporal properties of DGMs are disputed, the balance of evidence suggests an ice-marginal depositional environment with annual/seasonal regularities. Understanding the processes related to DGM formation is therefore critical, as it underpins the ability to use DGM to delineate ice-marginal retreat at unprecedented (potentially annual) resolutions.

A recent large-scale 3D morphometry study of DGMs and Crevasse-Squeeze Ridges (CSRs) was undertaken to constrain landform metrics and explore their formation processes. The results revealed statistically significant differences across all morphometrics between the sampled DGMs and CSRs. DGMs were found to be lower-relief, narrower, slightly more asymmetrical, and more sinuous than the studied CSRs. The morphometrics of DGMs support an ice marginal depositional environment. Furthermore, tendencies for cross-sectional asymmetry suggest a unidirectional push movement involved during formation. These inferences, however, must be supported with geophysical and/or sedimentological investigations.

Here we present the results of a field study using sedimentological and geophysical (Ground Penetrating Radar) techniques to investigate the internal architecture of DGMs in southwest Finland. Sedimentological data was acquired from two excavated exposures and 55 GPR profiles were obtained from four different locations across SW Finland. Radar facies were identified and corroborated with the lithofacies units as observed in the ca. 30 m long trench excavations. Typically, these facies comprise of stacked thrusted planes of laminated clay and diamicton on proximal slopes, sheared diamicton on surfaces indicative of proglacial pushing/overriding, and gravity-driven flow deposits on distal slopes. At places, glaciotectonic structures such as dipping, faults and folds were also identified.

The results may be used to complement the existing morphometry study, constraining the main processes involved in DGM formation and validating the use of DGMs as ice marginal indicators. This can ultimately be used as a foundation to explore the climatic significance of DGM ridges, thus meriting further work to constrain the spatial and temporal properties of DGMs during deglaciation.

How to cite: Rivers, G., Storrar, R., Mäkinen, J., Ojala, A., Holmes, N., and Holmroos, C.: Using sediment facies & ground penetrating radar profiles to investigate the internal architecture and genesis of De Geer moraines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-574, https://doi.org/10.5194/egusphere-egu24-574, 2024.

EGU24-1010 | ECS | Orals | GM10.4 | Highlight

  A glacier-based reconstruction of the Last Glacial Maximum climate in the southern European Alps     

Lukas Rettig, Giovanni Monegato, Sarah Kamleitner, Matteo Spagnolo, Adriano Ribolini, Susan Ivy-Ochs, Brice R. Rea, Franco Gianotti, and Paolo Mozzi

Improved records of precipitation and temperature are crucial to understand the evolution of Alpine glaciers during the Last Glacial Maximum (LGM). Palaeoclimate models and proxy data have suggested an increased moisture supply to the southern face of the Alps during the LGM, following a south-ward shift of the North-Atlantic jet stream. Ground control for such models, however, has been lacking for many sectors of the Alps, and regional climatic gradients have therefore remained poorly constrained. Here, we present new insights into the LGM palaeoclimate in the southern Alps, using the Equilibrium Line Altitudes (ELAs) of marginal glaciers as proxy. Marginal glaciers include ice caps, cirque, and valley glaciers that throughout the LGM remained isolated from larger outlet lobes connected to the Alpine ice network. Several sites of marginal glaciation were investigated through a combination of geomorphological mapping, surface exposure dating (both 10Be and 36Cl dating), and numerical reconstructions of palaeoglacier geometries and ELAs.

The chronological data indicate that marginal glaciers across the southern Alps reached their maximum extent by ca. 24 ka and that an important readvance occurred at 19 ka, at the end of the LGM. Reconstructed palaeoglacier ELAs show considerable variations, from ca. 1100 m a.s.l. in the Julian and Carnic Prealps (SE-Alps) up to almost 2000 m a.s.l. in the Maritime Alps (SW-Alps). Minor differences between the sites can be attributed to topoclimatic factors (i.e., received solar radiation related to catchment aspect). Spatial trends in ELA, however, primarily reflect regional climatic gradients. More specifically, we recognised: (1) a N-S gradient related to increasing summer temperatures with lower latitudes, and (2) a strong E-W gradient driven by precipitation. For all sites, our data indicate little to no reduction in LGM precipitation compared to the present day, highlighting the importance of substantial precipitation for the build-up of marginal LGM glaciers in the southern Alps.

How to cite: Rettig, L., Monegato, G., Kamleitner, S., Spagnolo, M., Ribolini, A., Ivy-Ochs, S., Rea, B. R., Gianotti, F., and Mozzi, P.:   A glacier-based reconstruction of the Last Glacial Maximum climate in the southern European Alps    , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1010, https://doi.org/10.5194/egusphere-egu24-1010, 2024.

EGU24-2307 | Orals | GM10.4

Schmidt hammer exposure dating (SHD) the Last Glacial-Interglacial Transition in Wester Ross, Scotland  

Alastair Curry, Olly Bartlett, and Jonathan Newitt

Understanding the extent, retreat dynamics and climate-glacier coupling of the Scottish Ice Sheet during the Last Glacial-Interglacial Transition (LGIT) is hampered by a highly fragmentary geomorphological record, and is dependent on a precise and accurate dating framework to constrain deglaciation. On land, readvance of the retreating ice margin is recorded in part of NW Scotland by moraines of the Wester Ross Readvance at ~15.4-15.8 ka, preceding the Lateglacial Interstade and the Loch Lomond Stade ~12.9-11.7 ka. While the number of dated landforms has increased in recent years, the LGIT chronology in NW Scotland is primarily based on a limited number of samples per site, using Terrestrial Cosmogenic Nuclide Dating (TCND) methods that can yield conflicting or uncertain results. This highlights the value of developing complementary dating methods.

Previous studies have questioned the reliability of the Schmidt hammer exposure dating (SHD) technique on lithologies other than granite. This research (i) evaluates the use of SHD on sandstone in the NW Scottish Highlands; (ii) develops a local, lithology-specific calibration curve; (iii) applies this to estimate the age of undated surfaces and tests existing interpretations of landscape change during the LGIT. Field results from a 1,500 km2 area of NW Scotland conclude that SHD can detect significant differences (p <0.001) between Torridonian sandstone surfaces of Wester Ross Readvance and Loch Lomond Stadial age. Based on 31 existing, re-calibrated 10Be ages, a calibration curve was generated (R2 = 0.58, p <0.001) for the period ~18-11 ka BP, and applied to 17 undated Torridonian sandstone surfaces. Our findings support the view that on selected lithologies and with rigorous adherence to careful field procedures, SHD can represent a valuable, cost-effective and reliable tool for obtaining large numerical dating samples for landforms in formerly glaciated terrain.

How to cite: Curry, A., Bartlett, O., and Newitt, J.: Schmidt hammer exposure dating (SHD) the Last Glacial-Interglacial Transition in Wester Ross, Scotland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2307, https://doi.org/10.5194/egusphere-egu24-2307, 2024.

EGU24-3491 | ECS | Posters on site | GM10.4

Quantification of landslide-induced changes in glacier dynamics – project outline 

Arunabh Bhattacharyya, Marek Ewertowski, Jakub Małecki, and Gisela Domej

The response of glacial masses to climate change is well documented. However, the impact of landslides on glacier dynamics and stability requires greater research. Landslides in glacierized mountains can be caused by climate change (e.g. permafrost thawing), intense precipitation, paraglacial response of slopes or earthquakes and can, in turn, limit ablation, increase meltwater production and alter glacier velocities. Besides, landslides can be hazardous to life and infrastructure. Permafrost degradation, de-buttressing of slopes, extreme precipitation and freezing and thawing cycles make mountain glaciers susceptible to instability and cascading hazards. Our project thus focuses on identifying the research gaps associated with landslide-glacier dynamics and related hazards. The two components of our project are 1) Remote sensing and GIS and 2) Modelling. Different spatial scales (landform, catchment, global) will be considered for our research.

This presentation aims to outline PhD project and discuss proposed approaches with the glaciological, geomorphological, and remote sensing community. A literature review aimed at generating an inventory of landslide-affected glaciers globally is the first step. This will be complemented by detailed analyses and quantification of landslide-induced changes in glaciers’ behaviour by selecting benchmark case studies across different glacial systems representing different environmental conditions. Acquiring UAV data (0.05-0.10 m), high resolution (0.3-1.0 m) (Pleiades, WorldView, etc.), and medium resolution (10-50 m) satellite imagery (Landsat, Sentinel, Aster) will be essential for the quantification of changes in glaciers velocity and mass balance. We also plan field visits to benchmark glaciers to ground-truth remote sensing data and collect information about sedimentological and geomorphological characteristics of landslide deposits.

This research was funded by the National Science Centre, Poland, project number 2021/42/E/ST10/00186

How to cite: Bhattacharyya, A., Ewertowski, M., Małecki, J., and Domej, G.: Quantification of landslide-induced changes in glacier dynamics – project outline, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3491, https://doi.org/10.5194/egusphere-egu24-3491, 2024.

EGU24-3632 | ECS | Posters on site | GM10.4

Insights from Cirque Floor Altitudes in the Western Putorana Nature Reserve, Russian Federation 

Ethan Lee and Rachel Oien

This study presents the first palaeoglacial assessment of the mountainous terrain in the western region of the Putorana Nature Reserve, Russian Federation. This exploration, the first of its kind in this region, focuses on approximately 200 cirques, utilising cirque floor altitudes as a proxy for Equilibrium Line Altitudes (ELAs) as a pivotal palaeoclimate indicator. The primary objective is to gain unprecedented insights into the last glacial advancement in the area and to contribute to our understanding of the palaeoclimate during the potential Last Glacial Maximum (LGM) in Russia.

Employing the Ohmura equation, this research aims to construct a comprehensive palaeo climate profile, with ELAs estimated from cirque floor altitudes. These cirques are systematically mapped using the 10 m Arctic DEM and reconstructed using the GlaRe tool. Additionally, the physical parameters of the cirques will be rigorously evaluated using the newly developed ACME2.0 tool. By concentrating on the last glacial advancement, this study seeks to provide valuable information about the palaeoclimatic conditions and glacial dynamics within the Western Putorana Nature Reserve. This offers the first insights into the understanding of the mountain glacial history of the region.

How to cite: Lee, E. and Oien, R.: Insights from Cirque Floor Altitudes in the Western Putorana Nature Reserve, Russian Federation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3632, https://doi.org/10.5194/egusphere-egu24-3632, 2024.

Knowledge of subglacial conditions is of great relevance in understanding glacier dynamics. A combination of micro- and macrosedimentological analysis of diamictons and deformation structures can form the basis for the reconstruction of past subglacial conditions. We present the results of such a study on subglacial tills, within an Alpine environment, at Einödgraben in the Kitzbühel Alps (Tyrol/Austria). The Late Pleistocene succession there (MIS 5d-MIS 2) shows great diversity in facies from wood-bearing alluvial to glaciolacustrine to subglacial deposits. Two glaciogenic diamictons (tills) within the sequence were analysed at the microscale and are correlated to the Last Glacial Maximum (LGM; Würmian Pleniglacial) and the early Lateglacial phase of ice decay. The first deformation phase of pre-LGM deposits occurred most likely in a subglacial setting close to the advancing glacier margin and resulted in diapir-like glaciotectonic macro-structures, which are unique for an inneralpine area. Subglacial erosion over these structures occurred and later pre-LGM emplaced deposits underwent deformation and partial homogenisation immediately beneath the glacier base leading to diamictons, indicative of subglacial deformable bed conditions. The tills of the LGM and the Würmian Lateglacial show a range of microfacies and deformation structures evidence of close and rapid changes in till rheology and stress field dynamic in the subglacial environment. Our study demonstrates the need for a reinvestigation of deposits occurring in the proximity of past active ice interfaces. The paleoglaciological evidence assembled from the detailed and spatially close research on the microsedimentology of till at Einödgraben reflects our increasing comprehension and understanding of till microsedimentology in Alpine environments. An awareness is also shown of the need for much further research on the glacial depositional mechanics in mountainous terrains that are different from those in the immense lowland plains of the extensive paleo-ice sheets of North America and Northern Europe.

How to cite: Reitner, J. M. and Menzies, J.: Till formation and subglacial deformation in a stratigraphic complex Late Pleistocene sequence (Einödgraben / Aurach, Kitzbühel Alps, Austria), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4566, https://doi.org/10.5194/egusphere-egu24-4566, 2024.

Subglacial hydrology has been shown to significantly influence ice sheet dynamics in both Greenland and Antarctica.  Though direct observation and study of the subglacial hydrological network is limited by the presence of thick overlying ice, insights into subglacial hydraulics can be gained by studying landforms derived from meltwater in deglaciated landscapes.  Murtoos and meltwater corridors are examples of meltwater derived landforms, the former being triangular-shaped hills flanked by shallow troughs, and the latter being broad, shallow landforms with clear erosional boundaries and distinct internal morphologies.  While meltwater corridors have been previously identified in British Columbia, this study represents the first identification and study of murtoos associated with the Cordilleran Ice Sheet.  We identified a large network of murtoos and meltwater corridors in south-central British Columbia and studied both the morphology and internal composition of both landform groups using high resolution elevation data and near surface geophysical surveys. Electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) surveys on different murtoos reveal a homogeneous internal composition of sandy diamicton, while the troughs lateral to murtoos contain sorted sediment.  We interpret the murtoos as subglacial meltwater erosional remnants, their morphology determined by meltwater erosion of the lateral troughs.  The meltwater corridors studied contain two distinct morpho-stratigraphic relationships: channelized reaches exhibiting shallow intersecting and/or parallel troughs floored by sandy diamicton, the residuals resembling glacial curvilineations; and flat bed reaches with narrow eskers composed of fine sand and gravel.  We interpret the channelized and flat bed reaches as being formed by subglacial meltwater erosion and deposition, respectively, with the switch in process and form being determined by bed topography.  Together, these landforms suggest extremely wet-bed conditions during deglaciation of the Cordilleran Ice Sheet, with widespread subglacial meltwater erosion and deposition.  These observations provide insight into the likely conditions beneath portions of the Greenland and/or Antarctic ice sheets where widespread meltwater production has been reported, such as the western land terminating portion of the Greenland Ice Sheet.

How to cite: Sodeman, A. and Brennand, T.: Morphology and Composition of Murtoos and Meltwater Corridors Associated with the Cordilleran Ice Sheet in South-Central British Columbia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4704, https://doi.org/10.5194/egusphere-egu24-4704, 2024.

EGU24-6044 | Orals | GM10.4 | Highlight

A landform-driven simulation of deglaciation of the Scandinavian Ice Sheet and the PalGlac project’s progress on data-modelling integration 

Chris Clark, Jeremy Ely, Anna Hughes, Rosie Archer, Ben Boyes, Frances Butcher, Nico Dewald, Chris Diemont, Helen Dulfer, and Sarah Bradley

The field of palaeo-glaciology has evolved from inquisitiveness about glaciated landscapes - how they came into being - into the wider role of improving glaciological understanding and more recently, into testing or improving the fidelity of ice sheet modelling approaches. Such endeavors are crucial for improving forecasts of today’s diminishing polar ice sheets and for predicting sea-level rise. The PalGlac project (2018 to 2024) is using glacial landform mapping and analysis to advance our understanding of ice sheets, and in this talk, we will focus on the demise of the Scandinavian Ice Sheet and how landform data is used to either test or calibrate (nudge) ice sheet modelling simulations.

Glacial landforms such as drumlins, moraines, meltwater channels and eskers record spatially extensive components of ice sheet activity, namely 1) ice flow geometry and thermal regime, 2) the pattern of ice-marginal recession, and 3) the subglacial flow of meltwater that likely modulated the first two. High-resolution (metres) digital elevation models (DEMs) are revolutionising the mapping and understanding of glacial landforms (Johnson et al. 2015). They permit detailed investigation across areas so large as to have been unimaginable decades ago. We here report on a multi-person mapping investigation of glacial landforms across the land areas of Fennoscandia, northern Europe, and parts of Russia, and which have yielded over 350,000  individual features recording ice flow (250,000), ice margins (70,000), and meltwater routing (30,000). All data, held in a GIS, are used to build a first-order reconstruction of the pattern of ice flow changes and ice margin retreat. Much of these data reveal a useful confirmation and replication of prior studies, which we now know with improved robustness, and with many new aspects being revealed, notably in ice divide positions.

Our ultimate aim is to build a simulation of whole ice sheet growth and decay incorporating changes in ice thickness and flow geometry and tracking successive ice-marginal positions. This is being achieved using the mapped landform data along with chronological data (Hughes et al. 2016), glacio-isostatic constraints and other constraints from the literature and comparing them with ice sheet modelling simulations using PISM (Winkelmann et al. 2011). We focus on using identified empirical changes in ice flow geometry (from the landforms) to choose between dozens of alternate ensemble ice sheet model simulations. The challenge is to build a three-dimensional simulation of ice sheet evolution that is physically well-founded that satisfies most of the flow geometry changes, and fits within empirically defined ice marginal positions.

 

References

Johnson, M.D., Fredin, O., Ojala, A.E.K., Peterson, G., 2015: Unraveling Scandinavian geomorphology: the LiDAR revolution. GFF 137, 245-251.

Hughes, A.L.C., Gyllencreutz, R., Lohne, Ø.S., Mangerud, J., Svendsen, J.I., 2016: The last Eurasian ice sheets--a chronological database and time-slice reconstruction, DATED-1. Boreas 45, 1–45.

Winkelmann, R., Martin, M.A., Haseloff, M., Albrecht, T., Bueler, E., Khroulev, C., Levermann, A., 2011: The Potsdam parallel ice sheet model (PISM-PIK)--Part 1: Model description. The Cryosphere 5, 715–726.

How to cite: Clark, C., Ely, J., Hughes, A., Archer, R., Boyes, B., Butcher, F., Dewald, N., Diemont, C., Dulfer, H., and Bradley, S.: A landform-driven simulation of deglaciation of the Scandinavian Ice Sheet and the PalGlac project’s progress on data-modelling integration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6044, https://doi.org/10.5194/egusphere-egu24-6044, 2024.

EGU24-6551 | Posters on site | GM10.4

Geomorphological and sedimentological records of Greenland Ice Sheet advance and retreat on the continental shelf offshore of NE Greenland during the last glaciation 

Colm O'Cofaigh, Dave Roberts, S. Louise Callard, Jerry Lloyd, Georgia Ware, Katharina Streuff, Stewart Jamieson, Boris Dorschel, and Torsten Kanzow

Marine geophysical data combined with radiocarbon dated sediment cores provide a record of the advance and retreat of the ancestral Northeast Greenland Ice Stream (NEGIS) across the continental shelf offshore of NE Greenland during the last glaciation. Today, NEGIS is the largest ice stream to drain the Greenland Ice Sheet (GrIS), holding a sea-level equivalent of 1.1-1.4 m. However, the longer-term history of the ice stream, especially on the adjoining outer continental shelf has, to date, been poorly constrained. Streamlined subglacial landforms record grounded ice flow in the outer shelf section in cross shelf bathymetric troughs, with mega-scale glacial lineations recording former streaming flow towards the shelf edge. Flow transverse landforms in the form of downlow-tapering, sediment wedges occur at the shelf edge and on the outer-mid shelf of the bathymetric troughs. These landforms differ in their morphology from the classic ‘ramp-step’ form of typical grounding wedges but are similarly interpreted as a form of grounding-zone wedge in which sediment prograded and thinned away from the grounding-zone. The wedges record a shelf-edge terminating, grounded ancestral NEGIS, as well as the subsequent episodic retreat of the ice stream inshore during deglaciation. Beyond the shelf edge, glacigenic debris flows imaged on acoustic stratigraphic profiles and recovered in sediment cores document sediment delivery onto the slope; such deposits are typical of submarine slopes offshore of shelf-edge terminating palaeo-ice streams. On the outer shelf subglacial tills and grounding-zone proximal sediments overlain by deglacial stratified glacimarine sediments record ice stream advance and retreat in the troughs. Radiocarbon dates from glacimarine sediments in these cores indicate early deglaciation from the shelf edge but with relatively slow rates of subsequent ice-stream retreat across the outer shelf.

How to cite: O'Cofaigh, C., Roberts, D., Callard, S. L., Lloyd, J., Ware, G., Streuff, K., Jamieson, S., Dorschel, B., and Kanzow, T.: Geomorphological and sedimentological records of Greenland Ice Sheet advance and retreat on the continental shelf offshore of NE Greenland during the last glaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6551, https://doi.org/10.5194/egusphere-egu24-6551, 2024.

EGU24-7690 | ECS | Orals | GM10.4

Glacial history of the King Haakon Trough System, sub-Antarctic South Georgia 

Katharina Streuff, Nina-Marie Lešić, Gerhard Kuhn, Miriam Römer, Sabine Kasten, and Gerhard Bohrmann

In an effort to elucidate an important part of the Quaternary evolution of sub-Antarctic South Georgia, hydroacoustic data from its southern continental shelf are presented. The island with its surrounding shelf is of key interest for climate reconstructions, because it is located within the core belt of the Southern Westerlies and between the main fronts of the Antarctic Circumpolar Current in the Southern Ocean. This makes it particularly susceptible to changes in climate conditions on a local, regional, but also Southern Hemisphere-wide scale.

The data provide new insights into the glacial evolution of the King Haakon Trough, one of several cross-shelf trough systems around the island. Numerous landforms, identified from high-resolution bathymetry data, document phases of ice advance and retreat. They are interpreted to be related to the confluence of two major trunk glaciers fed by an extended, possibly warm-based, South Georgia Ice Cap. Linear bedforms become progressively elongated towards the shelf and imply accelerated ice flow and/or softer sediment substrate towards the shelf edge. In contrast, recessional moraines and large morainal banks not only evidence shelf-wide ice extent during a peak glaciation, but also attest to staggered retreat, at least during the initial phase of deglaciation. The establishment of a complex bottom-current system around the onset of the last deglaciation is implied by the presence of moats and contourite drifts, which are mainly recorded in sub-bottom profiler data from the trough system. These data also show an acoustically semi-transparent facies of variable thickness present on the mid- and outer shelf as basal trough fill, which, on the basis of its acoustic appearance and the presence of several strong internal reflectors, is interpreted as a sequence of stacked glacial tills. These are similar to stacked tills previously documented from the Antarctic Peninsula and probably document a minimum of three extensive ice advances around South Georgia. Because the tills in the King Haakon Trough occur over a distance of ~26 km across the shelf, it is postulated that they derive from a minimum of three separate glaciations, rather than from re-advances within one glaciation period. Accordingly, the new findings from the combined bathymetry and sub-bottom profiler data show that the marine-geological archives around South Georgia offer unique potential to constrain how ice masses in the Southern Ocean responded to Quaternary climate change.

How to cite: Streuff, K., Lešić, N.-M., Kuhn, G., Römer, M., Kasten, S., and Bohrmann, G.: Glacial history of the King Haakon Trough System, sub-Antarctic South Georgia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7690, https://doi.org/10.5194/egusphere-egu24-7690, 2024.

EGU24-9282 | ECS | Posters on site | GM10.4

AlpIce - Towards an Alps-wide database of empirical geo(morpho)logical and geochronological data constraining Last Glacial Maximum to Holocene glacier fluctuations 

Sarah Kamleitner, Tancrède P. M. Leger, Susan Ivy-Ochs, Samuel U. Nussbaumer, Andreas Vieli, and Guillaume Jouvet

Latest advances in numerical modelling using machine learning sped-up glacier models by several orders of magnitude, thus facilitating glacier evolution models to run at high resolutions (hundreds of metres) over timescales of several tens of millennia and over mountain range scales. The RECONCILE project seeks to use the Instructed Glacier Model (IGM) to simulate the maximum state and deglaciation of the last glaciation of the European Alps and to test model output against the geological record. A robust framework against which to test Alps-wide and transient paleoglacier model simulations is however missing. Despite the long history of Quaternary research in the Alps and abundant publications on the topic, the integration of field evidence for model validation has thus far largely been restricted to the Last Glacial Maximum (LGM) ice extent. Inspired by work on the (former) British, Fennoscandian, Patagonian and Greenland ice sheets, we aim to build a comprehensive and standardized dataset on paleoglacier variations for the European Alps. Coupling geo(morpho)logical data and geochronological markers, the AlpIce database will act as an empirical basis for future quantitative model-data comparisons. Published empirical evidence that restrains the build-up, culmination, and disintegration of the Alpine LGM glaciers as well as subsequent Alpine Lateglacial and Holocene glacier advances are considered. Relevant surface exposure and radiocarbon datings are currently gathered and fed into the database. Data reliability assessments and paleoglaciological context classifications are undertaken concurrently. The database structure also allows the inclusion of additional chronological methods (e.g. luminescence dating, dendrochronology, archeological and historical sources) into AlpIce. Where applicable, the chronological constraints will be linked to related geo(morpho)logical features (e.g. former ice margins, trimlines) using GIS software. AlpIce is designed as an open-access resource hoping to prove useful for both empirical and modelling communities and beyond the scope of model validation.

How to cite: Kamleitner, S., Leger, T. P. M., Ivy-Ochs, S., Nussbaumer, S. U., Vieli, A., and Jouvet, G.: AlpIce - Towards an Alps-wide database of empirical geo(morpho)logical and geochronological data constraining Last Glacial Maximum to Holocene glacier fluctuations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9282, https://doi.org/10.5194/egusphere-egu24-9282, 2024.

EGU24-9498 | ECS | Orals | GM10.4

Reconstructing the Enns valley in the course of the ice ages based on findings on Gröbminger Mitterberg (Austria) 

Gerit E.U. Griesmeier, Jürgen M. Reitner, Daniel P. Le Heron, Christopher Lüthgens, and Gustav Firla

Within the Alps, the erosive effects of glaciers during the Last Glacial Maximum (LGM) means that evidence for earlier glaciations is rare. At Gröbminger Mitterberg (GM), traces of the history prior to the LGM are conserved below a layer of basal till of the LGM. The GM itself is a flat-topped hill located in the Enns valley in Styria (Austria), rising to an elevation of ca. 200 m above the Enns valley floor. It is situated between Mesozoic carbonates in the north and crystalline basement units in the south. The GM comprises crystalline basement covered by fluvial and deltaic sediments, overlain by a subglacial till. Based on the distribution of the sediments, borehole data and geoelectric data, an ancient river channel across GM can be reconstructed. 
The lithological spectrum of the fluvial and deltaic sediments at GM shows that the distribution of material from the south and the north is around 70 : 30 % throughout the GM, which is the same as that of the modern Enns river. This suggests that all sediments at GM and the channel across it were greatly impacted by the Enns river. The Enns valley in the area of GM can now be reconstructed as follows:
Some time before the Riss Glaciation (MIS 6), the Enns river meandered in a valley, situated at an elevation ca. 100 m higher than the present-day river. Large alluvial fans flowing northward into the Enns valley forced the Enns river to flow across Mitterberg in a channel, which was probably already partly created during earlier glaciations. The first crystalline pebbles reached the north of GM. During the phase of ice decay of the Riss Glaciation, ice marginal lakes developed at the margin of GM, where deltaic sediments developed. After the Riss Glaciation, the Enns river found itself in a similar situation like today and the Enns valley aggraded until it reached the top of GM shortly before the last glaciation. Large alluvial fans further east dammed a lake, which covered GM and was quickly filled with sediments. This part of the chronology is also supported by optically stimulated luminescence data using single grains of potassium-rich feldspar. They will be presented at the conference. The braided Enns valley was not only much wider than today, but also transported crystalline pebbles to the northern part of GM. In the course of the LGM, most of the previously deposited sediments were preserved and covered by basal till. 
The evolution of the Enns valley emphasises the close coupling between climate, erosion and sedimentation processes. Today, the Enns river incises again and sediments at GM are going to be eroded, but parts remain in their position. These current changes have probably repeatedly occurred through time and we can never be sure, how much time is really preserved on GM. Nevertheless, the proposed reconstruction in the Enns valley can also give hints on the history of other alpine valleys and may be helpful for future models of alpine wide glaciation and greenhouse phases.

How to cite: Griesmeier, G. E. U., Reitner, J. M., Le Heron, D. P., Lüthgens, C., and Firla, G.: Reconstructing the Enns valley in the course of the ice ages based on findings on Gröbminger Mitterberg (Austria), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9498, https://doi.org/10.5194/egusphere-egu24-9498, 2024.

EGU24-10169 | ECS | Posters on site | GM10.4

Field observations of interlinked subglacial cavities in Kangerlussuaq - Greenland ice sheet western margin. 

Anna Grau Galofre and Axel Noblet

The glacial hydrology and stability to sliding episodes of the Greenland Ice Sheet (GIS) are closely linked to the subglacial drainage capacity of its bed, which depends on its structure and connectivity. The central-western portion of the GIS, specifically in the region around Kangerlussuaq, is characterized by subglacial drainage systems consisting on meltwater-filled cavities on a hard bed (Harper et al., 2017), which may become interconnected following episodes of increased discharge. Episodes of connectivity following high pressure subglacial meltwater events may lead to enhanced sliding followed by channelization, and emplacement of subglacial floods (Harper et al., 2017).

We present preliminary field and remote sensing observations describing the morphology, topology, organization, and other field characteristics of recently exposed elements of the glacial hydrology system, which were emplaced by the western margin of the GIS. Our field site is located by the Europlanet Transnational Access TA1 Facility 4: Greenland-Kangerlussaq, which offers a unique opportunity to study the subglacial drainage patterns in this region (Carrivick et al., 2016). Few regions in the world offer the opportunity to study recently emplaced, well exposed subglacial morphologies at the level of accessibility of this site. Field data includes in situ-imagery, observations of glacial sliding directions, description of sedimentary deposits, morphology, scale and characteristics of subglacial cavities, and nature of the connection passages. Data acquired in the field is complimented with remote sensing data from the ArcticDEM and Maxar imagery.

We conclude with a discussion of the implications of our observations for the geometry and volumetric capabilities of currently active subglacial hydrology pathways under the western portion of the GIS, including addressing the possible modes of meltwater drainage from the observed morphologies and subglacial geological reconstructions (e.g., White et al., 2016), as well as a comparison of the morphology and geometry of observed interconnected subglacial cavities to morphologically and topologically similar systems located at the east of Hellas Basin on Mars. 

How to cite: Grau Galofre, A. and Noblet, A.: Field observations of interlinked subglacial cavities in Kangerlussuaq - Greenland ice sheet western margin., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10169, https://doi.org/10.5194/egusphere-egu24-10169, 2024.

EGU24-11008 | ECS | Posters on site | GM10.4

Application of a new statistically rigorous comparison tool of observed and modelled flow directions of the last British-Irish ice sheet over time 

Rosie Archer, Jeremy Ely, Timothy Heaton, Frances Butcher, Anna Hughes, and Chris Clark

Past ice flow direction can be inferred through mapping of subglacial lineations (e.g. drumlins and mega-scale glacial lineations). A numerical ice sheet model can also be used to reconstruct possible ice flow directions according to ice physics. These two methods are rarely integrated to see if the model can explain the observational data. Previous model-data comparison workflows made a large step forward. However, they lack statistical rigour and certain capabilities, such as comparing an ensemble of model simulations. To overcome these challenges, we created the Likelihood of Accordant Lineations Analysis (LALA) tool.  LALA is a tool to compare numerical model ice sheet simulations to observational data of past flow direction. LALA was created to take a step forward in improving model-data comparisons; making comparisons statistically rigorous and adding the ability to directly grade multiple simulations against each other, a feature that was missing from previous tools. For this poster, we show an example of the tool in action and use LALA to compare model simulations of the British-Irish ice sheet and observations of flow direction from subglacial lineations taken from the BRITICE-CHRONO project. We present the best and the worst fitting simulations according to LALA. We also dissect the score produced to give an indication of the flow directions which are most (and least) regularly matched by the numerical modelling. These results highlight opportunities for model development and the potential to reevaluate observations.

How to cite: Archer, R., Ely, J., Heaton, T., Butcher, F., Hughes, A., and Clark, C.: Application of a new statistically rigorous comparison tool of observed and modelled flow directions of the last British-Irish ice sheet over time, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11008, https://doi.org/10.5194/egusphere-egu24-11008, 2024.

EGU24-11208 | Orals | GM10.4

Tracking sediment transport through the Miage Glacier, Italy, combining a Lagrangian approach with luminescence burial dating of englacial clasts 

Audrey Margirier, Ann Rowan, Julien Brondex, Georgina E. King, Christoph Schmidt, David L. Egholm, Vivi K. Pedersen, C. Scott Watson, Remy Veness, Leif Anderson, and Benjamin Lehmann

 

Constraining the pathways and time scales of englacial sediment transport is of primary importance for both understanding the processes that move sediment through glacierised catchments and quantifying the response of mountain glaciers to climate change. However, sediment transport through glaciers is a more complex process than ice flow and difficult to observe; clasts can be transported englacially and at the ice margins, but also deposited into moraines before being re-entrained into englacial transport.

We developed a novel method taking a Lagrangian approach that combines luminescence rock surface burial dating of the time for englacial transport of individual rock debris with ice-dynamical glacier evolution modelling of glacial sediment transport to quantify rates of sediment transport through the Miage Glacier catchment in the Italian Alps. Luminescence rock surface burial dating allows determining the burial duration of rocks after they have been exposed to sunlight, but this method has not previously been applied to englacial clasts.

We obtained luminescence ages for seven samples embedded in the ice in the ablation zone of Miage Glacier, with burial ages ranging from 0.2 ± 0.1 ka to 5.0 ± 1.4 ka. Samples collected in the upper part of the ablation zone yield younger ages than samples collected near the terminus. The younger luminescence ages (0.2 ± 0.1 ka and 0.3 ± 0.1 ka) are consistent with expected burial duration based on the present-day glacier velocity. In contrast, older luminescence ages obtained for samples located in the lower part of the ablation zone (1.2 ± 0.1 ka to 5.0 ± 1.4 ka) show that these samples record a longer and more complex burial history, suggesting that these samples were either stored in the headwall area or within moraines for several thousand years before being entrained in the ice. In the Miage catchment, debris could have been stored in a moraine at the junction between the Bionnassay Glacier and the Dome Glacier before being entrained in the Miage glacier. We compare the burial ages of the englacial clasts with simulations of glacial sediment transport using a Lagrangian particle tracking scheme in the glacier model iSOSIA. The model results illustrate the range of englacial and subglacial sediment flow paths through the Miage Glacier and simulate similar durations of englacial transport to those obtained for our luminescence samples.

How to cite: Margirier, A., Rowan, A., Brondex, J., King, G. E., Schmidt, C., Egholm, D. L., Pedersen, V. K., Watson, C. S., Veness, R., Anderson, L., and Lehmann, B.: Tracking sediment transport through the Miage Glacier, Italy, combining a Lagrangian approach with luminescence burial dating of englacial clasts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11208, https://doi.org/10.5194/egusphere-egu24-11208, 2024.

EGU24-11358 | ECS | Orals | GM10.4

Quantitative CT scan analysis: an innovative tool for interpreting ice-contact sediments from overdeepened basins of the northern Alpine foreland 

Bennet Schuster, Sebastian Schaller, Lukas Gegg, Marius W. Buechi, Flavio S. Anselmetti, and Frank Preusser

Overdeepened basins are shaped and filled by the interplay of erosion and deposition during one or more glacial-interglacial cycles. Understanding and correlating the sedimentary infill of overdeepened systems is a key to understanding glacial dynamics in terms of the timing, extent, and character of Quaternary glaciations. Therefore, numerous overdeepened structures in the northern Alpine foreland have been explored by research drilling in recent years, resulting in a large collection of sediment cores of excellent quality, providing a unique opportunity to gain insight into these structures. Exploration of these basins shows that a depositional sequence in the sedimentary record of a glacial overdeepening typically begins with the subglacial deposition of coarse-grained units (diamicts and gravels), reflecting complex ice-bed-interactions during the transition from erosion to deposition. The identification and interpretation of these potential ice-contact sediments is crucial for understanding the glacial sedimentary sequences.

In this study, we use X-ray computed tomography (CT) scanning to identify and quantify sedimentological features and systematically characterise a wide range of potential ice-contact sediments from different levels within the sedimentary record of several overdeepened basins in the northern Alpine foreland. CT scanning provides a powerful tool for the detailed analysis of sedimentary drill cores, particularly in these glacial sediments, where such examinations have never been carried out on a large scale. This study aims to establish a CT analysis workflow and a database of characteristics of ice-contact sediments. This will contribute to the controversial discussion of the relevant processes that form ice-contact sediments and improve our ability to identify ice-contact sediments and their genesis in overdeepened basins.

How to cite: Schuster, B., Schaller, S., Gegg, L., Buechi, M. W., Anselmetti, F. S., and Preusser, F.: Quantitative CT scan analysis: an innovative tool for interpreting ice-contact sediments from overdeepened basins of the northern Alpine foreland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11358, https://doi.org/10.5194/egusphere-egu24-11358, 2024.

EGU24-11858 | ECS | Posters on site | GM10.4

Geomorphological Analysis of Cirques in the Western Islands of Greenland 

Rachel Oien and Bartosz Kurjanski

This study employs Arctic DEM data and GIS tools, ACME 2.0 (Li et al., 2024), and GlaRe (Pellietero et al., 2016), to systematically investigate cirques in the western islands off central Greenland. The primary objective is to reconstruct past Equilibrium Line Altitude (ELA) variations at the end of the Younger Dryas period and derive insights into palaeoclimate conditions in this region.

By leveraging high-resolution Arctic DEM datasets and advanced GIS methodologies, we analyse cirque morphologies and elevations to reconstruct ELAs, a key indicator of glacial development and climate conditions. The Younger Dryas, a well-documented, abrupt and relatively short climatic event, represents a critical period for understanding past climate dynamics and their impact on glacial landscapes on a timescale relevant to the contemporary human population.

Our approach combines the semi-automated extraction of cirque parameters from the Arctic DEM with GIS-based modelling to reconstruct palaeo-ELA variations. Through spatial and temporal analysis, we aim to discern patterns of glacial response to climatic shifts between 13-9.5ka (Leger et al., 2024), shedding light on the sensitivity of Arctic cirques to rapid environmental changes.

Preliminary results indicate distinct patterns in cirque morphology and ELAs consistent with variations in the ELA during the Younger Dryas. These findings contribute to a more comprehensive understanding of the regional impact of past climatic events on the Greenlandic glacial landscape. This research enhances our knowledge of the Younger Dryas climate dynamics in the western islands off Greenland, providing valuable insights into the region's palaeoclimate history and contributing to broader discussions on Arctic environmental change.

How to cite: Oien, R. and Kurjanski, B.: Geomorphological Analysis of Cirques in the Western Islands of Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11858, https://doi.org/10.5194/egusphere-egu24-11858, 2024.

EGU24-11985 | ECS | Posters on site | GM10.4 | Highlight

Luminescence rock surface dating of englacial transported debris from Mer de Glace glacier, French Alps 

Léa Rodari, Audrey Margirier, Georgina King, Ann Rowan, Christoph Schmidt, and Guillaume Jouvet

Significant mass loss and increased rock debris cover have been observed across many mountain glaciers due to climate change. However, the dynamics of sediment transport through alpine glaciers are not fully understood and should be investigated to better constrain the future evolution of mountain glaciers under a changing climate. Englacial sediment transport is difficult to observe and to that end, we quantify the englacial transport time of debris within a glacier using a novel method combining luminescence rock surface burial dating and ice-flow modelling. Our study focuses on Mer de Glace, Mont Blanc Massif, French Alps, where supraglacial debris has expanded over the past 20 years.

We collected near-surface rock debris (4–22 cm in diameter) of granite from the ablation area of Mer de Glace that we expect to have experienced different englacial transport durations. Under subdued red light, we cored the samples perpendicular to their surfaces and sliced the cores into ~1 mm discs for luminescence dating. We first evaluated whether the luminescence signals had been well bleached prior to deposition by measuring the evolution of luminescence signals with depth throughout the core (i.e. measurement of the bleaching plateau). We used a protocol comprising infra-red stimulation at 50 °C and 225 °C, followed by blue stimulation at 125 °C to explore the signals of different minerals with different luminescence properties. Of the 29 samples investigated, 20 were well bleached, exhibiting a clear plateau in luminescence signals with depth (following the approach of Rades et al., 2018). We are currently using a single-aliquot regenerative dose protocol to date the rock surfaces of these samples to obtain englacial transport durations. In the next step, we will contrast the englacial transport durations measured using luminescence with those predicted using the ice-flow model IGM (Jouvet et al., 2022), allowing us to better understand the dynamics of mountain glaciers over centennial to millennial time scales.

 

References

Jouvet, G., Cordonnier, G., Kim, B., Lüthi, M., Vieli, A., & Aschwanden, A. (2022). Deep learning speeds up ice flow modelling by several orders of magnitude. Journal of Glaciology68(270), 651-664.

Rades, E. F., Sohbati, R., Lüthgens, C., Jain, M., & Murray, A. S. (2018). First luminescence-depth profiles from boulders from moraine deposits: Insights into glaciation chronology and transport dynamics in Malta valley, Austria. Radiation Measurements120, 281-289.

How to cite: Rodari, L., Margirier, A., King, G., Rowan, A., Schmidt, C., and Jouvet, G.: Luminescence rock surface dating of englacial transported debris from Mer de Glace glacier, French Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11985, https://doi.org/10.5194/egusphere-egu24-11985, 2024.

EGU24-12152 | ECS | Orals | GM10.4

Geomorphic evidence for along-margin ice flow from Melville Bugt slope, west Greenland 

Shannon Klotsko, Rob Hatfield, Brendan Reilly, Alan Mix, Anne Jennings, Erin Gregory, Joe Stoner, Maureen Walczak, Jonas Donnenfield, Cara Fritz, Alice Hough, Robert Kelleher, Lindsay Monito, Paloma Olarte, Megan Siragusa, Katherine Stelling, and Tobias Vonahme

In summer 2023, the Baffin Bay Deglacial Experiment (BADEX) completed a 33-day cruise focused on the west Greenland margin; the overarching goal of this project is to investigate the evolving ocean and ice conditions along the west Greenland ice sheet from the last glacial maximum through the deglaciation. The cruise collected seafloor and sub-seafloor data, as well as water and plankton samples, with the aim of establishing 1) the timing and extent of warm Atlantic water incursion along the north-western Greenland margin; 2) the phasing of the initial ice margin retreat relative to oceanic and atmospheric changes; 3) the role of local or regional ice shelves in buttressing trough-bound outlet glaciers; and 4) the influence of regional geology, geomorphology, and ice dynamics on ice-margin retreat. Here, we present results from the ~600 km of new multibeam sonar data collected on the slope just north of the Melville Bugt trough mouth fan (TMF). The margin in this area curves landward, forming a crescent-shaped, submarine amphitheater that contains a range of bathymetric features, which vary in form with water depth and their proximity to the TMF. This includes a series of contour-following ridges that occur in depths from ~1000 to ~450 meters below modern water level. These ridges are more prominent farther away from the TMF but are more numerous closer to the trough. They are interpreted to be of glaciogenic origin, potentially formed by an ice shelf, fed by the trough, that flowed to the north and grounded on the slope. These ridges and other bathymetric features, extending up to 2000 meters water depth will be discussed. These results add to our understanding of the ice margin configuration in northern Baffin Bay during and after the last glacial period.  

How to cite: Klotsko, S., Hatfield, R., Reilly, B., Mix, A., Jennings, A., Gregory, E., Stoner, J., Walczak, M., Donnenfield, J., Fritz, C., Hough, A., Kelleher, R., Monito, L., Olarte, P., Siragusa, M., Stelling, K., and Vonahme, T.: Geomorphic evidence for along-margin ice flow from Melville Bugt slope, west Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12152, https://doi.org/10.5194/egusphere-egu24-12152, 2024.

EGU24-12758 | Posters on site | GM10.4

New surface exposure age data using cosmogenic radionuclides 10Be and 14C to constrain the age of the last deglaciation in the Retezat Mts, Southern Carpathians, Romania 

Zsófia Ruszkiczay-Rüdiger, Zoltán Kern, Balázs Madarász, Petru Urdea, Régis Braucher, Mihály Molnár, Botond Búró, and Aster Team

The presence of cosmogenic radionuclide concentrations inherited from previous exposure(s) of glacially transported boulders and moulded bedrock surfaces may hinder the determination of the surface exposure age (SED) of the last phase of (de)glaciation.

A previous study revealed that glacial landforms of the cirque area in the southern side of the Retezat Mountains (Southern Carpathians, Romania) hold significant amount inherited 10Be (t1/2=1.4 My), which was used for a tentative estimation of the amount of glacial erosion, assuming that the lowest 10Be concentration was representative of the true age of deglaciation (Ruszkiczay-Rüdiger et al., 2021, Geomorphology 384, 107719).

In this study, a western valley, the Zlătuia-Dobrunu valley of the Retezat Mts was sampled for 10Be SED. The novel data are in agreement with the previous datasets suggesting that the most extended glaciers belonged to the Last Glacial Maximum. However, the old apparent exposure durations based on 10Be analysis of samples from the cirque area provided firm evidence for the presence of excessive abundances of cosmogenic 10Be in this valley as well.

The use of the short-lived in situ produced 14C (t1/2= 5.7 ky) provides an independent age constraint for the timing of the last deglaciation, because all 14C inventories that might be inherited from a previous exposure would have already been decayed. As a consequence, the 14C concentrations are not biased by inheritance, thus i) enable the age determination of the landforms belonging to the last phases of deglaciation and ii) the 14C exposure ages compared to the 10Be data will allow an assessment of the inherited amount of 10Be and thus a more precise determination of the amount of glacial erosion.

In this study the new 10Be and 14C SED ages will be presented together with the mapped glacial landforms, reconstructed paleoglaciers and their Equilibrium Line Altitudes.

Funding: NKFIH FK124807, INSU/CNRS, ANR - “EQUIPEX Investissement d’Avenir”, IRD and CEA, the PNRR-III-C9-2022 - I8, no. 760055/23.05.2023, CF 253/29.11.2022. and Horizon 2020 grant 871149 ”EUROPLANET”.

How to cite: Ruszkiczay-Rüdiger, Z., Kern, Z., Madarász, B., Urdea, P., Braucher, R., Molnár, M., Búró, B., and Team, A.: New surface exposure age data using cosmogenic radionuclides 10Be and 14C to constrain the age of the last deglaciation in the Retezat Mts, Southern Carpathians, Romania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12758, https://doi.org/10.5194/egusphere-egu24-12758, 2024.

EGU24-13494 | ECS | Orals | GM10.4

First evidence and dating of Glacial Lake Yukon using paleomagnetic dating and cosmogenic nuclides 

Raphael Gromig, Brent Ward, Jeff Bond, Rene Barendregt, and Tibor Dunai

Yukon Territory has been repeatedly affected by the northern Cordilleran Ice Sheet during the last 2.6 million years, which has significantly affected the landscape. Yukon is unique in Canada in that it has three broad mappable chrono-geomorphic regions representing regionally coherent advances of the northern Cordilleran Ice Sheet and, unlike all other parts of Canada, a large unglaciated area. The oldest surface is a composite of several glaciations that are so old individual limits cannot be resolved. The oldest of these glaciations has occurred 2.6 million years ago and is believed to be responsible for shifting the route of the Yukon River.

Geological evidence suggests that the Yukon River, which now flows in northern/western direction into the Bering Sea, was initially flowing south into southwest Yukon and west into the Tanana River basin. Reversal of the Yukon River is believed to be a consequence of the onset of Northern Cordillera glaciations at the beginning of the Quaternary period. Glaciation of the St. Elias Mountains blocked the passage of the paleo-Yukon River and formed a glacially dammed lake. This lake covered an extensive area in central Yukon and then catastrophically drained after overtopping a threshold north of Dawson City. This formed the present route of the Yukon River flowing to the Bering Sea. The presence and timing of the formation of Glacial Lake Yukon has been subject of debate for several decades. However, this hypothesis was widely accepted despite the absence of physical evidence for the glacial lake.

The first physical evidence of Glacial Lake Yukon was discovered in 2022 when a succession of lake sediments was exposed in a placer mining operation in the Bonanza Creek Valley (tributary of the Klondike River) at the Lovett Hill site. The sampled section comprises more than 8 m of clays, silts and sands. This section is underlain by the Pliocene ‘White Channel gravel’, and the Quaternary Klondike outwash, with the latter representing first evidence of Quaternary glaciation in the Yukon. The lake sediment succession is overtopped by an erosive gravel unit, which likely marks the drainage of the lake.

In order to refine the regional glacial stratigraphy, we utilize a multidisciplinary approach to provide chronological control on the formation of Glacial Lake Yukon. This allows us to test the hypothesis that the reversal of the Yukon River and the formation of Glacial Lake Yukon are associated with the first large Cordilleran Ice Sheet. We combine paleomagnetic measurements and cosmogenic 26Al–10Be isochron dating. In addition, we test the utility of cosmogenic krypton on zircon grains in this setting. Initial paleomagnetic data indicate the lake sequence is reversely magnetized; this combined with a previous burial age of ca. 2.6 Ma for the initiation of Klondike outwash deposition, suggests deposition of the lake sediments during the Matuyama Chron (0.78 to 2.6 Ma). Cosmogenic nuclide data will further refine this age.

How to cite: Gromig, R., Ward, B., Bond, J., Barendregt, R., and Dunai, T.: First evidence and dating of Glacial Lake Yukon using paleomagnetic dating and cosmogenic nuclides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13494, https://doi.org/10.5194/egusphere-egu24-13494, 2024.

EGU24-13860 | Posters on site | GM10.4

Late Quaternary glacier-climate reconstruction in the Ahuriri River valley, Southern Alps of New Zealand 

Levan Tielidze, Shaun Eaves, Kevin Norton, Andrew Mackintosh, and Alan Hidy

I present the first dataset of Late Quaternary glacial maximum extent and deglaciation along with quantitative paleoclimate reconstructions from the Ahuriri River valley, Southern Alps, New Zealand. The new constraints based on geomorphological mapping and sixty-six cosmogenic 10Be surface exposure ages offer the opportunity to test hypotheses about the climate system, to better understand the processes that drove ice retreat and readvance during the Last Glacial Maximum and the subsequent glacial termination.

Reconstructions of past glacier geometries indicate that the local ELA was depressed by ~880 m and climate was 5±1 °C colder than present (1981–2010) at 19.8±0.3 ka, while ELA was depressed by ~770 m and climate was 4.4±0.9 °C colder at 16.7±0.3 ka. Subsequent estimations suggest ELA elevations at 14.5±0.3 ka, 13.6±0.3 ka, and 12.6±0.2 ka were ≤700 m, ≤630 m, and ~360 m lower than today. This equates to air temperatures of ≤3.9 °C, ≤3.5 °C, and 2.3±0.7 °C colder than today, assuming no changes in past precipitation.

The small amount of warming estimated in this study between 19.8±0.3 and 16.7±0.3 ka differs somewhat from glacial reconstructions in other major valleys in the Southern Alps, specifically from Rakaia River valley. Robust constraints of glacier changes in the Ahuriri valley between 14.5±0.3 and 12.6±0.2 ka confirm that an early glacier readvance occurred in New Zealand at this time, which has been previously recognised with only limited evidence. The reconstructed ELA suggests that the coldest part of the Late Glacial reversal occurred at 14.5±0.3 ka. 

How to cite: Tielidze, L., Eaves, S., Norton, K., Mackintosh, A., and Hidy, A.: Late Quaternary glacier-climate reconstruction in the Ahuriri River valley, Southern Alps of New Zealand, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13860, https://doi.org/10.5194/egusphere-egu24-13860, 2024.

EGU24-14426 | Orals | GM10.4 | Highlight

Reconstructing the deglacial dynamics of the northwestern Laurentide Ice Sheet  

Martin Margold, Benjamin J. Stoker, Helen E. Dulfer, Chris R. Stokes, Victoria H. Brown, Christopher D. Clark, Colm Ó Cofaigh, David J.A. Evans, Duane Froese, and Sophie L. Norris

The northwestern sector of the Laurentide Ice Sheet drained ice from the Cordilleran-Laurentide ice saddle and the Keewatin ice dome towards the ice margin on the arctic continental shelf during its late local Last Glacial Maximum. The glacial geomorphological and geological record of the region documents several massive palaeo-ice streams. However, the deglacial dynamics of this sector has not yet been reconstructed in detail and questions remain about the nature of deglaciation in this region: Did ice streams operate far up-ice or were they limited to a rather narrow ice-margin zone? Was ice stagnation widespread?

We reconstruct the deglaciation of the northwestern sector of the Laurentide Ice Sheet by glacial geomorphological inversion methods, based on our recent regional-scale mapping of the glacial geomorphological record. We find that the ice stream network evolved from large, marine-terminating ice streams to shorter, terrestrial ice streams. The ice drainage network experienced a reorganisation following the disappearance of the Cordilleran-Laurentide ice saddle, which previously feed ice in a northerly direction along the modern-day Mackenzie River, to more westerly ice flow sourced from the Keewatin ice dome. Deglaciation was dominated by dynamic ice retreat but we also find traces of localized ice stagnation in areas of higher ground fringing the major fast ice flow corridors. The ice flow pattern changed markedly once the ice front stepped back onto the Canadian Shield, where ice streaming largely ceased. This empirical reconstruction, fitted to the latest version of ice margin chronology, can serve as validation for numerical modelling efforts and provides information on broad-scale ice sheet dynamics during the last deglaciation. 

How to cite: Margold, M., Stoker, B. J., Dulfer, H. E., Stokes, C. R., Brown, V. H., Clark, C. D., Ó Cofaigh, C., Evans, D. J. A., Froese, D., and Norris, S. L.: Reconstructing the deglacial dynamics of the northwestern Laurentide Ice Sheet , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14426, https://doi.org/10.5194/egusphere-egu24-14426, 2024.

EGU24-15483 | Posters on site | GM10.4

The valley glacier network of the Valsugana (south-eastern Alps) during the LGM: Chronology and Equilibrium Line Altitudes  

Giovanni Monegato, Lukas Rettig, Sandro Rossato, Sarah Kamleitner, Susan Ivy-Ochs, Alessia Modesti, Francesco Gosio, Mirko Demozzi, Matteo Rinaldo, Enrico Marcato, Tommaso Trentini, Silvana Martin, and Paolo Mozzi

During the Last Glacial Maximum the Valsugana sector in the south-eastern European Alps was characterized by an extensive glacier network that included the large valley glacier belonging to the Adige glacier, through the transfluence in the Fersina area, and major tributaries from the Calamento and Cavè valleys. The glacier surface reached up to 1400 m a.s.l. in the western sector of the study area with a downstream gentle slope to the east. At Borgo Valsugana, the trunk glacier merged with several tributaries and flowed also towards the Tesino plateau to the east, where it merged with the tributary valley glacier. In the Tesino area, the glaciers flowed mainly to the south towards the major trunk glacier. This flowed downstream until Primolano, where the narrow reach of Canal del Brenta dammed its flow. The gorge promoted the bulging of the glacier front and its split into two lobes: the first to the south formed the lateral moraines of Enego and Col del Gallo ending with a seracs cascade; the second lobe to the east merged with the Cismon-Piave glacier. This latter was a major ice-field originated in the central Dolomites and reached its western frontal position above the Corlo gorge (Rossato et al., 2018).

 In this articulate network several nunataks remained ice-free; here, lateral moraines with erratic boulders mark the elevation of the trimline. At Mt. Lefre, three boulders were dated to the LGM with exposure dating method (10Be). These are the first exposure ages for an LGM glacier in the south-eastern Alps and can be compared to radiocarbon chronologies from other glaciated valleys

In the study area also independent glaciers (Mt. Agaro, Mt. Coppolo, Mt. Cavallara) developed. In the Prealps the large Altopiano dei Sette Comuni plateau glacier had a calculated Equilibrium Line Altitude (ELA) of 1680 m a.s.l. (Rettig et al., 2023), while the Monte Grappa ice cap had a calculated ELA of 1450 m a.s.l. (Baratto et al., 2003; Rettig et al., 2023). The ELA estimates allow insights into the climatic conditions under which the LGM glaciers in the Valsugana evolved.

 

References

Baratto A., Ferrarese F., Meneghel M., Sauro U. 2003. La ricostruzione della glaciazione Wurmiana nel Gruppo del Monte Grappa (Prealpi Venete). In: Biancotti, A., Motta, M. (Eds.), Risposta dei processi geomorfologici alle variazioni ambientali. Brigati G., Genova, pp. 67–77.

Rettig L., Monegato G., Spagnolo M., Hajdas I., Mozzi P. 2023. The Equilibrium Line Altitude of isolated glaciers during the Last Glacial Maximum – New insights from the geomorphological record of the Monte Cavallo Group (south-eastern European Alps). CATENA, 107187.

Rossato S., Carraro A., Monegato G., Mozzi P., Tateo F. 2018. Glacial dynamics in pre-Alpine narrow valleys during the Last Glacial Maximum inferred by lowland fluvial records (northeast Italy). Earth Surface Dynamics, 6, 809-828.

How to cite: Monegato, G., Rettig, L., Rossato, S., Kamleitner, S., Ivy-Ochs, S., Modesti, A., Gosio, F., Demozzi, M., Rinaldo, M., Marcato, E., Trentini, T., Martin, S., and Mozzi, P.: The valley glacier network of the Valsugana (south-eastern Alps) during the LGM: Chronology and Equilibrium Line Altitudes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15483, https://doi.org/10.5194/egusphere-egu24-15483, 2024.

EGU24-15554 | ECS | Orals | GM10.4

Early Pleistocene onset of glacial incision in the Baltic Basin revealed by 10Be-26Al burial dating of the Hattem Beds 

Kaleb Wagner, Lotta Ylä-Mella, Martin Margold, Mads Faurschou Knudsen, Freek Busschers, Marcel Bakker, Birte Lindahl Eriksen, Jesper Olsen, Jane Lund Andersen, and John Jansen

In Northwest Europe, the earliest presence of the Fennoscandian Ice Sheet (FIS) is registered in the Dutch-German border region, where fluvio-deltaic sediments of the ancient Eridanos river system contain weathered Nordic erratics within the so-called “Hattem Beds” (Upper Pieze Fm. [f.k.a. Lower member of the Enschede Fm.]). The Eridanos operated from the Early Miocene, integrating drainage across the east Fennoscandian Shield and Baltic Platform, until its headwaters were overridden by the FIS for the first time. The Hattem Beds, conventionally attributed to the Dutch Menapian Stage (~MIS 34; 1.1 Ma), mark the onset of glacial erosion within the Baltic Basin and termination of the Eridanos system.

Here we provide new sediment burial ages for this key stratum by exploiting the cosmogenic 10Be-26Al pair in quartz. We measure nuclide concentrations in archived drill-core samples obtained from the type locality at the Wapenveld quarry near Molenweg (NL), including those of the overlying Urk and underlying Lower Pieze Fms. (f.k.a. Harderwijk Fm).

Results with our Particle Pathway Inversion of Nuclide Inventories (P-PINI) burial dating model suggest a significantly older age for the Upper Pieze Fm. than has been previously inferred, underscoring glacial incision of the Baltic Basin and collapse of the Eridanos river system beginning in the Early Pleistocene (~2 Ma). This initial advance of the FIS into the Baltic Basin tracks the overall intensification of Northern Hemisphere glaciation indicated by marine records and alludes to the expansion of European ice masses prior to the Middle Pleistocene Transition (MPT; ~1.2–0.8 Ma). These findings add to a growing sense of mismatch between large empirically-derived pre-MPT ice sheet extents and low coeval glacial-interglacial ice volumes implicit in the global δ18O record.

How to cite: Wagner, K., Ylä-Mella, L., Margold, M., Faurschou Knudsen, M., Busschers, F., Bakker, M., Lindahl Eriksen, B., Olsen, J., Lund Andersen, J., and Jansen, J.: Early Pleistocene onset of glacial incision in the Baltic Basin revealed by 10Be-26Al burial dating of the Hattem Beds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15554, https://doi.org/10.5194/egusphere-egu24-15554, 2024.

EGU24-16431 | Orals | GM10.4

New data from Făgăraș and Retezat Massifs set the timeframe of the last glacial activity in Southern Carpathins during Younger Dryas and Early Holocene 

Daniela Pascal, Alfred Vespremeanu-Stroe, Regis Braucher, Razvan Popescu, Mihaela Enachescu, Alexandru Berbecariu, and Adrian Vasile

Past glaciations extent and chronology in the Romanian Carpathians have been disputed along most of the 20th century. Despite the recent studies presenting numerical age datings of the glacial deposits and erosion surfaces, the view on the latest glacial activity remained in debate due to results from Retezat Massif (one of the high and best studied massifs from Southern Carpathians), where authors found no evidences of Younger Dryas glaciers. In this context, we bring in the discussion new data from Retezat but even more from the Făgăraș Massif, which is the highest and largest massif from Southern Carpathians but less studied in relation to the Pleistocene glaciations with only a handful of numerical ages obtained so far. The new 10Be exposure ages collected from the highest morraines, fit the Younger Dryas - Early Holocene interval, in good agreement with European records, suggesting the glaciers reformation and advance during the Younger Dryas. It appears that some of the Younger Dryas glaciers survived in the first two millenia of the Early Holocene or reformed during Pre-Boreal Oscillation when cool and humid conditions have been present over Europe. Finally, we modeled the presence of Younger Dryas glaciers for the whole Făgăraș massif using the topographic and microclimatic characteristics of the glacial cirques which hosted new glaciers (proven by numerical ages) and found that ca 90 glaciers restricted to cirques formed during Younger Dryas in the Făgăraș massif. Samples were chemically processed at LN2C at CEREGE, France and at RoAMS Laboratory - IFIN HH, Romania. Targets of purified BeO were prepared for AMS measurements and measured at ASTER, the French National AMS Facility (CEREGE, Aix en Provence).

How to cite: Pascal, D., Vespremeanu-Stroe, A., Braucher, R., Popescu, R., Enachescu, M., Berbecariu, A., and Vasile, A.: New data from Făgăraș and Retezat Massifs set the timeframe of the last glacial activity in Southern Carpathins during Younger Dryas and Early Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16431, https://doi.org/10.5194/egusphere-egu24-16431, 2024.

EGU24-16440 | ECS | Posters on site | GM10.4 | Highlight

Deglaciation pattern of the last Scandinavian Ice Sheet across Fennoscandia 

Benjamin Boyes, Helen Dulfer, Nico Dewald, Frances Butcher, Chris Clark, Jeremy Ely, and Anna Hughes

Palaeo-ice sheets leave behind a landform record that we can decipher to understand glaciological processes and the responses of ice sheets to warming climates. Reconstructions of past ice sheet behaviour can inform numerical ice sheet models and are important for understanding ongoing glacio-isostatic uplift. The Scandinavian Ice Sheet, which was the largest component of the Eurasian Ice Sheet Complex during the last glaciation, glaciated Fennoscandia and northern Europe. Since the 19th Century, there has been considerable research into the deglaciation pattern of Scandinavian Ice Sheet during the last Glacial-Interglacial Transition. However, many reconstructions of retreat have been conducted at local-regional scales, which can be difficult to reconcile across ice sheet-scales, and ice-sheet scale reconstructions based on consistent approaches to mapping and data sources are rare. These inconsistencies lead to difficulties in creating ice-sheet wide reconstructions of deglaciation.

Using the glacial inversion approach, we combine our independently mapped ice marginal landforms, subglacial meltwater routes, and subglacial bedforms to produce a consistent ice sheet-scale assessment of deglaciation patterns across Norway, Sweden, and Finland. Here we present our latest version of the deglaciation pattern for the last Scandinavian Ice Sheet. This reconstruction has many similarities to previous efforts but adds significant detail. For example, in addition to overall retreat patterns, we capture instances of ice margin readvance. We also reconstruct a complex retreat pattern with the ice sheet breaking into small ice masses located within and adjacent to the Scandinavian Mountains.

How to cite: Boyes, B., Dulfer, H., Dewald, N., Butcher, F., Clark, C., Ely, J., and Hughes, A.: Deglaciation pattern of the last Scandinavian Ice Sheet across Fennoscandia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16440, https://doi.org/10.5194/egusphere-egu24-16440, 2024.

EGU24-16566 | ECS | Posters on site | GM10.4

Early stage Quaternary overdeepening in Upper Swabia - Germany 

Johannes Pomper, Clare Bamford, Frank Preusser, Ulrike Wielandt-Schuster, and Lukas Gegg

Overdeepenings are glacially shaped basins, incised into the bedrock deeper than the fluvial base level by subglacial erosion. Their sedimentary fillings are important archives for understanding glacial and postglacial history and the glacial impact on environmental transformation. Investigation of overdeepened features and their sedimentary contents is essential for understanding the processes and drivers of subglacial erosion, the timing and sequence of past glaciations, and accordingly their cumulated impact on landscape and topography.

This study is centred around an already acquired high quality drill core plus a correlating outcrop on the highest summit of Upper Swabia (The Hoechsten) in the North of the Lake Constance area (southwestern Germany). We investigate an overdeepening in an exceptional stratigraphic position: The sediment succession at Hoechsten is one of only a few examples of glacial basin fills that are correlated with the Early Pleistocene, and a key profile for this otherwise merely poorly constrained period. Situated in an elevated position, it is considered a component of an old highland-ramp topography that has since been largely reshaped over the course of repeated glaciations (Ellwanger et al. 2011).

Besides sedimentological analysis we apply standard geotechnical methods to reconstruct the deglaciation and potential phases of readvancement. Geotechnical data has proven valuable for the identification of a glacial sediment component, of previous mechanical loading by ice, or of the modification of a deposit by non-glacial processes. Furthermore, we compare micromorphological structures on the basis of microscale computed tomography analysis with results of a previously conducted thin-section study (Menzies & Ellwanger 2011). In the future, these analyses will be complemented by a multi-method dating approach (integrating e.g. luminescence and paleomagnetic properties and cosmogenic nuclides).

References:
Ellwanger, D., Wielandt-Schuster, U., Franz, M., & Simon, T. (2011). The Quaternary of the southwest German Alpine Foreland (Bodensee-Oberschwaben, Baden-Wuerttemberg, southwest Germany). E&G Quaternary Science Journal, 60(2/3), 306-328, DOI 10.3285/eg.60.2-3.07
Menzies, J. & Ellwanger, D. (2011). Insights into subglacial processes inferred from the micromorphological analyses of complex diamicton stratigraphy near Illmensee-Lichtenegg, Hoechsten, Germany. Boreas, 40(2), 271-288, DOI 10.1111/j.1502-3885.2010.00194.x

How to cite: Pomper, J., Bamford, C., Preusser, F., Wielandt-Schuster, U., and Gegg, L.: Early stage Quaternary overdeepening in Upper Swabia - Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16566, https://doi.org/10.5194/egusphere-egu24-16566, 2024.

EGU24-17599 | ECS | Posters on site | GM10.4

Unravelling the Patagonian Local Last Glacial Maximum and its Deglaciation History from a Modelling Perspective 

Andrés Castillo-Llarena, Franco Retamal-Ramirez, Jorge Bernales, Martin Jacques-Coper, Matthias Prange, and Irina Rogozhina

During the Marine Isotope Stages (MIS) 2-3, the Patagonian ice sheet (PIS) stretched along the southern Andes from 55°S to 38°S. Based on Glacial geomorphological and geochronological evidence, its western margin reached the Pacific Ocean, while its easternmost sectors were characterised by terrestrial lobes that fed large paleo-glacial lakes. Previous studies suggest that the maximum extension of PIS was reached towards the end of the MIS 3. However, uncertainty remains regarding the glacial and climate evolution that led to its maximum extension in asynchrony with the Northern Hemisphere ice masses and Antarctica.

We present an ensemble of transient numerical simulations of the PIS that were carried out through the MIS 3 and MIS 2, aiming to determine the range of climate conditions that match the field-derived ice sheet geometries and climate history of the Patagonian ice sheet prior the global LGM, which corresponds to the timing of the local glacial maximum and its subsequent deglaciation. Furthermore, we bracketed the spread in possible ice volumes and sea level contributions originating from uncertainties in the internal parameters and external forcings. The model ensemble is built using the ice sheet model SICOPOLIS forced by phases 3 and 4 of the Paleoclimate Modeling Intercomparison Project (PMIP). The transient simulations are based on a glacial index method by using a combination of Patagonian offshore records and Antarctic cores. Our results indicate that the regional climate conditions required to reproduce a realistic growth and demise of the PIS through the Late Quaternary are not captured by coarse-resolution global climate models, implying the need of climate models with high spatial resolution and a well-constrained ice mask, which could reproduce the necessary cooling to promote the adequate growth. Our results also suggest that the MIS3 should have witnessed colder conditions than those modeled at the LGM by global climate models to realistically simulate the evolution of the PIS in agreement with geological archives.

How to cite: Castillo-Llarena, A., Retamal-Ramirez, F., Bernales, J., Jacques-Coper, M., Prange, M., and Rogozhina, I.: Unravelling the Patagonian Local Last Glacial Maximum and its Deglaciation History from a Modelling Perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17599, https://doi.org/10.5194/egusphere-egu24-17599, 2024.

EGU24-19781 | ECS | Posters on site | GM10.4

The first glaciers at Ivrea, southern Alpine Foreland  

Shantamoy Guha, Pierre Valla, Lotta Yla-Mella, Mads Faurschou Knudsen, Franco Gianotti, Giovanni Monegato, Elena Serra, Konstanze Stübner, Johannes Lachner, Georg Rugel, and John D. Jansen

Pleistocene Glaciations and their effects on Alpine topography have drawn scientific attention since well before the days of Penck and Brückner (1909), although this indomitable pair left a strong legacy to build upon. The onset of large-scale glaciations in the Alps relative to the growth of the other great Northern Hemisphere ice sheets remains a first-order question in the Quaternary sciences. Previous chronologies from the southern Alpine Foreland based on magnetostratigraphy (Muttoni et al. 2003) and from the northern Alpine Foreland based on 10Be-26Al burial dating (Knudsen et al. 2020) converge around 1.0–0.9 Ma, during the Middle Pleistocene Transition (~1.2–0.8 Ma).

Extensive moraine complexes in the southern Alpine Foreland, such as those at Ivrea, offer a valuable opportunity to determine when glaciers advanced beyond the Alpine rangefront for the first time. The Ivrea Morainic Amphitheatre comprises interbedded glacial tills at the outlet of the Aosta Valley in NW Italy (Gianotti et al. 2015). The oldest tills have been attributed by previous workers to a stage before the Matuyama-Brunhes magnetic polarity reversal (~ 0.8 Ma).

We apply 10Be-26Al burial dating to the oldest glacigenic deposits at Ivrea, utilizing the Monte Carlo-based inversion model, P-PINI (Particle-Pathway Inversion of Nuclide Inventories). Our preliminary results indicate that the first major glacial advance occurred ~ 1.3–1.1 Ma. We combine these analyses with detrital thermochronology measurements on pebbles collected from preglacial sediments at Ivrea. These pebbles indicate provenance from the Austroalpine Massifs and an absence of the External Massifs (Mont Blanc granites)-in contrast to the present-day Aosta Valley sediments, which show the cooling signature of the Mont Blanc granites. 

We reflect on the coincident timing of the exhumation of the External Massifs and the earliest large-scale Alpine glaciations at the onset of the Middle Pleistocene Transition.

How to cite: Guha, S., Valla, P., Yla-Mella, L., Knudsen, M. F., Gianotti, F., Monegato, G., Serra, E., Stübner, K., Lachner, J., Rugel, G., and Jansen, J. D.: The first glaciers at Ivrea, southern Alpine Foreland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19781, https://doi.org/10.5194/egusphere-egu24-19781, 2024.

EGU24-20311 | Posters on site | GM10.4

Glacial cirque morphometry of Rila and Pirin Mountains (Bulgaria) 

Tamás Telbisz, Márton Krasznai, Emil Gachev, Alexander Gikov, and Zsófia Ruszkiczay-Rüdiger

Cirque valleys are typical landforms of formerly glaciated high mountains, which also play an important role in paleoclimate reconstruction. In Bulgaria, the Rila (highest peak, Musala 2925 m) and Pirin (highest peak, Vihren 2915 m) mountains were the only terrains, where significant glacial cover developed during the Pleistocene glaciations, although some minor glacial landforms also exist elsewhere in Bulgaria. During the glacial periods, valleys of the Rila and Pirin Mts were re-shaped by glacial erosion and currently are characterized by glacial cirques and U-shaped valleys reaching lengths of 22 km (in Rila) and 13.5 km (in Pirin).

In these two mountain ranges, a comprehensive, quantitative geomorphometric analysis of glacial cirques valleys has not yet been carried out, thus we try to fill this gap with the present work. Primarily, digital terrain models and GIS tools were used to delineate the cirques. Based on the delineations, the main morphometric parameters of the cirques (elevation, relative depth, width, length, area, aspect, slope conditions, etc.) were calculated and a careful statistical analysis of these parameters was performed. Both the topographic orientation and the lithological structure of the two neighbouring mountains are different, that gives us an opportunity for a comparison of topo-climatic and lithological factors of cirque development. For instance, based on elevation, size and orientation of the cirques, the possible correlations with the paleoclimate factors, like exposure or moisture transport directions can be examined. Finally, our results were compared with available cirque valley morphometric data of other high mountains rising on the Balkan Peninsula.

How to cite: Telbisz, T., Krasznai, M., Gachev, E., Gikov, A., and Ruszkiczay-Rüdiger, Z.: Glacial cirque morphometry of Rila and Pirin Mountains (Bulgaria), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20311, https://doi.org/10.5194/egusphere-egu24-20311, 2024.

  • Reconstructing the extent and timing of palaeoglaciers and their associated climate is of great importance for understanding the responses of glaciers to climate change. Glacial landforms are well-preserved in Zheduo Shan, one of the high mountain ranges on the eastern Tibetan Plateau (TP). However, few studies have constrained glacial chronologies and estimated palaeoclimate in this area. We investigated the glacial advance during the Last Glacial Maximum (LGM) in Zheduo Shan using 10Be surface exposure dating. We then reconstructed the extent and thickness of LGM glaciers based on geomorphological mapping and a flowline-based glacial modelPalaeoIce. Eleven 10Be exposure ages confirmed a major LGM glacial advance between 20.0 ± 3.2 ka and 19.3 ± 2.8 ka. The reconstructed LGM glaciers in this mountain range covered an area of 499.16 km2 with an average ice thickness of 54.4 m and a total ice volume of 52.82 km3. The regional average equilibrium-line altitude (ELA) was estimated as 4524 ± 140 m, 535 ± 140 m lower than the present value. Based on the empirical relationship between precipitation and temperature (P-T model) at the ELAs on the TP, the temperature and precipitation were estimated as 3.10–5.27 ◦C and 10–16% lower during the LGM than the present values, respectively. These results suggest that the LGM glacial advance was more sensitive to temperature than precipitation in Zheduo Shan.

How to cite: Yang, Y.: Reconstruction of palaeoglaciers and palaeoclimate in Zheduo Shan, Eastern Tibetan Plateau, during the Last Glacial Maximum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21174, https://doi.org/10.5194/egusphere-egu24-21174, 2024.

CL2 – Present Climate – historical and direct observations period

EGU24-7 | Orals | CL2.1

Trenberth’s (2022) Greenhouse Geometry 

Miklos Zagoni

“How Does a Greenhouse Effect Work?” asks Kevin Trenberth in his new book (The Changing Flow of Energy Through the Climate System, Cambridge University Press, 2022, Chapter 3, Sidebar 3.2). The answer is two plates in space, with sunlight shining on the first at a rate of 480 Wm-2; and four equations are presented to describe the resulting energy flow system (480, 320, and 160 Wm-2); see Fig. 3.3, panel 5 on page 30:

Since this structure is open at both sides, if we want to apply it for Earth-like conditions, a planetary surface should be introduced, and the equations have to be slightly modified to describe the surface-atmosphere geometry. After doing so, we have an energy flow system with incoming solar radiation (Wm-2) = 480, outgoing longwave radiation OLR = 480, and surface upward LW emission ULW = 720 = 1.5OLR. The greenhouse effect is G = ULW – OLR = 240 = OLR/2, and the normalized geometric greenhouse factor is g = G/ULW = 1/3. Here we show that these relationships are accurately satisfied by the real Earth’s clear-sky energy flow system. With the up-to-date CERES EBAF Edition 4.2 Version 2 data (release date 2-January-2024, global means 10/2000–09/2023): OLR = 265.95 Wm-2, ULW = 398.75 Wm-2, hence 1.5OLR = 398.92 Wm-2 (0.17 Wm-2 difference) and the greenhouse effect is G = 398.75 – 265.95 = 132.80 Wm-2 with OLR/2 = 132.97 Wm-2 (0.17 Wm-2 difference). The normalized greenhouse factor is g = 132.80/398.75 = 0.333. This parameter is one of the most stable from all climate data: its value was estimated as 0.33 in 1989 and determined as 1/3 in 2008; CERES EBAF Edition 2.8 (2017) found it as g = (398.40 – 265.59)/398.40 = 0.33336. — This close equivalence of the real Earth’s greenhouse factor and the GHG-independent geometric model implies that long-lived greenhouse gases do not play the role of the LW control knob that governs the greenhouse effect but produce a background on which water vapor and the lapse rate adjust and maintain the demanded greenhouse magnitude. In our talk, we present all the data needed to prove that Earth’s atmosphere follows this simple “plate-state” geometry. It can be shown [1] that not only the clear-sky greenhouse fluxes, but the whole annual global mean energy flow system, both clear-sky and all-sky, shortwave and longwave, at the TOA, within the atmosphere and at the surface, even the non-radiative flux components, may be derived from first principles without any reference to the atmospheric gaseous composition. Graeme Stephens’ idea could not be more timely: “Instead of the traditional paradigm of properties define processes, study how processes define property.” We would add: Study how principles define processes, then property. In this talk, we show how geometric principles define radiative processes to generate and maintain the required atmospheric state[2].

References:

[1] Zagoni, M. (2023) Arithmetic relationships in Earth's global mean energy flow system.
https://egusphere.copernicus.org/preprints/2023/egusphere-2023-698/

[2] https://earthenergyflows.com/Trenberths_greenhouse_geometry.html

 

How to cite: Zagoni, M.: Trenberth’s (2022) Greenhouse Geometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7, https://doi.org/10.5194/egusphere-egu24-7, 2024.

EGU24-387 | ECS | Posters on site | CL2.1

Data-driven Estimation of Cloud Effects on Surface Irradiance atXianghe, a Suburban Site on the North China Plain 

Mengqi Liu, Jinqiang Zhang, Hongrong Shi, Disong Fu, and Xiangao Xia

Clouds are a dominant modulator of the energy budget. The cloud shortwave radiative effect at the surface (CRE) is closely related to the cloud macro- and micro-physical properties. Systematic observation of surface irradiance and cloud properties are needed to narrow uncertainties in CRE. In this study, 1-min irradiance and Total Sky Imager measurements from 2005 to 2009 at Xianghe in North China Plain are used to estimate cloud types, evaluate cloud fraction (CF), and quantify the sensitivities of surface irradiance with respect to changes in CF whether clouds obscure the sun or not. The annual mean CF is 0.50, further noting that CF exhibits a distinct seasonal variation, with a minimum in winter (0.37) and maximum in summer (0.68). Cumulus occurs more frequently in summer (32%), which is close to the sum of the occurrence of stratus and cirrus. The annual CRE is –54.4 W m–2, with seasonal values ranging from –29.5 W m–2 in winter and –78.2 W m–2 in summer. When clouds do not obscure the sun, CF is a dominant factor affecting diffuse irradiance, which in turn affects global irradiance. There is a positive linear relationship between CF and CRE under sun-unobscured conditions, the mean sensitivity of CRE for each CF 0.1 increase is about 1.2 W m–2 [79.5° < SZA (Solar Zenith Angle) < 80.5°] to 7.0 W m–2 (29.5° < SZA < 30.5°). When clouds obscure the sun, CF affects both direct and diffuse irradiance, resulting in a non-linear relationship between CF and CRE, and the slope decreases with increasing CF. It should be noted that, although only data at Xianghe is used in this study, our results are representative of neighboring areas, including most parts of the North China Plain.

How to cite: Liu, M., Zhang, J., Shi, H., Fu, D., and Xia, X.: Data-driven Estimation of Cloud Effects on Surface Irradiance atXianghe, a Suburban Site on the North China Plain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-387, https://doi.org/10.5194/egusphere-egu24-387, 2024.

EGU24-1295 | Orals | CL2.1

Instantaneous Radiative Forcings of Greenhouse Gases   

William van Wijngaarden and Will Happer

The top of the atmsophere (TOA) instantaneous long wave radiative forcings resulting from increasing greenhouse gases such as CO2, CH4, N2O and various halogenated gases were found by solving the equation of transfer.  The observed altitude dependence of the greenhouse gas concentrations was used as well as the standard midlatitude temperature profile.  The calculations used the line intensities or absorption cross sections from the HITRAN database and also considered the effect of scattering by a cloud layer.  Various cloud properties were considered including altitude, optical depth and single scattering albedo for both isotropic and forward scattering.  The results show that a cloud layer reduces the TOA radiative forcing from its clear sky value.  The incremental forcing is even negative for an optically thick high altitude cloud.  This occurs because the temperature increases with altitude in the stratosphere.

How to cite: van Wijngaarden, W. and Happer, W.: Instantaneous Radiative Forcings of Greenhouse Gases  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1295, https://doi.org/10.5194/egusphere-egu24-1295, 2024.

EGU24-1782 | ECS | Orals | CL2.1

Effect of Uncertainty in Water Vapor Continuum Absorption on CO2 Forcing, Longwave Feedback, and Climate Sensitivity 

Florian E. Roemer, Stefan A. Buehler, Lukas Kluft, and Robert Pincus

We assess the effect of uncertainty in water vapor continuum absorption on CO2 forcing F, longwave feedback λ, and climate sensitivity S at surface temperatures Ts between 270K and 330K. We calculate this uncertainty using a line-by-line radiative-transfer model and a single-column atmospheric model, assuming a moist-adiabatic temperature lapse-rate and 80% relative humidity in the troposphere, an isothermal stratosphere, and clear skies. Emulating continuum uncertainty in observations, we hold total continuum absorption fixed at room temperature, but change its components: We assume a 10% decrease in self continuum absorption, which comprises interactions between water molecules, and a spectrally varying increase in foreign continuum absorption, which comprises interactions between water and non-water molecules. We find that continuum uncertainty mainly affects S through its effect on λ. Continuum uncertainty primarily impacts the surface feedback at Ts<290K and the atmospheric feedback at Ts>290 K. Under present-day conditions, those two effects have opposite signs and thus largely cancel each other, therefore the effect of continuum uncertainty on S is negligible (0.02K). At Ts>300K, however, the effect on S is much stronger (>0.2K). This is because at those Ts, the effects on λ of decreasing the self continuum and increasing the foreign continuum have the same sign. These results highlight the importance of a correct partitioning between self and foreign continuum to accurately determine the temperature dependence of Earth’s climate sensitivity.

How to cite: Roemer, F. E., Buehler, S. A., Kluft, L., and Pincus, R.: Effect of Uncertainty in Water Vapor Continuum Absorption on CO2 Forcing, Longwave Feedback, and Climate Sensitivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1782, https://doi.org/10.5194/egusphere-egu24-1782, 2024.

EGU24-3518 | ECS | Orals | CL2.1

Photosynthetically Active Radiation Dynamics in Wetland Ecosystem: A Decadal Study in the Biebrza National Park, Poland 

Jan Górowski, Krzysztof Fortuniak, Mariusz Siedlecki, and Włodzimierz Pawlak

Photosynthetically active radiation (PAR) is one of the most important ecosystem steering factors. This study presents the results of 10-year (2013-2022) continuous measurements of incoming (PARd) and reflected (PARu) photosynthetically active radiation made at the Kopytkowo site (53°35′30.8′′ N, 22°53′32.4′′ E, 109 m ASL) within the Biebrza National Park in northeastern Poland.  The site represents a unique wetland ecosystem on a European scale. The assessment employed a PQS1 Quantum Sensor positioned at a height of 2.7 m AGL, capturing PAR with a time step of ten seconds. Subsequently, the data underwent averaging to establish a 5-minute time step used in the study. The results were expressed in photosynthetically active photon flux density (PPFD in µmol·m⁻²-·s⁻¹-).

Two distinct seasons corresponded to different PARd regimes in the Biebrza Basin. On average the first season (the warm part of the year) commences in the latter half of March and lasts until early October. Throughout this period, the development of convective cloudiness impacts daily photosynthetically active radiation values. The winter season, which lasts for the remainder of the year, is characterised by a higher proportion of cloudy days, influencing the reduced values of surveyed radiation. In general, the annual and daily PARd course reflects the incoming radiation on the top of the atmosphere and its attenuation in the atmosphere. On the contrary, the highest values of PARu manifest during the winter months, resulting from reduced vegetation development and snow cover present at the measurement site. Around mid-April values of PARu begin to drop due to vegetation growth and the assimilation of light.

Simultaneous measurement of PARd and PARu allowed the calculation of albedo in terms of photosynthetically active radiation, which was then used to trace changes in the growing season of plants and their growth dynamics in the study area. Research shows an average of about 210 days of increased absorption of photosynthetically active radiation per year, which falls during the vegetation development period (April to November). The first stage (rapid development) starts at the beginning of April and lasts until the middle of the month. It is characterized by a sharp decline in the proportion of PAR. This is followed by a period of stable expansion, which lasts until the end of May, after which the PARu/PARd ratio remains at a similar low level until mid-November. The highest values occur in January and February, due to the presence of snow cover, which increases the reflection of radiation, and due to reduced plant activity.

Acknowledgements: The National Science Centre, Poland provided funding for this research under project UMO-2020/37/B/ST10/01219 and the University of Lodz under project 4/IDUB/DOS/2021. The authors thank the authorities of the Biebrza National Park for allowing continuous measurements in the area of the Park.

How to cite: Górowski, J., Fortuniak, K., Siedlecki, M., and Pawlak, W.: Photosynthetically Active Radiation Dynamics in Wetland Ecosystem: A Decadal Study in the Biebrza National Park, Poland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3518, https://doi.org/10.5194/egusphere-egu24-3518, 2024.

Surface warming is directly associated with the surface energy balance, where downwelling longwave radiation is a critical factor influencing and reflecting surface temperature variations. Accurately identifying various forcing and feedback mechanisms is essential to making more realistic predictions about future climate change. Spectrally-resolved radiance measurements play an important role in this pursuit by leveraging the distinctive absorption features of atmospheric compositions. Only recently, the availability of comprehensive, long-term records of spectrally resolved radiation and atmospheric properties has enabled us to observe and quantify the forcing and feedback factors, such as the cloud feedback characterized by its high uncertainty.

This study initiated by homogenizing the 23-year record of downwelling longwave radiance (DLR) observed by the Atmospheric Emitted Radiance Interferometer (AERI) at the Southern Great Plains site. A detailed DLR record for diverse sky conditions was obtained, enabling the determination of long-term trends in both clear-sky and all-sky scenarios. These trends reveal distinct spectral signals associated with various meteorological variables, forming the basis for further climate change signal attribution analysis.

Subsequently, we develop and validate a novel spectral fingerprinting method tailored to constrain surface forcings and feedbacks from long-term DLR trends. Our analysis identifies positive CO2 and negative O3 surface forcings in both clear-sky and all-sky conditions. Moreover, we observe that changes in temperature and water vapor concentration over the 23-year period contribute to an increase in downwelling longwave radiation. Significantly, our study discovers a negative cloud feedback that offsets the increase in downwelling longwave radiation resulting from elevated CO2, water vapor, and atmospheric temperature. These attributions of radiation changes, derived from AERI observations using the fingerprinting method, are validated against the kernel method and compared with the simulations of Global Climate Models.

How to cite: Huang, Y., Liu, L., and Gyakum, J.: Climate change signals of radiative forcing and feedback unveiled from long-term trends of spectrally resolved surface longwave radiation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4120, https://doi.org/10.5194/egusphere-egu24-4120, 2024.

 

In the context of global warming, the radiation balance in the Tibetan Plateau region is closely linked to changes in the cryosphere, such as glacier retreat, reduced snow cover, and degradation of permafrost. The abnormal changes in radiation balance further impact the East Asian circulation and global climate change. In this study, based on 23 years (2000-2022) of data from the Clouds and the Earth's Radiant Energy System (CERES) for atmospheric and surface radiation fluxes, the temporal and spatial characteristics of solar radiation reflection at the top of the atmosphere (TOA) over the Tibetan Plateau (TP) and its components, including cloud, atmospheric, and surface components, were analyzed. The results showed that the average TOA solar radiation reflection over the TP was 128.5 W m-2, with cloud component contributing approximately 60.3 %, clear-sky atmospheric component contributing approximately 18.4 %, and surface component contributing approximately 21.3%. From 2000 to 2015, there was a significant decreasing trend in TOA solar radiation reflection over the TP, with a Sen's slope of -1.59 W m-2 10a-1. The interannual variability intensity (i.e., standard deviation of anomalies) was approximately 1.44 during this period. However, from 2016 to 2022, the interannual variability intensity increased to 3.62. The changes in interannual variability of TP solar radiation reflection were closely related to the changes in cloud, atmospheric, and surface parameters. Further analysis is needed to understand the reasons for the changes in radiation balance over the TP. This study plans to explore the impacts and contributions of various atmospheric circulation factors on the interannual changes in TP solar radiation reflection and its components using reanalysis meteorological data and synthesis analysis, aiming to reveal the possible mechanisms behind the abrupt change in interannual variability intensity around 2015.

How to cite: Jian, B. and Li, J.: Investigating the Causes of Interannual Variation in Solar Radiation Reflection at the Top of the Atmosphere over the Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4595, https://doi.org/10.5194/egusphere-egu24-4595, 2024.

EGU24-5330 | ECS | Orals | CL2.1

Ensuring the monitoring of ground heat storage with satellite data 

Francisco José Cuesta-Valero and Jian Peng

Global ground heat storage is the second largest term of the Earth heat inventory only after the ocean, representing a 4-5% of the total heat storage within the climate system. Furthermore, determining the heat storage and heat flux in the land subsurface is necessary for closing the surface energy budget and quantifying the total energy exchange between the lower atmosphere and the shallow continental subsurface. Global long-term estimates of ground heat storage have been retrieved from geothermal data, with measurements from Eddy-covariance stations as a complement. Nevertheless, these two databases are biased towards northern extratropical latitudes, and there are not enough records to obtain a global average of ground heat storage after the year 2000. For this reason, ground heat storage for the period 2000-2020 consists in an extrapolation of the trend from the previous 30 years.

We estimate ground heat storage from six remote sensing products provided by the Climate Change Initiative of the European Space Agency (ESA-CCI). The products consist in land surface temperatures derived from three single-sensor (ENVISAT, MODIS-Terra, and MODIS-Aqua) and three multi-sensor datasets (IRCDR, IRMGP, and SSMI-SSMIS), covering all land surface except Greenland and Antarctica. First, ground heat fluxes are derived from the satellite land surface temperatures using two different methods, and are then evaluated against in situ heat flux observations at Eddy-covariance stations from the FLUXNET, the Integrated Carbon Observation System (ICOS), and Ameriflux databases. The heat fluxes are accumulated to derive ground heat storage for each satellite product, and combined with the estimates from geothermal data to cover the period 1960-2020. This new estimate yields a heat storage of 20.9 ± 4.3 ZJ during the period 1960-2018, while previous estimates reached 24.0 ± 5.4 ZJ and 20.47 ± 0.19 ZJ for the same period. During the period without geothermal estimates, from 2000 to 2020, the new multi-satellite average reaches 10.5 ± 6.4 ZJ, a similar value to the one based on a linear extrapolation of geothermal values (10.18 ± 0.22 ZJ). Furthermore, satellite estimates provide spatial patterns of heat flux changes at the global scale with a high spatial (1 km) and temporal (monthly) resolutions, which will allow to perform analyses not possible with other, more coarse, datasets. Overall, these results reinforce the values obtained in previous analyses, while the methodology used here ensures the monitoring of global ground heat storage in the next decades.

How to cite: Cuesta-Valero, F. J. and Peng, J.: Ensuring the monitoring of ground heat storage with satellite data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5330, https://doi.org/10.5194/egusphere-egu24-5330, 2024.

EGU24-5679 | ECS | Orals | CL2.1

Efficacies, pattern effects & radiative feedback in a large ensemble of HadGEM3-GC3.1-LL historical simulations 

Harry Mutton, Timothy Andrews, Leon Hermanson, Melissa Seabrook, Doug Smith, Mark Ringer, Gareth Jones, and Mark Webb

Climate feedbacks over the historical period have been investigated in a 47 member ensemble of atmosphere-ocean general circulation model (AOGCM) simulations. Here, the model response to historical forcing, as well as individual forcing constituents such as aerosol and greenhouse gases separately, has been analysed. The analysis addresses the cause of differing feedbacks across the ensemble, the disparity between feedbacks seen in these AOGCM simulations and atmosphere-only GCM (AGCM) experiments prescribed with observed SSTs, and the different forcing efficacies of the respective forcing agents. It is found that much of the spread in feedbacks across ensemble members and different experiments can be explained through varying SST patterns. The level of polar amplification is shown to strongly control the amount of sea ice melt per degree of global warming, a mechanism responsible for the spread in shortwave clear sky feedback and a large contributor to the different forcing efficacies seen across the different forcing agents. The spread in feedbacks across the historical ensemble is also shown to be caused by both the level of tropical surface temperature warming, due to its influence on longwave clear sky feedback, and the response of  cloud feedbacks to local surface temperatures and large scale changes in tropospheric temperature. It is also shown that each of these processes discussed are partly responsible for the disparity in feedbacks seen between AOGCM simulations and  AGCM experiments prescribed with observed SSTs.

How to cite: Mutton, H., Andrews, T., Hermanson, L., Seabrook, M., Smith, D., Ringer, M., Jones, G., and Webb, M.: Efficacies, pattern effects & radiative feedback in a large ensemble of HadGEM3-GC3.1-LL historical simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5679, https://doi.org/10.5194/egusphere-egu24-5679, 2024.

The incoming surface solar radiation is an essential climate variable as defined by GCOS. Long term monitoring of this part of the earth’s energy budget is required to gain insights on the state and variability of the climate system. In addition, climate data sets of surface solar radiation have received increased attention over the recent years as an important source of information for solar energy assessments, for crop modeling, and for the validation of climate and weather models; all applications are requiring high-quality and temporally-consistent data records.

Gridded regional and global data records of the surface irradiance are available based on satellite measurements as well as derived from numerical models, e.g., reanalysis systems. For climatological analyses, long-term data records, covering multiple decades, are required. SARAH-3 and CLARA-A3, the satellite-based climate data records from the EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF), provide data for more than 4 decades already, starting in 1983 and 1979, respectively, and are providing temporally consistent near real-time data.

Here, we present the surface solar radiation data from the SARAH-3 and the CLARA-A3 climate data records for Europe. Evaluation results using surface reference data from BSRN / GEBA and other sources document the quality of the satellite-based data in terms of accuracy and temporal stability. The variability, the changes, and the trends in surface radiation are presented and discussed. Additional data, e.g., top-of-atmosphere fluxes and cloud coverage, are used to assess potential causes for the trends and variabilities found in the surface solar radiation in Europe.  

How to cite: Trentmann, J. and Pfeifroth, U.: Four decades (and counting) of Satellite-based Surface Solar Radiation data - The CM SAF SARAH-3 and CLARA-A3 Climate Data Records , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6426, https://doi.org/10.5194/egusphere-egu24-6426, 2024.

Asian large-scale orography profoundly influences circulation in the North Hemisphere. Considerable spring top-of-the-atmosphere (TOA) radiative cooling over Southeast China (SEC) is very likely related to upstream orography forcing. Here we investigate the mechanical and thermal forcings of Asian large-scale orography, particularly the Tibetan Plateau (TP), on downstream East Asian cloud amount and atmospheric radiation budget during March-April using the Global Monsoons Model Intercomparison Project simulations. The thermal forcing drives significant surface heating and a low-level cyclone over the TP, pumping low-level air to the middle troposphere. Ascent and water vapor convergence triggered by the thermal forcing favor air condensation, low-middle clouds, and resultant strong spring cloud radiative cooling over SEC. Moreover, the thermal forcing moves the position of cloud radiative cooling westward towards the TP. The TP’s blocking role weakens low-level westerlies over SEC, but its deflecting role increases downstream high-level westerlies, dynamically favoring cloud formation over SEC and the eastward ocean. In addition, the TP can force ascent and increase cloud amounts over the western and central TP. The thermal forcing contributes to 57.1% of total cloud amount and 47.6% of TOA cloud radiative cooling induced by the combined orography forcing over SEC while the mechanical one accounts for 79.4% and 95.8% of the counterparts over the ocean to the east of SEC. Our results indicate that Asian large-scale orography shapes the contemporary geographical distribution of spring East Asian cloud amount and atmospheric radiation budget to a large extent.

How to cite: Li, J.: Mechanical and thermal forcings of Asian large-scale orography on spring cloud amount and atmospheric radiation budget over East Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6888, https://doi.org/10.5194/egusphere-egu24-6888, 2024.

EGU24-7893 | ECS | Orals | CL2.1

Projecting the Surface UV Radiation from CMIP6 Models and how Factors Influencing it are Changing 

Anthi Chatzopoulou, Kleareti Tourpali, Alkiviadis F. Bais, Dimitris Karagkiozidis, and Peter Braesicke

Links between stratospheric ozone depletion, climate change and UV variability reaching the ground have been established already in a number of studies. Apart from ozone variability and among other factors, aerosol properties, surface reflectivity and clouds are critical for the modulation of the surface UV radiation levels.

In the first part of the study, we examine the evolution of these variables through the years, as derived from simulations by models participating in the 6th Phase of the Coupled Model Intercomparison Project (CMIP6). The period of interest extends from the years before the peak of the ozone depletion (here we selected as reference period the years 1950-1960), up to the end of the 21st century. For a better understanding of future UV radiation levels, we selected three of the IPCC Shared Socioeconomic Pathways (SSPs); SSP1–2.6 as the most sustainable, SSP3–7.0 with high amounts of GHGs and SSP5–8.5 as the most extreme.

In the second part of the study, we provide an overview of the surface UV changes around the globe, with radiative transfer model (RTM) simulations of solar irradiance using libRadtran version 2.0.3. Monthly mean data of ozone, aerosol optical depth (AOD) at 550 nm and surface reflectivity from CMIP6 models are used as input data for the RTM simulations. Here we present changes of the local noon UV-Index (UVI), after weighting the simulations with the Commission Internationale de l'Éclairage (CIE) erythemal action spectra.

Some key changes in drivers and UVI will be discussed. After the middle of the 21st century there is an increasing trend of total ozone column, and more specifically over the Antarctic region, where the depletion is more pronounced, we find that ozone recovery is projected under SSP3–7.0 and SSP5–8.5, while this never fully occurs under SSP1–2.6. According to RTM simulations, reduction of UVI is expected due to the recovery of the ozone layer after the middle of the 21st century. AOD increases over the areas with strong emissions under the three SSPs, which leads to more scatter of irradiance and consequently to lower surface UVI. Finally, surface reflectivity simulations for the end of the 21st century show reductions under all SSPs, mostly over the high latitudes, mainly attributed to ice melt, resulting in decreases of surface UVI.

How to cite: Chatzopoulou, A., Tourpali, K., Bais, A. F., Karagkiozidis, D., and Braesicke, P.: Projecting the Surface UV Radiation from CMIP6 Models and how Factors Influencing it are Changing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7893, https://doi.org/10.5194/egusphere-egu24-7893, 2024.

EGU24-8223 | Orals | CL2.1

Robust increase in CO2 effective radiative forcing in warmer climates 

Chris Smith, Duncan Watson-Parris, Ryan Kramer, Timothy Andrews, Ada Gjermundsen, Harry Mutton, Jing Feng, David Paynter, Robin Chadwick, Hervé Douville, and Romain Roehrig

The effective radiative forcing (ERF) is a robust predictor of future equilibrium warming. It is generally assumed that the ERF depends only on changes in atmospheric constituents and is independent of the background climate state. Building on recent work demonstrating that, in contrast, the instantaneous radiative forcing (IRF) for CO2 is strongly state-dependent, we show that the ERF for CO2 also increases in warmer climate states. 

We analyse a 4×CO2 atmosphere-only forcing in both control and warmer climate states in eight CMIP6-era models. Four models participated in the Cloud Feedback Model Intercomparison Project (CFMIP) which used pre-industrial SSTs in its control state and SSTs from near the end of the same model’s coupled abrupt-4×CO2 run in its warm state. In the other four models we used an AMIP climatology as the control state and a uniform increase in SSTs of 4 K above this AMIP climatology in the warm state. All eight models show an increase in 4×CO2 ERF, ranging from 0.1-0.5 W m-2, translating to a relative increase of 0.02-0.09 W m-2 K-1 or 0.2-1.1 % K-1. The increase is statistically significant in five of the eight models.

Our findings have implications for derivation of simplified relationships of climate warming, for instance in the calculations of global warming metrics and in economic models, from which future climate change risks being underpredicted without a temperature adjustment.

We also run aerosol forcing experiments under the +4 K climate, for which there is less agreement between models, but some show large changes in aerosol ERF under the warmer climate state, with potential implications for our ability to discern transient warming even with a more accurate understanding of present-day aerosol forcing. 

How to cite: Smith, C., Watson-Parris, D., Kramer, R., Andrews, T., Gjermundsen, A., Mutton, H., Feng, J., Paynter, D., Chadwick, R., Douville, H., and Roehrig, R.: Robust increase in CO2 effective radiative forcing in warmer climates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8223, https://doi.org/10.5194/egusphere-egu24-8223, 2024.

In recent years, radiative feedbacks in the earth system have been strongly tied to the spatial pattern of sea surface temperatures (SSTs). This “pattern effect” has been strongly tied to the strength of cloud radiative feedbacks driven by atmospheric stability changes. SST patch Green’s functions experiments have revealed that the ratio of warming in deep convective tropical regions, versus outside, drives significant changes in atmospheric stability. These Green’s functions can be used to reconstruct feedbacks from given warming patterns. However, it remains unclear how different warming patterns arise. Different Green’s functions, prescribing surface heat fluxes in atmosphere-ocean coupled models instead of temperature changes in fixed SST experiments, may answer this question by showing how energy inputs translate into temperature changes.

Using a simplistic set of patches of applied surface heat fluxes in CESM2-CAM6 and HadCM3, we find that heat input into the tropics results in strongly negative radiative feedbacks from enhanced warm pool warming. This results in a small climate sensitivity to this tropical forcing. Conversely, heat fluxes input into the extratropics cause significantly less negative feedbacks that result in greater climate sensitivity to extratropical forcing.Furthermore, the response to tropical forcing occurs rapidly, with equilibrium roughly achieved within a few years both in slab ocean and fully coupled models. The response to extratropical forcing, by contrast, induces near-zero feedbacks in the first few years, followed by significantly weaker negative feedbacks than seen under tropical forcing, which leave this simulation far from equilibrium after 150 years in the fully coupled model.

These outcomes of forcing, from within the tropics and outside, can be combined to explain the early changes in feedbacks in response to global uniform forcing, or near-uniform global forcings such as from CO2. Reconstruction of the uniform case by summing the tropical and extra-tropical cases gives a good fit, except for an apparent temperature dependence in CESM2, and shows that extra-tropical component of surface forcing is driving the long-term feedbacks in the uniform forcing scenario.

Understanding the process of how the pattern of forcing results in different temperature change patterns may be key to comprehending future temperature changes, given that the pattern of future forcing evolves with the changing mix of anthropogenic forcing agents. Furthermore, exploring how models vary in their conversion of forcing into temperature change, even within the simple experimental design of this study, may highlight significant model feedback differences and contribute to narrowing the range in model predictions of future warming.

How to cite: Salvi, P., Gregory, J., and Ceppi, P.: Assessing the Impact of Surface Energy Inputs on Radiative Feedbacks in Tropical and Extra-tropical Regions: Strength, Evolution, and Timescales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8514, https://doi.org/10.5194/egusphere-egu24-8514, 2024.

A variation of the solar energy received by the earth – quantified by the Total Solar Irradiance (TSI) – is a radiative forcing for climate changes on earth. Since the 1976 Science paper by J. Eddy, solar-climate research has been dominated by the paradigm that solar activity and TSI have been slowly increasing since the Maunder Minimum - extending from about 1645 to 1715 – and the present, which was believed to be a Modern Solar Maximum. If this paradigm were valid, over the last 50 years, when most of the global warming has occurred, this warming would be partly due to anthropogenic greenhouse gas warming, and partly due to natural solar warming.

However, evidence has been accumulating against the ‘Modern Solar Maximum paradigm’. Based on this evidence, recently a new reconstruction of the centennial TSI variation from 1700 to 2020 was published. This new centennial TSI reconstruction is nothing less than a paradigm shift for Sun-Climate research. Following the new TSI reconstruction, the TSI did not gradually increase over the last 320 years, but rather varied with a long term periodicity of 105 years, and currently we are near the minimum of this 105 year variation. Therefore over the last 50 years, the sun did not contribute to global warming, but rather tried to cool the earth, partly counteracting greenhouse gas warming. Since we are near the minimum of the 105 year variation, we can expect a trend reversal and for the next 50 years we can expect that the sun will contribute to global warming, making it more difficult for mankind to reach the goals of the Paris Climate Agreement, in order to avoid catastrophic climate change.

How to cite: Dewitte, S.: Centennial Total Solar Irradiance variation : a paradigm shift for Sun-Climate research., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10211, https://doi.org/10.5194/egusphere-egu24-10211, 2024.

EGU24-10684 | ECS | Orals | CL2.1

Climate evolution in the spectral signatures of simulated and observed radiances 

Stefano Della Fera, Federico Fabiano, Quentin Libois, Lucie Leonarski, Guido Masiello, Piera Raspollini, Marco Ridolfi, Jost von Hardenberg, and Ugo Cortesi

Since the mid-2000s, stable hyperspectral observations of the mid-infrared (MIR) region (667 to 2750 cm-1) of the Earth’s emitted radiance have been provided by different space-based sensors (IASI, AIRS, etc.) producing a long-term dataset that has proven to be crucial for climatological studies. In addition, the FORUM mission, whose launch is planned for 2027, will provide unique spectrally resolved measurements extending down to the far-infrared (FIR) region (100 to 667 cm−1), thus filling the current observational gap of the Earth's emission spectrum measured from space. Since these measurements contain the spectral signatures of temperature, water vapour, clouds and gases concentration, they can be exploited to strictly test General Circulation Models (GCMs), to constrain the parametrizations of sub-grid-process and to monitor the evolution of the climate system.

In this work, 12 years (2008-2019) of IASI Metop-A measurements are compared to simulated spectral radiances provided by the EC-Earth GCM (ECE, version 3.3.3) based on the atmospheric and surface fields predicted in all-sky conditions by the model. An innovative strategy is adopted to consider the cloud variability within the large model grid cell (roughly 80-km grid spacing near the equator) and to optimally compare the climate model outputs with the higher spatial resolution (about 15 km of diameter) observations performed by the instrument. The spectral radiances are simulated online every 3 hours by the σ-IASI radiative transfer model, that has been previously embedded in the climate model through the Cloud Feedback Model Intercomparison Project (COSP) module. The comparison is performed on both low-resolution bands, between 190 to 2500 cm−1, and on selected high-resolution channels, that mimic IASI and FORUM observation in the MIR and in the FIR regions.   

Furthermore, spectral radiances are simulated by the EC-Earth climate models for two RCP climate scenarios (RCP 4.5 and RCP 8.5) spanning the time period from 2015 to 2035. 

The comparison between simulated and observed spectral radiances and the study of spectral trends within climate scenarios featuring distinct radiative forcing aids in elucidating the link with the evolution of key climate variables, to characterize relevant driving mechanisms and to determine how these observations can potentially help to identify biases in climate model simulations.

 

REFERENCES

Della Fera, S., Fabiano, F., Raspollini, P., Ridolfi, M., Cortesi, U., Barbara, F., and von Hardenberg, J.: On the use of Infrared Atmospheric Sounding Interferometer (IASI) spectrally resolved radiances to test the EC-Earth climate model (v3.3.3) in clear-sky conditions, Geosci. Model Dev., 16, 1379–1394, https://doi.org/10.5194/gmd-16-1379-2023, 2023 

Whitburn, S., Clarisse, L., Bouillon, M. et al. Trends in spectrally resolved outgoing longwave radiation from 10 years of satellite measurements. npj Clim Atmos Sci 4, 48 (2021). https://doi.org/10.1038/s41612-021-00205-7

HUANG, Xianglei, et al. A Synopsis of AIRS Global‐Mean Clear‐Sky Radiance Trends From 2003 to 2020. Journal of Geophysical Research: Atmospheres, 2022, 127.24: e2022JD037598. 

How to cite: Della Fera, S., Fabiano, F., Libois, Q., Leonarski, L., Masiello, G., Raspollini, P., Ridolfi, M., von Hardenberg, J., and Cortesi, U.: Climate evolution in the spectral signatures of simulated and observed radiances, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10684, https://doi.org/10.5194/egusphere-egu24-10684, 2024.

EGU24-12717 | Orals | CL2.1

Potential impacts of launch and orbital debris re-entry emissions 

Karen Rosenlof and Christopher Maloney

The recent surge in rocket launch rates, including the proposal of large low earth orbit satellite constellations (LLC’s) has renewed interest into how space traffic may impact Earth’s climate. In the future.  The current annual mass flux from satellites vaporized in Earth’s middle atmosphere each year is ~0.4 Gg, well below the ~20 Gg/year natural mass emissions from meteor ablation. However, it is predicted that if all proposed LLC’s are implemented, the total number of satellites in low earth orbit (LEO) will balloon from ~5,000 to over 60,000 units. The corresponding annual emissions from satellite re-entry is also expected to increase and approach 10 Gg/yr. Although little is currently known about the composition of  aerosols released during satellite ablation, we assume a significant portion of the aerosol population is metallic aluminum that will convert to aluminum oxide (Al2O3). Here we present results from a study which focuses on the radiative impacts and atmospheric transport of hypothetical Al2O3 emissions from satellite re-entry. The WACCM6 global model coupled with the CARMA sectional model was run with a 10 Gg/year mass flux of alumina aerosol between 60 km and 70 km. We evaluate how aerosol size and latitude of emission may impact the overall transport, atmospheric burden, and radiative impacts from satellite re-entry.

 

How to cite: Rosenlof, K. and Maloney, C.: Potential impacts of launch and orbital debris re-entry emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12717, https://doi.org/10.5194/egusphere-egu24-12717, 2024.

EGU24-12777 | Orals | CL2.1 | Highlight | CL Division Outstanding ECS Award Lecture

The pattern effect: How radiative feedbacks depend on surface warming patterns and influence near-term projections  

Maria Rugenstein

Recent research has highlighted that radiative feedbacks — and thus climate sensitivity — are not constant in time but depend sensitively on sea surface temperature patterns. I will discuss three implications of this realization.

First, I will show how coupled climate models fail to reproduce observed surface warming patterns and global mean top of the atmosphere (TOA) radiation trends. I use large initial condition ensembles to compare observations to account for internal variability and model mean-state biases. For certain periods, not a single ensemble member can reproduce observed values of surface temperature trends and TOA radiation trends. Models which more greatly underestimate the observed local sensitivity of surface and TOA, and models with a weak variability in the Equatorial Pacific surface temperatures tend to have a higher equilibrium climate sensitivity. Despite these astonishing observation-model discrepancies their global-mean temperatures are simulated well which points to a common model problem in surface heat fluxes and ocean heat uptake.

Second, I will discuss the relevance of the pattern effect for climate change projections. Given that problems coupled models have in reproducing observed warming patterns, we should doubt their pattern evolution in projections. I will introduce “surface warming pattern storylines” starting from the observations and bridging to simulated future patterns in standard scenarios. I show that (CMIP) coupled climate models used ubiquitously for climate change projections underestimate the uncertainty of possible global-mean temperature evolutions due to their surface warming patterns throughout the 21st century.

Third, I will introduce how a feed-forward convolutional neural network (CNN) can be trained to learn the pattern effect and predict global-mean TOA radiation from surface warming patterns. I use explainable artificial intelligence methods to visualize and quantify that the CNN draws its predictive skill for physically meaningful reasons. Remarkably and different from traditional approaches, I can predict radiation under strong climate change from training the CNN on internal variability alone. This out-of-sample application works only when feedbacks are allowed to be non-linear or equivalent, changing in time, which is another, independent manifestation of the relevance of the pattern effect.

How to cite: Rugenstein, M.: The pattern effect: How radiative feedbacks depend on surface warming patterns and influence near-term projections , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12777, https://doi.org/10.5194/egusphere-egu24-12777, 2024.

EGU24-12901 | Orals | CL2.1

Assessment of atmospheric and surface energy budgets using observation-based data products 

Michael Mayer, Seiji Kato, Michael Bosilovich, Peter Bechtold, Johannes Mayer, Marc Schroeder, Ali Behrangi, Shinya Kobayashi, Brent Roberts, and Tristan L'Ecuyer

Accurate diagnosis of regional atmospheric and surface energy budgets is a critical component for understanding the spatial distribution of the Earth’s Energy Imbalance (EEI). This contribution reviews frameworks and methods for consistent evaluation of key quantities of those budgets using observationally constrained data sets. It thereby touches upon assumptions made in data products which have implications for these evaluations. We evaluate 2001-2020 average regional total (TE) and dry static energy (DSE) budgets using satellite-based and reanalysis data. Uncertainties of the computed budgets are assessed through inter-product spread and evaluation of physical constraints. Furthermore, we infer fields of net surface energy flux by combining top-of-atmosphere radiative fluxes from satellites with reanalysis-based atmospheric TE budget terms (i.e., divergence and storage of energy). Results indicate biases <1 W/m2 on the global, <5 W/m2 on the continental, and ~15 W/m2 on the regional scale. Inferred surface energy fluxes exhibit reduced large-scale biases compared to surface flux data based on remote sensing and models. We use the DSE budget to infer atmospheric diabatic heating from condensational processes. Comparison to observation-based precipitation data indicates larger uncertainties (10-15 Wm-2 globally) in the DSE budget compared to the TE budget, which is reflected by increased spread in reanalysis-based fields. Continued validation efforts of atmospheric energy budgets are needed to document progress in new and upcoming observational products, and to understand their limitations when performing EEI research.

How to cite: Mayer, M., Kato, S., Bosilovich, M., Bechtold, P., Mayer, J., Schroeder, M., Behrangi, A., Kobayashi, S., Roberts, B., and L'Ecuyer, T.: Assessment of atmospheric and surface energy budgets using observation-based data products, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12901, https://doi.org/10.5194/egusphere-egu24-12901, 2024.

EGU24-14006 | Posters on site | CL2.1

Assessing the Variability of Radiation, Water and Energy in the Deep Tropics Over the Last 3 Decades 

Paul Stackhouse, Stephen Cox, J. Colleen Mikovitz, Taiping Zhang, and Nicolas Leitmann-Niimi

Global surface energy closure and its variability depends heavily upon the surface radiative energy budget in the deep tropics.  A key process observed is the change in convection regimes from disorganized convection to organized deep convection.  During these periods an imbalance is observed between energy and water fluxes in terms of energy closure in some atmospheric reanalysis systems, implying that processes are not simulated well.  A recent paper by Hsaio et al (2023, pre-published version) found that the transition process has wind shear and longwave cloud radiative feedback signatures.  In this presentation, we assess the surface radiative budget in the deep tropics by comparing multiple data products (GEWEX SRB Rel4IP, CERES Ed4.1, ISSCP FH, etc.) and describing the variability across the deep tropics for the period from 1988 to near present.  We assess this variability of the radiative flux anomalies (including the net TOA, surface and the atmospheric divergence fluxes) against water vapor divergence, cloud properties (include ISCCP “Weather States, Tselioudis et al. 2021) and larger scale wind shear.  We include further analysis contrasting 6 key tropical oceanic regions (Indian Ocean east and west, tropical western, central and eastern Pacific Ocean, and Tropical Atlantic Ocean) and the sensitivity of the fluxes as a function of fluctuations in cloud types in response to various larger scale atmospheric processes (e.g. El Niño, Indian Ocean Dipole).  These are contrasted against the modeled radiative fluxes from ERA-5 and MERRA-2.  Ocean buoy measurements of radiative fluxes are utilized to help assess data radiative flux uncertainty over the nearly 40 year period.  In general, the variability for overlap periods of these various data products agrees well, but there are significant differences in the net fluxes that vary according to the rendering of surface, atmospheric, aerosol and cloud properties.  We conclude with recommendations for continuing work.

How to cite: Stackhouse, P., Cox, S., Mikovitz, J. C., Zhang, T., and Leitmann-Niimi, N.: Assessing the Variability of Radiation, Water and Energy in the Deep Tropics Over the Last 3 Decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14006, https://doi.org/10.5194/egusphere-egu24-14006, 2024.

EGU24-14047 | ECS | Orals | CL2.1

A Spaceborne Camera To Augment Future Earth Radiation Budget Satellite Observations 

Jake Gristey and Sebastian Schmidt

Earth radiation budget (ERB) satellite observations require conversion of the measured radiance, which is a remotely-sensed quantity, to a derived irradiance, which is the relevant energy balance quantity routinely used in modelling and analysis of the climate system. The state-of-the-art approach for radiance-to-irradiance conversion taken by the Clouds and the Earth's Radiant Energy System (CERES) benefits from the exhaustive sampling of radiance anisotropy by multiple CERES instruments across many years. Unfortunately, the CERES approach is not easily extended to new ERB spectral channels that lack previous sampling, such as the “split-shortwave” planned to be part of the next-generation ERB mission: Libera. As an alternative approach, the capability of a monochromatic, wide-field-of-view camera to provide dense angular sampling in a much shorter timeframe is assessed. We present a general concept for how this can be achieved and quantify the proficiency of a camera to provide rapid angular distribution model (ADM) generation for the new Libera ultraviolet-and-visible (VIS) sub-band. A single mid-visible camera wavelength (555 nm) is shown to be ideal for representing the VIS sub-band, requiring only basic scene stratification for 555 nm to VIS conversion. Synthetic camera sampling with realistic operating constraints also demonstrates that the angular radiance field of various scenes can be well populated within a single day of sampling, a notable advance over existing approaches. These results provide a path for generating observationally-based VIS ADMs with minimal lag time following Libera’s launch. Coupled with efforts to utilize a camera for scene identification, this may also pave the way for future ERB satellite systems to develop stand-alone irradiance products for arbitrary sets of spectral channels, opening up new measurement and science possibilities.

How to cite: Gristey, J. and Schmidt, S.: A Spaceborne Camera To Augment Future Earth Radiation Budget Satellite Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14047, https://doi.org/10.5194/egusphere-egu24-14047, 2024.

EGU24-15022 | ECS | Orals | CL2.1

In-situ Measurements of the Emissivity of Ice and Snow surfaces in the Mid- and Far-infrared 

Laura Warwick, Jonathan Murray, Sanjeevani Panditharatne, Helen Brindley, Dirk Schuettemeyer, and Hilke Oetjen

Knowledge of the emissivity of the Earth’s surface is vital for understanding the Earth’s radiation budget. However, there is a lack of emissivity measurements in the far-infrared (wavenumbers less than 667 cm-1 or wavelengths greater than 15 μm) despite studies showing that the surface emissivity in these regions can have a discernible impact on the outgoing longwave radiation. In-situ measurements of surface emissivity in the far-infrared are also needed to support the upcoming far-infrared satellite missions; the Polar Radiant Energy in the Far-InfraRed Experiment (PREFIRE) developed by NASA and due to launch in spring 2024, and the European Space Agency’s Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission due to launch in 2027.

To fill this observational gap, the Far INfrarEd Spectrometer for Surface Emissivity (FINESSE) was developed at Imperial College London. FINESSE has a spectral range of 400 to 1600 cm-1 (6.25 to 25μm) and is designed for in-situ measurements of surface emissivity, particularly in cold climates.

In this presentation we present observations from the first deployment of FINESSE to the ALOMAR observatory in Northern Norway (69°16' N, 16° 0' E). We describe the campaign, the radiance measurements made by FINESSE and the auxiliary data taken. We then outline the method used to determine the surface temperature and emissivity and finally present the retrieved emissivity of the ice and snow surfaces.

How to cite: Warwick, L., Murray, J., Panditharatne, S., Brindley, H., Schuettemeyer, D., and Oetjen, H.: In-situ Measurements of the Emissivity of Ice and Snow surfaces in the Mid- and Far-infrared, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15022, https://doi.org/10.5194/egusphere-egu24-15022, 2024.

EGU24-16988 | ECS | Orals | CL2.1

Assessing lidar ratio impact on CALIPSO retrievals utilized for estimating aerosol shortwave direct radiative effects over the NAMEE domain 

Anna Moustaka, Marios-Bruno Korras-Carraca, Kyriakoula Papachristopoulou, Michael Stamatis, Emmanouil Proestakis, Ilias Fountoulakis, Stelios Kazadzis, Vassilis Amiridis, Kleareti Tourpali, Stavros Solomos, Christos Spyrou, Christos Zerefos, and Antonis Gkikas

One of the most vulnerable regions to climate change is the NAMEE (North Africa Middle East Europe) domain, hosting a variety of aerosol species of both natural and anthropogenic origin. This is one of the reasons why NAMEE constitutes an ideal region for assessing the aerosol-induced direct radiative effects (DREs) within the Earth-Atmosphere system. The overarching goal of the present study is to estimate clear-sky shortwave DREs via a holistic approach involving spaceborne retrievals, radiative transfer simulations and aerosol/radiation observations. We emphasize on the importance and sensitivity of the aerosol-speciated lidar ratio (LR) on calculating DREs. Our main dataset consists of CALIOP-CALIPSO backscatter coefficient vertically resolved retrievals (Level 2, Version 4.20) extracted from the LIVAS (LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies) database (2007-2020). Besides the CALIPSO aerosol optical depth (AOD) retrieval, the aerosol-speciated LRs based on the newly developed DeLiAn database, a collection of state-of-the-art ground-based measurements acquired by lidars operating at different regions of the world affected by various aerosol types, are also applied to the CALIPSO backscatter coefficient profiles for the calculation of a more representative AOD. Through a series of quality assurance filtering we conclude to 550 case studies collocated against ground-based AERONET stations characterized by either dust, marine, polluted continental/smoke, elevated smoke or clean continental aerosol layers according to the latest CALIPSO (V4) aerosol classification algorithm scheme. For the radiative transfer simulations, the libRadtran Radiative Transfer Model (RTM) is implemented for the spectral range of 250–5000 nm using a 4-stream plane parallel approximation. The CALIPSO aerosol-speciated AOD profiles at 532 nm along with lookup tables of spectrally resolved optical properties extracted from the AERONET almucantar retrievals make up the aerosol RTM inputs. For the surface inputs, the MODIS snow-free BRDF/albedo dataset and the libRadTran built-in IGBP albedo library are utilized. The columnar concentrations of ozone and water vapour are extracted from the MERRA-2 reanalysis. The simulated solar fluxes at TOA and at the surface are evaluated against satellite (CERES) and ground-based (BSRN) observations for cloudless conditions, respectively. Our key finding is that the consideration of the DeLiAn-based LR leads to more representative DREs and improves the simulated solar fluxes when mineral particles dominate.    

Acknowledgements: Authors acknowledge support by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “2nd Call for H.F.R.I. Research Projects to support Post-Doctoral Researchers” (Project Acronym:  ATLANTAS, Project number:  544). Part of this work was supported by the COST Action Harmonia (CA21119) supported by COST (European Cooperation in Science and Technology)

How to cite: Moustaka, A., Korras-Carraca, M.-B., Papachristopoulou, K., Stamatis, M., Proestakis, E., Fountoulakis, I., Kazadzis, S., Amiridis, V., Tourpali, K., Solomos, S., Spyrou, C., Zerefos, C., and Gkikas, A.: Assessing lidar ratio impact on CALIPSO retrievals utilized for estimating aerosol shortwave direct radiative effects over the NAMEE domain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16988, https://doi.org/10.5194/egusphere-egu24-16988, 2024.

EGU24-17804 | ECS | Posters on site | CL2.1

Effects of long-term changes in anthropogenic aerosol emissions on shortwave radiative flux and cloud variables over the North Pacific 

Jingyi Liu, Ken Carslaw, Daniel Grosvenor, Xin Huang, and Aijun Ding

China's high-intensity anthropogenic emissions have strongly affected regional aerosols, weather and climate over recent decades. Affected by the typical circulations in the Asian monsoon region, aerosols over the North Pacific are closely related to emissions from China. However, how changes in aerosol emissions from China has affected changes in aerosols, clouds and radiation over the North Pacific on the timescale of decades have not been explored in detail.

In this study, using in situ and satellite observations together with model data, we investigate the long-term trends of anthropogenic emissions, aerosols, cloud properties and top-of-atmosphere (TOA) net downward shortwave radiation flux (Fsw↓) over China and the North Pacific, and discussed the potential effects of aerosol on changes in Fsw↓ over the North Pacific. Anthropogenic emissions in China have undergone significant changes in the past few decades, 1960-2020. They show a similar increasing trend before 2000 and then start to fluctuate and decline. The significant turning points of observed visibility and PM2.5 occur around 2000 and 2013 due to the successive implementation of clean air policies. The coefficient of correlation between the two regions is 0.857 for Aerosol Optical Depth (AOD) and 0.953 for Aerosol Index (AI), indicating that aerosols in the two regions are highly correlated.

We use the MERRA-2 model outputs to investigate the Fsw↓ trends and diagnose the potential impact of aerosols on shortwave radiative fluxes. The Fsw↓ over the North Pacific shows a faster decline trend (-0.16 W m-2 y-1) compared to the trend without aerosols (-0.11 W m-2 y-1) during 1980-2000 (defined as the pre-2000 period), which is mainly driven by the enhanced cooling effect of increasing aerosols associated with growth in the anthropogenic emissions of East China. However, the Fsw↓shows an upward trend (+0.12 W m-2 y-1) during 2000-2020 (the post-2000 period), accompanied by a downward trend of cloud droplet number concentration (decreased by 13.9% during 2003-2020). The cooling effect of aerosols causes an overall reduction in the annual mean values of Fsw↓ of 3.5 W m-2 in the pre-2000 period,and 2.9 W m-2 in the post-2000 period, indicating that the aerosol forcing is weakened by 17%. To understand the trends and explore the dominant driven factors of Fsw↓ in different periods, we use multiple simulations of the UK Earth System Model. We will show the contributions of anthropogenic emissions to trends in aerosol-radiation interactions (ARI) and aerosol-cloud interactions (ACI) over the North Pacific, and quantify how changes in aerosol and other climate variables have contributed to the observed trends in Fsw↓ over the North Pacific caused by changes in cloud droplet concentrations, cloud fraction and liquid water path.

How to cite: Liu, J., Carslaw, K., Grosvenor, D., Huang, X., and Ding, A.: Effects of long-term changes in anthropogenic aerosol emissions on shortwave radiative flux and cloud variables over the North Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17804, https://doi.org/10.5194/egusphere-egu24-17804, 2024.

EGU24-17894 | ECS | Orals | CL2.1

A comprehensive study on the causes of Global Dimming and Brightening using a radiative transfer model and satellite and reanalysis input data  

Michael Stamatis, Nikolaos Hatzianastassiou, Marios Bruno Korras Carraca, Christos Matsoukas, Martin Wild, and Ilias Vardavas

Global Dimming and Brightening (GDB), which refers to the decrease/increase of incoming total solar radiation at the Earth's surface (or surface solar radiation, SSR) due to natural or anthropogenic composition changes of the Earth’s atmosphere, plays an important role in the Earth’s climate. According to the literature, the main drivers of the phenomenon are aerosols and clouds, contributing to GDB to different degrees depending on the world region and time period. This study aims, using a detailed spectral radiation transfer model (RTM), to identify and quantify the causes of GDB worldwide on a climatological scale. Specifically, it intends to determine their contribution to GDB as well as their spatio-temporal variability, performing detailed analyses on a monthly basis and a spatial latitude/longitude resolution of 0.5°x0.625°, all over the globe and for the 35-year period 1984-2018. The RTM required input data, such as those for cloud and aerosol optical properties, are taken from a synergy of satellite and reanalysis databases, namely the EUMETSAT’s CLARA-A2 and the NASA’s ISCCP-H and MERRA-2. Model runs, which are the main/base runs, are performed at the aforementioned spatial and temporal resolution and coverage to accurately calculate solar fluxes and GDB. Τhe contribution of clouds (cloud amount-CA and cloud optical thickness-COT of low, middle, high and total clouds), aerosol optical properties (aerosol optical depth-AOD, single scattering albedo-SSA and asymmetry parameter-AP), water vapor and ozone to GDB during the 35-year period 1984-2018 are calculated through RTM computations in which each parameter is kept ‘frozen’ at its initial conditions, namely the first year of the study period (namely 1984). Then, the contribution of a parameter P to the overall GDB is estimated from the difference between the GDB of the main RTM run, with all parameters being activated, and the GDB of the run with ‘frozen’ P parameter. In addition to the overall 35-year investigation, the study is also conducted on a decadal time scale, as well as on global, hemispherical, regional, and land/ocean spatial scales, in order to investigate the contribution of each parameter to GDB in more detail.

How to cite: Stamatis, M., Hatzianastassiou, N., Korras Carraca, M. B., Matsoukas, C., Wild, M., and Vardavas, I.: A comprehensive study on the causes of Global Dimming and Brightening using a radiative transfer model and satellite and reanalysis input data , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17894, https://doi.org/10.5194/egusphere-egu24-17894, 2024.

The Global Energy Balance Archive (GEBA) was founded by Professor Atsumu Ohmura after the (meta)data collection started in the early 1980s. Maintained at ETH Zurich, GEBA stores worldwide measured energy fluxes at the Earth’s surface over several decades (Wild et al. 2017). The knowledge of their spatio-temporal distribution is essential for understanding the genesis and evolution of the Earth’s climate and required for practical applications in the sectors of renewable energy, agriculture, water management and tourism. GEBA currently contains more than 700,000 monthly mean entries for various energy balance components, the most widely represented one being global (incoming shortwave) radiation. The observations at more than 2700 stations come from a variety of sources in heterogeneous formats. Data accessed through GEBA have been used in numerous scientific publications dealing with e.g. the quantification of the Earth’s energy balance, the estimation of long-term trends, which enabled the detection of multi-decadal variations known as “global dimming” and “brightening”, and the evaluation of surface fluxes in climate models and satellite-derived products. First organized in an Oracle relational database, GEBA serves the climate community since 1991 and (meta)data, associated with quality flags, are available on the internet since 1997. Recently, GEBA necessitated a technical revision of its infrastructure dating back to the 1990s, process automation and update of its contents. The ongoing major re-design and operational maintenance work is co-​funded since 2019 by the Federal Office of Meteorology and Climatology (MeteoSwiss) within the framework of the Global Climate Observing System (GCOS) Switzerland, according to its climate monitoring principle #10 “Data management systems that facilitate access, use and interpretation of data and products should be included as essential elements of climate monitoring systems”.

This poster presents (i) the challenges of the recent migration of GEBA to an open-source PostgreSQL platform, (ii) the state-of-the-art re-implementation of the web access interface displaying up-to-date database content status and allowing, after registration, user-friendlier data search, (iii) the key role GEBA plays in various research applications, and (iv) opportunities for quality improvement and future expansion. The new flexible and history-aware relational model (schema) and processing layer for computing derived data strive to solve inconsistency and redundancy issues in (meta)data structure and meet standardization goals (ISO, WMO, WRR), developer and user needs. Feedback from experts and offers from potential data contributors will be welcome and integrated into the project’s evolution.

We gratefully acknowledge the (meta)data sources (including WRDC, BSRN, ARM, SURFRAD, national weather services, project reports, OSCAR/Surface) and many observers in the field. We are indebted to the IT Services of ETH Zürich and the ETH “DocJob” students.

 

Reference:

Wild, M., A. Ohmura, C. Schär, G. Müller, D. Folini, M. Schwarz, M. Z. Hakuba, A. Sanchez-Lorenzo (2017), The Global Energy Balance Archive (GEBA) version 2017: a database for worldwide measured surface energy fluxes, Earth System Science Data, 9, 601-613.

How to cite: Wild, M. and Smith, P.: The Global Energy Balance Archive (GEBA) – Recent Developments, Current Database Access, Use for Research, Future Expansion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18254, https://doi.org/10.5194/egusphere-egu24-18254, 2024.

EGU24-18872 | Orals | CL2.1

Singular Vector Decomposition (SVD) of satellite datasets: relation between cloud properties, radiative fluxes and climate indices. 

Elisa Carboni, Gareth Thomas, Richard Siddans, and Brian Kerridge

We describe a technique, singular vector decomposition (SVD), that can identify the spatial patterns that best describe the temporal variability of a global satellite dataset. These patterns, and their temporal evolution are then correlated with established climate indices. 
We apply this technique to datasets of cloud properties and radiative  fluxes over three decades ((A)ATSR/SLSTR, MODIS, IASI and CERES), but it can be more generically used to extract the pattern of variability of any regular gridded dataset such as different parameters from satellite retrieval and models.
Leading singular vector for independent global data sets on both cloud properties (cloud fraction, cloud-top height) 
and TOA radiative fluxes, from polar orbiting satellites, covering different time periods is strongly correlated with ENSO index.
SVD approach can provide incites into the underlying causes of observed changes in a particular dataset and provide a new tool in using global satellite observations in assessing global climate model (GCM) performance.

How to cite: Carboni, E., Thomas, G., Siddans, R., and Kerridge, B.: Singular Vector Decomposition (SVD) of satellite datasets: relation between cloud properties, radiative fluxes and climate indices., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18872, https://doi.org/10.5194/egusphere-egu24-18872, 2024.

EGU24-19187 | ECS | Orals | CL2.1

Development of a hyperspectral spatio-temporal surface albedo dataset for Earth 

Giulia Roccetti, Luca Bugliaro, Felix Gödde, Claudia Emde, Mihail Manev, Michael Sterzik, Cedric Wehrum, and Ulrich Hamann
Surface albedo is a crucial component of accurate radiative transfer simulations of Earth's system, playing a key role in calculating the planet's energy budget. The MODIS Surface Reflectance dataset (MCD43C3, Version 6.1) provides detailed albedo maps across seven spectral bands, enabling the monitoring of daily and yearly changes in planetary surface albedo. However, a comprehensive set of albedo maps covering the entire wavelength range is essential for simulating radiance spectra and accurately retrieving atmospheric and cloud properties in Earth's remote sensing. Braghiere et al. (2023) highlighted the impact of simplistic assumptions on albedo maps in Earth System Models, estimating a 3.55 W m-2 divergence in radiative forcing when using hyperspectral albedo maps instead of the commonly employed two broadband albedo value approach. They find that omitting the hyperspectral nature of Earth’s surface causes deviation in many climatological patterns, such as precipitation and surface temperature, over regional scales.
 
We average the MODIS datasets over a 10-years period for different times of the year, obtaining a MODIS climatological dataset. Thanks to both high spatial and temporal resolution, we study albedo seasonal and spatial variability in the seven MODIS bands, obtaining estimates of the surface reflectivity as a function of space and time.
 
This MODIS climatological average is the starting point to generate hyperspectral albedo maps using a Principal Component Analysis (PCA) regression algorithm. Combining different datasets of hyperspectral reflectance laboratory measurements for various dry soils, vegetation surfaces, and mixtures of both, we reconstruct the albedo maps in the entire wavelength range from 400 to 2500 nm. We obtain hyperspectral albedo maps with a spatial resolution of 0.05° in latitude and longitude, a spectral resolution of 10 nm, and a temporal resolution of 8 days. The hyperspectral albedo maps are validated against SEVIRI and TROPOMI land surface products.
 
Using the spectral dimension of our albedo maps, we select different land surface types such as forests, deserts, cities and icy surfaces, and we integrate their spectral profiles over entire regions. In this way, it is possible to reconstruct regional spectral patterns which are the combination of typical vegetation and surface spectral features, like the Vegetation Red Edge. In addition, we study the seasonal variability of every region averaging spatially integrated spectra over three months period. From these seasonal spectra, we clearly see the impact of snow cover over different regions, the difference between wet and dry seasons over boreal forests and the formation of lakes over Greenland during the boreal summer. This hyperspectral albedo dataset will lead to more refined calculations of Earth's energy budget, its seasonal variability, and could be used to improve climate simulations.

How to cite: Roccetti, G., Bugliaro, L., Gödde, F., Emde, C., Manev, M., Sterzik, M., Wehrum, C., and Hamann, U.: Development of a hyperspectral spatio-temporal surface albedo dataset for Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19187, https://doi.org/10.5194/egusphere-egu24-19187, 2024.

EGU24-1193 | ECS | Posters on site | CL2.3

Climate drivers of meteorological droughts in north-western Europe (1836-2022) 

Emile Neimry, Hugues Goosse, and Mathieu Jonard

Droughts have garnered global attention due to their adverse effects on crops, ecosystems, and society. Despite their frequent occurrence in north-western Europe, the causes of these droughts remain poorly understood. This study investigates the historical climate drivers of meteorological droughts in the region. The identification of drought events since 1836 is conducted using the Standardized Precipitation Evapotranspiration Index at a 3-month scale, based on reanalysis datasets (ERA5 and 20CRv3). Subsequently, by employing clustering methods, we categorize the diverse atmospheric conditions leading to droughts into discernible patterns. Our next objective is to assess the long-term variability and trends within these patterns. This research provides a long-term regional analysis of meteorological drought drivers, contributing to a deeper understanding of regional climate changes over the past two centuries.

How to cite: Neimry, E., Goosse, H., and Jonard, M.: Climate drivers of meteorological droughts in north-western Europe (1836-2022), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1193, https://doi.org/10.5194/egusphere-egu24-1193, 2024.

EGU24-1722 | ECS | Orals | CL2.3

Revealing a systematic bias in percentile-based temperature extremes 

Lukas Brunner and Aiko Voigt

Worsening temperature extremes are among the most severe impacts of human-induced climate change. To quantify such extremes and their changes various methods have been applied over the years. One frequently used approach is to define extremes relative to the local temperature distribution as exceedances of a given percentile threshold. 

For hot extremes, the Expert Team on Climate Change Detection and Indices (ETCCDI) defines TX90p relative to the 90th percentile of maximum temperature on each calendar day in the 30-year period 1961-1990. To increase the number of samples available for the percentile calculation a 5-day running window is recommended leading to a total of 30x5=150 samples for each calendar day. However, this still limited number of samples can lead to internal variability being mixed into the percentile and cause a strongly varying extreme threshold, which is undesirable. Therefore, many studies do not follow the ETCCDI recommendation and use longer seasonal windows of 15- or even 31-days to increase the number of samples available for the percentile calculation. 

We show that the use of such long seasonal windows introduces a systematic bias that leads to a striking underestimation of the expected extreme frequency. This expected exceedance frequency is 10% for the 90th percentile when evaluating the extreme frequency in the same period as the threshold is calculated (in-base). For ERA5 the 1961-1990 average, global average temperature extreme frequency is only 9% – a relative bias of -10%. In individual regions and seasons, the bias can be considerably larger, exceeding -75%. 

We develop a simple bias correction and use it to show that the bias generally decreases in a warming climate in CMIP6. It, therefore, also affects estimates of future temperature and related heatwave changes. The decrease of the bias can lead to an overestimation of changes in the heatwave frequency by as much as 30%. Based on these results, we strongly warn against the use of long seasonal windows without correction when calculating extreme frequencies and their changes.

How to cite: Brunner, L. and Voigt, A.: Revealing a systematic bias in percentile-based temperature extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1722, https://doi.org/10.5194/egusphere-egu24-1722, 2024.

EGU24-1791 | Orals | CL2.3 | Highlight

Storylines of high-impact climate events 

Theodore Shepherd

High-impact climate events are generally expected to be exacerbated by climate change. For heatwaves, heavy precipitation, and evaporatively-driven drought, the IPCC AR6 made very strong general statements about changes in hazard. But as soon as one attempts to attribute high-impact climate events, the particular details of those events (which are inevitably compound events) and of the human-managed environment take centre stage. Because real-world events are not independent and identically distributed, one cannot reliably apply a general statement to a particular event. This basic aspect of statistical inference, widely recognized in other fields, seems not well appreciated within the climate science community. Physical climate storylines (physically-based unfoldings of past climate or weather events, or of plausible future events or pathways) offer a way to respect the complexity of high-impact climate events and the multiple causal factors involved, of which climate change will only be one. Indeed, identifying the non-climatic factors that affect vulnerability and exposure is essential for good decision-making around climate adaptation. In this talk I will describe the rationale behind the use of storylines for high-impact climate events from the broader perspective of attribution, and explain how conditional attribution allows probability and risk to enter in a physically interpretable and meaningful way.

How to cite: Shepherd, T.: Storylines of high-impact climate events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1791, https://doi.org/10.5194/egusphere-egu24-1791, 2024.

EGU24-2132 | ECS | Posters on site | CL2.3

A Regional Perspective of Storyline Simulations of the Recent European Summer Heatwaves 

Tatiana Klimiuk, Patrick Ludwig, Antonio Sánchez Benítez, Helge Goessling, Peter Braesicke, and Joaquim G. Pinto

Heatwaves are a major natural hazard affecting Europe, and their maximum temperatures are projected to increase strongly with climate change. In recent years, the event-based storyline approach has proven its applicability for climate change attribution studies. Constraining the large-scale dynamics to that of the recent past serves to separate the thermodynamic effects of increasing greenhouse gas concentrations from the largely uncertain dynamic changes. Within the SCENIC project, the storylines are produced with the spectrally nudged global coupled AWI-CM1 model (90 km horizontal resolution). They are downscaled with ICON-CLM to the Euro-Cordex (12 km) and subsequently to the central European domain (3 km). Using this model chain, we captured the series of European summer heat waves and droughts of 2018-2022. We placed them into the pre-industrial climate and three environments corresponding to +2, +3, and +4 K warmer worlds. We quantified the warming rate per degree of global warming (which sometimes exceeds 2.5 over larger areas) and assessed the role of soil-atmosphere feedback in contributing to these rates. More specifically, for several European heatwaves, we explored the connection of the evaporative regime of a region affected by a heatwave to the region's response to global warming during this event. Taking advantage of the high signal-to-noise ratio of event-based storylines, we add one more dimension - the global warming level - to the scope of land-atmosphere feedback studies.

How to cite: Klimiuk, T., Ludwig, P., Sánchez Benítez, A., Goessling, H., Braesicke, P., and G. Pinto, J.: A Regional Perspective of Storyline Simulations of the Recent European Summer Heatwaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2132, https://doi.org/10.5194/egusphere-egu24-2132, 2024.

EGU24-2258 | ECS | Posters on site | CL2.3

Storyline approach for the analysis of the 2012 drought in Serbia and possible future similar events 

Milica Tosic, Vladimir Djurdjevic, Ivana Tosic, and Irida Lazic

In 2012, Serbia experienced one of its warmest and driest years on record. The summer of 2012 marked the highest temperatures recorded since meteorological measurements began in Serbia, in relation to the reference period from 1991 to 2020. Throughout the summer, the entire country faced severe drought conditions persisting until the end of November. Serbia's agriculture is very vulnerable to drought - an estimated annual economic loss is approximately 2 billion euros due to extreme 2012 drought. Recent studies emphasize the value of the storyline approach in offering a comprehensive and manageable framework for evaluating environmental, societal and economic risks associated with climate change. Considering the potential for more intense climate events resulting from climate change, we decided to apply the storyline approach, to determine what future events similar to drought 2012 might look like and how they are influenced by different climate change scenarios. We constructed drought metrics based on precipitation deficit, following the method proposed by van der Wiel et al. [1], and with the use of the EOBS dataset. Analyzing future scenarios involved creating a meteorological analogue to the 2012 drought, using single model large ensemble historical and future scenario simulations from CMIP6 database - the MPI-M Earth System Model version 1.2, for different SSP scenarios. This analysis offers insights into different storylines, aiding the assessment of climate risks and the potential impacts of hypothetical drought scenarios.

The summer of 2012 was extraordinarily warm, and, as previous studies show significant changes in temperature extremes during the summer season in Serbia, we included analyses of temperature anomalies during the summer. Additionally, to create more comprehensive storylines, our study involves analyzing large-scale atmospheric patterns. Our results show an increase in drought severity in a warmer future, offering an enhanced understanding of how extreme events like the 2012 drought (or more severe) are changing measurably due to climate change, and provide examples of potential impacts, in order to raise public awareness about the potential consequences of future climate change in Serbia.

[1] van der Wiel, K., Lenderink, G. and de Vries, H., 2021. Physical storylines of future European drought events like 2018 based on ensemble climate modelling. Weather and Climate Extremes33, p.100350.

How to cite: Tosic, M., Djurdjevic, V., Tosic, I., and Lazic, I.: Storyline approach for the analysis of the 2012 drought in Serbia and possible future similar events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2258, https://doi.org/10.5194/egusphere-egu24-2258, 2024.

EGU24-2286 | ECS | Posters on site | CL2.3

Extreme rainfall in Northern China in September 2021 tied to air–sea multi‐factors 

Yue Sun, Jianping Li, Hao Wang, Ruize Li, and Xinxin Tang

The September rainfall over Northern China (NC) in 2021 was the heaviest since 1961 and had unprecedented socioeconomic impacts. Holding the hypothesis that the drivers of extreme climate events usually contain extreme factors, we firstly propose the Ranking Attribution Method (RAM) to find the possible air–sea multi-factors responsible for this rainfall event. Via the atmospheric bridges of zonal-vertical circulation and Rossby wave energy propagation, the remote factors of warm sea surface temperature anomalies (SSTA) over the tropical Atlantic, cold SSTA over the tropical Pacific, Southern Annular Mode-like pattern in the Southern Hemisphere and North Pacific Oscillation-like pattern in the Northern Hemisphere jointly strengthened the Maritime Continent (MC) convection and Indian monsoon (IM). Through meridional-vertical circulation, the intensified MC convection enhanced the subtropical high over southern China and induced ascending motion over NC. The local factor of extreme air acceleration in the east Asian upper-level jet entrance region further anchored the location of the southwest-northeast rain belt. The strengthened IM and subtropical high over southern China induced considerable moisture transport to the rain belt via two moisture channels. The combined effect of these extreme dynamic and moisture conditions formed this unprecedented rainfall event. This study suggests that the RAM can effectively reveal the factors that contributed to this extreme rainfall event, which could provide a new pathway for a better understanding of extreme climate events.

How to cite: Sun, Y., Li, J., Wang, H., Li, R., and Tang, X.: Extreme rainfall in Northern China in September 2021 tied to air–sea multi‐factors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2286, https://doi.org/10.5194/egusphere-egu24-2286, 2024.

EGU24-2365 | ECS | Orals | CL2.3

Sub-seasonal UK winter precipitation intensifies in-line with expected temperature scaling 

James Carruthers, Selma Guerreiro, Hayley Fowler, and Daniel Bannister

Interannual to multi-decadal variability in large-scale dynamics such as atmospheric and oceanic circulation results in significant noise and temporary trends in regional climate. Attempting to understand longer term trends as a result of anthropogenic climate change requires disentangling internal variability and climate change signals. One of these climate signals is the Clausius-Clapeyron (CC) scaling in precipitation resulting from temperature increases. In this work, we characterise and constrain variability in sub-seasonal winter rainfall in the UK resulting from synoptic scale-conditions. The UK experiences periods of sustained precipitation in some winters which result in widespread flooding due to extreme accumulation, such as the winter of 2013/2014. Using categorised sea-level pressure fields and gridded precipitation between 1900-2020, we simulate ‘expected’ precipitation resulting from North Atlantic synoptic conditions. We find a rising trend since the 1980s in observed monthly accumulation which is not reflected in the simulated precipitation timeseries, indicating that recent wet winters in the UK have been wetter than expected given the synoptic conditions. The rising trend in the residual (observed - simulated) mean monthly precipitation is in line with expected CC scaling rate of ~6-7% per degree warming according to changes in UK annual mean temperature. However, the residual in extreme monthly precipitation has scaled at approximately twice that rate. To better understand differences in changes for average and extreme precipitation accumulation, we explore the influence of dynamical feedbacks which may increase precipitation at higher intensities. We find that residual precipitation is influenced by the persistence of synoptic conditions and exhibits remote teleconnections to sea surface temperature and atmospheric conditions in the tropics and sub-tropics. This work highlights the importance of considering variability in large-scale dynamics when identifying climate change signals and sheds light on influences on sub-seasonal to seasonal winter precipitation in the UK.ences on sub-seasonal to seasonal winter precipitation in the UK.

How to cite: Carruthers, J., Guerreiro, S., Fowler, H., and Bannister, D.: Sub-seasonal UK winter precipitation intensifies in-line with expected temperature scaling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2365, https://doi.org/10.5194/egusphere-egu24-2365, 2024.

EGU24-2574 | Orals | CL2.3

Statistically impossible temperatures. 

Michael Wehner, Mark Risser, Likun Zhang, and William Boos

The 2021 heatwave in the Pacific Northwest of the United States and Canada was unusual in many regards. In particular, not only was the event deemed impossible prior to the human interference in the climate system, standard out-of-sample non-stationary generalized extreme value (GEV) analyses revealed it to be statistically impossible in 2021 as many observed temperatures were above the upper bound of the upper bound of fitted GEV distributions. Obviously, as the event actually occurred, these statistical models are not fit for the purpose of estimating the influence of climate change on the event’s probability.

By expanding the number of physical covariates beyond just greenhouse gas concentrations and by incorporating spatial statistical techniques in a Bayesian hierarchal framework, we are able to construct a statistical model where observed temperatures during this heatwave were not “impossible” and thus estimate the change in their probabilities leading to Granger-type causal inference attribution statements.

We further extend this statistical framework to all quality daily GHCN station measurements and find that while many physically plausible outlier temperatures are impossible in the simple non-stationary GEV framework, they can be explained using our more complicated non-stationary Bayesian spatial statistical model embedded in a deep learning machinery.

 

How to cite: Wehner, M., Risser, M., Zhang, L., and Boos, W.: Statistically impossible temperatures., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2574, https://doi.org/10.5194/egusphere-egu24-2574, 2024.

EGU24-3153 | ECS | Posters on site | CL2.3

A systematic bias in future heatwave diagnostics throughout the seasonal cycle 

Maximilian Meindl, Lukas Brunner, and Aiko Voigt

Human-induced climate change is leading to a warming Earth, resulting in more frequent and intense temperature extremes. Daily temperature extremes can be defined following various approaches, with relative percentile-based thresholds being a common method. Here we explore spatio-temporal heatwaves across the seasonal cycle derived from daily temperature extremes, emphasizing the critical role of the extreme threshold chosen in their definition.

To investigate the sensitivity of heatwave characteristics to the extreme threshold definition, we focus on the approach utilizing a so-called moving threshold. This method involves a 31-day running window to increase the sample size for percentile calculations as well as an additional 31-year running window to account for the impact of global warming. We recognize that introducing a seasonal running window may introduce biases in threshold exceedances. To address this issue, Brunner and Voigt (2023) proposed a simple bias correction method, involving the removal of the mean seasonal cycle before percentile threshold calculation, which we also use here to explore effects on downstream impact metrics. 

We focus on the 99th percentile as threshold and show the potential for a significant bias in the extreme frequency, exceeding 50% in certain regions according to 5 selected CMIP6 models. Our findings further reveal that without bias correction this also leads to a substantial underestimation of derived heatwave properties, in particular area, duration, and magnitude. For the ACCESS-CM2 model, the difference in heatwave area can reach up to 40%, when comparing bias-corrected and not bias-corrected results for the 100 biggest events in the period 1960-1990.

Our results contribute to a better understanding of the implications of using a seasonally running window on heatwave characteristics, providing valuable insights for future climate projections. We emphasize the importance of adopting appropriate methods and bias correction techniques to enhance the accuracy of temperature extreme assessments in the context of ongoing climate change.

 

References:

Brunner and Voigt (2023): Revealing a systematic bias in percentile-based temperature extremes. EGU General Assembly 2024. EGU24-1722

How to cite: Meindl, M., Brunner, L., and Voigt, A.: A systematic bias in future heatwave diagnostics throughout the seasonal cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3153, https://doi.org/10.5194/egusphere-egu24-3153, 2024.

EGU24-3174 | Orals | CL2.3

Storylines of East Asian cold extremes in 2020/2021 under different warming climate 

Wenqin Zhuo, Antonio Sánchez-Benítez, Helge Goessling, Marylou Athanase, and Thomas Yung

Whether cold-air outbreak over mid-latitude in a warmer climate would become more or less extreme is a subject of debate, particularly due to uncertainty links between Arctic amplification and these cold extremes, which complicated by the atmosphere internal variability.  Here we employ an event-based storyline approach, which fixed the atmospheric circulation to the observed  through spectral nudging, to quantify thermodynamic effect on extreme cold events during the winter of 2020/2021 in East Asia under different warming scenarios. Notably, we detect the strongest warming, up to +10K, over Eastern Siberia in the +4K-warmer climate, which is related to warmer cold air mass originating from unfrozen sea ice over Siberia region. In contrast, in the southern China, due to the observed and expected increasing aerosol concentration, peaking by the mid-21st century and altering the radiative balances, a mild cooling is present from pre-industrial to present-day climates. The cooling in this region is likely to persist in +2K-warmer scenario but was not observed when up to the +4K warmer climate. Correspondingly, no prominent temperature variation is observed in the middle East Asia, with the warming extent largely mirroring the overall climate background.

How to cite: Zhuo, W., Sánchez-Benítez, A., Goessling, H., Athanase, M., and Yung, T.: Storylines of East Asian cold extremes in 2020/2021 under different warming climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3174, https://doi.org/10.5194/egusphere-egu24-3174, 2024.

A “once-in-a-millennium” super rainstorm battered Zhengzhou, central China, from 07/17/2021 to 07/22/2021 (named “7.20” Zhengzhou super rainstorm). It killed 398 people and caused billions of dollars in damage. ​A pressing question, however, is whether rainstorms of this intensity can be effectively documented by geological archives to understand better their historical variabilities beyond the scope of meteorological data. Here, four land snail shells (Cathaica fasciola) were collected from Zhengzhou in 2021, and weekly to daily resolved snail shell δ18O records from June to September of 2021 were obtained by gas-source mass spectrometry (GSMS) and secondary ion mass spectrometry (SIMS). The daily resolved records show a dramatic negative shift between 06/18/2021 and 09/18/2021, which has been attributed to is related to the “7.20” Zhengzhou super rainstorm. Moreover, the measured amplitude of the shell δ18O shift caused by the “7.20” Zhengzhou super rainstorm is consistent with the theoretical value estimated from the flux balance model and local instrumental data within the error range. Our results suggest that the ultra-high resolution δ18O of land snail shells have the potential to reconstruct local synoptic scale super rainstorm events quantitatively. And the proposed “best practice” of current work indicated that fossil snail shells in sedimentary strata can be valuable material for investigating the historical variability of local super rainstorms under different climate background conditions.

How to cite: Wang, G., Dong, J., and Yan, H.: Quantitative reconstruction of a single super rainstorm using daily resolved δ18O of land snail shell, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4973, https://doi.org/10.5194/egusphere-egu24-4973, 2024.

EGU24-6659 | Orals | CL2.3

Empirical storylines of climate change using clustering analysis 

Xavier Levine and Priscilla Mooney

Storylines are intended to provide concrete realizations of the climate response to global warming, to help anticipate the possible impacts of climate change on society and nature. Recent studies on climate change storylines have used a multivariate linear regression (MLR) framework to determine those climate realizations, for specific variables, regions and seasons (called target variables); this is achieved by leveraging known climatic interactions across a large number of model projections, which are represented by the covariability of the target variable with pre-determined climate indices (called predictor indices). Yet, a systematic methodology for selecting the best set of predictor indices for a specific target variable is lacking, with the set of predictors usually being chosen according to our current understanding of the most important climatic interactions. Furthermore, the storylines that emerge from it are tailored to explain changes in one specific variable, region and season (the target variable), and thus are unable to be generally applicable to a range of target variables.

Even if the MLR framework succeeds in generating an array of representative climate outcomes for specific cases, we hypothesize that alternative methodologies can be used to generate likely climate outcomes from model simulations while alleviating some of the limitations of the MLR framework. Here, we propose to use clustering analysis to provide possible climate realizations from model projections. Clustering ensures a comprehensive and efficient decomposition of the spread in climate projections found across model simulations, without the need of predefining predictors (both an advantage and inconvenience), but also can be applied to more than one target variable at a time. 

We present findings from various empirical clustering methods, using the three main categories of algorithm (e.g. distribution-, density-, and centroid-based) to produce our so-called empirical storylines. We focus on the Arctic region during the boreal summer season, comparing storylines obtained from each clustering method with findings from a set of “classic” storylines obtained using the MLR framework. We discuss the implications of our results for improving our understanding of the spread in climate projections, and conclude on the existence of a most likely cluster (storyline) by relating our climate change clusters with clusters for the present-day climate. 

How to cite: Levine, X. and Mooney, P.: Empirical storylines of climate change using clustering analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6659, https://doi.org/10.5194/egusphere-egu24-6659, 2024.

EGU24-6945 | ECS | Orals | CL2.3

Not as Rare as Expected: Assessing Singapore’s Unprecedented Droughts in a Changing Climate 

Xiao Peng, Biao Long, and Xiaogang He

There has been growing evidence suggesting a rising frequency and/or intensity of droughts in tropical regions in a warming climate. Singapore, a water-scarce city heavily reliant on water imports, faces heightened vulnerability to extreme drought episodes. Preparing for unprecedented droughts is thus pivotal for this tropical island city to safeguard a sustainable and resilient water supply. However, the accuracy of quantifying the probability and severity of unprecedented droughts, such as those with a 1000-year return period, is hindered by observations (e.g., in situ measurements, satellite data, etc.) with limited data length, typically spanning only about 50 years. Physics-based regional climate models offer a distinct advantage in simulating extreme droughts beyond historically available data. Yet, naïve Monte Carlo simulations for rare events becomes computationally infeasible at high spatiotemporal resolutions, a scale most relevant in urban drought risk mitigation. In this study, building upon the Giardina-Kurchan-Lecomte-Tailleur algorithm, we develop a computationally efficient framework to simulate Singapore’s unprecedented drought events. Our framework couples the Weather Research and Forecasting (WRF) model with a sequential importance sampling procedure, incorporating the ‘Darwinian pressure’ to favor trajectories conducive to extreme drought conditions. With just slightly over 100 trajectories, we can efficiently simulate very rare drought events (e.g., 1-in-10000-years and rarer) while maintaining their physical plausibility. The WRF model also enables detailed spatiotemporal dynamics of unprecedented droughts, allowing direct estimation of potential compounding extremes, such as concurrent droughts and heatwaves. Moreover, we quantify changes in the likelihood of plausible yet unprecedented droughts under various future climate change scenarios, such as Shared Socioeconomic Pathway 5-8.5 (SSP585), in comparison to the present climate. Our results reveal a robust increase in the chance of unprecedented droughts, emphasizing the importance of developing resilient water strategies for Singapore to prepare for such events in the near future.

How to cite: Peng, X., Long, B., and He, X.: Not as Rare as Expected: Assessing Singapore’s Unprecedented Droughts in a Changing Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6945, https://doi.org/10.5194/egusphere-egu24-6945, 2024.

EGU24-7744 | ECS | Orals | CL2.3 | Highlight

Storylines for heat-mortality extremes 

Samuel Lüthi, Erich Fischer, and Ana Vicedo-Cabrera

Recent heat extremes reached records far out of the observational temperature range. These extremes challenged the risk view of climate scientists on what could be physically possible within the current climate conditions. However, it is precisely such unprecedented events that pose a large risk to underprepared societies. To better anticipate and prepare for such potential extreme events, the climate risk community started producing storylines which are designed to draw potential and plausible worst-case scenarios without aiming to quantify their probability of occurrence.

The recent development of the ensemble boosting method allows investigating physically plausible extreme heatwaves by re-initializing a climate model with random round-off perturbed atmospheric initial conditions shortly before the onset of a great heat anomaly. This allows for creating storylines whilst ensuring physical consistency. However, so far these storylines were only used to estimate the pure physical climate extreme without the additional quantification of impacts on society.

In this study, we therefore aim to produce several storylines for potential worst-case heat-mortality scenarios. For that, we aim to combine ensemble boosted climate model output with methods from environmental epidemiology to quantify heat-mortality. Concretely, we model the empirical relationship between daily mean temperature and daily mortality counts by using quasi-Poisson regression time series analyses with distributed lag nonlinear models, which is a well-established approach in climate change epidemiology. We then combine these empirical temperature-mortality relationships with the bias-corrected extreme storylines that we developed by ensemble boosting a fully-coupled free-running climate model (CESM2).

The findings of this study have significant implications for societies, particularly in the context of public health policy development, to effectively respond to unprecedented but anticipatable heat extremes.

How to cite: Lüthi, S., Fischer, E., and Vicedo-Cabrera, A.: Storylines for heat-mortality extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7744, https://doi.org/10.5194/egusphere-egu24-7744, 2024.

EGU24-8388 | ECS | Orals | CL2.3

The Future of Hot-Dry Events in the World’s Breadbasket Regions 

Victoria Dietz, Johanna Baehr, and Leonard Borchert

We use a 50-member large ensemble of the CMIP6 version of the MPI-ESM1.2-LR model to examine the future of hot-dry compound events at 1.5 and 2°C of global warming. By targeting the largest maize production areas (breadbasket regions) and their corresponding growing seasons, we tailor our analysis to food production, indicating potential future threats to global food security. Our results suggest a notable shift in the extremes associated with maize harvest failure in the breadbaskets between 1.5 and 2°C of global warming, highlighting the value of mitigating climate change and the future need to adapt to climate challenges in the agricultural sector.

Our analysis shows a significant increase in the likelihood of these extremes during maize growing seasons across almost all examined regions and variables. In particular, the occurrence probability of heat events and hot-dry compounds at least doubles in most regions when the world warms from 1.5 to 2°C. Locally, cumulated heat excess increases everywhere, while the spatial extent of heat consistently expands across all regions in contrast to the relatively stable pattern we find for precipitation as we transition from one level of global warming to another. We additionally explore spatial compounding, where multiple breadbasket regions experience simultaneous extremes in the same growing season, exacerbating global food security challenges. Scenarios that were virtually impossible in the past, such as hot-dry events affecting at least three regions simultaneously, take on non-zero probabilities in a world that is 1.5 or 2°C warmer. The probabilities of simultaneous heat and hot-dry compounds in a 2°C warmer world significantly exceed those in a 1.5°C warmer world, to the extent that there is little to no overlap between the corresponding ensemble spreads.

How to cite: Dietz, V., Baehr, J., and Borchert, L.: The Future of Hot-Dry Events in the World’s Breadbasket Regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8388, https://doi.org/10.5194/egusphere-egu24-8388, 2024.

In 2015, Limin Jiao et al. used concentric circles and inverse S function curves to analyze the construction land density of 28 major cities in China and successfully divided the internal structure of urban areas. Based on this, this study takes  Beijing-Tianjin-Hebei core area (Beijing, Tianjin and Langfang) and  Shanghai metropolitan area (Yangtze River Delta region) as the research objects, analyze the changes in construction land structure and urban heat island effect from 2001 to 2020.
It is feasible to use the Anselin local Moran I tool of Arcgis to analyze urban centers based on population density (Yingcheng Lia; Xingjian Liu, 2018). We established a fishing net analysis, and the grid with HH significant clustering (high population density surrounded by those of similar high densities) can be regarded as the center of the city. Then, concentric circles with a diameter of 1KM are established based on these center points, and the proportion of construction land in each circle is extracted. And use the inverse S function (Formula 1) to fit the extraction results.
 (1)
The determination coefficient R2 of all fitting results is greater than 0.98, and the results are highly reliable. Then the fitted function is differentiated twice. The two extreme points correspond to the concentric radius of the inner city and the suburbs (R1, R2, and R1<R2) respectively. We found that the radius of the central city and peripheral urban areas of both metropolitan areas has expanded over the past 20 years, with Shanghai's peripheral cities expanding at a faster rate. In addition, the urban radius of Beijing-Tianjin-Hebei is about twice that of Shanghai.
In this study, the urban heat island effect is represented by the difference in surface temperature between suburban areas and Inner City. The results show that the urban heat island effect in the two regions has shown an increasing trend over 

How to cite: Zhang, X., Roca Cladera, J., and Arellano Ramos, B.: Research on urban heat island effect based on concentric circle division of urban structure - Take the Beijing-Tianjin-Hebei and Shanghai metropolitan areas as examples, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9680, https://doi.org/10.5194/egusphere-egu24-9680, 2024.

EGU24-9911 | ECS | Posters on site | CL2.3

Attribution of European Heatwaves to Global Warming Using Spectrally Nudged Storylines 

Dalena Leon, Frauke Feser, and Linda Van Garderen

This study employs Spectrally Nudged Storylines to attribute heatwaves to anthropogenic global warming. Utilizing high-resolution global (ECHAM) and regional (CCLM) climate models, we aim to discern the influence of anthropogenic climate change on the characteristics of European heatwaves observed in the last decade. Differently to the statistical approach that uses large ensembles/datasets to study large amount of similar events and attribute their occurrence to climate change, the storylines simulate a specific extreme event under different thermodynamical conditions by constraining the large scale dynamics of the system. Thus, directly attributing the change in characteristics of the extreme event to the changes in the thermodynamics, based on the prescribed sea surface temperature and greenhouse gases emission levels. In such way, three storylines are built: a Factual storyline that resembles the climate state as we know it, a Counter Factual storyline that is fixed to the past century representing a world without climate change, and a Plus 2°C storyline that shows how these extreme events change in a world where the global mean temperature is 2°C higher than in pre-industrial times. By the use of these three storylines, we can tell to what extent global warming has provoked heatwaves to be as extreme in a world as we know it, and what can we expect them to be in a warmer future climate.

How to cite: Leon, D., Feser, F., and Van Garderen, L.: Attribution of European Heatwaves to Global Warming Using Spectrally Nudged Storylines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9911, https://doi.org/10.5194/egusphere-egu24-9911, 2024.

EGU24-10006 | ECS | Orals | CL2.3

Impacts of regional grid refinement on climate extremes over the Arctic in storyline-based earth system model simulations. 

René R. Wijngaard, Willem Jan van de Berg, Adam R. Herrington, and Xavier Levine

Over the last few decades, the Arctic region has warmed up at a greater rate than elsewhere at the globe, partly resulting from the on-going loss of sea ice and snow over land. It is projected that the amplified warming of the surface will continue in the future, most likely altering the magnitude and frequency of temperature extremes, such as heat waves and cold spells. In addition, the intensity and frequency of extreme precipitation and droughts are projected to change, which may pose serious threats for the human infrastructure and livelihoods. To assess (future) climate extremes, Earth System Models (ESMs) with (regionally) refined resolution could be helpful, particularly in mountainous regions.

In this study, we use the variable-resolution Community Earth System Model version 2.2 (VR-CESM) to evaluate and assess present-day and future climate extremes, such as heat waves and heavy precipitation, over the Arctic. Applying a globally uniform 1-degree grid and a VR grid with regional grid refinements to 28 km over the Arctic and Antarctica, we run present-day (2005–2014) and future (2090–2099) simulations with interactive atmosphere and land surface models, and prescribed sea ice and surface temperatures. The simulations follow two storylines of Arctic climate change that represent a combination of strong/weak polar Arctic amplification and strong/weak SST warming in the Barents-Kara seas. We evaluate the ability of the VR grid to simulate climatic extremes by comparison with gridded outputs of the globally uniform 1-degree grid and the ERA5 reanalysis and assess future climate extremes by focussing on temperature and precipitation extremes. The initial outcomes generally show that for some temperature/precipitation extremes indices the VR grid performs better than the globally uniform 1-degree grid, while for other indices the globally uniform 1-degree grid performs better. Future projections suggest that warm temperature extremes will generally increase both in magnitude and frequency, whereas cold temperature extremes will decrease in magnitude, especially over regions dominated by large sea ice loss. Further, precipitation is projected to increase in intensity and volume. The outcomes of this study may contribute to an improved understanding on future climate extremes and its implications.

How to cite: Wijngaard, R. R., van de Berg, W. J., Herrington, A. R., and Levine, X.: Impacts of regional grid refinement on climate extremes over the Arctic in storyline-based earth system model simulations., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10006, https://doi.org/10.5194/egusphere-egu24-10006, 2024.

It is well established that internal variability arising spontaneously from the chaotic nature of the climate system can amplify or obscure anthropogenically-forced signals, especially at near-term and at regional scale in the extratropics. In this talk, we focus on Northern Europe (NEU) winter climate changes over the 2020-2040 period and propose a set of internal variability storylines (IVS) to tackle related uncertainties. IVS are built from the combined evolution of the North Atlantic Oscillation (NAO) and the Atlantic Meridional Overturning Circulation (AMOC) diagnosed as drivers of variability for temperature over NEU.

We first show, based on a large ensemble of historical-scenario simulations from CNRM-CM6-1, that, depending on the near-term [AMOC-NAO] doublet evolution, anthropogenically-forced changes can be either considerably amplified with much warmer-wetter mean conditions, almost doubled, or considerably masked with marginal warming and unchanged mean precipitation with respect to present day. We then provide evidence for the robustness of our results by using large-ensembles from several models which ultimately allows assessing the full range of uncertainties for near-term climate change.

We finally use the 2010 severe winter case as an illustrative example of the added-value in expressing climate change knowledge in a conditional form through IVS to plan at best climate-related risks and local adaptation strategies at near term. Reframing the uncertain climate outcomes into the physical science space through IVS grapples the complexity of regional situations; it is also informative to more efficiently communicate towards the general public as well as for climate literacy in general.

How to cite: Cassou, C., Line, A., and Msadek, R.: Assessment of climate change at near-term (2020-2040) over Northern Europe through internal variability storylines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11961, https://doi.org/10.5194/egusphere-egu24-11961, 2024.

EGU24-11971 | Posters on site | CL2.3

Insights and Reflections: The 'Exploring Unprecedented Extremes' Workshop 

Dominique Paquin, Dominic Matte, Jens H. Christensen, Martin Drew, and Alexandrine Bisaillon

Due to the various regions and contexts around the world with distinct climatic characteristics, climate hazards vary significantly in their nature, frequency, and impact, causing property damage, population distress, communication failures, environmental damage, and economic losses. Unfortunately, 2023 showcased extreme weather and climate events that have surpassed previous records. These include heatwaves, floods, wildfires, tornadoes. The occurrence of these extreme events poses a challenge to our comprehension of future climates, primarily due to their divergence from our conventional thought patterns or their status as out-of-sample scenarios. With ongoing climate warming, the potential for more severe events in the future is a concern. Insufficient preparation may result in breakdowns within specific sectors or even societal collapse. Effective preparation involves multiple factors, with the initial challenge lying in forming expectations - a task complicated by events that fall outside our usual anticipations, such as out-of-sample occurrences. 

 

In the face of those climate challenges, understanding and mitigating the impacts of unprecedented climate extremes has become a critical area of focus. To shed light on this challenge, a workshop titled "Exploring Unprecedented Extremes" was convened in November 2023. This event brought together experts from diverse fields to deliberate on innovative approaches to climate change adaptation and mitigation. Emphasizing co-creation and interdisciplinary collaboration, the workshop addressed key themes such as the integration of various sectors into climate change strategies, the complexities of decision-making under uncertainty, and the crucial role of transdisciplinary research in comprehensively understanding and effectively responding to climate extremes. This poster focuses on the key takeaways and strategic reflections that emerged following the workshop, capturing the essence of our collaborative discourse on climate challenges.

How to cite: Paquin, D., Matte, D., Christensen, J. H., Drew, M., and Bisaillon, A.: Insights and Reflections: The 'Exploring Unprecedented Extremes' Workshop, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11971, https://doi.org/10.5194/egusphere-egu24-11971, 2024.

EGU24-12519 | ECS | Orals | CL2.3

Storyline simulations suggest a northward expansion of European droughts in warmer climates. 

Antonio Sánchez Benítez, Monica Ionita, Marylou Athanase, Thomas Jung, Qiyun Ma, and Helge Goessling

Climate change is causing an increase in the frequency, intensity and persistence of heatwaves and droughts, as seen, for example, in Central Europe in recent years. These changes are expected to be even more severe in the future. Two factors contribute to these changes in extreme events: dynamic changes – changes in the likelihood of weather patterns  – and thermodynamic changes. While the former are uncertain in future climate projections, the latter are characterized by a high signal-to-noise ratio, as there is a robust and ubiquitous rise in land-surface temperatures.

To better understand and analyze both contributions, we employ the so-called "event-based storyline approach", which involves nudging our global CMIP6 coupled climate model (AWI-CM1) towards the observed large-scale free-troposphere winds using various climate background conditions and initial states. This enables us to simulate the same weather conditions, including jet streams and blockings, in different climates: preindustrial, present, and in 2 °C, 3 °C, and 4 ºC warmer worlds. This methodology provides an efficient way of making the consequences of climate change more understandable to experts and non-experts, as extreme events that are fresh in people's memory are simulated in different climates with moderate computational resources.

Our simulations successfully reproduce recent hot and dry extreme events, like the 2019 or 2022 European heatwaves and the record-breaking 2022 drought. Our experiments reveal an intensification of these extremes from preindustrial to present climates (attribution), mainly in southern Europe, with no major changes in Central and Northern Europe. However, we project that this exacerbation will expand northward in future warmer climates, leading to even more severe drought in Central Europe and the Mediterranean by the end of the century. Taking advantage of our methodology we explore the physical mechanisms helping to exacerbate these events in future warmer climates.

How to cite: Sánchez Benítez, A., Ionita, M., Athanase, M., Jung, T., Ma, Q., and Goessling, H.: Storyline simulations suggest a northward expansion of European droughts in warmer climates., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12519, https://doi.org/10.5194/egusphere-egu24-12519, 2024.

EGU24-12974 | ECS | Orals | CL2.3

On the key role of anthropogenic warming in triggering extreme convective events: the case of the destructive Mediterranean derecho in 2022 

Juan Jesús González-Alemán, Damian Insua-Costa, Eric Bazile, Sergi González-Herrero, Mario Marcello Miglietta, Pieter Groenemeijer, and Markus G. Donat

A derecho is a widespread, long-lived, straight-line windstorm that is associated with a fast-moving group of severe thunderstorms known as a mesoscale convective system.

During 18 August 2022, a highly intense and organized convective storm, classified as a derecho, developed over the western Mediterranean Sea affecting Corsica, northern Italy and Austria, with wind gusts up to 62 m/s and giant hail (~11 cm). There were 12 fatalities and 106 people injured. This event received much attention in the media for its extraordinary impact and the rareness over the Mediterranean Sea. The derecho developed over an extreme marine heatwave that persisted during the whole summer. Therefore, the hypothesis of a relationship between the extreme atmospheric event and the extreme marine heatwave rapidly arose, and thus, a possible link with anthropogenic climate change.

This convective event can be considered as extreme from the affected locations point of view (in terms of winds) but also is between one of the most powerful derechos ever recorded in the USA and Europe. Also, the event developed over an extreme marine heatwave that was mainly affecting the western Mediterranean Sea during summer 2022.

Here, by performing model simulations with both the NCAR Model for Prediction Across Scales and the Météo-France nonhydrostatic operational AROME model and using an storyline approach, we find a relationship between the marine heatwave, the actual anthropogenic climate change conditions, and the development of this extremely rare and severe convective event. We also find a future worrying increase in intensity, size and duration of such an event with future climate change conditions.

How to cite: González-Alemán, J. J., Insua-Costa, D., Bazile, E., González-Herrero, S., Miglietta, M. M., Groenemeijer, P., and Donat, M. G.: On the key role of anthropogenic warming in triggering extreme convective events: the case of the destructive Mediterranean derecho in 2022, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12974, https://doi.org/10.5194/egusphere-egu24-12974, 2024.

EGU24-15314 | ECS | Orals | CL2.3

Investigating typical patterns for co-occurring heatwaves 

Vera Melinda Galfi

The typicality of extreme weather and climate events denotes their property to exhibit similarities in spatial patterns, temporal evolution, and underlying physical processes, with this resemblance intensifying as events become more extreme. Recent findings highlight that highly intense heatwaves, defined as prolonged local temperature anomalies, are consistently associated with specific large-scale circulation patterns. This suggests that there is a typical way to realise very extreme local temperature anomalies. Here, I will explore typical ways for the emergence of extremely intense hemispheric anomalies, characterized by notably large zonal variations in air temperature or geopotential height. This investigation aims to shed light on preferred atmospheric configurations leading to the simultaneous occurrence of heatwaves on a hemispheric scale.

How to cite: Galfi, V. M.: Investigating typical patterns for co-occurring heatwaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15314, https://doi.org/10.5194/egusphere-egu24-15314, 2024.

EGU24-15334 | Orals | CL2.3

Changes in land-atmosphere coupling may amplify increases in very rare temperature extremes 

Douglas Maraun, Reinhard Schiemann, Albert Osso, and Martin Jury

Extreme heat events are becoming more severe. Attribution studies have demonstrated the effect of anthropogenic climate change on recent devastating events, including the heat waves in Canada in 2021, Northern India in 2022 and the Western Mediterranean in 2023. Such impactful events are very rare with return periods of 100 years and more even in present climate. Their rareness is in stark contrast to the typically considered return periods ranging from less than a year to maybe 20 years. This choice might often be inevitable because of practical limitations, mainly the length of observational and climate model records. But generalising from such analyses to extreme events in general tacitly assumes that very rare events respond to climate change in a similar way as the analysed moderate extreme events. Several studies investigating land-atmosphere feedbacks and atmospheric circulation changes indicate, however, that this assumtion may not be justified.

Here we use three single model initial condition large ensembles (SMILES) to assess differences between projected changes in moderate heat extremes (represented by 2-year return values of the hottest day in a year) and very rare extreme events (represented by corresponding 200-year return values). We analyse changes from 1990-2014 to 2075-2099 according to the SSP5-8.5 scenario.

We find large regions where projected changes in very extreme events are markedly different - both stronger or weaker - to those in moderate extreme events. Model uncertainty about these differences is very high though: all considered SMILES suggest that such regions exist, but they do not agree on the locations.  The underlying mechanisms, however, are robust across models: in regions of increasing soil moisture temperature coupling strength, changes in very rare events can be almost twice as high as those in moderate extremes. Vice versa, in regions of decreasing coupling strength, changes may be much weaker. These changes can to a large extent be traced back to changes in precipitation patterns, highlighting the role of atmospheric circulation changes.  

The corresponding patterns emerge already over shorter time horizons and are thus relevant for mid-century projections, low emission scenarios and event attribution studies. Robust inference about these differences is impossible based on individual model simulations, but requires the sample size of SMILES.  Not accounting for these changes could lead to a dramatic misrepresentation of future climate risks from heat events. Our findings therefore confirm the importance of studies specifically targeting very extreme events.

How to cite: Maraun, D., Schiemann, R., Osso, A., and Jury, M.: Changes in land-atmosphere coupling may amplify increases in very rare temperature extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15334, https://doi.org/10.5194/egusphere-egu24-15334, 2024.

EGU24-15505 | ECS | Posters on site | CL2.3

Evaluating the simulation of extreme events with the land surface model CLM5.0 over Europe for 2018-2022: comparison with in situ and remotely sensed data 

Arpita Bose, Christian Poppe Terán, Bibi Naz, Visakh Sivaprasad, Stefan Kollet, and Harrie-Jan Hendricks Franssen

Climate change is expected to amplify the frequency and intensity of extreme events in the future. Recently there was a series of summers with heat waves and droughts over central Europe from 2018 to 2022, but also severe flooding in 2021. These events had substantial effects on agriculture, water resources, and human lives. To monitor and assess the impacts of extreme events, in situ and remote sensing data for soil moisture, evapotranspiration and carbon fluxes are important. In this study we evaluate simulation results by the Community Land Model (CLM, version 5.0) over the EUROCORDEX domain for past extreme events between 2018 and 2022 and analyze to which degree the model is able to reproduce low soil moisture levels, and changes in evapotranspiration, leaf area index and carbon fluxes in the areas most affected by the extreme event, on the basis of a comparison with in situ (e.g., ICOS) and remotely sensed (e.g., SMAP, MODIS) data. Additionally, we will compare CLM5.0 results to other land surface models, such as ERA5-Land, GLDAS, GLEAM. Our model setup over EUROCORDEX is driven by atmospheric forcings from the ERA5 reanalysis. The soil texture information is obtained from FAO at 10 km resolution and the land use data is from LULC from NCAR mapped to plant/crop functional types. It was found that CLM5.0 overestimates soil moisture and exhibits a wet bias compared to SMAP during heat waves. In addition, the comparison of measured evapotranspiration with CLM5.0 shows that drought stress response is underestimated by the model. A systematic underestimation or overestimation of the impact of past extreme events on the land surface would point to model limitations which is important to resolve to gain confidence in the simulation of future extreme events under conditions of climate change.

How to cite: Bose, A., Poppe Terán, C., Naz, B., Sivaprasad, V., Kollet, S., and Hendricks Franssen, H.-J.: Evaluating the simulation of extreme events with the land surface model CLM5.0 over Europe for 2018-2022: comparison with in situ and remotely sensed data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15505, https://doi.org/10.5194/egusphere-egu24-15505, 2024.

EGU24-16575 | ECS | Posters on site | CL2.3

Enhanced surface temperature over India during 1980–2020 and future projections: causal links of the drivers and trends 

Rahul Kumar, Jayanarayanan Kuttippurath, Gopalakrishna Pillai Gopikrishnan, Pankaj Kumar, and Hamza Varikoden

The Earth’s surface temperatures have increased significantly since the beginning of industrialisation. The substantial emissions of greenhouse gases have played a role in global warming and the ongoing climate change, with projections indicating continued trends. This study explores the long-term surface temperature trends in India from 1980 to 2020, utilizing surface, satellite, and reanalysis data. Causal discovery is employed to assess the impact of geophysical drivers on temperature changes. Southern India exhibits the highest mean surface temperatures, while the Himalayas experience the lowest, aligning with solar radiation patterns. The causal discovery analysis identifies the varying influence of atmospheric processes, aerosols, and specific humidity on surface temperature. Positive temperature trends are observed during the pre-monsoon (0.1–0.3 °C dec−1) and post-monsoon (0.2–0.4 °C dec−1) seasons in northwest, northeast, and north-central India. Northeast India demonstrates substantial annual (0.22 ± 0.14 °C dec−1) and monsoon (0.24 ± 0.08 °C dec−1) warming. Post-monsoon trends are positive across India, with the western Himalaya (0.2–0.5 °C dec−1) and northeast India (0.1–0.4 °C dec−1) experiencing the highest values. Projections based on the Coupled Model Intercomparison Project 6 (CMIP6) indicate potential temperature increases of 1.1–5.1 °C by 2100 under the Shared Socioeconomic Pathways (SSP5)–8.5 scenario. The escalating temperature trend in India raises concerns, emphasizing the necessity for adaptation and mitigation measures to counteract the adverse impacts of accelerated warming and regional climate change.

How to cite: Kumar, R., Kuttippurath, J., Gopikrishnan, G. P., Kumar, P., and Varikoden, H.: Enhanced surface temperature over India during 1980–2020 and future projections: causal links of the drivers and trends, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16575, https://doi.org/10.5194/egusphere-egu24-16575, 2024.

EGU24-17486 | ECS | Orals | CL2.3

Hydro-economic assessment of biophysical drought impacts on agriculture 

Mansi Nagpal, Jasmin Heilemann, Bernd Klauer, Erik Gawel, and Christian Klassert

As climate changes globally and locally, the risk of temperature anomalies, heat waves and droughts have significantly increased. Studies have demonstrated that droughts exert adverse biophysical effects on crop production, posing an unprecedented threat to harvests and resulting in substantial economic losses in Europe. Assessing these biophysical drought impacts on agriculture is crucial for developing effective strategies for drought preparedness, mitigation, and adaptation. This paper contributes to this effort by presenting a framework to estimate economic costs associated with droughts that specifically captures the biophysical impact of climate change on crop output.

Existing analyses for drought damages in agriculture are developed for a specific drought event and primarily focus on the reduction in farmer’s income or crop yields in drought events. In these assessments, the biophysical impacts of droughts are not isolated and evaluated from their effects on other economic variables such as output prices, resulting in inaccurate damages. Additionally, lack of single universal definition of drought adds complexity to estimating the costs of droughts. This paper is aimed to contribute by focusing on agricultural droughts, which occurs when variability in soil moisture affects plant growth and development. We simulate this biophysical effect of drought on crop yields by applying a statistical crop yield model to data on soil moisture, temperature and perception. This approach helps isolate the direct impact of drought on agriculture from other changes in aggregate economic production (e.g. business conditions, commodity prices) and farmer management decisions (e.g. intermediate input use). The simulated biophysical yield effects are then quantified into monetary terms to estimate economic damages of droughts. We further look into the relationship of the economic damages and the intensity of droughts to determine drought thresholds that lead to increased economic losses.

The results provide bottom-up estimates of the economic damages of drought induced water deficiency in agriculture across Germany for the years 2016-2020. The spatio-temporal patterns of drought impacts can be useful for drought policy planning at local and national level. The economic costs estimation framework could be valuable in estimating farmer compensations and loss and damage of droughts. The results of the study can provide reliable estimates of the costs of climate-change-related extreme weather events, which may help inform macroeconomic and integrated impact assessment models of economic losses (and gains).

How to cite: Nagpal, M., Heilemann, J., Klauer, B., Gawel, E., and Klassert, C.: Hydro-economic assessment of biophysical drought impacts on agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17486, https://doi.org/10.5194/egusphere-egu24-17486, 2024.

EGU24-17759 | Orals | CL2.3 | Highlight

A daily ensemble of Past and Future Weather for rapid attribution and future perspectives 

Hylke de Vries, Geert Lenderink, Erik van Meijgaard, Bert van Ulft, and Wim de Rooy

Europe faced many extreme events in the year 2023; storms, heatwaves, intense precipitation, widespread flooding, to mention a few. Long-standing records were broken, and re-broken again. The events invariably received a lot of attention by the media and triggered many questions from journalists, eager to report about them. These questions are typically about the frequency or ‘extremeness’ of the event, whether or how already occurred climate change has impacted this frequency, and what the future perspectives are: Would a similar event in future or past climate have (had) a larger or smaller impact? 

It is a challenge for scientists to answer such (attribution) questions rapidly, i.e., before or on the day of the event, or in the immediate aftermath. Weather attribution teams like WWA (World Weather Attribution) now apply standardised procedures based on combining observations and climate modelling, to produce such analyses within weeks.

Here we discuss an approach that may augment the set of already existing tools and frameworks for rapid attribution analysis. The approach is based on regional downscaling in combination with pseudo global warming (PGW). Each day a small downscaled ensemble is created using as initial and boundary conditions the ECMWF analysis and forecasts. In addition to this ‘present-day’ ensemble, also a ‘past’ and ‘future’ ensemble are created using PGW. Due to the synchronicity of the time-evolution of the past, current and future ensembles, the signal-to-noise ratio is high, allowing an immediate estimate of how (thermodynamic) changes could have contributed to the event, and how a similar event in a future climate could look. Inherent limitation of PGW is that it cannot, or only in a limited way, address the frequency-change aspect. 

We illustrate the PGW-ensemble with a number of events that occurred during 2023 such as storm Hans (August), the December snowfall, and the unprecedented yearly rainfall amount in the Netherlands.

How to cite: de Vries, H., Lenderink, G., van Meijgaard, E., van Ulft, B., and de Rooy, W.: A daily ensemble of Past and Future Weather for rapid attribution and future perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17759, https://doi.org/10.5194/egusphere-egu24-17759, 2024.

EGU24-17826 | ECS | Orals | CL2.3

Where and when will the next precipitation record be broken?  

Iris de Vries, Erich Fischer, Sebastian Sippel, and Reto Knutti

Not only will climate change lead to more intense extreme precipitation, it will also lead to more frequent record-breaking daily rainfall. Given the tendency of society to design critical infrastructure and emergency plans based on (statistics derived from) historical observations, an increasing occurrence of record-breaking events – events that are more intense than ever recorded – poses a high risk for loss and damage. 

A major challenge in the projection of very extreme events is their inherent rarity. This problem is even more prominent for record events: by definition these events are not present in sample data because they have not yet occurred. An additional difficulty, which is particularly challenging for precipitation, is the high internal variability in and local character of very rare extremes. This implies that, by chance, an observed data sample of finite size might contain few extremes, whereas the true probability and intensity of extremes given by the (unknown) underlying distribution is much higher. In practice, this can lead to “surprise extremes”. 

With the help of extreme value theory, we approach this problem from two angles, using multi-model CMIP6 data and two different ground-station based observational datasets. Firstly we assess, for all observed land grid cells, where the last observed precipitation record is “extraordinarily long ago” given the theoretical record breaking rate prescribed by historical and future climate according to the CMIP6 models. Secondly, we assess where the last observed record value is “extraordinarily low in intensity” given the historical and future modelled distribution of extreme precipitation. Combining these two approaches, we highlight regions on earth where the probability of record precipitation events in the near future is high.

We find that grid points where the last observed precipitation record is extraordinarily long ago are ubiquitous and scattered globally. When combining this with the observed record intensity, the number of grid points that stand out for their high near-term record probability decreases drastically. We find a somewhat higher density of high-probability grid points in Australia and southern South America, but the pattern is not very clear. Nonetheless, every world region contains a number of grid points where the current observed record is both extraordinarily long ago and low in intensity, and where the near-term probability of a new precipitation record is thus high.

How to cite: de Vries, I., Fischer, E., Sippel, S., and Knutti, R.: Where and when will the next precipitation record be broken? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17826, https://doi.org/10.5194/egusphere-egu24-17826, 2024.

EGU24-17905 | Posters on site | CL2.3

Climate projections over the Eastern Mediterranean Black Sea region using a pseudo global warming (PGW) approach.  

Patrick Ludwig, Soner C. Bagcaci, Ismail Yücel, M. Tugrul Yilmaz, and Omer L. Sen

This study presents high-resolution (4 km) simulations of the Weather Research and Forecasting (WRF) model using the pseudo-global-warming (PGW) approach. The aim is to investigate seasonal climatic changes in the Eastern Mediterranean Black Sea (EMBS) region between the periods of 2071-2100 and 1985-2014. The climate change signals retrieved from the CMIP6 GCMs under the highest emission scenario (SSP5-8.5) were added to ERA5 data to account for future climate perturbation. During the baseline period  (1995-2014), the dynamically downscaled ERA5 (not perturbed) and ground observations yielded daily near-surface temperature reach correlations of around 0.98 and daily precipitation correlations ranging from 0.60 to 0.76. The WRF simulations for the future climate accurately represent the low-level anticyclonic circulation over the EMBS caused by anomalous ridge development over southern Italy in winter (DJF) and the decrease in vertical pressure velocity and resulting low-level circulation due to heat-low development over the Eastern Mediterranean in summer (JJA) as represented by the GCMs. Likewise, the wetting and drying patterns in the regional WRF simulations match those in the GCM ensemble over the subregions of the EMBS in winter. However, abnormal precipitation increases occur in the WRF simulations over the Caucasus and nearby regions, which is a new insight as this pattern does not exist in the GCM ensemble. This abnormality is likely caused by the higher-than-expected sea-surface temperature (SST) of the Caspian Sea and considering high-resolution simulations over the complex topography of that region.

How to cite: Ludwig, P., Bagcaci, S. C., Yücel, I., Yilmaz, M. T., and Sen, O. L.: Climate projections over the Eastern Mediterranean Black Sea region using a pseudo global warming (PGW) approach. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17905, https://doi.org/10.5194/egusphere-egu24-17905, 2024.

EGU24-18632 | ECS | Posters on site | CL2.3

A climatological look on the intersection of synoptic conditions and extreme weather-induced potential impact events in the cross-border region of Austria and Italy 

Sebastian Lehner, Katharina Enigl, Alice Crespi, Massimiliano Pittore, and Klaus Haslinger
Extreme weather events and associated natural hazards pose a significant global threat to all levels of society. It is scientific consensus that climate change contributes to an increasing frequency and intensity of these events. One of the key challenges for decision-makers in the field of civil protection is to deal with the changing landscape of weather-induced impact events, that are driven by climate change. Hence, assessing the current and changing conditions across spatiotemporal scales for extreme weather events under a changing climate is essential.

This study explores the potential of utilizing weather circulation type classification through its correlation with observed weather-induced extreme events and their potential impacts on the local-scale. Thereby, high-impact weather types can be determined as a relevant background field, serving as a measure about the potential of severe weather hazards. We employ ERA5 reanalysis data as baseline meteorological input data to derive long-term and robust time series of weather types from mean sea level pressure that are relevant for the cross-border region of Austria and Italy. The classification scheme 'Gross-Wetter-Typen' (GWT) with 18 classes was used to assign each day a prevailing weather type class. The overlap between derived classes is further investigated by means of unsupervised clustering techniques, to evaluate clusters of groups across all GWT classes. Additional meteorological fields (e.g. equivalent potential temperature, geopotential height, precipitable water, ...) are validated on top of the GWT classes for further characterisation of extreme weather events. Days exhibiting extreme weather-induced potential impact events are derived via percentile methods applied to precipitation data from observational gridded datasets (Enigl et al., 2024, EGU24-10058). Finally, we extend our analysis with an evaluation of potential changes by applying found relationships to state-of-the-art climate model data from the Coupled Model Intercomparison Project 6 (CMIP6) to investigate the changing landscape of potential weather extremes.

Our findings indicate that a specific subset of large-scale weather circulation patterns acts as a crucial precursor to high-impact weather extremes. Furthermore, considering the climate change scenario SSP3-7.0, the frequency and associated precipitation totals linked to these weather patterns exhibit an increase. This suggests a potential rise in both the frequency and intensity of extreme weather events and their corresponding impacts if emissions continue to increase.

How to cite: Lehner, S., Enigl, K., Crespi, A., Pittore, M., and Haslinger, K.: A climatological look on the intersection of synoptic conditions and extreme weather-induced potential impact events in the cross-border region of Austria and Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18632, https://doi.org/10.5194/egusphere-egu24-18632, 2024.

EGU24-19572 | ECS | Posters on site | CL2.3

Heatwaves and compound extremes under atmospheric blocking 

Magdalena Mittermeier, Laura Suarez-Gutierrez, Yixuan Guo, and Erich Fischer

In early September 2023, Europe was under the influence of a pronounced atmospheric block in the shape of the Greek letter “omega”. Such an omega-blocking is characterized by a persistent anticyclone in the center flanked by two low pressure systems to the south in the west and east. The omega-block interrupts the mean westerly flow and leads to prolonged persistent conditions lasting for at least five days. The core of the omega-blocking in September 2023 was located over Central Europe and Southern Scandinavia, which experienced a heatwave in the first week of September 2023. On the other hand, the regions positioned at the eastern flanks of the omega-blocking (Greece, Bulgaria, Libya) were hit by heavy precipitation resulting in major floods.

While omega-blocking situations can result in severe spatially compounding extremes, there is still a research gap on current and future dynamics of (omega) blocking. Current generations of climate models underestimate blocking frequencies – especially over Europe. This makes it difficult to derive robust statistics about blocking related compound extremes under current and future climate, because the observational record only offers a limited number of event examples and atmospheric blocking underlies a high natural climate variability.

We employ the novel method of ensemble boosting to explicitly boost blocking situations in the Community Earth System Model 2 (CESM2) large ensemble. With this model re-initialization method initial conditions 10 to 30 days before the event are slightly perturbed, which results in hundreds of coherent physical event trajectories (event storylines). This allows to study following research questions: Is the CESM2 model capable of reproducing an omega blocking event with spatially compounding extremes in the magnitude of the September 2023 event? Could the September 2023 event have been even more devastating by chance? Have we experienced anything close to the most intense compound omega-blocking event possible under current climatic conditions? In our poster, we present our research concept as well as preliminary results.

How to cite: Mittermeier, M., Suarez-Gutierrez, L., Guo, Y., and Fischer, E.: Heatwaves and compound extremes under atmospheric blocking, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19572, https://doi.org/10.5194/egusphere-egu24-19572, 2024.

EGU24-19808 | Posters on site | CL2.3 | Highlight

Unveiling and communicating climate change by near-real-time attribution and projection of the current weather based on nudged storyline simulations 

Helge Goessling, Marylou Athanase, Antonio Sánchez-Benítez, Eva Monfort, and Thomas Jung

Attribution and projection of climate change by event-based storylines has recently been established as a powerful tool that complements the well-established probabilistic approach. Event-based storylines which nudge the observed atmospheric winds in climate models have been particularly helpful in isolating the thermodynamic component of climate change. The approach is characterised by a high signal-to-noise ratio because differences due to internal variability are effectively removed by imposing (via nudging) the same large-scale atmospheric circulation in different climates. Nudging-based storylines make it possible to unveil the “climate change signal of the day” for the actually observed weather, be it an extreme or an every-day event, which comes with a great potential for climate change communication. Here we take the approach one step further and present our efforts to provide nudging-based climate storylines in near-real-time. This includes not only the automated extension of storyline simulations on a daily basis, but also the dissemination via an online tool that allows both scientific and non-scientific users to explore the “climate change signal of the day” for a number of relevant variables in useful and intuitive ways. While the omission of possible dynamical changes and the reliance on a single model need to be communicated as clear limitations, we envisage that tools like our prototype may become an important piece of the future dissemination portfolio of climate change information.

How to cite: Goessling, H., Athanase, M., Sánchez-Benítez, A., Monfort, E., and Jung, T.: Unveiling and communicating climate change by near-real-time attribution and projection of the current weather based on nudged storyline simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19808, https://doi.org/10.5194/egusphere-egu24-19808, 2024.

EGU24-175 | ECS | Orals | CL2.4

Why do oceanic nonlinearities play a weak role in Extreme El Niño events? 

Fangyu Liu, Jérôme Vialard, Alexey V. Fedorov, Christian Éthé, Renaud Person, and Matthieu Lengaigne

Extreme El Niño events exhibit outsized impacts worldwide and considerably enhance the El Niño Southern Oscillation (ENSO) warm/cold phase asymmetries. While many mechanisms were proposed, no consensus has been reached and the relative role of atmospheric and oceanic processes remains to be illustrated. Here we quantitatively assess the contribution of oceanic nonlinearities through a state-of-the-art oceanic general circulation model, which realistically simulates extreme El Niño related characteristics and the oceanic nonlinear processes responsible for ENSO skewness. An effective way is developed to isolate sea surface temperature (SST) nonlinear response based on paired experiments forced with opposite wind stress anomalies. We demonstrate that the overall oceanic nonlinearities play a marginal role on extreme El Niño amplitude, which largely arises from the compensation between positive contributors from tropical instability waves (TIWs) and nonlinear dynamic heating (NDH) and negative contributors from subsurface processes and air-sea fluxes. The physical processes keep robust when using the other mixing scheme or mixed layer option for the heat budget. Our findings quantitively reveal the subtle contribution of oceanic nonlinearities, yielding strong evidence for the paramount role of atmospheric nonlinearities in shaping extreme El Niño events.

How to cite: Liu, F., Vialard, J., V. Fedorov, A., Éthé, C., Person, R., and Lengaigne, M.: Why do oceanic nonlinearities play a weak role in Extreme El Niño events?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-175, https://doi.org/10.5194/egusphere-egu24-175, 2024.

EGU24-626 | ECS | Posters on site | CL2.4

Dynamical evolution of ENSO in a warming background: A review of recent trends & future projections 

Sreevathsa Golla, Joël Hirschi, Jennifer Mecking, Adam Blaker, Stephen Kelly, and Robert Marsh

The wide-spread implications of El Niño–Southern Oscillation (ENSO) on global and regional climate necessitates a better understanding of how the underlying interannual dynamics have changed over recent years. Year-to-year changes in ENSO impact terrestrial and marine habitats, water availability, food security and social stability (Santoso et al., 2017). With abundant evidence of a warming climate, it is imperative to understand how a large-scale climatic oscillation such as ENSO is evolving and influencing changes in large-scale atmospheric circulation patterns (Alizadeh et al., 2022; Cai et al., 2021). Furthermore, quantifying the influence of the ocean on changes in this climatic pattern is an interesting and important question to answer. Evaluating the ability of models to appropriately represent the underlying physics and dynamical changes impacting the spatiotemporal extent and the intensity of ENSO is crucial to understanding ocean-climate teleconnections and changes in climatic extremes. In this study, we review and evaluate the representation of ENSO in several high-resolution CMIP6 and HighResMIP models and forced ocean-only simulations focusing on the ability of current state-of-the-art models to represent central equatorial pacific warming and cooling. This evaluation involves looking at the development and propagation of warm temperature anomalies on surface and sub-surface levels in the equatorial Pacific and understanding the differences in simulating surface heat budget and exchange with the overlying atmosphere and the deeper ocean. Surface and sub-surface (up to 200m depth) temperature anomalies in the Niño 3.4 region were calculated from modelled data and were then compared with anomalies from observational and reanalysis temperature datasets (like EN4, ORAS5). We find good agreement in the timing and vertical structure of surface/sub-surface temperature anomalies in the forced model simulations, particularly during strong ENSO years. Moreover, the genesis of sub-surface anomalies and their further propagation to the surface was well simulated in the forced simulations. The vertical coherence of temperature anomalies was relatively more pronounced in forced ocean-only simulations than in coupled high-resolution model runs. Furthermore, we comment on the shortcomings and suggest potential improvements that can be made in the models that could improve the model’s ability to capture ENSO strength and variability.

How to cite: Golla, S., Hirschi, J., Mecking, J., Blaker, A., Kelly, S., and Marsh, R.: Dynamical evolution of ENSO in a warming background: A review of recent trends & future projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-626, https://doi.org/10.5194/egusphere-egu24-626, 2024.

EGU24-696 | ECS | Orals | CL2.4

Tropical SST Impacts on the Subtropical Atmospheric Circulation and Regional Precipitation 

Weiteng Qiu, Mat Collins, Adam Scaife, and Agus Santoso

The tropical Pacific Ocean hosts the Earth’s most prominent year-to-year climate fluctuation, the El Niño-Southern Oscillation (ENSO), which exerts strong impacts on remote regions of the globe through atmospheric teleconnection. In this study, we use reanalysis data and Coupled Model Intercomparison Project Phase 6 (CMIP6) historical simulations to investigate the relationship between tropical and subtropical atmospheric circulation, and the tropical SST patterns and regional precipitation.   

We find dynamical relationships between subtropical high intensity, the Hadley and Ferrel Circulation intensity, and the Eady Growth Rate from the reanalysis. A poleward shift of the maximum in Eady Growth Rate is associated with a strengthening of the descending branches of the Ferrel and Hadley Cells, with subtropical troposphere adiabatic warming and an increased intensity and poleward movement of the subtropical highs. Shifts in the poleward Eady Growth Rate are dominated by changes in vertical wind shear which, in turn, are in thermal wind balance with variations and trends in temperature. The mechanism for the intensification of the subtropical highs involves feedbacks from high-frequency transient eddies. Strong North Pacific and South Pacific Subtropical highs are associated with La-Niña conditions. We also show that the mechanisms for interannual variations are similar to those for trends in the highs.

We further analysed the performance of the coupled models in reproducing the trends (1979-2014) of the tropical zonal wind and regional precipitation. The CMIP6 historical simulations do not capture the intensification of trade winds within the Niño 4 region, and they also fail to reproduce the statistically significant precipitation trends over the Southern North America and the Amazon. However, a linear adjustment, based on ENSO teleconnections, can be applied to the coupled models to make the precipitation trends much closer to observations. The relationship between SST patterns and precipitation trends are confirmed by looking at atmosphere-only simulations. This study provides further evidence of the importance of reconciling observed and modelled SST patterns in the tropical Pacific.

How to cite: Qiu, W., Collins, M., Scaife, A., and Santoso, A.: Tropical SST Impacts on the Subtropical Atmospheric Circulation and Regional Precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-696, https://doi.org/10.5194/egusphere-egu24-696, 2024.

EGU24-1547 | ECS | Orals | CL2.4

Variable-resolution global atmospheric models are sensitive to driving SST in ENSO/IOD-Australian rainfall teleconnections 

Ying Lung Liu, Lisa Alexander, Jason Evans, and Marcus Thatcher

We have investigated the sensitivity of a global climate model to driving sea surface temperatures (SST) in simulating Australian rainfall characteristics, including the El Niño-Southern Oscillation (ENSO)- and Indian Ocean Dipole (IOD)-related rainfall variability. We employed the Conformal Cubic Atmospheric Model (CCAM), a global atmospheric model characterized by variable resolution, CCAM was forced by two SST datasets with different spatiotemporal resolutions: the 0.25° daily Optimum Interpolation Sea Surface Temperature (CCAM_OISST) version 2.1 and the 2° monthly Extended Reconstruction SSTs Version 5 (CCAM_ERSST5). A benchmarking framework was employed to appraise model performance, revealing strong agreement between the simulations and the Australian Gridded Climate Data (AGCD) in climatological rainfall spatial patterns, seasonality, and annual trends. It is noted that both simulations tend to overestimate rainfall amount, with CCAM_OISST exhibiting a larger bias.

Moreover, CCAM's performance in capturing ENSO and IOD correlations with rainfall was assessed during Austral spring (SON) using a novel hit rate metric. The findings underscore that only CCAM_OISST effectively reproduces observed SON ENSO- and IOD-rainfall correlations, achieving hit rates of 86.6% and 87.5%, respectively, in contrast to 52.7% and 41.8% for CCAM_ERSST5. Noteworthy disparities in sea surface temperatures were observed along the Australian coastline between OISST and ERSST5 (the so-called “Coastal Effect”). These disparities may be attributed to spatial interpolation errors arising from the differences in resolution between the model and driving SST. An additional experiment within CCAM, masking OISST with ERSST within a 5° proximity to the Australian continent, underscores the pronounced impact of the “Coastal Effect” on IOD-Australian rainfall simulations. Conversely, its influence on ENSO-Australian rainfall was constrained. Therefore, realistic local SSTs are important if model simulations are to reproduce realistic IOD-rainfall responses over Australia. Additionally, even though an SST product with a longer time span is preferred in simulating IOD-related variability, circumspection is warranted in the analysis of the impact of IOD on Australian rainfall when utilizing climate model output with a substantial discrepancy in spatial resolutions between the model and the driving SST. After showing CCAM’s ability to simulate ENSO- and IOD-rainfall, our future research will involve pacemaker experiments to isolate remaining climate modes and investigate their independent impact on Australian rainfall.

How to cite: Liu, Y. L., Alexander, L., Evans, J., and Thatcher, M.: Variable-resolution global atmospheric models are sensitive to driving SST in ENSO/IOD-Australian rainfall teleconnections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1547, https://doi.org/10.5194/egusphere-egu24-1547, 2024.

EGU24-1749 | ECS | Orals | CL2.4

Seasonality of Feedback Mechanisms Involved in Pacific Coastal Niño Events 

Daniel Rudloff, Sebastian Wahl, and Joke Lübbecke

The 2017 Pacific Coastal Niño Event was the strongest of its type. It caused torrential rainfall and devastating flooding in Peru and Ecuador and thus rapidly caught the attention of the scientific community. Multiple studies have been conducted focusing on the causes and consequences of this event. While the strong connection between SST anomalies and local rainfall, especially during boreal spring, is well established, the causes of the extreme warming are still a subject of discussion. In this study, we focus on the seasonality of the effectiveness of mechanisms and feedbacks involved in coastal Niño Events, utilising reanalysis products and historical model simulations from the Flexible Ocean and Climate Infrastructure (FOCI).

The 2017 event stands out due to its strength and timing as it occurred earlier in the year than most other events. We find that the atmospheric conditions during this time of year are very different due to the presence of atmospheric convection which modulates the SST-cloud feedback. Further, the event coincided with the season of strongest wind-driven upwelling. This combination enables a different forcing of a short but strong event. Additional model sensitivity experiments are performed for a better understanding of underlying mechanisms. We show how the same local wind stress forcing acts differently in different seasons, with its strongest impact during the months of strongest entrainment. Events forced by local heat fluxes and wind stress forcing only do not show any subsurface warming, which is found to be the main reason for their rapid decay. Even though the atmospheric response to a coastal warming varies seasonally, without any subsurface forcing, e.g., the events cannot be sustained through atmospheric feedbacks.

How to cite: Rudloff, D., Wahl, S., and Lübbecke, J.: Seasonality of Feedback Mechanisms Involved in Pacific Coastal Niño Events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1749, https://doi.org/10.5194/egusphere-egu24-1749, 2024.

EGU24-2133 | Orals | CL2.4

The El Niño Southern Oscillation (ENSO) recharge oscillator conceptual model : past achievements, future prospects. 

Jérôme Vialard and the CLIVAR ENSO conceptual model Working Group

The Recharge Oscillator (RO) is a simple mathematical model of the El Niño Southern Oscillation (ENSO). It is based on two ordinary differential equations that describe the evolution of eastern Pacific sea surface temperature and western Pacific oceanic heat content. These equations are based on physical principles that operate in nature: (i) the air-sea interaction loop known as the Bjerknes feedback, (ii) a delayed negative feedback arising from the slow oceanic response to near-equatorial winds, (iii) state-dependent stochastic forcing from intraseasonal wind variations known as Westerly Wind Events, and (iv) nonlinearities such as those related to deep atmospheric convection and oceanic advection. These elements can be combined in different levels of RO complexity. The RO reproduces the ENSO key properties in observations and climate models: its amplitude, dominant timescale, seasonality, warm/cold phases asymmetries, and the seasonal predictability decrease known as the “spring barrier”. We then discuss the RO in view of timely research questions. First, the RO can be extended to account for pattern ENSO diversity (with events that either peak in the central or eastern Pacific). Second, the core RO hypothesis that ENSO is governed by tropical Pacific dynamics is discussed under the perspective of research suggesting an influence from other basins. Finally, we discuss the RO relevance for studying ENSO response to climate change, and underline that accounting for diversity and better linking the RO parameters to the long term mean state are important research avenues. We end by proposing a list of ten important RO-based research problems.

How to cite: Vialard, J. and the CLIVAR ENSO conceptual model Working Group: The El Niño Southern Oscillation (ENSO) recharge oscillator conceptual model : past achievements, future prospects., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2133, https://doi.org/10.5194/egusphere-egu24-2133, 2024.

EGU24-2166 | Orals | CL2.4

Mechanisms of Tropical Pacific Decadal Variability 

Antonietta Capotondi and the CLIVAR Tropical Pacific Decadal Variability Working Group

Naturally-occurring variability in the Tropical Pacific at timescales in the 7-70 years range, defined here as Tropical Pacific Decadal Variability (TPDV), modulates ENSO characteristics and its global impacts, and is linked to the rate of change of the globally-averaged surface temperature. Thus, understanding TPDV is integral to robustly separate the forced climate response from internally-generated climate variability and thereby produce reliable projections of the tropical Pacific and global climate. Several oceanic mechanisms have been proposed to explain TPDV, including off-equatorial Rossby wave activity, propagation of spiciness anomalies from the subtropical to the tropical regions, and changes in the strength of the shallow upper-ocean overturning circulations, known as “Subtropical Cells”. However, uncertainties remain on the relative importance of these oceanic mechanisms. Another critical source of uncertainty concerns the nature and origin of the atmospheric forcing of those oceanic processes. Anomalous wind forcing could arise as a response to tropical Pacific sea surface temperature (SST) anomalies, be induced by Pacific extra-tropical influences or result from tropical basin interactions. This presentation critically reviews the nature and relative importance of the oceanic and atmospheric processes driving TPDV. Although uncertain, the tropical oceanic adjustment through Rossby wave activity is likely a dominant source of variability at decadal timescales. A deeper understanding of the origin of TPDV-related winds is a key priority for future research.

How to cite: Capotondi, A. and the CLIVAR Tropical Pacific Decadal Variability Working Group: Mechanisms of Tropical Pacific Decadal Variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2166, https://doi.org/10.5194/egusphere-egu24-2166, 2024.

EGU24-2466 | ECS | Posters on site | CL2.4

Asymmetric Influences of ENSO Phases on the Predictability of North Pacific Sea Surface Temperature 

Zhaolu Hou, Jianping Li, and Yina Diao

The North Pacific sea surface temperature (SST) exerts profound climatic influence. El Niño-Southern Oscillation (ENSO) significantly impacts North Pacific SST, yet the influence from ENSO’s distinct phases on SST predictability remains unclear. Overcoming model limitations, this study assesses SST predictability under diverse ENSO phases using reanalysis. Quantifying predictability limits (PL), results unveil asymmetry: El Niño PL at 5.5 months, La Niña at 8.4 months, and Neutral at 5.9 months. This asymmetry mirrors contemporary multimodal prediction skills. Error growth dynamics reveal La Niña's robust signal strength with slow error growth rate, contrasting El Niño's weaker signal and faster error growth. Neutral exhibits intermediate signal strength and elevated error growth. Physically, predictability signal strength aligns with SST variability, whereas error growth rate correlates with atmospheric-ocean heating anomalies. La Niña, inducing positive heating anomalies, minimizes atmospheric noise impact, resulting in lower error growth. The results are beneficial for improving North Pacific SST predictions.

How to cite: Hou, Z., Li, J., and Diao, Y.: Asymmetric Influences of ENSO Phases on the Predictability of North Pacific Sea Surface Temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2466, https://doi.org/10.5194/egusphere-egu24-2466, 2024.

EGU24-2993 | Posters on site | CL2.4

El Niño Southern Oscillation and Tropical Basin Interaction in Idealized Worlds 

Dietmar Dommenget and David Hutchinson

In this study we discuss a set of fully coupled general circulation model simulations with idealised geometries of the tropical ocean basins and land with a focus on important characteristics of El Niño Southern Oscillation (ENSO) type of variability and tropical basin interaction. In a series of 15 simulations we first vary the zonal width of a single tropical ocean basin from 50o to 360o, while the rest of the tropical zone is set as land. Further we discuss different simplified configurations of two or three tropical ocean basins. The results show remarkable changes in ENSO characteristics as function of basin width and due to the interaction with other basins that challenge our current understanding of ENSO dynamics. A single basin ENSO has an optimal basin width of about 150o at which ENSO preferred period is the longest, the wind stress feedback is the strongest and variability is stronger than in all other basin widths, expect for the 350o basin. Tropical basin interactions substantially affect ENSO strength, periodicity, feedbacks, non-linearity, spatial scale and pattern. In experiments with two or three identical ocean basins we find highly synchronized ENSO modes that are identical between basins and far more energetic and oscillatory then the single basin modes. The results suggest that tropical basin interaction is an essential part of ENSO. The framework of these experiments can help to better understand the atmospheric dynamics of ENSO and should help to formulate an ENSO theory that incorporates tropical basin interactions as a core element.

How to cite: Dommenget, D. and Hutchinson, D.: El Niño Southern Oscillation and Tropical Basin Interaction in Idealized Worlds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2993, https://doi.org/10.5194/egusphere-egu24-2993, 2024.

This study investigates the delayed influence of the Indian Ocean dipole (IOD),  isolated and combined with ENSO, on the early winter North Atlantic-European (NAE) circulation.  Results reveal that a positive IOD induces a strong response in the NAE region during December, leading to a positive North Atlantic Oscillation (NAO)-like pattern. This circulation response also induces a north-south precipitation dipole and a positive temperature anomaly over Europe. The underlying physical mechanism involves a rainfall dipole response to the IOD in the Indian Ocean, persisting into early winter, which triggers a perturbation in the zonal wind within the subtropical South Asian jet (SAJET) region. This initiates a wave-train that propagates northeastward into the North Atlantic. Additionally, a positive IOD enhances transient eddy activity in the European region. Transient eddy forcing provides strong positive feedback to the NAO-like anomaly. While the ECMWF-SEAS5 seasonal hindcast system reproduces the sign of the response, its magnitude is considerably weaker. The possible reasons for this weak response are investigated. The model can reproduce the delayed rainfall dipole response to the IOD, however, the structure of the response shows some differences with the re-analysis. The zonal wind perturbation in ECMWF-SEAS5 in the SAJET region is only about half of the re-analysis magnitude. Moreover, the wave propagation into the stratosphere, as estimated by the 100h𝑃𝑎 eddy heat fluxes, plays a minor role in the re-analysis and the model.

How to cite: Kucharski, F., Raganato, A., and Abid, M. A.: The combined  impact of Indian Ocean dipole and ENSO on the North Atlantic-European circulation during early boreal winter in re-analysis and in the ECMWF-SEAS5 hindcast , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3110, https://doi.org/10.5194/egusphere-egu24-3110, 2024.

EGU24-3728 | Orals | CL2.4 | Highlight

Super El Niño: A product of three-ocean interactions  

Chunzai Wang, Jiazhen Wang, and Hanjie Fan

El Niño, the largest climate phenomenon on Earth, profoundly influences global climate, weather, ecosystems, and human societies. Super (or extreme) El Niño, in particular, has a significant impact on climate and extreme weather events, but its formation mechanism remains unknown. This presentation utilizes observations, climate model outputs, and coupled model experiments to demonstrate that interactions among the tropical Pacific, Indian, and Atlantic Oceans contribute to the development of super El Niño. The early onset of El Niño imparts sufficient strength in the summer and fall to trigger the Atlantic Niña and Indian Ocean dipole. Subsequently, the Atlantic Niña and Indian Ocean dipole alternately generate additional westerly wind anomalies over the equatorial western-central Pacific, reinforcing El Niño through the Bjerknes feedback and leading to the emergence of super El Niño. This novel mechanism is termed the Indo-Atlantic booster. The findings emphasize super El Niño as a product of three interactions, suggesting that incorporating both the Indian and Atlantic Oceans and their teleconnections with the Pacific will significantly enhance predictions of super El Niño and climate.

How to cite: Wang, C., Wang, J., and Fan, H.: Super El Niño: A product of three-ocean interactions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3728, https://doi.org/10.5194/egusphere-egu24-3728, 2024.

The El Niño-Southern Oscillation (ENSO) is one of the most significant integrated interannual oscillations with coupled atmosphere-ocean processes in the tropical Pacific. Most coupled climate models are weak in depicting ENSO asymmetry over equatorial Pacific subsurface. And it is still unclear how the stand-alone ocean model contributes to this bias. In this study, we found that most ocean models from the Ocean Model Intercomparison Project (OMIP), driven by JRA55, underestimate the asymmetry of ENSO in the equatorial western Pacific subsurface. We investigated the primary factors contributing to this bias using composite analysis and diagnostics, and found that the weaker responses in upwelling and stronger responses in downwelling to westerly and easterly wind stress anomalies in the models are mainly responsible for the bias. Furthermore, the underestimation of zonal current variability over western Pacific subsurface, influenced by the gradient of mean state of sea surface height along the equatorial Pacific, leads to an opposite relationship between asymmetry and the zonal component of nonlinear dynamic heating in the western Pacific subsurface comparing to that in the eastern Pacific subsurface. Our study emphasizes the importance of accurately modeling ocean currents to capture the characteristics of ENSO nonlinearity and highlights the significance of nonlinear dynamic responses to external forcing.

How to cite: Li, J. and Yu, Y.: Underestimated ENSO Asymmetry and Zonal Currents over the Equatorial Western Pacific in OMIP2 experiments , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4811, https://doi.org/10.5194/egusphere-egu24-4811, 2024.

EGU24-4820 | ECS | Posters on site | CL2.4

Synchronous Decadal Climate Variability in the Tropical Central Pacific and Tropical South Atlantic 

Chao Liu, Soon-Il An, Soong-Ki Kim, Malte Stuecker, Wenjun Zhang, Fei-Fei Jin, Jae-Heung Park, Leishan Jiang, Aoyun Xue, Xin Geng, Hyo-Jin Park, Young-Min Yang, and Jong-Seong Kug

The El Niño-Southern Oscillation (ENSO), the strongest interannual climate signal, has a large influence on remote sea surface temperature (SST) anomalies in all three basins. However, a missing map piece in the widespread ENSO teleconnection is the Equatorial Atlantic, where the ENSO footprint on local SST is less clear. Here, using reanalysis data and partially coupled pacemaker experiments, we show that the tropical Pacific SST anomalies, manifested as a Central Pacific (CP) ENSO-like structure, synchronize the tropical South Atlantic (40°W-10°E, 15°S-0°) SST anomalies over the last seven decades, but on a quasi-decadal (8-16 year) timescale. Such a decadal connection is most evident during the boreal spring-summer season, when the CP ENSO-like decadal SST anomalies induce a cooling of the South Atlantic SSTs through atmospheric teleconnections involving both Southern Hemisphere extratropical Rossby waves and equatorial Kelvin waves. The resulting subtropical South Atlantic low-level anticyclonic circulation and easterlies at its northern flank cause local ocean-atmosphere feedback and strengthen the Pacific-to-Atlantic teleconnections. In contrast, the concurrent tropospheric temperature teleconnection is less destructive to the above Atlantic SST response due to the weaker and more west decadal Pacific SST anomalies compared to the interannual ENSO counterpart. Pacific-driven coupled simulations reproduce key observational features fairly well, while parallel Atlantic-driven simulations show little forcing into the Pacific. Our results show that the tropical Central Pacific is an important source of decadal predictability for the tropical South Atlantic SST and the surrounding climate.

How to cite: Liu, C., An, S.-I., Kim, S.-K., Stuecker, M., Zhang, W., Jin, F.-F., Park, J.-H., Jiang, L., Xue, A., Geng, X., Park, H.-J., Yang, Y.-M., and Kug, J.-S.: Synchronous Decadal Climate Variability in the Tropical Central Pacific and Tropical South Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4820, https://doi.org/10.5194/egusphere-egu24-4820, 2024.

EGU24-5122 | Orals | CL2.4

The mechanism of multi-year La Niña events and their impact on spring precipitation over southern China 

Licheng Feng, Guangliang Li, and Ronghua Zhang

By diagnosing and analyzing the frequent occurrence of multi-year La Niña events in recent years, this study reveals the process and mechanism of the Southeast Pacific subsurface cold water triggering multi-year La Niña events. Revealing for the first time the propagation channels and physical processes of multi-year La Niña events triggered by subsurface cold water. In late spring and early summer, the anomalous eastward wind strengthens in the central equatorial Pacific, while abnormal wind stress divergence occurs in the eastern Pacific, which strengthens and spreads westward over time. The weak negative sea surface temperature anomaly in the eastern equatorial Pacific is accompanied by upwelling, providing a source of cold water for the surface. As the season progresses, the weakened equatorial undercurrent and the enhanced southern equatorial current cause cold water to spread westward and accumulate in the central Pacific, thereby extending upwards to expose the sea surface. The exposed cold water causes a cooling of the sea surface and triggers local sea atmosphere interactions, leading to abnormal development of sea atmosphere and ultimately forming a multi-year La Niña events. Composite analyses were performed in this study to reveal the differences in spring precipitation over southern China during multiyear La Niña events from 1901-2015. It was found that there is significantly below normal precipitation in the first boreal spring, but above normal in the second year. The differences in spring precipitation over southern China are correlative to the changes in anomalous atmospheric circulations over the northwest Pacific, which can in turn be attributed to different anomalous sea surface temperatures (SSTs) over the tropical Pacific. During multiyear La Niña events, anomalous SSTs were stronger in the first spring than those in the second spring. As a result, the intensity of abnormal cyclones (WNPC) in the western North Pacific Ocean (WNP) in the first year is stronger, which is more likely to reduce moisture transport, leading to prolonged precipitation deficits over southern China. In contrast, the tropical SST signal is too weak to induce appreciable changes in the WNPC and precipitation over South China in the second year. The difference in SST signals in two consecutive springs leads to different spatial patterns of precipitation in southern China by causing different WNPC.

How to cite: Feng, L., Li, G., and Zhang, R.: The mechanism of multi-year La Niña events and their impact on spring precipitation over southern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5122, https://doi.org/10.5194/egusphere-egu24-5122, 2024.

Understanding external drivers of the El-Nino Southern Oscillation (ENSO) is essential for predicting its future evolution. Orbital precession has been identified as a driver of ENSO variability through both proxy records and climate model simulations, yet the exact mechanics remain unclear. This orbital cycle moderates the seasonal timing of insolation relative to Earth's revolution around the Sun, thereby adjusting the magnitude of the seasonal cycle experienced by each hemisphere. Here, we analyze output from a suite of simulations in NCAR CESM 2.1.1 designed to analyze ENSO under different precessional extremes that significantly modify the meridional temperature gradients and the cold tongue seasonal cycle in the Pacific ocean. Variations in orbital precession have a strong impact on the magnitude, periodicity, and spatial expression of tropical Pacific variability. We find a critical role for both the North and South Pacific Meridional Modes (NPMM and SPMM) in explaining changes in ENSO and decadal variability by propagating subtropical anomalies to the equatorial Pacific along with a shift in the meridional structure of equatorial winds. As an example, when the perihelion of orbit occurs during boreal winter creating a dampened (strengthened) seasonal cycle in the Northern (Southern) Hemisphere, the SPMM becomes significantly more active while the NPMM weakens. This precessional state experiences a shift toward amplified decadal variability and a greater prevalence of Eastern El Nino events in comparison with the other orbital configurations tested. Understanding the precessional control of tropical variability via subtropical pathways may help explain developments that have occurred in the past, as well as future changes which may be observed due to shifts in meridional temperature gradients.

How to cite: Persch, C. and Sanchez, S.: A Critical Role for Meridional Modes in Determining the Equatorial Pacific Response to Orbital Precession, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6660, https://doi.org/10.5194/egusphere-egu24-6660, 2024.

The winter sea surface temperature (SST) anomalies in the Kuroshio and adjacent regions (KAR), which greatly influence the East Asian–North Pacific–North American climate, are closely related to El Niño–Southern Oscillation (ENSO). This SST relationship between the KAR and the equatorial eastern-central Pacific is widely assumed to be symmetric between El Niño and La Niña. Compared to previous studies indicating the significant and strong KAR warming during El Niño winters, this study indicates weakly negative KAR SST anomalies in the composite analysis for all La Niña events. Positive winter KAR SST anomalies unexpectedly appear in approximately half of La Niña events, which counteract negative SST anomalies in the rest of La Niña events. Further analysis suggests that the impact of La Niña on KAR SST anomalies is modulated by the East Asian winter monsoon (EAWM) during early winter. The weaker-than-normal EAWM offsets the anomalous northeasterly winds in the KAR induced by La Niña and then reinforces the KAR warming through warm oceanic advection. As for strong EAWM, it enhances the northeasterly winds to the west of an anomalous Philippine Sea cyclone associated with La Niña, leading to KAR cooling with more latent heat flux loss from the ocean and anomalous cold oceanic advection. Additionally, when the EAWM is independent of ENSO and is associated with the western Pacific pattern, it also can exhibit a pronounced influence on the KAR SST anomalies via the major processes of surface latent flux and horizontal heat advection in the ocean, accompanied by a change in Kuroshio transport.

How to cite: Chen, S., Chen, J., Wang, X., and Xiao, Z.: Varying Relationship between La Nin a and SST Anomalies in the Kuroshio and Adjacent Regions during Boreal Winter: Role of the East Asian Winter Monsoon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7307, https://doi.org/10.5194/egusphere-egu24-7307, 2024.

EGU24-7849 | ECS | Orals | CL2.4

On the decadal changes of Atlantic-Pacific interactions and the effects of external forcing 

Soufiane Karmouche, Evgenia Galytska, Gerald A. Meehl, Jakob Runge, Katja Weigel, and Veronika Eyring

We show the results of a study investigating the predominant role of external forcing in steering Atlantic and Pacific ocean variability during the latter half of the 20th (and early 21st) century. By employing the PCMCI+ causal discovery method, we analyze reanalysis data, pacemaker simulations, and a CMIP6 pre-industrial control run. The results reveal a gradual (multi)decadal change in the interactions between major modes of Atlantic and Pacific interannual climate variability from 1950 to 2014. A sliding window analysis identifies a diminishing El Niño-Southern Oscillation (ENSO) effect on the adjacent Atlantic basin through the tropical route, coinciding with the North Atlantic trending toward and maintaining an anomalously warm state after the mid-1980s. In reanalysis, this is accompanied by the prevalence of an extra-tropical pathway connecting ENSO to the tropical Atlantic. Meanwhile, causal networks from reanalysis and pacemaker simulations indicate that increased external forcing might have contributed to strengthening ENSO’s opposite sign response to tropical Atlantic variability during the 1990s and early 21st century, where warming tropical Atlantic sea surface temperatures induced La Niña-like easterly winds in the equatorial Pacific. The analysis of the pre-industrial control run underscores that modes of natural climate variability in the Atlantic and Pacific influence each other also without anthropogenic forcing. Modulation of these interactions by the long-term states of both basins is observed. This work demonstrates the potential of causal discovery for a deeper understanding of mechanisms driving changes in regional and global climate variability.

 

Karmouche, S., Galytska, E., Meehl, G.A., Runge, J.,Weigel, K.,& Eyring,V. (2023b, in review). Changing effects of external forcing on Atlantic-Pacific interactions. EGUsphere, 2023, 1–36. https://doi.org/10.5194/egusphere-2023-1861

How to cite: Karmouche, S., Galytska, E., Meehl, G. A., Runge, J., Weigel, K., and Eyring, V.: On the decadal changes of Atlantic-Pacific interactions and the effects of external forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7849, https://doi.org/10.5194/egusphere-egu24-7849, 2024.

Processes leading to the onset and development of an El Niño event in the tropical Pacific remain elusive. Observed data and Ocean General Circulation Model (OGCM) simulations are used to reveal a well-defined pattern of sea surface temperature (SST) perturbations along the mean North Equatorial Countercurrent (NECC) pathways in association with the onset and evolution of some El Niño events. The OGCM-based sensitivity experiments are conducted to illustrate how a warm SST anomaly (SSTA) on the equator can result from a thermal forcing that is prescribed north of 10°N, similar to observed SST anomalies in December 1988. Within approximately one year, the imposed SST anomaly north of 10°N tends to be transported to the dateline region on the equator by the mean ocean circulation in the western Pacific (the low-latitude western boundary current (LLWBC) and the NECC). In due course, an upper-layer ocean warming is generated off the equator at 6-10°N and then on the equator, which acts to induce a westerly wind anomaly response; a simple statistical atmospheric wind stress model is then used to depict an expected westerly wind response. These resultant SST and surface wind perturbations can couple together over the western tropical Pacific, forming air-sea interactions and setting up a stage for El Niño onset. As such, this pathway mechanism can reasonably well explain the appearance of a warm SST anomaly on the equator in the dateline region and the corresponding development of westerly wind anomalies over the western Pacific in association with El Niño onset.

 

How to cite: Gao, C. and Zhang, R.: A Mechanism from Pathway Perspective for the Generation of a Warm SST Anomaly in the Western Equatorial Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8442, https://doi.org/10.5194/egusphere-egu24-8442, 2024.

EGU24-8581 | ECS | Posters on site | CL2.4 | Highlight

Increased predictability of extreme El Niño from decadal interbasin interaction 

Xuan Ma, Rizhou Liang, Xiaosong Chen, Fei Xie, Jinqing Zuo, Cheng Sun, and Ruiqiang Ding

Predicting extreme El Niño–Southern Oscillation (ENSO) events remains a formidable task. Utilizing eigen microstates (EMs) of complex systems, we elucidate the interplay of two key sea surface temperature (SST) anomaly modes, the newly identified North Atlantic–west Pacific Mode (NAPAM) and discovered Victoria Mode (VM). Our findings demonstrate that a cold NAPAM phase coupled with a positive VM phase markedly elevates the probability of extreme El Niño events; NAPAM's decadal variability serves as a key modulator of extreme El Niño events' frequency. Our empirical model, capitalizing on these modes, achieves robust forecasts with a 6–8 month lead time and boasts a 0.73 correlation with the observed ENSO index in hindcasts. Notably, the model precisely forecasts the intensity of four landmark extreme El Niño episodes: 1982/1983, 1987/1988, 1997/1998, and 2015/2016. Our findings offer promising avenues for refining ENSO predictive frameworks and deepen our understanding of the key climatic drivers.

How to cite: Ma, X., Liang, R., Chen, X., Xie, F., Zuo, J., Sun, C., and Ding, R.: Increased predictability of extreme El Niño from decadal interbasin interaction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8581, https://doi.org/10.5194/egusphere-egu24-8581, 2024.

EGU24-9096 | ECS | Orals | CL2.4 | Highlight

Effects of Niño1+2 and Niño3.4 ENSO Events over Euro-Mediterranean Climate Variability  

Ece Yavuzsoy-Keven, Yasemin Ezber, and Omer Lutfi Sen

El Niño Southern Oscillation (ENSO) is a climate phenomenon that affects the atmospheric circulation of the Northern Hemisphere and causes short-term variability in temperature and precipitation patterns. ENSO impacts over the Euro-Mediterranean (EM) region are commonly defined by using Niño3.4 and Niño3 indices. However, some recent studies indicate that the ENSO event represented by both Niño1+2 and Niño3.4 indices (shared ENSO) is more effective over EM region climate.

In this study, we examine the response of the EM climate to ENSO events detected by Niño1+2 and Niño3.4 regions. NCEP/NCAR Reanalysis surface air temperature, precipitation, 500 hPa geopotential height, 850 hPa wind, and 300 hPa zonal wind datasets and SST-based ENSO indices from ERSSTv4 were used in the analysis for boreal winters between 1950 and 2019. For composite analysis, we separated ENSO events as El Niño and La Niña according to those observed in Niño1+2, Niño3.4, and both regions. We also tried to understand if there is any relation between ENSO and teleconnection patterns such as NAO, East Atlantic (EA), Trough Displacement Index for the Mediterranean Trough (TDI_MedT), and East Atlantic/Western Russia (EAWR) by using the cross-correlation analysis. Additionally, investigate the winter (December, January, February, DJF) ENSO’s possible lagged impacts on the teleconnection patterns in the subsequent seasons, spring (March-April-May, MAM), summer (June-July-August, JJA), and autumn (September-October-November, SON).

The major finding of this study is that the shared ENSO event is more effective over the EM climate than the ENSO events detected only by Niño1+2 or Niño3.4 indices. Further, it is also important for the predictability of the EM climate. In the shared El Niño event, the Middle East and much of North Africa tend to become colder than climatology while Europe becomes warmer. The anticyclonic wind anomaly over western Europe causes drier air in southern Europe and wetter air in northern Europe. The shared El Niño event also modulates the westerly flows at the upper troposphere. The westerly flow accelerates over high latitudes while decelerates over European mid-latitudes, causing northern Europe to be wetter and the Mediterranean Basin to be drier. The cross-correlation analysis including all SST-based ENSO indices and teleconnection indices that the EA index has a significant correlation with the Niño1+2 index across all seasons.

How to cite: Yavuzsoy-Keven, E., Ezber, Y., and Sen, O. L.: Effects of Niño1+2 and Niño3.4 ENSO Events over Euro-Mediterranean Climate Variability , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9096, https://doi.org/10.5194/egusphere-egu24-9096, 2024.

EGU24-9334 | ECS | Orals | CL2.4

Characterizing Nonlinearities in ENSO Dynamics Using Hybrid Machine Learning Models 

Jakob Schlör, Jannik Thuemmel, Antonietta Capotondi, Matthew Newman, and Bedartha Goswami

Event-to-event differences of the El Niño Southern Oscillation (ENSO) result in different patterns of extreme climate conditions globally, which requires ENSO forecasts that accurately predict both the likelihood and the type of an event. One question regarding predictable ENSO dynamics is the extent to which they may be captured by multivariate linear dynamics and, relatedly, whether predictable nonlinearities must be accounted for or may be treated stochastically.

In this study, we combine Recurrent Neural Networks with the Linear Inverse Model (LIM) to assess the role of predictable nonlinearities and non-Markovianity in the evolution of tropical Pacific sea surface temperature anomalies. We observe that modeling nonlinearities significantly enhances the forecast accuracy, particularly in the western tropical Pacific within a 9 to 18-month lag time. Our results indicate that the asymmetry of warm and cold events is the main source of the nonlinearity. Moreover, we demonstrate that the predictability of the Hybrid-model can be reliably inferred from the theoretical skill of the LIM whereas a similar assessment is not possible in pure deep learning models.

How to cite: Schlör, J., Thuemmel, J., Capotondi, A., Newman, M., and Goswami, B.: Characterizing Nonlinearities in ENSO Dynamics Using Hybrid Machine Learning Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9334, https://doi.org/10.5194/egusphere-egu24-9334, 2024.

The interannual variability of boreal summer sea surface temperature (SST) in the tropical Atlantic displays two dominant modes, the Atlantic zonal mode highlighting SST variations in the equatorial–southern tropical Atlantic (ESTA) region and the northern tropical Atlantic (NTA) mode focusing on SST fluctuations in the NTA region except in the Gulf of Guinea. Observational evidence indicates that both the boreal summer ESTA and NTA warming are accompanied by a pair of anomalous low-level anticyclones over the western tropical Pacific, and the NTA-related anticyclone is more obvious than the ESTA-related one. Both atmosphere-only and partially coupled experiments conducted with the Community Earth System Model version 1.2 support the observed NTA–Pacific teleconnection. In contrast, the ESTA-induced atmospheric circulation response is negligible over the tropical Pacific in the atmosphere-only experiments, and although the response becomes stronger in the partially coupled experiments, obvious differences still exist between the simulations and observation. The ESTA-induced atmospheric circulation response features an anomalous low-level cyclone over the western tropical Pacific in the partially coupled experiments, opposite to its observed counterpart. It is found that the ESTA warming coincides with significantly La Ni ñ a–like SST anomalies in the central–eastern equatorial Pacific,the influence of which on the tropical atmospheric circulation is opposite to that of the ESTA warming, and therefore contributes to difference between the ESTA-related simulations and observation. Moreover, the cold climatological mean SST in the ESTA region is unfavorable to enhancing the ESTA–Pacific teleconnection during boreal summer

How to cite: Ren, H.: The Impact of Tropical Atlantic SST Variability on the Tropical Atmosphere duringBoreal Summer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9772, https://doi.org/10.5194/egusphere-egu24-9772, 2024.

EGU24-10200 | ECS | Orals | CL2.4 | Highlight

Roles of Tropical-Pacific Interannual–Interdecadal Variability in Forming the Super Long La Niña Events 

Run Wang, Hong-Li Ren, and Minghong Liu

The super long La Niña phenomenon, which has an extremely long duration, like the recent 2020–2023 La Niña event, is less concerned than the super El Niño. In this study, we identify five super long La Niña events after 1950 and investigate roles of the 2–3-year quasi-biennial (QB) and 3–7-year low-frequency (LF) ocean–atmosphere coupled processes of El Niño–Southern Oscillation (ENSO), and the interdecadal background in forming the basin-scale prolonged negative sea surface temperature anomalies (SSTAs) during these events. We group the five events into the thermocline-driven type (the 1983–1986 and 1998–2002 events) and the wind-driven type (the 1954–1957, 1973–1976, and 2020–2023 events). The former inherited a sufficiently discharged state of equatorial upper-ocean heat content from the preceding super El Niño and dominated by the thermocline feedback, leading to a LF oceanic dynamical adjustment to support the maintenance of negative ENSO SSTAs. The latter were promoted by the relatively more important zonal advective feedback and Ekman pumping feedback and deeply affected by a strongly negative equatorial zonal wind stress background state that sourced from the strong negative phase of the Interdecadal Pacific Oscillation. Besides, the QB ENSO variability with casual contributions during these events is less important. Results show that both the LF ENSO variability and the interdecadal Pacific background could assist to the genesis of such elongated La Niñas.

How to cite: Wang, R., Ren, H.-L., and Liu, M.: Roles of Tropical-Pacific Interannual–Interdecadal Variability in Forming the Super Long La Niña Events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10200, https://doi.org/10.5194/egusphere-egu24-10200, 2024.

EGU24-11374 | ECS | Orals | CL2.4 | Highlight

The El Niño response to tropical volcanic eruptions and geoengineering  

Clarissa Kroll and Robert Jnglin Wills

Following tropical volcanic eruptions and in response to geoengineering efforts in climate models, the occurrence of El Niño is notably enhanced. However, the precise mechanisms leading to the preference of the El Niño state remain a subject of ongoing debate. In this study, we explore the El Niño response within the context of stratospheric aerosol injection experiments using the Community Earth System Model version 1, with the Whole Atmosphere Community Climate Model atmospheric component (CESM1 WACCM). Our investigation is centered around the Stratospheric Aerosol Geoengineering Large Ensemble Dataset encompassing three distinct scenarios: a simulation of the RCP8.5 scenario as baseline climate change scenario, a geoengineering scenario, in which surface temperature increases are completely compensated and a scenario focusing solely on the stratospheric heating derived from the geoengineering approach. Our analysis reveals that the El Niño response is primarily linked to the heating in the tropical tropopause layer and lower stratosphere, and notably, it occurs independently of tropospheric cooling effects. We explain the increased occurrence of El Niño after volcanic eruptions and simulated geoengineering interventions by a slow down of the tropical atmospheric circulation, which is caused by increases in gross moist stability due to aerosol heating in tropical tropopause layer.

How to cite: Kroll, C. and Jnglin Wills, R.: The El Niño response to tropical volcanic eruptions and geoengineering , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11374, https://doi.org/10.5194/egusphere-egu24-11374, 2024.

EGU24-11643 | ECS | Orals | CL2.4

Dynamical systems analysis of the "El Niño Southern Oscillation" phenomenon  

Julia Mindlin, Gabriel B Mindlin, and Pedro di Nezio

Since the 1980s, when the World Meteorological Organization launched the TOGA (Tropical Ocean-Global Atmosphere Program) program, great advances have been made in understanding ENSO by studying a hierarchy of models (Dijkstra, 2005). At the most complex end of this hierarchy are the Global Climate Models (GCMs), with which simulations of the entire climate system are performed, while at the most elementary end are the simple dynamical models that involve the minimum number of modes necessary to generate the phenomenon and therefore represent the dominant physical processes. Conceptually, two different ways of understanding the irregular oscillations of ENSO are still valid: it could be either a self-sustained oscillator of a chaotic nature or a stable mode excited by atmospheric noise. 

In this work, we use methods from complex systems to revisit the ideas regarding two plausible dynamics of ENSO. We ask if the dynamics can be better represented as a self-sustained oscillator of a chaotic nature or a stable mode excited by noise. For this, we analyzed the sea surface temperatures (SSTs), one of the output variables of the simulations generated with GCMs, the most complex simulations available from the extended system. This temperature field averaged in a particular region of the eastern equatorial Pacific (Niño 3.4) gives rise to a temporal signal widely used for ENSO monitoring and as a proxy for the study of the oscillation. In order to analyze the dynamics of the system, we reconstruct the phase space from an embedding of the temporal signal. We find that three modes are enough to recover the ENSO dynamics of the extended system, in principle of infinite dimension. Our conceptual model is based on the existence of a self-sustaining oscillation with a critical slowing down in phase space; that is, the system traverses a region of phase oscillation with a critical slowing down in phase space; that is, the system traverses a region of phase space more slowly, and includes a periodic forcing that gives rise to chaotic behavior for certain values of the parameters. We validate the model with a topological and statistical analysis of the periodic orbits in the system and, in addition, we show that the complexity of the signal is better represented as a self-sustained oscillator of a chaotic nature than as a stable mode excited by noise (Wang, 2018).

Dijkstra, HA, Nonlinear Physical Oceanography, volume 28. Springer, 2nd revised edition, 2005.

Wang C., A review of ENSO theories, National Science Review, Volume 5, Issue 6, November 2018, Pages 813–825

How to cite: Mindlin, J., Mindlin, G. B., and di Nezio, P.: Dynamical systems analysis of the "El Niño Southern Oscillation" phenomenon , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11643, https://doi.org/10.5194/egusphere-egu24-11643, 2024.

EGU24-12873 | ECS | Orals | CL2.4

The Dynamics and Propagation of Westerly Wind Bursts 

Inko Bovenzi, Minmin Fu, and Eli Tziperman

Westerly wind bursts (WWBs), a westerly anomaly in equatorial winds in the Pacific, occur before every major El Niño event, yet major aspects of their mechanism are still not fully understood. Proposed mechanisms include cyclones approaching the equator, eastern-propagating convective heating, and wind-induced surface heat exchange, which amplifies WWBs near their peaks (Fu and Tziperman, 2019). To better understand WWB dynamics, we study their composite momentum budget using reanalysis and examine the role of convective heating and other factors. We find that many WWBs are not directly explained by nearby tropical cyclones or convective precipitation. We study their momentum budget before, during, and after the peak of the event, finding different balances at each stage. A comparison of the deduced balance to that in atmospheric general circulation climate models should add confidence in their ability to simulate this important factor in El Niño's development.

How to cite: Bovenzi, I., Fu, M., and Tziperman, E.: The Dynamics and Propagation of Westerly Wind Bursts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12873, https://doi.org/10.5194/egusphere-egu24-12873, 2024.

EGU24-12936 | Orals | CL2.4

A Regime View of ENSO Flavors Through Clustering in CMIP6 Models 

Pradeebane Vaittinada Ayar, David Battisti, Camille Li, Martin King, Mathieu Vrac, and Jerry Tjiputra

El Niño-Southern Oscillation (ENSO) flavors in the tropical Pacific are studied from a regime perspective. Five recurring spatial patterns or regimes characterizing the diversity of ENSO are established using a clustering approach applied to the HadISST sea surface temperature (SST) anomalies. Compared to previous studies, our approach gives a monthly characterization of the diversity of the warm and cold phases of ENSO established from observations but commonly applied to models and observations. Two warm (eastern and central El Niño), two cold (basin wide and central La Niña) and a neutral reference regimes are found. Simulated SST anomalies by the models from the latest Coupled Model Intercomparison Project Phase 6 are then matched to these reference regimes. This allows for a consistent assessment of the skill of the models in reproducing the reference regimes over the historical period and the change in these regimes under the high-warming Shared Socio-economic Pathway (SSP5.8.5) scenario. Results over the historical period show that models simulate well the reference regimes with some discrepancies. Models simulate more intense and spatially extended ENSO patterns and have issues in capturing the correct regime seasonality, persistence, and transition between regimes. Some models also have difficulty simulating the frequency of regimes, the eastern El Niño regime in particular. In the future, both El Niño and central La Niña regimes are expected to be more frequent accompanied with a less frequent neutral regime. The central Pacific El Niño and La Niña regimes are projected to increase in amplitude and variability. 
Reference:
Vaittinada Ayar, P.Battisti, D. S.Li, C.King, M.Vrac, M., & Tjiputra, J. (2023). A regime view of ENSO flavors through clustering in CMIP6 modelsEarth's Future11, e2022EF003460. https://doi.org/10.1029/2022EF003460

How to cite: Vaittinada Ayar, P., Battisti, D., Li, C., King, M., Vrac, M., and Tjiputra, J.: A Regime View of ENSO Flavors Through Clustering in CMIP6 Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12936, https://doi.org/10.5194/egusphere-egu24-12936, 2024.

In recent decades, a growing body of research has highlighted the intricate interplay between the El Niño-Southern Oscillation (ENSO) and various climatic patterns across multiple ocean basins. Several studies have highlighted the significance of the South Atlantic Subtropical Dipole (SASD) and its association with ENSO.

This investigation examines the interaction between SASD and ENSO, focusing on the critical role of the South Pacific High in these dynamics. Our study proposes that the onset of the South American Monsoon (SAM) plays a crucial role in this connection, challenging the traditional perception of land's passive role in tropical interbasin interactions.

We identified two eastern Pacific and two central Pacific ENSO precursors from SAM onset period using ERA5 reanalysis data along with 1200-year CESM2 PI run. Applying partial linear regressions revealed the following patterns: initially, warm Southwestern Tropical Atlantic (SWTA) and basin-wide low pressure in the equatorial and subequatorial Atlantic, evolving into cold Southeastern Tropical Pacific (boreal spring); then, negative South Pacific Oscillation (SPO) during the following boreal summer, culminating in La Niña conditions between 12 and 15 months later (SON and DJF of the following year).

We hypothesize that anomalous upper-level divergent monsoonal circulation acts as a bridge connecting the two ocean basins. Ekman dynamics arguably transfers and amplify atmospheric signals from the SAM and SPO to the equatorial Pacific Ocean.

Random Forest and Support Vector Machines for regression analysis yielded results consistent with those from the linear model; superior skill was noted in La Niña prediction compared to under-predicted El Niño events.

Moving forward, we intend to construct causal networks to disentangle the complex interplays described herein while ensuring independence from other known teleconnections; alternatively, we plan to design appropriate numerical experiments using coupled GCMs.

This study's preliminary results present exciting opportunities to enhance early ENSO prediction by considering the impact of the South American Monsoon on aligning the variability of the tropical South Atlantic and South Pacific oceans.

How to cite: Bellacanzone, F. and Bordoni, S.: Enhancing early ENSO prediction: how the South American Monsoon onset connects the South Atlantic Subtropical Dipole and the South Pacific Oscillation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13140, https://doi.org/10.5194/egusphere-egu24-13140, 2024.

EGU24-13513 | ECS | Posters on site | CL2.4 | Highlight

Impact of summer-persistent ENSO events on the global climate and the occurrence of extreme weather events 

Anna Schultze, Zhengyao Lu, Qiong Zhang, Minjie Zheng, and Thomas Pugh

El Niño Southern Oscillation (ENSO), the most prominent climate variability in the tropical Pacific Ocean, significantly influences global climate and weather patterns, impacting ecosystems and societies worldwide. Our study focuses on the underexplored aspect of summer-persistent ENSO events, their global climatic impacts, and their role in triggering extreme weather occurrence.

ENSO events follow a distinct cycle, with El Niños more tightly bound to this cycle, while some La Niñas tend to fall below the ENSO threshold during the summer and then re-intensify in the following winter, resulting in multi-year La Niña events. However, there have been cases of slower ENSO decay, where sea surface temperature anomalies (SSTA) exceeding the ENSO threshold values into the northern-hemisphere summer, have been observed. The 2018/2019 El Niño, persisting until July, is a recent example, linked to significant events like the severe Australian bushfires in 2020 and the longest heatwave in history in the North Pacific in 2019. The El Niño was followed by a triple-dip La Niña, linked to extreme weather events in Africa, Australia and the United States. This highlights the importance of understanding the summer-persistent ENSO events.

Our study is structured based on three aims: identifying past summer-persistent ENSO events, assessing their impacts on global temperature and precipitation patterns, and examining their linkage to extreme weather events. Utilizing the Oceanic Niño Index calculated from the extended reconstructed sea surface temperature (ERSSTv5), we categorised ENSO events into conventional, summer-persistent, and multi-year summer-persistent types. The latter two were defined by events in which the Oceanic Niño Index exceeded the ENSO threshold until June for one or two consecutives summer seasons, respectively. We identified 12 summer-persistent ENSO events since 1940, separated into four summer-persistent El Niños, five summer-persistent La Niñas, and three multi-year summer-persistent La Niñas. Analyzing ERA5 reanalysis composites of 2-m temperature and precipitation, we compared the climatic impacts of these ENSO variants across winter and summer. This study advances our understanding of the climatic consequences of summer-persistent ENSO events, providing insights crucial for developing mitigation strategies for their impacts on global climate and extreme weather occurrences.

How to cite: Schultze, A., Lu, Z., Zhang, Q., Zheng, M., and Pugh, T.: Impact of summer-persistent ENSO events on the global climate and the occurrence of extreme weather events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13513, https://doi.org/10.5194/egusphere-egu24-13513, 2024.

The El Niño Southern Oscillation (ENSO) dominates tropical climate variability. While it is defined by alterations in sea surface temperatures in the eastern and central tropical Pacific, ENSO influences temperature and precipitation patterns across the globe through a network of atmospheric and oceanic teleconnections. Whether ENSO is controlled or responds to external climate factors has long remained elusive, in large part due to the lack of paleoclimate evidence of tropical variability during different climate states. Here we utilize the geochemical signatures of planktic foraminifera to reconstruct eastern and central tropical variability during the last glacial maximum (LGM), some 20-25,000 years ago. Climate conditions during the LGM were very different, featuring atmospheric CO2 concentrations, global temperatures, and sea level all substantially lower than today. However, precessional forcing, thought to be a potential control on ENSO expression, was similar to modern orbital configuration. Our reconstruction spans the central and eastern tropical Pacific during this key time frame and assesses how the patterns of variability - or ENSO ‘flavors’ - may have changed. We compare our spatial reconstructions of variability to changes in the equatorial Pacific thermocline and test hypotheses of thermocline control of ENSO. We explore the evolution of the eastern and central Pacific thermocline, and how their relationship may be an additional factor in influencing ENSO expression. Our results provide key insights into the evolution and history of tropical variability under differing background climate states, providing context for modern ENSO behavior and prediction.

How to cite: Rustic, G., Rosenheim, E., Slotter, J., and Hill, K.: Reconstructing Tropical Pacific Variability During the Last Glacial Maximum Using Individual Foraminifera: An Investigation of ENSO Flavors , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13790, https://doi.org/10.5194/egusphere-egu24-13790, 2024.

EGU24-13992 | ECS | Orals | CL2.4

Oceans outside the tropical Pacific influence ENSO when ENSO predictability is poor 

Jemma Jeffree, Nicola Maher, Dillon Amaya, and Dietmar Dommenget

Various studies demonstrate that the El Niño Southern Oscillation is influenced by each of the Atlantic Ocean, Indian Ocean, extra-tropical Pacific Ocean and Southern Ocean. However, there is no cohesive picture of the relative importance of different ocean basins. Furthermore, even when considering only one basin, there is disagreement over the strength of it's influence on ENSO. Differences between previous studies likely arise from differences in their design. Untangling interbasin influences is non-trivial, due to  the need to distinguish between correlation and causation. Investigating these interbasin interactions is additionally complicated by model bias, and computational expense limiting the breadth of model studies.

We investigate the interbasin influences on ENSO from a new angle. We use analogue forecasting instead of initialised ensemble forecasting: we select analogues similar to some target state from a long model run (e.g. pre-industrial control or single model initial-condition large ensemble), rather than initialising from that target state. The analogue forecasts, made by following the selected analogues through time in the model run, have been previously evaluated to show similar skill to an initialised forecast. These forecasts are much faster than traditional initialised forecasts, allowing us to explore multiple models, lead times and initialisation months. We explore whether these analogue forecasts are improved by considering information from regions outside the tropical Pacific, and then infer how these regions contribute to ENSO evolution.

When ENSO forecasts are skilful, before the Spring Predictability Barrier, outside influences have little impact on ENSO forecast skill. When ENSO forecasts cross the Spring Predictability Barrier and are poor, then considering information from outside the Tropical Pacific Ocean improves forecasts. We conclude that when ENSO is in a growth phase it dominates the climate system, but in a decay phase ENSO is influenced by regions outside the tropical Pacific. This behaviour is consistent across at least two global coupled climate models, despite large variability in the way these models represent ENSO's seasonal evolution. We intend to expand this investigation to more models, and to compare the impacts of verifying forecasts against observational or model data.

How to cite: Jeffree, J., Maher, N., Amaya, D., and Dommenget, D.: Oceans outside the tropical Pacific influence ENSO when ENSO predictability is poor, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13992, https://doi.org/10.5194/egusphere-egu24-13992, 2024.

EGU24-15294 | ECS | Orals | CL2.4

Towards a better understanding of ENSO diversity: a paleoclimate perspective 

Isma Abdelkader Di Carlo, Pascale Braconnot, Matthieu Carré, Mary Elliot, and Olivier Marti

El Niño-Southern Oscillation (ENSO) events are hard to put in one category because they differ in intensity, spatial pattern, and temporal evolution. Studies have characterized events into two main categories: central Pacific (CP) and eastern Pacific (EP) events. The indicators used to compute EP and CP events are varied, from area-averaged regions to Empirical Orthogonal Function (EOF) analysis. In the recent climatic period, they all show similar results. However, future projections show differing results when using two different methods of computing EP and CP events. Since the observational period is too short, we use paleoclimate reconstructions, which provide unique and quantitative measures of past climate changes over long time scales. We will first synthesize previous studies and discuss how they have used paleoclimate modeling and/or data to provide clues into how ENSO diversity may have been shaped in past climates. Our results indicate that many apparent inconsistencies in future projection studies are due to misleading use of ENSO diversity indicators and that investigating ENSO diversity with a climate change perspective requires assessing both changes in the climate mean state (annual mean and seasonality) and changes in variability. 

How to cite: Abdelkader Di Carlo, I., Braconnot, P., Carré, M., Elliot, M., and Marti, O.: Towards a better understanding of ENSO diversity: a paleoclimate perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15294, https://doi.org/10.5194/egusphere-egu24-15294, 2024.

EGU24-17071 | ECS | Posters on site | CL2.4

Present and future of Extreme El Niño teleconnections over North America in CMIP6 models 

Margot Beniche, Jérôme Vialard, and Matthieu Lengaigne

Previous studies did suggest a diversity of the ENSO teleconnection pattern, with an eastward shifted pattern for El Niño relative to La Niña or for “eastern Pacific” (EP) relative to “central Pacific” (CP) El Niño events. Recently, Beniche et al. (in revision) demonstrated that extreme El Niño events (i.e. the strongest EP events, such as those in 1982/83, 1997/98, and 2015/16) were the only events leading to a clear eastward shift of the winter ENSO teleconnection pattern over North America. This specific teleconnection is also associated with reproducible wet (warm) anomalies over the western USA coast (northern USA and Canada). They did however demonstrate it based on the limited observational dataset, and a single AMIP CNRM-CM6.1 ensemble.

The current study aims at evaluating the robustness of these results using the broader AMIP6 and CMIP6 datasets. The specificity of the Extreme El Niño North American winter teleconnection pattern, and its inter-event and inter-member reproducibility, are robust across 23 historical AMIP ensembles (1979-2014). These events are associated with 73% chances of warm conditions over the Northern USA and Canada and 68% chances of wet conditions over the Western US coast across the AMIP ensemble. The stronger reproducibility of the extreme El Niño teleconnections can be explained by a more favourable Signal to Noise (SNR) ratio (mainly due to stronger signal).

We further evaluate the realism of these teleconnections patterns in presence of the systematic biases that are present in CMIP6. We only select CMIP6 models that reproduce Extreme El Niño events based on the precipitation-index of Cai et al. (2014). In agreement with previous studies using CMIP5 (e.g. Bayr et al., 2019), we find that models with stronger cold climatological SST bias are unable to simulate extreme Niño3 rainfall anomaly events. CMIP6 models that reproduce extreme El Niño tropical rainfall reasonably also reproduce the specific extreme El Niño 500 hPa geopotential height and surface temperature winter teleconnection pattern over North America. They however do not reproduce well the specific wet anomalies over the west American coast associated with those events, casting doubt on the CMIP6 ability to project precipitation changes over this region. We end by discussing the relevance of these results for understanding projected changes in ENSO teleconnections over North America in the context of different Shared Socioeconomic Pathways (SSPs) scenarii.

How to cite: Beniche, M., Vialard, J., and Lengaigne, M.: Present and future of Extreme El Niño teleconnections over North America in CMIP6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17071, https://doi.org/10.5194/egusphere-egu24-17071, 2024.

EGU24-17210 | ECS | Posters on site | CL2.4 | Highlight

Crying wolf with the 2023 El Niño: a predicted event that failed to materialize? 

Sandro Carniel, Gian Luca Eusebi Borzelli, Aniello Russo, and Cosimo Enrico Carniel

The El Niño–Southern Oscillation (ENSO) is a phenomenon that involves the redistribution of heat in the tropical Pacific Ocean, resulting in irregular oscillations in the sea surface temperature (SST) between warm (El Niño) and cold (La Niña) phases, and impacting the global planetary climate. In July 2023 the World Meteorological Organization, formally responsible to declare the onset of El Niño, officially announced its onset to the media, urging governments to prepare for potential high impacts on health, ecosystems and economies. However, the analysis of long-term meteorological and oceanographic data updated to the end of 2023 shows that while the eastern Pacific was warmer than normal in the second half of the year, the overall configuration of the tropical Pacific climate system did not indicate a strong El Niño event. Our findings show that the 2023-24 El Niño event, initially predicted to be at least moderate and possibly strong, turned out to be weak and, de facto, the year closed confirming it as a weaker than expected event. Based on historical records, we hypothesize that the state of the Pacific climate system at the end of 2023, following the unusual 2023-24 El Niño, may lead to the development of a strong or very strong El Niño by mid-2024.

How to cite: Carniel, S., Eusebi Borzelli, G. L., Russo, A., and Carniel, C. E.: Crying wolf with the 2023 El Niño: a predicted event that failed to materialize?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17210, https://doi.org/10.5194/egusphere-egu24-17210, 2024.

EGU24-20761 | ECS | Orals | CL2.4

Visualizing the transition from LaNiño to ElNiño from NASA's model outputs 

Atousa Saberi and Gregory Shirah

The ENSO affects global weather. We used NASA GEOS Subseasonal to Seasonal (S2S) Coupled ocean-atmosphere model, NASA MERRA‐2 reanalysis, along with NOAA Niño3.4 SST anomaly index time series to visualize the transition from  LaNiño 2021 to ElNiño 2023. The visualization is a comprehensive model explainer showing changes in the top 300 meters of the Pacifc Ocean (such as thermocline flattening, movements of the temperature anomalies) coupled with the Walker Circulation and the continous coupled interaction between the ocean and the atmosphere. It's the first effort in visualizing the Walker Circulation and the moving convective branch across the Pacific without schematic plots but rather with climate model outputs.  We will also cover the effect of the two phases of ENSO on the global weather pattern. This visualization will be narrated and released to the public in the future.

How to cite: Saberi, A. and Shirah, G.: Visualizing the transition from LaNiño to ElNiño from NASA's model outputs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20761, https://doi.org/10.5194/egusphere-egu24-20761, 2024.

EGU24-21415 | Posters on site | CL2.4

How closely related are the Interdecadal Pacific Oscillation and El Niño-Southern Oscillation? 

Tim Cowan, Hanna Heidemann, Scott B. Power, and Benjamin J. Henley

Sea surface temperature (SST) patterns in the Pacific Ocean cause climate variability in many parts of the world. This is due to the El Niño-Southern Oscillation (ENSO) on interannual timescales and the Interdecadal Pacific Oscillation (IPO) acting on decadal to interdecadal timescales, modifying ENSO teleconnections. However, how both ENSO, ENSO diversity and the IPO interact with each other still requires further clarification. In this study, we use observations of Pacific Ocean SSTs from 1920 to 2022 to explore the statistical relationships between decadal ENSO variability and the IPO. More specifically, we show how ENSO event characteristics of both central and eastern Pacific El Niño, as well as all La Niña events varies between their occurrence in warm (positive), compared to cool (negative) phases of the IPO. We further show that up to 60% of the variability in the IPO Tripole Index can be reconstructed by using simple ENSO metrics such as the relative frequency of El Niño and La Niña events. While statistically a clear relationship between ENSO and the IPO exists, some of the IPO’s key features, especially North Pacific SSTs, cannot be explained by decadal ENSO variability.  

How to cite: Cowan, T., Heidemann, H., Power, S. B., and Henley, B. J.: How closely related are the Interdecadal Pacific Oscillation and El Niño-Southern Oscillation?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21415, https://doi.org/10.5194/egusphere-egu24-21415, 2024.

Monsoon rainfall and year-to-year variability play an important role in Africa’s energy, agriculture, and other societal sectors. Within the African continent, east African countries are affected much by higher degrees of variability in seasonal monsoon precipitation. Two large-scale climate drivers, the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO) are studied in this regard. A strong connection starting from a season ahead is identified for early austral summer (Oct-Nov-Dec, OND) monsoonal rain in eastern Africa.  This has been examined using various data sources, detrending data beforehand, analysing either recent or earlier time periods - covering two decades each, and using the analyses of regression. Results of compositing also suggested a strong significant anomaly in OND rain covering that region of east Africa (named here as region A:18˚S-12˚N, 25˚E-52˚E).  When IOD and ENSO are both negative in July-August-September(JAS) there is a significant deficit in OND rainfall, while an excess rain when both are positive. The Walker circulation plays a key role via altering descending and ascending branches in two circumstances. Based on this analysis, it is possible to deliver an estimation of cumulative rain in terms of median value, range and distribution, one season in advance, at a point location or average over a region. Results are further verified for recent two years of 2022 and 2023, where drivers were of same sign, either both negative (2022) or positive (2023). Classifications based on two drivers, starting from JAS, are not only modulating cumulative rain but also influencing onset dates; excess (deficit) rain and early (late) onset are associated with positive (negative) phases of both drivers. Interestingly, regions of east Africa, south of that box region show a complete reverse pattern in OND and that pattern continues till Dec-Jan-Feb. In terms of mechanisms, apart from Walker circulation, ocean also plays a key part.      

            Some results of compositing are confirmed for longer records (1940-2021) too and further classification of drivers, based on a threshold value (+0.4) is tested. In the recent year 2023, as both drivers were strongly positive in JAS, more analyses in such cases are presented.  We note, if either of the drivers is weak positive and lies in the range of 0 to +.04, the signal in region A weakens substantially on the eastern side of the box. The strongest weakening happens when both the drivers are of low magnitude in JAS (i.e.,  between 0 to +0.4). Rainfall (OND) variability of region A, at intra-decadal, decadal and multi-decadal scales are studied by applying the method of centered moving averages of 5-year, 11-year and 21-year respectively. A decreasing trend is noted in all situations and major peak/trough years are identified. For multi-decadal analyses, a shift at around 1958 is identified when the trend of OND rain is reversed and switched from increasing to decreasing. Our results have implications for future planning in optimizing energy and agricultural outputs and the livelihood of millions of east Africans will be impacted.   

How to cite: Roy, I. and Troccoli, A.: Important drivers of October to December rainfall season in eastern Africa and relevant mechanisms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21764, https://doi.org/10.5194/egusphere-egu24-21764, 2024.

EGU24-229 | ECS | Orals | CL2.5

The future changes in spatio-temporal distribution of urban heat load and factors that affect its variability 

Zdeněk Janků, Petr Dobrovolný, Jan Geletič, and Michal Lehnert

Summer temperature extremes are increasing rapidly under the current global climate change. Urban environments are among those most exposed to temperature extremes due to the urban heat island, and these exacerbated conditions significantly affect human health and activities, making urban heat load one of the most fundamental concerns for people living in cities. Our research quantifies spatio-temporal changes in urban heat load in two Central-European cities (Brno and Ostrava, Czech Republic) in different geographical configurations. We applied the urban climate model MUKLIMO_3, combined with the cuboid method, to simulate recent and future distributions of four summer climate indices. The simulation results clearly indicate continuous climate warming and project a significant increase in the mean annual values of summer climate indices by the end of the 21st century, particularly in the built-up areas with a predominance of impervious surfaces. Both model simulations and in-situ observations confirm that the magnitude of these changes can differ significantly from city to city suggesting the distribution of urban heat load is not only influenced by climate change, but also by local geography and anthropogenic factors. To determine the causes of the differences in urban heat load variability, we applied land use/land cover configuration metrics and correlation analysis using various geographical factors. Our results show that a compact and less fragmented land use/land cover structure can significantly increase the urban heat load. Altitude also has a strong influence on the heat load pattern in complex terrain. Therefore, some cities are and may continue to be extremely vulnerable to adverse summer temperature extremes. We suggest that urban planners should take into account the current impact of land use/land cover structure on temperature conditions when designing effective adaptation measures to mitigate urban heat load.

How to cite: Janků, Z., Dobrovolný, P., Geletič, J., and Lehnert, M.: The future changes in spatio-temporal distribution of urban heat load and factors that affect its variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-229, https://doi.org/10.5194/egusphere-egu24-229, 2024.

EGU24-423 | ECS | Orals | CL2.5

Combining crowdsourced weather data and the numerical urban climate model PALM – potentials and limitations 

Lara van der Linden, Patrick Hogan, Björn Maronga, Rowell Hagemann, and Benjamin Bechtel

The increasing intensity and frequency of heat waves combined with the urban heat island can create thermal conditions which are hazardous for human health. Numerical urban climate modelling can deliver the necessary information to plan resilient adaptation measures for healthy living conditions in cities under a future climate. However, as a model is always a simplification of the real world, model evaluation with measurement data is important. Traditional measurement networks and campaigns are very often not suitable in active planning processes. Crowdsourcing the required weather data offers the potential to easily evaluate model results at any given time.

To identify the potentials and limitations of this approach, the microscale urban climate model PALM is applied to simulate a hot day (Tmax > 30 °C) in a German city. The model results are evaluated with quality controlled crowdsourced air temperature data. The evaluation reveals a good model performance with a high coefficient of determination (R2) of 0.86 to 0.88 and a root mean squared error (RMSE) around 2 K. A temporal pattern in model accuracy is detected with an underestimation of night-time air temperatures. Due to the high number of available stations and the resulting representation of intra-urban temperature variations, the crowdsourced air temperature data proved valuable for model evaluation. Limitations for this approach arise from radiation errors leading to a reduced data quality. Furthermore, measurements from a single station are influenced by microscale and localscale conditions and therefore only the information derived from several stations can be used for evaluation.

How to cite: van der Linden, L., Hogan, P., Maronga, B., Hagemann, R., and Bechtel, B.: Combining crowdsourced weather data and the numerical urban climate model PALM – potentials and limitations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-423, https://doi.org/10.5194/egusphere-egu24-423, 2024.

Air and surface temperature are among the most important variables to study the urban climate and are closely linked with thermal comfort and human health. Despite their importance, for now only surface temperature can be estimated by remote sensing, which means that the spatial variability of urban air temperature data can only be studied with a dense set of weather stations, which are expensive and do not yet have a spatial resolution as good as remote sensing. Near-surface air exchanges heat mainly with the surface which suggests that their temperatures could be estimated by each other, but as air is a fluid and moves their relationship is complex, so this estimation cannot yet be done with enough precision. This study aims to help improve the estimation of air temperature with surface temperature using the concept of footprint/source areas, which are the average surface areas that air has most interacted with before reaching the sensor at a weather station. For that, footprint areas were approximated as circles around the weather station. Then, using Landsat 5 and 8 satellites data (which passes around 10 a.m. in local solar time), average surface temperatures at different radii around 51 weather stations at the Metropolitan Region of São Paulo, Brazil, were computed. Then, the Pearson Correlation Coefficient between air and surface temperature was computed for each radius, each weather station and different periods of the year, where the radius with maximum correlation would be an approximation of the true footprint area. The average surface temperature in this area is also a better value for estimating air temperature than the surface temperature in the original Landsat data (100 and 120 metters). 

How to cite: Lustosa, R. and Rocha, H.: Estimating air temperature based on satellite surface temperature in the Metropolitan Region of São Paulo, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-698, https://doi.org/10.5194/egusphere-egu24-698, 2024.

EGU24-1457 | ECS | Posters on site | CL2.5

Dense network of wet bulb globe temperature observations to assess the effect of diverse micro-environments on heat stress 

Ian Hellebosch, Sara Top, Steven Caluwaerts, Koen De Ridder, Raf Theunissen, and Clemens Mensink

There is an urgent need for governments to know which measures effectively decrease heat stress and how to adapt urban environments to keep our cities livable in a climate with more, and more extreme, heatwave days. To answer this question, an observational campaign took place in the urban fringe of Ghent (Belgium), a maritime mid-latitude city, during the summer of 2023, including a heatwave in June. This campaign employed diverse in-situ weather stations (2 Campbell stations, 2 Hobo devices and a station from the Flemish MOCCA and VLINDER networks) complemented by 16 AT-HTS01 devices, specifically designed to measure heat stress. Combined, the stations are equipped with black globe thermometers, anemometers, humidity sensors, short-wave radiation pyranometers and actively and passively ventilated air temperature sensors. Based on these variables the wet bulb globe temperature (WBGT) is computed and from this, the influence of different suburban micro-environments on heat stress is derived. In particular, the effects of the surface type, neighboring buildings, trees and forest patches on WBGT are investigated. Some air temperature sensors are installed in actively ventilated shields to detect air temperature differences in different forest patches excluding any radiation-induced measurement errors. Additionally, drone infrared measurements were conducted to estimate the surface temperature of the different surface types during the day and the night. A forest patch decreases the maximum air temperature during the heatwave to up to 1.5°C. At night, the unpaved surface decreases the globe temperature to up to 1.5°C compared to paved surfaces. During daytime shadow effects of buildings and trees have the largest impact on decreasing the globe temperature (by 10°C) and consequently strongly lowers the actual WBGT (up to 4°C). Future research will focus on validating meter-scale numerical models with these observations.

How to cite: Hellebosch, I., Top, S., Caluwaerts, S., De Ridder, K., Theunissen, R., and Mensink, C.: Dense network of wet bulb globe temperature observations to assess the effect of diverse micro-environments on heat stress, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1457, https://doi.org/10.5194/egusphere-egu24-1457, 2024.

EGU24-1643 | ECS | Orals | CL2.5

Quantifying the Effect of Urban Heat Advection using Crowd Weather Stations 

Jonas Kittner, Daniel Fenner, Matthias Demuzere, and Benjamin Bechtel

Detailed measurements are indispensable in order to understand small-scale urban climate effects. With professional weather stations (PWS) mostly being available outside of cities with few sites per city, alternative data sources such as crowd-sourced weather data have proven to be valuable. Often the Urban Heat Island (UHI) is studied under ideal calm conditions when its development is strongest. At the same time, it has been shown that wind leads to advection of urban air, impacting regions downwind of urban areas and within the city.

We aim to provide insights into the effects of Urban Heat Advection (UHA) in the Urban Canopy Layer (UCL). The metropolitan regions of Paris and Berlin were studied, using four years (2019 - 2022) of quality-controlled crowdsourced air-temperature data from thousands of privately-owned Crowd Weather Stations (CWS). Those data were combined with global ERA5-Land data to overcome gaps in rural CWS coverage and globally-available Local Climate Zone (LCZ) information.

It is shown that wind causes increased exposure to urban heat for areas located downwind of the city core, which was derived using a LCZ-weighted centroid detection. 

For all observed wind directions, classified by dynamically moving wind sectors, differences in spatial patterns were visible with the effect being strongest with regional wind speeds of 3 m·s−1. The results highlight the importance of considering the effects of UHA when studying the UHI to avoid underestimating the exposure to urban heat in downwind areas of the city. The results could be used as a starting point for coupling the conditions in the Atmospheric Boundary Layer with the resulting conditions in the UCL, utilizing a large database with crowdsourced CWS data.

How to cite: Kittner, J., Fenner, D., Demuzere, M., and Bechtel, B.: Quantifying the Effect of Urban Heat Advection using Crowd Weather Stations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1643, https://doi.org/10.5194/egusphere-egu24-1643, 2024.

EGU24-1788 | Posters on site | CL2.5

A Global Database of quality-controlled Crowd Weather Station Data 

Benjamin Bechtel, Jonas Kittner, Daniel Fenner, and Matthias Demuzere

Privately-owned weather stations, Crowd Weather Stations (CWS), offer high spatial and temporal density in many urban regions across the globe, and therefore have been used in a variety of urban climate studies, mostly focusing on single cities. One challenge in crowdsourcing CWS data lies in the fact that the link between measured atmospheric data and (historic-) metadata is often lost due to the limited metadata available from popular CWS networks. This poses challenges in retrieving and analyzing data, as, e.g., past changes in CWS location remain undetected, introducing incorrect data, thus reducing data integrity.

We developed an end-to-end workflow for consistently collecting and checking CWS (meta-)data in 257 areas worldwide, covering over 500 urban regions since 2019. The workflow automatically adds newly set-up CWS to the database, as well as consistently handling changes in CWS location. Until now, the database includes over 310,000 CWS with 7 Billion hourly observations of air temperature and relative humidity (mean, maximum, minimum). Over 65,000 changes in CWS location have been detected since 2019. This highlights the importance of continuous metadata updates for this dynamic data source, further enabling the use of the measurements for different applications. Within the database, CWS are linked to additional metadata, including a global digital elevation model, a global Local Climate Zones map, and the Global Human Settlement Layer Urban Center Database.

The database was developed using open data and open-source software, combining PostgreSQL, PostGIS, and Timescale, which allows us to manage billions of measurements efficiently. All air-temperature measurements are consistently and continuously quality controlled using the state-of-the-art open R-Package CrowdQC+. The result is a dataset of consistently-processed metadata and measurements with potential for global-scale (intra-)urban climate studies and in-depth city analyses.[MD1] [DF2] 

How to cite: Bechtel, B., Kittner, J., Fenner, D., and Demuzere, M.: A Global Database of quality-controlled Crowd Weather Station Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1788, https://doi.org/10.5194/egusphere-egu24-1788, 2024.

EGU24-1964 | ECS | Posters virtual | CL2.5

Establishment of Circular Open Data Ecosystems: Supporting the Transition to Urban Greening and Sustainability 

Anastasios Georgakopoulos, Aikaterini Karagiannopoulou, Chrysovalantis Tsiakos, and Angelos Amditis

As urban populations burgeon globally, the imperative to foster sustainable cities becomes increasingly pressing. One primary challenge in urban sustainability is the fragmented data silos within different stakeholders. Addressing these barriers, the key term of the Open Data Ecosystem (ODE) has started to gain a wider appreciation, as it emphasises the need to not only provide free and accessible data assets, but rather a circular, sustainable, demand-driven environment. Towards this perspective, the European-funded project Urban ReLeaf capitalised on the Data Landscape Playbook (DLP) methodology, launched by the Open Data Institute (ODI) to dismantle the data silos in six European cities, i.e., Athens (Greece), Dundee (Scotland), Cascais (Portugal), Mannheim (Germany), Riga (Latvia), and Utrecht (The Netherlands).

Four steps of DLP were adopted, called Plays, to examine the objectives of each city, identify the data owners and infrastructure, and assess the ethical context behind data accessibility. For the first play, a three-tier approach was established to (i) evaluate the initial objectives of the cities, (ii) transform them based on the latest perspectives, and (iii) correlate them with the project. Subsequently, the Data Ecosystem Mapping (DEM) was formulated and provided valuable information about the data assets, the data owners and the formal value exchanges between stakeholders that are generating jointly a data source. Continuing, we addressed key aspects related to the data itself. An early outcome of this process was that the majority of pilot cities chose to disseminate their data sources in open-access data repositories and machine-usable data formats. Unfortunately, most of the identified datasets were an outcome of individual data collection campaigns revealing any intention to continue.

Through the fourth step, we investigated the ethical content following FAIR guidelines. Each data source was classified according to ODI’s Data spectrum scheme (i.e., Closed, Shared, Open) and thus identified the tendency of the European cities towards open access policies. The latest was verified through the identification of the open-accessed data dashboards and licences. An exemption from the general adoption of the Creative Common (CC) licenses was Mannheim, which established the tailored dl-de-by-2.0 license of Germany. Finally, a preliminary review was applied towards the trustworthiness of the released data, investigating methodological procedures that safeguarded the inner trust of data, or the outer trust by the requested public’s opinion.

In conclusion, the integration of the ODI-DLP in urban contexts holds the promise of breaking down data silos, fostering circularity, collaboration, and propelling cities towards sustainability. By investigating the existing open data principles, and interoperable technologies that are used and engaging citizens, cities could harness the full potential of their data to inform policies and initiatives that enhance the Quality of Life (QoL) for residents and pave the way for a more sustainable urban future.

Acknowledgement: This research has been funded by the European Union’s Horizon Europe Research and Innovation Programme under Urban ReLeaf project (Grant Agreement No 101086638).

How to cite: Georgakopoulos, A., Karagiannopoulou, A., Tsiakos, C., and Amditis, A.: Establishment of Circular Open Data Ecosystems: Supporting the Transition to Urban Greening and Sustainability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1964, https://doi.org/10.5194/egusphere-egu24-1964, 2024.

EGU24-2159 | ECS | Orals | CL2.5

Assessing the quality of citizen-science rainfall data based on station setup 

Arjan Droste, Marchien Boonstra, Marie-Claire Ten Veldhuis, Marit Bogert, Marc Schleiss, and Sandra De Vries

The Delft Measures Rain Citizen-Science programme has been running for several years in the city of Delft, the Netherlands. Within this programme, interested citizens can apply to receive a low-cost Alecto WS5500 weather station, to measure local meteorological parameters in their own garden. Currently there are over 45 of these citizen-science weather stations spread across neighbourhoods in Delft, capturing rainfall variability in different urban microclimates. However, the scientific quality of these specific stations has never been tested, and from previous work we know that rigorous quality assurance is necessary in order to get meaningful (precipitation) data. Thus we have installed 8 Alecto stations in The Green Village outdoors urban climate field lab at the TU Delft. Stations have been explicitly installed in ways that a citizen might do: slightly tilted, next to a wall (simulating the limited open garden space of a Dutch urban residence), on top of a shed as well as free-standing. These different measurement setups, combined with a row of stations installed in the same way right next to one another, allow us to investigate the bias caused by less-than-ideal station installation, as well as systematic errors related to the tipping bucket mechanism and sensor drifts. Initial results show a general overestimation of the Alecto compared to reference stations and radar observations, and a discernible negative bias caused by sheltering effects of plants and, to a lesser extent by walls.

How to cite: Droste, A., Boonstra, M., Ten Veldhuis, M.-C., Bogert, M., Schleiss, M., and De Vries, S.: Assessing the quality of citizen-science rainfall data based on station setup, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2159, https://doi.org/10.5194/egusphere-egu24-2159, 2024.

EGU24-3171 | Orals | CL2.5

Serious game as a tool for understanding the need for adapting our neighbourhoods to climate change 

Magdalena Kuchcik, Agata Cieszewska, Joanna Adamczyk-Jabłońska, Joanna Dudek-Klimiuk, Renata Giedych, Krzysztof Klimaszewski, Marcin Łączyński, Gabriela Maksymiuk, Dorota Pusłowska-Tyszewska, and Piotr Wałdykowski

The strategic, serious games could be one of the most interesting and effective educational tools in climate change action methods. This is why interdisciplinary project Co-Adapt - Communities for Climate Change Action (NOR/IdeaLab/Co-Adapt/0002/2020-00; https://coadapt.pl/en)​ aims to develop an integration toolkit based on both board and  computer game to support resiliency and citizen engagement in city-communities, empowering them in responding to new climate change challenges with bottom-up involvement.

The game features simulations that allow local community to transform their neighborhoods into more resilient to the climate change. The game is adapted to local environmental and spatial conditions so people can play in a group on their real neighborhoods maps what stimulate higher motivation for participation in climate change transformation. The residents play together and they are forced to co-operate. They will explore various choices available for their neighborhoods (from wide, but limited and detailed range of solutions connected with green and blue infrastructure, renewable resources, climate-friendly changes of colors of facades and roofs etc.) and consequences (costs, savings, climatic benefits). The workshop toolkit integrates best practices collected from communities that are already involved in climate change actions in Norway, Denmark, France or USA and which were visited by project’ leaders.

The pilot board games were played October-November 2023 in five neighbourhoods in Warsaw diversified in relation to exposure to urban heat island, flood risk etc., urban structure and socioeconomic factors. They were carefully chosen after consultations with Warsaw City Council out of the most active local communities and on city-owned land. City ownership is crucial because at the end of the game each of the community will be able to implement some solutions from the game up to the sum of c. 6800 € (30 000 PLN). The residents could eg plant the trees, sow a flower meadow, create bioswale trough or start a small orchard.

Co-Adapt game is completely new idea of ​​implementing science into the behavior of local communities in order to arouse their will to act together, to improve their living environment, to adapt to climate change and to mitigate this change.  

 

How to cite: Kuchcik, M., Cieszewska, A., Adamczyk-Jabłońska, J., Dudek-Klimiuk, J., Giedych, R., Klimaszewski, K., Łączyński, M., Maksymiuk, G., Pusłowska-Tyszewska, D., and Wałdykowski, P.: Serious game as a tool for understanding the need for adapting our neighbourhoods to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3171, https://doi.org/10.5194/egusphere-egu24-3171, 2024.

EGU24-3181 | ECS | Posters on site | CL2.5

The cooling effect of a river as a contribution to climate change adaptation and resilience 

Kaja Czarnecka, Magdalena Kuchcik, and Agata Cieszewska

Due to climate change, adaptation strategies are being implemented all over the world, from the scale of the entire country to individual housing estates. The CoAdapt – Communities for Climate Change Action (NOR/IdeaLab/Co-Adapt/0002/2020-00) project documents the best nature-based solutions supporting adaptation to climate change and creates a database of good practices in neighbourhoods. One of the most effective examples is the use of blue infrastructure such as restoring rivers to the surface or thoughtful development of the immediate surroundings of the river. Therefore, to better understand the cooling effect of rivers, research was carried out in the Vistula River valley in Warsaw – the city where CoAdapt project was started. This study aims to investigate the differences in the thermal regime in the river valley and other parts of the city, and determine which elements of the immediate surroundings of the site impact the thermal environment the most.

The basis for the calculations was the air temperature sampled every 10 minutes by HOBO loggers at 2 m above the ground, collected in the years 2017-2022. The air temperature monitoring in the Vistula Valley was carried out on three stations: in the south and the downtown part on the left bank and the north on the right bank of the river. To present the thermal characteristics of the river and its cooling effect, these data were compared with the stations located in other parts of the city and characterized by different types of spatial development (e.g. Floor Area Ratio, Ratio of Biologically Vital Area, Sky View Factor). Moreover, based on 25 satellite thermal images from 2002-2018, the impact of the Vistula River on the incidence of the Cold Spot effect was analysed.

In this study, it was found that with increasing development density and a decrease in the share of biologically vital areas, the average daily air amplitude decreases. The northern and southern parts of the valley in Warsaw are characterized by similar thermal conditions. However, the middle one, located in the downtown area of the city, stands out significantly – it is warmer, and the Cold Spot effect occurs more often. Surrounded by highly heated artificial surfaces, the impact of the Vistula is more visible than in the case of green areas adjacent to the valley, although the range of impact is smaller due to the rapidly growing intensity of development in the city centre.

Getting acquainted with environmental data such as air and surface temperature and the good practices, then selecting diverse, effective methods based on blue and green infrastructure in neighbourhoods was one of the stages leading to the creation of the serious game – the main result of the CoAdapt project. Moreover, data related to the monitoring of the Vistula Valley were used to select neighbourhoods in Warsaw to conduct the CoAdapt workshops.

How to cite: Czarnecka, K., Kuchcik, M., and Cieszewska, A.: The cooling effect of a river as a contribution to climate change adaptation and resilience, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3181, https://doi.org/10.5194/egusphere-egu24-3181, 2024.

Over the last decade, numerous urban canyon schemes have been developed, aiming to reproduce the interactions between the urban surface and the atmosphere. They have either used a bulk approach, where the general urban surface characteristics are modified, or a layered approach, in which single or multiple canyon levels are adopted, taking into account the contributions of individual urban facets: such as roofs, walls, and floors. Bulk schemes have often been the preferred approach in numerical weather prediction and climate models for their cost-efficient way of representing key atmosphere-canopy interactions and other important urban characteristics.
TERRA_URB is one of these bulk urban canopy models (UCM), originally developed for the COSMO atmospheric model. It has recently been integrated into the Icosahedral Non-hydrostatic Weather and Climate Model (ICON). In this study, we extended the preliminary implementation in ICON with the capability of representing morphological and material properties of the urban surfaces as spatially varying (instead of constant) fields in order to better represent the variability of energy, moisture, radiation, and momentum fluxes between the canopy and the atmosphere across a city. The spatially varying properties were derived from the Ecoclimap Second Generation (ECOCLIMAP-SG) land cover dataset, which is the latest version of ECOCLIMAP, incorporating local climate zones with a relatively high resolution of 300 meters. To assess the performance of ICON with TERRA_URB, we simulated the hot and dry summer period of mid-July to mid-August 2022 over the cities of Zurich and Basel in three configurations, (i) without TERRA_URB, (ii) with TERRA_URB in the preliminary and (iii) in the enhanced version. The three versions were compared against each other and evaluated against different types of observations, including standard weather stations, temperature sensor networks, and flux tower measurements.
Overall, our results reinforce the importance of incorporating accurate characterization of urban morphological and material properties into UCMs. Going forward, we will further improve these urban parameters by incorporating local datasets not accessible to a global product like ECOCLIMAP-SG. This will include, among others, detailed 3D building information, building material properties, surface reflectance (albedo) properties derived from remote sensing, and anthropogenic heat fluxes estimated from a detailed CO2 emission inventory. Our ultimate goal is to develop a comprehensive ICON-based urban modeling system that can be run with either a bulk UCM or the multilayer UCM BEP-Tree, previously developed in our group for COSMO. This novel modeling system will allow us to study the feedback between vegetation, carbon, energy, and water cycles in the urban environment.

How to cite: Dönmez, K., Emmenegger, L., and Brunner, D.: Urban Climate and CO2 Simulations with the New Atmospheric Model ICON-ART Accounting for Spatially Varying Urban Morphology and Material Properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3375, https://doi.org/10.5194/egusphere-egu24-3375, 2024.

EGU24-3829 | ECS | Posters on site | CL2.5 | Highlight

Fast analysis of urban meteorological observations with the user-friendly MetObs-toolkit 

Thomas Vergauwen, Sara Top, Amber Jacobs, Andrei Covaci, Wout Dewettinck, Kobe Vandelanotte, Ian Hellebosch, and Steven Caluwaerts

Working with and analysing data from non-traditional measurement networks, such as urban climate networks, can be challenging and time consuming. After undertaking an observational campaign, researchers often face the issue of missing data due to technical problems such as power cuts or data communication issues. Additionally, data from low-cost networks or crowdsourced data need quality control to avoid the inclusion of measurement errors and biases, which often leads to additional gaps in the time series. Moreover, data storage formats and temporal measurement frequencies are often not consistent or synchronised when comparing data of different measurement networks. MetObs, an open-source Python toolkit, was developed to overcome these issues and fully exploits such valuable datasets. MetObs aims to provide a framework for the entire flow from raw sensor data to a dedicated analysis, with the possibility to apply it to various types of non-traditional networks without any formatting issues. To obtain a clean dataset, the time resolution is firstly resampled to the desired resolution, followed by identifying erroneous and missing records. Finally, missing records are filled in with the most suitable or preferred gap-filling method. Dedicated software for quality control, such as TITAN and CrowdQC+, already existed prior to the development of MetObs and are therefore implemented in the toolkit instead of being reinvented. The toolkit makes it moreover possible to generate analytics with the possibility to incorporate geographical data and create various graphics for the analysis of the meteorological measurements. MetObs was developed in such a way that people without a coding background can utilise it to get insight into their own meteorological measurements by following examples and using tutorials. At the same time, it allows more experienced data scientists to tweak the functionalities in such a way that the toolkit provides a pipeline for their dedicated use case.

How to cite: Vergauwen, T., Top, S., Jacobs, A., Covaci, A., Dewettinck, W., Vandelanotte, K., Hellebosch, I., and Caluwaerts, S.: Fast analysis of urban meteorological observations with the user-friendly MetObs-toolkit, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3829, https://doi.org/10.5194/egusphere-egu24-3829, 2024.

The urban expansion-induced heat can exacerbate heat stress for urban dwellers, especially during heat waves. The urban parameterization within the Community Land Model version 5 (CLM5) was modified incorporating the local climate zones (LCZs) framework, named CLM5-LCZs, to simulate the urban climate of cities in eastern China. The results exhibited that daytime and nighttime canopy urban heat island intensity (CUHII) were highest in the Compact Low Rise (LCZ3) and the Compact High Rise (LCZ1) areas respectively, while surface urban heat island intensity (SUHII) peaked in the Large Low Rise (LCZ8) and the Compact High Rise (LCZ1) areas during daytime and nighttime respectively. Urban dwellers were easier exposed to serious heat environment in LCZ3 and LCZ1 areas over the north subtropical climate zone. Contrasts of CUHII and SUHII among different urban classes could exceed 1.7 °C and 5.4°C. The intra-urban heterogeneity may alter the dominant factors controlling SUHII, which were also modulated by local climate and HW intensity. Unlike other controlling factors, the impact of local climate on the contribution from the urban-rural contrast of convection efficiency was larger than urban features. Overall, CLM5-LCZs displayed potential of implementing detailed simulations for inter- and intra-city UHIs at a larger scale, and enhancing the capabilities in modelling urban climate and exploring the causes and controls of UHIs.

How to cite: Zhang, N.: Modeling Urban Climate  in East China with CLM5 coupling Local Climate Zone Schemes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4061, https://doi.org/10.5194/egusphere-egu24-4061, 2024.

EGU24-4377 | ECS | Orals | CL2.5

Detection of urban effects on precipitation in the Seoul metropolitan area, South Korea 

Seong-Ho Hong, Han-Gyul Jin, and Jong-Jin Baik

With growing urban population and expanding urban areas, the importance of understanding urban effects on precipitation keeps increasing. This study attempts to detect urban effects on precipitation in the Seoul Metropolitan Area (SMA), South Korea by analyzing hourly rain gauge data during 2005–2020. Precipitation events are categorized according to 850-hPa wind directions, and the precipitation increases from the upwind to downwind regions are examined for different duration and intensity classes of precipitation events. The downwind precipitation increase is largest in summer (39%), especially in August (64%). The August precipitation is analyzed in detail. Precipitation statistically significantly increases in Seoul for weak winds and 25–50 km downwind of the center of Seoul for westerly winds, and the precipitation increases are largest in the afternoon. For the precipitation increases, the increases in frequency and intensity of precipitation events are responsible. Short-duration and heavy precipitation events associated with small-sized precipitation systems initiated within the SMA are mainly responsible for the precipitation increases. The downwind precipitation increase also occurs for southwesterly, southerly, and southeasterly winds, but the increases are associated with large-sized precipitation systems.

How to cite: Hong, S.-H., Jin, H.-G., and Baik, J.-J.: Detection of urban effects on precipitation in the Seoul metropolitan area, South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4377, https://doi.org/10.5194/egusphere-egu24-4377, 2024.

EGU24-4394 | Orals | CL2.5

Investigation of diurnal/nocturnal and seasonal effect of blue and green features on thermal exposure in Czech cities 

Michal Lehnert, Veronika Květoňová, Alena Koukalová, Martin Jurek, and Jan Geletič

Increasing intensity, frequency, and duration of hot extremes has been one of the most pronounced aspects of climate change in Central Europe. At the same time cities and towns, where the majority of the population live, are affected by added urban heat load. Such circumstances require effective adaptation of the municipalities to heat extremes. On that account, the influence of blue and green features and various surfaces on thermal exposure, represented by MRT and physiological indices of Universal Thermal Climate Index (UTCI) and Physiological Equivalent Temperature (PET), has been investigated over a period of five years in a set of short-term measurement campaigns in several Czech cities. The results showed that trees in open public areas of Czech cities lead to a substantial decrease of thermal exposure during the daytime whereas it might slightly increase on-site thermal exposure during the night. Maintained turfs in open areas characteristically reduce thermal exposure only slightly, depending on grass height and density and soil properties. Similarly, the cooling or warming effect of blue elements differs with their character. The effect of fountains and misting systems in open areas of thermal exposure is usually hardly detectable; however, ground-based fountains moisturising the pavement seem efficient. Further results from a recently launched measurement winter season campaign are expected soon. 

How to cite: Lehnert, M., Květoňová, V., Koukalová, A., Jurek, M., and Geletič, J.: Investigation of diurnal/nocturnal and seasonal effect of blue and green features on thermal exposure in Czech cities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4394, https://doi.org/10.5194/egusphere-egu24-4394, 2024.

EGU24-4737 | ECS | Orals | CL2.5

GreenRoofNet: Integrating High-Resolution Aerial Imagery with Deep Learning for Efficient Green Roof Monitoring 

Md Abdul Halim, Wenxi Liao, Imrul Kayes, Jennifer Drake, Liat Margolis, Debra Wunch, and Sean Thomas

Background: Urban environments are increasingly recognized as both significant contributors to and primary victims of climate change. Buildings in urban settings are responsible for approximately 33% of global greenhouse gas emissions, while cities themselves are often situated on fertile land with high carbon sequestration potential. To mitigate these impacts on climate, adopting nature-based sustainable technologies is essential for developing climate-smart cities. Among these, green roofs have emerged as a critical solution for climate change mitigation.

Significance of Green Roofs: Originally designed for stormwater management, green roofs have demonstrated effectiveness in various environmental aspects. They mitigate urban heat island effects, reduce sound and air pollution, lower building energy consumption, enhance biodiversity, and have the potential for carbon sequestration. Recognizing these benefits, Toronto implemented a by-law in 2009 mandating green roofs on all new large buildings with flat roofs larger than 2,000 m², complemented by incentives for the private sector. Despite the increase in green roof installations, there is a lack of efficient monitoring, leading to concerns about maintenance and compliance.

Challenges in Monitoring: The absence of an efficient green-roof monitoring system is a widespread problem. Traditional monitoring techniques face limitations, including on-site inspections and satellite imagery analysis. High-resolution satellite data are costly, while freely available images (e.g., from Landsat) lack the necessary resolution for small-scale green roof analysis. This gap highlights the need for an efficient, automated, and accurate green roof monitoring system.

Methods: To address this need, we developed an automated, deep-learning-based toolbox (GreenRoofNet) for monitoring green roofs using high-resolution (8 cm) orthoimages collected by the City of Toronto for other purposes. We segmented these images into 299x299 pixel tiles with a 20% overlap to ensure comprehensive coverage, particularly of smaller green roofs. Using 500 labeled images for training and validation, and the remainder for testing, we employed the Inception v4 architecture in TensorFlow. This deep convolutional network model was selected for its ability to extract detailed features crucial for accurate green roof detection. The model training involved a cross-entropy loss function, an Adam optimizer, and a dynamic learning rate, with a 50-epoch limit and early stopping to prevent overfitting. Post-processing of tiles was conducted using maximum confidence scores to amalgamate overlapping detections.

Results and Implications: The model has successfully identified green roofs with approximately 95% accuracy and detected their boundaries with about 90% precision. Preliminary analysis reveals that a segment of Toronto's green roofs is undergoing degradation, whereas a substantial proportion remains in good condition, with a smaller segment being currently undetectable or missing. Further testing is underway, with plans to package the results of this project in a web application featuring an open-source map. This tool will play a pivotal role in assessing the effectiveness of the green roof by-law, aiding in the verification of subsidies, guiding the maintenance of green roofs, and facilitating the estimation of their environmental benefits.

How to cite: Halim, M. A., Liao, W., Kayes, I., Drake, J., Margolis, L., Wunch, D., and Thomas, S.: GreenRoofNet: Integrating High-Resolution Aerial Imagery with Deep Learning for Efficient Green Roof Monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4737, https://doi.org/10.5194/egusphere-egu24-4737, 2024.

EGU24-5058 | Posters on site | CL2.5

The development of the Koreans’ climatic index for tourism (KCIT) 

Sookuk Park, Sangman Jo, Yuri Choi, and Jeonghyeon Moon

To develop the Koreans’ climatic index for tourism (KCIT) in the four tourism and recreation types (cultural tourism, beach walking, Oreum/light climbing, and Olle/tracking), this study conducted comprehensive microclimatic data collection and surveys throughout the four seasons of 2022-2023 in Jeju, Republic of Korea. The research involved expert opinions and insights from 26 experts and 1,860 tourists in cultural tourism, 15 and 511 in beach walking, 28 and 603 in Oreum, and 14 and 234 in Olle. The collected microclimatic data included air temperature, relative humidity, wind speed, and shortwave and longwave radiation, concurrently gathered with tourist surveys. The KCIT comprises 7 scales, ranging from very poor to ideal, and is composed of three critical aspects: thermal, aesthetic, and physical. The thermal aspect analyzed human thermal sensation across 9 ASHRAE scales, from very hot to very cold, utilizing physiological equivalent temperature. It revealed that a consistent optimal range was from neutral to slightly cool across the four tourism and recreation types. The possible range of all tourism and recreation was from hot to cold, and the difficult range was very hot and very cold. The aesthetic aspect evaluated cloud cover, establishing an optimal range of clear or less cloudy conditions (30-50%) for all tourism and recreation types, while beach walking displayed a preference for clearer skies. Wind speed, a physical aspect, indicated an optimal range of a gentle breeze, 1.4-3.4 ms-1, with variations observed across tourism and recreation types. The possible range was from 0 to 7.5 ms-1 in cultural tourism and from 0 to 5.5 ms-1 in the others. The difficult range was from 7.5 ms-1 in cultural tourism and 5.6 ms-1 in the others. Precipitation, another physical aspect, revealed optimal, possible, and difficult ranges of 0 mmhr-1, 0.1-5.0 mmhr-1, and more than 5.1 mmhr-1, respectively. The study highlights the versatility of the KCIT scale, offering a user-friendly tool for tourists and tour companies. Additionally, it presents valuable insights for local governments in shaping future tourism plans. This ongoing research is set to continue exploring other tourism and recreation aspects in 2024.

How to cite: Park, S., Jo, S., Choi, Y., and Moon, J.: The development of the Koreans’ climatic index for tourism (KCIT), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5058, https://doi.org/10.5194/egusphere-egu24-5058, 2024.

EGU24-5096 | ECS | Orals | CL2.5

Which dataset should be used to get building footprint and height worldwide ? 

Jérémy Bernard, Jean Wurtz, Valéry Masson, and Erwan Bocher

The building size and distribution has a big impact on atmospheric properties such as wind speed, air temperature, air pollution, etc. This impact may be quite different depending on the lattitude and the climate where a city is located. Nowadays, climate simulations performed over city territories consider average building properties (building height, distance between buildings, etc.) over one to several hundred meters grid cells. However, it is difficult to find a homogeneous building dataset that would be used over the world to observe the effect of a same building organisation between two regions of the world located at a different lattitude or in a different climate zone.

This work is dedicated to the evaluation of several building datasets (OpenStreetMap, BING, Global Human Settlement, etc.) that are available over several continents. The building footprint and height of each dataset are compared to local reference data for different parts of the world. The objective is to identify which dataset would be preferable to use depending on its quality and availability.

How to cite: Bernard, J., Wurtz, J., Masson, V., and Bocher, E.: Which dataset should be used to get building footprint and height worldwide ?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5096, https://doi.org/10.5194/egusphere-egu24-5096, 2024.

EGU24-5167 | ECS | Posters on site | CL2.5

Assessment of the optimal initial and boundary conditions for the LES-based model PALM 

Jelena Radovic, Michal Belda, Jaroslav Resler, Kryštof Eben, Martin Bureš, Jan Geletič, Pavel Krč, Hynek Řezíček, and Vladimír Fuka

Proper assessment of urban atmosphere and climate by physics-based Computational Fluid Dynamic (CFD) models has been a pressing topic in the urban modeling community. Due to the ever-increasing number of city dwellers, continuous urbanization, and consequent modification of the urban atmosphere, this topic is and will remain popular in the future. The most advanced microscale models widely used for urban boundary layer studies, typically based on the Large Eddy Simulation (LES) principle, are currently the ones whose higher accuracy and ability to capture physical processes in the urban atmosphere have been well-validated. However, to fully assess their reliability, the necessity of testing the influence of the initial and boundary conditions (IBC) on the model outputs is a crucial issue that needs to be addressed.
Four different three-day episodes throughout the year 2019 have been modeled using the PALM model system for experiment purposes. Two of the episodes encompass extreme weather events (e.i., a heatwave and a bad air quality period), and the other two episodes are chosen to represent non-extreme and usual weather conditions. In this experiment, an ensemble of 16 different WRF model realizations differing in parameterization setup is created and it serves as a source of IBC for the PALM model simulations. Firstly, a method for optimal WRF ensemble member selection has been developed, based on which subgroup of the ensemble members has been selected for driving the microscale model. The microscale model 8 x 8 km simulation domain is located in the realistic urban area in the city of Prague,  its horizontal resolution is 10m. Altogether, 14 simulations have been performed with identical configurations except for the driving conditions. The PALM model outputs have been evaluated against radio-soundings, and compared to the WRF model driving conditions, both quantitatively and qualitatively. 
This study shows that PALM model outputs are largely influenced by the imposed driving conditions and that the majority of errors originate from the mesoscale model, and propagate into the microscale simulation. The sensitivity of the microscale model on different IBCs is significant, but the PALM model is capable of attenuating the errors coming from the WRF model. Finally, the experiment stresses the importance of high-quality driving data and shows the complexity of the process of acquiring such data.

How to cite: Radovic, J., Belda, M., Resler, J., Eben, K., Bureš, M., Geletič, J., Krč, P., Řezíček, H., and Fuka, V.: Assessment of the optimal initial and boundary conditions for the LES-based model PALM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5167, https://doi.org/10.5194/egusphere-egu24-5167, 2024.

This study investigates the interactions between urban heat islands (UHIs) and heat waves in Seoul, South Korea, using 25-year (1997–2021) observations. Under heat waves, South Korea is under strong influence of an anomalous 500-hPa anticyclonic high and the expanded Tibetan high. The urban heat island intensity (UHII) calculated as the difference between the urban-station average and rural-station average of the daily minimum (maximum) 2-m temperature increases by 0.53 °C (0.20 °C) under heat waves, indicating synergistic interactions in both nighttime and daytime. UHII substantially varies within heat waves. UHII tends to increase under stronger heat waves and has statistically significant negative correlation with relative humidity and cloud fraction. Among heat wave days, strong (weak) UHI days with UHII larger (smaller) than its 90th (10th) percentile are selected, and these days well represent positive (negative) interaction cases. The strong UHI days exhibit relatively hot, calm, dry, and clear weather conditions with relatively strong subsidence compared to the weak UHI days. The dominant synoptic patterns on the strong and weak UHI days are the Pacific-Japan (PJ) pattern and the expanded western North Pacific subtropical high (WNPSH), respectively. The strong UHI days are frequent in recent years.

How to cite: Park, K., Jin, H.-G., and Baik, J.-J.: Contrasting interactions between urban heat islands and heat waves in Seoul, South Korea, and their associations with synoptic patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5568, https://doi.org/10.5194/egusphere-egu24-5568, 2024.

EGU24-6178 | ECS | Orals | CL2.5

Sensitivity of the high-resolution regional climate model AROME to urban sprawl over Paris region 

Léa Corneille, Aude Lemonsu, Tiago Machado, and Vincent Viguié

Cities, as cradles of population and economic activities, constitute a crucial issue in the current environmental challenges. Their organisation is enduring major changes and the issues surrounding spatial planning are of growing interest in a context of climate change, since cities are particularly vulnerable to extreme events.

The evaluation of the climate change impacts requires to refine the climate projections provided by global and regional climate models down to a finer spatial scale more adapted to the city study. Besides their fine resolution, these models may include a dedicated surface model to represent explicitly the urban areas and the physical processes involved.

The CP-RCM (Convection-Permitting Regional Climate Model) AROME is coupled to the TEB urban canopy model with an horizontal resolution of 2.5 km, and uses the ECOCLIMAP land use and land cover database to characterise the surface properties. It is applied over the Paris region for a past period, forced by the ERA5 reanalysis, in order to assess local impacts of climate change.

Nonetheless, the land use map, used by the CP-RCM AROME and based on data from the 1990s without evolution in time, can be a limit to the realism of climate simulations. The expansion incurred by cities until the current period is not represented, nor the future dynamics. 

This study compares different climate simulations run with past, present and future land use maps over Paris region with the aim to quantify and analyse the impact of land use changes on the regional climate, as well as to explore the consequences in terms of population exposure to high heat conditions.

How to cite: Corneille, L., Lemonsu, A., Machado, T., and Viguié, V.: Sensitivity of the high-resolution regional climate model AROME to urban sprawl over Paris region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6178, https://doi.org/10.5194/egusphere-egu24-6178, 2024.

EGU24-6183 | ECS | Orals | CL2.5

Explicit representation of cities in the ORCHIDEE land surface model 

Morgane Lalonde, Ludovic Oudin, Agnès Ducharne, Sophie Bastin, and Pedro Arboleda-Obando

Cities alter the interactions between the surface and the atmosphere by modifying energy and water budgets. This is caused by the low albedo of urban environments, its high thermal conductivity, the increased surface roughness, and by greater surface imperviousness. Since the beginning of the 21st century, advances in high-performance computing allowed steady refinement of the numerical grids of climate models at the kilometer scale. At this resolution, representing the urban environment explicitly is necessary, as simplifying it to bare soil no longer suffices for accurate energy and water budget assessments and satisfies e.g. the representation of heat waves or urban runoff. In the ORCHIDEE model of the IPSL, cities are currently represented as bare soil, which fails to account for specific urban processes. To enhance ORCHIDEE's performance and study the impacts of specific urban processes on energy and water fluxes, an urban land cover was added to the existing land cover classes taken into account by the model. For this urban class, we prescribed specific parameters for soil imperviousness (though hydraulic conductivity), surface roughness, albedo, and thermal conductivity. All those parameters are cell-dependent, i.e. they account for the diversity of urban environments and cities as characterized by the WUDAPT database (Ching et al., 2018). By comparing model simulations with and without the urban module, we assess the sensitivity of simulated turbulent fluxes, infiltration, soil moisture, runoff, drainage, temperature, and compare them to available observations over France.

How to cite: Lalonde, M., Oudin, L., Ducharne, A., Bastin, S., and Arboleda-Obando, P.: Explicit representation of cities in the ORCHIDEE land surface model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6183, https://doi.org/10.5194/egusphere-egu24-6183, 2024.

Urban Heat Islands (UHIs) represent a climatic consequence of urbanization, leading to elevated temperatures within cities compared to surrounding rural and suburban areas. Addressing this human-induced phenomenon demands effective mitigation strategies. This study quantifies the UHI in the Kansas City Metropolitan Areas (KCMA) in the United States and investigates the potential of albedo modification, particularly through the cool roof implementation, as a means to mitigate UHI effects within the KCMA.

Utilizing the Weather Research and Forecasting (WRF) model, we first designed a suite of high-resolution simulations, examined UHI dynamics during a heatwave event across various scenarios within the KCMA, and determined the effectiveness of mitigation strategies in reducing temperatures within the KCMA. Specifically, we simulated two cool roof scenarios: one representing "newly installed" cool roofs with an albedo of 0.8 and another reflecting "aged" cool roofs with an albedo of 0.5. Our findings reveal that cool roof materials significantly mitigated surface UHI effects during evenings, delaying the onset of UHI effects until later in the day. Moreover, our study showcases the more profound impact of cool roofs on surface skin temperature, influencing the surface energy balance by altering sensible and ground storage heat fluxes and the planetary boundary layer.

Leveraging numerical modeling, we led and launched an Urban Heat Island Mapping Campaign in Kansas City. It is a volunteer-based community citizen science field campaign that builds upon local partnerships among academia, local government agencies, non-profits, and private sectors. This campaign engages Kansas City's local residents in a scientific study to map and understand how heat is distributed in the communities and the factors affecting the uneven distribution of heat. It raises awareness about the adverse impacts of extreme heat and excessive urban heat and presents actionable measures for urban planners and policymakers to address heat-related challenges in metropolitan areas.

How to cite: Sun, F.: Urban Heat and Mitigation Potential in the Kansas City Metropolitan Area: Insights from Integrated Numerical Modeling and Heat Mapping, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6510, https://doi.org/10.5194/egusphere-egu24-6510, 2024.

EGU24-6559 | Posters virtual | CL2.5

Compound hot extremes at an urban site based on climatic and bioclimatic indices  

Dimitra Founda, Fragiskos Pierros, and George Katavoutas

Over the past decades, extreme weather phenomena like hot extremes and heat waves (HWs) stand out as a major threat for humans and ecosystems. Compound extremes are understood as simultaneous, concurrent or sequential extreme events, taking place at a single or different locations. Compound extreme events may exacerbate the risk and increase associated adverse impacts, compared to individual events.

In the study, we examined the occurrence of compound hot extremes at an urban site of the eastern Mediterranean over a century-long period, using the historical climatic records of the National Observatory of Athens (NOA, 1897-2023). Compound hot extremes are defined as concurrent daytime and nighttime hot extremes, namely cases when both, daily maximum (Tmax) and daily minimum (Tmin) air temperatures are above a predefined threshold value. The threshold values for Tmax and Tmin were set equal to 36.7 oC and 25.9 oC respectively, corresponding to the 90th percentile of the summer Tmax and Tmin distributions at NOA, over the reference period 1981-2010. Likewise, we examined compound heat waves, defined as sequences of at least 3 consecutive days when both Tmax and Tmin exceed the predefined thresholds. Analysis has shown that 60% of the total number of compound hot extremes and compound heat waves in Athens (NOA) was observed from 2000 onwards. Besides, 57% of the daytime HWs over the whole study period constitute also compound HWs, while this percentage increases to 72% after the 2000s, indicating an increase in nighttime HWs, very likely related to the urban heat island effect. 

In addition to the hot extremes based on air temperature, we have also estimated compound daytime and nighttime extremes related to human thermal comfort, using the bioclimatic index UTCI (Universal Thermal Climate Index), accounting also for relative humidity, solar radiation and wind speed conditions. Compound hot extremes based on UTCI were defined as the cases when the daily maximum UTCI value  was above the index threshold indicating ‘at least very strong heat stress’ (UTCI > 38), and simultaneously, the daily minimum UTCI value was above the index threshold indicating ‘at least moderate heat stress’ conditions (UTCI > 26). The analysis detected 45 compound hot extremes based on UTCI from 1960-2023, with 34 of them occurring after the 2000s, suggesting a dramatic increase in the frequency of cases with heat-related thermal discomfort throughout the whole day and night.  The higher frequency of compound hot events was observed during the extreme years 2007, 2021 and 2023.

 

How to cite: Founda, D., Pierros, F., and Katavoutas, G.: Compound hot extremes at an urban site based on climatic and bioclimatic indices , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6559, https://doi.org/10.5194/egusphere-egu24-6559, 2024.

EGU24-6988 | ECS | Posters on site | CL2.5

Synergistic effects between urban heat island and heat waves in China 

Zitong Shi

Under the background of climate change and fast urbanization, climate extremes such as heat waves tend to be more frequent, more severe, and longer-lasting. Cities face a greater risk of heat waves due to population growth, industry concentration, and the superposition of their unique climate effects. Quantitative analysis of the combined effects of regional-scale heat waves and local-scale urban heat islands is important for urban adaptation to climate change and for urban disaster prevention and mitigation. On one hand, urban expansion, causing reduced evapotranspiration and weakened wind speed that normally cools the lower atmosphere by turbulent heat loss and cooled air advection, led to magnified heat extremes. On the other hand, synergistic effects between urban heat island and heat waves were found in most cities in China. Given this synergistic interaction between urban heat islands and heat waves, collaborative efforts will be necessary to implement climate adaptation and mitigation strategies aimed at reducing the serious heat-related health risks faced by urban residents.

How to cite: Shi, Z.: Synergistic effects between urban heat island and heat waves in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6988, https://doi.org/10.5194/egusphere-egu24-6988, 2024.

EGU24-7058 | ECS | Orals | CL2.5

Assessing urban heat mitigation strategies in Singapore with a Digital Urban Climate Twin (DUCT) 

Minn Lin Wong, Ander Zozaya, and Kristina Orehounig

Addressing the urban heat island effect requires informed and strategic planning of measures to mitigate urban heating. This is particularly important for highly urbanized and densely populated cities in the tropics, such as Singapore, which experience high levels of thermal discomfort due to urban heat island effect, and is further intensified by global warming. To assess the impact and effectiveness of different heat mitigation measures, we utilize a Digital Urban Climate Twin (DUCT) model of Singapore. The DUCT integrates the Weather and Research Forecasting model and Building Energy Model (WRF/BEM), with an added modification to account for near-surface anthropogenic heat sources such as power plants and traffic emissions. Next to these models the DUCT also integrates various data sources such as weather conditions, landcover, buildings, traffic etc. to describe the thermal behaviour of the city.

In this study, we use the DUCT to conduct a comprehensive testing of the sensitivity of urban temperatures to various heat mitigation measures such as increasing urban greenery, changing urban morphology and improvements in building efficiencies and traffic. Preliminary results indicate that designating forest land use and incorporating green areas are the most effective in reducing local and surrounding temperatures. This is followed by increasing the urban vegetation fraction in the pre-existing urban landscape, increase in electric vehicle usage, and improvements in building energy efficiencies, which show a more limited impact on temperatures. This work aims to highlight the capabilities of the DUCT as a versatile tool for planning agencies and policy makers to test the effectiveness of various policies and guide strategic planning for the management of urban heat.

How to cite: Wong, M. L., Zozaya, A., and Orehounig, K.: Assessing urban heat mitigation strategies in Singapore with a Digital Urban Climate Twin (DUCT), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7058, https://doi.org/10.5194/egusphere-egu24-7058, 2024.

Increasing human activities and urbanization have posed huge challenges to the urban climate, such as the urban heat island effect, which makes air temperature in urban areas higher than that in suburban areas. Meanwhile, the urban heat island intensity (UHII) suffers impacts from the exacerbation of observed extreme heat events, but how extreme heat events affect UHII in different subdivided urban spaces remains unclear. In this paper, we attempt to address the impact of extreme heat days and nights on urban heat environment from the perspective of local climate zones (LCZs). Firstly, we propose a framework for LCZ classification for higher precision LCZ mapping over the Guanzhong Plain urban agglomeration in China. Secondly, to select extreme heat days and nights based on six extreme temperature indices (TXx, TNx, TX90p, TN90p, SU25 and TR20), the daily maximum, minimum and average seamless 1-km air temperatures are estimated using the random forest method for the period from 2000 to 2020. Finally, combining the LCZ map and gridded temperature product, we analyze variance in air temperature and UHII among different LCZs at daytime and nighttime, as well as the influence of extreme heat conditions on air temperature and UHII in different LCZs.

Our results indicate that the air temperature difference within LCZs is greater under extreme heat conditions compared against that under non-extreme conditions. Meanwhile, extreme heat conditions aggravate the urban heat risks at daytime, which is manifested in the following two aspects: (1) the temperature difference within LCZs on extreme heat days is greater than that on extreme heat nights; and (2) UHII at nighttime is stronger than that at daytime in most LCZs under non-extreme conditions, but under extreme heat conditions, it is the opposite. In addition, although the rank of UHII in different LCZs varies due to differences in time and definition of extreme heat days and nights, LCZ 6a (agricultural greenhouse) stands out for suffering the highest UHII under all conditions (different extreme temperature indices, on days and nights), to which particular attention should be paid. Our results could be contributed to conducting mitigation measures of urban heat risks and providing more explicit guidance to policymakers and urban planners.

How to cite: Wang, B., Gao, M., and Li, Z.: Impacts of extreme heat days and nights on urban heat environment: a perspective of local climate zones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7102, https://doi.org/10.5194/egusphere-egu24-7102, 2024.

EGU24-7195 | ECS | Orals | CL2.5 | Highlight

Urban heat trends across global cities 

Marzie Naserikia, Melissa Hart, Negin Nazarian, Panagiotis Sismanidis, Jonas Kittner, and Benjamin Bechtel

Urban heat is characterised by elevated temperatures in cities, resulting not only from global climate change but also from urban development and human activities. Previous research on urban heat has predominantly relied on satellite-derived land surface temperature (LST) data to investigate the changes in near-surface thermal environments. However, the applicability of LST for examining the temporal variation of air temperature is still not well understood. Using crowdsourced air temperature observations and satellite imagery, we explore the temporal variation of air temperature and its relationship with LST in more than 50 populated cities worldwide. Results show that city-average air temperature values are highly correlated with LST. However, the intensity of this correlation differs by season, day/night cycle, and is further influenced by background climate. Using satellite LST data, we expanded our analysis to include over 1500 urban areas and evaluated temperature changes in the past two decades. We observed a general trend of increasing temperatures in cities globally, although the rates of warming vary. The highest rate of temperature change was found in cold climate cities, with a more rapid increase during winter days. These cities are predominantly located in Eastern Europe, extending into parts of Western Asia. These findings provide new insights into the application of satellite-based LST for predicting future air temperature changes and identifying areas most vulnerable to urban overheating.

How to cite: Naserikia, M., Hart, M., Nazarian, N., Sismanidis, P., Kittner, J., and Bechtel, B.: Urban heat trends across global cities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7195, https://doi.org/10.5194/egusphere-egu24-7195, 2024.

EGU24-8061 | ECS | Orals | CL2.5

Urban canopy parameters and local climate zones over Europe using OpenStreetMap data 

Jean Wurtz, Jeremy Bernard, Valery Masson, and Bocher Erwan

Climate modelling needs to have accurate informations about topography, type of land and land-use, size and type of wind or radiative obstacles such as trees or buildings. Explicits climate models solves heat and mass equations for each individual surfaces but they cannot be applied at regional scale for long time periods due to computational limitations. Parameterized climate models can overpass this limitations considering that within a given grid cell (being from one to several hundred meters wide), the obstacles and lands follow a given setting (e.g. street canyon for cities, with or without a garden). The heat and mass balances are applied for each of the grid cells using urban canopy parameters summarizing the main relevant parameters describing an area (e.g. mean building height, canyon aspect ratio, building fraction, fraction of road, building type and use, etc.). However, there is currently no datasets over Europe that would accurately describe all these informations.

OpenStreetMap (OSM) is a free, open geographic database updated and maintained by a community of volunteers via open collaboration. It contains most of the informations needed by climate models. It can cover any part of the world and is particularly well fullfilled for the European continent. One of its limitation is the lack of building height information. GeoClimate is a tool that calculates urban canopy and land cover parameters as well as Local Climate Zones (LCZ). GeoClimate uses vector data such as the ones available through the OSM project and uses machine learning algorithm to estimate the height of building missing such information. GeoClimate has recently used the OSM data to calculate the needed informations needed by parameterized climate models such as SURFEX-MesoNH or WRF over Europe. The presentation will describe the way GeoClimate works and will show some of the results of the resulting dataset.

How to cite: Wurtz, J., Bernard, J., Masson, V., and Erwan, B.: Urban canopy parameters and local climate zones over Europe using OpenStreetMap data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8061, https://doi.org/10.5194/egusphere-egu24-8061, 2024.

EGU24-8258 | ECS | Posters on site | CL2.5

Assessing different urban heat metrics in varied settlements and their relation to thermal comfort 

Svea Krikau, Iris Otto, Natalie Scheck, and Susanne Benz

Rising temperatures, resulting in prolonged heat waves and increased occurrences of tropical nights, present a risk to both morbidity and mortality rates. Urban populations are particularly vulnerable due to the additional elevation of temperatures within urban areas compared to the rural surroundings, commonly known as the "urban heat island effect". For the identification of heat exposure air temperature (Ta) at a high spatial scale is a preferred metric, however due to the scarcity of official measurement stations land surfaces temperature (LST) measurements are often used as a substitute. In addition, most studies focus only on densely populated urban areas, neglecting smaller settlements in a rural environment.
Here we show the differences in LST and air temperature extremes at nighttime for the state of Hesse, Germany. This involves comparing various temporal aggregates (such as 90th percentile and mean) and diverse urban heat metrics (including absolute temperatures and rural-urban temperature differences). We furthermore focus on small towns (5000 to under 20000 residents), medium-sized cities (20000 to under 100000 residents) and large urban metropolises (over 100000 residents) separately, taking into account the distinct relations to land cover/land use characteristics (indicated by Local Climate Zones) of the individual urban heat metrics. To gain insights into how these different temperature parameters (as well as daytime LST) relate to human-perceived comfort the Thermal Comfort Index 'Physiological Equivalent Temperature' (PET) is included as a metric.

How to cite: Krikau, S., Otto, I., Scheck, N., and Benz, S.: Assessing different urban heat metrics in varied settlements and their relation to thermal comfort, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8258, https://doi.org/10.5194/egusphere-egu24-8258, 2024.

EGU24-8402 | ECS | Orals | CL2.5

Urban Hydrometeorology: an overview and bibliometric analysis of published research 

Dragan Milošević, Ryan Teuling, Spyros Paparrizos, and Gert-Jan Steeneveld

Urban hydrometeorological (UHM) research is important for managing the challenges that arise from the complex interactions between climate change, meteorological processes and the water cycle in urban environments. It provides valuable insights for sustainable urban development, infrastructure planning, climate change adaptation, public health and improving the overall resilience of cities to weather, water and climate-related challenges. This bibliometric research analyses published literature on the research topic of UHM. In total, 507 studies were assessed in the period 1975-2023 based on the Web of Science database, covering almost half of the century of UHM research. Three subperiods with different publication trends were noticed. The first publication subperiod is the longest (1975-2020), but with the fewest publications (45), while the second subperiod is substantially shorter (2011-2017), but with a significant increase in the number of publications (122). The third subperiod is the shortest, i.e., from 2018 to 2023, and it is characterized by further substantial increase in the number of publications (340); although the shortest, the third subperiod contains 67% of published UHM studies, thus showing the increased interest in this research topic during the recent years. Furthermore, majority of UHM studies were published in the research fields of: 1) Environmental Sciences (175 studies), 2) Water Resources (165 studies); and 3) Meteorology and Atmospheric Sciences (150 studies). Countries/regions leading the way in UHM research and publishing are the USA, China and England, while there is a noticeable lack of UHM studies from Global South. Regarding sustainable development, UHM studies mostly contributed to the research on SDG 13 (Climate Action), SDG 6 (Clean Water and Sanitation) and SDG 11 (Sustainable Cities and Communities). The keyword analysis further revealed the changes in the main research themes during the last decades of the 20th century and the first decades of the 21st century. This study can be beneficial for those interested in acquiring more knowledge about UHM research and its application.

How to cite: Milošević, D., Teuling, R., Paparrizos, S., and Steeneveld, G.-J.: Urban Hydrometeorology: an overview and bibliometric analysis of published research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8402, https://doi.org/10.5194/egusphere-egu24-8402, 2024.

EGU24-8483 | Orals | CL2.5

Use of urban climate recommendation maps for heat action plans 

Janalisa Hahne, Lutz Katzschner, and Sebastian Kupski

Cities worldwide are in the phase of either acknowleding the need for heat action plans or are already in the phase of improving their existing plans. Due to bad ventilation conditions heat plays a major role in city dwellers‘ life. Heat actions plans are therefore a strongly advised intrument by many experts. Main tools are urban climatic maps (UCM) and their recommendation plans.

This article is about the methods during the development phase of heat action plans with a focus on urban climatology. We suggest to use urban climate maps and recommendation maps under the framework of VDI Guidelines „urban climate and planning“ to locate areas, institutions and livinghoods facing heat and to develop recommendations to decrease vulnerability.

With the example of a small city in Western Germany the methodology is shown. Based on urban climate map and recommendation map those loactions were identified which are moderately hot or show inconvenient ventilation conditions. Together with demographic statistics (age), vunerable groups were identified: Children under 6 years and people over 65 years. Further, we analysed the location of institutions which become frequently visited by vulnerable people: i.e. kindergartens, schools, care institituions for older people. We added urban green infrastructure (UGI) as places for recreation during heat phases.

WIth the help of geoinformation services (GIS) we were able to combine the different information from UCM, recommendation map, UGI, demographic statistics and the location of the „sensitive institutions“ to find spots most attractive for recreation as well as spots less attractive or even dangerous in terms of health during heat. This technique gives valuable and localised information for developing heat action plans.

How to cite: Hahne, J., Katzschner, L., and Kupski, S.: Use of urban climate recommendation maps for heat action plans, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8483, https://doi.org/10.5194/egusphere-egu24-8483, 2024.

EGU24-8755 | ECS | Orals | CL2.5

Microclimatic effects of idealized urban planning projects on their surrounding area 

Martin Schneider, Tanja Tötzer, and Marianne Bügelmayer-Blaschek

Over the past years, microclimate simulations and analyses became an important tool for the impact assessment of different planning scenarios of real estate projects on a local site. Based on the results of evaluated scenarios, the need for (additional) climate adaptation measures can be identified and improved design concepts might be realized. While this process led to several positive developments and best practice examples, the impact of a building project on the microclimate of the surrounding areas in spatial proximity to the development area is often still neglected. Especially if formerly green areas are sealed, cold-air production areas are lost, or cold-air corridors blocked. Even positively assessed microclimate studies for the local site itself, can have a negative effect on the microclimate of the surrounding area. While large urban planning projects (e.g., area size > 15 ha) in Austria require environmental impact assessments, policy makers and administrative units lack objective criteria to request spatially extended microclimate analyses for medium sized projects that not only affect the development area but also the neighbouring quarters.

In the prevalent research project, “Development of a criteria catalogue for requiring extended microclimate analyses”, funded by the Climate and Energy Fund and carried out under the program "Austrian Climate Research Programme Implementation", potential microclimatic impact of urban planning projects on their surroundings during autochthonous weather conditions in summer is evaluated through sensitivity experiments with the urban climate model PALM-4U. Based on the concept of Local Climate Zones (LCZ), idealized real estate projects are set up in two locations (inner city and periphery) of the city of Linz (Austria). For each location, the following selected characteristics of static input data are varied: (1) size of building site, (2) building footprint, (3) building height, and (4) degree of soil sealing. By comparing simulation results to the reference scenario of an unsealed, green area, the potential impact in terms of intensity and spatial range is assessed.

Results of the sensitivity experiments are used to compile a compact set of criteria, which allows policy makers and administrative units to request spatially extended microclimate analyses to evaluate effects of medium sized urban planning projects on the district-wide microclimate if impacts are expected.

How to cite: Schneider, M., Tötzer, T., and Bügelmayer-Blaschek, M.: Microclimatic effects of idealized urban planning projects on their surrounding area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8755, https://doi.org/10.5194/egusphere-egu24-8755, 2024.

Radiative cooling (RC) materials gained interest over the past decades, as these can help mitigating the urban heat island effect, fighting climate change and reducing the cooling demand for buildings. Their altered photonic properties, albedo and emissivity, enable these materials to cool down below ambient temperature and radiate heat in the atmospheric spectral window (8-13 µm), effectively releasing heat into space. Current RC materials typically consist of thin layers of metal and polymer, manufactured through energy-intensive and costly manufacturing processes. The Horizon 2020 project ‘MIRACLE’ is developing a new innovative radiative cooling material, that for the first time, is based on conventional concrete.

This study quantifies the effect of the Photonic Meta Concrete (PMC) on the climate of the highly urbanized region of Flanders, Belgium (13600 km²). Modelling such a large area allows to explore the impact on the urban heat island across multiple cities with diverse geometrical and geographical properties. More specifically, this study assesses the urban heat island effect of selected cities during a heatwave in August of 2019, comparing scenarios with and without the implementation of PMC in the built environment. The COSMO-CLM regional climate model, utilizing the TERRA-URB urban-canopy land-surface scheme, is employed for this assessment. Integration of the PMC’s photonic properties, i.e. the specific emissivity and albedo, into the urban canopy scheme is achieved by adapting the land surface parameters using the Semi-empirical Urban CanopY parametrization (SURY). Comparisons are made between scenarios incorporating specific albedo of the PMC, specific emissivity of the PMC or both against a baseline scenario without the PMC implementation. These comparisons aim to estimate the mitigation potential offered by this innovative material.

Initial findings suggest that the PMC shows promising potential for lowering city temperatures, with the albedo being identified as the primary factor in combating the urban heat island effect. In Brussels, surface temperatures drop by as much as eight degrees, while temperatures at a height of two meters decrease by up to two degrees

How to cite: Adams, N., Neirynck, J., Borgers, R., and Van Lipzig, N.: Implementation of a newly developed Photonic Meta-Concrete into the COSMO-CLM model to estimate the impact on the urban heat island: a case study of Flanders, Belgium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9028, https://doi.org/10.5194/egusphere-egu24-9028, 2024.

EGU24-9290 | ECS | Posters on site | CL2.5

Interaction between Urban Heat Island and Sea-Breeze: a focus on Shanghai 

Hongying Chen, Sara Top, Rafiq Hamdi, and Steven Caluwaerts

In the context of ongoing global warming and the intensification of urbanization processes, urban climate research is particularly important. The urban heat island (UHI) stands out as the most typical characteristic of urban climates. Shanghai is recognized as one the largest cities in China, with over 24 million inhabitants. Located on the east coast, Shanghai’s climate is significantly affected by the UHI and sea breeze, particularly during the summer.

UHI and sea breezes have been extensively explored in various coastal cities on a global scale.  This study aims to run for the first time the ALARO model over the Shanghai region and analyze interplay between sea breezes and UHI during heat waves (HW). The ALARO-SURFEX regional climate model set-up will be used for dynamical downscaling from ERA5 up to kilometric resolution. Urban effects will be taken into account by running the Town Energy Balance (TEB) module. The model runs will be evaluated based on observations in different Local Climate Zones (LCZs). The ECOCLIMAP database used to characterize the land characteristics has been updated based on detailed urban datasets of Shanghai.  Additionally, this study will explore the effects of LCZs on this interaction.

How to cite: Chen, H., Top, S., Hamdi, R., and Caluwaerts, S.: Interaction between Urban Heat Island and Sea-Breeze: a focus on Shanghai, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9290, https://doi.org/10.5194/egusphere-egu24-9290, 2024.

EGU24-9351 | ECS | Posters on site | CL2.5

Mapping Urban Heat Islands Using Calibrated ENVI-met Model : Application to Sense-City Data 

Nacer Sellila, Julien Waeytens, Martin Hendel, Yan Ulanowski, and Alejandra Castellanos

Urban heat islands (UHI) occur in urban areas with higher temperatures than in surrounding zones, exhibiting an average increase of 2°C. During summer heatwaves, this difference can even reach up to even 12°C. This intense heat phenomenon in urban areas leads to thermal stress, potentially causing health issues such as increased risks of dehydration, heat strokes, and other heat-related health problems. To evaluate the impact of thermal variations on health in urban environments, ENVI-met is used. This work focuses on two main points: sensitivity analysis and parameter calibration.

Numerical sensitivity analysis allows to study the influence of urban area model parameters on quantities of interest (e.g. thermal confort indices). These parameters include notably surface albedo and emissivity. Hence, it gives information of their impact on heat islands. This step prioritizes the influence of each parameter, providing crucial insights for the subsequent stages of the study.

To better understand these urban phenomena and design efficient mitigation solutions, the calibration of the ENVI-met model stands as a promising approach. It aims to establish a digital twin based on experimental data. This calibrated model will enable a detailed mapping of urban temperature and other environmental parameters, thereby enhancing our understanding of the mechanisms behind urban heat islands.

This approach will facilitate an evaluation and comparison between the outcomes of the numerical model and the experimental data collected in Sense-City urban area. Sense-City is a climate chamber that can cover two $400m^{2}$ areas. These urban areas can be studied in natural conditions or in controlled climatic conditions. This comparison will strengthen the credibility and trust in the accuracy of the established digital twin. Thanks to simulations and experimental observations, we will have the opportunity to deepen our knowledge about the formation and the evolution of urban heat islands in this specific environment and to select efficient cooling strategies at the block-scale.

How to cite: Sellila, N., Waeytens, J., Hendel, M., Ulanowski, Y., and Castellanos, A.: Mapping Urban Heat Islands Using Calibrated ENVI-met Model : Application to Sense-City Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9351, https://doi.org/10.5194/egusphere-egu24-9351, 2024.

Heat stress is a major challenge in urban areas, especially in cities which are affected by the urban heat island effect. Adaptation measures are a key strategy to mitigate future heat and health consequences in the context of climate change. To improve both indoor and outdoor microclimatic conditions and thermal comfort, nature-based solutions like roof greenings or wet roofs are implemented as they do not require additional space in dense urban environments. However, cooling effects of evaporation- and transpiration-based adaptation measures are limited by water availability to enable latent heat flux and reduce sensible and wall heat flux during extreme prolonged heat events. Water storage systems like rainfed cisterns can supply water for roof greenings or wet roofs during hot periods, but also store storm water to reduce flooding risks. While individual green roofs or blue roofs only show small local cooling potentials in their direct surrounding of their installation, scaling such measures for a larger proportion of buildings can cause significant cooling effects for the entire air volume of a city. This research aims to simulate heat mitigation effects of blue and green roofs on building wall temperature and thermal outdoor comfort using the physically-based microclimate model ENVI-met. A 16-ha 3D gridded model domain of a dense urban district in the city of Cologne/Germany was parameterized using remote sensing data and field observations. The model is validated based on a quality-controlled, densely-distributed microclimate measurement network with 59 sensors which was setup in the study area. A new model parameterization for wet roofs was developed. Scenario analyses are performed to scale these measures up to an implementation on all 338 buildings in the model domain (100%). Statistically significant average cooling effects of -0.52 K and up to -2.67 K on air temperature and -3.85 K and up to -29.03 K on building roof wall temperature were found for blue roofs in relation to the reference run of the status-quo. For roof greenings, average cooling effects of -0.76 K and up to -3.01 K for air temperature and -12.82 K and up to -39.45 K for wall temperature were determined. Cooling effects of green roofs on outdoor air temperature are strongest during daytime, and for wet roofs strongest in the evenings. Green roofs also have a higher wall cooling potential than blue roofs during daytime. However, roof greenings only show small effects on wall temperatures during nighttime, while blue roofs slightly heat up walls in nighttime. In future research, climate change adaptation and heat mitigation potentials of combining blue and green roofs with other nature-based and technical solutions in the street canyons will be analysed. 

How to cite: Eingrüber, N., Korres, W., and Schneider, K.: Comparison of heat mitigation effects of blue roofs and green roofs on building wall temperature and thermal outdoor comfort based on scenario analyses using 3D microclimate modelling for a dense urban district , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9967, https://doi.org/10.5194/egusphere-egu24-9967, 2024.

EGU24-10422 | Posters on site | CL2.5 | Highlight

Urban turbulence fluxes for free!  Estimating the surface fluxes for heat, moisture and momentum over cities from crowdsourced observations. 

Gert-Jan Steeneveld, Fidessa Wijnholds, and Wessel van der Meer

The interest in urban meteorology is growing and thus the need to understand and quantify the urban energy balance consisting of the sensible heat flux (QH), the latent heat flux (QE) and the momentum flux (u*) is essential. However, professional meteorological flux observations over cities are scarce and challenging to maintain. Nevertheless, many cities have a dense network of personal weather stations, operated by citizens. This study presents a model to estimate turbulence fluxes over cities that is driven by air temperature, wind speed, and relative humidity from urban weather stations and by information about the urban morphology. The model was tested against flux observations in Amsterdam (the Netherlands) once fed with professional observations from the automatic weather stations of the Amsterdam Atmospheric Monitoring Supersite and once from crowdsourced observations Netatmo personal weather stations. Overall, for both professional and crowdsourced input the estimated QH and u∗ agreed with the observations, whereas the model performed relatively poor for QE. Using crowdsourced input resulted in nearly identical root mean squared errors (RMSE) for QH and QE as using professional input, whereas for u∗ the RMSE was smaller when professional input was used. The model performed better during daytime, under conditions with few clouds and without precipitation. Also, we test the approach for Vienna (Austria) and Tokyo (Japan), and develop the approach further and show that the spatial variability of the temperature across an urban network can be used as proxi for the downwelling solar radiation. Although there is room for model improvement, our results illustrates the potential of using crowdsourced observations to estimate the urban surface fluxes for heat, moisture and momentum.

How to cite: Steeneveld, G.-J., Wijnholds, F., and van der Meer, W.: Urban turbulence fluxes for free!  Estimating the surface fluxes for heat, moisture and momentum over cities from crowdsourced observations., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10422, https://doi.org/10.5194/egusphere-egu24-10422, 2024.

EGU24-11400 | ECS | Orals | CL2.5

The food-water-climate nexus of green infrastructure: Examining ecosystem services trade-offs of peri-urban agriculture 

Ricard Segura-Barrero, Johannes Langemeyer, Alba Badia, Sergi Ventura, Jaime Vila-Traver, and Gara Villalba

Emission reduction, heat mitigation, and improved access to water and food provision are increasingly critical challenges for urban areas in the context of global climate change adaptation and mitigation. The revival of local agricultural production is often lauded as a potential nature-based solution. However, an expansion of peri-urban agriculture (peri-UA) may entail significant trade-offs in the ecosystem services it provides.

This study explores the impacts on the food-water-climate nexus of different scenarios of peri-urban agricultural expansion in a semi-arid, Mediterranean climate, addressing local food provision, freshwater use, local temperature regulation, global climate change mitigation, and the trade-offs thereof. Examining four theoretical land-use scenarios in the Metropolitan Area of Barcelona, the study integrates estimates of food provision and irrigation water requirements based on georeferenced urban metabolism approach with the local atmosphere and biogenic carbon balance estimates produced through the combination of an atmospheric model with a satellite and meteorological-driven biosphere model.

Our study reveals that a 31.12 % (+17.27 km2) and 115.08 % (+64.25 km2) increase in the current peri-UA in the AMB, achieved by replacing natural non-forested and forest areas, results in an increase in local food production of 24.0 % (+16503 tons year-1) and 85.8 % (+58940 tons year-1), respectively. However, it would also increase the irrigation water requirements by 10.0 % (+3.2 hm3) and 43.5 % (+14.1 hm3), respectively. The analysis of the midday/midafternoon temperatures during a summer hot month reveals that peri-UA especially when it is irrigated can potentially reduce near-surface temperatures up to 0.7 °C with respect to a current scenario, however the air cooling affects principally located in rural regions with lower population density, while temperature reductions in the densest urban areas are minimal. If an expansion of Peri-UA goes at the expense of natural non-forested and forests areas, as in the scenarios we used, it has further the potential to disrupt the regional carbon balance, impacting the net ecosystem productivity of the AMB green infrastructure and overall carbon stocks with reductions in the net ecosystem productivity of up to 18.5 % and reduce total carbon stocks by 3.3 %.

These findings, derived from an innovative and combined modelling approach, reveal significant trade-offs in ecosystem services associated with an expansion of peri-urban agriculture. It is likely that similar trade-offs would be observed with other nature-based solutions strategies. An integrated understanding of these trade-offs, facilitated by nexus approaches that combine different models, appears to be a promising direction for informing land-use decision-making in the context of urban climate adaptation and mitigation. 

How to cite: Segura-Barrero, R., Langemeyer, J., Badia, A., Ventura, S., Vila-Traver, J., and Villalba, G.: The food-water-climate nexus of green infrastructure: Examining ecosystem services trade-offs of peri-urban agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11400, https://doi.org/10.5194/egusphere-egu24-11400, 2024.

EGU24-11609 | Orals | CL2.5

A new method for automatic identification and ranking the urban heat island hotspots 

Adina-Eliza Croitoru, Zsolt Magyari-Saska, Csaba Horvath, and Sorin Pop

Urban Heat Islands (UHIs) are increasingly posing critical challenges to urban environments and human well-being. In response, we propose a novel methodology to identify Urban Heat Island Hotspots (UHIHs) to address the urgent need for effective management and mitigation strategies. Our research introduces the innovative concept of direct UHIHs detection and ranking, providing a framework for urban planning stakeholders to prioritise areas for regeneration based on UHIH severity.

A new concept is proposed, and it consists of: hotspot ranking in a given urban area, a new algorithm for hotspot detection, and a new tool for automatic detection and ranking hotspots. This approach greatly improves the effectiveness of interventions to mitigate the adverse impacts of UHIs on urban environments and public health.

This methodology addresses the critical importance of incorporating threshold percentiles and considering the spatial coverage of the study area. It relies on percentile-based thresholds, establishing the minimum acceptable values for individual cells and the mean values of the entire UHIH area. Through extensive experimentation with various threshold pairs, we identified the most suitable thresholds for further application, considering both LST values and non-climatic factors (e.g., urban fabric and imperviousness). The new hotspot identification algorithm calculates minimum acceptable values for individual cells and hotspot means, which plays a pivotal role in pinpointing UHI hotspots effectively. Each hotspot is identified on a step-by-step basis, starting with the identification of the highest temperature cell, which hasn’t been assigned to any other hotspot in previous steps. Further on, the algorithm searches among all surrounding cells and checks if they meet the two threshold conditions or not. In case of a positive result, the identified cell is assigned to the current hotspot and placed in a stack for its neighbours to be further considered. In addition to the detection process, this research introduces the concept of hotspot ranking based on their intensity. This innovative feature enhances the utility of our algorithm by prioritising the severity of UHI hotspots, facilitating data-driven decision-making for urban planning and climate mitigation strategies.

The practical implementation of the proposed algorithm is sustained by the use of the versatile R programming language, providing researchers and practitioners with a flexible and user-friendly tool.

This research addresses the complex challenges urban heat islands induce, offering a comprehensive approach readily adoptable by researchers and urban planners. It underscores the urgency of UHI management and its potential to enhance the well-being of urban populations.

In summary, this new approach and tool could become very useful in the urban planning process as they:

  • Enhance the effectiveness by prioritising the assessment of UHIHs based on their severity in a given location;
  • Provide a valuable tool for data-informed decision-making in urban planning and climate mitigation;
  • Enables urban planners and stakeholders to allocate resources and interventions more strategically, focusing on the critical areas from the UHI perspective;
  • Maximise the impact of the urban planners/stakeholders’ efforts in enhancing urban resilience and sustainability.

How to cite: Croitoru, A.-E., Magyari-Saska, Z., Horvath, C., and Pop, S.: A new method for automatic identification and ranking the urban heat island hotspots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11609, https://doi.org/10.5194/egusphere-egu24-11609, 2024.

EGU24-11633 | ECS | Orals | CL2.5

Effect of city and climate change on weather conditions, building thermal comfort and energy consumption: application to Strasbourg region 

Florentin Breton, Alice Micolier, Makram Abdellatif, Maxence Mendez, and Nadège Blond

Weather conditions play a large role in thermal comfort and energy consumption, such as during a cold spell (body hypothermia and building heating) or a heatwave (body overheating and building air conditioning). These weather conditions can be modified by urban factors and climate change, such as higher temperatures in city-center and in future periods. However, weather conditions used for building design and renovation are often taken for convenience from past data near airports. The present study aims to determine weather conditions with urban factors and climate change, as well as thermal comfort and energy needs for several building types in different environments. Measurements and simulations are combined to provide weather conditions and building estimations for different locations (rural, periurban, urban), seasonal cases (winter, summer, heatwave) and periods (recent past, mid-century, end-century). A first application of the approach is presented over the city of Strasbourg (France).

We find that the urban case has higher temperature, reduced windspeed and relative humidity, less energy for winter heating and less summer thermal comfort than the periurban than the rural case. Climate change leads to higher temperature and lower relative humidity, and to less summer thermal comfort especially during a heatwave and for older buildings. The combined effect of city, heatwave and climate change on outdoor air temperature reaches 8 to 11 degrees, and similarly for the indoor air temperature of very old buildings but 5 to 7 degrees for recent (well-insulated) buildings. This approach may support building renovation strategies and analyses of population vulnerability. The perspectives include the application to other regions, a comparison of urban climate models, and an investigation of urban scenarios.

How to cite: Breton, F., Micolier, A., Abdellatif, M., Mendez, M., and Blond, N.: Effect of city and climate change on weather conditions, building thermal comfort and energy consumption: application to Strasbourg region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11633, https://doi.org/10.5194/egusphere-egu24-11633, 2024.

EGU24-12850 | Orals | CL2.5

High-resolution air temperature modeling during the summer 2022 heat waves over Dijon 

Alexandre Berger, Julien Crétat, Julien Pergaud, Benjamin Pohl, Mélissa Poupelin, and Yves Richard

1Centre de Recherches de Climatologie/Biogéosciences, Université de Bourgogne, Dijon, France - alexandre.berger@u-bourgogne.fr

2Laboratoire ThéMA, Université de Bourgogne, Dijon, France

 

Heat waves (HWs) become more frequent, severe and longer under climate change. In cities, their impact is exacerbated by urban heat islands (UHIs). Proposing efficient adaptation plans necessitates upstream studies to further understand air temperature space-time variability within cities during HWs, their drivers, and associated mechanisms and processes.

This study aims at understanding 2 m air temperature (T2m) space-time variability during the four HWs that occurred in Dijon during summer 2022 based on the dense MUSTARDijon network of 92 thermometers. We used a 150 m mesoscale simulations performed with the Meso-NH atmospheric model coupled with the TEB and ISBA surface schemes optimized for urban and rural environments, respectively. First, we evaluate the capability of Meso-NH to simulate the diurnal cycle of T2m for the four HWs over urban and rural environments. We show that Meso-NH more skillfully simulates the T2m diurnal cycle over urban than rural environments, despite a systematic cold bias in early morning and late afternoon. Second, we focus on the drivers of T2m space-time variability by using different predictors including land cover, energy budget, soil and atmospheric humidity and atmospheric dynamics. Buildings and roads contribute to warm the urban environment mostly at night, but these contributions are exaggerated by Meso-NH during all HWs. By contrast, vegetation contributes to cool the urban environment all day long for low vegetation and at night only for high vegetation in both observations and simulations. Also, wind speed seems having a strong impact on UHI intensity.

How to cite: Berger, A., Crétat, J., Pergaud, J., Pohl, B., Poupelin, M., and Richard, Y.: High-resolution air temperature modeling during the summer 2022 heat waves over Dijon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12850, https://doi.org/10.5194/egusphere-egu24-12850, 2024.

EGU24-13001 | ECS | Posters on site | CL2.5

Multiscale characterization the Urban Heat Island (UHI) of the city of Milan (Italy) 

Luca Gallia, Federico Agliardi, Sergio Cogliati, Stefano Basiricò, Roberto Garzonio, Cinzia Panigada, Roberto Colombo, and Riccardo Castellanza

Milan is one of the largest, most industrialized and populated cities of Italy. It extends over more than 180 Km2, most of which are built or paved areas. The area is characterized by the perturbation of thermal regime known as Urban Heat Island (UHI), that is related to a variety of natural and anthropogenic factors. UHI is observed on different spatial scales, from macro (citywide) to micro (neighbourhoods), and can be significantly heterogeneous depending on urban structure and builts environment. UHI usually includes three layers: surface-layer heat island (SLHI), canopy-layer Heat Island (CLHI) to the top of built environment, and boundary-layer Heat Island (BLHI). Its robust monitoring and modelling is crucial to support actions aimed at improving urban climate. 

In this perspective, we focused on the reconstruction of the Milan UHI, taking into account its spatial heterogeneity and temporal variability. We started by mapping the UHI at the regional scale of the Milan metropolitan area since April 2013, using Landsat imagery that is able to provide Land Surface Temperature (LST) at 100m resolution. Through Google Earth Engine, we collected 14 Landsat-8 LST images over the period 2015-2023. This allowed obtaining macroscale measures of the heterogeneous nature of the UHI and identifying important hot-spots. One of them is the Bicocca neighborhood, a former industrial district that underwent significant urban changes over the last four decades, and it is still made of a mixture of industrial, residential, vegetated, or mixed spots. For each of these targets, we analyzed the spatial distributions and temporal trends of LST, providing “signatures” of the different components of a complex UHI.

At the urban micro-scale, we focused our attention on Piazza della Scienza (Bicocca university campus) and its surroundings that are undergoing extensive urban regeneration, including depaving and nature-based solutions in the framework of the PNRR project MUSA (Milano Urban Sustainability Action). Here, UHI characterization and monitoring in space and time is required to compare pre- and post- intervention conditions and to setup and calibrate dynamic numerical models that support a quantitative understanding of urban climate evolution and urban design optimization. This kind of monitoring requires a trade-off between the needs of accurate spatially-distributed and temporally-continuous measurements of surface and air temperature and related variables. To do this, we combined different techniques and multiple technologies. Surface temperature was characterized through a radiometrically-calibrated IRT camera (FLIR-T1020/T650) for the spatially-distributed, discontinuous time-lapse characterization of key sectors of ground and buildings. Furthermore, HOBO sensors (T/RH-sensors) provided accurate continuous temperature time series at many key locations spread over the area. Air temperature was monitored through UAV-based thermal sensors along vertical profiles up to 120m high at different locations and different times, to obtain a 3D grid of temperature measurements across the CLHI. This wealth of information, obtained at different spatial scales over time, will allow the reconstruction of the internal structure, heterogeneity and temporal trends of the Milan UHI, as a first step towards the development of dynamic numerical models that will support the definition, implementation and validation of urban renewal and mitigations strategies.

How to cite: Gallia, L., Agliardi, F., Cogliati, S., Basiricò, S., Garzonio, R., Panigada, C., Colombo, R., and Castellanza, R.: Multiscale characterization the Urban Heat Island (UHI) of the city of Milan (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13001, https://doi.org/10.5194/egusphere-egu24-13001, 2024.

EGU24-13324 | ECS | Orals | CL2.5

Disagreements among current-generation global urban estimates across scales 

Tirthankar Chakraborty, Zander Venter, Lei Zhao, Matthias Demuzere, Wenfeng Zhan, Jin Gao, and Yun Qian

The rise in high-resolution satellite technology and computational advancements has enabled the development of global urban land cover datasets, crucial for understanding climate risks in our increasingly urbanizing world. Here, we analyze urbanization patterns across spatiotemporal scales from several such widely used current-generation datasets and find substantial discrepancies in percentage of urban land influenced by differing urban definitions and methodologies. Despite these inconsistencies, the datasets show a rapidly urbanizing world, with global urban land nearly tripling between 1985 and 2015. We also discuss the implications of these inconsistencies for several use cases, including for monitoring urban climate impacts, such as localized urban warming and urban flood risks, and for modeling urbanization and its influence on weather and climate from regional to global scales. Our results demonstrate the importance of choosing application-appropriate datasets for examining specific aspects of historical, present, and future urbanization with potential implications for informing sustainable development, resource allocation, and quantifying climate impacts.

How to cite: Chakraborty, T., Venter, Z., Zhao, L., Demuzere, M., Zhan, W., Gao, J., and Qian, Y.: Disagreements among current-generation global urban estimates across scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13324, https://doi.org/10.5194/egusphere-egu24-13324, 2024.

EGU24-13679 | ECS | Orals | CL2.5

“GENIUS: Satellite Monitoring Platform for City Management and Planning” 

Javier Medina, Ana Hernández-Duarte, Freddy Saavedra, Valentina Contreras, Marcelo Leguía, and Carlos Romero

More than 50% of people worldwide live in cities with upward projections. Ensuring health, public safety, and maintaining a high quality of life is a challenge within cities due to the accelerated growth of urbanization, climate change, and the limited resources available for urban management and planning. Strategies for sustainable urban planning are a need that has become relevant worldwide. The concept of a Smart City is presented as an approach that integrates many inputs from different sources to make decisions based on reliable and updated information, considering, for example, environmental monitoring. However, capturing the spatiotemporal variability of processes within the city requires a significant investment in time and resources, especially for medium-sized cities in Latin America, where little information is available. Earth Observation based on open-access information offers essential opportunities to obtain information of interest, contributing to cities' physical and environmental characterization. Satellite sensors allow cities to be characterized in terms of the presence and state of vegetation, surface temperature, changes in the urban footprint, level of luminosity, and atmospheric pollution, among other parameters. This ongoing project is progressing with a web platform containing urban-environmental indicators derived from satellite images to support intelligent planning and management of sustainable development strategies in the city. The platform is currently undergoing pilot development in the city of Quilpué, Valparaíso Region, with the potential for scaling to other territories at the regional and national levels. Preliminary findings with satellite data reveal adverse trends in surface temperature, vegetation health, and air quality in Quilpué City, which are currently undergoing validation with on-site data. Efforts were focused on merging socio-economic and environmental data to pinpoint areas with vulnerable populations. Despite the emphasis on environmental variables, gaps exist in analyzing population exposure to these factors due to outdated demographic information. This underscores the importance of nature-based solutions to exposure variables such as air quality, surface temperature, and proximity of green areas, which could be addressed by governance risk management and public policy planning. This approach offers substantial potential for informed decision-making and risk mitigation strategies.

How to cite: Medina, J., Hernández-Duarte, A., Saavedra, F., Contreras, V., Leguía, M., and Romero, C.: “GENIUS: Satellite Monitoring Platform for City Management and Planning”, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13679, https://doi.org/10.5194/egusphere-egu24-13679, 2024.

EGU24-14149 | Orals | CL2.5

Contrasting Responses of Heat Mitigation Strategies on Surface and Air Temperature and on Thermal-Stress Indices Deduced from Mesoscale Modelling 

Sylvie Leroyer, Stéphane Bélair, Nasim Alavi, Oumarou Nikiema, Rodrigo Munoz-Alpizar, and Ivana Popadic

With recent advances in subkilometric numerical weather prediction (NWP) for urban areas1, it has become possible to develop numerical platforms to assess landscape modifications and in particular heat mitigation scenarios in urban areas. One of the major barriers that exist for urban planners and health institutes to rely on such data is that they might be reluctant to consider the large amount of data produced by such numerical simulations.  This study aims at analyzing results in a more holistic approach, with the objectives of developing training data for statistical assessment of the impact of heat mitigation strategies in a particular city.

In a recent study2, evaluations of scenarios for the urban landscape modifications were performed in Canada for Montreal and Toronto metropolitan areas with the Global Environmental Multiscale (GEM) atmospheric model with grid spacing of 250 m (with the Town Energy Balance TEB and the Interactions between the Soil, the Biosphere and the Atmosphere ISBA surface schemes) and applied during two overheating periods in 2010 when large impacts on the mortality rate were observed. More than 20 scenarios were assessed with realistic but ambitious scenarios, including increase of vegetation fraction with or without irrigation, and of thermal reflectivities. Various responses on the temperature reduction were found with an overall improvement, and down to -3 oC during the daytime, but negative effects were also found on the thermal stress during daytime when increasing albedo values.

More insights into the results are provided in this study, using various normalized efficiency metrics, as for example those based on previous work3 and extended to the mean radiant temperature and to thermal stress indices computed in these experiments (UTCI and WBGT4).  Dependencies of the measures on the various environmental conditions will be presented and greening strategies will be analyzed in combination with the soil water availability. 

References:

1.Leroyer, S., et al., 2022, https://doi.org/10.3390/atmos13071030

2.Leroyer, S., et al., 2019, https://doi.org/10.5281/zenodo.7075789

3.Krayenhoff, E.S., et al., 2021, https://doi.org/10.1088/1748-9326/abdcf1

4.Leroyer, S., et al., 2018, https://doi.org/10.1016/j.uclim.2018.05.003

How to cite: Leroyer, S., Bélair, S., Alavi, N., Nikiema, O., Munoz-Alpizar, R., and Popadic, I.: Contrasting Responses of Heat Mitigation Strategies on Surface and Air Temperature and on Thermal-Stress Indices Deduced from Mesoscale Modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14149, https://doi.org/10.5194/egusphere-egu24-14149, 2024.

EGU24-14389 | Posters on site | CL2.5

ILS+Urban: an offline land-surface process model for global urban climate and energy simulations 

Yuya Takane, Tomoko Nitta, Sachiho A. Adachi, Kei Yoshimura, Masuo Nakano, Makoto Nakayoshi, Shiho Onomura, and Ben Crawford

We have developed ILS+Urban: a coupled model of an offline land-surface model (ILS) and an urban canopy and building energy model (SLUCM+BEM) for global urban climate and energy research. The ILS is an offline land-surface model that includes MATSIRO, a land-surface model for the global climate model MIROC5. The SLUCM+BEM is a new parametrisation for urban climate and energy simulations developed by the authors, which can simply simulate anthropogenic heat from buildings (QFB) and electricity consumption (EC) from human activities. We have implemented the SLUCM+BEM in the ILS, which allows us to simulate global urban climate and energy with relatively low computational resources in offline mode. A test simulation of ILS+Urban shows that QFB and EC tend to be quantitatively high throughout the year in the Middle East, for example. In the near future, we will implement a global urban database (e.g. global LCZ, anthropogenic heat emissions and morphology) and new technology parameterisations (e.g. EV, PV and heat pump water heaters) for global urban climate and energy projections and countermeasures for urban heat and energy savings & generation. In addition, the ILS+Urban will be coupled with global climate models (e.g. MIROC and NICAM).

How to cite: Takane, Y., Nitta, T., Adachi, S. A., Yoshimura, K., Nakano, M., Nakayoshi, M., Onomura, S., and Crawford, B.: ILS+Urban: an offline land-surface process model for global urban climate and energy simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14389, https://doi.org/10.5194/egusphere-egu24-14389, 2024.

Cities such as Austin, Texas have in the last decade noted increase in severity and frequency of weather extremes, causing loss of life and millions in damaged property and  critical infrastructure. Communities with the fewest resources often experience the greatest burden from these events and struggle to “bounce back.” The City of Austin, as well as all other cities around the world, are currently scrambling to understand how to plan for an uncertain future. 

The University of Texas (UT)-City Climate CoLab is a novel initiative that builds on the success of national climate assessments, the state and regional climate centers, and highlights and fills the void of creating a city climate office. The UT-City of Austin CoLab develops Austin and City-specific climate information, data products, tools, and assessments to drive innovation and investment in research, policy, governance, and education. This CoLab is the first City-academia  climate collaboratory in the US through the city council.

City Council, planners, engineers, and other decision-makers are using the past to predict the future, and with climate change, that approach is no longer sufficient. This presentation will bring out the workings of this colab with the City staff and community group on extreme weather and climate projects. The City Colab has been working on different needs/problems to solve:

  • Specific climate data and models needs that are often confusing for community and City project teams and staff, therefore not immediately useful for planning and policy purposes;
  • Academic research can be made accessible to different City departments, agencies, and programs to improve decision-making -- but is not easily usable; 
  • Currently there is no entity that directly supports municipal climate data needs. Climate aligns with multiple departments’ work but needs differ across teams. Need more coordination across departments and to connect data to city department decision making;
  • Currently, academia / City climate research projects are selected per faculty interest and a much more strategic approach is needed.

Types of Projects: (a) City Climate Assessment (coinciding with global climate assessment from IPCC; (b)  Data products:  Provide data based on different department needs; Develop data products and downscale the needed climate model information so that it is useful at city scale i.e. 100 km uniform grid information to gridded neighborhood scale (target 1 km x 1 km data output or even finer); (c) Communication: Collaborate with local news weather teams to share climate information; Connect through the City Public Information Office to share takeaways in official city press releases; (d)  Policy and Governance: Map intra- and inter-agency climate governance networks to understand key relationships, programs, and community organizations for outreach;  Research policy and governance frameworks;  Connect climate modeling data products to social and policy science, including social vulnerability;  Develop a stakeholder database and platform. (e) Outreach: Workshop and outreach for assessing media, community and stakeholder needs; Conduct public participation in scientific research by collecting and sharing data based on community feedback; Advance community science and volunteer monitoring efforts. 

A number of research topics are underway  and an outline of these activities, lessons learnt, and path ahead will be presented. 

How to cite: Niyogi, D.: The University of Texas Austin City Climate CoLab - Localizing Climate Decision using Data and Community Partnerships, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14394, https://doi.org/10.5194/egusphere-egu24-14394, 2024.

EGU24-15108 | ECS | Posters on site | CL2.5

Modelling Microclimatic Benefits of Urban Green Spaces: Insights from ENVI-met Simulations in Augsburg, Germany 

Jonathan Simon, Joachim Rathmann, Jacqueline Oster, Max Stocker, Lisa-Marie Falkenrodt, Elisabeth André, Bhargavi Mahesh, Yekta Said Can, Michael Dietz, Andreas Philipp, and Christoph Beck

With two thirds of the world's population expected to live in urban areas by 2050, the exacerbation of the urban heat island effect is a critical challenge, affecting thermal comfort, public health, and air quality. Urban green spaces (UGS) emerge as pivotal tools for mitigating these adverse effects. They provide essential ecosystem services, including thermal comfort, shade, pollution control, carbon storage, and water cycling. In addition, UGS provide city-dwellers with opportunities for recreation, social interaction, and aesthetic inspiration.

This study, funded by the German Research Foundation under contract 471909988, uses ENVI-met, a three-dimensional, grid-based microclimate model, to examine the positive microclimatic and biometeorological effects of UGS in different vegetation-dominated urban areas. The latest fractal-based L-tree (Lindenmayer system) representation in ENVI-met V5 provides a more nuanced representation of trees, categorised by tree species, considering variations in leaf area density within the tree crowns and the structurally correct representation of the tree skeleton.

Focusing on UGS in Augsburg, Germany, including an urban park and different urban forest sites such as a mixed forest, a pine forest, a beech-dominated forest and a heath, the study examines the hypothesis that L-trees provide more accurate microclimate models than grid-based 3D-plants of older ENVI-met versions. The investigation considers the influence of spatial resolution, tree species, tree shapes, and tree heights on modelling precision. Additionally, the study investigates whether UGS heat mitigation is more pronounced in summer than in other seasons and how much it is influenced by area size, vegetation density, and study site. The spatial extent of the model areas is approximately 0.4 km² - 1.0 km² with a spatial resolution of 2 m - 5 m. We expect that the microclimatic impact of tree species composition within an UGS may be negligible, but could nevertheless influence subjective thermal comfort, aesthetic inspiration, and health-related parameters. These aspects are the subject of two further parts of the study, which deal with the objective health effects and the subjective perception of different UGS.

Validation of microclimate model results includes field measurements using Kestrel 5400 heat stress trackers and HOBO MX2301A loggers. The study collected participant health and survey data during thermal walks through the UGS study sites, using wearable devices and questionnaires, to further validate various biometeorological effects and subjective perceptions. The research contributes to the advancement of microclimate modelling in urban parks and forests and provides insights crucial for optimizing ecosystem services of UGS to enhance urban resilience and promote sustainable development.

How to cite: Simon, J., Rathmann, J., Oster, J., Stocker, M., Falkenrodt, L.-M., André, E., Mahesh, B., Can, Y. S., Dietz, M., Philipp, A., and Beck, C.: Modelling Microclimatic Benefits of Urban Green Spaces: Insights from ENVI-met Simulations in Augsburg, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15108, https://doi.org/10.5194/egusphere-egu24-15108, 2024.

EGU24-15290 | Posters on site | CL2.5 | Highlight

Transforming public spaces towards user-friendly, climate resilient and energy producing spaces - the BARTLETT 

Tanja Tötzer, Marianne Bügelmayer-Blaschek, Martin Jung, Martin Schneider, Romana Berg, Karl Berger, Silja Tillner, Alfred Willinger, Karl Grimm, Irene Zluwa, and Elia Stefan

Urban areas are severely affected by climate change, as the associated increase in temperature and precipitation intensity are further exacerbated by the prevailing morphology of densely built areas and the prevalence of sealed surfaces. Especially heat has been recognised as an increasing risk and therefore, appropriate adaptation measures such as nature-based solutions (NbS) have been studied extensively.

Space is scarce and valuable in cities and the usability of urban spaces has gained a growing attention in the last years – not only in the sense of climate adaptation but also for climate protection, as the energy transition calls for the implementation of renewable energy sources, where public spaces offer great potential for PV-suitable areas. In addition, an increasing number of people living in cities demand more living space and put even more pressure on available public spaces.

These three aspects form the basis of the presented study, where a highly frequented public space, the Volkertplatz in Vienna is chosen to be transformed into a climate-resilient, user-friendly and energy-generating space. To achieve this, the following steps are necessary: (i) analysis of the current and future local climate conditions, (ii) incorporating and understanding the needs of the local users, (iii) design of the BARTLETT (Blue-green energy-generating canopied seating and communication facility) and (iv) implementation of an appropriate process of involvement of the local authorities.

The analyses show that the current design of the space prevents the infiltration of rainwater, intensifies the prevailing heat load in summer and mainly meets the needs of male users. Therefore, the transformed space needs to reduce the identified barriers in order to improve the quality of the Volkertplatz.  A key element is the BARTLETT, a construction that improves the local microclimate, collects rainwater for irrigation of the plants and produces energy through the installed PV collectors. Furthermore, the design enhances the usability of the square by different groups, providing both open and more hidden spaces. To ensure the acceptance of local citizens, their needs have been identified, their behaviour observed, and their opinions incorporated through workshops. As important as the local support, is the timely involvement of relevant political stakeholders, which is ensured by the project partners and collected in a handbook to allow transferability to other public spaces.

How to cite: Tötzer, T., Bügelmayer-Blaschek, M., Jung, M., Schneider, M., Berg, R., Berger, K., Tillner, S., Willinger, A., Grimm, K., Zluwa, I., and Stefan, E.: Transforming public spaces towards user-friendly, climate resilient and energy producing spaces - the BARTLETT, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15290, https://doi.org/10.5194/egusphere-egu24-15290, 2024.

EGU24-15357 | ECS | Orals | CL2.5

Urban Heat Island under Climate Change over European cities: Evaluation of the EURO-CORDEX ensemble performance in reproducing the UHI 

Eloisa Raluy-López, Victoria Gallardo, Pedro Jiménez-Guerrero, and Juan Pedro Montávez

The urban heat island (UHI) is defined as the temperature difference between a city and its rural surroundings. It is one of the most studied urban phenomena and can have potential adverse effects on human well-being. Furthermore, the UHI may contribute to an increase in the urban energy consumption and ecological footprint, potentially exacerbating the impacts of climate change. The aim of this study is to evaluate the capability of different regional models from the EURO-CORDEX ensemble to accurately reproduce the UHI over several European large cities. Subsequently, the evolution of the UHI under climate change scenarios is studied using the models that demonstrate good performance. 

The employed data were extracted from the EURO-CORDEX EUR-11 project and the ERA5-land dataset. The historical data cover the period 1971-2000. The future model data under the climate change RCP8.5 scenario are divided into near future (2021-2050) and distant future (2071-2100) periods. There are multiple ways to perform the UHI intensity calculation. In this case, the urban temperature of each city is assigned as the temperature series of the most urbanized grid point. The reference rural temperature is defined as the mean temperature series of all the valid rural points inside a 1º box centered in the most urbanized point. A rural point is considered to be valid if its rural fraction falls below 5%, its land fraction is no lower than 50% and if its altitude does not differ more than 100 meters from the urban point altitude.

The results of this study show that several models do not simulate the timing of the UHI correctly, exhibiting its daily maximum during the daytime instead of the nighttime, as seen in other studies. ERA5-land data present similar limitations. However, the RegCM4-6 and HadREM3-GA7-05 models are two examples of regional models able to successfully reproduce the UHI effect and its annual and daily cycles. The differences between the historical and future mean annual cycles of the UHI daily maximum show small to no changes in most of the cities, with these small differences being generally negative. Barcelona and Lisbon present greater negative changes, with a reduction of the UHI intensity of around 0.2 ºC in the near future and a reduction of around 0.4 ºC in the distant future. In contrast, Porto and Toulouse present positive differences with an intensification of the UHI effect of around 0.3-0.4 ºC in the distant future. Furthermore, the greatest changes in each city occur during the summer season. No important changes in the hourly distribution of the UHI daily maximum are found. In conclusion, the UHI effect seems to generally not aggravate the rising temperatures due to climate change in urban areas.

 

The authors acknowledge the ECCE project (PID2020-115693RB-I00) of the Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033). ERL thanks her predoctoral contract FPU (FPU21/02464) to the Ministerio de Universidades of Spain.

How to cite: Raluy-López, E., Gallardo, V., Jiménez-Guerrero, P., and Montávez, J. P.: Urban Heat Island under Climate Change over European cities: Evaluation of the EURO-CORDEX ensemble performance in reproducing the UHI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15357, https://doi.org/10.5194/egusphere-egu24-15357, 2024.

EGU24-15412 | Orals | CL2.5 | Highlight

A public database of future heat stress in 140 cities to examine the potential for heat reduction via climate-smart urban development  

Quentin Lejeune, Niels Souverijns, Sarantis Georgiou, Niklas Schwind, Sajid Ali, Tiago Capela Lourenço, Khadija Irfan, Dirk Lauwaet, Inês Gomes Marques, Helena Gonzales Lindberg, Inga Menke, Shruti Nath, Peter Pfleiderer, Hugo Pires Costa, Fahad Saeed, Mariam Saleh Khan, Sylvia Schmidt, Emily Theokritoff, Burcu Yesil, and Carl-Friedrich Schleussner

Heatwaves are becoming more frequent because of climate change, and this trend is exacerbated in cities due to the urban heat island effect. With more than half of the world’s population living in cities, it is essential to quantify the future evolution of heat stress and develop smart adaptation strategies to counter its impacts. This requires the capturing of fine-grained variations in heat-related hazards within the urban fabric. However, the coarse resolutions of Earth System Models makes it difficult to model urban areas explicitly. Moreover, high-resolution modelling of future climate conditions in cities is often conducted for select cities only, in very focused studies or by private companies, thus limiting the availability of its results in the public domain. Additionally, there is limited understanding of the potential of climate-smart urban development for reducing heat stress.

In the H2020 PROVIDE project, we use the urban boundary layer climate model UrbClim to generate projections of urban heat stress at a 100-meter resolution, for about 20 indicators in 140 urban centres across the world. UrbClim consists of a land surface scheme with simplified urban physics coupled to a 3-D atmospheric boundary layer module, and can represent the effect of varying land cover conditions on local climate. We consider three emission scenarios: 1) compatible with the 1.5°C goal of the Paris Agreement, 2) representative of the trend from current policies, and 3) an intermediary scenario. The forcing data corresponding to these scenarios is generated by coupling the emulator for Global Mean Temperature FaIR, with the Earth System Model emulator with spatially explicit representation MESMER. This allows us to account for uncertainties in the forcing data arising from both the response of Global Mean Temperature (GMT) to emissions, and the response of large-scale climate conditions above each city included in the study to rising GMT.

The resulting database is integrated into the PROVIDE climate risk dashboard, an open-access and user-friendly online tool that allows visualization of global-to-local future climate impacts depending on mitigation outcomes. The dashboard also contains a module that allows its users to first select a critical heat stress level of their choice, and then get information about the emission scenarios that would enable to avoid exceeding that level in their city of interest. This more impact-centered perspective on the UrbClim results provides information on future heat stress in a way that better reflect how climate impact information is accounted for in local adaptation processes.

Furthermore, we explore the potential for urban greening plans co-developed by urban planners and city-level stakeholders to reduce heat stress by running UrbClim at very high resolution (down to 1 meter) for the cities of Lisbon (Portugal), Bodø (Norway), Islamabad (Pakistan), and Berlin (Germany). These new results will eventually also be made available in the PROVIDE climate risk dashboard. Together with the insights from the urban planners and stakeholders’ needs, they offer more practical and policy-relevant insights for adaptation practitioners at the municipal level on the potential for climate-smart urban development to reduce heat stress.

How to cite: Lejeune, Q., Souverijns, N., Georgiou, S., Schwind, N., Ali, S., Capela Lourenço, T., Irfan, K., Lauwaet, D., Gomes Marques, I., Gonzales Lindberg, H., Menke, I., Nath, S., Pfleiderer, P., Pires Costa, H., Saeed, F., Saleh Khan, M., Schmidt, S., Theokritoff, E., Yesil, B., and Schleussner, C.-F.: A public database of future heat stress in 140 cities to examine the potential for heat reduction via climate-smart urban development , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15412, https://doi.org/10.5194/egusphere-egu24-15412, 2024.

EGU24-15460 | ECS | Posters on site | CL2.5

Cool pavements for adapting Paris to climate change 

Charbel Abboud, Sophie Parison, Frédéric Filaine, Martin Hendel, Laurent Royon, and Maïlys Chanial

In order to adapt to climate change, cities are studying various urban cooling techniques to improve 
pedestrian thermal comfort of users during heatwaves including urban greening and cool materials [1,2]. On 
technique being considered by the City of Paris is cool pavements [3] . To this aim, an experimental test site 
has been constructed and instrumented to study the thermal and climatic behavior of candidate sidewalk 
structures.
The experimental demonstrator is located in Bonneuil-sur-Marne near Paris, France. This experimental 
device consists of 16 samples of various sidewalk structures [4]. Each sample is approximately 4x4m across 
by 25 cm deep and is composed of several layers following real-world conditions. The samples are 
instrumented with temperature and heat flow sensors at several depths, with the data recorded every 5 
minutes. Additional weather measurements are also conducted onsite to monitor air temperature and 
humidity, global horizontal short- and longwave irradiance as well as wind speed and direction. 
This communication is focused on data collected during the summers of 2021 and 2022, specifically 
temperatures and heat fluxes and the derived surface heat budget of each sample. These data from each 
strcture will be analyzed with respect to their contribution to the degradation of pedestrian thermal comfort 
as well as to the urban heat island effect in order to inform the city services in their selection of suited 
sidewalk materials. 
Additional testing inside a climate chamber will supplement the demonstrator test site with complementary 
measurements performed in the laboratory. 

References:

[1] H. Akbari, M. Pomerantz, and H. Taha, “Cool surfaces and shade trees to reduce energy use and improve 
air quality in urban areas,” Sol. Energy, vol. 70, no. 3, pp. 295–310, Jan. 2001.
[2] M. Chanial, G. Karam, S. Parison, M. Hendel and L. Royon. (2022). Microclimatic analysis of an 
experimental cooling watering device (in French).. CIFQ 2022, Paris (France).
[3] Santamouris, M. (2013). Using cool pavements as a mitigation strategy to fight urban heat island—A 
review of the actual developments. Renewable and Sustainable Energy Reviews, 26, 224-240. 
[4] S. Parison, M. Chanial, F. Filaine and M. Hendel. (2022). Surface heat budget of sixteen pavement 
samples on an experimental test site in the Parisian region. SURF 2022, Milano (Italy).

How to cite: Abboud, C., Parison, S., Filaine, F., Hendel, M., Royon, L., and Chanial, M.: Cool pavements for adapting Paris to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15460, https://doi.org/10.5194/egusphere-egu24-15460, 2024.

EGU24-15471 | ECS | Posters on site | CL2.5

Monitoring pedestrian heat stress in Greater Paris 

James Kamara, Frédéric Filaine, Arnaud Grados, Nassim Filaoui, Basile Chaix, Julien Bigorgne, Martin Hendel, and Laurent Royon

Urban heat islands, combined with extreme heat waves, can provoke a public health risk. During the 2003 heat wave in Paris, strong correlations were observed between nighttime outdoor air temperatures and mortality [1]. However, previous studies only focus on outdoor nighttime air temperatures when citizens are sleeping, without linking these observations with the heat stress they may have been exposed to during the day or in their apartment. 

This standpoint is one of the principal aims of  “Heat waves, urban Health islands, Health: a mobile sensing approach” (H3Sensing ANR research project) by adopting citizen science methods in order to measure heat stress exposure over several days as well as physiological parameters. Mobile measurements of microclimatic parameters [2] allow us to characterize and map heat stress exposures [3] in Greater Paris. Stationary measurements in apartments and surveys will complete the data set which will be combined with measured physiological data.

Initial prototyping and testing of the microclimatic measurement kits and sensor characterization are presented and perspectives discussed. Besides, the constraints related to the prototype, such as using low-cost sensors or battery autonomy, will be discussed too.

 

References:

[1] Karine Laaidi, Abdelkrim Zeghnoun, Bénédicte Dousset, Philippe Bretin, Stéphanie Vandentorren, Emmanuel Giraudet and Pascal Beaudeau.(2011). The Impact of Heat Islands on Mortality in Paris during the August 2003 Heat Wave, Environmental Health Perspectives.

[2] Riccardo Bartoli, Frédéric Filaine, Sophie Parison and Martin Hendel. (2022). Development of a portable device for measuring thermal stress of a pedestrian (in French). CIFQ 2022, Paris(France).

[3]  Ilaria Pigliautile, Anna Laura Pisello.A new wearable monitoring system for investigating pedestrians' environmental conditions: Development of the experimental tool and start-up findings, CIRIAF ‐ Interuniversity Research Center, (Elsevier B.V.), University of Perugia, Perugia, Italy, (2018).





How to cite: Kamara, J., Filaine, F., Grados, A., Filaoui, N., Chaix, B., Bigorgne, J., Hendel, M., and Royon, L.: Monitoring pedestrian heat stress in Greater Paris, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15471, https://doi.org/10.5194/egusphere-egu24-15471, 2024.

EGU24-15826 | ECS | Orals | CL2.5

Evaluating the implementation of the new urban parameterization for the ICON atmospheric model: results over Italy 

Angelo Campanale, Marianna Adinolfi, Mario Raffa, Jan-Peter Schulz, and Paola Mercogliano

The increasing in the resolution of atmospheric models for numerical weather prediction and climate simulations allows a more accurate description of the physical processes at urban scale. Furthermore, as the world continues to warm, urban areas are expected to face the brunt of the impacts due to large populations and higher temperatures.

In all this scenario, the interest in proper modelling the physical processes in urban areas has gained wide attention from the research community. In particular, the convection-permitting atmospheric models, associated with urban parameterizations, are able to resolve the heterogeneity of cities with applications for heat stress assessment and the development of urban climate adaptation and mitigation strategies. Generally, these schemes parametrize the effects of buildings, streets and other man-made impervious surfaces on energy, water and momentum exchanges between surface and atmosphere, accounting also for the anthropogenic heat flux, as a heat source from the surface to the atmosphere due to human activities.

In this perspective, a bulk urban canopy parameterization, TERRA_URB, has been developed for the multi-layer land surface scheme of the COSMO regional atmospheric model. This parameterization has already demonstrated to be able to properly take into account the overall properties of urban areas and to correctly reproduce the prominent urban meteorological characteristics for different European cities. Thus, in the framework of the transition from the COSMO model to the new Icosahedral Nonhydrostatic (ICON) Weather and Climate regional model, TERRA_URB needs to be implemented in ICON.

In this work, we present the results for TERRA_URB in the ICON-LAM (limited area model), for some cities of the Italian peninsula at 2km resolution. The main outcome of this study is that the porting of the TERRA URB scheme in ICON is satisfactorily completed, and it reasonably reproduces urban effects, like Urban Heat Islands, while improving air temperature forecasts for the investigated urban areas. The results constitute an updating of numerical weather prediction and climate simulations for urban modelling applications, although further investigations aimed at enhancing the calibration of the model parameterization and introduction of more realistic urban canopy parameters are needed.

How to cite: Campanale, A., Adinolfi, M., Raffa, M., Schulz, J.-P., and Mercogliano, P.: Evaluating the implementation of the new urban parameterization for the ICON atmospheric model: results over Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15826, https://doi.org/10.5194/egusphere-egu24-15826, 2024.

EGU24-15984 | Orals | CL2.5

Comparison of different methods to produce local climate zone maps using the LczExplore tool 

Erwan Bocher, Matthieu Gousseff, Bernard Jérémy, Elisabeth Le Saux Wiederhold, Baptiste Alglave, and Emmanuelle Kerjouan

Urban climate conditions under global or regional change are a major stake for city planners and policy makers.

Members of the different involved communities need a common way to describe urban territory, a way that urban planners and policy makers can easily comprehend and that at the same time can be validated by specialists of the different science relevant fields : climatology, meteorology, building energy, environment and social sciences...

Local Climate Zones (LCZ) have proven their usefulness as an easy to use and scientifically founded concept.

Several methods aim at classifying a territory into LCZ, and a few workflow even allow an automatic classification. These methods produce maps which are often similar, but may show some differences, due to input data or implemented algorithm.

Outside these technical considerations, to assess the impact of urban planning scenarios, one may also want to compare maps before and after the planned urban renovation projects.

Therefore, the need for automation of LCZ map comparison asks for an easy to use tool.

The `lczexplore` package is a free open-source package that allows to easily import, visualize, group and compare LCZ maps, even if they do not use the same spatial units / resolution. These LCZ maps can come from vector layers or raster layers. Five steps are usually performed by the tool:

1. The LCZ classifications (or any other qualitative variables) are imported from a file (geojson or shapefile format)

2. Each LCZ classification can then be visualized

3. Some LCZ levels may be grouped in broader categories

4. A pair of LCZ classifications (or qualitative variable maps) can then be compared:

- a map of agreement/disagreement is produced,

- the general agreement and a pseudo-kappa indicator of agreement are computed,

- the summed surface of each LCZ type is computed for each classification,

- a confusion matrix shows how the levels of one LCZ classification break up into the levels of the other

5. Influence of the level of confidence on the agreement between classifications is performed (sensitivity analysis)

To illustrate the use of LczExplore, we propose a study case where three different maps are compared :

- one created within the WUDAPT project, an approach using remote sensor data and machine-learning algorithm

- a second created using the GeoClimate software and geographical data provided by an institutionnal actor (the French National Geographical Institute)

- a third created using the GeoClimate software and crowdsourced geographical data (from OpenStreetMap).

The use of lczexplore package allows to easily visualize how the different map agree or differ, and gives insight on how methods can be complementary to each other, and how input data or algorithms could be improved in the future.

How to cite: Bocher, E., Gousseff, M., Jérémy, B., Le Saux Wiederhold, E., Alglave, B., and Kerjouan, E.: Comparison of different methods to produce local climate zone maps using the LczExplore tool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15984, https://doi.org/10.5194/egusphere-egu24-15984, 2024.

EGU24-16110 | ECS | Orals | CL2.5 | Highlight

Downscaling climate projections to map future outdoor thermal comfort in cities based on a deep learning approach 

Ferdinand Briegel, Simon Schrodi, Markus Sulzer, Thomas Brox, Andreas Christen, and Joaquim G. Pinto

Outdoor thermal comfort is influenced not only by meteorological variables air temperature, radiation and humidity at regional and local scales but also by local parameters such as mean radiant temperature and wind patterns, which vary at meter-scale within cities. All these factors can be affected by ongoing climate change. Hence, modelling future thermal comfort requires a multi-scale approach. Thermal comfort in outdoor settings can be quantified and described by thermal indices such as the Universal Thermal Climate Index (UTCI), which reflects the human response to environmental and physiological forcing. To date, several microscale modelling approaches have been proposed to model the meteorological and geometric variables that contribute to the UTCI, but they are all highly detailed, complex and computationally intensive. As a result, only individual heat waves, short case studies or single points have been modelled to estimate future heat stress conditions in cities.

This study introduces a novel and efficient deep-learning model that instantly and accurately predicts thermal comfort maps across entire cities and for long periods. This model is unique in its adoption of a solitary deep learning architecture, avoiding the use of sub-models that separately model, for example, air temperature or wind speed. We will refer to this model as the Unified Human Thermal Comfort Neural Network (UHTC-NN). Training and evaluation of the UHTC-NN is based on a machine learning model from a previous study, which combines four sub-models modelling air temperature, mean radiant temperature, wind speed, and relative humidity into UTCI. The UHTC-NN has a mean absolute error of 0.5 K compared to its preceding model. The UHTC-NN enables new applications of thermal comfort modelling, including meter-scale urban climate projection to support climate adaptation management in cities.

In a case study, we apply UHTC-NN to downscale 15 EURO-CORDEX climate projections with a 3-hour resolution over 30 years to generate high-resolution (1x1 m) street-level outdoor thermal comfort maps for the city of Freiburg, Germany. We compare the changes in UTCI frequency distribution and uncertainties of three different Representative Concentration Pathways (RCP2.6, 4.5 and 8.5) for the years 2070-2099 with the historical climate (1990-2019). Our study models the entire city center of Freiburg, with a domain size of 2.5x2.5 km, covering various aspects of the city's urban form. We show that the average number of hours per year with strong to extreme heat stress (UTCI >= 32°C) will increase up to three and six times for RCP2.6 and RCP8.5, respectively. The number of night-time hours with UTCI >= 20°C will increase by a factor of two and five, respectively for RCP2.6 and RCP8.5, compared to the 1990-2019 period. In addition, the 80th UTCI percentile shifts by 2°C and 4°C for RCP2.6 and RCP8.5, respectively. The presented high-resolution urban climate simulations allow us to identify intra-urban variability and daytime / nocturnal hot-spots where climate change will have the greatest impacts on outdoor thermal comfort. Such urban climate simulations therefore allow for an effective selection of areas where climate adaptation needs to be prioritized.

How to cite: Briegel, F., Schrodi, S., Sulzer, M., Brox, T., Christen, A., and Pinto, J. G.: Downscaling climate projections to map future outdoor thermal comfort in cities based on a deep learning approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16110, https://doi.org/10.5194/egusphere-egu24-16110, 2024.

EGU24-16326 | ECS | Posters on site | CL2.5

Integrating Quality Control and Data Gathering in Space-Time Analysis for Temperature Assessment in European Cities 

Setareh Amini and Stefan Brönnimann

Urban areas across Europe are facing unprecedented challenges from climate change, further intensified by the emergence of urban heat islands (UHIs). The resulting elevated temperatures within cities have profound implications for public health, energy consumption, and overall urban liveability. Climate adaptation and evidence-based urban planning that are needed to address these pressing issues require a better understanding of urban temperature dynamics. To address this pressing issue, our research aims to bridge a critical gap in our understanding of urban temperature dynamics through a comprehensive space-time analysis focused on 9 European cities. The primary emphasis at this stage is placed on the foundational step: collection, enhancement, and intercomparison of local temperature information. This initiative, which is part of the European COST-Action FAIRNESS (https://www.fairness-ca20108.eu/), is driven by the imperative need for accurate and localized data to inform evidence-based urban planning and climate adaptation strategies, highlighting the urgency and significance of our research.

 

We collected measurements from nine European cities, namely, Amsterdam, Basel, Bern, Biel, Turku, Rennes, Novi Sad, Birmingham, and Zurich The initial phase of the work involved the collection of raw data from different networks, encompassing varying time periods. The datasets exhibited considerable diversity in formats and temporal resolutions, necessitating meticulous handling. In parallel, metadata relevant to each dataset was collected. The primary step was to standardize all data into a common file format, with the Station Exchange Format (SEF) being the chosen standard. During this formatting process, a version with harmonized time resolution was generated, ensuring coherence across the datasets. Subsequently, a series of automatic quality control procedures were developed to systematically enhance the reliability and precision of the datasets. These procedures were designed to be universally applicable to all stations, promoting consistency in the assessment of temperature data. Additionally, for certain networks, a radiation correction was implemented to further refine the accuracy of the collected information.

 

Looking ahead, the datasets will be published, offering accessibility to urban planners and other stakeholders. The outcomes of this preliminary phase not only contribute to advancing space-time analysis in temperature assessment but also establish a robust foundation for subsequent research stages. The significance of this work resonates with urban planners, environmental scientists, and policymakers actively involved in crafting localized strategies for climate-resilient urban planning in European cities.

How to cite: Amini, S. and Brönnimann, S.: Integrating Quality Control and Data Gathering in Space-Time Analysis for Temperature Assessment in European Cities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16326, https://doi.org/10.5194/egusphere-egu24-16326, 2024.

At the end of the century, during the hot summer days, the thermal environment will be unbearable in most of the outdoor spaces of the cities. The few locations where the thermal environment will remain moderate will constitute heat shelters. The present study analyses the evolution of the quantity and the nature of the outdoor heat shelters, in a 27km2 central portion of the Lyon conurbation, during a hot summer day that is representative of the climate at the end of the century.

A specific methodology has been applied to perform such an analysis. The weather data for the representative hot summer day (RHSD) was selected within a database of weather projections made available by the CORDEX project. The RHSD represents weather conditions that may happen statistically once every 5 years, during the 14th of July, in Lyon, at the end of the century. Then, mean radiant temperature and operative temperature predictions were performed using the SOLWEIG micro-meteorological model. The heat shelters were defined as the outdoor locations where the operative temperature is below 37°C. With this definition, the heat shelters may not provide thermal comfort, but prolongated stays in the heat shelters would be safe for most of the population. The quantity of available heat shelters was measured through the heat shelter area per capita, which represents the total of the area covered by the heat shelters divided by the number of inhabitants in the domain.

During the RHSD, the heat shelters area goes below  per capita between 10:15 and 17:45, and reaches  between 15:00 and 16:00. During this period, the outdoor public domain is not able to provide heat shelters. This result suggests that people will have to adapt their way of life to the disappearance of heat shelters in the core of the afternoons, in order to avoid prolongated stays in the outdoor public environment.

The observation of the heat shelter maps reveals that, between 9:00 and at 19:00, the heat shelters are exclusively located within shaded areas. Continuous tree covers are more efficient than buildings to provide heat shelters: between 13:00 and 14:00, heat shelters are exclusively located in the core of the urban forests. In the streets, the capacity of shaded areas to provide heat shelters highly depends on the presence of surfaces (buildings façade or soil) that reflect the solar radiation toward the shaded areas. This result invites to rethink the way climate adaptation solutions should be designed in cities.

How to cite: David, D. and Salles, M.: Evaluation of the heat shelters availability in the city of Lyon, during a hot summer day at the end of the century., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16912, https://doi.org/10.5194/egusphere-egu24-16912, 2024.

EGU24-16969 | ECS | Orals | CL2.5 | Highlight

Modelled outdoor temperature effects and heat-related mortality impact of cool roofs and rooftop photovoltaics in London 

Charles H. Simpson, Oscar Brousse, Michael Davies, and Clare Heaviside

Population exposure to high temperatures poses health risks and increases mortality, but comprehensive studies comparing impacts of building and street levels interventions on air temperature at urban scales are still lacking. High-albedo roofs (also called “cool roofs”) can lower the air temperature in urban areas, compared to standard low-albedo roofs. As part of the transition to renewable power generation rooftop regional authorities in the UK have set targets for rooftop solar panel capacity, but some recent studies have argued that solar panels may increase urban temperatures and therefore have unintended consequences. Using advanced urban climate modelling (WRF BEP-BEM), we model the impact of these cool roofs and rooftop photovoltaics on urban air temperature during the record-breaking hot summer of 2018, and estimate the impact these measures may have on heat-related mortality.

We find that cool roofs and rooftop photovoltaics both decrease modelled daily-mean temperature compared to standard low-albedo roofs. Rooftop photovoltaics may reduce heat-related mortality by 96 (12%), or cool roofs by 249 (33%), in scenarios where all roofs have these measures. Monetised using value of statistical life, we estimate benefits for solar roofs and cool roofs of £237M and £616M respectively for London July-August 2018 conditions, and we estimate 20 TWh of electricity, worth £3-6 billion, would be generated in the rooftop PV scenario. Our modelling indicates that, in the conditions of London July-August 2018, rooftop PV or cool roofs may reduce near-surface air temperatures and therefore heat related mortality, with cool roofs having a larger effect.

How to cite: Simpson, C. H., Brousse, O., Davies, M., and Heaviside, C.: Modelled outdoor temperature effects and heat-related mortality impact of cool roofs and rooftop photovoltaics in London, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16969, https://doi.org/10.5194/egusphere-egu24-16969, 2024.

EGU24-17406 | ECS | Orals | CL2.5

Climate sensitive designs for policy makers: how well can LES models represent urban microclimates? 

Leyla Sungur, Wolfgang Babel, Eva Spaete, and Christoph Thomas

Cities can offer an extraordinarily high or low urban level of climatic stressors depending on their location and topographical setting, infrastructural geometry and anthropogenic activities. To protect human well-being today and in the future, it is crucial to better understand how to mitigate temperature extremes in cities. Since cities are constantly growing and transforming in response to their residents’ needs, planning a foresighted sustainable climate-friendly infrastructure is critical. This need creates a niche for research to assess local climate effects that effect the lower atmosphere ground layer where human activity takes place. Large Eddy Simulation (LES) models can simulate heat transport and mixing processes by directly resolving large-scale turbulence and are often used to simulate urban development activities potentially mitigating the adverse effects of heatwaves in cities. Despite their growing use in forming recommendations, these models are inherently difficult to validate which leads to ‘simply believing them’.

We evaluate the performance of an urban LES model against a reference multi-station observational network focusing how well the space-time dynamics of distinct urban microclimate including densely-built hot spots, peri urban and park-cool islands agree. We selected a 72-hour extreme heatwave period in July 2019 in a mid-sized city in Germany which suffers from a similarly large urban heat island effect as larger cities. We investigated air temperature, air humidity, wind speed and direction as key elements impacting the perceived heat stress or relief by humans. Observations were compared to the PALM-4U LES model with a nested domain dynamically driven by the mesoscale COSMO-D2 output by the German Meteorological Service at spatial resolutions of 20 m and 5 m domain. We employed the stochastic multiresolution decomposition (MRD) technique applied to two-point correlation statistics for characterizing the space-time behavior.

Absolute air temperatures differences amounted to +5 K overestimation of modeled nocturnal air temperatures. A key finding from the MRD analysis is that correlation between stations does not follow separation distance (as expected for homogeneous domains) but rather the distinct urban microclimatic for air temperature and specific humidity in both observations and model at both resolutions. Separating the results into day and night shows distinct differences for air temperature and specific humidities for both model resolutions compared to the observations, but only small differences for near-surface winds. The model performance varies with its resolution and climate element: while winds are better represented in the finer 5 m resolution, specific humidity cannot be simulated properly by the model at night. Air temperature during day is better represented by the 20 m resolution, while the match between observations and the 5 m-prediction is better at night.

We show that the LES model can simulate the statistical space-time behavior of urban microclimates but performs poorly when absolute targets are modeled. Simulated air temperature and specific humidity follow mostly the implemented synoptic advective forcing large scale model which does not recognize local microclimatic effects. For near-surface winds, this model performs better with finer resolution as the larger eddies resolved depend on the geometry of the city.

How to cite: Sungur, L., Babel, W., Spaete, E., and Thomas, C.: Climate sensitive designs for policy makers: how well can LES models represent urban microclimates?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17406, https://doi.org/10.5194/egusphere-egu24-17406, 2024.

EGU24-17510 | ECS | Posters virtual | CL2.5

Exploring the impact of Local Climate Zones to the efficacy of cooling materials at the urban scale 

Nikolaos Michail Stavrianos, Ilias Agathangelidis, Constantinos Cartalis, and Christos Giannaros

The Mediterranean region is an exceptionally thermally vulnerable area, projected to suffer from frequent and severe heatwaves in the coming decades. Numerical simulations enable a comparative assessment of different heat adaptation strategies. Additionally, the Local Climate Zone (LCZ) scheme allows a standardized classification of urban neighbourhoods depending on their urban form. In this work, high resolution microscale simulations using ENVI-met are conducted for Athens, Greece, under typical summer conditions (simulated by the Weather Research and Forecasting model) and idealized configurations of high density LCZs 2 and 3. For each LCZ, a total of four simulations are performed, starting from the base situation and three additional scenarios where cooling materials are applied on ground surfaces and/or rooftops. Each scenario is assessed in terms of the reduction in air temperature within the simulation area. Findings indicate that the efficacy of cooling materials varies depending on LCZ characteristics. Understanding these differences is necessary for implementing targeted strategies to mitigate urban overheating for specific urban settings.

How to cite: Stavrianos, N. M., Agathangelidis, I., Cartalis, C., and Giannaros, C.: Exploring the impact of Local Climate Zones to the efficacy of cooling materials at the urban scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17510, https://doi.org/10.5194/egusphere-egu24-17510, 2024.

EGU24-17816 | Posters on site | CL2.5

Quantifying Adaptation Measures for Thermal Stress in German Cities using the Microscale Urban Climate Model PALM-4U: Insights from the UrbanGreenEye Project 

Mohamed Salim, Sebastian Schubert, Sebastian Lehmler, Benjamin Stöckigt, Annett Frick, and Galina Churkina

The UrbanGreenEye project is a collaborative research initiative focusing on monitoring urban areas for climate change adaptation using remotely sensed indicators. The project addresses the critical need for comprehensive and accessible data to support sustainable urban development. In the context of climate change adaptation, the project recognizes the challenges faced by local civil services in obtaining timely and cost-effective information about urban structures. This study presents the crucial role of the microscale building-resolving urban climate mode PALM-4U in quantifying the effectiveness of vital indicators derived from Earth Observation, such as land surface temperature (LST), urban green volume, vegetation vitality, and imperviousness. For instance, the implementation of PALM-4U enables a detailed deficit analysis of urban green volume, allowing for the identification of areas experiencing thermal and hydrological stress. The model PALM-4U is used in validating greening scenarios, providing valuable insights for urban planners and decision-makers in formulating effective adaptation measures. Recognizing the inherent uncertainties in satellite-based calculations of indicators, the model PALM-4U investigates the impact of these uncertainties on the accuracy of PALM-4U simulations. By employing artificial intelligence algorithms, including Convolutional Neural Networks (CNN) and Long Short-Term Memory (LSTM) models, the UrbanGreenEye project aims to enhance the reliability of satellite-derived data for improved urban climate modeling. Through collaboration with nine partner municipalities, this research contributes to bridging the gap between remote sensing capabilities and local authorities' needs. The outcomes of this study will facilitate the creation of a robust model for urban green volume deficiency, identifying hotspots for adaptation measures and supporting evidence-based urban planning strategies. Additionally, urban areas, influenced by the urban heat island effect, experience elevated surface and air temperatures due to factors such as increased solar absorption, lack of vegetation, and human activities. The model PALM-4U is used to explor the relationship between surface and air temperatures. Understanding this correlation is crucial for informing decisions by city planners and policymakers to mitigate the urban heat island effect. The insights gained also aid meteorologists in accurate temperature predictions for urban areas and contribute to scientific understanding of temperature dynamics, providing valuable perspectives on the potential impacts of climate change on future cities. Ultimately, the assessment of remotely sensed indicators using the model PALM-4U within the UrbanGreenEye project is considered a considerable step towards enhancing the resilience of urban areas to climate change.

How to cite: Salim, M., Schubert, S., Lehmler, S., Stöckigt, B., Frick, A., and Churkina, G.: Quantifying Adaptation Measures for Thermal Stress in German Cities using the Microscale Urban Climate Model PALM-4U: Insights from the UrbanGreenEye Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17816, https://doi.org/10.5194/egusphere-egu24-17816, 2024.

EGU24-18972 | Posters on site | CL2.5

Extreme heat hazard in the urban areas of Romania in a changing climate 

Dana Magdalena Micu, Sorin Cheval, Alexandru Dumitrescu, Raluca Smău, and Vlad Amihăesei

Cities emerge as particularly vulnerable environments to climate extremes, exacerbated by the observed climate change These environments are human heat stress hotspots due to the amplified contribution of the urban heat island effect and joint action of extreme weather events  The study aims to detect and quantify the changing signals in the combined heat hazard (CHH), associated with concurrent hot days (HD - maximum temperature above 30˚C) and nights (HN - minimum temperature above 20˚C) in 40 large cities of Romania (>100,000 inhabitants), including the capital city. CHH is highly relevant in the assessment of heat-health risk through its inhibiting influence on the recovery from daytime heat stress and exacerbation of the extreme heat impact through sleep deprivation at night. We use homogenized climate observations (1961-2021) and ensemble EUROCORDEX simulations (RCP4.5, RCP8.5), for the near future (2021-2050) and far-future (2071-2100), to analyse the temporal changes in two CHH metrics: CHHf - frequency (number of co-occurrences of HD and HN), and CHHl - length (the maximum number of consecutive co-occurrences of HD and HN). The results show consistent geographical patterns in the change signals of the CHH metrics, over both present and future climates. The strongest change signals in CHH, as well as the most pronounced projected changes, especially in the far-future under RCP8.5 are found in the cities located in the southern, eastern and western lowlands of the country (i.e., Bucharest, Giurgiu, Iasi, Timisoara).

These cities show strong increases in both frequency and duration of CHH, almost doubling by 2050 and even more by 2100. These results are suggestive of a consistent amplification and northward expansion of the areas prone to CHH (i.e., cities located in the central and northern parts of the country).

The correlations between the temporal variability of CHH and the cooling degree days provide an improved understanding of the relationship between energy consumption and prevailing climatic conditions during the extreme heat episodes in urban areas, under both present and future climate warming. The study provides valuable insights into the urban heat hazard and provides science-based evidence that could be used for assessing the heat-health risk at the city scale and optimisation of decision-making for climate change adaptation. 

This study has been funded by the project Synergies between Urban Heat Island and Heat Wave Risks in Romania: Climate Change Challenges and Adaptation Options (SynUHI) PN-III- P4-PCE-2021-1695 

 

How to cite: Micu, D. M., Cheval, S., Dumitrescu, A., Smău, R., and Amihăesei, V.: Extreme heat hazard in the urban areas of Romania in a changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18972, https://doi.org/10.5194/egusphere-egu24-18972, 2024.

EGU24-19264 | Posters on site | CL2.5

Sub-daily Land Surface Temperature data for urban heat monitoring from spaceenhanced by machine learning 

Christian Mollière, Lukas Kondmann, Julia Gottfriedsen, and Martin Langer

Urban heat islands are becoming a major health factor for cities in the eye of a warming planet. Fueled by impervious surfaces and rising temperatures, extreme heat may lead to 235,000 emergency room visits and 56,000 hospital admissions annually in the US alone in 2023 [1]. Beyond its economic impact, urban heat therefore puts a strain on wellbeing and health across the globe with visible effects on mortality.

Urban planning aims to mitigate extreme heat in cities, a challenge intensified by urban densification and climate change. However, accurately predicting and managing urban heat is complex due to the difficulty in measuring local physical processes, particularly in dynamically changing environments. The scarcity of granular measurements of land surface temperature compounds this issue. While satellite imagery from thermal instruments offers some assistance, traditional data sources often lack the necessary temporal density of observations. Rapid diurnal temperature fluctuations necessitate near-real-time monitoring for effective decision-making and a comprehensive understanding of urban temperature dynamics.

New Space constellations with higher temporal cadence are starting to close this data gap with enormous potential for urban development as well as extreme heat event anticipation. For example, OroraTech’s Forest constellation allows frequent observation of urban areas. With 2 satellites operating in orbit and 9 more planned to launch in 2024, we aim to provide Land Surface Temperature (LST) every 12 hours globally. Once our full constellation is operational in 2027, the update frequency will again improve to sub-hourly.

The native spatial resolution of Forest data at 200m is, however, a challenge for urban applications. We are currently exploring enhancing our imagery with artificial intelligence approaches to 70m to get from city quarter to building block level. These super-resolution techniques are the result of recent advancement in AI and image processing with promising results on our thermal data. Yet, the usability of super-resolved data for urban policy is underexplored. We aim to present preliminary findings of the accuracy of our super-resolution method compared with higher resolution Ecostress data and investigate the applicability of the results for urban planning as well as extreme heat event analysis. With this, we aim to help cities to mitigate and adapt to the new public health challenges as a result of extreme heat.

[1]: Yale Program on Climate Change Communication, 2023 https://yaleclimateconnections.org/2023/07/extreme-heat-will-cost-the-u-s-1-billion-in-health-car e-costs-this-summer-alone/

How to cite: Mollière, C., Kondmann, L., Gottfriedsen, J., and Langer, M.: Sub-daily Land Surface Temperature data for urban heat monitoring from spaceenhanced by machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19264, https://doi.org/10.5194/egusphere-egu24-19264, 2024.

EGU24-19271 | Posters on site | CL2.5

Compound impact of extreme summer heat waves and droughts on surface urban heat island in Budapest 

Zsuzsanna Dezső and Rita Pongrácz

The aim of our research is to investigate how heat waves affect the surface urban heat island (SUHI) phenomenon in Budapest, a mid-latitude city with significant year-to-year differences in temperature and precipitation. A unique, 22-year long time series of continuous measurements from the MODIS instrument on NASA's Terra and Aqua satellites was used to study the SUHI pattern, surface temperature and humidity in detail. The two decades of surface temperature data show a significant warming trend. Analysis of the summers shows that the SUHI intensity decreases as the rural area around the city becomes warmer, especially in July and August, as the less moisture available in the rural area is unable to reduce the surface temperature, similar to the urban area. Thus, the SUHI intensity is mainly determined by the rural surface temperature. During summers with frequent and intense heat waves and droughts, the SUHI is very weak because the land surface temperatures are very high in both urban and rural areas resulting in very little difference between the built-up area and the vegetation-covered surrounding. In our research, we analyse this phenomenon in detail for the years 2003, 2007 and 2022, when intense heat waves occurred in the region. Due to climate change, heat waves and droughts are projected to become more frequent, more intense and more persistent in the future, which is likely to result in adverse effects to the quality of life of urban populations. A detailed analysis aiming to understand the complex environmental processes in the urban environment is essential to develop effective adaptation strategies to the upcoming challenges of climate change.

Acknowledgements: Research leading to this study has been supported by the Hungarian National Research, Development and Innovation Fund (under grant K-129162) and the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014).

How to cite: Dezső, Z. and Pongrácz, R.: Compound impact of extreme summer heat waves and droughts on surface urban heat island in Budapest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19271, https://doi.org/10.5194/egusphere-egu24-19271, 2024.

EGU24-19427 | ECS | Orals | CL2.5

High spatio-temporal monitoring of weather and outdoor thermal comfort in urban environments: A modular sensor network, first year data and outreach 

Gregor Feigel, Marvin Plein, Matthias Zeeman, Dirk Schindler, Andreas Matzarakis, Swen Metzger, and Andreas Christen

Timely information on the effects of the increasing intensity, frequency and duration of heatwaves on cities and critical infrastructure is needed for warning, emergency management and for developing context-specific climate adaptation strategies. Aside from the challenge of deploying sensor networks within built environments, there are hardly any operational city-wide networks that continuously measure and communicate human thermal comfort indices in public spaces. 

To address this gap, a two-tiered weather and outdoor human thermal comfort monitoring network was developed and deployed in Freiburg in 2022. The monitoring network comprises a total of 42 automatic weather stations primarily mounted on public lamp posts at a height of 3 m, with the Tier-I network consisting of 13 customised stations, which are equipped with an in-house developed data logging unit optimised for this application, that is extend by a spatially dense but less complex Tier-II network consisting of 29 commercial weather stations. Both networks collect data on air temperature, humidity and precipitation, with the Tier-I network providing additional data on wind, radiation, pressure, lightning, solar radiation and black-globe temperature to calculate human-biometeorological thermal indices such as the Physiological Equivalent Temperature (PET). 

Over the course of the first year of deployment (01-Sept-2022 to 31-Aug-2023), the stations have continuously collected high-resolution data (30 and 60 sec) with only little data loss. In a case study, the intra-urban differences in thermal comfort were analysed during the hot month of July 2023, in which five official heat warnings were issued by the German Meteorological Service (DWD). The results show expected intra-urban and urban-rural contrasts and that mid-density sites experience the highest number of summer days, totalling 22, compared to 19-20 in the city centre. The highest amount of moderate heat stress and higher (PET > 29°C) was observed in FRLAND (26,3%) compared to 13-19% at rural sites. Also more tropical nights were observed at inner city sites with 5-6, compared to 3 at outer, primarily suburban sites. Remote and rural sites reported no tropical nights. 

Over the full annual cycle and the entire network, the number of tropical nights ranged between 0 (rural) and 29 (inner city) per year. The highest number of summer days per year was recorded in industrial and suburban areas (up to 101) compared to 84-97 days in the city centre and 62-90 days at rural sites. The average annual air temperatures reveal a distinct long-term heat island with an annual mean temperature up to 14.0°C in the city centre, and 11.6°C - 12.7°C at rural sites of same elevation.

These results highlight the benefit of continued monitoring for real-time assessments, efficient identification of hot-spots for climate adaptation strategies, and model evaluation and to improve our understanding of urban heat islands and human thermal comfort patterns. In addition, an outreach platform and mobile app (uniWeatherTM) have been developed to provide end-users and the public with free access to real-time data and interpretation following FAIR principles.

How to cite: Feigel, G., Plein, M., Zeeman, M., Schindler, D., Matzarakis, A., Metzger, S., and Christen, A.: High spatio-temporal monitoring of weather and outdoor thermal comfort in urban environments: A modular sensor network, first year data and outreach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19427, https://doi.org/10.5194/egusphere-egu24-19427, 2024.

The third United Nations Conference on Housing and Sustainable Urban Development (HABITAT-III) in October 2016 adopted the New Urban Agenda (United Nations, 2017), which brings into focus urban resilience, climate and environment sustainability, and disaster risk management.
Following the event at the United Nations Economic and Social Council, efforts are required from WMO to consolidate its input to the revision of the New Urban Agenda (NUA) and support urban related activities in a comprehensive manner. Urban development is now a cornerstone of the United Nations 2030 Sustainable Development Goals. It has its own sustainable development goal (SDG 11): Make cities inclusive, safe, resilient and sustainable.
To support implementation of urban activities the WMO inter-programme Urban Expert Team under the Commission for Atmospheric Sciences and Commission for Basic Systems (2018) supported by a dedicated team of urban focal points in the Secretariat developed the Guidance on Integrated Urban Hydro-Meteorological, Climate and Environmental Services (IUS). The needs for integrated urban services (IUS) include information for short-term preparedness (e.g. hazard response and early warning systems), longer-term planning (e.g. adaptation and mitigation to climate change) and support for day-to-day operations (e.g. water resources). The aim is to build urban systems and services that meet the special needs of cities through a combination of dense observation networks, high-resolution forecasts, multi-hazard early warning systems, disaster management plans and climate services. This approach gives cities the tools they need to reduce emissions, build thriving and resilient communities and implement the UN Sustainable Development Goals.

The ways and approaches, as well as priorities for relization of such systems depend on specific climatic, geographical, economical and environmental conditions specific cities. In this presentation we will classify and concider different approaches, methodologies and tools for selected cities in different climate zones (e.g. northern, tropical), economical conditions (developed and developing worlds) and combinations of risk factors (e.g., multi-hazards, heat stress, floods, air quality). Specific focus will also be done on the mitigation and adaptation strategies and their combinations. 

How to cite: Baklanov, A.: Integrated Hydrometeorology, Climate and Environmental Systems and Services for Sustainable Cities: Approaches for different regions and countries. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19983, https://doi.org/10.5194/egusphere-egu24-19983, 2024.

Extreme weather conditions associated with climate change could impact urban living in many ways. These conditions include flooding caused by extreme rainfall events and tidal surges caused by super tropical cyclones. Among these weather extremes, the extreme regional calm wind condition (ERCWC or weak synoptic forcing condition) relevant to air pollution has been less studied. Meanwhile, current urban planning guidelines for air quality consider only prevailing weather conditions without taking extreme weather into account. The current computational fluid dynamics (CFD) study examines urban air pollution dispersion under the influence of urban heat associated with ERCWC. First, our large-eddy simulation (LES) turbulent model results were validated with the results of the ETH Zürich Atmospheric Boundary Layer Water Tunnel experiment. We then examined the simulated airflow patterns and dispersion patterns inside representative urban parametric models. The National Supercomputing Centre Singapore provided all computing resources for our simulations. The adopted parametric models were developed based on urban density analysis to reflect the real urban morphology of Singapore. The models consist of nine building clusters, each containing 24 generic building blocks. The study compared the prevailing wind scenario with calm scenario driven by buoyancy. Inlet boundary conditions for the former and latter scenarios were determined by using the annual-average wind velocity measured at an urban weather station and zero wind velocity, respectively. In the latter scenario, ground and building surfaces were set at 5°C above ambient temperatures, which is within Singapore's measured values. There were a total of four sources of line emission in the computational domain. New insights and implications were found regarding urban air dispersion within the urban canopy layer for the buoyancy-driven scenario (the ERCWC) over the prevailing wind scenario. Wind reversal at certain areas for the buoyancy-driven scenario is an example, which leads to upwind sites to become downwind sites. We recommend upgrading the current guidelines for urban planning to improve urban resilience during extreme weather conditions by implementing mitigation measures, some of which were discussed in this study.

How to cite: Wai, K.-M. and Yuan, C.: On the modification of neighbourhood-scale atmospheric dispersion within urban morphologies by the buoyancy effect - a CFD study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21451, https://doi.org/10.5194/egusphere-egu24-21451, 2024.

EGU24-22023 | Posters on site | CL2.5

Mitigating Urban Heat Island Intensity in Urban Environments by optimal control method 

Waleed Mouhali, Nacer Sellila, Mohammed Louaked, and Houari Mechkour

Climate in urban areas differs from that in neighboring rural areas, as a result of urban development. It can create issues. Among these disturbances, Urban Heat Island (UHI) is a huge risk with many negative consequences (health, comfort...). It concerns urbanized area where temperatures are higher than in surrounding areas. To reduce this effect, the implantation (and design) of green spaces in dense cities is a pertinent solution.

In this study, we use optimal control method to find the optimal shape of green space. We consider city as a porous media system. Therefore, a three-dimensional model is established for numerical studies of the effects of urban anthropogenic heat and wind velocity in urban and rural regions. The transport mechanism of fluid in the cities is governed by the Navier–Stokes–Forchheimer porous media system. It is actually based on non-stationary turbulent fluid dynamics coupled with heat equation considering building/soil radiation effects.

We compute two-dimensional direct numerical simulation. We show the results for temperature and velocity fields. This work presents the governing equations, the control optimal algorithm and discusses the results of the predictions of the flow problems constituting the initial validation space of the model.

How to cite: Mouhali, W., Sellila, N., Louaked, M., and Mechkour, H.: Mitigating Urban Heat Island Intensity in Urban Environments by optimal control method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22023, https://doi.org/10.5194/egusphere-egu24-22023, 2024.

EGU24-22059 | Orals | CL2.5 | Highlight

New directions for urban climate science 

Gerald Mills and Evyatar Erell

The study of urban climates is at a critical juncture in its development as its subject matter is viewed as increasing relevant to a number of intersecting concerns across a hierarchy of scales. These concerns include global climate change and its drivers and consequences, which are focused on cities where most reside. Addressing these concerns requires an integrated science of cities, which does not yet exist. Our current urban climate knowledge framework developed as a series of specialist endeavours concentrating on aspects of the outdoor and of the indoor environments. As a result, much of the training, methodologies, technical language and data that are associated with these specialist fields are distinct and not easily transferable. In the climate field, there is a clear division between the outdoor and indoor climates and addressing each independently makes it difficult to find solutions to urban challenges, such as achieving zero Carbon cities. Moreover, the lack of a common framework causes confusion when articulating findings. As examples, the urban canopy layer (UCL) in urban climatology commonly refers to the outdoor space below roof level and is bounded by the ground, the walls of adjacent buildings and the interface at roof level; the walls are also part of the indoor canopy, which is bounded by the walls and the roof. Clearly these spaces are strongly connected by exchanges of energy and mass and by the movement of people across the wall interface, yet these receive little attention. In this presentation we will discuss the emergence of indoor and outdoor climate sciences and the potential for integration within an urban climate science.

How to cite: Mills, G. and Erell, E.: New directions for urban climate science, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22059, https://doi.org/10.5194/egusphere-egu24-22059, 2024.

EGU24-22073 | Posters on site | CL2.5

Urban Climate Observatory (UCO) Berlin, Germany 

Fred Meier, Achim Holtmann, Marco Otto, and Dieter Scherer

The Urban Climate Observatory (UCO) Berlin is an open and long-term infrastructure for integrative research on urban weather, climate, and air quality. Quality-controlled observations are carried out in order to study the interaction between atmospheric processes and urban structures, as well as climate variability and climate change in urban environments. It enables multi-scale, three-dimensional atmospheric studies integrating observational and numerical modelling methods. The UCO Berlin includes the following components:

The Urban Climate Observation Network (UCON) Berlin provides long-term observations of atmospheric variables (air temperature, relative humidity, air pressure, global radiation, wind, precipitation) in the Urban Canopy Layer (UCL) at various locations since the 1990s. Since 2015 freely available data from Netatmo weather stations in Berlin and surrounding have been systematically collected (Crowdsourcing).

The meteorological towers are located in the garden of the Institute of Ecology at Rothenburgstraße (ROTH) in Berlin-Steglitz since 2018 and on the roof of the main building of the TU Berlin at Campus Charlottenburg (TUCC) since 2014. Turbulent fluxes of sensible and latent heat as well as carbon dioxide are derived from eddy covariance (EC) systems, which combines an open-path gas analyzer and a three dimensional sonic anemometer-thermometer (IRGASON, Campbell Scientific). The EC-systems at ROTH are installed at 40 m, 30 m, 20 m, 10 m and 2 m above ground and at TUCC at 10 m above roof (56 m above ground). The down- and upwelling radiation is measured separately for short-wave and long-wave radiation (CNR4, Kipp & Zonen) at the same heights as the EC-systems. The seasonal development of vegetation is observed at both tower locations using phenocams part of the international PhenoCam (phenocam.nau.edu) network. The ROTH tower is an associate site of the European research infrastructure Integrated Carbon Observation System (ICOS) and part of the national ICOS-D network (ID: DE-BeR).

Ground-based remote sensing is used to study the urban boundary layer since 2017. The UCO Berlin operates two Doppler LiDAR systems (Streamline XR, Halo Photonics) and provide profiles of the horizontal wind speed and wind direction as well as information on atmospheric turbulence. Cloud height, cloud cover and aerosol layers are recorded with ceilometers (CHM 15k, Lufft) at sites Grunewald and TUCC, which is part of the E-Profile Network of the European meteorological services EUMETNET. The ceilometer range is 15 km, the vertical resolution is 15 m and the temporal resolution is 15 s. A microwave radiometer (HATPRO-G5, RPG Radiometer Physics GmbH) provides vertical profiles of air temperature and absolute humidity up to an altitude of 10 km. Integrated liquid water path (LWP) and the integrated water vapor (IWV) are derived from measurements of the brightness temperature in 14 channels. An X-band Doppler weather radar with dual polarization (GMWR-25-DP, GAMIC) for precipitation research is in operation since autumn 2022 and has a range of 100 km.

The website of the UCO Berlin provides a data portal for search of meta data and download of open climate data in Berlin and surrounding: https://uco.berlin

How to cite: Meier, F., Holtmann, A., Otto, M., and Scherer, D.: Urban Climate Observatory (UCO) Berlin, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22073, https://doi.org/10.5194/egusphere-egu24-22073, 2024.

EGU24-4732 | PICO | CL2.6

Approaching 1.5°C: What is the Current Global Warming Level? 

Richard Betts, Stephen Belcher, Leon Hermanson, Albert Klein Tank, Jason Lowe, Chris Jones, Colin Morice, Nick Rayner, Adam Scaife, and Peter Stott

It will be important to know when global warming has reached 1.5°C, as this will be a key marker in global policy given the ambition to pursue efforts to limit warming to this level. But how should the temperature increase be defined in this context? The Global Stocktake agreed at COP28 in Dubai noted “global warming of about 1.1 °C” based on the IPCC 6th Assessment Report, but this number applies to the average of 2011-2020 and hence is already out of date. We propose that the metric for current global warming should allow immediate of identification of passing particular levels of global warming, such as 1.5°C, to avoid unnecessary delays in responding to the exceedance. We also propose that the metric should be consistent with the definition of future Global Warming Levels in the IPCC 6th Assessment Report, which uses 20-year means of projected temperature anomalies with an exceedance year defined as the mid-point of the 20-year period. Without this consistency, the apparent time of reaching 1.5°C could differ from the time previously projected by the IPCC merely because of differences in the definition, which could be misinterpreted as indicting that global warming had reached 1.5°C either earlier or later than projected. This could either undermine confidence in projections or misinform discussions on action to address climate change.

While various indicators are already in use that provide a more instantaneous measure of global warming, none are consistent with the IPCC definition of future GWLs nor are suitable for use as a baseline for impacts assessments. To address this, we propose a new metric, the Current Global Warming Level (CGWL), which uses a 20-year average over the previous 10 years from observations and the next 10 years from a forecast or projections. Here we compare the CGWL with the various indicators currently in use for quantifying the current level of global mean temperature change, and compare their indications of global temperature change over recent decades and of the current level of global warming. We also compare the year of exceeding past global warming levels of 0.5°C, 1.0°C and 1.2°C for each indicator. We use a combined observational dataset following IPCC methods and process the indicators from this. For each indicator, we explain potential difficulties that could arise from its use to assess when global warming reaches 1.5°C relative to pre-industrial, and explain the rationale for our proposed indicator, the Current Global Warming Level.

How to cite: Betts, R., Belcher, S., Hermanson, L., Klein Tank, A., Lowe, J., Jones, C., Morice, C., Rayner, N., Scaife, A., and Stott, P.: Approaching 1.5°C: What is the Current Global Warming Level?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4732, https://doi.org/10.5194/egusphere-egu24-4732, 2024.

EGU24-5499 | PICO | CL2.6

Destinations of Climate Monitoring information: State of the Climate reports 

Jessica Blunden, Robert Dunn, and John Kennedy

One of the goals of climate monitoring is to ensure that the ongoing changes in the Earth's climate system are placed in context against longer-term changes and are clearly and widely communicated.  There are a number of reports produced on an annual basis which collate and synthesise the outputs from climate monitoring products for a range of essential climate variables (ECVs) and extreme climate events.  Among the most highly regarded peer-reviewed global-scale publications, a provisional version of the World Meteorological Organisation (WMO) State of the Global Climate report feeds into the United Nations Framework Convention on Climate Change Conference of the Parties (UNFCCC COP) process each year, directly informing policy makers and stakeholders about the current state of several key climate metrics.  The more comprehensive BAMS State of the Climate report is an almanac of the major events of each year and an assessment of more than three-dozen ECVs that encompass Earth's land, oceans, cryosphere, and atmosphere, which provides a useful reference document for a wide range of stakeholders, from the general public to educators to private and public decision makers.  In this presentation we outline the process behind each report, the wide range of information they contain, and give pointers on how to get more involved.

How to cite: Blunden, J., Dunn, R., and Kennedy, J.: Destinations of Climate Monitoring information: State of the Climate reports, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5499, https://doi.org/10.5194/egusphere-egu24-5499, 2024.

EGU24-5536 | PICO | CL2.6

A multi-dataset trend analysis of precipitation characteristics over Europe 

Romana Beranova and Radan Huth

Understanding long-term changes in precipitation is essential for climate research. However, it is a well-established fact that various types of data (station, gridded, reanalysis) can yield different results in extreme and trend statistical analyses. In this contribution, we investigate the long-term changes in precipitation characteristics across different data sources, focusing on the European land area. Our study incorporates station data from the ECA&D project, station data interpolated onto a regular grid (Eobs, Regen) and reanalyses (NCEP/NCAR, 20CR, ERA5). The objective is to explore the seasonal trends of precipitation total amounts, intensity, and probability. The analysis concentrates on the long-term trends of these precipitation characteristics from 1961 to 2010, with emphasis on winter and summer. Trends are estimated using the nonparametric Sen’s slope estimator, and the Mann-Kendall test is applied to assess the statistical significance of these trends. In general, a similar trend pattern is evident within the ECA&D, Eobs and ERA5 datasets. Conversely, the NCEP/NCAR and 20CR reanalyses exhibit the most significant disparities in trends for all precipitation characteristics. Our aim is not only to identify differences between the data sources but also to pinpoint the causes behind these differences.

How to cite: Beranova, R. and Huth, R.: A multi-dataset trend analysis of precipitation characteristics over Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5536, https://doi.org/10.5194/egusphere-egu24-5536, 2024.

EGU24-5945 | ECS | PICO | CL2.6

Susceptibility of the Iberian Peninsula to extreme precipitation and aridity: a high-resolution analysis for 1950–2022 

André Claro, André Fonseca, Helder Fraga, and João Santos

This study consisted of the assessment of the Iberian Peninsula’s (IP) susceptibility to precipitation extreme events (PEE) and aridity across a long historical period of 1950–2022 and a shorter period of 1981–2022, based on the calculation of eight extreme precipitation and two aridity indices. Furthermore, two recently developed extreme precipitation susceptibility indices were also applied, namely a composite index and a principal component analysis-based index. ERA5-Land reanalysis data were used for those calculations, previously bias-corrected with the Iberia01 observational dataset as a baseline in their overlapping period of 1971–2015, following a quantile-mapping approach. A trend analysis performed for the two periods reveals an annual and seasonal drying trend over southwestern, central, and northeastern regions, as well as a wetting trend over the southeast annually. Regarding the PEE contribution to total precipitation (which is higher over eastern IP, and around 24% to 28%), it is increasing in several coastal regions during winter, and in north-central regions during summer and annually. High to very high susceptibility areas, which correspond to approximately 50% of the IP, are located on the mountains’ Atlantic-facing (western IP mountains) or Mediterranean-facing (eastern IP mountains) side, while the inner IP plateaus reveal low to moderate susceptibility. Our results agree with previous studies and show with high detail the susceptibility to PEEs and the recent past trends of all IP regions, which is a novelty comparatively to those studies. This highly detailed information can be used, e.g., to improve the assessment and mitigation of urban flood risks, mitigate water scarcity in the agro-food industry, or prevent crop destruction during extreme precipitation events.

How to cite: Claro, A., Fonseca, A., Fraga, H., and Santos, J.: Susceptibility of the Iberian Peninsula to extreme precipitation and aridity: a high-resolution analysis for 1950–2022, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5945, https://doi.org/10.5194/egusphere-egu24-5945, 2024.

EGU24-11518 | ECS | PICO | CL2.6

High-resolution climate reanalyses datasets for hydro-climatic impact studies over Switzerland 

Raul R. Wood, Joren Janzing, Amber van Hamel, Jonas Götte, Dominik Schumacher, and Manuela I. Brunner

To study and model hydro-climatic extremes (e.g., droughts and floods), high quality, multivariate and spatially consistent meteorological datasets are necessary. In-situ measurements, however, often don`t cover these multivariate data needs, and are variable in space and time. New generations of high-resolution reanalysis products, with continental to global scales, are available that offer a wide range of internally consistent land surface variables. However, it is yet unclear which of these datasets are most suitable for hydro-climatic impact studies, e.g., to assess the spatiotemporal connectedness of floods and droughts, or to quantify the multivariate meteorological drivers of these extremes. Here, we present a comparison of multiple high-resolution reanalysis datasets (i.e., ERA5(-land), CERRA(-land) and CHELSA-v2) with a gridded observational product from MeteoSwiss. We compare various climatological statistics of precipitation and temperature, such as differences in the mean and the tails of the distribution, as well as the consistency of temporal trends and interannual variability. We further analyze differences in selected univariate and multivariate climate indicators, such as the annual maximum 1–5-day precipitation, the number of dry/wet days, or the fraction of solid/liquid precipitation. Lastly, we present the spatiotemporal consistency of several observed hydro-climatological extreme events, including the drought in 2018 and the floods in 2005 over Switzerland.

For most of the reanalysis products the analysis shows a clear elevational dependence in the biases, i.e., increasing with elevation, compared to the gridded observational dataset. The regional reanalysis product CERRA(-land) can overall reduce the biases in the general climatological statistics (e.g., means, tails of the distribution), but shows inconsistencies when moving to the event scale. It for example shows inconsistencies in the temporal evolution and severity of the 2018 drought in Switzerland, whereas the other reanalysis products are more consistent. This presentation gives a comprehensive overview of the differences in the current state-of-the-art reanalysis datasets over the complex terrain of Switzerland.

How to cite: Wood, R. R., Janzing, J., van Hamel, A., Götte, J., Schumacher, D., and Brunner, M. I.: High-resolution climate reanalyses datasets for hydro-climatic impact studies over Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11518, https://doi.org/10.5194/egusphere-egu24-11518, 2024.

EGU24-11519 | ECS | PICO | CL2.6

Towards monitoring climate change on a yearly basis using observational constraints. 

Octave Tessiot and Aurélien Ribes

Climate change monitoring and adaptation policies require reliable and updated indicators about global warming. Reports of the Intergovernmental Panel on Climate Change (IPCC) provide updated indicators every 5 to 7 years, based in particular on the latest available data and evidence. In the last report, projections were derived from climate model simulations constrained by observations. Current warming was derived from observations averaged over the last 10 years, or again a combination of model and observations in attribution statements.

Here we explore the possibility of updating present and future warming estimates on a yearly basis, by incorporating new observations to observational constraints. First, we show that adding the latest temperature observations each year leads to a continuous improvement in estimating warming projections. In particular, warming estimates are not affected by year-to-year internal variability. Second, regarding current warming, we show that observational constraints can be used to derive an estimate of the forced warming for the current year, without having to average over the last 10 years - as the IPCC does in its latest report. This provides an unbiased estimate of current warming, without adding further variance. Third, we show that updating model data can lead to a gap in the estimate of current and future warming, but this remains within the uncertainties we estimate. Finally, we argue that annual updates of current and future warming estimates provide accurate, robust, and reliable information about climate change, while remaining consistent with previous years' estimates.

How to cite: Tessiot, O. and Ribes, A.: Towards monitoring climate change on a yearly basis using observational constraints., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11519, https://doi.org/10.5194/egusphere-egu24-11519, 2024.

EGU24-12091 | ECS | PICO | CL2.6

Historical Climate Assessments in Panama 

Husayn El Sharif, Gustavo Cárdenas-Castillero, Shivani Chougule, Aris Georgakakos, and Juan Pimento

Panama is vulnerable to the effects of climate change, particularly the increase in ocean and atmospheric temperatures, changes in precipitation patterns, and rises in sea level. During the last decades, regional and local studies have reported a warming trend in the Central American region, including Panama. Temperature data from Central Panama indicate an increase of approximately 1°C since the 1970's. A 142-year precipitation record from the Panama Canal Authority shows a clear trend towards an increased frequency of severe storms and droughts during the last 25 years. The purpose of these historical climate assessments is twofold: first, to assess whether statistically significant climatic trends exist in the historical record (indicating that climatic change is occurring), and second, to establish climatic baselines against which to evaluate the consistency and relative change of future climate projections vis-à-vis the historical record. Historical climatic data includes precipitation, maximum and minimum air temperature, and surface downwelling solar radiation (MJ/m2) from all existing ground stations in Panama.

The significance of trends and other metrics of climatic change will be assessed through non-parametric statistical tests. Numerical trends will be developed and assessed for each and all climatic variables of interest for the 30 most recent years at different temporal and spatial scales. This analysis will be conducted on annual, monthly, and daily time scales and at the national, hydroclimatic region, province, and district spatial scales. In addition to the four climatic variables referenced above, trends will also be assessed for the following climatic indices at the same spatial scales referenced above: heat waves, annual drought duration, average and maximum rainfall deficit during annual droughts, biennial drought duration, and average and maximum rainfall deficit during biennial droughts. This historical weather data analysis is crucial for water management, water availability, Panama Canal operation, agriculture, and energy, helping Panamanian society quantify and manage climate risks.

How to cite: El Sharif, H., Cárdenas-Castillero, G., Chougule, S., Georgakakos, A., and Pimento, J.: Historical Climate Assessments in Panama, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12091, https://doi.org/10.5194/egusphere-egu24-12091, 2024.

EGU24-12207 | ECS | PICO | CL2.6

Recent tendencies of extreme heat events in Italy: from 1991 to present days 

Giulio Settanta, Piero Fraschetti, Francesca Lena, Walter Perconti, and Emanuela Piervitali

Recent records about extreme events linked to high temperatures have enhanced the attention over the heat wave phenomenon. 2022 summer has seen a worrisome heat-related excess mortality in Europe and 2023 is the hottest year of record at the global scale, according to the Copernicus Climate Change Services.

Heat waves are a major natural hazard for the most fragile parts of the population. In order to understand their impact, how communities can adapt, and to provide reliable scenarios over the close future, the key point lies in the quantitative addressing of all the aspects that compose heat waves. These include the monitoring of their change in frequency and intensity over time.

This study is focused on the analysis of several temperature-extremes indices, including those specifically related to heat waves. Each of them regards a specific aspect, such as number, frequency, duration and severity. The dataset is based upon a set of quality-controlled and homogenized daily maximum and minimum temperature data from more than 250 ground-based weather stations in Italy. To catch the tendencies of the recent Italian climate, the period analysed covers the latest 33 year time span: 1991 – 2023. Data have been extracted for the most part from SCIA, the Italian national system for climate data collection, processing, and dissemination (www.scia.isprambiente.it) and have therefore undergone a series of automatic procedures which ensure the data quality.

Two analyses have been used in this study: the first one is based on single stations time series and reports an extrapolated trend of the indices over the Italian territory; the second analysis is targeted to look for a global signal about temperature extremes behaviour and therefore considers stations’ data in an aggregated form. The latter analysis splits the 33 year time frame into three decades plus the last 3 years, to get a statistically robust assessment of climate tendencies over time.

The two analyses are found in agreement in depicting a heat wave presence in Italy which is increasing. In particular, half of the stations report an increase of 4 days or more of heat waves per decade, with a national average value of almost 2.5 days per decade. Such behaviour is observed in terms of persistency and intensity too, composing an alarming picture for both the close and the far future. The quantitative findings of the present work can support the development of adaptation measures in the country.

This work is supported by the Italian PNC - Investimento E.1- SALUTE AMBIENTE - BIODIVERSITA' - CLIMA, Missione 6 - Linea di Investimento 1.4, progetto: "Cobenefici di salute ed equità a supporto dei piani di risposta ai cambiamenti climatici". Area A-6. Codice PREV-A-2022-12376994 - Financed by the European Union - NextGenerationEU

How to cite: Settanta, G., Fraschetti, P., Lena, F., Perconti, W., and Piervitali, E.: Recent tendencies of extreme heat events in Italy: from 1991 to present days, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12207, https://doi.org/10.5194/egusphere-egu24-12207, 2024.

In the context of climate change, the escalation of temperature extremes and the persistence of heatwaves have become subjects of growing concern. This study examines Argentina's heatwave patterns from 1950 to 2022, using the ERA5-LAND dataset. The use of this dataset allows for a detailed exploration with high spatial resolution (0.1° x 0.1°) and temporal precision, facilitating regional analyses in countries with vast territories, such as Argentina. The investigation focuses on analyzing temporal and spatial variations through four key metrics: heatwave duration, frequency, mean, and maximum temperature. It also explores seasonal disparities, distinguishing between the Warm Season (WS) and Cold Season (CS), and delves into the influence of the ENSO cold and warm phases (La Niña,El Niño). We use 2-meter temperature data on an hourly basis to calculate daily maximum (Tx) and minimum (Tn) temperatures and detect heatwaves. Our findings reveal an overall escalation in heatwaves across the majority of Argentine regions. Southern Patagonia and the Northwest emerge as hotspots with the most significant upward trends in heatwave metrics, while the Litoral region (Northeast) experiences noteworthy increases, particularly in its northern areas. Conversely, the South of Buenos Aires province (Central region) exhibits decreasing trends in specific areas. Specifically, for Tn, the Warm Season (WS) highlights more significant positive trends in heatwave metrics in most regions, with South Patagonia and the Northwest consistently displaying increases in all metrics. However, for Tx, positive significant trends are observed in both Warm and Cold Seasons, with the North West registering increases in all metrics except Cold Season intensity. Furthermore, the study identifies variations in heatwave occurrences during El Niño and La Niña phases. La Niña events contribute to an increased heatwave frequency across all regions, as evidenced by Tn and Tx metrics. In Patagonia, La Niña amplifies all studied heatwave metrics for both temperature variables. Conversely, during El Niño months, heatwave intensities increase nationwide, excluding Patagonia. This comprehensive research contributes to existing knowledge by providing a detailed, high spatial resolution understanding of heatwave behavior, offering invaluable insights for adapting to extreme temperature events like heatwaves. 

Key words: extreme events, ERA5-LAND, reanalysis 

How to cite: Cimolai, C., Aguilar, E., and Skrynyk, O.: Assessing Argentina's Heatwave Dynamics (1950-2022): A Comprehensive Analysis of Temporal and Spatial variability using ERA5-LAND , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13311, https://doi.org/10.5194/egusphere-egu24-13311, 2024.

EGU24-13380 | ECS | PICO | CL2.6

Assessing Climate Heterogeneity across Europe with the Wettest Days Contributing to 50% of Annual Precipitation (WD50) 

Benjamin Goffin, Prakrut Kansara, and Venkataraman Lakshmi

Characterizing climates (and climatic changes) is particularly important to meet Sustainable Development Goal (SDG) and inform adaptation strategies. To that end, one can capture climate heterogeneinity by focusing on extreme precipitation amounts. Our work went a step further by considering how extreme precipitation contribute to annual precipitation. Across Europe, we calculated the fraction of annual precipitation contributed by very wet days (R95pTOT). Looking at this problem from the opposite angle, we also calculated how many of the Wettest Days in a year constitute 50% of the annual precipitation (WD50). We applied these indices to gridded datasets of daily observations (e.g. E-OBS, CPC, and GPCC) at various spatial resolutions. WD50 showed that 22 to 34 days make up half of the annual precipitation throughout many parts of Europe. Aside from spatial variability, these values also fluctuated from year to year. Additionally, we found substantial differences across data products and spatial resolutions. Overall, our study highlighted how different precipitation indices and gridded datasets can capture (or fail to capture) climate heterogeneinity across Europe.

How to cite: Goffin, B., Kansara, P., and Lakshmi, V.: Assessing Climate Heterogeneity across Europe with the Wettest Days Contributing to 50% of Annual Precipitation (WD50), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13380, https://doi.org/10.5194/egusphere-egu24-13380, 2024.

Past ground surface temperature (GST) changes have been reconstructed from borehole temperature-depth profiles in many areas over the world, but there are still significant uncertainties in understanding regional responses. We reconstruct the past GST changes in southwestern Japan over the past century from borehole temperature-depth profiles using the Bayesian least-squares method to invert borehole temperatures to produce the histories. This analysis reveals that the average reconstructed GST shows temperature increases of about 1.0oC during the past century. This is consistent with nearby meteorological annual surface air temperature (SAT) and area-averaged annual mean sea surface temperature (SST) reported by the Japan Meteorological Agency. The consistency suggests that GST from borehole temperature-depth profiles shares information with the mean SAT and SST records over long time scales. Reconstructed GST changes using other temperature profiles at different parts of in and around Japan showed that the amplitude of the temperature increase varies by site. This suggests that further research with better spatial resolution is required.

How to cite: Tanaka, A. and Goto, S.: Japan warming inferred by combining borehole temperatures with surface air and mean sea surface temperatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13394, https://doi.org/10.5194/egusphere-egu24-13394, 2024.

In the Brazilian Amazon, large-scale and spatially explicit evidence of observed climate change in the recent decades is still scarce but important for monitoring areas that require climate action if changes persist over a long-term. Many areas in this region have faced high levels of deforestation during the last decades, leading to changes in energy fluxes that may amplify the effects on climate caused by globally increasing greenhouse gas (GHG) emissions.

In this study we assessed how land surface temperature and rainfall changed across space and seasonal intervals during the last two decades. We also aimed to understand if highly deforested areas were more likely to experience positive or negative changes at a particular seasonal interval.

We focused on the Amazon rainforest domain over Brazil, dividing the region into 0.5° grid cells. We used forest cover mapping from MapBiomas to compute total deforestation from 2003 to 2021 relative to the cell’s area. For land surface temperature (LST), we used data from the MODIS MYD11A1 product, selecting daily daytime observations. For rainfall volume we used daily estimates from CHIRPS. For each year from 2003-2021, we performed aggregations for the annual, driest quarter (three consecutive driest months based on the climatology) and wettest quarter for each cell, averaging LST and summing rainfall volume. We then subtracted the 2013-2021 to 2003-2012 averages in each cell, excluding extreme drought years to reduce changes from internal climate variability such as extreme El Niño. 

We found that, over the last two decades, annual LST and rainfall increased on average in the Brazilian Amazon by 0.31°C and 4% respectively. At least 80% of cells experienced increases in LST at any of the time intervals, with warming greater than 1.5°C in some locations. Areas with substantial warming were predominant in southern Amazon at the annual scale and driest quarter, but widely dispersed in the wettest quarter. In terms of rainfall, increases were found for 68% of cells at the annual scale and ~56.5% in the other time intervals. The driest quarter had the largest frequency of rainfall reductions and increases >20%. In all time intervals, substantial rainfall decreases were found in the states of Roraima and southwestern Amazonas, whereas substantial rainfall increases were found in eastern Acre.

For all cells with deforestation >10%, more than 70% had LST warming >0.5°C annually and during the driest quarter, in contrast to only 40% in the wettest quarter; in cells with no long-term deforestation (<=0.5%), the proportion was less than 8%. In all time intervals, areas with >10% deforestation had a frequency of both rainfall increases and decreases about 10-15 percentage points greater, suggesting no clear pattern for a greater likelihood in rainfall changes.

We find that regional climate change in the Amazon is very dynamic in space and season, especially in terms of rainfall changes, requiring careful examination. We also demonstrate how deforestation has been leading to a greater intensity of LST warming in the region, representing a regional climate forcing that may be as important as increased GHG emissions.

How to cite: Silveira, M., Aragão, L., and Keys, P.: Land surface temperature and rainfall changes in the Brazilian Amazon during the last two decades: variability in space, season, and by deforestation intensity , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14413, https://doi.org/10.5194/egusphere-egu24-14413, 2024.

EGU24-15129 | PICO | CL2.6

Gridded data of daily atmospheric precipitation and minimum, mean and maximum air temperature for Ukraine, 1946-2020 

Volodymyr Osadchyi, Oleg Skrynyk, Vladyslav Sidenko, Enric Aguilar, Jose Guijarro, Tamás Szentimrey, Olesya Skrynyk, Liudmyla Palamarchuk, Dmytro Oshurok, Igor Kravchenko, Zoryna Kyreyeva, and Dmytro Pinchuk

In this contribution, we present the results of the development of long gridded climate time series, which cover the territory of Ukraine for the period of 1946-2020 (75 years). The spatial resolution of the developed data is 0.1o×0.1o (approximately 10 km in both longitude and latitude directions), while their time discreteness is 1 day. Four essential climate variables are included in the dataset, namely daily sums of atmospheric precipitation and daily minimum, mean and maximum air temperature. The created gridded product is based on the complete collection of weather measurements, performed at 178 meteorological stations of Ukraine, which constitute the modern national observation network. Quality assurance check, homogenization and gridding of the station time series were performed by means of widely used and well approved climatological software, i.e. INQC, Climatol and MISH, respectively. The produced gridded time series were statistically compared on the monthly and daily time scales with several existing data sets, which have the same spatial resolution (i.e., previously developed gridded monthly data of Ukraine, ERA5-Land, E-OBS). The comparison showed good accordance with UA monthly data (partly obtained from other paper sources than the daily data) and acceptable agreement with ERA5-Land and E-OBS data. The developed long gridded time series are of great importance as they were built with the involvement of as many real weather measurements as possible. Therefore, they can be used as a reference for a wide variety of climatological applications for the territory of Ukraine.

 

Oleg Skrynyk acknowledges the support from the MSCA4Ukraine fellowship program, which is funded by the European Union.

How to cite: Osadchyi, V., Skrynyk, O., Sidenko, V., Aguilar, E., Guijarro, J., Szentimrey, T., Skrynyk, O., Palamarchuk, L., Oshurok, D., Kravchenko, I., Kyreyeva, Z., and Pinchuk, D.: Gridded data of daily atmospheric precipitation and minimum, mean and maximum air temperature for Ukraine, 1946-2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15129, https://doi.org/10.5194/egusphere-egu24-15129, 2024.

EGU24-15289 | ECS | PICO | CL2.6

A new 0.5° x 0.5° REACHES-LME reanalysis temperature dataset for East Asia since the 14th century 

Eric Sun, Hsin-Cheng Huang, Kuan-Hui Elaine Lin, and Wan-Ling Tseng

To understand and reconstruct paleoclimate, historical records are commonly used. In this study, we utilize the REACHES (Reconstructed East Asian Climate Historical Encoded Series) data, derived from Chinese historical documents, to derive new 0.5o x 0.5o latitude/longitude reanalyais temperature data since the mid-14th centuries. The REACHES reconstructed temperature index (four-point ordinal scale from -2 extreme cold to 1 warm) data covers more than 1,400 sites in the east China. But it has a significant flaw in a large number of missing values most likely reflecting normal weather (index value 0) and so produced a very biased and skewed distribution. To enhance the prediction for the missing data and improve REACHES data quality, we apply simple kriging to impute the missing data and set the mean of the underlying spatial process to zero (normal weather) to adjust for the missing patterns. To improve climate reconstruction accuracy in China, we propose a data assimilation approach by combining the REACHES reconstructed temperature index data with Last Millennium Ensemble (LME) reanalysis data. We propose a nonstationary time series model for the LME data and apply regularized maximum likelihood with a fused lasso penalty for parameter estimation. We treat the resulting distribution as the prior for historical temperatures, which are then updated to acquire refined temperatures based on the REACHES data using the Kalman filter and smoother. Overall, our approaches, which combine historical climate records, climate models, and statistical techniques, provide insights into past climate variations and enhance the accuracy of historic temperature estimation in east Asia.

 

How to cite: Sun, E., Huang, H.-C., Lin, K.-H. E., and Tseng, W.-L.: A new 0.5° x 0.5° REACHES-LME reanalysis temperature dataset for East Asia since the 14th century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15289, https://doi.org/10.5194/egusphere-egu24-15289, 2024.

EGU24-15349 | ECS | PICO | CL2.6

The observed evolution of sub-daily to multi-day heavy precipitation in Switzerland 

Victoria Bauer and Simon Scherrer

Heavy precipitation events and their changes due to climate change affect many aspects of daily life in the Alpine region. In this study, we revisit the long-term (1901-2022) evolution of daily and multi-day heavy precipitation intensity and frequency, discuss trends for sub-daily to multi-day events in the recent period 1981-2022, and investigate possible elevation dependencies in the complex topography of Switzerland. Station measurements from the dense operational network of MeteoSwiss from all parts of the country and elevation levels are analyzed. We find that daily maximum precipitation and the frequency of precipitation events exceeding the 99th daily percentile have increased since 1901, with a peak in the 1980s and some decline thereafter. For the more recent period 1981-2022, positive trends in summer heavy precipitation intensity are found for short (10 minutes to 3 hours) events, but no changes are found in the frequency of these events. For longer events (one to five days), however, decreases in intensity and frequency are found, especially for the winter half-year. We hypothesize that the opposing trends on long and short time scales are caused by the superposition of thermodynamics (i.e. the main forcing of anthropogenic climate change) and internal variability of atmospheric dynamics. We also observe a small negative elevation dependence of the long-term trends up to 2300 m. For the 1981-2022 trends, no strong elevation dependence is found for sub-daily events. For daily events we find small opposing negative summer and positive winter elevation dependencies. The reason for these trends remains unclear. Our results underline the need to better investigate the interplay between climate change, internal variability of large-scale dynamics and elevation for heavy precipitation in the complex Alpine terrain. Longer observational records with high spatial and temporal resolution will help to answer this open question.

How to cite: Bauer, V. and Scherrer, S.: The observed evolution of sub-daily to multi-day heavy precipitation in Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15349, https://doi.org/10.5194/egusphere-egu24-15349, 2024.

EGU24-16497 | PICO | CL2.6

Uncertainty of heat wave metric calculations 

Oleg Skrynyk, Enric Aguilar, and Caterina Cimolai

Climate/weather extremes such as heat waves (HWs) are of the great interest to study as they have the significant harmful effect on the environment and society. There are many researches dealing with the calculation of HW metrics and their long-term trends on both the global and regional/national spatial scale. In our work based on a case study of Ukraine, we aimed to quantify the uncertainty of HW metric calculations, which might originate from climate input data. To this end, we used a mini statistical ensemble of several gridded data sets of maximum daily air temperature (TX), covering the territory of Ukraine for the period of 1950-2020 (70 years) with the same spatial resolution. The ensemble included ERA5 reanalysis data (remapped by means of the CDO software to the finer grid of 0.1ox0.1o with different interpolation algorithms), ERA5-Land, E-OBS (the ensemble mean) and Ukrainian gridded observation data previously developed for the period of 1946-2020. We defined a HW as an event when conditions (TX in our case) above criteria (90-th percentile calculated based on the WMO standard 1961-1990 reference period) persist at least three consecutive days, with permission of a 1-day time gap. Four HW metrics were considered, namely heat wave number (HWN), duration (HWD), frequency (HWF) and amplitude (HWA). The calculation of yearly time series of the HW metrics was performed by means of the R package heatwaveR for each grid point of the domain and each member of the constructed statistical ensemble. The uncertainty of the HW metrics was defined as a difference between min and max metric’s values calculated for different members of the ensemble. We also calculated the range of the possible variations in long term trends of obtained yearly time series of the HW metrics. Our results showed that depending on climate data used for HW climatology analysis, the calculation results might differ significantly for a particular grid point and year. However, on average (over the whole domain and the period under study), variation of the HW metrics is not so pronounced. Moderate variations are also observed in long-term trends of the metric time series.

 

This work has received funding through the MSCA4Ukraine project, which is funded by the European Union

How to cite: Skrynyk, O., Aguilar, E., and Cimolai, C.: Uncertainty of heat wave metric calculations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16497, https://doi.org/10.5194/egusphere-egu24-16497, 2024.

EGU24-16501 | ECS | PICO | CL2.6

Gridded datasets of climate indices: comparison of two approaches 

Anna-Maria Tilg, Maral Habibi, Barbara Chimani, and Marion Greilinger

Gridded data is highly appreciated for many climate related applications due to their spatial information compared to single station locations. The quality and additional value of a gridded dataset is depending on the method itself and on the amount of additional information, e.g. topographical data, used for the interpolation. Furthermore, there is an ongoing discussion on the implications of using gridded datasets of primary climate parameters like temperature or precipitation to derive gridded datasets of climate indices. Within the project SDGHUB (https://www.sdghub.at/), we are exploring the influence of different approaches on the final gridded climate index dataset.  

The focus is on the frequently used climate index of hot days (days with a maximum air temperature above or equal to 30 °C). In the first approach the hot days were computed from the gridded climate dataset SPARTACUS (Hiebl and Frei, 2016), while in the second approach the hot days were directly interpolated considering station values. SPARTACUS is a national gridded dataset of Austria, available on a daily basis with a 1 km-spatial resolution via the DataHub of GeoSphere Austria (https://data.hub.geosphere.at/). It covers the period from 1961 onwards and includes the parameters of maximum, minimum and mean air temperature and rain amount.  

For the second approach the efficacy of several geostatistical interpolation methods, including Kriging with External Drift (KED), Ordinary Kriging (OK), and Regression Kriging (RK), with a particular emphasis on their ability to represent the spatial variability of hot days was explored. The comparison showed that KED provides the best results, as the complex terrain in Austria can be considered best. Therefore, this method was used for further analysis. To further improve the interpolation results of KED, different data transformations were tested, with the square root transformation emerging as the most effective one. As for SPARTACUS, the direct interpolation was done on a 1 km-scale for Austria.

To evaluate the performance of the two respective approaches a cross-validation is applied.

The presentation will include information on the interpolation methods and provide insights into the evaluation and differences of the two datasets as well as the effect of station density. The final dataset of hot days will be available via the DataHub of GeoSphere Austria with a monthly, seasonal and annual resolution.

 

References

Hiebl J, Frei C (2016) Daily temperature grids for Austria since 1961 – concept, creation and applicability. Theor Appl Climatol 124:161–178. https://doi.org/10.1007/s00704-015-1411-4

 

Acknowledgement

The project SDGHUB is funded by the Austrian Federal Ministry for Climate Action, Environment, Energy, Mobility and Technology (BMK) via the ICT of the Future Program - FFG No 892212.

How to cite: Tilg, A.-M., Habibi, M., Chimani, B., and Greilinger, M.: Gridded datasets of climate indices: comparison of two approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16501, https://doi.org/10.5194/egusphere-egu24-16501, 2024.

EGU24-17206 | PICO | CL2.6

Recent climate change in Iceland 

Halldór Björnsson, Kristín Ólafsdóttir, and Guðfinna Aðalgeirsdóttir

The climate in Iceland has warmed by about 1°C per century since the start of the 20th century. The warming has been intermittent with strong decadal variablility but the last two decades stand out as the warmest since continuous measurements began in the 19th century. Changes in precipitation, snow fraction and extreme precipitation have also occurred. The warming has impacted glaciers which have lost 16% of their mass and 19% of their area since the early 20th century. Several small glaciers have vanished, new pro-glacial lakes have formed and significant changes have occurred in the drainage system from some glaciers. The iso-static rebound resulting from the ice mass loss is widespread and exceeds 1 cm per year on the southeastern shore where it is highest. The warming has generally increased the productivity of plants leading to observed greening.

The recently published Climate Change Impact Assessment for Iceland, the fourth since the start of this century concluded that Climate Change is having a strong impact on physical and biological systems, with increasing societal impacts, especially with increasing risks associated with natural hazards such as flash floods, landslides, subglacial eruptions, and coastal flooding.

How to cite: Björnsson, H., Ólafsdóttir, K., and Aðalgeirsdóttir, G.: Recent climate change in Iceland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17206, https://doi.org/10.5194/egusphere-egu24-17206, 2024.

Understanding and monitoring the melting of the Greenland Ice Sheet (GrIS) is crucial for contemporary climate assessment and discussions, given its potential to contribute up to 7 metres to the global sea level rise [1]. In 2021, the National Snow and Ice Data Center (NSIDC) estimated an annual contribution of 400 billion tons of meltwater from the Greenland and Antarctic ice sheets to the world’s oceans [2], impacting ocean salinity and temperature, thereby influencing ocean circulation. This study focuses on surface melt, exploring observational challenges in polar regions and proposing a method using remotely sensed data from infrared (IR) and passive microwave (PMW) satellites to create a composite surface melt product for the GrIS.

Field campaigns and in-situ measurements are limited in polar regions due to harsh conditions, making remote sensing from satellites an essential tool. Infrared data provides high spatial resolution but is sensitive to clouds, while passive microwave data, with lower spatial resolution, penetrates clouds effectively. The study combines these types of data to derive surface melt using, in part, the Cross-Polarized-Gradient-Ratio (XPGR) method, which accounts for their complementary strengths and weaknesses [3]. Additionally, an extended version (ExtXPGR) is employed, considering additional factors [4]. The study discusses the challenges and advantages of using both infrared and microwave data and highlights the importance of threshold definitions for detecting melt in each type of data.

Validation involves comparing the derived surface melt product with in-situ measurements from the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) [5] and the Danish Meteorological Institute (DMI) [6]. The study also uses data from the NSIDC’s Ice Sheets Today project for further validation [7]. The results show promising agreement between the derived surface melt product and the various validation sources.

The study addresses challenges in data processing, including regridding/interpolation, and combining different data sources to achieve a temporally and spatially stable composite surface melt product covering the GrIS from 2002 to 2018.

Overall, this study contributes to the comprehensive understanding of GrIS surface melt by proposing a methodology that integrates infrared and passive microwave data, providing a valuable tool for climate researchers.

 

[1] NASA, Greenland Sea Level Rise. https://climate.nasa.gov/faq/30/if-all-of-earths-ice-melts-and-flows-into-the-ocean-what-would-happen-to-the-planets-rotation/ 

[2] NSIDC, Ice sheets and why they matter, https://nsidc.org/learn/parts-cryosphere/ice-sheets/why-ice-sheets-matter 

[3] W. Abdalati and K. Steffen, Passive microwave-derived snow melt regions on the Greenland ice sheet, doi: 10.1029/95GL00433,Journal: Geophysical Research Letters, 22,7 ,787-790, 1995, https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/95GL00433

[4] X. Fettweis and M. Tedesco and M. van den Broeke and J. Ettema, Melting trends over the Greenland ice sheet (1958–2009) from spaceborne microwave data and regional climate models, doi: 10.5194/tc-5-359-2011, journal: The Cryosphere, 5, 359–375, 2011, https://tc.copernicus.org/articles/5/359/2011/tc-5-359-2011.pdf 

[5] PROMICE and GEUS, Programme for Monitoring of the Greenland Ice Sheet & Greenland Climate Network, https://promice.org/ 

[6] DMI, GEUS, and DTU, PolarPortal, Monitoring Ice and Climate in the Arctic, http://polarportal.dk/en/home/ 

[7] NSIDC, Ice Sheets Today, https://nsidc.org/ice-sheets-today 

How to cite: Suhr, M.: Greenland surface melt product from remotely sensed multi-sensor surface temperatures., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18474, https://doi.org/10.5194/egusphere-egu24-18474, 2024.

EGU24-19560 | ECS | PICO | CL2.6

Satellite-based surface temperatures of the Arctic ocean and sea ice, 1982–2021.  

Pia Nielsen-Englyst, Jacob Høyer, Wiebke Kolbe, and Ioanna Karagali

The Arctic is warming faster than any other region. Despite much attention there has actually been limited consensus on the magnitude of Arctic amplification over time. Within the framework of the Copernicus Marine Monitoring Service Sea Ice Thematic Assembly Center, the first gap-free (L4) of combined sea surface temperature (SST) and sea ice surface temperature (IST) climate data record of the Arctic (>58°N) has been developed for the period 1982-2021. The data set has been generated using optimal interpolation to combine multiple infrared satellite observations to daily, gap-free fields with a spatial resolution of 0.05 degrees. The combination of SST and IST provides a consistent climate indicator which can be used to monitor day-to-day variations as well as climate trends in the Arctic Ocean. Validation against in situ measurements from drifting buoys, moored buoys and Argo floats shows mean differences of 0.01 °C, 0.04 °C and 0.04 °C and standard deviations of 0.54 °C, 0.56 °C and 0.51 °C, respectively for the open ocean. Over sea ice, validation shows a mean difference of 1.52 °C and standard deviation of 3.12 °C, for skin surface temperatures. For air temperatures from the North Pole (NP) ice drifting stations as well as ECMWF distributed buoys and CRREL buoys, validation shows mean differences of −2.35 °C, −3.21 °C and –2.87 °C and standard deviations of 3.12 °C, 3.34 °C and 3.36 °C, respectively. Analysis of the CDR show sea and sea-ice surface temperature of the Arctic has risen with about 4.5 °C over the period 1982–2021, with a peak warming of around 10 °C in the northeastern Barents Sea. The L4 ISTs have been converted to near surface air temperatures (T2m) and initial results indicate that it is possible to derive reliable T2m over sea ice based on the satellite-observed L4 ISTs. The satellite-derived L4 T2m product provides an important supplement to the sparse in situ air temperature network in the Arctic and to the existing model-based air temperatures. It has a large potential to be used for assimilation, global surface temperature reconstructions or for evaluation of global reanalyses and climate models. 

How to cite: Nielsen-Englyst, P., Høyer, J., Kolbe, W., and Karagali, I.: Satellite-based surface temperatures of the Arctic ocean and sea ice, 1982–2021. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19560, https://doi.org/10.5194/egusphere-egu24-19560, 2024.

EGU24-1468 | ECS | Orals | CL2.7 | Highlight

The role of plant traits in climate warming responsiveness of tree species 

Yahya Ghalayini, Nicole Estrella, Jens Kattge, and Annette Menzel

Climate warming is mostly advancing the onset date of spring phenology, yet milder winters with higher temperatures may in fact delay this date, as chilling requirements of species are not fully met in time. The spring phenology of trees and forests is interconnected with ecosystem functions and services, thus the responses of single species to climate warming may have significant implications at the economic and ecological levels. Despite the numerous studies which have been conducted during the past decade on the responses of plant spring phenology to climate warming, the relative importance of various factors, such as phylogeny, floristic status, climate of the native range, life strategy and plant traits, is still not well understood. In this study, twigs from 53 different tree species with two different natural-chilling treatments were forced in climate chambers at 20°C/day and 15°C/night until budburst, and the onset of budburst was monitored 3 times per week. The forcing requirements until budburst were linked to phylogeny (genera), life strategy (pioneer to climax), climate of their native range (oceanic to continental), floristic status (native, ornamental, and invasive) and eight important plant traits from the TRY database. The aim of our study is to answer the following questions: Are pioneer species more responsive to warming compared to later successional strategies? Is the climate of the native range, floristic status and continent of the species related to responsiveness to forcing? Can plant traits indicate the degree of species’ phenological responses to climate warming?

How to cite: Ghalayini, Y., Estrella, N., Kattge, J., and Menzel, A.: The role of plant traits in climate warming responsiveness of tree species, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1468, https://doi.org/10.5194/egusphere-egu24-1468, 2024.

Leaf unfolding of trees is influenced by a wide range of environmental factors, such as climate, stand structure, soil characteristics, and topography. However, few studies have investigated the compound effects of those environmental factors. Furthermore, several factors, such as stand structure and soil characteristics, have not been sufficiently studied. In particular, the influence of water-holding capacity and the resulting soil-water balance on the phenological behaviour of adult trees is largely unexplored.

This study aims to understand how interactions between multiple environmental factors, including climate, stand structure, soil characteristics, and topography, influence the phenological timing of Fagus sylvatica, Picea abies, Larix decidua and Tilia cordata. To understand the effects of these factors, field data on soil characteristics (depth, texture, bulk density, and organic carbon), topography (elevation, relief type, slope aspect and slope inclination) and stand structure (basal area, tree height and stand height) were collected at 52 long-term monitoring sites from a phenological network across all biogeographic regions of Switzerland. Data is currently being analysed using linear mixed-effects models.

Preliminary results indicate that growing degree days, drought and elevation are the most important factors determining the timing of leaf unfolding across species. Among those factors, drought consistently seems to have the highest impact on advancing leaf unfolding. Other factors such as relief type, stand height and basal area appear to be relevant as well, but seem more species specific. For example, relief type, which can affect heat accumulation irrespective of weather conditions, seems important for Larix decidua, but not Fagus sylvatica. In contrast, there is reasonable evidence that competition parameters such as stand height and basal area affect Fagus sylvatica, but not Larix decidua.

This study considerably improves our understanding about the compound effect of established as well as rarely investigated environmental factors on the timing of leaf unfolding across species throughout a wide range of environmental conditions.

How to cite: Ostovary, I. and Bigler, C.: Effects of climate, stand structure, soil characteristics and topography on leaf unfolding of trees in Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1970, https://doi.org/10.5194/egusphere-egu24-1970, 2024.

Four different varieties of Ashwagandha (Withania somnifera Dunal) viz.  Vallabh 01 (V01), Vallabh 02 (V02), Pratap (P), and Chetak (C) were investigated to determine the impact of elevated temperature (ET) levels on the morphology, biomass, and concentration of phytochemicals. The plants were exposed to ET (AT ± 3˚C) from November to March 2022. Results showed an increase in the shoot length (53.1% in V01 and 22.4% in V02, P, and C), and a 70% decrease in the root length of all the varieties under ET. Enhancement in the shoot biomass production (14.05, 11.3, 1.15, and 10.29% in V01, V02, P, and C) while the decline in the root biomass production (17.07, 34.6, 1.54, and 2.33% in V01, V02, P and C) were found under ET. Under ET, V01 showed a 3.6 % decrease in the phytochemical content while the other three varieties (V02, P, C) had an increase in the phytochemical content (45.2%, 10.02%, and 32.14% respectively). The ET significantly enhanced terpenoids, steroids, and alkaloids in all varieties of W. somnifera. These findings showed that V01 is most tolerant while P is sensitive to temperature stress (V01> V02> C> P). The study revealed the tolerance ability of Withania somnifera to temperature stress in the context of climate change.

Keywords: Withania somnifera, temperature stress, climate change, phytochemical profile, growth

How to cite: Singh, A. and Mina, U.: Effect of elevated temperature on the morphology and phytochemical profile of Withania somnifera’s varieties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2213, https://doi.org/10.5194/egusphere-egu24-2213, 2024.

EGU24-2839 | ECS | Orals | CL2.7

Ecophysiological modelling of cessation of wood formation phenology in temperate and boreal forest trees 

Jianhong Lin, Nicolas Delpierre, and Cyrille Rathgeber

Wood phenology is an important indicator of ecosystem response to climate change. However, compared to leaf phenology, the understanding of wood phenology is still in its infancy. In this study, we developed the first ecophysiological model to simulate the cessation of wood formation for two major Northern Hemisphere conifer species (Pinus sylvestris and Picea abies). The model developed postulates cessation of wood formation to be driven by both photoperiod and temperature. We calibrated and validated the model based on the GLOBOXYLO database documenting the occurrence of phenological stages in wood formation. We focused on two European species here, namely Pinus sylvestris and Picea abies, totaling 96 site-years. The model received support for both species with a root mean square error of 12.6 days and 8.6 for the prediction of validation data, respectively. The model accuracy was significantly related to the within-population variability in the observed data of cessation of wood formation, with higher prediction errors in years when trees of the same population were not in sync. Moreover, we found the number of radial cell and tree diameter to also affect the cessation of wood formation based on a path analysis model. This study improves the knowledge of the role of environmental and ontogenetic factors controlling the cessation of wood formation in the temperate and boreal zones.

How to cite: Lin, J., Delpierre, N., and Rathgeber, C.: Ecophysiological modelling of cessation of wood formation phenology in temperate and boreal forest trees, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2839, https://doi.org/10.5194/egusphere-egu24-2839, 2024.

EGU24-2900 | Orals | CL2.7

The modest influence of internal factors on autumn phenology compared to climate factors  

Shilong Ren and the Global change and plant phenology

Autumn phenology plays a vital role in regulating the length of growing season and carbon uptake in terrestrial ecosystems. Under global climate change, delayed autumn phenology has been widely reported, but as to the potential drivers and mechanisms, it is are still unclear, especially the impact magnitude and direction of internal factors. In this study, based on satellite-derived the end of growing season (EOS) and photosynthetic data over the Northern Hemisphere (>30° N) from 1982 to 2014, we comprehensively investigated the impacts of developmental and environmental factors on EOS and compared their relative effects across different climate zones and vegetation types. We found the magnitude of EOS shift was highly heterogeneous across climate zones and vegetation types. It delayed more in humid regions than in drought regions. The response of EOS to temperature and precipitation in warm-dry areas was opposite to that in other areas. Spring phenology had an important legacy effect on EOS. But no direct sink limitation effect of growing season photosynthesis on autumn phenology was detected in any climate zone or vegetation type, as reported in some other field observations. While internal factors played a certain role in modulating EOS, their total impact was lower than the influence of temperature and precipitation in most regions and vegetation types. Our findings emphasize the complexity of factors influencing EOS, and call for elaborate investigation on the driving mechanisms of autumn phenology at different scales and under different climate backgrounds.

How to cite: Ren, S. and the Global change and plant phenology: The modest influence of internal factors on autumn phenology compared to climate factors , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2900, https://doi.org/10.5194/egusphere-egu24-2900, 2024.

EGU24-3141 | Orals | CL2.7 | Highlight

Spring phenology of Swiss grasslands under climate change – variability and trends since 1961 

Pierluigi Calanca, Pierre Mariotte, and Massimiliano Probo

Phenological observations provides important information for the agricultural management of grasslands, especially in spring, when a clear trade-off between increasing biomass and decreasing forage quality emerges as plant development progresses. For this reason, and in view of the impacts of climate change on agroecosystems and the needs for adapting farming activities to altered climatic conditions, there is much interest for understanding the long-term trends of key phenological stages.

In this contribution we first provide an overview of 30 years of phenological observations carried out since 1995 at more than 50 sites located in Western Switzerland and covering an altitudinal belt ranging between 400 and 1400 m above sea level. Using the so-called Dactylis glomerata (cocksfoot) equivalent stage to assess the average plant development in these grasslands, we show that full heading has been advancing by about 2 days per decade over the 30 years of observations.

Secondly, we demonstrate that observed dates of full heading and associated trends are very well matched by estimates obtained with a simple phenological model. We use this model, along with models for determining the end of the snow season and the beginning of the vegetation period, to extend the assessment of climate change impacts on grassland spring phenology in Western Switzerland back to 1961. We report on shifts and associated trends calculated along the altitudinal transect covered by our network.

Finally, we compare the development of grassland phenology with the one of spring phases of other plant species and discuss our results in the context of the overall temperature evolution in Switzerland. We also emphasize a possible association of the variability in the spring phenology of grasslands with the long-term evolution of large-scale atmospheric circulation modes, and the implications of projected future changes in climatic conditions for the agricultural utilization of permanent grasslands.

How to cite: Calanca, P., Mariotte, P., and Probo, M.: Spring phenology of Swiss grasslands under climate change – variability and trends since 1961, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3141, https://doi.org/10.5194/egusphere-egu24-3141, 2024.

EGU24-3469 | Posters on site | CL2.7

Temperature trends  in olive growing season in producing areas of Extremadura (Spain) 

Luis L. Paniagua, Abelardo García-Martín, Dolores García García, Cristina Aguirado, F. Javier Rebollo, Francisco J. Moral, and Fulgencio Honorio

The olive tree is mainly cultivated in the temperate zones of the Mediterranean area. Temperature is the main factor to evaluate the climatic suitability for olive cultivation. The study of the spatial and temporal variations of temperatures in a territory is necessary to define the most appropriate areas for production, as well as to evaluate different varieties. Extremadura has more than 269,000 ha of olive trees with a production of 884,960 tonnes, the third-largest surface area, and the second-largest olive-growing production in Spain. In this study the number of olive active days (OAD), the growing degree-days (GDD), and the average temperature of the olive growing period (OGST) index are analysed. The active days for the olive tree have been defined as those in which the average daily temperatures are above 14.4 °C between April and October. The minimum and maximum daily temperatures, from the meteorological data base of the Spanish government (AEMET), located in the main olive growing areas have been used, considering a period from 1991 to 2020. Mann-Kendal test and Sen's slope have been used to determine trends and their magnitude. The results show 200 active days per year, between 185 in Ibores and 215 in Vegas del Guadiana. The mean GDD value was 1514°C, varying between 1363°C in the Ibores area and 1685°C in La Serena whith a significant increasing trend in five areas. Growing degree-days have increased by an average of 4.9°C per year. The mean OGST value was 22.0°C, varying between 21.7°C in the Logrosan-Guadalupe area and 22.4°C in La Siberia. It has also shown a significant increasing trend in the index in four areas. Temperatures in the olive tree growth period have increased by an average of 0.21°C per decade, which represents an average increase of 0.67°C between 1991 and 2020.

Keywords: olive, active days, degree-days, temperature, trends, Spain.

How to cite: Paniagua, L. L., García-Martín, A., García García, D., Aguirado, C., Rebollo, F. J., Moral, F. J., and Honorio, F.: Temperature trends  in olive growing season in producing areas of Extremadura (Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3469, https://doi.org/10.5194/egusphere-egu24-3469, 2024.

EGU24-3949 | Posters on site | CL2.7

Characterization of Evapotranspiration and effective precipitation in the Olive Areas of Extremadura, Spain. (1990-2021) 

Abelardo García Martín, Luis Lorenzo Paniagua Simón, Fulgencio Honorio Guisado, Francisco Jesús Moral, Francisco Javier Rebollo, Cristina Aguirado, and Lourdes Rebollo

The olive tree (Olea europaea L.) is one of the main woody perennial crops in Europe, especially in the Mediterranean area. The area dedicated to olive cultivation in the European Union (EU) has increased in the last decade, reaching 4.6 million hectares. Extremadura (Spain) is the region with a semi-arid Mediterranean climate located most south-west of Europe. It has a great climatological contrast in the North-South direction. Numerous studies indicate that an increase in temperatures and a reduction in precipitation is expected due to climate change in the Mediterranean region. This would cause an increase in crop Evapotranspiration and a lower contribution of rain, especially in dryland crops. Using time series of climate data (1990-2021), the differences between areas have been analyzed using an Anova and Tukey test. The trend of Evapotranspiration of the olive crop and annual effective Precipitation  in 13 olive-growing regions of Extremadura was also analyzed. To determine the monotonic trend, the Mann-Kendal test and Sen's slope estimator were used. The results showed clear differences between the olive-growing areas, for the analyzed indices. An increase in Evapotranspiration was found in important Olive-growing areas. However, the effective precipitation did not show any trend. These results contribute to the climatic characterization of the Olive-growing regions of Extremadura and could affect the yields and quality of production, requiring a varietal adaptation and cultivation techniques, as well as a change in the distribution of suitable cultivation areas.

Keywords: Olive tree, Agroclimatology, Evapotranspiration, Extremadura

How to cite: García Martín, A., Paniagua Simón, L. L., Honorio Guisado, F., Moral, F. J., Rebollo, F. J., Aguirado, C., and Rebollo, L.: Characterization of Evapotranspiration and effective precipitation in the Olive Areas of Extremadura, Spain. (1990-2021), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3949, https://doi.org/10.5194/egusphere-egu24-3949, 2024.

EGU24-4051 | ECS | Posters on site | CL2.7

Changes in grapevine budburst and harvest dates in Croatia under current and future climate conditions 

Branimir Omazić, Maja Telišman Prtenjak, Marko Kvakić, Josip Meštrić, Marijan Bubola, Ivan Prša, and Marko Karoglan

The increase in temperature affected the entire plant world, including the vines. These changes are reflected in the quantity and quality of the harvest, the chemical composition, and the appearance of the phenological phases of the grapevine. The shift of budding towards the beginning of the year can be particularly worrying due to the frequent occurrence of frost in the continental area of ​​Croatia. The shift of the harvest towards the warmer part of the year brings problems when storing grapes. Due to the great importance of viticulture for agriculture and tourism in Croatia, it is necessary to examine changes in the occurrence of phenological phases in current and future climatic conditions.

Due to all of the above, statistical models were developed to describe the occurrence of phenological phases. Also, the crop model STICS was parameterized for the Croatian region and four grape varieties. Bayesian statistics were also used to get an insight into the amount of earlier and later harvests. To get a clearer picture of the changes in the future climate three CORDEX Regional Climate Models (RCMs) simulations (CLMcom-CCLM4-8-17, SMHI-RCA4, CNRM-ALADIN5.3) for the Croatian domain and varieties were used in this research. All RCMs are forced by output from Global Climate Models (GCMs) with moderate (RCP4.5) and high-end (RCP8.5) greenhouse gas (GHG) scenarios. SMHI-RCA4 is driven by five different GCMs (CNRM-CERFACS-CNRM-CM5, ICHEC-EC-EARTH, IPSL-IPSL-CM5A-MR, MOHC-HadGEM2-ES and MPI-M-MPI-ESM-LR), CLM by four (CNRM-CERFACS-CNRM-CM5, ICHEC-EC-EARTH and MOHC-HadGEM2-ES, MPI-M-MPI-ESM-LR), and CNRM-ALADIN5.3 with one (CNRM-CERFACS-CNRM-CM5). All the simulations have horizontal grid spacing of 0.11◦.

The results show clear trends in the budburst and harvest shifting in Croatia, regardless of the variety. Future climate analysis indicates a further shift in the occurrence of phenological phases towards the beginning of the year (that is, an earlier occurrence). The expected shifts in budburst in the period P2 (2041-2070) compared to the period P0 (1971-2000) are more pronounced for traditional varieties ('Graševina' and 'Plavac mali'), where median differences suggest shifts of 15 days towards the beginning of the year, regardless of the RCP scenario. The results indicate a shift in budburst to early March, which is a particular threat for white varieties that are mostly grown in continental parts of Croatia where low temperatures and frost in March can reduce most of the harvest. In addition, the results indicate a further shift in harvesting in the future climate, and an increase in the number of early harvests, and a decrease in the number of later harvests, regardless of location and variety. The reduction in later harvests is the most significant and can be expected in the range of approximately 30-75%. So, according to the results, in the 30-year period (2041-2070) 30-75% of the years will no longer have the later harvest that took place in the period 1971-2000.

How to cite: Omazić, B., Telišman Prtenjak, M., Kvakić, M., Meštrić, J., Bubola, M., Prša, I., and Karoglan, M.: Changes in grapevine budburst and harvest dates in Croatia under current and future climate conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4051, https://doi.org/10.5194/egusphere-egu24-4051, 2024.

EGU24-4683 | Orals | CL2.7 | Highlight

Assessing winegrape suitability in a changing climate through phenology and thermal physiology   

Ignacio Morales-Castilla, Sofía Aguirre-Iglesias, Lara Río, Marta Fernández-Pastor, and Mercedes Uscola Fernández

There is a pressing need for cost-efficient adaptation of agriculture to a warming climate. An increasingly supported approach relies on leveraging varietal diversity, assuming that crop varieties exhibit distinct responses to climate, thereby providing a range of choices under various scenarios. This holds true for winegrapes, where considerable variability in phenological and physiological traits has been documented across varieties. However, it remains unclear whether phenology or physiology is more informative concerning varietal suitability to diverse climate conditions. Additionally, the extent to which phenology and physiology correlate in a predictable manner is still unknown, raising the question of whether one can be utilized as a surrogate of the other. In this study, we address these questions by examining understudied varieties of Iberian winegrapes as a case study. We integrate field phenological observations from the last decades with results from experiments determining the heat tolerance of eight varieties of Spanish and Portuguese winegrapes. Our findings reveal that there is no unequivocal relationship between phenology and thermal physiology. Specifically, later varieties, assumed to better cope with warming climates, do not consistently exhibit greater heat tolerance. These results suggest that phenology and heat tolerance are not interchangeable but instead represent complementary sources of information. Consequently, they can (and should) be integrated into assessments of the risk of thermal stress and climate suitability of winegrape varieties.

 

How to cite: Morales-Castilla, I., Aguirre-Iglesias, S., Río, L., Fernández-Pastor, M., and Uscola Fernández, M.: Assessing winegrape suitability in a changing climate through phenology and thermal physiology  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4683, https://doi.org/10.5194/egusphere-egu24-4683, 2024.

EGU24-4891 | Posters on site | CL2.7

Phenological responses to urban heat and light in the Greater Seoul area  

JiHyun Kim, Soyoung Sohn, and Yeonjoo Kim

Vegetation phenology is a critical indicator of terrestrial carbon and water dynamics; therefore, it is essential to understand its sensitivity to the changing climates, especially to rising temperatures. A wide range of phenological responses can be explored in urban areas where anthropogenic activities elevated temperatures as well as artificial lights. In this study, we analyzed one decade (2012 - 2021) of data on surface temperature, phenology, and land cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) and artificial lights at night (ALAN) data from the Visible Infrared Imaging Radiometer Suite (VIIRS) over the capital of South Korea and its surroundings. We calculated urban cover fractions (UCF) and estimated the long-term trends of the start of the season and the end of the season (ΔSOS and ΔEOS) and the temperature during the SOS and EOS (ΔTSOS and ΔTEOS) and in the ALAN (ΔALAN). We then investigated how much of those factors (i.e., ΔT, ΔALAN, and UCF) contributed to the ΔSOS and ΔEOS and explored temperature sensitivities of the ΔSOS and ΔEOS under different conditions. We found that the SOS appeared to advance by three days per decade (p = 0.068), while the EOS was delayed significantly (p < 0.001) by four days per decade over most of the study region. We also noticed that 70% of ΔSOS was primarily attributed to UCF, while ΔTSOS drove the rest. For the ΔEOS, the influence of ΔALAN appeared to be substantial (26%), with ΔTEOS having a similar contribution level (31%). We show that the temperature sensitivity of ΔSOS is higher by 4.5% in the highly urbanized areas, and the temperature sensitivity of ΔEOS is 4.3% higher in the regions with increasing lights. Our results suggest that vegetation phenological response to the increasing temperature would become complicated with the increases of urban-like conditions (i.e., higher levels of CO2 concentration), therefore highlighting the importance of further studies for a better understanding of terrestrial vegetation responding to the changing climates.

This study is supported by the National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT) (2020R1C1C1014886 and 2022R1C1C2009543), the Korea Agency for Infrastructure Technology Advancement (KAIA) grant funded by the Ministry of Land, Infrastructure, and Transport (22CTAP-C163540-02), and the Korea Environment Industry & Technology Institute (KEITI) funded by Korea Ministry of Environment (2022003640002).

How to cite: Kim, J., Sohn, S., and Kim, Y.: Phenological responses to urban heat and light in the Greater Seoul area , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4891, https://doi.org/10.5194/egusphere-egu24-4891, 2024.

EGU24-5594 | Posters on site | CL2.7

Spatial analysis of the annual and seasonal aridity trends in the Main Olive-Growing Areas of Extremadura (southwestern Spain) 

Francisco Jesús Moral García, Francisco javier Rebollo Castillo, Cristina Aguirado Montero, Lourdes Rebollo Moyano, Abelardo García Martín, Luis Lorenzo Paniagua Simón, and Fulgencio Honorio Guisado

Understanding drought, or wetness, conditions is essential not only for the rational use of water resources but also for explaining landscape and ecological characteristics. Climate change is expected to lead to an increase in aridity in many parts of the world. In semi-arid regions with warm climates, aridity poses a significant hazard, leading to the potential for desertification due to increased precipitation variability and prolonged droughts. Aridity indices can be employed to identify areas susceptible to desertification. In order to analyse the distribution of aridity in Extremadura, particularly in the areas covered by the olive oil denominations of origin in this region (the cultivation of olive trees is of great economic and social importance in Extremadura), the De Martonne aridity index (IDM) has been used. Temperatura and precipitation data from 81 weather stations located throughout Extremadura, within the 1951–2010 period, were utilised to calculate IDM at every station. Later, the IDM was mapped using an integrated Geographic Information System (GIS) and a multivariate geostatistical approach (regression-kriging) that incorporated comprehensive secondary information on elevation. Annual an seasonal IDM-kriged maps were generated. Finally, temporal trends were analysed using the Mann-Kendall test, and the Sen’s estimator was utilised to estimate the magnitude of trends. An increase in aridity, as the IDM decreased, was apparent during the study period, mainly in the more humid locations of the north. An increase of the seasonal IDM was also found, but it was only statistically significant in some locations in spring and summer, with the highest decreasing rate in the north of Extremadura. Although the denominations of origin in the north of the region have higher decreasing rates, leading to a drier climate, the areas in the centre and south of the region and, in consequence, the denominations of origins within these areas, with more arid climates, can be more seriously affected by the increasing aridity.

Keywords: Aridity; Climate Change; De Martonne aridity index; Extremadura; Olive tree.

How to cite: Moral García, F. J., Rebollo Castillo, F. J., Aguirado Montero, C., Rebollo Moyano, L., García Martín, A., Paniagua Simón, L. L., and Honorio Guisado, F.: Spatial analysis of the annual and seasonal aridity trends in the Main Olive-Growing Areas of Extremadura (southwestern Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5594, https://doi.org/10.5194/egusphere-egu24-5594, 2024.

EGU24-6105 | Posters on site | CL2.7

Analysis of the optimal temperatures for the synthesis of carbohydrates during the productive period of the olive tree in the olive-growing areas of Extremadura, Spain. 

Fulgencio Honorio Guisado, Cristina Aguirado Montero, Luis Lorenzo Paniagüa Simón, Ablardo García Martín, Lourdes Rebollo Moyano, Francisco Javier Rebollo Castillo, and Francisco Jesús Moral García

Climate is considered one of the most influential factors in vegetative development, formation and quality of fruits. The study based on bioclimatic indices and the orography of a territory makes it possible to evaluate its suitability for a specific crop and find areas with particularities. This study shows the analysis and trend of the Number of Days with Optimal Temperatures for Carbohydrate Synthesis (NDCHS), in the 12 olive-growing areas (270,000 ha) of Extremadura (Southwest of Spain). Based on the average daily temperature of the 75 climatic stations located in the olive-growing areas, the NDCHS was calculated for the period 1990-2021. To determine the trend, the Mann-Kendal test and Sen's slope estimator were used, and the Pearson test was used to obtain the correlation between the climatic variables. The results show an annual average of 111 days for the NDCHS. The minimum value was found in Ibores with 100 days and the maximum in Vegas del Guadiana with 120 days. The Pearson correlation obtained a maximum value of 0.848 with the average temperature. The Mann-Kendall test showed significant increasing trends in 8 of the 12 olive-growing areas with a minimum of 0.34 (Sen's slope) in Logrosán-Guadalupe and a maximum of 0.76 for the regions of Alburquerque and Vegas del Guadiana. A general average increase of 0.54 NDCHS per year was found for the olive-growing regions in the period studied.

Keywords: Olive tree, Extremadura, olive-growing areas, carbohydrates

How to cite: Honorio Guisado, F., Aguirado Montero, C., Paniagüa Simón, L. L., García Martín, A., Rebollo Moyano, L., Rebollo Castillo, F. J., and Moral García, F. J.: Analysis of the optimal temperatures for the synthesis of carbohydrates during the productive period of the olive tree in the olive-growing areas of Extremadura, Spain., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6105, https://doi.org/10.5194/egusphere-egu24-6105, 2024.

EGU24-6301 | ECS | Orals | CL2.7

Leveraging Citizen Science and Machine Learning for Plant Phenology Monitoring 

Negin Katal, Michael Rzanny, Patrick Mäder, Hans Christian Wittich, David Boho, and Jana Wäldchen

Plant phenology investigates the timing of critical events in a plant's life cycle, encompassing budburst, flowering, fruiting, and senescence, with their significance rooted in their responsiveness to environmental conditions. Despite the growing interest in phenology, challenges persist in documenting these processes due to their extensive spatial and temporal scales.

While global phenological networks traditionally collect data at the individual scale, a concern is arising regarding the declining number of phenological observers, prompting questions about the future of these datasets. Simultaneously, the surge in plant identification apps among citizens has yielded a substantial volume of plant occurrence records, accompanied by plant images, spanning diverse temporal and spatial scales.

In this study, we explore the viability of utilizing opportunistically captured plant observations gathered through a plant identification app to determine the onset of flowering. Additionally, we investigate how citizen science-based phenological monitoring can be enhanced by incorporating images generated by the app. To achieve this, we developed a machine learning-based workflow enabling the automatic annotation of thousands of images into specific phenological stages. Beyond examining the onset of flowering, our established methodology allows for the exploration of other phenological stages, such as budburst or fruiting, on a large scale.

Subsequently, we compare these opportunistic phenological records with systematically collected data from phenological networks. This approach not only streamlines image annotation but also augments the usefulness of citizen science data for phenological monitoring purposes.

How to cite: Katal, N., Rzanny, M., Mäder, P., Wittich, H. C., Boho, D., and Wäldchen, J.: Leveraging Citizen Science and Machine Learning for Plant Phenology Monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6301, https://doi.org/10.5194/egusphere-egu24-6301, 2024.

EGU24-6333 | ECS | Posters on site | CL2.7

Phenological characterization of major winegrape varieties in the Iberian Peninsula 

Marta Fernandez Pastor and the Iberian Future Wines Research Team

The phenology of wine grapes has emerged as a crucial aspect for comprehending and forecasting the impacts of climate change on viticulture. This is due to phenology being essential in evaluating the suitability of grape varieties to future conditions. However, there is still a lack of quantitative characterization for key phenological stages in a majority of indigenous wine grape varieties from Spain and Portugal. Here we analyze the phenological responses to climate of predominant grape varieties in the Iberian Peninsula, including Tempranillo, Airen, Garnacha, Macabeo, and other varieties like Albariño, Godello, Pedro Ximenez, Fernão Pires (Portugal), which are extensively cultivated in specific regions. We compiled a comprehensive dataset from research centers and specialized organizations such as Origin Denominations across the Iberian Peninsula. The recorded field observations were then compared against well-established agroclimatic indices, such as Growing Degree Days (GDD), days with maximum temperature above 35°C, or days below 10ºC, amongst others. Even within our limited set of varieties, we observed surprising diversity in responses, supporting phenology-based varietal selection as an adaptive solution. This underscores the necessity to continue documenting phenology for many other locally understudied varieties. Our findings fill a knowledge gap, contributing to ongoing efforts in refining varietal selection strategies for adapting viticulture to climate change.

How to cite: Fernandez Pastor, M. and the Iberian Future Wines Research Team: Phenological characterization of major winegrape varieties in the Iberian Peninsula, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6333, https://doi.org/10.5194/egusphere-egu24-6333, 2024.

EGU24-6646 | Orals | CL2.7

Assessing wood formation phenology with dendrometers: opportunities and pitfalls 

Cyrille Rathgeber and Ignatius Adikurnia

Comprehending the development, function, and adaptation of trees to changing environments requires a comprehensive understanding of the phenology of wood formation. In recent decades, numerous studies have investigated the impact of climate change on wood formation, with a focus on the start, end, and duration of the growing season. While some studies use microcores to directly observe wood phenology on anatomical sections, which requires a great deal of laboratory work, many others use indirect observations of variations in trunk circumference measured using dendrometers. However, it has not yet been properly assessed whether dendrometer records can provide reliable estimates of the phenology of wood formation.

To answer this question, we collected weekly data from band dendrometers and wood microcores of six important European species (European beech, European larch, Norway spruce, Scots pine, silver fir, and pedunculate oak) growing at five different study sites located in eastern France over a period of three years or more. Classical logistic growth curves were used to fit dendrometer measurements to determine the days of the year when 5% and 95% of total annual growth are completed. Almost direct observations of the beginning and end of wood growth were obtained by processing and analyzing microcores.

At the beginning of the growing season, dendrometer estimates and microcore observations were in agreement for fir and spruce trees. However, for larch, beech, pine, and oak trees, dendrometer estimates were consistently delayed by approximately 10, 13, 15, and 25 days, respectively. At the end of the growing season, the dendrometer approach did not yield significant differences for fir, larch, spruce, and oak trees. However, it provided earlier estimates for beech and later estimates for pine trees. Reduced major axis regressions indicated significant linear relationships between dendrometer estimates and microcore observations for fir, spruce, pine and beech at the beginning of the growing season and for fir, beech and oak at the end.

The study explored the impact of tree species' life traits on the deviation level between the dendrometer and microcore approaches. The results indicate that deviation decreases with an increase in growth rate, but increases with greater heterogeneity of tree-ring structure (from diffuse-porous to conifer and ring-porous tree-rings) and roughness of the bark (from smooth or scaly to fissured bark types). The study revealed that deviation decreases with elevation for larch trees in the southern Alps. Conversely, for beech, fir, pine, spruce, and oak trees in the northeast of France, deviation increases with spring precipitation.

This study highlights the challenges associated with using band dendrometers to estimate wood formation phenology. While the 'cheap and fast' band dendrometer approach may seem like an attractive alternative to the 'expensive and labor-intensive' microcore approach, it is important to consider the limitations of this method. Indeed, our results indicate that the accuracy of band dendrometers estimates depends on tree growth rate, species life traits, site conditions, and climate variability. Therefore, it may be challenging to use them to investigate tree adaptation to climate changes and changes in woody carbon sequestration.

How to cite: Rathgeber, C. and Adikurnia, I.: Assessing wood formation phenology with dendrometers: opportunities and pitfalls, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6646, https://doi.org/10.5194/egusphere-egu24-6646, 2024.

EGU24-7233 | Posters on site | CL2.7 | Highlight

Enhanced secondary growth induced by warmer temperatures in early summer advances autumn leaf senescence in temperate saplings 

Yann Vitasse, Shilong Ren, Charlotte Grossiord, Manuel Walde, and Constantin Zohner

Phenological events in temperate plants are highly dependent on external factors such as temperature and photoperiod, but also on internal factors linked to the plant's development. Recent studies have demonstrated a strong correlation between the timing of autumn leaf senescence in temperate trees and temperature conditions before the summer solstice that alter the rate of plant development. However, experimental evidence to specifically test this hypothesis is lacking. Here, we examined how accelerated growth in early summer induced by warmer temperatures affects the timing of senescence in three common European trees: Carpinus betulus, Tilia cordata and Acer platanoides. Potted saplings were grown under "ambient" open top chambers (OTCs), i.e. with similar temperature as outside the OTC, and under actively warmed OTCs, i.e. +5°C above the ambient, from January until the summer solstice. At the summer solstice, all the potted trees were transferred to an unheated greenhouse, sharing the same climatic conditions until leaf fall in autumn. Plant diameter and height were measured before bud burst, at the summer solstice and after leaf senescence. In addition, gas exchange measurements were conducted before and after the summer solstice to assess leaf performance. Finally, leaf senescence was measured weekly, visually and using a chlorophyll meter, from August until leaf fall.

Leaf-out dates were strongly advanced in the warming treatment for all species (14–28 days). Primary growth was not affected by warming for any species whereas secondary growth was significantly enhanced in the warming treatments for C. betulus and T. cordata. Interestingly, the initiation of leaf senescence occured significantly earlier for the saplings that were subjected to warmer temperature in early summer for C. betulus and T. cordata but not for A. platanoides, suggesting an effect of secondary growth rate during early summer in regulating the start of leaf senescence. Chlorophyll content, photosynthesis and SLA also showed significant differences between the two temperature conditions applied in early summer for C. betulus and T. cordata, even when measured several months after their transfer to the same conditions. Specifically, at the end of summer, leaves that were exposed to the warming treatment in early summer were less efficient for carbon assimilation, had lower chlorophyll content, showed higher SLA (T. cordata only) and started coloration earlier than the ones kept under ambient conditions during early summer.

Our results suggest that there is a strong link between growth development in spring and the timing of leaf senescence onset in autumn as recently shown at large scale in the northern hemisphere. More studies focusing on molecular and/or on tree physiological mechanisms should be conducted to identify the underlying mechanisms responsible for the link between secondary growth rate in early summer and the onset of leaf senescence. 

How to cite: Vitasse, Y., Ren, S., Grossiord, C., Walde, M., and Zohner, C.: Enhanced secondary growth induced by warmer temperatures in early summer advances autumn leaf senescence in temperate saplings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7233, https://doi.org/10.5194/egusphere-egu24-7233, 2024.

EGU24-8438 | ECS | Posters on site | CL2.7

Parameterization and verification of the STICS model for grapevines in the region of Croatia 

Josip Meštrić, Maja Telišman Prtenjak, Branimir Omazić, and Marko Kvakić

Many studies have shown how changes in air temperature affect the dates of occurrence of phenological phases. Grapevine plays a significant socio-economic role, both in Croatia and throughout the entire Mediterranean region. 'Graševina' and 'Plavac mali' are the most represented varieties in Croatia, so the emphasis in this research is on them at four different locations: Daruvar, Križevci, Hvar, and Lastovo. In addition to 'Graševina' and 'Plavac mali,' international varieties such as 'Chardonnay' and 'Merlot' were also observed.

STICS is a plant development model that simulates the soil-plant-atmosphere relationships based on the water, carbon, and nitrogen balance required for the growth of different crops, whether annual and/or perennial, herbaceous and/or woody.

The optimization of parameters was carried out using the implemented Nelder-Mead simplex method. Although it is desirable to optimize as many parameters as possible, in reality, increasing the number of parameters complicates the model. Therefore, it is necessary to find a compromise and determine the minimum number of parameters sufficient for quality optimization. In this work, 10 parameters were selected. These are parameters that are common to all predefined varieties and had different values.

During measurements, the STICS model showed satisfactory results at three out of four observed stations. The model verification demonstrated success with correlations primarily between r=0.6 and r=0.8. The performance of the model can be visually represented in various ways. In this work, two methods were employed: QQ plot and Taylor diagram.

Phenological and meteorological data from the Croatian Meteorological and Hydrological Service were used.

How to cite: Meštrić, J., Telišman Prtenjak, M., Omazić, B., and Kvakić, M.: Parameterization and verification of the STICS model for grapevines in the region of Croatia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8438, https://doi.org/10.5194/egusphere-egu24-8438, 2024.

Understanding the factors driving leaf-out times in temperate and boreal trees is increasingly vital in the context of rapid climate change, as it is crucial for predicting ecosystem dynamics. This study investigates if and how the sensitivity of spring phenology to temperature (St) has evolved in recent decades, especially given the ongoing debates about the extent and direction of future phenological shifts. Leaf-out times are influenced by a mix of spring warming, winter chilling, and day length, with their significance varying across different species. However, climate change could reduce St due to warmer climates and earlier spring onset, potentially enhancing winter chilling and day length constraints. To evaluate the relative importance of these factors, we conducted a comprehensive analysis using both long-term ground observations and satellite-derived phenology data, covering a span of six decades. Our approach included simulations to better understand the mechanisms behind variations in species-level Ts. This research aims to determine whether the phenological responsiveness of trees to climate change is decreasing, taking into account both environmental and physiological factors. Our findings challenge the prevailing belief of a consistent decline in St sensitivity, underscoring the need for a more nuanced understanding of the drivers behind leaf-out phenology in a changing climate. This study adds to the ongoing discourse on how global warming shapes natural phenomena and is pivotal for forecasting how ecosystems will respond to environmental changes.

How to cite: Zohner, C.: Quantifying changes in temperature sensitivity of spring phenology over recent decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9812, https://doi.org/10.5194/egusphere-egu24-9812, 2024.

EGU24-10021 | ECS | Posters on site | CL2.7

Analysis of meteorological variables influence on the growing season in Europe 

Petra Dížková, Lenka Bartošová, Markéta Poděbradská, Monika Bláhová, Milan Fischer, Daniela Semerádová, Jan Balek, Lenka Hájková, Zdeněk Žalud, and Miroslav Trnka

Using remote sensing data to assess plant phenology is a useful method for monitoring areas at larger spatial scales. One of the most widely used methods for analyzing changes in the timing of the growing season is the employment of vegetation indices and phenological metrics (phenometrics) derived from them. Using phenometrics, it is possible to evaluate changes in the growing season for different land covers and different environmental conditions not only at the local level but also in larger areas. At the larger scales, the meteorological conditions and especially their influence on plant phenology can be more diverse. For the determination of basic phenometrics (the start of the growing season (SOS), the end of the growing season (EOS), and the length of the growing season (LGS)), we used Enhanced Vegetation Index2 (EVI2) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. Phenometrics and their trends were calculated for four different land covers (arable land, broad-leaved forest, coniferous forest, and grassland) in the time period from 2000 to 2022 in the central European region. Furthermore, the changes in the timing of the growing season were calculated in different altitude and environmental zones and their trends were compared with meteorological variables (e.g., minimum and maximum air temperature, length of day, global radiation, precipitation, soil moisture, etc.). Based on this analysis, the main factors influencing phenological changes for different land covers were evaluated in different environmental conditions.

Acknowledgment: This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic (grant AdAgriF - Advanced methods of greenhouse gases emission reduction and sequestration in agriculture and forest landscape for climate change mitigation (CZ.02.01.01/00/22_008/0004635).

How to cite: Dížková, P., Bartošová, L., Poděbradská, M., Bláhová, M., Fischer, M., Semerádová, D., Balek, J., Hájková, L., Žalud, Z., and Trnka, M.: Analysis of meteorological variables influence on the growing season in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10021, https://doi.org/10.5194/egusphere-egu24-10021, 2024.

EGU24-10317 | ECS | Orals | CL2.7

Modeling Olive Phenological Phases for Agro-Climate Risk Assessment in a Changing Future Climate over the Euro-Mediterranean Region 

Ali Didevarasl, Jose M. Costa-Saura, Donatella Spano, Richard L. Snyder, Pierfrancesco Deiana, Diana Rechid, Katharina Bülow, Maurizio Mulas, Giovanni Nieddu, and Antonio Trabucco

Under a future changing climate, the Mediterranean is considered a region extremely prone to global warming and intensified climate events, which will possibly change the timing of phenological phases and alter conditions and risks for olive tree growth. This situation may restrict olive cultivation which is economically strategic in the Mediterranean countries. Since, the timing and management of agronomic practices (planting, irrigation, fertilization, crop protection, harvesting, etc.) are based on phenological phases and plant growth, accurate phenological projections are essential to assess climate risks and guide optimal management apt to mitigate climate change effects on olive development. Initially, the present investigation aims to introduce innovative phenological modeling, i.e., Chill, Anti-Chill, and Growing Degree Days combined model (CAC_GDD) applicable in heterogenous areas with limited and scattered observations. Then, we project future changes in olive phenological phases (i.e., sprouting, blooming, and pit hardening) and relevant agro-climate stressors during these phases over the Euro-Mediterranean for both early and mid-late bud break cultivars. For model parametrization and validation, the phenological observations were gathered from nine experimental sites in Italy and temperature time-series from the European Centre for Medium-Range Weather Forecasts, Reanalysis v5. To project the timing of phenological phases and then calculate the agro-climate stressors we used an ensemble of high-resolution climate projections at 0.11° from EURO-CORDEX (Coordinated Regional Climate Downscaling Experiment) repository, for two historical (1976-2005) and future (2036-2065) 30-year periods under three emission scenarios (i.e., RCP2.6, RCP4.5, and RCP8.5). The CAC_GDD modeling showed the best performance (RMSE: 4 days) for the blooming phase of mid-late cultivars, suiting similarly and in some cases even better than the more complex model to our experimental conditions. The spatial phenological projection illustrated that at least 75% of the Euro-Mediterranean area will experience significant phenological advances for olive crops. Meanwhile, current olive cultivations in the Mediterranean basin may face accelerated climate extremes mainly at blooming and pit hardening stages in the future. Hence, we expect possible future shifts in olive-growing areas from the Mediterranean to colder regions with more thermal suitability for the mid-late cultivars.

How to cite: Didevarasl, A., Costa-Saura, J. M., Spano, D., Snyder, R. L., Deiana, P., Rechid, D., Bülow, K., Mulas, M., Nieddu, G., and Trabucco, A.: Modeling Olive Phenological Phases for Agro-Climate Risk Assessment in a Changing Future Climate over the Euro-Mediterranean Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10317, https://doi.org/10.5194/egusphere-egu24-10317, 2024.

EGU24-10492 | ECS | Orals | CL2.7

Earlier flowering onset induced by air heating occurs only in certain grassland species in the Giessen T-FACE experiment 

Philipp Dehn, Uwe Grüters, Gerald Moser, and Christoph Müller

This study investigates the flowering onset of species in an extensively managed, temperate grassland under future atmospheric conditions. Free air CO2 enrichment experiments combined with a warming treatment via IR heaters (T-FACE) are state of the art for investigating future developments in terrestrial ecosystems. This study presents the first results of a new approach to T-FACE technology. In this experiment, the air temperature is increased directly via heating elements, thus creating more realistic environmental conditions for future climate studies.

Plant phenology, a widely used indicator of changing environmental conditions, was therefore one of the first subjects to be investigated with the new system. Four grasses and five herbaceous plants were monitored several times a week for the onset of flowering over a period of five years.

These were Arrhenatherum elatius, Holcus lanatus, Poa pratensis, Trisetum flavescens as well as Draba verna, Galium album, Geranium pratense, Glechoma hederacea and Sanguisorba officinalis.

While significantly earlier flowering was observed in some species, other species showed no change in the onset of flowering. Results suggest that changes in the onset of flowering were mainly seasonal and independent of the functional plant group.

How to cite: Dehn, P., Grüters, U., Moser, G., and Müller, C.: Earlier flowering onset induced by air heating occurs only in certain grassland species in the Giessen T-FACE experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10492, https://doi.org/10.5194/egusphere-egu24-10492, 2024.

EGU24-10858 | ECS | Orals | CL2.7

SwissPhenoCam: Country-scale automated tree-phenology tracking from webcam imagery. 

Vivien Sainte Fare Garnot, Maaike de Boer, Lynsay Spafford, Jelle Lever, Christian Sigg, Barbara Pietragalla, Roman Zweifel, Yann Vitasse, Arthur Gessler, and Jan Dirk Wegner

Large-scale, high-quality phenological observations of trees are key to a better understanding of the environmental factors that control phenological processes, as well as their responses to a changing climate. Over the last decades, phenocams (i.e., webcams capturing time-lapse images of individual plants,  canopies, or communities) have been shown to be a reliable compromise between ground based human observation and satellite remote sensing. Phenocams combine the advantages of automated, real-time data acquisition and a high resolution that allows for the monitoring of individual organisms. Here, we focus on tree species in Switzerland and lay the foundation for a country-scale phenocam network.

In comparison to the global spatial coverage of satellite data, phenocam coverage is bound by the local implantation of cameras. To mitigate this limitation, we integrated a diversity of sources into our data pipeline: weather cameras, private cameras (e.g., from hotel or ski resorts), as well as cameras specifically installed for phenological observation. Combining those sources, we identified over 150 potential sites across the Swiss territory with cameras installed by the same industrial provider. In our first iteration, we focused on 27 of those sites, prioritizing based on the amount of clearly visible trees. We collected the image time series for each location with up to 12 years of site-level history. Due to the diversity of image sources the temporal resolution varied between 1 and 144 images per day. For each of the sites, we annotated the polygon delineating the boundaries of each tree, or group of trees in image pixel coordinates. Next, we identified the species of each tree via on-site visual inspection. Our dataset contains over 1,700 polygons of individual trees, covering over 20 predominant tree species of Switzerland, and over 1,300 polygons of groups of trees categorized into 5 classes.

To obtain phenological observations from this dataset, we adopt two distinct approaches. First, to relate to on-site observations, we reprocess the data for easy visual inspection and developed an ontology of 16 phenophases (e.g., ‘start of leaf unfolding’, ‘leaf maturity’, ‘start flowering’) that can be readily observed by a human from webcam imagery. Phenophases were defined such that they are meaningful for phenological studies and can be matched with Swiss Phenology Network observations where possible. The visual analysis of the images by phenology experts yields over 13,000 different phenological observations.  Second, to relate to satellite-based phenology metrics, we identified changes in greenness over time for each polygon which correspond to leaf development. 

In this communication, we show our dataset preparation pipeline, as well as a comparative study of the phenological metrics obtained via different means on the same trees: visual analysis of the images, greenness extraction, and citizen network reports. In future works, we will explore how this dataset can be used to train machine learning methods to predict phenological phases from the image time series. We will explore if machine learning methods can allow for precise phenophase identification like in visual inspection, while  being fully automated like greenness extraction.

How to cite: Sainte Fare Garnot, V., de Boer, M., Spafford, L., Lever, J., Sigg, C., Pietragalla, B., Zweifel, R., Vitasse, Y., Gessler, A., and Wegner, J. D.: SwissPhenoCam: Country-scale automated tree-phenology tracking from webcam imagery., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10858, https://doi.org/10.5194/egusphere-egu24-10858, 2024.

Via electronic media like smart phone apps volunteer observers of phenological networks are able the immediately transmit their eye observations and photographs to the data base. Based on such real time observations some phenological network operators provide graphical displays of the current phenological development on their respective home pages. The graphical representation of near real time phenological observations allow a number of interesting and useful applications.

The numbers of phenological observations and of reporting observers can be monitored in real time. They typically reflect the seasonal variation of the frequency of phenological events with a strong spring maximum and a lesser autumn maximum. The effect of phenology related media releases on observation numbers can be assessed as well. The long term trend of active observer and observation numbers helps to evaluate the measures for recruiting and encouraging volunteer observers.

Another application is the quality control of phenological observations. Photographs of plants and their phases might be checked by the network operator and in case of species or phase misidentification the observer might be contacted for feedback from the operator. Many phenological phases display a distinct regression with station elevation, which helps to detect outliers via scatter plots.

Phenological real time observations are the basis for monthly phenology reports, which are published for instance on the phenowatch home page during the phenologically active season (www.phenowatch.at). In mid- to higher latitudes the sequence of cold/warm events are well reflected by the variations of the phenological progress.

The current phenological development of fruit trees may be combined with the expected daily minimum temperatures and thus provide a hint to potential late frost damage events during the frost sensitive flowering period.

Another application of real time phenological observations has emerged due to sponsoring of biodiversity enhancing measures for grassland (“The European Green Deal” for instance). Grass cutting dates can be optimised via phenological real time observations. Thus cutting dates are not unnecessarily late to the disadvantage of the farmer nor too early to the disadvantage of biodiversity.

Finally, monitoring phenological trends might be the most exciting topic to be accomplished via real time phenological observations. Currently observed phenological entry dates can be related to long term trends, whether they indicate a continuation, flattening or steepening of the trends. At the next level questions dealing with explanations of the trends, potential future phenological changes and their significances might be investigated. Climate impact on ecosystems as exemplified by phenology constitutes an important motivation to continue with the operation of phenological observation networks.

The phenology team at GeoSphere Austria, Austria’s national weather service, created during the last couple of years a number of graphical representations for the above mentioned purposes, which are being introduced in this poster.

How to cite: Scheifinger, H., Hübner, T., and Ressl, H.: Graphical representation of real time phenological information for the purpose of quality control, Citizen Science participation, media and climate impact monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10866, https://doi.org/10.5194/egusphere-egu24-10866, 2024.

Phenological shifts are crucial indicators of ecosystem responses to climate change. Complex feedbacks exist between the timing and length of temperate deciduous forest growing seasons and water, energy and carbon cycling. Understanding these feedbacks is essential for accurate future climate and forest productivity predictions. Despite knowing that warmer late-season temperatures postpone autumn senescence, extending the growing season, the specific drivers of autumn phenology remain unclear. Recent studies indicate that early-season warming may counteract these growing season extensions through developmental constraints. The compensatory point between these two antagonistic effects, i.e., the date when the effect of temperature on senescence reverses, may be governed by day length. However, the relative roles of early-season development and late-season temperature in driving autumn phenology need to be clarified. Our climate manipulation experiments on European beech (Fagus sylvatica) aimed to address this complexity. We show that cooling at different times of the day has inverse effects on beech's primary growth cessation, affirming that warming can either postpone bud set or advance it by speeding up development. By manipulating leaf-out timing we found that reduced early-season development delayed bud set (mean = 3.56 days, p = 0.002). The effect of cooling in July was more pronounced for the reduced-development (late-leafing) trees (mean = 5.27 days, p < 0.001). This indicates that the effects of temperature later in the season depend on early-season development, which, in turn, points to a flexible effect reversal date. However, cooling in August advanced bud set regardless of leaf-out timing (mean = -3.08 days, p < 0.001), indicating that temperature becomes increasingly important as a driver of autumn phenology as the late-season progresses. This study underscores the importance of accounting for both developmental and warming factors when predicting autumnal phenological shifts.

How to cite: Rebindaine, D., Zohner, C., and Crowther, T.: Disentangling the antagonistic effects of development and temperature on the autumn phenology of european beech using manipulative experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12385, https://doi.org/10.5194/egusphere-egu24-12385, 2024.

EGU24-13418 | Posters on site | CL2.7

Detecting species-specific changes in spring phenology of Mt Medvednica forests using NDVI obtained from remote sensing with MODIS  

Hrvoje Marjanović, Anikó Kern, Mislav Anić, Doroteja Bitunjac, and Maša Z. Ostrogović Sever

Estimating climate-change-induced changes in biological systems, e.g., tree phenology, requires long, consistent and reliable datasets. Phenology observations within meteorological and other ground observation networks provide invaluable data but are of limited geographical distribution and observational range. Remote sensing observations surpass such problems and have been extensively used in phenology research, but suffer from other issues such as coarse spatial resolution, relatively long observation repeat cycles, issues due to clouds, short observational time series, etc. Those issues limit the number of remote sensing platforms which are suitable for the analysis of possible changes in the phenology of forest tree species at a local or regional level. NDVI derived from the MODIS daily measurements of reflectances at 250 m resolution spanning from 2000, in combination with tree species distribution maps from forest management plans, might be an optimal tool for investigating recent shifts in species-specific tree phenology at a local or regional level. Increased frequency of climate extremes, such as late spring cold spells, combined with the sensitivity of deciduous trees to frost damage during leaf unfolding and flowering, threatens the health and regeneration capacity of forests. The possible decoupling of tree and animal phenology additionally strains the entire forest ecosystem. These problems are exacerbated in urban and peri-urban forests, such as forests in Mount Medvednica Nature Park, Croatia, which are of major importance to the well-being of the people living in the Zagreb metropolitan area. Urban and peri-urban forests are exposed not only to the effects of climate change but also to the negative effects of pollution and the ‘urban heat island’ which all affect the timing and duration of leaf unfolding. 
Our research aims to quantify the changes in the spring phenology of Mt Medvednica’s forests during the period 2000–2020 using MODIS NDVI at 250 m, local forest management maps with tree species distribution information, and a digital elevation model. Our results show a delay in the Start of Season (SOS) with the overall trend of 0.12 days·yr-1, but only due to SOS delay in common beech (F. sylvatica, 0.13 day·yr-1), which might be a consequence of delay in meeting the chilling requirement needed to end the dormancy. Other deciduous tree species showed no significant trend in SOS. On the other hand, the End of Green-up (EOG) occurred sooner for all investigated tree species, with an average trend in EOG of –0.18 days·yr-1 (F. sylvatica and Q. pubescens, –0.17; Q. cerris,  0.21; Q. petrea and Castanea sativa, –0.23 day·yr-1). Consequently, during the 21 years of observation, the duration of leaf development of Mt Medvednica’s forests was on average shortened by 6.5 days.

Keywords: phenology, leaf unfolding, MODIS, NDVI, peri-urban forests, Mount Medvednica.

Acknowledgements:
The research has been supported by the Croatian Science Foundation project MODFLUX (HRZZ IP-2019-04-6325), by the Hungarian Scientific Research Fund (OTKA FK-146600) and by the TKP2021-NVA-29 project of the Hungarian National Research, Development and Innovation Fund. We thank to Croatian Forests Ltd. for granting access to their forest database and Croatian Meteorological and Hydrological Service for providing meteorological data.

How to cite: Marjanović, H., Kern, A., Anić, M., Bitunjac, D., and Ostrogović Sever, M. Z.: Detecting species-specific changes in spring phenology of Mt Medvednica forests using NDVI obtained from remote sensing with MODIS , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13418, https://doi.org/10.5194/egusphere-egu24-13418, 2024.

A phenology project was launched in 2020 in the Eastern Townships region of southern Quebec, Canada, with the help from students from Bishop’s University. Initially, one of the main goals was to boost local phenology observations and gather data that will become useful in the future to document the impacts of climate change. We also wanted to pair the pollen monitoring programme that exists in Sherbrooke since 2006 with directs phenological observations of the local vegetation. The other goal of TreeTraque is to increase people's awareness of the impacts of climate change on vegetation.

 

Riding on the momentum generated by the recent adoption of the politique de l’arbre (tree- or greening policy) by the city of Sherbrooke and by the push from numerous conservation organizations within the region, we are now adding a knowledge mobilization component to the project. We wish to reach the genera public more broadly to educate them about the importance of trees in the urban environment: they combat the urban heat island effect, capture atmospheric pollution, and enhance the esthetics of a neighbourhood. A few greening programs are already in place in Sherbrooke, however, they only aim at planting trees on institutional, industrial and commercial lots. It appears important to raise awareness among the general population, especially homeowners. Indeed, in some neighbourhoods, we see that numerous owners choose not to have trees on their property or prefer shrubs or plants that do not provide any shade on buildings, streets or driveways. Our long-term objective is to create more shade to help combat the urban heat island effects and reduce the impacts of future heat waves.  

How to cite: Levac, E. and Courtemanche, B.: Phenology and knowledge mobilization about the importance of trees in urban environments in southern Quebec, Canada, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14009, https://doi.org/10.5194/egusphere-egu24-14009, 2024.

EGU24-14988 | ECS | Orals | CL2.7 | Highlight

Roe Deer and Plant Phenology Nexus – Match or Mismatch? 

Johanna Kauffert, Christian Ehrmantraut, Piotr Tryjanowski, Peter Mikula, Andreas König, and Annette Menzel

Plasticity and factors driving parturition dates of ungulates is a topic that has been addressed in many studies. These factors potentially give us clues about a possible trophic mismatch between the timing of seasonal events and resources due to an earlier onset of phenological spring introduced by climate change. Particularly, roe deer (Capreolus capreolus L.), the most widespread and abundant ungulate in Central Europe, has been a species of great concern. As an income breeder, it must finance the energy-demanding end of gestation and lactation by currently available resources in spring. Yet, roe deer is the only artiodactyl species known to undergo embryonic diapause, a temporal suspension of embryonic development, for four to five months after mating in summer. Hence, it could potentially adjust the end of embryonic diapause to shifting environmental conditions to match the parturition of their offspring with the advancing greening in spring. Potentially resulting shifts in parturition timing in May and June are also of great interest to farmers as parturition and rearing of fawns coincide with annual spring mowing. Due to the fawns’ hiding strategy to protect themselves from natural predators, they often fall victim to approaching mowing machinery. Although farmers are legally obliged (in Germany) and are already untiringly searching meadows before mowing, not all fields can be searched simultaneously when mowing is constrained to short time windows due to periods of favourable weather for hay and silage production. Therefore, knowledge about the much-debated plasticity to environmental conditions in roe deer may provide helpful information for preventing accidental mowing death of fawns in spring by anticipating when most of the young and immobile fawns are forecasted to be present in the meadows and allocating targeted measures.

How to cite: Kauffert, J., Ehrmantraut, C., Tryjanowski, P., Mikula, P., König, A., and Menzel, A.: Roe Deer and Plant Phenology Nexus – Match or Mismatch?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14988, https://doi.org/10.5194/egusphere-egu24-14988, 2024.

EGU24-15091 | ECS | Posters on site | CL2.7

Exploring the role of functional traits in regulating the spatial and temporal variability in land surface phenology across temperate forests 

Yingyi Zhao, Zhihui Wang, Zhengbing Yan, Minkyu Moon, Dedi Yang, Lin Meng, Solveig Franziska Bucher, Jing Wang, Guangqin Song, Zhengfei Guo, Yanjun Su, and Jin Wu

Plant phenology, the study of recurring plant life history events’ timing, is a key indicator of global environmental change and significantly impacts ecosystem functions and services. Land surface phenology (LSP) characterizes plant phenology by monitoring seasonal plant canopy structure dynamics via satellites. Numerous studies have demonstrated that ecosystem-scale LSP variability is mainly driven by climate and environmental conditions across different ecosystems. However, significant spatial and temporal phenological variations are still observed within local landscapes where environmental conditions are relatively similar. This suggests that biotic factors may be important to regulating LSP variability, but their role in determining phenological variability has been underexplored. To address this knowledge gap, we selected four temperate forest sites with minor topographic relief to ensure the homogeneity of environmental conditions and examined how functional traits regulate intra-site spatial and temporal LSP variability. We combined plant functional traits derived from remote sensing data with multi-year Harmonized LandSat-Sentinel-2 (HLS) data to investigate the effects of functional traits on phenological variability. For spatial LSP variability, we assessed the extent to which functional traits could explain the variation in the start of season (SOS) and end of season (EOS). We found that functional traits showed a substantial explanatory power for spatial phenological variability across all the study sites, with cross-validation correlations (cv) ranging from 0.50 to 0.85. For temporal LSP variability, we used multi-year series of the two band Enhanced Vegetation Index (EVI2) to calculate the cumulative deviation of EVI2 values from their long-term means, which served as an indicator of temporal phenological variability. Functional traits also significantly contributed to the temporal variability across all sites, with cv ranging from 0.46 to 0.71. Furthermore, our results show that plant traits related to vegetation competitive ability and productivity (e.g., canopy height, plant area index, and leaf mass per area), are crucial to explaining intra-site phenological variability, but their relative contributions vary among different sites. Collectively, these results demonstrate that functional traits play a critical role in regulating intra-site spatial and temporal LSP variability, and plants employ diverse strategies to cope with the environment, which ultimately impacts various ecological processes.

How to cite: Zhao, Y., Wang, Z., Yan, Z., Moon, M., Yang, D., Meng, L., Bucher, S. F., Wang, J., Song, G., Guo, Z., Su, Y., and Wu, J.: Exploring the role of functional traits in regulating the spatial and temporal variability in land surface phenology across temperate forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15091, https://doi.org/10.5194/egusphere-egu24-15091, 2024.

EGU24-15552 | ECS | Orals | CL2.7

Intraspecific variation of spring and autumn phenology in Fagus sylvatica 

Ilka Beil, Nadine Pluquette, Nora Willenbockel, and Jürgen Kreyling

The timing of spring leaf out and autumn senescence needs to be well adapted to the climate at the particular site to ensure precise alignment with the change of the seasons.  From a tree species with a large distribution range covering wide parts of Europe, we would expect substantial variation the phenological characteristic and in the chilling requirements of different provenances. If climate is getting warmer and winters are getting shorter, the local adaptation to might not fit future climate anymore, so that the trees cannot take advantage out of an early start of the growing season or a late warm autumn.

In a provenance trial with young beech seedlings, we quantified the differences between spring leaf out and autumn senescence of the provenances and individuals. We further asked which climate parameters were the evolutionary drivers for those phenological characteristics. And we investigated, if there is a correlation between phenological timing and growth, assuming that early flushing and late colouring individuals would utilize the growing season better.

The difference between the earliest and the latest provenance in spring leaf out was 8 days and in autumn senescence 17 days. For spring leaf out, we tested for several climate parameters and found that the longer the winter with more days between 0 and 10°C at the place of origin, the later the trees leafed out in our common garden. This climate parameter reflects nicely the often-used quantification of chilling. So, at places were typically more chilling time occurs over winter, the trees developed higher chilling requirements.  But also, the lower the minimum temperature in winter at the place of origin, the earlier they leafed out in our common garden, which is less intuitive. For autumn, eastern provenances coloured their leaves earlier than western provenances if grown under the same climate. The growth of the seedlings will be measured in winter 2023/2024 and will be evaluated in relation to their provenances and to their phenological characteristics in the presentation.

How to cite: Beil, I., Pluquette, N., Willenbockel, N., and Kreyling, J.: Intraspecific variation of spring and autumn phenology in Fagus sylvatica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15552, https://doi.org/10.5194/egusphere-egu24-15552, 2024.

EGU24-16853 | Posters on site | CL2.7

Phenological variability between species of floodplain forests and the role of the pollinators 

Lenka Bartošová, Petra Dížková, Jana Bauerová, Jan Balek, Zdenka Křenová, Eva Svobodová, Monika Bláhová, Lenka Hájková, Martin Možný, Zdeněk Žalud, and Miroslav Trnka

The impact of climate change on phenological timing is well-known and described in the scientific literature. Most papers agree that rising temperature accelerates the onset of spring phenological phases. Nevertheless, there is more significant disagreement in the synchronicity or asynchronicity of phenological trends of individual species. In this study, therefore, we will work with long-term phenological data that have been observed continuously in floodplain forests (and relate to herbs, shrubs, trees, and bird populations) from 1961 to the present. The observed plants and bird species showed statistically significant (p < 0.05) shifts in phenological terms to an earlier year. Still, the rate of the shift among the observed species differed. The most progressive shifts were detected for the herbs (2.3 days per decade), followed by the shrubs (2.2 days per decade), trees (1.4 days per decade), and finally, the bird species (also 1.4 days per decade). There are many changes in trends within the specific species group – e.g., quite a considerable variability was detected for herbs – the phenophase ´full flowering´ trend is moving between 1.3 and 3.3 days per decade. For this reason, we also include the role of pollinators within this study - bumblebees (Bombus) as a new input to the phenological observations to see if there is any asynchrony between these early spring species.

 

Acknowledgment: This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic (grant AdAgriF - Advanced methods of greenhouse gases emission reduction and sequestration in agriculture and forest landscape for climate change mitigation (CZ.02.01.01/00/22_008/0004635).

How to cite: Bartošová, L., Dížková, P., Bauerová, J., Balek, J., Křenová, Z., Svobodová, E., Bláhová, M., Hájková, L., Možný, M., Žalud, Z., and Trnka, M.: Phenological variability between species of floodplain forests and the role of the pollinators, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16853, https://doi.org/10.5194/egusphere-egu24-16853, 2024.

EGU24-17491 | Orals | CL2.7 | Highlight

Plant macrophenological dynamics - from individuals to plant group behaviour using citizen science data 

Karin Mora, Michael Rzanny, Jana Wäldchen, Hannes Feilhauer, Teja Kattenborn, Guido Kraemer, Patrick Mäder, Daria Svidzinska, Sophie Wolf, and Miguel D. Mahecha

Understanding the implications of climate change on ecosystems necessitates continuous monitoring of plant phenology. While citizen science data collected through smartphone applications offer a rich source of information, existing phenology studies predominantly focus on individual species.

This study introduces a pioneering data science approach to quantify plant group behaviour from individual observations. Leveraging over ten million ground measurements of plant observations obtained through the Flora Incognita plant identification app in Germany from 2018 to 2023, our analysis unveils macrophenological patterns arising from plant group behaviour. The findings indicate nonlinear changes in group behaviour across the annual cycle.

Furthermore, we explore the relationship between these macrophenological patterns on the ground and phenology derived from remote sensing data. The growing databases of citizen science holds great potential to investigate climate-induced phenological shifts and provide valuable insights into plant group behaviour.

How to cite: Mora, K., Rzanny, M., Wäldchen, J., Feilhauer, H., Kattenborn, T., Kraemer, G., Mäder, P., Svidzinska, D., Wolf, S., and Mahecha, M. D.: Plant macrophenological dynamics - from individuals to plant group behaviour using citizen science data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17491, https://doi.org/10.5194/egusphere-egu24-17491, 2024.

EGU24-17609 | ECS | Posters on site | CL2.7

Are space-for-time substitution approaches appropriate in phenology research? Results from a macroecological approach 

Andrea L. Silva-Cala, Robert Rauschkolb, Solveig Franziska Bucher, Jens Kattge, Sönke Zaehle, and Christine Römermann

Knowing and understanding variation in plant phenology is important for three main reasons. 1. Plant phenology is sensitive to climate change, 2. Plant phenology influences the dynamics and interactions between species, and 3. It drives important ecosystem functions. Still, large-scale, macroecological analyses spanning several phenological databases from various continents and environmental conditions are scarce.

Here we present the first results of a global analysis of the relationship between phenological events and functional traits in herbaceous plant species as a basis for predicting variations in ecosystem functions. More specifically, we analyzed phenological data from three different data sources: the PEP725 database from Europe, the NPN database from the US, and the PhenObs database from a global network of botanical gardens (www.idiv.de/en/phenobs). We evaluate spatio-temporal variations of three phenological stages: leaf emergence, open flowers, and onset of senescence. We linked phenological variations in space as well as phenological variations in time with variations in temperature (extracted from CRU TS database v4.07) of the observation periods and observation sites, respectively. Deduced associations between phenology and temperature across time and space were compared between Europe and North America, and between controlled environments in botanical gardens and natural environments.

First results indicate that the direction of phenological responses to changes in temperature is consistent across time and space. However, the variability of this response is higher across time compared to space. This higher variation phenology is not explained by differences in variations of temperature, but we assume that other environmental and climatic factors could vary more strongly across the spatial compared to the temporal gradient. The phenological responses of plants growing in botanical gardens to increasing temperature, were less variable compared to plants growing in uncontrolled environments. We attribute these differences to botanic garden management, such as irrigation, which mitigates the effects of increased temperature and drought on herbaceous species phenology. On our poster, we will further determine the climatic factors and functional traits that explain inter- and intraspecific phenological variability.

How to cite: Silva-Cala, A. L., Rauschkolb, R., Bucher, S. F., Kattge, J., Zaehle, S., and Römermann, C.: Are space-for-time substitution approaches appropriate in phenology research? Results from a macroecological approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17609, https://doi.org/10.5194/egusphere-egu24-17609, 2024.

EGU24-18098 | Orals | CL2.7

How can phenology monitoring network data improve operational systems for regional yield prediction? A case study for winter wheat and grain maize in France with the WOFOST model.  

Julien Morel, Martin Claverie, Davide Fumagalli, Catherine Cauchard, Abir Mahajba, Marc Zribi, and Maurits van den Berg

Mechanistic, process-based crop models are a key component of operational systems for regional yield forecasting, such as the Mars Crop Yield Forecasting System (MCYFS) of the Joint Research Centre of the European Commission. Such systems usually rely on spatially explicit soil, weather and crop data to simulate crop growth, biomass accumulation and yield formation. 

In order to simulate crop growth over large regions, the MCYFS uses strongly simplified crop and management information. Phenology parameterization is a typical example of such simplification, as fixed sowing dates and values for phenological parameters are used across years and sub regions, resulting in potentially large differences between simulated phenology and reports from the field, ultimately reducing the accuracy of other simulated variables, such as leaf area index, biomass and yield. 

In this study, we use ground truth phenological data obtained during the past 10 years in France, with the crop model WOFOST (which is used in the MCYFS), to assess the effects of a more precise phenology parameterization on simulations and yield predictions. In addition, we built on findings from a recent study connecting phenological stages with Copernicus Sentinel-2 satellite time series to assess the operational potential of integrating remote sensing and crop modeling for the purpose of crop yield forecasting. 

The crop model WOFOST is used to simulate the growth and development of the two crops. WOFOST works at a daily time step and calculates daily biomass gains on the basis of underlying processes, such as photosynthesis, respiration, and how these processes are influenced by environmental conditions, such as irradiation, temperature and soil water conditions. Daily biomass gains are partitioned among plant organs depending on thermal-time-determined phenological stages. Phenology simulation is based on a temperature sum approach. Key phenological parameters include base temperature, set at 0 °C for wheat and 4 °C for maize, the thermal time from emergence to anthesis (TSUM1), the thermal time from anthesis to physiological maturity (TSUM2) and, in the case of wheat, a vernalization factor (Fv). 

Phenological data used in this study are derived from the “Céré’Obs” program (https://cereobs.franceagrimer.fr/cereobs-sp/), which aims to provide objective data on the status of major cereal crops in France. Data are provided at the level of administrative regions. In this study, winter wheat and grain maize are considered, from 2012 onwards. 

Baseline simulations are first performed with the standard MCYFS setting of WOFOST. Then, updated simulations are performed, following a two-step approach: first, sowing dates are forced from Céré’Obs information for each year and region in France. Then, key phenological parameters TSUM1, TSUM2 and, in the case of wheat, Fv, are recalibrated so as to minimize differences between simulated phenology and ground observations. This parameterization update is performed both with Céré’Obs-collected information and remote sensing-derived information. Model’s outputs for both standard and updated simulations are finally compared against sub-national official yields. 

How to cite: Morel, J., Claverie, M., Fumagalli, D., Cauchard, C., Mahajba, A., Zribi, M., and van den Berg, M.: How can phenology monitoring network data improve operational systems for regional yield prediction? A case study for winter wheat and grain maize in France with the WOFOST model. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18098, https://doi.org/10.5194/egusphere-egu24-18098, 2024.

EGU24-18358 | Posters on site | CL2.7 | Highlight

Consequences of three years of drought in Catalonia 

Montserrat Busto and Xavier de Yzaguirre

Catalonia has been experiencing the most important drought since, at least, 1970. This three-year drought has not experienced any significant precipitation episodes and has particularly affected terrestrial ecosystems.

The Mediterranean vegetation, adapted to periods without rain, overcame the first year of drought (2021) without great phenological impact beyond specific places and individuals.

In the second year of drought (2022), the lack of water affected sprouting, fruiting, and leaf senescence, such as lower fruit productivity and smaller-than-normal fruit size.

During the third year of drought (2023), the strong water stress has directly threatened the survival of some monitored species. The ones that have not died present several phenological anomalies such as lack of flowering (with the consequent absence of fruit), minimal foliation, and drying of branches of the entire individual.

Such resilient species as holm oak, almond tree, grey-leaved cistus, olive tree, strawberry tree and grape have been affected. In the inland agricultural area of Catalonia irrigated by the Canal d'Urgell, there has been an obligation to limit support irrigation to a minimum to keep trees alive, which has caused the loss of the harvest in many places.

These three years without rain have been accompanied by an increase in the average temperature which has advanced ripening. Abnormally warm autumns have led to second blooms or re-sprouting of leaves (grape and shadow plane tree, for example). The mild temperature of the 2023 winter has complicated the structural pruning of the vine and other fruit trees due to the absence of the physiological winter stop.

How to cite: Busto, M. and de Yzaguirre, X.: Consequences of three years of drought in Catalonia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18358, https://doi.org/10.5194/egusphere-egu24-18358, 2024.

EGU24-18553 | ECS | Orals | CL2.7

Adapting Italian Agriculture to Climate Change: A MONICA Model Analysis of Chickpea and Lentil Phenology Shifts  

Alessandro Triacca, Gabriele Nerucci, Claas Nendel, Stefano Carlesi, Federico Leoni, and Anna-Camilla Moonen

The impact of climate change on agricultural systems is profound, prompting the need for adaptive crop management strategies. In this context, our study leverages the MONICA crop model, which has been finely tuned and validated using data from Italian chickpea and lentil field trials, to predict how these crops will respond to future climatic changes across Italy. Central to our research are two pivotal questions: firstly, the expected changes in chickpea and lentil phenology under future climate scenarios in Italy; and secondly, the strategies Italian farmers can employ to adjust to these phenological shifts, thereby optimizing the production of these legumes in potentially shifting cultivation areas.

The MONICA model, specifically tailored for chickpea and lentil, incorporates comprehensive field trial data to accurately simulate these crops. Applied across the Italian peninsula in a 1 km2 gridded format, the model provides an extensive analysis of how different climate conditions will affect crop phenology.

Our research is structured around three different 30-year simulation periods: a historical baseline (1994-2023), an intermediate future (2024-2053), and a distant future (2054-2083), each under two distinct IPCC emission scenarios (SSP1-2.6 and SSP2-4.5). This approach facilitates a thorough investigation into the influence of climate change on the growth and development of chickpea and lentil, with a special focus on the timing of flowering and maturity to deduce phenological changes.

Preliminary results reveal notable shifts in phenology, with significant implications for the timing of flowering and maturity, thereby affecting overall crop cycles. Subsequently, the study delves into adaptive strategies by assessing various factors, including yield, yield quality, yield stability, economic impact, water use efficiency, and soil fertility, with an emphasis on nitrogen levels.

The study evaluates four distinct crop rotation strategies:

  • Benchmark: A conventional Italian 4-year rotation comprising legume, wheat, maize, and barley.

  • Autumn Shift: The Benchmark rotation, but with chickpea and lentil sown in autumn.

  • Sustainable: Replacing maize in the Benchmark rotation with a cover crop (clover), resulting in a legume, wheat, clover, and barley sequence.

  • Sustainable Autumn Shift: The Sustainable rotation with autumn sowing for chickpea and lentil.

These strategies are scrutinized under the different climate scenarios to assess their effectiveness in adapting to the anticipated phenological changes. Early findings indicate that altering sowing dates and modifying crop rotations can markedly affect yield, yield stability, and the overall sustainability of agriculture. Specifically, crops sown in autumn, especially within the sustainable rotations, demonstrate potential in adapting to the expected shifts in phenology, poten- tially yielding more stable crops and environmental advantages.

Our research aims to furnish Italian farmers with practical insights, assisting them in adapting sowing dates and management practices to uphold sustainable legume production amidst climatic shifts. Beyond its immediate application, this research offers a framework that could be applied to other regions and crops, thereby enhancing our understanding of agricultural adaptation to climate change.

How to cite: Triacca, A., Nerucci, G., Nendel, C., Carlesi, S., Leoni, F., and Moonen, A.-C.: Adapting Italian Agriculture to Climate Change: A MONICA Model Analysis of Chickpea and Lentil Phenology Shifts , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18553, https://doi.org/10.5194/egusphere-egu24-18553, 2024.

EGU24-18867 | Orals | CL2.7

Modelling phenology in European beech forests as waves of photo-thermal responses 

Sofia Bajocco and Simone Bregaglio

Plant phenology, which refers to the timing of cyclic or recurring eco-physiological events in plants, provides key information about the seasonal dynamics of vegetation and ecosystem processes. While traditional phenological surveys imply the visual detection of easily observable events like flowering, bud break and defoliation, phenological patterns may be unclear due to combined effects or compensatory processes of driving variables (e.g., temperature and photoperiod). Monitoring the continuous plant development during a season is essential for interpreting temporal changes between observed phenological phases and the environmental impacts on the plants' seasonal dynamic. This is especially true for deciduous broadleaf forests, like European beech, where the canopy is sensitive to intra-annual climatic changes and extreme events like spring frosts. In this view, remotely sensed vegetation indices (VIs) observations, thanks to their high temporal resolution, provide a reference data source for investigating phenological moments (phenometrics) and trends. However, there are still two major drawbacks to be solved: (i) phenometrics are merely mathematical moments of the VI annual curve and do not represent any ecophysiological phase, (ii) the VI annual profile allows to detect the canopy growth processes of a plant community but does not reveal the dormancy-related processes occurring when the dominant vegetation cover is senescing. To fill this research gap, this work proposes a process-based model, named swell (simulated waves of energy light and life), able to simulate the complete VI intra-annual profile of beech forests based on their photo-thermal responses during the dormancy and the growing season. To this aim, the EU-forest dataset was used as spatial information of the European beech forests (data from 16 ecoregions), the MODIS NDVI (2010-2023) as reference data for swell calibration (4426 pixels) and independent evaluation (6672 pixels), and the E-OBS Copernicus dataset as weather input source. The rationale of swell is that each phenophase starts upon the completion of the previous one and progresses as a function of phenophase-specific photothermal requirements, using temperature and daylength as climatic cues. The swell simulations agreed with MODIS NDVI profiles (RMSE < 0.10, PBIAS < 5%, Pearson r > 0.8) across time and ecoregions, obtaining similar performances in calibration and evaluation and comparable performances with a fine-fitting statistical method fitted yearly (i.e., Elmore). Aggregating NDVI simulations by latitude and elevation bands allowed exploring patterns of beech phenology across Europe, whose dynamics can be inspected to reveal the vegetation response of this species in response to largely variable photothermal conditions.

How to cite: Bajocco, S. and Bregaglio, S.: Modelling phenology in European beech forests as waves of photo-thermal responses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18867, https://doi.org/10.5194/egusphere-egu24-18867, 2024.

EGU24-18968 | ECS | Posters on site | CL2.7

Climate change-induced shifts in leaf phenology of trees: past and future trends 

Michael Meier

Forests and atmosphere interact, for example when trees assimilate and respire CO2 during photosynthesis. Depending on their productivity and net assimilation, forests may function as a carbon sink or source. Further, the amounts of synthesized sugars assigned to growth, reproduction, and defense affect the fitness of the trees and eventually the distribution of species. Climate strongly impacts such forest-atmosphere interactions, which affect forests and in turn feed back to the climate.

For deciduous trees, the beginning and end of the photosynthetically active pe­riod (i.e., the ‘growing season’) relate to spring and autumn leaf phe­nology (i.e., leaf unfolding and leaf senescence), respectively. The climatic conditions during the growing season (i.e., the ‘bioclimate’) are directly and indirectly influenced by climate change, as climate change alters the timing and length of the growing season through shifts in leaf unfolding and leaf senescence. While past changes in leaf unfolding and leaf senescence can be analyzed by in-situ observations, the underlying drivers and particularly possible future changes are often studied with pro­cess-oriented models. However, these models may suffer from a bias to­wards the mean (BTM), which causes the simulated values to be closer to the average than the observations and could result in overly flat simulated trends.

Here I discuss (1) changes in the growing season and bioclimate in Switzerland during recent decades, (2) impacts of the calibration approach on the performance of 21 leaf se­nescence models tested with observations from Central Europe, and (3) effects of the BTM in these models on their performance and projections. Growing seasons have predominately lengthened at elevation-specific rates, which was primarily caused by changes in leaf senescence and increased the number of days with a negative atmospheric water balance at low elevations. Calibrations with the Gen­eralized Simulated Annealing algorithm and with systematically balanced or stratified samples yielded the best performing leaf senescence models, while their performance was most influenced by their structure. The BTM caused the performance of current leaf senescence models to be only slightly better than the performance of a null model that constantly simulates the average of the calibration sample. Standard model comparisons favored models with stronger BTM, while models with weaker BTM projected smaller backward shifts in future leaf senescence. The latter is counter-intuitive, since smaller shifts result from flatter trends and are therefore associated with stronger rather than weaker BTM.

I conclude that (1) the effects of phenological changes on the bioclimate should be considered when studying past and future forest productivity and species composition, (2) inference from process-oriented models to the underlying processes and drivers of leaf senescence is valid, and (3) current leaf senescence projections are highly uncertain and thus unreliable. While it is likely that current projections of future biosphere behavior under global change are distorted by erroneous state-of-the-art leaf senescence models, there is ample need and potential for the development of more accurate process-oriented models.

How to cite: Meier, M.: Climate change-induced shifts in leaf phenology of trees: past and future trends, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18968, https://doi.org/10.5194/egusphere-egu24-18968, 2024.

EGU24-19657 | Posters on site | CL2.7

Land surface phenology across major natural vegetation land cover types and biogeographical regions in the Iberian Peninsula 

Jose A. Caparros-Santiago, Miguel A. Garcia-Perez, and Victor Rodriguez-Galiano

Land surface phenology (LSP), the study of seasonal dynamics on the vegetated land surface from satellite data, has contributed to improve the understanding of the phenological dynamics of vegetation in boreal and temperate ecosystems located in the high and mid-latitude regions of the Northern Hemisphere. Iberian Peninsula is one of the most biologically rich regions of the European continent, where endemic plant species are very common. Hence, the ecosystems of the Iberian Peninsula provide a wide variety of ecosystem services, which may be altered by changes in climatic conditions. LSP has not been studied in detail in the Iberian ecosystems. Despite their ecological importance and vulnerability to climate change, there is a lack of an exhaustive and long-term characterisation of the phenological patterns of the main natural vegetation land cover types of the whole Iberian Peninsula. Therefore, the goal of this study was to monitor the LSP dynamics across major natural vegetation land cover types in the Alpine, Atlantic, and Mediterranean biogeographical regions of the Iberian Peninsula. Two-band Enhanced Vegetation Index (EVI2) time-series were generated from the MOD09Q1 surface reflectance product from January 2001 to December 2021. This MODIS product is based on 8-day image composites at a spatial resolution of 250 meters. The methodology to estimate LSP from raw EVI2 time-series followed two steps, including a) data denoising and b) the extraction of spring and autumn phenometrics. A double logistic function was used to smooth the EVI2 time-series from TIMESAT software. Start of the growing season (SOS) (i.e., proxy of the spring phenology) and the end of the growing season (EOS) (i.e., proxy of the autumn phenology) were extracted using a 10% threshold-based technique.

Results of this research showed spring and autumn phenometrics had a similar spatial pattern across major natural vegetation land cover types of the three biogeographic regions of the Iberian Peninsula. Generally, SOS dates were in March-April, while EOS dates were in November-December. Despite this, the spatial patterns of LSP were very different in Mediterranean shrublands, savannahs and grasslands. SOS and EOS dates showed the highest variability in these natural vegetation land cover types. The growing season generally started between October and February (SOS) and ended between June and November (EOS). The spatial variability of spring and autumn phenometrics in these three natural vegetation cover types may be related to several factors: i) the mixture of the phenological cycles of different functional vegetation types (e.g., herbaceous, shrub or tree vegetation); ii) the mixture of phenological trajectories of multiple plant species; iii) the influence of non-vegetation cover, such as bare soil, affecting spectral information. These LSP patterns of natural vegetation cover types in the Iberian Peninsula could contribute to improve the understanding of the response of Iberian ecosystems to climate change.

How to cite: Caparros-Santiago, J. A., Garcia-Perez, M. A., and Rodriguez-Galiano, V.: Land surface phenology across major natural vegetation land cover types and biogeographical regions in the Iberian Peninsula, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19657, https://doi.org/10.5194/egusphere-egu24-19657, 2024.

EGU24-22513 | Posters on site | CL2.7

Towards a global, remotely sensed monitoring of lake phytoplankton phenology 

Jelle Lever, Stefan Simis, Xiaohan Liu, Luis J. Gilarranz, Petra D’Odorico, Christian Ginzler, Achilleas Psomas, Alexander Damm, Arthur Gessler, Yann Vitasse, and Daniel Odermatt

Changing environmental conditions caused by climate change, eutrophication, and other anthropogenic factors affect the timing, duration, and surface extent of lake algae blooms across the globe. It remains, however, challenging to quantify the relative impacts of different environmental changes on the timing and characteristics of lake algae blooms, and to detect phenological trends over time, as these blooms vary considerably from year to year. Global data sets that may allow us to study algae-bloom properties along a wide range of environmental conditions and years are needed to address these challenges.

For this study, we developed such a data set using satellite remote sensing. We analyze the phytoplankton phenology of 2025 lakes across a wide range of climate zones over a period of approximately 20 years. More specifically, we used daily lake chlorophyll estimates derived from MERIS and OLCI data to extract phenology metrics (e.g. the onset and decline of peaks in chlorophyll concentration) for individual pixels within each of the 2025 lakes. Through a newly developed method, we determined the timing of blooms, i.e. clusters of peaks in different pixels occurring within the same lake during the same period of the year, and, subsequently, studied the change in the timing, duration, and size of those blooms across years.

This will, ultimately, help us to get a better overview of the extent to which lake algae blooms have changed across the globe, to attribute those changes to anthropogenic drivers, and to develop effective environmental policies to combat those changes where needed.

How to cite: Lever, J., Simis, S., Liu, X., Gilarranz, L. J., D’Odorico, P., Ginzler, C., Psomas, A., Damm, A., Gessler, A., Vitasse, Y., and Odermatt, D.: Towards a global, remotely sensed monitoring of lake phytoplankton phenology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22513, https://doi.org/10.5194/egusphere-egu24-22513, 2024.

Trees inhabiting seasonal climates organize their life cycle activities following an internal program termed phenology. The rising temperature through global warming has substantially influenced the timing of these phenological events, most prominently studied through the advancement of leaf emergence. Moreover, changes in precipitation patterns have led to severe drought events that have increased in both intensity and frequency worldwide. Both trends necessitate trees to adjust and synchronize their annual cycle within the ‘window of opportunity’ presenting itself based on favourable temperature and available soil moisture. Depending on when critical water limitations occur, tree species are affected at different developmental stages throughout their seasonal cycle. Thus, the severity of impact at a given stage and/or the flexibility to shift developmental and growth activities determine whether the same stressor results in mortality or minor growth reductions.

We used over 1000 saplings of six North American tree species (Sequoia sempervirens, Pinus contorta, Quercus garryana, Betula papyrifera, Prunus virginiata, and Acer macrophyllum) to investigate how flexibly (or conservatively) trees re-arrange (or stick to) their phenological sequence and growth activities when impacted by a) drought or b) defoliation events. Both treatments were applied separately at three different times (after leaf emergence, at the summer solstice, and in August) on different batches of saplings. The saplings were grown in a Polytunnel in Vancouver, BC, Canada without water limitations (except for the periodic drought treatments) and were equipped with magnetic dendrometers to monitor radial growth along with observations of bud development and shoot elongation. After harvest, we assessed total root and shoot biomass. In addition, through an image analysis of micro stem slices (utilizing a microtome), we were able to review the xylem properties (e.g., the number of cells produced, vessel size) of treated and control saplings.

Our findings reveal how artificial downregulation of source and sink activities at different points in the growing season impacts the performance of radial and apical meristems. Furthermore, we identify the potential of temperate tree species to cope with environmental stressors by optimally utilizing the available ‘time window of opportunity’—for instance, by shifting or splitting their phenological development and growth activity around a drought period. Finally, we discuss how these characteristics correlate with a species’ strategy and the level of bud determinism, i.e., whether shoots continue to grow later in the season (neo-growth atop pre-formed tissue).

How to cite: Baumgarten, F. and Wolkovich, E.: Phenological plasticity: shifting growth and developmental phases of North American tree species in response to environmental stressors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22525, https://doi.org/10.5194/egusphere-egu24-22525, 2024.

Extratropical cyclone (EC) is a main source of precipitation at midlatitudes, but its contribution to the Antarctic surface mass balance (SMB) still remains uncertain. Based on five global climate model simulations, we propose that it probably exists a tipping point of the SMB during the evolution of the Antarctic Ice Sheet (AIS), and EC greatly contributes to the tipping point. Before the tipping point, decreasing elevation of the AIS and warming sea surface temperature promote southward movement of ECs, leading to increased precipitation and inhibiting the AIS melting. However, EC becomes a negative contribution to SMB due to increased AIS surface temperature, runoff and rainfall. This study highlights that EC contributes to the tipping point of the AIS evolution.

How to cite: Xu, D. and Lin, Y.: A tipping point in the contribution of extratropical cyclones to Antarctic surface mass balance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-234, https://doi.org/10.5194/egusphere-egu24-234, 2024.

EGU24-788 | ECS | Posters on site | AS1.13

Characterization of cirrus clouds in the arctic depending on ambient conditions 

Georgios Dekoutsidis, Silke Groß, Martin Wirth, Christian Rolf, Andreas Schäfler, and Florian Ewald

The increase of the average global temperature of the Earth’s atmosphere has been measured with various methods dating back to the 19th century. In the past few decades scientists have shown that the arctic regions are warming even faster than the global average. This phenomenon has been labeled Arctic Amplification. Cirrus clouds are a potential contributor to this phenomenon. They reflect only a small part of the incoming solar radiation and can absorb and reemit earth’s long-wave radiation, thus potentially having a warming effect. Warm Air Intrusion (WAI) events transport warm, water-vapor- and aerosol-rich airmasses from the mid-latitudes into the arctic and can also contribute to arctic amplification. On the one hand the transported airmasses are already warm and contain significant amounts of water vapor which is a strong greenhouse gas. On the other hand, the cirrus clouds that form during such an event might have different and potentially stronger effects on the radiation budget of the atmosphere. Since it has also been shown that WAI events in the arctic are becoming more frequent or long-lasting, it is important to study the effects these events have on the macrophysical and optical properties of cirrus clouds in the arctic.

The HALO-(AC)3 field campaign took place in March and April of 2022. One of the central goals of the campaign was to study WAI events in the arctic regions of the Northern Hemisphere. Among others, the German research aircraft HALO was used to perform remote sensing measurements. In this study we use data collected during this campaign by the combined water vapor differential absorption and high spectral resolution lidar system WALES and the HAMP cloud radar. We selected two research flights: RF03, performed during an active warm air intrusion event (WAI case) and RF17, performed during undisturbed arctic conditions (AC case). For these flights we calculated the relative humidity over ice (RHi) and the backwards trajectories using the Lagrangian analysis tool LAGRANTO and the CLaMS-Ice model, which combines the Chemical Lagrangian Model of the Stratosphere (CLaMS) with two-moment ice microphysics. Our aim is to provide an in-depth analysis of the two types of cirrus clouds and find potential differences between them.

The clouds of the WAI case had a greater mean geometrical and optical depth as well as a slightly higher linear depolarization ratio, as measured by WALES. The distributions of RHi for the WAI case had its maximum slightly over saturation and a small negative skewness, while the AC case had its maximum at saturation with a bigger negative skewness. The supersaturations within and at close proximity to the WAI clouds reached high values over 127% more frequently than for the AC case. Surprisingly, the backwards trajectories revealed that the AC case had a significant part being of liquid origin and formed via heterogeneous nucleation, whilst the WAI case was predominantly of in-situ origin with homogeneous nucleation being the dominant process.

How to cite: Dekoutsidis, G., Groß, S., Wirth, M., Rolf, C., Schäfler, A., and Ewald, F.: Characterization of cirrus clouds in the arctic depending on ambient conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-788, https://doi.org/10.5194/egusphere-egu24-788, 2024.

EGU24-914 | ECS | Posters on site | AS1.13

Intense precipitation events during polar winter over the Academic Vernadsky station: clouds, precipitation and temperature extremes 

Anastasiia Chyhareva, Svitlana Krakovska, Irina Gorodetskaya, and Liudmyla Palamarchuk

West Antarctica and the Antarctic Peninsula are considered to be climate tipping point regions where climate change processes can cause irreversible impacts. The Antarctic Peninsula region has a unique ecosystem, which can be harmfully affected by these changes. In the past decades have from Pacific mid-latitudes and specifically atmospheric rivers, accompanied by mixed-phase clouds and precipitation, can lead to surface melt on both sides of the Antarctic Peninsula.

This study focused on intense precipitation events during the winter in the Southern Hemisphere in 2022 in the Antarctic Peninsula observed during the Year of Polar Prediction targeted observing periods. Polar WRF (v. 4.5) simulation data with grid step 1km and temporal resolution 10 minutes were analysed for the region of Academic Vernadsky station, Antarctic Peninsula mountains and former glacier Larsen B bay.

Distributions of clouds and precipitation were analysed, as well as their concentrations and phases in the cross-section of the mountains. Also, temperature profiles were examined in the cross-sections, specifically for the 2km profile.

According to the simulations data, based on Thompson’s microphysical scheme found that mixed phased and liquid clouds and precipitation could occur up to 3km even in August, which is climatically the coldest month over the coastal areas and mountains. Maximum concentrations of ice crystals and liquid droplets could exceed 1g/kg. After the intense precipitation that occur on the western Antarctic Peninsula slopes, strong warming up to 6°C in a 2km layer is simulated for the eastern slopes of AP (Larsen B ice shelf embayment).

Simulation results were compared with radiosounding data and instrumental measurements at the Akademic Vernadsky station. According to the radiosounding that were held during all events, Polar WRF underestimated the temperature in the lower troposphere (up to around 950hPa), which can impact the surface precipitation phase and temperature simulations. However, as far as Polar WRF simulations for wind speed, direction, temperature, and vertical movements are correlated with radiosounding data, we can assume that the distribution of considered microphysical and thermodynamical characteristics gained from Polar WRF simulations are trustable.  

How to cite: Chyhareva, A., Krakovska, S., Gorodetskaya, I., and Palamarchuk, L.: Intense precipitation events during polar winter over the Academic Vernadsky station: clouds, precipitation and temperature extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-914, https://doi.org/10.5194/egusphere-egu24-914, 2024.

EGU24-1678 | ECS | Posters on site | AS1.13

Shortwave cloud warming effect observed over Greenland 

Haotian Zhang, Chuanfeng Zhao, Annan Chen, Xin Zhao, and Yue Zhou

Clouds play a pivotal role in regulating the Earth's energy budget, primarily by exerting a global net cooling effect through the competing effects of shortwave radiation shading and longwave radiation trapping. However, here we report a shortwave warming effect by clouds over Greenland, contrary to the conventional belief of a cooling effect. Utilizing satellite observations from the Greenland region during the summers from 2013 to 2022, we identify a positive shortwave cloud radiative forcing when the ratio of surface albedo to top-of-atmosphere (TOA) reflectivity surpasses 1.42, implying that cloud induced warming can occur in any place when the surface is bright enough compared with TOA. Moreover, we find that the shortwave cloud warming effect on the Earth-atmosphere system is particularly prominent for optically thin clouds. These findings are crucial for understanding the radiation budget over polar regions and improving the prediction of polar ice melting.

How to cite: Zhang, H., Zhao, C., Chen, A., Zhao, X., and Zhou, Y.: Shortwave cloud warming effect observed over Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1678, https://doi.org/10.5194/egusphere-egu24-1678, 2024.

EGU24-1691 | ECS | Posters on site | AS1.13

The vertical structure of atmospheric rivers in Antarctica in the present-day and future 

Marlen Kolbe, Richard Bintanja, Eveline C. van der Linden, and Raul R. Cordero

Recent extremes in Antarctic temperature, surface melt and sea ice loss have been robustly linked to the occurrence of atmospheric rivers (ARs). However, the precise mechanisms that generate variations in the surface impacts of ARs are poorly understood, especially in the Antarctic region. Based on Arctic evidence that the vertical and horizontal advancement of ARs over sea ice strongly depends on the sea ice-preceding surface type, the season, as well as meteorological conditions, we investigate the vertical structure and propagation of extreme ARs reaching sea ice and the Antarctic ice sheet, and further quantify the associated surface impacts. We further link the wind speed and surface vertical structure and proximity of ARs to variations in turbulent mixing and radiative fluxes, which ultimately determine the impact on the surface and subsequent AR pathway. While previous studies have mostly detected ARs based on  observations and reanalyses, we additionally assess AR characteristics based on 6 CMIP6 models under present-day and future conditions (SSP5-8.5) to robustly study their propagation and impacts when reaching Antarctic sea ice and the ice sheet. 

How to cite: Kolbe, M., Bintanja, R., van der Linden, E. C., and Cordero, R. R.: The vertical structure of atmospheric rivers in Antarctica in the present-day and future, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1691, https://doi.org/10.5194/egusphere-egu24-1691, 2024.

EGU24-3671 | ECS | Orals | AS1.13 | Highlight

Antarctic Atmospheric Rivers in Present and Future Climates 

Michelle Maclennan, Andrew Winters, Christine Shields, Léonard Barthelemy, Rudradutt Thaker, and Jonathan Wille

Atmospheric rivers (ARs) are long, narrow bands of moisture that propagate poleward from the midlatitudes and occasionally reach the Antarctic Ice Sheet. Despite occurring only ~1% of the time, Antarctic ARs contribute 10% of the annual precipitation and are major drivers for heatwaves, foehn events, and surface melting on ice shelves. While snowfall is currently the dominant impact of ARs over the grounded Antarctic Ice Sheet, the relative contribution of ARs to snowfall, rainfall, and surface melt may change in a warming climate, along with the frequency and intensity of AR events themselves. Here, we use the Community Earth System Model version 2 (CESM2) Large Ensemble to detect ARs during the current period (1980–2014) and future climate (2015–2100) under the SSP370 radiative forcing scenario. We use an AR detection threshold for the current period based on the 98th percentile of the meridional component of integrated vapor transport (vIVT). To account for projected future increases in atmospheric moisture content (Clausius-Clapeyron effect) and its impacts on vIVT, we scale our AR detection threshold for the future period by the relative change in integrated water vapor compared to the present-day climatology. We then describe how the frequency, intensity, and year-to-year variability in Antarctic ARs changes by the end of the 21st century by region, with links to changes in the large-scale atmospheric circulation accompanying ARs. Finally, we quantify AR-attributed precipitation, precipitation variability, and trends in the future climate, ultimately providing an early assessment of future AR-driven changes to Antarctic surface mass balance.

How to cite: Maclennan, M., Winters, A., Shields, C., Barthelemy, L., Thaker, R., and Wille, J.: Antarctic Atmospheric Rivers in Present and Future Climates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3671, https://doi.org/10.5194/egusphere-egu24-3671, 2024.

EGU24-4327 | ECS | Orals | AS1.13 | Highlight

Ground-based Remote Sensing of Aerosol, Clouds, Dynamics, and Precipitation in Antarctica - First results from a one-year campaign at Neumayer Station III in 2023 

Martin Radenz, Ronny Engelmann, Silvia Henning, Holger Schmithüsen, Holger Baars, Markus M. Frey, Rolf Weller, Johannes Bühl, Cristofer Jimenez, Johanna Roschke, Lukas Muser, Nellie Wullenweber, Sebastian Zeppenfeld, Hannes Griesche, Ulla Wandinger, and Patric Seifert

Novel ground-based remote sensing observations of aerosols and clouds have been carried out in Antarctica at the German Neumayer Station III (70.67°S, 8.27°W) for a whole year. The deployment of the mobile exploratory platform OCEANET-Atmosphere brought full ACTRIS aerosol and cloud profiling capabilities next to meteorological, radiation, and air chemistry in-situ observations at the Antarctic station. Neumayer III is currently the only station on a floating ice shelf that is manned throughout the year, providing excellent conditions for studying atmospheric effects on the Antarctic ice shelf.

For that deployment the standard instrumentation of OCEANET-Atmosphere (PollyXT Raman polarization Lidar, a HATPRO microwave Radiometer, a Cimel sun and lunar photometer, and Radiation sensors) was extended by a Mira-35 cloud radar, a scanning LITRA-S Doppler lidar and a Parsivel² optical disdrometer. Together, these instruments brought the full ACTRIS aerosol and cloud profiling capabilities to a region where sophisticated ground-based observations were not available. The synergy of the different instruments allows for detailed retrievals of aerosol and cloud properties, such as cloud-relevant aerosol properties, liquid droplet properties and ice crystal concentrations.

While data analysis is ongoing, three scientific highlights have already been identified during austral fall and winter, namely:

  • Observations of a persistent shallow mixed-phase cloud embedded in a plume of advected marine aerosol. State of the art microphysical retrievals are used to obtain aerosol and cloud microphysical properties. Closure between cloud-relevant aerosol particles and precipitating ice crystals was achieved, demonstrating that the cloud formed in an aerosol-limited environment.
  • Two extraordinary warm air intrusions: One with intense snowfall produced the equivalent of 10% of the yearly snow accumulation, a second one with record high temperatures and heavy icing due to supercooled drizzle.
  • Omnipresent aerosol layers in the stratosphere, contributing almost 50% to the aerosol optical depth of around 0.06 at 500nm. Lidar-derived optical signatures revealed sulphate aerosol in the stratosphere - most likely linked to the Hunga Tonga eruption in 2022.

We will present an overview of the campaign, the three highlights and provide an outlook on potential future usage of the dataset.

How to cite: Radenz, M., Engelmann, R., Henning, S., Schmithüsen, H., Baars, H., Frey, M. M., Weller, R., Bühl, J., Jimenez, C., Roschke, J., Muser, L., Wullenweber, N., Zeppenfeld, S., Griesche, H., Wandinger, U., and Seifert, P.: Ground-based Remote Sensing of Aerosol, Clouds, Dynamics, and Precipitation in Antarctica - First results from a one-year campaign at Neumayer Station III in 2023, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4327, https://doi.org/10.5194/egusphere-egu24-4327, 2024.

EGU24-4752 | ECS | Orals | AS1.13

Open Water in Sea Ice Causes High Bias in Polar Low-Level Clouds in GFDL CM4 

Xia Li, Zhihong Tan, Youtong Zheng, Mitchell Bushuk, and Leo Donner

Global climate models (GCMs) struggle to simulate polar clouds, especially low-level clouds that contain supercooled liquid and closely interact with both the underlying surface and large-scale atmosphere. Here we focus on GFDL's latest coupled GCM–CM4–and find that polar low-level clouds are biased high compared to observations. The CM4 bias is largely due to moisture fluxes that occur within partially ice-covered grid cells, which enhance low cloud formation in non-summer seasons. In simulations where these fluxes are suppressed, it is found that open water with an areal fraction less than 5% dominates the formation of low-level clouds and contributes to more than 50% of the total low-level cloud response to open water within sea ice. These findings emphasize the importance of accurately modeling open water processes (e.g., sea ice lead-atmosphere interactions) in the polar regions in GCMs.

How to cite: Li, X., Tan, Z., Zheng, Y., Bushuk, M., and Donner, L.: Open Water in Sea Ice Causes High Bias in Polar Low-Level Clouds in GFDL CM4, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4752, https://doi.org/10.5194/egusphere-egu24-4752, 2024.

EGU24-5220 | ECS | Posters on site | AS1.13

Clouds and precipitation in the initial phase of marine cold air outbreaks as observed by airborne remote sensing 

Imke Schirmacher, Sabrina Schnitt, Marcus Klingebiel, Nina Maherndl, Benjamin Kirbus, and Susanne Crewell

During Arctic marine cold air outbreaks (MCAOs), cold and dry air flows from the central Arctic southward over the open ocean. There, cloud streets form that transform to cellular convection downstream under extreme surface heat fluxes. MCAOs strongly affect the Arctic water cycle through large-scale air mass transformations and can lead to extreme weather conditions at mid-latitudes. The description of air mass transformations is still challenging partly because previous observations do not resolve fine scales and lack information about cloud microphysical properties. Therefore, we focus on the crucial initial phase of development within the first 170 km over open water of two MCAO events with different strengths observed during the HALO-(AC)3campaign. Both times the POLAR 5 and 6 aircraft flew several legs along the same track perpendicular to the cloud streets crossing the sea ice edge several times to allow a quasi-Lagrangian perspective. Based on high-resolution remote sensing and in-situ measurements, the development of the boundary layer, formation of clouds, onset of precipitation, and riming are studied. We establish a novel approach based on radar reflectivity measurements only to detect roll circulation that forms cloud streets.

For the event with the stonger contrast between surface and 850 hPa potential temperature (MCAO index), cloud tops are higher, more liquid-topped clouds exist, the liquid layer at cloud top is wider, and the liquid water path, mean radar reflectivity, amount of rime mass, precipitation rate and occurrence are larger compared to the weaker event. However, the width of the roll circulation is similar for both MCAO events. All parameters, moreover, evolve with distance over open water, as the boundary layer deepens and cloud top heights rise. Cloud streets form after traveling 15 km over open water. After 20 km, cloud cover increases to just below 100 % and after around 30 km, precipitation forms. We find that maxima in the rime mass have the same horizontal scale as the roll circulation. The presentation will highlight how cloud macro- and microphysical parameters vary with distance over open water and explain the differences between both MCAO events.

How to cite: Schirmacher, I., Schnitt, S., Klingebiel, M., Maherndl, N., Kirbus, B., and Crewell, S.: Clouds and precipitation in the initial phase of marine cold air outbreaks as observed by airborne remote sensing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5220, https://doi.org/10.5194/egusphere-egu24-5220, 2024.

EGU24-6156 | ECS | Posters on site | AS1.13

Ice crystal numbers in Arctic clouds over sea ice and ocean: satellite retrievals and cloud-resolving modelling 

Iris Papakonstantinou Presvelou and Johannes Quaas

Mixed-phase and ice clouds are prominent parts of the Arctic climate system. In particular, boundary layer clouds and their interactions with local aerosols may play an important role in the amplified warming that has been observed in the Arctic during the recent years. These aerosols which are known as ice nucleating particles (INPs) are necessary for the heterogeneous ice formation in temperatures above -38oC. Several in-situ observations have measured a high number of effective ice nucleating particles, possibly related to biological activity in the open ocean. In contrast, in our previous study analyzing the novel active remote sensing dataset DARDAR-Nice for ten years in the Arctic region (Papakonstantinou-Presvelou et al., 2022), we found an increased ice number in low-level clouds over sea ice compared to the open ocean, suggesting other possible factors that might contribute to this difference. Here we perform several sensitivity experiments with the ICON model at kilometer-scale resolution in order to investigate the effect of these factors to the ice number, namely the contribution of local INPs, blowing snow and secondary ice production.

How to cite: Papakonstantinou Presvelou, I. and Quaas, J.: Ice crystal numbers in Arctic clouds over sea ice and ocean: satellite retrievals and cloud-resolving modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6156, https://doi.org/10.5194/egusphere-egu24-6156, 2024.

EGU24-6664 | Orals | AS1.13 | Highlight

Antarctic precipitation: distributed observations during the POPE and AWACA campaigns 

Alexis Berne and Alfonso Ferrrone

Although the deployment of ground-based remote sensing instruments has made possible significant progress, Antarctic precipitation remains poorly understood, in particular away from the scientific stations where most field campaigns have taken place in the past. The PEA Orographic Precipitation Experiment (POPE) campaign took place at the Princess Elisabeth Antarctica station (Queen Maud Land, East Antarctica) during the austral summer 2019-2020. In this framework, a transect of three Doppler vertically profiling precipitation radars (MRR-PRO) was deployed from 20 to 30 km away from the station, in complete autonomy in the complex terrain of the Sor Rondane Mountains. The measurements collected during this campaign highlighted the complex interactions between the terrain and a dry layer likely due to katabatic winds, modulating the occurrence of precipitation in the area.
This POPE campaign also served as a test of the idea of deploying complex instruments dedicated to cloud and precipitation monitoring in complete autonomy to access relevant information away from stations, in areas poorly covered so far. This is a strong motivation for the AWACA project (ERC Synergy), which aims to study the atmospheric branch of the water cycle over Antarctica. AWACA started in September 2021 with the design and construction of autonomous observation platform units (4 in total) sheltering various sensors: surface meteorology, isotopic composition of water vapor and precipitation, and remote sensing of clouds and precipitation. The main deployment along a 1100-km transect between the Dumont d'Urville station at the coast and the Concordia station on the inner Plateau, is scheduled for the austral summer 2024-2025.
In this presentation, I will summarize the main results about precipitation from the POPE campaign as well as the main objectives of the AWACA project.

How to cite: Berne, A. and Ferrrone, A.: Antarctic precipitation: distributed observations during the POPE and AWACA campaigns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6664, https://doi.org/10.5194/egusphere-egu24-6664, 2024.

EGU24-8702 | ECS | Posters on site | AS1.13

Assessing the Performance of the Weather Research and Forecasting (WRF) Model in Simulating Atmospheric In-Cloud Icing Over Fagernesfjellet, Norway 

Pravin Punde, Yngve Birkelund, Muhammad Virk, and Xingbo Han

Atmospheric icing ensues when water droplets in the atmosphere freeze upon interacting with diverse objects, presenting substantial hazards to infrastructure and leading to disruptions in both road and air traffic. 

This study introduces a detailed analysis of in-cloud icing conducted specifically over Fagernesfjellet, Norway. Utilizing the Weather Research and Forecasting (WRF) model, ERA-5 data was employed for both initial and lateral boundary conditions. The simulation covers a three-month period from October 1, 2022, to December 31, 2022, with a grid spacing of 9,3,1 km.

Acknowledging the substantial influence of local terrain on icing conditions, the analysis prioritizes the highest model resolution. The determination of the icing load involves the utilization of a Makkonen ice accretion model, and the resultant values, alongside surface parameters, undergo validation against field measurements taken at Fagernesfjellet, Norway. The representation of supercooled liquid water (SLW) in numerical weather prediction (NWP) models is crucial for precise atmospheric icing forecasts. Hence, we conduct a comprehensive evaluation of the Thompson scheme's performance in simulating liquid water content (LWC) and, consequently, the icing load, along with general weather parameters associated with icing.

From our preliminary analysis, the WRF model showcases effectiveness in simulating in-cloud icing conditions. WRF adeptly reproduces crucial surface parameters such as temperature, pressure, relative humidity, wind speed, and direction. Nevertheless, there are discernible differences between the observed data and WRF results, particularly noticeable in the case of wind speed and direction.

How to cite: Punde, P., Birkelund, Y., Virk, M., and Han, X.: Assessing the Performance of the Weather Research and Forecasting (WRF) Model in Simulating Atmospheric In-Cloud Icing Over Fagernesfjellet, Norway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8702, https://doi.org/10.5194/egusphere-egu24-8702, 2024.

EGU24-9122 | Posters on site | AS1.13

Microphysical cloud properties in the initial phase of Arctic cold air outbreaks 

Marcus Klingebiel, Evelyn Jäkel, Michael Schäfer, André Ehrlich, and Manfred Wendisch

Cloud streets are a common feature of cold air outbreaks in the Arctic region. These are long, parallel bands of cumulus clouds that form perpendicular to the wind direction. They are caused by the interaction between the cold air mass and the warm ocean surface. Within the framework of (AC)³, the HALO-(AC)³ campaign was performed in spring 2022 involving several research aircraft to study cold air outbreaks and their belonging cloud streets. In this study we use a spectral imaging instrument, called AISA Hawk, to retrieve cloud microphysical properties in the very initial phase of these cloud streets and therefore focus on their development over the leads in the marginal sea ice zone. 

How to cite: Klingebiel, M., Jäkel, E., Schäfer, M., Ehrlich, A., and Wendisch, M.: Microphysical cloud properties in the initial phase of Arctic cold air outbreaks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9122, https://doi.org/10.5194/egusphere-egu24-9122, 2024.

A fundamental divide exists between previous studies which conclude that polar amplification does not occur without sea ice and studies which find that polar amplification is an inherent feature of the atmosphere independent of sea ice. We hypothesise that a representation of climatological ocean heat transport is key for simulating polar amplification in ice-free climates. To investigate this we run a suite of targeted experiments in the slab ocean aquaplanet configuration of CESM2-CAM6 with different profiles of prescribed ocean heat transport, which are invariant under CO2 quadrupling. In simulations without climatological ocean heat transport, polar amplification does not occur. In contrast, in simulations with climatological ocean heat transport, robust polar amplification occurs in all seasons. What is causing this dependence of polar amplification on ocean heat transport? Energy-balance model theory is incapable of explaining our results and in fact would predict that introducing ocean heat transport leads to less polar amplification. We instead demonstrate that shortwave cloud radiative feedbacks can explain the divergent polar climate responses simulated by CESM2-CAM6. Targeted cloud locking experiments in the zero ocean heat transport simulations are able to reproduce the polar amplification of the climatological ocean heat transport simulations, solely by prescribing high latitude cloud radiative feedbacks. We conclude that polar amplification in ice-free climates is underpinned by ocean-atmosphere coupling, through a less negative high latitude shortwave cloud radiative feedback that facilitates enhanced polar warming. In addition to reconciling previous disparities, these results have important implications for interpreting past equable climates and climate projections under high emissions scenarios.

How to cite: England, M. and Feldl, N.: Robust polar amplification in ice-free climates relies on ocean heat transport and cloud radiative effects , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9946, https://doi.org/10.5194/egusphere-egu24-9946, 2024.

EGU24-10621 | ECS | Orals | AS1.13 | Highlight

Arctic Warm and Moist Air Intrusions in ICON Simulations 

Jan Landwehrs, Sofie Tiedeck, Sonja Murto, and Annette Rinke

Warm and moist air intrusions (WAI) contribute strongly to extreme warm events in the central Arctic and deliver a major part of the moisture transport into this region, with significant impacts on cloud formation and the surface energy balance. Within the PolarRES EU-project we use the ICON model to study such events both in case studies for the MOSAiC expedition and climate simulations.

MOSAiC provided comprehensive observations of two WAIs in mid-April 2020 when near-surface air temperatures reached the melting point for the first time in this spring. We evaluate different ICON-LAM set-ups, including a pan-Arctic domain with 11km horizontal resolution, as well as more confined domains at convection-permitting 2.5km resolution with varying cloud microphysics settings. A better agreement with local observations is found on the smaller model domains at higher resolution. Additionally, the representation of liquid water is improved by using a more complex two-moment cloud microphysics scheme, where a scenario with higher CCN (cloud condensation nuclei) concentration is found to be more suitable for the aerosol-rich intrusion around April 16.

In a climatological perspective we demonstrate the tracking of moisture intrusion events in decadal-scale climate simulations with ICON-LAM at 11km resolution in a pan-Arctic domain. We drive the regional model with ERA5 and selected CMIP6 GCMs to obtain vertically integrated water vapor transport at high spatial and temporal resolution. This is then used to identify, track and classify WAIs, to study their climatological characteristics, impacts and long-term trends under climate change.

How to cite: Landwehrs, J., Tiedeck, S., Murto, S., and Rinke, A.: Arctic Warm and Moist Air Intrusions in ICON Simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10621, https://doi.org/10.5194/egusphere-egu24-10621, 2024.

EGU24-11947 | ECS | Orals | AS1.13

Boundary-layer cloud modeling challenges on the North Slope of Alaska 

Kyle Fitch, Zachary Cleveland, McKenna Stanford, and Lindsay Dedrickson

The accurate modeling and prediction of cloud base heights is critical for energy balance calculations and aviation operations, alike. Low-level (i.e., boundary-layer) Arctic clouds can be difficult to model, making prediction of formation and dissipation challenging. Primarily mixed-phase, these clouds typically contain low quantities of supercooled liquid water and often slowly precipitate relatively small amounts of moderately and heavily rimed snow particles. While this appears to be the predominant cloudy state on the North Slope of Alaska (NSA), the delicate balance of microphysical, dynamical, radiative, surface coupling, and advective processes can rapidly shift to heavy snow (with various degrees of riming) or to a complete dissipation of the cloud layer without any precipitation, depending on the dominant processes. Here we strive to disentangle these various processes. First, we compare the predictive performances of four different numerical weather models in forecasting the presence and base-heights of low-level clouds: the High-Resolution Rapid Refresh - Alaska (HRRR-AK) model, the Polar Weather Research and Forecasting (Polar WRF) model, the Unified Model (UM), and the European Centre for Medium-range Weather Forecasting (ECMWF) model.  Initial results comparing model output at two U.S. Department of Energy Atmospheric Radiation Measurement (AMT) NSA sites, during the fall season in 2019 and 2022, show that the UM slightly outperforms the HRRR-AK in terms of accurately forecasting the presence of a low-level cloud layer (89% of the time). All models have a significant bias of 300 to 800 meters in forecasting cloud base height (lower than is observed); however, the UM and ECMWF models have the lowest biases. Finally, a case study for a particularly challenging April 2017 thin-cloud event is presented, wherein we compare the performance of four different bulk microphysical parameterization schemes using a higher-resolution large eddy simulation (LES) model, the WRF-LES. Initial results show that the Thompson scheme was the only one able to reproduce and sustain a substantial supercooled liquid layer, but it was unable to reproduce the transition from a deep, liquid-rich cloud to a thin layer with moderately and heavily rimed precipitation. This is the first step in linking simulated LES-scale riming processes with those parameterized at a coarser mesoscale model scale. This has important implications for forecasting low-level clouds in an operational environment, given the efficiency of the riming process.

How to cite: Fitch, K., Cleveland, Z., Stanford, M., and Dedrickson, L.: Boundary-layer cloud modeling challenges on the North Slope of Alaska, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11947, https://doi.org/10.5194/egusphere-egu24-11947, 2024.

EGU24-13193 | Posters on site | AS1.13

Atmospheric Rivers vis-à-vis the Summer Seasonal Cycle and Regional Greenland Surface Melt 

William Neff, Christopher Cox, Mathew Shupe, and Michael Gallagher

Recent analysis [Mattingly et al., 2023] suggests that Atmospheric Rivers (ARs) in combination with planetary scale dynamics and coupled orographic processes (e.g., foehn effect), could lead to enhanced melting in northeast Greenland and could, in turn, be linked to increasing mass loss from outflow glaciers there [Khan et al., 2022]. The importance of large-scale dynamics, which is supported by other studies too (e.g., Neff et al., 2014), led us to examine more generally the patterns of summer melt over the whole of Greenland as influenced by factors such as the seasonal cycle, the frequency of ARs, and general synoptic influences.

Our AR detection method used ERA-5 reanalysis daily data at 65oN, 55oE and 850 hPa from 2000 through 2022, JJA, and for wind directions between 112.5o and 225.0o.  We carried out linear analysis correlation between integrated water vapor, IWV; tropospheric temperature, T850 hPa; tropospheric wind speed, WS 850 hPa; and melt fraction (MF) in an area over the southwest coast near where the typical AR track first encounters the ice sheet between 62-67oN and 50-47o E.  We found high correlation between high IWV and temperature; good correlation between IWV, coastal MF and T850 hPa; and  weak dependence of MF on southerly wind speed.

A consideration in quantifying the effects of ARs on total surface melt is the fact that their influence can extend over multi-day periods. The effect continues along the west coast after the warm front has passed over the ice sheet at the end of the AR life cycle when residual moist, warm air remains trapped in the downstream low along the 3-km high ice sheet, affecting surface energy budgets and where smaller less-ordered mesoscale circulations remain. In addition, because the initial northward transport occurs in concert with a strong ridge centered just east of the center of the ice sheet.  In our analysis we will show results associated with four melt areas: 1) near coastal to the west, 2) over the lower accumulation region such as in the area of the old Dye-2 radar site, 3) at the Summit of Greenland where melt is historically low but of increasing frequency of late, and 4) in the far northeast which was of interest in Mattingly et al. (2023). ARs directly affect the southwest ice sheet and their frequency can modulate MF near the shoulder seasons. Secondary effects along the east coast as the ridge passes, which may include subsidence (Mattingly et al. 2023), are weak but detectable. The frequency of ARs is less influential in the southwest in mid-summer when mean temperatures are warmer throughout the region. Melting in the northeast is only weakly related to ARs and generally follows to the seasonal cycle of warming.

 

Neff, W., et al. (2014, JGR, doi:10.1002/2014JD021470).

Khan, S. A., et al. (2022), E, Nature, doi:10.1038/s41586-022-05301-z.

Mattingly, K. S.,  et al.(2023), , Nature Communications, 14(1), 1743, doi:10.1038/s41467-023-37434-8.

How to cite: Neff, W., Cox, C., Shupe, M., and Gallagher, M.: Atmospheric Rivers vis-à-vis the Summer Seasonal Cycle and Regional Greenland Surface Melt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13193, https://doi.org/10.5194/egusphere-egu24-13193, 2024.

EGU24-13345 | ECS | Posters on site | AS1.13 | Highlight

Precipitation in the Arctic and Southern Ocean: new insights from aircraft and ship-borne measurements 

Larry Ger Aragon, Yi Huang, Peter May, Jonathan Crosier, Paul Connolly, Estefania Montoya Duque, and Keith Bower

Precipitation is an important component of the hydrologic cycle and sea ice mass balance in polar regions. However, precipitation products in high latitudes constitute the highest uncertainties among satellite retrievals and numerical models. These uncertainties arise from limited in-situ observations of high-latitude precipitation and the fundamental differences between the Arctic and Southern Ocean/Antarctic environments that complicate the key precipitation properties and associated processes. To help address this knowledge gap, this study uses recent aircraft and ship-borne measurements to understand better the microphysical properties of precipitation over the Arctic and Southern Ocean/Antarctic regions. For the Arctic case, select summertime precipitation events are examined using aircraft measurements from precipitation imaging probes. We present the microphysical properties of Arctic precipitation in terms of the dominant ice precipitation type, particle size distributions, and important bulk properties. For the Southern Ocean/Antarctic case, we use recent measurements from ship-borne disdrometer and dual-polarimetric radar and present the distinctive polarimetric signatures and surface precipitation properties of seven synoptic types across the Southern Ocean. We also demonstrate an improved radar rainfall retrieval algorithm for the region, considering the dominance of small raindrop sizes of less than one millimeter in Southern Ocean rainfall. This research is leading toward more accurate, high-resolution estimates of precipitation properties in high-latitude regions, crucial in advancing the understanding of a range of climatological and meteorological processes as well as in evaluations of weather and climate models.

How to cite: Aragon, L. G., Huang, Y., May, P., Crosier, J., Connolly, P., Montoya Duque, E., and Bower, K.: Precipitation in the Arctic and Southern Ocean: new insights from aircraft and ship-borne measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13345, https://doi.org/10.5194/egusphere-egu24-13345, 2024.

EGU24-14866 | Orals | AS1.13

Coordinated observations of the water cycle of marine cold-air outbreaks in the European Arctic during the ISLAS 2022 field campaign 

Harald Sodemann, Iris Thurnherr, Andrew Seidl, Alena Dekhtyareva, Aina Johannessen, Marvin Kähnert, Mari B. Steinslid, Sander Løklingholm, Lars R. Hole, Paul Voss, Lukas Papritz, Marina Dütsch, Robert O. David, Tim Carlsen, David M. Chandler, Patrick Chazette, Julien Totems, Alfons Schwarzenboeck, Franziska Hellmuth, and Julien Delanoe and the ISLAS2022 Team

Marine cold-air outbreaks (mCAOs) are a characteristic type of high-impact weather in the European Arctic and are characterized by an intense water cycle where polar cloud processes play an important role. Model simulations and weather forecasts of mCAO events are challenging and associated with poor predictability. One reason is that processes related to the water cycle interact with one another on a wide range of scales. In regional models, some of these processes are resolved and others are fully or partly parameterised. To test and improve numerical weather prediction models, additional observations and novel types of measurements of water vapour are highly demanded. Stable water isotopes are an increasingly available measurement, allowing to trace sub-grid scale processes, and providing the potential to constrain the mass budget of the atmospheric water cycle during mCAO events. During the ISLAS2022 field experiment (21 March to 10 April 2022), the stable isotope composition of water vapour and liquid samples, cloud structures, and other meteorological parameters were collected between Svalbard and Northern Scandinavia on various measurement platforms. Airborne survey flights to Svalbard provided the ocean evaporation signature and subsequent processing of water vapour during mCAO conditions. During a number of flights, mCAO airmasses were repeatedly sampled over a course of hours to days, allowing to characterize their thermodynamic evolution as clouds were first forming, then glaciating and precipitating. In addition, vapour isotope and sea water isotope measurements were taken continuously onboard R/V Helmer Hanssen between Tromsø and the Greenland west coast. Finally, coordinated land-based measurement activity over Northern Norway and Sweden allowed collection of precipitation samples, thus closing the mass budget of the mCAO events. Furthermore, using buoyancy-controlled meteorological balloons launched from Ny Ålesund, we additionally obtained continuous in-situ measurements of the boundary-layer evolution during the mCAO. We provide an overview over the airborne and ground-based measurement activities during the campaign and provide several examples to highlight the potential of the stable water isotope measurements to constrain the water budget of mCAOs in conjunction with traditional meteorological observations.

How to cite: Sodemann, H., Thurnherr, I., Seidl, A., Dekhtyareva, A., Johannessen, A., Kähnert, M., Steinslid, M. B., Løklingholm, S., Hole, L. R., Voss, P., Papritz, L., Dütsch, M., David, R. O., Carlsen, T., Chandler, D. M., Chazette, P., Totems, J., Schwarzenboeck, A., Hellmuth, F., and Delanoe, J. and the ISLAS2022 Team: Coordinated observations of the water cycle of marine cold-air outbreaks in the European Arctic during the ISLAS 2022 field campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14866, https://doi.org/10.5194/egusphere-egu24-14866, 2024.

EGU24-14968 | ECS | Orals | AS1.13

Insights into cloud biases over high-latitude oceans from a cloud-controlling factor framework 

Joaquin Blanco, Rodrigo Caballero, Steven Sherwood, and Lisa Alexander

A long-standing and pervasive problem within the modelling community is the proper representation of cloud albedo over the Southern Hemisphere (SH) oceanic region. Errors persist despite the extensive evidence that these are related to the unique microphysical characteristics of the austral clouds. In this study we investigate additional causes of cloud albedo biases over the 50˚–65˚ oceanic band using CMIP6 simulations and a cloud-controlling factor (CCF) approach on daily timescales. We gain further insight by replicating our method over the equivalent oceanic region in the Northern Hemisphere (NH).

Cloud albedo, computed from upwelling and downwelling shortwave radiation at surface and top of the atmosphere, is averaged into bins of vertical velocity, surface wind, and sea-surface temperature. The performance of fifteen models in both atmospheric-only and ocean-coupled configurations is evaluated against CERES satellite retrievals in combination with ERA5 reanalysis for the 2000–2014 period.

When averaging cloud albedo by vertical velocity bins, we find that shallow boundary-layer (deep convective) clouds are consistently underpredicted (overpredicted) over the high-latitude oceans of the SH. We repeat the method for the 50˚–65˚ band in the North Atlantic and Pacific oceans and find that similar compensating errors exist.

Another important result is that the SH cloud biases occur for sea-surface temperatures below 4°C. We show that a connection exists between this empirical finding and the biases as determined from microphysical effects, i.e.: a deficit of cloud albedo is due to models producing glaciated rather than supercooled liquid water clouds. Our CCF method allow us to see that in such cases, models tend to simulate NH clouds for the SH.

We also find that the positive sign of the cloud albedo hemispheric asymmetry (SH-NH difference over the 50°–65° band) is consistently predicted by nearly all models, many of which also predict a similar magnitude to observations. However, this is a consequence of compensating errors as individually most models tend to either overpredict or underpredict cloud albedo in both hemispheres.

How to cite: Blanco, J., Caballero, R., Sherwood, S., and Alexander, L.: Insights into cloud biases over high-latitude oceans from a cloud-controlling factor framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14968, https://doi.org/10.5194/egusphere-egu24-14968, 2024.

Cold air outbreaks (CAOs) are a key component of the Arctic climate system, featuring intense convective cloud fields embedded in cold, dry air masses over relatively warm surfaces. Large-Eddy Simulation (LES) is a technique often used to investigate CAOs at high spatial and temporal resolutions, resolving the intricate processes involved and providing a wealth of virtual data. A complication with LES studies of CAOs is the typical absence of suitable observational data to fully constrain the simulations, and thus anchor them in reality. This study aims to use observational data from the recent airborn HALO-(AC)³ campaign in the Atlantic sector of the Arctic to drive LES experiments exclusively with observations. To this purpose data from Research Flights 10 and 11 are used, which probed a weak CAO in the Fram Strait on 29 and 30 March 2022. A Lagrangian model framework is adopted, making use of observations along the two-day low-level trajectory that stretched from close to the North Pole to the sea-ice free area Southwest of Svalbard. HALO observations are integrated into the reanalysis-based model forcing in an incremental way, yielding a suite of forcing datasets. These observational data consist of vertical soundings of thermodynamic state, pressure gradients, mesoscale divergence and advective tendencies, as
well as surface properties to act as boundary conditions. The LES code incorporates advanced representations for mixed-phase microphysical processes and radiative transfer, to allow a realistic representation of clouds and turbulence in the transforming low-level airmass. LES results obtained with
this setup are evaluated against independent HALO datasets on clouds and other boundary-layer properties. Inter-comparing the suite of LES runs with different forcing datasets elucidates the impacts of individual forcing components on the air mass transition and associated cloud evolution. 

How to cite: Paulus, F. and Neggers, R.: Studying Cloud Transformations in Cold Air Outbreaks using Large-Eddy Simulations Exclusively Driven by HALO-(AC)³ Campaign Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15625, https://doi.org/10.5194/egusphere-egu24-15625, 2024.

EGU24-16011 | ECS | Posters on site | AS1.13

Differential absorption G-band radar for Arctic clouds and water vapor observations 

Sabrina Schnitt, Mario Mech, Jens Goliasch, Davide Ori, Thomas Rose, and Susanne Crewell

The Arctic climate is changing at fast pace. The contribution of low-level clouds to Arctic amplification feedback processes remains challenging to quantify as model evaluation requires continuous, high-quality observations in a demanding environment. Advancing the understanding of governing processes in mixed-phase clouds, ubiquitous in the Arctic, calls for temporally high-resolved measurements of cloud and precipitation microphysical properties as well simultaneous quantification of water vapor amount and profiles in all-weather conditions.

We present the novel and worldwide unique G-band Radar for Water vapor profiling and Arctic Clouds (GRaWAC) system, suitable to deliver these measurements. GRaWAC is a FMCW G-band radar with Doppler-resolving capabilities and simultaneous dual-frequency operation at 167 and 175GHz. The Differential Absorption Radar technique is applied to the measurements to derive temporally continuous water vapor profiles in cloudy and precipitating conditions, which closes a current gap in observational state-of-the-art instrumentation.

We reveal first measurements from a mid-latitudinal ground site and airborne test flights to illustrate GraWAC’s potential for water vapor, cloud and precipitation profiling. Based on instrument simulations, we outline the benefits of such observations at an Arctic ground-based supersite, such as AWIPEV station, Ny-Alesund, Spitsbergen. There, the G-band radar measurements will be embedded in a synergy of remote sensing instruments, including an operational microwave radiometer and a Ka- and W-band cloud radar, respectively. We highlight future applications of these synergistic measurements, and therein especially the multi-frequency radar space, for model evaluation studies targeting an improved representation of mixed-phase clouds in the Arctic.

How to cite: Schnitt, S., Mech, M., Goliasch, J., Ori, D., Rose, T., and Crewell, S.: Differential absorption G-band radar for Arctic clouds and water vapor observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16011, https://doi.org/10.5194/egusphere-egu24-16011, 2024.

EGU24-16088 | ECS | Orals | AS1.13 | Highlight

Investigating potential sources of Ice Nucleating Particles around the Antarctic peninsula 

Floortje van den Heuvel, Mark Tarn, Benjamin Murray, and Thomas Lachlan-Cope

Clouds are a major source of uncertainty in climate model projections, especially in the Southern Ocean where the large model biases in short and long wave radiative fluxes affect the model representation of sea surface temperatures, sea ice and ultimately large scale circulation in the Southern Hemisphere. Evidence suggests that the poor representation of mixed phase clouds and the role of Ice Nucleating Particles (INPs) in these clouds are likely to be responsible for the model biases in this region. To understand how clouds will respond in a future climate we need to both better understand the effects and sources of INPs in the present, and attempt to anticipate the importance of new sources of INPs which could be revealed in a warming climate and by a reduction in glacial coverage.

In order to achieve this, we have dispersed samples of dusts from the Antarctic peninsula and James Ross Island in the Leeds aerosol chamber to characterise the size-resolved ice-nucleating activity of Southern high latitude dusts and to determine the heat lability of the INPs as a potential indicator for biogenic ice nucleators. We’ve also created suspensions from a number of Antarctic mosses and lichen to measure the ice-nucleating activity of these potential sources of INPs. Preliminary results indicate that the collected dusts nucleated ice at temperatures between -18 ºC and -14 ºC while mosses and lichen nucleated ice at temperatures ranging from -18 ºC to -6 ºC, depending on the source. Future work will include a comparison with ambient air filter samples collected around Rothera (Antarctic peninsula) and in the Arctic.

How to cite: van den Heuvel, F., Tarn, M., Murray, B., and Lachlan-Cope, T.: Investigating potential sources of Ice Nucleating Particles around the Antarctic peninsula, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16088, https://doi.org/10.5194/egusphere-egu24-16088, 2024.

EGU24-16503 | ECS | Posters on site | AS1.13

Investigating Arctic Clouds and Water Vapor over Sea Ice: Airborne Passive Microwave Observations during HALO-(AC)3 

Nils Risse, Mario Mech, Catherine Prigent, and Susanne Crewell

Clouds and water vapor play a critical role in the water and energy balance of the Arctic. However, few field observations of these quantities over sea ice exist. Passive microwave observations provide high sensitivity to clouds and water vapor with high spatial and temporal coverage in polar regions. However, retrievals of atmospheric quantities from satellites and aircraft require a description of the variable sea ice emissivity, which depends on the properties of sea ice and snow. Recently, improved retrieval methods that derive sea ice and atmospheric properties simultaneously allowed for improved exploitation of the information from passive microwave observations.

This work presents liquid water path (LWP), ice water path (IWP), and integrated water vapor (IWV) retrieved from the HALO Microwave Package (HAMP) operated onboard the HALO aircraft during the HALO-(AC)3 field campaign in spring 2022 in the Fram Strait. The nadir-viewing HAMP measures along two water vapor bands (22.24 and 183.31 GHz), two oxygen bands (50-60 and 118.75 GHz), and the atmospheric windows at 31 and 90 GHz over different surface types. The retrieval accounts for variable surface emission through a joint surface-atmosphere optimal estimation scheme with the Passive and Active Microwave Radiative Transfer (PAMTRA) model.

The high spatial coverage of the HALO flights allows for assessing the spatial and temporal variability of the retrieved IWV, LWP, and IWP under various atmospheric and surface conditions. A particular focus lies on the warm air intrusion events and their related poleward changes in cloud properties and water vapor over sea ice that HALO captured. Furthermore, the hectometer-scale airborne observations allow statistical comparison with operational satellite products, reanalysis, and model simulations along the flight track. The HAMP observations will improve the characterization of clouds and water vapor in the Arctic and potentially improve the use of passive microwave satellite observations over sea ice.

How to cite: Risse, N., Mech, M., Prigent, C., and Crewell, S.: Investigating Arctic Clouds and Water Vapor over Sea Ice: Airborne Passive Microwave Observations during HALO-(AC)3, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16503, https://doi.org/10.5194/egusphere-egu24-16503, 2024.

EGU24-17876 | Posters on site | AS1.13 | Highlight

How can the proposed  WIVERN satellite mission improve global snowfall measurements? 

Maximilian Maahn, Alessandro Battaglia, Anthony Illingworth, Pavlos Kollias, Stef Lhermitte, Filippo Emilio Scarsi, and Frederic Tridon

Snowfall is an important climate change indicator affecting surface albedo, glaciers, sea ice, freshwater storage, and cloud lifetime. Accurate snowfall measurements at high latitudes are particularly important for the mass balance of ice sheets and for sustaining healthy ecosystems, including fish and wildlife populations. Yet, snowfall remains a quantity which is hard to measure due to high spatial variability, the remoteness of polar regions and challenges associated with in situ measurements of snowfall. The recently decommissioned NASA CloudSat mission provided invaluable information about global snowfall climatology from 2006 to 2023. The CloudSat-based estimates of global snowfall are considered the reference for global snowfall estimates, but these data sets suffer from poor sampling and the inability to see shallow precipitation, which limits their use, for example, as input to surface mass balance models of the major ice sheets. WIVERN (WInd VElocity Radar Nephoscope) is one of the two remaining ESA Earth Explorer 11 candidate missions equipped with a conical scanning 94 GHz radar and a passive 94 GHz radiometer. The main objective of the mission is to measure global in-cloud winds using the Doppler effect, but can also quantify cloud ice water content and precipitation rate. 

 

This presentation discusses the potential of the WIVERN mission to provide improved estimates of global snowfall measurements. Compared to CloudSat, WIVERN's 800 km swath provides 70 times better coverage and its 42 degree angle of arrival significantly reduces the radar blind zone near the surface (especially over the ocean). In addition, WIVERN's radar is accompanied by a radiometer, which can further improve the estimation of snowfall rates. The improved sampling is demonstrated for specific regions ( Antarctica, Greenland) by computing the sampling error at different spatial and temporal scales via simulations of WIVERN vs. CloudSat orbits based on the snowfall rates produced by ERA5 reanalysis. Clutter and signal to clutter ratio simulations are performed for oceanic surfaces and orographic terrains by using a geometric–optics approach and the WIVERN illumination geometry.  Our results show that the WIVERN sampling strategy significantly reduces the uncertainty in polar snowfall estimates, making it a valuable product for climate model evaluation and as an input to surface mass balance models of the major ice sheets.

How to cite: Maahn, M., Battaglia, A., Illingworth, A., Kollias, P., Lhermitte, S., Scarsi, F. E., and Tridon, F.: How can the proposed  WIVERN satellite mission improve global snowfall measurements?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17876, https://doi.org/10.5194/egusphere-egu24-17876, 2024.

EGU24-18277 | ECS | Posters on site | AS1.13

Investigating the role of air mass history of Arctic black carbon in GCMs 

Roxana S. Cremer, Paul Kim, Sara M. Blichner, Emanuele Tovazzi, Ben Johnson, Zak Kipling, Thomas Kühn, Duncan Watson-Parris, David Neubauer, Phillip Stier, Alistair Sellar, Eemeli Holopainen, Ilona Riipinen, and Daniel G. Partridge

Black Carbon (BC) aerosols are known to be important for the Earth’s climate, yet their exact role to the changing of the Earth’s climate and Arctic amplification remains unclear. An accurate description of the BC life cycle in general circulation models (GCMs) can help reduce the uncertainties due to BC aerosols and specify BC's role in the Arctic.

In this study, several GCMs (ECHAM6.3-HAM2.3, ECHAM6.3-HAM2.3-P3, ECHAM6.3-HAM2.3-SALSA2 and UKESM1.0) are compared in terms of their representation of BC mass in the Arctic within the AeroCom project GCM Trajectory. A novel Lagrangian framework is employed to examine the history of air masses reaching the observational station Zeppelin, Svalbard. Therfore the removal processes were analysed along the trajectory and the GCMs compared with each other. The analysis emphasises the impact of remote emissions on local BC concentrations in the Arctic, indicating a longer BC lifetime compared to the global average. This underlines the importance of dry and wet scavenging parametrisations in the GCMs.

 

 

 

How to cite: Cremer, R. S., Kim, P., Blichner, S. M., Tovazzi, E., Johnson, B., Kipling, Z., Kühn, T., Watson-Parris, D., Neubauer, D., Stier, P., Sellar, A., Holopainen, E., Riipinen, I., and Partridge, D. G.: Investigating the role of air mass history of Arctic black carbon in GCMs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18277, https://doi.org/10.5194/egusphere-egu24-18277, 2024.

EGU24-18940 | Posters on site | AS1.13

Liquid water path derived from airborne observations over the sea-ice-free Arctic ocean 

Mario Mech, Maximilin Ringel, Nils Risse, and Susanne Crewell

Arctic Amplification is most evident in the rise of the near-surface air temperature observed in the last decades, which has been at least twice as strong as the global average. The mechanisms behind that are widely discussed. Many processes and feedback mechanisms still need to be better understood, especially those connected to clouds and their role in the water and energy cycle. Thereby, the cloud liquid water path (LWP) is an important cloud parameter, and it is important to know its occurrence and spatial variability. However, observing LWP is prone to high uncertainties, especially in the Arctic, leading to about a factor of two difference in satellite retrievals between microwave and near-infrared retrievals. Moreover, weather and climate models show significant differences in Arctic regions.

Within this contribution, we will present LWP observations over the sea-ice-free Arctic ocean from measurements conducted during four airborne campaigns conducted within the framework of the "Arctic Amplification: Climate relevant atmospheric and surface processes and feedback mechanisms (AC)3" during the last years over the Fram Strait West of Svalbard. The LWP has been derived by statistical retrieval approaches based on brightness temperature measurements of the Microwave Radar/radiometer for Arctic Clouds (MiRAC) operated onboard the Polar 5 research aircraft of the Alfred-Wegener Institute for Polar and Marine Research (AWI). The consistent LWP product has been used in a comparison study to validate satellite estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Microwave Scanning Radiometer 2 (AMSR2) and the one from the ERA5 reanalyses. It could be seen that the various products reveal a characteristic shape of the LWP distribution, but their overall performance varies with season and synoptic situations, i.e., ERA5 does not produce larger LWP values and an over- or under-estimation for specific flights and too high LWP values for MODIS and too low for AMSR2 during cold air outbreak events.

How to cite: Mech, M., Ringel, M., Risse, N., and Crewell, S.: Liquid water path derived from airborne observations over the sea-ice-free Arctic ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18940, https://doi.org/10.5194/egusphere-egu24-18940, 2024.

EGU24-22016 | ECS | Posters virtual | AS1.13

Snowfall particle size distribution and precipitation observations in the Southern Ocean and coastal Antarctica 

Claudio Durán Alarcón, Irina Gorodetskaya, Diogo Luis, Alexis Berne, Michael Lehning, and Katherine Leonard

Snowfall is a key component to the Antarctic region, contributing significantly to the surface mass balance and influencing mean sea level changes. The intricate nature of ice particle microphysics, encompassing type, size, and structure, presents a great challenge in comprehending the processes of solid precipitation in Antarctica. The characteristics of individual ice crystals as they fall from clouds are crucial for understanding their formation and evolution along the vertical profile. Mechanisms such as aggregation, fragmentation, and riming play a pivotal role in accurately representing precipitation in numerical weather prediction models [1]. Despite their importance, the scarcity of observations for evaluating and validating these processes, particularly in the Southern Ocean and Antarctica, adds complexity. To address this gap, a comprehensive set of precipitation observations occurred during the Antarctic Circumnavigation Expedition (ACE) in the austral summer of 2016-2017 was carried out, utilizing diverse sensors aboard the research vessel Akademik Tryoshnikov. The observational toolkit included a snow particle counter (SPC), two total particle counters (Wenglors), vertical precipitation profiles from 24-GHz micro rain radar (MRR) observations, and manually collected Formvar samples. The Formvar technique, preserving ice particle shapes, offers insights into microphysical properties of ice crystals and snowflakes. SPC and Formvar were employed for particle size distribution (PSD) characterization and quantitative precipitation estimations (QPE) [2]. Precipitation was derived from MRR using the existing reflectivity (Ze)-snowfall (S) relationship for Antarctica [3,4,5]. During ACE, primary observations related to snowfall were near the coasts of the Antarctic Peninsula, Western Antarctica, and Adélie Land (Eastern Antarctica). In the last region, a large-scale event was observed by both the ACE expedition and a Multi-angle Snowflake Camera (MASC) at Dumont d’Urville station. Results showed good agreement between Formvar, SPC (size < 500µm), and MASC (size > 500µm) PSDs. Notably, the 20-µm resolution Formvar images exhibited significantly better performance for particles smaller than 500µm compared to MASC (35-µm resolution). Regarding QPE, all sources exhibited a large spread, particularly MRR estimations, sensitive to Ze-S relationship parameters. The use of PSD observations proved useful in making informed choices about these parameters. In monitoring snowfall precipitation, developing a multi-instrumental approach to overcome individual system limitations is crucial, reducing uncertainty.

References:

[1] Grazioli, J. et al. MASCDB, a database of images, descriptors and microphysical properties of individual snowflakes in free fall. Sci Data 9, 186 (2022).

[2] Sugiura, K. et al., Application of a snow particle counter to solid precipitation measurements under Arctic conditions. CRST, 58: 77-83, 2009.

[3] Grazioli, J. et al., Measurements of precipitation in Dumont d'Urville, Adélie Land, East Antarctica. TC 11, 1797–1811, 2017.

[4] Souverijns, N. et al., Estimating radar reflectivity – snowfall rate relationships and their uncertainties over Antarctica by combining disdrometer and radar observations. AR, 196: 211–223, 2017.

[5] M.S. Kulie and R. Bennartz, Utilizing Spaceborne Radars to Retrieve Dry Snowfall. JAMC, 48, 2564-2580.

Acknowledgements: PROPOLAR APMAR-2024, FCT ATLACE (CIRCNA/CAC/0273/2019) and ANR-APRES3. ACE was made possible by funding from the Swiss Polar Institute and Ferring Pharmaceuticals.

How to cite: Durán Alarcón, C., Gorodetskaya, I., Luis, D., Berne, A., Lehning, M., and Leonard, K.: Snowfall particle size distribution and precipitation observations in the Southern Ocean and coastal Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22016, https://doi.org/10.5194/egusphere-egu24-22016, 2024.

EGU24-4289 | ECS | Orals | AS2.2

Modelling of urban lake breeze circulation: the implications on urban heat island mitigation 

Qilong Zhong, Jiyun Song, Xiaoxue Wang, and Yuguo Li

Recent years have seen more intense and frequent heatwaves across the globe. Urban overheating phenomenon induced by global warming and urban heat island (UHI) effect has adverse impact on human health. In particular, compact high-rise cities witnessed worsened wind environment, exacerbating the UHI phenomenon. Blue space such as urban lakes may help mitigate the UHI effect and improve citizens’ living environment. Under weak synoptic wind conditions, the temperature difference between built-up areas and lakes can induce wind circulation, known as lake-breeze circulation (LBC). The LBC system can transport cool and fresh air from lake surfaces into built-up areas, reducing urban air temperature and improving urban wind environment, while increasing urban air humidity. In this study, we developed a multi-scale water-energy coupled CFD model to simulate the transport processes of heat and moisture between lake surfaces and built-up areas within the urban boundary layer. The model adopted a porous turbulence model to simulate the entire urban canopy layer, a lake evaporation model and a species transport model to simulate lake dynamics, and a coordinate transformation method to simulate the effect of the background atmosphere. The model features the capability of resolving dynamics of atmospheric temperature, humidity, and wind at both street canyon scale (1 m) and city scale (50 km) with relatively low computational costs. Based on this model, we conducted sensitivity analysis to investigate the impact of urban parameters (e.g., city scale, building height and density, anthropogenic activities) and lake parameters (e.g., lake scale and lake surface temperature) on the spatial variation of temperature, humidity, wind, and thermal comfort index. Our results can provide significant references for urban planning and city design for sake of UHI mitigation.

How to cite: Zhong, Q., Song, J., Wang, X., and Li, Y.: Modelling of urban lake breeze circulation: the implications on urban heat island mitigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4289, https://doi.org/10.5194/egusphere-egu24-4289, 2024.

EGU24-4829 | ECS | Orals | AS2.2

A one-dimensional urban flow model with an Eddy-diffusivity Mass-flux (EDMF) scheme and refined turbulent transport (MLUCM v3.0) 

Jiachen Lu, Negin Nazarian, Melissa Hart, and Scott Krayenhoff

In recent years, urban canopy models (UCMs) have been used as fully coupled components of mesoscale atmospheric models as well as offline tools to estimate temperature and surface fluxes using atmospheric forcings. Examples include multi-layer urban canopy models (MLUCMs), where the vertical variability of turbulent fluxes is calculated by solving prognostic momentum and turbulent kinetic energy (TKE, $k$) equations using length scale ($l$) and drag parameterizations. These parameterizations are based on the well-established 1.5-order $k-l$ turbulence closure theory and are often informed by microscale fluid dynamics simulations. However, this approach can include simplifications such as the assumption of the same diffusion coefficient for momentum, TKE, and scalars. In addition, the dispersive stresses arising from spatially-averaged flow properties have been parameterized together with the turbulent fluxes while being controlled by different mechanisms. Both of these assumptions impact the quantification of turbulent exchange of flow properties and subsequent air temperature prediction in urban canopies. To assess these assumptions and improve corresponding parameterization, we conducted 49 large-eddy simulations (LES) for idealized urban arrays, encompassing variable building height distributions and a comprehensive range of urban densities ($\lambda_p\in[0.0625,0.64]$) seen in global cities. We find that the efficiency of turbulent transport (numerically described via diffusion coefficients) is similar for scalars and momentum but 3.5 times higher for TKE. Additionally, the parameterization of the dispersive momentum flux using the $k-l$ closure was a source of error, while scaling with the pressure gradient and urban morphological parameters appears more appropriate. In response to these findings, we propose two changes to MLUCM v2.0: (a) separate characterization for turbulent diffusion coefficient for momentum and TKE; and (b) introduction of an explicit physics-based "mass flux" term to represent the non-Gaussian component of the dispersive momentum transport as an amendment to the existing "eddy diffusivity" framework. The updated one-dimensional model, after being tuned for building height variability, is further compared against the original LES results and demonstrates improved performance in predicting vertical turbulent exchange in urban canopies.

How to cite: Lu, J., Nazarian, N., Hart, M., and Krayenhoff, S.: A one-dimensional urban flow model with an Eddy-diffusivity Mass-flux (EDMF) scheme and refined turbulent transport (MLUCM v3.0), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4829, https://doi.org/10.5194/egusphere-egu24-4829, 2024.

EGU24-5608 | ECS | Orals | AS2.2

Impacts of urban development on the local weather: A comprehensive analysis from 1970 to 2020 in Madrid. 

Juan Carbone, Beatriz Sánchez, Carlos Román-Cascón, Alberto Martilli, Dominic Royé, and Carlos Yagüe

The proportion of the world’s population living in cities has increased from 37% to 56% over the last 50 years, and it is expected to continue rising further to 60% by 2030 (UN, 2022). As an essential effect of this evolution, urban land cover has expanded rapidly. In the case of Madrid, the increase in urban fraction during the period from 1970 to 2020 has been 20%. It is well known that urbanization reduces the vegetated cover and modifies surfaces properties altering the surface-atmosphere interactions and the different terms of the Surface Energy Balnace (SEB) compared to nearby rural areas. Therefore, analyzing the influence of these changes in urban land cover contributes to understand the potential risks that urban residents might face considering the urban grown and the expected temperatures increases, as this has adverse impacts on human health, livelihoods, and key urban infrastructure.

The aim of the present study is to examine the consequence of Madrid's urban growth on the near-surface air temperature and on the SEB. We conduct a modeling study using WRF-ARW with the multilayer urban parameterization BEP-BEM, in which the land use and the land cover have been modified according to urban expansion in Madrid and its surroundings from 1970 to 2020. Two scenarios of common meteorological conditions of special interest are selected for this study: a period of intense heatwave during the summer season and a short period of strongly stable atmospheric conditions in winter, both observed in 2020. The results show that in areas where the urban fraction become greater an increase in near-surface air temperature is found for both simulated periods, especially during the night, pointing out that the cooling rate decreases in urban areas. The growing of urban land cover over time also modifies the SEB and turbulent transport in Madrid and surroundings, leading to an increase in temperatures, specially for the minima ones.

How to cite: Carbone, J., Sánchez, B., Román-Cascón, C., Martilli, A., Royé, D., and Yagüe, C.: Impacts of urban development on the local weather: A comprehensive analysis from 1970 to 2020 in Madrid., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5608, https://doi.org/10.5194/egusphere-egu24-5608, 2024.

EGU24-6308 | ECS | Orals | AS2.2

The Implementation of the BEP+BEM Offline Parameterization Scheme: Exploring Urban Dynamics through Climatic Projections 

Gianluca Pappaccogli, Andrea Zonato, Alberto Martilli, Riccardo Buccolieri, and Piero Lionello

As climate change continues to exert an impact on urban areas, the comprehension of its effects on the urban environment becomes crucial for sustainable urban planning. This study presents a novel approach employing the Building Effect Parameterization (BEP) coupled with a Building Energy Model (BEM) in an offline configuration to simulate urban climates. The multi-layer BEP+BEM model, properly describes the vertical arrangement of urban fabric, accounting for the distribution of heat, moisture, and momentum sources throughout the urban canopy layer. Additionally, energy consumption within buildings for both cooling and heating is estimated by the BEM, providing a comprehensive perspective on the urban energy balance. Coupled with a 1-D column model of urban canopy flow, the BEP+BEM offline model accurately estimates drag coefficients and turbulent length scales based on urban fabric characteristics. In the proposed version, the model has been extended to consider additional factors such as green areas and street trees, along with existing green roofs, photovoltaic panels and the permeability of urban materials. This expansion enhances the model's capability to assess the effectiveness of sustainable infrastructure in mitigating climate change effects on urban areas. In this study, the BEP+BEM scheme is forced by data from climate projections, allowing for the dynamic representation of various Local Climate Zones (LCZs) under distinct climatic conditions. Simulations in different LCZs and under different climatic conditions are compared to evaluate the impact of climate change on urban environment, enabling the exploration of how different urban areas respond to changing meteorological forcings. The sensitivity analysis includes a range of standard urban typologies (i.e. LCZs), capturing the complexity of interactions between the built environment and the atmosphere. This approach offers an assessment of the impacts of climate change on key urban phenomena, such as urban heat islands (UHI), thermal discomfort, and heightened energy consumption by buildings. The outcomes of this study provide valuable insights for the urban climate community, policymakers, and researchers with the aim of enhancing the resilience of cities in the face of a changing climate. By bridging the gap between climate projections and urban climate simulations, a consistent framework is presented in this work for evaluating and adapting various urban environments to future climatic conditions.

How to cite: Pappaccogli, G., Zonato, A., Martilli, A., Buccolieri, R., and Lionello, P.: The Implementation of the BEP+BEM Offline Parameterization Scheme: Exploring Urban Dynamics through Climatic Projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6308, https://doi.org/10.5194/egusphere-egu24-6308, 2024.

EGU24-7011 | Orals | AS2.2

UrbanTALES: A comprehensive dataset of Urban Turbulent Airflow using systematic Large Eddy Simulations 

Negin Nazarian, Jiachen Lu, Melissa Hart, and E. Scott Krayenhoff

The urban canopy layer (UCL) is characterized by a heterogeneous flow pattern that responds to heterogeneous urban geometries. The varying heights and layouts of buildings play a pivotal role in shaping this spatial variability, as they block, divert, and slow wind and determine the exchange of momentum and energy above the urban canopy. When representing these complex dynamics, however, research has conventionally relied on microscale simulations conducted over limited (often idealized) building arrays. Extending the findings to realistic urban neighborhoods and urban parameterizations presents a clear limitation, as evidenced by discrepancies in multi-model comparisons with observational data in cities.

More extensive datasets of urban airflow are needed to cover a range of realistic urban neighborhoods and provide a more holistic analysis of turbulent flow in different urban characteristics. Responding to this gap in the field, we developed a historically extensive and comprehensive dataset of Urban Turbulent Airflow based on state-of-the-art  Large Eddy Simulations (UrbanTALES). The dataset includes 400 urban layouts with both idealized and realistic configurations. Realistic urban neighborhoods were obtained from major cities worldwide, incorporating variations in plan area densities [0.0625-0.64] and height distributions [4-70m]. Idealized urban arrays, on the other hand, include two commonly studied configurations (aligned and staggered arrays), featuring both uniform and variable height scenarios along with oblique wind directions. 

UrbanTALES offers canopy-averaged data as well as 2D and 3D flow fields tailored for different applications in urban climate research. The dataset provides time-averaged wind flow properties, as well as second- and third-order flow moments that are critical for understanding turbulent processes in the UCL. Here, we describe the UrbanTALES dataset and its application, noting the unique opportunity to deploy a comprehensive representation of realistic urban neighborhoods for a) revisiting neighborhood-scale urban canopy parameterizations in various models and b) informing in-canopy flow and turbulent analyses. Furthermore, we discuss the application of this dataset for training Machine Learning algorithms for pedestrian wind speed. 

How to cite: Nazarian, N., Lu, J., Hart, M., and Krayenhoff, E. S.: UrbanTALES: A comprehensive dataset of Urban Turbulent Airflow using systematic Large Eddy Simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7011, https://doi.org/10.5194/egusphere-egu24-7011, 2024.

EGU24-7970 | ECS | Posters on site | AS2.2

Can urban heating inadvertently induce urban cooling? 

Klaas Laan and Dilia Kool

EGU24-7970

Can urban heating inadvertently induce urban cooling?

Klaas Laan and Dilia Kool

 

Cities are getting hotter—and will continue to get hotter with projected climate change and increases in urbanization. However, is it possible that rising temperatures present an opportunity for enhanced evaporative cooling? Evaporative cooling generally increases linearly with an increase in the vegetative fraction. But it is also well documented that this linearity breaks down at a certain point, and that as the vegetation becomes denser, the relative increase in evapotranspiration becomes more marginal. One possible explanation is the known phenomenon that lateral heat advection enhances evapotranspiration from “scattered” or “patchy” vegetation. Lateral heat advection occurs when there is a large temperature contrast between hot, non-vegetated surfaces and much cooler vegetated surfaces. Lateral heat advection is expected to be larger at lower vegetation fractions (more source areas) and in climates that have more extreme temperatures (arid regions, future climate change-affected areas (?)). We expect that potential evaporation per unit area, enhanced by lateral heat advection, will be inversely proportional to the vegetation fraction. Thus, higher temperatures and lower vegetation fractions would result in higher evaporative cooling per unit vegetated area. This, then, could explain the non-linear relationship between evaporative cooling and vegetation fraction.

We here present a novel analysis of the dynamics of potential and actual evapotranspiration as a function of vegetation fraction using an existing urban energy balance dataset for 13 locations representing a range of climate conditions (Lipson et al., 2022; doi 10.5194/essd-14-5157-2022). A separate assessment of the horizontal component of potential evaporation and its potential implications for enhanced evaporation sheds light on whether urban heating could, to some extent, induce urban cooling.

How to cite: Laan, K. and Kool, D.: Can urban heating inadvertently induce urban cooling?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7970, https://doi.org/10.5194/egusphere-egu24-7970, 2024.

EGU24-13329 | Posters on site | AS2.2

A Versatile Reduced Order Model of Urban Boundary Layer Dynamics in the Center of Paris 

Konstantin Kuznetsov, Paul Sylvestre, Pavel Litvinov, Oleg Dubovik, and David Fuertes

The computational demands of Computational Fluid Dynamics (CFD) often limit its real-time or large-scale applications, particularly in scenarios requiring multiple simulations based on varying input parameters. This study introduces a surrogate reduced order model (ROM) that not only addresses the computational challenges of CFD but also underscores its potential for broad applicability.

We focus on the dynamics of the Urban Boundary Layer (UBL), a key factor in understanding urban microclimates and their impact on energy consumption, thermal comfort, and local weather phenomena. Using a representative urban test case from the city center of Paris, we illustrate the effectiveness of our approach. During the offline phase, the ROM is constructed by assembling a database of Dynamic Mode Decomposition (DMD) modes [1] associated with various aspects of UBL dynamics, such as temperature distribution, wind patterns, and turbulence characteristics. These modes are determined based on a set of meteorological conditions defined through k-means clustering analysis. During the online phase, we interpolate these DMD modes from the database, enabling us to determine the dynamic characteristics of the UBL within the domain without initiating computationally intensive code_saturne calculations.

Our validation for the UBL dynamics in central Paris indicates that the online phase can achieve a Normalized Root Mean Square Error (NRMSE) of 2-8%. A distinctive aspect of our approach is the incorporation of DMD during the code_saturne computation process. Some modifications of DMD can be seamlessly integrated into numerous code_saturne simulations, harnessing the advantages of DMD with minimal computational trade-offs. This ROM approach offers a promising tool for urban climate studies, urban planning, and environmental management, providing a more efficient means to simulate and understand the complex dynamics of the Urban Boundary Layer.

How to cite: Kuznetsov, K., Sylvestre, P., Litvinov, P., Dubovik, O., and Fuertes, D.: A Versatile Reduced Order Model of Urban Boundary Layer Dynamics in the Center of Paris, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13329, https://doi.org/10.5194/egusphere-egu24-13329, 2024.

EGU24-15662 | ECS | Posters on site | AS2.2

How does urbanization shape the record-breaking temperatures in Izmir, Turkey ? 

Fatma Başak Saka and Yurdanur Unal

The urban heat island effect, denoting the temperature difference between urban and rural areas, has become more widely recognized due to the increasing urbanization over the years. Recent studies related to the urban heat island effect mainly focus on changes in atmospheric changes and their role in triggering significant weather phenomena. Understanding these dynamics is crucial for making future projections. This research is motivated by the need to understand how the urban heat island intensity affects the boundary layer and temperature structure of İzmir, Türkiye during a record-breaking temperature period, in July 2023.  Temperatures in the Aegion region for July 2023 are above season normals of the 1991-2020 period by 1.7ºC. To investigate how urbanization contributed to the temperature changes the chosen timeframe is modeled using the Weather Research and Forecasting (WRF) Model (version 4.3). To enhance spatial resolution, we integrated the Coordination of Information on the Environment (CORINE) land cover data into the model, employing a nested domain setup ranging from outer to inner domains with resolutions of 9-3-1 km. ERA5 Reanalysis was chosen as the initial condition to force the model throughout the selected period. Following the simulations using the parameterizations set optimized for the Izmir region in July 2023, the obtained results were scrutinized through a comparison with data from meteorological observation stations to analyze the accuracy and performance of the simulations.    Then, to examine how urban areas affect atmospheric behavior under record-breaking conditions, atmospheric conditions of  July 2003 were simulated by utilizing the same parameterizations and boundary conditions with altered land use categories.   The urban land-use categories within the domain were changed to the most dominant rural land-use category.   In evaluating the city's influence on record-breaking temperatures, the analysis focused on changes in the atmospheric boundary layer and its associated parameters by comparing the simulations with urbanizations and without urbanization in İzmir.

How to cite: Saka, F. B. and Unal, Y.: How does urbanization shape the record-breaking temperatures in Izmir, Turkey ?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15662, https://doi.org/10.5194/egusphere-egu24-15662, 2024.

EGU24-16346 | ECS | Posters on site | AS2.2

Urban roughness sublayer characteristics: sensitivity to planetary boundary layer schemes and multi-layer urban models 

Wanliang Zhang, Jimmy Chi Hung Fung, and Mau Fung Michael Wong

The Pearl River Delta (PRD) region in China is characterized by a large fraction of urbanized areas of which the growth rate is unprecedented. Modelling a realistic meteorological field for such a region is challenging mainly due to the uncertainties in the meso-scale numerical model, and the paucity of high-resolution profiler-type observations. In this study, we aim to improve the understanding of the urban effects on the modelled meteorological field in the PRD region by applying different fine-tuned planetary boundary layer (PBL) schemes coupled with two multi-layer urban models and leveraging the high spatial-temporal wind LiDAR observations. Particularly, the momentum in the urban roughness sublayer (RSL, about three times the building height) will be thoroughly investigated using long-lasting profiler-type observations.

The Weather Research and Forecast (WRF) model offers a variety of PBL schemes which may feature a non-local transport algorithm under unstable atmospheric conditions. Most PBL schemes utilize the surface layer fluxes calculated based on the Monin-Obukhov similarity theory, acting on the first model layer only. Although this bulk parameterization of surface layer fluxes is appropriate for urban areas occupied predominantly by low-rise buildings, it is unable to reflect the momentum drag and thermal exchange processes when the average building height (H) within a model cell greatly exceeds the height of the lowest model. Multi-layer urban models, Building Effects Parameterization (BEP), and Building Energy Model (BEM) can be coupled with PBL schemes to provide a more realistic interaction between buildings and air within the RSL. Required input for initializing the multi-layer urban models include H and average street width, which can be simply prescribed (assumed) or derived from the local climate zones.

Despite many efforts have been made to study the improvements by urban models on the surface meteorological variables, such as 10-m wind speed, 2-m temperature and moisture, little investigation of modelled results has been carried out focusing on the RSL and the entire boundary layer over a long-time series due to scarce observations. Recently, three wind LiDAR units were deployed in Hong Kong, providing us with a valuable opportunity to monitor wind profile evolution continuously at a 25-m and 1-hr resolution and to reveal the transport of surface layer fluxes to the overlying RSL.  In the result section, we first present the wind speed profiles to understand the benefits of a multi-layer urban model compared to the bulk parameterization, justified by the LiDAR observations. Secondly, as the non-local PBL scheme can transport the surface fluxes to non-adjacent cells, a comparison of the momentum flux profile will be presented between local and non-local PBL schemes under different stabilities.

How to cite: Zhang, W., Fung, J. C. H., and Wong, M. F. M.: Urban roughness sublayer characteristics: sensitivity to planetary boundary layer schemes and multi-layer urban models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16346, https://doi.org/10.5194/egusphere-egu24-16346, 2024.

EGU24-16420 | Orals | AS2.2

Representing mean wind speed profile over urban canopy with building height variability 

Keisuke Nakao, Hideki Kikumoto, Hiroshi Takimoto, Jia Hongyuan, and Wang Xiang

 The horizontal mean wind speed profile in vertical direction within and above urban canopy (UC) is an essential information to drive the exchange of momentum, heat, moisture and pollutants in atmosphere. Well-known profiles in logarithmic and exponential layers, which express upper and lower wind over UC, respectively, are efficient assumptions used to express UC wind profile.

 This study attempted to add the intermediate layer (IL) between those two-layers to include the effect of building height variability on the mean wind speed profile. Large-eddy simulations (LESs) of UC with building height variability were conducted using a wide range of morphology parameters, that is, plan area index, aspect ratio, and the standard deviation of building height.

 A tendency of the bulk drag coefficient of the IL was expressed by the plan area index and the frontal area index at the intermediate layer. The wind speed at IL was modeled linearly by the length- and velocity-scale analysis. By parameterizing the coefficients of these three layers, we attempted to analytically represent an entire wind speed profile by the three-layer wind profiles. The results indicated reasonable consistency in the wind speeds at mean building height and the momentum flux with LES data. Effect of the thermal stratification was investigated by the correction of the length-scale in IL.

How to cite: Nakao, K., Kikumoto, H., Takimoto, H., Hongyuan, J., and Xiang, W.: Representing mean wind speed profile over urban canopy with building height variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16420, https://doi.org/10.5194/egusphere-egu24-16420, 2024.

EGU24-16891 | ECS | Orals | AS2.2

A systematic investigation of urban modifications of mixed layer height and cloud cover in Berlin, Germany 

Daniel Fenner, Andreas Christen, Russell Glazer, Sue Grimmond, Simone Kotthaus, Dana Looschelders, Fred Meier, William Morrison, and Matthias Zeeman

In order to better understand how urban areas modify the regional atmospheric boundary layer (ABL) and to improve and evaluate weather and climate models for urban applications and services, detailed ABL observations are needed. With new instrument technologies and advanced automatic algorithms for detection of aerosols, mixed-layer height (MLH) and boundary-layer clouds, ground-based remote sensing instruments are increasingly used in urban observational networks.

During a one-year measurement campaign in Berlin, Germany (urbisphere-Berlin, Autumn 2021 – Autumn 2022), a variety of ground-based ABL observations were carried out in the greater Berlin region. Berlin as an isolated continental city with approximately 3.8 million inhabitants provides a fairly homogeneous rural background. The urbisphere network included five inner-city, six outer-city and 14 rural sites equipped with continuously-operated Automatic Lidar and Ceilometers (ALC). The measurement network was designed and set up in a systematic and rigorous manner in order to capture intra-urban, urban-rural, and upwind-city-downwind effects of MLH, cloud-base height (CBH), and cloud cover fraction (CCF) along several transects as air masses move over the city. Based on the ALC observations, MLH, CBH and CCF were automatically derived. ALC observations are complemented by measurements of wind and temperature profiles over the city using Doppler-Wind Lidars and radiosondes concurrently released in urban and rural locations during selected days. Surface heat fluxes are continuously measured with six eddy-covariance flux towers and seven path-averaging scintillometers in urban and rural settings.

This contribution highlights the scientific considerations of the systematic measurement network design and the corresponding data analysis. We are proposing a scheme of attributing measurements to rings around the city centre representing the inner city (radius of 6 km), the outer city (radius of 18 km) and rural areas (radius of 90 km), further separated into upwind, downwind and other sectors. A detailed statistical analysis of the year-long dataset finds differences in MLH, CBH and CCF during different seasons and under different weather forcings. Selected case-study days are analysed in more detail to understand the processes controlling the interactions between surface fluxes and mixed-layer dynamics. These days are further used to evaluate the forecasting skill of hectometric dynamical-modelling runs with regard to ABL dynamics, quantifying also the sensitivity of ABL dynamics in the model to surface representation (e.g. soil moisture, heat flux partitioning).

How to cite: Fenner, D., Christen, A., Glazer, R., Grimmond, S., Kotthaus, S., Looschelders, D., Meier, F., Morrison, W., and Zeeman, M.: A systematic investigation of urban modifications of mixed layer height and cloud cover in Berlin, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16891, https://doi.org/10.5194/egusphere-egu24-16891, 2024.

EGU24-17628 | ECS | Posters on site | AS2.2

Large-Eddy Simulations of Methane Dispersion at the Utrecht University Campus 

Steven van der Linden, Judith Tettenborn, Thomas Röckmann, Stephan de Roode, and Bas van de Wiel

Last June 2023 a controlled release experiment (CRE) of methane was conducted at the campus of the Utrecht University, the Netherlands, with the aim of improving models for emission quantification. The methane was released at different flow rates and subsequently measured in the local area (along closed paths of approximately 500 m length) using vehicle mounted sensors. In addition, several wind sensors were deployed at approximately 35 meters distance of the release location covering the dominant flow pathways between the buildings.

Although the setup enables us to relate the variability in wind direction and concentration peaks in the direct vicinity of the release, the limited spatial extent of the setup still makes it challenging to determine the dispersion of methane on the larger campus scale. Therefore, we explore the possibility to use meter-scale Large-Eddy Simulations (LES) in which the flow around the buildings is explicitly resolved with an immersed boundary method. With this approach, we aim to provide detailed information on the dispersion of methane ranging from the street-level to the campus scale.

Here, we will show the first results of our simulations and a comparison with the observations. The controlled release experiment and wind measurements serve as validation for the LES, with the LES ideally reproducing the observed concentrations and wind directions in a statistical sense. We will discuss the model complexity required to accurately model observed dispersion features and look at the dependence of this result to changes in model setup. For example, how the model result changes with respect to a change in the prescription of large-scale meteorological conditions.

Such validated urban LES may in the future be used not only for forward-in-time prediction of pollutant concentrations but also for inverse modelling to estimate the location of pollutant release, when only a limited number of observations are available.

How to cite: van der Linden, S., Tettenborn, J., Röckmann, T., de Roode, S., and van de Wiel, B.: Large-Eddy Simulations of Methane Dispersion at the Utrecht University Campus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17628, https://doi.org/10.5194/egusphere-egu24-17628, 2024.

EGU24-17845 | Orals | AS2.2

Can a city modify a severe convective windstorm? 

Francesco De Martin, Andrea Zonato, and Silvana Di Sabatino

It is well known that cities can modify the rainfall distributions, in particular deep moist convection is more frequently triggered over and downwind urban areas. However, the effect of cities on the most extreme convective events, such as hailstorms, downbursts or tornadoes, is poorly studied. This topic needs further investigation since exposure and vulnerability to severe storm risk is larger in cities than in the surrounding rural area. What happens if a severe convective windstorm impacts a big city? Is the storm modified by the urban land use?

Our analysis focuses on a case study that occurred on 25 July 2023, when a nocturnal downburst affected the city of Milan, in northern Italy, with measured wind gusts up to 30 m/s. The intense wind gusts downed many trees in the public parks and over the streets, blocking urban mobility. The event is investigated in depth using both observations and high-resolution numerical simulations performed with the WRF model.

Observations show that a UHI over Milan before the storm was negligible, while there was a drier air mass over the city than over the surrounding rural area. Consequently, a pool with low values of equivalent potential temperature (theta-e), a quantity that strongly influences deep moist convection, was present over the city.

Four nested WRF simulations are carried out with grid resolution from 9 km up to 333 m, and 64 vertical levels starting from 5m AGL. Two different boundary layer parametrizations are tested, namely MYJ and BouLac schemes, as well as two different microphysics schemes: Thompson and WRF Single-moment 6-class. Moreover, simulations with bulk urban parametrizations are compared with those coupled with the building effect parameterization and the building energy model (BEP-BEM), employing data of the World Urban Database and Access Portal Tools (WUDAPT).  Simulations without the urban land use (no-urban) are carried out to test the effect of the Milan urban area on the convective storm. Results of all these simulations are compared with surface observations and radar data. The simulations have a similar skill, with slightly better results using the BouLac scheme coupled with BEP-BEM. Simulations using urban parametrizations are able to reproduce the pre-storm pool with low theta-e values over Milan, while no-urban simulations do not simulate the low theta-e pool.

All WRF simulations accurately reproduce the violent windstorm, both in terms of simulated wind gusts, rainfalls and radar reflectivity. Removing the city, stronger wind gusts are simulated at the surface due to the significantly reduced drag. However, rainfalls are slightly intensified downwind of the city, as well as the drop of potential temperatures associated with the downdrafts.

In conclusion, the urban canopy may have prevented the development of even more violent wind gusts in the city, due to the increased surface roughness. On the other hand, despite the presence of a pool of low theta-e values, the storm likely intensified downwind the city. A possible motivation to that intensification will be proposed in the presentation. 

How to cite: De Martin, F., Zonato, A., and Di Sabatino, S.: Can a city modify a severe convective windstorm?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17845, https://doi.org/10.5194/egusphere-egu24-17845, 2024.

EGU24-18040 | Orals | AS2.2

Linking synoptic flow and city dynamics: PANAME observations of the Paris urban boundary layer   

Simone Kotthaus, Martial Haeffelin, Jonnathan Céspedes, Jean-François Ribaud, Jean-Charles Dupont, Marc-Antoine Drouin, Pauline Martinet, and Aude Lemonsu

Atmospheric boundary layer dynamics form in response to synoptic flow and surface-atmosphere exchanges. Over cities, the complex roughness and additional heat from storage and anthropogenic emissions clearly affect atmospheric stability, with implications for heat risk and pollution dispersion. This work examines how the specific dynamics of the Paris region urban atmosphere interact with the synoptic flow using observations from a dense measurement network.

The interdisciplinary PANAME initiative is a framework coordinating the synergy of numerous projects that are studying the Paris atmosphere using both numerical modelling at various scales and novel observations. The measurement network not only includes dense surface station measurements and turbulent flux towers, but also ground-based atmospheric profile remote sensing and additional radiosonde measurements within the city. This work exploits observations from automatic lidars and ceilometers (ALC), Doppler wind lidars (DWL), and microwave radiometers (MWR) that are operated along a suburban-urban transect to collect simultaneous profiles of air temperature, wind, turbulence, and aerosol characteristics at high vertical and temporal resolution. The continuous observations from a network of compact ground-based remote sensing instruments are shown to be extremely valuable for an improved understanding of the complex processes that govern the urban atmosphere as they are highly variable in space and time.

The complex dynamics of the urban atmospheric boundary layer are explored through advanced measurement products, such as low-level jet characteristics and mixed layer heights. We evaluate how different indicators of atmospheric stability from synergy of multiple remote sensing profile data can portray the spatial and temporal variations in urban boundary layer dynamics. The work highlights the importance of atmospheric boundary layer dynamics as a crucial driver for near-surface conditions.

How to cite: Kotthaus, S., Haeffelin, M., Céspedes, J., Ribaud, J.-F., Dupont, J.-C., Drouin, M.-A., Martinet, P., and Lemonsu, A.: Linking synoptic flow and city dynamics: PANAME observations of the Paris urban boundary layer  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18040, https://doi.org/10.5194/egusphere-egu24-18040, 2024.

EGU24-18319 | ECS | Orals | AS2.2

Wind tunnel study on the influence of vegetation density and wind direction on urban canyon ventilation 

Annika Vittoria Del Ponte, Sofia Fellini, Massimo Marro, Pietro Salizzoni, and Luca Ridolfi

Inserting vegetation within the urban environment mitigates the urban heat island effect, the flooding risk, and improves air quality. However, its aerodynamic effect has remarkable impact on the pollutant transport and, consequently, on human health comfort. Indeed, the presence of vegetation within an urban canyon leads to non-trivial patterns of pollutant concentration and mass fluxes, as a consequence of complex mean and turbulent velocity fields. In addition to the vegetation density, the flow structure within canyons is influenced by their geometry and by the wind direction.

   The aim of the present study is to experimentally investigate the velocity field within a canyon, varying the vegetation density and the wind direction. We measured flow velocity statistics within an indefinitely long street canyon, with unit height-to-width ratio, subject to a neutrally stratified boundary layer modeled in the wind tunnel of École Centrale de Lyon. The aerodynamic impact of vegetation was reproduced by inserting plastic miniatures of trees along the two long sides of the canyon. We considered an empty canyon and a vegetated canyon, whose longitudinal axes are oriented with angles of 0°, 30°, and 60° with respect to the external wind flow.

  Results reveal that when the canyon is inclined with respect to the external wind direction the mean flow follows a complex helicoidal structure. The presence of trees decreases significantly the mean longitudinal velocity and weakens the transversal circulation in the inclined canyon. The dampening effect of the mean longitudinal flow is more marked increasing the inclination angle of the canyon. Turbulent fluctuations are enhanced above the tree crowns, mostly when the wind blows parallel to the canyon axis. On the contrary, turbulent fluctuations decreases at tree trunk and crown levels, in particular when the canyon is inclined of 60° with respect to the external wind direction. Spectra of the velocity signal show that the presence of trees induces an evident shift of the energy peak towards high frequencies.

  The collected data constitute a step forward to understand and modeling the urban microclimate.

How to cite: Del Ponte, A. V., Fellini, S., Marro, M., Salizzoni, P., and Ridolfi, L.: Wind tunnel study on the influence of vegetation density and wind direction on urban canyon ventilation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18319, https://doi.org/10.5194/egusphere-egu24-18319, 2024.

In this work, various very-high-resolution simulations with the Harmonie-AROME Numerical Weather Prediction (NWP) model are performed for the city of Paris during an intense heatwave event in the summer of 2022, to evaluate the capability of the model to reproduce real conditions, at various resolutions and incorporating different kinds of landuse and urban morphology types.

 

In particular, simulations are performed using ECWMF operational forecasts at 9 km resolution as boundary conditions, for the operational 2.5 km runs. Moreover, two 500 m and 100 m resolution domains have been one-way nested in the parent one.

For considering the impact of urban areas, the state-of-the-art urban canopy parameterization Town Energy Balance (TEB, Masson et al., 2000), has been employed within the modeling system, and its single-layer and multi-layer options have been compared to evaluate the improvements brought by the multi-layer capability.

 

To test the impact of various urban morphologies, simulations have been run with 1) the default ECOCLIMAP-SG landuse at 300-meter resolution, which considers urban areas as 10 different categories, derived from the WUDAPT Local Climate Zones Classification, and 2) the Geoclimate urban morphology at 100-meter resolution, derived from the Open Street Map (OSM) database (Bernard et al., 2022). The latter employs the Open Street Map database to estimate close-to-reality urban geometries, with the help of a random forest technique to estimate missing building heights in the dataset.

 

The comparison with 79  in-situ observations shows that all the simulations are able to currently represent urban air temperature trends for homogeneous areas, such as the Paris city center and compact homogeneous areas. 

On the other hand, heterogeneous and scattered urban areas temperatures are not well represented by both higher-resolution simulations and the category-based ECOCLIMAP-SG landuse.On the contrary, the OSM-based landuse is sensible to city heterogeneity and horizontal variability.

 Considering the 100-m simulations, it is clear that category-based land uses are not suitable for very-high-resolution urban canopy layer simulations, since they cannot truly capture the neighborhood-scale variation within the same city.

For this reason, it is important, with increasing NWP resolution, to employ suitable landuse datasets, coherent with the employed horizontal resolution and applicable physical parameterizations.

How to cite: Zonato, A. and Theeuwes, N.: Very-high-resolution simulations with Harmonie-AROME of a heatwave case for the city of Pari with different landuse datasets., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18500, https://doi.org/10.5194/egusphere-egu24-18500, 2024.

EGU24-18976 | ECS | Posters on site | AS2.2

Integrating Airborne LiDAR Data into Urban Flow Models: A Focus on Buildings and Trees 

Dana Lüdemann, Niels Troldborg, Jan Pehrsson, and Ebba Dellwik

Airborne LiDARs can provide updated and highly accurate information of the 3D urban layer. This presentation focuses on transforming such information into boundary conditions for urban flow models.

When addressing buildings, we use a method called City3D [1], which outputs a watertight geometrical model at a specified level of detail (LoD).This resulting model is then utilized in the computational fluid dynamics (CFD) solver EllipSys [2]. We demonstrate how a novel implementation of the immersed boundary method (IBM) [3] simulates the wind flow and dispersion around the building. Additionally, we explore how different LoD
influence the simulation results.

The LiDAR data can also be used to model the drag force of trees. We demonstrate this process based on recent observations of a real tree. Finally, we discuss the relative importance of trees and buildings in an urban modelling context, highlighting the significance of including more details in the 3D urban layer.

References
[1] Jin Huang, Jantien Stoter, Ravi Peters, and Liangliang Nan. City3d: Large-scale building reconstruction from airborne lidar point clouds. Remote Sensing, 14(9), 2022.
[2] Jess A. Michelsen. Basis3D - a Platform for Development of Multiblock PDE Solvers: - release, volume AFM 92-05. Technical University of Denmark, 1992.
[3] Niels Troldborg, Niels N. Sørensen, and Frederik Zahle. Immersed boundary method for the incompressible reynolds averaged navier–stokes equations. Computers Fluids, 237:105340, 2022.

How to cite: Lüdemann, D., Troldborg, N., Pehrsson, J., and Dellwik, E.: Integrating Airborne LiDAR Data into Urban Flow Models: A Focus on Buildings and Trees, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18976, https://doi.org/10.5194/egusphere-egu24-18976, 2024.

EGU24-19930 | Posters on site | AS2.2

Modelling the urban heat island in Birmingham, UK at the neighbourhood scale  

Jian Zhong, Yanzhi Lu, Jenny Stocker, Victoria Hamilton, and Kate Johnson

Cities have higher peak temperatures compared to surrounding rural areas. The urban-rural surface air temperature difference is known as the urban heat island (UHI). As extreme heat exposure can lead to adverse health effects, information on UHI characteristics of cities is important for future urban climate planning strategies. This study applied the ADMS-Urban Temperature and Humidity model to investigate the key processes driving the UHI in Birmingham, UK, at the neighbourhood scale. This model was configured with a range of input datasets (such as meteorological data, landuse data, building data, anthropogenic heat sources etc) and run on the University of Birmingham’s BlueBEAR HPC. This urban climate modelling was evaluated against the temperature measurement datasets from UK Met Office and Weather Underground. The spatiotemporal variations of surface air temperature in Birmingham, UK were captured by this model. This modelling study can be further applied to explore the impacts of local urban head island mitigation strategies.

How to cite: Zhong, J., Lu, Y., Stocker, J., Hamilton, V., and Johnson, K.: Modelling the urban heat island in Birmingham, UK at the neighbourhood scale , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19930, https://doi.org/10.5194/egusphere-egu24-19930, 2024.

EGU24-20040 | Posters on site | AS2.2

Dynamics and spatial distribution of air pollution over Minsk, Belarus as revealed by mesoscale and high-resolution urban WRF-Chem modelling 

Siarhei Barodka, Ilya Bruchkouski, Nikita Kasushkin, Tsimafei Schlender, Piotr Silkov, and Tatiana Tabalchuk

This study is devoted to simulation of the Urban Pollution Island (UPI) phenomena over the urban territory of Minsk, Belarus and its surrounding area. We aim at recreating the common features of the air pollution spatial distribution and its time evolution on diurnal, week-long and seasonal scales. For that purpose we utilize WRF-Chem modelling system in nested runs using BEP/BEM urban parametrization schemes for the innermost high-resolution domains (500 m, 300 m, 100 m grid step). We employ two different approaches to urban morphology representation in the model (the Local Climate Zones methodology and direct representation of some of the urban parameters on the given model grid) and use ML-processed Open Street Maps (OSM) vector data and available remote sensing data to represent land use / land cover, buildings and streets parameters for Minsk urban territory and the surrounding area. A series of model runs is performed for time periods with various cases of meteorological conditions in different seasons of recent years. Anthropogenic emissions are specified for the Minsk area as several point sources (representing industrial emissions) and distributed sources over a network of main street and roads (representing vehicle emissions). By proceeding from national statistical data with estimates of main sources of atmospheric pollution in Belarus over the recent years, we formulate hypothetical distributions of emissions intensity over the specified sources and its temporal dynamics with diurnal and weekly cycles. Simulation results obtained with different configurations of the model, different weather conditions and different emission scenarios are compared to available observations: satellite remote sensing data, ground-based observations of air quality and meteorological parameters, vertical profiles of atmospheric pollution and meteorological parameters retrieved from MAX-DOAS and sodar observations.

How to cite: Barodka, S., Bruchkouski, I., Kasushkin, N., Schlender, T., Silkov, P., and Tabalchuk, T.: Dynamics and spatial distribution of air pollution over Minsk, Belarus as revealed by mesoscale and high-resolution urban WRF-Chem modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20040, https://doi.org/10.5194/egusphere-egu24-20040, 2024.

EGU24-288 | ECS | Orals | AS3.10 | Highlight

Role of thin clouds in modulating the cloud radiative effect of marine low clouds 

Goutam Choudhury and Tom Goren

The cloud radiative effect (CRE) of low-level marine clouds has traditionally been expressed primarily as a linear function of the cloud cover. However, recent studies have revealed a substantial change in CRE even at a constant cloud cover. This change is attributed to variations in cloud morphology governed by the horizontal and vertical distribution of cloud water. A unique feature of these morphologies, especially for low marine clouds, is the occurrence of distinct quantities of optically thin clouds. Understanding the impact of these thin clouds on low-level marine CRE is crucial for two reasons. First, spaceborne studies indicate a prevalent occurrence of thin clouds in areas characterized by peak low-level cloud cover. Second, the relationship between thin clouds and CRE may differ from that of their optically thicker counterparts due to their semitransparency to incoming shortwave and outgoing longwave radiations. This study investigates the influence of thin clouds on the CRE of low-level clouds over the Southeast Pacific Ocean using six years of concurrent measurements from MODIS and CERES spaceborne sensors. The results show a substantial influence of thin clouds on the shortwave and longwave components of CRE, as well as the balance them. The findings emphasize the need for a more comprehensive representation of thin clouds and, therefore, cloud morphology in climate models.

How to cite: Choudhury, G. and Goren, T.: Role of thin clouds in modulating the cloud radiative effect of marine low clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-288, https://doi.org/10.5194/egusphere-egu24-288, 2024.

EGU24-638 | ECS | Posters on site | AS3.10 | Highlight

Aerosols enhance winter fog lifetime over North India 

Arun Nair, Chandan Sarangi, and Yun Qian

Anthropogenic aerosols affect cloud properties and change their
lifetime, a phenomenon dubbed as aerosol-cloud interactions (ACi). Radiation fog is a
surface-level cloud formed due to night-time radiative cooling of the land surface. Each year,
north India experiences several prolonged fog events. These multi-day fog episodes can
affect surface visibility and air quality, affecting human health and the transportation sector.
From long-term observations, we find that the fog duration and foggy days are enhanced
during high aerosol loading periods over north India.
However, the mechanistic role of heavy aerosol pollution on the evolution, lifetime,
and frequency of North Indian fog episodes is still poorly understood. Using chemistry-
coupled regional model simulations, we find ACi leads to fog lifetime enhancement by
producing smaller droplets and reducing the droplet deposition rate. During the daytime, the
enhanced activation of aerosols into droplets prevents evaporation from the surface.
Interestingly, during this period, the aerosol radiative effect also helps produce conducive
surface conditions to delay fog dissipation. The unequivocal role of aerosol effects on the fog
lifetime over North India suggests the urgent need to regulate particulate pollution to reduce
long periods of fog.

How to cite: Nair, A., Sarangi, C., and Qian, Y.: Aerosols enhance winter fog lifetime over North India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-638, https://doi.org/10.5194/egusphere-egu24-638, 2024.

EGU24-907 | ECS | Posters on site | AS3.10

Aerosol optical and radiative properties over Asia: Ground-based AERONET observations 

Kamran Ansari and Ramachandran Srikanthan

Aerosols continue to contribute the largest uncertainty in quantifying Earth’s climate change. The uncertainty associated with aerosol radiative forcing is found to be higher over Asia. The simulation and future projection of aerosol impact on climate may not be highly accurate over Asia due to rapid changes in aerosol emissions, limitations in simulating the observed aerosol trends, and the non-availability of regional distribution of columnar aerosol parameters based on high-quality observational datasets on a seasonal scale. For the first time, this comprehensive study examines the spatial and regional variations of aerosol columnar optical and physical properties (aerosol optical depth (AOD), fine mode fraction (FMF), and single scattering albedo (SSA)) and their associated radiative effects (aerosol radiative forcing (ARF) and heating rate (HR)) using high-quality Aerosol Robotic Network (AERONET) datasets on seasonal and annual scales over Asia. This study is performed over a total of 44 selected AERONET observational sites covering different regions of Asia, e.g., Central, South, South-East, and East Asia. AOD, ARF at the surface and in the atmosphere, and aerosol-induced atmospheric HR are observed to be the highest over South Asia, followed by South-East, East, and Central Asia in each season. SSA is found to be lower over South and Central Asia compared to South-East and East Asia. The combined influence of both fine anthropogenic aerosol emissions (e.g., carbonaceous aerosols) from biomass burning and fossil fuel combustion, and coarse mode dust aerosols from seasonal transport lead to higher AOD (0.6) and lower SSA (0.90), which overall result in higher ARF (~−70 Wm-2 at surface and 40 Wm-2 in atmosphere) and HR (0.80 Kday-1) over South Asia. South-East and East Asia are dominated by fine aerosols (higher FMF) due to higher contributions from forest fire and anthropogenic emissions, respectively, and relatively less dominance of dust aerosols compared to Central and South Asia. In addition, the seasonal aerosol optical and radiative parameters over Asia are also compared and contrasted with other regions of the globe, e.g., North America, South America, Europe, Africa, and Australia, where aerosol emissions are significantly different and mostly lower than in Asia. These findings provide observational constraints that are crucial for the improvement in model simulations for accurately assessing the radiative and climatic impacts of aerosols over a global aerosol hotspot region, Asia, where the uncertainty associated with aerosol radiative forcing is found to be higher. Details of the spatiotemporal variations in aerosol characteristics over Asia will be presented, compared and contrasted with the rest of the world, and inferences will be drawn. 

How to cite: Ansari, K. and Srikanthan, R.: Aerosol optical and radiative properties over Asia: Ground-based AERONET observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-907, https://doi.org/10.5194/egusphere-egu24-907, 2024.

EGU24-1229 | ECS | Orals | AS3.10 | Highlight

Absorbing aerosols can strongly enhance extrem precipitation 

Guy Dagan and Eshkol Eytan

Understanding the impact of anthropogenic aerosols on extreme precipitation is of both social and scientific significance. While anthropogenic absorbing aerosols are known to influence Earth's energy balance and atmospheric convection, their role in extreme events remains unclear. This study employs convective-resolving radiative-convective-equilibrium simulations to comprehensively investigate the impact of absorbing aerosols on extreme tropical precipitation. Our findings reveal an underappreciated mechanism whereby absorbing aerosols can, under certain conditions, significantly intensify extreme precipitation despite reducing the mean. Notably, we demonstrate that a mechanism previously observed in much warmer (hothouse) climates—where intense rainfall alternates with multi-day dry spells—can manifest under current realistic conditions due to the influence of absorbing aerosols. This mechanism operates when an aerosol perturbation shifts the lower tropospheric radiative heating rate to positive values, generating a strong inhibition layer. Our work underscores an additional potential effect of absorbing aerosols, with implications for climate change mitigation and disaster risk management.

How to cite: Dagan, G. and Eytan, E.: Absorbing aerosols can strongly enhance extrem precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1229, https://doi.org/10.5194/egusphere-egu24-1229, 2024.

EGU24-1773 | ECS | Orals | AS3.10

Salting out, non‑ideality and synergism enhance surfactant efficiency in atmospheric aerosols 

Manuella El Haber, Corinne Ferronato, Ludovic Fine, Anne Girroir-Fendler, and Barbara Nozière

The surface tension of sub-micron aerosol particles is expected to affect their efficiency in becoming cloud droplets. Over the last years the role of surfactants in the activation of atmospheric aerosols into cloud droplets has received a growing interest. However, most of the investigations have focused on mixtures containing only one surfactant, while the composition of atmospheric aerosol is complex. Until now, there was little experimental information on the surface properties of mixtures of surfactants with other aerosol components. In this work pendant droplet tensiometry was used to determine the adsorption isotherms and cmc of aqueous mixtures of amphiphilic surfactants (SDS, Brij35, TritonX100, TritonX114, and CTAC) with inorganic salts (NaCl, (NH4)2SO4) and soluble organic acids (oxalic and glutaric acid). Interestingly, inorganic salts and organic acids systematically enhanced the efficiency of the surfactants by further lowering the surface tension and, in some cases, the CMC. Furthermore, all the mixtures studied were strongly non-ideal, some even displaying some synergism, thus demonstrating that the common assumption of ideality for aerosol mixtures is not valid. The molecular interactions between the mixture components were either in the bulk (salting out), in the mixed surface monolayer (synergy on the surface tension) or in the micelles (synergy on the CMC) and need to be included when describing such aerosol mixtures.

Figure 1: Evolution of the minimal surface tension for mixtures of amphiphilic surfactants and organic acids (left) and two amphiphilic surfactants (right).

How to cite: El Haber, M., Ferronato, C., Fine, L., Girroir-Fendler, A., and Nozière, B.: Salting out, non‑ideality and synergism enhance surfactant efficiency in atmospheric aerosols, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1773, https://doi.org/10.5194/egusphere-egu24-1773, 2024.

EGU24-1828 | ECS | Orals | AS3.10

Long term changes in fog frequency at Swedish airports and its potential drivers 

Moa K. Sporre, Linda Hartman, Shubham Singh, and Johan Friberg

Fog can substantially impact air traffic by inhibiting or aggravating take-off or landing. This can result in large economical costs and even loss of human lives. In this study we investigate how fog frequency has changed at Swedish airports over time. The large north-south extent of Sweden with strong gradients in aerosol concentrations makes it an interesting study area for aerosol impact on fog. We base the study on visibility data from 14 airports. Most visibility data from the airports start in the 1970s but some stations have data before this and some have measurements that start in the 1980s. The visibility measurements are combined with data on air temperature, wind speed, wind direction, and air pressure from the airports. In the study we also include measurements aerosol proxies, namely SO2 in the air from 4 stations and SO42- in rainwater from 10 stations in Sweden. Moreover, emission data of SO2 from Europe from 1970 to present day has been analysed. 
The analysis shows that the fog frequency changes in Sweden vary with location of the airport. At four airports in southern Sweden, the fog frequency show a statistically significant decrease when comparing the periods before and after 1995. The most prominent changes has occurred at the airports close to Malmö and Gothenburg. The annual fog frequency for these stations changes from 5-6 % in the 1980s to 3-4 % in the 2010s with higher changes during winter. For the airports located further north there is no decrease in fog frequency. Some airports in the northern part of Sweden show a statistically significant increase in fog frequency, though the fog frequencies are lower there than in southern Sweden. 
We find that the fog frequency changes in Southern Sweden correlate well with changes in air of SO2, rainwater SO42- concentrations, which both show strong decreases since the 1970 and 1980s in southern Sweden. The changes in these concentrations are much weaker further north in Sweden. The fog frequency changes in southern Sweden thus seems to be driven by changes in the load of hygroscopic aerosol. The fog changes in northern Sweden correlate well with temperature, which is increasing at all airports. The rising temperatures in the north could contribute with more favorable conditions for fog formation at these airports where it previously was to cold for fog formation during parts of the year. Out results indicate that the work on air pollution mitigation in Europe over the past 50 years has reduced fog impact on air traffic in southern Sweden.    

How to cite: Sporre, M. K., Hartman, L., Singh, S., and Friberg, J.: Long term changes in fog frequency at Swedish airports and its potential drivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1828, https://doi.org/10.5194/egusphere-egu24-1828, 2024.

EGU24-2062 | ECS | Orals | AS3.10

Interactions of warm cloud, precipitation, and local forcings over the Great Barrier Reef: Insights from convection-permitting simulations 

Wenhui Zhao, Yi Huang, Steven Siems, Michael Manton, and Daniel Harrison

The important role of warm clouds in regulating the regional energy balance and ocean temperature, that are directly linked to the thermal coral bleaching events, has been increasingly recognised over the Great Barrier Reef (GBR). These shallow clouds, however, are by their nature sensitive to perturbations in both their thermodynamic environment and microphysical background. In this study, we employ the Weather Research and Forecasting (WRF) model with a convection-permitting configuration at 1 km resolution to examine the interactions between the warm clouds and different local forcings over the GBR. A range of local forcings including local aerosol loading, coastal topography, and sea surface temperature (SST) is examined.

Our simulations show a strong response of cloud microphysical properties, including cloud droplet number concentration (CDNC), liquid water path (LWP), and precipitation to the changes in atmospheric aerosol population over the GBR. Higher CDNC and LWP correlated to increased aerosol number concentration leads to a rise in shortwave cloud radiative effect, though the magnitude is small, over both the mountains and upwind over the GBR. While cloud fraction shows little responses, a slight deepening of the simulated clouds is evident over the upwind region in correspondence to the increased aerosol number concentration. A downwind effect of aerosol loading on simulated cloud and precipitation properties is further noted. In consideration of the coastal topography, cloud fraction and accumulated precipitation are strongly sensitive to orographic forcing over the GBR. Orographic lifting and low-level convergence are found to be crucial in explaining the cloud and precipitation features over the coastal mountains downwind of the GBR. However, clouds over the upwind ocean are more strongly constrained by the trade wind inversion, whose properties are, in part, regulated by the coastal topography. Finally, on the scales considered in our study, the warm cloud fraction and the ensuant precipitation over the GBR show only a small response to the local SST forcing, with this response being tied to the simulated cloud type.

How to cite: Zhao, W., Huang, Y., Siems, S., Manton, M., and Harrison, D.: Interactions of warm cloud, precipitation, and local forcings over the Great Barrier Reef: Insights from convection-permitting simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2062, https://doi.org/10.5194/egusphere-egu24-2062, 2024.

EGU24-2079 | Posters on site | AS3.10

Weak Aerosol Hygroscopicity Measured over the Southern Tibetan Plateau: Implication for Cloud Activation 

Yuan Wang, Jiming Li, Fang Fang, and Ping Zhang

Cloud activation over the Tibetan Plateau (TP) plays a pivotal role in regional cloud-precipitation processes and, by extension, global climate. However, its characteristics remain elusive due to the absence of observations in the TP. Leveraging the Second Tibetan Plateau Scientific Expedition and Research Program, we conducted a ground in-situ aerosol-cloud-precipitation experiment in the southern TP (GACPE-STP) from August to October 2023, thereby unveiling, for the first time, the aerosol activation characteristics in this crucial region. Our findings reveal a discernibly weak aerosol activation capacity, with mean cloud condensation nuclei number concentration (NCCN) ranging from 24 to 483 cm-3 and activation fraction from 2% to 48% at the supersaturation (SS) range from 0.07% to 0.7%. Through multi-method measurements of aerosol hygroscopicity (k), including derivation from both dry and humidified particle number size distribution (PNSD) and scattering coefficients, along with calculations based on NCCN(SS) and dry PNSD, we consistently observe low hygroscopicity with mean values below 0.1. This contrasts starkly with the recommended continental k value of 0.3, a departure that may be linked to unique surface characteristics and local fuel-usage practices in the TP region. As the dry aerosol diameter (D) increases, k exhibits an initial rise followed by a decline, adhering to a Gaussian distribution. The resulting k(D) fitting serves as a parameterization for predicting cloud activation in this region. Notably, utilizing the recommended continental κ value of 0.3 leads to a significant overestimation of cloud droplet number concentration (77% to 426%), subsequently contributing to an overestimation of cloud optical thickness and an underestimation of cloud-rain autoconversion. This cascade effect results in a substantial overestimation of the aerosol indirect effects. Employing the k(D) parameterization can significantly enhance the precision of cloud activation predictions in this region. These findings peel back a layer of mystery surrounding cloud activation in the TP region. To construct a comprehensive understanding, we advocate for additional in-situ experiments, including ice nuclei measurements, crucial for a nuanced depiction of cloud activation in the TP region.

How to cite: Wang, Y., Li, J., Fang, F., and Zhang, P.: Weak Aerosol Hygroscopicity Measured over the Southern Tibetan Plateau: Implication for Cloud Activation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2079, https://doi.org/10.5194/egusphere-egu24-2079, 2024.

EGU24-2107 | ECS | Posters on site | AS3.10

The influence of submicron sized aerosol scavenging by snow in the Cb cloud 

Darko Savic, Vladan Vuckovic, and Dragana Vujovic

In this work we have investigated the effect of aerosol particles (APs) scavenging by snow in a cumulonimbus cloud. It was shown that APs in the atmosphere have a major impact on cloud formation, development and its products, climate, environment, public health, etc. The scavenging coefficients for various snow scavenging processes were calculated, analyzed and implemented in a three-dimensional, three-moment microphysical model in which all the number concentrations and the mixing ratios, were explicitly calculated for all hydrometeor categories. Analyzing the AP scavenging coefficients we concluded that Brownian/turbulent diffusion is the dominant process for smaller diameter aerosols, up to a point, where inertial interception overpowers. Impaction scavenging is by far the most dominant process of APs scavenging by snow for particles larger than ~0.5 µm in diameter, therefore it was neglected because most of the APs injected into the cloud are of the diameter <0.2 µm. Scavenging coefficient of snow is comparable to that of raindrops or even cloud droplets, which means that APs scavenging with snow should be included in the model. Two sets of numerical experiments were conducted: (1) APs were scavenged only by cloud and rainwater and (2) APs were scavenged by cloud and rainwater and snow. No ice nucleation processes were included. The results of 3D numerical simulations showed that snow contributes more to mass than the number of AP washouts, as it collects larger particles more efficiently. As snowflakes melt into raindrops, scavenging by snow becomes a significant mechanism for removing APs from the atmosphere. Approximately 29.3% and 7.2% of the total number and mass of APs, respectively, get deposited on the ground through precipitation during a 3-hour simulation when snow does not actively collect APs. When snow collection is included in the model, the total number and mass of APs precipitated on the ground increase by 10.7% and 56.9%, giving a total of 32.4% and 11.3%, respectively.

How to cite: Savic, D., Vuckovic, V., and Vujovic, D.: The influence of submicron sized aerosol scavenging by snow in the Cb cloud, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2107, https://doi.org/10.5194/egusphere-egu24-2107, 2024.

Different cloud types have distinct radiative effects on the energy budget of the earth–atmosphere system. To better understand
the cloud radiative impacts, it is necessary to distinguish the effects of different cloud types, which can be achieved through
the cloud radar data that can provide cloud profiles for both day-to-day and diurnal variations. In this study, we use 6-year
high-temporal resolution data from the Ka-Band Zenith Radar (KAZR) at the Semi-Arid Climate and Environment Observa-
tory of Lanzhou University (SACOL) site to analyze the physical properties and radiative effects of main cloud types. The
three types of clouds that occur most frequently at the SACOL site are single-layer ice clouds, single-layer water clouds, and
double-layer clouds with the annual occurrence frequencies being 29.1%, 3.4%, and 8.3%, respectively. By using the Fu–Liou
radiative transfer model simulation, it is found that the distinct diurnal variations of both the occurrence frequency and their
macro- and micro-physical properties significantly affect the cloud-radiation. On annual mean, the single-layer ice clouds
have a positive radiative forcing of 7.4 W/m 2 to heat the system, which is a result of reflecting 12.9 W/m 2 shortwave (SW)
radiation and retaining 20.3 W/m 2 longwave (LW) radiation; while the single-layer water clouds and double-layer clouds
have much stronger SW cooling effect than LW warming effect, causing a net negative forcing of 8.5 W/m 2 . Although all
these clouds have an overall small cooling effect of 1.1 W/m 2 on the annual radiative energy budget, the significant differ-
ences of the diurnal and seasonal distributions for different type clouds can lead to distinct radiative forcing. Especially the
LW warming effect induced by the exclusive ice clouds in the cold season may have an important contribution to the rapid
winter warming over the semi-arid regions.

How to cite: Wang, M.: Radiative contributions of different cloud types to regional energy budget over the SACOL site, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2679, https://doi.org/10.5194/egusphere-egu24-2679, 2024.

EGU24-2702 | ECS | Orals | AS3.10

Exploring the Influence of Turbulence on Droplet Size Growth and Precipitation in Warm Clouds 

Shri Vignesh, Ambedkar Sanket, Arya Narayanan Unni, Srikrishna Sahu, Sachin S. Gunthe, Swetaprovo Chaudhuri, Rama Govindarajan, and Raman I. Sujith

There has been significant progress in comprehending the role of characteristic properties of aerosol in cloud droplet formation over the past decade [1]; however, the growth of cloud droplets into rain droplets, initiating precipitation in warm clouds, is still not well understood [2]. Collision and coalescence among droplets are assumed to be responsible for the rapid growth of cloud droplets to rain droplets. Turbulence is believed to play a significant role in the growth of cloud droplets [2]. 

The influence of turbulence on droplet dynamics is nominally characterized by the Stokes number, which decides if the droplet either follows the streamlines or decorrelates from it. Due to their deviation from the streamlines, droplets can form clusters and caustics, thereby increasing the chance of collisions [3]. Thus, the size distribution of droplets can determine the influence of turbulence on droplet collisions. The cloud droplet size distribution depends on several parameters, such as the initial aerosol number concentration, aerosol properties, and the in-cloud supersaturation. Thus, investigating the influence of turbulence on a given droplet size distribution can facilitate a better scientific understanding of the onset of precipitation. 

In the present study, we experimentally investigated the influence of turbulence on different cloud droplet size distributions. We generated homogeneous isotropic turbulence of various intensities in a closed chamber and seeded it with droplets relevant to that observed in clouds originating under different environmental conditions. Using Phase Doppler particle analyzer (PDPA), we measured the droplet size distributions and analyzed the changes with turbulence intensity. Our experiments show significant growth for cloud droplet size distributions with a higher degree of polydispersity than slender droplet size distributions. We attribute this enhancement in collisions to the induced relative velocity between droplets of different Stokes numbers. We observed a positive trend between clustering and droplet size growth, thus indicating the role of clustering in enhancing collisions.

Acknowledgments: We thank Dr. Amit Kumar Patra and Dr. T. Narayana Rao for their valuable suggestions. We acknowledge the ISRO-IITM cell (No. SP/21-22/1197/AE/ISRO/002696) and  IoE initiative (SP22231222CPETWOCTSHOC) for funding this work. 

References:

[1] Gunthe, S.S., King, S.M., Rose, D., Chen, Q., Roldin, P., Farmer, D.K., Jimenez, J.L., Artaxo, P., Andreae, M.O., Martin, S.T. and Pöschl, U., 2009. Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity. Atmospheric Chemistry and Physics, 9(19), pp.7551-7575.

[2] Devenish, B.J., Bartello, P., Brenguier, J.L., Collins, L.R., Grabowski, W.W., IJzermans, R.H.A., Malinowski, S.P., Reeks, M.W., Vassilicos, J.C., Wang, L.P. and Warhaft, Z., 2012. Droplet growth in warm turbulent clouds. Quarterly Journal of the Royal Meteorological Society, 138(667), pp.1401-1429.

[3] Ravichandran, S. and Govindarajan, R., 2015. Caustics and clustering in the vicinity of a vortex. Physics of Fluids, 27(3).

How to cite: Vignesh, S., Sanket, A., Narayanan Unni, A., Sahu, S., S. Gunthe, S., Chaudhuri, S., Govindarajan, R., and I. Sujith, R.: Exploring the Influence of Turbulence on Droplet Size Growth and Precipitation in Warm Clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2702, https://doi.org/10.5194/egusphere-egu24-2702, 2024.

Anthropogenic aerosols and their interactions with clouds play a crucial role in regulating the Earth's radiation balance and introduce significant uncertainties in climate change projection. The effective radiative forcing due to aerosol-cloud interactions (ERFaci) is particularly difficult to quantify, leading to uncertainties in model projections of cloud feedback and climate sensitivity. Analysis of CMIP6 model simulations indicate that models with a strongly-positive cloud feedback tend to be offset with strongly negative ACI, leading to similar projections of global mean temperatures during the historical period. However, because anthropogenic aerosol primarily occur in the Northern Hemisphere, the hemispheric asymmetry in warming (NH-SH) differs significantly between low and high ACI models, with observed trends being more consistent with low ACI (weak cloud feedback) models. However, recent satellite estimates of ERFaci based on cloud controlling factors (CCF) is more consistent with high ACI models.  We evaluate the CCF approach using a series of perfect model experiments. The magnitude of ERFaci depends on two factors: the amount of aerosol loading between the pre-industrial and present day, and the susceptibility of cloud albedo and cloud lifetime to that aerosol loading. By comparing observationally-constrained estimates of ERFaci with CMIP6 model simulations, we quantify the contributions of aerosol loading differences and cloud susceptibility to the inter-model spread. We find that explicitly accounting for the role of aerosol activation on cloud droplet formation is essential to obtaining accurate estimates of ERFaci, and when this is done, the satellite constrained estimates of ERFaci are more consistent with low ACI models.

How to cite: soden, B. and park, C.: Reconciling Top-Down and Bottom-Up Estimates of the Effective Radiative Forcing from Aerosol-Cloud Interactions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3278, https://doi.org/10.5194/egusphere-egu24-3278, 2024.

EGU24-3659 | Posters on site | AS3.10

The effects of ice nucleation parameterizations in GFDL climate model  

Huan Guo and Songmiao Fan
We incorporated a temperature, dust, and sea spray aerosol-dependent ice nucleation parameterization in the recently developed GFDL AM4-MG2 framework, and refer to this new configuration as AM4-MG2-new. The major difference of the ice nucleation parameterizations in AM4-MG2-new and AM4-MG2 is the inclusion of sea spray aerosol as ice nucleating particles (INPs). Then we conducted AMIP (Atmospheric Model Intercomparison Project) mode simulation with AM4-MG2-new. It turns out that AM4-MG2-new produces mean model climate comparable to AM4-MG2, for example, similar cloud radiative and precipitation fields, but different cloud water phase partitioning or supercooled cloud fractions, especially over the mid-high latitudes where mixed-phase clouds (clouds that consist of both liquid and ice) are prevalent. The cloud-phase feedback could in turn impact the estimate of climate sensitivity. The results suggest that ice nucleation parameterizations, which have large uncertainties, have important impacts on climate sensitivity.

How to cite: Guo, H. and Fan, S.: The effects of ice nucleation parameterizations in GFDL climate model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3659, https://doi.org/10.5194/egusphere-egu24-3659, 2024.

EGU24-3924 | ECS | Posters on site | AS3.10

Impact of biomass burning emission variability on precipitation over tropical oceans 

Xiaoyan Zhang, Xiyan Xu*, Gensuo Jia, and Yue Liang

Numerical simulations mostly constrain the total amount of biomass burning aerosols but rarely prescribe the realistic emission variability. Ignoring high heterogeneity of emission variability may lead to uncertainties in climate projections. Based on the Community Earth System Model version 2 Large Ensemble Community Project (CESM2-LE), we investigated the impact of interannual variability of biomass burning emissions on tropical precipitation and extremes. Our results revealed that global carbonaceous aerosol emission was 180-320 Tg over the period 1990-2020. Tropical regions (30°S-30°N) had the largest emission flux and variability. Higher interannual variability triggered increasing precipitation and extremes in tropics where spatial heterogeneity of precipitation anomalies can be detected. More precipitation and northward ITCZ shift occurred in central and western Pacific Oceans, while precipitation reduction together with southward ITCZ rain-belt over eastern Pacific and Atlantic Basins. The asymmetries were attributable to weakened Walker circulation and its uplifting branch tilted toward the Southern hemisphere. Correspondingly, nonlinear aerosol-cloud interactions increased (reduced) the total and high cloud cover over the southern central-western Pacific (eastern Pacific and Atlantic) Oceans. Convective activities were then strengthened (weakened) due to lower (higher) outgoing longwave radiation at top of atmosphere, which drove the cross-equatorial heat transport variations, and ultimately led to southward (northward) shift of ITCZ. Our results revealed the synergistic mechanisms between biomass burning emission variability, radiation and cloud characteristics, and large-scale circulation modes, thereby gaining new insights into the tropical hydrological cycle.

How to cite: Zhang, X., Xu*, X., Jia, G., and Liang, Y.: Impact of biomass burning emission variability on precipitation over tropical oceans, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3924, https://doi.org/10.5194/egusphere-egu24-3924, 2024.

EGU24-4059 | Posters on site | AS3.10

Cloud Susceptibility to Aerosols: Comparing Cloud-Appearance vs. Cloud-Controlling Factors Regimes 

Yannian Zhu, Jihu Liu, Minghuai Wang, and Daniel Rosenfeld

Clouds can be classified into regimes by the cloud appearance or by the cloud meteorological controlling factors. The cloud appearance regimes inherently include adjustments to aerosol effects, such as transitions between closed and open cells. Therefore, aggregation of cloud susceptibilities to aerosols over the cloud-appearance regimes excludes much of the cloud adjustment component of the susceptibilities. In contrast, aggregating susceptibilities over regimes defined by cloud-controlling factors includes the full effects of cloud adjustments. Here we compared the susceptibilities of the two kinds of cloud regimes and demonstrated this effect. Overall, increasing cloud droplet number concentration (Nd) consistently leads to precipitation suppression, higher cloud fraction (CF), and reduced liquid water path (LWP), regardless of how the regime is defined. However, their susceptibilities to Ndaggregated over cloud-appearance regimes are significantly lower than those aggregated over cloud-controlling factors regimes, with lower-tropospheric stability (LTS) serving as an example to define cloud-controlling factors regimes. This underestimation is more pronounced for CF susceptibility, where the susceptibility for cloud appearance regimes is only 1/4 of the susceptibility for cloud controlling regimes. These findings imply that relying solely on cloud-appearance regimes may underestimate the effective radiative forcing produced by cloud adjustment (ERFaci). Nevertheless, the substantial variability in the magnitude of cloud adjustment across appearance regimes at similar LTS also suggests that a single cloud-controlling factor is not sufficient to fully separate cloud regimes to quantify cloud adjustment. Therefore, identifying a comprehensive set of cloud-controlling factors is essential for accurately quantifying cloud adjustments in future studies.

How to cite: Zhu, Y., Liu, J., Wang, M., and Rosenfeld, D.: Cloud Susceptibility to Aerosols: Comparing Cloud-Appearance vs. Cloud-Controlling Factors Regimes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4059, https://doi.org/10.5194/egusphere-egu24-4059, 2024.

EGU24-4329 | ECS | Posters virtual | AS3.10 | Highlight

Comparing ML retrieved and invisible ship tracks to probe the meteorological dependence of cloud susceptibility to aerosol 

Peter Manshausen, Duncan Watson-Parris, and Philip Stier

Aerosol-cloud interactions continue to resist reliable quantification, partly owing to their strong dependence on cloud and weather regimes. For a long time, opportunistic experiments such as ship tracks have been used to overcome issues of confounding. Recent advances leverage (i) Machine Learning (ML) to drastically enlarge ship track data bases, and (ii) ‘invisible ship tracks’, found by advecting ship emissions, to overcome selection biases in ship track studies. Here, we combine both approaches, to advance our understanding of how meteorology controls cloud responses to aerosol emissions. Firstly, we show that even though the ML dataset is much larger than previous hand-logged data sets, it still contains only a fraction of less than 1% of the cloud regions polluted by shipping. This means less than 1% of ship tracks are visible. Secondly, we find that this fraction varies strongly with location and season, with the Southern Hemisphere winter leading to most visible tracks in the Stratocumulus regions of the SE Pacific and SE Atlantic. Thirdly, we identify meteorological regimes favourable to the visibility of tracks, using ML methods such as Random Forests and Explainable AI, alongside traditional methodsThe regime favourable to visible tracks is defined by a stable lower troposphere and little vertical movement, low sea surface temperatures, high cloud cover, and low boundary layer heights. Lastly, we quantify the link between ship track visibility and albedo change in polluted clouds, establishing to what extent days with visible tracks are those when cloud albedo is most susceptible to aerosol. Building on this relationship, a predictive model like our Random Forest has applications in deliberate Marine Cloud Brightening by predicting the days that are most susceptible to aerosol perturbations.

How to cite: Manshausen, P., Watson-Parris, D., and Stier, P.: Comparing ML retrieved and invisible ship tracks to probe the meteorological dependence of cloud susceptibility to aerosol, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4329, https://doi.org/10.5194/egusphere-egu24-4329, 2024.

EGU24-4358 | ECS | Orals | AS3.10

Ice-nucleating particles in springtime cold-air outbreaks associated with Arctic haze 

Erin Raif, Sarah Barr, Mark Tarn, James McQuaid, Martin Daily, Steven Abel, Paul Barrett, Keith Bower, Paul Field, Kenneth Carslaw, and Benjamin Murray

Concentrations of ice-nucleating particles (INPs) were measured in springtime cold-air outbreaks over the Norwegian and Barents Seas using filter samples taken on board the FAAM BAe-146 aircraft. These measurements of INP concentrations were comparable to the highest INP concentrations previously observed in the Arctic and were similar to typical terrestrial midlatitude INP concentrations. This is important because shallow cloud systems such as those in mid- to high-latitude cold-air outbreaks are highly sensitive to INPs and are a highly uncertain contributor to cloud feedbacks. 

To investigate the types of aerosol responsible for this high INP concentration, we used aerosol-size data from underwing optical probes to derive an active site density of the INP samples. By comparing to laboratory derived active site densities of different aerosol types, this suggested that sea spray was unlikely to be a dominant INP type and that there were likely to be strong biological and dust components to the INP population. Scanning electron microscopy with energy-dispersive spectroscopy used on selected filters revealed that sub-micron particles were dominantly sulphates and carbonaceous, while super-micron particles were dominantly mineral dust.

Samples taken above the cloud decks had greater active site densities than those below, and back-trajectory analysis and meteorological conditions suggested a lack of obvious local INP sources. We hypothesise that the high INP concentration is most likely to be associated with aged aerosol that has accumulated over the Arctic (Arctic Haze).  These high INP concentrations imply that these clouds may have a more negative cloud-phase feedback than their Southern Ocean equivalents.

How to cite: Raif, E., Barr, S., Tarn, M., McQuaid, J., Daily, M., Abel, S., Barrett, P., Bower, K., Field, P., Carslaw, K., and Murray, B.: Ice-nucleating particles in springtime cold-air outbreaks associated with Arctic haze, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4358, https://doi.org/10.5194/egusphere-egu24-4358, 2024.

Sea spray aerosols (SSA) play a crucial role as a primary aerosol source on a global scale, exerting significant influence on the Earth's radiative balance. Variations in sea water composition and concentrations across different regions can introduce disparities in sea spray aerosol properties. This study focuses on investigating and comparing the hygroscopicity of artificial sea salt particles and nascent sea spray aerosols from offshore waters and open sea areas within the Pacific Ocean. An aerosol optical tweezer (AOT) system is developed to measure the diameter hygroscopic growth factor (GF) and the hygroscopicity parameter (κ) of both artificial sea salt and natural sea spray aerosol particles. Our findings indicate that the hygroscopic properties of supermicron sea spray aerosols from offshore waters and open sea areas are remarkably similar and can be effectively represented by artificial sea salt particles. Furthermore, through the application of the theoretical Zdanovskii, Stokes, and Robinson (ZSR) mixing rule, the calculated κ values reinforce the validity of our aerosol optical tweezer measurements. Hence, we propose that, for modeling supermicron sea spray aerosol particles produced in either offshore waters or open sea areas, the properties of artificial sea salt particles, rather than NaCl particles, serve as robust proxies for natural sea spray aerosols. To be specific, we recommend utilizing a κ value of 1.20, for modeling sea spray aerosol properties at a relative humidity of 90% (RH=90%). This empirically derived κ value, rooted in our study, can enhance the accuracy of climate models and contribute to a more precise understanding of aerosol-climate interactions.

 

How to cite: Qiu, J. and Zhao, C.: Hygroscopic Behavior of Sea Spray Aerosols in Offshore Waters and Open Sea Areas Investigated with Aerosol Optical Tweezers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4957, https://doi.org/10.5194/egusphere-egu24-4957, 2024.

EGU24-4997 | ECS | Posters on site | AS3.10

A Comprehensive Method to Unveiling Uncertainty in Multi-Factor Systems 

Bishuo He and Chunsheng Zhao

The accurate assessment of influencing factors in multi-factor systems is crucial, but current methodologies face challenges in evaluating uncertainty comprehensively. In aerosol radiative forcing, existing methods may lack completeness, potentially leading to erroneous conclusions. This study introduces a universally applicable method for precise sensitivity analysis of influencing factors in multi-factor systems. Two measurement dimensions for sensitivity analysis methods are established: accurately expressing sensitivity and quantifying sensitivity. Combined utilization of different methods allows for a comprehensive analysis. The proposed method can simultaneously express and quantify sensitivity, including the analysis of nonlinear components unaffected by the absence of factors. In a sensitivity analysis on aerosol optical parameters, the aerosol shell complex refractive index (CRI_shell) emerges as the most sensitive factor. Calculations reveal substantial variability (5% to 91%) in the proportion of nonlinear components resulting from factor interactions. This emphasizes the importance of employing methods resistant to nonlinear influences, as susceptible methods may introduce significant biases. The proposed sensitivity analysis facilitates factor importance assessment at three levels: primary and secondary factors, sensitivity ranking, and quantified sensitivity. This method exhibits universality and holds promising prospects for practical applications in the field. Results provide a valuable reference for future model parameter settings and routine observations.

How to cite: He, B. and Zhao, C.: A Comprehensive Method to Unveiling Uncertainty in Multi-Factor Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4997, https://doi.org/10.5194/egusphere-egu24-4997, 2024.

EGU24-5189 | Posters on site | AS3.10

Large-eddy simulations of the stratocumulus to cumulus transition in the Northeast Pacific using ICON 

Moritz Schnelke, Maike Ahlgrimm, and Anna Possner

The Northeast Pacific stratocumulus deck is one of the well-known subtropical semipermanent stratocumulus decks that transitions into shallow cumuli along the sea surface temperature gradient away from the Californian coast line. In this study we use observational data from the Marine ARM GPCI Investigation of Clouds (MAGIC) ship campaign to evaluate stratocumulus to cumulus transitions (SCTs) in idealised large-eddy simulations (LESs) with the ICOsahedral Nonhydrostatic Model (ICON). The simulations are conducted with a horizontal resolution of 50 m and a vertical resolution of at most 10 m in the lowest 3 km of the atmosphere. 
From previous studies of SCTs, including MAGIC and in particular Leg15A, it is well known that entrainment processes drive an important, and likely dominant role in forcing the transition. However, recent studies have shown that microphysical effects like sedimentation or precipitation can significantly alter the course of the SCT. Suppressed precipitation through a higher number of cloud droplets often leads to a delayed SCT. On the other hand, this is counteracted by the associated increase in entrainment, which benefits the transition. This raises the question of the mechanism of this interaction and the overall strength of microphysical effects. 
Here we present the evaluation of ICON LES and the characterisation of nine selected transitions from the MAGIC campaign, including the well analysed Leg15A. 

How to cite: Schnelke, M., Ahlgrimm, M., and Possner, A.: Large-eddy simulations of the stratocumulus to cumulus transition in the Northeast Pacific using ICON, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5189, https://doi.org/10.5194/egusphere-egu24-5189, 2024.

This study investigates the relationship between aerosols and cloud properties in the South Asian monsoon over two decades, using satellite data. We conducted a 20-year analysis of aerosols and diverse cloud properties during the monsoon months. Precipitation patterns were categorized into high and low years based on anomalies. Significant correlations emerged between aerosol optical depth (AOD) and cloud properties, including cloud fraction, cloud droplet size, cloud top features, column-integrated water vapor, ice water path, and liquid water path. AOD and cloud fraction showed positive correlations, though not always translating to increased precipitation, underlining the role of cloud microphysics. AOD influenced cloud droplet size differently across regions, with some showing smaller droplets with higher AOD. Cloud height, temperature, and reflectivity were affected by AOD, indicating its influence on cloud properties through droplet concentration. Column-integrated water vapor positively correlated with AOD, implying aerosol involvement in water vapor condensation into cloud droplets. These findings uncover the intricate regional dynamics of aerosol-cloud interactions during the South Asian monsoon, offering valuable insights into the delicate relationships between aerosols, cloud properties, and precipitation variations across the diverse landscape of South Asia. This underscores the significance of considering regional variations in aerosol-cloud interactions when evaluating their impact on South Asian monsoon systems.

How to cite: Khattak, P., Cermak, J., Fatima, S. H., and Fuchs, J.: Spatiotemporal Impacts of Aerosols on Cloud Properties and Precipitation Patterns in South Asian Monsoon Region: Contrasting High and Low Precipitation Years., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5454, https://doi.org/10.5194/egusphere-egu24-5454, 2024.

EGU24-5460 | Orals | AS3.10 | Highlight

Aerosol size distribution variability over the Southern Ocean: implications for cloud droplet number concentrations 

Julia Schmale, Athanasios Nenes, Iris Thurnherr, Silvia Henning, Christian Tatzelt, Andrea Baccarini, and Martin Gysel-Beer

The Southern Ocean is a key component of the climate system, where clouds especially matter. Therefore, it is important to correctly simulate clouds in climate models. Even though there has been substantial improvement, climate models still struggle in their representation of cloud microphysical properties.

In this study, based on data from the Antarctic Circumnavigation Expedition in 2026/17, we explore environmental factors, such as stable water isotopes in atmospheric water vapor, cyclones and boundary layer stability, that influence the abundance of aerosols and their size distribution, the most important variables for particles to act as cloud condensation nuclei (CCN), along a latitudinal gradient from 35°S to 75°S. Moreover, we use a cloud parcel model to estimate the cloud droplet number concentration and cloud maximum supersaturation (SS) based on the particles’ size distribution, hygroscopicity and measured updraft velocities.

Based on the latitudinal gradient of observed CCN, which features a distinct minimum around 60°S, and the carbon monoxide mixing ratios, which reach background levels south of 60°S indicating absence of anthropogenic influence, we compare aerosol properties north and south of this latitude. The northern aerosol population features two distinct Aitken modes, a nucleation mode and a mode with a Hoppel minimum around 60 nm. The presence of cyclones reduces the particle number concentrations over all diameters. We also observe a stronger Aitken mode presence in unstable boundary layer conditions, where downward mixing of freshly formed particles in the outflow of clouds in the free troposphere can occur. The southern population features only three modes, a nucleation mode and two distinct bimodal distributions with Hoppel minima around 70 nm. Only in stable boundary layer conditions an Aitken mode emerges in the 75th percentile that is larger in particle number than the accumulation mode, pointing towards a potential source of condensable vapors from the ocean surface that grow the Aitken mode, leading to observably higher kappa values. The Aitken mode is further associated with air masses with relatively less depletion in d18O, pointing towards a marine source further north.

The cloud droplet number concentration simulations feature the same latitudinal pattern as the measured CCN with the “dip” around 60°S. This is consistent with droplet observations from satellites. Interestingly, the simulated cloud maximum SS tends to increase with latitude, from roughly 0.27% at 40°S towards 0.43% at 75°S. To estimate the sensitivity of clouds towards available aerosol particles, we form the ratio of the particle number concentration larger than the observed Hoppel minimum over the simulated cloud droplet number concentrations. We find that clouds north and south of 60°S experience elevated sensitivity (ratio < 1) to aerosol concentrations in 23 % and 27 % of the time, respectively. This demonstrates that the Southern Ocean cloud regime is indeed sensitive to aerosol number and size distributions, which in turn are influenced by synoptic features (e.g., cyclones) and marine boundary layer stability. On the other hand, frequent occurrence of low SS, demonstrates that cloud formation is also often updraft limited.

How to cite: Schmale, J., Nenes, A., Thurnherr, I., Henning, S., Tatzelt, C., Baccarini, A., and Gysel-Beer, M.: Aerosol size distribution variability over the Southern Ocean: implications for cloud droplet number concentrations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5460, https://doi.org/10.5194/egusphere-egu24-5460, 2024.

EGU24-5996 | ECS | Orals | AS3.10

Coupled 3D radiation deepens cumulus clouds without changing the mean surface solar irradiance 

Mirjam Tijhuis, Bart van Stratum, and Chiel van Heerwaarden

Most atmospheric models consider radiative transfer only in the vertical direction (1D), as 3D radiative transfer calculations are too costly. Thereby, horizontal transfer of radiation is omitted, resulting in incorrect surface radiation fields. Previous work on 3D radiative effects mainly used uncoupled 3D radiative transfer. In our current work, we study the impact of coupled 3D radiative transfer on the development of clouds, and the resulting impact on the domain average surface solar irradiance.

We performed a series of realistic Large-Eddy simulations with MicroHH. We developed the option to use aerosol data from the CAMS global reanalysis to include the interactions between aerosols and radiation in our LES simulations. This makes sure our simulated radiation is in line with observations. To investigate the impact of 3D radiative transfer, we selected 12 days on which shallow cumulus clouds formed over Cabauw, the Netherlands. For each day, we performed simulations with 1D radiative transfer and with a coupled ray-tracer. The simulations with the coupled ray-tracer also include the results of uncoupled 1D radiative transfer. This allows us to compare the differences between 1D and 3D radiative transfer when the clouds are the same.  

In general, our simulations with coupled 3D radiative transfer have a higher domain average liquid water path compared to our simulations with coupled 1D radiative transfer. The cloud cover is similar in both simulations, but the cloud size is increased in the simulations with coupled 3D radiative transfer. For the domain average radiation, we find that 3D radiative transfer in general decreases the direct radiation and increases the diffuse radiation, but the net effect is on average less than 1 W m-2. We can explain the differences in radiation when we look separately at the direct and diffuse radiation, the uncoupled 3D effects, and the impact of the change in the clouds. The uncoupled effect of 3D radiative transfer is an increase in global radiation, which is counteracted by a decrease is global radiation caused by the change in clouds.

How to cite: Tijhuis, M., van Stratum, B., and van Heerwaarden, C.: Coupled 3D radiation deepens cumulus clouds without changing the mean surface solar irradiance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5996, https://doi.org/10.5194/egusphere-egu24-5996, 2024.

EGU24-6013 | Posters on site | AS3.10

Determining the influence of fluorescent primary biological aerosol particles on low-level Arctic clouds 

Paul Zieger, Gabriel Pereira Freitas, Ben Kopec, Kouji Adachi, Radovan Krejci, Dominic Heslin-Rees, Karl Espen Yttri, Alun Hubbard, and Jeffrey M. Welker

Mixed-phase clouds are integral to the Arctic climate system as they regulate the energy transport to and from the surface. Their ice content, which influences the cloud's optical and physical properties, is regulated by the presence of ice nucleating particles (INP).  Despite this, knowledge of the sources and concentrations of INP in the Arctic is notably lacking.  Here, we investigate the abundance and variability of fluorescent primary biological aerosol particles (fPBAP) within cloud residuals at a key site at 79° North over an entire year. fPBAP have been found to be active INP at warmer temperatures. Samples were continuously collected using a multiparameter bioaerosol spectrometer coupled to a ground-based counterflow virtual impactor inlet at the Zeppelin Observatory in Ny-Ålesund, Svalbard. We found that fPBAP concentrations within cloud residuals closely aligned with the expected concentration of high-temperature INP. Transmission electron microscopy confirmed the presence of fPBAP, likely bacteria, in the cloud residual samples. Seasonal analysis demonstrated a higher presence of fPBAP within cloud residuals over the summer, with water vapor isotope measurements revealing a connection between summer cloud formation and regionally sourced air masses. Low-level MPC were predominantly observed at the beginning and end of summer, possibly due to the presence of high-temperature INP. Our study - currently under interactive discussion* - provides observational evidence supporting the role of fPBAP in determining the phase of low-level Arctic clouds, with implications for the composition of respective cloud condensation nuclei sources in the future under rapid Arctic climate and environmental change.

*Pereira Freitas, G., Kopec, B., Adachi, K., Krejci, R., Heslin-Rees, D., Yttri, K. E., Hubbard, A., Welker, J. M., and Zieger, P. 2023: Contribution of fluorescent primary biological aerosol particles to low-level Arctic cloud residuals, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-2600.

How to cite: Zieger, P., Pereira Freitas, G., Kopec, B., Adachi, K., Krejci, R., Heslin-Rees, D., Yttri, K. E., Hubbard, A., and Welker, J. M.: Determining the influence of fluorescent primary biological aerosol particles on low-level Arctic clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6013, https://doi.org/10.5194/egusphere-egu24-6013, 2024.

EGU24-6816 | ECS | Orals | AS3.10

Observations of ambient aerosol and warm cloud formation in a New Mexico summer deep-convection system 

Huihui Wu, Nicholas Marsden, Paul Connolly, Michael Flynn, Paul Williams, Graeme Nott, Kezhen Hu, Declan Finney, Navaneeth Thamban, Keith Bower, Alan Blyth, Thomas Choularton, Martin Gallagher, and Hugh Coe

Aerosol particles can affect the formation and properties of clouds by acting as cloud condensation nuclei (CCN) and ice nucleating particles (INP). The accurate representation of aerosol size distribution and composition along with cloud nucleating properties play an important role in describing aerosol-cloud interactions. The Deep Convective Microphysics Experiment (DCMEX) is a project aimed at improving the representation of microphysical processes in deep convective clouds. The DCMEX campaign (July to Aug 2022) was conducted using the UK FAAM (Facility for Airborne Atmospheric Measurements) BAe-146 Atmospheric Research Aircraft and characterized the aerosol-cloud system over the isolated Magdalena Mountain region in New Mexico. The aircraft was equipped with a range of online instruments to measure aerosol chemical composition (i.e., Aerosol Mass Spectrometry, AMS; Laser Ablation Aerosol Particle Time of Flight mass spectrometry, LAAPToF) and aerosol size distributions, as well as cloud microphysics.

A 6-days backward dispersion analysis of this region shows that the air source flow transferred from Northwest (NW, California coast) to Southeast (SE, Gulf of Mexico) during the campaign period. This air mass source change coincided with changes in meteorological parameters including such as enhancement of convection available potential energy (CAPE), decreased cloud-base height, and increased boundary layer humidity. The aerosol size distribution and chemical composition in out-of-cloud runs also show variations under different air mass source conditions. Larger sulphate and lower organic contributions were observed in the sub-micron (<1 μm) aerosol mass fraction in the SE airflow when compared to flow from the NW, with the organic components more oxidized. The LAAPToF single particle measurements (0.5-2.5 μm) indicate more aged sea salt in number fraction within the SE ocean flow. The calculated kappa values suggest more hygroscopic aerosols with the source transfer. Number size distributions indicate enhanced Aiken-mode particles when the air mass source changed.

A bin-microphysics model was employed to simulate the warm cloud development in this convective system. The simulation results show that both the change of aerosol characteristics and cloud-base conditions affect the warm cloud development, which follow the trends seen in the cloud microphysics observations. Initial cloud base conditions (i.e., initial temperature and relative humidity) mainly affected cloud properties by altering the water mixing ratios while aerosol characteristics mainly affected the initial cloud droplet number concentrations.

Next, we will combine these online aerosol measurements with detailed cloud microphysical measurements and offline INP analysis, to investigate the contributory effect of aerosols on primary ice formation in this deep-convection system and their relationship to secondary ice production processes.

How to cite: Wu, H., Marsden, N., Connolly, P., Flynn, M., Williams, P., Nott, G., Hu, K., Finney, D., Thamban, N., Bower, K., Blyth, A., Choularton, T., Gallagher, M., and Coe, H.: Observations of ambient aerosol and warm cloud formation in a New Mexico summer deep-convection system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6816, https://doi.org/10.5194/egusphere-egu24-6816, 2024.

EGU24-6913 | ECS | Posters on site | AS3.10

Hysteresis in water content of ultrafine glassy organic aerosols: Evidence from laboratory and modelling study 

Manqiu Cheng, Mikinori Kuwata, and Ying Li

Water content of aerosol particles is important for atmospheric impacts, such as radiative effects and chemical reactivity. Traditionally, crystalline inorganic aerosol particles such as NaCl were known to experience hysteresis in water content, meaning that hygroscopic growth depends on exposure history to water vapor. On the contrary, past laboratory studies for organic aerosol reported absence of hysteresis, especially for ultrafine size range. Here, we show that water contents for ultrafine organic aerosol particles have hysteresis at sub-0 °C. Hygroscopic growth of monodisperse ultrafine particles (diameter = 40, 100, and 200 nm) of sucrose and glucose were investigated for the temperature range of -21 °C to +23 °C. Hygroscopic growth of these particles did not exhibit any hysteresis process at +23 °C, consistent with literature. However, hygroscopic growth of these particles was different for hydration and dehydration experiments at sub-0 °C, demonstrating the occurrence of hysteresis. The lowest relative humidity (RH), at which the two modes of experiments provided the same water content, was defined as merge RH. Merge RH was approximately the same as that for the glass transition point, demonstrating that water diffusion in a highly viscous matrix of organic aerosols is the key for the occurrence of hysteresis. Employment of a kinetic multilayer model provided quantitative prediction of merge RH as a function of temperature, particle size, and residence time. Considering the temperature and RH range of Earth’s atmosphere, we hypothesize that hysteresis in organic aerosol ubiquitously occur in the upper troposphere.

How to cite: Cheng, M., Kuwata, M., and Li, Y.: Hysteresis in water content of ultrafine glassy organic aerosols: Evidence from laboratory and modelling study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6913, https://doi.org/10.5194/egusphere-egu24-6913, 2024.

The lifetime of clouds has an important influence on radiation balance, atmospheric matter cycling, and global precipitation patterns. However, current assessments of cloud lifetime rely on statistical methods, underscoring the need for effective observational techniques. Moreover, existing research predominantly centers on precipitation removal, neglecting the process of cloud dissipation.Utilizing optical tweezers-Raman spectroscopy technology and CCD real-time imaging, this study conducts experiments on the evaporation of individual suspended droplets with a series of concentration gradients. We establish a method for quantifying the evaporation time of microdroplets, and characterize their evaporation dynamics through the temporal variation of OH-stretching Raman peak. Our research reveals the substantial influence of droplet solute concentration on evaporation time, indicating that even minute variations in solute concentration within cloud droplets can induce profound disparities in their lifetime.Furthermore, alterations in environmental relative humidity also have an impact on the dissipation of cloud droplets. These findings hold critical scientific significance, enhancing our understanding of cloud lifetime and providing a scientific foundation for accurately simulating cloud generation and dissipation processes in numerical models.

How to cite: Guo, S. and Zhao, C.: Advancing Cloud Science: Exploring the Lifetime of Indiviual Cloud Droplets through Aerosol Optical Tweezers and Raman Spectroscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7092, https://doi.org/10.5194/egusphere-egu24-7092, 2024.

EGU24-7148 | ECS | Posters on site | AS3.10

Probing pH of Particle in HCO3-/CO32- System through Optical Tweezers Coupled with Raman Spectroscopy 

Chengyi Fan and Chunsheng Zhao

Acidity stands as a pivotal physicochemical parameter influencing aerosol particles, impacting their morphology and environmental interactions, such as phase separation and the formation of secondary organic aerosols. However, directly measuring particles pH remains a challenge, necessitating urgent exploration. This study utilizes optical tweezers to investigate and compare methods for measuring pH of particle. Initial steps involved preparing a solution with sodium carbonate and sodium bicarbonate system, followed by measurement of ion concentration calibration curves for HCO3- and CO32-. Droplets were then generated using an atomizer and prepared solution. A single-beam Gaussian optical tweezers captured individual particles and obtained their Raman spectra in conjunction with a Raman spectrometer. Four methods—Henderson-Hasselbalch equation, Debye-Hückel theory, specific ion interaction theory, and thermodynamic model—were then applied to calculate pH values based on HCO3-/CO32- conjugate acid/base pairs and ion concentration calibration curves. The experimental results demonstrated small error in each calculated pH value. Additionally, the study revealed a rapid decomposition process of HCO3- in droplets, possibly attributed to the high specific surface area of small droplets or the absence of CO2 in the optical tweezers chamber. The study also monitored the evolution of pH values in sodium bicarbonate particles over time. Furthermore, the study investigated difference in pH values calculated by the four calculation methods under different ion strengths and pH values. The study also measured the pH value of sodium carbonate particles in relation to relative humidity. Overall, the experimental outcomes were reasonable and validated the capability of optical tweezers in probing the pH of atmospheric particles, offering insights into the applicable conditions of different methods and directions for refining thermodynamic models.

 

How to cite: Fan, C. and Zhao, C.: Probing pH of Particle in HCO3-/CO32- System through Optical Tweezers Coupled with Raman Spectroscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7148, https://doi.org/10.5194/egusphere-egu24-7148, 2024.

EGU24-8451 | ECS | Posters on site | AS3.10

Comparison between model and observational cloud fraction adjustment using explainable machine learning 

Yichen Jia, Hendrik Andersen, and Jan Cermak

This ongoing study uses machine learning to quantify and compare observation- and global climate model-based sensitivities of cloud fraction (CF) for marine boundary layer clouds (MBLCs) to atmospheric aerosols. In addition, differences in the meteorological influence on these sensitivities between the model and observation are examined.

Aerosol-cloud interactions in MBLCs remain one of the most substantial sources of uncertainties in climate simulations. Recent studies have reported that climate forcing from an increase in low-level liquid cloud fraction due to aerosol perturbations may be dominant. However, the impact of ambient meteorological conditions on the aerosol influence on CF continues to pose challenges as their covariability and interactions obscure the quantification of the aerosol–CF relationship.

We established a data-driven framework based on cloud droplet number concentration (Nd, as a proxy for aerosol) and CF retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) and meteorological parameters from the European Centre for Medium-Range Weather Forecasts Reanalysis v.5 (ERA5). The eXtreme Gradient Boosting (XGBoost) machine learning is applied to the daily collocated MODIS-ERA5 data (2011-2019) from 60°N to 60°S to predict CF with Nd and meteorological predictors. The Nd–CF sensitivity and its dependence on meteorological factors are quantified by SHapley Additive exPlanation (SHAP) values and SHAP interaction values. We found that both CF sensitivities and their interactions with meteorology derived from the SHAP approach exhibit distinct and coherent regional characteristics.

The ongoing work is intended to implement an identical XGBoost-SHAP setup on outputs from the ICOsahedral Non-hydrostatic-Hamburg Aerosol Module (ICON–HAM) global atmospheric-aerosol model, and to compare the magnitudes and geographical patterns of the sensitivities and interactive effects derived from observations with those from ICON-HAM. Discrepancies may point to the physics parameterization schemes in ICON-HAM which may need further evaluation of their representativity with respect to relevant processes. This novel explainable machine learning framework can potentially provide insights into parameterization tuning and enhance our knowledge of the complex aerosol-cloud-climate system.

How to cite: Jia, Y., Andersen, H., and Cermak, J.: Comparison between model and observational cloud fraction adjustment using explainable machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8451, https://doi.org/10.5194/egusphere-egu24-8451, 2024.

EGU24-8917 | Orals | AS3.10

Cloud drop activation of insoluble particles: impact of surface properties 

Ari Laaksonen, Linnea Mustonen, Ana A. Piedehierro, Yrjö Viisanen, and André Welti

A number of studies have reported experimental CCN activation properties of water insoluble particles, mainly various minerals and soots, during the past decade or so (e.g. Kumar et al., 2011; Lathem et al., 2011, Dalirian et al., 2018). A popular theoretical framework for interpreting the results is the FHH adsorption activation theory (Sorjamaa and Laaksonen, 2007), which is a combination of the two-parameter FHH adsorption isotherm model and the Kelvin equation. However, it has become clear that the FHH activation theory tends to overpredict critical supersaturations quite substantially when the FHH parameters are determined from experimental water adsorption isotherms (Laaksonen et al., 2016; Hatch et al., 2019). A possible reason for the discrepancy is surface roughness of the particles, not accounted for in the FHH adsorption activation theory (Laaksonen et al., 2016). One way to quantify the extent of the surface roughness is through the surface fractal dimension, which can be determined e.g. with the help of nitrogen adsorption measurements. We showed earlier (Laaksonen et al., 2016) that employing the surface fractal dimension within the FHH framework does seem to improve the theoretical predictions. However, our data for water and nitrogen adsorption measurements were obtained from literature sources, and therefore the surface properties of a given mineral species employed in the adsorption measurements and in the CCN experiments were not necessarily similar. Therefore, the uncertainty limits of the surface fractal dimension -corrected predictions were rather high. Here, we compare theoretical and experimental critical supersaturations for several metal oxide and mineral aerosols. The materials used in the water and nitrogen adsorption measurements are the same as those used in the CCN experiments, allowing us to improve the reliability of our conclusions regarding the quality of the theoretical predictions.   

Dalirian, M, Ylisirniö, A., Buchholz, A., Schlesinger, D., Ström, J., Virtanen, A. and Riipinen, I. (2018). Cloud droplet activation of black carbon particles coated with organic compounds of varying solubility.  Atmos. Chem. Phys. 18, 12477-12489.

Hatch, C.D., Tumminello, P.R., Cassingham, M.A., Greenaway, A.L., Meredith, R. and Christie, M.J. (2019). Technical note: Frenkel, Halsey and Hill analysis of water on clay minerals: toward closure between cloud condensation nuclei activity and water adsorption. Atmos. Chem. Phys. 19, 13581-13589.

Kumar, P, Sokolik, I.N. and A. Nenes, A (2011). Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals. Atmos. Chem. Phys. 11, 3527–3541.

Laaksonen, A., Malila, J. and Nenes A (2016). Surface fractal dimension, water adsorption efficiency, and cloud nucleation activity of insoluble aerosol. Sci. Rep. 6, 25504.

Lathem, T., Kumar, P., Nenes, A., Dufek, J., Sokolik, I.N., Trail, M. and Russell, A. (2011). Hygroscopic properties of volcanic ash. Geophys. Res. Lett. 38, L11802.

Sorjamaa, R. and Laaksonen A. (2007). The effect of H2O adsorption on cloud drop activation of insoluble particles: a theoretical framework. Atmos. Chem. Phys. 7, 6175–6180.

How to cite: Laaksonen, A., Mustonen, L., Piedehierro, A. A., Viisanen, Y., and Welti, A.: Cloud drop activation of insoluble particles: impact of surface properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8917, https://doi.org/10.5194/egusphere-egu24-8917, 2024.

This study employed the WRF-Chem-SBM model which couples spectral-bin cloud microphysics (SBM) and online aerosol module (MOSAIC) to investigate aerosol-cloud interactions in liquid-phase clouds over eastern China and its adjacent oceans. The results indicate that with an increase in aerosol number concentration (Na), cloud droplet number concentration (Nd) exhibits a trend of initially increasing and then decreasing, both over land and ocean. The difference lies in the stronger convective and land surface effects over land, leading to more intense activation, while over the ocean, weaker supersaturation and richer water vapor content result in weaker activation but more favorable conditions for cloud droplet growth. Cloud processes over land are more intense than over the ocean, but the cloud liquid water content (CLWC) in both regions shows a similar trend with the variation of Nd. In precipitating clouds with richer water content and stronger intracloud processes, as Nd increases, the cloud droplet effective radius decreases, and CLWC exhibits a gradual increase followed by a rapid decrease. In non-precipitating clouds with lower water content and weaker intracloud processes, the increase in Nd leads to a more gradual growth of CLWC, and the subsequent decrease in CLWC is also more subtle. Furthermore, this study discusses the impact of meteorological and aerosol conditions on aerosol activation and cloud development. Environments with a moderate Na are more conducive to aerosol activation, while in environments with low to moderate Na, CLWC exhibits faster growth. Compared to humidification, cooling has a more significant effect on aerosol activation and CLWC growth.

How to cite: Zhao, J., Ma, X., Quaas, J., and Jia, H.: Exploring aerosol-cloud interactions in liquid-phase clouds over eastern China and its adjacent ocean using the WRF-Chem-SBM model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9292, https://doi.org/10.5194/egusphere-egu24-9292, 2024.

EGU24-9408 | ECS | Posters on site | AS3.10

WRFChem Simulation of Aerosol perturbation on Outgoing Longwave Radiation over West Africa's Heterogeneous Landscapes 

Ayodeji Oluleye, Julius Akinyoola, Ezekiel Imole Gbode, and Mariano Mertens

Outgoing Longwave Radiation (OLR) across West Africa is characterized by significant variability as a consequence of the region's diverse landscape or landuse/landcover and the influence of various climatic drivers. This study revealed spatiotemporal patterns of OLR over West Africa, aiming to enhance our understanding through the assessment of the WRF-Chem model's ability to accurately capture these dynamic processes. CAMS reanalysis dataset was used to scrutinizing the model's performance on a regional scale. Two experiments were also conducted to investigate non-aerosol and aerosol perturbation on OLR variability in the region. 

Our findings revealed a distinctive spatial heterogeneity in OLR across West Africa, particularly during different seasons. Notably, during the June-July-August (JJA) period, the Guinea coast exhibited lower OLR values (160 – 195 W/m²) attributable to dense cloud cover, increased precipitation, and elevated water vapor content. In contrast, the Sahel and Sahara Desert regions displayed an average OLR value of 225 W/m², associated with lower humidity and precipitation levels. The December-January-February (DJF) and March-April-May (MAM) seasons revealed higher OLR values (255 W/m²) in the Sahel and Sahara Desert, attributed to clear skies and reduced humidity. The evaluation of the WRF-Chem model demonstrated its competency in reproducing observed data, evidenced by a positive correlation and relatively low Root Mean Square Error (RMSE). Variations in model performance across different data points and seasonal periods were indicated by the Standard Deviation. Trend analyses also indicated an increasing trend and variability in OLR values from February to August in the Guinea Coast and Sahara Desert, contrasting with a decreasing trend in the Sahel region. In a pristine atmosphere devoid of aerosol perturbation, OLR exhibited less variability and greater consistency from the Guinea coast to the Sahara Desert, with occasional extreme values noted in the latter. Conversely, periods of aerosol perturbation revealed a wider range of OLR values, signifying increased variability influenced by aerosol-induced alterations to the atmosphere's radiative balance and energy exchange.

The study concludes that the influence of aerosol perturbations emerges as a key factor, introducing heightened variability in OLR values, which holds implications for our understanding of radiative processes in this region.

How to cite: Oluleye, A., Akinyoola, J., Imole Gbode, E., and Mertens, M.: WRFChem Simulation of Aerosol perturbation on Outgoing Longwave Radiation over West Africa's Heterogeneous Landscapes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9408, https://doi.org/10.5194/egusphere-egu24-9408, 2024.

EGU24-9453 | Posters on site | AS3.10

Ice-nucleating particles over the Labrador Sea during the M-Phase campaigns 

Mark D. Tarn, Polly B. Foster, Sam J. Clarke, James B. McQuaid, Joseph Robinson, Erin N. Raif, Sarah L. Barr, Katherine H. Bastin, Kathleen A. Thompson, Zongbo Shi, Richard Cotton, Paul R. Field, Keith N. Bower, Martin W. Gallagher, Thomas Choularton, and Benjamin J. Murray

As the Earth warms, it is important to understand how a change in the ice:water ratio in mixed-phase clouds influences the cloud-phase feedback; a cooling effect caused by the change in albedo of the cloud. Ice-nucleating particles (INPs), aerosols that can trigger the freezing of liquid cloud droplets via heterogeneous nucleation, may regulate this cooling process by maintaining the ice contents in clouds, hence it is necessary to identify the types, sources, and concentrations of INPs to determine their contribution and better represent this in models. We undertook ship and aircraft-based INP measurement campaign in the Labrador Sea region, which features clouds that are susceptible to the effect of INPs, in 2022: (i) a cruise on the RRS Discovery, as part of a joint SEANA/M-Phase project in May-June, and (ii) a flight campaign on the FAAM BAe-146 aircraft as part of the M-Phase project in October-November that focused on northwesterly cold air outbreak (CAO) cloud systems.

During the SEANA/M-Phase ship cruise, real-time measurements of INP concentrations were taken using a Portable Ice Nucleation Experiment (PINE) expansion chamber alongside offline filter-based measurements and bulk seawater measurements. Preliminary results suggest that high INP concentrations correlated with air masses that had passed over the exposed (i.e. not snow- or ice-covered) coastline of Greenland, while lower concentrations correlated with air masses that had passed over the sea ice. These results suggest a high-latitude source of INPs not currently accounted for in models, the study of which could be crucial in understanding their influence on clouds in a changing climate.

Offline filter-based INP measurements during the FAAM aircraft campaign showed highly reproducible INP concentrations during CAO events (0.05 INP L−1 at −15 °C), with both much higher and much lower concentrations during non-CAO days. Further analysis will include further processing of the campaign data, including aerosol size distributions together with real-time INP data taken from a new online continuous flow diffusion chamber (CFDC), the Met Office Ice Nuclei Counter (INC), aboard the aircraft, together with aerosol composition analysis via scanning electron microscopy of filters, which will allow the types and sources of INPs in the Labrador Sea region to be established.

The M-Phase campaigns in the Labrador Sea have shed some light on INP properties in the region, and further processing of the data will allow determination of INP sources, activity, and relationship with aerosol size distributions. Better representation of INPs in models based on these findings will allow for reduced uncertainty in the cloud-phase feedback and its impact on climate predictions.

How to cite: Tarn, M. D., Foster, P. B., Clarke, S. J., McQuaid, J. B., Robinson, J., Raif, E. N., Barr, S. L., Bastin, K. H., Thompson, K. A., Shi, Z., Cotton, R., Field, P. R., Bower, K. N., Gallagher, M. W., Choularton, T., and Murray, B. J.: Ice-nucleating particles over the Labrador Sea during the M-Phase campaigns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9453, https://doi.org/10.5194/egusphere-egu24-9453, 2024.

EGU24-11095 | ECS | Orals | AS3.10

Surface climate response to the size and season of northern hemisphere, high latitude, effusive volcanic eruptions 

Tómas Zoëga, Trude Storelvmo, and Kirstin Krüger

Effusive volcanic eruptions are known to impact climate through the emission of sulphur dioxide and subsequent formation of sulphate aerosols. These aerosols affect radiative transfer in the atmosphere, both directly by scattering sunlight and indirectly through aerosol-cloud interactions. By scattering sunlight, the direct aerosol effect leads to surface cooling. Changes in cloud properties as a result aerosol-cloud interactions, on the other hand, lead to both reflection of sunlight and trapping of outgoing thermal emissions from the ground. Clouds, therefore, have the potential to either cause surface warming or cooling, depending on factors such as the cloud response to the volcanic aerosols and the availability of sunlight.

We perform a series of simulations using the Community Earth System Model with the Community Atmosphere Model (CESM2-CAM6) to simulate the climate impacts of northern hemisphere, high latitude, effusive volcanic eruptions. We construct a standard eruption scenario, using the 2014-15 Holuhraun eruption in Iceland as a reference. The Holuhraun eruption released up to 9.6 Tg SO2 over a period of six months, from September 2014 to February 2015, with the emission rate gradually decreasing over time. We apply several different magnitude scalings to this standard scenario and vary the timing of the eruption. This allows us to analyse the climate response as a function of both the eruption size and season.

For eruptions starting in winter, we find significant surface warming in our simulations as a result of trapping of outgoing thermal emissions in the absence of sunlight. This warming is mainly confined to the Arctic but also appears over parts of northern Eurasia and North-America, albeit to a lesser extent. This is consistent with our previous work on the Holuhraun eruption where we found evidence for winter surface warming over the Greenland Sea as a result of that eruption, both in model simulations and observations.

Conversely, we find surface cooling during summertime eruptions. The spatial distribution of the cooling pattern is different from the winter warming as the cooling predominantly occurs over the Eurasian and North-American continents and is hardly visible in the Arctic. Furthermore, based on preliminary results, whereas the Arctic winter warming is mainly due to aerosol-cloud interactions, the continental summer cooling stems mostly from the direct aerosol effect. Our results indicate a non-linear relationship between the surface air temperature response and the eruption size.

How to cite: Zoëga, T., Storelvmo, T., and Krüger, K.: Surface climate response to the size and season of northern hemisphere, high latitude, effusive volcanic eruptions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11095, https://doi.org/10.5194/egusphere-egu24-11095, 2024.

EGU24-11712 | ECS | Orals | AS3.10

A cloud-by-cloud approach for studying aerosol-cloud interaction in satellite observations  

Fani Alexandri, Felix Müller, Goutam Choudhury, Peggy Achtert, Torsten Seelig, and Matthias Tesche

Aerosol-cloud interactions are of central importance for understanding climate processes but remains the largest uncertainty associated with climate change. Hence, the effective radiative forcing (ERF) due to ACI and rapid adjustments (ERFaci) is still assessed only with medium confidence. An important part of this uncertainty originates from the difficulty of quantifying ACI using observations, especially for ice-containing clouds. In this study, we present a novel Cloud-by-Cloud (CxC) approach for studying ACI in satellite observations that merges properties of individual clouds that have been tracked from geostationary satellite observations with height-resolved concentrations of cloud condensation nuclei (nCCN) and ice nucleating particles (nINP) from polar-orbiting lidar data. This approach lays the foundations for better understanding of ACI through a thorough investigation of matched aerosol-cloud cases at cloud level. The methodology is applied to satellite observations over Central Europe and Northern Africa for several years, resulting in a bottom-up dataset of combining parameters that can be stratified accordingly for assessing the impact of changes in cloud-relevant aerosol concentrations on the surrounding quality assured liquid and ice-containing clouds. The first preliminary results of this novel CxC approach are promising and constitute a step forward in the quantification of ERFaci from space.

How to cite: Alexandri, F., Müller, F., Choudhury, G., Achtert, P., Seelig, T., and Tesche, M.: A cloud-by-cloud approach for studying aerosol-cloud interaction in satellite observations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11712, https://doi.org/10.5194/egusphere-egu24-11712, 2024.

The role of aerosol and aerosol-cloud interactions (ACI) in the Earth system is a major source of uncertainty in projections of Earth’s future climate and in interpreting how the climate has evolved in the past. The “Enabling Aerosol-cloud interactions at GLobal convection-permitting scalES (EAGLES)” project aims to achieve unprecedented realism in predictions of aerosol and ACI in the next-generation Earth system models. The effort includes improving the representation of aerosol and ACI processes with physics-based or data-driven methods, readying the parameterizations for kilometer-scale simulations, and constraining the model using process-oriented diagnostics based on both satellite and in-situ measurements. By combining process models, large-eddy simulations, and observational data from ARM, satellites, and other sources, stubborn model biases associated with resolution and physics have been addressed accordingly. We demonstrate that improved atmospheric simulations can be achieved with better physics, better integration with data, and better software. We also identify new opportunities for improvements.

How to cite: Ma, P.-L.: Enabling Aerosol-cloud interactions at GLobal convection-permitting scalES (EAGLES), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12164, https://doi.org/10.5194/egusphere-egu24-12164, 2024.

EGU24-12184 | ECS | Posters on site | AS3.10 | Highlight

In-situ optical characterization of ice fog and diamond dust events at DOME-C, Antarctica 

Adrian Hamel, Massimo del Guasta, Emma Järvinen, and Martin Schnaiter

In-situ measurements of small atmospheric ice crystals (< 100 µm) on the Antarctic plateau are rare. Yet, small ice crystals are abundant in a region that often reaches cirrus temperatures even in the warmest season. The Particle Phase Discriminator (PPD-2K) was deployed on DOME-C, Antarctica during austral summer 2023/2024. It was used to characterize the microphysical and optical properties of individual ice fog and diamond dust ice crystals having sizes between approximately 10 and 100 µm. These properties included particle concentration, size distribution and spatial light scattering patterns in the forward direction that allow the analysis of the particle sphericity (particle phase), shape and crystal complexity.
The atmospheric ice crystals on the Antarctic plateau commonly appear in form of ice fogs that have an effect on the radiative budget. In this presentation an ice fog event occurring between 26.11.2023 and 27.11.2023 is analyzed in detail using additional data from LIDAR, temperature and humidity sensors operated at DOME-C. The results are compared to previous findings in Antarctica and to ice fog measurements with the same instrument in a polluted environment at Fairbanks, Alaska.

How to cite: Hamel, A., del Guasta, M., Järvinen, E., and Schnaiter, M.: In-situ optical characterization of ice fog and diamond dust events at DOME-C, Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12184, https://doi.org/10.5194/egusphere-egu24-12184, 2024.

EGU24-12304 | Posters on site | AS3.10

A Rapid Pathway for Saharan Dust Transport to the Arctic 

Denghui Ji, Xiaoyu Sun, Mathias Palm, and Justus Notholt

A new pathway for Saharan dust transport to the Arctic is found recently[1,2], crossing the North Atlantic directly into the Arctic. In order to reveal the climatology features of this rapid pathway, Merra-2, ERA5 reanalysis data and Geos-Chem model simulations are used in this study. We started our analysis with a dust enhancement case study. From model simulations, on 14 March 2022, a Saharan dust event is transported northwards. This dust took only a few days to reach the Arctic along this pathway. In the following month, there were four dust enhancement events. Model results indicate that the Shahara Desert is the main source (~ 80%) of Arctic dust in spring. From Merra-2 reanalysis data (dust aerosol optical depth, AOD), this new pathway once opened from 2000 to 2015, and then closed until 2022. Combined with the North Atlantic Oscillation (NAO) index and the ERA5 reanalysis data (700 hPa wind field), we find that the opening of the rapid pathway tends to be in the weakly positive or negative phase of the NAO. It implies that the jet stream is more meandering, which is favorable for dust transport. Specifically, the opening of the rapid pathway requires the presence of cyclones in the residual circulation near Iceland and anticyclones in the mid-latitude Atlantic.

 

Reference

[1] Francis, D., Eayrs, C., Chaboureau, J.-P., Mote, T., & Holland, D. M. (2018). Polar jet associated circulation triggered a Saharan cyclone and derived the poleward transport of the African dust generated by the cyclone. Journal of Geophysical Research: Atmospheres, 123, 11,899–11,917. https://doi.org/10.1029/2018JD029095

[2] Francis, D., Mattingly, K. S., Lhermitte, S., Temimi, M., and Heil, P.: Atmospheric extremes caused high oceanward sea surface slope triggering the biggest calving event in more than 50 years at the Amery Ice Shelf, The Cryosphere, 15, 2147–2165, https://doi.org/10.5194/tc-15-2147-2021, 2021.

How to cite: Ji, D., Sun, X., Palm, M., and Notholt, J.: A Rapid Pathway for Saharan Dust Transport to the Arctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12304, https://doi.org/10.5194/egusphere-egu24-12304, 2024.

EGU24-12776 | ECS | Posters on site | AS3.10

Study of cloud droplet formation and growth under turbulent conditions in LACIS-T 

Svetlana Melnik, Silvio Schmalfuß, Frank Stratmann, Mira Pöhlker, and Dennis Niedermeier

The study of cloud formation is a crucial aspect of understanding the Earth's weather and climate system. Cloud droplet formation, growth, and the resulting size distributions are influenced by various atmospheric conditions. Despite extensive research, the impact of turbulence on droplet formation and growth remains incompletely understood.

To address this knowledge gap, we investigated the effect of turbulent saturation fluctuations on these mentioned processes. The respective study was conducted using the turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T, Niedermeier et al., 2020) which is a closed-loop, moist-air wind tunnel. LACIS-T is an ideal facility for pursuing mechanistic understanding of these processes and interactions under well-defined and reproducible laboratory conditions.

In LACIS-T, by mixing of three conditioned air streams (i.e. two particle-free air streams, and one aerosol stream), it is possible to precisely adjust temperature and water vapor fields so as to achieve various (super)saturation levels. A passive or active grid are used to introduce turbulence.

In our study, we examined the growth of size-selected monodisperse NaCl particles under various conditions of saturation and temperature at different turbulence patterns. Results of the study provide new experimental insights into the effect of turbulence on cloud droplet formation, growth, and consequently, the shape of cloud droplet size distributions.

Niedermeier et al. (2020), Atmos. Meas. Tech., 13, 2015-2033, https://doi.org/10.5194/amt-13-2015-2020.

Keywords: Cloud droplet growth, Droplet size distribution, Turbulence, Saturation fluctuations

How to cite: Melnik, S., Schmalfuß, S., Stratmann, F., Pöhlker, M., and Niedermeier, D.: Study of cloud droplet formation and growth under turbulent conditions in LACIS-T, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12776, https://doi.org/10.5194/egusphere-egu24-12776, 2024.

The estimation of cloud radiative forcing (RFaci), arising from aerosol-cloud interactions (also known as the first indirect effect), relies on approximating cloud albedo susceptibility (β) to changes in droplet concentration. β depends on both cloud albedo and droplet concentration, which are observable through satellite observations. Typically, satellite data is spatially aggregated to coarser resolutions, such as 1 × 1° scenes. However, at these spatial scales, cloud albedo tends to be heterogeneous, while the β approximation assumes homogeneity. This study demonstrates that the common practice of aggregating satellite data and neglecting cloud albedo heterogeneity results in an average overestimation of 10% in previous RFaci estimates.

How to cite: Goren, T., Sourdeval, O., Kretzschmar, J., and Quaas, J.: Spatial Aggregation of Satellite Observations Leads to an Overestimation of the Radiative Forcing due to Aerosol-Cloud Interactions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12779, https://doi.org/10.5194/egusphere-egu24-12779, 2024.

EGU24-12965 | Orals | AS3.10

Evaluating Droplet Size Distribution Evolution in Aerosol-constrained Simulations of Tropical Cumulus Congestus against Airborne Polarimetry Observations 

Bastiaan van Diedenhoven, McKenna Stanford, Ann Frindlind, Andrew Ackerman, Qian Xiao, Jian Wang, Otto Hasekamp, Snorre Stamnes, Brian Cairns, Andrzej Wasilewski, and Mikhail Alexandrov

The evolution of cumulus congestus within tropical oceanic and maritime environments is modulated by the interaction of convective dynamics, liquid- and ice-phase microphysical processes, aerosol loading, and entrainment of ambient environmental air. Characterizing this evolution requires robust observational constraints of aerosol properties and cloud macrophysics and microphysics. The NASA Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex) field campaign in 2019 targeted growing cumulus congestus clouds using airborne in situ and remote sensing platforms. In situ aircraft microphysical measurements and retrievals from the Research Scanning Polarimeter (RSP) both show that cloud droplet number concentrations decrease and effective radius increases with increasing cloud top height, with droplet size distributions (DSDs) that broaden with height. These observed components are responsive to an active collision-coalescence process that produce millimeter-sized drops, onsetting warm-rain formation. Here, we present an analysis of CAMP2Ex RSP data showing the evolution of droplet number concentrations and DSDs with height and its variation with RSP-retrieved aerosol number concentrations. For one case study (RF14, 9/25/2019), we perform large eddy simulations (LES) at 100-m horizontal grid spacing using bin and bulk microphysics schemes. Detailed multi-modal, vertically resolved aerosol measurements from the Fast Integrated Mobility Spectrometer (FIMS) are used as input. The relative ability of the bulk and bin schemes to produce the observed DSD evolution, from activation to warm-rain production, is evaluated. Sensitivity experiments are performed to assess the roles of height-varying aerosol concentrations, rain-forming collision-coalescence, and entrainment in realizing observed droplet number concentration and effective radius profiles. Additionally, we share the prospect of detailed aerosol properties, droplet number concentrations, and DSDs, similar to as acquired by RSP, becoming available from polarimeters on NASA’s PACE satellite mission, launched in early 2024.

How to cite: van Diedenhoven, B., Stanford, M., Frindlind, A., Ackerman, A., Xiao, Q., Wang, J., Hasekamp, O., Stamnes, S., Cairns, B., Wasilewski, A., and Alexandrov, M.: Evaluating Droplet Size Distribution Evolution in Aerosol-constrained Simulations of Tropical Cumulus Congestus against Airborne Polarimetry Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12965, https://doi.org/10.5194/egusphere-egu24-12965, 2024.

EGU24-14768 | ECS | Posters on site | AS3.10

Cloud Condensation Nuclei (CCN) activity of sub-micron aerosols during the Southwest Monsoon over a pristine site in the Western Ghats, India 

Aishwarya Singh, Kavyashree Kalkura, Rameshchand Ka, Ravikrishna Raghunathan, Ulrich Poschl, Hang Su, James Allan, Gordon Mcfiggans, Meinrat Andreae, Scot Martin, Hugh Coe, Pengfei Liu, and Sachin Gunthe

Aerosols, with their direct and indirect effects impacting the climate, have been established to significantly perturb Earth's radiative budget and hydrological cycle. The climate impact of aerosols is complex and multifaceted, with various factors influencing the combined net effect. The intricacies of aerosol effects, mainly through aerosol-cloud interactions, necessitate precise measurements to reduce the uncertainty in forecasting future climate fluctuations1. Studying their characteristics in pristine settings can provide an enhanced scientific understanding of aerosol impact in background conditions, as opposed to polluted ones2. With this motivation, we conducted a comprehensive field measurement campaign during the second phase of the COVID-induced lockdown in Munnar, a relatively clean high-altitude site in the Western Ghats of India. Munnar is surrounded by lush tea plantations and extensive forest reserves, and tea production and tourism are the major human activities in the area. However, suspended tourist activities due to the pandemic and frequent precipitation during monsoon enabled us to study the ambient aerosol characteristics in near-natural conditions3. This study presents results from the size-resolved Cloud Condensation Nuclei (SR-CCN) measurements conducted along with aerosol size distribution and chemical composition at the Natural Aerosol and Bioaerosol High Altitude Laboratory (NABHA; 10.09 N, 77.06 E; 1605m asl) during the Southwest Monsoon season between June-October 2021. The median number concentration for 10–450nm particles was observed to be 533cm-3, with 357cm-3and 908cm-3 as first and third quartiles, respectively, similar to other pristine locations, such as Amazonia during the wet season4. The average non-refractory particulate matter (NR-PM1) concentration was 2.28±1.81 µg/m3 (mean ± one standard deviation). The SR-CCN measurements were carried out for set supersaturations between 0.1% and 0.85% for particles ranging between 20-350 nm in diameter. The critical dry diameter varied from 60 to 150nm for highest to lowest supersaturation, similar to previously reported studies elsewhere4,5. During the campaign, the efficiency spectra of CCN often reached unity despite organic aerosols dominating the submicron aerosol composition.

Further, hygroscopicity, a particle size and composition function, was investigated using the kappa-Köhler theory. The hygroscopicity parameter, kappa, derived from SR-CCN measurements(kCCN) varied between 0.26 and 0.57. kCCN did not exhibit much variation in the Aitken mode regime (60-80nm) but increased in the accumulation mode (100-160nm), suggesting higher hygroscopic fraction in larger (aged) particles. Assuming a linear mixing of organic and inorganic aerosols, chemically derived hygroscopicity (kchem) was comparable to kCCN, following similar diurnal variation. Further details will be presented.

References:

1.Lohmann, U. & Ferrachat, S. Impact of parametric uncertainties on the present-day climate and on the anthropogenic aerosol effect. AtmosChemPhys (2010).

2.Andreae, M. O. Aerosols Before Pollution. Science (2007).

3.Navasakthi, S., Pandey, A., Bhari, J. S. & Sharma, A. Significant variation in air quality in South Indian cities during COVID-19 lockdown and unlock phases. EnvironMonitAssess (2023).

4.Gunthe, S. S. et al. Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity. AtmosChemPhys (2009).

5.Singh, A. et al. Rapid growth and high cloud-forming potential of anthropogenic sulfate aerosol in a thermal power plant plume during COVID lockdown in India. NPJClimAtmosSci (2023).

How to cite: Singh, A., Kalkura, K., Ka, R., Raghunathan, R., Poschl, U., Su, H., Allan, J., Mcfiggans, G., Andreae, M., Martin, S., Coe, H., Liu, P., and Gunthe, S.: Cloud Condensation Nuclei (CCN) activity of sub-micron aerosols during the Southwest Monsoon over a pristine site in the Western Ghats, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14768, https://doi.org/10.5194/egusphere-egu24-14768, 2024.

EGU24-15150 | Orals | AS3.10

Using a global aerosol model to interpret satellite-derived aerosol-cloud interactions  

Harri Kokkola, Muhammed Irfan, Antti Lipponen, Silvia Calderon, and Antti Arola

Determining the susceptibilities of cloud properties to perturbations in aerosols has been a persisting challenge in climate research. For example, satellite-retrieved susceptibility of cloud droplet number concentration (CDNC) to changes in cloud condensation nuclei (CCN) varies regionally, also having opposite correlations over land and ocean. Over the oceans, the correlation between CCN and CDNC is positive and in many cases, with a proper regression method, the dlogCDNC/dlogCCN exceeds 1. On the other hand, over land, many studies have found a negative correlation. As our preliminary global climate model simulations give qualitatively similar results to satellite retrievals, we have used the model together with reanalysis data of aerosol, meteorological properties, and cloud properties to interpret how other parameters such as cloud activation updrafts and vertical mixing of aerosol affect the satellite derived CCN vs CDNC correlations. In this study, we focus on ocean regions determining how these different atmospheric properties affect the derived slope between CCN and CDNC. Our results indicate that as satellite derived CCN is a columnar value, does not properly represent the true variability of cloud base CCN. Thus, the mixing of aerosol as well as cloud activation updrafts cause biases in the satellite determined CCN vs CDNC correlations.

How to cite: Kokkola, H., Irfan, M., Lipponen, A., Calderon, S., and Arola, A.: Using a global aerosol model to interpret satellite-derived aerosol-cloud interactions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15150, https://doi.org/10.5194/egusphere-egu24-15150, 2024.

EGU24-15271 | Posters on site | AS3.10

Chemical characterization of sub-micrometer marine aerosol around the Ross Sea during CAIAC (2022-23 Antarctic summer) 

Matteo Rinaldi, Marco Paglione, Marco Rapuano, Diego Fellin, Stefano Decesari, Niccolò Losi, Luca Ferrero, and Angelo Lupi

Remote from most human influences, the Southern Ocean (SO) is one of the most pristine regions on Earth and a window to preindustrial atmospheric conditions (Hamilton, 2015). Currently, many unknowns remain about atmospheric and oceanographic processes in this region and their relations. This is largely due to the poor understanding of aerosol sources and processes in this region.

Sub-micrometer aerosol samples were collected onboard the Italian RV Laura Bassi cruising the Southern Ocean and the Ross Sea, in the framework of the PNRA (Programma Nazionale di Ricerca in Antartide) project CAIAC (oCean Atmosphere Interactions in the Antarctic regions and Convergence latitude). The aim is to characterize the marine aerosol chemical composition in different ecoregions, with a particular interest for organic aerosols and their formation processes in relation with the patterns of oceanic biological activity.

Samples were collected by a high volume sampler (TECORA, ECHO-HIVOL, 500 LMP) from mid-January to mid-February 2023, deploying a wind direction selection system to avoid ship contaminations. A total of 9 samples were collected. The samples have been analysed for their water-soluble Carbon and Nitrogen content by a C-N elemental analyzer (Shimadzu) and for the ionic composition (including low molecular weight acids and amines) by ion chromatography (Dionex). The characterization of the water-soluble organic fraction in terms of tracers and functional group abundance was performed by 1H NMR (Proton Nuclear Magnetic Resonance) spectroscopy (Decesari et al, 2020).

The samples show variable contributions in terms of primary and secondary components, mostly depending on back trajectory origin and wind speed, with a general predominance of secondary species. Sulfate resulted generally the most abundant aerosol component, while water soluble organic matter (WSOM) showed a non-negligible contribution from 5 to 14% of the analysed mass. NMR spectra show the complexity of the WSOM composition, even though all the spectra were dominated by the MSA signal, which contribution in terms of carbon to WSOM spans from 8 to 64%.

Analysis of organic aerosol sources is in progress by back-trajectory analysis and statistical analysis of the NMR spectra.

 

Acknowledgements: CAIAC (oCean Atmosphere Interactions in the Antarctic regions and Convergence latitude) PNRA project.

 

Decesari, S. et al. (2020), Atmos. Chem. Phys., 20, 4193–4207, https://doi.org/10.5194/acp-20-4193-2020

Hamilton, D. S. Weather 2015, 70 (9), 264– 8, DOI: 10.1002/wea.2540

How to cite: Rinaldi, M., Paglione, M., Rapuano, M., Fellin, D., Decesari, S., Losi, N., Ferrero, L., and Lupi, A.: Chemical characterization of sub-micrometer marine aerosol around the Ross Sea during CAIAC (2022-23 Antarctic summer), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15271, https://doi.org/10.5194/egusphere-egu24-15271, 2024.

EGU24-15384 | ECS | Posters on site | AS3.10

A mesoscale model for aerosol-cloud interaction studies WRF-PMCAMx-UF with insights to secondary ice production 

Eemeli Holopainen, Paraskevi Georgakaki, David Patoulias, Georgia Sotiropoulou, Romanos Foskinis, Spyros Pandis, and Athanasios Nenes

The interaction between aerosols and clouds is a complex process and it causes large uncertainties in predicting the global climate. This interaction has been studied using chemical transport models (CTMs) as they simulate the distribution and composition of atmospheric aerosols. In this study, we developed a coupled version of the Weather Research and Forecasting (WRF) model with the PMCAMx-UF CTM (Skamarock et al., 2008; Patoulias et al. 2022). We did this by using prognostic cloud droplet number in the Morrison et al. 2009 cloud microphysics scheme of the WRF model. We calculated the prognostic cloud droplet number from the predicted aerosol fields of PMCAMx-UF using the Morales and Nenes 2014 activation scheme. In addition, we investigated the effects of prognostic cloud droplets to secondary ice production (SIP) in the WRF model. This involved the incorporation of various SIP processes, including Hallett-Mossop (HM), collisional fracturing and breakup (BR), droplet freezing and shattering (DS), and sublimational breakup of snow (SBS) and graupel (SBG), following the approaches outlined in Georgakaki et al. 2023. First we evaluated the impact of coupled WRF-PMCAMx-UF model with prognostic droplets to the same model with prescribed droplet number as well as the SEVIRI satellite observations. Secondly we evaluated the effects of adding SIP processes and prognostic droplets to non-SIP and prescribed droplet case and satellite observations. The results showed that using the combined model with prognostic droplets decreased the cloud droplet number concentration (CDNC) and liquid water content (LWC) when compared to the prescribed droplet simulation. This caused a more positive surface radiative forcing and thus a warming effect. In addition, the number of small particles decreased and large particle numbers increased when switching to prognostic droplets. Further, comparing to satellite observations, the prognostic droplet simulation performed better in terms of CDNC than the prescribed droplet simulation. Adding the SIP processes to the model increased the ice crystal number concentration (ICNC) as well as LWC in some areas. Compared to satellite observations, introducing SIP and prognostic droplets into the model performed slightly better in terms of CDNC as well as ice water path (IWP) than the non-SIP and prescribed droplet cases. Thus, a more realistic representation of CDNC as well as incorporation of SIP processes in the coupled model allows a more precise capture of evolving aerosol-cloud interactions in the atmosphere.

How to cite: Holopainen, E., Georgakaki, P., Patoulias, D., Sotiropoulou, G., Foskinis, R., Pandis, S., and Nenes, A.: A mesoscale model for aerosol-cloud interaction studies WRF-PMCAMx-UF with insights to secondary ice production, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15384, https://doi.org/10.5194/egusphere-egu24-15384, 2024.

EGU24-15938 | Orals | AS3.10 | Highlight

Climate responses to regional aerosol emissions: Early multi-model results from RAMIP 

Laura Wilcox, Robert Allen, Bjørn Samset, Molly MacRae, Luke Fraser-Leach, Tsuyoshi Koshiro, Paul Kushner, Anna Lewinschal, Risto Makkonen, Joonas Merikanto, Declan O'Donnell, Naga Oshima, David Paynter, Steven Rumbold, Toshihiko Takemura, Kostas Tsigaridis, and Dan Westervelt

Anthropogenic aerosol emissions are expected to change rapidly over the coming decades, with complex geographical and seasonal patterns. This is expected to drive strong, spatially varying trends in temperature, hydroclimate, and extreme events, both near and far from emission sources. These changes are poorly constrained in current models, and very sparsely represented in climate risk assessments, partly because of a lack of dedicated emission pathways and multi-model investigations.

The Regional Aerosol Model Intercomparison Project (RAMIP) is designed to quantify and bound the role of regional aerosol emissions changes in near-term climate projections. RAMIP experiments are based on the SSPs commonly used in CMIP6 Endorsed MIPs, but are designed to explore sensitivities to aerosol type and location, and provide improved constraints on uncertainties driven by aerosol radiative forcing and the dynamical response to aerosol changes. The core experiments assess the effects of different aerosol emission pathways in East Asia, South Asia, Africa and the Middle East, and North America and Europe through 2051, using a multi-ensemble-member approach in a set of 10 Earth System Models.

Based on early output from a subset of participating RAMIP models, we highlight regions where current and future aerosol reductions may lead to changes in seasonal mean climate and the frequency and severity of extreme events. We will also show examples of how the near-future evolution of temperature and precipitation extremes in Europe and Asia may be influenced by local air quality policies, and those further afield.

How to cite: Wilcox, L., Allen, R., Samset, B., MacRae, M., Fraser-Leach, L., Koshiro, T., Kushner, P., Lewinschal, A., Makkonen, R., Merikanto, J., O'Donnell, D., Oshima, N., Paynter, D., Rumbold, S., Takemura, T., Tsigaridis, K., and Westervelt, D.: Climate responses to regional aerosol emissions: Early multi-model results from RAMIP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15938, https://doi.org/10.5194/egusphere-egu24-15938, 2024.

Marine stratocumulus clouds contribute a significant cooling effect to the Earth's climate, but their role in global climate change hasn't been well quantified. Aerosols from anthropogenic and natural sources alter the characteristics of stratocumulus clouds, although the extend of all cloud adjustments is not yet fully quantified. In particular the cloud fraction adjustment is associated with potentially large radiative forcings, but also high uncertainties.

We used cloud retrievals from the GOES-East satellite to explore cloud fraction adjustments in raining stratocumuli structures, and MERRA-2 aerosol reanalysis data as a proxy for the aerosol-dependent cloud droplet size.

We found that increases in aerosol loading coincide with both increases and decreases in cloud fraction relative to the climatological mean. Decreases in aerosol loading coincide with increases in the fraction of optically thin cloud features which were calculated for various maximum thresholds of optical depth.

For cloud covers with cloud fractions and optically thin cloud areas close to the climatological mean, increased aerosol loading tends to coincide with increases in both of these properties. This is not the case for cloud covers that differ significantly from the climatological mean.

A better understanding of the link between how cloud fraction and optical density respond to aerosol loading could help to improve our knowledge of the effects of aerosols on the radiative properties of stratocumuli.

How to cite: Vieira Fischer, F. and Possner, A.: Exploring cloud fraction adjustments in the South Pacific marine stratocumulus cloud deck using 3 years of GOES 16 retrievals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16133, https://doi.org/10.5194/egusphere-egu24-16133, 2024.

EGU24-16381 | Posters on site | AS3.10

Temperature dependence of cloud drop activation of insoluble particles 

Ana A. Piedehierro, André Welti, Yrjö Viisanen, and Ari Laaksonen

The critical supersaturation of cloud droplet activation by water-soluble aerosols increases at lower temperatures. This is due to the Kelvin effect, with the logarithm of the saturation ratio being inversely proportional to the absolute temperature and linearly proportional to the surface tensions and molecular volume of water. Less is known about the temperature dependence of critical supersaturation when the cloud condensation nuclei (CCN) are water-insoluble. 

The FHH activation theory describes the CCN activation of insoluble particles by combining the FHH (Frenkel-Halsey-Hill) adsorption isotherm and the Kelvin equation. The temperature dependence induced by the Kelvin term is inherently similar to that observed in water-soluble particles. However, the influence of the adsorption term on critical supersaturation as a function of temperature remains unclear. 

The typical temperature dependence of water vapour adsorption is such that an increase in the adsorption layer thickness is expected with decreasing temperature at a constant saturation ratio. Nevertheless, it is known that some adsorbent materials behave differently, adsorbing water vapour more efficiently at higher temperatures, while a third class of adsorbents shows no temperature dependence at all. In this study, we investigate the temperature dependencies of critical supersaturations for water-insoluble particle types that exhibit diverse temperature responses in adsorption measurements. We interpret the results in terms of the FHH adsorption activation model.

How to cite: Piedehierro, A. A., Welti, A., Viisanen, Y., and Laaksonen, A.: Temperature dependence of cloud drop activation of insoluble particles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16381, https://doi.org/10.5194/egusphere-egu24-16381, 2024.

EGU24-16865 | ECS | Orals | AS3.10

Observation of fluorescent primary biological particles at the North Pole: A case of inter-coupled system behaviour? 

Julia Asplund, Annica ML Ekman, Gabriel Freitas, Mats A. Granskog, Benjamin Heutte, Remy Lapere, Morven Muilwijk, Tuomas Naakka, Julia Schmale, Jennie Thomas, and Paul Zieger

Aerosol-cloud interactions remain among the most uncertain key parameters in the fast-changing Arctic climate system. Arctic clouds often consist of both liquid droplets and ice crystals, the abundance of which is constrained by the availability of ice nucleating particles (INP). We present observations of fluorescent primary biological aerosol particles (fPBAP), shown to be potent INP, obtained during the Arctic Ocean 2018 expedition onboard the Swedish icebreaker Oden in August- September of 2018, at the North Pole. The fPBAP were recorded on a single-particle level using a Multiparameter Bioaerosol Spectrometer, as a part of a complete setup for measuring physical and chemical aerosol properties.  Potential sources of fPBAP during an extended period of high concentrations are investigated using a combination of auxiliary measurements, trajectory analysis, remote sensing data, ocean biogeochemistry reanalysis data, and model experiments with WRF-Chem. Our evidence suggests that the observed case of increased fPBAP concentration at the North Pole was caused by transport of fPBAP enriched marine aerosol from a source within the Arctic region, but in open water south of the pack ice. We also highlight how future interdisciplinary efforts can be used more efficiently to improve the source mapping of Arctic fPBAP, which is needed to assess their overall climate-relevance in the polar regions.

How to cite: Asplund, J., Ekman, A. M., Freitas, G., Granskog, M. A., Heutte, B., Lapere, R., Muilwijk, M., Naakka, T., Schmale, J., Thomas, J., and Zieger, P.: Observation of fluorescent primary biological particles at the North Pole: A case of inter-coupled system behaviour?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16865, https://doi.org/10.5194/egusphere-egu24-16865, 2024.

In this work, a data set comprised of satellite observations and reanalysis data is used in explainable machine learning models to analyse the relationship between the cloud droplet number concentration (Nd), cloud liquid water path (LWP) and the fraction of precipitating clouds (PF) in 5 distinct marine stratocumulus (MSC) regions.

Aerosol--cloud--precipitation interactions (ACI) are a known major cause of uncertainties in simulations of the future climate. An improved understanding of the in-cloud feedback processes accompanying ACI could help in advancing their implementation in global climate models. This is especially the case for marine stratocumulus clouds which constitute the most common cloud type globally.

The machine learning framework applied here makes use of Shapley additive explanation (SHAP) values, allowing to isolate the impact of Nd from other confounding factors which proved to be very difficult in previous satellite based studies.

All examined MSC regions display a decrease of PF and an increase in LWP with increasing Nd, despite marked inter-regional differences in the distribution of Nd. The negative Nd-PF relationship is stronger in high LWP conditions, while the positive Nd-LWP relationship is amplified in precipitating clouds. While these results for the Nd-LWP relationship differ from the findings in recent satellite-based global analyses, they are consistent with previous studies using model simulations. The results presented here indicate that precipitation suppression plays an important role in MSC adjusting to aerosol-driven perturbations in Nd.

How to cite: Zipfel, L., Andersen, H., Cermak, J., and Grosvenor, D. P.: How cloud droplet number concentration impacts liquid water path and precipitation in marine stratocumulus clouds - a satellite-based analysis using explainable machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16965, https://doi.org/10.5194/egusphere-egu24-16965, 2024.

EGU24-17179 | Orals | AS3.10

Ice nucleating properties of air filter and snow samples taken in the Central Arctic during MOSAiC 

Amélie Kirchgaessner, Markus Frey, Floor van den Heuvel, Tom Lachlan-Cope, Ananth Ranjithkumar, and Xin Yang

Arctic clouds are still poorly represented in climate models. An important reason for this is our lack of knowledge regarding the various sources of natural aerosol in the high Arctic. Recent field campaigns have provided evidence that over sea ice blowing snow can act as a source of sea salt aerosol (SSA). This source can account for the maximum in SSA that occurs in the Polar Regions during winter and spring. SSA can influence the regional climate through the indirect radiative effect, but also through the role it plays as nucleation particle in cloud formation. Its contribution to and potential as ice nucleating particle (INP) is still largely unknown though. 

 Here we will present offline samples of airborne aerosol taken in the Central Arctic during MOSAiC focussing on the transition period from winter to spring. The samples comprise of quasi-ciontinuous low-volume air filter samples taken in the British Antarctic Survey’s aerosol lab container on board of RV Polarstern, weekly snow samples from the ice floe, and filter samples taken by tethered balloon. These samples were analysed for their ice nucleating characteristics using a peltier cold stage and applying a machine learning algorithm to the images taken during the cooling process.

Initial results confirm an increased presence of INP in both the airborne and snow samples at the turn from winter to spring. 

How to cite: Kirchgaessner, A., Frey, M., van den Heuvel, F., Lachlan-Cope, T., Ranjithkumar, A., and Yang, X.: Ice nucleating properties of air filter and snow samples taken in the Central Arctic during MOSAiC, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17179, https://doi.org/10.5194/egusphere-egu24-17179, 2024.

EGU24-17218 | ECS | Posters on site | AS3.10

Air mass history linked to the development of Arctic mixed-phase clouds 

Rebecca Murray-Watson and Ed Gryspeerdt

The development of clouds during marine cold-air outbreaks (MCAOs) represent a complex phenomenon, transitioning from stratocumulus decks near ice edges to cumuliform fields downwind. This change cloud morphology changes the radiative properties of the cloud, and therefore is of importance to the surface energy budget. Therefore, it is crucial to understand the factors which may drive transition to a broken cloud field. Previous in situ and modelling studies suggest the formation of ice may enhance precipitation and therefore accelerate break-up. However, little is known about the development of mixed-phase clouds in MCAOs. 

This study uses pseudo-Lagrangian trajectories and satellite data to analyze this mixed-phase cloud development. We observe a rapid transition from liquid to ice phases in MCAO clouds, contrasting with similar cloud formations outside MCAO conditions. These mixed-phase clouds initially form at temperatures below -20°C near ice edges but can dominate even at -13°C further into outbreaks. This temperature shift suggests a significant role for biological ice nucleating particles (INPs), which increase in prevalence as air masses age over marine environments. The study also notes the influence of the air mass's history over snow- and ice-covered surfaces, which may be low in INPs, on cloud evolution. This link helps explain seasonal variations in Arctic cloud development, both during and outside of MCAOs. Our findings emphasize the importance of understanding local marine aerosol sources and the broader INP distribution in the Arctic for accurate cloud phase modeling in the region. 

How to cite: Murray-Watson, R. and Gryspeerdt, E.: Air mass history linked to the development of Arctic mixed-phase clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17218, https://doi.org/10.5194/egusphere-egu24-17218, 2024.

EGU24-17439 | Orals | AS3.10

Atmospheric aerosol characterization at Princess Elisabeth station, East Antarctica and identifying source regions using backward trajectory modelling 

Alexander Mangold, Karen De Causmaecker, Quentin Laffineur, Preben Van Overmeiren, Charlotte Deramaix, Christophe Walgraeve, Nadine Mattielli, and Andy Delcloo

Atmospheric composition plays an important role in present and near-future climate change. Airborne particles exert direct and indirect radiative impacts and can serve as cloud condensation and ice nuclei, having therefore a strong influence on cloud formation and precipitation. Furthermore, a detailed understanding of present-day atmospheric transport pathways of particles from source to deposition in Antarctica remains essential.

Since 2010, the aerosol total number and size distribution, aerosol absorption coefficient and mass concentration of light-absorbing aerosols and the aerosol total scattering coefficient have been monitored at the Belgian research station Princess Elisabeth Antarctica (PEA). The station is situated in Dronning Maud Land, East Antarctica (71.95° S, 23.35° E, 1390 m asl). Besides these instruments, a cloud condensation nuclei counter was operated during three austral summers. Meteorological data come from an automatic weather station. In this work, we investigate the climatology of the particle properties with respect to the air mass origin. To that end, we used the FLEXTRA trajectory model to investigate transport pathways into Antarctica. The model was driven with ECMWF ERA-5 meteorological fields. 10-days 3D backward trajectories, starting from PEA, were calculated for the period 01/01/2010 to 31/12/2020, in 3-hour-intervals. A k-means cluster analysis has been done based on latitude, longitude and altitude, resulting in four clusters of air mass origin.

We will present results for the climatology of particle properties and the air mass origin. In addition, the backward trajectories have been combined with measured atmospheric particle properties and parameters like potential vorticity and exposure to sunshine duration, showing the distribution of the measured atmospheric particle properties between and within the air mass origin clusters. Some distinct features could be seen in the air mass origin clustering. Source regions from South America, Southern Africa and Australia, New Zealand were limited and the Southern Ocean was a main source region, as was the Antarctic continent itself. For each season, the dominating cluster represented mainly air masses of Antarctic continental origin with a large influence of upper tropospheric air. We will show further results of our analysis on air mass origin and atmospheric and particle properties, with respect to differentiations between seasons, clusters, continental and maritime origin and source altitude compartments.

How to cite: Mangold, A., De Causmaecker, K., Laffineur, Q., Van Overmeiren, P., Deramaix, C., Walgraeve, C., Mattielli, N., and Delcloo, A.: Atmospheric aerosol characterization at Princess Elisabeth station, East Antarctica and identifying source regions using backward trajectory modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17439, https://doi.org/10.5194/egusphere-egu24-17439, 2024.

EGU24-17504 | Posters on site | AS3.10

Cloud droplet formation characteristics at eleven locations throughout Greece during summer 2020 and 2021 

Kaori Kawana, Romanos Foskinis, Eemeli Holopainen, Alexandros Papayannis, Andreas Aktypis, Christos Kaltsonoudis, David Patoulias, Angeliki Matrali, Christina Vasilakopoulou, Evangelia Kostenidou, Kalliopi Florou, Nikos Kalivitis, Konstantinos Eleftheriadis, Constantini Samara, Mihalis Lazaridis, Nikolaos Mihalopoulos, Spyros Pandis, and Athanasios Nenes and the Observation Team

    Aerosol particles affect the climate system by directly absorbing and scattering solar radiation or by acting as cloud condensation nuclei (CCN) and modulating cloud radiative properties. Cloud particle activation is at the heart of these aerosol-cloud interactions, but it is important to quantify the degree to which aerosol (size distribution and composition) or dynamical aspects (vertical velocity) contribute to cloud droplet number concentration, as they determine in the end the cloud sensitivity to aerosol variations.

    In this study, we use a comprehensive dataset of number-size distributions and meteorological data observed at 11 sites throughout the E. Mediterranean (Greece) during the summers of 2020 and 2021 and use them as input into a state-of-the-art cloud activation parameterization to determine the potential activated cloud droplet number and maximum supersaturation. Remote sensing retrievals of droplet number complement the analysis and are used to evaluate the droplet number calculations carried out with the parameterization. We then examine the droplet formation characteristics of each region (urban, rural, remote, and mountain), determine when clouds are velocity- and aerosol-limited, link them to airmass origin, and discuss the implications for cloud formation in the region.

How to cite: Kawana, K., Foskinis, R., Holopainen, E., Papayannis, A., Aktypis, A., Kaltsonoudis, C., Patoulias, D., Matrali, A., Vasilakopoulou, C., Kostenidou, E., Florou, K., Kalivitis, N., Eleftheriadis, K., Samara, C., Lazaridis, M., Mihalopoulos, N., Pandis, S., and Nenes, A. and the Observation Team: Cloud droplet formation characteristics at eleven locations throughout Greece during summer 2020 and 2021, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17504, https://doi.org/10.5194/egusphere-egu24-17504, 2024.

EGU24-17810 | ECS | Posters on site | AS3.10

An investigation of fog and low cloud life cycles and their interaction with biomass burning aerosols in the Namib 

Alexandre Mass, Hendrik Andersen, Jan Cermak, and Eva Pauli

In this contribution, a statistical model and several satellite products (SEVIRI, CALIPSO) are used to study the potential semi-direct effects of biomass burning aerosols (BBA) on the persistence of fog and low clouds (FLC) in the Namib during the biomass burning season.

Fog, which is the most relevant non-rainfall water source for plants and animals in the coastal parts of the Namib Desert, may become increasingly important for local ecosystems as regional climate simulations predict a warmer and drier climate for southern Africa in the future. Previous studies showed the role of BBA on cloud development over the ocean off the Namibian coast. The same processes are likely to influence Namib-region FLC formation and persistence as well. However, the potential effects of aerosols on FLC in the Namib Desert have yet to be investigated.

Using reanalysis products in combination with satellite data, a statistical model is built to predict FLC dissipation times in high and low BBA loading days. It is found that during this season, FLC dissipation times are positively correlated to BBA loading (higher aerosol loading coinciding with later FLC dissipation). By analyzing the contribution of the different predictors to the output of the statistical model, it is found that the positive correlation is mostly explained by the synoptic scale meteorology. Nevertheless, the synoptic scale circulation and aerosol loading are highly correlated in the region, thus some of the results could still be attributed to aerosol semi-direct effects. To definitively contrast aerosol effects from meteorology, modeling of aerosol-cloud interactions in the region could be promising.

How to cite: Mass, A., Andersen, H., Cermak, J., and Pauli, E.: An investigation of fog and low cloud life cycles and their interaction with biomass burning aerosols in the Namib, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17810, https://doi.org/10.5194/egusphere-egu24-17810, 2024.

EGU24-17813 | ECS | Orals | AS3.10

Typical signatures of the transition zone of cumulus cloud shadows in solar radiation 

Jonas Witthuhn, Hartwig Deneke, and Heike Kalesse-Los

Investigating solar radiation and its variability due to clouds and aerosol is critical for efficient and reliable solar energy systems. During broken cloud conditions, reflections at cloud edges and changing aerosol properties in the vicinity of clouds affect the surface solar radiation significantly. In these situations, the distinction between clouds and clear skies with aerosol is not always well defined[1]. As seen from the surface, this region exists around cloud core shadows and is called the transition zone. Here, a unique dataset of observations from a dense pyranometer network is used to detect and investigate signatures of shortwave broadband transmittance in the transition zone.

The TROPOS pyranometer network consists of up to 100 individual stations. Data of one campaign is used for this study: 60 stations were distributed over an area of about 6 km² during the S2VSR[2] measurement campaign in 2023 at the ARM Southern Great Planes (SGP) site in Oklahoma, USA. The surface solar irradiance is measured at each station with a time resolution of 10 Hz. The transition zone is detected and characterized by applying a modified clear sky detection algorithm[3] to the data. An additional component of our analysis is the determination of the cloud motion. This vector is determined using the Farneback optical flow algorithm[4] on a cloud shadow mask calculated from the “Clouds Optically Gridded by Stereo” (COGS) product[5].

The study aims to quantify the small-scale effects of the transition zone on surface solar irradiance and potential photo-voltaic yield. This information is valuable for photo-voltaic site planning and provides scientifically relevant insights into the interaction between clouds, aerosol and solar radiation.


[1] e.g., Calbó et al. 2017, https://doi.org/10.1016/j.atmosres.2017.06.010

[2] https://www.arm.gov/research/campaigns/sgp2023s2vsr

[3] Bright et al. 2020, https://doi.org/10.1016/j.rser.2020.109706

[4] Farneback 2000, https://doi.org/10.1109/ICPR.2000.905291.

[5] Romps & Oktem et al. 2018, https://doi.org/10.1175/bams-d-18-0029.1

How to cite: Witthuhn, J., Deneke, H., and Kalesse-Los, H.: Typical signatures of the transition zone of cumulus cloud shadows in solar radiation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17813, https://doi.org/10.5194/egusphere-egu24-17813, 2024.

EGU24-18173 | Orals | AS3.10

The Shedding Light On Cloud Shadows project: measuring and simulating surface solar irradiance under broken clouds 

Chiel van Heerwaarden, Wouter Mol, Menno Veerman, Bart van Stratum, Mirjam Tijhuis, Bert Heusinkveld, Oscar Hartogensis, Jordi Vilà-Guerau de Arellano, and Mary-rose Mangan

This year marks the end of the Shedding Light On Cloud Shadows project (SLOCS, 2019-2024). SLOCS aims to understand temporal, spatial, and spectral variability in surface solar irradiance driven by individual clouds from field observations and 3D cloud-resolving large-eddy simulations. In this contribution, we would like to present the highlights of the project and the most important conclusions.

The reason for initiating SLOCS is that clouds trigger large fluctuations in solar surface irradiance, and therefore in surface heat fluxes, but there is still much to be learned about these fluctuations. The incoming radiation in shadows is almost an order of magnitude less than under clear sky, while peaks near clouds shadows can sometimes reach a 50% increase with respect to clear sky, due to scattering of sunlight on clouds. Performing cloud-resolving simulations with realistic surface solar irradiance patterns under broken clouds remains therefore a challenge, and current cloud-resolving models do not capture the radiation-cloud interactions well. 

The Shedding Light On Cloud Shadows (SLOCS) project addresses this challenge by i) performing spatial observations in a spatial grid fine enough (~50 m, 10 Hz) to capture individual clouds using a newly designed instrument, and ii) developing 3D radiative transfer models for cloud-resolving models with optimal balance between detail level and performance. The FESSTVaL, LIAISE, and CloudRoots campaigns provided unique opportunities to measure surface solar irradiance around cloud shadows in different climates. In the campaigns, we performed grid measurements of radiation, while benefiting from complementary boundary-layer and cloud observations.

The most important lessons learned from the field observations are:
1. Scales as small as meters and seconds contribute significantly to fluctuations in surface solar irradiance
2. All broken cloud patterns generate strong peaks, but the underlying mechanisms vary greatly amoung cloud types
3. Spectral variations (in colors of light) are mostly significant under cumulus clouds.

We used those observations to set up a series of cloud-resolving simulations with MicroHH and to evaluate two newly-developed radiative transfer solvers: i) a ray tracer fast enough to be coupled to our cloud-resolving model and ii) a solver that post-processes the outcome of a 1D two-stream solver to emulate 3D effects. Also, we studied the impact of periodic and open lateral boundary conditions. The most important conclusions are:

1. Capturing 3D interactions between clouds and radiation accurately leads to larger clouds with more liquid water compared to those in simulations with conventional 1D methods
2. Post-processing conventional 1D radiation computations allows for simulating surface solar irradiance fields with realistic probability density functions, but inaccurate cloud shadow shape and location.
3. Open lateral boundaries in large-eddy simulations are at least as important as correct radiation-cloud interactions in producing realistic cloud shadows in the range from hectometers to kilometers.

How to cite: van Heerwaarden, C., Mol, W., Veerman, M., van Stratum, B., Tijhuis, M., Heusinkveld, B., Hartogensis, O., Vilà-Guerau de Arellano, J., and Mangan, M.: The Shedding Light On Cloud Shadows project: measuring and simulating surface solar irradiance under broken clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18173, https://doi.org/10.5194/egusphere-egu24-18173, 2024.

EGU24-18214 | ECS | Posters on site | AS3.10

Leveraging surface observations and passive satellite retrievals of cloud properties: Applications to cloud type classification and cloud base height retrieval 

Julien Lenhardt, Johannes Quaas, Dino Sejdinovic, and Daniel Klocke

Clouds are key regulators of the Earth’s energy budget. Their microphysical and optical properties lead to vastly disparate radiative properties. Retrieving information about clouds is thus crucial to reduce uncerntainties in our estimation of climate change. In this study, we present a common approach to the retrieval of cloud type and cloud base height (CBH), two useful aspects to characterise clouds and their radiative effects.

We leverage surface observations of these two cloud characterictics from the network made available by the UK Met Office, linked to satellite retrievals of relevant cloud properties from the MODIS instrument, namely cloud top height, cloud optical thickness and cloud water path. Our approach relies on a convolutional auto-encoder (AE) to project a data cube (dimension of 3 channels, 128 km, 128 km), comprised of the aforementioned cloud properties, to a latent space of lower dimensionality. The latter is then used as predictor for the cloud characteristics of interest.

We demonstrate the skill of the developed method by applying it to CBH retrievals. We create a global dataset of retrieved CBH which exhibits accuracy and precision, in particular for low-level cloud bases, achieving a mean absolute error of 379 m and a standard deviation of the absolute error of 328 m. This is also compared to active satellite retrievals and other CBH retrieval methods. The second application focuses on cloud types, defined following the standards of the WMO. With our approach, we retrieve cloud type occurences at a global scale and are able to study their spatial and temporal patterns. We further use the developed method on km-scale global climate model outputs from the ICON model to help diagnostic cloud representation in this new generation of climate models. Lastly, the presented applications illustrate how fusing surface observations and satellite retrievals still constitutes a resourceful approach to study clouds and their properties.

How to cite: Lenhardt, J., Quaas, J., Sejdinovic, D., and Klocke, D.: Leveraging surface observations and passive satellite retrievals of cloud properties: Applications to cloud type classification and cloud base height retrieval, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18214, https://doi.org/10.5194/egusphere-egu24-18214, 2024.

EGU24-19084 | ECS | Orals | AS3.10

Assessing Model simulation for central Arctic aerosol load by usingAEROSNOW dataset: Relevance for precipitation 

Basudev Swain, Vountas Marco, Deroubaix Adrien, Lelli Luca, Gunthe Sachin S., Bösch Hartmut, and Burrows John P.

The Arctic is currently warming rapidly, at a rate four times higher than the global average. This warming has significant consequences, leading to increased precipitation in the Arctic. Aerosols play a crucial role in cloud formation, cloud condensation nuclei (CCNs) and ice-nucleating particles (INPs), influencing rain and snowfall. However, uncertainties remain in the modelling of aerosols and their impact on precipitation due to a lack of high-resolution spatio-temporal observations. This is particularly the case in the central Arctic cryosphere due to the presence of extensive cold, bright snow and ice surfaces coupled with widespread cloud cover.

This study addresses the observational data gap and provides an opportunity to refine model simulations at different spatio-temporal scales. We achieve this by using total aerosol optical depth (AOD) datasets generated by the AEROSNOW algorithm over the extensive central Arctic cryosphere. AEROSNOW retrieves AOD data using top-of-atmosphere reflectance measurements obtained through the Advanced Along-Track Scanning Radiometer (AATSR) aboard the ENVISAT satellite, spanning from 2003 to 2011. AEROSNOW integrates an aerosol retrieval algorithm with a rigorous cloud masking scheme and intro-
duces a novel quality flagging methodology tailored for the central Arctic region (≥ 72°N).

Using the AEROSNOW retrieved dataset for the central Arctic, we evaluate different models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6). Our results show significant differences in the spatio-temporal aerosol load and its annual and seasonal variations with precipitation. In particular, there is a decrease in aerosol loading that coincides with increased precipitation along the northern periphery of Alaska and the Bering Sea.

Significant discrepancies and variations of up to 6.2 mm/day in precipitation are observed between models, with higher aerosol loading leading to lower precipitation and vice versa. Furthermore, the spatially averaged multi-model mean overestimates aerosol concentrations in spring and underestimates them in summer compared to satellite observations. The CMIP6 models do not reproduce the seasonal variations in aerosol distribution seen with AEROSNOW, particularly an increase in aerosol loading during the summer coinciding with the sea ice retreat cycle. These discrepancies may be due to the lack of advanced natural aerosol formation mechanisms in the models, as a consequence of Arctic warming, and exposure to open
ocean emissions.

In summary, our study has led us to speculate that as model sophistication increases, modelled aerosol processes become increasingly uncertain. Ultimately, this investigation has the potential to elucidate the critical link between aerosols and the prevailing rain-dominated Arctic conditions under ongoing Arctic warming in future CMIP projects.

How to cite: Swain, B., Marco, V., Adrien, D., Luca, L., Sachin S., G., Hartmut, B., and John P., B.: Assessing Model simulation for central Arctic aerosol load by usingAEROSNOW dataset: Relevance for precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19084, https://doi.org/10.5194/egusphere-egu24-19084, 2024.

EGU24-19429 | ECS | Posters on site | AS3.10

Local and long-range transported sources of natural aerosols in southern Greenlandic fjord systems 

Joanna Dyson, Nora Bergner, Lionel Favre, Benjamin Heutte, Julian Weng, Patrik Winiger, Athanasios Nenes, Kalliopi Violaki, and Julia Schmale

The Arctic is warming up to four times faster than the global average with fragile fjord ecosystems in the relatively warm Southern Greenland being especially sensitive to changes across various facets of the environment. With longer and warmer summer melt periods leading to increased glacial melt with marine and land-terminating glaciers slowly receding, the potential of sediments from newly exposed glacial outwash plains to be aerosolized increases. At the same time biological productivity in the ocean is changing. Hence, the composition and sources of atmospheric aerosols responsible for the formation of clouds in this region are evolving and we expect this to influence both the cloud condensation nuclei (CCN) and Ice Nucleating Particle (INP) populations. Given the complex terrain and mixture of ice, ocean and land in fjord systems, the dispersion of aerosols and gases originating at the surface is subject to lower atmosphere stability and dynamics before they can reach cloud level. 

In this presentation, we will show results from a comprehensive and extensive field campaign in the Kullajeq province of Southern Greenland in June-August 2023. We will present vertical aerosol size distributions, particle number concentrations and absorption measurements taken using a tethered balloon in addition to complementary ground based online aerosol measurements. Two key sources of aerosols will be discussed: near-daily local new particle formation (NPF), and long-range transported Canadian wildfire plumes. We will explore the following questions: Are aerosols from fjords and increased biological productivity the source of the frequent NPF observed in Narsaq, and how do aerosols from distant sources such as Canadian biomass burning effect the aerosol population in Southern Greenland?

How to cite: Dyson, J., Bergner, N., Favre, L., Heutte, B., Weng, J., Winiger, P., Nenes, A., Violaki, K., and Schmale, J.: Local and long-range transported sources of natural aerosols in southern Greenlandic fjord systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19429, https://doi.org/10.5194/egusphere-egu24-19429, 2024.

EGU24-20480 | ECS | Posters on site | AS3.10

The sensitivity of cloud micro- and macrophysical properties to cloud microphysics parameterisations and simulation setup 

Maor Sela, Philipp Weiss, and Philip Stier

The climate impact and radiative effect of clouds and aerosols are significant. Both are among the most considerable sources of uncertainties in the climate system and in modelling the climate system. This arises not only from the fundamental uncertainty in cloud microphysics processes but also from their representation in models, and in particular in Cloud-Resolving Models (CRMs). CRMs are powerful tools for weather prediction, climate study, and investigating aerosol-cloud interactions at regional and global scales. However, they introduce a substantial degree of uncertainty due to model construction and parameterisation. To further investigate the sources of uncertainty in CRMs, we isolate two key aspects: the model's configuration (global and regional) and the employed cloud microphysics scheme (single- and double-moment schemes). Then, for each key aspect, we compare the simulated data to identify any discrepancies.
We present results from regional simulation with ICON-Sapphire in limited area mode. The region we focused on in this study is the Amazon basin, using a horizontal resolution of about 1.2 km and a time period of 8 days. First, we compare results obtained using both single- and double-moment bulk microphysics schemes, maintaining consistency in other simulation parameters. Then, we compare results obtained from both regional and global simulations utilising the single-moment bulk microphysics scheme, again maintaining consistency in other simulation parameters. 
We find that the double-moment cloud microphysics scheme yields increased ice levels and reduced precipitation rates compared to the single-moment cloud microphysics scheme. We also find that the Amazonian diurnal cycle of precipitation rate, ice, and liquid water paths is more pronounced in the global runs compared to the regional runs.
These results and other results that we will present may have implications on global radiation balance in global km-scale climate models.

How to cite: Sela, M., Weiss, P., and Stier, P.: The sensitivity of cloud micro- and macrophysical properties to cloud microphysics parameterisations and simulation setup, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20480, https://doi.org/10.5194/egusphere-egu24-20480, 2024.

EGU24-20572 | Orals | AS3.10 | Highlight

Aerosol effects on convective clouds in global km-scale models – from idealised aerosol perturbations to explicit aerosol modelling 

Philip Stier, Philipp Weiss, Ross Herbert, and Maor Sela

Aerosol effects on convective clouds and climate mediated via radiative and microphysical perturbations remain highly uncertain. Microphysical perturbations are generally not included in current climate models due to the simplified representation of convective clouds in existing parameterisations. Progress has been made through regional cloud resolving modelling, however such simulations often neglect energy and water budget constraints and the coupling to larger scales.

The emergence of global km-scale climate models provides a significant opportunity to advance our understanding of aerosol-convection interactions. Here we present results from a hierarchy of global km-scale atmospheric model simulations using ICON, investigating aerosol effects on convective clouds. Idealised model simulations, in which aerosols are prescribed as fixed plumes of radiative properties, with an optional associated semi-empirical scaling of droplet number perturbations, provide fascinating insights into the physical processes underlying aerosol effects on convection and into the interaction of local perturbations with the larger scale dynamics – but neglect key aerosol-convection interactions. These simulations highlight the importance of the radiatively mediated pathway for tropical convective clouds, with significant impacts on the diurnal cycle of cloud properties and precipitation over the Amazon and the Congo basin – and interactions with the large-scale dynamics for perturbations over the Pacific warm pool region.

We contrast our results from idealised simulations with simulations including explicit aerosols, enabled by a novel reduced complexity aerosol scheme suitable for global km-scale models, HAM-Lite. Comparison of the idealised simulations with prescribed aerosol perturbations and the simulations with explicit aerosols, provides new insights into the complexity of aerosol-convection interactions. This study provides a testbed for a future global km-scale model intercomparison project focusing on aerosol effects as part of the GEWEX Aerosol Precipitation (GAP) initiative.

How to cite: Stier, P., Weiss, P., Herbert, R., and Sela, M.: Aerosol effects on convective clouds in global km-scale models – from idealised aerosol perturbations to explicit aerosol modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20572, https://doi.org/10.5194/egusphere-egu24-20572, 2024.

EGU24-21153 | Orals | AS3.10 | Highlight

Nonlinearity of the cloud response postpones climate penalty of mitigating air pollution in polluted regions 

Hailing Jia, Johannes Quaas, and Otto Hasekamp

Aerosol–cloud interactions contribute substantially to uncertainties in anthropogenic forcing, in which the sensitivity of cloud droplet number concentration (Nd) to aerosol plays a central role. Here we use satellite observations to show that the aerosol–Nd relation (in log–log space) is not linear as commonly assumed. Instead, the Nd sensitivity decreases at large aerosol concentrations due to the transition from aerosol-limited to updraft-limited regime, making the widely used linear method problematic. The similar nonlinear behavior is also observed in weekly cycles; specifically, polluted conditions exhibit a reduced amplitude of weekly cycles in Nd compared to clean conditions with similar aerosol perturbations.  A sigmoidal transition is shown to adequately fit the data. When using this revised relationship, the additional warming that arises from air pollution mitigation is delayed by two to three decades in heavily polluted locations, compared to the linear relationship. This cloud-mediated climate penalty will manifest markedly starting around 2025 in China and 2050 in India after applying the strongest air quality policy, underlining the urgency of mitigating greenhouse gas emissions.

How to cite: Jia, H., Quaas, J., and Hasekamp, O.: Nonlinearity of the cloud response postpones climate penalty of mitigating air pollution in polluted regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21153, https://doi.org/10.5194/egusphere-egu24-21153, 2024.

EGU24-21392 | Orals | AS3.10

Cloud condensation nuclei concentrations derived from the CAMS reanalysis 

Karoline Block, Mahnoosh Haghighatnasab, Daniel G. Partridge, Philip Stier, and Johannes Quaas

Determining number concentrations of cloud condensation nuclei (CCN) is one of the first steps in the chain in analysis of cloud droplet formation, the direct microphysical link between aerosols and cloud droplets, and a process key for aerosol-cloud interactions (ACI). 

Here, we present a new CCN dataset (https://doi.org/10.26050/WDCC/QUAERERE_CCNCAMS_v1) which combines aerosol modeling with observations to better explore magnitude, source, temporal and spatial distribution of CCN numbers. The dataset features 3-D CCN number concentrations of global coverage for various supersaturations and aerosol species covering the years from 2003 to 2021 with daily frequency.

CCN are derived based on aerosol mass mixing ratios from the latest Copernicus Atmosphere Monitoring Service reanalysis (CAMSRA) in a diagnostic model that uses CAMSRA aerosol properties and a simplified kappa-Köhler framework which are suitable for global models. The emitted aerosols in CAMSRA are not only based on input from emission inventories using aerosol observations, they also have a strong tie to satellite-retrieved aerosol optical depth (AOD) as this is assimilated as a constraining factor in the reanalysis. Thus, this dataset is one of its kind as it offers lots of opportunities to be used for evaluation in models and in ACI studies.

We will illustrate the distribution and variability of such derived CCN, evaluate them with observations and have a look at some specific features this dataset provides.

Data description paper (preprint): https://essd.copernicus.org/preprints/essd-2023-172/

How to cite: Block, K., Haghighatnasab, M., Partridge, D. G., Stier, P., and Quaas, J.: Cloud condensation nuclei concentrations derived from the CAMS reanalysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21392, https://doi.org/10.5194/egusphere-egu24-21392, 2024.

EGU24-21400 | Orals | AS3.10 | Highlight

A dynamical-systems perspective on aerosol-stratocumulus interactions 

Franziska Glassmeier and Benjamin Hernandez

The evolution of stratocumulus cloud decks is governed by three timescales: the large-scale evolution of the boundary layer, the mesoscale evolution of liquid water path and cloud fraction, and the microscale processes of cloud microphysics and aerosol-cloud interactions. Our quantitative understanding of aerosol-cloud-climate cooling is especially challenged by the mesoscale response of stratocumulus decks to aerosol perturbations. This response can on the one hand be muted because cloud adjustments partially compensate an initial effect, a feature known as buffering or resilience. On the other hand, stratocumulus may respond by drastic transitions between the closed- and open-cell morphologies or into the shallow-cumulus regime. We will conceptualize this behavior from the perspective of dynamical-systems theory. Our description can be visualized as a quasi-potential landscape. This landscape quantifies the resilience of mesoscale cloud states to perturbations and charts transition pathways. Building on this, we will explore implications for the quantification of adjustments, especially in cloud fraction.

How to cite: Glassmeier, F. and Hernandez, B.: A dynamical-systems perspective on aerosol-stratocumulus interactions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21400, https://doi.org/10.5194/egusphere-egu24-21400, 2024.

EGU24-763 | ECS | Posters on site | BG1.1

The influence of pyrolysis time, moisture, and plant species on carbon bridgehead fraction of charcoal 

Vinothan Sivapalan and William Hockaday

Paleofire reconstructions are a challenging endeavor primarily due to the numerous factors involved in wildfire frequency, behavior, and regimes. These factors include, but are not limited to fuel composition, moisture, soil types, climate/weather conditions, and topographical features. Therefore, development of robust wildfire proxies requires vigorous experimental testing for multiple variables. Here, we explore the influence of pyrolysis time, moisture, and plant species on a novel proxy for fire intensity—carbon bridgehead fraction of charcoal. Experimentally, we have produced charcoals from three native Texas plants: live oak (Quercus sp.), Ashe juniper (Juniperus ashei), and broomsedge bluestem (Andropogon virginicus) under a range of temperature (300-700°C), moisture (0-100% moisture capacity), and time (0-1 hr) conditions in a tube furnace. Samples were analyzed using solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy with two experiments to calculate carbon bridgehead fraction: cross polarization – magic angle spinning (CP-MAS) to quantify total aromatic carbon and dipolar dephasing (DD) to quantify aromatic bridgehead carbon. Results reveal significant differences between vegetation types, with moisture delaying or slowing the rate of carbon bridgehead formation. Relationship between carbon bridgehead fraction and time are less clear and may be influenced by the formation of pyrolysis byproducts (such as pyroligneous acids and free radicals) and/or signal losses in the cross-polarization spectra. To assess the influence of these factors on carbon bridgehead fraction we plan to conduct additional analyses on our experimental charcoals, including electron paramagnetic resonance (EPR) spectroscopy to quantify the free radicals in samples and C elemental analysis to assess carbon observability by NMR. Future work involves ground truthing the proxy to modern wildfires and subsequently applying it to paleorecords.

How to cite: Sivapalan, V. and Hockaday, W.: The influence of pyrolysis time, moisture, and plant species on carbon bridgehead fraction of charcoal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-763, https://doi.org/10.5194/egusphere-egu24-763, 2024.

EGU24-1123 | ECS | Orals | BG1.1

Assessment of ecohydrological response of Himalayan Forest ecosystems to  forest fires 

Nagashree Ge and Ashutosh Sharma

Himalayan forests boast an incredible biodiversity, harboring a wide range of flora and fauna and playing a significant role in regulating water resources. Forest fires are one of the disturbances which constitute a major force influencing, even determining, the structure and functions of ecological components-populations, communities, and ecosystems. The ability to withstand disturbance is defined as resistance whereas resilience is the capacity to recover from disturbance. These two terms define the ecohydrological response to forest fire. This study insights on how remote sensing technique can be utilized for the measurement of ecohydrological response of a large extent of region subjected to forest fire based on resistance-resilience framework and how further implementation of these measures would help to know the changes in the interaction been vegetation and water cycle. Normalized burn ratio (NBR) is used to quantify the response.  The outcome of the study reveals that deciduous needled leaf forests are subjected frequently to forest fires compared to other classes of forests during 2002-2022. The regions considered for study showed moderate to high range of resistance but low resilience, signifying the region has gained and lost vegetations in the post-fire. There was a variation in rainfall and run-off occurred during the post-fire year for different burn severities. The present approach has the potential to quantify the response of ecosystems to the forest fire and related effects on hydrology of the region.

How to cite: Ge, N. and Sharma, A.: Assessment of ecohydrological response of Himalayan Forest ecosystems to  forest fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1123, https://doi.org/10.5194/egusphere-egu24-1123, 2024.

From March to April, widespread forest fires and agro-residue burning frequently occur in Southeast Asia, which release large amounts of gas species and aerosols and impact air quality over the wide source and downwind regions. In this study, we investigated the impact of biomass burning (BB) over Southeast Asia on particulate matter concentrations and aerosol properties in downwind areas of the low-latitude plateau from 1 March to 30 April 2019, with a focus on a typical pollution event in Kunming (KM), the capital of Yunnan Province, by using a wide variety of observations from the Chenggong ground monitoring station in Yunnan University, an air quality network in China, satellite retrievals and ERA-5 reanalysis data and numerical simulation. A regional pollution event contributed by BB pollutants from Southeast Asia and the India-Myanmar trough occurred in Yunnan Province on 31 March to 1 April 2019, which was the only typical pollution event that pollution transmission ran through central Yunnan Province from south to north since 2013, when the Airborne Pollution Action Plan was unveiled by China government. The daily mean PM2.5, PM1, and black carbon concentrations increased by 73.3 μg m−3 (78%), 70.5 μg m−3 (80%), and 7.7 μg m−3 (83%), respectively, and the scattering and absorbing coefficients increased by 471.6 Mm−1 and 63.5 Mm−1 , respectively, at the Chenggong station. The southwest winds exceeding 2 km vertically thick appeared in front of the India-Myanmar trough over the fire regions, pushing BB plumes northward into Yunnan Province. The model results show that 59.5% of PM2.5 mass produced by BB in Yunnan Province was sourced from the Myanmar-Thailand border, and 29.3% was from western Myanmar at a lower altitude (<4.9 km), which indicated that BB in the Myanmar-Thailand border was the dominant contributor.

How to cite: Fan, W., Li, J., Han, Z., and Wu, J.: Impacts of biomass burning in Southeast Asia on aerosols over the low-latitude plateau in China: an analysis of a typical pollution event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1471, https://doi.org/10.5194/egusphere-egu24-1471, 2024.

EGU24-1756 | ECS | Orals | BG1.1

Direct Estimation of Carbon Emissions from High Latitude Fires: The Adapted FREM Approach 

Will Maslanka and Martin Wooster

Landscape fires are a widespread natural phenomenon that directly influences carbon cycling through the combustion of organic material. Space-based remote sensing, including Active Fire (AF), remains the only way to estimate wildfire activity accurately on the regional-to-global scale. Fire emission inventories generally fall into two categories. “Bottom-up” methodologies rely on observations of AF counts, Fire Radiative Power (FRP), or burned area to estimate the amount of biomass burned, or “Top-down” methodologies, which directly relate observations of FRP to landscape fire emission estimates. Bottom-up methods tend to have a reliance on uncertain parameters, such as pre-fire fuel load and combustion completeness, or a conversion factor between FRP and fuel consumption rate. The Fire Radiative Energy Emission (or FREM) approach is one such top-down methodology that has removed such a reliance, by directly relating FRP to observed rates of emissions, such as CO or aerosols, but has so far been used with geostationary FRP data only. Whilst very effective at lower latitudes, due to the poor spatial resolution and extreme viewing geometry of geostationary data at higher latitudes, the approach is not applicable for fires in this region in its current format. However, by using polar orbiting FRP data and making use of the high latitude orbital convergence, this study looks to adapt the FREM approach to deliver direct estimation of carbon emissions for high latitude (>60°N) landscape fires. We use direct observations of FRP, from Suomi-NPP, NOAA-20 and MODIS, along with observations of Total Column Carbon Monoxide from TROPOMI onboard Sentinel-5P. A series of cloud-free plumes and associated FRP data were identified in Deciduous and Evergreen Needleleaf biomes in North America and Russia in the summers of 2019 – 2023. The resulting emission coefficients and emission totals were compared to pre-existing top-down and bottom-up emission coefficients and totals from the FEER, GFAS, and GFED inventories for high latitude fires between 2018-2023. This adapted FREM approach is shown to provide direct emission estimates without recourse to significant assumptions and can do so in real time – opening up a new avenue for real-time fire emission estimation at high latitudes.

How to cite: Maslanka, W. and Wooster, M.: Direct Estimation of Carbon Emissions from High Latitude Fires: The Adapted FREM Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1756, https://doi.org/10.5194/egusphere-egu24-1756, 2024.

EGU24-2099 | ECS | Orals | BG1.1

Exploring the effect of vegetation photosynthesis phenology on wildfire dynamics 

Gengke Lai, Jialing Li, Jun Wang, Chaoyang Wu, Yongguang Zhang, Constantin M. Zohner, and Josep Peñuelas

2023 has witnessed a record-breaking extreme wildfire season in Canada from coast to coast, following closely to the unprecedented wildfire outbreaks in 2019/20 Australia and 2021 Siberia, causing far-reaching threats on terrestrial carbon stock, air quality, and human society. The heightened wildfire activity in specific regions prompts us to rethink the underlying factors driving the global wildfire dynamics. Climate change has been recognized as an important factor in amplifying wildfire risk, mainly through increasing temperature and reducing relative humidity. However, the role of vegetation productivity and phenology on wildfire dynamics remains elusive, even though which can exacerbate or mitigate the climate-induced fire risk. Importantly, changes in vegetation phenology can cause biophysical feedback to the climate system and land surface by modulating the exchanges of water and energy between land and the atmosphere. Considering the climate feedback of vegetation phenology, we hypothesize that peak photosynthesis timing (PPT) can contribute to wildfire activity. To explore it, we provide comprehensive analyses using multiple satellite-based photosynthesis observations from solar-induced chlorophyll fluorescence (SIF), and wildfire activity from national fire perimeters and MODIS global burned area records from 2001 to 2018, as well as diverse methodologies and models. In response to changes in various biological and climatic factors, we find PPT has advanced 1.10 ± 0.57 days per decade at a global scale. This earlier PPT acts to expand the extent of wildfires, with an increase in the global average burned fraction by 0.021% (~2.20 Mha) for every additional day of PPT advancement. Satellite observations and the Earth system modeling consistently reveal that this expansion is attributed to the intensified drought conditions during the potential fire season, induced by the earlier PPT that can modulate the global patterns of temperature, precipitation, and surface soil moisture. Furthermore, current fire-vegetation models participating in the FireMIP project underestimate the sensitivity of burned area to PPT, despite reproducing their negative correlation. Our findings highlight the importance of climate-vegetation-fire feedback loops in future prediction of wildfire dynamics and the strategy of climate change adaptation and mitigation.

How to cite: Lai, G., Li, J., Wang, J., Wu, C., Zhang, Y., Zohner, C. M., and Peñuelas, J.: Exploring the effect of vegetation photosynthesis phenology on wildfire dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2099, https://doi.org/10.5194/egusphere-egu24-2099, 2024.

EGU24-4071 | ECS | Posters on site | BG1.1 | Highlight

The Influence of Climate Teleconnections on Global Burned Area 

Yuquan Qu, Harry Vereecken, Sander Veraverbeke, and Carsten Montzka

Wildfires are known to be controlled by fuels and weather. Climate teleconnections may influence wildfires by altering fuel availability and fire weather. In this study, we used the random forest approach to systematically detect relationships between teleconnection climate indices (CIs) and burned area while accounting for different lag times. Results indicate that burned area is especially modulated by climate teleconnections in Africa and Australia. The Tropical Northern Atlantic (TNA) pattern was the most influential CI for the global burned area, followed by the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the Pacific–North American (PNA) pattern. To study pathways of how teleconnections affect the burned area, we distinguished two classes of fire drivers: bottom-up fuel availability and top-down weather conditions. Bottom-up fuel drivers showed higher correlation with CIs than top-down weather drivers and served as mediators between teleconnections and wildfires. The mediating effect of top-down weather drivers was only apparent in specific seasons. Our study highlights that in teleconnection-wildfire hotspot regions, knowledge of the relation between CIs and drivers of wildfires could improve long-term wildfire predictability. We recommend that bottom-up fuel drivers should also be integrated into wildfire predictive frameworks as they play an important mediating role in linking teleconnections and wildfires.

How to cite: Qu, Y., Vereecken, H., Veraverbeke, S., and Montzka, C.: The Influence of Climate Teleconnections on Global Burned Area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4071, https://doi.org/10.5194/egusphere-egu24-4071, 2024.

EGU24-5191 | ECS | Orals | BG1.1 | Highlight

Impacts of land use change and interannual climate variability on biomass burning emissions, air quality and public health in Amazon 

Tsin Hung Leo Ng, Amos P. K. Tai, Stephen Sitch, Luiz Aragao, and Shixian Zhai

Biomass burning in Amazon Basin has a significant impact on regional climate and deteriorates regional air quality, which poses a threat to human and ecosystem health. The fire-induced pollution worsens during dry season (Jul to Nov) and shows a strong seasonal variation. Past research has demonstrated that the occurrence of wildfires in Amazon is not only influenced by deforestation, but also interannual climate variability, particularly droughts. Here we estimate the impacts of deforestation and droughts on fire emissions and regional air quality between 2010 to 2015 by using Global Fire Emission Database Version 4 (GFED v4) to drive a global 3-D atmospheric chemical transport model GEOS-Chem High Performance (GCHP) and further examine the effect of PM2.5 and O3 on premature mortality across the region. By comparing the “fire-on” and “fire-off” scenarios, we find that biomass burning alone in normal years (2011 and 2013) contributes 5.7 μg m-3 (47.6% of the total concentration) PM2.5, 0.08 ppm (46.3%) CO, 0.03 ppb (85.0%) NOx, and 9.5 ppb (41.2%) O3; and these numbers during drought years (2010, 2012, 2014 and 2015) increase to 19.6 μg m-3 (74.7%) for PM2.5, 0.20 ppm (67.0%) for CO, 0.19 ppb (97.4%) for NOx, and 15.6 ppb (52.0%) for O3. We find that these pollutants from wildfires mainly concentrate in the south-eastern Amazon and then transport southward, thus strongly impacting public health in the downwind regions. We estimate that premature mortality due to long-term exposure to particulate matter and ozone by applying the simulated concentration to the concentration-response functions from the European Environment Agency. We find that ~8,500 and ~10,400 deaths per year are attributable to PM2.5 and O3 exposure for 2010-2015 respectively. During drought years, we discover there are 2.8% and 3.4% more deaths than normal years for PM2.5 and O3 exposure. Our study shows the significance of biomass burning emissions in shaping the air quality in the Amazon region, and highlights the impact of drought events on enhancing biomass emissions, worsening regional air quality and causing public health issues. Therefore, it is important to address the underlying causes of biomass burning in the Amazon, such as deforestation and land use change, and droughts, to protect the region's ecosystems and mitigate the impacts of climate change.

How to cite: Ng, T. H. L., Tai, A. P. K., Sitch, S., Aragao, L., and Zhai, S.: Impacts of land use change and interannual climate variability on biomass burning emissions, air quality and public health in Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5191, https://doi.org/10.5194/egusphere-egu24-5191, 2024.

EGU24-5236 | ECS | Posters on site | BG1.1 | Highlight

Are there lightning Fires in the Amazon Rainforest? 

Cunhui Zhang, Thomas Janssen, Matt Jones, and Sander Veraverbeke

Tropical rainforests have exceptionally high biodiversity and store large amounts of carbon in biomass. However, large and frequent fires across tropical rainforests in the last decades threaten the ecosystem integrity of these ecosystems. The general belief is that fires in the Amazon rainforest are all human-ignited and that lightning fires do not occur in rainforests due to the predominant wet conditions. However, recent research indicates the possibility of lightning fires in tropical rainforests. Here, we aim to investigate the occurrence of lightning-ignited fires in the Amazon rainforest, a topic that has been largely overlooked in the current understanding of fire dynamics in this biome. We collected and analyzed data on lightning strikes, fire occurrences, and weather patterns derived from satellite imagery and climate datasets. The objective is to detect, quantify, and characterize lightning fires in the Brazilian Amazon rainforests, thereby providing new insights into the natural fire regime of this crucial ecosystem.

How to cite: Zhang, C., Janssen, T., Jones, M., and Veraverbeke, S.: Are there lightning Fires in the Amazon Rainforest?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5236, https://doi.org/10.5194/egusphere-egu24-5236, 2024.

EGU24-5348 | Posters on site | BG1.1

Wetlands in monoculture forests – how fire activity and different forest management strategies impact Sphagnum-dominated peatlands 

Katarzyna Marcisz, Mariusz Bąk, Mariusz Lamentowicz, Piotr Kołaczek, Thomas Theurer, Paweł Matulewski, and Dmitri Mauquoy

Monoculture forests are now a dominant forest type in Europe. Created for easier management and increased timber production, they are now witnessing many disturbances due to climate change, such as more frequent windthrows, droughts, fires or insect outbreaks. The functioning of forests impacts other elements of the landscape, including peatlands, which also have been affected by various natural and anthropogenic disturbances (e.g., drainage) that make them more vulnerable to drying and burning. We aim to recognize how peatland functioning has changed along with changing forest management strategies. For this we studied a Sphagnum-dominated peatland located in the Tuchola Pinewoods – one of the largest Scots pine (Pinus sylvestris) monoculture forest in Poland. We used high-resolution multi-proxy palaeoecology including pollen, plant macrofossils and testate amoebae, additionally focusing on a wide range of charcoal analyses: charcoal counts, charcoal morphological types, and Raman spectroscopy. Our results show that the studied peatland experienced several critical transitions in vegetation composition and hydrology over the last 600 years when new forest management techniques were introduced. A reduction in fire activity led to a dominance of Sphagnum and increased peat accumulation rates. Establishment of a monoculture forest further impacted the site and stabilized Sphagnum growth and acidity levels. We believe that these results can be helpful for the improvement of conservation planning for peatlands located in forested areas, especially in monoculture forests.

The study is funded by the National Science Centre, Poland (2020/39/D/ST10/00641).

How to cite: Marcisz, K., Bąk, M., Lamentowicz, M., Kołaczek, P., Theurer, T., Matulewski, P., and Mauquoy, D.: Wetlands in monoculture forests – how fire activity and different forest management strategies impact Sphagnum-dominated peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5348, https://doi.org/10.5194/egusphere-egu24-5348, 2024.

EGU24-5494 | ECS | Orals | BG1.1 | Highlight

Half of global burned area is due to managed anthropogenic fire: findings from a coupled socio-ecological modelling approach  

Oliver Perkins, Matthew Kasoar, Apostolos Voulgarakis, Tamsin Edwards, and James Millington

Globally, vegetation fires are a key component of many ecosystems and have substantial impacts on carbon emissions. Yet humans also use and manage fires for a huge range of purposes around the world, dependent on numerous social and biophysical factors. Existing representations of anthropogenic fire in dynamic global vegetation models (DGVMs) have been highly simplified, with readily available global variables (e.g. population density) used to estimate numbers of anthropogenic ignitions. Here, we present results from a novel coupled socio-ecological modelling approach to improve understanding of how human and biophysical factors combine to drive the spatio-temporal distribution of global fire regimes. Specifically, we present the integration of two process-based models. The first is the Wildfire Human Agency Model (WHAM!1), which draws on agent-based approaches to represent anthropogenic fire use and management. The second model is JULES-INFERNO2, a fire-enabled DGVM, which takes a physically-grounded approach to the representation of vegetation-fire dynamics.

The new WHAM-INFERNO model ensemble suggests that as much as half of all global burned area is generated by managed anthropogenic fires - typically small fires that are lit and spread according to specific land use objectives (such as crop residue burning). Furthermore, we demonstrate that including representation of managed anthropogenic fires in a coupled socio-ecological simulation can improve understanding of the biophysical drivers of unmanaged wildfires, by allowing clearer recognition of the role of anthropogenic land management in global fire regimes. Hence, WHAM-INFERNO is applied to understand how landscape fragmentation, wider land use change, and changes in human fire management have together led to observed recent declines in global burned area despite the warming climate. Overall, findings presented here have substantial implications for understanding of present and future fire regimes, indicating that changes to socio-economic systems are at least as important a consideration as climate change.  

1. Perkins, O., Kasoar, M., Voulgarakis, A., Smith, C., Mistry, J., and Millington, J. (2023). A global behavioural model of human fire use and management: WHAM! v1.0. EGUsphere, 1–42. 10.5194/egusphere-2023-2162.

2. Mangeon, S., Voulgarakis, A., Gilham, R., Harper, A., Sitch, S., and Folberth, G. (2016). INFERNO: a fire and emissions scheme for the UK Met Office’s Unified Model. Geosci. Model Dev. 9, 2685–2700. 10.5194/gmd-9-2685-2016.

How to cite: Perkins, O., Kasoar, M., Voulgarakis, A., Edwards, T., and Millington, J.: Half of global burned area is due to managed anthropogenic fire: findings from a coupled socio-ecological modelling approach , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5494, https://doi.org/10.5194/egusphere-egu24-5494, 2024.

EGU24-6077 | ECS | Orals | BG1.1

Updated Exposure Estimate for Indonesian Peatland Fire Smoke using Network of Low-cost Purple Air PM2.5 sensors 

Ailish M Graham, James B McQuaid, Thomas E L Smith, Hanun Nurrahmawati, Devina Ayona, Hasyim Mulawarman, Chaidir Adam, Dominick V Spracklen, Richard Rigby, and Shofwan A B Choiruzzad

Air pollutant emissions from wildfires on Indonesian peatlands lead to poor regional air quality across south-east Asia. Fine particulate matter (PM2.5) emissions are particularly high for peat fires leading to substantial population exposure to PM2.5. Despite this, air quality monitoring is limited in regions close to peat fires meaning the impacts of peatland fires on air quality is poorly understood and it is difficult to evaluate predictions from atmospheric chemistry models. To address this, we deployed a network of low-cost (Purple Air) PM2.5 sensors at 8 locations across Central Kalimantan, where peat fires are frequent. The sensors measured indoor and outdoor PM2.5 concentrations during August to December 2023. During the haze season (September 1st to October 31st), daily mean outdoor concentrations were 120 mg m-3 but peaked at >400 mg m-3. Indoor PM2.5 concentrations were only ~10% lower (mean 110 mg m-3), indicating that is difficult for the population to reduce their exposure to PM2.5 from fires. The reduction in mean PM2.5 concentrations between outdoor and indoor environments was larger in urban locations (-11%) compared with rural locations (-3%), suggesting urban housing may provide better protection from outdoor air pollution. To generate an updated assessment for the population’s exposure to peatland fire PM2.5 we combine the information from monitoring both indoor and outdoor PM2.5 concentrations with modelled ambient (outdoor) PM2.5 concentrations from the WRF-Chem atmospheric chemistry transport model. Our updated exposure assessment accounts for the population’s personal exposure to peatland fire PM2.5 for the first time.

How to cite: Graham, A. M., McQuaid, J. B., Smith, T. E. L., Nurrahmawati, H., Ayona, D., Mulawarman, H., Adam, C., Spracklen, D. V., Rigby, R., and Choiruzzad, S. A. B.: Updated Exposure Estimate for Indonesian Peatland Fire Smoke using Network of Low-cost Purple Air PM2.5 sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6077, https://doi.org/10.5194/egusphere-egu24-6077, 2024.

EGU24-6624 | ECS | Orals | BG1.1

Excessive fire occurrence in Romania from 2001 to 2022: Trends and drivers across ecoregions and land cover classes 

Till Mattes, Irene Marzolff, and Angelica Feurdean

Wildfire is an integral part of temperate ecosystems, but human activities have significantly altered fire regimes, including frequency, size, intensity and seasonality. Romania, located in central-eastern Europe, recently exhibited the highest biomass burning in Europe. However, little is known of the trends and determinants of fire recurrence, apart from the common use of fire to clear crop residues on arable land. This study utilizes satellite-based fire data (FIRMS) from 2001 to 2022 and land cover maps (CORINE) to investigate temporal trends in fire occurrence across ecoregions and land cover types in Romania and identify those most susceptible to fire.

Over 2001-2022, Romania witnessed a total of 0.44 fires/ km² averaging 0.02 fires/km²/yr. Our analysis revealed a declining trend in fire occurrence along an elevation gradient, from plains to hills, plateaus and mountains, aligning with the prevalence of the dominant land cover classes and climatic gradients. Agricultural land cover types demonstrated the highest fire incidence, with arable land exhibiting the highest rate (0.04 fires/km²/yr) and forests the lowest (below 0.01 fires/km²/yr). Following the accession of Romania to the EU in 2007 and the prohibition of agricultural fires, a reduction in burning on arable land (crop residues) can be observed, while the use of fire in other agricultural classes persisted or even increased, indicating a more complex effect of socio-economic developments on fire pattern. Specifically, areas more marginal for agriculture, such as complex agricultural fields interspaced with housing and natural vegetation continued to employ fire as a management tool.

Natural land cover classes, such as wetlands principally occupying the Danube Delta (0.06 fires/km²/yr) and natural grasslands (0.01 fires/km²/yr), also experienced substantial fire occurrences and an intensification in more recent periods. Given the rarity of naturally ignited fires (lightning) in Romania, the intentional use of fire to clear dry reed biomass for land regeneration appears to be prevalent also in moist areas. Remarkably, broadleaved and mixed forests burned more frequently than coniferous forests despite the latter having traits to convey high flammability and burn with high frequency. This feature suggests that fires in broadleaved forests, predominant at low and mid elevations, likely expanded from neighbouring agricultural lands.

Crucially, our analysis highlights that years with elevated fire occurrence coincide with extreme droughts and heatwaves (e.g., 2012, 2015), emphasizing the influence of extreme climate conditions in accelerating fire episodes and the spread of fires initiated in agricultural areas into natural and semi-natural habitats. Given the substantial occurrence of fires in agricultural land but also in natural habitats, such as wetlands and grasslands in Romania, research investigating the risks and vulnerability of these habitats to fire should be prioritized.

How to cite: Mattes, T., Marzolff, I., and Feurdean, A.: Excessive fire occurrence in Romania from 2001 to 2022: Trends and drivers across ecoregions and land cover classes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6624, https://doi.org/10.5194/egusphere-egu24-6624, 2024.

Wildfires have become more prevalent in recent years because of climate change. Meanwhile wildfires, as a major type of biomass burning, could emit a large amount of black carbon (BC) and brown carbon (BrC) to the atmosphere. Since BC and BrC play important roles in climate change, air pollution and human health issues, it is necessary to research their physicochemical properties to evaluate their impacts on urban areas. Here we present BC mass concentration and absorption coefficients measured by aethalometer (AE43), combing with the chemical constitutions acquired by GC-MS, during the record-breaking 2023 wildfire season in Canada. The back-trajectory analysis indicated that the smoke mainly came from north Quebec where the wildfires took place. We demonstrated how BC and BrC emitted by wildfires could affect urban regions after long-range transport.

How to cite: Li, H. and Ariya, P.: Measurement of Physicochemical Properties of Black Carbon and Brown Carbon and the Impacts of Canada Record-Breaking Wildfires in Summer 2023 , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6761, https://doi.org/10.5194/egusphere-egu24-6761, 2024.

EGU24-7467 | ECS | Posters on site | BG1.1

The Impact of Wildfires on Atmospheric Nitrogen Deposition in the United States: A Multiple Linear Regression-based Analysis 

Jiangshan Mu, Yingnan Zhang, Chenliang Tao, Zhou Liu, Yu Zhao, Lei Zhang, Yuqiang Zhang, and Likun Xue

Nitrogen deposition can exert a significant impact on global ecosystems. The increased occurrence of natural factors such as wildfires are becoming more important in atmospheric deposition especially with the continued decreases of the anthropogenic emissions in developed countries. In this study, we investigate the mechanisms by which the increasingly frequent wildfires affect nitrogen deposition in the United States using comprehensive datasets and multiple linear regression (MLR) methods. We found a downward trend in nitrogen deposition in the U.S. (-0.09 kgN ha yr-1), mainly due to the decreases in oxidative nitrogen deposition (-0.1 kgN ha yr-1). In contrast, reduced nitrogen deposition showed a slight increase (0.02 kgN ha yr-1). Our preliminary results show that wildfires contributed ~10% to the U.S. domestic deposition overall, but the magnitudes and signs of impact vary geographically, depending on the frequency and intensity of wildfires and the dominant deposition types. On average across the U.S., wildfires predominantly negatively contribute to wet deposition, while their contributions to dry deposition is smaller or slightly positive. Specifically, wildfires enhance dry deposition in the western U.S. while inhibiting wet deposition in the southeastern U.S. Wildfires exert a suppressive effect on both oxidized and reduced forms of nitrogen deposition in the southeastern U.S. Our study highlights the significant influence of wildfires on nitrogen deposition, underscoring the need to consider wildfire events in environmental management and policy-making.

How to cite: Mu, J., Zhang, Y., Tao, C., Liu, Z., Zhao, Y., Zhang, L., Zhang, Y., and Xue, L.: The Impact of Wildfires on Atmospheric Nitrogen Deposition in the United States: A Multiple Linear Regression-based Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7467, https://doi.org/10.5194/egusphere-egu24-7467, 2024.

EGU24-7895 | ECS | Posters on site | BG1.1

Vegetation types influence fine-scale drought impact on land surface cooling and burn patterns in the Siberian coastal tundra 

Nils Rietze, Jakob Assmann, and Gabriela Schapeman-Strub

In 2020, the Northeastern Siberian lowland tundra faced an extreme drought and unprecedented wildfires. The burning of carbon-rich soils in this region can release large amounts of carbon, worsening climate change and Arctic warming.  However, we know little about of how droughts impact vegetation and how this vegetation might become fuel for large fires in the typically wet landscapes of the Northeastern Siberian lowland tundra. We studied the impact of the extreme summer drought in 2020 on the tundra vegetation and the resulting burn patterns in the Indigirka lowlands using a combination of in-situ, thermal, and multispectral remote sensing data from drone and high-resolution satellite imagery. The fine-scale vegetation types revealed increased landscape-wide drought susceptibility indicated by an overall loss of land surface cooling. This suggests a shift towards an energy budget dominated by sensible heat flux, which may feed back and intensify the heatwave.  Further, we found that mostly dry vegetation types were affected by fire in the NE Siberian coastal tundra, while wetter vegetation types did not burn, leading to a fine-scale heterogeneous burn pattern. Our results indicate that the enhanced drought susceptibility of vegetation types may have led to higher fire fuel connectivity of the tundra landscape. Consequently, this may have resulted in the large burn extents observed in 2019 and 2020. Our analysis is an effort toward the prediction of fire fuel connectivity and fire management in remote Arctic areas.

How to cite: Rietze, N., Assmann, J., and Schapeman-Strub, G.: Vegetation types influence fine-scale drought impact on land surface cooling and burn patterns in the Siberian coastal tundra, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7895, https://doi.org/10.5194/egusphere-egu24-7895, 2024.

EGU24-8017 | ECS | Posters on site | BG1.1

Combining stand-level and remote sensing data to model post-fire recovery of Mediterranean tree-forest communities – A case study in Spain. 

Raul Hoffren, Juan de la Riva, Darío Domingo, María Teresa Lamelas, Paloma Ibarra, Alberto García-Martín, and Marcos Rodrigues

Mediterranean forests are recurrently affected by wildfires. Fire activity is expected to accelerate in the future due to landscape homogenization, fuel accumulation, and climate warming. A key aspect to prevent and mitigate the negative impacts of wildfires on ecosystems is to understand the factors that govern the recovery of forest communities. This study analyzes the post-fire recovery potential of four representative Mediterranean tree-communities (Pinus halepensis, Pinus nigra, Pinus pinaster, and Quercus ilex) affected by large wildfires (> 500 ha) during the summer of 1994 in Spain. For this purpose, information collected in the field 25 years after the fires in 203 forest plots (131 burned and 72 unburned control plots) was coupled with remote sensing, geospatial, and forest inventory data, to build an empirical model capable of assessing recovery. Remote sensing data provided a proxy for burn severity, through the Composite Burn Index, and allowed modelling the local topography (slope and aspect) of the terrain. The geospatial data included climatic information on temperature and precipitation trends. These data were entered into the model, calibrated using Random Forest, to provide information on the degree of recovery, inferred from the similarity (in terms of vegetation height, aboveground biomass, species diversity) between the burned and unburned control plots. Results showed that only the 25% of the burned plots can be considered as recovered. The burn severity had a significant effect on the recovery albeit strongly modulated by local topography. Overall, the key features of the recovered plots were a low-to-moderate burn severity and a favorable topographical setting, especially the shading effect of steep northwestern slopes. Furthermore, a warmer and more humid climate improved the capacity of recovery. These results constitute a valuable tool for improving forest management and preserving ecosystem services.

How to cite: Hoffren, R., de la Riva, J., Domingo, D., Lamelas, M. T., Ibarra, P., García-Martín, A., and Rodrigues, M.: Combining stand-level and remote sensing data to model post-fire recovery of Mediterranean tree-forest communities – A case study in Spain., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8017, https://doi.org/10.5194/egusphere-egu24-8017, 2024.

Wildfires pose an increasing threat to boreal forest and tundra ecosystems in boreal North America (Alaska and northwestern Canada), as their frequencies rise under global warming. These fires exhibit strong interannual variability that is influenced by regional atmospheric circulation. However, potential impacts of remote boundary forcings on regional fires and the underlying mechanisms remain unclear. This study provides a comprehensive analysis on the impacts of spring sea surface temperature (SST) and sea ice on interannual variability of burned area in this region during fire season (summer) from 1997 to 2020 using GFED5 burned area, SST and sea ice concentration data from the Met Office Hadley Centre, and ERA5 reanalysis data. Results show that in spring a warmer SST in the East Pacific and reduction of sea ice in the northern Chukchi Sea lead independently to an increase in burned area in boreal North America. The correlation coefficients between the SST and sea ice factors with the burned area in boreal North America are 0.43 and –0.44 respectively. The SST-fire relationships can be explained as follows: A warm SST anomaly in the East Pacific triggers a northeastward-propagated Rossby wave, inducing a high-pressure anomaly over boreal North America in spring. Consequently, this circulation anomaly causes a higher surface temperature and thus vegetation growth or drying. As temperatures rise and lightning activity intensifies in summer, burned area increases. On the other hand, the process of sea ice affecting burned area is different. A reduction in sea ice coverage in the northern Chukchi Sea leads to a decrease in surface albedo, resulting in an increase in heat flux. The heat release persists from spring to summer and causes a high-pressure circulation anomaly in boreal North America in summer, which suppresses regional water vapor convergence and precipitation, reducing soil moisture and surface air humidity and increasing vapor pressure deficit (VPD) thereby promoting fuel flammability.

How to cite: Zhao, Z., Lin, Z., and Li, F.: Impacts of Spring East Pacific SST and Arctic Sea Ice on Interannual Variability of Summer Burned Area in boreal North America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8303, https://doi.org/10.5194/egusphere-egu24-8303, 2024.

EGU24-8506 | Orals | BG1.1

Anticipating future extreme wildfire events by coupling ignition and success of initial attack models 

Pere Joan Gelabert Vadillo, Adrian Jiménez Ruano, Fellice Catelo, and Marcos Rodrigues Mimbrero

In recent years, the EU Commission has enacted various firefighting policies to combat and diminish the adverse effects of wildfires. The Mediterranean area has experienced an observable extension of its wildfire season, coupled with rapid shifts in fire-weather dynamics, resulting in exceptionally severe wildfire occurrences. As of 2022, the EU has recorded an approximate total burned area of 792,902 hectares, with forests accounting for 66% of this figure (Rodrigues et al., 2023).

The main objective of this study is to anticipate extreme wildfire conditions by providing a synthetic product depicting the chances of a fire event starting and escaping containment. To do so, we combined empirical models of ignition likelihood and effectiveness of the initial attack stage. We employed machine learning techniques to calibrate binary regression models using historical wildfire ignition data and geospatial layer depicting the main drivers of ignition and containment, namely: accessibility, human pressure on wildlands, fuel moisture and availability. We illustrate our approach along the Mediterranean coastal region of Spain. Our approach enables us to predict wildfire contention capacity under diverse population growth and climate warming scenarios. This strategy aims to improve disaster risk reduction by pointing wildfire management zones and prioritizing intervention in high-risk areas.

Results indicate a high predictive ability to model human-caused wildfire ignition (AUC>0.80) but a modest capability to capture the containment capability (AUC≈0.70). Accessibility by road largely controls the spatial pattern of ignition and containment, with dead fuel moisture content modulating the temporal pattern of probability. We further illustrate the approach by providing insights into future SSP (Shared Socieconomic Pathways) scenarios by synthesizing both products into comprehensive management zones (Rodrigues et al., 2022).

 

References

Rodrigues, M., Camprubí, À.C., Balaguer-Romano, R., Megía, C.J.C., Castañares, F., Ruffault, J., Fernandes, P.M., Dios, V.R. de, 2023. Drivers and implications of the extreme 2022 wildfire season in Southwest Europe. Science of The Total Environment 859, 160320. https://doi.org/10.1016/j.scitotenv.2022.160320

Rodrigues, M., Zúñiga-Antón, M., Alcasena, F., Gelabert, P., Vega-Garcia, C., 2022. Integrating geospatial wildfire models to delineate landscape management zones and inform decision-making in Mediterranean areas. Safety Science 147, 105616. https://doi.org/10.1016/j.ssci.2021.105616

How to cite: Gelabert Vadillo, P. J., Jiménez Ruano, A., Catelo, F., and Rodrigues Mimbrero, M.: Anticipating future extreme wildfire events by coupling ignition and success of initial attack models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8506, https://doi.org/10.5194/egusphere-egu24-8506, 2024.

EGU24-8507 | ECS | Posters on site | BG1.1

Unravelling Variability: Discrepancies in Amazonian Biomass Burning Emissions Under Different Emission Factor Scenarios  

Guilherme Mataveli, Matthew W. Jones, Gabriel Pereira, Saulo R. Freitas, Valter Oliveira, Esther Brambleby, and Luiz E.O. C. Aragão

Biomass burning (BB) plays a key role in the biosphere–atmosphere interaction. It is a major source of trace gases and aerosols that alters the atmosphere and the water cycle. Additionally, these emissions are often related to other detrimental impacts including biodiversity loss in fire-sensitive biomes, increase of respiratory diseases, and massive economic losses. BB emissions are used as inputs in models that estimate air quality and the effect of fires on Earth’s climate. Hence, an accurate estimation of BB emissions is paramount. While BB emissions spread over most of the global vegetated areas, the integration of orbital remote sensing and modelling is the most effective approach to estimate them from regional to global scales. BB emission estimation follows the relationship between burned biomass and the emission factor (EF - mass emitted of a given species, for example carbon dioxide, per mass of dry matter burned). The burned biomass can be estimated using two approaches: (i) based on the relationship among burned area, above-ground biomass, and combustion completeness; or (ii) based on fire radiative power (FRP), a quantitative measurement that is directly related to the rate of burned biomass and is estimated to each active fire detected by several orbital sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. EF values, which are Land Use and Land Cover (LULC) based, are required to estimate BB emissions independently on the approach adopted to estimate the burned biomass. Although novel approaches to improve the accuracy of BB emissions have been developed, the impact of EF values on the final estimated emissions remains uncertain. We have evaluated the impact of the EFs on the final estimate of fine particulate matter (PM2.5) emitted from BB in the Brazilian Amazon during a nineteen years’ time series (2002-2020) by running the PREP-CHEM-SRC emissions preprocessor tool under four EF scenarios: the tool original EF values based on the work of Andreae and Merlet (2001), the average EF values recently updated by Andreae (2019), and the minimum and maximum EF values also proposed by this author. The minimum (maximum) EF values were defined as the average EF value for each LULC class minus (plus) one standard deviation. The PM2.5 emissions were estimated at the spatial resolution of 0.1º using the FRP approach implemented on PREP-CHEM-SRC (3BEM_FRP model) having MODIS active fires as input, since this approach requires fewer inputs and the impact of the EFs over the emissions would be more evident. Our results showed that the annual average PM2.5 emission in the Amazon varied by 163% between the four EF scenarios (from1,426 Gg and 3,747 Gg), while the scenario based on the average values was the closest to the one based on PREP-CHEM-SRC original EF values (2,582 Gg and 2,213 Gg, respectively – an increase of 17%). These results contribute to the better understanding of how this single parameter impacts on the estimation of BB emissions.

How to cite: Mataveli, G., W. Jones, M., Pereira, G., R. Freitas, S., Oliveira, V., Brambleby, E., and E.O. C. Aragão, L.: Unravelling Variability: Discrepancies in Amazonian Biomass Burning Emissions Under Different Emission Factor Scenarios , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8507, https://doi.org/10.5194/egusphere-egu24-8507, 2024.

EGU24-8668 | ECS | Posters on site | BG1.1

Effect of long-range transported fire emissions on aerosol and cloud properties at high latitudes: In situ measurements and satellite observations 

Snehitha M. Kommula, Angela Buchholz, Yvette Gramlich, Tero Mielonen, Liqing Hao, Iida Pullinen, Lejish Vettikkat, Jorma Joutsensaari, Siegfried schobesberger, Petri Tiitta, Ari Leskinen, Dominic Heslin Rees, Sophie Haslett, Karolina Siegel, Chris Lunder, Paul Zieger, Radovan Krejci, Sami Romakkaniemi, Claudia Mohr, and Annele Virtanen

Global warming and climate change-induced rise in Earth’s temperature have increased the frequency of forest/wildfires over the past decade. Therefore, understanding the effect of fire emissions on aerosol-cloud interactions is crucial for improving Earth system models.

         We present observations from in-situ measurements of aerosol properties at the Puijo SMEAR IV station in eastern Finland and the Zeppelin Observatory in Ny-Ålesund, High Arctic. Both stations are frequently inside low-level clouds due to their topographic prominence. During the autumn of 2020, fire emissions from the same active fire region in south-eastern (SE) Europe reached both stations after ~2 - 8 days of atmospheric aging. This enabled us to investigate the changes in aerosol and cloud properties for clouds formed under the influence of aged fire emissions (referred to as the ‘fire’ period) and under cleaner conditions with no fire emission influence at these stations (‘non-fire’ period). The aerosol hygroscopicity parameter (κchem) was derived from the chemical composition data obtained from online aerosol mass spectrometers and was used to derive the number concentration of cloud condensation nuclei (NCCN) from the measured particle size distributions.

         At both stations, the aerosol number concentration in the accumulation mode and the cloud condensation nuclei concentration (NCCN) were higher during the fire period than during non-fire times. However, the aerosol hygroscopicity increased at Puijo but decreased a Zeppelin from the non-fire to fire period. At Puijo, in-situ measured cloud droplet number concentration (CDNC) was by a factor of ~7 higher when comparing fire to non-fire periods. This was in good agreement with the satellite observations (MODIS, Terra). At Puijo, the higher CCN concentrations during the fire period cause a depletion of the water vapor available for cloud droplet activation leading to larger observed activation diameters during cloud events despite the higher hygroscopicity of the aerosol particles.

         These observations show the importance of SE European fires for enhancing the CCN activity in Finland and the high Arctic. Results from this study emphasize the complex interplay between particle size and chemical composition, and how fires even from sources far away can have strong impacts in these remote regions.

How to cite: Kommula, S. M., Buchholz, A., Gramlich, Y., Mielonen, T., Hao, L., Pullinen, I., Vettikkat, L., Joutsensaari, J., schobesberger, S., Tiitta, P., Leskinen, A., Rees, D. H., Haslett, S., Siegel, K., Lunder, C., Zieger, P., Krejci, R., Romakkaniemi, S., Mohr, C., and Virtanen, A.: Effect of long-range transported fire emissions on aerosol and cloud properties at high latitudes: In situ measurements and satellite observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8668, https://doi.org/10.5194/egusphere-egu24-8668, 2024.

EGU24-9225 | ECS | Orals | BG1.1 | Highlight

Warming and cooling influences of North American boreal fires 

Max van Gerrevink, Sander Veraverbeke, Sol Cooperdock, Stefano Potter, Qirui Zhong, Michael Moubarak, Scott J. Goetz, Michelle C. Mack, James T. Randerson, Merritt R. Turetsky, Guido van der Werf, and Brendan M. Rogers

The Arctic-boreal region is warming rapidly, with consequences for northern ecosystems and global climate. Fires across the Arctic-boreal region are a major natural disturbance mechanism that initiate climate warming (positive) and cooling (negative) feedbacks. Understanding the net forcing effect from boreal fire on climate is crucial in managing and mitigating climate change impacts of boreal fires. Here we report radiative forcing estimates from boreal forest fires across Alaska and Western Canada (Arctic Boreal Vulnerability Experiment-domain). Our results integrate the effect of greenhouse gas emissions (warming) and aerosols emission (net cooling) have through direct combustion, post-fire vegetation recovery sequestering carbon (cooling), fire-induced permafrost degradation emitting CO2 and CH4 (warming), and changes in surface albedo (cooling). Alaskan fires are on average climate warming (1.34±2.95 W/m2 per burned area) – uncertainty given as spatial standard deviation, while Canadian fires show on average a climate cooling (‑2.26±2.48 W/m2 per burned area) effect. The emissions from the combustion of organic soils and post-fire permafrost thaw dominate the positive feedback for Alaskan fires, whereas the cooling effect of post-fire changes in surface albedo because of prolonged spring snow cover dominate for the western Canadian fires. Our work demonstrates large-scale spatial variability in the climate feedbacks from North American boreal forest fires. Such fine-scale spatial information on the warming and cooling influences of forest fires could be useful in designing forest management and fire suppression activities informed by climate impacts.

How to cite: van Gerrevink, M., Veraverbeke, S., Cooperdock, S., Potter, S., Zhong, Q., Moubarak, M., Goetz, S. J., Mack, M. C., Randerson, J. T., Turetsky, M. R., van der Werf, G., and Rogers, B. M.: Warming and cooling influences of North American boreal fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9225, https://doi.org/10.5194/egusphere-egu24-9225, 2024.

EGU24-9270 | ECS | Orals | BG1.1

What limits the growth of lightning fires in the remote northeast Siberian taiga? 

Thomas Janssen and Sander Veraverbeke

In recent years, boreal forests have experienced unprecedented fire activity. These fires have contributed substantially to carbon emissions and posed hazards to human health. In the remote northeast Siberian taiga, the vast majority of fires are ignited by lightning strikes and not by human activity. Furthermore, active fire suppression is largely absent in these remote areas, resulting in uncontrolled fire growth. Here, we present a detailed look at the places and times where these lightning fires do finally stop spreading and aim to identify the causes. We employ various remote sensing and geo-spatial datasets including fire weather as well as landscape variables such as the presence of surface water, road networks, woody fuel load, fire history, elevation and landcover, to pinpoint the limitations to fire growth along fire perimeters recorded between 2012 and 2022 at a 300-meter spatial resolution. We were able to attribute 87% of all fire perimeter locations to a statistically significant (p < 0.01) change in one or more of these fire limitations over either time (fire weather) or space (landscape). The analysis reveals that fire growth is mainly limited by a change in the vegetation (fuel type and fuel load) as well as a change to less favourable weather for fire spread, although there are clear regional differences in the importance of specific limitations. Overall, fire weather seems to be the most important limitation to fire growth in the north of the Siberian taiga where continuous permafrost is present. With a rising frequency of lightning strikes, droughts, and heatwaves in boreal regions, uncontrolled lightning fires have the potential to expand even further in the future, leading to significant implications for vulnerable permafrost landscapes and, consequently, the global carbon cycle.

How to cite: Janssen, T. and Veraverbeke, S.: What limits the growth of lightning fires in the remote northeast Siberian taiga?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9270, https://doi.org/10.5194/egusphere-egu24-9270, 2024.

EGU24-10145 | ECS | Posters on site | BG1.1

Burned area and climate extremes in different land covers in southeastern Australia 

Patrícia Páscoa, Ana Russo, Andreia Ribeiro, and Célia Gouveia

Large burned areas (BA) in southeastern Australia were regularly registered during hot and dry years, such as the Black Saturday (2009) and the Black Summer (2019-2020) extreme bushfires. These types of extreme climate conditions are expected to become more frequent, leading to an increased risk of large BA in this region.

In this work, the influence of drought conditions and hot events on the BA in southeastern Australia was assessed, using correlation and copula functions. Bivariate copula functions were fitted, and conditional probabilities of large BA given climate extremes were computed. Three classes of drought intensity were studied, namely moderate, severe, and extreme, as well as three thresholds for temperature extremes, namely the 80th, 90th, and 95th percentiles. Monthly BA were computed as the sum of the burned pixels in the fire season (from October to March), using data from the MODIS Burned Area product. The analysis was performed on forests, grasslands, and savannas separately. Drought conditions were assessed with SPEI at several time scales, computed with data from the CRU TS4.07 dataset. Maximum and minimum daily temperature were retrieved from the ERA5 dataset.

Results showed that the correlation between BA and SPEI was high in the current and previous 1 month for all land covers, being highest in savannas and lowest in grasslands. Short time scales of SPEI had the highest correlation on grasslands, and the opposite was observed in forests and savannas. The correlation with maximum temperature increased until 10-15 days before the fire event and surpassed 0.6 over forests. Minimum temperature presented much lower correlations and there was not a pronounced increase in the previous days, as observed with the maximum temperature.

The conditional probability of large BA increased with the intensity of the drought on all land covers, and it reached almost 100% probability of exceeding the 50th percentile of BA under extreme droughts on forests and savannas. For the case of the 80th percentile of BA, the probability was lower, but the difference given drought and non-drought conditions was larger than for the 50th percentile. On savannas and forests, the conditional probability was still high when considering SPEI in the previous 2 and 3 months.

Maximum temperature yielded a higher probability of BA for the two highest percentiles. Savannas presented the lowest probability of BA given hot events, and forests the highest. The probability increased up to 10 days before the fire. Overall, the probabilities obtained given drought conditions are higher than given hot events, particularly for larger fires. Moreover, high probabilities obtained with large time scales and longer lead times are indicative of the importance of drought conditions before the fire season and may help predict the occurrence of large BA.

 

Acknowledgments: This study was partially supported by FCT (Fundação para a Ciência e Tecnologia, Portugal) through national funds (PIDDAC) – UIDB/50019/2020, by project Floresta Limpa (PCIF/MOG/0161/2019), and by project 2021 FirEUrisk, funded by European Union’s Horizon 2020 research and innovation programme under the Grant Agreement no. 101003890). A.R. was supported by FCT through https://doi.org/10.54499/2022.01167.CEECIND/CP1722/CT0006. 

How to cite: Páscoa, P., Russo, A., Ribeiro, A., and Gouveia, C.: Burned area and climate extremes in different land covers in southeastern Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10145, https://doi.org/10.5194/egusphere-egu24-10145, 2024.

EGU24-10377 | ECS | Posters on site | BG1.1

Human land occupation regulates the effect of the climate on the burned area of the Cerrado biome 

Carlota Segura-Garcia, David Bauman, Vera L. S. Arruda, Ane Alencar, and Imma Oliveras Menor

The Brazilian Cerrado is a heterogeneous biome formed by a mosaic of savannas, grasslands, and smaller patches of denser woody forms. In this biome, fire is a natural disturbance agent that contributes to maintaining its open ecosystems and rich biodiversity. However, modern human activities and climate change are altering its fire regimes. In tropical savannas, land-use expansion is usually associated to a decrease in burned area primarily through land fragmentation, but also through active fire suppression. Meanwhile, climate change is fostering fire weather conditions, exacerbating fire activity. Hence, the two main drivers of fire could be pushing burned area in opposite directions, both with important ecological consequences for the Cerrado. However, it remains unclear how these two drivers interact, which is essential to devise effective fire management policies and conservation plans.

In this study, we use a causal inference framework to quantify the interaction between anthropic area percentage – as a proxy of human presence and fragmentation – and various climatic variables on their effects on Cerrado’s burned area. As well, we explore the spatial structure of temporal trends in burned area, anthropic expansion and climate change, and quantify the causal effect of the last two on the former.

We use geospatial data from different sources on a 0.2o grid over the Cerrado for the period 1985 to 2020. We use burned area and land use data from the MapBiomas project, and climate re-analysis data from ERA5 Land, CHIRPS and TerraClimate. We design our models using Directed Acyclic Graphs, a graphic representation of the causal relations between the predictors and burned area that informs variable selection for causal inference. Hence, based on these DAGs, we build multilevel Bayesian regression models to quantify the effects of the predictors and their interactions.

We find that a larger presence of land-use activities keeps burned area low and, importantly, hinders the effects of the climate. That is, while in landscapes composed mostly of native vegetation hotter and drier conditions increase burned area as expected; in anthropic landscapes, humans completely limit burned area responsiveness to climate. We also find spatially heterogeneous increasing and decreasing trends in burned area over the period, but concentrated in those areas of the Cerrado that were mostly natural in 1985. In these areas, a large anthropic expansion brought about a decrease in burned area, while we observe an increase in burned area in relation to climate change only in the areas that remained intact throughout the study period.

In conclusion, burned area in the Cerrado is shaped primarily by the extent of human presence in the landscape, even limiting the effects of the climate, while climatic effects become relevant in areas with larger tracts of native vegetation, suggesting that these areas may be more vulnerable to climate change.

How to cite: Segura-Garcia, C., Bauman, D., S. Arruda, V. L., Alencar, A., and Oliveras Menor, I.: Human land occupation regulates the effect of the climate on the burned area of the Cerrado biome, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10377, https://doi.org/10.5194/egusphere-egu24-10377, 2024.

EGU24-10606 | ECS | Orals | BG1.1

Characterizing lightning-ignited wildfire occurrences at sub-grid scales in orography-aware NOAA/GFDL land model LM4.2 

Rui Wang, Enrico Zorzetto, Sergey Malyshev, and Elena Shevliakova

Lightning ignitions are the dominant causes of wildfires in many regions, responsible for 80% of burned areas at high latitudes and about 70% of fires in the Amazon rainforest. With global wildfire activities and extreme fire events (e.g., intensity, duration, and size) increasing under the changing climate conditions, understanding the interactions between lighting, landscape characteristics, and wildfires is crucial for predicting and mitigating the impacts of climate change. Cloud-to-ground lightning activities are driven by a combination of large- and local-scale factors, e.g., local atmospheric circulations and convection and topography. Furthermore, the number of lightning strikes is predicted to increase by 10 – 30 % per degree warming. Decadal satellite observations have revealed Earth’s lightning hotspots at very high resolution, however, there is a paucity of fine-scale lightning strikes and lightning-ignited wildfires (LIW) in the Earth system and climate models. Currently, many climate and ESM  models do not include fires at all or simulate them with meteorological inputs and grid-average lightning at the scale of atmospheric models (25 to 100 km), introducing large uncertainties of LIW due to the lack of information at the scales relevant to fire dynamics.  Lack of information about lightning trends and variability hinders the prediction and projection of fires and their contribution to carbon and other atmospheric tracers and global warming. For example, in the US National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL) ESM4.1 model, the fire model uses a climatology of lightning strikes from preindustrial to 2100.

In this presentation, we will demonstrate the implications of capturing subgrid lightning distributions in the GFDL land model LM4.2 for the global simulations of wildfire dynamics over the available records (1998-2013) and provide insights into future projections. LM4.2 captures sub-grid heterogeneity of land cover and use, soil geomorphology, and topography, facilitating the understanding of LIW distribution across global to regional and sub-grid scales. In this study, we leverage 0.1° × 0.1° lightning observations from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) in the GFDL LM4-HB to characterize fine-scale lightning strike distribution and associated LIW.

How to cite: Wang, R., Zorzetto, E., Malyshev, S., and Shevliakova, E.: Characterizing lightning-ignited wildfire occurrences at sub-grid scales in orography-aware NOAA/GFDL land model LM4.2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10606, https://doi.org/10.5194/egusphere-egu24-10606, 2024.

EGU24-10793 | ECS | Posters on site | BG1.1

A Decision Support System for Forest Fire Danger Notices in Ireland  

Padraig Flattery, Klara Finkele, Paul Downes, Alan Hally, and Ciaran Nugent

Since 2006 the Canadian Forest Fire Weather Index System (FWI) has been employed operationally at Met Éireann to predict the risk of forest fires in Ireland. Around 11% or 770,000 ha of the total land area of Ireland is afforested, but there are also large areas of open mountain and peatlands covered in grasses, dwarf-shrub and larger woody shrub type vegetation which can provide fuel for spring wildfires under suitable conditions. After winter, vegetation can be dead or have a very low live moisture content, and the flammability of this vegetation can be readily influenced by prevailing weather, especially following prolonged dry periods.

Different decision support tools are available to different sectors, namely:

  • The General Public: who have access to fire weather index meteograms on Met Éireann’s public website.
  • Local Authorities, who have access to the ANYWHERE multi-hazard warning system, which provides multiple sources of information about fire danger and propagation.
  • The Department of Agriculture, Food and Marine (DAFM), who are provided with information and additional support from National and European partners and networks.

DAFM is the Forest Protection authority in Ireland responsible for issuing Forest Fire Danger Notices which improve preparedness for fire responses and are based on a range of factors including information provided by Met Éireann who calculate the FWI and FWI components using observation data at synoptic stations, and the predicted FWI for the next five days ahead based on numerical weather prediction data. This allows fire responders to build resilience and prepare for impending fires.

The FWI is determined based on the types of forest fuel and how quickly they dry out/get rewetted, and components of fire behaviour. The FWI represents the fire intensity as the rate of energy per unit length of fire front (kW/m). The components which provide the most accurate indication of risk under Irish conditions are the Fine Fuel Moisture Code and Initial Spread Index, based on the fuels involved and ignition patterns observed to date. Since 2022 Met Eireann provide the FWI as well as the individual components Fine Fuel Moisture Content and Initial Spread Index via the public website for synoptic stations. These indices are based on observations and a seven-day forecast into the future using ECMWF predictions. This allows all county councils responsible for wildfire preparedness to access this information swiftly and directly.

Met Éireann also use the ANYWHERE multi-hazard warning tool which allows for visualisation of multiple fire-related risk factors and warning indices to be viewed simultaneously. The ANYWHERE system, in combination with our station-based forecast and antecedent conditions, provide fire managers and response teams with excellent information with which to make decisions.

How to cite: Flattery, P., Finkele, K., Downes, P., Hally, A., and Nugent, C.: A Decision Support System for Forest Fire Danger Notices in Ireland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10793, https://doi.org/10.5194/egusphere-egu24-10793, 2024.

EGU24-10920 | ECS | Posters on site | BG1.1

Reconstructing 20th century burned area by combining global fire model input, satellite observations and machine learning 

Seppe Lampe, Lukas Gudmundsson, Vincent Humphrey, Inne Vanderkelen, Bertrand Le Saux, and Wim Thiery

The temporal coverage (∼2000 to present) of global burned area satellite observations limits many aspects of fire research e.g., long-term trend analysis, disentangling the effect of various drivers on fire behaviour and detection and attribution of changes to climate change. As a result, global fire models are more frequently being called upon to answer questions about past and future fire behaviour. Unfortunately, the limited temporal coverage of the observations also hinders the development and evaluation of these fire models. The current generation of global fire models from ISIMIP are able to simulate well some characteristics of regional fire behaviour such as mean state and seasonality. However, the performance of these models differs greatly from region to region, and aspects such as extreme fire behaviour are not well represented yet. Here, we explore the possibility of using machine learning algorithms to model burned area from the same input parameters that are passed to global climate models. Once trained, this data-driven model can be evaluated against regional proxies for past fire behaviour e.g., tree rings and charcoal records. Hopefully, this data-driven reconstruction can provide valuable insights on the 20th century burned area, and can help improve and evaluate fire models.

How to cite: Lampe, S., Gudmundsson, L., Humphrey, V., Vanderkelen, I., Le Saux, B., and Thiery, W.: Reconstructing 20th century burned area by combining global fire model input, satellite observations and machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10920, https://doi.org/10.5194/egusphere-egu24-10920, 2024.

EGU24-10947 | Orals | BG1.1 | Highlight

Burned area and fire emissions according to the fifth version of the Global Fire Emissions Database (GFED) 

Guido van der Werf, James Randerson, Dave van Wees, Yang Chen, Roland Vernooij, Louis Giglio, Joanne Hall, Douglas Morton, Kelley Barsanti, and Bob Yokelson

Quantifying burned area and associated fire emissions is paramount to understand how changing fire patterns affect radiative forcing and air quality. It is now well established that many fires are too small to be detected by coarse resolution satellite burned area products on which the Global Fire Emissions Database (GFED) relied. In the fifth version of GFED (GFED5) we therefore combine burned area derived from mapped coarse-resolution burned area from the MODIS sensor -which excels in detecting larger fires- with small-fire burned area. The latter is derived from MODIS active fire detections scaled to burned area using ratios constrained by higher-resolution burned area datasets from Landsat and Sentinel-2 for selected regions. Burned area in cropland regions was based on the Global Cropland Area Burned (GloCAB) dataset. Total global burned area is 61% higher than in GFED4s. We converted burned area to emissions using a simplified version of the CASA model used in previous GFED versions, but which now runs at a 500 m spatial resolution. This allows for better constrained modeled fuel loads based on field measurements. Although GFED5 emissions are aggregated to a 0.25 degree grid due to the statistical nature of deriving our burned area, we can now account for heterogeneity in fire processes within these large pixels. Emissions (3 Pg carbon per year) are roughly 50% higher than in GFED4 and we show how diverging trends in grassland versus forest ecosystems impact trends in total emissions. Finally, we show how converting fire carbon losses to trace gas and aerosol emissions is now better constrained due to the addition of several new emission factor measurement campaigns. In the savanna biome we now account for spatial and temporal variability in emission factors.

How to cite: van der Werf, G., Randerson, J., van Wees, D., Chen, Y., Vernooij, R., Giglio, L., Hall, J., Morton, D., Barsanti, K., and Yokelson, B.: Burned area and fire emissions according to the fifth version of the Global Fire Emissions Database (GFED), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10947, https://doi.org/10.5194/egusphere-egu24-10947, 2024.

EGU24-11206 | ECS | Posters on site | BG1.1 | Highlight

Global cloud-to-ground lightning data to inform wildfire ignition patterns 

Esther Brambleby, Sander Veraverbeke, Guilherme Mataveli, Manoj Joshi, and Matthew Jones

Lightning is recognised as a crucial wildfire ignition source worldwide, especially in remote regions including boreal and temperate forests where large carbon stocks are held. The societal consequences of these wildfires, as well as their contribution to climate change, can be immense. The occurrence of lightning is projected to increase in these areas under climate change, however robust assessments of lightning contribution to wildfire risk have been restricted to selected regions due to the narrow spatial extent of cloud-to-ground lightning records. Consequently, evaluations of lightning-fire relationships using existing global lightning observational datasets have been limited to considering the total amount of lightning. Only cloud-to-ground lightning can ignite a wildfire, therefore when considering impacts on wildfire risk it is essential to distinguish between lightning types.

Using Vaisala’s unique Global Lightning Dataset (GLD360), which discriminates between cloud lightning and cloud-to-ground lightning strikes, we present our preliminary analyses of the spatial patterns and seasonality of cloud-to-ground lightning. Here, we show the regional variation in the lightning frequency and the cloud-to-ground fraction, as well as the strength (current) and polarity of cloud-to-ground lightning strikes.

By considering cloud-to-ground lightning strikes only, we characterise the spatial and seasonal variation in lightning events with the potential to ignite wildfires. Combining global observations of lightning strikes with observations of individual fires and coincident meteorology will advance our mechanistic understanding of wildfire ignition potential in a range of weather conditions, improve the process representation of the ignition process in global models, and refine projections of changing wildfire risks under climate change.

How to cite: Brambleby, E., Veraverbeke, S., Mataveli, G., Joshi, M., and Jones, M.: Global cloud-to-ground lightning data to inform wildfire ignition patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11206, https://doi.org/10.5194/egusphere-egu24-11206, 2024.

This research delves into the dynamics of forest fires across various Indian regions, particularly during the unique COVID-19 lockdown period. The study's core focus is on the interaction between forest fires, climatic factors, and vegetation indices in a scenario of reduced human activity. It employs a multidimensional methodology, integrating satellite imagery and climatic data from periods before, during, and post-lockdown. The lockdown provides a critical opportunity to assess the impact of decreased human interference on forest fire patterns. Advanced statistical techniques are used to analyze the relationship between vegetation indices, fire occurrences, and meteorological conditions. This approach aims to uncover the underlying mechanisms driving these relationships, moving beyond simple trend identification. The research offers a nuanced perspective by differentiating natural factors from human influences. This distinction is vital in understanding the environmental dynamics during the lockdown. The findings have significant implications, offering insights for policymakers and environmentalists in enhancing forest fire management strategies. Emphasizing the need for a comprehensive understanding of environmental interactions, this study contributes to forming more informed and sustainable approaches to natural disaster management in the face of global challenges like climate change and pandemics.

How to cite: Kate, R. and Bhattacharya, J.: Forest Fires during COVID-19: Assessing Environmental Interactions and Fire Dynamics Amidst Reduced Human Intervention in India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11291, https://doi.org/10.5194/egusphere-egu24-11291, 2024.

EGU24-11432 | ECS | Posters on site | BG1.1 | Highlight

Northern high latitude peat fires: from lab to modelling  

Dimitra Tarasi, Eirini Boleti, Katie Blackford, Matthew Kasoar, Emmanouil Grillakis, Guillermo Rein, Hafizha Mulyasih, and Apostolos Voulgarakis

Climate warming is occurring most rapidly at high latitudes, heightening the vulnerability of carbon-rich peatlands to fire. Northern peatlands comprise the largest terrestrial carbon store, and exert a net cooling effect on the climate. Warmer and drier conditions due to the anticipated climate change are expected to contribute substantially to increased fire severity and frequency in the northern high latitudes, potentially shifting peatlands from being carbon sinks to being greenhouse gas emission sources. Therefore, peat fires, which are considered the largest and most persistent fires on Earth, can significantly impact the global carbon cycle, atmospheric composition, climate, air quality, and human health. Representing peatland fire feedbacks to climate in Earth system models is essential for accurately predicting the future of the climate system. Here, we present the first steps of an effort to distill lab results on peat burning and emissions into global fire modelling. Since peat moisture content and the depth of burn have been experimentally proved to be critical for the representation of peat fires, we aim to incorporate those mechanisms into a global model functionality. More specifically, we aim to represent the mechanistic understanding of the ignition and spread of peat fires in INFERNO-peat, the peat module of the JULES-INFERNO global fire model. To assess the added value of our updated model, we compare the simulated burnt area and carbon emissions with observation-based products. As boreal regions remain a big mystery for the future of our planet, our improved model representation of peat fires in northern high latitudes contributes to a better understanding of future atmospheric composition, radiative forcing and climate. 

How to cite: Tarasi, D., Boleti, E., Blackford, K., Kasoar, M., Grillakis, E., Rein, G., Mulyasih, H., and Voulgarakis, A.: Northern high latitude peat fires: from lab to modelling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11432, https://doi.org/10.5194/egusphere-egu24-11432, 2024.

EGU24-11599 | ECS | Orals | BG1.1

Comparison and validation of state-of-the-art fire emissions models for the Amazon 

Dave van Wees, Vincent Huijnen, Matthias Forkel, Jos de Laat, Niels Andela, and Christine Wessollek

Amazon forest conservation is critical for reaching net-zero carbon emissions and protecting regional biodiversity but these efforts are at risk from deforestation, fire and drought. In particular, accurate quantification of carbon losses from forest and deforestation fires are required to understand long-term impacts of fire on the carbon cycle and inform management strategies. Recent developments in the detection of burned area, near-real time tracking of fire patch metrics, and higher-resolution fire emissions models allow for improved estimates of carbon losses from fire. Nevertheless, independent validation of these novel approaches often remains elusive, leading to large disagreement between different emissions inventories.

Here, we compare carbon emissions estimates from several state-of-the-art fire emissions models, including a 500-m resolution GFED version, GFAS, and the Sense4Fire project, in a case-study for the Amazon region. Where necessary, we have updated the models to extend to 2022 and to include the most recent version of model input data from MODIS (Collection 6.1). We analysed the added years of data to elucidate recent trends in fire-related carbon emissions across the Amazon and adjacent biomes. For validation, we ingested the CO emissions from the considered fire emissions models into an atmospheric transfer simulation (IFS-COMPO) and compared those to column CO observations from Sentinel-5P TROPOMI. Finally, we propose an optimization methodology for matching modelled CO concentrations to observations with the objective of constraining regional carbon losses from fire. Results provide novel insights into carbon losses from fire across different fire types and land use practices, and can be extended to global scale for improved estimates of global fire emissions.

How to cite: van Wees, D., Huijnen, V., Forkel, M., de Laat, J., Andela, N., and Wessollek, C.: Comparison and validation of state-of-the-art fire emissions models for the Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11599, https://doi.org/10.5194/egusphere-egu24-11599, 2024.

EGU24-11809 | ECS | Posters on site | BG1.1

Analysing the effects of postfire oak afforestation on the provision of ecosystem services 

Luis Filipe Lopes, Erika S. Santos, Leónia Nunes, Paulo M. Fernandes, and Vanda Acácio

Forests play a substantial role in generating externalities and supporting services essential for maintaining key ecosystem functions and processes. Fire has long been a natural element of forest dynamics, contributing to model the structure, composition, and diversity of vegetation. However, changes in fire regimes in recent decades in Europe (e.g., more frequent and severe fires) have led to negative ecological, social, and economic impacts, particularly marked by a decline in the provision of ecosystem services. Mediterranean Europe, being a region highly prone to wildfires and currently experiencing a change in fire regimes, exemplifies this situation.

In this study, we aim to understand the effects of postfire oak afforestation on the provision of ecosystem services (ES). We analysed 15 afforestation projects with the deciduous Pyrenean oak (Quercus pyrenaica) carried out in 1994-2006 in similar soil type (Cambisols) in the North and Center of Portugal, including seven pure and eight mixed oak stands. For each project area, we identified an adjacent control area affected by the same fire event but without oak afforestation or evident management. In 2021-2022, for each project and control areas, we collected field data on: site conditions, stand characteristics, forest biometry, understory vegetation (height and cover), floristic richness and diversity, oak natural regeneration and litter. At the moment of data collection, the majority of projects (10) were 12 to 17 years old, with the remaining projects (5) having been implemented 21 to 25 years ago. Collected data was used to quantify provisioning ecosystem services (wood volume) and regulation and maintenance services (forest and litter carbon, fire protection, maintenance of nursery populations, habitats, and seed dispersal).

Afforested areas supplied more provisioning services (higher wood volume), as a consequence of a higher tree density when compared to non-afforested areas. Total carbon content and litter carbon were not significantly different between afforested and control areas. Nevertheless, afforested and control areas exhibited distinct patterns concerning carbon in the different forest layers: carbon in the tree layer was significantly higher in afforested areas, while carbon in the understory layer was significantly higher in control areas. Afforested areas also showed a significantly higher fire protection service, as a consequence of lower fuel load from regular understory shrub management. Lastly, we found no significant differences in services related to maintenance of nursery populations and habitats (estimated with floristic species and diversity), and seed dispersal (estimated with oak natural regeneration), although afforested areas presented a higher number of oak seedlings.

Our study shows that postfire afforestation in oak forests may have a positive, null or negative impact on ES, depending on the service under analysis, highlighting the existence of trade-offs among multiple ES. We emphasize the importance of a comprehensive understanding of the impacts of postfire afforestation on ES to guide postfire management, aiming to enhance forest resilience in the face of predicted climate change.

How to cite: Lopes, L. F., Santos, E. S., Nunes, L., Fernandes, P. M., and Acácio, V.: Analysing the effects of postfire oak afforestation on the provision of ecosystem services, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11809, https://doi.org/10.5194/egusphere-egu24-11809, 2024.

EGU24-11962 | Orals | BG1.1

The Great Fuel Moisture Survey: developing fundamental wildfire science and sustainable community owned agency in traditionally non-fire prone societies 

Nicholas Kettridge, Katy Ivison, Alistair Crawford, Gareth Clay, Claire Belcher, Laura Graham, and Kerryn Little

New fire vulnerable communities are emerging in traditionally non-fire prone regions of the world. But these communities are often largely unaware of the developing threat and do not hold the core wildfire knowledge to galvanise collective community-based action to mitigate the risk. Furthermore, we urgently require knowledge of fuel moisture dynamics and flammability of fuels in such regions to provide accurate assessments of fire danger at the national scale. Here we characterise the moisture content and flammability of heather through engaged environmental science, demonstrating the potential of the approach to develop a public consciousness and knowledge of wildfire within communities. Fuel sampling kits were sent to 150 samplers who collected ~1000 vegetation samples across the UK (from Land’s End to John O’Groats) over a period of two days during a single period of high fire danger. The validity of the volunteer approach for collecting high quality fuel moisture data was also assessed from the analysis of a separate ~1500 samples collected by 17 samplers in a single test plot. The approach provides a simple nationally available entry point for residents traditionally unaware of both the wildfire risk and the management of their community for wildfire mitigation. Empowering samplers offers potential future opportunity to create meaningful local datasets, to build communities, and in doing so give a strong voice to residents in regional and national policy discussions.

How to cite: Kettridge, N., Ivison, K., Crawford, A., Clay, G., Belcher, C., Graham, L., and Little, K.: The Great Fuel Moisture Survey: developing fundamental wildfire science and sustainable community owned agency in traditionally non-fire prone societies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11962, https://doi.org/10.5194/egusphere-egu24-11962, 2024.

EGU24-11965 | ECS | Posters on site | BG1.1

Effects of 2018 wildfire on soil properties in a peatland within the Peak District National Park (central England) 

Luigi Marfella, Mark A. Ashby, Georgia Hennessy, Rossana Marzaioli, Flora A. Rutigliano, and Helen C. Glanville

Peatland soil is a valuable component of natural capital by constituting the largest terrestrial carbon sink (~30% of the global soil carbon) and an essential freshwater source. Despite covering only ~3% of the Earth’s surface, peatlands provide crucial ecosystem services i.e. water-quality improvement and climate regulation by storing carbon in peat. However, peat degradation due to anthropogenic activities (e.g. drainage) as well as global climate change exposes this ecosystem to fire risk.
This study assessed the medium-term (~5 years) impacts of the 10 August 2018 wildfire within The Roaches Nature Reserve. This area spans the southeastern sector of the Peak District National Park and Special Area of Conservation (SAC-UK0030280). According to the Staffordshire Wildlife Trust (responsible authority for Reserve management), the human-caused fire broke out in a wooded area and aided by wind, spread to the peatland. Here, we integrated soil analyses and vegetation surveys of a burnt and unburnt area i) to assess possible correlations between soil biogeochemical properties and vegetation cover with ii) remote sensing to collect data on fire severity exploring temporal and spatial wildfire impacts.
Processing of satellite imagery highlighted a high-severity fire impact within the perimeter of the burned area, which predicts alteration of soil characteristics. Preliminary outcomes on the soil indicated deacidification and reduced water content in the burned peat remains 5 years post-fire.
Given that global peatland conservation is an important tool for addressing climate-change, this research appears necessary to develop effective management strategies, including rewetting of peatlands postfire.

How to cite: Marfella, L., Ashby, M. A., Hennessy, G., Marzaioli, R., Rutigliano, F. A., and Glanville, H. C.: Effects of 2018 wildfire on soil properties in a peatland within the Peak District National Park (central England), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11965, https://doi.org/10.5194/egusphere-egu24-11965, 2024.

The ignition, spread, and severity of wildfires are driven largely by weather conditions (Jain et al. 2020: https://doi.org/10.1139/er-2020-0019; Liu et al. 2013: https://doi.org/10.1371/journal.pone.0055618).  The main tool for weather prediction across the globe is a set of physical, coupled atmosphere/ocean models, called numerical weather prediction (NWP).  Despite rapid improvements in the last few decades, NWP alone is not sufficient for wildfire prediction, because it does not resolve every process related to wildfire.  One solution is to post-process NWP with statistical models, which correct the NWP model towards better resolving processes related to the phenomenon of interest (here, wildfire).  This post-processing is called model-output statistics (MOS) and typically involves linear regression.  However, recent work has advanced MOS by incorporating more powerful statistical models from deep learning (DL).  We use DL to predict extreme fire weather and behaviour at multi-day lead times throughout the United States.

 

For fire weather, we have trained U-nets -- a type of deep neural network -- to predict at lead times of 3-240 hours over the United States.  The output (target) variables are seven indices from the Canadian Fire Weather Index System (CFWIS), computed from the ECMWF Reanalysis version 5 (ERA5).  These seven indices include the fine-fuel moisture code (FFMC), initial-spread index (ISI), overall fire-weather index (FWI), etc.  Meanwhile, the input (predictor) variables come from five sources.  The first is a forecast time series of atmospheric state variables (height, temperature, humidity, and wind) from the Global Forecast System (GFS) NWP model.  The second is a forecast time series of surface and subsurface moisture (soil moisture, accumulated precipitation, and snow depth) from the GFS.  The third is a set of constant fields (terrain height/slope/aspect, land-sea mask, etc.) describing the underlying terrain.  The fourth is a lagged time series of CFWIS over the past several days, i.e., past target values.  The fifth is a forecast time series of CFWIS indices, computed by applying the CFWIS functions directly to GFS-forecast weather variables.  These are the uncorrected (GFS-only) CFWIS forecasts, to be corrected by the U-net.

 

For fire behaviour, we have trained random forests -- ensembles of decision trees -- to predict fire radiative power (FRP) at lead times of 1-48 hours over the United States.  The labels (correct answers) for FRP are obtained from the Regional ABI and VIIRS Emissions (RAVE) merged satellite product.  Predictors for the random forest include the first three sources listed for the U-net above, plus a lagged time series of FRP over the past 24 hours, i.e., past target values.

 

Both models -- the U-net for fire weather and the random forest for fire behaviour -- are trained with built-in uncertainty quantification.  Thus, at every lead time and grid point, both models provide an expected value and an estimate of their own uncertainty.  We will present objective evaluation results (for both the mean forecast and uncertainty) and explainable artificial intelligence (XAI) to understand what the models have learned, e.g., which spatiotemporal weather patterns in a given area are most conducive to extreme fire weather/behaviour.

How to cite: Lagerquist, R. and Kumler, C.: Using deep learning to improve multi-day forecasts of extreme fire weather and behaviour throughout the United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12223, https://doi.org/10.5194/egusphere-egu24-12223, 2024.

EGU24-12320 | ECS | Orals | BG1.1

Integrating Human Domain Knowledge into Artificial Intelligence for Hybrid Forest Fire Prediction: Case Studies from South Korea and Italy 

Hyun-Woo Jo, Shelby Corning, Pavel Kiparisov, Johanna San Pedro, Andrey Krasovskiy, Florian Kraxner, and Woo-Kyun Lee

Forest fires pose a growing global threat, exacerbated by climate change-induced heat waves. The intricate interplay between changing climate, biophysical, and anthropogenic factors emphasizes the urgent need for sophisticated predictive models. Existing models, whether process-based for interpretability or machine learning-based for automatic feature identification, have distinct strengths and weaknesses. This study addresses these gaps by integrating human domain knowledge, crucial for interpreting forest fire dynamics, into a machine learning framework. We introduce FLAM-Net, a neural network derived from IIASA's wildfire Climate impacts and Adaptation Model (FLAM), melding process-based insights of FLAM with machine learning capabilities. In optimizing FLAM-Net for South Korea, new algorithms interpret national-specific forest fire patterns, and multi-scale applications, facilitated by U-Net-based deep neural networks (DN-FLAM), yield downscaled predictions. Successfully tailored to South Korea's context, FLAM-Net and DN-FLAM reveal spatial concentration near metropolitan areas and the east coastal region, with temporal concentration in spring. Performance evaluation yields Pearson's r values of 0.943, 0.840, and 0.641 for temporal, spatial, and spatio-temporal dimensions. Projections based on Shared Socioeconomic Pathways (SSP) indicate an increasing trend in forest fires until 2050, followed by a decrease due to increased precipitation. During the optimization process of FLAM-Net for Italy, optimal parameters for sub-areas are identified. This involves considering biophysical and anthropogenic factors at each grid, contributing to improved localized projection optimization by utilizing various sets of optimal parameters. There by, this process illuminates the intricate connections between environmental factors and their interpretation in the dynamics of forest fires. This study demonstrates the advantages of hybrid models like FLAM-Net and DN-FLAM, seamlessly combining process-based insights and artificial intelligence for interpretability, accuracy, and efficient optimization. The findings contribute scientific evidence for developing context-specific climate resilience strategies, with global applicability to enhance climate resilience.

How to cite: Jo, H.-W., Corning, S., Kiparisov, P., San Pedro, J., Krasovskiy, A., Kraxner, F., and Lee, W.-K.: Integrating Human Domain Knowledge into Artificial Intelligence for Hybrid Forest Fire Prediction: Case Studies from South Korea and Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12320, https://doi.org/10.5194/egusphere-egu24-12320, 2024.

EGU24-12529 | ECS | Orals | BG1.1 | Highlight

GlobalRx: A global assemblage of regional prescribed fire records for use in assessments of climate change impacts 

Alice Hsu, Jane Thurgood, Adam Smith, Liana Anderson, Hamish Clarke, Stefan Doerr, Paulo Fernandes, Crystal Kolden, Cristina Santín, Tercia Strydom, and Matthew Jones and the GlobalRx Consortium

Prescribed (Rx) and controlled fires are an important land management tool used globally for a variety of reasons, including the reduction of hazardous fuel loads, ecological conservation, agriculture, and natural resource management. Its use has important implications for wildfire risk, biodiversity, and carbon storage. However, the use of Rx and controlled fires is highly dependent upon weather conditions, requiring a weather window during which a careful balance of temperature, moisture, and wind ensure that the burns achieve their objectives while minimizing ecological damage or risk to human lives or assets. The planning and execution of Rx burns must also consider how these weather conditions interact with the local vegetation and ecology. As fire weather is projected to grow more extreme under the impacts of climate change, there is a growing need to monitor this effect on the ability to carry out Rx burning.

Here, we introduce a new dataset, GlobalRx, which includes around 140,000 records of Rx and other controlled fires from 16 countries, encompassing 207 ecoregions and 13 biomes around the world. For each record, we have geolocated values of various metrics of fire weather and fire danger (e.g. fire weather indices, vapour pressure deficit) from the ERA5 meteorological reanalysis, as well as the biome, ecoregion, fuelbed type, and protected area status from global thematic layers. We demonstrate the usefulness of this dataset for analyzing viable meteorological windows under which Rx fires may be conducted across diverse environmental settings in the present climate, as well as how these Rx burning windows may shift under the threats of climate change. This dataset has potential to shed light on how Rx burning windows may shift under future climate change, as well as opportunities to understand other drivers and effects of Rx burning.

This project has been supported by valuable contributions from non-public data from a consortium of data providers: Parks Canada, South Africa National Parks, Brazilian Institute of the Environment and Renewable Natural Resources, East-Pyrenees Prescribed Burning Team, Institute for Nature Conservation and Forests (Portugal), Regional Forest Fire Service (Italy), Russian Federal Forestry Agency, H2020 LifeTaiga Project, Government of the Principality of Asturias, Council of Andalucía, Council of Galicia, Forestry England, National Forestry Commission of Mexico, ZEBRIS Geo-IT GmbH, Hokkaido University, Pau Costa Foundation, Asian Forest Cooperation Organization.

How to cite: Hsu, A., Thurgood, J., Smith, A., Anderson, L., Clarke, H., Doerr, S., Fernandes, P., Kolden, C., Santín, C., Strydom, T., and Jones, M. and the GlobalRx Consortium: GlobalRx: A global assemblage of regional prescribed fire records for use in assessments of climate change impacts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12529, https://doi.org/10.5194/egusphere-egu24-12529, 2024.

EGU24-13237 | Posters on site | BG1.1

The role of fire radiative power to estimate fire-related smoke pollution. 

Rita Durao, Catarina Alonso, Ana Russo, and Célia Gouveia

The intensity of a wildfire can be assessed based on its released energy, obtained through remote measurements of the fire's radiative power. Since the Fire Radiative Power (FRP) is proportional to the amount of burned biomass and therefore to smoke production. Higher FRP values are associated with more severe fires, suggesting higher levels of smoke production and, consequently, higher emissions of particulate matter and other pollutants. The specific composition of smoke emissions can vary depending on factors such as the type of vegetation burned, the temperature of the fire, and the combustion conditions. In general, fire smoke is composed of a variety of air pollutants, including gases (NOx, CO, VOCs, O3, PAHs, etc) and particulate matter (PM). The objective of this work is to evaluate the ability of FRP, to be used as an indicator of fire smoke pollution. Particulate matter (PMx) and carbon monoxide (CO) concentrations emitted during recent wildfires in Portugal are analyzed to assess the link between pollution concentration levels and fire intensity over the affected areas, taking into account the spatial and temporal characteristics of each event. For this purpose, two particularly severe fires with significant impacts on air quality in central and southern Portugal were analyzed namely the ones taking place in October 2017 and August 2018. Concentrations of PMx and CO were evaluated through CAMS data, and the radiative power through the FRP product of the SEVIRI/MSG disseminated by LSA-SAFThe results show that the emitted pollutant concentrations significantly exceeded the established daily target limit values (air quality and public health guidelines). The fire intensity, based on the emitted Radiative Energy (FRE) derived from FRP, aligns with the known severity of these events, consistent with the observed concentrations of air pollutants, being demonstrated that the FRP can be associated with smoke production, especially PMx emissions during a fire. Thus, the proposed methodology using FRP can be a valuable tool for assessing the impact of wildfires on air quality and understanding the potential for smoke dispersion over fire-affected regions. The role of FRP as an indicator of air pollution highlights the potential use of FRP in assisting in management activities, operational planning, and emergency intervention during ongoing fires. 

Acknowledgments: This study is partially supported by the European Union’s Horizon 2020 research project FirEUrisk (Grant Agreement no. 101003890); and by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES on behalf of DHEFEUS -2022.09185.PTDC and the project FAIR- 2022.01660.PTDC).

How to cite: Durao, R., Alonso, C., Russo, A., and Gouveia, C.: The role of fire radiative power to estimate fire-related smoke pollution., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13237, https://doi.org/10.5194/egusphere-egu24-13237, 2024.

EGU24-13416 | ECS | Posters on site | BG1.1

Two decades of fire-induced albedo change and associated radiative effect over sub-Saharan Africa 

Michaela Flegrova and Helen Brindley

Fire is an important, widespread Earth-system process, influencing local ecosystems and climate around the globe. Over half of global burned area occurs in Africa, with over 10% of the continent affected by fire every year. Fire temporarily alters the surface properties, including surface albedo, causing long-lasting changes to the surface radiation budget.

We present the analysis of 20 years of fire and albedo data in Africa, using the MODIS product suite. We show that fire causes an average immediate albedo decrease, recovering exponentially with a time constant of several weeks. While the magnitude of albedo changes shows large spatial and temporal variations and a strong land cover type (LCT) dependency, exponential recovery is observed in the majority of LCTs. We show that fires cause long-term brightening, observing on average a small positive albedo change 10 months after a fire, but we find this is driven almost exclusively by slow vegetation recovery in the Kalahari region.

Using downward surface shortwave flux estimates we calculate the fire-induced surface radiative forcing (RF), peaking at 5±2 Wm−2 in the burn areas, albeit with a significantly smaller effect when averaged temporally and spatially. We find that the average long-term RF is negative because of the brightening observed.

Our temporal analysis does not indicate a decrease in overall fire-induced RF, despite a well-documented reduction in burning in Africa in the recent decades, suggesting that the RF of individual fires is increasing because of higher levels of downward surface shortwave flux. We hypothesise this may be due to lower levels of smoke aerosols in the atmosphere.

How to cite: Flegrova, M. and Brindley, H.: Two decades of fire-induced albedo change and associated radiative effect over sub-Saharan Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13416, https://doi.org/10.5194/egusphere-egu24-13416, 2024.

EGU24-14202 | Posters on site | BG1.1 | Highlight

Evaluation of global fire simulations in CMIP6 Earth system models 

Fang Li, Xiang Song, Sandy Harrison, and Zhongda Lin

       Fire is the primary form of terrestrial ecosystem disturbance globally and a critical Earth system process. So far, most Earth system models (ESMs) have incorporated fire modeling, with 19 out of them submitted fire simulations to the CMIP6. Transitioning from CMIP5 to CMIP6, much more models submitted fire simulations and the dominant fire scheme has evolved from GlobFIRM to the Li scheme. However, it remains unknown how well CMIP6 ESMs perform in fire simulations. This study provides the first comprehensive evaluation of CMIP6 fire simulations, through comparisons with multiple satellite-based datasets and the Reading Paleofire Database of global charcoal records (RPD).

        Our results show that most CMIP6 models simulate the global amounts of present-day burned area and fire carbon emissions within the range of satellite-based products, and reproduce observed major features of spatial pattern and seasonal cycle as well as the relationships of fires with precipitation and population density, except for models employing the GlobFIRM fire scheme. Additionally, most CMIP6 models can reproduce the response of interannual variability of tropical fires to ENSO, except for some models incorporating the SPITFIRE fire scheme. From 1850 to 2015, CMIP6 models generally agree with RPD, with some discrepancies in southern South America before 1920 and in temperate and eastern boreal North America, Europe, and boreal Asia after 1990. Compared with CMIP5, CMIP6 has solved the serious issues of CMIP5 which simulates the global burned area less than half of observations, fails to capture the high burned area fraction in Africa, and underestimates seasonal variability. CMIP6 fire carbon emissions simulations are also closer to RPD. However, CMIP6 models still fail to capture the present-day significant decline in observed global burned area and fire carbon emissions partly due to underestimation in anthropogenic fire suppression, and fail to reproduce the spring peak in NH mid-latitudes mainly due to an underestimation of crop fires. Based on our findings, we identify potential biases in fire and carbon projection based on CMIP6 models. We also provide suggestions for the fire scheme development, and bias correction methods when generating multi-source merged fire products.

How to cite: Li, F., Song, X., Harrison, S., and Lin, Z.: Evaluation of global fire simulations in CMIP6 Earth system models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14202, https://doi.org/10.5194/egusphere-egu24-14202, 2024.

EGU24-14446 | ECS | Posters on site | BG1.1

Wildland Fire Smoke and Emissions Tradeoff Decision Support 

Laurel Sindewald, Shawn Urbanski, Karin Riley, Christopher Eckerson, Alex Dye, and Rachel Houtmann

In 2023, 6,551 wildfires across Canada burned 184,961 km2 of the landscape—about 5% of Canadian forests—emitting nearly 480 megatonnes of carbon, with emissions leading to air quality warnings as far away as Washington DC, USA. In early June, the air quality index in New York City was over 400, and by mid-June, smoke plumes passed above Europe. As wildland fires of increasing severity occur with increasing frequency, driven by global climate change and decades of fire suppression, societies near and far from high-risk ecosystems face increased exposure to wildfire emissions that may have both acute and long-term health impacts. Prescribed fire interventions show promise for reducing the risk of large wildfires in fire-prone ecosystems, but implementing prescribed fire can be difficult, in part due to concerns about the potential health impacts of prescribed fire smoke on nearby communities. To provide decision support for land managers aiming to reduce wildfire risk with prescribed fire treatments, we will produce a geospatial database of daily pollutant emissions and fire intensity from simulations of prescribed and wildland fires over a 20-year period for: 1) a baseline scenario of no management actions, 2) one or more scenarios of prescribed fire locations and timing based on interaction with tribes and Okanogan-Wenatchee National Forest (OWNF) managers, and 3) scenarios of prescribed fire locations and timing based on fire paths, locations of highly valued resources, areas available and suitable for treatment, determined by the research team. We can accomplish this by iterating between FSim, the Large Fire Simulator, which stochastically simulates large wildfire ignition and spread across a LANDFIRE fuels landscape, and FFE-FVS, the Forest Vegetation Simulator with the Fire and Fuels Extension, which simulates post-fire regeneration, forest growth, management actions including prescribed fire, fuel dynamics, and fuel consumption and pollutant emissions from prescribed fires and wildfires. Because FSim takes a Monte Carlo approach, simulating fires over 10,000 or more hypothetical fire seasons comprised of daily weather sequences, we will be able to estimate the probability of each landscape pixel burning in a wildfire and the conditional probability of that pixel burning at different flame lengths, allowing us to provide emissions estimates within a risk-assessment framework for managers. The framework will allow land managers to quantify the likelihood that smoke impacts from near-term prescribed fire treatments will be offset by reductions in severe smoke events from future wildfires. Additionally, the smoke event geospatial datasets may provide input into atmospheric transport models which could be used to simulate regional to national scale smoke impacts. We will pilot the project in Okanogan-Wenatchee National Forest, Washington, USA, working with the forest’s managers to design fuel treatment scenarios that will yield realistic fire occurrence trajectories and emission estimates to inform near-term prescribed fire operations. As a U.S. Federal Bipartisan Infrastructure Law Research & Development “proof of concept” project, the Wildland Fire Smoke and Emissions Tradeoff Decision Support project will inform U.S. Forest Service management policy and strategy around the use of prescribed fire in other National Forests in the U.S.

How to cite: Sindewald, L., Urbanski, S., Riley, K., Eckerson, C., Dye, A., and Houtmann, R.: Wildland Fire Smoke and Emissions Tradeoff Decision Support, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14446, https://doi.org/10.5194/egusphere-egu24-14446, 2024.

EGU24-14748 | ECS | Posters virtual | BG1.1

Reconstructing human-fire-vegetation inter-relationships in a protected dry tropical forest, Mudumalai National Park, southern India 

Prabhakaran Ramya Bala, Nithin Kumar, Diptimayee Behera, Anoop Ambili, and Raman Sukumar

Tropical dry forests are recognized globally as the first frontier of human land-use change, due to multiple factors that make them amenable to human occupation, especially with the use of fire. However, in southern India, biodiversity ‘hotspots’ with human habitation are not uncommon with a long-term co-existence of humans in pristine environments. This points to the need for more accurate evidence-based (using charcoal, pollen, phytoliths) understanding of if, when and how land use and land cover changes impact regional vegetation-fire relationships. We reconstruct the environmental history for Mudumalai National Park, a fire-prone dry forest with >30% of the park subject to annual fires and a west-to-east rainfall-vegetation gradient. We examined a 150 cm sediment profile from an excavation in a seasonal wetland in the wettest part. The record spans 1200 years in time (bracketing radiocarbon dates) with very low macrocharcoal counts (mean - 4), with highest numbers in the surface and near-surface layers. Molecular fire proxies Polycyclic Aromatic Hydrocarbons (PAHs) were also found present - Phenanthrene (Phe), Anthracene (Ant), Fluoranthene (Fl), Pyrene (Py), Benzo[ghi]fluoranthene (Bghi), Benz[a]anthracene (BaA), Chrysene (Chr), Benzo(b)fluoranthene (BbF), Benzo(k)fluoranthene (BkF), Benzo[e]pyrene (BeP), Benzo[a]pyrene (BaP), and Perylene (Pry). Notably, Fl, Py, Bghi, BbF, BaA,and BeP constituted 90% of the total concentrations. Diagnostic ratios of PAHs for source determination pointed at a pyrogenic source consistently across all samples. Paleovegetation proxies n-alkanes (C14-C33) were analyzed and the average chain length (ACL) showed a transition towards higher chain lengths towards the surface indicating a change towards grass sources (C31, C33) in addition to woody biomass-derived compounds (C27, C29). Further analysis to characterize the human-fire-vegetation relationships is underway and to our knowledge, as the first report from a protected forest in India, our study offers critical insights for forest fire management in forested landscapes.

How to cite: Ramya Bala, P., Kumar, N., Behera, D., Ambili, A., and Sukumar, R.: Reconstructing human-fire-vegetation inter-relationships in a protected dry tropical forest, Mudumalai National Park, southern India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14748, https://doi.org/10.5194/egusphere-egu24-14748, 2024.

EGU24-14762 | Orals | BG1.1

Climate change has increased fire PM2.5 and its associated health burden 

Chaeyeon Park, Kiyoshi Takahashi, Shinichiro Fujimori, Thanapat Jansakoo, Chantelle Burton, Huilin Huang, Sian Kou-Giesbrecht, Christopher Reyer, Matthias Mengel, and Eleanor Burke

Climate change has influenced fire activities, altering the fire risk associated with air pollution and human health. However, the specific contribution of climate change to fire risks on air pollution and health burden has not yet been discovered. In this study, three fire-vegetation models were employed to simulate fire aerosol emissions under two simulations over the past six decades: an observation climate scenario and a counterfactual scenario where the long-term climate change trend is removed. Combining fire aerosol emissions with a chemical transport model and an avoidable mortality risk model, we calculated global fire PM2.5 and its associated mortality. By comparing the results under the two simulations, we demonstrated the climate change has increased the fire PM2.5 and its mortality. The findings indicated an increase in fire mortality over the six decades: 46,401 in the 1960s and 98,748 in the 2010s, with 3-8% attributed to climate change. Clear relationships were observed between the contribution of climate change to fire mortality and relative humidity or air temperature in some regions. This suggests that fire risks in these regions are sensitive to climate change and necessitate the development of adaptation strategies to mitigate risks in the future.  

How to cite: Park, C., Takahashi, K., Fujimori, S., Jansakoo, T., Burton, C., Huang, H., Kou-Giesbrecht, S., Reyer, C., Mengel, M., and Burke, E.: Climate change has increased fire PM2.5 and its associated health burden, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14762, https://doi.org/10.5194/egusphere-egu24-14762, 2024.

EGU24-14891 | Orals | BG1.1

Fire hazard trajectories under climate change and management scenarios 

Marcos Rodrigues, Pere Gelabert, Teresa Lamelas, Raúl Hoffrén, Juan de la Riva, Darío Domingo, Cristina Vega-García, Paloma Ibarra, Aitor Ameztegui, and Lluís Coll

In this work we showcase the in-progress results from the FirePATHS project (PID2020-116556RA-I00). The project aims to assess the evolution of fire danger under different emission and forest management scenarios through the explicit interaction of the climate-vegetation-fire system. For this purpose, a methodological framework combining different simulation models of the elements of this system is proposed. The core of the process lies in the modeling of vegetation dynamics at stand scale according to different trajectories of climatic evolution to characterize the state and typology of fuels and the subsequent simulation of potential fire behavior during the 21st century.

We analyzed a set of 114 Pinus halepensis plots, surveyed in the field during 2017;  68 plots burned during the summer of 1994 and 46 unburned control stands. We used the medfate model to simulate forest functioning and dynamics, which provides the necessary fuel model parameters to be entered into fire behavior models (Fuel Characteristics Classification System, implemented in medfate as well). The combination of these two approaches provides time-varying estimates of fire behavior metrics (e.g., flame length or rate of spread). The simulation was conducted under SSP climate scenarios (SSP 126, 245, 370 and 585) depicting different levels of climate warming, vegetation dynamics and, hence, fire danger. Likewise, we devised a set of forest management prescriptions aimed at reducing climate vulnerability of tree communities and reducing extreme wildfire potentials. A baseline scenario with no management was also assessed.

We observed very contrasting trajectories between burned and control stands, with the first leading to increasing fuel loads, except in SSP 585. Fire potentials depicted a significant increase in surface fire behavior, with adaptive and mitigation management being able to mitigate it to some extent.

How to cite: Rodrigues, M., Gelabert, P., Lamelas, T., Hoffrén, R., de la Riva, J., Domingo, D., Vega-García, C., Ibarra, P., Ameztegui, A., and Coll, L.: Fire hazard trajectories under climate change and management scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14891, https://doi.org/10.5194/egusphere-egu24-14891, 2024.

EGU24-15398 | Posters on site | BG1.1

Effects of recent increase in anomalous fires and smokes at high latitude regions on regional atmosphere 

Kwon-Ho Lee, Kwanchul Kim, and Dasom Lee

Spatiotemporal patterns and trends of atmospheric aerosols in high latitude region have been analyzed. Aerosol observation data from 2000-2022 acquired from the earth observing satellites including the Moderate Resolution Imaging Spectroradiometer (MODIS), the Ozone Monitoring Instrument (OMI), or geostationary satellites such as the Geostationary Korea Multi-Purpose Satellite-2A (GK-2A) . Results showed that Aerosol Optical Thickness (AOT) over the high latitude region has gradually decreased before 2016. However, AOT has increased significantly over the past 8 years. This increase was clearly shown in North America and North Asia, and was associated with an increase with fire activities. Smoke plumes originated from fire active fires transported eastward with meteorology, but occasionally moved toward the Arctic region. The occurrence of fires and the production and transport of aerosols will be a consequence or factor of the recent rapid climate change.

Acknowledgement: This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1I1A3A01062804).

 

How to cite: Lee, K.-H., Kim, K., and Lee, D.: Effects of recent increase in anomalous fires and smokes at high latitude regions on regional atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15398, https://doi.org/10.5194/egusphere-egu24-15398, 2024.

EGU24-15436 | ECS | Posters on site | BG1.1

Investigation of spatiotemporal variability in South American wildfire emissions and its impacts on CO concentrations 

Maria Paula Velasquez Garcia, Richard Pope, Steven Turnock, and Martyn Chipperfield

Wildfires in South America are a significant concern, causing high emissions and deforestation rates. They affect air quality, radiation balance, and sensitive ecosystems like the Amazon rainforest. Wildfires are expected to intensify with future land use and climate changes, making it crucial to enhance decision-making tools. Models of atmospheric composition, combined with wildfire emissions inventories, support decision-making by simulating events and their impacts on air quality. There are currently a range of wildfire/biomass burning emission inventories, which all use different approaches. This can lead to substantial differences in estimated emissions and thus impacts on atmospheric composition estimation.  This study aims to assess four inventories (2004-2022) in South America: Global Fire Emissions Database (GFED), Fire INventory from NCAR (FINN), Global Fire Assimilation System (GFAS) and Brazilian Biomass Burning Emission Model (3BEM-FRP), focussing on carbon monoxide (CO) given its relatively large emission and complementary satellite missions retrieving atmospheric CO. Our results analyse the temporal consistency in the emission seasonal cycles from the inventories and quantify the spatial agreement/differences between them. We also exploit the Measurements Of Pollution In The Troposphere (MOPITT) retrieved CO to assess the links between emission inventory tendencies with that of the atmospheric temporal evolution. Finally, we use an offline version of the INteractive Fire and Emission algoRithm for Natural envirOnments (INFERNO) model, within the Joint UK Land Environment Simulator (JULES) framework to investigate simulated skill of emissions of CO against the observational constraints above as INFERNO is the fire model of choice in the UK Earth System Model (UKESM).

How to cite: Velasquez Garcia, M. P., Pope, R., Turnock, S., and Chipperfield, M.: Investigation of spatiotemporal variability in South American wildfire emissions and its impacts on CO concentrations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15436, https://doi.org/10.5194/egusphere-egu24-15436, 2024.

EGU24-15518 | Posters on site | BG1.1

Integrating stakeholders’ opinion in land management to build climate resilience in the context of fire risk 

Valentina Bacciu, José Costa Saura, Grazia Pellizzaro, Bachisio Arca, Pierpaolo Duce, Donatella Spano, and Costantino Sirca

The Mediterranean region, already a climate change hotspot, is experiencing milder winters, hotter and drier summers, and increased extreme weather events, leading to longer fire seasons and increasing fire impacts. The socio-economic consequences of wildfires are significant, including the loss of human lives, infrastructure, and economic activity. Additionally, wildfires contribute significantly to climate change, accounting for up to 20% of global greenhouse gas emissions annually. Climate change is expected to worsen these conditions in the near future.

Given these circumstances, it is necessary to accelerate the transition towards the implementation of integrated and holistic fire management approaches aligned with future hazards. In the framework of The HUT project (The Human-Tech Nexus - Building a Safe Haven to cope with Climate Extremes), financed by the Horizon Europe program, the "Ogliastra-DEM8" case study (located in Sardinia, Italy) is aimed at responding to this necessity.

In particular, the main objective of The HUT is to mitigate the effects of climate-related events, by integrating and leveraging best practices and successful multi-disciplinary experiences and focusing on the prevention and preparedness phases of the disaster risk management cycle. In this context, the specific aim of the "Ogliastra-DEM8" case study is to provide the scientific/knowledge base needed to help policymakers and decision-makers defining adaptation and mitigation strategies that are effective in reducing fire impacts and associated costs in the short to medium-term under a changing climate. Towards this end, innovative tools (e.g., fire simulators, catastrophe insurance products, nature-based solutions) and stakeholder engagement, including participatory methods, will be developed.

This work presents the first phase of the work aimed at evaluating enablers and barriers to multi-hazard/systemic risk reduction by (i) reviewing the literature from other projects based in Sardinia, (ii) mapping and engaging stakeholders during an initial round of workshops, and (iii) debating fire-smart land management and adaptation options. Preliminary results indicate key barriers such as stakeholder conflicts, administrative silos, lack of political will, and funding complexities. All these elements contributed to varying degrees to the lack of a comprehensive approach towards integrated and sustainable management of the entire territory. On the other hand, enablers include stakeholder engagement, evidence of performance and co-benefits, and community awareness.

Further work will integrate stakeholder opinions into fire exposure and risk mapping under climate change conditions, with the goal of selecting and co-designing with them which fire-smart land management and adaptation options can be applied and where to protect the most important and vulnerable communities and ecosystems.

How to cite: Bacciu, V., Costa Saura, J., Pellizzaro, G., Arca, B., Duce, P., Spano, D., and Sirca, C.: Integrating stakeholders’ opinion in land management to build climate resilience in the context of fire risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15518, https://doi.org/10.5194/egusphere-egu24-15518, 2024.

EGU24-16087 | Posters on site | BG1.1

Assessing post-fire soil erosion and water contamination risk in European fire-affected catchmentswith WEPPcloud-EU WATAR watershed model 

Jonay Neris, Carmen Sánchez-García, Marta Basso, Roger Lew, Anurag Srivastava, Mariana Dobre, Pete Robichaud, Erin Brooks, Cristina Santin, and Stefan Doerr

Soil and ash are key sources of sediment, carbon, nitrogen, and associated pollutant movement following a wildfire. Their transport into freshwater systems can pose severe environmental and socio-economic implications including impacts to water quality and aquatic ecosystems, disruptions to drinking water supply and high remediation costs, as well as the depletion of carbon and nutrients from areas affected by erosion. We assessed the risk of soil erosion, ash and contaminant transport, and water contamination in three burned European catchments in Central Europe (Germany and the Czech Republic), Portugal and Spain using the European Water Erosion Prediction Project cloud interface with the Wildfire Ash Transport and Risk (WEPPcloud-EU WATAR) watershed model. The watersheds varied in size from 100 to 22,000 ha and represent distinct climatic conditions. To our knowledge, this is the first application of this model in European post-fire scenarios. We calibrated and validated the model using catchment runoff data (where available) and nearby streamflow data from both pre- and post-fire periods when runoff data was unavailable. Additionally, we used sediment transport data (where available) along with ash contaminant content data to calibrate and validate erosion and ash transport rates. Model performance was assessed using statistics like Nash-Sutcliffe Efficiency (NSE), coefficient of determination (R2) and percent bias (PBias (%)). Once the model was calibrated and validated, we estimated the post-fire risk of soil erosion, ash transport, and ash pollutant concentrations in the affected areas. The simulations provided the probabilities of occurrence and return periods for severe erosion events, as well as for ash and contaminant transport events. Based on these simulations, we identified hillslopes that were the main sources of runoff, erosion, ash and contaminant transport. This information is important to managers who can prioritize the application of mitigation treatments and prevention plans. Given the projected increase in fire weather in many regions in Europe, our findings suggest that the WEPPcloud-EU WATAR model is an increasingly useful tool in predicting and mitigating soil erosion and water contamination impacts of European burnt catchments.

How to cite: Neris, J., Sánchez-García, C., Basso, M., Lew, R., Srivastava, A., Dobre, M., Robichaud, P., Brooks, E., Santin, C., and Doerr, S.: Assessing post-fire soil erosion and water contamination risk in European fire-affected catchmentswith WEPPcloud-EU WATAR watershed model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16087, https://doi.org/10.5194/egusphere-egu24-16087, 2024.

EGU24-16263 | ECS | Orals | BG1.1

Fire, permafrost, and people: Late Holocene fire regimes and their impacts on lake systems in Yakutia, Siberia 

Ramesh Glückler, Elisabeth Dietze, Stefan Kruse, Andrei Andreev, Boris K. Biskaborn, Evgenii S. Zakharov, Izabella Baisheva, Amelie Stieg, Shiro Tsuyuzaki, Kathleen Stoof-Leichsenring, Luidmila A. Pestryakova, and Ulrike Herzschuh

The Republic of Sakha (Yakutia), the coldest permanently inhabited region on Earth, is characterized by unique ecological relationships between larch forest, permafrost, and wildfires. Together, they can stabilize each other, preserving the larch-dominated biome. Abundant lakes have important cultural and subsistence-related functions and are dynamically connected to warming permafrost processes. Recently intensified wildfire seasons, however, raised questions regarding the causes and impacts of long-term (centennial to millennial) fire regime changes. Despite recent progress, eastern Siberia is still sparsely covered by reconstructions of long-term fire history. This also limits any evaluation of fire regime impacts on permafrost lake development and catchment erosion. Past studies have shown the benefit of combining paleoecological fire reconstructions with geochemical data to shed light on fire regime changes and their impacts on lake catchments, as well as traces of potential human land use.

We present nine new records of Late Holocene wildfire activity, based on macroscopic charcoal in lake sediments (including information on charcoal particle sizes, morphologies, and length to width ratios), accompanied by sediment geochemistry data from high-resolution XRF core scanning. The studied lakes are located in the Lena-Amga interfluve of the Central Yakutian Lowlands, the Verkhoyansk Mountains, and the Oymyakon Highlands. The new data cover both thermokarst and glacial lakes, and a range from remote to rural settings and low to high elevations. Charcoal concentration in the lowland lakes is on average three times as high as in the highland lakes. Contrary to our hypothesis, charcoal concentration in most lakes is negatively correlated to many XRF-derived lithogenic elements indicating detrital input from catchment erosion (e.g., Ti, K). Reminiscent of earlier findings [1], multiple lowland sites share a signal of sharply decreasing biomass burning around 1300 CE. This coincides with the initial settlement of the Sakha people and increased catchment erosion. The new fire reconstructions allow for the evaluation of potential human impacts on past fire regime changes in Yakutia, while improving the region’s representation in global synthesis studies.

[1]  Glückler R. et al. (2021): Wildfire history of the boreal forest of south-western Yakutia (Siberia) over the last two millennia documented by a lake-sediment charcoal record. Biogeosciences 18 (13): 4185–4209. https://doi.org/10.5194/bg-18-4185-2021.

How to cite: Glückler, R., Dietze, E., Kruse, S., Andreev, A., Biskaborn, B. K., Zakharov, E. S., Baisheva, I., Stieg, A., Tsuyuzaki, S., Stoof-Leichsenring, K., Pestryakova, L. A., and Herzschuh, U.: Fire, permafrost, and people: Late Holocene fire regimes and their impacts on lake systems in Yakutia, Siberia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16263, https://doi.org/10.5194/egusphere-egu24-16263, 2024.

EGU24-16293 | ECS | Posters on site | BG1.1 | Highlight

Global atmospheric impacts of aerosols emitted from the 2023 Canadian wildfires 

Iulian-Alin Rosu, Matt Kasoar, Eirini Boletti, Mark Parrington, and Apostolos Voulgarakis

Wildfires are a central but relatively unexplored component of the Earth system. Severe wildfire events can lead to intense destruction of both nature and property, as was the case during the anomalously intense 2023 Canadian wildfire event. Last year, approximately 5% of the total forest area of Canada burned [1] [2], which is the highest wildfire damage Canada has ever sustained [1].

Conditions pertaining to climate change and modifications in atmospheric conditions are considered to be responsible for this record series of wildfires [3]. Increasing mean temperatures and decreasing humidity in the region has exacerbated wildfire risk. Carbon emissions from the 2023 Canadian wildfires have been the highest on record [4], including large amounts of carbonaceous aerosol which can exert substantial atmospheric radiative forcing. Also, Canadian fire emissions contributed around 20% of global emissions from vegetation fires. Thus, beyond the well-known health risks of wildfire emission compounds, it is important to also study the consequences of these emissions on large-scale atmospheric composition and meteorological behavior.

In this work, the global and regional atmospheric impact of the previously mentioned series of wildfires is investigated using the EC-Earth3 and UKESM1 earth system models. Simulated atmospheric conditions with and without the wildfire emissions, as provided by the Copernicus Atmosphere Monitoring Service (CAMS) Global Fire Assimilation System (GFAS), are compared through atmospheric modelling in the context of the Canadian 2023 fire season. The investigation reveals the connections between the emissions produced by this series of wildfires and atmospheric phenomena of importance, such as large-scale circulation, temperature patterns, and precipitation.

[1] "Fire Statistics". Canadian Interagency Forest Fire Centre. Retrieved January 4, 2024.

[2] The State of Canada’s Forests: Annual Report 2022. Canadian Minister of Natural Resources.

[3] Barnes, Clair, et al. "Climate change more than doubled the likelihood of extreme fire weather conditions in eastern Canada." (2023).

[4] “Copernicus: Emissions from Canadian wildfires the highest on record – smoke plume reaches Europe”. Atmosphere Monitoring Service, Copernicus. Retrieved January 4, 2024.

How to cite: Rosu, I.-A., Kasoar, M., Boletti, E., Parrington, M., and Voulgarakis, A.: Global atmospheric impacts of aerosols emitted from the 2023 Canadian wildfires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16293, https://doi.org/10.5194/egusphere-egu24-16293, 2024.

EGU24-16592 | ECS | Posters on site | BG1.1 | Highlight

Exploring the role of post-fire erosion as a carbon sink mechanism 

Antonio Girona-García, Diana Vieira, Stefan Doerr, and Cristina Santín

Wildfires release approximately 2.1 Pg C to the atmosphere each year. The impact of wildfires on the carbon cycle, however, extends well beyond direct emissions, involving complex interactions among various source and sink processes. One such process, the enhanced post-fire soil organic carbon (SOC) erosion, remains unquantified as a potential C sink mechanism. Post-fire SOC erosion functions as a C sink when the subsequent burial and stabilization of eroded C offsite, coupled with the recovery of net primary production and SOC content onsite, outweigh the C losses to the atmosphere during post-fire transport of SOC. In this work, we synthesize published data on post-fire SOC erosion and evaluate its overall potential to act as C sink. In addition, we estimate its magnitude at continental scale following the 2017 wildfire season in Europe, showing that SOC erosion can indeed play a quantitatively significant role in the overall C balance of wildfires. 

How to cite: Girona-García, A., Vieira, D., Doerr, S., and Santín, C.: Exploring the role of post-fire erosion as a carbon sink mechanism, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16592, https://doi.org/10.5194/egusphere-egu24-16592, 2024.

EGU24-16676 | ECS | Orals | BG1.1

Study of greenhouse gases emitted by biomass burnings with a decade of infrared observation of CO2 and CH4 by IASI 

Victor Bon, Cyril Crevoisier, and Virginie Capelle

Biomass burnings are one of the major sources of greenhouse gases in the atmosphere, impacting air quality, public health, climate, ecosystem dynamics, and land-atmosphere exchanges. In the tropics, South America represents about 10 % of the tropical emissions and present a large diversity of biomes and fire conditions. Over the last two decades, satellite observations have provided crucial information, notably via active fires detection, Fire Radiative Power (FRP) estimates and burned area (BA) measurements from imagers such as Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS). Global inventories (e.g., GFED, GFAS, FEER, QFED, etc.) heavily rely on these satellite-derived indicators to estimate emissions from biomass burnings. However, emissions derived from these various models can significantly differ among them and large uncertainties persist regarding fire emissions, their variability, and their links with several drivers (e.g., type of combustion, vegetation, transport, etc.).

In this context, we propose a novel approach to estimate emissions from biomass burnings by directly using greenhouse gas concentrations in the atmosphere derived from spaceborne observations. Leveraging a decade of observations from the Infrared Atmospheric Sounding Radiometer (IASI) on-board the three Metop satellites, we have access to an unprecedented spatial coverage of global mid-tropospheric CO2 and CH4 concentrations twice a day (9:30 AM/PM LT). From this dataset, we developed the Daily Tropospheric Excess (DTE) method, which is based on the use of the diurnal cycle of biomass burnings and the vertical transport of their emissions to link the observed diurnal variations of the mid-tropospheric CO2 and CH4 concentrations to burnings activities.

We will demonstrate the relevance of the DTE for analyzing CO2 and CH4 emissions from various type of burnings, biomes, and human activities across South America. This will be achieved by comparing DTE with existing indices of fire characteristics such as FRP and BA from MODIS/SUOMI satellite observations, alongside global emissions databases like GFED and GFAS. Globally, we will show that their spatial distribution, seasonal intensity, and interannual variability are consistent with each other, even if some differences have been found and will be discussed. Additionally, geostationary data from GOES-R, MSG, and Himawari-8 satellites will be used to analyze the impact of observation times on the differences observed between the various datasets and the DTE.

How to cite: Bon, V., Crevoisier, C., and Capelle, V.: Study of greenhouse gases emitted by biomass burnings with a decade of infrared observation of CO2 and CH4 by IASI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16676, https://doi.org/10.5194/egusphere-egu24-16676, 2024.

EGU24-17593 | Orals | BG1.1

Effect of combustion conditions on aerosol particle emissions from savanna and grassland fires 

Ville Vakkari, Angela Buchholz, Liqing Hao, Mika Ihalainen, Kerneels Jaars, Kajar Köster, Viet Le, Pasi Miettinen, Arya Mukherjee, Saara Peltokorpi, Iida Pullinen, Stefan J. Siebert, Olli Sippula, Markus Somero, Lejish Vettikkat, Annele Virtanen, Pasi Yli-Pirilä, Arttu Ylisirniö, and Pieter G. van Zyl

Fire is an integral part of savanna and grassland biomes and globally approximately half of landscape fire emissions originate from savannas and grasslands. Emissions of trace gases and aerosol particles from landscape fires are characterised by emission factors (EFs), which denote the amount of emitted substance per mass of combusted biomass. EFs vary depending on both the biomass that is consumed in the fire and the combustion characteristics of the fire, i.e. the ratio of flaming to smouldering combustion. However, emission inventories tend to use only one average EF for each biome.

Here, we use a set of 27 laboratory experiments to characterise the effect of combustion characteristics on submicron aerosol EFs from savanna and grassland biomass acquired from South Africa as well as boreal forest floor samples from Finland. Combustion experiments were carried out at the ILMARI facility in Kuopio, Finland from May to June 2022 under an open stack mimicking natural burning and dilution. Sample was injected into a 29 m3 environmental chamber for ageing studies. Chemical and physical properties of both fresh and aged smoke were observed with a host of instruments including e.g. AMS, FIGAERO-CIMS, VOCUS, SP2 and SMPS. The ratio of flaming to smouldering combustion was characterised by modified combustion efficiency (MCE), i.e. CO2/(CO2+CO).

The increase of organic aerosol EF with increasing smouldering fraction (i.e. decreasing MCE) was very similar for both the grassland and savanna combustion experiments. Surprisingly, also the boreal forest floor EFs closely follow the same trend, where smouldering-dominated combustion EFs are more than 10 times higher than EFs for flaming combustion. We observed also that the submicron aerosol particle size distribution shifts towards larger sized particles with increasing smouldering fraction. Furthermore, both the number and the mass of the size distribution cannot be fully characterised with a single log-normal size distribution, which needs to be considered when converting mass emissions into number size distribution in simulations.

How to cite: Vakkari, V., Buchholz, A., Hao, L., Ihalainen, M., Jaars, K., Köster, K., Le, V., Miettinen, P., Mukherjee, A., Peltokorpi, S., Pullinen, I., Siebert, S. J., Sippula, O., Somero, M., Vettikkat, L., Virtanen, A., Yli-Pirilä, P., Ylisirniö, A., and van Zyl, P. G.: Effect of combustion conditions on aerosol particle emissions from savanna and grassland fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17593, https://doi.org/10.5194/egusphere-egu24-17593, 2024.

EGU24-17935 | Posters on site | BG1.1

The FLARE Workshop perspective on Fire’s Role in the Carbon Cycle 

Chantelle Burton, Stephen Plummer, Noah Liguori-Bills, Morgane Perron, Douglas Kelley, Miriam Morrill, Boris Vannière, Joanne Hall, Stijn Hantson, Matthias Forkel, Christoph Völker, Kebonye Dintwe, Cristina Santin, Jessie Thoreson, Benjamin Poulter, Matthew Jones, and Douglas Hamilton

Fire substantially influences and modulates the global carbon cycle through numerous processes, interactions, and feedbacks. Fires are also strongly intertwined with human activities; people act both as drivers of change through ignitions, suppression, land-cover change, prescribed burning, and climate change, and are affected in return by changes in fire regimes. 

Despite fire’s many complex interactions throughout the Earth System, it is often viewed only as a destructive process, and one that solely acts as a source of atmospheric carbon. In terms of fire’s carbon budget, the release of carbon only represents the very initial stages of the process, missing the drivers and complex ways in which fire shapes plant species evolution and ecosystem trajectories, nutrient cycling and redistribution, carbon allocation, deposition and sequestration over different spatiotemporal scales. Therefore, there is a clear need to fully understand the role of fire in the Earth System holistically. However, different aspects of fire’s role in the carbon cycle are often studied by different communities and disciplines, hindering this much-needed integrated understanding. 

Through the Fire Learning AcRoss the Earth Systems (FLARE) workshop (September 2023) we brought together fire scientists across multiple disciplines to facilitate transdisciplinary discussion. We propose that the visualization of fire processes as carbon colours across the Earth System can be a thematic tool for unifying disciplines. It explores all aspects of fire and smoke implications for living systems and opens questions about fire’s role in carbon budgets, afforestation, and climate change and related mitigation strategies. We also identified several scientific challenges for the community where, by working together, we can address some fundamental questions for fire’s role in the carbon cycle, such as: What is the contribution of fire and of individual fire events to the global carbon cycle? How do changes in fire regimes influence ecosystem stability across different timescales? How do future changes in fire regimes influence global climate, allowable emissions and carbon budgets, and temperature mitigation ambitions? In this presentation, we explore how we can bring a more interdisciplinary approach to fire science to address these fundamental questions.

How to cite: Burton, C., Plummer, S., Liguori-Bills, N., Perron, M., Kelley, D., Morrill, M., Vannière, B., Hall, J., Hantson, S., Forkel, M., Völker, C., Dintwe, K., Santin, C., Thoreson, J., Poulter, B., Jones, M., and Hamilton, D.: The FLARE Workshop perspective on Fire’s Role in the Carbon Cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17935, https://doi.org/10.5194/egusphere-egu24-17935, 2024.

EGU24-18169 | ECS | Posters on site | BG1.1 | Highlight

What makes a fire grow extremely large? 

Rebecca Scholten, Tirtha Banerjee, Yang Chen, Ajinkya Desai, Tianjia Liu, Douglas Morton, Sander Veraverbeke, and James Randerson

Wildfires are an important disturbance in global ecosystems and are a critical driver of trends in the land carbon budget. Fire is an extreme phenomenon, with the largest burned area often occurring during extreme fire seasons generating large fires. Days with fire conditions conducive to fire ignition and spread are increasing in a warming climate in many regions of the world, contributing to increases in fire occurrence and annual burned area. However, the climate, fuel, and weather conditions that lead to extremely large fires in different biomes are poorly understood.

Here, we explore the temporal evolution of extremely large fires in temperate and boreal regions using new satellite-derived fire event tracking datasets optimized to match higher resolution time series of fire progression from aircraft and other sources. We aimed to understand the specific environmental conditions required for the development of a large fire. Our analysis revealed a disproportionate impact of multiple fire ignitions in creating large fires through merging. Our findings suggest that the largest fires in both biomes may be commonly created through multiple fires growing together. We hypothesize that a combination of physical and anthropogenic factors may accelerate merging, making these fires extremely difficult to contain and more robust to environmental controls regulating extinction. In our analysis, we use the Fire Events Database, the Arctic-boreal Fire Atlas, and GOFER, which enable attribution of ignition sources. Our analysis may contribute to an improved understanding of the influence of large-scale lightning storms in creating extremely large and destructive fire events.

How to cite: Scholten, R., Banerjee, T., Chen, Y., Desai, A., Liu, T., Morton, D., Veraverbeke, S., and Randerson, J.: What makes a fire grow extremely large?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18169, https://doi.org/10.5194/egusphere-egu24-18169, 2024.

EGU24-18811 | Posters virtual | BG1.1

Taking advantage of satellite data, large datasets of fire records and cloud computing for modelling potential fire severity useful for better assess fire risk 

José Maria Costa Saura, Valentina Bacciu, Donatella Spano, and Costantino Sirca

Fire risk analyses, usually focused on fire hazard (i.e. the probability of fire occurrence), often neglect an important issue such as the sensitivity/vulnerability (i.e., the degree of potential damage, sensus IPCC) of different locations within the area of interest.  Such lack of consideration comes from past data processing constrains that limited fire severity studies to analyse only single or few fire events. Nowadays, online data repositories and processing platforms (e.g. Google Earth Engine) allow to easily integrate and process a vast amount of data from multiple sources that might prove useful for developing tailored tools for decision making. Here, we present an example for predicting potential fire severity based on the analysis of more than 1 000 fire events from southern France and western Italy which integrates climate, topographical and remote sensing variables. Furthermore, we assessed if the model “used” the explanatory variables under a meaningful biophysical sense.   Using the random forest algorithm and the relativized difference of the Normalized Burn Ratio (rdNBR) as proxy of fire severity, we reach to explain up to 75% of the variability in the data with most of the variables showing a clear and interpretable effect. Our results suggests that this type of approach might prove useful for better address fire risk assessments.

How to cite: Costa Saura, J. M., Bacciu, V., Spano, D., and Sirca, C.: Taking advantage of satellite data, large datasets of fire records and cloud computing for modelling potential fire severity useful for better assess fire risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18811, https://doi.org/10.5194/egusphere-egu24-18811, 2024.

EGU24-18894 | ECS | Posters virtual | BG1.1

Mapping open burning of agricultural residues from Earth Observations 

Eduardo Oliveira, João Gata, Diogo Lopes, Leonardo Disperati, Carla Gama, and Bárbara Silva

Agricultural residue burning is a common practice in various regions of the world, which may have several environmental impacts, including on air quality, and the potential for triggering wildfires. In Portugal, this practice is particularly prevalent during the wet season, spanning from October to April. It involves open field burning of pruning residues and extensive burning to clear shrubbery, creating pastures for livestock. This research, conducted within the framework of the PRUNING project - Mapping open burning of agricultural residues from Earth Observations and modelling of air quality impacts- aims to explore the potential for detecting such events through satellite remote sensing.

The primary focus of this study is to assess the limitations of satellite remote sensing detection, with the overarching aim of integrating these findings into a systematic monitoring framework for open burning of agricultural residues. Additionally, the study aims to predict pollutant emissions and assess their impacts on air quality, providing valuable insights for environmental management and sustainable agricultural practices.

To achieve this goal, an in-depth analysis of known burning events was conducted using infrared thermal sensors. Multiple products, including Fire Radiative Power and fire masks from various sensors (e.g., MODIS, VIIRS, and Sentinel 3), were employed to characterize these known open field burning events. The results of this work allow verifying the tradeoffs effects associated with spatial, spectral, and temporal resolutions for each sensor, elucidating their impacts on the precision and accuracy of event detections. In parallel, this study evaluated the accuracy of the MINDED-FBA method in characterizing these known events. This automatic detection method, allows incorporating data from higher spatial resolution sensors (e.g., Sentinel-1, Sentinel-2, Landsat), for determining the extent of burned areas through multiple multispectral indices. In this context, the MINDED-FBA method may also be used to validate thermal anomalies detection products. Finally, the results of this work have also been compared to a national level register database of open burning, provided by the ICNF (Institute for Nature Conservation and Forests).

How to cite: Oliveira, E., Gata, J., Lopes, D., Disperati, L., Gama, C., and Silva, B.: Mapping open burning of agricultural residues from Earth Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18894, https://doi.org/10.5194/egusphere-egu24-18894, 2024.

EGU24-18941 | Orals | BG1.1

Arctic peat fire emissions estimated from satellite observations of fire radiative power 

Johannes Kaiser, Kerstin Stebel, Philipp Schneider, and Vincent Huijnen

Exceptional wildfire activity occurred in the Arctic during the last years due to pronounced heat episodes. The Arctic has an abundance of peat and soils with organic content. When peat is burnt, the carbon flux into the atmosphere is virtually irreversible and this process may become of global significance for Arctic fires. Furthermore, smoke from smoldering fires (below-ground, peat) has a different chemical composition than smoke from flaming fires. It is therefore important to distinguish peat fires and above-ground, potentially flaming fires in fire emission estimation.

The operational Copernicus Atmosphere Monitoring Service (CAMS) is tracking global fire activity and emissions with its Global Fire Assimilation System (GFAS) as a near-real time service. GFAS uses satellite-based observations of fire radiative power (FRP), which links observed thermal radiation directly to the biomass combustion rate, i.e. amount of biomass burnt and corresponding emission of carbon into the atmosphere, based on satellite retrievals from MODIS and VIIRS. 

Here, we present a partitioning of the Arctic fire activity represented in GFAS into smoldering below-ground and potentially flaming above-ground fires using two approaches: (1) masking the fire activity maps with published peat maps and (2) analysing the observed diurnal cycles of the fire activity at all locations. We subsequently apply adapted emission factors and compare the resulting emission estimates to the standard values produced by CAMS for carbon, carbon monoxide, nitrogen dioxide and aerosols.

Furthermore, we may confront the fire emission estimates with independent atmospheric smoke observations by feeding them into IFS-COMPO, which is used to generate hindcasts of atmospheric composition, including tropospheric columns of CO and NO2. This allows an evaluation of the estimated trace gas emissions, by comparing the model simulations to satellite retrievals of carbon monoxide and nitrogen dioxide. It thus provides an independent assessment of the estimated fire emissions, and, in turn, carbon flux.

How to cite: Kaiser, J., Stebel, K., Schneider, P., and Huijnen, V.: Arctic peat fire emissions estimated from satellite observations of fire radiative power, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18941, https://doi.org/10.5194/egusphere-egu24-18941, 2024.

EGU24-18977 | Orals | BG1.1 | Highlight

Global seasonality of small-scale livelihood fire 

Matthew Kasoar, Cathy Smith, Ol Perkins, James Millington, and Jayalaxshmi Mistry

Landscape fires are increasingly represented in dynamic global vegetation models to understand impacts on carbon emissions and climate. Deliberate human fire use and management influence landscape fire characteristics, varying in space and time depending on social, economic, and ecological factors. For example, fire is used variously in rural livelihoods involving e.g., agriculture, hunting, gathering, and for other cultural practices, often depending on the time of year. Yet existing global fire models typically represent human fire use as a constant function of gridded datasets such as population density or gross domestic product.

Recently, initiatives have begun to draw together available data on global fire use from across multiple disciplines and disparate sources into coherent databases. We draw on information from one of these databases, the Livelihood Fire Database (LIFE), which includes case studies in 587 locations worldwide, to assess the availability of data on seasonality of anthropogenic fires associated with small-scale rural livelihoods. By defining seasonal cycles relative to the local variation of precipitation and evapotranspiration at each case study location, we look for patterns in the spatiotemporal nature of anthropogenic fires associated with different fire-use purposes - such as clearing vegetation for agriculture, maintaining pasture for livestock, or driving game when hunting - and consider the potential for this analysis to inform fire models.

For many fire types, especially those related to hunting, gathering, human wellbeing, and social signalling, there are limited quantitative data available, but it is possible to draw qualitative insights from case studies. Where quantitative data are available, we find some correspondence between fire seasonality and the intended fire-use purpose, suggesting that distinguishing between distinct fire-use purposes could improve the representation of human fire use in fire models, and consequently the seasonal cycle of fire emissions. Case studies demonstrate that environmental and social conditions drive variation in fire use for the same purpose, reiterating that a wide range of factors influence human behaviour and that assumptions of uniform drivers of anthropogenic fire may be misleading. Many of the fires now being revealed in global burned area data by new fine-scale remote sensing products are likely human-set; continued collection, collation, and analyses of data on human fire use globally is important to ensure appropriate anthropogenic representation in fire models.

How to cite: Kasoar, M., Smith, C., Perkins, O., Millington, J., and Mistry, J.: Global seasonality of small-scale livelihood fire, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18977, https://doi.org/10.5194/egusphere-egu24-18977, 2024.

EGU24-19223 | ECS | Posters virtual | BG1.1

Monitoring wildfires from satellite, integration in Copernicus services and characterizing atmospheric impacts from the regional to the global scales 

Dominika Leskow-Czyżewska, Stephan Bojinski, Julien Chimot, Andrea Meraner, Mark Parrington, and Federico Fierli

Satellite-borne observations offer the possibility to monitor wildfires and their impact worldwide. In addition, satellite products are increasingly used in early warning and forecasting systems for fire management. Europe is implementing a long-term and reliable observational programme and, within this frame, EUMETSAT, the European meteorological satellite operator, provides numerous observational products ranging from near-real-time wildfire identification (e.g. fire radiative power) to atmospheric impacts (e.g. major pollutants and smoke). 

Our presentation will focus on the satellite data value chain, e.g. the integration in the Copernicus Atmosphere Monitoring Service (CAMS) Global Fire Assimilation System (GFAS). To do that, we will firstly present datasets addressing wildfires (e.g. Fire Radiative Power, atmospheric composition, and smoke) currently generated at EUMETSAT and its Satellite Applications Facility (SAF). We will also introduce upcoming (based on the Flexible Combined Imager on-board the Meteosat Third Generation) and future products (Sentinel-4 and 5), with an example of potential joint use for a past intense fire case in the Mediterranean (Greece, August 2023).  

We will then show the entire value chain, including how the data is used in the Copernicus Atmosphere Monitoring Service (CAMS) Global Fire Assimilation System (GFAS), with an example on the recent intense and anomalous fire season in Canada (spring to summer 2023). This will show how distinct phases of wildfires management – from early warnings up to the impacts on yearly emissions – can be monitored with the synergy of satellite data and Copernicus forecast and analysis. Finally, we will touch also on the user support activities within EUMETSAT in this area. 

How to cite: Leskow-Czyżewska, D., Bojinski, S., Chimot, J., Meraner, A., Parrington, M., and Fierli, F.: Monitoring wildfires from satellite, integration in Copernicus services and characterizing atmospheric impacts from the regional to the global scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19223, https://doi.org/10.5194/egusphere-egu24-19223, 2024.

EGU24-19330 | Orals | BG1.1

Burned Area Mapping with Sentinel-2 based on reflectance modelling and deep learning – preliminary global calibration and validation 

Marc Padilla, Ruben Ramo, Sergio Sierra, Bernardo Mota, Roselyne Lacaze, and Kevin Tansey

Current global burned area products are available at coarse spatial resolutions (300-500 m), what leads to large amounts of errors, hindering an accurate understanding of fire-related processes. This study proposes a global calibration method for a sensor-independent burned area algorithm, previously used with 300 m Sentinel-3 Synergy data, and here implemented with 20 m Sentinel-2 MSI imagery. A binomial model that combines reflectance-based burned area predictions constrained by spatio-temporal densities derived from VIIRS active fires is calibrated using a reference dataset generated from Landsat imagery at a sample of 34 units across the globe. Preliminary leave-one-out cross-validation analyses show promisingly high accuracies (Dice of coefficient of 84.8%, commission error ratio of 13.2%, omission error ratio of 17.1% and relative bias of -4.5%), especially taking into account the mismatch of acquisition dates between reference and algorithm input data, what introduces apparent errors on the validation results.

How to cite: Padilla, M., Ramo, R., Sierra, S., Mota, B., Lacaze, R., and Tansey, K.: Burned Area Mapping with Sentinel-2 based on reflectance modelling and deep learning – preliminary global calibration and validation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19330, https://doi.org/10.5194/egusphere-egu24-19330, 2024.

EGU24-19716 | ECS | Posters on site | BG1.1

"Fire impacts in the Cerrado: Integrating LiDAR and field data to monitor vegetation structure and post-fire recovery." 

Manoela Machado, Wesley da Cruz, Maria Antonia Carniello, Emily Sturdivant, Francisco Navarro-Rosales, Marcia Macedo, Wayne Walker, and Imma Oliveras Menor

Fire is a natural disturbance capable of altering plant distributions and community assemblages, influencing species evolution through the selection of traits and strategies, and affecting biogeochemical cycles. This powerful tool of landscape transformation can negatively impact even a fire-dependent ecosystem when natural fire regimes are altered. In recent times, interactions between human activities in the Cerrado (e.g., deforestation and intentional fires used to clear land), and a hotter and drier climate (due to climate change), have altered natural fire regimes causing more frequent and intense fire events, negatively impacting biodiversity, human health, and the regional climate. These fire-disturbed areas are widespread and highly vulnerable to future degradation from compounding disturbances, but they still harbour valuable biodiversity and carbon stocks that deserve protection and restoration. Monitoring the impacts of fire disturbance on vegetation structure and the potential pathways of recovery is critical to understand and protect resilient ecosystems under a rapidly changing climate. Robust monitoring requires the integration of modelled and field-based data tools and techniques. Field inventories alone are insufficient to capture the spatiotemporal variability of impacts of fire on native vegetation and should be coupled with remotely sensed data, among which, LiDAR (light detection and ranging) is unparalleled in characterising 3-D vegetation structure. Thus, the combination of LiDAR and forest inventory data is ideally suited for scaling the impacts of fire on forest vegetation and associated carbon stocks. In this study, we are assessing key metrics of vegetation structure derived from a combination of LiDAR and field data collected at the Experimental Station Serra das Araras, Mato Grosso state, Brazil. This field site comprises Cerrado vegetation that has been subject to three experimental fire treatments: every year, every two years, and every three years beginning in 2017, as well as fire suppression for over three decades. We are investigating whether key vegetation structural metrics can capture different fire treatments and identify spatial patterns of disturbance. We are also assessing if these patterns are different when comparing LiDAR data collected with a handheld scanner versus an airborne drone. This study aims to refine our methods and improve our understanding of vegetation structure responses across a gradient of fire disturbance regimes and potential post-fire recovery trajectories, which are key not only for ecological studies but also for emerging carbon markets – one of several mechanisms aimed at achieving climate change mitigation, conservation, and sustainable development outcomes. We hope to improve the process of carbon stock mapping in disturbed ecosystems and use the outputs to drive scenarios modelling at larger scales, providing a more comprehensive assessment of what future Cerrado carbon dynamics might look like under a range of possible disturbance/recovery dynamics.

How to cite: Machado, M., da Cruz, W., Carniello, M. A., Sturdivant, E., Navarro-Rosales, F., Macedo, M., Walker, W., and Oliveras Menor, I.: "Fire impacts in the Cerrado: Integrating LiDAR and field data to monitor vegetation structure and post-fire recovery.", EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19716, https://doi.org/10.5194/egusphere-egu24-19716, 2024.

EGU24-20564 | ECS | Orals | BG1.1 | Highlight

Future global wildfire regimes under high and low climate mitigation efforts  

Olivia Haas, Colin Prentice, and Sandy P. Harrison

There is growing concern over future trajectories of burning on Earth. One the one hand, some regions have seen the emergence of large and novel wildfires, whilst satellite observations continue to show declining burnt area globally, most notably in the tropics. Quantifying the response of global wildfire regimes to future changes in especially challenging given that wildfires are driven by climate, vegetation, and human activities, and that these different factors may have contrasting and opposing effects.

Using global empirical models of burnt area, fire size and fire intensity we explore the trajectory of future fire regimes under high and low climate change mitigation efforts. The models are driven by lightning ignitions, climate, vegetation properties, topography, and human factors. Making use of a set of sensitivity analysis, we show a global shift in wildfire patterns by the end of the 21st century even with warming kept below 1.5°. Burning will generally be reduced in tropical regions but larger and more intense wildfires will occur in extra-tropical regions. Under low mitigation, increases in burnt area worldwide overwhelm the human-driven decline, with up to a 60% increase in burnt area by the end of the century. However, fire size and intensity will be increasingly limited by dryness and vegetation fragmentation.

These results suggest that even under high climate change mitigation, fire management strategies must urgently be revised as current fire-suppression policies will no longer be effective in much of the world. Regional-level fire management, led by local stakeholders, should be encouraged. Wildfire risk and management must also be incorporated into mitigation scenarios that rely on extending forest area if these mitigation scenarios want to remain realistic.

How to cite: Haas, O., Prentice, C., and Harrison, S. P.: Future global wildfire regimes under high and low climate mitigation efforts , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20564, https://doi.org/10.5194/egusphere-egu24-20564, 2024.

EGU24-381 | ECS | Posters on site | CR7.7

Effects of Arctic sea-ice concentration on turbulent surface fluxes in four atmospheric reanalyses 

Tereza Uhlíková, Timo Vihma, Alexey Karpechko, and Petteri Uotila

A prerequisite for understanding the local, regional, and hemispherical impacts of Arctic sea-ice decline on the atmosphere is to quantify the effects of sea-ice concentration (SIC) on the turbulent surface fluxes of sensible and latent heat in the Arctic.

The best available information in data-sparse regions such as the Arctic is provided by global atmospheric reanalyses. Because each reanalysis uses its own forecast model, data-assimilation system, and often also different atmospheric and surface observations to create the data sets, their atmospheric and surface variables, and boundary conditions often differ. While the differences between reanalyses in variables SIC, latent and sensible heat flux have been demonstrated via comparisons against observations and inter-comparisons between reanalyses, how much these data sets scatter in the effects of SIC on surface turbulent fluxes is not known.

To fill these knowledge gaps, we analyse these effects utilising four global atmospheric reanalyses: ERA5, JRA-55, MERRA-2, and NCEP/CFSR (CFSR and CFSv2), and evaluate their uncertainties arising from inter-reanalysis differences in SIC and in the sensitivity of the turbulent surface fluxes to SIC.

Using daily field means in nine Arctic basins, the magnitude of the differences in SIC is up to 0.15, but typically around 0.05 during all four seasons. Bilateral orthogonal-distance regression analyses indicate that the greatest sensitivity of both the latent and the sensible heat flux to SIC occurs in the cold season, November to April. For these months, using daily means of data, the average sensitivity is 400 W m-2 for the latent heat flux and over 800 W m‑2 for the sensible heat flux per unit of SIC (change of SIC from 0 to 1, positive sign referring to the downward flux). The differences between reanalyses are as large as 300 W m-2 for the latent heat flux and 600 W m-2 for the sensible heat flux per unit of SIC. The sensitivity is highest for the NCEP/CFSR reanalysis. Comparing two study periods 1980–2000 and 2001–2021, we find that the effect of SIC on turbulent surface fluxes has weakened, due to the increasing surface temperature of sea ice and the sea-ice decline.

Multilateral ordinary-least-square regression analyses show that the effect of SIC on turbulent surface fluxes arises mostly via its effect on atmosphere-surface differences in temperature and specific humidity, whereas the effect of SIC on wind speed (via surface roughness and atmospheric-boundary-layer stratification) partly cancels out in the turbulent surface fluxes, as the wind speed increases the magnitude of both upward and downward fluxes.

How to cite: Uhlíková, T., Vihma, T., Karpechko, A., and Uotila, P.: Effects of Arctic sea-ice concentration on turbulent surface fluxes in four atmospheric reanalyses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-381, https://doi.org/10.5194/egusphere-egu24-381, 2024.

EGU24-450 | ECS | Posters on site | CR7.7

Impact of stratospheric polar vortex variability on Antarctic surface climate and sea ice 

Bianca Mezzina, Froila M. Palmeiro, and Hugues Goosse

The interannual variability of Antarctic sea ice is considered to be mainly driven by tropospheric and oceanic processes. However, the stratosphere also constitutes a possible source of sea ice variability. The stratospheric variability in the southern high latitudes is dominated by the stratospheric polar vortex (SPV), an extremely cold air mass confined to the pole by strong westerly winds. The SPV is characterized by a large seasonal cycle, peaking in austral winter and breaking down in late spring (with the so-called stratospheric final warming, SFW), but also by interannual variations. While there is robust evidence of a downward impact of the polar stratospheric variability on the Northern Hemisphere surface climate, including sea ice, whether a similar link is present in the Southern Hemisphere is still unsettled.

Here, we perform a multi-model assessment of the impact of the dynamical state of the SPV on Antarctic surface climate and sea ice by applying the same experimental protocol to three state-of-the-art general circulation models (GCMs): EC-EARTH, CMCC-ESM and CanESM. The three GCMs have similar ocean and sea ice components but different atmosphere.

First, we examine 200-year control experiments and compare them to observations. To assess the impact of the SPV state on the surface and sea ice, we build composites of “strong” and “weak” SPV years based on the late-winter stratospheric conditions. We then compare the anomalous patterns of sea ice concentration during the following spring, as well as anomalies of atmospheric fields such as sea-level pressure and surface temperature. To detect the possible downward stratosphere-troposphere coupling, we also compute the temporal evolution of vertical profiles of zonal-mean zonal wind and temperature. A similar analysis is also carried out using composites based on the timing of the SFW (“early” versus “late”).

To further isolate the potential role of the polar stratosphere in driving Antarctic surface climate, we run an additional set of sensitivity experiments with suppressed stratospheric variability. For each model, we build 200-member ensembles of 1-year long runs initialized from the control experiment, with the polar stratosphere nudged to the models' climatology, while the troposphere and the extra-polar stratosphere evolve freely. We then compare the variability of Antarctic sea ice and surface climate in these sensitivity experiments to that of the control run and investigate changes in the suggested mechanisms for the stratospheric downward influence.

How to cite: Mezzina, B., Palmeiro, F. M., and Goosse, H.: Impact of stratospheric polar vortex variability on Antarctic surface climate and sea ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-450, https://doi.org/10.5194/egusphere-egu24-450, 2024.

EGU24-2610 | Posters on site | CR7.7

Similarities and differences in circulation beneath the Filchner-Ronne and Ross Ice Shelves: Lagrangian point of view 

Vladimir Maderich, Roman Bezhenar, Igor Brovchenko, Dias Fabio Boeira, Cecilia Äijälä, and Petteri Uotila

The two world’s largest ice shelves, the Filchner-Ronne Ice Shelf (FRIS) and the Ross Ice Shelf (RIS) account for half the area of Antarctic ice shelves. They play a key role in transforming water masses on the shelf and forming Antarctic Bottom Water.

The objective of the work was to study the similarities and differences of circulation under the FRIS and RIS using the data of numerical simulation of currents, temperature, and salinity in the Weddell and Ross Seas from the Whole Antarctica Ocean Model (WAOM). The modelling results were used to run the particle-tracking model Parcels for computing Lagrangian particle trajectories. Three Lagrangian characteristics were calculated for FRIS and RIS: (i) Visitation frequency is defined as the percentage of the particles P visited each 2x2 km grid column at least once in a period of modelling (20 y); (2) Representative particle trajectory is the particle trajectory which deviates least from rest of trajectories; (iii) The mean age is the age of particles visited each 2x2 km grid column at least once.

The representative particle trajectories show that anticyclonic circulation beneath the FRIS and RIS is caused by the inflow of High Salinity Shelf Water (HSSW) through troughs off the western coast of the Weddell and Ross Seas. Transformed into ISW water, it flows out through the troughs in these seas. Part of the transformed water under the FRIS flows out through the Filchner Trough between Berkner Island, while water under RIS flows into the Ross Sea in the strait between Roosevelt Island and the shore. The eastern part of RIS is not ventilated by water inflowing from Ross Island. It is slowly ventilated by water entering a trough between Roosevelt Island and the eastern coast of the Ross Sea. Visitation frequency and representative trajectories suggest similar paths for water mass entering RIS in all seasons. Except December-February particles in anticyclonic gyre can return under RIS. Meanwhile, for particles released in January-August, outflows from FRIS took place through both the Ronne and Filchner ice fronts. In the October-December release the outflow through the Ronne ice front essentially exceeds flow through the Filchner depression.

How to cite: Maderich, V., Bezhenar, R., Brovchenko, I., Fabio Boeira, D., Äijälä, C., and Uotila, P.: Similarities and differences in circulation beneath the Filchner-Ronne and Ross Ice Shelves: Lagrangian point of view, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2610, https://doi.org/10.5194/egusphere-egu24-2610, 2024.

This study investigates the Arctic sea ice concentration trend during 1979-2021 and explores why the autumn Arctic sea ice loss is accelerated after 2002 and its trend declining center shifts from the Chukchi Sea to the Barents-Kara-Laptev Seas. Attribution analysis reveals that the enhanced summer sea ice concentration negative trend in large part explains the autumn sea ice concentration accelerating reduction, whereas it is the trend center shift of increased downward longwave radiation that accounts for mostly of the autumn sea ice concentration decline center shift. Further analysis suggests the downward longwave radiation trend is closely related to large-scale atmospheric circulation changes. A tendency towards a dipole structure with an anticyclonic circulation over Greenland and the Arctic Ocean and a cyclonic circulation over Barents-Kara Seas enhances (suppresses) the downward longwave radiation over Western (Eastern) Arctic by warming and moistening (cooling and drying) the lower troposphere during 1979-2001. In comparison, a tendency towards a stronger Ural anticyclone combined with positive phase of the North Atlantic Oscillation pattern significantly promotes the increase of downward longwave radiation over Barents-Kara-Laptev Seas during 2002-2021. Our results set new insights into the Arctic sea ice variability and deepen our understanding of the climate change.

How to cite: Jiang, Z.: Two distinct declining trend of autumn Arctic sea ice concentration before and after 2002, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2781, https://doi.org/10.5194/egusphere-egu24-2781, 2024.

EGU24-5533 | ECS | Posters on site | CR7.7

Updated sea ice code and atmospheric forcing improve the Antarctic summer sea ice of an ocean model 

Cecilia Äijälä, Yafei Nie, Lucia Gutierrez-Loza, Chiara De Falco, Siv Kari Lauvset, Bin Cheng, and Petteri Uotila

The ocean and sea ice play an important role in the Antarctic climate system, and the atmosphere plays an important role in forcing the sea ice and the ocean. A better understanding of these interactions is needed to understand recent changes and anticipate future changes in the Antarctic. ​

We present a regional ocean model MetROMS-UHel for a quarter-degree resolution domain of the Antarctic Ocean. MetROMS-UHel is based on the MetROMS-Iceshelf model that uses ROMS (Regional Ocean Modeling System), with ocean-ice shelf thermodynamics. For the sea ice, MetROMS-Iceshelf uses CICE (Community Ice CodE) 5.1.2., while MetROMS-UHel has been updated to CICE 6.3.1. We run both models with two different atmospheric forcings, ERA-Interim (ECMWF Re-Analysis ERA-Interim from 1992 to 2018) and ERA5 (ECMWF Reanalysis v5 from 1992 to 2023). The atmospheric reanalysis plays an important role in the results, and this way we see which changes are due to the updated sea-ice model and which are from the updated atmospheric forcing.

The models simulate the interannual variability of the Antarctic sea ice extent reasonably well. The sea ice extent is similar for all model runs and close to observed in all seasons except JFM. In JFM the extent varies between the models especially in the Ross and Weddell Seas, with the largest, and closest to observed extent produced by the MetROMS-UHel CICE 6, ERA5 run. Important watermasses are well represented by the models, with cold waters being slightly fresher in the MetROMS-UHel runs.

How to cite: Äijälä, C., Nie, Y., Gutierrez-Loza, L., De Falco, C., Lauvset, S. K., Cheng, B., and Uotila, P.: Updated sea ice code and atmospheric forcing improve the Antarctic summer sea ice of an ocean model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5533, https://doi.org/10.5194/egusphere-egu24-5533, 2024.

EGU24-5813 | ECS | Orals | CR7.7

Antarctic sea ice sensitivity to the orographic gravity wave drag in a fully coupled climate model  

Maria Vittoria Guarino, Jeff Ridley, Riccardo Farneti, Fred Kucharski, and Adrian Tompkins

Low-level winds over Antarctica are overwhelmingly controlled by the local orography. They, in turn, exert a large control on sea ice formation and transport.

In Global Circulation Models, the influence of orography on the climate system is modelled via orographic gravity wave drag (OGWD) parameterizations. Models usually partition the drag exerted on the atmosphere by the sub-grid scale orography into two components due to flow blocking and gravity waves.

In this work, we investigate the relationship between Antarctic sea ice and the parameterized OGWD in the UK Earth System Model (UKESM). We present results from sensitivity tests performed using the UKESM-CMIP6 historical runs.
In these simulations, the partition between the “flow-blocking” component and the “gravity wave” component of the OGWD parameterization was altered to simulate “flow-over” and “flow-blocking” regimes. These experiments show that sea ice strongly responds to changes in the orographic gravity wave drag. The strong sea ice decline simulated by the control run from 1980 to 2015, not matched by the observational record, is halted and is delayed by 15-20 years (across the ensemble members) in our flow-blocking regime simulation. Conversely, in the flow-over regime simulation, sea ice begins declining about 10 years earlier than in the control run. The systematic response of the coupled system suggests the existence of a dynamical relationship between sea ice and OGWD.

The pan-Antarctic signal for sea ice decline derives from the Weddell Sea sector. The pathway through which OGWD influences sea ice is via modifications of the flow regime across the Antarctic Peninsula, and thus the surface wind stress across the Weddell Sea sector, which in turn alters the occurrence of oceanic deep convection. This happens because the flow regime across the Antarctic Peninsula is critical in determining the strength and pattern of the surface winds on both the windward side (Bellingshausen and Amundsen Seas sector) and the lee side (Weddell Sea sector) of the mountain ridge.

How to cite: Guarino, M. V., Ridley, J., Farneti, R., Kucharski, F., and Tompkins, A.: Antarctic sea ice sensitivity to the orographic gravity wave drag in a fully coupled climate model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5813, https://doi.org/10.5194/egusphere-egu24-5813, 2024.

EGU24-7523 | ECS | Posters on site | CR7.7

Amplified Interannual Variation of the Summer Sea Ice in the Weddell Sea, Antarctic After the Late 1990s 

Yuanyuan Guo, Xiaodan Chen, Sihua Huang, and Zhiping Wen

The sea-ice extent (SIE) in the Weddell Sea plays a crucial role in the Antarctic climate system. Many studies have examined its long-term trend, however whether its year-to-year variation has changed remains unclear. We found an amplified year-to-year variance of the Weddell Sea SIE in austral summer since 1998/1999 in observational datasets. Analyses of sea-ice concentration budget and surface fluxes indicate that it is the thermodynamic process that drives the amplification of SIE variations, rather than the sea-ice-drift- related dynamic process. Compared to 1979–1998, the Southern Annular Mode in the preceding spring shows a closer linkage with the Weddell Sea SIE in 1999–2021 through a stronger and more prolonged impact on sea surface temperature, which thermodynamically modulates local sea ice via changing surface heat and radiation fluxes. Our study helps advance the understanding of extreme low Antarctic-SIE records occurring in recent decades and improve future projections of the Antarctic sea-ice variability.

How to cite: Guo, Y., Chen, X., Huang, S., and Wen, Z.: Amplified Interannual Variation of the Summer Sea Ice in the Weddell Sea, Antarctic After the Late 1990s, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7523, https://doi.org/10.5194/egusphere-egu24-7523, 2024.

EGU24-8422 | ECS | Posters on site | CR7.7

The impact of atmospheric forcing on wintertime sea-ice lead patterns in the Southern Ocean 

Umesh Dubey, Sascha Willmes, Alexander Frost, and Gunther Heinemann

Sea-ice leads are narrow, linear fractures in sea ice, and are an important basis for understanding the mechanism of the atmosphere-sea ice-ocean system in the Southern Ocean. We use monthly sea-ice lead frequencies based on satellite thermal imagery with 1 km2 grid resolution to investigate potential causes for the observed spatial and temporal variabilities of sea-ice leads during wintertime (April-September), 2003-2023, using ERA5 winds and sea level pressure, as well as climate indices El Niño–Southern Oscillation (ENSO) and Southern Annular Mode (SAM). The presented investigation provides evidence for correlations between mean monthly lead frequency and monthly wind divergence, as well as monthly sea level pressure across the majority of the circum-Antarctic regions (significantly in the Weddell Sea, Ross Sea and Amundsen & Bellingshausen Sea). Furthermore, our investigation evaluates the influence of wintertime ENSO and SAM on sea-ice lead patterns in the Southern Ocean. Results reveal a positive correlation between sea-ice leads and SAM, in the Weddell Sea and specific regions of the Ross Sea. Moreover, a positive correlation is found between sea-ice leads and ENSO, particularly in the Ross Sea, Western Pacific Ocean, and certain portions of the Indian Ocean. While the driving mechanisms for these observations are not yet understood in detail, the presented results can contribute to opening new hypotheses on atmospheric forcing and sea-ice interactions. The contribution of atmospheric forcing to regional lead dynamics is complex, and a more profound understanding requires detailed investigations in combination with considerations of ocean processes. This study provides a starting point for further research into the detailed relationships between sea-ice leads and atmosphere, ocean, combined effect of ENSO-SAM, respectively in the Southern Ocean.

How to cite: Dubey, U., Willmes, S., Frost, A., and Heinemann, G.: The impact of atmospheric forcing on wintertime sea-ice lead patterns in the Southern Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8422, https://doi.org/10.5194/egusphere-egu24-8422, 2024.

EGU24-8652 | Posters on site | CR7.7

SSP3-7.0 projections of Antarctic sub-ice-shelf melting with the Energy Exascale Earth System Model 

Xylar Asay-Davis, Darin Comeau, Alice Barthel, Carolyn Begeman, Wuyin Lin, Mark Petersen, Stephen Price, Andrew Roberts, Irena Vankova, Milena Veneziani, Jonathan Wolfe, and Shixuan Zhang

To date, few Earth System Models (ESMs) have the ability to simulate the flow in the ocean cavities below Antarctic ice shelves and its influence on basal melting.  Yet capturing both this flow and the resulting melt patterns is critical for representing local, regional, and global feedbacks between the climate and sub-ice-shelf melting.  Here, we present a small ensemble of historical simulations and SSP3-7.0 projections in an ESM that includes Antarctic ice-shelf cavities, the Energy Exascale Earth System Model (E3SM) v2.1.  The simulations have active ocean, sea-ice, atmosphere, land and river components.  The model domain has 12 km horizontal resolution around Antarctica, which is adequate for capturing dynamics in the larger ice-shelf cavities, melt fluxes aggregated across Antarctic regions, and water masses across most of the Antarctic continental shelf. The projections show significant warming and freshening of water masses on the Antarctic continental shelf, a deepening and poleward shift of the Amundsen Sea Low (ASL), and a significant increase in Antarctic melting through the 20th and 21st centuries.  We also see a significantly more modest drift in water-mass properties and melt rates in our control simulation with constant 1950 conditions from which the historical runs were branched.  In addition to providing an estimate of future melting and other changes in regional and global climate under SSP3-7.0, these simulations are also a steppingstone to coupled ice sheet-ocean simulations planned for the near future.  We briefly discuss these plans and the coupling strategy that we are developing.

How to cite: Asay-Davis, X., Comeau, D., Barthel, A., Begeman, C., Lin, W., Petersen, M., Price, S., Roberts, A., Vankova, I., Veneziani, M., Wolfe, J., and Zhang, S.: SSP3-7.0 projections of Antarctic sub-ice-shelf melting with the Energy Exascale Earth System Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8652, https://doi.org/10.5194/egusphere-egu24-8652, 2024.

EGU24-9796 | ECS | Posters on site | CR7.7

Development of Polar Lows in Future Climate Scenarios over the Barents Sea 

Ting Lin, Anna Rutgersson, and Lichuan Wu

Polar lows (PLs) are intense mesoscale cyclones that form over polar oceans during colder months. Characterized by high wind speeds and heavy precipitation, they profoundly impact coastal communities, shipping, and offshore activities. Amid the substantial environmental changes in polar regions due to global warming, PLs are expected to undergo noteworthy transformations. In this study, we investigate the response of PL development in the Barents Sea to climate warming based on two representative PLs. Sensitivity experiments were conducted including the PLs in the present climate and the PLs in a pseudo-global warming scenario projected by the late 21st century for SSP 2-4.5 and SSP 3-7.0 scenarios from CMIP6. In both warming climate scenarios, there is an anticipated decrease in PL intensity, in terms of the maximum surface wind speed and minimum sea level pressure. Despite the foreseen increase in latent heat release in the future climate, contributing to the enhancement of PL intensity, other primary factors such as decreased baroclinic instability, heightened atmospheric static stability, and reduced overall surface heat fluxes play pivotal roles in the overall decrease in PL intensity in the Barents Sea under warming conditions. The augmentation of surface latent heat flux, however, results in increased precipitation associated with PLs by enhancing the latent heat release. Furthermore, the regional steering flow shifts in the warming climate can influence the trajectory of PLs during their development.

How to cite: Lin, T., Rutgersson, A., and Wu, L.: Development of Polar Lows in Future Climate Scenarios over the Barents Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9796, https://doi.org/10.5194/egusphere-egu24-9796, 2024.

EGU24-10555 | ECS | Posters on site | CR7.7

Towards an improved Antarctic sea-ice representation in HadGEM3-GC5 

Tarkan Bilge, Kaitlin Naughten, Paul Holland, Edward Blockley, David Storkey, and Jeff Ridley

The historical runs of CMIP6-era coupled climate models generally exhibit negative biases in Antarctic sea ice, as identified across a range of models during the CMIP6 simulations (Roach et al. 2020). The UK's national coupled climate model, HadGEM3, has been no exception to this. The CMIP6 version, HadGEM3-GC3, underestimated Antarctic sea ice in historical simulations owing to a Southern Ocean warm bias (Andrews et al. 2020). As part of the DEFIANT (Drivers and Effects of Fluctuations in sea Ice in the ANTarctic) project, in this research we perform an analysis of the representation of sea ice in HadGEM3-GC5, a more recent version of the coupled model. Analysis of existing HadGEM3-GC5 simulations has identified unrealistic convection events associated with open water polynyas. We have started to perform a suite of sensitivity experiments to investigate the importance of the freshwater budget and ocean mixing parameterisation scheme on these convection events, and subsequently on pan-Antarctic sea ice. These initial experiments take the form of short simulations with constant year-2000 forcings, incorporating various parameter perturbations and modifications to freshwater input. We present evidence of the improved characterisation of pan-Antarctic sea ice in HadGEM3-GC5 compared to HadGEM3-GC3, and the preliminary analysis of perturbation simulations aimed at understanding and addressing the remaining challenges in the model coupled climate system.

How to cite: Bilge, T., Naughten, K., Holland, P., Blockley, E., Storkey, D., and Ridley, J.: Towards an improved Antarctic sea-ice representation in HadGEM3-GC5, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10555, https://doi.org/10.5194/egusphere-egu24-10555, 2024.

EGU24-11497 | Orals | CR7.7

How well do the regional atmospheric, oceanic and coupled models describe the Antarctic sea ice albedo? 

Kristiina Verro, Cecilia Äijälä, Roberta Pirazzini, Damien Maure, Willem Jan van de Berg, Petteri Uotila, and Xavier Fettweis

A realistic representation of the Antarctic sea ice surface albedo, especially during the melting period, is essential to obtain reliable atmospheric and oceanic model predictions. Antarctic sea ice cover influences the atmosphere by reflecting solar radiation and acting as a barrier between the atmosphere and the ocean, for example. The Antarctic sea ice consists of ice floes of varying thickness, usually covered by snow, and broken up by cracks, leads and polynyas. Therefore, the optical properties of sea ice can vary greatly.

We use regional atmospheric (HCLIM-AROME), oceanic (MetROMS-UHel) and coupled (MAR-NEMO) models to compare the representation of the basic sea ice characteristics: sea ice albedo, snow and ice thickness, and meteorological data during the melt periods of two Antarctic domains with very different sea ice conditions, using data of the ISPOL and Marsden field campaigns. During the ISPOL campaign (Dec 2004; Hellmer et al. 2008) RV Polarstern was moored to an ice floe in the Weddell Sea, where snow-covered multi-year ice persists. The Marsden field campaign (Nov. 2022; Dadic et al. 2023) was established over 2.4m thick land-fast ice of McMurdo Sound, where snow thickness ranged from 0 to 40 cm in patches over the roughest ice. We aim to bridge the models to observations, by comparing model output to various levels of observations, from in-situ measurements of the ISPOL and Marsden campaigns to smaller/larger scale satellite observations over Weddell and Ross Seas. 

The first comparisons revealed that HCLIM, with a simplistic 1D thermodynamic sea ice scheme (SICE, Bartrak et al. 2018), was underestimating snow albedo up to 30%, and needed retuning for Antarctic conditions. Overall, preliminary results indicate that the models do well reproducing the snow-covered sea ice during the ISPOL campaign, when the weather was warm, with the air temperature mostly above −5◦C. MetROMS-UHel, which uses the Delta-Eddington multiple scattering radiative transfer model to calculate the sea ice albedo, even reproduced similar diurnal variability than observed. The Marsden field campaign took place in an area of complex topography, cold weather conditions, and greatly varying sea ice. The models tend to overestimate the albedo of the land-fast ice of the Marsden field campaign, as a uniform, instead of patchy, snow layer is modelled. Models also cannot reproduce the variety of sea ice, such as freshly formed ice, in the McMurdo Sound area apparent on the satellite images.

How to cite: Verro, K., Äijälä, C., Pirazzini, R., Maure, D., van de Berg, W. J., Uotila, P., and Fettweis, X.: How well do the regional atmospheric, oceanic and coupled models describe the Antarctic sea ice albedo?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11497, https://doi.org/10.5194/egusphere-egu24-11497, 2024.

EGU24-12637 | ECS | Orals | CR7.7

Does Strength Matter? An Exploration into Cyclone Strength and the Impact on Arctic Sea Ice 

Elina Valkonen, Chelsea Parker, and Linette Boisvert

Arctic cyclones are an integral part of the polar climate system. They import moisture and energy from the midlatitude and impact the underlying surface through dynamic adn thermodynamic interactions. The rapid warming and sea ice decline in the Arctic makes it more important than ever to understand the tightly coupled interactions between the Arctic sea ice and episodic weather events, such as cyclones.

In this presentation, we use a Lagrangian ice parcel database to study the impact different strength cyclones have on the Arctic Sea ice. The database includes daily 25km Arctic ice parcel tracks and associated atmospheric and sea ice conditions, including passing cyclone track data from 2002-2021. We divide these cyclone tracks into three distinctive groups based on their central pressure and average wind speed. After this, we split the ice parcel tracks and associated atmospheric data based on these cyclone groups: ice affected by weak cyclones, ice affected by normal cyclones, and ice affected by extreme cyclones.

We will then utilize these parcel groups to study the atmospheric conditions (precipitation, temperature, radiative balance) and sea ice changes for three days before, during, and three days after the cyclone passes. We will average the ice parcel and associated atmospheric variable data over the ice parcel life cycle and across the before, during, and after cyclone pass timescales. We will then apply statistical pattern recognition on these averaged sea ice and atmospheric variable fields. This analysis will allow us to better understand the role cyclone strength has in cyclone-sea ice interactions. We will present these results separately for individual seasons, locations, and surrounding SIC.

How to cite: Valkonen, E., Parker, C., and Boisvert, L.: Does Strength Matter? An Exploration into Cyclone Strength and the Impact on Arctic Sea Ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12637, https://doi.org/10.5194/egusphere-egu24-12637, 2024.

EGU24-12913 | Orals | CR7.7

Do clouds care about aerosol from sea ice sources (blowing snow, open leads) during Arctic winter/ spring? – a case study from MOSAiC 2019-20 

Markus Frey, Floor van den Heuvel, Amélie Kirchgäßner, Simran Chopra, Thomas Lachlan-Cope, Ronny Engelmann, Albert Ansmann, Heike Wex, Ananth Ranjihkumar, Xin Yang, Jessica Mirrielees, Kerri Pratt, Ivo Beck, Julia Schmale, and Xianda Gong

Aerosols play a key role in Arctic warming via radiative direct and indirect effects. It is well-known that increased aerosol concentration due to Arctic haze raises cloud longwave emissivity, resulting in surface warming. Recently, a MOSAiC study demonstrated that blowing snow above sea ice generates fine sea salt aerosol, which results in up to tenfold enhancement of cloud condensation nuclei leading to potentially significant surface warming rivalling that due to Arctic haze. Yet, radiative properties of aerosol emitted by sea ice sources, vertical coupling and interaction with clouds remain major uncertainties in quantifying the aerosol impact on Arctic climate change.

We use MOSAiC observations to analyse the coupled ocean-ice/snow-atmosphere system and assess contributions of sea ice sources (blowing snow, open leads) to atmospheric cloud-forming particles in particular ice-nucleating particles (INP). Choosing the 2020 winter/spring transition with profound seasonal changes in sea ice and air mass origin, we discuss the importance of sea ice aerosol to low-level clouds in comparison to advected aerosol. We consider measurements of snow particles, physico-chemical properties and INP content of aerosol and snow on sea ice, vertical profiles linking ground observations to the level of cloud formation, and assess climate sensitivity using the UKESM model.

How to cite: Frey, M., van den Heuvel, F., Kirchgäßner, A., Chopra, S., Lachlan-Cope, T., Engelmann, R., Ansmann, A., Wex, H., Ranjihkumar, A., Yang, X., Mirrielees, J., Pratt, K., Beck, I., Schmale, J., and Gong, X.: Do clouds care about aerosol from sea ice sources (blowing snow, open leads) during Arctic winter/ spring? – a case study from MOSAiC 2019-20, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12913, https://doi.org/10.5194/egusphere-egu24-12913, 2024.

EGU24-14392 | ECS | Orals | CR7.7

Impact of Weakened Antarctic Circumpolar Current on the Northern Hemisphere Climate 

Peixi Wang, Yuhui Han, Song Yang, Jun Ying, Zhenning Li, Xichen Li, and Xiaoming Hu

Recent findings show a remarkable linkage between the Northern Hemisphere and Southern Hemisphere climates. Previous studies have focused on the impact of the climate change in the northern high-latitudes on that in the Southern Hemisphere, but few studies concerned the impact of Southern Ocean circulation on the Northern Hemisphere, especially the Arctic climate. In this study, we close the Drake Passage (DP) to slow down the Antarctic Circumpolar Circulation (ACC) in the fully coupled Community Earth System Model, to investigate the impact of weakened ACC on the Northern Hemisphere.

Two model experiments, DP opened and DP closed experiments, are performed. Relative to the DP opened case, a warmer Antarctic with less sea ice cover but a colder Arctic with more sea ice cover appear in the DP closed case resulting from weaker ACC and Atlantic Meridional Overturning Circulation (AMOC). Especially, the changes in surface air temperature in the two poles are largest in winter.

Compared to the DP opened case, the anomalous southward heat transport by weakened ACC is largest in winter, contributing to the winter amplification in the Antarctic. However, the seasonal difference in AMOC change is insignificant. To understand the winter amplification in the Arctic, we further analyze local surface heat flux changes in the Arctic. The anomalous downward longwave radiation and sensible and latent heat fluxes are stored in the ocean in summer and released to the atmosphere in the following winter. Although the ocean heat content warms the surface, the upward sensible and latent heat fluxes cool the surface more significantly in winter. This local atmosphere-ocean-ice interaction contributes to the winter amplification in the Arctic. 

When DP is closed, the westerlies become stronger and move poleward in the Northern Hemisphere because of the increased meridional temperature gradients, especially in winter. The change in surface temperature also contribute to the weakening of Aleutian Low in winter. The warming in the Antarctic and the cooling in the Arctic leads to the notable weakening of Hadley circulation in the Southern Hemisphere. Additionally, compared to the DP opened case, the Intertropical Convergence Zone shifts southward and the Walker circulation and trade winds over the Pacific strengthen. These results shed light on understanding the interhemispheric interaction and the pole-to-pole connection.

How to cite: Wang, P., Han, Y., Yang, S., Ying, J., Li, Z., Li, X., and Hu, X.: Impact of Weakened Antarctic Circumpolar Current on the Northern Hemisphere Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14392, https://doi.org/10.5194/egusphere-egu24-14392, 2024.

During space reentry, satellites undergo ablation in the Mesosphere, leading to the dispersion of ablated material across the globe. The Mesospheric circulation efficiently concentrates this material into the polar winter stratosphere, from where its fate is not well known. Historically, the mass of satellite debris has been significantly smaller than that of naturally occurring meteoroids. The meteoric material also undergoes ablation and deposit similar material, which is transported to the poles and can be observed in Greenland ice cores. With the current exponential increase in the number of launched satellites, the mass of the satellite debris will go from negligible to surpassing the mass of natural meteoric material within the next few years. Here, the quantity and composition of material to be expected in the polar stratosphere the coming years are presented. The question is raised: What potential impacts will the drastic increase of satellite debris have on the polar atmosphere/cryosphere?

How to cite: Megner, L.: Should we worry about the massive increase of satellite reentry debris in the polar regions?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14537, https://doi.org/10.5194/egusphere-egu24-14537, 2024.

Cyclones are an important driver of heat and moisture transport into the Arctic and additionally cause high wind speeds and abrupt wind direction changes during their passage. The subsequent impacts on the Arctic sea ice cover consist of i) a thermodynamic stalling/enhancement of the seasonal sea-ice growth/melt, and ii) enhanced drift and deformation of sea ice. The statistical quantification of these cyclone impacts on the Arctic sea-ice cover is a very recent research topic.

By conducting a climatological monthly analysis based on the ERA5 reanalysis and a cyclone tracking algorithm, we reveal a distinct seasonal cycle of cyclone impacts on sea-ice concentration in the Atlantic Arctic Ocean (strong impacts from autumn to spring, but weak impacts in summer). We further demonstrate that the cyclone impacts have changed significantly throughout the last four decades in a warming Arctic, magnitude-wise strongest in the Barents Sea in autumn.

Still, open questions remain with respect to the impacts of cyclones on the Arctic sea ice in the present climate and regarding their possible changes in a warming Arctic. Specifically, the influence of cyclone passages on the formation of leads in the sea-ice cover has not been statistically analyzed so far. Thus, we extend our analysis to cyclone related changes in sea-ice lead fraction derived from horizontally high-resolved (down to 1km²) MODIS sea-ice observations.

Our results indicate that cyclone passages significantly increase sea-ice lead fraction in large parts of the central Arctic Ocean. Mixed results are found for the Arctic marginal seas. The analysis of particular cyclone cases further suggests that groups of consecutive cyclones traversing the sea ice within short time are particularly effective in driving changes in sea-ice concentration and lead fraction. The statistical quantification of the importance of such a temporal clustering of cyclones for their sea-ice impacts is topic of ongoing research.

How to cite: Aue, L. and Rinke, A.: Advancing the understanding of cyclone impacts on Arctic sea-ice concentration and sea-ice lead formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15589, https://doi.org/10.5194/egusphere-egu24-15589, 2024.

EGU24-15744 | ECS | Orals | CR7.7

Topographically constrained tipping point for complete Greenland Ice Sheet melt 

Michele Petrini, Meike D. W. Scherrenberg, Laura Muntjewerf, Miren Vizcaino, Raymond Sellevold, Gunter Leguy, William H. Lipscomb, and Heiko Goelzer

A major impact of anthropogenic climate change is the potential triggering of tipping points, such as the complete loss of the Greenland Ice Sheet (GrIS). Currently, the GrIS is losing mass at an accelerated pace, mainly due to a steep decrease in its Surface Mass Balance (SMB, snow accumulation minus surface ablation from melt and associated runoff). Here, we investigate a potential SMB threshold for complete GrIS melt, the processes that control this threshold, and whether it exhibits characteristics commonly associated with tipping points, such as a non-linear response to external forcings. To do this, we adopt a semi-coupled approach, forcing the Community Ice Sheet Model v.2 (CISM2) with different SMB levels previously calculated at multiple elevation classes with the Community Earth System Model v.2 (CESM2). The SMB calculation in CESM2 and the elevation class method allow us to account for the SMB-elevation feedback based on snow/firn processes and energy fluxes at the ice sheet surface. We find a positive SMB threshold for complete GrIS melt of 230±84 Gt/yr, corresponding to a 60% decrease from the GrIS simulated pre-industrial SMB. The ice sheet shows a highly non-linear response to sustained melt, and its final state is determined by the effect of the SMB-height feedback in response to surface melt and Glacial Isostatic Adjustment (GIA). The GrIS is tipping from nearly 50% equilibrium volume towards complete melt when the ice margin in the central west unpins from a coastal region with high bedrock elevation and SMB. We find that this relatively small coastal region is important to determine the ice sheet stability in response to sustained warming. Based on the ice sheet geometry in previous modelling studies of the GrIS during the last interglacial, we suggest that a stabilizing effect of the bedrock topography in the central West might have occurred in the past.

How to cite: Petrini, M., Scherrenberg, M. D. W., Muntjewerf, L., Vizcaino, M., Sellevold, R., Leguy, G., Lipscomb, W. H., and Goelzer, H.: Topographically constrained tipping point for complete Greenland Ice Sheet melt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15744, https://doi.org/10.5194/egusphere-egu24-15744, 2024.

EGU24-15858 | ECS | Orals | CR7.7

Contrasting trends of marine bromoform emissions in a future climate 

Dennis Booge, Jerry Tjiputra, Dirk Olivié, Birgit Quack, and Kirstin Krüger

Bromoform (CHBr3) from the ocean is the most important organic compound for atmospheric bromine with an atmospheric lifetime of ~2-4 weeks. Natural production, being the main source of oceanic CHBr3, is high at the coasts and in open ocean upwelling regions due to production by macroalgae and phytoplankton. Although highly relevant for the future halogen burden and ozone layer in the stratosphere, the global bromoform production in the ocean and its emissions are still poorly constrained in observations and are mostly neglected in Earth System Model (ESM) climate projections. Anthropogenically forced climate change may lead to considerable changes in ocean temperature and ocean acidification, and will also influence primary productivity. Especially biogeochemical processes in the Arctic will be strongly influenced by climate change in the near future.  However, the future trend of the marine emissions of bromoform and other very short-lived substances (VSLS) remains unclear. Two studies projected an increase of the relative importance of brominated VSLS for stratospheric ozone loss in contrast to other ozone depleting substances, due to increasing oceanic emissions of the brominated VSLS. Both studies applied constant (observation based) oceanic concentrations for the emission calculations in a future warming ocean, which assumes a production increase. Thus, a consistent way of addressing the bromoform production and concentration in the global ocean, its air-sea gas exchange and concentration in the atmosphere with high spatial and temporal resolution is ultimately needed to further progress with our understanding of potential future climate trends.

Here, we show first model results of fully coupled ocean-atmosphere bromoform interactions in the Norwegian ESM (NorESM) with the ocean model BLOM and the ocean biogeochemistry component iHAMOCC for the period from 2015 to 2100 (SSP585 scenario). Model data for the historical period until 2014 is validated with oceanic and atmospheric observations listed in the HalOcAt (Halocarbons in the Ocean and Atmosphere) data base.

On global average, our model results indicate decreasing oceanic CHBr3 concentrations and emissions until the end of this century. In contrast, atmospheric CHBr3 mixing ratios are projected to increase during the same period. The results indicate that the lifetime of atmospheric CHBr3 increases until 2100 compared to current days as atmospheric loss due to photolysis and reaction with hydroxyl radicals is projected to decrease.

In contrast, bromoform in the Arctic shows an increasing trend of marine CHBr3 concentrations, their emissions and atmospheric mixing ratios. Moreover, annual mean Arctic marine bromoform concentrations in 2100 (5.2 pmol L-1) are projected to exceed global values (4.5 pmol L-1). Increasing sea surface temperature and sea ice retreat in the Arctic drives the higher CHBr3 productivity. The resulting emissions in the Arctic are projected to increase by 67% until 2100 indicating this region to be a significant source of brominated VSLS in a future climate. The relevance and uncertainties of the model results are discussed.

How to cite: Booge, D., Tjiputra, J., Olivié, D., Quack, B., and Krüger, K.: Contrasting trends of marine bromoform emissions in a future climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15858, https://doi.org/10.5194/egusphere-egu24-15858, 2024.

EGU24-16385 | ECS | Posters on site | CR7.7

Simulating Arctic aerosol-cloud interactions in a warm air intrusion event during the MOSAiC campaign 

Ruth Price, Paul R. Field, Bjørg Jenny Kokkvoll Engdahl, Oskar Landgren, Annette Rinke, and Andrew Orr

Aerosols play a crucial role in determining the characteristics and radiative impacts of Arctic clouds. Parameterisations of aerosols and clouds in climate models remain uncertain, confounding efforts to improve our understanding of their behaviour both now and in the future. Moreover, model biases in cloud microphysics are compounded by interlinked biases in Arctic boundary layer structure, surface properties and large-scale meteorology. This interdependence among variables poses significant hurdles for modelers attempting to accurately simulate Arctic atmospheric processes.

In this study, we have used a regional atmospheric model, the UK Met Office Unified Model, coupled to a cloud microphysical model (Cloud Aerosol Interacting Microphysics, CASIM) and an aerosol-chemistry-climate model (UK Chemistry and Aerosols, UKCA). This integrated approach has been employed to investigate warm air intrusion events during April 2020 of the MOSAiC campaign. Our results provide vital information on the behaviour of model processes that have been tuned for mid-latitude regimes, such as cloud droplet activation, in the Arctic environment during warm air intrusion events that had clear impacts on the surface energy budget. 

How to cite: Price, R., Field, P. R., Engdahl, B. J. K., Landgren, O., Rinke, A., and Orr, A.: Simulating Arctic aerosol-cloud interactions in a warm air intrusion event during the MOSAiC campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16385, https://doi.org/10.5194/egusphere-egu24-16385, 2024.

EGU24-16632 | Posters on site | CR7.7

Bounding the contribution of open leads to sea spray aerosol emissions in the high Arctic 

Rémy Lapere, Jennie L. Thomas, Louis Marelle, and Pierre Rampal

In the Arctic ocean, open leads have the ability to release sea spray into the atmosphere. However, the magnitude and seasonality of this flux are relatively unknown, which is a limitation to our understanding of the polar climate. Most atmospheric models do not include sea spray from leads, because of the lack of existing parameterization. In this work we propose a parameterization for sea spray fluxes from open leads in the Arctic, which leverages aerosol flux measurements from a past campaign combined with the latest generation of sea ice modeling.

Based on our parameterization, the annual total emitted mass of sea salt from open leads, [0.1–1.5] Tg/yr, is comparable to emissions from blowing snow and to the transported mass of sea salt from open ocean coming from the lower latitudes. Furthermore, the seasonality of open lead and blowing snow sea salt emissions have opposite phases, and their spatial distribution across the Arctic is also different. Therefore, we find that including both open lead and blowing snow sea salt fluxes can improve the reproduction of the annual cycle of sea salt aerosol atmospheric concentration at high latitude stations.

Using sea ice concentration fields from the neXtSimv2 sea ice model and implementing our parameterization in the WRF-Chem chemistry-transport model, we evaluate the impacts of open lead emissions on sea salt concentrations and clouds in the high Arctic.

How to cite: Lapere, R., Thomas, J. L., Marelle, L., and Rampal, P.: Bounding the contribution of open leads to sea spray aerosol emissions in the high Arctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16632, https://doi.org/10.5194/egusphere-egu24-16632, 2024.

EGU24-16827 | Orals | CR7.7

Ocean-driven basal channel growth at Fimbulisen 

Qin Zhou, Tore Hattermann, Chen Zhao, Rupert Gladstone, Ashely Morris, and Petteri Uotila

Small-scale basal features, such as channels and crevasses, are abundant on many ice shelves.  These features may, either directly or via modulating basal melting, impact ice shelf stability and, therefore, also global sea level. However, simulating the effect of these features on ice shelves at a hundred-meter scale or smaller is still challenging even for dedicated regional simulations, which typically ignore the small-scale features and smooth the ice draft. Fine-resolution (8 m) basal topography retrieved from the Reference Elevation Model of Antarctica (REMA) data reveals that channelized basal features of several tens of kilometers traverse the ice base both along and across the Jutulstraum ice stream on the Fimbulisen Ice Shelf (FIS). The FIS cavity is currently filled with fresh and cold Eastern Shelf Water (ESW), and recent observations have shown a sustained inflow of Warm Deep Water (WDW) since 2016. In this study, we first assess the effect of the basal channels on the cavity circulation and basal melting of the FIS with a fine-scale unstructured grid Finite-Volume Community Ocean Model (FVCOM) model of the FIS ice cavity. The grid resolution varies from 50 m in the focused region along the ice stream to 1500 m in the open ocean. Sensitivity studies are carried out using the high-resolution ice draft from REMA and a smoothed version of it, combined with varying proportions of WDW in the cavity. Our results show that the basal channels lead to (i) a redistribution of basal melting, (ii) a net melt increase at the deep ice area, and (iii) the entrapment of melt-modified WDW in the channels where WDW reaches the deep ice area. Using an idealized ice sheet model, we demonstrate that this entrapment of warm water in the channel results in a net melt increase with a preferential melt that promotes channel growth and migration, forming a positive feedback loop. We further investigate the positive feedback mechanism using an Elmer/Ice–FVCOM model setup with the same fine-scale mesh as the ocean model. This ocean-driven coupled evolution of the channelized system may occur on other shelves in East Antarctica where ESW and WDW coexist. Considering this coupled process in generating sea level projections could constrain East Antarctica's contribution to future sea level rise.

 

How to cite: Zhou, Q., Hattermann, T., Zhao, C., Gladstone, R., Morris, A., and Uotila, P.: Ocean-driven basal channel growth at Fimbulisen, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16827, https://doi.org/10.5194/egusphere-egu24-16827, 2024.

EGU24-17682 | ECS | Posters on site | CR7.7

Changes of clouds and sea ice in EC-Earth- and ERA5-driven retrospective ensemble hindcasts with the fully coupled ice-sheet–ocean–sea ice–atmosphere–land circum-Antarctic model PARASO 

Florian Sauerland, Pierre-Vincent Huot, Sylvain Marchi, Hugues Goosse, and Nicole van Lipzig

We created 4 retrospective hindcasts using PARASO, a five-component (ice sheet, ocean, sea ice, atmosphere, and land) fully coupled regional climate model over an Antarctic circumpolar domain: a control run forced with reanalysis data from ERA5 and ORAS5, and an ensemble of 3 members forced by 3 different EC-Earth global hindcasts. We compare the ocean and sea ice properties of the ERA5-driven simulation to the ensemble mean of the EC-Earth-driven ones, to separate the impact of the different source of boundary conditions from internal variability generated by the different ensemble members. Moreover, we analyse if and how the different ocean temperatures and sea ice extents influence the formation of clouds. We compare the moisture and heat fluxes at the ocean surface between the EC-Earth-driven ensemble and the ERA5-driven hindcast, as well as the moisture and cloud water contents in the atmosphere. This not only provides information on the contribution of external and internal variability inside the PARASO domain for those variables, but by comparing the variability in fluxes to the variability of clouds, we can also estimate the importance of ocean-cloud-interactions. Our results also show that the increasing trend observed in Antarctic sea ice extent observed prior to 2015 is well represented in the ERA5-driven run, but not in the EC-Earth-driven ensemble, indicating a stronger influence of mid-latitude forcings compared to local processes. 

How to cite: Sauerland, F., Huot, P.-V., Marchi, S., Goosse, H., and van Lipzig, N.: Changes of clouds and sea ice in EC-Earth- and ERA5-driven retrospective ensemble hindcasts with the fully coupled ice-sheet–ocean–sea ice–atmosphere–land circum-Antarctic model PARASO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17682, https://doi.org/10.5194/egusphere-egu24-17682, 2024.

EGU24-17841 | ECS | Orals | CR7.7

Response of EC-Earth3 to Antarctic meltwater 

André Jüling, Erwin Lambert, Philippe Le Sager, and Sybren Drijfhout

Ice-sheet meltwater affects ocean stratification and circulation, sea ice, and ultimately the global climate through various feedback mechanisms. Most current generation global climate models do not include interactive ice sheets and as such do not capture the projected increases in additional meltwater under future emission scenarios. We use the EC-Earth3 coupled climate model to investigate the climate response to various scenarios of Antarctic meltwater input. With the idealized experiments of the Southern Ocean Freshwater Input from Antarctica Model Intercomparison Project (SOFIAMIP), as well as a plausible future meltwater release experiment, we investigate the sensitivity to both amount and location of the freshwater forcing in both the eddy-permitting (0.25°) and the standard, non-eddying (1°) resolution model versions. We find that the amount of freshwater strongly controls the sea ice with associated atmospheric adjustments and feedbacks. We also see that while inserting additional meltwater at the surface enhances stratification increasing sea ice cover, inserting it at depth decreases stratification and enables more ocean heat to be released at the surface. Our results represent improved model physics and support calls for using prescribed Antarctic meltwater input as forcing in the Coupled Model Intercomparison Project to, for example, improve modelled sea ice evolution and sea level trends.

How to cite: Jüling, A., Lambert, E., Le Sager, P., and Drijfhout, S.: Response of EC-Earth3 to Antarctic meltwater, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17841, https://doi.org/10.5194/egusphere-egu24-17841, 2024.

The Filchner-Ronne Ice Shelf currently has a “cold” cavity with comparably low melt rates or refreezing at the ice-ocean interface. However, it has been shown that a switch to “warm” conditions under a very strong climate warming scenario is possible within this century (Hellmer et al., 2012). In this case, modified Circumpolar Deep Water that resides at intermediate levels offshore enters the cavity and fuels a 21-fold increase in aggregated melt rates (Naughten et al., 2021), with implications for ice-shelf buttressing and thereby the dynamics of tributary ice streams and glaciers. Interactions of resulting cavity changes with the ocean could furthermore amplify or weaken the increase in ice shelf melting. Here we investigate the influence of ice-ocean feedbacks on sub-shelf melt rates and the regime shift from a “cold” to a “warm” ice-shelf cavity using standalone and coupled configurations of the ice sheet model Úa and the ocean model MITgcm (De Rydt and Gudmundsson, 2016; Naughten et al., 2021). Furthermore, we test their influence on reversibility back to “cold” conditions, and the impact of a regime shift on grounded ice dynamics.

How to cite: Reese, R. and De Rydt, J.: Do ice-ocean feedbacks influence a regime shift of the Filchner-Ronne ice shelf cavity?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18887, https://doi.org/10.5194/egusphere-egu24-18887, 2024.

EGU24-1649 | ECS | PICO | GM7.3

Dunes on the north-eastern Tibetan Plateau as influenced by climate change: a remote sensing study of the past 5 decades  

Lukas Dörwald, Frank Lehmkuhl, Janek Walk, Xiaoping Yang, Deguo Zhang, Andreas Baas, Lucie Delobel, Bruno Boemke, and Georg Stauch

Dunes react quickly to climatic changes, with the main drivers being the dominating wind regime (e.g. magnitude and direction), precipitation, and temperature. Further, human impact can alter dune movement by fixation of active dunes through greening projects, or reactivation of stationary ones through overgrazing by animals. The north-eastern Tibetan Plateau shows a high variability of climatic parameters like wind, temperature, and precipitation within a high elevation environment, situated between the mid-latitude westerlies and the East Asian Summer monsoon. The presented studies asses active barchan dunes in different climatic settings, from the arid southern margins of the Badain Jaran Desert, to the humid Zoige Basin.

Since climate stations on the Tibetan Plateau are rare and their measurements often cover only a short time span, climatic changes were studied from ERA-5 reanalysis data, dating back to the 1950s. These metrics were processed via cloud computing, using Google Earth Engine, and were then compared to dune migration rates, which were deduced from optical satellite imagery. Here, the CORONA KH-4B images from the late 1960s, the Landsat archives, and up-to-date high resolution data (GeoEye and WorldView) were used. The Normalized Difference Vegetation Index (NDVI) was implemented to observe changes in vegetation. As a newly tested metric, dune field density changes were calculated, in order to investigate dynamics of dense dune field setting.

Over 500 dunes were mapped and analyzed in total within four focus-areas for comparative purposes. The results highlight a wide range of different behavioral patterns of dunes within the environment of the north-eastern Tibetan Plateau. This showcases how dunes can be influenced by and linked to climatic changes.

How to cite: Dörwald, L., Lehmkuhl, F., Walk, J., Yang, X., Zhang, D., Baas, A., Delobel, L., Boemke, B., and Stauch, G.: Dunes on the north-eastern Tibetan Plateau as influenced by climate change: a remote sensing study of the past 5 decades , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1649, https://doi.org/10.5194/egusphere-egu24-1649, 2024.

EGU24-1752 | PICO | GM7.3

A conceptual model for alluvial fan formation and development  

Frank Lehmkuhl and Lewis A. Owen

The development of alluvial fans is sensitive to environmental change and, thus, alluvial fans provide essential archives for reconstructing Quaternary paleoenvironmental conditions, particular climate, hydrology, and tectonics. Although alluvial fans have been studied across the globe for over a century, there is no unifying scheme/framework or model to consider their complete variety and mode of formation. By reviewing the global spatial and temporal range of alluvial fan types and data from selected key dryland regions, we are able to develop a conceptual scheme/framework for their geomorphology and formation, and thus aid in their application for Quaternary climate and environmental change studies. This approach suggests that there are three main regimes for alluvial fan geomorphology and formation: Type I) microscale mountain alluvial fans, small in size and extent (radius < a few 100 m); Type II) mesoscale (radius

How to cite: Lehmkuhl, F. and Owen, L. A.: A conceptual model for alluvial fan formation and development , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1752, https://doi.org/10.5194/egusphere-egu24-1752, 2024.

EGU24-2355 | PICO | GM7.3

Monitoring and simulating dryland soil salinization and assessing the impact of climate change and global warming on soil salinity processes over the past three decades in the Bajestan playa (NE Iran) 

Azra Khosravichenar, Mehdi Aalijahan, Saeedreza Moazeni-Noghondar, Anthony R. Lupo, Alireza Karimi, Mathias Ulrich, Naser Parvian, Aboozar Sadeghi, and Hans von Suchodoletz

Dryland soil salinization strongly affects soil properties, with severe consequences for regional ecology, agriculture and the aeolian dust dynamics. Given its climate-sensitivity it forms a serious environmental hazard, and to cope with this challenge during current global warming it needs to be better understood.

The Bajestan Playa, located in the heavily salinization-affected drylands of Iran, is home to several protected areas and serves as a crucial source of regional dust emissions. Consequently, soil salinization in this region affects both local ecosystems and societies but was not systematically studied yet.

Using an unprecedented comprehensive approach, we systematically monitored regional soil salinity from 1992 to 2021 through a combination of remote sensing, on-site field measurements, and laboratory analyses. We linked these data with regional and global climatic information to achieve three main objectives: (i) understanding the spatio-temporal dynamics of soil salinity, (ii) assessing the impact of regional and global climate changes on salinization processes, and (iii) exploring the potential applications of our approach for future soil salinity studies.

Our high-resolution annual data over three decades have provided significantly deeper insights into soil salinization dynamics. Furthermore, this pioneering, multidisciplinary research showcases substantial potential for future applications in other salinity-affected drylands forming a foundational knowledge base to address the consequences of ongoing global climate change.

How to cite: Khosravichenar, A., Aalijahan, M., Moazeni-Noghondar, S., R. Lupo, A., Karimi, A., Ulrich, M., Parvian, N., Sadeghi, A., and von Suchodoletz, H.: Monitoring and simulating dryland soil salinization and assessing the impact of climate change and global warming on soil salinity processes over the past three decades in the Bajestan playa (NE Iran), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2355, https://doi.org/10.5194/egusphere-egu24-2355, 2024.

The lower fourth member of the Paleogene Shahejie Formation (Es4L) in Bonan sag, Bohai Bay Basin, East China was taken as an important target for oil and gas exploration in Shengli oilfield. Bonan sag is one of several sag in the Bohai Bay Basin, located in north-east China. Paleogene deposits are characterized by red rock layers, formed under a hot-warm and arid climate. Four depositional systems were developed in the Bonan sag. Among them, the fan delta developed in the central part of the study area, consisting of gray-white fine glutenite with poor sorting and rounding. The braided river delta is developed in the southern part with large lithofacies. The lithology shows some light gray conglomerate, pebbly sandstone, sandstone and small amount of mudstone. Floodplain facies is mainly developed in the inundated plain that in some weather conditions have the characteristics of shallow lake facies. However, a number of questions remain unanswered about the disparate presence of evaporites, the diverse colors of the mudstones and the varying levels of total organic carbon (TOC) in the area. These disparities can be seen in the many oscillations in TOC content, from the source of the sediments in the upper relief to the flood lacustrine plain. Consequently, given to this conditions, the depositional system which occurs in the area remains unclear from previous works. However, looking at the distribution of the sediments in an apparently short distance of less than 50km from the south to the North of sag, suggests that they are more likely to be terminal fan deposits. Terminal fans are an architectural system for draining and depositional process from high relief to flood plain, with gradual discharge of water through infiltration and evaporation. Although some researchers have conducted studies on terminal fans around the world, the concept remains unfamiliar and deserves to be more elucidated. This approach postulates to be useful to better understanding the sedimentary deposits in the Bonan sag and must be reviewed for similar hydrocarbon explorations elsewhere.

How to cite: Mioumnde, A. P., Zhang, L., and Yan, Y.: Paleoenvironment and Depositional Analysis of a Paleogene Formation: Terminal Fan Sedimentation Approach for Reservoir Quality Study in the Lower Shahejie Fourth Member, Bonan sag, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2604, https://doi.org/10.5194/egusphere-egu24-2604, 2024.

 In view of the problem that the Cretaceous favorable sedimentary facies belt in Kedong structural belt in the southwest depression of the Tarim Basin is not clear, in order to reduce the uncertainty of the research on the spatial and temporal distribution of source sink sedimentary systems in low drilling density areas, the applicability of sedimentary forward modeling in the Tarim Basin is explored. Based on existing geochemical data, statistical analysis of trace elements and rare earth elements is conducted to explore the ancient sedimentary environment during the sedimentation process of the Cretaceous Kizilsu Group, which is a prerequisite for conducting sedimentary forward modeling. By comprehensively utilizing drilling, seismic and other data, combined with previous research results, DionisosFlow sedimentary forward simulation software is applied to clarify the development characteristics of sedimentary systems. The results show that based on different element abundances, ratios, and sedimentary markers, the study of ancient sedimentary environments shows that the ancient climate is mainly characterized by semi humid, semi dry, and dry hot climate conditions; During the sedimentation period of the Kizilsu Group, the overall water depth was relatively shallow, and the ancient redox environment was a shallow underwater oxidation environment. The favorable paleoenvironmental conditions and abundant material sources provide favorable conditions for the development of shallow water delta sedimentary systems. The Kizilsu Group mainly develops braided river delta sediments in the northern gentle slope zone, with front edge sediments as the main type. The southern steep slope zone develops alluvial fans and fan delta sedimentary systems, and the central part develops shoreline shallow lake facies sediments. The western Kunlun Mountains in the south are the main source of material supply, while the Maigaiti ancient uplift in the north is the secondary source of material supply. The ancient uplift during the sedimentation period of the Kizilsu Group has a blocking effect on the delta that flows into the lake, dividing the southern fan delta and lake sedimentary system from the northern braided river delta and lake sedimentary system.

How to cite: Zhang, Y. and Zhang, L.: Application of Sedimentary Forward Simulation in the Kezilesu Group of the Kedong Structural Belt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2738, https://doi.org/10.5194/egusphere-egu24-2738, 2024.

EGU24-3400 | ECS | PICO | GM7.3

Small endorheic basin sediments along a climatic gradient as paleoenvironmental archives 

Itzhak Raish, Joel Roskin, Shlomy Vainer, and Revital Bookman

 

Understanding and quantifying the natural variability and evolution of past climate systems require the use of datasets that are considerably long, continuous, and of broad spatial coverage. However, common terrestrial proxies, specifically in low- and mid-latitude could be puzzling due to the diversity of climate systems that records a mixed and regionally wide signal that fails to detect the short-term and transitional climate variability. In Holocene records, which are often used to study human-environment interactions, these resolutions are critical.

Here we explore the potency of deposits that are filling endorheic (internally drained) basins of not more than several km2 in size to serve as paleoenvironmental archives. We focus on three sites spread along a steep, ~150 km long climatic gradient in Israel that are influenced by several atmospheric circulation patterns. Core-drilled sediments acquired from such basins have undergone sequential analyses to characterize their textural, geochemical, and luminescence properties. Optically stimulated luminescence (OSL) dating, applied to construct a chronological framework, is coupled with port/pulsed OSL (POSL) analyses, mainly to analyze sedimentation trends and target samples for OSL dating.

The geomorphic and sedimentological responses to environmental perturbations of the late Quaternary are reflected distinctly in each site. Changes in depositional environments that occur throughout all sites often point to similar regional climatic trends, and are partly synchronous with established climatic events.  The compiled interpretation from several sites along a given climatic transect is anticipated to form a robust regional paleoenvironmental framework that can serve a wide range of Quaternary studies.

How to cite: Raish, I., Roskin, J., Vainer, S., and Bookman, R.: Small endorheic basin sediments along a climatic gradient as paleoenvironmental archives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3400, https://doi.org/10.5194/egusphere-egu24-3400, 2024.

EGU24-5535 | ECS | PICO | GM7.3

The formation and development of nebkhas based on chronology and sedimentology in the Ordos Plateau, northern China 

Yue Du, Ruijie Lu, Luo Ma, Dongxue Chen, and Yingna Liu

The Ordos Plateau lies on the northwest margin of the East Asian monsoon region as well as the farming-pastoral ecotone in northern China, with a wide distribution of nebkhas. The formation and development of nebkhas in this region are closely related to natural envi ronmental conditions and human activities. However, the processes of nebkhas formation and development under natural and anthropogenic influence still remain unclear. In this study, four typical nebkhas in the Ordos Plateau were selected after detailed field investigations. Chronology and sedimentary features of the formation and development of nebkhas were studied based on optically stimulated luminescence (OSL) dating, lithology, grain size, etc. The results demonstrated that modern nebkhas had formed since at least ~0.59 ka in the southwest of the Ordos Plateau, followed by the middle region, at least ~0.34 ka, and later in the south and north regions, at least ~0.10 ka. There were thin layers of weakly-developed paleosols at ~0.32-0.25 ka, peaks in the silt and fine sand content and lower deposition rates, about 0.37-0.46 cm/a, indicating a relatively humid climate and weak aeolian activities. After ~0.10 ka, aeolian activities intensified and the nebkhas widely developed with a higher deposition rate, ~0.45-5.21 cm/a. Nebkhas in the study region developed primarily over paleo-channels or paleosol layers. Very fine sand and fine sand were dominant composition on grain size of nebkha sediments; saltation was a main means for the particle movements, indicating near-source accumulation for nebkha sediments. In recent decades, local farmers are used to adding nebkhas deposits to the soil of irrigation areas to improve the soil quality and alleviate soil salinization. Such agricultural activities, together with land reclamation, have accelerated the demise of the nebkhas in the Ordos Plateau.

How to cite: Du, Y., Lu, R., Ma, L., Chen, D., and Liu, Y.: The formation and development of nebkhas based on chronology and sedimentology in the Ordos Plateau, northern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5535, https://doi.org/10.5194/egusphere-egu24-5535, 2024.

EGU24-5537 | ECS | PICO | GM7.3

Estimation of aeolian sediment volume in the middle reaches of the Yarlung Zangbo River based on GPR and LiDAR 

Jianyu Ling, Rongyi Qian, Xu Liu, Zhibo Huang, Ding Wang, Ketong Hu, and Jinhang Zhang

Sand control is one of the most important components of environmental protection. In the middle reaches of the Yarlung Zangbo River, the phenomenon of desertification is becoming serious, which has a great impact on the local ecological environment protection and economic development. The accurate estimation of the volume of aeolian sediment is of great significance to the formulation of the treatment plan. However, most of the existing studies are based on remote sensing interpretation to estimate the area of aeolian sediment, and the research on the volume of aeolian sediment is relatively weak. To make up for this research gap and provide reliable basic information for sand control in the middle reaches of the Yarlung Zangbo River, we carried out research on estimation of aeolian sediment volume based on GPR and LiDAR. The experimental area of this study is located in Zhanang County in the middle reaches of the Yarlung Zangbo River, with an area of approximately 1.8 km2. We set up six GPR survey lines in the experimental area and obtained the bottom interface and corresponding average elevation of aeolian sediment. Subsequently, high-precision surface elevation of the study area was obtained by LiDAR, and the average surface elevation was calculated. Then we obtained the average thickness of the aeolian sediment is 3.25 m by subtraction of the average surface elevation and the elevation of the aeolian sediment bottom interface. Finally, we determined that the volume of aeolian sediment in the experimental area was about 5,850,000 m3. Our study has realized the volume estimation of typical aeolian sediment area in the middle reaches of Yarlung Zangbo River, which has important guiding significance for sand control.

How to cite: Ling, J., Qian, R., Liu, X., Huang, Z., Wang, D., Hu, K., and Zhang, J.: Estimation of aeolian sediment volume in the middle reaches of the Yarlung Zangbo River based on GPR and LiDAR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5537, https://doi.org/10.5194/egusphere-egu24-5537, 2024.

Climate change continues to impact diverse ecosystems. Drylands stand out as particularly vulnerable environments, as they are highly responsive to key indicators of change. The sensitivity and response time of these regions remain largely unknown, underscoring the need for a deeper understanding of their systems.

Arid regions are considered optimal for Earth Observation based research, primarily due to factors such as minimal anthropogenic disturbance, sparse vegetation cover, and low cloud coverage. These attributes make drylands advantageous for studying and monitoring the impact of climate change, providing valuable insights into these vulnerable ecosystems.

Southern Mongolia stands out as an especially well-suited study area to test novel approaches and to detect land surface changes over both space and time. The basin of Orog Nuur was selected in this study to observe long-term environmental changes, building on significant prior studies conducted around the drainage basin.

Our approach emphasizes the utilization of state-of-the-art earth observation technology to unveil the dynamics of desert ecosystems. This involves cloud-based processing, such as Google Earth Engine and the German High Performance Data Analytics (HPDA) platform “terrabyte”. Throughout the project, we will apply various multispectral and active SAR techniques spanning 50 years to monitor geomorphological processes, ecosystem changes and ongoing surface dynamics linked to climate change indicators. Some of important pillars of the long-term time series analysis can be listed as greening and precipitation events, lake level dynamics, dune movement rates, mapping of sedimentological, geomorphological provinces and aeolian coverage, in order to understand frequency-magnitude relationships.

The findings will be supported by a series of fieldworks covered by UAS campaigns and auxiliary ground-truth sensors, ensuring the accuracy of our estimations by in-situ measurements. Based on the derived surface characteristics, various ecosystems will be defined, and a high-level ecosystem integrity model will be developed. Ultimately, our model aims to represent the intactness, functioning and structure of the different ecosystems within arid regions. Additionally, due to our high temporal study concept, the model will serve as the base for quantifiable measurements of the responsiveness and adaptiveness of the ecosystems.

Having a model for ecosystem intactness not only help to preserve fragile ecosystems but also strengthens the resilience and adaptive capacity of communities. Furthermore, the transferability of our framework to other drylands may also lead to a comprehensive understanding of the arid characteristics.

Keywords: Earth Observation, arid regions, dryland, remote sensing, climate change, impact, geomorphological process, ecological modelling, land surface dynamics

How to cite: Arisoy, B., Ullmann, T., and Stauch, G.: Desert Sensing – Characterizing recent surface dynamics in arid regions through high-performance data analytics of multi-sensor Earth Observation archives and in situ records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10337, https://doi.org/10.5194/egusphere-egu24-10337, 2024.

Mineral dust aerosol particles are tiny soil particles mobilized and entrained into the atmosphere by wind. Suspended in the atmosphere and transported away from source regions by prevailing wind systems, dust aerosol alters the Earth’s radiation budget, stimulates cloud and precipitation formation processes, and modulates the carbon cycle as it may enhance bio-productivity due to its mineralogical composition. In the light of the manifold dust feedbacks with relevance to the climate, knowledge on the atmospheric pathway of dust from source to sink is essential for accurate climate simulations. Thereby, the spatio-temporal variability of dust source activity, and consequent dust production and entrainment into the atmosphere is of particular interest as dust emission marks the beginning of the atmospheric dust cycle. Although crucial for the understanding of the climate system, detailed knowledge on the interannual variability of dust source characteristics (i.e., emissivity and their susceptibility to wind erosion) and activity (i.e., occurrence frequency of dust emission events and emission fluxes) is still somewhat limited. In particular the impact of changing environmental conditions on dust sources and their emission variability is not fully understood yet and requires further research. This is also of importance in order to assess the spatially and temporally changing contribution of dust sources to the local and regional atmospheric dust burden and related dust feedbacks.

This presentation will provide an overview of different dust source types, their key characteristics, and their response to environmental changes due to climate change with regard to emission flux and dust source activity. It will include examples from remote sensing approaches and dust modelling in order to examine the interannual variability in a changing climate.

How to cite: Schepanski, K.: Mineral dust in the climate system: Dust source types and their response to environmental changes in a changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11443, https://doi.org/10.5194/egusphere-egu24-11443, 2024.

Aeolian-Fluvial interactions range from aeolian- to fluvial-dominated processes, often resulting in unique morphologies and complex stratigraphies along dunefield margins. In the Northwestern Negev dunefield (Israel) desert, a key factor influencing transitions from aeolian- to fluvial-domination, is the basin size. While medium-sized (40-200 km2) and large (>200 km2) basins were breached before or during the early Holocene, small basins are still dammed by dunes. Often their surficial and buried palaeochannel is comprised of a sequence of remain of dune-dammed water bodies in the form of fossilized playas. Unlike medium and large basins, where incision exposes Aeolian-Fluvial deposits after the dune-dam breaching, small dune-dammed fluvial systems necessitate sampling techniques such as drilling into continuously aggrading Aeolian-Fluvial deposits to reconstruct the stratigraphy and interpret paleoclimate and palaeoenvironmental records. We demonstrate the potential of a SUERC Portable-OSL (port-OSL) for interpreting palaeo-records in small dune-dammed basins.

The Shivta-East basin (3.3 km2) was hand-augered along an ephemeral stream's propagation path into the dunefield, at three disconnected playa-like sediments of seasonal dune-dammed waterbodies. At each dune-dammed waterbody sediments, samples were taken at 15-25 cm intervals and analyzed using the port-OSL reader. Their estimated ages were interpolated according to a calculated regional linear regression based on the northwestern Negev dunefield luminescence age database. This regression, generated by training a data set of thirty-two aeolian sand samples, analyzed for both OSL dating and port-OSL Net counts, accounts for 72% of the age variability, with a standard error of 3.4 ka between the model and the data. Due to the absence of modern-day OSL dated samples, the regression line was reconstructed for the LGM until the early Holocene. The regression model enables dating of the Last Glacial Maximum, Heinrich-1, and Younger Dryas sand incursions, previously described as the main active periods of the aeolian system.

K-means cluster analysis based on the port-OSL signals, reveals three distinct clusters, which points to alternations of the sedimentary units, between sand and fluvial sourced fine-grained sediments. The three clusters are understood to reflect both the mineralogical composition and burial age of the deposits. The overlying cluster mainly consists of fine-grained sediments deposited in the dune-dammed waterbody, while the other two units are sandy deposits.

Interpolation of the sandy samples from all three playas along the palaeochannel in the linear regression demonstrates that during the Heinrich-1 and Younger Dryas events, an aeolian-dominated environment dune-dammed the fluvial system, enabling aeolian sand deposition. Later, coevally with the fluvial system's propagation into the second (middle) dune-dammed waterbody, aeolian domination persisted until the Early Holocene generating the third and upstream dune-dammed waterbody.

This study demonstrates the potential and limitations of the port-OSL reader combined with statistical methods for chrono-stratigraphic analysis of hand-augered samples collected from an altering depositional environment. The ability to rapidly estimated depositional ages and associated palaeoclimatic periods highlights the potential for further exploration of the port-OSL reader in different environmental settings.

How to cite: Greenbaum, N., Robins, L., and Joel, R.: Regional Depositional Age Assessment using Portable-OSL of Hand-Augered Aeolian-Fluvial Deposits along a chain of Small Dune-Dammed Basins in the Northwestern Negev Dunefield Margins, Israel , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12423, https://doi.org/10.5194/egusphere-egu24-12423, 2024.

The Great Central Desert of Iran, located at the center of the Iranian plateau, bears valuable but scattered geological and geomorphological archives. However, the scarcity of data on the paleoenvironment and paleolandscape of this area is attributed to challenging accessibility and harsh climatic conditions. The Khur area in the eastern edge of the Iranian Central desert was selected for this investigation due to its distinctive geomorphological features and improved accessibility.
This study aims to delineate Late Pleistocene-Holocene landscape evolution in central Iran by utilizing sedimentary and morphostratigraphical evidence of aeolian-fluvial sequences. In a first step, geomorphological features were mapped based on satellite imagery, digital elevation models, geological maps and field observations. Subsequently, localities for excavator sections were deduced from these findings, guaranteeing accessibility and further ensuring their incorporation of anticipated stratigraphic key features, including contact zones of distinct geomorphological environments. Stratigraphic description of the excavated profiles was recorded, and sedimentary logs were drawn.
The preliminary results reveal complex interactions of Aeolian, fluvial, and lacustrine morphodynamics during the Late Pleistocene and Holocene. Seven landform groups including aeolian dunes and interdune areas, sandy mud flat, alluvial fans and fluvial plains, dissected fan toe with backward erosional valleys were recognized. Within these, five interfingering sedimentary units were identified based on distinctive geometry and layering and their internal facies distribution: Fluvial flood deposits, well to poorly-sorted alluvial deposits, aeolian sand deposits, fluvially reworked marl (fine-grained mud), paleosol horizons.
In summary, repeatedly changed depositional environments and cyclical climatic changes, where dune development took place during phases of increasing aridity, whereas non-aeolian deposition and paleosol formation might have occurred during more humid conditions and more stable paleosurfaces.
Luminescence dating, sedimentological and geochemical analyses, will determine climatic cycles, sedimentary environments and landscape evolution history.

How to cite: Rashidi Koochi, Z., Büdel, C., Torabi, M., Baumhauer, R., and Fuchs, M.: Towards Late Pleistocen-Holocene stratigraphy and landscape evolution of Khur area, Central IranTowards Late Pleistocen-Holocene stratigraphy and landscape evolution of Khur area, Central Iran, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12653, https://doi.org/10.5194/egusphere-egu24-12653, 2024.

EGU24-13466 | ECS | PICO | GM7.3

Reconstructing timeframes, processes and environmental implications of Late Quaternary aeolian Parna deposition in south-eastern Australia 

Felix Lauer, Samuel Marx, Anthony Dare-Edwards, and Jan-Hendrik May

Sedimentary sequences with major aeolian dust contribution blanket the flat to hilly landscapes of eastern New South Wales. Originally identified by Butler in 1956 within the Riverine Plain and adjoining hills, these widespread clay-rich sediments were termed "Parna”. Parna – which has often been compared to loess – is thought to be fine-grained sediment generated through exogenic processes in arid environments and transported as stable aggregates by prevailing westerly winds during the Quaternary. The primary hypothesized source regions for Parna are arid and semi-arid river and lake systems situated in the western Murray-Darling Basin. Despite the prolonged critical discourse surrounding the concept and terminology of Parna, investigations addressing unresolved questions have been limited, with absolute dating of the aeolian sequences being restricted to only a few sites.

Given the complexity of the Parna sequences resulting from the interaction of aeolian, hillslope and pedological processes, we choose a multimethodological approach combining field observations, grain size analysis, geochronological and geochemical methods to investigate the processes and time frames of sedimentation and sediment provenance. Results of optically stimulated luminescence (OSL) dating for several Parna sites in the Wagga Wagga (Beattie 1972) and Yass region, show age estimates reaching back 150,000 years. Sedimentological parameters are used to distinguish between material derived from local hillslope and aeolian input. Geochemical characteristics will help to trace sources and pathways of the aeolian material. Advancing our understanding of the Parna concept, implying large-scale deposition but also deflation of aeolian material, is one component of reconstructing Quaternary landscape development and environmental conditions in south-eastern Australia.

Butler, B.E., 1956. Parna-an aeolian clay. Australian Journal of Science, 18(5), 145-151.

Beattie, J.A., 1972. Groundsurfaces of the Wagga Wagga Region, New South Wales. C.S.I.R.O Soil. Pub Australia. No. 28.

How to cite: Lauer, F., Marx, S., Dare-Edwards, A., and May, J.-H.: Reconstructing timeframes, processes and environmental implications of Late Quaternary aeolian Parna deposition in south-eastern Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13466, https://doi.org/10.5194/egusphere-egu24-13466, 2024.

EGU24-15208 | PICO | GM7.3

Optically stimulated luminescence dating of loess sequences in the Tibetan Plateau and their palaeoenvironmental implications 

Shengli Yang, Li Liu, Qiong Li, Pushuang Li, and Yuanlong Luo

The Tibetan Plateau (TP) is extremely sensitive to climate change. Widely loess deposits distributed in the Tibetan Plateau are important archives for studying the past environmental changes of the Tibetan Plateau. However, little information is understood due to the poorly age constrained of the TP loess. In this study, we use the single-aliquot regenerative dose optically stimulated luminescence (OSL) method, and the post-infrared infrared stimulated luminescence protocol (pIRIR) to date the well-preserved loess–paleosol sequences in the eastern TP and discuss the applicability and reliability of OSL dating of the TP loess for establishing a reliable numerical age framework. We found that quartz OSL signal of TP loess is dominated by fast component, and the equivalent dose can be measured by SAR method. The growth curve shapes and saturation dose shows that the quartz OSL signal in this region saturated at ~200~230 Gy. The prior-IR stimulation plateau test, dose recovery, recycling ratio and recuperation indicated that pIR200IR290 could be used for the equivalent dose estimation of potassium feldspar. Our results contribute to an improved understanding of the TP dust history and paleoenvironmental changes in the Last Glacial cycles.

How to cite: Yang, S., Liu, L., Li, Q., Li, P., and Luo, Y.: Optically stimulated luminescence dating of loess sequences in the Tibetan Plateau and their palaeoenvironmental implications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15208, https://doi.org/10.5194/egusphere-egu24-15208, 2024.

EGU24-21074 | PICO | GM7.3

Holocene linear dune accumulation in the western Thar desert, India.  

Shashank Nitundil, Abi Stone, Aayush Srivastava, and Komal Songara

The densely populated Thar Desert in the northwestern part of the Indian subcontinent contains a complex spatial pattern of now vegetated dune morphologies. There is a growing dataset of luminescence ages that demonstrates a dominance of Holocene dune dynamics in the preserved record (e.g., Srivastava et al, 2020; Parida et al., 2023; Nitundil et al., 2023). This region is undergoing rapid change in recent decades with widespread flattening of dunes for agricultural land, which is fed by the Indira Gandhi Canal that provides water for irrigation.

 

Our work has developed a training set of >40 samples with published luminescence ages to create a calibration approach for the signals measured using portable luminescence readers (POSL) (Nitundil et al., 2023). Other POSL signal characteristics, such as IRSL:BSL ratios are a good indicator that the Thar sands have a broadly common sedimentary provenance, as well as transport processes and post-depositional histories of mineral weathering. During this work, a rigorous exploration of sediment properties, including moisture content and presence of carbonate was undertaken, and from this, guiding principles for building a calibration curve were developed.

 

Vegetated linear dunes have been sampled in five regions along a ~75 km north-south transect in the western Thar. The POSL calibration has been applied to determine estimated ages for three dunes at the second most northerly site, to shallow depths (2 m) (Nitundil et al., 2023), and from multiple profiles within two dunes at each of three other sites along the transect (a further 19 shallow, 2 m profiles). Fieldwork in September 2023 focussed on obtaining close to full dune vertical profiles via auguring (~10 m depth) from three sites, as well as exploring dynamics across and along a dune using ~0.8 m hand dug pits. This presentation will highlight key findings from the calibration exercise, and present POSL-based ages estimates across the western Thar to explore what they reveal about Holocene dune accumulation in this region. 

 

References

Nitundil, S., et al. (2023) Applicability of using portable luminescence reader for rapid age-assessments of dune accumulation in the Thar desert, India. Quat. Geochron. 78, 101468.

Parida, S. et al. (2023) Luminescence Dating of Dunes in the Western Thar Desert:  New Data and Regional Synthesis. XXI INQUA Congress, 14-20th July 2023, Rome, Italy.

Srivastava, A., et al. (2020) Holocene palaeoenvironmental changes in the Thar Desert: An integrated assessment incorporating new insights from aeolian systems. Quat. Sci. Rev. 233, 106214.

 

How to cite: Nitundil, S., Stone, A., Srivastava, A., and Songara, K.: Holocene linear dune accumulation in the western Thar desert, India. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21074, https://doi.org/10.5194/egusphere-egu24-21074, 2024.

EGU24-21086 | PICO | GM7.3

S.A.N.D.S. - Surface Archaeology on the Namib Desert Surface.  

Abi Stone, Dominic Stratford, Ted Marks, Rachel Bynoe, Kaarina Efraim, Eugene Marais, Rachel Smedley, and George Leader

The hyper-arid Namib Sand Sea (NSS) represents a significant challenge to human occupation, yet, despite these challenges, Early Stone Age (ESA) and Middle Stone Age (MSA) tools are found across this landscape. Whilst surface scatters are hindered by a lack of clear stratigraphy, they provide a spatially integrated record of the structuring of landscape use through time and relationships to sources of raw material and water. Omitting such sites leads to bias in our interpretations of early hominin distribution. We are investigating how and why early hominins were moving into the northern NSS, starting with two interdune pan sites: Namib IV (Leader et al., 2023) and Narabeb. Here we set out the context of these archaeological sites, the stratigraphies observed and our emerging luminescence chronologies for the sedimentary sequences.

 

To establish the palaeoenvironmental context of the lithics (both ESA and MSA) and fossil fauna at Namib IV we dug a series of test pits to explore the sedimentological record. The Namib IV surface has a complex meso-topography with a spatially-patchy, resistant calcareous surface unit, and our test pits reveal a similarly complex sedimentary record across space. This includes the preserved remnant of an aeolian slip face, and elsewhere a number of horizontally bedded units beneath surface calcareous layers. 13 samples from Namib IV were selected for luminescence dating, using pIRIRSL feldspar methods, anticipating ages close to quartz saturation (e.g. Stone et al. (2010) in this region). Narabeb contains predominantly MSA lithics. North (~2 km) of the artifact collection area is a prominent ‘ledge’ of interbedded muds and sands, previously dated using quartz OSL (Stone et al., 2010). We dug two small geotrenches associated with surface calcareous exposures, taking samples for pIRIRSL dating along with two sampling points in the lower unconsolidated dune flank. We also date a sample from the Stone et al. (2010) sequence using pIRIRSL (K fieldspar) to revise the saturated quartz luminescence age estimate.

 

References

Leader, G.M., Bynoe, R., Marks, T., Stone, A., Efraim, K., Stratford, D., Marais, E. (2023) Revisiting the Acheulean at Namib IV in the Namib Desert, Namibia. Journal of Field Archaeology 48(5), 380-394.

Stone, A., Thomas, D.S.G., Viles, H.A. (2010) Late Quaternary palaeohydrological changes in the northern Namib Sand Sea: new chronologies using OSL dating of interdigitated aeolian and water-lain interdune deposits. Palaeogeography, Palaeoclimatology, Palaeoecology 288 (1-4), 35-53.

How to cite: Stone, A., Stratford, D., Marks, T., Bynoe, R., Efraim, K., Marais, E., Smedley, R., and Leader, G.: S.A.N.D.S. - Surface Archaeology on the Namib Desert Surface. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21086, https://doi.org/10.5194/egusphere-egu24-21086, 2024.

EGU24-118 | Posters on site | HS2.1.5

Precipitation, temperature, and vegetation indices analysis for Saudi Arabia region: Feasibility of Google Earth Engine 

Zaher Mundher Yaseen, Bijay Halder, Mohamed A. Yassin, and Sani I. Abba

Climatic disaster is continuously triggering environmental degradation and thermal diversification over the earth's surface. Global warming and anthropogenic activities are the triggering factors for thermal variation and ecological diversification. Saudi Arabia has also recorded precipitation, temperature, and vegetation dynamics over the past decades. Therefore, monitoring past precipitation, temperature, and vegetation condition information can help to prepare future disaster management plans and awareness strategies. The Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks - Climate Data Record (PERSIANN-CDR) from the Center for Hydrometeorology and Remote Sensing (CHRS) data portal and Moderate Resolution Imaging Spectroradiometer (MODIS) are applied for precipitation, Land Surface Temperature (LST), Enhance Vegetation Index (EVI), and Normalized Difference Vegetation Index (NDVI) from 2003 to 2021 respectively. Yearly mean LST, EVI, NDVI, and precipitation values are calculated through the Google Earth Engine (GEE) cloud computing platform. MODIS-based LST datasets recorded the highest temperatures is 43.02 °C (2003), 45.56 °C (2009), 47.83 °C (2015), and 49.24 °C (2021) respectively. In between nineteen years, the average mean LST increased by 6.22 °C and the most affected areas are Riyadh, Jeddah, Abha, Dammam, and Al Bahah. The mean Precipitation is recorded around 776 mm, 842 mm, 1239 mm, and 1555 mm for the four study periods, while the high precipitation area is Jazan, Asir, Baha, and Makkah provinces. In between nineteen years, 779 mm of precipitation is increasing in Saudi Arabia.  Similarly, the NDVI vegetation indices observed 0.885 (2003), 0.871 (2009), 0.891 (2015), and 0.943 (2021), while EVI observed 0.775 (2003), 0.776 (2009), 0.744 (2015), and 0.847 (2021). The R2 values of the LST and EVI correlation is 0.0239 (2003), 0.0336 (2009), 0.0136 (2015) and 0.0175 (2021) similarly correlation between LST and NDVI is 0.0352 (2003), 0.0265 (2009), 0.0183 (2015) and 0.0161 (2021) respectively. The vegetation indices indicate that the green space is gradually increasing in Saudi Arabia and the highly vegetated lands are Meegowa, An Nibaj, Tabuk, Wadi Al Dawasir, Al Hofuf, and part of Qaryat Al Ulya. This analysis indicates that the temperature is increasing but precipitation and green spaces are increasing because of the groundwater recharge through dam construction, precision agriculture, and planned build-up is helps to prepare Saudi Arabia as a green country. Therefore, more attention to preparing the strategic agricultural plants as well as other vegetation and artificial groundwater recharge can improve the country as a green nation. This analysis might help to prepare future planning, awareness, and disaster management teams to prepare for future disasters and strategic steps for sustainable development.

How to cite: Yaseen, Z. M., Halder, B., Yassin, M. A., and Abba, S. I.: Precipitation, temperature, and vegetation indices analysis for Saudi Arabia region: Feasibility of Google Earth Engine, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-118, https://doi.org/10.5194/egusphere-egu24-118, 2024.

Water is scarce in the northern Chihuahuan Desert, with ~350 mm/yr precipitation, potential evapotranspiration at 1800mm/yr, and rising mean annual temperatures by >2°C since 1960. The main water resources are the Ogallala, Pecos Valley, Dockum, and Edwards-Trinity Plateau aquifers, with depletion rates of ~1 m/yr. Despite the arid climate, the Monahans and Kermit dune fields host perched water tables 1-10 m below the surface, in up to 40 m of aeolian sand spanning the past ca. 2.6 ma, and isolated from the underlying Pecos Valley Aquifer by a Pliocene/Pleistocene fluvial gravel-rich clay. A 3D model based on borehole lithology shows a topographic inversion with a southwest-trending paleo-slope infilled with aeolian sand. The aeolian stratigraphy and basin modeling indicate progressive infilling by aeolian sand with periods of pluvial lake formation and soil development, with groundwater providing dune field stability for vertical accretion and limiting aeolian erosion. Cores of sediments retrieved from the Monahans and Kermit dune fields were sampled for OSL ages and yielded ages up to 500 ka 20 m below the surface of the dunes, with identified deposition periods between 545-470 ka, 300-260 ka, 70-45 ka and post 16 ka. A set of three monitoring wells equipped with data loggers revealed aquifer recharge of 35-40 cm in the Spring and Fall consistent with regional precipitation variability, and a daily recharge cycle of 3-8 mm potentially linked to plant uptake or gravitational forces. Deuterium and 18O isotopic ratios for the dune field aquifers indicate an evaporative enriched water source compared to the Pecos Valley Aquifer, Pecos River, and Chihuahuan Desert precipitation, consistent with local precipitation. Apparent 14C ages <1360 yr for aquifer waters from the upper 1 m indicate recent meteoric recharge. Older 14C ages of > 1.3 to 2.2 ka for waters ~30 m deep and at the western edge of the aquifer indicate mixing with Holocene recharge waters in a southwest flowing aquifer. In contrast, the Pecos Valley Aquifer yields 14C ages of ca. 0.9 to 40 ka with the youngest ages near the dune fields, which suggests recharge from these perched aquifers.

How to cite: Fournier, A. and Forman, S.: Origin, gradient, and recharge processes of perched aquifers of the Monahans and Kermit dune fields, northern Chihuahuan Desert, Texas, USA , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-765, https://doi.org/10.5194/egusphere-egu24-765, 2024.

EGU24-1165 | ECS | Orals | HS2.1.5

Agrohydrological modelling approach for assessing the impact of climate change on water resources and land management in the Messinian region, Greece. 

ismail bouizrou, Giulio Castelli, Gonzalo Cabrera, Lorenzo Villani, and Elena Bresci

The Mediterranean region is highly susceptible to the consequences of warming, leading to an increasing of extreme events such as droughts, severe heat waves, and precipitation events. The Messinia watershed (MW) is predominantly characterized by olive cultivation, encompassing approximately 70% of the landscape. These olive orchards constitute a vital component of the Mediterranean ecosystem, playing a crucial role in regional agriculture. The MW is a perfect illustration of a Mediterranean watershed significantly impacted by climate change, as well as soil degradation and a lack of effective land management practices.

In this context, agro-hydrological modelling emerges as a potent tool to address soil degradation and enhance water resource retention within the olive orchards at the watershed scale. To achieve this objective, the SWAT+ agrohydrological model was chosen for a comprehensive assessment of the potential impacts of climate change on water resources and ecosystems in the Messinia region. The adopted modelling approach involved both hard and soft calibration techniques, simulating four sub-watersheds of Messinia by incorporating remote sensing data, including evaporation and soil moisture, for multi-criteria model calibration.

The calibrated model was subsequently employed to assess the potential impacts of climate change on water resources and ecosystems in the Messinia region, utilizing various RCM climate scenarios. Our findings are valuable for addressing soil degradation, as well as for guiding land and water management practices in the Messinian watershed.

 

 

This research was carried out within the SALAM-MED project, funded by the Partnership for Research and Innovation in the Mediterranean Area Programme (PRIMA).

The content of this abstract reflects the views only of the author, and the Commission cannot be held responsible for any use that may be made of the information contained therein.

 

How to cite: bouizrou, I., Castelli, G., Cabrera, G., Villani, L., and Bresci, E.: Agrohydrological modelling approach for assessing the impact of climate change on water resources and land management in the Messinian region, Greece., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1165, https://doi.org/10.5194/egusphere-egu24-1165, 2024.

Desertification on the Mongolian Plateau is deepening, and sand and dust have great negative impacts on many countries in East Asia. Based on meteorological and socio-economic data in the context of climate change, this study analyzed the driving mechanisms and impacts of desertification and water body area response on the Mongolian Plateau using, among others, the GTWR model. The following conclusions were drawn: the area of the Mongolian Plateau showed a decreasing trend from 1990 to 2019, and the number of lakes larger than 1 km2 decreased by 173 or 537.3 km2 in Inner Mongolia, and by 737 or 2875.1 km2 in Mongolia, and all of them were dominated by lakes of 1-10 km2; and the analysis of the correlation between the area of the water bodies showed that the The reasons driving the change of water body area in Inner Mongolia Autonomous Region and Mongolia are similar and different, soil moisture and precipitation have obvious promotion effects, economic development and livestock numbers have different degrees of negative impacts on different countries; The GTWR model is used to represent the impacts of different influencing factors on the water body area in time and space, and the evaporation and GDP are shifted from slight inhibition to promotion, and the population and temperature are both inhibited. Soil moisture and livestock numbers are contributing; Surface water resource monitoring is important to deepen the desertification of the Mongolian Plateau and to provide better water resource recommendations and protection measures for the Mongolian Plateau.

How to cite: Yan, Y. and Cheng, Y.: Study of water body area changes in the desertification process of the Mongolian Plateau and analysis of driving factors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1185, https://doi.org/10.5194/egusphere-egu24-1185, 2024.

EGU24-2567 | ECS | Orals | HS2.1.5 | Highlight

GIRHAF (Gridded hIgh-resolution Rainfall for the Horn of AFrica): a new rainfall product for detailed applications in a region beset by climate hazards 

Manuel F. Rios Gaona, Katerina Michaelides, and Michael Bliss Singer

Rainfall is one of the most important inputs for applications such as hydrological modelling, water resource allocation, flood/drought analysis, and climatic risk assessments. Currently, there exist numerous (global) products offering rainfall estimates at various spatio-temporal resolutions. Nevertheless, there are still places on Earth where the coverage and/or quality of such products is limited due to sparse ground-control data, thus constraining the robustness of input rainfall for hydrological and climate applications. Located in Eastern Africa, the Horn of Africa (HOA) is a place where climate impacts like droughts and floods frequently inflict a huge toll on the lives and livelihoods of millions residing in subsistence rural communities. For places like this, high resolution rainfall data are fundamental to understanding the availability of water resources, flood hazard, and soil moisture dynamics relevant to crop yields and pasture availability.

Here we introduce GIRHAF (Gridded hIgh-resolution Rainfall for the Horn of AFrica), which is a 20-year rainfall product, with a spatio-temporal resolution of 0.05°×0.05°, every 30 minutes. GIRHAF is based on downscaling CHIMES (Climate Hazards center IMErg with Stations) a pentad operational rainfall product which corrects microwave signals in IMERG (Integrated Multi-satellitE Retrievals for GPM -Global Precipitation Measurement mission-) by in situ rain gauging networks. The goal of this product is to offer the HOA region high-resolution rainfall fields that can support more detailed mechanistic analyses of historical rainfall and can also provide the base dataset required to develop stochastic rainfall models capable of simulating forecasted or projected climate scenarios. It is our aspiration that GIRHAF will enable improved responses to climatic hazards as well as better water resources management in the HOA region, and perhaps to allow people of this region to better prepare to future climate scenarios.

How to cite: Rios Gaona, M. F., Michaelides, K., and Singer, M. B.: GIRHAF (Gridded hIgh-resolution Rainfall for the Horn of AFrica): a new rainfall product for detailed applications in a region beset by climate hazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2567, https://doi.org/10.5194/egusphere-egu24-2567, 2024.

EGU24-4462 | ECS | Posters on site | HS2.1.5

Modeling the impact of climate and land use changes on future water resources dynamics in central Sicily, Italy 

Shewandagn Lemma Tekle and Brunella Bonaccorso

Drought events, worsened by climate change, produce detrimental impacts on freshwater availability especially in arid and semi-arid regions. The situation becomes more critical when these hydrologic extremes combine with land use change mainly caused by anthropogenic factors, such as urbanization, intensive farming, and industrial activities. The present study is designed to investigate the combined impacts of climate and land use changes on the future freshwater  stored in the artificial reservoirs of three adjacent river basins located in the central Sicily (Italy), i.e: Verdura (2 active reservoirs with capacities 9.2 Mmc and 4.19 Mmc), Imera Meridionale (one active reservoir with capacity 15 Mmc), and Platani (one active reservoir with capacity 20.7Mmc), using the Soil and Water Assessment Tool (SWAT) model. The reservoirs are used for irrigation, drinking water supply, and electric power generation. Future climate variables such as rainfall, minimum and maximum temperatures were derived from an ensemble Regional Climate Models for two main representative concentration pathway (RCP) scenarios, such as an intermediate emission scenario (RCP4.5) and a severe emission scenario (RCP8.5). A coupled multi-layer perceptron neural networks and cellular automata (MLP-CA) model was implemented to simulate future land use of the region considering the CORINE land cover in 2000, 2006, 2012, and 2018 as a reference dataset. The future land use is then projected until the mid-century (2048) in a six-year interval using the validated MLP-CA model. The soil data from the European soil data center (EUSDAC) was used as input for the SWAT model. The result indicated that the basins could experience a decrease in inflows to the reservoirs. The separate evaluation of climate change and land use changes indicated that the effect of climate change on streamflow variation is more pronounced than the effect of land use change only. In this study, we introduced new hydrological insights into the region by analyzing the attributions of climate change, land use change, and coupled climate and land use changes on the future freshwater availability which were overlooked in the previous studies. The implementation of the proposed approach can contribute to design environmentally sustainable and climate resilient river basin management strategies.

 

Keywords: MLP-CA, Land use change, Climate change, SWAT, Hydrological modeling, Water availability

How to cite: Tekle, S. L. and Bonaccorso, B.: Modeling the impact of climate and land use changes on future water resources dynamics in central Sicily, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4462, https://doi.org/10.5194/egusphere-egu24-4462, 2024.

EGU24-5604 | Orals | HS2.1.5

An integrated hydrological modeling approach to assess the natural groundwater recharge trends in a Mediterranean coastal aquifer 

Anis Chekirbane, Khaoula Khemiri, Constantinos Panagiotou, and Catalin Stefan

Integrating physical models with socio-economic considerations is essential to sufficiently analyze complex hydrological systems and design effective strategies for groundwater management. This integrated approach offers an effective means of detecting links between aquifer properties and groundwater processes. This study aims to assess the impact of human activities and climate changes on groundwater resources. In particular, the final goal is to quantify the spatial distribution of natural groundwater recharge, which is needed to assess the impact of anthropogenic factors on sustainable groundwater management in the Chiba watershed, NE of Tunisia as an example of a stressed hydrosystem.

The proposed methodology is based on the estimation of natural groundwater recharge through hydrological modeling with the use of the SWAT model while considering land use/land cover changes occurring within the study area, coupled with the DPSIR (Drivers-Pressures-States-Impacts-Responses) socio-economic approach for time period 1985-2021. The surveys were constructed and processed based on the probability of occurrence for the degree of satisfaction with arguments related to the DPSIR parameter within the category of the 5-point Likert scale (ranging from level 1 - very low to level 5 - very high), including mean, standard deviation, and the consensus (CnS).
Chiba watershed was selected as a case study since its climate is representative of the Tunisian semi-arid context, and due to the high vulnerability of the existing groundwater systems with respect to human activities.

The hydrological simulations suggest a gradual decrease of 33% in the aquifer's natural recharge over the entire time period. The long-term average value of the annual recharge rate per sub-basin does not exceed 3 mm/year, keeping groundwater recharge levels in the basin relatively low. This observation is mainly attributed to climate change with CnS of 0.6 and over-exploitation of the water sources for irrigation purposes (CnS = 0.62), leading to aquifer depletion and degradation of groundwater-dependent ecosystems (CnS = 0.73). These results suggest that different management practices, such as more conservative water use (CnS = 0.6), long-term monitoring and Managed Aquifer Recharge (MAR) with wastewater (CnS = 0.76), can help rural residents to diversify their economies while preserving these water resources. However, although attempts of MAR have been undertaken, they remain insufficient to counter the pressure on the coastal aquifer, underlining the importance of preserving the fragile semi-arid landscape.

The proposed approach is applicable to other regions having similar climatic and socio-economic conditions. It also demonstrates that pure modeling solutions need to be coupled to the socio-economic approaches to be able to constitute a solid asset for sustainable water resources management of stressed hydro-systems.

 

Acknowledgments

This work is funded by National Funding Agencies from Germany,  Cyprus, Portugal, Spain, and Tunisia under the Partnership for Research and Innovation in the Mediterranean Area (PRIMA) and supported under Horizon 2020 by the European Union’s Framework for Research and Innovation.

How to cite: Chekirbane, A., Khemiri, K., Panagiotou, C., and Stefan, C.: An integrated hydrological modeling approach to assess the natural groundwater recharge trends in a Mediterranean coastal aquifer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5604, https://doi.org/10.5194/egusphere-egu24-5604, 2024.

EGU24-6984 | ECS | Posters on site | HS2.1.5

Westerly aridity in the western Tarim Basin driven by global cooling since the mid-Pleistocene transition 

Hongye Liu, Rui Zhang, Gaowen Dai, and Yansheng Gu

To explore the relationship between the global change, westerlies, and central Asian aridity, we report ~1.1 Ma local sedimentary environment changes according to high-resolution gamma ray (GR) from downhole logging, Grain size, magnetic susceptibility (MS), rubidium/strontium (Rb/Sr) ratios and total organic carbon (TOC) of an 800-m core (KT11) from the Kashgar region in the western Tarim Basin, arid zone of China. Four dominant sedimentation types, including lacustrine facies, delta facies, fluvial facies, and aeolian dunes, were identified through lithology and grain size frequency curves. The 1.1 Ma sedimentary successions experienced delta deposits with fluvial and aeolian deposits and lacustrines (1.1-0.6 Ma), alternating fluvial and aeolian facies with the occurrence of deltas and lacustrines (0.6-0.15 Ma), and aeolian facies interbedded with deltas and fluvial facies (0.15 Ma-present). Spectral analyses of the GR, MS, and Rb/Sr data reveal cycles with ~70 m, ~30 m and ~14 m wavelengths. These cycles represent ~100-kyr short-eccentricity, ~40-kyr obliquity and ~20-kyr precession frequencies, respectively and mainly are driven by orbitally forced climate change.

Stepwise drying sedimentary conditions and enhanced desertification indicated by increasing Rb/Sr ratios and proportion of aeolian sands, and decreasing TOC since the past 1.1 Ma, implied intensified westerlies, likely resulted from ice volume expansion and ongoing global cooling according to geological record comparison and simulations during the Last Glacial Maximum compared to preindustrial conditions, which may have controlled the expansion of the permanent deserts in inland Asia. These persistent drying trends and intensified westerly circulation in arid regions during glacial periods after the mid-Pleistocene Transition indicated by larger amplitudes of aeolian sand proportion than prior to 0.6 Ma are similar to those in the interior monsoonal Asia, where the larger-amplitude of median grain size indicated enhanced East Asian Winter monsoon intensity and drier glacials.

How to cite: Liu, H., Zhang, R., Dai, G., and Gu, Y.: Westerly aridity in the western Tarim Basin driven by global cooling since the mid-Pleistocene transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6984, https://doi.org/10.5194/egusphere-egu24-6984, 2024.

EGU24-7068 | ECS | Orals | HS2.1.5

Exploring Drought Patterns in the Headwaters of the Tarim River Basin through an Integrated Surface-Groundwater Drought Index 

Xiaohan Yu, Xiankui Zeng, Dongwei Gui, Dong Wang, and Jichun Wu

The Tarim River Basin, China's largest inland river, has been grappling with persistent drought challenges. Over 90% of its water resources originate from the headwaters, heavily relying on groundwater. Existing drought indices often compartmentalize considerations of surface water and groundwater variables. Consequently, there is a necessity for a comprehensive drought index that accounts for the interplay between surface water and groundwater. This study employs the Copula function to formulate the Standardized Precipitation Evapotranspiration Groundwater Index (SPEGI), incorporating surface water (precipitation minus evaporation) and groundwater (changes in total water storage observed by GRACE satellite minus changes in output from the VIC model). SPEGI is computed using a moving average approach across various time scales (1, 3, 6, 12 months) and is juxtaposed with traditional indices such as Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Soil Moisture Index (SSMI), and Standardized Groundwater Index (SGI). The findings underscore that SPEGI, grounded in the integrated consideration of surface and groundwater variables, provides a more comprehensive depiction of drought conditions in the study area. In contrast to traditional indices, SPEGI not only accounts for short-term precipitation and evaporation changes but also effectively reveals the characteristics of groundwater fluctuations. Additionally, by comparing SPEGI with NDVI data, the study delves into the desertification process in the region. The research discerns that SPEGI's assessment of drought resilience is more sensitive, manifesting an increasing trend in the desertification process with the enlargement of SPEGI's sliding window. Overall, this research contributes novel methodologies and empirical evidence for fostering sustainable water resource utilization and informing climate change adaptation decisions within the basin.

How to cite: Yu, X., Zeng, X., Gui, D., Wang, D., and Wu, J.: Exploring Drought Patterns in the Headwaters of the Tarim River Basin through an Integrated Surface-Groundwater Drought Index, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7068, https://doi.org/10.5194/egusphere-egu24-7068, 2024.

EGU24-7611 | ECS | Orals | HS2.1.5

Locating unsustainable water supplies for supporting ecological restoration in China's drylands 

Fengyu Fu, Shuai Wang, and Xutong Wu

China, with vast dryland areas, has undertaken extensive ecological restoration (ER) projects since the late 1970s. While ER is a crucial means against desertification and land degradation, it must be implemented in a water-sustainable manner to avoid exacerbating the carbon–water trade-off, especially in water-limited drylands. However, there is still limited research on accurately identifying water unsustainable ER regions in China's drylands. Here, we developed a water supply–demand indicator, namely, the water self-sufficiency (WSS), defined as the ratio of water availability to precipitation. With the use of remote sensing and multisource synthesis datasets combined with trend analysis and time series detection, we conducted a spatially explicit assessment of the water sustainability risk of ER in China's drylands over the period from 1987 to 2015. The results showed that 17.15% (6.36 Mha) of ER areas face a negative shift in the WSS (indicating a risk of unsustainability), mainly in Inner Mongolia, Shanxi, and Xinjiang provinces, driven by evapotranspiration. Moreover, 29.34% (10.9 Mha) of the total ER areas, whose area is roughly double that of water unsustainable ER areas, exhibit a potential water shortage with a significant WSS decline (-0.014 yr-1), concentrated in Inner Mongolia, Shaanxi, and Gansu provinces. The reliability of our findings was demonstrated through previous studies at the local scale and an analysis of soil moisture changes. Our findings offer precise identification of water unsustainable ER regions at the grid scale, providing more specific spatial guidance for ER implementation and adaptation in China's drylands.

How to cite: Fu, F., Wang, S., and Wu, X.: Locating unsustainable water supplies for supporting ecological restoration in China's drylands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7611, https://doi.org/10.5194/egusphere-egu24-7611, 2024.

EGU24-8825 | ECS | Orals | HS2.1.5

Assessing stream water scarcity and groundwater roles under global change in a Mediterranean watershed: the Onyar River basin (NE Catalonia, Spain) 

Paula Gabriela Cordoba Ariza, Ramon J. Batalla, Sergi Sabater, and Josep Mas-Pla

Mediterranean basins face significant water scarcity which requires examining long-term data to evaluate their trends in water availability and quality and assess management options. In this presentation, we explore the historical streamflow changes, the influencing climatic —streamflow, precipitation, temperature, and evapotranspiration (PET and AET)— and land-use factors, and the evolution of surface water quality in the Onyar River (Inner Catalan basins, NE Spain; 295 km2) during the last decades (1960-2020).

Results highlight a consistent decline in streamflow, most pronounced over the last two decades, accompanied by an increase in PET, and a probable decrease in groundwater recharge. These changes co-occurred with higher concentrations of river water ammonium and nitrate. We attribute these patterns to changes in land use such as afforestation and intensive fertilization, as well as increased groundwater withdrawal, particularly during irrigation seasons. Additional factors include growing urban water demand and the discharges of treated wastewater back into the river system. Evaluation of the relationship between groundwater and surface water using end-member mixing analysis of hydrochemical data points out an interesting scale-dependence behaviour: groundwater baseflow from alluvial formations was relevant in the smallest subbasins, whereas regional groundwater flow involving deeper aquifers could significantly contribute to stream discharge in the lowest zones of the basin. Since water balance alteration in the future climate scenarios will reduce the contribution of the headwater flow as well as groundwater storage and baseflow generation, reclaimed wastewater shows up as a relevant source to maintain stream runoff, yet its quality is low and might not be properly diluted by rainfall originated runoff.

These observations provide a comprehensive overview of the declining water quantity and quality in the Onyar River network, attributing these trends to an interplay of climatic and anthropogenic factors. They urge for integrated water resources management strategies to mitigate the implications of these environmental changes, such as protecting baseflow generating areas as well as controlling reclaimed wastewater quality.

Funding: G. Córdoba-Ariza acknowledges funding from Secretariat of Universities and Research from Generalitat de Catalunya and European Social Fund for her FI fellowship (2022 FI_B1 00105). 

How to cite: Cordoba Ariza, P. G., Batalla, R. J., Sabater, S., and Mas-Pla, J.: Assessing stream water scarcity and groundwater roles under global change in a Mediterranean watershed: the Onyar River basin (NE Catalonia, Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8825, https://doi.org/10.5194/egusphere-egu24-8825, 2024.

Intermittent rivers and ephemeral streams represent half of the global river network and span all climates. The intermittent rivers and ephemeral streams is a short-hand term for all flowing water that ceases to flow or that dries up completely at some point in time and/or space They are more frequent in arid and semi-arid areas but are also present in temperate, tropical humid, boreal, and alpine areas, where they are mainly located in headwaters. Their abundance is increasing due to climate change and water withdrawals for human activities.

The objective of this study is to represent the spatio-temporal dynamics of flow intermittence at the reach level in river of the seven sub-catchments of the Maures massif (between 1.5 km² and 70 km²).

First, two hydrological continuous models of varying complexities are performed: GR6J (lumped and conceptual), and SMASH (spatially distributed and conceptual) in terms of temporal calibration/validation, by dissociating dry and wet years, to asses the models’ability to simulate observed drying event over time. The metrics are based on daily flow records observed in the 7 catchments since 1968 to 2023.

In the second part, a regionalization method is tested on the spatially distributed model (SMASH). The HDA-PR approach (Hybrid Data Assimilation and Parameter Regionalization) incorporating learnable regionalization mappings, based on multivariate regressions is used. This approach consist to search for a transfer function that quantitatively relates physical descriptors to conceptual model parameters from multi-gauge discharge in order to produce a regional model.

Flow condition observed from multiple data sources (daily flow time series from gauging stations, phototrap installed along the river network taking daily pictures from 2021-04-01 to 2023-31-12, daily conductivity measurements series from 2021-01-01) are used to validate the ability of the regional model to simulate flow intermittence (prediction of dry events) at river section level.

The distributed modelling approach, with a high-resolution conceptual hydrological modeling at 0.250 km² and coupled with Hybrid Data Assimilation and Parameter Regionalization descriptors shows results highlight the effectiveness of HDA-PR surpassing the performance of a uniform regionalization method with lumped model parameters. However, the results on smallest catchments area are lowest.

The study shows the interest of using daily photos which are a good indication of the hydrogical state of the streams to obtain intermittence data and increasing the spatial coverage of observations in order to validate regional model.

How to cite: Folton, N., De Fournas, T., Colléoni, F., and Tolsa, M.: Modelling the intermittence of watercourses in the small French Mediterranean catchments of the Maures massif (Réal Collobrier ) with the SMASH platform (Spatially distributed Modelling and ASsimilation for Hydrology) , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9681, https://doi.org/10.5194/egusphere-egu24-9681, 2024.

EGU24-9899 | Orals | HS2.1.5

60,000 years of hydrologic connectivity on the Australian dryland margins: the case of the Willandra Lakes World Heritage Area 

Kathryn Fitzsimmons, Markus Fischer, Colin Murray-Wallace, Edward Rhodes, Tobias Lauer, Maike Nowatzki, Kanchan Mishra, and Nicola Stern

Australia is big, flat, old and arid: it is the driest inhabited continent on Earth. The catastrophic flooding of recent years has demonstrated not only the potential for extreme conditions at both ends of the hydroclimatic scale, but also how little we understand of the interplay between climatic, hydrological, and surface-process mechanisms affecting this part of the world. We know still less about long-term hydrological dynamics, particularly for the dry inland where water resources are scarce and land surfaces are susceptible to erosion, requiring careful management.

Records of past hydrological variability can help inform us about changing hydroclimate states and their impact on the land surface. The Willandra lakes system, located on the desert margins of southeastern Australia, is one of the few dryland areas which preserves long-term sedimentary records of hydrologic change. The headwaters of these lakes lie in the temperate highlands hundreds of kilometres to the east; as a result, lake filling and drying reflects the interaction between rainfall in the watershed and hydrologic connectivity across the catchment and between the lakes. Environmental change in the Willandra is recorded in the sediments of the lake shoreline dunes, preserved as semi-continuous deposition of different lake facies over 60,000 years.

Here we investigate long-term hydrologic connectivity across the Willandra lakes and their catchment. Our approach uses a novel integration of lake-level reconstruction based on lunette sedimentology, stratigraphy and luminescence geochronology, with hydrologic and palaeoclimatic modelling of key event time slices over the last 60 ky. We characterize the land-surface response to various hydroclimate states, so improving our understanding of dryland atmosphere-hydrosphere interactions.

How to cite: Fitzsimmons, K., Fischer, M., Murray-Wallace, C., Rhodes, E., Lauer, T., Nowatzki, M., Mishra, K., and Stern, N.: 60,000 years of hydrologic connectivity on the Australian dryland margins: the case of the Willandra Lakes World Heritage Area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9899, https://doi.org/10.5194/egusphere-egu24-9899, 2024.

EGU24-10078 | ECS | Orals | HS2.1.5 | Highlight

Wheat irrigation in Marrakech conditions: A Simulation Study using SALTMED 

El Houcine El Moussaoui, Aicha Moumni, Said Khabba, and Abderrahman Lahrouni

In Morocco, agriculture accounts for 80-90% of water resources. Available data show that the performance of current irrigation systems remains low to medium, with water losses at plots ranging from 30 to 40%, divided between percolation and evaporation. Gravity irrigation is almost total in the study area, resulting in significant percolation losses. In principle, this percolation contributes mainly to the recharge of the aquifer.

The purpose of this study was to evaluate, by simulation, the impact of irrigation techniques on wheat yield and growth using the generic agro-environmental model SALTMED under the climatic and soil conditions of zone R3, which is an irrigation area located in the region of Sidi Rahal about 40 km east of the city of Marrakech in the plain of Haouz. We started the study by calibrating the model based on two parameters: photosynthetic efficiency and harvest index. After calibration, we compared different irrigation techniques implemented in the model (surface irrigation, sprinkler irrigation, and drip irrigation). Simulation results showed that the drip irrigation technique is the most economical, exhibiting the lowest losses attributed to percolation and soil evaporation. Notably, percolation, a significant contributor to groundwater recharge, measured approximately 255.5 mm/season. In addition, the irrigation practice in the study area appears to be overestimated during the observed season and could be reduced by half, according to SALTMED. When the irrigation dose is halved, the simulated yield (grain and total biomass) decreases by only 1.33%.

How to cite: El Moussaoui, E. H., Moumni, A., Khabba, S., and Lahrouni, A.: Wheat irrigation in Marrakech conditions: A Simulation Study using SALTMED, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10078, https://doi.org/10.5194/egusphere-egu24-10078, 2024.

EGU24-10387 | ECS | Orals | HS2.1.5

Nitrogen modeling and performance of Multi-Soil-Layering (MSL)bioreactor treating domestic wastewater in rural community 

Sofyan Sbahi, Naaila Ouazzani, Abdessamed Hejjaj, Abderrahman Lahrouni, and Laila Mandi

The multi-soil-layering (MSL) bioreactor has been considered in the latest research as an
innovative bioreactor for reducing the level of pollutants in wastewater. The efficiency of the
MSL bioreactor towards nitrogen pollution is due to the mineralization of organic nitrogen in
aerobic layers to ammonia, and reactivity of ammonia nitrogen with soil and gravel by its
adsorption into soil layers followed by nitrification and denitrification processes when the
alternating phases of oxygenated/anoxic conditions occurs in the filter. In this study, we have
examined the performance of the MSL bioreactor at different hydraulic loading rates (HLRs)
and predicted the removal rate of nitrogen. To improve the prediction accuracy of the models,
the feature selection technique was performed before conducting the Neural Network model.
The results showed a significant removal (p <0.05) efficiency for five-day biochemical
oxygen demand (BOD 5,  86%), ammonium (NH 4 + , 83%), nitrates (NO 3 − , 81%), total kjeldahl
nitrogen (TKN, 84%), total nitrogen (TN, 84%), orthophosphates (PO 4 3− , 91%), and total
coliforms (TC, 1.62 Log units). However, no significant change was observed in the nitrite
(NO 2 − ) concentration as it is an intermediate nitrogen form. The MSL treatment efficiency
demonstrated a good capacity even when HLR increased from 250 to 4000 L/m 2 /day,
respectively (e.g., between 64% and 86% for BOD 5 ). The HLR was selected as the most
significant (p < 0.05) input variable that contribute to predict the removal rates of nitrogen.
The developed models predict accurately the output variables (R 2  > 0.93) and could help to
investigate the MSL behavior.

How to cite: Sbahi, S., Ouazzani, N., Hejjaj, A., Lahrouni, A., and Mandi, L.: Nitrogen modeling and performance of Multi-Soil-Layering (MSL)bioreactor treating domestic wastewater in rural community, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10387, https://doi.org/10.5194/egusphere-egu24-10387, 2024.

EGU24-11799 | ECS | Orals | HS2.1.5 | Highlight

Exploring the mechanisms controlling dryland hydroclimate in past 'warmer worlds' 

Monika Markowska, Hubert B. Vonhof, Huw S. Groucutt, Michael D. Petraglia, Denis Scholz, Michael Weber, Axel Gerdes, Richard Albert, Julian Schroeder, Yves S. Krüger, Anna Nele Meckler, Jens Fiebig, Matthew Stewart, Nicole Boivin, Samuel L. Nicholson, Paul S. Breeze, Nicholas Drake, Julia C. Tindall, Alan M. Haywood, and Gerald Haug

Drylands cover almost half of Earth’s land surfaces, supporting ~30% of the world’s population. The International Panel on Climate Change predicts increasing aridification and expansion of drylands over the course of this century. As we approach new climate states without societal precedent, Earth’s geological past may offer the best tool to understand hydroclimate change under previously, allowing us to elucidate responses to external forcing. Paleo-records from previously warm and high-CO2 periods in Earth’s past, such as the mid-Pliocene (~3 Ma), point towards higher humidity in many dryland regions. 

Here, we examine desert speleothems from the hyper-arid desert in central Arabia, part of the largest near-continuous chain of drylands in the world, stretching from north-western Africa to the northern China, to elucidate substantial and recurrent humid phases over the past 8 million years. Independent quantitative paleo-thermometers suggest that mean annual air temperatures in central Arabia were approximately between 1 to 5 °C warmer than today. The analyses of the isotopic composition (δ18O and δ2H) of speleothem fluid inclusion waters, representing ‘fossil rainwater’, reveal an aridification trend in Arabia from the Late Miocene to Late Pleistocene during Earth’s transition from a largely ‘ice-free’ northern hemisphere to an ‘ice-age’ world. Together, our data provide evidence for recurrent discrete wetter intervals during past warmer periods, such as the Pliocene. Data-model comparisons allow us to assess the agreement between our paleoclimate data and climate model output using the HadCM3 isotope-enabled model simulations during past ‘warmer worlds’ – namely the mid-Piacenzian warm period (3.264 to 3.025 Ma). To assess the hydroclimate response to external forcing, we examine model output from a series of sensitivity experiments with different orbital configurations allowing us to postulate the mechanisms responsible for the occurrence of humid episodes in the Arabian desert, with potential implications for other dryland regions at similar latitudes. Together, our approach unveils the long-term controls on Arabian hydroclimate and may provide crucial insights into the future variability.

How to cite: Markowska, M., Vonhof, H. B., Groucutt, H. S., Petraglia, M. D., Scholz, D., Weber, M., Gerdes, A., Albert, R., Schroeder, J., Krüger, Y. S., Meckler, A. N., Fiebig, J., Stewart, M., Boivin, N., Nicholson, S. L., Breeze, P. S., Drake, N., Tindall, J. C., Haywood, A. M., and Haug, G.: Exploring the mechanisms controlling dryland hydroclimate in past 'warmer worlds', EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11799, https://doi.org/10.5194/egusphere-egu24-11799, 2024.

EGU24-12194 | ECS | Orals | HS2.1.5

High resolution surface soil moisture microwave products: intercomparison and evaluation over Spain 

Nadia Ouaadi, Lionel Jarlan, Michel Le Page, Mehrez Zribi, Giovani Paolini, Bouchra Ait Hssaine, Maria Jose Escorihuela, Pascal Fanise, Olivier Merlin, Nicolas Baghdadi, and Aaron Boone

Surface soil moisture (SSM) products at high spatial resolution are increasingly available, either from the disaggregation of coarse-resolution products such as SMAP and SMOS, or from high-resolution radar data such as Sentinel-1. In contrast to coarse resolution products, there is a lack of intercomparison studies of high spatial resolution products, which are more relevant for applications requiring the plot scale. In this context, the objective of this work is the evaluation and intercomparison of three high spatial resolution SSM products on a large database of in situ SSM measurements collected on two different sites in the Urgell region (Catalonia, Spain) in 2021. The satellite SSM products are: i) SSMTheia product at the plot scale derived from a synergy of Sentinel-1 and Sentinel-2 using a machine learning algorithm; ii) SSMρ product at 14 m resolution derived from the Sentinel-1 backscattering coefficient and interferometric coherence using a brute-force algorithm; and iii) SSMSMAP20m product at 20 m resolution obtained from the disaggregation of SMAP using Sentinel-3 and Sentinel-2 data. Evaluation of the three products over the entire database showed that SSMTheia and SSMρ yielded a better estimate than SSMSMAP20m, and SSMρ is slightly better than SSMTheia. In particular, the correlation coefficient is higher than 0.4 for 72%, 40% and 27% of the fields using SSMρ, SSMTheia and SSMSMAP20m, respectively. The lower performance of SSMTheia compared to SSMρ is due to the saturation of SSMTheia at 0.3 m3/m3. The time series analysis shows that SSMSMAP20m is able to detect rainfall events occurring at large scale while irrigation at the plot scale are not caught. This is explained by the use of Sentinel-2 reflectances, which are not linked to surface water status, for the disaggregation of Sentinel-3 land surface temperature. The approach can therefore be improved by using high spatial and temporal resolution thermal data in the perspective of new missions such as TRISHNA and LSTM. Finally, the results show that although reasonable estimates are obtained for annual crops using SSMTheia and SSMρ, poor performance is observed for trees, suggesting the need for better representation of canopy components for tree crops in SSM inversion approaches.

How to cite: Ouaadi, N., Jarlan, L., Le Page, M., Zribi, M., Paolini, G., Ait Hssaine, B., Escorihuela, M. J., Fanise, P., Merlin, O., Baghdadi, N., and Boone, A.: High resolution surface soil moisture microwave products: intercomparison and evaluation over Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12194, https://doi.org/10.5194/egusphere-egu24-12194, 2024.

    The Yellow River (YR) is 5464 km long and the cradle of Chinese civilization. It is also well known for being the most sediment-laden river and having the largest vertical drop over its course. Although the YR accounts for only 3% of China’s water resources, it irrigates 13% of its cropland. Exceptional historical documents have recorded frequent occurrence of YR flooding events that resulted in huge losses of lives and property.
    The earliest observational record of YR runoff, beginning in 1919 at the Shanxian gauge station, is too short to study centennial-scale variability. Since the start of the Anthropocene in the 1960s, frequent human activities have resulted in large deviation between observed streamflow. The reconstruction of annual historical natural runoff of the YR is necessary to quantify the amount of anthropogenic YR water consumption in recent decades. Tree rings, with the merits of accurate dating and annual resolution, have been widely used in runoff reconstruction worldwide. In this study, 31 moisture-sensitive tree-ring width chronologies, including 860 trees and 1707 cores, collected within the upper-middle YR basins were used to reconstruct natural runoff for the middle YR course over the period 1492–2013 CE.
    The reconstruction provides a record of natural YR runoff variability prior to large-scale human interference. Most of the extreme high/low runoff events in the reconstruction can be verified with historical documents. The lowest YR flow since 1492 CE occurred during 1926–1932 CE and the YR runoff in 1781 is the highest. These two extreme values could be regarded as a benchmark for future judicious planning of water allocation. Since the late 1980s, observed YR runoff has fallen out of its natural range of variability, and there was even no water flow for several months each year in the lower YR course during 1995 to 1998. Especially concerning was that the inherent 11-year and 24-year cycles of YR became disordered following the severe drought event in late 1920s, and eventually disappeared after the 1960s.
    Year-to-year variability in YR water consumption by human activities (WCHA) was quantified, which showed good association between crop yields and acreage in Ningxia and Inner Mongolia irrigation regions. Meanwhile, WCHA was strongly negatively correlated with sediment load at Toudaoguai and Shanxian stations, which led to a 58% reduction of sediment load in Toudaoguai (upper reach) and 29% in Shanxian (middle reach). 
    If human activities continue to intensify, future YR runoff will be further reduced, and this will negatively impact agriculture, human lives, and socioeconomic development in the middle and lower basins of the YR. To reduce the risk of recurring cutoff of streamflow in the YR lower basin, water should be allocated judiciously. Our reconstructed YR natural runoff series are important for future YR water resource management. In addition, our results also provide an important model of how to distinguish and quantify anthropogenic influence from natural variability in global change studies.

How to cite: Liu, Y.: Changes and attribution of natural runoff in the Yellow River over the past 500 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13979, https://doi.org/10.5194/egusphere-egu24-13979, 2024.

EGU24-14057 | ECS | Posters on site | HS2.1.5

Turbulent fluxes at kilometer scale determined by optical-microwave scintillometry in a heterogeneous oasis cropland of the Heihe River Basin 

Feinan Xu, Weizhen Wang, Chunlin Huang, Jiaojiao Feng, and Jiemin Wang

Observations of kilometer-scale turbulent fluxes of sensible (H) and latent heat (LE) are required for the validation of flux estimate algorithms from satellite remote-sensing data and the development of parameterization schemes in the hydro-meteorological models. Since 2019, two sets of Optical and Microwave scintillometer (OMS) systems have been operated in the Heihe River Basin of northwestern China, one on an alpine grassland of upper reaches, another on an oasis cropland of middle reaches, to measure both the areal H and LE. Combined with the observations of eddy-covariance (EC) and meteorological tower systems in both sites, an improved procedure for OMS data processing is proposed. The newly proposed procedure especially improves the preprocessing of raw scintillation data, properly uses the current probably better Lüdi et al. (2005) method in deriving meteorological structure parameters, and chooses the coefficients of similarity functions by Kooijmans and Hartogensis (2016) in calculating fluxes. Evaluated with the results of rather homogeneous grassland, the area-averaged H and LE over the heterogeneous oasis are then determined. Estimates of H and LE agree reasonably well with those obtained from EC in most cases. However, the most interesting is that LE over the oasis during the early crop growing stages is clearly larger than that of EC; while both agree well during the longer crop grown periods. Footprint analysis shows that, compared with EC, the OMS has clearly larger source area that contains a slight area of orchard and shelterbelts distributed near the light path, leading to larger LE during the early stages of crop growth. The area-averaged evapotranspiration (ET) over the oasis is then analyzed more acceptably, which varies from 3 to 5 mm day-1 depending on meteorological conditions during the 39 days of the crop growing period. These results are used to validate the Penman-Menteith-Leuning Version 2 (PML-V2) scheme.

How to cite: Xu, F., Wang, W., Huang, C., Feng, J., and Wang, J.: Turbulent fluxes at kilometer scale determined by optical-microwave scintillometry in a heterogeneous oasis cropland of the Heihe River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14057, https://doi.org/10.5194/egusphere-egu24-14057, 2024.

    Recurrent droughts in history, especially climatic aridity since the mid-20th century have aroused great social anxiety about the water resources in the Chinese Loess Plateau (CLP). Given lacking of extended instrumental-like records, new precipitation reconstructions in the CLP are badly needed for objectively evaluating the current precipitation situation, understanding the spatial-temporal differences, and serving for predicting the future. Here we present a tree-ring-based 248-year regional precipitation reconstruction (P8–7) in the Heichashan Mountain, which can significantly represent the past dry-wet variations in the eastern CLP (ECLP). P8–7 explains 48.72% of the instrumental record, reveals a wetting trend since the early 2000s and attains the second wettest period over the past 248 years in 2014–2020 AD. The 1920s/2010s is recorded as the driest/wettest decade. 1910–1932 AD ranks as the driest period over the past centuries. The 19th century is comparatively wet while the 20th century is dry. Precipitation in the ECLP and western CLP (WCLP) has changed synchronously over most time of the past two centuries. However, regional difference exists in the 1890s–1920s when a gradually drying occurred in the ECLP, while not evident in the WCLP, although the 1920s megadrought occurred in the CLP. Moreover, the 20th-century drying in the ECLP begins in the 1950s, later than the WCLP. It reveals that P8–7 variability is primarily influenced by the Asian Summer Monsoon and related large-scale circulations. The seismic phase shift of the contemporaneous Northern Hemispheric temperature may also be responsible for the 1920s megadrought.

How to cite: Cai, Q. and Liu, Y.: Hydroclimatic characteristics on the Chinese Loess Plateau over the past 250 years inferred from tree rings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14189, https://doi.org/10.5194/egusphere-egu24-14189, 2024.

EGU24-16291 | ECS | Orals | HS2.1.5

A New Perspective on Agricultural Drought Periods: A Mediterranean Semi-Arid Context 

Kaoutar Oukaddour, Michel Le Page, and Younes Fakir

Extreme weather events have an increasing repercussions on ecosystems in recent years. By comprehending how vegetation responds to climatic extremes, their effects may be mitigated. In a semi-arid Mediterranean region, this study examines the temporal connections of the main triggers of agricultural drought, low precipitation, vegetation growth, thermal stress, and soil water deficit. Drought periods and their characteristics were determined using a revised run theory approach. The Pearson correlations across various spatial scales revealed a moderate to low degree of concordance among the drought indices. This discrepancy can be attributed to the geographical heterogeneity and climatic variations observed among the agrosystems within the basin.

The cross-correlation analysis demonstrated the cascading impacts resulting from reduced precipitation. During drought events, the significant connection between precipitation deficits and vegetation persists for at least one month across most index pairs. This suggests that agricultural drought occurrences can be temporally linked through the selected drought indices. The study unveiled short-, mid-, and long-term effects of precipitation deficiencies on soil moisture, vegetation, and temperature. As anticipated, variables like soil moisture and surface temperature, being more instantaneous, exhibited no lag in response to precipitation. Notably, vegetation anomalies at the monthly time step displayed a two-month lag, indicating a preceding impact of vegetation on precipitation.

Employing the run theory to identify drought events and stages with different thresholds revealed substantial variability in drought characteristics namely the duration, the magnitude magnitude, and the intensity. This variability was notably influenced by the selection of both normality and drought thresholds.

How to cite: Oukaddour, K., Le Page, M., and Fakir, Y.: A New Perspective on Agricultural Drought Periods: A Mediterranean Semi-Arid Context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16291, https://doi.org/10.5194/egusphere-egu24-16291, 2024.

EGU24-17049 | ECS | Orals | HS2.1.5

Potential of the Photochemical Reflectance Index in Understanding Photoinhibition and Improving Irrigation Water Efficiency in the Mediterranean Zone 

Zoubair Rafi, Saïd Khabba, Valérie Le Dantec, Patrick Mordelet, Salah Er-Raki, Abdelghani Chehbouni, and Olivier Merlin

Morocco's semi-arid region faces challenges due to limited water resources, necessitating efficient irrigation practices for sustainable agriculture. Precision agriculture, coupled with advanced technologies like the Photochemical Reflectance Index (PRI), holds great potential for optimizing irrigation water usage and enhancing crop productivity in this environment. This abstract provides a comprehensive overview of integrating precision agriculture techniques, PRI, and Net Radiation (Rn) to improve irrigation water efficiency and maximize crop productivity in Morocco's semi-arid zone. The study presents and analyzes an experimental investigation of the PRI signal in a winter wheat field throughout an agricultural season to comprehend its dependence on agro-environmental parameters such as global radiation (Rg) and Rn. Rn directly impacts the energy absorbed by plants, a crucial factor for photosynthesis. Elevated Rn levels generally increase energy availability for photosynthetic processes, resulting in higher chlorophyll fluorescence and PRI values. However, excessive Rn can lead to photoinhibition, damaging the photosynthetic apparatus and reducing photosynthetic efficiency. Understanding the interplay between net radiation, PRI, and photoinhibition is crucial for optimizing agricultural practices. Monitoring and managing net radiation levels allow farmers to ensure that the energy available for photosynthesis remains within the optimal range, minimizing the risk of photoinhibition while maximizing crop productivity. Additionally, the daily water stress index based on PRI (PRIj), developed independently of structural effects related to leaf area index (LAI), showed a coefficient of determination (R2) of 0.74 between PRIj and Rn. This reflects the extent of excessive light stress experienced by the wheat field throughout the experiment. In conclusion, the integration of precision agriculture techniques, specifically PRI, offers a promising approach to enhance irrigation water efficiency in Morocco's semi-arid zone. By employing this innovative tool, farmers can optimize water usage, reduce environmental impacts, and ensure the long-term sustainability of agriculture.

How to cite: Rafi, Z., Khabba, S., Le Dantec, V., Mordelet, P., Er-Raki, S., Chehbouni, A., and Merlin, O.: Potential of the Photochemical Reflectance Index in Understanding Photoinhibition and Improving Irrigation Water Efficiency in the Mediterranean Zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17049, https://doi.org/10.5194/egusphere-egu24-17049, 2024.

EGU24-17321 | ECS | Orals | HS2.1.5

Quantifying Olive Tree Evapotranspiration in Semi-Arid Regions through Remote Sensing-Based SEBAL Model: Validation with Optical-Microwave Scintillometer 

Hamza Barguache, Jamal Ezzahar, Mohamed Hakim Kharrou, Said Khabba, Jamal Elfarkh, Abderrahim Laalyej, Salah Er-Raki, and Abdelghani Chehbouni

Accurately assessing sensible (H) and latent (LE) heat fluxes, along with evapotranspiration, is crucial for comprehending the energy balance at the biosphere-atmosphere interface and enhancing agricultural water management. Although the eddy covariance (EC) method is commonly employed for these measurements, it has limitations in providing spatial representativeness beyond a few hundred meters. Addressing this challenge, optical-microwave scintillometers (OMS) have emerged as a valuable tool, directly measuring kilometer-scale H and LE fluxes. These measurements serve to validate satellite remote sensing products and model simulations, such as the Surface Energy Balance Algorithm for Land (SEBAL). In this study, OMS measurements were utilized to assess the fluxes simulated by the SEBAL model at the Agdal olive orchard near Marrakech city. The results revealed that SEBAL's estimated sensible heat fluxes were 3% higher than those measured by OMS, while latent heat fluxes were approximately 15% lower. Based on these findings, we infer that OMS can effectively validate satellite-driven surface energy balance models, thereby supporting agricultural water management.

How to cite: Barguache, H., Ezzahar, J., Kharrou, M. H., Khabba, S., Elfarkh, J., Laalyej, A., Er-Raki, S., and Chehbouni, A.: Quantifying Olive Tree Evapotranspiration in Semi-Arid Regions through Remote Sensing-Based SEBAL Model: Validation with Optical-Microwave Scintillometer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17321, https://doi.org/10.5194/egusphere-egu24-17321, 2024.

EGU24-17560 | ECS | Posters virtual | HS2.1.5

Estimation of Irrigation Water Demand in the Southern Mediterranean Region through Explicit Integration of Irrigation Processes in a Land Surface Model: A Case Study of the Tensift Catchment (Morocco). 

Ahmed Moucha, Lionel Jarlan, Pére Quintana-Segui, Anais Barella-Ortiz, Michel Le Page, Simon Munier, Adnane Chakir, Aaron Boone, Fathallah Sghrer, Jean-christophe Calvet, and Lahoucine Hanich

The utilization of water by various socio-economic sectors has made this resource highly sought after, especially in arid to semi-arid zones where water is already scarce and limited. In this context, effective management of this resource proves to be crucial. Our study aims to: evaluate the performance of the new irrigation module in ISBA, quantify the water balance, and assess the impact of climate change and anthropogenic factors on this resource by the horizon of 2041-2060, utilizing high-resolution futuristic forcings from the study (Moucha et al., 2021). To assess the ISBA model with its new irrigation module, we initially compared observed and predicted fluxes with and without activation of the irrigation module. Subsequently, we compared irrigation water inputs at the ORMVAH-defined irrigated perimeters within the Tensift basin. The results of this evaluation showed that the predictions of latent heat flux (LE) considering all available stations in the basin shifted from -60 W/m² for the model without irrigation to -15 W/m². This indicates that the integration of the new irrigation system into ISBA significantly improves the predictions of latent heat flux (LE) over the period 2004-2014 compared to the regular model. Considering the irrigated perimeters, the study results demonstrated that the model with the integration of the irrigation module was capable of replicating the overall magnitude and seasonality of water quantities provided by ORMVAH despite a positive bias. Exploration of the water balance at the Tensift basin level revealed the ISBA model's ability, equipped with its irrigation module, to describe complex relationships among precipitation, irrigation, evapotranspiration, and drainage. Finally, the assessment of the impact of climate change and vegetation cover for the period 2041-2060, utilizing high-resolution SAFRAN forcings projected to the same horizon (Moucha et al., 2021), revealed an increase in irrigation water needs. These results are of paramount importance in the context of sustainable water resource management in arid and semi-arid regions.

How to cite: Moucha, A., Jarlan, L., Quintana-Segui, P., Barella-Ortiz, A., Le Page, M., Munier, S., Chakir, A., Boone, A., Sghrer, F., Calvet, J., and Hanich, L.: Estimation of Irrigation Water Demand in the Southern Mediterranean Region through Explicit Integration of Irrigation Processes in a Land Surface Model: A Case Study of the Tensift Catchment (Morocco)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17560, https://doi.org/10.5194/egusphere-egu24-17560, 2024.

EGU24-17649 | ECS | Orals | HS2.1.5

Comprehensive Analysis of Hydrological Dynamics and Uncertainties in the Moroccan High Atlas: A Focus on Seasonal Precipitation, Runoff, and Flood Events 

Myriam Benkirane, Abdelhakim Amazirh, El Houssaine Bouras, Adnane Chakir, and Said Khabba

The Mediterranean regions, particularly the Moroccan High Atlas, is exposed to natural risks associated with the hydrological cycle, notably intense precipitation events that trigger sudden floods. This research delves into the subtleties of hydrological dynamics in the High Atlas watersheds, specifically in the Zat watershed, to comprehend the seasonality of precipitation and runoff and elucidate the origins of floods.

The results reveal a strong correlation between observed and simulated hydrographs, affirming the model's capability to capture complex hydrological processes. Evaluation metrics, particularly the Nash coefficient, demonstrate a robust model performance during the calibration phase, ranging from 61.9% to 90%. This attests to the model's ability to reproduce the dynamic nature of hydrological systems in the Moroccan High Atlas.

It is noteworthy that the study identifies the snowmelt process as a significant factor of uncertainty in runoff flooding parameters. The complexities associated with snowmelt, especially in the context of spring precipitation, emerge as a crucial factor influencing uncertainties in the simulated results. This finding underscores the importance of accurately representing snowmelt dynamics in hydrological simulations for regions prone to natural risks.

Moreover, the integration of Probability Distribution Functions and Monte Carlo simulations, coupled with rigorous evaluation metrics, enhances our understanding of calibration parameter uncertainties and validates the model's performance. The identified influence of snowmelt on runoff flooding parameters provides crucial insights for future model improvements and the development of effective mitigation strategies in regions vulnerable to natural risks. This research contributes to advancing hydrological modeling practices in complex terrain.

 

Keywords: Seasonality, Rainfall-Runoff, Floods, Calibration, Monte Carlo simulation, Parameter Uncertainty, Hydrological Modeling, Snowmelt Dynamics, Natural Risks.

How to cite: Benkirane, M., Amazirh, A., Bouras, E. H., Chakir, A., and Khabba, S.: Comprehensive Analysis of Hydrological Dynamics and Uncertainties in the Moroccan High Atlas: A Focus on Seasonal Precipitation, Runoff, and Flood Events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17649, https://doi.org/10.5194/egusphere-egu24-17649, 2024.

The Mediterranean area is recognized as a hotspot for climate change challenges, with noticeable patterns of rising temperatures and dryness. Olive agroecosystems are particularly affected by the increasing aridity and global climatic changes. Despite being a symbol of the Mediterranean and traditionally grown using rainfed agricultural practices, olive growers have to adapt to cope with higher temperatures, drought, and more frequent severe weather incidents, necessitating their attention and adaptation (Fraga et al., 2020). Moreover, crop production in Morocco heavily relies on irrigation because rainfed cropping has limited productivity (Taheripour et al., 2020). The olive sector is of great importance in Morocco, and there is an urgent need to implement sustainable water management practices. This includes water-saving strategies such as regulated and sustained deficit irrigation (RDI and SDI) to sustain olive production and strengthen the sector's resilience to climate change and water scarcity. These strategies primarily differ in terms of their irrigation timing and the quantity of water applied (Ibba et al., 2023). This study aims to evaluate the effect of two deficit irrigation strategies on productive parameters of the Menara olive cultivar, to serve as a tool for operational irrigation water management and appraise the adaptive responses of this cultivar under conditions of induced drought stress. In pursuit of this aim, an experiment was carried out in an olive orchard over two consecutive years (2021 and 2022), comparing four treatments of regulated deficit irrigation (RDI): T1 (SP 100- NP 70% ETc), T2 (SP 100- NP 60% ETc), T3 (SP 80- NP 70% ETc), T4 (SP 80- NP 60% ETc) and two treatments of sustained deficit irrigation (SDI): T5 (70% ETc) and T6 (60% ETc), with fully irrigated trees T0 (100% ETc). The findings showed that controlled water stress, as applied through regulated deficit irrigation (RDI), did not exert a severe impact on the flowering traits and yield of the Menara olive cultivar. Notably, the RDI strategy, particularly under T4 treatment, allowed for the reduction of supplied water by 20% in sensitive periods (SP) flowering and from the beginning of oil synthesis to harvest and by 40% in the normal period (NP)during pit hardening, respectively, without compromising fruit yield. However, the SDI strategy, characterized by restricted water availability, which reduced total water application under T5 and T6 treatments by 30% and 40% throughout the entire season, led to a decline in the fruit yield by about 50% and resulted in the most significant drop in water productivity, ranging from 19% to 33% compared to the control T0. Furthermore, the findings underscored the adaptability of responses to water stress and elucidated the consequential impact of each irrigation strategy on the performance of Menara olive trees across successive years, particularly the importance of regulated deficit irrigation as a water management strategy and the need to consider its implication on flowering traits and crop yield over successive growing seasons to establish the enduring adaptability of this locally cultivated olive cultivar.

How to cite: Ibba, K., Er-Raki, S., Bouizgaren, A., and Hadria, R.: Sustainable Water Management for Menara Olive Cultivar: Unveiling the Potential of Regulated and Sustained Deficit Irrigation Strategies in Morocco, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17808, https://doi.org/10.5194/egusphere-egu24-17808, 2024.

EGU24-17983 | ECS | Orals | HS2.1.5

Comparison of C-band radar and infrared thermal data for monitoring corn field in semi-arid area. 

Abdelhafid Elallaoui, Pierre-Louis Frison, Saïd Khabba, and Lionel Jarlan

In semi-arid Mediterranean regions, the scarcity and limitations of water resources pose major challenges. These invaluable resources are threatened by various factors such as climate change, population growth, urban expansion, and agricultural intensification. Specifically, agriculture, which consumes approximately 85% of the water in the semi-arid zone of the South Mediterranean region, directly contributes to the depletion of groundwater. To promote rational irrigation management, it becomes imperative to monitor the water status of crops. Remote sensing is a valuable technique allowing for monitoring crop fields in different parts of the electromagnetic spectrum giving complementary information about crop parameters. The main objective of this study is to assess the potential of radar and Infrared Thermal data for monitoring the water status of crops in semi-arid regions. In this context, a radar system was installed in Morocco, in the Chichaoua region, consisting of 6 C-band antennas mounted on a 20-meter tower. These antennas are directed towards a maize field. This system allowed for radar data acquisition in three different polarizations (VV, VH, HH) with a 15-minute time-step over the time period extending from September to December 2021. Additionally, the system is complemented by continuous acquisitions from a Thermal Infrared Radiometer (IRT) at 30-minute intervals. These data are further supplemented by in-situ measurements characterizing crop parameters (state of the cover, soil moisture, evapotranspiration and meteorological variables). The study initially focused on analyzing the diurnal cycle of radar temporal coherence. The results indicated that coherence was highly sensitive to wind-induced movements of scatterers, with minimal coherence when wind speed was highest in the late afternoon. Moreover, coherence was also responsive to vegetation activity, particularly its water content, as the morning coherence drop coincided with the onset of plant activity. Subsequently, the study examined the potential of the relative difference between surface vegetation temperature and air temperature to monitor the water status of crops. The results showed that during a period of imposed water stress, the amplitude of this difference increased. These results open perspectives for monitoring the water status of crops using radar and thermal observations with a high revisit frequency.

How to cite: Elallaoui, A., Frison, P.-L., Khabba, S., and Jarlan, L.: Comparison of C-band radar and infrared thermal data for monitoring corn field in semi-arid area., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17983, https://doi.org/10.5194/egusphere-egu24-17983, 2024.

EGU24-18201 | ECS | Orals | HS2.1.5

Analyzing Tree Degradation in the Haouz Plain through Remote Sensing: Assessing the Impact of Drought and Spatial Extent 

Youness Ablila, Abdelhakim Amazirh, Saïd Khabba, El Houssaine Bouras, Mohamed hakim Kharrou, Salah Er-Raki, and Abdelghani Chehbouni

Trees characterized by persistent foliage, like olive trees, serve as indispensable assets in arid and semi-arid regions, exemplified by the Haouz plain in central Morocco. The decline in water resources for irrigation, attributed to climate change and excessive underground water extraction, has led to significant degradation of tree orchards in recent years. Employing remote sensing data, we conducted a spatial analysis of tree degradation from 2013 to 2022 using the supervised classification method. Subsequently, a drying speed index (DS) was computed based on the Normalized Difference Vegetation Index (NDVI) derived from Landsat-8 data, specifically focusing on the identified trees. This DS was then correlated with the Standardized Precipitation Index (SPIn) to elucidate the connection between tree degradation and drought, as indicated by precipitation deficit. The findings reveal a discernible declining trend in trees, with an average decrease in NDVI by 0.02 between 2019 and 2022 compared to the reference period (2013-2019). This decline has impacted an extensive area of 37,550 hectares. Furthermore, the outcomes derived from the analysis of SPI profiles depict a prolonged period of dryness, particularly extreme drought in the past four years, characterized by SPI values consistently below -2. Notably, a high correlation coefficient (R) of -0.87 and -0.88 was observed between DS and SPI9 and SPI12 respectively, emphasizing the strong linkage between drying speed and the duration and intensity of drought. These findings emphasize the reliability of NDVI as an effective tool for precise classification of tree land cover. Additionally, they underscore the significant influence of drought on the degradation of trees in the Haouz plain.

How to cite: Ablila, Y., Amazirh, A., Khabba, S., Bouras, E. H., Kharrou, M. H., Er-Raki, S., and Chehbouni, A.: Analyzing Tree Degradation in the Haouz Plain through Remote Sensing: Assessing the Impact of Drought and Spatial Extent, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18201, https://doi.org/10.5194/egusphere-egu24-18201, 2024.

EGU24-18295 | ECS | Posters on site | HS2.1.5

The relevance of Rossby wave breaking for precipitation in the world’s arid regions 

Andries Jan De Vries, Moshe Armon, Klaus Klingmüller, Raphael Portmann, Matthias Röthlisberger, and Daniela I.V. Domeisen

Precipitation-related extremes in drylands expose more than a third of the world population living in these regions to drought and flooding. While weather systems generating precipitation in humid low- and high-latitude regions are widely studied, our understanding of the atmospheric processes governing precipitation formation in arid regions remains fragmented at best. Regional studies have suggested a key role of the extratropical forcing for precipitation in arid regions. Here we quantify the contribution of Rossby wave breaking for precipitation formation in arid regions worldwide. We combine potential vorticity streamers and cutoffs identified from ERA5 as indicators of Rossby wave breaking and use four different precipitation products based on satellite-based estimates, station data, and reanalysis. Rossby wave breaking is significantly associated with up to 80% of annual precipitation and up to 90% of daily precipitation extremes in arid regions equatorward and downstream of the midlatitude storm tracks. The relevance of wave breaking for precipitation increases with increasing land aridity. Contributions of wave breaking to precipitation dominate in the poleward and westward portions of subtropical arid regions during the cool season. In these regions, climate projections for the future suggest a strong precipitation decline, while projections of precipitation extremes are highly uncertain due to the influence of the atmospheric circulation. Thus, our findings emphasize the importance of Rossby wave breaking as an atmospheric driver of precipitation in arid regions with large implications for understanding projections and constraining uncertainties of future precipitation changes in arid regions that are disproportionally at risk of freshwater shortages and flood hazards.

How to cite: De Vries, A. J., Armon, M., Klingmüller, K., Portmann, R., Röthlisberger, M., and Domeisen, D. I. V.: The relevance of Rossby wave breaking for precipitation in the world’s arid regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18295, https://doi.org/10.5194/egusphere-egu24-18295, 2024.

EGU24-19012 | Orals | HS2.1.5

Decoupling the Influence of Climate Change and Natural Variability on the Middle Eastern Shamal Wind  

Hamza Kunhu Bangalth, Jerry Raj, Udaya Bhaskar Gunturu, and Georgiy Stenchikov

The Middle Eastern Shamal, a prominent north-northwesterly wind, plays a crucial role in the Arabian Peninsula's climate and environment. Originating from the interaction between a semipermanent anticyclone over northern Saudi Arabia and a cyclone over southern Iran, it influences regional climate. The Shamal is essential in transporting dust and pollutants from the Tigris-Euphrates to the Persian Gulf, affecting air quality, health, and travel. Its potential as a renewable energy source also highlights its importance for the region's future energy strategies.

However, understanding the time series of the Shamal wind is a complex task, owing to the intertwined influences of natural climate variability and human-induced climate change. While climate change is a critical factor, natural variability driven by internal climate modes like the Atlantic Multidecadal Oscillation (AMO), Pacific Decadal Oscillation (PDO), and North Atlantic Oscillation (NAO) also significantly influences these winds. These oscillations, operating over multidecadal scales, alongside the overarching trend of climate change, form a complex web affecting the regional climate. 

This study addresses the challenge of decoupling the impacts of climate change and natural climate variability on the Shamal wind. Our analysis employs Empirical Mode Decomposition (EMD), a relatively new approach that allows us to decouple the influence of various internal climate modes from that of anthropogenic climate change. This method surpasses traditional techniques by avoiding assumptions of linearity and stationarity. The study utilizes ERA5 reanalysis data to analyze summer and winter Shamal winds.

Preliminary findings indicate that internal climate modes like the AMO are equally significant as climate change in influencing Shamal wind in the past. This insight is crucial for more accurate projections and predictions of future Shamal wind behavior, benefiting the Middle East's environmental management, health, and renewable energy sectors.

How to cite: Bangalth, H. K., Raj, J., Gunturu, U. B., and Stenchikov, G.: Decoupling the Influence of Climate Change and Natural Variability on the Middle Eastern Shamal Wind , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19012, https://doi.org/10.5194/egusphere-egu24-19012, 2024.

EGU24-19172 | Orals | HS2.1.5

Assessing the possibilities of Sentinel products for qualifying and quantifying soil water status of agricultural systems in southern France  

Claude Doussan, Urcel Kalenga Tshingomba, Nicolas Baghdadi, Fabrice Flamain, Arnaud Chapelet, Guillaume Pouget, and Dominique Courault

Water management poses a pervasive challenge in southern France, exacerbated by increasing summer droughts linked to global warming. Water use during spring and summer increases and gets more variable in term of quantity used for crops. Agricultural water use is highly influenced by the diversity in irrigation practices and technics (sprinkler irrigation, drip irrigation, flooding, etc.) ; and can lead to tensions among water users. It is thus essential to estimate field water use at basin scale, as well as crop water status, in order to further optimize water delivered for irrigation. Advances in remote sensing, particularly with Sentinel 1 (S1) and 2 (S2) data, facilitated the development of soil moisture products (SMP) with improved spatial and temporal resolution to characterize soil water in agricultural plots. These SMP products are accessible through the Theia French public platform and suitable for main crops, with NDVI below 0.75 or surfaces with moderate roughness. These specifications can be met for a variety of crop conditions in the south of France. Yet, the validity of the SMP products under various agricultural plot conditions, considering slope, orientation, roughness, and soil moisture, remains to be assessed over extended time periods. From another point of view, such SMP products do not presently apply to orchards plots, which are however, an essential but overlooked component of water use in irrigation and deserve further examination with S1 and S2 data. The objective of our study is twofold: (i) to test SMP products for field crops in different settings and among years, (ii) to preliminary test if S1 data, combined to S2 data, may be linked to soil moisture in orchard plots. Results reveal for (i) that differences can appear between SMP products and soil moisture in various monitored plots, primarily due to variability within farming systems. Beyond a specific slope and vegetation threshold, the correlation does not improve significantly. For (ii), in orchards plots, using a time smoothing of data, S1 VV-retrodiffusion data and NDVI from S2 seem to correlate with soil moisture measurements, with an RMSE < 0.05 cm3/cm3 and enable detection of irrigation events. This study shows that S1 and S2 data are valuable in estimating soil moisture of agricultural plots, giving however some limits in their use, and gives some hope in their further use for orchards water management.

How to cite: Doussan, C., Kalenga Tshingomba, U., Baghdadi, N., Flamain, F., Chapelet, A., Pouget, G., and Courault, D.: Assessing the possibilities of Sentinel products for qualifying and quantifying soil water status of agricultural systems in southern France , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19172, https://doi.org/10.5194/egusphere-egu24-19172, 2024.

EGU24-19511 | Posters on site | HS2.1.5

OurMED PRIMA-funded Project: Sustainable Water Storage and Distribution in the Mediterranean 

Seifeddine Jomaa, Amir Rouhani, Maria Schade, J. Jaime Gómez-Hernández, Antonio Moya Diez, Maroua Oueslati, Anis Guelmami, George P. Karatzas, Emmanouil A Varouchakis, Maria Giovanna Tanda, Pier Paolo Roggero, Salvatore Manfreda, Nashat Hamidan, Yousra Madani, Patrícia Lourenço, Slaheddine Khlifi, Irem Daloglu Cetinkaya, Michael Rode, and Nadim K Copty

The Mediterranean Region is a unique mosaic of different cultures and climates that shape its peoples, natural environment, and species diversity. However, rapid population growth, urbanisation and increased anthropogenic pressures are threatening water quantity, quality, and related ecosystem services. Known as a climate change hotspot, the Mediterranean region is increasingly experiencing intensifying droughts, diminished river flows, and drier soils making water management even more challenging. This situation calls for an urgent need for water management to shift from a mono-sectoral water management approach based on trade-offs, to more balanced multisectoral management that considers the requirement of all stakeholders. This means that sustainable water management requires ensuring that water is stored and shared fairly across all sectors at the basin scale.

The research project OurMED (https://www.ourmed.eu/) is part of the Partnership for Research and Innovation in the Mediterranean Area (PRIMA) Programme supported by the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 2222. The project was launched in June 2023 and will continue for three years with a grant of 4.4 million euros to develop a holistic water storage and distribution approach tightly integrated into ecosystem services at the river basin scale.

OurMED builds on the multidisciplinary skills of 15 consortium Partners and comprises universities, NGOs, research centres and SMEs from ten countries with complementary expertise in hydrology, hydrogeology, agronomy, climate change, social sciences, remote sensing, digital twins, ecology, and environmental sciences, among others, making it a truly interdisciplinary project. OurMED includes eight distinct demo sites, representing diverse water-related ecosystem properties of the Mediterranean landscape. These include the catchment areas of Bode (Germany), Agia (Crete, Greece), Konya (Turkey), Mujib (Jordan), Medjerda (Tunisia), Sebou (Morocco), Arborea (Sardinia, Italy), and Júcar (Spain). The Mediterranean basin, as a whole, is considered as an additional regional demo site to ensure replicability and reproducibility of proposed solutions at larger scales. 

OurMED vision combines not only technologically-advanced monitoring, smart modelling and optimization capabilities, but also provides data fusion and integrated digital twin technologies to make optimized solutions readily available for decision making. OurMED concept and its implementation to the different demo sites will be presented and discussed.

How to cite: Jomaa, S., Rouhani, A., Schade, M., Gómez-Hernández, J. J., Moya Diez, A., Oueslati, M., Guelmami, A., Karatzas, G. P., Varouchakis, E. A., Tanda, M. G., Roggero, P. P., Manfreda, S., Hamidan, N., Madani, Y., Lourenço, P., Khlifi, S., Daloglu Cetinkaya, I., Rode, M., and Copty, N. K.: OurMED PRIMA-funded Project: Sustainable Water Storage and Distribution in the Mediterranean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19511, https://doi.org/10.5194/egusphere-egu24-19511, 2024.

EGU24-20067 | ECS | Orals | HS2.1.5

Impact Of Ocean Layer Thickness on The Simulation Of African Easterly Waves in High-Resolution Coupled General Circulation Model Simulations 

Jerry Raj, Elsa Mohino Harris, Maria Belen Rodriguez de Fonseca, and Teresa Losada Doval

African easterly waves (AEWs) play a crucial role in the high-frequency variability of West African Monsoon (WAM) precipitation. AEWs are linked to more than 40% of the total Mesoscale Convective Systems (MCSs) in the region and these MCSs contribute approximately 80% of the total annual rainfall over the Sahel. Moreover, around 60% of all Atlantic hurricanes, including 80% of major hurricanes, have their genesis associated with AEWs. The simulation of AEWs poses challenges for General Circulation Models (GCMs), for instance, coarse-resolution models in CMIP5 cannot simulate distinct northern and southern AEW tracks. Additionally, accurately simulating rainfall over West Africa proves to be a challenge for these models due to the involvement of multiscale processes and the influence of complex topography and coastlines. 

The present study investigates the impact of ocean layer thickness on the simulation of African easterly waves (AEWs) using a high-resolution coupled General Circulation Model (GCM). The study employs high-resolution global simulations conducted using the climate model ICON as part of the next Generation Earth System Modeling Systems (nextGEMS) project. Two experiments, each spanning 30 years with a horizontal resolution of 10 km, are conducted. These experiments vary in terms of the thickness of the layers in the upper 20m of the ocean. In one experiment, the upper 20m ocean layers have a thickness of 2m, whereas in the other, it is 10m. The representation of two types of AEWs with periods of 3-5 days and 6-9 days are analyzed in the simulations. There is a notable disparity in the representation of African easterly waves (AEWs) between these two experiments. The simulation with thicker ocean layers exhibits less intense wave activity over the Sahel and equatorial Atlantic for 3-5 day AEWs which is evident in the eddy kinetic energy field. This corresponds to diminished convection and negative precipitation anomalies for 3-5 day AEWs compared to the 2m upper ocean layer thickness simulation. In the case of 6-9 day AEWs, the simulation with thicker ocean layers exhibits intensification of wave activity over northern West Africa.

How to cite: Raj, J., Mohino Harris, E., Rodriguez de Fonseca, M. B., and Losada Doval, T.: Impact Of Ocean Layer Thickness on The Simulation Of African Easterly Waves in High-Resolution Coupled General Circulation Model Simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20067, https://doi.org/10.5194/egusphere-egu24-20067, 2024.

EGU24-20356 | ECS | Posters on site | HS2.1.5

Seasonal Water Turbidity Dynamics in Arid Central Asia: A Case Study of Lake Balkhash, Kazakhstan, Under Changing Environmental Conditions 

Kanchan Mishra, Kathryn E. Fitzsimmons, and Bharat Choudhary

Lake Balkhash, one of the largest inland lakes in Central Asia, plays a pivotal role in providing water and ecosystem services to approximately 3 million people. However, like many water bodies in dryland regions worldwide, Lake Balkhash's hydrology has been significantly affected by climate change and land cover and land-use shifts driven by population growth and water-intensive economic activities. To manage these vital water resources effectively, monitoring the health of water bodies is essential for effective water resource management, security, and environmental conservation. Turbidity, a water quality indicator, measures the water clarity and represents a broader environmental change, allowing us to assess the water body's health and the extent of anthropogenic impact on the entire catchment. It is a measure of water clarity and serves as a crucial indicator of water health, as it represents the primary mechanism for transporting pollutants, algae, and suspended particles.

The present study investigates the temporal and spatial variability of turbidity in Lake Balkhash. We utilize the normalized difference turbidity index (NDTI) with Landsat satellite data spanning from 1991 to 2022 to map turbidity. We consider various climatic and anthropogenic factors, including precipitation, temperature, wind speed and direction, and water levels in and around the lake.

Our findings reveal an overall declining turbidity trend over interannual and seasonal timescales. The results provide a significant negative correlation between turbidity, temperature, and water levels at both temporal scales. However, no straightforward relationship emerges between turbidity and precipitation or wind variables. Specifically, during spring and summer, turbidity exhibits a strong association with temperature and water levels, while in the fall season, water levels are more closely correlated with turbidity. These results underscore the substantial impact of rising temperatures and fluctuations in water levels on the turbidity dynamics of Lake Balkhash. These findings highlight that the warming climate and alterations in lake hydrology pose significant risks to water quality, indicating that monitoring water health alone may not suffice to mitigate the impacts of climate change and human activities.  

How to cite: Mishra, K., Fitzsimmons, K. E., and Choudhary, B.: Seasonal Water Turbidity Dynamics in Arid Central Asia: A Case Study of Lake Balkhash, Kazakhstan, Under Changing Environmental Conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20356, https://doi.org/10.5194/egusphere-egu24-20356, 2024.

EGU24-20398 | Posters on site | HS2.1.5

Analysis of operational droughts in an alpine Mediterranean basin using a conjunctive use model of surface and groundwater resources 

Juan-de-Dios Gómez-Gómez, Antonio Collados-Lara, David Pulido-Velázquez, Leticia Baena-Ruiz, Jose-David Hidalgo-Hidalgo, Víctor Cruz-Gallegos, Patricia Jimeno-Sáez, Javier Senent-Aparicio, Fernando Delgado-Ramos, and Francisco Rueda-Valdivia

Extreme events, and particularly, droughts are a main concern in Mediterranean basins that will be increased in the future due to climate change (CC), according to the forecasting for the region made by researchers. A novel integrated approach is proposed to analyze operational droughts and their propagation in future CC scenarios at a basin scale. This approach has been applied to the Alto Genil basin (Granada, Spain), an alpine Mediterranean basin with the singularity of having an important snow component in its precipitation regime. The Standardized Precipitation Index (SPI) methodology has been applied to the variable Demand Satisfaction Index (DSI) at a monthly scale to evaluate operational droughts. A conjunctive use model of surface and groundwater resources developed with the code Aquatool has been used to obtain historical and future DSI monthly series. It is an integrated management model that includes all water demands, water resources (surface, groundwater, and their interaction), regulation and distribution infrastructures in the Alto Genil system. The Vega de Granada aquifer is a key element of the water supply system such for agricultural needs as for guarantee the urban supply to the city of Granada. Groundwater flow in this important aquifer has been simulated with a distributed approach defined by an eigenvalue model to integrate it in the management model, and in order to obtain a more detailed analysis of its future evolution. The proposed methodology consists of the sequential application of the following steps: (1) generation of future scenarios for the period 2071-2100 to obtain series of precipitation (P) and temperature (T); (2) application of a chain of models: a rainfall-runoff model (Témez) coupled with a snowmelt model to obtain runoff (Q) series in subbasins of Alto Genil basin, a crop water requirement model (Cropwat) to get agricultural demand series, and an integrated management model (Aquatool) to get historical and future series of DSI; and (3) analysis of operational droughts comparing historical and future series of the Standardized Demand Satisfaction Index (SDSI), which is the application of the SPI methodology to the variable DSI. A cluster analysis of variables P and Q has been made in order to define homogeneous hydroclimatic areas by aggregation of subbasins. It will allow us to perform an analyses of the heterogeneity in  the propagation of droughts.

Aknowledments: This research has been partially supported by the projects: STAGES-IPCC (TED2021-130744B-C21), SIGLO-PRO (PID2021-128021OB-I00), from the Spanish Ministry of Science, Innovation and Universities, RISRYEARTH (Recovery funds), and “Programa Investigo” (NextGenerationEU).

How to cite: Gómez-Gómez, J.-D., Collados-Lara, A., Pulido-Velázquez, D., Baena-Ruiz, L., Hidalgo-Hidalgo, J.-D., Cruz-Gallegos, V., Jimeno-Sáez, P., Senent-Aparicio, J., Delgado-Ramos, F., and Rueda-Valdivia, F.: Analysis of operational droughts in an alpine Mediterranean basin using a conjunctive use model of surface and groundwater resources, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20398, https://doi.org/10.5194/egusphere-egu24-20398, 2024.

EGU24-20616 | Orals | HS2.1.5

Integrating Multi-Sensor and Multi-Platform Technologies for Enhanced Assessment of Spectral Indices and Phenological Dynamics in a Seasonal Tropical Dry Forest 

Magna Moura, Rodolfo Nobrega, Anne Verhoef, Josicleda Galvíncio, Rodrigo Miranda, Bruna Alberton, Desiree Marques, Cloves Santos, Bruno Nascimento, Maria Maraiza Pereira, and Patricia Morellato

The Seasonal Tropical Dry Forest (STDF) known as Caatinga occupies approx. 10% of the Brazilian territory. Its vegetation exhibits rapid phenological responses to rainfall resulting in corresponding increases in gross primary productivity and biomass production. Determining the timing of the start and end of the growing season is very important to ecosystem studies and to precisely quantify the carbon balance. Satellite-derived vegetation indices have been widely used to capture the vegetation dynamics in response to fluctuating environmental conditions. However, the spatial and temporal resolution of these indices cannot capture fine vegetation features and phenology metrics in a highly biodiverse and heterogeneous environment such as the Caatinga. On the other hand, phenocameras have been successfully used for this particular purpose for tropical and dry ecosystems. Complementarily, proximal spectral response sensors (SRS) have been used to allow computation of vegetation indices as phenology proxies. Due to their ability to capture high spatial resolution imagery, Unmanned Aerial Systems (UAS) or drones, can deliver an excellent spatial and a very good temporal resolution for diverse detailed vegetation studies. In this context, the objective of this study was to verify whether multi-sensor and multi-platform technologies provide an enhanced assessment of spectral indices and phenological dynamics of the Caatinga. The field campaign occurred in a pristine area of caatinga vegetation, located at the Legal Reserve of Caatinga, Embrapa Semi-Arid, Petrolina, Brazil. Indices for detecting phenology dynamics were obtained using multi-spectral cameras installed on unmanned aerial vehicles (UAV), field spectral response sensors (SRS), phenocameras (digital RGB cameras) and MODIS satellite data (visible and near infrared) from 2020 to 2023. Environmental driving data were measured via instrumentation installed on a flux tower. Standard statistical measures, including correlation coefficients were employed to verify the relationship observed on Normalized Difference Vegetation Index (NDVI), Photochemical Reflectance Index (PRI), and Green Chromatic Coordinate (Gcc) determined by different sensors and platforms. We observed a substantial and fast increase in Gcc, NDVI and PRI immediately after rainfall events. The sensitivity of NDVI and PRI to changes in vegetation can vary depending on factors such as vegetation greenness, overall plant health, and stress responses according to the environmental conditions of the study area. Particularly during the dry season, indices derived from higher spatial resolution sensors consistently showed lower NDVI values compared to those obtained from proximal spectral response sensors (SRS) and drones. Our observations indicate that the representation of vegetation captured by satellites and drones aligns well with the data obtained from phenocamera and proximal SRS platforms. The combination of high temporal resolution provided by SRS and phenocameras resulted in improved and more reliable indices that will be indispensable for evaluating the response of Caatinga vegetation to current and future conditions.

Funding: This study was supported by the São Paulo Research Foundation-FAPESP (grants ##2015/50488-5, #2019/11835-2; #2021/10639-5; #2022/07735-5), the Coordination for the Improvement of Higher Education Personnel - CAPES (Finance Code 001), the National Council for Scientific and Technological Development - CNPq (306563/2022-3).

How to cite: Moura, M., Nobrega, R., Verhoef, A., Galvíncio, J., Miranda, R., Alberton, B., Marques, D., Santos, C., Nascimento, B., Pereira, M. M., and Morellato, P.: Integrating Multi-Sensor and Multi-Platform Technologies for Enhanced Assessment of Spectral Indices and Phenological Dynamics in a Seasonal Tropical Dry Forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20616, https://doi.org/10.5194/egusphere-egu24-20616, 2024.

EGU24-20999 | ECS | Orals | HS2.1.5

Soil and rock water dynamics in a semiarid karst savanna undergoing woody plant encroachment

Pedro Leite, Bradford Wilcox, Daniella Rempe, and Logan Schmidt

EGU24-544 | ECS | PICO | HS7.9

Land-Atmosphere Interactions over North West Himalaya 

Ashish Navale and Karthikeyan Lanka

Precipitation can originate from evaporated water over oceans and land in remote locations or from local terrestrial sources. The precipitation due to these local sources is called recycled precipitation. Recycled precipitation has been used extensively to study land-atmosphere interaction and has shown to be helpful when studying the relationship between atmospheric or terrestrial variables and precipitation. Mountainous areas such as the Himalaya, Tibetan Plateau, Alps, Andes, and the Rocky Mountains are a hotspot for high local recycling and land-atmosphere interaction. The North West Himalaya (NWH) has drawn attention recently to the issue of climate change due to the region's drastically reduced rainfall and rapidly rising temperature over the past century. Climate change also affects the large number of processes involved in land-atmosphere interaction. The complex topography and heterogeneous climate of NWH makes it challenging to understand the land-atmosphere interaction in this region. In this study, we use an Eulerian water tagging method implemented into the Weather Research and Forecasting (WRF) model to study land-atmosphere interaction in NWH. This method is considered one of the most accurate techniques to quantify recycled precipitation. We simulated summer (June, July, August, and September) and winter (December, January, February, and March) precipitation in the NWH for twenty years from 2001 to 2020.

Results show that, due to availability of more thermal energy the summer experienced more recycling than winter. The western disturbances in winter and southwest monsoon during summer contributes to the locally evapotranspirated moisture and affects the recycling ratio of NWH. However, the irregular western disturbances lead to high variability in the winter recycling ratio. Our analysis shows a strong diurnal cycle of recycling ratio in NWH which peaks in the afternoon. The trend analysis from twenty years although did not show any significant trend in recycled precipitation, other variables affecting land-atmosphere interaction such as soil moisture, latent heat and 2-meter air temperature showed significant trends in NWH. We also studied land-atmosphere interaction over two contrasting regions: the foothills of Himalaya and the high-elevation region. The recycled precipitation was high in the lower elevations during summer and at higher elevations during winter. We also found higher land-atmosphere interaction during summer at higher elevations and during both summer and winter at foothills. However, due to continuous precipitation along the foothills of NWH, a brief shift in soil moisture to a wet regime is expected during monsoon which reduces the influence of soil moisture on the atmosphere leading to low land-atmosphere interaction. However, good land-atmosphere interaction exists throughout the summer in the higher Himalaya, where this change in regime is not apparent.

How to cite: Navale, A. and Lanka, K.: Land-Atmosphere Interactions over North West Himalaya, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-544, https://doi.org/10.5194/egusphere-egu24-544, 2024.

EGU24-1391 | ECS | PICO | HS7.9 | Highlight

US Corn Belt enhances regional precipitation recycling 

Zhe Zhang, Cenlin He, Fei Chen, Gonzalo Miguez-Macho, Changhai Liu, and Roy Rasmussen

Precipitation recycling, characterized by the contribution of local evapotranspiration (ET) to local precipitation, is a critical component of the
regional water cycle. In the US Corn Belt, vast croplands and irrigation applications have markedly modified surface energy and water balance, which in
turn modulates precipitation recycling. However, previous studies often neglected the complex hydrological and crop physiological processes at land surface with an oversimplified assumption. In this study, we aim to understand the precipitation recycling in the US Corn Belt with explicit shallow groundwater dynamics, crop growth, and irrigation processes in the WRF model, with the water vapor tracer (WVT) capability to track ET directly from croplands. We found that the croplands exhibit a strong cooling effect on air temperatures and increasing summer precipitation. The increase in precipitation can be attributed to enhanced precipitation recycling, ranging from 11 to 22%, and much stronger seasonality during summer growing seasons. Such cooling effect and contribution to precipitation recycling is more significant in a drought year compared to normal and wet years, depending on both large-scale moisture advection and local moisture source. Our results have important implications to modeling ecohydrology and agricultural management in the Earth system, understanding precipitation recycling in the entire water cycle and designing sustainable water resource governance.

How to cite: Zhang, Z., He, C., Chen, F., Miguez-Macho, G., Liu, C., and Rasmussen, R.: US Corn Belt enhances regional precipitation recycling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1391, https://doi.org/10.5194/egusphere-egu24-1391, 2024.

EGU24-1607 | PICO | HS7.9

Impacts of irrigation on local, regional, and remote climate 

Min-Hui Lo and Hung-Chen Chen

Irrigation significantly impacts climate across local, regional, and remote scales. This critical agricultural practice transforms local land surface properties, leading to increased soil moisture and consequent changes in the surface energy balance. Such changes typically result in cooler local surface temperatures due to higher latent heat flux from enhanced evapotranspiration. Beyond its local effects, irrigation substantially influences regional climate and hydrology. The introduction of additional moisture into the atmosphere from irrigated areas can alter regional atmospheric dynamics, potentially affecting cloud formation and modifying precipitation patterns. While irrigation practices can be beneficial for agriculture, they may also have unintended consequences on regional climates, including altering rainfall distribution. Furthermore, the implications of irrigation can extend to remote climate systems. Irrigation-induced redistribution of heat and moisture can influence atmospheric circulation patterns and atmospheric wave dynamics, impacting hydroclimate far beyond the immediate area of irrigation. These remote effects underscore the interconnected nature of global climate systems and the extensive impact of localized human activities like irrigation.

In sum, irrigation exerts a cascading influence on climate systems at various scales. It reshapes local surface conditions, drives changes in regional atmospheric processes, and has potential implications for remote climates. Comprehending these complex interactions is crucial for formulating sustainable irrigation strategies and addressing the broader climatic impacts of such practices.

How to cite: Lo, M.-H. and Chen, H.-C.: Impacts of irrigation on local, regional, and remote climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1607, https://doi.org/10.5194/egusphere-egu24-1607, 2024.

Land use and cover change (LULCC) is an important climatic forcing. However, it is challenging to quantify the responses of local precipitation to LULCC forcing due to the complex interaction between the land surface and atmosphere. The ecologically fragile Loess Plateau (LP) of China has experienced evident changes in precipitation patterns, but the underlying mechanism remains unclear. The biophysical effects of LULCC on precipitation and the water vapor balance in the LP region were quantified based on the LULCC forcing experiments from the sixth phase of the Coupled Model Intercomparison Project (CMIP6). We found that the selected 11 Earth system models (ESMs) reproduced the general spatial pattern of annual precipitation on the LP region, with slight overestimation in the southern LP. The multimodel ensemble (MME) average showed that global LULCC forcing exerted a negative effect on long-term mean precipitation in this region during the period of 1850-2014. In particular, it decreased evidently during the period from 1850 to 1960, with a reduction of approximately 14.1 mm. However, a positive effect was detected for the period of 1961-2014, with an increase of 6.4 mm in annual precipitation. This is largely related to the intensified water vapor transport in the southern boundary and westerly belt of the LP region resulting from global LULCC forcing. Furthermore, water vapor balance analysis showed that global LULCC forcing resulted in a divergence in water vapor transport within the LP region, leading to a net water vapor output to the surrounding regions. These findings highlight the importance of considering global LULCC, in addition to regional LULCC, in studying regional climate change and associated impacts on the water cycle.

How to cite: Qiu, L.: Importance of biophysical forcing of global land cover to local precipitation and water vapor budget on the Loess Plateau of China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5039, https://doi.org/10.5194/egusphere-egu24-5039, 2024.

EGU24-6236 | ECS | PICO | HS7.9

Regional impacts of simulated irrigation in the IPSL climate model. 

Pierre Tiengou, Agnès Ducharne, Frédérique Cheruy, Yann Meurdesoif, and Pedro Arboleda

The recent years have shown increasing interest and effort to include simulation of irrigation in Earth System Models to better account for the effects of this anthropogenic process on climate. We present here preliminary results about the impacts of simulated irrigation on surface-atmosphere interactions using LMDZ and ORCHIDEE, the atmosphere and land surface components of the IPSL Climate Model. The DYNAMICO-LMDZ configuration, coupling the physics of LMDZ to the recent icosahedral dynamical core DYNAMICO, is run as a Limited Area Model (LAM) to conduct a regional study over North-Eastern Spain. The simulation domain encompasses the Ebro valley where the LIAISE (Land-surface Interactions with the Atmosphere In Semi-Arid Environment) field campaign was conducted in 2021. This campaign was specifically designed to provide better understanding of the local and regional impacts of irrigation and the surface heterogeneities it creates. A new representation of irrigation, based on a soil moisture deficit approach, has recently been developed in ORCHIDEE and simulations are run with and without it to assess the impacts of simulated irrigation in the model. Direct effects at the land-surface interface (soil moisture, turbulent fluxes, temperature) are studied first, before focusing on the structure of the boundary layer and precipitations. Field observations from the campaign are used to evaluate the model, and the outputs will also be compared to higher-resolution simulations that have been conducted using the Meso-NH model in the context of the LIAISE project. The impacts of irrigation will be studied using various resolutions of the LAM from 10 to 50km, to better understand the scales at which land-surface coupling processes can be explicitly resolved by the dynamics of the model, and assess the importance of parametrizating these processes.

How to cite: Tiengou, P., Ducharne, A., Cheruy, F., Meurdesoif, Y., and Arboleda, P.: Regional impacts of simulated irrigation in the IPSL climate model., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6236, https://doi.org/10.5194/egusphere-egu24-6236, 2024.

EGU24-8049 | ECS | PICO | HS7.9 | Highlight

Global terrestrial moisture recycling in Shared Socioeconomic Pathways 

Arie Staal, Pim Meijer, Maganizo Kruger Nyasulu, Obbe Tuinenburg, and Stefan Dekker

The global water cycle has undergone considerable changes since pre-industrial times due to global climate change and land-use changes. These drivers will almost certainly continue to change during the course of this century. However, where, how, and to which extent terrestrial moisture recycling will change as a result remains unclear.

Mutually consistent scenarios of climate change and land-use changes for the 21st century are provided by the Shared Socioeconomic Pathways (SSPs). The SSPs provide a framework of five different narratives involving varying degrees of challenges associated with mitigation or adaptation. From each narrative follow different implications for emissions, energy, and land use. The SSPs serve as the conceptual framework behind the sixth generation of the Coupled Model Intercomparison Project, CMIP6.

Terrestrial moisture recycling is often assessed using atmospheric moisture tracking models. An example is UTrack, a Lagrangian model to track moisture through three-dimensional space. Here we present a new forward-tracking version of UTrack that is forced by output of a CMIP6 model to study how terrestrial moisture recycling may change across the globe until the end of the  21st century in a range of SSPs, from mild to severe: SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. For this forcing, we chose the Norwegian Earth System Model version 2, or NorESM2. It has a temporal resolution of one day and a spatial resolution of 1.25° × 0.9375° at eight pressure levels.

We find that across the 21st century, the global terrestrial moisture recycling ratio decreases with the severity of the Shared Socioeconomic Pathways (SSPs). We calculate a decrease in global terrestrial precipitation recycling by 2.1% with every degree of global warming. Because the SSPs represent internally consistent scenarios of both global warming and global land cover changes, it is hard to distinguish the relative contributions of these two, but the evidence points at a major influence of global warming on moisture recycling.

We find spatial differences in trends in recycling ratios, but which are broadly consistent among SSPs. If a change in precipitation (either drying or wetting) coincides with an increase in terrestrial precipitation recycling ratio, we call it land-dominated. We call the change in precipitation ocean-dominated if it coincides with a decrease in terrestrial precipitation recycling ratio. Land dominance tends to occur in regions with already large terrestrial precipitation recycling ratios, mainly interior South America (land-dominated drying) and eastern Asia (land-dominated wetting). Land-dominated drying may also happen in eastern Europe, in central America and in subtropical sub-Saharan Africa. Ocean-dominance, mainly in the form of wetting, is found primarily in the high northern latitudes and in central Africa.

We also simulated the changes in basin recycling for the 27 major river basins of the world, confirming the overall tendency of decreasing recycling with severity of the SSP, as well as its spatial variations.

How to cite: Staal, A., Meijer, P., Nyasulu, M. K., Tuinenburg, O., and Dekker, S.: Global terrestrial moisture recycling in Shared Socioeconomic Pathways, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8049, https://doi.org/10.5194/egusphere-egu24-8049, 2024.

The ecological restoration benefits in the Yellow River Basin (YRB) are significant, characterized by increased vegetation and reduced sediment. However, afforestation has resulted in elevated water consumption, posing a threat to the sustainability of ecological functions and socio-economic water use. Previous studies treating evapotranspiration (ET) as absolute water consumption and neglecting the precipitation increase from water recycling, have introduced considerable uncertainty and limited our understanding and prediction of the process. By combining GLEAM ET data and UTrack data, we depicted the contribution of ET in the YRB to local and surrounding basin precipitation .Our study reveals a substantial increase in ET in the YRB from 1980 to 2020. ET in this basin contributes to precipitation in both local and downstream areas through moisture recycling. On average, ET contributes 107 mm/yr of precipitation locally (21%), with the primary contribution from the Upper and Middle region. Additionally, ET contributes 63, 23, 20, and 20 mm/yr of precipitation to the Haihe River Basin, Yangtze Basin, Huaihe River Basin, and Songliao River Basin, respectively. Alongside the increase in ET, its contribution to precipitation is also rising, diminishing outward from the YRB. The increased ET brings about approximately 11 mm/yr of additional precipitation to YRB, offsetting about a quarter of the ET increase. We also provide a schematic diagram illustrating the water cycle in the YRB, elucidating the proportions of each component. This work contributes to a clearer understanding of the basin's hydrological processes, offering scientific support for water resource management and sustainable development in the changing conditions of the YRB.

How to cite: Zhang, H. and Wang, S.: Increased evapotranspiration in the Yellow River basin brings additional precipitation locally and downwindwards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8107, https://doi.org/10.5194/egusphere-egu24-8107, 2024.

EGU24-9778 | PICO | HS7.9

Estimating the impact of irrigation and groundwater pumping on regional hydroclimate using an Earth System Model 

Yusuke Satoh, Yadu Pokhrel, Hyungjun Kim, and Tokuta Yokohata

Irrigation is an anthropogenic forcing to the Earth-system that alters the water and heat budgets at the land surface, leading to changes in regional hydro-climate conditions over a range of spatiotemporal scales. These impacts of irrigation are anticipated to escalate in the future due to increased food demand and the pervasive effects of climate change. Thus, it is imperative to better understand the nature, extent, and mechanisms through which irrigation affects the Earth's system. However, despite its increasing importance, irrigation remains a relatively nascent component in the Earth-system modeling community, necessitating advancements in modeling and a deepened understanding.

Our research aims to improve the quantitative understanding of the impacts of irrigation and groundwater use as anthropogenic drivers on regional climate and environmental changes. To this end, we developed an improved Earth-system modeling framework that is based on MIROC-ES2L (Hajima et al 2020 GMD) coupled with hydrological human-activity modules (Yokohata et al. 2020 GMD). This model enables the simulation of a coupled natural-human interaction including hydrological dynamics associated with irrigation processes. Employing this Earth-system model, we carried out a numerical experiment in T85 spatial resolution, utilizing an AMIP style set-up. Here, our ensemble simulation allows for statistical quantification of the irrigation impact differentiating them from the uncertainties arising due to natural variability.

Through our investigation, we have identified specific regions and seasons where irrigation exerts a discernible influence on regional hydro-climate. Notably, our results show substantial disparities—larger than or comparable to inter-annual variability—between simulations incorporating and excluding the irrigation process, particularly in heavily irrigated regions such as Pakistan and India. Our model demonstrates that the introduction of moisture into the soil through irrigation alters the hydrological balance of the land surface, consequently influencing the overlying atmosphere. Conversely, we found significant uncertainty in the impact estimate for some regions, even those heavily irrigated, such as the central United States and eastern China, indicating the challenges of robustly estimating irrigation impacts with limited samples. This underscores the necessity for an appropriate statistical approach to evaluate the impact of irrigation, considering the inherent variability. Furthermore, our study delves into estimating regional variations in the contributions of groundwater and surface water use to these impacts. Emphasizing the importance of a more nuanced understanding of regional characteristics in irrigation impact assessments, our research underscores the significance of coupled earth system models in comprehending and predicting the intricate interplay between human activities and the Earth's climate system.

How to cite: Satoh, Y., Pokhrel, Y., Kim, H., and Yokohata, T.: Estimating the impact of irrigation and groundwater pumping on regional hydroclimate using an Earth System Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9778, https://doi.org/10.5194/egusphere-egu24-9778, 2024.

EGU24-12725 | ECS | PICO | HS7.9 | Highlight

Hydrological implications of future tree cover change and climate change 

Imme Benedict, Freek Engel, Caspar T. J. Roebroek, and Anne J. Hoek van Dijke

The availability of fresh water over land may become increasingly scarce under climate change. Future large scale tree cover changes can either enhance or mitigate this water scarcity. Previous work focused mostly on the impact of tree cover change in our current climate. Instead, we investigate the impact of climate change and future global tree cover change on precipitation, evapotranspiration, and runoff (water availability) in a future climate. To do so, multiple datasets and methodologies are combined; data from five CMIP6 models, a future tree cover change dataset, six Budyko models and a moisture recycling dataset. With this interdisciplinary data-driven approach the separate and combined effects of future climate change and future large-scale tree cover change can be quantified. The changes in water availability are studied on grid cell level (1 by 1 degrees), averaged over the globe, and aggregated for selected river basins (Yukon, Mississippi, Amazon, Danube and Murray-Darling).

Globally averaged, future climate change results in an increase in runoff where future tree cover change decreases the runoff. Both effects are of similar magnitude and lead to a limited net effect in water availability compared to the present climate. However, locally, the effects of tree cover change and climate change can be substantial, resulting in changes in water availability of more than 100 mm/year, either positive or negative. For the five selected river basins different responses in direction and magnitude of water availability are found due to future tree cover change under climate change. In all catchments, except the Mississippi basin, the climate change signal dominates over the tree cover change signal. For the Mississippi basin we find a dominant impact of tree cover change, opposite to the climate change signal, resulting in reduced water availability.

How to cite: Benedict, I., Engel, F., Roebroek, C. T. J., and Hoek van Dijke, A. J.: Hydrological implications of future tree cover change and climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12725, https://doi.org/10.5194/egusphere-egu24-12725, 2024.

EGU24-13419 | ECS | PICO | HS7.9

Irrigation impact on thermodynamics in weather forecast modelling 

Kirsten Maria FLORENTINE Weber, Linus Magnusson, Gianpaolo Balsamo, Margarita Choulga, Souhail Boussetta, Xabier Pedruzo Bagazgoitia, and Gabriele Arduini

By 2030, over 300 million hectares worldwide will be irrigated, constituting the second most significant anthropogenic influence on land use following urbanisation. Our study focuses on an irrigated Terrestrial Environmental Observatories (TERENO)/Integrated Carbon Observation System (ICOS) site in Germany, unveiling irrigation's immediate effects on soil moisture, latent heat flux, skin and soil temperature. As we strive to seamlessly integrate irrigation processes into the ECMWF Integrated Forecasting System (IFS), our investigation extends to an offline model, ECLand, including dynamical vegetation. Introducing a perturbed precipitation field offers a refined perspective of mimicking irrigation. The feedback provides us with insights into the coupling of simple irrigation representation on thermodynamic variables, ensuring optimal benefits for the IFS. After verification with remote sensing data, the next step involves coupling water fluxes to stomatal conductance via photosynthesis, shedding light on the preliminary influence of irrigation on enhanced vegetation growth. This aims to untangle irrigation effects of increased soil moisture and greening. 

How to cite: Weber, K. M. F., Magnusson, L., Balsamo, G., Choulga, M., Boussetta, S., Pedruzo Bagazgoitia, X., and Arduini, G.: Irrigation impact on thermodynamics in weather forecast modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13419, https://doi.org/10.5194/egusphere-egu24-13419, 2024.

EGU24-15039 | ECS | PICO | HS7.9

Fate and changes in moisture evaporated from the Tibetan Plateau (2000–2020) 

Chi Zhang, Deliang Chen, Qiuhong Tang, Jinchuan Huang, and Mei Yan

The Tibetan Plateau (TP) has been termed the “Asian water tower” and it plays an important role in regulating the Asian water cycle, which affects billions of people. Although the areal mean evaporation of the TP is not high, the total evaporation integrated over the vast terrain of the TP is huge and may strongly influence downwind regions. However, the ultimate fate of this evaporation moisture remains unclear. This study tracked and quantified TP-originating moisture using an extended WAM2Layers model. The findings reveal that the involvement of moisture from the TP in the downwind precipitation is most pronounced near the eastern boundary of the TP and gradually diminishes eastward. Consequently, the TP moisture ratio in precipitation reaches the highest of over 30% over the central-eastern TP. 44.9–46.7% of TP annual evaporation is recycled over the TP, and 65.1–66.8% of the TP evaporation is reprecipitated over terrestrial China. Moisture recycling of TP origin shows strong seasonal variation, with seasonal patterns largely determined by precipitation, evaporation and wind fields. High levels of evaporation and precipitation over the TP in summer maximize local recycling intensity and recycling ratios. Annual precipitation of TP origin increased mainly around the northeastern TP during 2000–2020. This region consumed more than half of the increased TP evaporation. Further analyses showed that changes in reprecipitation of TP origin were consistent with precipitation trends in nearby downwind areas: when intensified TP evaporation meets intensified precipitation, more TP moisture is precipitated out. This study also analyzed the uncertainty due to different tracking modes in WAM2Layers, i.e., backward and forward moisture tracking. In forward moisture tracking, the annual precipitation recycling ratio (PRR) of the TP was estimated to be 26.9–30.8%. However, due to the non-closure issue of the atmospheric moisture balance equation, the annual PRR in backward tracking could be ~6% lower.

How to cite: Zhang, C., Chen, D., Tang, Q., Huang, J., and Yan, M.: Fate and changes in moisture evaporated from the Tibetan Plateau (2000–2020), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15039, https://doi.org/10.5194/egusphere-egu24-15039, 2024.

EGU24-16857 | ECS | PICO | HS7.9

Reconciling bilateral connections of atmospheric moisture within the hydrological cycle 

Simon Felix Fahrländer, Elena De Petrillo, Marta Tuninetti, Lauren Seaby Andersen, Luca Monaco, Luca Ridolfi, and Francesco Laio

To improve our understanding of how we are connected globally through water flows, at scales relevant to policy and management, is imperative for global water stewardship. It is therefore crucial to describe the fate of moisture in the atmosphere by evaluating the global moisture inter-dependencies at the country level.  However, few studies have addressed global moisture inter-dependencies at the country level.

In this study, we present a novel dataset of country-to-country atmospheric moisture flows, including both terrestrial and oceanic sources, and propose an approach to assure the closure of the global and country-scale atmospheric water balance. By adopting an analogy with international trade analysis, we employ an iterative proportional fitting method to adjust the bilateral exchanges of water vapor from sources to sinks, ensuring that the total imported (exported) atmospheric moisture equals the total precipitation (evaporation) derived from ERA5 on an annual basis. 

Relevant analysis to understand water inter-dependencies between countries and regions can be performed from the bilateral matrix we present. We assess the terrestrial moisture recycling ratio (TMR) as the portion of countries’ or regions’ precipitation originating from terrestrial evaporation. Furthermore, we estimate a global TMR of 36%, while we find the highest TMRs are those of Eastern Asia (64%), Eastern Europe (68%), and Central Africa (79%). The bilateral structure of the dataset allows also to shed light on key links (and relative weights) dominating the exchange of atmospheric moisture between two countries or regions, thus supporting inter-countries water governance. For example, Central Africa receives 80% of its terrestrially sourced precipitation from Eastern Africa, while Eastern Europe evenly gets moisture from four distinct links, Eastern Asia, Central Asia, Southern Europe and Northern Europe, covering 70% of its import from terrestrial sources. 

Future studies can leverage the dataset to explore nations’ links in the global atmospheric moisture flow network and assess their role in the global hydrological cycle.

How to cite: Fahrländer, S. F., De Petrillo, E., Tuninetti, M., Andersen, L. S., Monaco, L., Ridolfi, L., and Laio, F.: Reconciling bilateral connections of atmospheric moisture within the hydrological cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16857, https://doi.org/10.5194/egusphere-egu24-16857, 2024.

EGU24-17252 | ECS | PICO | HS7.9 | Highlight

Impacts of the Three Gorges Dam on regional precipitation: based on high resolution simulation 

Peiyi Peng, Yiming Zhang, and Xu Di

The Three Gorges Dam (TGD), as the largest hydropower project, resulting in increasing water area from 408km2 to 1084km2 and extending waterway into 660 km. It is obvious that land use change would influence regional precipitation, but affected region owing to the TGD is on dispute. Moreover, the highest resolution of previous studies is 1.5 km, however the width of artificial lake formed by the TGD is about 1.1 km. To this end, we address the need of a higher resolution of numerical simulation by running weather research and forecast (WRF) model with 3 two-way nested domains. Two simulations under different land use (with or without TGD) are compared. Results showed that regional precipitation is suppressed owing to TGD to some extent. More precisely, increasing precipitation happens in downwind region, whereas decreasing precipitation occurs upwind region. Besides, water surface expansion leads to a reduction in surface temperature within 0~5 km of surrounding area. The TGD construction increase specific humidity and surface within 5 km buffer. That is because water surface expansion results in moisture surplus in nearby region.

How to cite: Peng, P., Zhang, Y., and Di, X.: Impacts of the Three Gorges Dam on regional precipitation: based on high resolution simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17252, https://doi.org/10.5194/egusphere-egu24-17252, 2024.

EGU24-19575 | ECS | PICO | HS7.9

Analysis of moisture recycling at unprecedented resolution in the western Mediterranean region  

Damián Insua Costa, Jessica Keune, Akash Koppa, Christian Massari, and Diego G. Miralles

The western Mediterranean region is a climate change hotspot, where the increase in temperature far exceeds the global average. This is causing its hydrological cycle to be highly impacted, with an increase in the frequency and intensity of droughts, extreme precipitation and floods. For this reason, a more holistic understanding of the atmospheric branch of water cycle and its connexion to meteorological changes is needed. Here we use satellite-based observational data recently generated within the 4DMED-Hydrology ESA project to analyse the atmospheric water transport in the region at an unprecedented resolution. Specifically, we combine a Lagrangian back-trajectory model for moisture tracking (FLEXPART–HAMSTER; Keune et al., 2022) with observed evaporation and precipitation data to quantify moisture recycling at 1 km spatial resolution. Our results show average local precipitation recycling rates close to 30% in summer months, in agreement with previous studies (Batibeniz et al., 2020), but this rate is highly variable over time, being much higher in periods of drought, when water supply is most needed. Likewise, the results reveal that evaporation recycling is highly spatially variable, meaning that moisture evaporated in some parts of the Mediterranean region is much more efficiently rained within the same region than others. For instance, in the Po Valley, the fraction of evaporation that returns to the region as rain is much higher than in its surroundings, which is why we consider it as a Mediterranean moisture source hotspot. Our findings demonstrate how meteorological anomalies can affect the transfer of water through the atmosphere in the region, and highlight the importance of investing in high-resolution Earth observation to advance our understanding of the different branches of the hydrological cycle. 

References: 

Keune, J., Schumacher, D. L., & Miralles, D. G. (2022). A unified framework to estimate the origins of atmospheric moisture and heat using Lagrangian models. Geoscientific Model Development, 15(5), 1875–1898. https://doi.org/10.5194/gmd-15-1875-2022 

Batibeniz, F., Ashfaq, M., Önol, B., Turuncoglu, U. U., Mehmood, S., & Evans, K. J. (2020). Identification of major moisture sources across the Mediterranean Basin. Climate Dynamics, 54, 4109-4127. https://doi.org/10.1007/s00382-020-05224-3 

How to cite: Insua Costa, D., Keune, J., Koppa, A., Massari, C., and G. Miralles, D.: Analysis of moisture recycling at unprecedented resolution in the western Mediterranean region , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19575, https://doi.org/10.5194/egusphere-egu24-19575, 2024.

EGU24-20936 | ECS | PICO | HS7.9 | Highlight

Atmospheric moisture recycling and its influence in the Sudd Region in the Upper Nile Basin 

Yueyang Chen and Asaad Shamseldin

Moisture recycling, is defined as the precipitation in a region which is partially contributed
by evapotranspiration from the same region. It is the interaction between terrestrial hydrology
and atmospheric processes, and plays a crucial role in forming local water resources and
affecting local climate. Up to date, global moisture recycling at regional and continental
scales has been understood relatively well, the patterns of local moisture recycling and the
main variables impacting it remain unclear. For wetlands, the evaporation alters local climate
by re-precipitation in surrounding regions, which can also be analysed from the viewpoint of
moisture recycling. Yet, there is rare research has been done in this viewpoint to analyse and
manage water resources of wetlands. It is thus of importance to carry out such research to
unveil it. As the largest wetland in Africa, the Sudd region has relatively large precipitation
recycling contributed by the surrounding regions, as well as large swampy areas of upper
Nile Basin, which makes it an appropriate study case for the moisture recycling of wetlands.
In this research, it is the first time to carry out atmospheric moisture recycling of Sudd region,
considering anthropogenic activities such as engineering practices, hydro-politics and
complex system. In this article, we will present multi-year hydro-climatology patterns of
Sudd, and the calculation results from Water Accounting Model-Two Layers (WAM-
2layers), including water vapor sources of its precipitation, and the reprecipitation of its
evapotranspiration. We will also analyse their spatial distributions, origin and destination, and
find the multi-year average moisture recycling ratio of the basin. From our calculation, it is as
high as 24% in some regions. In summary, this work shows that Sudd region is of great
significance to the neighbouring regions in terms of moisture recycling, and this would be
also useful to provide a practical basis for planning by considering local land-atmosphere
interaction.

How to cite: Chen, Y. and Shamseldin, A.: Atmospheric moisture recycling and its influence in the Sudd Region in the Upper Nile Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20936, https://doi.org/10.5194/egusphere-egu24-20936, 2024.

EGU24-508 | ECS | Posters on site | OS1.10

Interactions Between a Marine Heatwave and Tropical Cyclone Amphan in the Bay of Bengal in 2020 

Saurabh Rathore, Rishav Goyal, Babita Jangir, Caroline Ummenhofer, Ming Feng, and Mayank Mishra

Interactions are diagnosed between a marine heatwave (MHW) event and tropical super cyclone Amphan in the Bay of Bengal. In May 2020, an MHW developed in the Bay of Bengal driven by coupled ocean-atmosphere processes which included shoaling of the mixed layer depth due to reduced wind speed, increased net surface shortwave radiation flux into the ocean, increased upper ocean stratification, and increased sub-surface warming. Ocean temperature, rather than salinity, dominated the stratification that contributed to the MHW development and the subsurface ocean warming that also increased tropical cyclone heat potential. The presence of this strong MHW with sea surface temperature anomalies >2.5°C in the western Bay of Bengal coincided with the cyclone track and facilitated the rapid intensification of tropical cyclone Amphan to a super cyclone in just 24 h. This rapid intensification of a short-lived tropical cyclone, with a lifespan of 5 days over the ocean, is unprecedented in the Bay of Bengal during the pre-monsoon period (March-May). As the cyclone approached landfall in northern India, the wind-induced mixing deepened the mixed layer, cooled the ocean's surface, and reduced sub-surface warming in the bay, resulting in the demise of the MHW. This study provides new perspectives on the interactions between MHWs and tropical cyclones that could aid in improving the current understanding of compound extreme events that have severe socio-economic consequences in affected countries.

How to cite: Rathore, S., Goyal, R., Jangir, B., Ummenhofer, C., Feng, M., and Mishra, M.: Interactions Between a Marine Heatwave and Tropical Cyclone Amphan in the Bay of Bengal in 2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-508, https://doi.org/10.5194/egusphere-egu24-508, 2024.

EGU24-1252 | ECS | Posters on site | OS1.10

Future Projections of Marine Heatwaves in the Indian Ocean under Different Socioeconomic Pathways 

Dushantha Sandaruwan Jayarathna Wijendra Naidhelage, Wen Zhou, Matthew Collins, Oluwafemi E. Adeyeri, Xuan Wang, Erandani Lakshani Widana Arachchige, and Ni Zekai

Marine heatwaves (MHWs) are extended periods of abnormal warm sea surface temperature (SST) events that can have considerable impact on the marine ecosystems and associated services. Despite recent developments in studying MHWs in the Indian Ocean, our understanding of their future occurrence remains limited. Hence, this study is crucial to expanding our understanding of future MHWs in the region. We use observational data from the Optimal Interpolated Sea Surface Temperature analysis (OISSTv2) and daily SST data from 14 models obtained from Coupled Model Intercomparison Project Phase 6 (CMIP6) to investigate the spatial and temporal characteristics of MHWs in the historical period (1982-2014) and future (2015-2100) under three shared socioeconomic pathways (SSPs, e.g., SSP126, SSP245, SSP585). During the historical period, more intense MHWs concentrated near the northern Arabian and Bay of Bengal region, with total MHW days of 20 ~ 25 days per year and mean intensity of 2 ~ 3 oC per year. The CMIP6 models overestimate the duration of MHWs while underestimating their intensity. Nevertheless, we employ the quantile delta mapping bias correction method to minimize these uncertainties in the CMIP6 multi model ensemble mean for a robust and reliable depiction of the future MHWs characteristics. We note accelerated positive trend in MHW metrics, including total days, and cumulative intensity, in the future compared to the historical period, resulting from global warming. Moreover, different emission scenarios exhibit different future MHWs characteristics. Specifically, the duration and mean intensity of MHWs are distinctly higher under SSP585 compare to other two scenarios, except for MHW frequency. Considering that we focused on a fixed baseline for MHW detection, we attribute the increase in MHWs duration to anthropogenic greenhouse gas emissions. Therefore, we emphasize the need for proactive measures to mitigate the impacts on future MHWs on marine ecosystems and associated services in the face of climate change.

 

How to cite: Wijendra Naidhelage, D. S. J., Zhou, W., Collins, M., E. Adeyeri, O., Wang, X., Widana Arachchige, E. L., and Zekai, N.: Future Projections of Marine Heatwaves in the Indian Ocean under Different Socioeconomic Pathways, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1252, https://doi.org/10.5194/egusphere-egu24-1252, 2024.

Heading into a potential El Niño in 2023/24, concern was high amongst Australian marine stakeholders regarding potential marine heatwave impacts on marine industries and systems in the coming summer. Targeted climate outlook briefings for the Great Barrier Reef and Western Australian coral reefs have been provided prior to and throughout the summer months by the Australian Bureau of Meteorology for the past 10-15 years, however in 2023 these were requested much earlier than usual. Also in 2023, national level seafood-focused briefings were requested by the fisheries sector for the first time, with various state and regional level meetings and information requests also occurring.

Subseasonal to seasonal forecast information played a critical role in these briefings, providing both the big picture in terms of climate drivers impacting Australian waters as well as regional information regarding sea surface temperatures around Australia. These forecast products are operationally produced by the Australian Bureau of Meteorology using the seasonal prediction system ACCESS-S. Clear communication of forecast probabilities and model skill was essential. New prototype marine heatwave forecasts were also presented to marine stakeholders, indicating where there was a high likelihood of marine heatwaves occurring in the upcoming season, together with likely severity. Demand for this new information on temperatures extremes was high and provided impetus for setting up coordinated briefings and response plans across sectors.

Forecasts can provide a 'preparation window' for marine stakeholders to implement proactive management strategies prior to high-risk conditions, noting however that not all industries have the same level of agility to respond. Subseasonal to seasonal forecast tools, that are useful, usable and used, provide valuable information to assist marine stakeholders in managing climate risk and vulnerability in a warming climate.

How to cite: Spillman, C., Hobday, A., Smith, G., and Hartog, J.: Building industry resilience through seasonal forecast briefings to Australian marine stakeholders heading into the 2023/24 summer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1558, https://doi.org/10.5194/egusphere-egu24-1558, 2024.

EGU24-1779 | ECS | Posters on site | OS1.10

Assessing Marine Heatwave Variability in the Luzon Strait 

Rose Angeli Macagga and Po-Chun Hsu

The Luzon Strait, a 350-km wide channel located between Taiwan and the Philippines, connects the West Philippine Sea and the north Pacific Ocean. Multiple factors affect the circulation in the Luzon Strait, such as the Kuroshio Current, monsoon, and the West Philippine Sea circulation. Discrete periods of extreme ocean warming events, also known as marine heatwaves (MHWs), have been occurring longer and more frequently across the globe. Anomalous temperature events can cause drastic changes in the biogeochemical processes and trigger adverse effects on marine ecology in the surrounding areas. This study aims to understand the variation in MHWs in the study area (16-24°N, 115-126°E), focusing on the Luzon Strait, using a daily global 5-km sea surface temperature (SST) product from 1985 to 2022. Four points of known coral reef areas were also chosen to further assess the MHWs and their possible effects on marine ecology.  Six MHW indices were utilized to describe the frequency, duration, and intensity of MHW events. The highest frequency of 17 MHWs in a year occurred in 1998, while the longest duration per event of 144 days and the total duration in a year of 308 days were recorded in 2020 and 2021, respectively. The highest values for all three intensity parameters were recorded in 2021, with mean, maximum, and cumulative intensities reaching 2.62°C, 3.86°C, and 227.42°C-days, respectively. The spatial distribution of monthly SST and ocean current profile showed thermal areas and helped identify high-risk areas. Climate variations, such as El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO), were also explored as physical drivers of MHW in the study area. It has been observed that most of the years featuring MHW events at the four coral reef points occurred during the La Niña phase of ENSO, in conjunction with the negative phase of PDO, including 1998, 2010, and from 2020 onwards. Additionally, from 2016 to 2019, MHWs were observed at the same points during the positive phase of PDO, in conjunction with El Niño, La Niña, or Neutral phases of ENSO.

How to cite: Macagga, R. A. and Hsu, P.-C.: Assessing Marine Heatwave Variability in the Luzon Strait, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1779, https://doi.org/10.5194/egusphere-egu24-1779, 2024.

EGU24-1883 | ECS | Orals | OS1.10

Extreme and compound ocean events are key drivers of projected low pelagic fish biomass  

Natacha Le Grix, William Cheung, Gabriel Reygondeau, Jakob Zscheischler, and Thomas Frölicher Frölicher

Ocean extreme events, such as marine heatwaves, can have harmful impacts on marine ecosystems. Understanding the risks posed by such extreme events is key to develop strategies to predict and mitigate their effects. However, the underlying ocean conditions driving severe impacts on marine ecosystems are complex and often unknown as risks to marine ecosystems arise not only from hazards but also from the interactions between hazards, exposure and vulnerability. Marine ecosystems may not be impacted by extreme events in single drivers but rather by the compounding effects of moderate ocean anomalies. Here, we employ an ensemble climate-impact modeling approach that combines a global marine fish model with output from a large ensemble simulation of an Earth system model, to identify the key ocean ecosystem drivers associated with the most severe impacts on the total biomass of 326 pelagic fish species. We show that low net primary productivity is the most influential driver of extremely low fish biomass over 68% of the ocean area considered by the model, especially in the subtropics and the mid-latitudes, followed by high temperature and low oxygen in the eastern equatorial Pacific and the high latitudes. Severe biomass loss is generally driven by extreme anomalies in at least one ocean ecosystem driver, except in the tropics, where a combination of moderate ocean anomalies is sufficient to drive extreme impacts. Single moderate anomalies never drive extremely low fish biomass. Compound events with either moderate or extreme ocean conditions are a necessary condition for extremely low fish biomass over 78% of the global ocean, and compound events with at least one extreme variable are a necessary condition over 61% of the global ocean. Overall, our model results highlight the crucial role of ex-treme and compound events in driving severe impacts on pelagic marine ecosystems.

How to cite: Le Grix, N., Cheung, W., Reygondeau, G., Zscheischler, J., and Frölicher, T. F.: Extreme and compound ocean events are key drivers of projected low pelagic fish biomass , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1883, https://doi.org/10.5194/egusphere-egu24-1883, 2024.

EGU24-1925 * | ECS | Posters on site | OS1.10 | Highlight

Drivers of Global Marine Heatwaves in a Warming World 

Ce Bian, Zhao Jing, and Lixin Wu

Global warming has exacerbated occurrence of extreme events, threatening the environment of human living. Marine heatwaves (MHWs) are prolonged extreme warm water events in the ocean, exerting devastating impacts on marine ecosystems. Comprehensive knowledge of physical processes controlling MHW life cycles is pivotal to improving MHW forecast capacity, yet it is still lacking. Here, we use a historical simulation from a global eddy-resolving climate model with an improved representation of MHWs, and innovatively show that heat flux convergence by oceanic mesoscale eddies acts as a dominant driver of MHW life cycles over most parts of the global ocean. In particular, the mesoscale eddies make an important contribution to growth and decay of MHWs, whose characteristic spatial scale is comparable or even larger than that of mesoscale eddies. Moreover, our results proved that features of global MHWs are scale-dependent. The primary drivers of MHWs shift from oceanic advection to atmospheric forcing as their spatial scale becomes larger. There is evident geographic heterogeneity in the transition scale between these oceanic and atmospheric-process dominated regimes. Our study reveals the crucial role of mesoscale eddies in controlling the global MHW life cycles and highlights that using eddy-resolving ocean models is essential for accurate MHW forecasts. Another contribution is we clarified the transition scale of global MHWs, which is essential for parameterization of MHWs forecasting in a warmer future. 

How to cite: Bian, C., Jing, Z., and Wu, L.: Drivers of Global Marine Heatwaves in a Warming World, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1925, https://doi.org/10.5194/egusphere-egu24-1925, 2024.

Under global warming, the frequency and intensity of marine heatwaves are increasing. However, the inhibition of atmospheric forcing marine heatwaves (AMHW) on upwelling and its impact on marine ecosystems remain poorly understood. To address this issue, the satellite sea surface temperature and reanalysis data during 1998-2021 were analyzed in three distinct upwelling systems, northwestern South China Sea. The results showed that the coastal tide-induced upwelling in the west (W) of Hainan Island is primarily suppressed by enhanced stratification during the AMHW events, since the coastal tide-induced upwelling is insensitive to wind weakening. Contrarily, the wind-driven upwelling in the east (E) and northeast (NE) of Hainan Island are jointly regulated by wind and stratification during the AMHW. Specifically, the AMHW events have a stronger inhibitory effect in the upwelling and phytoplankton growth in the NE than that in the E. The causes could be the followings: (1) the background upwelling in the NE region is stronger than in the E, thus the NE region has a higher susceptibility to the wind weakening; (2) the wind-driven upwelling begins to be suppressed by AMHW when the high-pressure system is aligned with the coastline of the upwelling. In the NE region, the location of the high-pressure center during the occurrence of AMHW is positioned in closer proximity to the upwelling area. Moreover, the inhibitory effect of wind weakening and stratification enhancing on upwelling changes with the development of the AMHW. Before and during the mature phase of AMHW, stratification and wind jointly inhibit upwelling and phytoplankton growth, while it shifts to stratification dominated (>85%) during the decline phase. This study suggests that MHW has a great impact on the upwelling ecosystem, especially the wind-driven upwelling, which should be given high attention under global warming (with increasing MHW events in the future).

How to cite: Liu, S., Lao, Q., and Chen, F.: Impacts of Marine Heatwave Events on Three Distinct Upwelling Systems and its Implication for Marine Ecosystems in the Northern South China Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1942, https://doi.org/10.5194/egusphere-egu24-1942, 2024.

EGU24-1948 | ECS | Posters on site | OS1.10

Frequent marine heatwaves hidden below the surface of the global ocean 

Di Sun, Furong Li, Zhao Jing, Shijian Hu, and Bohai Zhang

Marine heatwaves are extreme warm water events that can cause devastating impacts on ecosystems and have complex socio-economic ramifcations. Surface signals and drivers of marine heatwaves have been extensively investigated based on satellite observations, whereas their vertical structure in the global ocean remains unclear. In this study, we identify marine heatwave events in the epipelagic zone (0–200 m) using a four-dimensional spatio-temporal framework based on three ocean reanalysis datasets. We find that only about half of the marine heatwave events have continuous surface signals during their life cycles and around one-third always reside in the subsurface ocean without any imprint on sea surface temperature. The annual number of these subsurface marine heatwave events shows a signifcant increase in response to subsurface mean-state warming during the past three decades. Our findings reveal the limitation of identifying marine heatwaves solely based on the sea surface temperature and underscore the necessity of subsurface observations for monitoring marine heatwaves.

How to cite: Sun, D., Li, F., Jing, Z., Hu, S., and Zhang, B.: Frequent marine heatwaves hidden below the surface of the global ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1948, https://doi.org/10.5194/egusphere-egu24-1948, 2024.

EGU24-2617 | ECS | Orals | OS1.10

Underestimated Arctic warming and potential ecosystem impact due to unresolved marine heatwaves 

Ruijian Gou, Yaocheng Deng, Klara Wolf, Yingzhe Cui, Clara Hoppe, Lixin Wu, Qi Shu, and Gerrit Lohmann

The Arctic is warming faster than any other regions, a phenomenon known as Arctic amplification, which has far-reaching effects for global climate. Modelled historical simulations show a significant underestimation of the amplification and the future projection exhibits non-negligible model spread. Here we show that in a future warming scenario, the warming in the Arctic is generally larger when comparing high-resolution climate models with low-resolution versions. We attribute the different extent of Arctic warming to Arctic marine heatwaves (MHWs), known as episodes of extreme ocean surface warming. The resolution of the MHWs, which are stronger and more realistic in the high-resolution model versions, increases the melting of sea ice and thus the absorption of solar radiation by the ocean in the short term, thereby reinforcing the long-term trend of Arctic warming. We point out that the amplification of Arctic warming is underestimated by the current generation of climate models, which generally have low resolution, thereby underestimating Arctic marine heat waves. In addition, Arctic heatwaves cause extreme temperature fluctuations associated with increased stratification. This poses major challenges to Arctic ecosystems and has a negative impact through direct physiological temperature effects and indirectly through nutrient supply and taxonomic shifts. We conclude that the eddy- and storm-resolving models provide a new perspective on how the Earth system responds to past and future climate and environmental extremes.

How to cite: Gou, R., Deng, Y., Wolf, K., Cui, Y., Hoppe, C., Wu, L., Shu, Q., and Lohmann, G.: Underestimated Arctic warming and potential ecosystem impact due to unresolved marine heatwaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2617, https://doi.org/10.5194/egusphere-egu24-2617, 2024.

EGU24-2720 | ECS | Orals | OS1.10

Significant reduction of potential exposure to extreme marine heatwaves by achieving carbon neutrality 

Seok-Geun Oh, Seok-Woo Son, Sujong Jeong, and Yang-Ki Cho

Marine heatwave (MHW), a prolonged period of anomalously warm seawater, has a catastrophic repercussion on marine ecosystems. With global warming, MHWs have become increasingly frequent, intense, and prolonged. To avoid irreversible damages from such extreme events, net-zero human-caused carbon emissions by 2050s, called carbon neutrality, were proposed. Here, we evaluate the impact of carbon neutrality on MHWs in the late 21st century using multi-model projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) Shared Socioeconomic Pathway (SSP)1-1.9 and SSP3-7.0 scenarios. It is found that if the current “regional rivalry” over carbon emissions policy continues into this century (i.e., SSP3-7.0), the MHWs in the late 21st century will become stronger over 1°C and longer lasting over 365 days than historical ones, especially in the western boundary current and equatorial current regions. Approximately 68% of the global ocean will be exposed to permanent MHWs, regionally 93% in the Indian Ocean, 76% in the Pacific Ocean, 68% in the Atlantic Ocean, 65% in the Coastal Ocean, and 48% in the Southern Ocean. Such extreme MHWs can be significantly reduced by achieving carbon neutrality (i.e., SSP1-1.9). In particular, the proportion of exposure to permanent MHWs can be reduced to as low as 0.02 to 0.07%, depending on the region. This result underscores the critical importance of ongoing efforts to achieve net-zero carbon emissions to reduce the potential ecological risks induced by extreme MHW exposure.

How to cite: Oh, S.-G., Son, S.-W., Jeong, S., and Cho, Y.-K.: Significant reduction of potential exposure to extreme marine heatwaves by achieving carbon neutrality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2720, https://doi.org/10.5194/egusphere-egu24-2720, 2024.

Extreme and persistent marine heatwaves (MHWs) occur frequently in the Northeast Pacific, with huge impacts on climate, ecosystem and socio-economic. This study investigates the atmospheric circulations associated with the 33 MHWs since 1951 in observations. The composite results reveal that the MHWs in the Northeast Pacific can be triggered by a couple of anticyclonic and cyclonic anomalies, i.e., the anticyclonic anomaly to the northeast of the MHW region and cyclonic anomaly to the southwest.  This atmospheric circulation pattern can be detected as the dominant mode through EOF analysis on 500-hPa geopotential height anomalies over the Northeast Pacific-North America region, following the Pacific–North American teleconnection. These observational results are verified by using the outputs of 34 models in the historical simulation from phase 6 of the Coupled Model Intercomparison Project (CMIP6). Further diagnosis of the heat budget is performed, in attempt to illustrate the processes of MHW formation and maintenance.

How to cite: Tang, C. and Lu, R.: The atmospheric circulation anomalies associated with the formation of marine heatwaves in the Northeast Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3459, https://doi.org/10.5194/egusphere-egu24-3459, 2024.

EGU24-4034 | ECS | Orals | OS1.10

Projected amplification of summer marine heatwaves in a warming Northeast Pacific Ocean 

Marylou Athanase, Antonio Sánchez-Benítez, Helge Goessling, Felix Pithan, and Thomas Jung

Marine heatwaves are expected to become more frequent, intense, and longer-lasting in a warming world. However, it remains unclear whether feedback processes could amplify or dampen extreme ocean temperatures. Here we impose the observed atmospheric flow in coupled climate simulations to determine how the record-breaking 2019 Northeast Pacific marine heatwave would have unfolded in preindustrial times, and how it could unravel in a +4°C warmer world compared to present-day conditions. We find that air-sea interactions, involving reductions in clouds and ocean mixed-layer depth and air advection from fast-warming subpolar regions, modulate warming rates within the marine heatwave. In a +4°C warmer climate, global oceans are +1.9°C warmer than present levels, and regional mean warming in the Northeast Pacific can reach +2.3–2.7 ± 0.25°C. Our identified feedback processes are projected to further amplify the intensity and spatial extent of analogous Northeast Pacific summer marine heatwaves beyond those thresholds, with a warming reaching +2.9 ± 0.15°C above present levels. Such an event-specific amplification would place even greater stress on marine ecosystems and fisheries.

How to cite: Athanase, M., Sánchez-Benítez, A., Goessling, H., Pithan, F., and Jung, T.: Projected amplification of summer marine heatwaves in a warming Northeast Pacific Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4034, https://doi.org/10.5194/egusphere-egu24-4034, 2024.

EGU24-4862 | ECS | Posters on site | OS1.10

Depth-dependent coastal Marine Heatwaves: a case study in Shark Bay, Western Australia 

Yuwei Hu and Chunzai Wang

Marine Heatwaves (MHWs) are commonly defined as extreme warm weather or climate events and typically have large impacts on the local ecosystems and economy. Coastal seas that connect the open ocean and land are highly impacted by local terrestrial weather and climate systems. Distinct geographical features (e.g. water depth and bottom topography) of each coastal sea may locally contribute to the spatiotemporal pattern and associated drivers of coastal MHWs. To unravel this undetermined contribution, we choose the Shark Bay (Western Australia) as a case study domain. It is a semi-enclosed bay adjacent to the warm Leeuwin Current with in-bay water depth varying around 0 to 25m and out-bay depth from 25m down to 200m in the selected study area. Thus, the contribution of air-sea heat flux, advection, and other oceanic processes can be quantitatively evaluated by applying the mixed layer heat budget analysis based on a 0.1-degree model reanalysis dataset, Bluelink ReANalysis (BRAN) 2020. Additionally, three high-resolution satellite sea surface temperature (SST) products are used to identify, visualize, and analyze the spatiotemporal patterns of MHWs in Shark Bay. The spatial maps of MHW mean duration, mean cumulative intensity and event frequency exhibit a highly consistent pattern with large differences between metrics in shallow and deep areas. Mixed layer heat budget analysis within a month before each corresponding peak day of three selected major events, to some extent, confirms that this distinct spatial pattern is partially due to the constrained contribution of the entrainment processes below the mixed layer in shallow areas. The entrainment processes that are closely related to the mixed layer depth change may warm the surface layer during mixed layer shoaling by excluding less warm water below the mixed layer. This is not the case in very shallow regions. Interestingly, slightly different from what was previously assumed, the in-bay areas, instead of being warmed by the horizontal advection when the out-bay areas are warmed by the anomalous warming Leeuwin current, are slightly cooled by a constrained net cooling effect. We found that coastal MHW events in shallow areas are typically frequent but less intense if they occur independently under the typical net cooling effects of horizontal advection. Whereas coastal MHWs in deep areas are less frequent, but more intense and prolonged when concurrent with anomalous warm water advection. The shallowest in-bay areas that are not included in the heat budget analysis are outside the influence area of the net cooling effects. Thus, these areas may be intrinsically embedded with frequently fast warming effects of the net heat flux. By using the 90th percentile definition, these frequent warming are defined as MHWs, but the regularity of historical events may not lead to catastrophic impacts regarding the shorter duration and smaller cumulative intensity of an individual event. We then suggest that a global assessment of the net cooling effects of horizontal advection is necessary, to identify qualified coastal areas associated with higher resistance to sudden and prolonged ocean warming. 

How to cite: Hu, Y. and Wang, C.: Depth-dependent coastal Marine Heatwaves: a case study in Shark Bay, Western Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4862, https://doi.org/10.5194/egusphere-egu24-4862, 2024.

EGU24-5083 | ECS | Orals | OS1.10

Long-term warming and interannual variability contributions’ to marine heatwaves in the Mediterranean 

Amelie Simon, Carlos Pires, Thomas L. Frölicher, and Ana Russo

In the past 40 years, marine heatwaves (MHWs) have experienced a worldwide increase in duration, intensity, frequency and spatial extent. This trend has been particularly evident in the Mediterranean, where exceptional events were observed during the summers of 2022, 2018 and 2003. This study proposes a twofold analysis of MHWs in the Mediterranean, focusing on their statistical characteristics and physical causes. A satellite dataset is utilized to analyze MHWs via an index, called activity, which aggregates the occurrence, duration, intensity and spatial extent of events. Our results show that the trend toward more active summers for MHWs is strongest in the western Mediterranean basin and long-term warming is the main driver in the whole Mediterranean basin. We also show that in the western and Adriatic Mediterranean region, the increase of SST variability contributes about a third to the MHW activity long-term trend whereas in the central, eastern and Aegean basins, the variability of SST mostly acts to diminish this trend. Through principal component analysis (PCA) of MHW activity, we found that the three most severe summer MHW events in the Mediterranean occur at the same location where the overall trend is highest. Interannual variability increased MHW activity in 2022 around the Balearic Sea, in 2018 in the eastern basins and in 2003 in the central basins. A joint PCA revealed that the long-term trend in MHW activity co-varies with a positive geopotential height anomaly over the Mediterranean, which is consistent with the generation of atmospheric-driven MHWs and which, at the North Atlantic scale, resembles the positive phase of the summer East Atlantic. The additional interannual variability contribution to these three severe summers was associated with western warming and projected onto the positive phase of the summer North Atlantic Oscillation. The increase in MHW over the last 40 years is also associated in the western, central and Adriatic regions with increased downward short-wave radiation and in the eastern Mediterranean with decreased upward long-wave radiation. Increased upward latent heat flux partly compensated for the MHW long-term increase over the whole Mediterranean basin. The interannual variability of MHW activity is related in the western, central and Adriatic basins to increased downward sensible and decreased upward latent heat flux possibly due to warm and humid air intrusion.

 

A.S., A.R. and C.P. thank Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES http://doi.org/10.54499/JPIOCEANS/0001/2019 (ROADMAP), T.L.F. thank the Swiss National Science Foundation (Grant P00P2_198897), A.R and C.P thanks the national funds (PIDDAC) – UIDB/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020). A.S. was supported by ANR and France 2030 through the project CLIMArcTIC (grant ANR-22-POCE-0005). A.R. was supported by FCT through https://doi.org/10.54499/2022.01167.CEECIND/CP1722/CT0006.

How to cite: Simon, A., Pires, C., Frölicher, T. L., and Russo, A.: Long-term warming and interannual variability contributions’ to marine heatwaves in the Mediterranean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5083, https://doi.org/10.5194/egusphere-egu24-5083, 2024.

EGU24-5286 | ECS | Posters virtual | OS1.10

Marine Heat Waves long-term trend assessment in the Northeast Atlantic region.  

Lluís Castrillo-Acuña, Silvia Martínez-Martínez, and Álvaro de Pascual-Collar

Marine heat waves (MHWs) may be understood as prolonged periods of anomalously high sea surface temperatures (SST). These events are associated to impacts on marine ecosystems such as coral bleaching, mass mortality of marine invertebrates due to heat stress, rapid species’ migrations, fishery closures or quota changes, among others.

The Iberia-Biscay-Ireland (IBI) region, covering from the Canary basin to the Celtic Sea, demonstrated for the year 2022 peak anomaly values of 15 MHWs events, 128 days of mean durations, and 261 total days of MHW according to a reference period from 1982 to 2022 (Castrillo-Acuña et al. 2024). The result of almost 300 days of MHW in some areas for the 2022 suggest that the current methodology may not be complete, as MHW are expected to be an extreme phenomenon. Global assessments such us Oliver et al. (2018) and Schlegel et al. (2019) had demonstrated the correlation between long term mean SST trends and some MHWs properties, but may this influence be strong enough to invalidate the results?

In this study we present a sensitive experiment of the affection of long term mean trends of SST and MHW detection by using different detrending methods. Also considering different refence periods.  It is performed in the IBI domain which covers upwellings, straits, bays, continental shelfs, open waters, etc. The study aims to investigate how the presence of medium to long-term trends may condition the MHW properties in different key oceanographic areas. In this way, we can differentiate regions where the variability of MHW is not conditioned by SST trends from those where it is and its magnitude.

 

 

 

 

 

 

 

 

Castrillo-Acuña, L., Alonso-Valle, A., de Pascual-Collar, A.: Characterization of Marine Heat Waves in the IBI Region in 2022. Manuscript submitted to the 8th edition of the Copernicus Ocean State Report (OSR8), Copernicus Publications, State Planet, 2024.

 

Oliver, E. C. J., Donat, M. G., Burrows, M. T., Moore, P. J., Smale, D. A., Alexander, L. V., Benthuysen, A., Feng, M., Sen Gupta, A., Hobday, A. J., Holbrook, N. J., Perkins-Kirkpatrick, S. E., Scannell, H. A., Straub, S. C., and Wernberg, T.: Longer and more frequent marine heatwaves over the past century. Nature Communications, 9(1), Article 1. https://doi.org/10.1038/s41467-018-03732-9, 2018.

 

Schlegel, R. W., Oliver, E. C. J., Hobday, A. J., & Smit, A. J. : Detecting Marine Heatwaves With Sub Optimal Data. Frontiers in Marine Science, 6.    https://www.frontiersin.org/articles/10.3389/fmars.2019.00737, 2019.

How to cite: Castrillo-Acuña, L., Martínez-Martínez, S., and de Pascual-Collar, Á.: Marine Heat Waves long-term trend assessment in the Northeast Atlantic region. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5286, https://doi.org/10.5194/egusphere-egu24-5286, 2024.

EGU24-5667 | Orals | OS1.10

Marine heatwaves: Can we predict them in the Barents Sea? 

Helene R. Langehaug, Anne Britt Sandø, Robinson Hordoir, Francois Counillon, Ping-Gin Chiu, and Roshin Raj

Marine heatwaves (MHW) can have large negative impacts on life in the ocean, such as kelp forest and corals. These environments are vital for protecting a range of different species in the ocean. With global warming, the occurrence and intensity of MHW are expected to increase, also in the polar regions. The Barents Sea has experienced large climate changes, becoming less influenced by sea ice during the last decades. Being able to predict the likelihood of MHW to occur in the Barents Sea could be highly beneficial to fisheries, aquaculture, and other relevant stakeholders. Such information could be useful in long-term risk assessment. In this study, we assess for the first time the skill of the Norwegian Climate Prediction Model (NorCPM) in predicting the likelihood of MHW. For this analysis, we focus on intense MHW in July 2016 taking place in the Barents Sea, and previously documented by satellite data. We find promising results in the seasonal predictions from NorCPM, where the predictions show increased probability for MHW to occur in July 2016 compared to July 2015 (when the MHW activity was lower than in 2016). The increased probability was already seen six months prior to the event. Furthermore, we downscale the results from the global NorCPM to a more refined grid with a horizontal resolution of 10km. This test case shows that downscaling can provide valuable information on the subsurface signature of MHW. We found the event in July 2016 to be shallow (down to about 50m) compared to another MHW event in July 2013, where warm anomalies occupied the whole water column. These results suggest that the event in July 2016 was atmospheric-driven, consistent with a previous study, whereas the event in 2013 is more likely to be ocean-driven. The results from this case study are promising for future seasonal prediction of MHW using NorCPM, and more in-depth studies are needed to quantify the predictive skill for different cases and different regions.

How to cite: Langehaug, H. R., Sandø, A. B., Hordoir, R., Counillon, F., Chiu, P.-G., and Raj, R.: Marine heatwaves: Can we predict them in the Barents Sea?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5667, https://doi.org/10.5194/egusphere-egu24-5667, 2024.

EGU24-5681 | Posters on site | OS1.10

Global surface ocean temperature anomalies in 2023 and their climate context 

Matthew Menary and Leon Hermanson

Around 3 billion people rely on the ocean for their livelihoods, with around 10% of the world’s population directly relying on fishing. As human-driven climate change causes the world to warm, the ocean and the ecosystems within are increasingly susceptible to heatwave events that can have severe consequences. Such marine heatwaves (MHWs) can last from several days to a year and result in the destruction of ocean habitats and the diminution or relocation of fish species, with knock-on effects for coastal communities. The frequency of MHWs has doubled since 1982 and they are likely to continue to increase in frequency, intensity, and duration. However, the link between MHWs and modes of climate variability remains uncertain. Here, we investigate to what extent maps of temperature anomalies in 2023 can be attributed to large-scale climate modes with centres of action in the Atlantic, North Pacific, and tropical Pacific. Specifically, we regress global sea surface temperatures on to indices of Atlantic Multidecadal Variability (AMV), the 2nd EOF of North Pacific variability (commonly linked to MHWs), and El Nino/Southern Oscillation (ENSO, which strongly correlates with the 1st EOF of North Pacific variability). We find that around 30% of the variance in global, annual sea surface temperature anomalies can be explained by a linear combination of these indices. Since 2012, the combination of these indices has been unprecedented, associated with anomalous warming (on top of the global trend) throughout the northern hemisphere. As such, climate variability (which may include a forced component) is currently providing an unusually high baseline for further MHW events. Further work will aim to use decadal prediction models to investigate the predicted evolution of these indices over the coming years.

How to cite: Menary, M. and Hermanson, L.: Global surface ocean temperature anomalies in 2023 and their climate context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5681, https://doi.org/10.5194/egusphere-egu24-5681, 2024.

EGU24-6542 | Orals | OS1.10

Large-scale drivers of Northeast Pacific MHWs in a changing climate 

Antonietta Capotondi, Matthew Newman, Tongtong Xu, and Emanuele Di Lorenzo

The Northeast Pacific Ocean has experienced episodes of intense and persistent warm conditions, also known as marine heatwaves, with devastating ecological impacts. Being able to predict these extreme events a few seasons in advance is therefore very important, but has proven elusive in many cases. While the intensity of Northeast Pacific marine heatwaves has been related to local stochastic atmospheric forcing with limited predictability, their evolution and persistence may be controlled by large-scale climate influences. Here we use a multi-variate statistical approach to identify these large-scale drivers, as well as the initial states that optimally develop into a marine heatwave at a later time in this region. Results indicate that a decadal mode of variability related to the Pacific Decadal Oscillation plays a key role in creating conditions favorable to the development of Northeast Pacific marine heatwaves. This mode is also implicated in the development of Central Pacific El Niño events, which may contribute to the persistence of the Northeast Pacific warm anomalies. In addition, this mode of variability appears to be responsible for the increased Northeast Pacific sea surface temperature variance in recent decades, suggesting that changes in internal climate variability may be responsible for the enhanced MHW activity in this region during this recent period.

How to cite: Capotondi, A., Newman, M., Xu, T., and Di Lorenzo, E.: Large-scale drivers of Northeast Pacific MHWs in a changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6542, https://doi.org/10.5194/egusphere-egu24-6542, 2024.

EGU24-6880 | Posters on site | OS1.10

Just another Tasman Sea marine heatwave? 

Neil Holbrook

Through late November and early December 2023, a severe category marine heatwave (MHW) was detected moving southwards off the east coast of Tasmania, Australia. The MHW was characterised by offshore sea surface temperature anomalies ~4oC above climatological values embedded within and around large anticyclonic eddies with warm anomalies to >1000m depth. Given the deleterious impacts from previous MHWs on marine ecosystems, fisheries, and aquaculture in the region, serious concerns were raised. To advise and prepare stakeholders, a series of online briefings was given by physical, biogeochemical, fisheries, and social scientists on the current and likely evolving environmental conditions associated with the MHW. So, how unusual was this event? Was it successfully forecast? Was it expected from our knowledge of large-scale modes of climate variability and their teleconnections? This presentation will discuss the characteristics, evolution – both forecast and projected – and emerging impacts of the November-December 2023 Tasman Sea MHW. It will be argued that the characteristics of this event mirror expectations from anthropogenic climate change, and that initialised seasonal SST forecasts were little different from expectations under climate change projections and trend persistence.

How to cite: Holbrook, N.: Just another Tasman Sea marine heatwave?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6880, https://doi.org/10.5194/egusphere-egu24-6880, 2024.

EGU24-7402 | ECS | Orals | OS1.10 | Highlight

Future Intensification of Marine Heatwaves in Marine Protected Areas 

Eun Byeol Cho, Eun Young Kwon, and Axel Timmermann

Marine Protected Areas (MPAs) are designated areas aimed at preserving marine ecosystems. However, they encounter the persistent obstacle of increasing ocean temperature. The occurrence of extreme warming events, known as Marine Heatwaves (MHWs), poses a significant threat to the delicate balance of marine ecosystems within MPAs. To understand the future changes in marine heatwaves (MHWs) in these regions, it is crucial to utilize advanced climate modeling capable of accurately capturing regional bathymetric features in MPAs, like coastlines, continental shelves, or islands. In this study, we utilized the SSP585 greenhouse warming simulations conducted with the OpenIFS-FESOM2 coupled model (AWI-CM3, 31 km atmosphere resolution, 4-15 km ocean resolution) to explore future changes in MHWs in the epipelagic to the upper mesopelagic zones (0-500m depth) of the global MPAs. In the current climate, MHWs in the MPAs exhibit greater maximum intensity and higher frequency than the global averages. However, MHWs in MPAs have shorter durations, leading to a lower cumulative intensity. The average warming rate within the MPAs is similar to or slightly lower than the average warming rate of the global ocean. Nevertheless, the MPAs are expected to see a 20% greater increase in the cumulative intensities of MHWs compared to the global ocean, from the past to the future. The findings suggest that marine protected areas (MPAs) are more susceptible to extreme temperature events compared to open ocean zones. Our findings underscore the significance of addressing anthropogenic warming to safeguard MPAs, emphasizing the need for prompt measures to mitigate these impacts and protect these vital marine ecosystems. 

How to cite: Cho, E. B., Kwon, E. Y., and Timmermann, A.: Future Intensification of Marine Heatwaves in Marine Protected Areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7402, https://doi.org/10.5194/egusphere-egu24-7402, 2024.

EGU24-7671 | ECS | Orals | OS1.10

The 2023 marine heatwave in the North Atlantic and the Mediterranean Sea: ocean response to atmospheric circulation 

Lorine Behr, Elena Xoplaki, Niklas Luther, Elina Tragou, Jürg Luterbacher, and Vassilis Zervakis

The year 2023 was characterized by record-breaking global surface air and sea surface temperatures (SSTs), the latter reaching a record 21° C in April (excluding the polar regions; Copernicus 2023). As June to October were the warmest on record globally (WMO 2023), extreme and long-lasting marine heatwave (MHW) events were observed, especially in the North Atlantic and the Mediterranean Sea. In general, the occurrence of MHWs in the subtropics and western boundary current regions is predominantly driven by atmospherically induced processes such as the net ocean heat uptake from the atmosphere, associated with a reduction in latent heat loss and increased shortwave radiation (Schlegel et al. 2021; Vogt et al. 2022). The atmospheric circulation with persistent high‑pressure systems and anomalously weak wind speeds associated with increased insolation is the dominant driver of the above processes. We focus on the state of the atmosphere at the surface and in the mid-troposphere during 2023 and identify specific atmospheric patterns and SST anomaly structures. To detect MHWs and calculate their characteristics we use the daily gridded NOAA OI SST version 2.1 dataset (Huang et al. 2021, updated), derived from the AVHRR satellite, in-situ ship and buoy SST data. For the atmospheric component, we used the mean sea level pressure (SLP), the horizontal wind at 10 m, the geopotential height at 500 hPa (zg500) and the 2 m maximum temperature (Tmax) from the ECMWF ERA5 reanalysis (Hersbach et al. 2020, updated). Atmospheric and ocean datasets are provided globally with a high resolution (0.25°). We use daily anomalies with 1983 to 2012 as the reference period (as recommended by Hobday et al. 2018). The evaluation of MHW metrics such as frequency, duration, mean and cumulative intensity in different subregions of the North Atlantic and Mediterranean revealed that the most frequent MHWs were observed in the western Mediterranean (WMED), the longest MHWs in the central northeast Atlantic and the cumulatively most intense MHWs in the northwest Atlantic and central northeast Atlantic. The most intense MHWs are found in the WMED and off Newfoundland. During summer we detect asynchronous, above normal SLP, zg500 and Tmax over the northwest Atlantic, the WMED and the Black Sea, representing a type of blocking condition. A weakened Azores High, associated with reduced wind speed, mixing and upwelling, allows SSTs to rise substantially in the central northeast Atlantic during summer (Copernicus 2023). The first Empirical Orthogonal Function shows an antiphase dipole of SST and zg500 anomalies (explained variances of 43.9 % and 34.3 %, respectively) between the Mediterranean and West of the British Isles as well as monopol SST and zg500 anomalies (explained variances of 57.7 % and 41.9 %, respectively) over the northwestern Atlantic and the Labrador Sea.

How to cite: Behr, L., Xoplaki, E., Luther, N., Tragou, E., Luterbacher, J., and Zervakis, V.: The 2023 marine heatwave in the North Atlantic and the Mediterranean Sea: ocean response to atmospheric circulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7671, https://doi.org/10.5194/egusphere-egu24-7671, 2024.

EGU24-8423 | ECS | Orals | OS1.10

Mechanism and Forecast Potential of North Pacific Marine Heatwaves inferred from Adjoint Sensitivities 

Xiaoxue Wang, Armin Köhl, and Detlef Stammer

The increasing frequency and intensity of heatwave events have led to a significant rise in heat-related threads on land and in the ocean during recent years. A classic example of a marine heat wave (MHW) is the 2014 – 2016 warm event that spread across the northeastern Pacific (NEP) Ocean—an event that researchers coined “the blob”. Here we use an adjoint sensitivity approach to shed new light on potential causes for reoccurring NEP marine heatwaves events in the region of the NEP. The study is based on the Massachusetts Institute of Technology general circulation model (MITgcm) and its adjoint, for which the mean sea surface temperature (SST) of different target regions (region 1: 145°~ 160°W, 48°~ 56°N; region 2: 130°~ 145°W, 40°~ 48°N) and different target years (e.g. year 2014) was set as objective function. The adjoint sensitivities show that during the year of emergence, air-sea turbulent surface heat flux is the dominant atmospheric driver. The horizontal temperature advection, i.e., the impact of the basin-wide ocean circulation, is found to be less important, but might act as a preconditioning of MHW through climate oscillations (e.g. NPGO). Because atmospheric forcing anomalies occurring within the 18 months prior to the MHW event play a particularly critical role in driving the overall response locally through air-sea interactions, the leading 18 month atmospheric conditions in the central North Pacific can be considered as predictive signals for later marine heatwave events. Based on our preliminary findings, it can be concluded that 2024 may not be a heatwave year for NEP region. 

How to cite: Wang, X., Köhl, A., and Stammer, D.: Mechanism and Forecast Potential of North Pacific Marine Heatwaves inferred from Adjoint Sensitivities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8423, https://doi.org/10.5194/egusphere-egu24-8423, 2024.

EGU24-10707 | ECS | Orals | OS1.10

Investigating the role of air-sea heat flux for marine heatwaves in the Mediterranean Sea 

Dimitra Denaxa, Gerasimos Korres, Giulia Bonino, Simona Masina, and Maria Hatzaki

The Mediterranean Sea (MS) has been experiencing progressively intensified Marine heatwave (MHW) conditions over the past decades, associated with severe environmental and socioeconomic impacts. Building upon prior research on physical mechanisms underlying the occurrence of MHWs, here we assess the relative role of air-sea heat exchange in driving the onset and decline phases of surface MHWs in the basin, utilizing remote sensing and reanalysis data for the period 1993-2022. Although contributing positively to the SST evolution during most MHWs, surface heat flux is identified as the primary driver in less than half of the onset/decline MHW phases. This finding suggests that oceanic processes play a crucial role in driving SST anomalies during MHWs in the basin. The role of surface heat flux becomes more pronounced during onset periods and warmer seasons, with the latent heat being the most significant heat flux component in modulating SST anomalies during both MHW phases and across all seasons. Heat flux emerges as the major driver of most onset phases in the Adriatic and the Aegean Seas. Onset/decline phases shorter than 5 days exhibit a weaker heat flux contribution compared to longer phases. Moreover, an inverse relationship between event severity and heat flux contribution is observed. At the subsurface, mixed layer shoaling is observed over the entire duration of most events, particularly for those of shorter duration. Therefore, the surface cooling right after the peak intensity day is likely not associated with vertical mixing in such cases. After the MHW end day, a significant mixed layer deepening in most cases suggests that further dissipation of heat is commonly driven by vertical mixing. This study emphasizes the need for considering subsurface information for MHW studies and accounting for limitations associated with the definitions employed for MHW phases. Clearly articulating such choices, tailored to the specific contexts of individual studies, is vital for precise interpretation and meaningful comparisons across different studies on MHW drivers.

How to cite: Denaxa, D., Korres, G., Bonino, G., Masina, S., and Hatzaki, M.: Investigating the role of air-sea heat flux for marine heatwaves in the Mediterranean Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10707, https://doi.org/10.5194/egusphere-egu24-10707, 2024.

EGU24-12034 | ECS | Orals | OS1.10 | Highlight

The increased likelihood of plankton community changes following marine heatwaves 

Ryan Deeley, Tobias Grafke, and Ulrike Feudel

When modelling any climatic system, it is important to carefully consider the relation between the many timescales that govern its evolution, since a certain change in their interplay can drastically affect the likelihood of observing critical transitions to distinct environmental regimes. In this study, we present how the onset of marine heatwaves - that are responsible for inducing prolonged periods of positive temperature fluctuations - can weaken state-based resilience leading to noise-induced shifts between species’ concentration levels in plankton communities. This is shown in a modified Truscott-Brindley model, a stochastically forced fast-slow system that encapsulates the interaction between phytoplankton and zooplankton species during red tide events in marine environments. Deterministically, the system can be bistable, possessing stable states with high and low phytoplankton biomass, or in an excitable monostable regime, where phytoplankton blooms form following perturbations. Environmental perturbations to the (temperature-dependent) species’ growth rates are modelled using multiplicative noise terms, namely Ornstein-Uhlenbeck processes with a correlation time parameter τ. During marine heatwaves, the correlation time τ of the external perturbations will increase. With ensemble Monte Carlo simulations of phytoplankton collapses, we demonstrate how mean first-exit times from the domain of attraction scale as the noise intensity weakens, across different prescribed values for the correlation time τ. These results yield numerical approximations for the systems’ quasipotential barrier heights - a concept from Freidlin and Wentzell’s theory of large deviations that quantifies resistance to noise-induced escape from a given domain - which elucidates a non-monotonic relation between the system vulnerability to critical transitions and the correlation time τ of the external perturbations. Indeed, initially there is a notable drop in system resilience as the correlation time τ grows from zero, although as τ increases further beyond a critical value, the system resilience begins to then increase. This non-monotonic relation is also reflected in the action values of most probable transition paths for escaping the domain of attraction, found using an augmented Lagrangian method to overcome the degenerate noise present in the system. These findings are compared and contrasted with results from other studies exploring how climate tipping points, or stochastic escapes from a domain of attraction, depend on the correlation time of the external perturbations. Finally, we consider candidate time-series for correlation times constructed from temperature records for the North Sea across periods including anomalously high values, and discuss whether - subject to these - varying system vulnerability to critical transitions is more sensitive to the rate of emergence or duration of the marine heatwaves.

How to cite: Deeley, R., Grafke, T., and Feudel, U.: The increased likelihood of plankton community changes following marine heatwaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12034, https://doi.org/10.5194/egusphere-egu24-12034, 2024.

EGU24-13423 | Posters on site | OS1.10

Marine heatwaves in the Red Sea: a study of their spatial characteristics, trends and relationships to climate modes 

Manal Hamdeno, Aida Alvera-Azcárate, George Krokos, and Ibrahim Hoteit

Episodes of very warm sea surface temperatures (SST), known as marine heatwaves (MHWs), can potentially alter ocean ecosystems with far-reaching ecological and socio-economic consequences. In this work, we focused on the Red Sea (RS), a region of outstanding socio-economic importance, and investigated its spatio-temporal MHW variability between 1982 and 2021. In addition, the relationship between MHWs and different climate teleconnection patterns was investigated. Our results show that during the study period (1982-2021), the highest frequencies of MHWs were in the southern Red Sea (SRS), while the prolonged and more intense ones were in the northern Red Sea (NRS). By analyzing satellite-derived sea surface temperatures (SST), we identified a warming trend in the RS that began from the mid-1990s, and has intensified since 2016. This temperature increase was accompanied by an increase in the MHW frequency and total days. 78 MHW events with a total of 1016 heat days occurred in the RS between 1982 and 2021, of which 36 events (46%) and 590 days (58%) were recorded in the last decade. In the NRS, the annual MHW frequency was highest in 2010, 2018, 2019 and 2021, while in the SRS it was highest in 1998 and from 2017 to 2021. In cold years, characterized by a negative average SST anomaly, MHWs were mainly found in the NRS. In contrast, in warm years characterized by a positive average SST anomaly, MHWs mainly affected the SRS. However, an exception was observed in 2010, which is considered one of the warmest years in the last four decades. In this year, MHWs were predominantly localized in the NRS, deviating from the typical pattern observed in warm years. The MHW frequency showed a strong positive correlation (> 0.7) with the Atlantic Multidecadal Oscillation (AMO) over the entire RS and a positive correlation (> 0.4) with the Indian Ocean Dipole Index (IOD), which was more pronounced in the SRS, whereas it had a negative correlation (< -0.5) with the East Atlantic/Western Russia (EATL/WRUS) pattern, particularly in the NRS. It was noted that 2010 was also an exceptional year for the climate modes as the AMO and IOD were in strong positive phases, and  the EATL/WRUS was in its highest negative phase, both of which may have contributed to the increased MHWs in that year. This study highlights the link between climate patterns and the occurrence of marine heatwaves in the Red Sea and provides valuable insights into this important aspect of climate change.

How to cite: Hamdeno, M., Alvera-Azcárate, A., Krokos, G., and Hoteit, I.: Marine heatwaves in the Red Sea: a study of their spatial characteristics, trends and relationships to climate modes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13423, https://doi.org/10.5194/egusphere-egu24-13423, 2024.

EGU24-14495 | Posters on site | OS1.10

Unraveling the Indian Monsoon's Role in Fueling the Unprecedented 2022 Marine Heatwave in the Western North Pacific 

Qianghua Song, Chunzai Wang, Yulong Yao, and Hanjie Fan

An unprecedented marine heatwave (MHW) event occurred in the middle-high latitude of the western North Pacific in the summer of 2022. We demonstrate that enhanced precipitation thousands of kilometers away fueled this extreme MHW event in July 2022. In the upper atmosphere of the MHW region, a persistent atmospheric blocking system is formed, which reduces convection and cloud cover and increases shortwave radiation at the ocean surface, leading to higher sea surface temperatures. Atmospheric perturbations induced by latent heat release from the extreme precipitation in the Indian summer monsoon region enhance this atmospheric blocking through the propagation of quasi-stationary Rossby waves. Our hypothesis is verified by using a numerical model that is forced with the observed atmospheric anomalous diabatic heating. This study sheds light on how a subtropical extreme event can fuel another middle-high latitude extreme event through an atmospheric bridge.

How to cite: Song, Q., Wang, C., Yao, Y., and Fan, H.: Unraveling the Indian Monsoon's Role in Fueling the Unprecedented 2022 Marine Heatwave in the Western North Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14495, https://doi.org/10.5194/egusphere-egu24-14495, 2024.

EGU24-15499 * | ECS | Orals | OS1.10 | Highlight

Modelling marine heatwaves impact on shallow and upper mesophotic tropical coral reefs  

Nicolas Colombi, Chahan M. Kropf, Friedrich A. Burger, David N. Bresch, and Thomas L. Frölicher

Coral reefs ecosystems, often compared to rain forests for their high biodiversity, are threatened by coral bleaching. Coral bleaching occurs when the symbiotic relationship between dinoflagellates and corals breaks under environmental stresses, notably high ocean temperatures. Thermal stress on coral reefs predominantly occurs during marine heatwaves, which can take place synchronously at the surface and subsurface, or asynchronously in either one of the two levels. Subsurface marine heatwaves tend to last longer with potentially higher cumulative intensities compared to their surface counterpart. However, to the best of our knowledge, no global coral bleaching model takes into account the variability between the thermal stress measured at the surface and the one experienced by coral reefs at their specific depth. Here we show that developing a marine heatwave impact model for shallow and upper mesophotic coral reefs, increased coral bleaching modelling accuracy by 4.7 ± 1.3% compared to a model using surface marine heatwaves. To define marine heatwaves at coral reef depth, we used trilinear interpolation using the GLORYS12 reanalysis temperature product. Our model provides coral bleaching values at times and locations where no record was taken, providing a global reconstructed dataset of coral bleaching with daily resolution from January 1st 1993 to December 31st 2020 in 9944 locations. Furthermore, our model indicates that since 1993 over 40% of coral reefs bleached. We anticipate this study to be a starting point for more accurate coral bleaching modelling. Observing that upper mesophotic coral reefs (30-50m) might be more threatened than shallow coral reefs, provides additional evidence to reshape our perception of upper mesophotic coral reefs as potential refugees from climate change.

How to cite: Colombi, N., Kropf, C. M., Burger, F. A., Bresch, D. N., and Frölicher, T. L.: Modelling marine heatwaves impact on shallow and upper mesophotic tropical coral reefs , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15499, https://doi.org/10.5194/egusphere-egu24-15499, 2024.

EGU24-16606 | ECS | Orals | OS1.10 | Highlight

Vertical structures of global marine heatwaves 

Ying Zhang, Yan Du, Ming Feng, and Alistair J. Hobday

A marine heatwave (MHW) is typically defined as an anomalous warm event in the surface ocean, with wide-ranging impacts on marine and socio-economic systems. The surface warming associated with MHWs can penetrate into the deep ocean; however, the vertical structure of MHWs is poorly known in the global ocean. Here, we identify four main types of MHWs with different vertical structures using Argo profiles: shallow, subsurface-reversed, subsurface-intensified, and deep MHWs. These MHW types are characterized by different spatial distributions with hotspots of subsurface-reversed and subsurface-intensified MHWs at low latitudes and shallow and deep MHWs at middle-high latitudes. These vertical structures are influenced by ocean dynamical processes, including oceanic planetary waves, boundary currents, eddies, and mixing. The area and depth of all types of MHWs exhibit significant increasing trends over the past two decades. These results contribute to a better understanding of the physical drivers and ecological impacts of MHWs in a warming climate. 

How to cite: Zhang, Y., Du, Y., Feng, M., and Hobday, A. J.: Vertical structures of global marine heatwaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16606, https://doi.org/10.5194/egusphere-egu24-16606, 2024.

An extreme event, Marine heatwave, has become a pressing concern in recent years. It is defined as a discrete event where the sea surface temperature remains above a specific threshold value of climatology for several consecutive days, and the intervals between two consecutive abnormal high-temperature events are less than two days. Due to climate change, there is an increasing trend in both the intensity and duration of marine heat waves. Marine heatwaves may not directly affect human society; however, they can pose significant threats to marine ecosystems, coastal communities, and the ocean carbon sink, thereby impacting human well-being. The ocean carbon sink is the most significant carbon sink among the world's three major carbon sinks. It absorbs around 25% of anthropogenic carbon dioxide emissions annually. Dissolved inorganic carbon within the ocean carbon sink relies on the carbon sequestration of biological pumps such as coral, seagrasses, and kelps to store it in the deep water. Influenced by the El Niño-Southern Oscillation and currents, the northeastern Pacific Ocean is a hotspot for marine heatwaves, typically beginning from the North Pacific offshore regions in the spring and impacting the U.S. West Coast in the fall. Consequently, the coastal area of California is selected as the study area and divided into three regions.

Previous studies have shown that the escalating severity of marine heatwaves may result in these biological pumps losing their functions or habitats. However, regarding ocean carbon sequestration, whether the incapacities of these biological pumps due to marine heatwaves will have a short-term impact on the carbon sequestration capacity in the ocean remains to be verified. This study aims to analyze the time series of marine heatwaves and ocean carbon sink capacity with the time series analysis and determine the impacts on ocean carbon sink. We categorize marine heatwave extreme events in California into three indicators and the ocean carbon sequestration capacity into physical and biological indicators. Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN) is employed to extract the trends and interannual variations. Meanwhile, to identify the correlations between the marine heatwave and the ocean carbon sink at different time points and different time scales, we apply Time-Dependent Intrinsic Correlation (TDIC). Due to the longer temporal scales in changes in the ocean, the impact of marine heatwaves on the ocean carbon sink may have a potential delay. Therefore, we employ Time-Dependent Intrinsic Cross-Correlation (TDICC), a method based on TDIC that could be utilized to analyze the time-lag effects in the interaction between marine heatwaves and the ocean carbon sink.

How to cite: Fu, C.-H. and Tsai, C. W.: Impact of Marine Heatwaves on Ocean Carbon Sink: A Case Study of Coastal Areas in California, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16628, https://doi.org/10.5194/egusphere-egu24-16628, 2024.

The oceanographic and climate communities are putting significant effort into reaching a consensus on a common definition for Marine Heatwaves (MHW). The absence of such a unified definition poses a substantial obstacle when it comes to making retrospective comparisons between various MHW studies. This hindrance is critical for achieving a mechanistic understanding of the role of MHWs in marine ecosystems.

However, why is it so challenging to characterize and define MHWs? The answer is straightforward: there isn't a single, distinct dynamical mechanism responsible for the persistence of heat anomalies in the ocean, which we refer to as MHWs. Unlike variability associated with phenomena such as large oceanic eddies, oceanic fronts, upwelling systems, tropical cyclones, or climate modes, prolonged heat anomalies do not exhibit characteristic time or spatial scales. As a result, common MHW definitions group together prolonged temperature anomalies lasting from days to years and spanning from a few kilometers to thousands of kilometers in scale.

Analyzing sea surface temperature anomalies through power spectra reveals a "red" power spectrum with no discernible time scales. A similar analysis in spatial dimensions similarly shows a lack of any specific scale. Given this absence of emergent scales, we suggest adopting a process-based definition for MHWs. Such an approach would classify all events into a smaller number of categories, each linked to a specific driver or dynamical process operating on certain spatiotemporal scales. This shift could significantly reduce the subjectivity involved in selecting the temporal and spatial scales required for current MHW definitions, ultimately advancing our understanding of these events.

How to cite: Liguori, G.: The need to adopt process-based or impact-based definitions for marine heatwaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17696, https://doi.org/10.5194/egusphere-egu24-17696, 2024.

EGU24-18946 | Orals | OS1.10

Towards monitoring subsurface marine heatwaves based on sea surface properties in the Eastern Pacific 

Eike E. Köhn, Matthias Münnich, Meike Vogt, and Nicolas Gruber

As marine heatwaves (MHWs) become a growing concern for marine ecosystems, an effective ecosystem management necessitates precise monitoring of such periods with exceptionally high water temperatures. As satellite-based temperature measurements do not reach beyond the sea surface, identifying subsurface MHWs has so far relied on lower-resolution data obtained from (autonomous) in-situ measurements. In this study, we assess to which extent subsurface MHWs, defined statically by a seasonally varying 90th percentile, can be deduced from surface properties that can be remotely-sensed at a high spatio-temporal resolution. To this end, we build a Random Forest (RF) classification model with daily data from a high-resolution numerical hindcast simulation focused on the Eastern Pacific (1979-2019). The RF is trained to distinguish between extreme and non-extreme temperatures at the depth of the climatologically maximum mixed layer depth (MLD), i.e. a depth that is decoupled from the sea surface throughout most parts of the year. We train the RF on the first 80% of the hindcast simulation data (i.e., 1979-2011) and use a range of predictor variables, such as anomalies of sea surface temperature (SST), height (SSH) and salinity (SSS) as well as derivatives of these physical variables. Testing the model on the last 20% of the hindcast simulation (2012-2019), the RF correctly identifies more than two thirds of all subsurface extreme states, leaving only about 30% of subsurface extremes unidentified. Yet, of all RF-based subsurface extreme classifications, about 40% of subsurface temperatures are false positives. Nevertheless, the RF model outperforms a simple SST based extrapolation of extreme states into the ocean interior. The RF-based classification is mostly guided by SSH and SST anomalies (together reduce impurity by about 50%), followed by climate indices like the Oceanic Niño Index (ONI) and the Pacific Decadal Oscillation (combined impurity reduction by 20%). This simulation-based study emphasizes the potential of exploring remote sensing data, particularly SST and SSH, to extend the monitoring of MHWs beneath the sea surface. Integrating this high-resolution statistical estimate with lower-resolution in-situ hydrographic information has the potential to make subsurface MHW monitoring a feasible and valuable tool for marine ecosystem management.

How to cite: Köhn, E. E., Münnich, M., Vogt, M., and Gruber, N.: Towards monitoring subsurface marine heatwaves based on sea surface properties in the Eastern Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18946, https://doi.org/10.5194/egusphere-egu24-18946, 2024.

EGU24-20695 | Orals | OS1.10

Marine Heatwaves in the Chesapeake Bay: Characteristics, Subsurface Structure and Impact on Hypoxia 

Piero Mazzini, Nathan Shunk, Cassia Pianca, and Ryan Walter

Marine Heatwaves (MHWs) are prolonged events of anomalously warm sea water temperature, and have major detrimental effects to marine ecosystems and the world's economy. Thanks to satellite remote sensing of sea surface temperature, significant advances have been made regarding the characterization and impact of MHWs on global scales, however, these data are typically inadequate to resolve most estuarine environments with complex shorelines and reduced spatial scales. In our work we analyzed a novel data set with over three decades of in situ surface and subsurface temperature records to investigate MHWs in the largest estuary in the US: the Chesapeake Bay. Our major findings will be presented in detail, including MHW characteristics in the Bay, their trends, subsurface structure and impact on Bay hypoxia. Projections of trends found in our work suggest that by the end of the century the Chesapeake Bay will reach a semi-permanent MHW state, when extreme temperatures will be present over half of the year, and thus could have devastating impacts to the bay ecosystem and regional economy. Improving our basic understanding of MHWs, their trends and impact on hypoxia in the Chesapeake Bay is necessary to guide management decisions in this valuable environment.

How to cite: Mazzini, P., Shunk, N., Pianca, C., and Walter, R.: Marine Heatwaves in the Chesapeake Bay: Characteristics, Subsurface Structure and Impact on Hypoxia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20695, https://doi.org/10.5194/egusphere-egu24-20695, 2024.

CL3.1 – Future Climate – Climate change: From regional to global

EGU24-672 | ECS | Orals | CL3.1.1

Land-atmosphere coupling induced local moist convection initiation in central Europe 

Noah Breuninger and Kirsten Warrach-Sagi

In Europe, extreme weather events are expected to increase noticeably in frequency, duration, and intensity with the continued warming of the planet's climate. Land-atmosphere feedbacks have been shown to play an important role in the exacerbation of events such as heat waves and droughts. Due to the important role of convective events in local weather an improved understanding of the role that land-atmosphere feedback plays in the development of convection initiation is required.

The heated condensation framework (HCF) enables the quantification of land-atmosphere coupling strength and local convection events in dependence of the temperature and moisture profiles from the ground to the planetary boundary layer height. The HCF is applied to the hourly data from the Weather Research and Forecasting (WRF) model application of the University of Hohenheim (UHOH) within the decadal km-scale regional climate simulations within CORDEX-FPS convection.

The analysis reveals the Po-Valley area as a hotspot of land-atmosphere coupling-induced local convection initiation in central Europe. Further strong wet and dry soil anomalies impact the number of local convection initiation events throughout the studied domain.

How to cite: Breuninger, N. and Warrach-Sagi, K.: Land-atmosphere coupling induced local moist convection initiation in central Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-672, https://doi.org/10.5194/egusphere-egu24-672, 2024.

EGU24-733 | ECS | Orals | CL3.1.1

Highlighting future climate extremes in CMIP6-based convection-permitting simulations over the Black Sea Basin 

Mehmet Baris Kelebek, Fulden Batibeniz, and Barış Önol

The frequency and severity of extreme weather events, including temperature and precipitation extremes, have been increasing globally due to human-induced climate change. The Black Sea Basin (BSB), with its complex topography and strong air-sea interactions, is particularly susceptible to climate change and serves as a hot-spot for studying regional climate extremes. To obtain reliable information in BSB, high-resolution convection-permitting simulations are necessary. In this research, we performed convection-permitting climate simulations for historical (2005–2014) and future (2061–2070) periods to investigate the changes in temperature and precipitation extremes and underlying mechanisms based on the SSP3-7.0 climate change scenario over the BSB. To achieve this, we downscaled the CMIP6-based MPI-ESM1.2-HR outputs to 3 km horizontal resolution using the WRF model. The future simulation demonstrates an increased exposure to warm extremes as indicated by the positive change of the TX90P index by about 18% and an increase of the heat wave duration index (HWDI) reaching 55 days per year over the BSB. These changes primarily occur over the highlands of Eastern Anatolia due to enhanced land-atmosphere interactions. In March, a change in low-level circulation leads to a sudden warming of approximately 6°C and an early onset of the melting season, resulting in a 20% reduction in snow cover over Eastern Anatolia. This shift increases extreme temperatures due to a substantial snow albedo feedback caused by a 10% reduction in surface albedo in this area. Furthermore, our analyzes highlight the intensification of daily and sub-daily precipitation along the coastal regions of the Black Sea. Particularly in winter and autumn, the ratio of daily extreme precipitation amounts to the seasonal total precipitation (R90PTOT index) reaches 45% in the future over the eastern Black Sea. Additionally, daily precipitation probabilities shift towards higher values for extreme precipitation amounts in the same area with maximum precipitations exceeding 280 mm/day. At the sub-daily scale, this region experiences an intensification in hourly precipitation throughout the day due to a 22% increase in low-level moisture flux resulting from 1°C warmer sea surface temperatures in winter. The increased extreme precipitation in the autumn is associated with the intensification of afternoon precipitation along the Black Sea coasts of Türkiye. This study emphasizes the importance of convection-permitting climate simulations in improving our understanding of climate extremes in the topographically complex BSB. It provides valuable insights for mitigation and adaptation efforts in this climate change hot-spot.

Acknowledgment: The numerical calculations reported in this paper were fully performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA resources).

How to cite: Kelebek, M. B., Batibeniz, F., and Önol, B.: Highlighting future climate extremes in CMIP6-based convection-permitting simulations over the Black Sea Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-733, https://doi.org/10.5194/egusphere-egu24-733, 2024.

EGU24-1873 | ECS | Posters on site | CL3.1.1 | Highlight

Exploring the climate change influence on short-duration convective precipitation extremes in the southeastern Alpine forelands 

Stephanie Haas, Gottfried Kirchengast, and Jürgen Fuchsberger

Short-duration extreme convective precipitation events (SDECPEs) are increasingly altered by climate change. Considering their severe risk, and high impact on our everyday lives, a profound understanding of such extreme precipitation is crucial. For their investigation we can leverage a newly developed class of Threshold-Exceedance-Amount (TEA) metrics, which enable the detection and tracking of weather and climate extremes. The compound indices based on these TEA metrics have proven to be a useful tool to investigate changes of different characteristics of temperature and precipitation extremes, both in isolation and in combination.

It is challenging, however, to perform such an analysis for SDECPEs, since their short durations of only about one to three hours and their highly localized character make them very weakly detectable in reanalysis datasets like ERA5-Land, with a spatial resolution of the order of 10 km (0.1° x 0.1° grid). High resolution datasets like from the WegenerNet climate station network in southeast Austria (100 m x 100 m, 5 min) and GeoSphere Austria’s INCA dataset (1 km x 1 km, 15 min) are far better suited for this purpose but offer only data over the most recent two decades. To our knowledge, there is currently no dataset that on its own fulfills all three key requirements (high spatial resolution, high temporal resolution, long data record) for the analysis of SDECPEs over time.

To get observations-based insight into the influence of climate change on SDECPEs in the southeast Alpine forelands, in particular their possible amplification, we aimed to bypass and overcome the weaknesses of any single dataset by a study consisting of two parts: (1) the high-resolution exploration of SDECPEs in the well-observed most recent two decades. Here we investigate the relationship between maximum hourly precipitation and average hourly precipitation on SDECPE-days and complement our findings with information about the temperature increase in the study region. (2) We perform a longer-term assessment of the development of SDECPEs based on reanalysis data. Using the knowledge gained from (1), we are able to model maximum hourly precipitation data and compare the changes in event characteristics to the ones of daily precipitation sums.

We show that our approach does reveal some evidence for a climate change induced amplification of SDECPEs in the southeast Alpine forelands. At the same time, the results vary strongly within the study region, mainly due to high natural variability.

How to cite: Haas, S., Kirchengast, G., and Fuchsberger, J.: Exploring the climate change influence on short-duration convective precipitation extremes in the southeastern Alpine forelands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1873, https://doi.org/10.5194/egusphere-egu24-1873, 2024.

This study examines an extreme wind gust event of over 45 m s-1 occurring in the Yangtze River Delta (YRD) in East China on 30 April 2021, which broke the historical record of surface wind speeds of 221 automated weather stations. A high-resolution mesonet of eight radar wind profilers (RWPs) and six triangular regions along the path of the propagating wind gust is utilized to investigate the dynamics of the extreme wind gust event. Downward transport of turbulence and momentum, and the changes in vertical divergence and vorticity distributions during the event are analyzed. Downward momentum transport likely contributes to the formation of a gust front, and the combination of a gust front and a mesocyclone is of significance in the formation of the extreme wind gust in addition to the large-scale environment. Intensification in mesoscale circulation produced by the merging process likely results in new convection initiation, which potentially accelerates the surface wind through intensified wind shear, and ultimately resulting in the occurrence of the extreme wind gust. This study highlights the role of multiscale processes in the formation of extreme wind gust, as well as the advantage of the non-negligible capability of RWP mesonet in monitoring the turbulence and momentum transport during the passage of the extreme wind systems. The RWP mesonet can serve as a good entry point in extreme wind nowcasting and prediction studies in the future.

How to cite: Chen, T.: An Observational Analysis of the Evolution and Structures of an Extreme Wind Gust Event in East China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2517, https://doi.org/10.5194/egusphere-egu24-2517, 2024.

EGU24-2976 | ECS | Posters on site | CL3.1.1

Intensification of mesoscale convective systems in the East Asian rainband over the past two decades 

Puxi Li, Fengfei Song, Haoming Chen, Jian Li, Andreas Prein, and Wenxia Zhang

 As one of the major producers of extreme precipitation, mesoscale convective systems (MCSs) have received much attention. Recently, MCSs over several hotpots, including the Sahel and US Great Plains, have been found to intensify under global warming. However, relevant studies on the East Asian rainband, another MCS hotpot, are scarce. Here, by using a novel rain-cell tracking algorithm on a high spatiotemporal resolution satellite precipitation product, we show that both the frequency and intensity of MCSs over the East Asian rainband have increased by 21.8% and 9.8% respectively over the past two decades (2000-2021). The more frequent and intense MCSs contribute nearly three quarters to the total precipitation increase. The changes in MCSs are caused by more frequent favorable large-scale water vapor-rich environments that are likely to increase under global warming. The increased frequency and intensity of MCSs have profound impacts on the hydroclimate of East Asia, including producing extreme events such as severe flooding. 

How to cite: Li, P., Song, F., Chen, H., Li, J., Prein, A., and Zhang, W.: Intensification of mesoscale convective systems in the East Asian rainband over the past two decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2976, https://doi.org/10.5194/egusphere-egu24-2976, 2024.

EGU24-3009 | ECS | Orals | CL3.1.1

Exploring changes of precipitation extremes under climate change through global variable-resolution modeling 

Wei Sun, Jian Li, Rucong Yu, Nina Li, and Yi Zhang

Understanding the responses of precipitation extremes to global climate change remains limited owing to their poor representations in models and complicated interactions with multi-scale systems. Here we take the record-breaking precipitation over China in 2021 as an example, and study its changes under three different climate scenarios through a developed pseudo-global-warming (PGW) experimental framework with 60–3 km variable-resolution global ensemble modeling. Compared to the present cli- mate, the precipitation extreme under a warmer (cooler) climate increased (decreased) in intensity, cov- erage, and total amount at a range of 24.3%–37.8% (18.7%–56.1%). With the help of the proposed PGW experimental framework, we further reveal the impacts of the multi-scale system interactions in climate change on the precipitation extreme. Under the warmer climate, large-scale water vapor transport con- verged from double typhoons and the subtropical high marched into central China, enhancing the con- vective energy and instability on the leading edge of the transport belt. As a result, the mesoscale convective system (MCS) that directly contributed to the precipitation extreme became stronger than that in the present climate. On the contrary, the cooler climate displayed opposite changing characteris- tics relative to the warmer climate, ranging from the large-scale systems to local environments and to the MCS. In summary, our study provides a promising approach to scientifically assess the response of pre- cipitation extremes to climate change, making it feasible to perform ensemble simulations while inves- tigating the multi-scale system interactions over the globe.

How to cite: Sun, W., Li, J., Yu, R., Li, N., and Zhang, Y.: Exploring changes of precipitation extremes under climate change through global variable-resolution modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3009, https://doi.org/10.5194/egusphere-egu24-3009, 2024.

This contribution focuses on the change in 1h heavy precipitation distribution in response to the increasing air temperature in Czechia (Central Europe). The air temperature, the dew point temperature and the temperature of lifting condensation level are used as temperature characteristics. The change in the distribution of 1h precipitation measurements is compared with the results of reanalyses based on simulations of ALADIN-CZ NWP model and with the results of future climate simulations by ALADIN-CLIMAT-CZ climate model. In general, the increase in heavy precipitation appears clearly in the very upper part of precipitation distribution. Values of the upper percentiles of precipitation increase up to a certain temperature threshold and then they decrease, which is in line with other studies. This is also visible in the simulations of future climate.

How to cite: Sokol, Z. and Popova, J.: Change in the distribution of heavy 1h precipitation due to temperature changes in measured values, model reanalyses and model simulations of future climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3043, https://doi.org/10.5194/egusphere-egu24-3043, 2024.

EGU24-3707 | ECS | Posters on site | CL3.1.1

Combined Radar Quality Index for Quantitative Precipitation Estimation of Heavy Rainfall Events 

Yang Zhang, Liping Liu, and Hao Wen

For quantitative precipitation estimation (QPE) based on polarimetric radar (PR) and rain gauges (RGs), the quality of the radar data is crucial for estimation accuracy. A combined radar quality index (CRQI) is proposed to represent the quality of the radar data used for QPE and an algorithm that uses CRQI to improve the QPE performance. Nine heavy rainfall events that occurred in Guangdong Province, China, were used to evaluate the QPE performance in five contrast tests. The QPE performance was evaluated in terms of the overall statistics, spatial distribution, near real-time statistics, and microphysics. CRQI was used to identify good-quality data pairs (i.e., PR-based QPE and RG observation) for correcting estimators (i.e., relationships between the rainfall rate and the PR parameters) in real-time. The PR-based QPE performance was improved because estimators were corrected according to variations in the drop size distribution, especially for data corresponding to 1.1 mm < average Dm < 1.4 mm, and 4 < average log10 Nw < 4.5. Some underestimations caused by the beam broadening effect, excessive beam height, and partial beam blockages, which could not be mitigated by traditional algorithms, were significantly mitigated by the proposed algorithm using CRQI. The proposed algorithm reduced the root mean square error by 17.5% for all heavy rainfall events, which included three precipitation types: convective precipitation (very heavy rainfall), squall line (huge raindrops), and stratocumulus precipitation (small but dense raindrops). Although the best QPE performance was observed for stratocumulus precipitation, the biggest improvement in performance with the proposed algorithm was observed for the squall line.

How to cite: Zhang, Y., Liu, L., and Wen, H.: Combined Radar Quality Index for Quantitative Precipitation Estimation of Heavy Rainfall Events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3707, https://doi.org/10.5194/egusphere-egu24-3707, 2024.

EGU24-3771 | Posters on site | CL3.1.1

Summer and tropical consecutive days in normal periods 1961-1990 and 1991-2020. 

Pavel Faško, Oliver Bochníček, and Ladislav Markovič

Summer and tropical days were and are part of the processing of historical observations. Their processing was the content of each monthly report of meteorological observations as well as the annual processing in the form of a yearbook. Changes in temperature (especially positive deviations from normal values) also cause their more frequent occurrence. This would not be unusual or unexpected, even if the regularity of these periods cannot be predicted. Higher air temperatures often cause health problems, especially for older and more sensitive people. Nausea and loss of concentration occur especially during longer periods of hot days. In this contribution, we decided to process the occurrence of periods of summer days (t_max≥25 °C) and periods of tropical days (t_max≥30 °C). The term period here means consecutive days (minimum 2). Professional and aerial meteorological stations covering the territory of Slovakia well were selected. Their length was considered for two normal periods, namely 1961-1990 and 1991 - 2020. The mutual comparison gave us a clear idea of the redistribution of periods of different lengths and the territorial unit (places in Slovakia). While for summer days we observe a decrease in shorter periods and an increase in longer periods, especially in lowland areas, in the rest of the territory, especially in the north, or in mountainous areas, rather an increase even from the shortest periods.

On tropical days, or when comparing the periods of tropical days in both normal periods (1961 - 1990 and 1991 - 2020), we find the fact of a very strong increase from the shortest periods of consecutive tropical days at all selected meteorological stations. Since it is impossible to compare the frequency of periods as well as the number of tropical days themselves in absolute terms, we helped ourselves with a percentage evaluation. The fact is that, especially for tropical days, the biggest increase is in the north of the country, the shortest periods (2-3 days in a row) increased by up to 250%. They even began to appear in places where they could not be observed in the period 1961 - 1990. The results conceived in this way will help not only the tourism industry, but also the adaptation of man and his environment to changes in the climate system.

 

How to cite: Faško, P., Bochníček, O., and Markovič, L.: Summer and tropical consecutive days in normal periods 1961-1990 and 1991-2020., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3771, https://doi.org/10.5194/egusphere-egu24-3771, 2024.

EGU24-4436 | ECS | Orals | CL3.1.1

How Could Lake-Effect Snow Storms Evolve in a Warming Future Climate? 

Miraj Kayastha, Pengfei Xue, Chenfu Huang, Jiali Wang, Zhao Yang, William Pringle, Tirthankar Chakraborty, Yun Qian, and Robert Hetland

When cold, dry air travels over a relatively warmer lake, lake-effect snow (LES) develops due to an increase in moisture flux from the lake to the atmosphere, which in turn promotes cloud formation and subsequent precipitation. A destructive LES storm struck the Buffalo region in New York, from November 17-20, 2022. Buffalo, located at the eastern end of Lake Erie and subject to winter winds that sweep across the lake, was inundated with nearly 7 feet of snow, prompting the declaration of federal emergencies by multiple counties. The LES storm highlighted the need for at-risk communities to enhance their preparedness for comparable future incidents. Using a cloud-resolving 4 km scale, we investigated how such an LES storm might manifest in a warmer future climate by employing the Pseudo-Global Warming (PGW) method and a two-way coupled lake-atmosphere regional climate modeling system. The modeling system comprises a two-way coupled Weather Research and Forecasting (WRF) model and a Finite Volume Community Ocean Model (FVCOM)-based three-dimensional lake model. Under the PGW methodology, the future atmospheric forcing necessary for our regional climate modeling system was derived from a reanalysis climate dataset by incorporating projected atmospheric changes from a variety of CMIP6 earth system models. Furthermore, we integrated the warming signals in the lakes by utilizing the projected lake conditions obtained from a regional climate modeling system that was previously established and also incorporated an FVCOM-based lake model. According to our findings, the total storm precipitation for such an event by the end of this century could increase by 14% under a high-emission scenario, with an increase in rainfall at the expense of snowfall. Under the present-day climate conditions, snowfall was the primary type of precipitation experienced during the event. However, in a warmer future climate, the distribution of precipitation might be nearly equal between snowfall and rainfall. By conducting two additional simulations in which either the lake or atmosphere is warmed individually using the projected future conditions, we found that the warmer lakes primarily contributed to the increase in storm precipitation through increased evaporation, while the warmer atmosphere primarily influenced the form of storm precipitation during such an LES storm in the future.

How to cite: Kayastha, M., Xue, P., Huang, C., Wang, J., Yang, Z., Pringle, W., Chakraborty, T., Qian, Y., and Hetland, R.: How Could Lake-Effect Snow Storms Evolve in a Warming Future Climate?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4436, https://doi.org/10.5194/egusphere-egu24-4436, 2024.

EGU24-4916 | Orals | CL3.1.1

Climate variability outweighs influence of climate mean on summer precipitation extremes 

Kalle Nordling, Bjørn Samset, and Nora Fahrenbach

Climate change can involve changes in mean conditions, and in their variability on short to long timescales. But which of the two  is more important for our future climate?  We present a study indicating that for the number of extreme precipitation days, changes in climate variability dominate over  changes in the mean state. This analysis is based on three large ensemble simulations across three CMIP6 models (MPI-ESM1-2-LR, CanESM5, and ACCESS-ESM1-5). Here, we decompose the total changes in daily summer precipitation and daily maximum temperature into mean and variability components (standard deviation and skewness of the daily probability density functions).  Our key findings are that:1) Changes in climate variability (i.e., day-to-day variability of precipitation and changes in the precipitation distribution) have a more pronounced impact on extreme precipitation events than changes in the mean state. 2) In contrast, changes in the mean temperature state play a more dominant role in determining overall changes in daily temperature. These insights  are valuable for understanding the mechanisms driving extreme weather events and  highlight the need to consider daily variability changes in climate change impact assessments.

How to cite: Nordling, K., Samset, B., and Fahrenbach, N.: Climate variability outweighs influence of climate mean on summer precipitation extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4916, https://doi.org/10.5194/egusphere-egu24-4916, 2024.

The Analysis of Different Spatial-temporal Rainfall Characteristics and Drought Disaster Risk Assessment in Penghu Area

 

Keywords: Empirical Orthogonal Function, Wavelet Analysis, Standardized Precipitation Index, Drought

 

Under the impact of extreme climate and the trend of global warming, the frequency of natural disasters has increased, and extreme rainfall and extreme drought events have gradually increased, causing threats to human life, food shortages, and ecological catastrophes. In recent years, with the development of tourism industry in Penghu, the demand for water resources has increased, but available surface water sources are very scarce. At present, Penghu’s freshwater source is mainly seawater desalination, but this method is likely to affect Penghu’s unique coral reef marine ecology.

This study uses data mining methods to analyze rainfall characteristics and drought trends. Rainfall characteristic analysis uses empirical orthogonal function (EOF) and wavelet analysis (WA), and drought trend analysis uses the Standardized Precipitation Index (SPI) at different time scales. The results show that the rainfall characteristics of South Penghu Marine National Park and Penghu Island are different, and the rainfall difference between drought years and non-drought years is large. The drought index shows that in recent years, South Penghu Marine National Park is still in a relatively dry state, with a higher drought frequency than Penghu Island and Taiwan Island. The risk of agricultural drought and hydrological drought is high on a medium to long time scale. Therefore, special attention needs to be paid to the rainfall situation in South Penghu Marine National Park.

How to cite: Hsin-Wen, P. and Yuan-Chien, L.: The Analysis of Different Spatial-temporal Rainfall Characteristics and Drought Disaster Risk Assessment in Penghu Area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4924, https://doi.org/10.5194/egusphere-egu24-4924, 2024.

EGU24-6617 | ECS | Posters on site | CL3.1.1

Two-stage non-linear approach in the analysis of precipitation time series  

Beatrice Lioi, Krzysztof Kochanek, Tiziana Bisantino, and Vito Iacobellis

An increasing perception of climate change both on a global and local scale, accompanied by the increase in observed average surface temperature of the oceans, and by the increased frequency of extreme events in different territories, creates the necessity of developing hydrological tools and models within the framework of non-stationarity. This study analyses the daily and hourly rainfalls recorded in Puglia (Southern Italy). In scientific literature the widely used non-parametric Mann-Kendall (MK) test is suggested to identify monotonic trends, then followed by the application of a further non-parametric measure of trend, the Sen's Slope. Indeed, in parametric methods the non-stationary character is exercised with the addition of the temporal variable (co-variant) t in the probability distribution. In this framework the Two-Stage (TS) method allows to tackle this problem by associating the linear or non-linear temporal dependence to both mean and standard deviation of time series (Kochanek et al., 2013). In this field, we propose an advancement of the TS methodology by introducing a polynomial function in the mean trend, leaving the variance trend linear. The obtained results represent the first non-linear application of the TS method in a non-stationary approach to extreme events. With such application of the TS method, we show how to update the evaluation of quantiles with 5 or 10 years return time, in the aim of a technical application to hydraulic risk management and urban planning.

How to cite: Lioi, B., Kochanek, K., Bisantino, T., and Iacobellis, V.: Two-stage non-linear approach in the analysis of precipitation time series , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6617, https://doi.org/10.5194/egusphere-egu24-6617, 2024.

EGU24-6792 | Orals | CL3.1.1

Exploring Continental Convection-Permitting Model Simulations for South America: Cross-correlation Dynamics between precipitation and temperature time series at São Paulo 

Kwok Pan Chun, Thanti Octavianti, Hristos Tyralis, Georgia Papacharalampous, Rosmeri Porfirio da Rocha, Emir Toker, Yasemin Ezber, Luminita Danaila, Kate Halladay, and Ron Kahana

Increasing spatial resolution to kilometre scales allows the deactivation of deep convection parameterisation schemes. As a result of various global initiatives for the next generation of climate studies, continental convection-permitting model (CPM) simulations are now accessible. Nonstationary local extremes, like heatwaves and intense precipitation, are probabilistically linked to regional circulation through scaling relationships. However, these relationships have not been extensively explored in the new simulations available in the early 2020s. Hourly time series data were extracted from the UK Climate Science for Service Partnership (CSSP) and the US South America Affinity Group (SAAG) CPM simulations to compare extreme characteristics of precipitation and temperature for 39 stations in a region of São Paulo, Brazil. Compared to reanalysis and satellite data, which exhibit lower variance in hourly time series, these two sets of CPM simulations have precipitation that is more similar to station observations than the ERA5 data and the Integrated Multi-satellitE Retrievals for the Global Precipitation Measurement (IMERG) data.

The cross-correlation structures of the time series are investigated to quantify temporal dependence and reveal patterns between temperature and precipitation at an hourly timescale. Within a higher-dimensional probability space for joint risk, the cross-correlation structures between temperature and precipitation at different lags demonstrate the "memory" of these variables, indicating the influence of past values on future behaviour across multiple time points. Their forecasting power for these two variable based on each other is also explored to offer insights into the physical processes within the evolving simulated dynamic system.

Overall, the results underscore the added value of convection-permitting models in providing more realistic simulations of local dynamics of extremes. The identified cross-correlation structures from the CPMs are valuable for exploring opportunities to design AI engines based on weather generator algorithms that use stochastic differential equations. Using CPM simulations, these weather generators can be employed to develop AI approaches for rapid decision support tools aimed at stakeholders facing extreme weather events related to compound risks of temperature and precipitation.

How to cite: Chun, K. P., Octavianti, T., Tyralis, H., Papacharalampous, G., da Rocha, R. P., Toker, E., Ezber, Y., Danaila, L., Halladay, K., and Kahana, R.: Exploring Continental Convection-Permitting Model Simulations for South America: Cross-correlation Dynamics between precipitation and temperature time series at São Paulo, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6792, https://doi.org/10.5194/egusphere-egu24-6792, 2024.

Extreme precipitation events can cause flooding in central European river catchments. Climate simulations show that extreme precipitation, especially towards longer return periods, will intensify in a warmer climate for most parts of Europe. In order to study the mechanisms leading to the intensification of particularly extreme events, we investigate 10-year daily precipitation events over five major central European river catchments in Community Earth System Model Large Ensemble simulations. A statistical evaluation and comparison of large-scale circulation patterns associated with the events with operational ensemble weather prediction data from the ECMWF indicate a realistic representation of the 10-year extreme events in the climate model. Differences in these circulation patterns are analysed between the historical climate of 1990-2000 and a warmer climate at the end of the century (2091-2100). While most events occur in the core summer months (June-August) in the historical climate, there is a broadening of the seasonal distribution with extreme events from May to October in the warmer climate. Precipitation rates increase locally by 5-7%/K, similar to the Clausius-Clapeyron rate, related to significant increases in lower-tropospheric humidity. Averaged over the entire catchments, precipitation still increases, but with lower intensification rates varying between 1.2 and 3.8%/K for the individual catchments. This is due to a combination of thermodynamic and dynamic factors, in particular the shift towards the cold season, associated with smaller temperature increases during the events than expected from the overall warming, and a weakening of vertical motion over parts of the catchments. In future research, the robustness of these findings should be investigated through comparison with other climate simulations.

How to cite: Ruff, F. and Pfahl, S.: Projected future changes of very extreme precipitation events over central European river catchments from ensemble climate simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8043, https://doi.org/10.5194/egusphere-egu24-8043, 2024.

Arthropods play vital roles in the ecosystem (e.g., pollinators, decomposers, biological pest control), and thus can act as indicators of ecosystem integrity. The state of these ecosystems is sensitive to variations in climate conditions, especially on small islands. The Circum-Sicilian islands are a chain of small islands around Sicily in the central Mediterranean. With the use of Convection permitting simulations, many of these islands can finally be adequately resolved. The objective of the project PALEOSIM (PALEOclimate modelling of Small Islands in the Mediterranean and possible impacts on arthropod habitats) is to study climate impacts on the habitats of arthropods (mainly insects) in the Circum-Sicilian islands. To achieve this, RegCM5 is driven by CMIP6 and PMIP4 data for a 3 km region covering the west and central Mediterranean.

Climate indices from the simulations have been used to assess the ecological niche of select arthropod species and hence determine how these conditions have changed across different time scales. The data used to drive RegCM5 allows for the study of time slices across several scenarios, which include: the last glacial maximum, mid-Holocene, ~1000 CE, ~1850 CE, ~1995 CE (a historical baseline), and Global Warming Levels of 1.5, 2, and 3 °C. This analysis reveals how some species are especially sensitive to changes in climate conditions, and the significant threat of the current climate crisis.

How to cite: Ciarlo, J., Coppola, E., Micallef, A., and Mifsud, D.: Climate-induced variations in arthropod habitats of the Circum-Sicilian islands according to convection permitting simulations of the Mediterranean driven by CMIP6 and PMIP4 data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8279, https://doi.org/10.5194/egusphere-egu24-8279, 2024.

EGU24-9342 | Posters on site | CL3.1.1

Convection-Permitting simulations over South America: a look at the uncertainty sources at the sub-daily time scale 

Francesca Raffaele, Erika Coppola, Leidinice Silva, Maria Laura Bettolli, Josefina Blasquez, Jesus Fernandez, Josipa Milovac, Rosmeri Porfirio da Rocha, and Silvina Solman

A set of high resolution simulations have been performed over the La Plata region in South America, and a multi-model ensemble of Convection-Permitting simulations has been produced for a 3-years period (2018-2021). We have used this new high resolution ensemble to investigate more in depth the daily and hourly timescales.

The available satellite and gridded observational datasets show a clear uncertainty  when going to sub-daily timescale, therefore the validation of the model ensemble mean and extreme precipitation is performed by including also a station based observational dataset at both daily and hourly time scale, to assess  the model uncertainty within the context of the aforementioned observational uncertainty.

Moreover, a cluster analysis of the diurnal cycle precipitation has been used as a starting point for a spatial characterization of the precipitation in a region of heterogeneous topography. The ensemble models' performance has been validated inside five different regions in order to spatially homogenize the precipitation regimes at hourly timescales.

The results underlined a good agreement in the model ensemble especially in those areas where the homogenization of the stations is more pronounced.

On the other hand, the spread among models grow when looking at areas characterized by complex orography, thus highlighting the importance of having available a set of simulations as big as possible so that complexity can be represented within the  model uncertainty. 

How to cite: Raffaele, F., Coppola, E., Silva, L., Bettolli, M. L., Blasquez, J., Fernandez, J., Milovac, J., Porfirio da Rocha, R., and Solman, S.: Convection-Permitting simulations over South America: a look at the uncertainty sources at the sub-daily time scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9342, https://doi.org/10.5194/egusphere-egu24-9342, 2024.

In the last 10 years, the very high resolution regional climate models have started to be used and recently the newly available regional climate model ensemble for the Great Alpine region, at the convection permitting (CP-RCM) resolution (> 3 km), has been released by the CORDEX Flagship Pilot Study on Convective phenomena at high resolution over Europe and the Mediterranean (FPSCONV). At such resolution, the improvement of the representation of local hydrological processes becomes relevant because the climate impact on the hydrological cycle at that scale is expected to be much better captured.  

To this aim, the CETEMPS hydrological model (CHyM) is used coupled off-line with the different CP-RCM ensemble members.  The model has been run in two different configurations, using either temperature and precipitation from the driving CP-RCM or directly the runoff. The hydrological simulation ensemble has been validated against local station data for the Po river and central Italian river basins, by using hydrological indicators, such as the Kling–Gupta efficiency (KGE). The climate change projections are compared with previous lower resolution simulation driven by convection parametrized regional climate models from the Euro-CORDEX ensemble.  

How to cite: Vargas-Heinz, L., Coppola, E., and García-Valdecasas Ojeda, M.: Impact of climate change on the hydrological cycle of the Great Alpine region by means of regional climate convection permitting high resolution simulations and hydrological model simulations. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10350, https://doi.org/10.5194/egusphere-egu24-10350, 2024.

The past 10 years of research proved that regional convection-permitting models (RCPMs) more realistically represent sub-daily statistics and extremes compared to GCMs and RCMs thanks to the possibility to switch off the parameterisation of convection at this resolution. Now, thanks to recent computational advancements, GCMs are approaching convection-permitting resolution (GCPM), but little is known on their performance at climatological scale over Europe.

Here we compare two 5-year GCPM simulations performed with IFS and ICON, respectively at 9 and 5km, within the NextGEMs project against the multi-model RCPM ensemble at circa 3 km run under the CORDEX Flagship Pilot project on Convective Phenomena over Europe and the Mediterranean (FPS Convection). The analysis focuses on the representation of sub-daily precipitation characteristics between GCPMs in comparison with the RCPM ensemble and several regional observational datasets over the greater Alpine region. In additional, the impact of a higher resolution (5km instead of 25km) of the ocean model is investigated thanks to an additional GCPM run. The natural variability of the GCPMs is evaluated with a bootstrapping approach and put in relation with the total and model uncertainty of the RCPM ensemble.  

Having GCMs that realistically represent the large-scale dynamics as well as the local scale process would be a crucial step forward and provide further confidence on the climate projections and support the Destination Earth project of the European Community.

How to cite: Fosser, G. and Bordoni, S.: Lessons learnt on convection-permitting models and their uncertainty at both global and regional scale , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10431, https://doi.org/10.5194/egusphere-egu24-10431, 2024.

EGU24-10599 | ECS | Orals | CL3.1.1

Heatwave analysis over the city of Valencia (Spain) for past and future climate change models and scenarios 

Ana Fernandez-Garza, Eric Gielen, Manuel Pulido-Velazquez, Hector Macian-Sorribes, Adria Rubio-Martin, and Dariana Avila-Velasquez

Heatwaves have emerged as an increasingly recurrent extreme meteorological event, in the Mediterranean region and throughout Europe, during the summer. This is attributable to shifts in the distribution and magnitude of temperatures. In particular, the Comunitat Valenciana a region in Spain experienced the last summer its highest temperature, registering a 1.6ºC increase in the monthly average temperature compared to the reference period (1991-2020). On August 10, the historical record was exceeded by 3.4ºC, with temperatures exceeding 40ºC in more than 50% of the territory as reported by the Spanish Meteorological Agency (AEMET). During this climatic event, the Mortality Monitoring (MoMo) system reported a substantial spike in excess deaths, reaching 1,990 in August. This figure significantly exceeded the preceding month’s tally of 686 fatalities and the subsequent month’s count of 186 deaths. This concentration of mortality in the hottest month underscores the severity of the impact.

The analysis of heatwaves is crucial to provide scientific support for the necessary formulation of inform adequate public policies. Additionally, it enables the population to undertake necessary actions to mitigate the adverse effects of high temperatures.

In a context of increasing temperatures due to climate change, foreseeing its future evolution would provide valuable information for better preparedness. The present research analyses future heatwaves and trends in the city of Valencia, Spain. Future temperatures refer to five bias adjusted CMIP6 (Coupled Model Intercomparison Project Phase 6) climate change models across four different scenarios: historical (1979 to 2014), SSP126, SSP370 and SSP585 (2015-2100). Model suitability is evaluated comparing historical runs with reference data from W5E5-ERA5Land. Afterwards, an analysis of future heatwaves is conducted, using the operational definition of heatwave from Spain: periods of at least three consecutive days where maximum temperature exceeds a critical threshold set by each municipality, which in Valencia refers to the 90th percentile of maximum temperatures for the historical period.

For each detected heatwave the selected indicators are: the number, frequency, duration, intensity, amplitude, and risk level associated with these climatic events. Our analysis evaluates how the number of heatwaves vary, as well as to understand the behaviour of heatwaves in Valencia to determine how the risk might evolve in future contexts, and in a future generating a predictive model providing information on their spatial distribution, intensity, duration and severity.

Acknowledgements:

This study has received funding from the: “THE HUT project” (The Human-Tech Nexus – Building a Safe Haven to cope with Climate Extremes), under the European Union’s horizon research and innovation programme (GA No. 101073957).

How to cite: Fernandez-Garza, A., Gielen, E., Pulido-Velazquez, M., Macian-Sorribes, H., Rubio-Martin, A., and Avila-Velasquez, D.: Heatwave analysis over the city of Valencia (Spain) for past and future climate change models and scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10599, https://doi.org/10.5194/egusphere-egu24-10599, 2024.

Convection permitting climate models (CPMs) display much improved present-day rainfall statistics at local scales as compared to common regional and global climate models. Yet, because CPMs are computationally very demanding, runs are short — typically covering 10 to 20 years  only  —  which makes it hard to distinguish the changes due to global warming from the noise due to internal variability. In addition, runs cover a limited set of changes at larger scales as only few global climate models have been downscaled so far. This challenges the representativeness of the results. Here, we discus these issues within the context of the production of the Dutch climate scenarios issued in fall 2023. We use spatial pooling of information to improve signal to noise. To produce scenarios for local rainfall extremes, we combined information from the CPMs with information from CMIP6 and one RCM (RACMO) using a simple scaling framework. From the CPMs we derived sensitivities of changes in rainfall intensity to surface dew point temperature change. By using spatial pooling and by taking out rain frequency change (using wet conditional statistics) a reasonable collapse of the data of 7 CPM simulations could be obtained, with typical dependencies between 1 and 2 times the Clausius Clapeyron relation. The change in rain frequency and the dew point temperature are derived from a  set of RACMO simulations using pseudo-global warming perturbations derived from CMIP6 combined with a simple perturbed physics method. With these RACMO simulations we covered a range in large-scale conditions compatible with CMIP6.  Subsequently, rain intensity change and frequency change are combined using a transformation of the observed rainfall distribution.  In this way, we could produce a set of climate scenarios for daily and hourly precipitation extremes covering a wide range in global change conditions. Besides these changing rainfall statistics, we also analyzed the spatial temporal characteristics of showers in order to investigate whether showers become larger in scale in the future climate.

How to cite: Lenderink, G., de Vries, H., and van Meijgaard, E.: Combining convection permitting modeling results with CMIP6 global climate model results to produce scenarios for local precipitation extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10660, https://doi.org/10.5194/egusphere-egu24-10660, 2024.

Extreme weather and climate events such as heat waves, droughts or heavy precipitation are already impacting urban areas worldwide, and such extremes are expected to become more frequent and/or severe with climate change. For vulnerability assessment and climate resilient urban planning, local decision-makers and stakeholders need high-resolution climate information that is tailored to their needs according to different geographical contexts (e.g. through the representation of mountainous areas, coastal lines or city characteristics). They also need information on the appropriate time scale, from specific events of a few days to decade-long statistics. Today, regional climate information often comes from global climate models that are downscaled to the local scale using statistical tools or regional climate models (RCMs) such as those used in the CORDEX initiative.

Longterm RCM simulations achieve horizontal resolutions of the order of ten kilometers and offer added value in certain respects compared with their global counterparts, but remain insufficient in certain specific geographical contexts such as the representation of cities, highly heterogeneous mountainous areas or along coastlines. The latest generation of RCMs, known as Convection Permitting Regional Climate Models (CPRCMs), now reach a spatial resolution of a few kilometers and can better represent heterogeneous land surfaces, with the potential offering a new quality of climate information better suited to local applications.

Here, we compare some evaluation simulations (e.g. driven by reanalysis) carried out as part of the EURO-CORDEX initiative (12,5 km RCM) and the CORDEX Flagship Pilot Study on Convection (3 km CPRCM) over the period 2000-2009. We analyze their ability to represent the urban climate of different European cities and the differences resulting from choices in urban parameterizations, land cover representation approaches (dominant coverage or fractional approaches) and land cover databases. We show that:

  • For most European cities, RCM simulations have a too coarse resolution; for example, for all coastal cities, the points that should be considered urban are mainly covered by water.

  • CPRCM simulations enable these areas to be better represented thanks to the increased resolution, but there are significant differences depending on how the different land covers are represented in a grid cell and how urban areas are simulated.

  • Depending on the meteorological variables of interest, some of the simpler urban parameterizations (altered slab) give results that are relatively close to the more sophisticated ones (multi-layer urban canyon).

  • While the increased complexity of CPRCM simulations enables urban climate to be better represented, it also increases the differences between simulations and makes it more difficult to quantify uncertainties and synthesize results into a general assessment (which is often needed by decision-makers) underlining the growing need to use ensembles of climate models for impact assessment.

How to cite: Le Roy, B. and Rechid, D.: Added values and uncertainties of convection permitting regional climate model simulations for urban impact studies over Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11048, https://doi.org/10.5194/egusphere-egu24-11048, 2024.

EGU24-11130 | ECS | Orals | CL3.1.1 | Highlight

How does 3°C global warming affect hail over Europe? 

Iris Thurnherr, Ruoyi Cui, Patricio Velasquez, Killian Brennan, Lena Wilhelm, Heini Wernli, Christian R. Steger, and Christoph Schär

Thunderstorm-related severe weather, in particular hail, causes extensive damage to life and infrastructure in the Alpine region. However, changes in hail impact due to a warmer climate are still not fully understood. In the scClim project, convection-permitting regional climate simulations over Europe using the model COSMO with a ~2.2 km horizontal resolution have been conducted for present-day climate conditions (2011-2021) and a climate scenario with a 3°C global warming using a pseudo-global-warming approach. ERA5 reanalyses were used as boundary conditions and a CMIP6 simulation (MPI-ESM1-2-HR) to infer the large-scale climate-change signal. The integrated online diagnostic HAILCAST is used to calculate maximum hail size. The simulations provide total precipitation and maximum hail size estimates every 5 minutes, which allows for hail cell tracking in the climate simulations and the analysis of hail events in a warmer climate. Validation of the present-day simulation against observations of temperature, precipitation and hail shows an overall good model performance. For hail in particular, radar-based, station-based and crowd-sourced observations have been used to assess the model performance in simulating hail on spatial, diurnal and seasonal scales. The validation outcome encourages further study of the climate signal of hail as simulated with the pseudo-global-warming approach. We will show projected changes in the spatial distribution and seasonal cycle of hail over Europe as well as changes in lifetime, storm area and location of hail cells due to a 3°C global warming.

How to cite: Thurnherr, I., Cui, R., Velasquez, P., Brennan, K., Wilhelm, L., Wernli, H., Steger, C. R., and Schär, C.: How does 3°C global warming affect hail over Europe?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11130, https://doi.org/10.5194/egusphere-egu24-11130, 2024.

EGU24-11157 | ECS | Orals | CL3.1.1 | Highlight

Evaluating sub-daily extreme precipitation from an ensemble of convection-permitting simulations: the role of topography. 

Nathalia Correa Sánchez, Eleonora Dallan, Francesco Marra, Giorgia Fosser, and Marco Borga

Past studies have shown that in orographically complex terrain, observed extreme precipitation intensity is impacted by elevation in different ways at different durations. Convection-permitting climate models (CPMs) are receiving increasing attention thanks to the more realistic representation of extreme sub-daily precipitation compared to coarser climate models. Two almost still unexplored themes concern: i) CPMs' ability to represent the observed relationship between precipitation and topography and ii) how the model ensemble uncertainty depends on elevation. To address these questions, we evaluate sub-daily extreme precipitation from an ensemble of eight CPM members (reanalysis-driven simulations) on topographically diverse terrains. We use observed data from rain gauges as benchmark. The analysis is conducted over the Eastern Italian Alps, where a strong relationship between precipitation sub-daily extremes and topography is observed (Dallan et al., 2023). We apply a non-asymptotic statistical approach (Simplified Metastatistical Extreme Value, SMEV) to estimate extreme precipitation return levels and assess their intra-model and inter-model uncertainties using a bootstrapped samples method. It is shown that the ensemble mean describes in a realistic way the precipitation extremes, with fractional standard errors of the mean-over-the-ensemble return levels ranging between 0,16 (24 hrs duration, 2 yrs return time) to 0,41 (1 hr duration, 100 yrs return time). We found that, compared to rain gauges, CPMs systematically underestimate extreme return levels in lowlands, whereas overestimate them at higher altitudes. Nevertheless, the CPMs can capture the relationship between rain depth and elevation, which is particularly important for 1-3 hrs duration. While the intra-model uncertainty decreases systematically with elevation at all durations, a more complex behaviour is observed for both inter-model and total uncertainty. These findings help to characterize the impact of elevation on the ensemble of CPM simulations, which is particularly required for the applications of these simulations for adaptation to future flood risk.

REFERENCES
Dallan, E., Marra, F., Fosser, G., Marani, M., Formetta, G., Schär, C., & Borga, M. (2023). ID56. How well does a convection-permitting regional climate model represent the reverse orographic effect of extreme hourly precipitation? Hydrology and Earth System Sciences, 27(5), 1133–1149. https://doi.org/10.5194/hess-27-1133-2023.

How to cite: Correa Sánchez, N., Dallan, E., Marra, F., Fosser, G., and Borga, M.: Evaluating sub-daily extreme precipitation from an ensemble of convection-permitting simulations: the role of topography., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11157, https://doi.org/10.5194/egusphere-egu24-11157, 2024.

EGU24-11440 | ECS | Orals | CL3.1.1 | Highlight

High-resolution simulation of French Polynesia climate 

Amarys Casnin, Gilles Bellon, Marania Hopuare-Klouman, Cécile Caillaud, Victoire Laurent, and Sophie Martinoni-Lapierre

Islands of French Polynesia, located in the tropical Pacific Ocean, are small – Tahiti, the largest is about 50 km long – and can exhibit complex orography due to their volcanic origin. In order to simulate properly the atmospheric flow and convective motions over these islands, the non-hydrostatic model AROME is used at high-resolution (2.5 km) to produce a 20-year simulation of the climate over the Society Islands as well as part of the Tuamotu archipelago and Austral Islands. This simulation enables to evaluate AROME ability to simulate these island climates, particularly in terms of rainfall and wind.

AROME is significantly better than the quasi-hydrostatic regional climate model ALADIN with coarser resolution (20 km) at simulating the climate of French Polynesia, and provides a better description of this climate than the available gridded observation products.

By comparing model’s precipitation to observed precipitation at weather stations, results generally show a correct simulation of mean daily rainfall and diurnal cycles. There is however a dry bias for windward stations over Tahiti and a wet bias for leeward stations. These biases remain relatively weak and less pronounced than the biases of other gridded datasets such as IMERG and CMORPH satellite estimates.

The model also simulates winds that compare well to in situ observations and other gridded data. The typical island effect on low-level circulation is well simulated by AROME contrary to ERA5 and satellite data.

How to cite: Casnin, A., Bellon, G., Hopuare-Klouman, M., Caillaud, C., Laurent, V., and Martinoni-Lapierre, S.: High-resolution simulation of French Polynesia climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11440, https://doi.org/10.5194/egusphere-egu24-11440, 2024.

Derechos are severe convective storms known for producing widespread damaging winds. While less frequent than in the United States of America (USA), derechos also occur in Europe. The notable European event on 18 August 2022 exhibited gusts exceeding 200 km h-1, spanning 1500 km in 12 hours. This study presents a first climatology of warm-season derechos in France, identifying thirty-eight (38) events between 2000 and 2022. Similar to Germany, derechos in France are associated with a southwesterly circulation and display comparable frequencies. While a suggestive trend of higher late-season frequency and a potential larger proportion of low-intensity events in France are observed, caution is warranted due to the lack of statistical significance arising from a relatively small sample size. The study also examines synoptic and environmental changes linked with analogues of the 500 hPa geopotential height patterns associated with past warm-season derechos, comparing analogues from a relatively distant past (1950–1980) with a recent period (1992–2022). For most events, a notable increase in convective available potential energy (CAPE) is observed, consistent with Mediterranean trends. However, there is no consistent change in 0–6 km vertical wind shear in the recent period. These environmental shifts align with higher near-surface temperatures, altered mid-level atmospheric flow patterns, and often, increased rainfall. The role of anthropogenic climate change in these changes remains uncertain, given potential influences of natural variability factors such as the El Niño Southern Oscillation (ENSO) or the Atlantic Multidecadal Oscillation (AMO).

How to cite: Fery, L. and Faranda, D.: Analyzing 23 years of warm-season derechos in France: a climatology and investigation of synoptic and environmental changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11710, https://doi.org/10.5194/egusphere-egu24-11710, 2024.

EGU24-12016 | ECS | Orals | CL3.1.1 | Highlight

Determining the intensity of future heatwave episodes at urban scales: the case study of the Metropolitan Area of Barcelona 

Sergi Ventura, Josep Ramon Miró, Ricard Segura-Barrero, Fei Chen, Alberto Martilli, Changhai Liu, Kyoko Ikeda, and Gara Villalba

Given that cities concentrate more than half of the global population, it becomes crucial to assess the potential impacts of future climate change on cities. This study employs the Pseudo Global Warming (PGW) methodology to replicate recent heatwave (HW) episodes in the Metropolitan Area of Barcelona (AMB) under projected climate conditions until the year 2100. Initially, we identify all the HW events in the AMB over the past three decades (1991-2020) and simulate these HWs using the high-resolution Weather and Research Forecasting model (WRF) with the urban parameterizations BEP+BEM. 

Subsequently, the HWs observed in the last 30 years are replicated under mid-century (2041-2070) and end-century (2071-2100) climate conditions based on the SSP370 scenario. This scenario considers a future where greenhouse gas emissions and temperatures consistently rise, reflecting current climatic trends and geopolitical realities, including regional conflicts. Anticipated CO2 emissions are forecasted to nearly double from present levels by the year 2100.

The contrast between recent and future HWs is examined not only in terms of temperature and relative humidity but also concerning the synoptic patterns responsible for generating HW conditions. The findings reveal a potential increase in geopotential height by up to 100 geopotential meters (gpm) by the end of the century, reaching values of up to 6050 gpm. Average maximum 2-m air temperatures are projected to rise by 2.5°C during the mid-century and 4.2°C by the end of the century. The most significant temperature anomalies (deviations from the mean temperature) are associated with persistent and stable synoptic patterns, which are projected to increase the most in frequency and intensity. The findings on relative humidity reveal a general decrease over the AMB, with a peak value of -16.2% in the west of the domain during the PGW-END.

How to cite: Ventura, S., Miró, J. R., Segura-Barrero, R., Chen, F., Martilli, A., Liu, C., Ikeda, K., and Villalba, G.: Determining the intensity of future heatwave episodes at urban scales: the case study of the Metropolitan Area of Barcelona, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12016, https://doi.org/10.5194/egusphere-egu24-12016, 2024.

EGU24-12321 | ECS | Posters on site | CL3.1.1 | Highlight

Changes in extreme precipitation in East Africa and Mount Kenya based on high-resolution regional climate model simulations for the end of the 21st century 

Martina Messmer, Santos J. González Rojí, Christoph C. Raible, and Thomas F. Stocker

The climate in Africa is very diverse ranging from tropical rainforest to deserts. Also, East Africa is covered by different climate zones and is very dry compared to other tropical regions. This is owed to various large-scale drivers, such as the complex topography, large water bodies such as Lake Victoria and vicinity to the Indian Ocean. The southern part of East Africa is characterized by two rainy seasons, which are separated by dry periods. The long rains from March to May feature more continuous precipitation, while the short rains from October to November show high interannual variability with days of high precipitation intensities and drier intervals.

The CMIP5 and CMIP6 models project a general wetting of East Africa in the future, with a high model agreement. To obtain a better understanding of what this means for extreme precipitation and changes in the hydrological cycle we performed three different regional downscaling simulations using WRF: one for the present period from 1981–2010, and two for the end of the century (2071–2100). The latter two simulations are driven by, the RCP2.6 and the RCP8.5 scenarios, and the respective global forcing fields are based on CESM model runs. The regional model covers four different domains, whereby the first extends from the Sahara down to Madagascar with 27 km horizontal resolution, the second domain focuses on East Africa with 9 km resolution, the third domain at 3 km resolution zooms into the western part of Kenya, covering land with complex topography, and the last domain centers on Mount Kenya and surroundings at 1 km resolution.

Preliminary results show that the rainy seasons are difficult to capture by WRF, when driven by a global climate model. This might be related to the fact that some of the atmospheric circulation is misrepresented in the global model and cannot be corrected by the regional model dynamics. While the long rains are underestimated in the present compared to a downscaling of ERA5, the short rains show an overestimation. A sensitivity study with adjusted SSTs to overcome some of the circulation issues in the global climate model only weakly improves the results. The projections for the future show an increase in extreme precipitation days, but also in the extreme daily precipitation amounts compared to present extreme (p99) precipitation. While the rainy seasons are projected to be more intense, the dry seasons tend to become drier, leaving some months without precipitation at all. The results further suggest that the extreme precipitation events do not differ for the RCP2.6 and RCP8.5. Thus, extreme precipitation events in Kenya might be limited by an upper bound, but this is subject of ongoing research.

How to cite: Messmer, M., González Rojí, S. J., Raible, C. C., and Stocker, T. F.: Changes in extreme precipitation in East Africa and Mount Kenya based on high-resolution regional climate model simulations for the end of the 21st century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12321, https://doi.org/10.5194/egusphere-egu24-12321, 2024.

EGU24-12413 | Posters on site | CL3.1.1

A very High-resolution Climate Dataset for a High-altitude Region in Southern Spain: Sierra Nevada (HighResClimNevada) 

Matilde García-Valdecasas Ojeda, David Donaire-Montaño, Feliciano Solano-Farias, Juan José Rosa-Cánovas, Emilio Romero-Jiménez, Nicolás Tacoronte, Yolanda Castro-Díez, María Jesús Esteban-Parra, and Sonia R. Gamiz-Fortis

High mountain regions are characterized by a high spatiotemporal variability in their climatic variables. Unfortunately, in these regions there is a lack of climatic information, mainly due to its difficult accessibility, and if any, it is usually short, sparse, or incomplete with numerous gaps and outliers. Sierra Nevada (SN), located in the southern Iberian Peninsula (IP), constitutes a double hot spot as it is a mountain region located in the Mediterranean, both of which are particularly vulnerable to climate change.

To investigate the impact of climate change on mountainous ecosystems in SN, a high-resolution dataset for this region, HighResClimNevada, was created for the period from 2001 to 2020. For this purpose, the Weather Research and Forecasting (WRF) model version 4.3.3 driven by ERA5 reanalysis was used as convection permitting model (CPM) with a two “one-way” configuration to achieve simulated climatic fields over SN with 1 km spatial resolution. Because SN is topographically complex, the parent domain (d01) was configured spanned the entire IP with 5 km spatial resolution, while the nested domain (d02) was centered in SN but covered the entire Andalusia region. Maximum and minimum temperatures, precipitation, wind speed, solar incoming radiation, relative humidity, and surface pressure available are available in HighResClimNevada.

HighResClimNevada has been evaluated in terms of precipitation and maximum and minimum temperatures using bioclimatic and extreme indices, which are of special interest for ecologists and botanists. For this evaluation, we compared climatic fields from HighResClimNevada to observational gridded products from different sources (i.e., station-based products, satellite, and reanalysis), but also with in-situ weather stations located in the study region. In general, results indicate that HighResClimNevada has a good ability to represent the general climate characteristics in SN, making it a very useful tool for studying climate, its impact, and trends in this complex region.

Data availability: HighResClimNevada is available on the World Data Center for Climate (WDCC) at DKRZ (https://doi.org/10.26050/WDCC/HighresolClimNevada_eval).

Acknowledgements: This research has been carried out in the framework of the projects PID2021-126401OB-I00, funded by MCIN/AEI/10.13039/501100011033/FEDER Una manera de hacer Europa, LifeWatch-2019-10-UGR-01 co-funded by the Ministry of Science and Innovation through the FEDER funds from the Spanish Pluriregional Operational Program 2014–2020 (POPE) LifeWatch-ERIC action line, and the project P20_00035 funded by FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades.

How to cite: García-Valdecasas Ojeda, M., Donaire-Montaño, D., Solano-Farias, F., Rosa-Cánovas, J. J., Romero-Jiménez, E., Tacoronte, N., Castro-Díez, Y., Esteban-Parra, M. J., and Gamiz-Fortis, S. R.: A very High-resolution Climate Dataset for a High-altitude Region in Southern Spain: Sierra Nevada (HighResClimNevada), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12413, https://doi.org/10.5194/egusphere-egu24-12413, 2024.

EGU24-12651 | Orals | CL3.1.1 | Highlight

The influence of high Mediterranean Sea surface temperature on Storm Daniel intense rainfall 

Daniel Argüeso, Marta Marcos, and Ángel Amores

In September 2023, Storm Daniel hit the central Mediterranean and became the deadliest storm in the recorded history of the region. The storm originated from a low-pressure system around 4th September, which genesis can be attributed to an omega block centred in southern Europe. Then, it evolved into a Mediterranean tropical-like cyclone (medicane), impacting both the northern and the southern Mediterranean shores before dissipating around 12th September.

The storm particularly impacted Greece and Libya and, although the casualties and other major consequences are closely linked to significant infrastructure failures in Libya, both countries registered record-breaking rainfall amounts. For example, Zagora (Greece) experienced 754 mm in just 18 hours and Al-Bayda (Libya) saw a record highest daily rainfall of 414 mm. These events require an extraordinary supply of water vapor to maintain such rainfall rates. In the complex interplay of factors contributing to the development and intensity of weather systems like Storm Daniel, the Sea Surface Temperature (SST) stands as a likely primary driver. High SSTs provide not only the necessary energy, but also the moisture required to fuel the cyclone.

Over the months preceding Storm Daniel, the Mediterranean SST has consistently reached anomalously high levels, which was potentially a key ingredient in shaping the storm characteristics. To quantify the influence of local SST on the storm intensity, we used five ensembles of convection-permitting simulations (2 km) with an atmospheric model, which each of the ensemble members were initialized at different times. The five ensembles vary on the atmospheric and SST boundary and initial conditions, which were generated using different approaches to create counterfactual scenarios, from a simple removal of the mean climatological difference to an innovative data-driven method, which removes the long-term climate change signal correlated to global warming from SST. Combining these different estimates of atmosphere and SST counterfactual scenarios, we could quantify the relative contribution of global warming through local high SSTs and remote factors to rainfall amounts by Storm Daniel. In addition, we used a back-tracking algorithm to determine the source of water vapor that precipitated over Greece and Libya to understand the differences between the two phases of the event and the role of local SSTs. Our results show that local SST was crucial on the Libyan phase of the storm, while the rainfall amounts registered in Greece were mainly driven by remote factors. Also, the comparison of the different ensembles showed that the effects of long-term trends in SST are important in Libya, but the dominant contribution comes from the anomalous high SSTs that the region has recently experienced, which cannot be directly explained by mean climatological changes. In fact, these exception conditions are responsible for most of the record-breaking rainfall amounts observed during the second phase of the storm.

How to cite: Argüeso, D., Marcos, M., and Amores, Á.: The influence of high Mediterranean Sea surface temperature on Storm Daniel intense rainfall, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12651, https://doi.org/10.5194/egusphere-egu24-12651, 2024.

EGU24-12958 | ECS | Posters on site | CL3.1.1

Regional Climate Projection for Atlantic Canada under SSP245 and SSP585 

Freddy Pinochet, Hugo Beltrami, Elena Garcia-Bustamante, Jorge Navarro, and Fidel Gonzalez-Rouco

We use the Weather Research and Forecasting (WRF4.4) model for a regional climate simulation in Atlantic Canada. We seek to establish a robust repository of future climate projections for the region, that include the influence of northern ice coverage from the Labrador Sea and Ungava Bay, and sea surface temperatures (SST). The simulation is bounded by a Bias-Corrected ensemble of 18 CMIP6 General Circulation Models (GCMs) that offer better quality boundary conditions than the individual CMIP6 models in terms of the climatological mean, interannual variance and extreme events.

The simulation extends within the historical period from 1980 to 2014 and two future scenarios (SSP245 and SSP585) from 2015 to 2100. The configuration includes three domains with progressively increasing resolution from 30km to 9km and 3km. The finest resolution of 3 km by 3 km covers an area of approximately 561 kilometers by 462 kilometers around the province of Nova Scotia, Canada. The temporal resolution in WRF is set at 180 seconds, with boundary conditions updated every 6 hours, yielding output at a 6-hour time step for all WRF variables.

To validate the historical simulation, we use the reanalysis from ECMWF (ERA5)  and Station-Level Inputs and Cross-Validation for North America from The Oak Ridge National Laboratory (DAYMET). Preliminary statistical metrics reveal that our historical simulation underestimates the daily maximum temperature by 13%, overestimates daily minimum temperature by 2.7%, and underestimates the daily total precipitation by 16%. These findings provide valuable insights into the model performance and variability, and highlight areas for potential refinement for our projection scenarios. Analyses of the future (2015-2100) simulations are focused on estimating future precipitation (convective permitting), and surface air temperature (T2) extreme events.

How to cite: Pinochet, F., Beltrami, H., Garcia-Bustamante, E., Navarro, J., and Gonzalez-Rouco, F.: Regional Climate Projection for Atlantic Canada under SSP245 and SSP585, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12958, https://doi.org/10.5194/egusphere-egu24-12958, 2024.

EGU24-14514 | ECS | Posters on site | CL3.1.1

Numerical analysis of urban heat island in the coastal tropical desert city Doha, Qatar 

Rajeswari Jayarajan Roshini, Christos Fountoukis, Azhar Siddique, Shamjad Moosakutty, Mohammedrami Alfarra, and Mohammed Ali Ayoub

Qatar has witnessed substantial urbanization in recent years; the Doha metropolitan area grew by approximately a factor of 8 between 1984 and 2020, while bare land was reduced by more than 50%. Recent Climate projections mark the Middle East as a climate change hotspot, making it an ideal region for studying urbanization and its implications. The distribution of the Urban heat island effect and its modification with urbanization over the tropical desert city of Doha, Qatar is investigated using high-resolution Weather Research and Forecasting (WRF-ARW) model simulations. Two fair weather cases corresponding to the winter and summer seasons during 2022 are considered for analysis. Four sets of simulations are conducted by modifying the land use land cover (LULC) data and urban parameterization schemes keeping all other physics options and configuration constant. The study includes the recent 100m hybrid CGLC-MODIS-LCZ dataset (Hybrid-LCZ data), which includes the global map of Local Climate Zones (LCZ), for the first time in the region. The simulations are (1) Comparatively older LULC data corresponding to the year 2001 (hereafter MODIS), (2) the current extensive urban area corresponding to 2018 coupled with a single-layer urban canopy model (UCM) (hereafter LCZ-UCM), (3) hybrid LCZ data coupled with multilayer Building Environment Parametrization (BEP) (hereafter LCZ-BEP), and (4) hybrid LCZ coupled with Building energy model (BEM) (hereafter LCZ-BEM). To the best of our knowledge, this is the first numerical analysis of the UHI effect over this region that includes simulations with the local climate zones (LCZ). The results indicate the presence of strong UHI intensity with a maximum of 4.5˚C (6.5˚C) during the winter (Summer) period. During late night and early morning hours, the urban heat island (UHI) effect is strong and during daytime, a strong urban cool island (UCI) effect dominates the region. During the winter period, the intensity of UHI and UCI are controlled by the prevailing synoptic wind systems. The amplitude of the UHI and UCI trend is reduced by the prevailing North Westerly winds, while the moisture-rich South Westerly winds enhance it. However, during summer the surface representation along with local weather patterns modulates the intensity of the UCI and UHI. A consistent improvement in the simulated meteorological parameters is noted from the simulation with MODIS, UCM, BEP, and BEM during the summer season. The LCZ-BEM model accurately simulates the urban heat island intensity, temperature, and relative humidity with minimal deviation from observations. However, in winter as the synoptic features play a crucial role in the surface conditions all model experiments show similar performance in comparison to the observations.    

 

How to cite: Jayarajan Roshini, R., Fountoukis, C., Siddique, A., Moosakutty, S., Alfarra, M., and Ayoub, M. A.: Numerical analysis of urban heat island in the coastal tropical desert city Doha, Qatar, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14514, https://doi.org/10.5194/egusphere-egu24-14514, 2024.

EGU24-15276 | ECS | Posters on site | CL3.1.1

Evaluation of Weather Research and Forecasting Model Sensitivity to Different Physics Schemes in Convection-Permitting Mode over Southern Iberian Peninsula 

David Donaire-Montaño, Feliciano Solano-Farías, Matilde García-Valdecasas Ojeda, Juan José Rosa-Cánovas, Emilio Romero-Jiménez, Yolanda Castro-Díez, María Jesús Esteban-Parra, and Sonia R Gámiz-Fortis

Convection-Permitting Models (CPMs) represent a crucial advancement in climate modeling, allowing for enhanced spatial resolution at convection scales (≤ 4 km). In convection-permitting simulations, various small-scale weather processes, notably microphysics and convection, play important roles. Evaluating the Weather Research and Forecasting (WRF) model's performance at convection scales becomes particularly pertinent in complex orography regions with substantial climate variability, such as Andalusia, in the southern part of the Iberian Peninsula (IP). To address this, convection-permitting simulations were conducted, focusing on the assessment of precipitation and 2-m temperature throughout the exceptionally wet year of 2018.

The simulations were based on two "one-way" nested domains: the parent domain (d01) covering the entire IP at 5 km spatial resolution and the nested domain (d02) covering the Andalusia region at 1 km spatial resolution. Implementing these simulations involved the exploration of 12 parameterization schemes, encompassing three microphysics (MP) schemes (THOMPSON, WRF single moment 6-class (WSM6), and WRF single moment 7-class (WSM7)) and four convection schemes for d01 (Grell 3D (G3), Grell-Freitas (GF), Kain-Fritsch (KF), along with the deactivated cumulus parameterization (OFF)). In the process of evaluating the model outputs, a comprehensive approach was adopted, using diverse observational datasets, including both gridded and station data. The comparisons were conducted on a point-to-point basis, considering various time aggregations (monthly, daily and hourly).

Main results show, on one hand, simulations employing the Grell-Freitas (GF) or deactivated cumulus parameterization (OFF) in d01 exhibited superior performance compared to reference datasets. On the other hand, while THOMPSON demonstrated a better fit in high mountain areas, it generally exhibited a poorer agreement with reference datasets than WSM6 and WSM7. In terms of temperature, the results displayed remarkable similarity, prompting the primary consideration of precipitation results. The WSM7-GF scheme emerged as the optimal configuration for the Andalusia region, underscoring its suitability in capturing the complex meteorological dynamics of this distinctive locale.

Keywords: sensitivity study, convection-permitting climate simulations, southern Iberian Peninsula, Andalusia, parameterization schemes, Weather Research and Forecasting model.

 

Acknowledgements:

This research has been carried out in the framework of the projects PID2021-126401OB-I00, funded by MCIN/AEI/10.13039/501100011033/FEDER Una manera de hacer Europa, P20_00035 funded by FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades, and LifeWatch-2019-10-UGR-01 co-funded by the Ministry of Science and Innovation through the FEDER funds from the Spanish Pluriregional Operational Program 2014–2020 (POPE) LifeWatch-ERIC action line.

How to cite: Donaire-Montaño, D., Solano-Farías, F., García-Valdecasas Ojeda, M., Rosa-Cánovas, J. J., Romero-Jiménez, E., Castro-Díez, Y., Esteban-Parra, M. J., and Gámiz-Fortis, S. R.: Evaluation of Weather Research and Forecasting Model Sensitivity to Different Physics Schemes in Convection-Permitting Mode over Southern Iberian Peninsula, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15276, https://doi.org/10.5194/egusphere-egu24-15276, 2024.

EGU24-16029 | ECS | Orals | CL3.1.1 | Highlight

Convection-Permitting Climate Models: Present and Future Insights on daily and sub-daily Extreme Precipitation in Norway 

Kun Xie, Lu Li, Stefan Sobolowski, Hua Chen, and Chong-Yu Xu

Convection-permitting climate models (CPMs) have demonstrated enhanced capability in capturing extreme precipitation compared to convection-parameterization models. Despite this, a comprehensive understanding of their added values in daily or sub-daily extremes, especially at local scale, remains limited. In this study, we conduct a thorough comparison of daily and sub-daily extreme precipitation from HCLIM3 and HCLIM12 across Norway, divided into eight regions, using gridded and in-suit observations. Our main focus is to investigate the added values of HCLIM3 compared to HCLIM12 for precipitation extreme indices at daily and sub-daily time-steps on both local and regional scales. We find that the HCLIM3 better captures the maximum 1-day precipitation (Rx1d) at most of the regions except south-western region. Notably, the performance of HCLIM3 in capturing Rx1d shows a notable coastal-inland division, overestimating along the coastal areas and underestimating in the inland regions. In general, HCLIM3 better matches observations than HCLIM12 for daily and sub-daily precipitation extreme indices at regional scale in Norway. However, at the local scale, neither HCLIM3 nor HCLIM12 can capture the temporal evolution of Rx1h during 10 years, except one station near Oslo (eastern region), where only HCLIM3 fits the observations. In general, HCLIM3 performs better than HCLIM12 on Rx1d and Rx1h in Norway with the mean of bias distribution closer to zero, although it varies a bit among regions (for example, HCLIM3 performs worse in the south-western region). In addition, the seasonality of Rx1h can be also better captured by HCLIM3 at both regional and local scales, while HCLIM12 tends to underestimate hourly extremes. In a future warming climate, HCLIM3 with higher Clausius-Clapeyron (CC) scaling, exhibits a higher increase than HCLIM12 in the Rx1h and Rx1d over most regions of Norway except southern and south-west regions. Under global warming, short-duration extreme events with greater CC scaling have a higher increase rate than long-lasting events. This study highlights the importance of more realistic convection-permitting regional climate predictions and projections in providing reliable insights into the characteristics of precipitation extremes and their future changes across Norway's eight regions. Such information is crucial for effective adaptation management to mitigate severe hydro-meteorological hazards, especially for the local extremes.

How to cite: Xie, K., Li, L., Sobolowski, S., Chen, H., and Xu, C.-Y.: Convection-Permitting Climate Models: Present and Future Insights on daily and sub-daily Extreme Precipitation in Norway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16029, https://doi.org/10.5194/egusphere-egu24-16029, 2024.

The Sichuan Basin (SB), a lowland region in southwest China located at the eastern slope of the Tibetan Plateau (TP), regularly experiences heavy and extreme precipitation events. These extreme events often lead to flooding that can pose a threat to life and livelihoods of people in this densely populated area. A notable example is the summer of 2020, during which large parts of East Asia were affected by anomalously high precipitation. In the SB, these events broke the previous record of daily accumulated rainfall at multiple stations.  

Since such events are expected to increase in both frequency and intensity in a warmer climate, understanding their causes and the physical processes involved is of high relevance in the SB region. Modelling the climate in mountainous regions with complex topography is challenging but recent developments in convection-permitting modelling make it possible to perform process-based studies.

The CORDEX Flagship Pilot Study Convection-Permitting Third Pole (CPTP) aims to improve our understanding of the water cycle over the TP and its surrounding regions using a multi-model ensemble of kilometre-scale simulations. Recent results using a set of CPTP simulations for one extreme precipitation event suggest that an accurate representation of the large-scale forcing is crucial to correctly simulate the event. In this study, we assess how well different kilometre-scale CPTP simulations capture multiple observed heavy and extreme precipitation events that occurred in the SB during the summer of 2020 by validating them against observations and reanalysis data. In addition, we analyse how the simulations differ among each other in representing the observed events and related important physical factors, e.g. large- and mesoscale circulation and moisture transport. A realistic representation of extreme events in climate models can provide a basis for more reliable future projections and uncertainty estimates.

How to cite: Detjen, L., Curio, J., and Ou, T.: Heavy and extreme precipitation events in the Sichuan Basin during the 2020 summer season in a set of kilometre-scale simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17506, https://doi.org/10.5194/egusphere-egu24-17506, 2024.

EGU24-18143 | ECS | Posters on site | CL3.1.1

Advancing regional to local climate knowledge: Insights from German NUKLEUS and UDAG Consortium Projects 

Eleonora Cusinato, Christoph Braun, Hendrik Feldmann, Beate Geyer, Klaus Keuler, Patrick Ludwig, Julia Moemken, Kevin Sieck, Katjia Trachte, Barbara Frühe, Christian Steger, and Joaquim G. Pinto

According to the latest assessment of the IPCC report, regional climate changes in mean climate and extremes are expected to become more widespread and pronounced. As a consequence, climate hazards are projected to increase in every region of the world leading to the necessity of developing climate adaptation and mitigation plans.  In this context, the German Federal Ministry of Education and Research (BMBF) funded several projects whose primary goal is to provide up-to-date regional and local climate projections that will subsequently form the bases for climate German adaptation strategies.

This contribution aims at illustrating ongoing research within the framework of two of these consortium projects, namely NUKLEUS (Usable Locale Climate Information for Germany) and UDAG (Updating the data basis for adaptation to climate change in Germany) to the EURO-CORDEX community. The innovative aspect of both projects lies in the creation of an unprecedented ensemble of convection permitting climate projections for “hydrological Germany" at high temporal and spatial resolution, which allows to provide information on climate change at regional and local scales.

For this purpose, NUKLEUS downscaled three global coupled models (GCMs) within the CMIP6 framework using three regional climate models (namely REMO, COSMO-CLM6 and ICON-CLM) first to the EURO-CORDEX Eur-11 domain (12 km) and subsequently to the km-scale at approximately 3 km resolution over Germany for the scenario SSP3-7.0. However, the resulting ensemble is not sufficient to provide actionable climate change information.
UDAG project aims at overcoming this limitation by downscaling a wide range of CMIP6-GCMs (6-8) using ICON-CLM first to 12 km resolution providing regional climate simulations for Europe for the scenarios SSP3-7.0 and SSP1-2.6 and then to approximately 3 km to generate climate projections specifically targeted for "hydrological Germany."

Given the shared use of common CMIP6-GCMs in the downscaling process for both projects, and considering the early stage of the UDAG project, this contribution presents initial insights from the NUKLEUS project. Biases evaluation analysis is conducted, revealing noteworthy distinctions in the RCMs at 12 km and 3 km compared to the CMIP6-GCMs. Subsequently, key metrics for extreme values statistics related to temperature and precipitation are discussed. In summary, these methods and findings serve as a preliminary groundwork for the forthcoming UDAG analysis.

 

How to cite: Cusinato, E., Braun, C., Feldmann, H., Geyer, B., Keuler, K., Ludwig, P., Moemken, J., Sieck, K., Trachte, K., Frühe, B., Steger, C., and Pinto, J. G.: Advancing regional to local climate knowledge: Insights from German NUKLEUS and UDAG Consortium Projects, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18143, https://doi.org/10.5194/egusphere-egu24-18143, 2024.

The detection of local climate change signals, in particular those related to extreme events, is challenging due to the large internal variability of the climate system. The BMBF-funded project ClimXtreme Module B-CoDEx focuses on improving the signal-to-noise ratio of climate change signals in extreme weather events using innovative data compression methods.

This study uses principal component analysis (PCA) for spatial extremes (Cooley and Thibaud, 2019) to analyse heatwaves and droughts over the northern hemisphere. An extremal pattern index (EPI) is introduced as an integrative measure of the intensity and spatial extent of an extreme heat anomaly. Its bivariate extension is used to account for simultaneous spatial extremes in two variables. EPI provides us with a compact description of heatwaves. We see, for example, that preceding precipitation deficits significantly influence the development of heatwaves, and that heat waves often coincide with instantaneous short-term droughts. 

To investigate extreme hourly precipitation, a scale-dependent decomposition using the dual-tree wavelet transform is proposed, as described e.g. in Buschow and Friederichs (2021). For this study, we rely on reanalysis data (COSMO-REA6, CERRA) over Germany. A comparison of the two datasets regarding their representation of large- and small-scale events shows significant differences, especially for the small-scale events. Furthermore, we apply established methods to perform a scale-dependent detection of extreme precipitation and to reveal trends that are hidden by variability on other scales. 

How to cite: Szemkus, S. and Friederichs, P.: Investigating heatwaves/droughts and convective precipitation extremes using compact descriptions of spatio-temporal fields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18175, https://doi.org/10.5194/egusphere-egu24-18175, 2024.

EGU24-18290 | ECS | Orals | CL3.1.1

Assessing Future Climate Extremes in Türkiye: A High Resolution CMIP6-based Analysis 

Berkin Gümüş, Sertaç Oruç, İsmail Yücel, and Mustafa Tuğrul Yılmaz

This study employs the latest versions of global climate models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to evaluate climate extremes in Türkiye from 2015 to 2100 under two future scenarios, SSP2-4.5 and SSP5-8.5. Utilizing a number of high resolution CMIP6 models and different scenarios over the full projection period make this study unique over the region. To downscale coarse-resolution climate models to approximately 9 km (0.1° × 0.1°) spatial resolution, Quantile Delta Mapping (QDM) is employed. The downscaling process utilizes the European Centre for Medium-Range Weather Forecasts Reanalysis 5-Land (ERA5-Land) dataset as the reference data. Analysis of 12 extreme precipitation indices (EPIs) and 12 extreme temperature indices (ETIs) between 2015 and 2100 consistently indicates an increased frequency and intensity of extreme weather events in Türkiye under both future scenarios. The SSP5-8.5 scenario predicts a higher degree of water stress compared to SSP2-4.5, with a 20% reduction in total precipitation in the Aegean and Mediterranean regions of Türkiye. Despite an overall decrease in precipitation, the findings suggest an increase in the severity and frequency of extreme precipitation events. This implies that a greater proportion of total precipitation will be contributed by these extreme events. Anticipated trends include an increase in temperature extremes, encompassing both the lowest and highest daily maximum temperatures across all regions of Türkiye. This signifies a warming signal of up to 7.5 °C by the end of the current century. Cold extremes also exhibit a tendency towards warming, as evidenced by a significant decrease in the number of ice days across all areas. This trend may potentially result in less snow accumulation, which negatively affects various sectors.

How to cite: Gümüş, B., Oruç, S., Yücel, İ., and Yılmaz, M. T.: Assessing Future Climate Extremes in Türkiye: A High Resolution CMIP6-based Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18290, https://doi.org/10.5194/egusphere-egu24-18290, 2024.

EGU24-19237 | ECS | Posters on site | CL3.1.1

Climate Initiative for Iberian Mountain Areas (CIMAs): improving our understanding of climate variability over mountain areas using high resolution modelling. 

Emilio Greciano-Zamorano, Jesús Fidel González-Rouco, Cristina Vegas-Cañas, Félix García-Pereira, Jorge Navarro-Montesinos, Elena García-Bustamante, Esteban Rodríguez-Guisado, and Ernesto Rodríguez-Camino

Mountain areas are particularly sensitive to global warming as they usually present a complex distribution of climates and ecosystems and feedbacks tend to amplify the effects of climate change. Additionally, the large spatial variability of temperature gradients and heterogeneity in the occurrence, amount and distribution of precipitation and snow cover in mountainous areas are especially relevant for water resources and stresses the need for high altitude observations and high-resolution modelling over complex terrain. However, harsh meteorological conditions and the complex orography associated with this environment that, as part of the Mediterranean domain, has been underscored as a climate change hot-spot, hinder the obtention of a good coverage of high-altitude observations and pose challenges for regional climate models.

CIMAs is a joint effort aiming at improving our understanding of climate variability over mountain regions in Iberia. A pilot area has been selected over the Sierra de Guadarrama (Spanish Central range, about 50 km from Madrid) aiming at studying climate variability through very high (1 km) resolution simulations, exploring models’ ability to capture relevant processes at that scale. A set of observational sites ranging from high altitudes to low levels at both sides of the mountain range has been used.

ERA Interim, ERA5 and different WRF nested simulations, spanning the last three decades and reaching 1 km resolution, have been compared to a dense network of in situ observations. Results show a clear improvement with increasing resolution for temperature, but some altitude-related biases for precipitation. In this sense, some sensitivity tests to changing convection parameterizations and to convection permitting configurations have been assessed.

How to cite: Greciano-Zamorano, E., González-Rouco, J. F., Vegas-Cañas, C., García-Pereira, F., Navarro-Montesinos, J., García-Bustamante, E., Rodríguez-Guisado, E., and Rodríguez-Camino, E.: Climate Initiative for Iberian Mountain Areas (CIMAs): improving our understanding of climate variability over mountain areas using high resolution modelling., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19237, https://doi.org/10.5194/egusphere-egu24-19237, 2024.

EGU24-19523 | ECS | Posters on site | CL3.1.1 | Highlight

Scaling of Precipitation in the Alps: Insights from a Convection Permitting Regional Climate Model Ensemble 

Luna Santina Lehmann, Patricio Velasquez, Albert Ossó, and Christoph Schär

Previous studies predict an intensification of heavy precipitation events with climate change. These events are widely known to cause natural disasters with great property damage and loss of life, like flash floods or landslides. Knowledge about the scaling of precipitation, referring to the changes of precipitation intensity to warmer temperatures, is important for effective mitigation measures. Previous studies have investigated this scaling with regards to the Clausius Clapeyron relation, over various regions worldwide, using observational as well as model data. In this study we analyze the precipitation scaling over an orographically complex region as the Alps, as well as compare different methods to obtain the scaling rate.

To this end, we employ a 10-year multi-model ensemble of kilometer-scale convection-permitting climate model (CPM) simulations over the Greater Alpine Region from the CORDEX-FPS, with a spatial resolution ranging from 2.2 to 4 km. These simulations were obtained by downscaling global climate model (GCM) projections to intermediate regional climate models (RCMs), which were in turn further downscaled to kilometer scale by convection permitting climate models (CPMs). Previous work has shown the added value of these CPMs compared to lower resolution RCMs especially for extreme precipitation. We analyze these simulations over four alpine subdomains, which are characterized by different climatological characteristics.

In the calculation of precipitation scaling rates, we use two different precipitation indices, wet-hour percentiles and all-hour percentiles. These indices differ in that the latter encompasses all events, wet and dry, whereas the wet-hour percentile only includes events that go over a certain threshold. We compare the scaling calculated using these precipitation indices on an annual and seasonal basis, to show insights into the mechanisms that may cause scaling rates to exceed expectations given from the Clausius Clapeyron relation. Our results show that future precipitation intensity may be inferred from present-day scaling. The seasonal analysis shows scaling exceeding the Clausius Clapeyron scaling in the summer and autumn seasons for the wet-hour analysis, but not for the all-hour analysis.

How to cite: Lehmann, L. S., Velasquez, P., Ossó, A., and Schär, C.: Scaling of Precipitation in the Alps: Insights from a Convection Permitting Regional Climate Model Ensemble, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19523, https://doi.org/10.5194/egusphere-egu24-19523, 2024.

EGU24-20433 | Orals | CL3.1.1

High resolution regional re-analysis ensemble for Austria 

Nauman K. Awan, Christoph Wittmann, Clemens Wastl, and Florian Meier

In recent decades reanalysis products have emerged as a pivotal resource for numerical model evaluations, significantly enhancing our understanding of Earth’s system. They have also been employed in various projects aimed at climate monitoring and assessment of climate change impacts. In this study, we present first results from ongoing work aimed at creating a first of its kind high resolution reanalysis ensemble for Austria. ECMWF's ERA5 ensemble is downscale to a 2.5 km resolution by employing three-dimensional variational assimilation (3DVAR) system available in AROME. Upon completion, this dataset will provide spatially, temporally, and physically consistent 3D and 2D atmospheric fields spanning from 2012 to 2022. The presented analysis focused on representation of three distinct extreme precipitation events simulated in a one and a half year long simulation (01-01-2021 to 30-06-2022). The reanalysis ensemble is compared with operational weather models and a high resolution (1 km x 1 km) gridded observational reanalysis. Based on statistical scores, all variations are ranked. In general, the results are on par with our operational models, however, some ensemble members exhibit slightly better performance compared to our operational models, which highlights the advantages of employing an ensemble system.

How to cite: Awan, N. K., Wittmann, C., Wastl, C., and Meier, F.: High resolution regional re-analysis ensemble for Austria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20433, https://doi.org/10.5194/egusphere-egu24-20433, 2024.

Global warming results in increase in the intensity and frequency of extreme temperature events across the world. This study used multivariate copula approach to comprehend variations in intensity and frequency of extreme temperature events over 54 urban agglomerations in India. The current study uses the Coupled Model Intercomparison Phase 6 (CMIP6) framework to explore the relationship between temperature intensity duration frequency for 1.5°C, 2°C, and 3°C global warming levels (GWL) over the two time periods, T1(2021-2050) and T2(2071-2100). Using bivariate copulas, we analyse the changes in return estimates for temperature extreme considering 10, 20, 50, and 100-year return periods over 2, 5, and 10-day durations. Amongst various distributions, the lognormal and extreme value distribution appeared as the most suitable distributions to represent duration and temperature intensity, respectively. As far as copula analysis is concerned, the Gumbel-Hougaard copula was found to be most suitable to illustrate the joint behaviour. With respect to base period, more than 60%, 64% and 80% of urban agglomerations report an increase in the extreme temperature return values under 1.5°C, 2°C, and 3°C GWL respectively. By the end of the century, more than 83% of urban agglomerations will experience an increase in the extreme temperature return values. A significant regional variation has been observed in the percentage change of the return estimates. Cities such as Mysore, Bangalore, Pune, Dharwad, Coimbatore report 9-18% decrease in the extreme temperature return values. Whereas, cities such as Amritsar, Jalandhar, Delhi, Shimla, and Kanpur report 23%-28%, increase in return values. Furthermore, these cities are projected to experience an increase of 30% by the end of the century. The findings highlight the urgent necessity for the implementation of climate change mitigation strategies that are more closely aligned with the objectives outlined in the Paris Agreement. By implementing strategies aimed at limiting global warming, we can effectively alleviate the detrimental impacts and increasing hazards linked to extreme heat events.

How to cite: Joshi, N., Maurya, H., Suryavanshi, S., and Dubey, A.: Appraisal and Prognosis: Towards Projecting the Future Changes in Urban Extreme Temperature Events over India under Climate Change Scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1395, https://doi.org/10.5194/egusphere-egu24-1395, 2024.

EGU24-1716 | ECS | Orals | CL3.1.3

Attribution using analogues: a case study of the Western European flood event of July 2021  

Vikki Thompson, Dim Coumou, Sjoujke Philip, Sarah Kew, and Izidine Pinto

In July 2021 a cut-off low pressure system brought extreme precipitation to Western Europe. Record daily rainfall totals led to flooding that caused loss of life and substantial damage to infrastructure in Germany, Belgium, and the Netherlands. By identifying flow analogues – dynamically similar events - in both reanalysis data and large ensembles of climate model simulations we can investigate how the dynamics involved in this event are changing through time. Analogue methods are increasingly used in event attribution, we highlight considerations that must be made when using such methods. 

For July 2021, we show that similar low pressure systems are occurring more frequently, and the lows are deepening through time. We find some analogues persist for much longer than was seen in July 2021. These dynamical changes effect surface impacts of such events. Such unprecedented events will become increasingly likely in a warming climate, and society must adapt to reduce future impacts. 

How to cite: Thompson, V., Coumou, D., Philip, S., Kew, S., and Pinto, I.: Attribution using analogues: a case study of the Western European flood event of July 2021 , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1716, https://doi.org/10.5194/egusphere-egu24-1716, 2024.

EGU24-1910 | ECS | Orals | CL3.1.3

Attributed and projected climate change impacts on maize yield in Cameroon as mediated by heat-tolerance adaptation 

Lennart Jansen, Sabine Undorf, and Christoph Gornott

Sub-Saharan Africa is projected to be exposed to substantial climate change hazards, especially in its agricultural sector, so adaptation will be necessary to safeguard food security. However, tropical and subtropical maize production regions approach critical temperature thresholds in the growing season already in today’s climate, and climate change might already be contributing to this. Projecting future, and attributing already observed, yield impacts due to anthropogenic climate change under adaptation assumptions can thus provide valuable context to future adaptation needs. No adaptation impact studies currently exist for heat-tolerance of maize in West Africa, let alone one that combines projections and counterfactual historical simulations to this effect.

Here, we report on a study in which we focus on maize in Cameroon to model the effect and potential of crop-varietal heat-tolerance adaptation. We use climate reanalysis data (mainly W5E5), historical and counterfactual bias-corrected and downscaled CMIP6-DECK and -DAMIP simulations along with ISIMIP3a data, and future projections from CMIP6/ISIMIP3b. The two climate change scenarios SSP1-2.6 and SSP3-7.0 were analysed for 2020-2100 and historical simulations for 1984-2014.

The process-based crop model APSIM was run in a spatially disaggregated, grid-based approach as to represent Cameroon’s diverse agro-ecological zones. The impact of heat tolerance adaptation in maize was assessed by parametrising one unadapted baseline variety and one synthetic heat-tolerant variety in APSIM and comparing yield outcomes.

Yields are substantially higher for the heat-tolerant variety. Either variety experience similar losses in the projected future compared to now, increasing with climate change scenario and time. Impacts on maize yield are dominantly attributed to heat stress. Already observed climate change impacts compared to counterfactual climate further indicate that adaptation to present-day climate can be considered climate change adaptation beyond development.

How to cite: Jansen, L., Undorf, S., and Gornott, C.: Attributed and projected climate change impacts on maize yield in Cameroon as mediated by heat-tolerance adaptation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1910, https://doi.org/10.5194/egusphere-egu24-1910, 2024.

EGU24-1917 | ECS | Orals | CL3.1.3

Human-induced climate change has decreased wheat production in northern Kazakhstan 

Paula Romanovska, Sabine Undorf, Bernhard Schauberger, Aigerim Duisenbekova, and Christoph Gornott

Northern Kazakhstan is a major exporter of wheat, contributing to food security in Central Asia and beyond, but wheat yields fluctuate and low-producing years occur frequently. The most severe low-producing year in this century was in 2010, leading to severe consequences for the food security of wheat importing countries. To date, the extent to which human-induced climate change contributes to this is unclear.

In this session, we present the first attribution study for wheat production in northern Kazakhstan, which is at the same time one of the very first climate impact attribution studies for the agricultural sector in general. We quantify the impact of human-induced climate change on the average wheat production as well as economic revenues and on the likelihood of a low-production year like 2010. For this, we use bias-adjusted counterfactual and factual climate model data from two large ensembles of latest-generation climate models as input to a statistical subnational yield model. The climate data and the yield model were shown to be fit for purpose as the factual climate simulations represent the observations, the out-of-sample validation of the yield model performs reasonably well with a mean R2 of 0.54, and the results are robust under the performed sensitivity tests.

Our results show that human-induced climate change, and explicitly increases in daily-minimum temperatures and extreme heat, have had a critical impact on wheat production, decreasing yields between 2000 and 2019 by around 6.2 to 8.2% (uncertainty range of two climate models), increasing the likelihood of the 2010 low-production event by 2.1 to 3 times, and leading to economic losses of 119 to 158 million USD. The latest IPCC report assessed that climate change has today mixed positive and negative impacts on wheat production in Central Asia, but the results are stated with low confidence as studies are sparse in this region. This climate impact attribution study addresses this gap, finding clear indications for a negative influence of climate change, especially via temperature increases, on wheat production in northern Kazakhstan.

How to cite: Romanovska, P., Undorf, S., Schauberger, B., Duisenbekova, A., and Gornott, C.: Human-induced climate change has decreased wheat production in northern Kazakhstan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1917, https://doi.org/10.5194/egusphere-egu24-1917, 2024.

EGU24-1962 | Orals | CL3.1.3

Forced Component Estimation Statistical Methods Intercomparison Project (ForceSMIP): First Results 

Robert Jnglin Wills, Clara Deser, Karen McKinnon, Adam Phillips, and Stephen Po-Chedley

Anthropogenic climate change is unfolding rapidly, yet its regional manifestation is often obscured by naturally occurring variability internal to the atmosphere and ocean system. A primary goal of climate science is to identify the forced response, i.e., spatiotemporal changes in climate in response to greenhouse gases, anthropogenic aerosols, and other external forcing, amongst the noise of internal climate variability. Separating the forced response from internal variability can be addressed in climate models by taking the average over a large ensemble, where the same model is run multiple times with small differences in initial conditions leading to different realizations of internal variability. However, there is only one realization of the real world, making it a major challenge to isolate the forced response in observations, as is needed for accurate attribution of historical climate changes, for characterizing and understanding observed internal variability, and for climate model evaluation.

In the Forced Component Estimation Intercomparison Project (ForceSMIP), contributors utilized existing and newly developed statistical and machine learning methods to estimate the forced response during the historical period within individual ensemble members and observations, across nine key climate variables (sea-surface temperature, surface air temperature, precipitation, sea-level pressure, sea-ice concentration, zonal-mean atmospheric temperature, monthly maximum and minimum temperature, and monthly maximum daily precipitation). Participants had access to five CMIP6 large ensembles on which to train their methods, but they then had to apply their methods to individual evaluation members, the identity of which was hidden to all participants. Participants used methods including regression methods, dynamical adjustment, convolutional neural networks, linear inverse models, fingerprinting methods, and low-frequency component analysis, and all codes have been collected to make an open-access repository. The ForceSMIP submission period ends on March 1, 2024, and we will present first results showing how the different methods performed on climate models, what they assessed to the be the forced response in observations, and how the estimate of the forced response in observations compares with that in climate models.

How to cite: Jnglin Wills, R., Deser, C., McKinnon, K., Phillips, A., and Po-Chedley, S.: Forced Component Estimation Statistical Methods Intercomparison Project (ForceSMIP): First Results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1962, https://doi.org/10.5194/egusphere-egu24-1962, 2024.

EGU24-2525 | ECS | Orals | CL3.1.3

A framework for the super attribution of multiple extreme events 

Chen Lu, Erika Coppola, Emanuela Pichelli, and Davide Faranda

Detection and attribution of anthropogenic influence on extreme events has always been one of the focuses of climate research. A number of studies have been undertaken that employed different approaches (such as the risk-based, Boulder, and circulation-based ones) for attributing individual extreme events of various types over the globe. While many of these extreme events are attributable to anthropogenic or natural factors, some still remain inconclusive. To this end, a super attribution framework is proposed, in which multiple extreme events occurring in one region within a predefined timeframe are considered as a whole instead of individually. The rationale is that climate change may influence large-scale circulation over a region, which subsequently alters the frequency of extreme events in multiple locations in this area. Specifically, the supervariable is proposed to characterize how severely a region is affected by extreme precipitation in terms of area. It is defined as the fraction of area in a region that experiences extreme precipitation of over 99.9th percentile in each day. The trends in the supervariable in the 20 Italian regions are examined. For regions with positive but not significant trends, there could be an anthropogenic signal present, but it could be too weak to be detected. Therefore, regions with positive trends are selected, and a super attribution is undertaken on them simultaneously. It is accomplished by calculating the combined supervariable, which is obtained by pooling the stations/grids of the selected regions together. Simultaneous events that occur in the autumn of each year are then considered. The results show that a statistically significant increasing trend can be identified in the combined supervariable for the selected regions, which suggests an increase in the area affected by extreme precipitation. In parallel to the statistical analysis, dynamical attribution is also carried out using the analog method, and the type of pattern that is both significantly influenced by climate change and associated with significant increases in precipitation is identified.

How to cite: Lu, C., Coppola, E., Pichelli, E., and Faranda, D.: A framework for the super attribution of multiple extreme events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2525, https://doi.org/10.5194/egusphere-egu24-2525, 2024.

EGU24-3100 | ECS | Orals | CL3.1.3

Direct and lagged climate change effects intensified the widespread 2022 European drought 

Emanuele Bevacqua, Dominik L. Schumacher, Oldrich Rakovec, Rohini Kumar, Stephan Thober, Robert Schweppe, Luis Samaniego, Sonia I. Seneviratne, and Jakob Zscheischler

In 2022, Europe faced an extensive summer drought that resulted in severe socio-economic consequences. Combining observations and climate model outputs with hydrological and land-surface simulations, we show that central and southern Europe experienced the highest observed total water storage deficit since the observations started in 2002, likely marking the highest and most widespread soil moisture deficit since 1960. While precipitation deficits primarily drove the soil moisture drought, global warming contributed to over 30% of the drought intensity and its spatial extent via enhancing evaporation. We reveal that about 15-40% of the climate change contribution was mediated by the warming that started drying the soil before the hydrological year of 2022, indicating the importance of considering lagged climate change effects to avoid underestimating risks. Qualitatively similar effects were observed in river discharges. These findings highlight that global warming impacts on droughts are widespread, long-lasting, and already underway, and that drought risk may escalate in the future. 

How to cite: Bevacqua, E., Schumacher, D. L., Rakovec, O., Kumar, R., Thober, S., Schweppe, R., Samaniego, L., Seneviratne, S. I., and Zscheischler, J.: Direct and lagged climate change effects intensified the widespread 2022 European drought, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3100, https://doi.org/10.5194/egusphere-egu24-3100, 2024.

EGU24-3444 | Orals | CL3.1.3

Quantifying the contribution of forcing and three prominent modes of variability to historical climate 

Andrew Schurer, Gabriele Hegerl, Hugues Goosse, Massimo Bollasina, Matthew England, Michael Mineter, Doug Smith, and Simon Tett

Climate models can produce accurate representations of the most important modes of climate variability, but they cannot be expected to follow their observed time evolution. This makes direct comparison of simulated and observed variability difficult, and creates uncertainty in estimates of forced change. Here we discuss the use of a particle filter data-assimilation technique in a global climate model, that sub-selects members among an ensemble of simulations, to follow the observed Northern Atlantic Oscillation, El Niño Southern Oscillation and Southern Annular Mode, without the use of nudging terms. We investigate the role of these three modes of climate variability, as pacemakers of climate variability since 1781, evaluating where their evolution masks or enhances forced climate trends. Since the climate model also contains external forcings, these simulations, in combination with model experiments with identical forcing but no assimilation, can be used to compare the forced response to the effect of the three modes assimilated and evaluate the extent to which these are confounded with the forced response. The assimilated model is significantly closer than the “forcing only” simulations to annual temperature and precipitation observations over many regions, in particular the tropics, the North Atlantic and Europe. We will show that the NAO variability leads to large multi-decadal trends in temperature, and sea-ice concentration, and that constraining the El Niño–Southern Oscillation reconciles simulated global cooling with that observed after volcanic eruptions.

How to cite: Schurer, A., Hegerl, G., Goosse, H., Bollasina, M., England, M., Mineter, M., Smith, D., and Tett, S.: Quantifying the contribution of forcing and three prominent modes of variability to historical climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3444, https://doi.org/10.5194/egusphere-egu24-3444, 2024.

EGU24-3785 | ECS | Orals | CL3.1.3

Disentangling forced trends in the North Atlantic jet in CESM2 using deep learning  

Alejandro Hermoso and Sebastian Schemm

According to state-of-the-art climate simulations, the future evolution of the wintertime North Atlantic jet stream is highly uncertain compared to other ocean basins. This has important consequences on the projected daily weather variability and the occurrence of extreme events over Europe. In this context, disentangling the forced trends in the North Atlantic jet caused by an increase in greenhouse gases from its natural variability is a challenging but extremely relevant task.

In this study, we use a deep learning-based method, the Latent Linear Adjustment Autoencoder (LLAE), to separate forced trends from natural variability in an ensemble of fully-coupled Community Earth System Model simulations. The LLAE consists of a variational autoencoder and an additional linear component. The model predicts the component of the wind associated with natural variability from upper-level detrended temperature and geopotential. The residual between this prediction and the original wind field can be interpreted as the component of the wind related to the external forcing. Despite the large variability of the original trends, especially in the historical period, the LLAE is effective in extracting the forced component of the trend, which is similar for all ensemble members. The main characteristics of the forced trend are an increase in the wind speed along a southwest-northeast oriented band and an extension of the jet over Europe. These features are common for different periods and have similarities to the full North Atlantic jet trend in the ERA5 reanalysis.

How to cite: Hermoso, A. and Schemm, S.: Disentangling forced trends in the North Atlantic jet in CESM2 using deep learning , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3785, https://doi.org/10.5194/egusphere-egu24-3785, 2024.

EGU24-3960 | ECS | Posters on site | CL3.1.3

Attributing the influence of climate change on the 2022 Pakistan floods  

Daniel Cotterill, Dann Mitchell, Peter Stott, Paul Bates, and Nicholas Leach

In 2022 large parts of Pakistan suffered devastating flooding, with the southern provinces of Balochistan and Sindh particularly badly impacted. These regions received record-breaking rainfall totals during August, following a very wet July over the summer monsoon season. In this attribution study we combine the forecasting attribution technique developed by Leach et al. 2021 with flood inundation modelling to estimate the influence of anthropogenic climate change on the 2022 floods. This combined storyline and probabilistic approach uses the European Centre for Medium-Range Weather Forecasts (ECMWF) forecasts, and perturbed counterfactual forecasts with the same synoptic setup. These are fed into the 2D hydrodynamic flood inundation model LISFLOOD-FP over the worst affected regions to produce flood maps at 90m resolution.

How to cite: Cotterill, D., Mitchell, D., Stott, P., Bates, P., and Leach, N.: Attributing the influence of climate change on the 2022 Pakistan floods , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3960, https://doi.org/10.5194/egusphere-egu24-3960, 2024.

EGU24-3988 | Orals | CL3.1.3

Global warming rates and surface temperature patterns through 2023: A Green’s function based investigation 

Bjorn H. Samset, Chen Zhou, Jan S. Fuglestvedt, Marianne T. Lund, Jochem Marotzke, and Mark D. Zelinka

The rate of global surface warming has seemingly been steady since the 1970s. Any progress towards halting climate change will be heralded by a slowdown in the warming rate, but tracking it on sub-decadal timescales is challenging because of strong interannual-to-decadal variability.

Recently, we used a physics-based Green’s function approach to filter out modulations to global mean surface temperature from sea-surface temperature (SST) patterns, and showed how this results in an earlier emergence of a discernible climate response to strong emissions mitigation. We have also shown how the filtered observations reveal a marked step-up in warming rate around 1990, consistent with known increases in ocean heat uptake. CMIP6 models are currently broadly unable to simultaneously capture the observed long-term warming rate, and such a step-up in rates over the last decades.

Here, we summarize these results, which were based on the CESM1 Earth System Model, and extend them to multiple, independently derived Green’s functions. We discuss how this toolkit can be complementary to existing attribution techniques. Then we apply it to an investigation of the surprising SST patterns in 2023, and what they imply about the potential causes for the high global mean surface temperature. Finally, we discuss the prospects for rapid detection of a climate response to strong greenhouse gas emissions mitigation, modulated by one or more areas of strong aerosol emissions changes, using Green’s functions or other techniques for reducing the influences of internal variability.

Key references:

Samset, B.H., Zhou, C., Fuglestvedt, J.S. et al. Steady global surface warming from 1973 to 2022 but increased warming rate after 1990. Commun Earth Environ 4, 400 (2023). https://doi.org/10.1038/s43247-023-01061-4

Samset, B.H., Zhou, C., Fuglestvedt, J.S. et al. Earlier emergence of a temperature response to mitigation by filtering annual variability. Nat Commun 13, 1578 (2022). https://doi.org/10.1038/s41467-022-29247-y

How to cite: Samset, B. H., Zhou, C., Fuglestvedt, J. S., Lund, M. T., Marotzke, J., and Zelinka, M. D.: Global warming rates and surface temperature patterns through 2023: A Green’s function based investigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3988, https://doi.org/10.5194/egusphere-egu24-3988, 2024.

EGU24-4029 | Orals | CL3.1.3

Novel methods needed to attribute human health impacts of climate change 

Dann Mitchell, Chin Yang Shapland, Eunice Lo, Kate Tilling, and Nick Leach

Attribution of different hazards and impacts of climate change to specific radiative forcings, including greenhouse gasses, is emerging as a critical field for evidence-based decisions used in, e.g. legal settings, and for Loss and Damage. A recent report published by Wellcome shows that there are 13 climate-health attribution publications to date, mainly using methods that are adapted from the core attribution community, including the good practice and IPCC recommendations. Most of these studies have cut corners from what many in the attribution community would call ‘the gold standard’, but for good reason, the health signal is more complex than a purely climate signal. Here I discuss a number of new approaches that can be used to attribute human health outcomes from climate change. I give an example using forecast-based attribution, which allows for a low-bias, high-spatial resolution assessment to be made. I concentrate on the Pacific NorthWest heatwave, and couple the results to all-cause, age-specific mortality. I show how this can be used for a variety of different health outcomes, including cause-specific mortality, and morbidity, e.g. mental health related, or vector-borne diseases. I discuss how different attribution techniques can be used to complement each other in the context of health. 

How to cite: Mitchell, D., Shapland, C. Y., Lo, E., Tilling, K., and Leach, N.: Novel methods needed to attribute human health impacts of climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4029, https://doi.org/10.5194/egusphere-egu24-4029, 2024.

EGU24-4187 | ECS | Posters on site | CL3.1.3

Humid, warm and treed ecosystems show longer time-lag of vegetation response to climate 

Xinran Gao, Alemu Gonsamo, and Wen Zhuo

Climate-induced temperature rise and shifting precipitation patterns across diverse global ecosystems impact vegetation growth. Due to the diverse nature of terrestrial ecosystems and their climates, interactions between climate and vegetation vary spatially and temporally. Most studies focus on simultaneous interactions, overlooking the legacy effects of climate on vegetation physiology and growth. In this research, we use satellite-observed Solar-Induced Fluorescence (SIF) and Enhanced Vegetation Index (EVI) as the indicators of vegetation photosynthesis and greenness to assess the time-lag effect in vegetation response to climate from May 2018 to Dec 2021. Specifically, we examine the relationship between SIF, EVI, and concurrent or antecedent climate variables containing precipitation, soil moisture, and temperature. Additionally, we compare different time-lags of these climate variables under distinct environmental conditions to understand how climatic conditions influence them. Our findings reveal that arid and cold climates exhibit more concurrent climate-vegetation interactions than other ecosystems. In contrast, humid ecosystems with high mean annual temperature and precipitation show a substantial time-lag response of vegetation to climate, for up to six months. Given the significance of time-lag effects in global climate-vegetation interactions, acknowledging these effects is paramount for improving our understanding of vegetation dynamics in a changing climate.

How to cite: Gao, X., Gonsamo, A., and Zhuo, W.: Humid, warm and treed ecosystems show longer time-lag of vegetation response to climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4187, https://doi.org/10.5194/egusphere-egu24-4187, 2024.

EGU24-4529 | Orals | CL3.1.3

The need for a detection and attribution system for the carbon cycle 

Ana Bastos, Na Li, and István Dunkl

Climate change is a consequence of the perturbation of the global carbon cycle through emission of CO2 and other greenhouse gases through fossil fuel burning, large-scale deforestation and other human activities since the industrial revolution. These emissions have been buffered by about 50% by the land and ocean carbon sinks, which have increased in pace with anthropogenic emissions. At the same time, changes in temperature and precipitation patterns and extremes due to climate change influence the efficiency of the land and ocean carbon sinks, so that their efficiency is projected to decline as negative consequences of climate change become more important.

Recent studies have pointed out that the global land carbon sink might be already slowing down and even declining in some regions, e.g., Europe. Understanding to which extent these recent trends are driven by climate change and extremes, policy changes or other factors is key to predict how the land sink will evolve in the coming decades and better constrain the potential for land-based climate change mitigation. However, at time scales of few years to decades, the role of internal climate variability on trends and extremes in climatic drivers of ecosystem carbon cycling cannot be ignored, and may mask or amplify changes in carbon sinks due to anthropogenic activities.

Here, we argue that extending Detection and Attribution (D&A) to the carbon cycle realm is crucially needed to support both climate science and policy assessments. We will discuss a number of conceptual and practical hurdles that make this exercise arguably even more challenging than climate D&A. We further present developments that can open the way towards a D&A for the carbon cycle, including improved quantification of carbon fluxes over land, the progress towards fast-track assessments of carbon flux anomalies following weather extremes, and the use of D&A techniques to study recent trends in the carbon cycle.

 

How to cite: Bastos, A., Li, N., and Dunkl, I.: The need for a detection and attribution system for the carbon cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4529, https://doi.org/10.5194/egusphere-egu24-4529, 2024.

EGU24-5240 | ECS | Posters on site | CL3.1.3

Different responses of cereals to interacting climatic indicators in Northern Europe. 

Faranak Tootoonchi and Giulia Vico

Precipitation and temperature interactively impact crop yields. Climate change is expected to be detrimental in most regions because of excessive temperatures and reduced water availability for crops. Nevertheless, at higher latitudes, warming might be an opportunity, unless excessive or co-occurring with other damaging conditions. To effectively evaluate the prospects of future staple crop production in Nordic conditions, we need to examine the past response of cereals to climatic indicators, not only averaged over the growing season but also at different physiologically relevant developmental stages. Moreover, we need to consider the legacy impacts of conditions during pre-growing period. Using county-level staple crop yield and meteorological data for 1965-2020 across Sweden, we systematically explored the role of various climate indicators on cereal yields (winter and spring wheat, spring barley and oats) in a Northern Europe context. For all crops, precipitation and average temperature over the entire growing season were the most relevant to explain yields. Combinations of higher precipitation totals and average temperature increased the yield for winter wheat. The same combination, as well as combinations of lower precipitation and lower average temperature, increased yield for spring barley. Increasing length of the longest dry period up to 3 weeks, combined with intermediate temperatures, increased yield for spring wheat and oats. Crops also responded to combinations of precipitation and temperature indicators during the post-flowering period for winter wheat and oats, and pre-flowering for spring barley, placing models with indicators in these periods as the second best models, based on the Akaike Information Criterion. For spring wheat, aridity index, i.e., a proxy of water availability prior to sowing, ranked as the second best explanatory indicator. Considering current future projections, both precipitation totals and temperature averages are likely to increase in Sweden. These changes in climatic conditions can lead to increasing opportunities for cultivation of spring crops such as oats with high resilience toward water logging, or promote a shift from spring sown-crops to autumn-sown crops such as winter wheat with more resilience toward unfavorable climatic conditions, even beyond currently cultivated latitudes.

How to cite: Tootoonchi, F. and Vico, G.: Different responses of cereals to interacting climatic indicators in Northern Europe., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5240, https://doi.org/10.5194/egusphere-egu24-5240, 2024.

EGU24-5703 | Orals | CL3.1.3 | Highlight

Detecting climate milestones on the path to climate stabilization 

Andrew H. MacDougall, Joeri Rogelj, Chris D. Jones, Spencer K. Liddicoat, and Giacomo Grassi

The era of anthropogenic climate change can be described by defined climate milestones. These milestones mark changes in the historic trajectory of change, and include peak greenhouse gas emissions, peak CO2 concentration, deceleration of warming, net-zero emissions, and a transition to global cooling. However, given internal variability in the Earth system and measurement uncertainty, definitively saying that a milestone has passed requires rigour, with the statistical illusion of the 2010s global warming hiatus being a recent cautionary tale of the need for robust methods.

Here we use CMIP6 simulations of peak-and-decline scenarios to examine the time needed to robustly detect three climate milestones: 1) the slowdown of global warming; 2) the end of global surface temperature increase; and 3) peak concentration of CO2. To detect these climate milestones we use a modified version of the Monte-Carlo based method of Rahmstorf et al. 2017, developed to test whether the global warming hiatus was an illusion. The method has been modified to account for auto-correlated noise characteristic of the climate system.

We estimate that it will take 40 to 60 years after a simulated slowdown in warming rate, to robustly detect the signal in the global average temperature record. Detecting when warming has stopped will also be difficult and for the one peak-and-decline scenario that has model simulations extended to the year 2300, it takes until the mid 22nd century to have enough data to conclude that  warming has stopped. Detecting that CO2 concentration has peaked is far easier, and a drop in CO2 concentration of 3 ppm is consistent with a greater than 99% chance that CO2 has peaked in all scenarios examined.  Overall it is sobering that even under aggressive mitigation scenarios a conclusive end to global warming is at the very outer edge of the living future, with only a small number of the very youngest children alive today likely to witness detection of the end of global warming.

How to cite: MacDougall, A. H., Rogelj, J., Jones, C. D., Liddicoat, S. K., and Grassi, G.: Detecting climate milestones on the path to climate stabilization, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5703, https://doi.org/10.5194/egusphere-egu24-5703, 2024.

EGU24-6720 | ECS | Posters on site | CL3.1.3

Future Precipitation Changes in North America in a Warmer Climate 

Wengui Liang and Ming Zhao

Future predictions in regional precipitation changes under global warming have heavily relied on the climate model simulations. Understanding the physical mechanisms of future hydroclimate changes in responses to different forcings will help improve our confidence in the model projections. Here we investigated the future precipitation changes in North America using the high-resolution(~50km) climate model GFDL-AM4, alongside other CFMIP models. We analyzed both the mean and extreme precipitation changes in the region during different seasons in response to distinct forcings: quadruple CO2, uniform SST warming, and a more realistic SST warming pattern. We noticed that the precipitation changes in North America are more sensitive to CO2 forcing in the summer than in the winter. The overall precipitation tends to decrease due to CO2 forcings and increases due to uniform warming. We will demonstrate the physical mechanisms of how CO2 suppresses the precipitation in the summer and how warmer climate can amplify the precipitation in most North American regions. To address uncertainties in future hydroclimate projections for North America, we will leverage multiple CFMIP models, providing a robust evaluation of model reliability in predicting these changes.

How to cite: Liang, W. and Zhao, M.: Future Precipitation Changes in North America in a Warmer Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6720, https://doi.org/10.5194/egusphere-egu24-6720, 2024.

EGU24-6807 | ECS | Posters on site | CL3.1.3

Identification of forced response and internal climate variability using ensemble linear dynamical modes 

Andrey Gavrilov, Sergey Kravtsov, and Maria Buyanova

The problem of accurate detection of climate response to slow external forcing in 19-21 centuries is complicated by the presence of internal climate variability, which can also exhibit slow (decadal and multidecadal) large-scale dynamics, and also by the fact that there is only one observed climate realization available. At the same time, state-of-the-art Earth system models (ESMs) exhibit different spatiotemporal content on slow time scales, and their ability to estimate forced and internal climate variability needs further verification, especially given a relatively poor (short) observational statistics with respect to slow time scales.

Here we present a method called ensemble linear dynamical mode (E-LDM) decomposition [1] which addresses the problem of forced signal and internal variability detection from small ensembles of ESM simulations. The method is based on the general assumption that the forced response is the same in all ensemble members and the internal variability is uncorrelated, while both of them can be essentially represented by a low-dimensional set of spatial patterns and corresponding forced and internal time series with certain time scales; the patterns, the time series and their time scales are optimized via the Bayesian framework. We compare the E-LDM method with other state-of-the-art methods of forced signal detection on synthetic and ESM-simulated data, and also discuss its applicability to the problem of intercomparison of ESMs and their verification with respect to real data. 

This research was supported by the state assignment of the Institute of Applied Physics of the Russian Academy of Sciences (Project No. FFUF-2022-0008). 

1. Gavrilov, A., Kravtsov, S., Buyanova, M., Mukhin, D., Loskutov, E., & Feigin, A. (2023). Forced response and internal variability in ensembles of climate simulations: identification and analysis using linear dynamical mode decomposition. Climate Dynamics, 1–28. https://doi.org/10.1007/S00382-023-06995-1.

How to cite: Gavrilov, A., Kravtsov, S., and Buyanova, M.: Identification of forced response and internal climate variability using ensemble linear dynamical modes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6807, https://doi.org/10.5194/egusphere-egu24-6807, 2024.

EGU24-7224 | ECS | Orals | CL3.1.3

Detection and Attribution of the Weakening of Global Angular Momentum 

Susmit Subhransu Satpathy and Christian L.E Franzke

The slowing down of the circulation in a warming climate due to anthropogenic forcings is still not understood. How internal variability and anthropogenic forced response in climate models influence the weakening of global angular momentum is still unclear. Here in this study, we utilise a 100-member ensemble simulation (CESM2-LENS) to detect and attribute the causes of the slowing down of atmospheric circulation. We observe a progressive decrease in angular momentum, projected to continue until 2100. The rate of weakening is observed to accelerate within the 1980~2020 period closely resembling the Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO) shift, with the entering of the positive phase of AMO and the negative phase of the PDO during the end of the 20th Century. Using, multivariate linear regression analysis, we provide the combined role of AMO, PDO, and GMST (a proxy for climate change signal) in influencing the angular momentum changes during the 20th and 21st centuries.
Further, we use a statistical-based approach applied to the ensemble simulations to extract the indirect response (internal variability) and provide the linkage of the AMO and PDO shift in contributing to the weakening rate. We annotate that the shift in the AMO and PDO phases in the mid-1990s weakened the upper-level westerlies over the Northern Atlantic Pacific region and accelerated the weakening of the Hadley Cell circulation. This was due to internal variability contributing to the global angular momentum balance change. Our results elucidate the potential role of the climate system's internal variability and anthropogenic forcings in modulating the distribution of the global angular momentum.

Keywords: Angular momentum; Atmospheric Circulation; Anthropogenic Forced Response; Atlantic Multidecadal Oscillation (AMO); Pacific Decadal Oscillation (PDO); Hadley Cell; Atlantic-Pacific walker cell

How to cite: Satpathy, S. S. and Franzke, C. L. E.: Detection and Attribution of the Weakening of Global Angular Momentum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7224, https://doi.org/10.5194/egusphere-egu24-7224, 2024.

EGU24-7532 | ECS | Posters on site | CL3.1.3

A new technical framework for probability analysis of hydrological wet and dry encounter in changing environment 

Yuli Ruan, Zhenxin Bao, Guoqing Wang, Cuishan Liu, and Yan Wang

The calculation of hydrological encounter probability is of great significance to formulating joint prevention schemes for flood and drought disasters. Under the combined influence of global climate change and human activities, the consistency of hydrological processes has been destroyed, and the frequency and intensity of hydrological wet and dry encounters between river basins have become more complex, significantly impacting regional water resources security. Thus, this study provides a high precision hydrological wet and dry encounter probability analysis technology coupled with efficient dimensionality reduction theory:(1)The optimal distribution model of each marginal distribution is selected in the distribution model selector.(2)The cumulative distribution function(CDF1) and cumulative experience frequency calculated by the optimal distribution model are loaded into the regular feature learner to obtain the relationship function (RF) between the cumulative distribution function and the cumulative experience frequency.(3)The indexes reflecting the impact of climate change and human activities are loaded into the efficient dimensionality reduction tool to obtain the comprehensive and human activity indexes.(4)After considering the influence of the changing environment, the cumulative distribution function (CDF2) of the marginal distribution is analyzed using the GAMLSS model, and it is substituted into the RF to obtain the final cumulative distribution function (CDF_final). (5)Finally, the CVINECopula function and the encounter probability calculation method are used to calculate the probability of encountering wet and dry. This study fully considers the impact of climate change and human activities on hydrology and effectively avoids the problem of dimension disaster through an efficient dimension reducer. In addition, the coupled distribution model selector and the rule feature learner can significantly improve the calculation accuracy of the encounter probability of water resources.

How to cite: Ruan, Y., Bao, Z., Wang, G., Liu, C., and Wang, Y.: A new technical framework for probability analysis of hydrological wet and dry encounter in changing environment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7532, https://doi.org/10.5194/egusphere-egu24-7532, 2024.

EGU24-8491 | ECS | Posters on site | CL3.1.3

The impact of Atlantic Multidecadal Variability on Baltic Sea temperatures limited to winter 

Florian Börgel, Matthias Gröger, H. E. Markus Meier, Cyril Dutheil, Hagen Radtke, and Leonard Borchert

We analyze multidecadal temperature fluctuations of the Atlantic Ocean and their influence on Northern Europe, focusing on the Baltic Sea, without a priori assuming a linear relationship of this teleconnection. Instead, we use the method of low-frequency component analysis to identify modes of multidecadal variability in the Baltic Sea temperature signal and relate this signal to the Atlantic climate variability. Disentangling the seasonal impact reveals that a large fraction of the variability in Baltic Sea winter temperatures is related to multidecadal temperature fluctuations in the North Atlantic, known as Atlantic Multidecadal Variability (AMV). The strong winter response can be linked to the interaction between the North Atlantic Oscillation and the AMV and is maintained by oceanic inertia. In contrast, the AMV does not influence the Baltic Sea’s summer and spring water temperatures.

How to cite: Börgel, F., Gröger, M., Meier, H. E. M., Dutheil, C., Radtke, H., and Borchert, L.: The impact of Atlantic Multidecadal Variability on Baltic Sea temperatures limited to winter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8491, https://doi.org/10.5194/egusphere-egu24-8491, 2024.

EGU24-8892 | Orals | CL3.1.3

The role of anthropogenic forcing on Australia’s Tinderbox (2017-19) Drought and its future likelihood  

Surendra Rauniyar, Scott Power, Pandora Hope, and Ulrike Bende-Michl

During the 2017-2019 period, a large region of the Murray Darling Basin in Australia received the lowest three-year rainfall resulting in an unprecedented drought, known as the Tinderbox Drought. The cool season (Apr-Sep) rainfall declined by more than 54% of the 1901-1960 average. An analysis of the observed rainfall records (1900 – 2020) shows that it was exceptionally unlikely that a decline of this magnitude could occur from internal climate variability alone. In this study, we analysed outputs from CMIP5 and CMIP6 climate models under different forcing conditions (i.e., pre-industrial, historical-all forcings and different future emissions pathways) to estimate the relative contribution of anthropogenic forcing and internal variability to the observed 2017-2019 cool season rainfall reduction and the future likelihood of three-year rainfall change as dry or drier than the Tinderbox Drought under different emission pathways. According to the models, taken at face value, the Tinderbox Drought is an extremely unlikely event, but the likelihood of its occurrence is being increased from virtually impossible to extremely unlikely by the anthropogenic forcing. This suggests that the Tinderbox Drought was largely dominated by internal climate variability, however, it would not have been as dry without the influence of anthropogenic forcing. We found that the likelihood of a three-year drought as dry or drier than the Tinderbox Drought is going to increase by 15% towards the end of the twenty-first century under a high-emission scenario. Even with a marked reduction in emissions, its likelihood will be still around 5 % which is 10 times higher than the pre-industrial climate. Only a few ensemble members simulate a drying as large or larger than the observed 2017-2019 drying. The inability of most models to fully replicate the large drying seen so far leads to two possible conclusions: the rainfall in this region is more sensitive to greenhouse gas concentrations than is currently modelled, or factors other than climate change have coincidentally reduced rainfall during the recent period of anthropogenic climate change. 

How to cite: Rauniyar, S., Power, S., Hope, P., and Bende-Michl, U.: The role of anthropogenic forcing on Australia’s Tinderbox (2017-19) Drought and its future likelihood , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8892, https://doi.org/10.5194/egusphere-egu24-8892, 2024.

EGU24-9233 | Orals | CL3.1.3 | Highlight

Multi-method attribution of the 2023 boreal summer temperature extremes in the Mediterranean region 

Neven-Stjepan Fuckar, Myles Allen, and Michael Obersteiner

As global climate change accelerates a spectrum of extreme events (e.g., heatwaves, droughts, etc.) are occurring in many parts of the world at an increasing frequency and intensity threatening the socio‐economic fabric of our modern civilisation. The boreal summer (JJA) 2023 was globally the warmest, while July and August 2023 were the two warmest months on the observational record. Embedded in these global conditions were series of strong heatwaves that in the Mediterranean region often reached above 40deg.C in daily maximums of surface (2m) air temperature (SAT). We apply multi-method attribution approach to illuminate the role of climate change in setting this expectational monthly and seasonal SAT conditions in the Mediterranean.

We utilise a collection of observations and reanalysis products combined with large ensembles of CMIP5 and CMIP6 historical and future simulations to analyse the role of atmospheric circulation and anthropogenic factors leading to these extreme events on monthly and seasonal timescales. We also use large ensembles of historical and counterfactual simulations of weather@home2 (climateprediction.net numerical experiments) globally distributed to and executed by volunteers on their home computers to assesses to what extent anthropogenic forcing altered the probability and magnitude of these extremes. We explore conditional perspective of the atmospheric circulation in this attribution analysis. The initial results indicate a significant role of the global climate change in modifying likelihood and intensity of these boreal SAT summer extreme events.

How to cite: Fuckar, N.-S., Allen, M., and Obersteiner, M.: Multi-method attribution of the 2023 boreal summer temperature extremes in the Mediterranean region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9233, https://doi.org/10.5194/egusphere-egu24-9233, 2024.

During summer 2020, Southern China experienced an extremely dry and hot summer, which was identified as one of the top ten domestic weather and climate extreme events in 2020 by China Meteorological Administration. Summer mean precipitation, surface air temperature (TAS), and number of hot days (NHD) were about 25% dryer, 1.5℃ warmer, and 11 days larger than the 1981–2010 normal. These are the 4th largest precipitation deficit, the highest TAS, and the 2nd highest NHD in the 1961–2020 record. The large-scale circulation anomalies over the West Pacific increased the likelihood of these extremely event. Anthropogenic influences on this event were investigated using 525-member ensembles of the atmosphere-only HadGEM3-GA6 model and the multi-model ensembles from the Coupled Model Intercomparison Project Phase 6 (CMIP6). Anthropogenic forcings doubled (increased by 11%) the probability of precipitation deficits, and increased occurrence more than  times for both TAS anomaly (1.25 probability higher) and NHD anomaly (300% probability higher) in HadGEM-GA6 (CMIP6). That means that the 2020-like TAS and NHD anomalies would not occur without anthropogenic forcings, and there is weak evidence that human influences decrease rainfall over Southern China. However, the precipitation deficit increased the likelihood of exceeding the observed thresholds for both TAS and NHD by about 17 (4) and 9 (11) times in HadGEM3-GA6 (CMIP6), respectively. Under SSP2-4.5 and SSP5-8.5 scenarios in the future, 2020-like hot but wet extreme events increase in magnitude and frequency, while the frequency of dry events declines.

How to cite: Wang, K. and Zheng, Z.: Anthropogenic Influences on the Extremely Dry and Hot Summer of 2020 in Southern China and Projected Changes in the Likelihood of the Event , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9654, https://doi.org/10.5194/egusphere-egu24-9654, 2024.

EGU24-10578 | ECS | Posters on site | CL3.1.3

Estimation of the dynamical contribution to European temperature variations. 

Enora Cariou, Julien Cattiaux, Saïd Qasmi, and Aurélien Ribes

Europe is one of the fastest-warming region of the world and temperatures of the recent years have been systematically higher than best estimates of the forced response. This may be due to internal variability in favor of warmer situations, or it may indicate that the forced response is underestimated.

In Europe, inter-annual temperature variations are primarily linked to the variability of North Atlantic atmospheric dynamics. The temperature T for a given day and year can be written as the sum of the forced response µ (the non-stationary climate normal) and the internal variability D + ε (D the atmospheric dynamics and ε the residual).

We investigate two methods for estimating the forced response in transient simulations, via a denoising of the temperature T from the dynamical term D. To test these methods, we use a perfect model framework, here the large ensemble of 50 MIROC6 transient simulations. The mean of the large ensemble provides an accurate estimate of the forced response (the « truth »), to which estimates from individual members can be compared.

The contribution of the D term is first estimated with a circulation analogues method. We reconstruct the temperatures of one individual member from similar atmospheric situations of the other 49 members. The analogues are calculated on the T-µ series, rather than on the T series directly.

Second, we reconstruct temperatures using deep neural networks. Using a U-NET, we estimate the function f in the equation T=µ+f(X)+ ε, where X is the sea level pressure. Our network is trained on the different members of the large ensemble.

How to cite: Cariou, E., Cattiaux, J., Qasmi, S., and Ribes, A.: Estimation of the dynamical contribution to European temperature variations., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10578, https://doi.org/10.5194/egusphere-egu24-10578, 2024.

EGU24-10870 | Orals | CL3.1.3

ClimateMeter: Putting Extreme Weather Phenomena in Climate Perspective  

Davide Faranda and the The ClimaMeter Team

Climate change is a global challenge with manifold and widespread consequences, including the intensification and increased frequency of numerous extreme weather phenomena. In response to this pressing issue, we introduce ClimaMeter, a platform designed to assess and contextualize extreme weather phenomena in relation to climate change. The platform provides near-real-time information on the dynamics of extreme events, serving as a resource for researchers, policymakers, and acting as a scientific outreach tool for the general public. ClimaMeter currently analyzes heatwaves, cold spells, heavy precipitation, and windstorms. This presentation sheds light on the methodology, data sources, and analytical techniques that ClimaMeter relies on, offering a comprehensive overview of its scientific foundations. To illustrate ClimaMeter, we present some examples of recent extreme weather events. Additionally, we highlight the role of ClimaMeter in promoting a profound understanding of the complex interactions between climate change and extreme weather phenomena, with the hope of ultimately contributing to informed decision-making and climate resilience. Follow us on X @ClimaMeter and visit www.climameter.org.

 
 
 

How to cite: Faranda, D. and the The ClimaMeter Team: ClimateMeter: Putting Extreme Weather Phenomena in Climate Perspective , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10870, https://doi.org/10.5194/egusphere-egu24-10870, 2024.

EGU24-11020 | ECS | Orals | CL3.1.3

Half of the unprecedented global soybean production failure in 2012 is attributable to climate change. 

Raed Hamed, Corey Lesk, Theodore G. Shepherd, Henrique M.D Goulart, Linda van Garderen, Bart Van den Hurk, and Dim Coumou

The United States (US), Brazil, and Argentina collectively produce about 75% of the world's soybean supply. In 2012, soybean crops failed in these three major producing regions due to spatially compound hot and dry weather across North and South America. This led to unprecedented shortages in the global supply, resulting in record-high market prices. Despite the severity of this event, the role of historical and future anthropogenic warming in influencing such occurrences remains unknown. Here, we present different impact storylines of the 2012 event by imposing the same seasonally evolving atmospheric circulation in a pre-industrial, present day (+1°C above pre-industrial), and future (+2°C above pre-industrial) climate. We use so-called nudged atmospheric simulations and train a statistical model to estimate yield losses from meteorological conditions. While the drought intensity is rather similar under different warming levels, our results show that anthropogenic warming strongly amplifies the impacts of such a large-scale circulation pattern on global soybean production, driven not only by warmer temperatures, but also by stronger heat-moisture interactions. We estimate that 51% (47-55%) of the global soybean production deficit in 2012 is attributable to climate change. Future warming (+2°C above pre-industrial) would further exacerbate production deficits by 58% (46-67%), compared to present-day 2012 conditions. This highlights the increasing intensity of global soybean production shocks linked to similar atmospheric conditions with warming and thus requires urgent adaptation strategies.

How to cite: Hamed, R., Lesk, C., Shepherd, T. G., M.D Goulart, H., van Garderen, L., Van den Hurk, B., and Coumou, D.: Half of the unprecedented global soybean production failure in 2012 is attributable to climate change., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11020, https://doi.org/10.5194/egusphere-egu24-11020, 2024.

EGU24-11126 | ECS | Orals | CL3.1.3

Reconciling risk-based and storyline attribution with Bayes theorem 

Sebastian Buschow, Petra Friederichs, and Andreas Hense

Current research on climate change attribution falls into two broad camps. Classic “risk-based” studies typically assess differences in the distribution of some climate variable between two scenarios: one representing factual conditions and one without man-made climate change. More recently, this line of investigation has been complemented by “storyline” approaches, which consider the impact of climate change, conditional on a particular state of the internal climate variability.
The apparent gap between the two approaches can be bridged with Bayesian statistics. We demonstrate that a conditional attribution statement depends on two unconditional Bayesian decisions between the scenarios, one using all information and one using everything except the event of interest.
To illustrate this result, we employ Gaussian mixture models to conduct conditional and unconditional attribution studies of European summer temperatures based on multiple CMIP6 ensemble simulations. We find that the resulting attribution statements can be either strengthened or weakened by the conditioning, depending on the estimated covariance structure. 

How to cite: Buschow, S., Friederichs, P., and Hense, A.: Reconciling risk-based and storyline attribution with Bayes theorem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11126, https://doi.org/10.5194/egusphere-egu24-11126, 2024.

EGU24-12127 | ECS | Orals | CL3.1.3

Enhanced global carbon cycle sensitivity to tropical temperature linked to internal climate variability 

Na Li, Sebastian Sippel, Nora Linscheid, Christian Rödenbeck, Alexander J. Winkler, Markus Reichstein, Miguel D. Mahecha, and Ana Bastos

The sensitivity of annual atmospheric CO2 growth rate (AGR) variations to tropical temperature has almost doubled between 1959 and 2011, a trend that has been linked to increasing drought in tropical ecosystems. This sensitivity metric has been used to suggest an emergent constraint of the future land carbon sink in response to climate change. However, a recent study showed that this sensitivity has decreased since then. Here, we investigate whether this doubling sensitivity reflects a forced response to climate change, or if it may arise due to internal climate variability. 

We show that, first, several similar events have occurred in individual simulations of Earth System Model Large Ensembles since 1851, but without changes in the ensemble mean's forced signal, suggesting the possibility of the doubling sensitivity being an internally-driven signal. Second, these observed doubling sensitivity events are linked to few strong El Niño events, such as 1982/83 and 1997/98. Such extreme events result in enhanced carbon release in tropical and extratropical terrestrial ecosystems, thus increasing the variance of the global land sink. Third, the doubling event is mostly explained by an increase in the variance of global AGR (rather than variance of tropical temperature or changes in the covariance), so that the signal constitutes only an "apparent" sensitivity change. In conclusion, the doubling sensitivity is not necessarily caused by forced climate change, but may arise from tropical and northern land sinks associated with internal climate variability.


Wang, X., Piao, S., Ciais, P. et al. A two-fold increase of carbon cycle sensitivity to tropical temperature variations. Nature 506, 212–215 (2014). https://doi.org/10.1038/nature12915

Luo, X., Keenan, T. F. Tropical extreme droughts drive long-term increase in atmospheric CO2 growth rate variability. Nat Commun 13, 1193 (2022). https://doi.org/10.1038/s41467-022-28824-5

How to cite: Li, N., Sippel, S., Linscheid, N., Rödenbeck, C., Winkler, A. J., Reichstein, M., Mahecha, M. D., and Bastos, A.: Enhanced global carbon cycle sensitivity to tropical temperature linked to internal climate variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12127, https://doi.org/10.5194/egusphere-egu24-12127, 2024.

EGU24-12807 | ECS | Orals | CL3.1.3

Children disproportionally exposed to attributable heatwaves at low-latitude low-income countries 

Rosa Pietroiusti, Erich Fischer, Rupert Stuart-Smith, Luke Harrington, Luke Grant, Annalisa Savaresi, Sam Adelman, and Wim Thiery

Heatwaves are increasing in frequency, intensity, and duration, and represent the category of extreme event that is most easily attributable to anthropogenic warming. Yet how the spatiotemporal patterns of attribution outcomes link to population dynamics and demographic patterns is still poorly understood. Here we investigate whether children and young people are already being affected by a disproportionately greater number of attributable heat extremes, especially in the Global South. Using observations, reanalysis, and simulations of temperature changes available through the ISIMIP3b and CMIP6 projects, in combination with demographic data, we will investigate whether temperature extremes emerge more clearly and consistently from the noise across low-income countries in lower latitudes, which have some of the youngest populations. Our anticipated findings could have implications for children and young people seeking redress from climate harms, for example through climate lawsuits.

How to cite: Pietroiusti, R., Fischer, E., Stuart-Smith, R., Harrington, L., Grant, L., Savaresi, A., Adelman, S., and Thiery, W.: Children disproportionally exposed to attributable heatwaves at low-latitude low-income countries, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12807, https://doi.org/10.5194/egusphere-egu24-12807, 2024.

EGU24-13114 | Posters on site | CL3.1.3

Attribution of hydrological trends and change points in the discharge of Mackenzie River during 1972-2020 

John Xiaogang Shi, Jiayi Xu, and Daqing Yang

Due to the amplification of climate change in the polar regions, the changes in discharge are more pronounced for the Arctic rivers, which are relevant to other hydro-climatic indicators (e.g., precipitation, snowmelt, groundwater, and permafrost) in the river basin. To investigate the recent changes of river discharge in the Mackenzie River Basin (MRB) responding to climate change, this study used the Mann-Kendall trend test and correlation coefficient approach to examine the long-term variability in discharge at three gauges along the watercourses of MRB between 1972 and 2020, focusing on the inter-decadal trends and the occurrence of hydrological extremes. From the 1970s to 2000s, the discharge in the MRB has increased significantly. However, a reverse trend was shown in the 2010s that is more pronounced in winter and spring. Moreover, the analyses in annual discharge have revealed that the extremely low discharge in 1994/1995 is highly associated with the changes in snowfall, while the extremely high discharge events in 2012/13 and 2019/2020 are more influenced by the reduced sea ice extent and peatland burning over the last decades.

How to cite: Shi, J. X., Xu, J., and Yang, D.: Attribution of hydrological trends and change points in the discharge of Mackenzie River during 1972-2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13114, https://doi.org/10.5194/egusphere-egu24-13114, 2024.

As the science of climate attribution continues to gain importance, we should remember that this discipline reaches back to the 1920s, when catastrophic droughts motivated research into the Southern Oscillation (Walker and Bliss 1932). Climate attribution existed before human-induced climate change, and this deep literature belies recent suggestions that limited research categorically constrains contributions to efforts like loss and damage compensation (King et al. 2023). Some hazards, like droughts and extreme temperatures, are much easier to link to climate change (Noy et. al, 2023). ENSO-related droughts, in particular, represent a very important and well-studied type of hazard. Techniques for linking droughts to impacts in food insecure countries are well-developed, and formal attributions of eastern and southern African droughts (e.g. Funk et al. 2016, 2018, 2019, 2023A, 2023B) have supported advances in long-lead forecasting.

Building on this work, in this talk we connect ‘modal’ analyses of sea surface temperatures (SST) with an evaluation of reanalysis ‘atmospheric heating’. Our modal framework grows out of analyses of ENSO-residual SST (Compo and Sardeshmukh, 2010; Newman and Solomon 2012; Lyon et al. 2014); most of the variance of observed and simulated global SST can be described an ENSO mode and an ENSO-residual West Pacific Warming Mode (WPWM, Funk and Hoell 2015; Funk 2023B).

In this talk we describe observed and CMIP6-simulated changes in ENSO and WPWM Principal Components (PC) time series, and highlight the real-world implications of two key characteristics: the long term increases in both, and their modest inverse correlation on decadal time scales, which leads to more extreme ocean states. Strong El Niños correspond to large ENSO PC values. La Niña events in a warming Pacific Ocean are associated with exceptionally warm west Pacific SST, corresponding to the increasing WPWM PC, and La Niña-related droughts (Funk et al. 2023B).

While these PC extremes produce very warm Pacific SST, and strong SST gradients, formally evaluating the impact of these SST patterns can be challenging. Tropical Pacific atmospheric heating, which drives many ENSO-related teleconnections provides a useful metric of ENSO strength. This heating combines diabatic heating due to precipitation, radiation, sensible heating and evaporation and adiabatic heating due to heat convergence. Using 1950-2023 ERA5 reanalyses, and CPC Oceanic Niño Index-based ENSO event definitions, we suggest that when  ENSO events occur, ENSO-related atmospheric heating extremes have become substantially and significantly more energetic. Contrasting 1996-2022 and 1950-1996 El Niño events, we find very large increases in January-to-June heating over the equatorial eastern Pacific. A similar contrast for La Niña events indicates large heating increases over the western Pacific that extend from June of into September of the following year. Hence, ENSO events are likely becoming stronger and longer due to climate change. We conclude by showing how CMIP6 SST simulations and statistical heating/SST relationships can be used to estimate climate change-related enhancements to these heating extremes.

Facing a future “characterized by unprecedented aridification/wetting punctuated by more severe extremes” (Stevenson et al. 2021), these insights can help support the formal attribution of ENSO-related droughts.

How to cite: Funk, C., Stevenson, S., Harrison, L., and Wehner, M.: A modal/thermodynamic attribution analysis suggests that climate change is making La Niña and El Niño events stronger, longer and more energetic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13123, https://doi.org/10.5194/egusphere-egu24-13123, 2024.

EGU24-13472 | Orals | CL3.1.3

The Detection and Attribution Model Intercomparison Project: CMIP6 highlights and plans for CMIP7 

Nathan Gillett, Isla Simpson, Gabi Hegerl, Reto Knutti, Aurélien Ribes, Hideo Shiogama, Daithi Stone, Claudia Tebaldi, Piotr Wolski, and Wenxia Zhang

The Detection and Attribution Model Intercomparison Project (DAMIP) coordinates single forcing climate model simulations for detection and attribution analysis and other applications. DAMIP simulations were carried out with fifteen climate models as part of CMIP6, and these simulations were used in at least 270 published articles. These simulations were also used directly in at least five chapters of the IPCC Sixth Assessment Working Group I Report, and they underpinned the estimate of anthropogenic attributable warming highlighted in the Summary for Policymakers of that report, and quoted directly in the UNFCCC Glasgow Climate Pact. For CMIP7, natural-only, well-mixed greenhouse gas-only, and aerosol-only simulations have been proposed as fast track DAMIP simulations, and planning of a broader set of experiments is currently underway. This talk will highlight key DAMIP results from CMIP6, and will discuss plans for the CMIP7 version of DAMIP. Comments and suggestions regarding the CMIP7 DAMIP experimental design will be welcomed.

How to cite: Gillett, N., Simpson, I., Hegerl, G., Knutti, R., Ribes, A., Shiogama, H., Stone, D., Tebaldi, C., Wolski, P., and Zhang, W.: The Detection and Attribution Model Intercomparison Project: CMIP6 highlights and plans for CMIP7, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13472, https://doi.org/10.5194/egusphere-egu24-13472, 2024.

EGU24-13745 | ECS | Orals | CL3.1.3

The Emergence of Low-Frequency Variability: Comparison of Historical Data and Simulations 

Raphaël Hébert, Vanessa Skiba, and Thomas Laepple

Regional climate change projections over the course of the 21st century require the accurate simulation of both anthropogenic and natural variability. The spatial patterns of natural variability are relatively well constrained on sub-decadal timescales based on instrumental data evidence, and climate models can simulate them. For longer (supra-decadal) timescales, however, the spatial patterns of natural (temperature) variability are poorly constrained because of the shortness of the instrumental record and the overlap with anthropogenic influences. Insights gained from paleoclimate data over land in mid-latitudes suggest that oceanic influence was the main driver of increased low-frequency natural variability, in contrast to its stabilizing role on sub-decadal timescales. Here, by studying the spatial imprint of multi-decadal climate variability, we show that the instrumental data is consistent with this hypothesis. While the pattern is also observed in climate models, it is much weaker and seems to rely solely on forced variability. Therefore, while climate models can simulate anthropogenic warming, our evidence indicates, particularly over the northern land mid-latitudes, that they are not simulating supra-decadal natural variability (forced and internal) consistent with instrumental observations in terms of the spatial pattern and its amplitude.  

How to cite: Hébert, R., Skiba, V., and Laepple, T.: The Emergence of Low-Frequency Variability: Comparison of Historical Data and Simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13745, https://doi.org/10.5194/egusphere-egu24-13745, 2024.

Climate change has given a new dimension to the unpredictability of rice yields. Climate variability and change impact rice yield directly through the variation of climatic variables. Rice yield is also affected by pests and disease occurrences. However, climatic impacts on rice pests and diseases are not well known. This study aims to investigate the impact of climate variability on rice yield and diseases in coastal Bangladesh through systematic literature review (SLR), complemented by climate-crop data analysis. Mann-Kendall (MK) tests were conducted to assess the trends in climatic variables, while a mixed-effects model was employed to evaluate the influence of climatic variables on rice yield. Logit models were also used to identify the most critical weather parameters influencing the disease occurrences. SLR indicated that 61% of studies reported negative effect while 18% reported positive effect of climate variability on rice yield. Historical climate-crop data analysis indicates that both temperature (0.04°C/year) and humidity (0.14 %/year) have significantly increased. Despite a short-term positive effect of temperature and humidity on rice yield, a chronic cumulative negative effect was found over 38 years. Moreover, there was a positive correlation of rice yield with temperature and humidity. Additionally, trends of climatic variables had a negative effect (-10.9%) which is equivalent to a yield reduction of 140 kg/ha/year. Due to increased temperature and humidity, the occurrence of sheath blight disease was increasing higher than that of blast and bacterial blight disease. These findings are consistent with SLR. Sustainable rice production therefore needs better adaptation strategies at the farmers’ level.  It is suggested that the agricultural extension department should provide training to farmers regarding climatic parameter changes and their impact on rice diseases and yield, usage of climate information services, as well as climate-smart rice production, is imperative for better adaptation to climate change.

How to cite: Mousumi, M. A. and Paparrizos, S.: Impacts of climate variability on rice yield and diseases in coastal Bangladesh: A systematic literature review with climate and crop data analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14299, https://doi.org/10.5194/egusphere-egu24-14299, 2024.

EGU24-14889 | ECS | Orals | CL3.1.3

Compound events drowned in climate noise? The benefits of employing a regional SMILE in compound hot and dry summer assessment  

Andrea Böhnisch, Elizaveta Felsche, Magdalena Mittermeier, Benjamin Poschlod, and Ralf Ludwig

Compound hot and dry extremes like the recent summers of 2015, 2018, and 2022 have an impact on a wide range of sectors in Europe, including health, transport, energy production, ecology, agriculture, and forestry. Current research suggests that climate change will increase the intensity, frequency, and duration of joint hot and dry extreme summers in Europe.

However, how robust and skilful are assessments of these compound events?

Here, we understand compound hot and dry extreme summers as the joint exceedance of temperature and (negative) precipitation thresholds (thresholds: 2001-2020 summer 95th percentiles). Since this definition results in particularly rare events, a robust climatology of these extreme events can hardly be obtained from observational time series alone. To investigate these events and their variability, larger sample sizes are required. Some studies so far focus on temporally limited observational records and regional multi-model ensembles that both do not allow for robust climate variability assessment. Others address internal climate variability by using single-model initial condition large ensembles (SMILEs), but based on global models and thus truncating spatial heterogeneity. In an attempt to meet these limitations, we exploit a 50-member SMILE of the Canadian Regional Climate Model, version 5, at 12 km resolution (CRCM5-LE, RCP 8.5 from 2006 onwards, driven by the Canadian Earth System Model Version 2 large ensemble, CanESM2-LE) in this study. Owing to its large size and high spatial resolution, the CRCM5-LE is a yet unique source for analyzing compound events on a regional scale.

We consider detrended ERA5-Land data during 1955-2023 for evaluation purposes. In general, comparing single observational time series to SMILEs remains challenging due to internal climate variability. By using, among others, a bootstrapping approach, we find a very good agreement of the local compound event frequency distribution in the CRCM5-LE and ERA5-Land. Also, regional hotspots of event frequencies agree in the SMILE and reanalysis data. Going one step further, we also statistically disentangle climate change signals and internal variability in event frequencies at two global warming levels (+2 °C, + 3°C) by means of, e.g., signal-to-noise ratios.  

In general, the regional model (re)produces fine-scale spatial patterns of hot and dry compound events (e.g., mountains, land-sea contrast). These are found in event frequencies and change signals at impact-relevant scales. Furthermore, the application of a SMILE provides an extensive database of events. The latter is crucial for assessing trends and climatologies of highly variable events like compound hot and dry extremes. In combining a regional climate model and the SMILE approach, we thus show the benefits of a regional SMILE for addressing the uncertainty in compound event assessment.

How to cite: Böhnisch, A., Felsche, E., Mittermeier, M., Poschlod, B., and Ludwig, R.: Compound events drowned in climate noise? The benefits of employing a regional SMILE in compound hot and dry summer assessment , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14889, https://doi.org/10.5194/egusphere-egu24-14889, 2024.

The Pacific Walker circulation (PWC) and Hadley circulation (HC) are the most prominent circulations of the Earth, which can exert far-reaching impacts on global and regional hydrological cycles. Both of these two large-scale circulations have experienced significant changes under global warming. Specifically, the PWC is reported to strengthen since the 1980s while the HC is proposed to widen. The causes behind these observed changes have been the subject of climate research, with divergent views on the influence of external forcing versus internal variability. Here, based on initial-condition large ensemble simulations, we quantify the relative contributions of internal variability and external forcing in modulating recent changes in tropical large-scale atmospheric circulations. We find that the recent PWC strengthening and HC widening is robust consequences of internal variability rather than external forcing. We further reveal that Interdecadal Pacific Oscillation (IPO) is the dominant internal mode, with its phase evolution contributing about 63% of the observed PWC strengthening and at least 73% of the HC widening in the Northern Hemisphere.

How to cite: Wu, M.: Role of Interdecadal Pacific Oscillation (IPO) in modulating recent changes in tropical large-scale atmospheric circulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15720, https://doi.org/10.5194/egusphere-egu24-15720, 2024.

EGU24-16821 | Posters on site | CL3.1.3

Anthropogenic Climate Change Attribution to a Giant Hail Event in August 2022 in Northeastern Spain  

Ana Morata, Ana Montoro-Mendoza, Carlos Calvo-Sancho, Juan Jesús Gónzalez-Alemán, Javier Díaz-Fernández, Pedro Bolgiani, José Ignacio Farrán, Daniel Santos, and María Luisa Martín

On August 30th, 2022, a giant hailstorm occurred in northeastern Spain with hailstones reaching up to 12 cm, a record for Spain. In addition to the damage to roofs, cars, and croplands, the giant hailstorm caused 67 injuries and even one fatality. During the event, the weather pattern over Europe was a quasi-omega block in the Western Mediterranean with a narrow cut-off low over the center-eastern of France, inducing the development of the very short-wave trough in extreme northeastern Spain. Such setup, the typical summer thermal-low and very high Mediterranean SSTs, promoted vorticity advection and a high amount of moisture in low-levels. In this study, that constitutes the first climate change attribution to giant hailstorms, we study the climate change effect in the hail-favorable environment, in which hailstone growth was promoted, by applying the pseudo-global warming approach. Three climatic models from CMIP6 (EC-EARTH3, CESM-WACCM and MRI-ESM2-0) are used to obtain the climate change increment (Present-Preindustrial), needed in the pseudo-global warming approach. The increment is computed for all the prognostic variables and added to ERA5 to be used as initial/boundary conditions. The WRF-ARW model is used to simulate the event. A control simulation is performed using the ERA5 initial conditions without perturbation to compare it with the preindustrial-like climate. The results indicate that the environment in a preindustrial-like climate would have been less conducive to convective hazards with a significant reduction in the studied thermodynamic parameters. The hailstorm event considering the preindustrial-like climate would have been less severe than the real event in the present climate. The applied methodology opens up the possibility of a new way to attribute such events to the anthropogenic climate change.

How to cite: Morata, A., Montoro-Mendoza, A., Calvo-Sancho, C., Gónzalez-Alemán, J. J., Díaz-Fernández, J., Bolgiani, P., Farrán, J. I., Santos, D., and Martín, M. L.: Anthropogenic Climate Change Attribution to a Giant Hail Event in August 2022 in Northeastern Spain , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16821, https://doi.org/10.5194/egusphere-egu24-16821, 2024.

EGU24-16870 | ECS | Posters on site | CL3.1.3

Statistical methods for estimating the forced component of historical SST and precipitation changes: A bias-variance tradeoff 

Maren Höver, Robert Jnglin Wills, and Nora Fahrenbach

Distinguishing the influences of externally forced responses and internal variability on the observed climate is critical for attributing historical climate change and for evaluating the forced responses simulated by climate models. Statistical methods such as optimal fingerprinting, low-frequency component analysis (LFCA), and dynamical adjustment have proven useful for this application. The skill of such statistical methods can be evaluated using climate model large ensembles, where the forced response is estimated by averaging over many realizations. Our study uses large ensemble simulations from five different climate models to evaluate the performance of three statistical methods for this application: (1) low-frequency component analysis, (2) signal-to-noise maximizing pattern optimal fingerprinting (SNMP-OF), which uses the patterns from an ensemble-based signal-to-noise maximizing pattern (SNMP) analysis for optimal fingerprinting, and (3) a novel method based on SNMP analysis called fingerprint maximizing patterns (FMP), which finds patterns within observed variability that have the maximum fingerprint of the model-based forced response. 

We investigate how the root mean square error (RMSE) of these three methods varies across the choices of hyperparameters and show that all methods have a similar maximum skill. However, the contribution to the RMSE from the mean bias in the forced response estimate varies across the methods, with SNMP-OF and FMP showing a larger mean bias than LFCA. This demonstrates that methods that largely rely on the model forced response to obtain the observed forced response may give biased estimates and underestimate the uncertainty in these estimates due to the bias-variance tradeoff. 

Additionally, we apply these methods to observed Sahel precipitation, which is extensively debated in terms of its forced component, and closely related North Atlantic sea surface temperatures (SSTs). We show that while the methods give a robust estimate of the forced response in North Atlantic SSTs from 1950 to 2022, their estimates of the forced response in Sahel precipitation over the same period differ in sign. The fact that these estimates of the Sahel precipitation response differ substantially, despite all methods performing similarly well for large ensembles, suggests substantial epistemic uncertainty in estimates of the forced precipitation response in this region.

How to cite: Höver, M., Jnglin Wills, R., and Fahrenbach, N.: Statistical methods for estimating the forced component of historical SST and precipitation changes: A bias-variance tradeoff, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16870, https://doi.org/10.5194/egusphere-egu24-16870, 2024.

EGU24-17481 | ECS | Posters on site | CL3.1.3 | Highlight

How exceptional was the September 2023 global heat?  

Svenja Seeber, Dominik L. Schumacher, Mathias Hauser, and Sonia I. Seneviratne

In September 2023, the global mean surface temperature (GMST) anomaly reached a new maximum, exceeding the previous record by an unprecedented 0.5 °C. This is not only the highest monthly anomaly ever recorded, but also stands out compared to the more moderate anomalies seen during the record-breaking summer of 2023. It is likely that developing El Niño conditions are at least partly responsible for the anomalous heat. However, it remains unclear if such a sharp rise in global mean temperature is to be expected due to our warming climate and internal climate variability or if the September 2023 GMST was a rare event even for the current global warming level. In other words, could we soon witness even more intense monthly temperature anomalies? Moreover, are climate models able to adequately reproduce such extreme records? 

To address these questions, we analyze observations as well as CMIP6 model simulations and employ techniques from extreme event attribution. These statistical approaches typically focus on regional-scale weather and climate extremes. Here, we apply them to the September 2023 global heatwave to investigate the occurrence probability of this event, considering the influence of global warming as well as El Niño.

 

How to cite: Seeber, S., Schumacher, D. L., Hauser, M., and Seneviratne, S. I.: How exceptional was the September 2023 global heat? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17481, https://doi.org/10.5194/egusphere-egu24-17481, 2024.

EGU24-17768 | ECS | Orals | CL3.1.3

Collective attribution of historical heatwaves to anthropogenic climate change 

Yann Quilcaille, Lukas Gudmundsson, Thomas Gasser, and Sonia I. Seneviratne

Event attribution has significantly developed over the past years, with an increasing number of events being attributed to human-induced climate change. Typical event attribution studies focus on the assessment of individual events of high societal relevance. While this allows for a detailed analysis and a comprehensive interpretation, it also implies that the influence of anthropogenic climate change is not assessed for many extreme events. Here, we present the first collective attribution of 149 historical heatwaves reported over the 2000-2021 period. We apply a well-established extreme weather attribution approach (Philip et al., 2020; van Oldenborgh et al., 2021) to heatwaves in the EM-DAT database (EM-DAT, 2023). Each of these heatwaves were reported for severe societal impacts, making them relevant for attribution. For each listed heatwave, we identify the event in observational data (ERA5, BEST) and CMIP6 data, then we estimate the probability distribution conditional on global mean surface temperature, deduce the occurrence probabilities of the events for present and pre-industrial climate conditions. We discuss the method and the choices made to systematize the definition of the event, the evaluation of the probabilities and the selection of the datasets. The results of this framework is consistent with existing attribution studies, albeit with limits. This work calls for a more systematic reporting of heatwaves, and paves the way for the use of these results in climate litigation cases.

Furthermore, we calculate the contributions in global mean surface temperature of 110 fossil fuels and cement companies using their CO2 and CH4 emissions (Heede, 2014) and the reduced-complexity Earth system model OSCAR (Gasser et al., 2017). This collective attribution allows to extend these contributions to the analyzed historical heatwaves. The majority of heatwaves are made substantially more probable and intense due to six carbon majors that represent 0.30°C of global mean surface temperature. Though, other carbon majors cannot be neglected, as their sole contribution may be enough to make some heatwaves possible. We suggest that extending attribution studies to the actors could consolidate their applicability for climate litigation.

 

EM-DAT, CRED / UCLouvain: www.emdat.be, last access: 09.01.2024.

Gasser, T., Ciais, P., Boucher, O., Quilcaille, Y., Tortora, M., Bopp, L., and Hauglustaine, D.: The compact Earth system model OSCAR v2.2: Description and first results, Geoscientific Model Development, 10, 271-319, 10.5194/gmd-10-271-2017, 2017.

Heede, R.: Tracing anthropogenic carbon dioxide and methane emissions to fossil fuel and cement producers, 1854–2010, Climatic Change, 122, 229-241, 10.1007/s10584-013-0986-y, 2014.

Philip, S., Kew, S., van Oldenborgh, G. J., Otto, F., Vautard, R., van der Wiel, K., King, A., Lott, F., Arrighi, J., Singh, R., and van Aalst, M.: A protocol for probabilistic extreme event attribution analyses, Adv. Stat. Clim. Meteorol. Oceanogr., 6, 177-203, 10.5194/ascmo-6-177-2020, 2020.

van Oldenborgh, G. J., van der Wiel, K., Kew, S., Philip, S., Otto, F., Vautard, R., King, A., Lott, F., Arrighi, J., Singh, R., and van Aalst, M.: Pathways and pitfalls in extreme event attribution, Climatic Change, 166, 13, 10.1007/s10584-021-03071-7, 2021.

How to cite: Quilcaille, Y., Gudmundsson, L., Gasser, T., and Seneviratne, S. I.: Collective attribution of historical heatwaves to anthropogenic climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17768, https://doi.org/10.5194/egusphere-egu24-17768, 2024.

EGU24-17854 | ECS | Posters virtual | CL3.1.3

Attribution of extreme weather events in Germany 

Jonas Schröter, Miriam Tivig, Philip Lorenz, and Frank Kreienkamp

Since 2019, the Deutsche Wetterdienst (DWD) has been actively developing a workflow for the operational attribution of extreme weather events. The primary objective is to automate as many steps of the process as possible with minimal human input, to communicate the impact of climate change on a particular event within days to weeks after it has happened.

In parallel with some studies together with the World Weather Attribution group (WWA), like the study by Tradowsky et al. (2023) regarding the flash-floods in Western Europe in 2021, the decision was made to develop a national rapid attribution workflow. This leads to the opportunity to semi-operationally attribute more (and in addition weaker) extreme events. So far, in the first phase of the ClimXtreme project (https://climxtreme.net/), a prototype workflow for probability-based attribution was established based on the protocol used by the WWA (Philip et al., 2020). Now, in the second phase of the project, a synthesis tool will be added. The optimal approaches for a synthesis tool of different model results and observations are still a topic of active discussion. The synthesis itself is crucial for the end result of every probabilistic attribution study. Especially for rapid analysis, there has to be a fixed and accepted method that can be applied for different events. Various syntheses are therefore compared in order to determine the ones that are best suited for the region under consideration (mostly Germany and Mid-Europe) and for different event classes.

This poster will focus on the recent developments and possible synthesis options for the probabilistic extreme weather event definition.

How to cite: Schröter, J., Tivig, M., Lorenz, P., and Kreienkamp, F.: Attribution of extreme weather events in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17854, https://doi.org/10.5194/egusphere-egu24-17854, 2024.

EGU24-18512 | ECS | Orals | CL3.1.3

Exploring drivers of evapotranspiration in CMIP6: A Multivariate Perspective 

Marius Egli, Sebastian Sippel, Vincent Humphrey, and Reto Knutti

To detect, quantify and attribute the effects of climate change in the context of rising carbon emissions, analyses often pinpoint individual variables. The aim is to find a signal of the externally forced response amidst internal climate variability. This becomes more challenging when examining regional shifts or variables with high internal variability like evapotranspiration, which in addition is affected by observational and modeling uncertainty. However, the interconnection of climate variables provides an advantage in considering them together, allowing us to explore how their relationships evolve over time and a better understanding of the underlying drivers.

Here, we investigate the combined effects of energy and water availability on evapotranspiration in climate models. Using a simple linear model, we quantify the contributions of these variables, which vary regionally. Water availability is more important in dry regions, whereas in wetter regions energy is the more dominant constraint on evapotranspiration. Moreover, we also find regions in which water availability dominates inter-annual variability, while evapotranspiration trends are better predicted by energy availability. This suggests that different causal factors may drive variations in the short and long term, which bears implications for the interpretation and potential constraint of projected future trends. In such a case, a signal of climate change is much more easily detected in a multi variate space, as the signal emerges in a direction where there is little internal variability. Finally, this approach provides insights into the complex influences shaping evapotranspiration and opens the door to possible constraints on future changes.

How to cite: Egli, M., Sippel, S., Humphrey, V., and Knutti, R.: Exploring drivers of evapotranspiration in CMIP6: A Multivariate Perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18512, https://doi.org/10.5194/egusphere-egu24-18512, 2024.

EGU24-18953 | Orals | CL3.1.3

Disentangling the forced and unforced components of observed surface air temperature trends 

Hasi Aru, Chao Li, and Dirk Olonscheck

Global mean surface air temperature stands is a critical indicator for gauging climate change, both on contemporary and over centennial scales. Previous studies on surface air temperature (SAT) variations tend to emphasize the uncertainties in model-simulated global warming projections, instead of differentiating the observed SAT trend patterns. Our study aims to partition observed SAT trends into forced and unforced components on decadal to multidecadal scales. Utilizing historical simulations from the ensemble mean of six large ensemble models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we develop a regression model specifically designed to robustly detect and attribute trends in the observed SAT. We evaluate the models' capability to replicate the detected forced SAT trends. Our findings indicate that external forcings are a significant driver of  SAT trend patterns on multidecadal scales, with pronounced warmingtrends over the Eurasian and North American continents. Conversely, on decadal scales, the forced SAT trends are not as evident within the observational data. Our results also underscore the limitations of current state-of-the-art climate models in capturing decadal trend variability. Interestingly, when comparing high- to low-sensitivity climates—those with high (ECS > 4.5K) versus low (ECS < 4.5K) equilibrium climate sensitivity—we find the high-sensitivity models to underrepresent the unforced signals of observed SAT trends. By leveraging significant observational data that captures the forced trend patterns on multidecadal timescales, we could enhance and constrain the future projection of SAT trends and variability more effectively.

How to cite: Aru, H., Li, C., and Olonscheck, D.: Disentangling the forced and unforced components of observed surface air temperature trends, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18953, https://doi.org/10.5194/egusphere-egu24-18953, 2024.

EGU24-19145 | Orals | CL3.1.3

Attributing child undernutrition from agricultural shocks to climate change in Burkina Faso 

Asya Dimitrova, Rahel Laudien, Anna Dimitrova, Sabine Undorf, and Jillian Waid

Climate change significantly threatens food security, particularly in low-income countries heavily reliant on subsistence and rainfed agriculture. Most existing empirical literature has examined the impacts of climate variability and extremes on undernutrition and agricultural outputs independently. There is a lack of studies exploring the causal pathway from climate change to agricultural shocks and their consequent nutritional and health impacts.

In this study, we investigate the extent to which the current and historical burden of child stunting in Burkina Faso can be attributed to climate change-induced agricultural deficits. First, we combine individual anthropometric data from five rounds of the Demographic Health Survey (DHS) and provincial-level crop yield data to assess the association between child stunting and exposure to agricultural deficits at birth. We define agricultural deficits as annual deviations in crop yields from their long-term average for three major food crops in the region: maize, millet, and sorghum. Second, we employ observationally-derived climate reanalysis data as well as counterfactual and factual climate data from ATTRICI (four pairs of datasets based on different reanalysis data), part of ISIMIP3a. These are analysed with a statistical crop yield modelling approach to estimate crop yields with and without climate change, respectively.

The epidemiological analysis reveals a non-linear health risk function, with risk of child stunting increasing rapidly when crop yields at birth are lower than the period average (<100%). The crop yield modelling shows a clear climate signal in annual variation in crop yields. The comparison between the factual and counterfactual climate data show a signal, especially in temperature. The outputs of the two models and the counterfactual/factual datasets are combined in an attribution framework in order to estimate the number of stunted children at the province level that can be attributed to climate change-induced agricultural deficits for the period 1984-2022. Repeating the analysis with factual and counterfactual CMIP6-DAMIP data to attribute explicitly the anthropogenic climate change is also considered. The study thus complements the climate impact attribution literature by a regional case study of so-far not attributed health aspects of crucial societal and economic importance.

How to cite: Dimitrova, A., Laudien, R., Dimitrova, A., Undorf, S., and Waid, J.: Attributing child undernutrition from agricultural shocks to climate change in Burkina Faso, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19145, https://doi.org/10.5194/egusphere-egu24-19145, 2024.

Historical archives and climate model simulations show that there can be multi-century periods with no local extreme precipitation, referred to as disaster gaps, followed by intense temporal clusters of extreme precipitation. The irregular occurrence of extreme precipitation represents a major challenge for detection and attribution of climate signals, adaptation planning and for insurance pricing. Here we use the first large ensemble of a convection permitting model (including twelve 100-yr simulations) and multi-century GCM simulations to study the irregular occurrence of local precipitation extremes.

We show that local extreme precipitation events occur highly irregularly, with potential clustering (11% probability of five or more 100-year events in 250 years) or long disaster gaps with no events (8% probability for no 100-year events in 250 years). Even for decadal precipitation records, there is almost a 50% chance of a complete absence of any tail events in a 70-year period, the typical length of observational or reanalysis data. This generally causes return levels – a key metric for infrastructure codes or insurance pricing – to be underestimated.

We then explore whether the occurrence of extreme events is purely random (“white noise”) or induced by low-frequency modes of internal variability, such as the multi-decadal variability in the North Atlantic. Surprisingly, we find based on millennial climate simulations that long-term variability in extreme precipitation is largely random, with no clear indication of low-frequency decadal to multidecadal variability.

We also evaluate the potential of employing information across neighbouring locations, which substantially improves the estimation of return levels by increasing the robustness against potential adverse effects of long-term internal variability. The irregular occurrence of events makes it challenging to estimate return periods for planning and for extreme event attribution.

How to cite: Fischer, E. and Zeder, J.: Multi-century disaster gaps followed by strong clusters of extreme precipitation – understanding the irregular occurrence of local heavy rainfall, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19934, https://doi.org/10.5194/egusphere-egu24-19934, 2024.

EGU24-20081 | Orals | CL3.1.3

Towards an operational forecast-based attribution system - beyond isolated events 

Nicholas Leach, Shirin Ermis, Olivia Vashti Ayim, Sarah Sparrow, Fraser Lott, Linjing Zhou, Pandora Hope, Dann Mitchell, Antje Weisheimer, and Myles Allen

Interest in the question of how anthropogenic climate change is affecting extreme weather has grown considerably over the past few years - and 2023 has been no exception. This increase in interest has brought a need for robust approaches that are able to quantitatively answer this question rapidly after an event occurs. However, conventional attribution frameworks using statistical or dynamical climate models have been challenged by several recent events that lay well beyond the historical record.

While such events have proven difficult to attribute using conventional methodologies, many were surprisingly well forecast by high-resolution numerical weather prediction systems. These systems generally lie at the state-of-the-art in the spectrum of earth system modelling, and their deficiencies are well documented and understood. We suggest that they therefore represent an opportunity for answering attribution — and other weather and climate risk-related — questions, based on models that are demonstrably able to simulate the often non-linear physics of the extremes that we are most interested in. This can increase the confidence in any attributable changes assessed since such changes can be explained in terms of the underlying physical processes. Further, as attribution science extends beyond purely physical assessments and into socioeconomic impacts, this opportunity will grow: weather models are already widely used by risk and emergency management professionals as inputs to hazard models. A final advantage of basing attribution statements on weather forecast models is that it is not only apparent when a forecast model can be used — but also when the model has a crucial deficiency as indicated by a forecast bust. In this case it would be clear that making a quantitative attribution statement would not be appropriate.

We have previously used a global high-resolution and coupled ensemble prediction system to quantify human influence on the Pacific Northwest Heatwave and Storm Eunice. Here, we move from event-centric to pseudo-operational experiments. We present a season of perturbed forecasts for attribution, initialised twice per week during the 2022-23 winter in both pre-industrial and future climates, using the same operational ECMWF model as before. A number of high-impact extreme events took place during this winter, and we will present preliminary results from some of these.

We suggest that this large set of simulations may be of interest to a wide range of users both inside and outside the attribution community, and we therefore aim to make them publicly available. In addition, we are keen to overcome the limitation imposed by our use of a single model within these experiments, and therefore invite other weather forecasting groups to run comparable experiments.

How to cite: Leach, N., Ermis, S., Vashti Ayim, O., Sparrow, S., Lott, F., Zhou, L., Hope, P., Mitchell, D., Weisheimer, A., and Allen, M.: Towards an operational forecast-based attribution system - beyond isolated events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20081, https://doi.org/10.5194/egusphere-egu24-20081, 2024.

EGU24-20885 | ECS | Posters on site | CL3.1.3

Evaluation of Extreme Weather Events: Using ECMWF's Reforecast Data 

Olivia Vashti Ayim

The frequency and intensity of extreme weather events, like heat waves, are increasing significantly due to climate change. These events have different effects on various socio-economic sectors worldwide, which directly affect people’s lives. This study aims to quantify how quickly the probability of these severe events changes and use this information to predict short-term extreme events. By integrating this measure into socio-economic predictive models, we can better understand the potential impact of climate change on different regions and populations, allowing for the development of more effective adaptation strategies. This study used ECMWF’s Reforecast data to statistically analyze the probabilities of extreme temperatures in the Pacific Northwest region and the time taken in decades for local temperatures to change, which will result in a doubling of these risks. The findings indicate an increasing probability of extreme temperatures with every unit increment in Global Land Surface Temperature Anomaly in more than 80 per cent of the region. Moreso, with the current rate of global warming (~0.32K/decade) the estimated time that the local temperature changes will result in a doubled risk of such extreme temperatures is averaging 0.2 of a decade over the PNW region. 

How to cite: Ayim, O. V.: Evaluation of Extreme Weather Events: Using ECMWF's Reforecast Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20885, https://doi.org/10.5194/egusphere-egu24-20885, 2024.

Global warming could surpass the 1.5 oC temperature target within a decade and even inevitably exceed 2 oC in this century, if fossil fuel emissions are not abated sufficiently and artificial interventions are not implemented. Even a temporary overshoot beyond 2 oC potentially disrupts the global carbon cycle, with the risk of irreversible and devastating changes to current terrestrial carbon sinks, such as the tropical forests and the northern high-latitude permafrost. Large-scale geoengineering is proposed as an adjunct to the conventional mitigation to partially counteract anthropogenic warming, and avoid dramatic alterations in the Earth system and the hazardous consequences. However, carbon dioxide removal and solar radiation modification differ in their role in interacting with the terrestrial carbon cycle, through directly interfering with the carbon cycle and indirect perturbation by changing the energy balance. The varied regional responses also affect the capacity of global carbon uptake, which further impacts on the efficacy of geoengineering. It's prudent to investigate the responses of the global terrestrial carbon balance in such context, i.e., the delayed consideration of solar radiation modification or carbon dioxide removal on top of various possible overshoot scenarios, to bring the global temperature back to and maintain the long-term targets.

How to cite: Chen, Y. and Ji, D.: Terrestrial carbon cycle response to solar radiation modification and carbon dioxide removal under potential temperature overshoots , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-613, https://doi.org/10.5194/egusphere-egu24-613, 2024.

EGU24-918 | ECS | Orals | CL3.1.6

Potential Impact of Stratospheric Aerosol Injection on Horticulture Suitability in Africa? 

Temitope Samuel Egbebiyi, Chris Lennard, Kwesi Quagraine, Romaric C. Odoulami, Izidine Pinto, Babatunde J. Abiodun, Piotr Wolski, and Simone Tilmes

Global warming will be devastating for agriculture in Africa, with consequent impacts on horticultural crop suitability. Horticultural crops are the main source of vitamins and antioxidants into our body and provide nutritional security. Stratospheric Aerosol Injection (SAI), which involves the injection of sulfur into the stratosphere to reduce incoming solar radiation to the earth surface, has been proposed as a strategy to reduce global warming rate, however, how this may affect horticultural crops, mango, orange and tomato, in Africa is still unknown. Our study examines the impact of climate change (GHG) and SAI on crop suitability and planting season in Africa. We used datasets from the Stratospheric Aerosol Geoengineering Large Ensembles (GLENS) project for the periods 2011-2030 and 2070-2089 as inputs into Ecocrop model to investigate GHG and SAI impacts on horticultural crops suitability in Africa. Our findings show GHG may lead to an increase of 3-4oC in both minimum and mean temperature and a 5-10mm increase in total monthly rainfall in West, Central and East Africa but a decrease (10mm) in southern Africa. SAI intervention results in cooling over Africa of up to 3oC in both minimum and mean temperature and may also lead to a decrease, 10-20mm in total monthly rainfall over the region by the end of century. The intervention may lead to an increase (~0.2) in Suitability Index Value (SIV) of mango and tomato over West and central Africa. However, a projected decrease (~0.3) in SIV is expected for mango and orange from Angola extending to northern Mozambique in southern Africa. In addition, no change in SIV is expected for the three crops in North Africa. SAI intervention may lead to 2-5% increase in suitable area for mango and tomato but a decrease (2%) for orange. The study provides information for decision-makers about choice of adaptation strategies to enhance regional economies and promote healthy nutrition in Africa.

Plain Abstract

Africa's agriculture will suffer greatly from global warming and affect horticulture crops. Our bodies get the majority of their vitamins and antioxidants from horticultural crops, which also offer nutritional security. Although, the injection of sulphur into the stratosphere has been put forward as an option to reduce effect of global warming but how this might impact horticultural crops, tomatoes, oranges, and mangoes, grown in Africa is still unknown. To examine the effects of climate change (GHG) and SAI horticultural crops suitability in Africa, we utilised information from the Stratospheric Aerosol Geoengineering Large Ensembles (GLENS) project for the periods 2011–2030 and 2070–2089 as inputs into the Ecocrop model. Over West and Central Africa, the Suitability Index Value (SIV) of tomatoes and mangoes may rise (~0.2) because of the intervention while for mango and orange a decline (~0.3) in SIV is anticipated from Angola to northern Mozambique in southern Africa. Mango and tomato suitable areas may rise by 2-5% because of SAI intervention but decrease by 2% for orange. Decision-makers can use the study's insights to choose adaption methods that will boost African regional economies and encourage a healthy diet. 

How to cite: Egbebiyi, T. S., Lennard, C., Quagraine, K., Odoulami, R. C., Pinto, I., Abiodun, B. J., Wolski, P., and Tilmes, S.: Potential Impact of Stratospheric Aerosol Injection on Horticulture Suitability in Africa?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-918, https://doi.org/10.5194/egusphere-egu24-918, 2024.

The urgency to limit continued global mean temperature rise has prompted the emergence of methods of solar climate intervention (SCI) to cool the planet. Stratospheric aerosol injection (SAI) is a method of SCI that would cool the planet by injecting aerosols into the stratosphere to reflect a small amount of incoming solar radiation away from Earth. There is not yet a complete understanding of how the impacts and risks of SAI on human and natural systems compare to those of climate change alone. While there has been some work that has examined the potential impact of SAI on extreme weather events, none has thoroughly examined the potential impact of SAI on warm spells, defined as prolonged periods of anomalously warm temperature that may occur at any time of the year. Warm spells have detrimental impacts that are projected to worsen with continued climate warming including risks to human health, agriculture and ecosystems. Here, the impact of SAI on the frequency, magnitude, intensity, and duration of warm spells is investigated globally using the ARISE-SAI simulations. Specifically, future projections of warm spells under ARISE-SAI are compared to those under climate change alone following the moderate SSP2-4.5 emissions scenario.  The ARISE-SAI simulations indicate that increases in the frequency, magnitude, intensity and duration of warm spells could be limited if SAI were to be deployed, although there is significant regional variability. 

How to cite: Glade, I. and Hurrell, J.: Assessing the impact of stratospheric aerosol injection on warm spell characteristics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1689, https://doi.org/10.5194/egusphere-egu24-1689, 2024.

Model of stratospheric aerosol injection deployment scenarios have often assumed that a global sunscreen could be applied to the earth on relatively short notice, perhaps in response to a climate emergency.  This emergency response framing confuse the time scales associated with the commencement of such a program.  Once deployed, stratospheric aerosols could cool the earth quite quickly, but such a deployment would require aircraft and other infrastructure that does not currently exist.  Given the span required to develop and certify a novel aircraft program and thereafter to build a fleet numbering in the hundreds, scenario builders should assume a roughly two-decade interval between a funded launch decision and the attainment of a target level of cooling.

How to cite: Smith, W.: An assessment of the infrastructural and temporal barriers constraining a near-term implementation of a global stratospheric aerosol injection program, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2221, https://doi.org/10.5194/egusphere-egu24-2221, 2024.

EGU24-2611 | ECS | Posters on site | CL3.1.6

Modelling the Impact of Surfactants on Anthropogenic CO2 Transfer between the Ocean and Atmosphere 

Jianing Hu and Miguel Maqueda

During the industrial revolution, anthropogenic carbon dioxide (CO2) emissions have rapidly increased, raising worries about their impact on global climate change. The oceans are an important sink of anthropogenic CO2, taking in about 30% of emissions. Despite the important role of surfactants in reducing gas exchanges between the atmosphere and the ocean, their effect on oceanic intake of CO2 has received limited attention in ocean models. In this exploratory work, we examine the impact of a parameterization of surfactants on CO2 fluxes between the ocean and the atmosphere using the NEMO (Nucleus for European Modelling of the Ocean) ocean engine in the ORCA2-LIM-PISCES configuration. Understanding and quantifying the potential effect of surfactants on the ocean's absorption of anthropogenic CO2 is the main goal of our modelling. Using documented atmospheric CO2 concentrations from 1750 till present, we carried out three simulations of the intake of anthropogenic CO2 by the ocean, one in which the presence of surfactants was ignored and two in which different formulations of the impact of surfactants on air-sea gas exchange were used. According to the simulations, the impact of the presence of surfactant on net, basin-scale anthropogenic CO2 fluxes into the ocean is rather small, on the order of just a few percent. However, in regions where, in the model, the intake of anthropogenic CO2 is largest, such as the Southern Ocean and the Kuroshio and Gulf Stream region, the reduction in these fluxes can attain between 10% and 40%. On seasonal timescales, the global effect of surfactants is to slightly enhance the amplitude of the annual cycle of fluxes by between 10% and 15%. The presence of surfactants leads to a reduction in the total mass of anthropogenic dissolved inorganic carbon (DIC) in the global ocean by about 6% at the end of the integration. Regionally, the concentrations of anthropogenic DIC in the water column (mass of DIC per unit area) are up to 10% lower in the Southern Ocean and in the northern branch of the Kuroshio when surfactants are present.

How to cite: Hu, J. and Maqueda, M.: Modelling the Impact of Surfactants on Anthropogenic CO2 Transfer between the Ocean and Atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2611, https://doi.org/10.5194/egusphere-egu24-2611, 2024.

EGU24-4102 | ECS | Orals | CL3.1.6

Comparison of marine cloud brightening in large eddy simulations 

William McFarlane Smith

Modelling of marine cloud brightening (MCB), a form of solar radiation modification, has thus far proven challenging due to the incongruous nature of the scales required. The microphysics of the cloud droplets and aerosols can only be resolved at really small scales, but just as important are the large-scale impacts on circulation and radiation. Large eddy simulations (LES) seem best placed to deal with this problem; they can resolve circulation an turbulence, but also have small enough grid boxes that useful parametrisation of microphysics can be made. When coupled to parcel models their representation of microphysical processes can be improved even further, although at a computational cost. There have been multiple studies of MCB in LES so far, but with wide-ranging background conditions and experimental designs. This leads to varying results that are challenging to compare. The aim of this study is to directly compare the results of at least two LES models, MONC and DALES, for an MCB experiment. They will first be compared with a historic data set, before being configured to ran the MCB experiment. It is hoped that MONC can also be coupled to a parcel model to improve its representation of cloud microphysics.

How to cite: Smith, W. M.: Comparison of marine cloud brightening in large eddy simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4102, https://doi.org/10.5194/egusphere-egu24-4102, 2024.

EGU24-4114 | ECS | Posters on site | CL3.1.6

Sensitivities of Marine Cloud Brightening Studied with a Lagrangian Cloud Model 

Zachary Christopher Rowland, Fabian Hoffmann, Franziska Glassmeier, Isabelle Steinke, and Herman Russchenberg

Marine cloud brightening (MCB) is a proposed climate engineering technique in which shallow liquid clouds are deliberately seeded with aerosol particles to increase their albedo and lifetime. Development of accurate models is essential to assess the feasibility of MCB; however, this is complicated by the large number of interacting microphysical processes that occur during cloud formation and the many environmental parameters that influence them. To simulate these microphysical processes in the required detail, a Lagrangian cloud model has been coupled to a simple adiabatic parcel model for this study.

Using this modelling framework, a sensitivity analysis is performed to determine the susceptibility of MCB to the aerosol particle size distribution, meteorological conditions, and several cloud microphysical choices. Attention is paid to the effect of varying the number of giant cloud condensation nuclei (GCCN) in the aerosol distribution, as these are known to enhance precipitation, with potentially deleterious effects to MCB. The results of this analysis provide insight for understanding the susceptibility of cloud formation to environmental conditions and practical considerations for any possible future MCB implementation.

How to cite: Rowland, Z. C., Hoffmann, F., Glassmeier, F., Steinke, I., and Russchenberg, H.: Sensitivities of Marine Cloud Brightening Studied with a Lagrangian Cloud Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4114, https://doi.org/10.5194/egusphere-egu24-4114, 2024.

EGU24-4373 | Orals | CL3.1.6 | Highlight

Developing an African Climate Intervention Research Coalition 

Chris Lennard, Babatunde Abiodun, and Andy Parker

With the 1.5oC global warming target set to be breached in the next decade, and as the impacts of this warming across the world become more deleterious, Climate Intervention (CI) and in particular Solar Radiation Modification (SRM) will become the subject of global political discussion. While low latitude, developing countries have the most to gain or lose from CI and SRM, they are underrepresented in current discussions, however, decisions regarding development and implementation/rejection of SRM require that these countries be at the center of such conversations.

Preparing the African voice for this discussion is essential and requires a well-resourced and well-connected African research community that understands the regional impacts of global warming and how CI may mitigate or exacerbate these impacts. While there are many SRM research projects around Africa facilitated by the DEGREES Initiative, a coordinated CI research community does not yet exist.

Here we present results from a project that aims to transition the current loose research network into a well-structured CI and SRM research coalition, nurturing an expert SRM community in Africa over the next 5-10 years.

The main component of the project is a workshop that will bring together African CI and SRM researchers alongside representatives of the World Climate Research Programme, the Coordinated Regional Downscaling Experiment (CORDEX-Africa) and International African research institutions. The workshop will discuss how to build, grow, and sustain a coalition of African SRM researchers, considering its research and capacity-building activities, its initial composition, and its structure. The workshop will also develop an initial roadmap of activities for the coalition and consider potential funding sources to support it. Furthermore, we will explore using a research hub model as a vehicle through which the coalition, its activities and growth is supported.

The insights and outcomes from these discussions will be synthesized into a white paper outlining the goals and principles of the coalition, with concrete recommendations for next steps. Key messages of the white paper will be presented in this session.

The work is pioneering and entrepreneurial and we know of no other efforts like this. In fact, we believe this would be the first continental scale SRM research coalition in the world, let alone in the Global South.

How to cite: Lennard, C., Abiodun, B., and Parker, A.: Developing an African Climate Intervention Research Coalition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4373, https://doi.org/10.5194/egusphere-egu24-4373, 2024.

EGU24-6144 | Orals | CL3.1.6

Idealized modeling of uncooperative two-actor SRM deployment 

Olivier Boucher, Anni Määttänen, Thibaut Lurton, and François Ravetta

Potential SRM deployment scenarios are increasingly discussed in the literature and an effort to construct plausible scenarios is underway in the scientific community. Such deployment scenarios underpin the design of possible governance mechanisms of SRM. A wide range of possible scenarios can be envisaged, including unilateral deployment by one actor, uncooperative multi-actor deployment, global centralized deployment or a global moratorium. In order to inform the current dialogue on governance, we explore in this work the behavior of a system where two uncooperative actors deploy SRM. We rely on a simple four-box climate model that responds to stratospheric aerosol injection (SAI) in the northern and southern hemispheres, including the oceanic response. The stratospheric aerosol optical depth has been parameterized with impulse response functions fitted on IPSL-CM6A-LR runs with injections at different latitudes. We couple this model to a control module in order to investigate different controlled SRM deployment strategies, reflecting potential governance scenarios. The two actors inject varying amounts of aerosols in the stratosphere to reach their own climate target which is unknown by the other actor. The climate target can be a temperature target (change of the temperature with respect to the initial state) or a monsoon target (variability of the monsoon index). Depending on the objectives and the characteristics of the deployment strategies by the two actors, we construct several experiments that result in i) involuntary cooperation between the two actors, ii) conflicting behaviors, or ii) one actor taking advantage of the other (free riding). We have also constructed experiments mimicking political decision-making timescales and potential perceived failure of SRM, causing more or less random interruptions of the injections. Although the scenarios are highly idealized and do not represent a realistic implementation of SRM, they help to understand the potential, synergies, risks and challenges of a decentralized, uncooperative deployment of SRM. We will discuss how the analysis of this type of experiments can inform the discussion on potential SRM governance strategies. Our future plans include adding a parametrization of the sea level rise and of ocean acidification into the model to investigate the behavior of these parameters as a result of the different SRM deployment and governance strategies. The simple model could also be used for educational purposes, for example to inform and to train decision-makers on SRM climate intervention and its effects and consequences.

How to cite: Boucher, O., Määttänen, A., Lurton, T., and Ravetta, F.: Idealized modeling of uncooperative two-actor SRM deployment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6144, https://doi.org/10.5194/egusphere-egu24-6144, 2024.

EGU24-6419 | ECS | Orals | CL3.1.6

Africa's Climate Response to Marine Cloud Brightening 

Romaric C. Odoulami, Haruki Hirasawa, Kouakou Kouadio, Trisha D. Patel, Kwesi A. Quagraine, Izidine Pinto, Temitope S. Egbebiyi, Babatunde J. Abiodun, Christopher Lennard, and Mark G. New

Climate intervention through solar radiation modification is one proposed method for reducing climate risks from anthropogenic warming. Marine Cloud Brightening (MCB), one such approach, proposes to inject sea salt aerosol into a regional marine boundary layer to increase marine clouds' reflectivity. This study assessed the potential influence of four MCB experiments on the climate in Africa using simulations from the Community Earth System Model (CESM2) with the Community Atmospheric Model (CAM6). Four idealised MCB experiments were performed with the CESM2(CAM6) model under a medium-range background forcing scenario (SSP2-4.5) by setting cloud droplet number concentrations to 600 cm-3 over three subtropical ocean regions: (a) Northeast Pacific (MCBNEP); (b) Southeast Pacific (MCBSEP); (c) Southeast Atlantic (MCBSEA); and (d) the combination of these three regions (MCBALL). The CESM2(CAM6) model reproduces the observed spatial distribution and seasonal cycle of precipitation and minimum and maximum temperatures over Africa and its climatic zones well. The results suggest that MCBSEP would induce the strongest global cooling effect and thus could be the most effective in decreasing (increasing) temperatures (precipitation) and associated extremes across most parts of the continent, especially over West Africa, in the future (2035-2054) while other regions could remain warmer or dryer compared to the historical climate (1995-2014). While the projected changes under MCBALL are similar to those of MCBSEP, MCBNEP and MCBSEA could result in more warming and, in some regions of Africa, create a warmer future than under SSP2-4.5. Also, all MCB experiments are more effective in cooling maximum temperature and related extremes than minimum temperature and related extremes. These findings further suggest that the climate impacts of MCB in Africa are highly sensitive to the deployment region.

How to cite: Odoulami, R. C., Hirasawa, H., Kouadio, K., Patel, T. D., Quagraine, K. A., Pinto, I., Egbebiyi, T. S., Abiodun, B. J., Lennard, C., and New, M. G.: Africa's Climate Response to Marine Cloud Brightening, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6419, https://doi.org/10.5194/egusphere-egu24-6419, 2024.

EGU24-7071 | Orals | CL3.1.6

Multi-model simulation of solar geoengineering indicates avoidable destabilization of the West Antarctic ice sheet 

John Moore, Yangxin Chen, Chao Yue, Svetlana Jevrejeva, Dan Visioni, Petteri Uotilla, and Liyun Zhao

Heat transported in Circumpolar Deep Water is driving the break-up of ice shelves in the Amundsen Sea sector of Antarctica, that has been simulated to be unavoidable under all plausible greenhouse gas scenarios. However, climate intervention scenarios have not been considered. Solar geoengineering changes global thermal radiative balance, and atmospheric and oceanic transportation pathways. We simulate stratospheric aerosol injection (SAI) designed to reduce global mean temperatures from those under the unmitigated SSP5-8.5 scenario to those under the SSP2-4.5 scenario with six CMIP6-class Earth System Models. These consistently show intensified Antarctic polar vortex and sub-polar westerlies, which mitigates changes to easterly winds along the Amundsen Sea continental shelf compared with greenhouse gas scenarios. The models show significantly cooler Amundsen Sea waters and lower heat content at 300-600 m under SAI than with either solar dimming or the SSP5-8.5 unmitigated greenhouse gas scenarios. However, the heat content increases under all scenarios compared with present day suggesting that although vulnerable ice shelves would continue to thin, the rate would be lower for SAI even with SSP5-8.5 specified greenhouse gases, than for the moderate (SSP2-4.5) scenario. The simulations here use climate interventions designed for global temperature targets; interventions targeted at preserving the frozen high latitudes have also been proposed that might be expected to produce bigger local effects, but potentially deleterious impacts elsewhere. Considering the huge disruptions to society of ice sheet collapse, more research on avoiding them by intervention technology is a moral imperative. 

How to cite: Moore, J., Chen, Y., Yue, C., Jevrejeva, S., Visioni, D., Uotilla, P., and Zhao, L.: Multi-model simulation of solar geoengineering indicates avoidable destabilization of the West Antarctic ice sheet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7071, https://doi.org/10.5194/egusphere-egu24-7071, 2024.

EGU24-7258 | ECS | Orals | CL3.1.6

Exploring the impacts of changes in solar radiation on ecohydrological variables 

Yiran Wang, Naika Meili, and Simone Fatichi

Several geoengineering projects are designed to modify solar radiation to limit global warming. These changes in solar radiation can have impacts on ecohydrological systems which are poorly quantified. In this study, CMIP6 outputs were used to calculate sensitivities of global and local near-surface meteorological variables to solar radiation changes. These sensitivities were applied to the currently observed climate to perturb meteorological variables in response to changes in solar radiation. These new conditions were used as inputs to a mechanistic ecohydrological model (T&C) to analyze the partitioning and changes in energy and water fluxes and the response of vegetation productivity in different biomes and climates. Specifically, we run two simulation scenarios to understand the solar radiation impacts on ecohydrological systems. The first scenario focuses only on changes in solar radiation, while the second scenario considers the combined effects of solar radiation changes and its climate feedback. The results show that, in the absence of climate feedback, changes in solar radiation are mainly reflected in changes in sensible heat, with less impact on the hydrological cycle, and vegetation productivity is positively and linearly correlated with changes in solar radiation. When climate feedback is included, the effects on latent heat and hydrologic variables are more pronounced, and the response of vegetation productivity to negative and positive solar radiation changes tend to be asymmetric. These results provide a basis for how land-surface processes could respond to regional brightening and dimming and future solar geoengineering programs.

How to cite: Wang, Y., Meili, N., and Fatichi, S.: Exploring the impacts of changes in solar radiation on ecohydrological variables, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7258, https://doi.org/10.5194/egusphere-egu24-7258, 2024.

EGU24-8269 | ECS | Orals | CL3.1.6

 Evaluation of Some Atmospheric Transmittance Indices Over Nigeria 

Oluwatosin Obasi-oma, Israel Emmanuel, Olushola Ojo, and Babatunde Adeyemi

Atmospheric transmittance, encompassing parameters such as the clearness index, cloudiness index, and transmitting index, plays a pivotal role in the transfer of electromagnetic energy in the atmosphere. This research aimed to enhance our understanding of solar energy availability by investigating these transmittance indices across specific locations in Nigeria's diverse climatic zones. By analyzing satellite hourly data from MERRA-2 spanning ten years, the diurnal and spatial distribution patterns of solar radiation parameters and transmittance indices were examined. The research identified distinct patterns in the radiation parameters and transmittance indices. In the morning hours, radiation parameters exhibited an increasing trend from coastal to inland locations, while the afternoon period showed a reverse pattern for diffuse solar radiation. Clearness and transmitting coefficient demonstrated consistent increases from the coast inland during both morning and afternoon hours, whereas the cloudiness index displayed an opposite pattern. Moreover, the transmittance indices showed a gradual reduction from west to east during the evening. Coastal regions experienced average annual values of 100W/m2 for diffuse solar radiation, 1443W/m2 for direct solar radiation, and 500W/m2 for global solar radiation, while Sahelian regions recorded 104W/m2, 2081W/m2, and 678W/m2, respectively. The clearness index ranged from 0.35 to 0.54, the cloudiness index ranged from 0.15 to 0.46, and the transmitting coefficient ranged from 0.19 to 0.45 across the studied locations. The observed distribution patterns provide valuable insights into solar energy availability within Nigeria's climatic zones. The contrasting patterns between morning and afternoon periods suggest variations in atmospheric conditions. Importantly, the study emphasizes the significance of the transmitting coefficient in characterizing atmospheric transmittance and its role in defining radiation transfer variables. In conclusion, this research contributes to existing knowledge by evaluating atmospheric transmittance indices and their distribution patterns in specific locations across Nigeria. The findings underscore the importance of considering the transmitting coefficient alongside other parameters to accurately assess solar energy availability. Understanding these indices and their variations is essential for the effective utilization and management of solar energy resources.

How to cite: Obasi-oma, O., Emmanuel, I., Ojo, O., and Adeyemi, B.:  Evaluation of Some Atmospheric Transmittance Indices Over Nigeria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8269, https://doi.org/10.5194/egusphere-egu24-8269, 2024.

In this study, we present a series of systematic AIDA cloud chamber experiments investigating the cloud microphysics governing cirrus cloud thinning effectiveness (i.e., the competition between heterogeneous and homogeneous ice nucleation) at temperatures below 230 K. Parcel model simulations based on our experimental studies show that the total ice crystal concentrations are very sensitive to the complex interplay between background aerosol, seeding and updraft velocities. We find regimes of successful cirrus thinning, as well as regimes resulting in thicker cirrus (overseeding). In addition, we also find that updraft fluctuations potentially play a critical role in influencing cirrus cloud thinning effectiveness.

How to cite: Steinke, I., Schorr, T., and Leisner, T.: Using cloud chamber experiments and numerical simulations to investigate the complexities of cirrus cloud thinning effectiveness, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9732, https://doi.org/10.5194/egusphere-egu24-9732, 2024.

EGU24-10285 | ECS | Orals | CL3.1.6

Assessing GFDL-ESM4.1 Climate Responses to CESM2-WACCM6 Geoengineering Forcing for 2.0°C Warming Target 

Shipeng Zhang, Vaishali Naik, David Paynter, Simone Tilmes, and Jasmin John

In this work we apply GFDL Earth System Model (GFDL-ESM4.1) to explore the climate responses to a geoengineering scenario that aims to restrict global warming to 2.0°C above pre-industrial levels (1850–1900) under the CMIP6 overshoot scenario (SSP534-OS) . Simulations of this geoengineering scenario with the CESM Whole Atmosphere Community Climate Model (CESM2-WACCM6) showed nearly unchanged interhemispheric and pole-to-Equator surface temperature gradients relative to present-day conditions around 2020, and reduced global impacts, such as heatwaves, sea ice melting, and large shifts in precipitation patterns (Tilmes et al 2020). Here we implement the identical stratospheric forcing in the GFDL-ESM4.1 model and find excessive global surface cooling and reduced precipitation responses, compared to those projected in CESM2-WACCM. Notably, the Southern Hemisphere experiences more substantial cooling compared to the Northern Hemisphere, accompanied by a north-ward shift in the Intertropical Convergence Zone (ITCZ). These distinct climate responses between GFDL-ESM4.1 and CESM2-WACCM6 can be traced back to their different climate feedback parameters. Furthermore, our analysis reveals that spatially heterogeneous forcing within the geoengineering scenario results in diverse climate feedback parameters even just in one model, through varying surface warming and cooling patterns. This research highlights the importance of considering model structure uncertainties and spatial forcing patterns for a comprehensive evaluation of future scenarios and geoengineering strategies.

How to cite: Zhang, S., Naik, V., Paynter, D., Tilmes, S., and John, J.: Assessing GFDL-ESM4.1 Climate Responses to CESM2-WACCM6 Geoengineering Forcing for 2.0°C Warming Target, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10285, https://doi.org/10.5194/egusphere-egu24-10285, 2024.

EGU24-12943 | Orals | CL3.1.6

Links between boreal forest and clouds inferred from long-term atmospheric observations 

Ekaterina Ezhova, Aino Aarne, Antti Arola, Antti Liponen, Anna Lintunen, Taina Yli-Juuti, Jaana Bäck, Harri Kokkola, Veli-Matti Kerminen, Tuukka Petäjä, Annele Virtanen, and Markku Kulmala

Clouds play a vital role in the Earth's radiation budget, with low-level clouds having a net cooling effect. Evidence shows that forests alter low-level clouds' formation and physical properties (e.g., [1-3]). In their turn, clouds modify radiation transfer, influencing near-surface variables and forest carbon uptake. Shallow cumulus clouds can enhance photosynthesis due to the diffuse fertilization effect, and the relative increase in photosynthesis is most significant in boreal forests compared to other ecosystems [4]. All this evidence suggests a strong atmosphere-biosphere link for boreal forests. 

We use long-term observations at SMEAR II station in Finland and satellite data sets to study how air mass transformation over boreal forests changes the optical properties of low-level clouds. Further, we assess the dynamics of photosynthesis and net ecosystem exchange in response to changing cloud properties and near-surface variables under different low-level clouds. We show that stratus clouds dampen photosynthesis, and the effect is amplified with the time spent by an air mass over a forest. Oppositely, cumulus clouds enhance photosynthesis compared to the clear sky conditions. If an air mass is exposed to the boreal forest for several days, and cumulus clouds form during the daytime, photosynthesis is efficient, and clouds' transmittance somewhat decreases. Our results suggest that shallow cumulus clouds formed in an air mass interacting with boreal forest can become more reflective. At the same time, these clouds provide ideal conditions for enhanced boreal forest carbon uptake.

References

[1] Teuling, A. J., Taylor, C. M., Meirink, J. F., Melsen, L. A., Miralles, D. G., van Heerwaarden, C. C., Vautard, R., Stegehuis, A. I., Nabuurs, G.-J., and de Arellano, J. V.-G.: Observational evidence for cloud cover enhancement over western European forests, Nat. Commun., 8, 14065, 2017. 

[2] Yli-Juuti, T., Mielonen, T., Heikkinen, L., Arola, A., Ehn, M., Isokääntä, S., Keskinen, H.-M., Kulmala, M., Laakso, A., Lipponen, A., Luoma, K., Mikkonen, S., Nieminen, T., Paasonen, P., Petäjä, T., Romakkaniemi, S., Tonttila, J., Kokkola, H., and Virtanen, A.: Significance of the organic aerosol driven climate feedback in the boreal area, Nat. Commun., 12, 5637,  2021. 

[3] Petäjä, T., Tabakova, K., Manninen, A., Ezhova, E., O'Connor, E., Moisseev, D., Sinclair, V. A., Backman, J., Levula, J., Luoma, K., Virkkula, A., Paramonov, M., Räty, M., Äijälä, M., Heikkinen, L., Ehn, M., Sipilä, M., Yli-Juuti, T., Virtanen, A., Ritsche, M., Hickmon, N., Pulik, G., Rosenfeld, D., Worsnop, D. R., Bäck, J., Kulmala, M., and Kerminen, V.-M.: Influence of biogenic emissions from boreal forests on aerosol–cloud interactions, Nat. Geosci., 15, 42–47,  2022. 

[4] Zhou, H., Yue, X., Lei, Y., Zhang, T., Tian, C., Ma, Y., & Cao, Y.: Responses of gross primary productivity to diffuse radiation at global FLUXNET sites. Atmospheric Environment, 244, 117905, 2021.

How to cite: Ezhova, E., Aarne, A., Arola, A., Liponen, A., Lintunen, A., Yli-Juuti, T., Bäck, J., Kokkola, H., Kerminen, V.-M., Petäjä, T., Virtanen, A., and Kulmala, M.: Links between boreal forest and clouds inferred from long-term atmospheric observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12943, https://doi.org/10.5194/egusphere-egu24-12943, 2024.

EGU24-15670 | Posters on site | CL3.1.6

Hydro-meteorological and Agricultural drought assessment under Solar Radiation Modification over the Niger river basin in West Africa 

Amadou Coulibaly, Abdoulaye Ballo, Komlavi Akpoti, and Windmanagda Sawadogo and the Amadou Coulibaly1*

West African countries are vulnerable to the adverse impacts of climate extremes such as drought which are becoming more frequent and more intense over the past decades. However, drought characterization and its associated drivers are not well understood in the region. In this study, we will investigate the implication of Solar Radiation Modification (SRM) in Hydro-meteorological and Agricultural drought over the Niger River Basin, as well as their larger-scale atmospheric and ocean-atmosphere drivers. The impacts of SRM on these aspects of drought will be assessed using ARISE/GeoMIP Global Climate Model (GCM) data. The study will use three drought indices: Standardized Precipitation Evapotranspiration Index (SPEI) over each grid point for each dataset for 1 month, 3 months, 6 months and 12 months. Precipitation Concentration Index (PCI) employed as an indicator of rainfall concentration for annual and seasonal scales (wet and dry seasons). Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP) to measure the rainfall distribution and the peak rainfall date, based on the daily or monthly total precipitation. Standardized runoff index (SRI) and standardized soil moisture index (SSWI). The Soil and Water Assessment Tool (SWAT) will be used to assess the current and future water balance in the basin and to estimate the features of meteorological, hydrological and agricultural droughts. The model with be driven by a statistically downscaled of the SRM climate model data. In the Preliminary results, models reproduce the near normal drought for each type of drought over the basin. The ssp585 shows less dry condition in the far future over the basin. The model intervention reduces the gap and has serious implications for future management of droughts over the basins. This is an ongoing study. The results of this research will provide valuable insights to stakeholders in the region on the regional impacts of a global climate mitigation solution such as SRM on key socio-economic climate hazards. Details results from the study will be presented in oral at the workshop. The results will enable much better-informed contributions from African policymakers in the UNFCCC and other fora where the pros and cons of geoengineering of climate in general, and SRM in particular, are being debated.

How to cite: Coulibaly, A., Ballo, A., Akpoti, K., and Sawadogo, W. and the Amadou Coulibaly1*: Hydro-meteorological and Agricultural drought assessment under Solar Radiation Modification over the Niger river basin in West Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15670, https://doi.org/10.5194/egusphere-egu24-15670, 2024.

EGU24-15763 | ECS | Orals | CL3.1.6 | Highlight

Could planetary scale solar radiation management prevent a West Antarctic Ice Sheet collapse?  

Johannes Sutter, Thomas Frölicher, Anthony Jones, Christian Wirths, and Thomas Stocker

Solar radiation modification (SRM) is increasingly discussed as a tool to reduce or avert global warming and concomitantly the risk of ice-sheet collapse, as is considered possible for the West Antarctic Ice Sheet (WAIS). While there is a growing body of literature on the climate impacts of various hypothetical SRM employment schemes, the concomitant effects on ice sheet dynamics are much less studied let alone understood. We present the first study explicitly modelling the Antarctic Ice Sheet response to global SRM-interventions with a continental scale ice sheet model. Intuitively, the question whether a WAIS collapse can be prevented depends on a manifold of factors such as ice sheet sensitivity, timing and design of the SRM-intervention and underlying climate scenarios. Our study suggests that safeguarding the WAIS from long-term collapse would either require rapid decarbonization efforts or quasi-immediate SRM-interventions. Both cases are either politically unrealistic or imprudent considering the precautionary principle. We discuss the response of the Antarctic Ice Sheet under various climate and SRM scenarios and the associated uncertainties which need to be resolved to get a more conclusive understanding on the impact of SRM-geoengineering strategies on earth’s two remaining large ice sheets. 

How to cite: Sutter, J., Frölicher, T., Jones, A., Wirths, C., and Stocker, T.: Could planetary scale solar radiation management prevent a West Antarctic Ice Sheet collapse? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15763, https://doi.org/10.5194/egusphere-egu24-15763, 2024.

EGU24-15841 | ECS | Orals | CL3.1.6

Analysing the impact of solar radiation management on the terrestrial biosphere in CMIP6 models 

Isobel Parry, Paul Ritchie, and Peter Cox

Solar radiation management (SRM) has the potential to artificially cool the Earth by increasing the reflection of incoming sunlight. One commonly researched SRM strategy is stratospheric aerosol injection (SAI), which involves the injection of sulphate aerosols into the stratosphere that scatter incoming solar radiation, thus cooling the planet. There are large uncertainties in the potential impact that solar radiation management could have on the biosphere, and further work is required to improve our understanding of the risks associated with this form of climate intervention. This presentation examines the impact of SRM on vegetation carbon, net primary productivity, and land carbon. We take results from five 6th generation climate models (CMIP6) which ran experiments as part of the geoengineering model intercomparison project (GeoMIP) and compare them with a high emissions scenario (ssp585). The GeoMIP experiments aim to investigate the global effects of using stratospheric aerosol injections and directly decreasing solar irradiance to reduce global temperatures to a ‘middle of the road’ scenario (ssp245), but without reducing the high greenhouse gas concentrations. Compared to ssp585, we find that ssp585 plus SRM tends to increases global NPP and land carbon storage. The global patterns of change in vegetation carbon storage vary between the ESMs, but there is a widespread agreement that SRM would have a positive impact on carbon storage and NPP  in the Amazon rainforest.

How to cite: Parry, I., Ritchie, P., and Cox, P.: Analysing the impact of solar radiation management on the terrestrial biosphere in CMIP6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15841, https://doi.org/10.5194/egusphere-egu24-15841, 2024.

EGU24-18905 | Orals | CL3.1.6

Solid particle SAI with a fully coupled atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.0 

Timofei Sukhodolov, Sandro Vattioni, Fabrice Stefanetti, Iris Schuring, Jan Sedlacek, and Gabriel Chiodo

Solid particles, such as alumina, calcite, and diamond, have been proposed as an alternative material for the stratospheric aerosol injection (SAI) studies. The traditional SAI set-up based on sulphate aerosols was shown to have several limitations such as stratospheric heating, due to absorption of long wave radiation, or ozone depletion, due to chlorine activation at the particle surfaces. Solid particles are thought to potentially overcome these limitations by having better optical properties and/or larger chemical inertness. In our work, we use for the first time a fully coupled atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.0, which incorporates a solid particle emission scheme, to assess the SAI effects of the alumina, calcite, and diamond. For each solid particle type, we followed the GeoMIP protocols and performed G4 and G6 experiments, which are cooling efficiency calibration runs and the transient ensemble runs to bring decadal surface temperatures of the SSP5 scenario to the ones from the SSP2 scenario, respectively. For all considered SAI substances, we find that the resulting burden is close to the yearly emission quantity, suggesting an average lifetime of approximately one year. Diamond has the highest burden-per-emission ratio, suggesting a higher lifetime, which is explained by its small particle radius. Sulfur, alumina, and calcite provide very similar cooling per emission, while diamond has a cooling efficiency of about a factor of three higher. Diamond also has the lowest absorption in the long wave, which allows it to show the weakest heating of the lower stratosphere, no increase in the stratospheric water vapour, and smallest dynamical effects on ozone. In terms of surface climate artifacts, those species that show the weakest heating in the stratosphere (calcite and diamond) also show the least anomalies in atmospheric and oceanic circulation patterns compared to the SSP2 scenario. Information on the interaction between alumina, calcite and ozone-relevant chemical cycles is available, but has not been sufficient so far for implementing their ozone chemistry with high confidence in the results. Additional laboratory studies, thus, are required for further modelling research on this subject.

How to cite: Sukhodolov, T., Vattioni, S., Stefanetti, F., Schuring, I., Sedlacek, J., and Chiodo, G.: Solid particle SAI with a fully coupled atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.0, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18905, https://doi.org/10.5194/egusphere-egu24-18905, 2024.

A proposed method to aid in mitigating global climate change is stratospheric aerosol injection (SAI). Recent work on SAI has shown its ability to reverse some of the changes induced by global warming, if employed properly. Still, many uncertainties on the effects of SAI exist. It is unclear if we can reverse the same amount of change with delayed SAI at high resolution, to be defined as 0.25 degree atmosphere or finer. A method is introduced that produces the needed atmospheric forcing for the atmospheric model component, which has a lower model top than more generally used in SAI studies. This method is based on existing data from the Geoengineering Large Ensemble Project (GLENS), and allows us to run high-resolution experiments. In this study, we further investigate atmospheric circulation changes using the Community Earth System Model (CESM), with a focus on Antarctica.

How to cite: de Jong, J.: Atmospheric circulation changes due to delayed stratospheric aerosol injection in high-res CESM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19933, https://doi.org/10.5194/egusphere-egu24-19933, 2024.

EGU24-20697 | Orals | CL3.1.6

Diffuse radiation characterized gross primary production over the globe 

Mingjie Shi and Tirthankar Chakraborty

Diffuse radiation, which is modulated by cloud and aerosol conditions, can have varied impacts on gross primary production (GPP), with the specific impacts depending on vegetation density, environmental conditions, and the specific physiological characteristics of plants. To quantify the sensitivity of GPP variation to changes in diffuse radiation at the global scale, we use several reanalysis datasets and a satellite-derived products with distinct characterizations of the division between direct beam and diffuse radiation, to force the Energy Exascale Earth System Model Land Model (herein ELM). We find large variations in the range of GPP due to the change in ratio of diffuse radiation to the total downward shortwave radiation (or diffuse fraction). The research implies substantial control of diffuse radiation on atmosphere–biosphere interaction, and demonstrates the importance of thoroughly and systematically validating the simulated diffuse radiation by atmosphere modules, along with assessing the ecosystem responses to the diffuse radiation variations within global land models.

How to cite: Shi, M. and Chakraborty, T.: Diffuse radiation characterized gross primary production over the globe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20697, https://doi.org/10.5194/egusphere-egu24-20697, 2024.

EGU24-20960 | Orals | CL3.1.6

Tropical Cyclone-related Extreme Rainfall and Its Impact under Solar Radiation Management (SRM) in Eastern Indonesia Region  

Sorja Koesuma, Akhmad Faqih, Hendri Hendri, Jassica Listyarini, Adinda Madi Astiani, Delfina Azzahra Kusuma, and Rahmat Gernowo

The provinces of East Nusa Tenggara (NTT) and Papua are located in the eastern part of Indonesia. The occurrence of tropical cyclones and extreme weather events has recently increased in both regions. It is necessary to be aware of the impact, both direct and indirect, of tropical cyclones, which affect the weather, especially extreme rainfall. The study aims to investigate the impact of extreme rainfall and find potential solutions.

We use some of the following tropical cyclone data that happened in Indonesia. The tropical cyclone of Seroja on April 4, 2021, reached mainland NTT and had a significant impact, especially on Timor Island and Sumba Island. The tropical cyclone of Surigae was formed in the northern region of Papua on April 12-19, 2021. The peak of this cyclone was on 16 April 2021. The tropical cyclone of Ray formed around the Northwest/Western Pacific Ocean on December 13-20, 2021.

We analysed the atmospheric dynamics (rainfall) of the tropical cyclone events using the ERA5 model. We also use Bias correction from GeoMIP to analyse the rainfall and compare both results. The result shows that both data are well correlated and tend to decrease.

How to cite: Koesuma, S., Faqih, A., Hendri, H., Listyarini, J., Madi Astiani, A., Azzahra Kusuma, D., and Gernowo, R.: Tropical Cyclone-related Extreme Rainfall and Its Impact under Solar Radiation Management (SRM) in Eastern Indonesia Region , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20960, https://doi.org/10.5194/egusphere-egu24-20960, 2024.

EGU24-1858 | Posters on site | OS2.5

Quantifying adaptation strategies: The gate index approach to extreme sea level scenarios in the western Baltic Sea 

Jian Su, Birte-Marie Ehlers, Jacob Woge Nielsen, Kristine Skovgaard Madsen, Morten Andreas Dahl Larsen, and Frank Janssen

Sea level rise is a significant threat to coastal regions, requiring thorough scientific evaluations to implement effective adaptation planning. Recent incidents of damages to ships and infrastructure in harbours during storm surge events in the western Baltic Sea have highlighted the urgent need for robust adaptation strategies to sea level rise. This study utilizes regional climate simulations, employing five members of the EURO-CORDEX ensembles, to investigate sea level rise scenarios under the RCP4.5 and RCP8.5 scenarios. Using the concept of "gate index", the study quantitatively assesses the frequency and duration of potential closures of storm surge gates in harbours in response to extreme sea level rise events. The results show significant spatial differences in vulnerabilities across the region, with increased risks under the RCP8.5 scenario. The analysis also emphasises substantial uncertainties, stemming from various factors such as variations in global climate models, complexities in ocean-atmosphere interactions, potential changes in ice sheet dynamics, and uncertainties in future greenhouse gas emissions trajectories. In addition, regional factors such as local sedimentation processes, tectonic activities, and land-use changes can further amplify these uncertainties. The interplay of these multifaceted factors underscores the complex nature of projecting sea-level rise, highlighting the need for a cautious and adaptive approach in coastal planning and policy formulation. These findings provide critical insights for policymakers and practitioners engaged in coastal risk assessment and adaptation planning in the vulnerable Baltic Sea region.

How to cite: Su, J., Ehlers, B.-M., Nielsen, J. W., Madsen, K. S., Larsen, M. A. D., and Janssen, F.: Quantifying adaptation strategies: The gate index approach to extreme sea level scenarios in the western Baltic Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1858, https://doi.org/10.5194/egusphere-egu24-1858, 2024.

Coastal areas are more vulnerable due to the high extreme natural events and anthropogenic activates are destroying the environment. Food demand is gradually increasing because of the population pressure, while alternative planning like aquaculture land is increasing in some parts of the Saudi Arabia. Global sea level rise is also a triggering factor for shoreline change in the coastal environment with high soil salinity increase. Without any sustainable planning and management, those areas are gradually affected through shoreline shifting and soil salinity-related problems. Remote sensing is the most powerful tool to detect those earth’s surface changes through earth observational datasets. Landsat series datasets were applied for detecting shoreline shifting, aquaculture land identification, and soil salinity along with automatic water area detection using Google Earth Engine cloud computing platform from 1994 to 2023 near Alqalh area, Saudi Arabia. Decadal shoreline shifting observed like 4.48 km2 (1994-2002), 8.82 km2 (2002-2014), 6.61 km2 (2014-2023) and 9.24 km2 (1994-2023), while overall 43.47 km2 (1994-2023) of the area is accretion measured. In the initial periods (1994) aquaculture land did not exit in this area but in the recent time (2023) this area have 71.16 km2 (13.38%) of aquaculture land. Some geo-spatial indices also applied for soil salinity, vegetation and water body area where Vegetation Soil Salinity Index (VSSI) observed high salinity in the year of 2024 due to huge aquaculture land and shoreline shifting towards north-west, south and south-east position of the study area. This investigation outcomes may help local planners in developing novel adaptation strategies in order to protect the environmental degradation.  

Keywords: Coastal area water assessment; Shoreline shifting; Soil salinity; Aquaculture; Remote sensing.                                          

How to cite: Al-Suwaiyan, M. and Yaseen, Z. M.: Coastal area shoreline shifting detection and water salinity assessment based on remote sensing and google earth engine platform: Active aquacultural case study area in Saudi Arabia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2656, https://doi.org/10.5194/egusphere-egu24-2656, 2024.

EGU24-3340 | ECS | Orals | OS2.5

Seasonal to multiannual marine ecosystem prediction using a deep learning approach 

Ji-sook Park, Jong-yeon Park, Jeong-hwan Kim, and Yoo-geun Ham

Marine biogeochemistry governs the flux of climate-active gases at the ocean-atmosphere interface, influencing diverse climate feedbacks. Despite advances in Earth System Models (ESMs) for climate-ecosystem predictions, challenges persist in the initialization and validation with biogeochemical observation data. In this study, Convolutional Neural Network (CNN)-based models predict chlorophyll concentrations in a productive large coastal area. The model was trained and validated using Coupled Model Intercomparison Project Phase 6 (CMIP6) multi-model ensemble datasets and physical–biogeochemical reanalysis data from a data assimilative ESM run. Through sensitivity tests on the model structure and input data, the CNN-based model demonstrates physical interpretability consistent with previous studies. Our optimized model adeptly reproduces annual observational chlorophyll variations in coastal regions where dynamic models face challenges, demonstrating comparable prediction skill to dynamic models in seasonal prediction by capturing large-scale climate variabilities. These findings highlight the importance of combining dynamic models and deep learning approaches, offering the potential for more accurate and comprehensive predictions of marine ecosystems.

How to cite: Park, J., Park, J., Kim, J., and Ham, Y.: Seasonal to multiannual marine ecosystem prediction using a deep learning approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3340, https://doi.org/10.5194/egusphere-egu24-3340, 2024.

Investigations on the spatiotemporal variability of coastal sea level and its mechanisms are of great scientific and practical importance. Unlike deep-ocean sea level that can be measured by satellite altimetry, studies on the spatial variability of coastal sea level require measurements from tide gauges and their associated vertical leveling information. Also, the dynamical mechanisms controlling the temporal variability has long been a research hotspot of coastal ocean dynamics. Local winds on the shelf and coastal currents are well recognized to be important in driving coastal sea level variability, but how do open-ocean signals affect sea level at the coast is less known. In addition, coastal sea level reconstruction or prediction often relies on climate models or statistical models. From a new and more dynamic perspective, we recently propose a dynamic framework to quantitatively reconstruct sea level at the coast. This presentation will focus on our recent works on the spatiotemporal variability of coastal sea level, including its alongshore tilts, mechanisms and dynamic reconstruction, as well as the implications and outstanding issues for further research.

How to cite: Lin, H.: Coastal sea level variability: Geodetic measurements, driving factors & dynamic reconstruction., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3419, https://doi.org/10.5194/egusphere-egu24-3419, 2024.

The need to understand and forecast disasters driven by anthropogenic and natural forces in the Gulf of Mexico and to support management responses to hazardous events led policymakers, scientists, and industry representatives in Mexico to launch an ocean observation and modeling project (2015–2023) aimed at collecting multi-layered baseline information and continuous monitoring of the ocean environment across the southern Gulf of Mexico. We will show the observational network and modeling efforts, led by the Research Consortium for the Gulf of Mexico (CIGoM), include developing a marine hazard warning system to investigate the multiple stressors that are altering the state and health of this large marine ecosystem and its coastal communities. This warning system is intended to aid in establishing of national contingency plans and mitigate the impacts of extreme events and long-term ocean trends. Stressors include hydrocarbon spills, tropical cyclones, marine heatwaves, long-term ocean surface warming, and harmful algal blooms. In this talk we will present part of our work related to the early warning system we have developed involving satelita detection, forecasting models and impact assessments of some oil spills that have occurred in the past few months in this region.

How to cite: Herguera, J. C. and the CIGOM: Ocean Monitoring and Prediction Network for the Sustainable Development of the Gulf of Mexico, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4170, https://doi.org/10.5194/egusphere-egu24-4170, 2024.

EGU24-4995 | Posters on site | OS2.5

The Ieodo Ocean Research Station (Ieodo-ORS) and Research Endeavors by the Korea Hydrographic and Oceanographic Agency (KHOA) 

Kwang-Young Jeong, Gwangho Seo, Seok Jae Kwon, Hyun-Sik Ham, and Hyun-Ju Oh

Constructed in June 2003, "The Ieodo Ocean Research Station (Ieodo-ORS)," a steel-framed tower-type platform, is strategically positioned near a submarine rock named Ieodo. Its primary objective is to advance our understanding of oceanic and atmospheric phenomena and their intricate interactions in the East China Sea. This station attains global significance owing to its distinctive open-sea location, situated approximately 149 km away from Jeju Island. Initially established by KIOST as part of the Research and Development project of the Ministry of Oceans and Fisheries, control of the Ieodo-ORS was transferred to the KHOA in 2007. Outfitted with 29 instruments for collecting oceanographic, meteorological, and environmental data, the Ieodo-ORS functions as a central hub for diverse projects initiated by the KHOA. These projects are geared towards refining observation techniques, optimizing the utilization of observational data, and systematically monitoring oceanic and atmospheric environments. Since 2014, the KHOA has executed the 'Ieodo-ORS Field Research Trip' program, providing support for a dedicated ship to service the Ieodo-ORS and leverage its facilities. The ultimate objective of the KHOA is to establish the Ieodo-ORS as a globally recognized scientific station through a comprehensive array of academic research initiatives.

How to cite: Jeong, K.-Y., Seo, G., Kwon, S. J., Ham, H.-S., and Oh, H.-J.: The Ieodo Ocean Research Station (Ieodo-ORS) and Research Endeavors by the Korea Hydrographic and Oceanographic Agency (KHOA), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4995, https://doi.org/10.5194/egusphere-egu24-4995, 2024.

EGU24-6248 | Orals | OS2.5

A new UK scale ocean-wave-river modelling system for predicting extreme sea levels at the coast  

Michela De Dominicis, Lucy Bricheno, Ryan Patmore, Toby Marthews, Segolene Berthou, and Laurent Amoudry

Extreme coastal sea level events are driven by various mechanisms, spanning a wide range of time scales. The long-term decadal and seasonal variability of mean sea level is combined at the coast with the seasonal variability of freshwater discharges, the daily scale of weather-related wave and surge events, and the semidiurnal to diurnal scale of astronomical tidal oscillations. Currently, future extreme sea levels are calculated as a combination of individually modelled sea surface height associated with storm surges and waves, tide and sea level rise, with number of limitations, e.g. the interaction between sea level rise and extreme sea surface height associated with storm surges, waves and tides is not taken into account. Progress in the modelling of the coupled coastal processes is urgently needed to predict how sea level rise will influence extreme sea level change at the coast and to ensure that design criteria for coastal protection are correctly specified, and hazard warning systems picks up potential disasters.

To reproduce the non-linear interactions between mean sea level, storm surge, tides and waves, we are developing an innovative high-resolution (500m) UK scale coastal ocean model based on the NEMO and WaveWatchIII systems (NEMO-WWIII UK500). This new configuration will include intertidal areas and processes (wetting and drying scheme); tides-surge-waves and sea level rise interactions; fully vertically resolved physics to include wave-current interactions and river plume dynamics; near-shore wave processes (wave set-up and run-up); sea level rise impact on tidal range/phase. NEMO-WWIII UK500 will provide predictions of water levels and waves conditions for present (fully validated by contemporary observations) and future scenarios.

The NEMO-WWIII UK500 will also provide a downstream boundary condition to the hydrological model JULES. This will enable the quantification of the effects of ocean water levels on rivers (backwater effect), which is important to lead to correct water levels in the transitional waters (e.g. estuaries and tidal rivers) which host a large proportion of infrastructure (e.g. ports, airports, power stations) and habitats of national and international significance.

How to cite: De Dominicis, M., Bricheno, L., Patmore, R., Marthews, T., Berthou, S., and Amoudry, L.: A new UK scale ocean-wave-river modelling system for predicting extreme sea levels at the coast , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6248, https://doi.org/10.5194/egusphere-egu24-6248, 2024.

EGU24-6367 | Posters on site | OS2.5

Projecting the impacts of climate change in the Atlantic Ocean: a global ocean downscaling approach 

Anna Katavouta, Jason Holt, Yuri Artioli, Giovanni Galli, James Harle, Lee de Mora, Sarah Wakelin, and Chris Wilson

The latest generation CMIP6-class Earth system models (ESMs) are a great tool for projecting climate variability on multi-centennial and global scales as they are designed to explicitly represent the process-coupling amongst the different Earth system components (atmosphere, ocean, land, cryosphere, biosphere) and prioritise system robustness such as minimisation of drift. However, CMIP6-ESMs do not accurately represent the fine-scale circulation and water-masses in ocean margins and shelf seas since by design: (i) their resolution is too coarse and so they only implicitly include regional-scale processes or even exclude these processes (particularly shelf-seas related processes); and (ii) their initialisation from a steady state leads to their divergence from reality and present-day conditions. To address these shortcomings and project the impacts of climate change in the Atlantic Ocean with focus on regional scales, we downscale globally an ensemble of future ocean projections with a NEMO-ERSEM coupled hydrodynamic-ecosystem model. Here, we discuss the design-methodology for our global ocean downscaling experiment: (i) selection of future scenarios, (ii) initialisation from “real” ocean conditions, (iii) selection of the CMIP6-ESMs atmospheric conditions to force our model based on their realism and uncertainty span, and (iv) treatment of the river runoffs as to impose both a realistic rivers state and a future trend consistent with CMIP6-ESMs. Comparisons of our global ocean downscaling simulations to CMIP6-ESMs during the historical period demonstrate their added value in terms of representation of physical ocean conditions and circulation in the Atlantic Ocean. We also present preliminary analysis in terms of future trends in temperature, salinity and circulation patterns in the Atlantic Ocean, with focus on regional features like changes in the Gulf Stream and trends in coastal regions.

How to cite: Katavouta, A., Holt, J., Artioli, Y., Galli, G., Harle, J., de Mora, L., Wakelin, S., and Wilson, C.: Projecting the impacts of climate change in the Atlantic Ocean: a global ocean downscaling approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6367, https://doi.org/10.5194/egusphere-egu24-6367, 2024.

EGU24-7012 | ECS | Posters virtual | OS2.5

Temporal trends and causes of deoxygenation: a comparison of the Northwest Atlantic Shelf and Atlantic Basin 

Hung Nguyen, Samantha Siedlecki, Enrique Curchitser, Charles Stock, Cesar Rocha, Zhuomin Chen, and Felipe Soares

Oxygen concentrations are of fundamental importance for organisms as well as geochemical cycling in oceans. Since the middle of the 20th century, oxygen concentrations have been declining in the open ocean and the coastal ocean. Located near the intersection of subtropical and subpolar circulation, the northwest Atlantic (NWA) Shelf is sensitive to climate variability. Recent work has been done on regional NWA trends in sea-surface temperature, salinity, and chlorophyll, but the trends and drivers of oxygen in the region have not yet been established. Here, we use World Ocean Database oxygen observations to determine the temporal trend of subsurface oxygen concentrations between 50-100m on the NWA Shelf from 1988 to 2019. We also use a regional NWA ROMS and MOM6 configuration to simulate the historical decadal trends and spatial patterns in dissolved oxygen concentrations over the shelf. Our results indicate a significant decrease of oxygen by 1.542±0.308 µmol/kg/year, which surpasses the established Atlantic basin-wide trend. The greatest subregional oxygen loss occurs on the Scotian Shelf and in the Gulf of St. Lawrence. A detailed analysis revealed that the oxygen trends on the NWA shelf are driven by changes in Apparent Oxygen Utilization (AOU), consistent with the decreased influence of Labrador Current in the region and associated water mass properties. Our model identifies the location of minimum oxygen concentrations occurring both at the bottom but also at midwater column depths in the Mid-Atlantic Bight and Gulf of Maine. Under SSP5-8.5, our dynamically downscaled projection (2014-2098) projects that the bottom oxygen in the NWA Shelf will accelerate relative to the historical period (1980-2014). Diagnosis of the mechanisms behind the future acceleration as well as the mid-water column minimum oxygen pattern using various tools will be presented.

How to cite: Nguyen, H., Siedlecki, S., Curchitser, E., Stock, C., Rocha, C., Chen, Z., and Soares, F.: Temporal trends and causes of deoxygenation: a comparison of the Northwest Atlantic Shelf and Atlantic Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7012, https://doi.org/10.5194/egusphere-egu24-7012, 2024.

EGU24-7495 | Orals | OS2.5

Transdisciplinary co-design to assess impacts of climate change on coastal schemes. 

Laurent Amoudry, Elina Apine, Sara Kaffashi, Constantinos Matsoukis, Marta Meschini, Marta Payo Payo, Amani Becker, Kenisha Garnett, Simon Jude, Claire Evans, Stephen Jay, Francisco Mir Calafat, Andy Plater, Leonie Robinson, Joanna Zawadzka, Jennifer Brown, Richard Dunning, Anil Graves, and Tim Stojanovic

Coastal hazards pose a significant risk to people, property, and infrastructure worldwide. They will be increasing over the next century mainly driven by sea level rise. Managing the coast in a sustainable way requires understanding the impacts under a changing climate of actions done and decisions taken now. This often relies on exploring the response of coastal systems to changing natural and/or anthropogenic drivers using modelling tools. The experimental design of such modelling work is essential in providing the robust scientific evidence needed to underpin effective coastal management. Yet, this experimental design often remains rooted within disciplinary silos and may not take a holistic view of the whole coupled human-environment coastal system. We will explore how considering whole coastal social-ecological systems and social acceptance can shape the experimental design of modelling coastal impacts under a changing climate, and lead to better scientific evidence.

We will present a new integrated, transdisciplinary system-based framework that brings together the provision of a conceptual representation of the complex coastal social-ecological system and consideration of key drivers in this, modelling coastal flooding and valuing ecosystem services now and into the future, and the influence of social perceptions and values. We will illustrate our approach with case studies across the United Kingdom. We will also discuss the benefits and challenges of following a transdisciplinary approach with respect to common coastal managements ambitions, such as improving coastal resilience, promoting a transition towards greener nature-based solutions, and following national and/or global net-zero and net gain objectives.

Our case studies span a range of coastal systems across three nations of the United Kingdom in order to provide examples of different policies and interventions as well as different environmental drivers. Our work builds on the outcomes of a  transdisciplinary capacity-building workshop, which highlighted the need for robustness, consistency, and communication when developing modelling scenarios. We use Fuzzy-Cognitive Mapping to elicit maps of generic coastal social-ecological systems. This is complemented by Soft System Modelling of coastal scheme decision making. We use questionnaire surveys and focus groups combined with Q-sort methodology to define and rank key factors in social acceptability of coastal schemes. Numerical modelling of coastal flooding relies on nested implementations of DELFT3D and SFINCS (Super-Fast INundation of CoastS) models for our case studies. Economic assessment and cost benefit analyses are grounded in the CICES framework and use GIS for habitat mapping to identify the extent and value of various habitats and assess potential flood losses. Overlaying social and flood maps for different scenarios ensures a thorough understanding of impacts, aiding informed decision-making. This approach integrates current habitat conditions with future change projections, essential for effective environmental management and policy planning.

Applying these methods for our case studies, and bringing them together via morphological analysis, our results show that Fuzzy-Cognitive Mapping, Soft System Modelling, Q-sort, and focus groups all provide valuable information and change the optimal output of the experimental design and selection of scenarios. The outcome is that the scientific evidence produced becomes more useful, useable, and trusted.

How to cite: Amoudry, L., Apine, E., Kaffashi, S., Matsoukis, C., Meschini, M., Payo Payo, M., Becker, A., Garnett, K., Jude, S., Evans, C., Jay, S., Mir Calafat, F., Plater, A., Robinson, L., Zawadzka, J., Brown, J., Dunning, R., Graves, A., and Stojanovic, T.: Transdisciplinary co-design to assess impacts of climate change on coastal schemes., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7495, https://doi.org/10.5194/egusphere-egu24-7495, 2024.

EGU24-8413 | ECS | Posters on site | OS2.5

Probabilistic Assessment of Exposure to Coastal Hazards at a Nuclear Power Station Development Site in the UK 

Zehua Zhong, Hachem Kassem, Ivan Haigh, Dafni Sifnioti, and Ben Gouldby

A fundamental requirement for the development of nuclear power stations is an evaluation of the risk and exposure to external hazards that may challenge nuclear safety. These hazards are often driven by a wide range of meteorological, oceanographic, and geomorphological processes which act on varying spatial and temporal scales. For coastal flooding and erosion, assessing the hazard potential requires consideration of both the local wave and water level variations and the associated regional weather conditions. Fortunately, the development of downscaling techniques offers useful tools for transferring large-scale climate forcings to local impacts. This research aims to conduct probabilistic assessments of coastal hazard exposure at a nuclear power station in the UK by using a hybrid downscaling framework. First, a weather typing method is employed to statistically downscale from regional atmospheric conditions to coastal waves and storm surges at the Hartlepool nuclear power station, which will be further downscaled to coastal flooding and erosion using physics-based dynamical models. We performed a sensitivity analysis to determine what parameters are significant in weather typing to downscale waves and storm surges. The resulting weather types and their associated wave climate and surge conditions are useful in identifying weather patterns related to extreme wave and surge events, which helps to reduce the computational effort in dynamical downscaling by focusing on those coastal-risk weather types and investigating their impacts. The sensitivity analysis reveals that the inclusion of the gradient of sea level pressure as the predictor and the use of local predictands to guide the classification of weather types are important to improve the model performance. 

How to cite: Zhong, Z., Kassem, H., Haigh, I., Sifnioti, D., and Gouldby, B.: Probabilistic Assessment of Exposure to Coastal Hazards at a Nuclear Power Station Development Site in the UK, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8413, https://doi.org/10.5194/egusphere-egu24-8413, 2024.

EGU24-8719 | Orals | OS2.5

Using on-demand prediction services to build user-tailored coastal Digital Twins 

Anabela Oliveira, Marta Rodrigues, Isa Elegbede, Gonçalo Jesus, André Fortunato, Ricardo Martins, and Alberto Azevedo

The concept of open forecast data has been gaining importance throughout the world, whether they address global, regional or local dynamics.  Most forecast systems in operation, however, just publish images, without providing quantified predictions that could be used to produce new services and have a greater societal impact. The initiatives under the UN Ocean Decade such as CoastPredict (https://www.coastpredict.org/) and DITTO (https://ditto-oceandecade.org/) programs aim at opening forecast information to all and address dynamics from the global to the coastal dimension.

Setting up model or forecast systems are complex tasks that require considerable expertise of coastal dynamics, numerical modeling and computer science. In the last few years, several initiatives have emerged to provide simplified ways to address this challenge and provide user-friendly tools to set up models and their forecast systems, with automatic linkage to global or regional forcings and access to data comparison in near real time. These on-demand forecast platforms aim at expanding the application of forecast systems worldwide, allowing for a broad implementation of decision support and emergency tools thus being an integral part of Digital Twins creation for coastal areas. Examples include SURF (Trotta et al., 2021), Delft-FEWS (Delft-Flood Early Warning System, Werner et al., 2013) and OPENCoastS (Oliveira et al., 2019, 2021).

Herein the OPENCoastS service and web platform are used to illustrate the creation of a core coastal Digital Twin for a data-poor region, using model outputs to compute relevant indicators for fisheries. The application site is the coast of Nigeria in Africa and CMEMs global data is used both to force the predictions and to evaluate its results through comparison with remote sensing products. Indicators suitable for fisheries sustainable operation are presented, developed in close collaboration with local players. This demonstration showcases the importance of on-demand forecast platforms and their role in the construction of Digital twins, facilitating the implementation of the UN Decade goals. The proposed methodology can be expanded in the future to other coastal regions in the scope of the UN Decade WOLLF project, supported by the human and computational resources provided by the ATTRACT European Digital Innovation Hub project.

References

Trotta, F., Federico, I., Pinardi, N., Coppini, G., Causio, S., Jansen, E., Iovino, D., Masina, S., 2021. A Relocatable Ocean Modeling Platform for Downscaling to Shelf-Coastal Areas to Support Disaster Risk Reduction. Front. Mar. Sci. 8, 642815. https://doi.org/10.3389/fmars.2021.642815.

Werner, M., Schellekens, J., Gijsbers, P., van Dijk, M., van den Akker, O., Heynert, K., 2013. The Delft-FEWS flow forecasting system. Environmental Modelling & Software 40, 65–77. https://doi.org/10.1016/j.envsoft.2012.07.010

Oliveira, A., A.B. Fortunato, M. Rodrigues, A. Azevedo, J. Rogeiro, S. Bernardo, L. Lavaud, X. Bertin, A. Nahon, G. Jesus, M. Rocha, P. Lopes, 2021. Forecasting contrasting coastal and estuarine hydrodynamics with OPENCoastS, Environmental Modelling & Software, Volume 143,105132, ISSN 1364-8152, https://doi.org/10.1016/j.envsoft.2021.105132.

Oliveira, A., A.B. Fortunato, J. Rogeiro, J. Teixeira, A. Azevedo, L. Lavaud, X. Bertin, J. Gomes, M. David, J. Pina, M. Rodrigues, P. Lopes, 2019. OPENCoastS: An open-access service for the automatic generation of coastal forecast systems, Environmental Modelling & Software, Volume 124, 104585, ISSN 1364-8152, https://doi.org/10.1016/j.envsoft.2019.104585

How to cite: Oliveira, A., Rodrigues, M., Elegbede, I., Jesus, G., Fortunato, A., Martins, R., and Azevedo, A.: Using on-demand prediction services to build user-tailored coastal Digital Twins, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8719, https://doi.org/10.5194/egusphere-egu24-8719, 2024.

EGU24-9126 | Orals | OS2.5

Climate Change Impacts on the Adriatic Sea: Integrating Sea State Indicators and River Release Dynamics 

Vladimir Santos da Costa, Giorgia Verri, Murat Gunduz, Alessandro De Lorenzis, Luca Furnari, Alfonso Senatore, Jacopo Alessandri, and Lorenzo Mentaschi

This comprehensive study, conducted within the AdriaClim project, offers a detailed exploration of the multifaceted impacts of climate change on the Adriatic Sea. We propose a limited area climate downscaling with mesoscale integrated modeling of the Adriatic water cycle, including the atmosphere, hydrology and marine thermo-hydrodynamics. The analysis covers the climate window between 1992 and 2050, under the high emission scenario RCP8.5 Examination of Sea Surface Temperature (SST) patterns, revealing a discernible warming trend, particularly along the continental slope influenced by the Western Adriatic Coastal Current. This regional warming has substantial implications for the delicate balance of the Adriatic Sea's ecosystems and underscores the need for targeted adaptive measures.

Marine Heatwaves (MHWs) exhibit both increased duration and intensity during the projection period. This emphasizes the imminent ecological and socio-economic repercussions, necessitating a proactive approach in policy formulations. The study delves into the intricacies of Brunt–Väisälä frequency analysis, unraveling alterations in ocean circulation and heat transport. This comprehensive understanding of regional climate impacts is crucial for informed decision-making in climate adaptation strategies.

Sea Level Rise (SLR) dynamics are explored in detail, showcasing nuanced spatial variations. A latitudinal decrease towards the northeast and heightened levels along the west coast are identified. The mid-term projection indicates a steric-driven increase in SLR, highlighting the importance of region-specific considerations and factors influencing sea level changes. These findings contribute significantly to the broader discourse on global sea-level rise and its regional variations.

A pivotal aspect of the study addresses the impact of projected changes in river release on local density stratification and SLR. Projections indicate a mid-term future decrease of approximately 35% in river release, affecting the Northern and Southern sub-basins differently. The Northern sub-basin will experience salinization prevailing on heating through the whole water column due to the projected runoff decrease, resulting in dense water formation increase and moderated sea level rise. Conversely,  the runoff decrease will have a lower impact in the Southern sub-basin where the future changes of other mechanisms may play a major role, making heating prevailing on salinization at intermediate to deep water column, resulting in lower dense water formation and higher SLR.

This integrated analysis underscores the intricate dynamics of regional climate impacts on the Adriatic Sea. The interplay of warming trends, altered ocean stratification, intensified MHWs, and river release dynamics demands a holistic approach to climate adaptation. Despite the significant strides made, the study acknowledges certain limitations, such as the absence of land subsidence models. The dynamic nature of the Adriatic Sea and the evolving landscape of climate change necessitate continuous monitoring and refinement of models for heightened accuracy in future projections.

The study serves as a testament to the importance of integrated research with a more comprehensive representation of the local water cycle at high time and space resolutions emphasizing the imperative of harmonizing scientific insights with pragmatic policy implementations.

How to cite: Santos da Costa, V., Verri, G., Gunduz, M., De Lorenzis, A., Furnari, L., Senatore, A., Alessandri, J., and Mentaschi, L.: Climate Change Impacts on the Adriatic Sea: Integrating Sea State Indicators and River Release Dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9126, https://doi.org/10.5194/egusphere-egu24-9126, 2024.

EGU24-10061 | Posters on site | OS2.5

Adaptation to climate change: Regional sea surface temperature scenarios for the North Sea and the Baltic Sea 

Birte-Marie Ehlers, Jian Su, and Frank Janssen

The German Strategy for Adaptation to Climate Change (Deutsche Anpassungsstrategie - DAS) is the political framework to climate change adaptation in Germany and laid the foundation to prepare for the impacts of climate change and reduce climate risks in a continuous process. The DAS core service “Climate and Water” provides monitoring and projection data to evaluate requirements for climate change adaptation.

An ensemble of regional climate ocean simulations is provided to tackle a large number of questions on the topics of sea level, water temperature, salinity and currents. The regional climate ocean simulation ensemble is based on atmospheric forcing from five members of the EURO-CORDEX ensemble. The simulations were calculated for a thirty-year ”historical” period (1971-2000), a thirty-year ”near future” period (2031-2060) and one for the ”far future” (2071-2100) for the RCP8.5 scenario.In this study, we focus on the evaluation of the sea surface temperature (SST), which has a major impact on the ecosystem and therefore must be part of the adaptation strategy. A comparison of all SST model results with observational data provides a bias correction of the individual ensemble members, which than is also applied to the projected data. The ensemble approach is examined with respect to substantial uncertainties and different types of ensemble representation are discussed. The results are prepared for policymakers and practitioners engaged in coastal risk assessment and adaptation planning and will be available on the internet at https://das.bsh.de.

How to cite: Ehlers, B.-M., Su, J., and Janssen, F.: Adaptation to climate change: Regional sea surface temperature scenarios for the North Sea and the Baltic Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10061, https://doi.org/10.5194/egusphere-egu24-10061, 2024.

EGU24-10202 | ECS | Posters on site | OS2.5

Critical decade for freshwater discharge into the Adriatic Sea 

Leonardo Aragão, Lorenzo Mentaschi, Giorgia Verri, Alfonso Senatore, and Nadia Pinardi

Located in the central Mediterranean Sea, the Adriatic Sea experiences complex water circulation patterns driven by saltwater inflow from the Ionian Sea through the Strait of Otranto and the outflow through the same strait but richly charged by fresh and dense waters formed in the northern Adriatic Sea. These circulation patterns place the unique hydrodynamics of the Adriatic Sea as the mainframe in shaping its diverse marine ecosystem, making it a primary region in dense water formation within the Mediterranean Sea. However, in recent decades, the region has continually recorded longer and more intense periods of drought. Some studies account for the loss of about 80 billion tons of freshwater during the 2021-2022 drought only at the Po River basin. To explore this matter further, the present work aims to analyse the last decade (2013-2022) of river discharges into the Adriatic Sea and frame the impacts of recent drought events in the current climatological period. To this end, the hydrological data reconstructed with the European Flood Awareness System (EFAS) were analysed for the period 1991-2022, quantifying river discharges separately in the four subregions of the Adriatic Sea: Shallow Northern Adriatic Sea (SNAd), Northern Adriatic Sea (NAd), Central Adriatic Sea (CAd), and Southern Adriatic Sea (SAd). Over the past 32 years, river discharges have shown different trends along the Adriatic Sea subregions, where a delicate balance between dry seasons in some subregions has been slightly balanced by flood seasons in others and vice versa. This delicate balance, combined with the diversity of its river basins, prevents us from estimating a trend with statistical significance for the Adriatic Sea. However, the river discharge trends are forthright when computed individually for each subregion, balancing slightly negative trends in the northern subregions (-0.6% and -1.0% per year in SNAd and NAd) with intriguingly positive trends in the southern subregions (+0.4% and +1.3% per year in CAd and SAd). When the analysis window narrows to the last decade (2013-2022), this balance breaks down, and a strong negative trend emerges across the entire Adriatic Sea, without exception, indicating reductions of -4.2% per year in freshwater input throughout the river basin. As suggested by the Standardised Flow Index (SFI) results, a climate indicator used to estimate the long-term impact of drought and flood periods on river discharges, 2022 was crucial for the last negative decadal trend. During this year, the northern Adriatic experienced the driest period in the last 32 years, while the southern Adriatic experienced river discharge reductions during flood months. Nevertheless, the most worrying element about the extreme drought of 2022 is that this year is part of a drought cycle that has continuously reduced freshwater availability in the Adriatic Sea every 4-5 years since 2008.

How to cite: Aragão, L., Mentaschi, L., Verri, G., Senatore, A., and Pinardi, N.: Critical decade for freshwater discharge into the Adriatic Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10202, https://doi.org/10.5194/egusphere-egu24-10202, 2024.

EGU24-11438 | ECS | Orals | OS2.5

Investigating the efficiency of nature-based solutions against estuarine coastal flooding under present and future conditions  

Constantinos Matsoukis, Marta Payo Payo, Elina Apine, Sara Kaffashi, Marta Meschini, Amani Becker, Kenisha Garnett, Simon Jude, Claire Evans, Stephen Jay, Francisco Mir Calafat, Andy Plater, Leonie Robinson, Joanna Zawadzka, Jennifer Brown, Richard Dunning, Anil Gaves, Tim Stojanovic, and Laurent Amoudry

Most coastal areas around the world are currently at risk of flooding, which is increasing due to sea level rise and other impacts of a changing climate. The design of appropriate flood protection policies and schemes is thus becoming more imperative. Partly in response to net zero and net gain agendas, coastal practitioners across sectors have started to champion ‘greener’ nature-based solutions in place of traditional hard coastal defences. However, social acceptance is limited, and examples worldwide are too scarce to fully test and demonstrate the efficiency and societal benefits of nature-based solutions. Appropriate case studies are required to build the knowledge and evidence base needed for the implementation of nature-based solutions.  

In this study, the efficiency of nature-based solutions (e.g., managed realignment) against flooding is investigated for an estuarine case study in Scotland. The Forth Estuary is one of UK’s most important estuarine ecosystems both for economic and ecological reasons. In recent years, flooding events have considerably affected urban areas and infrastructure along the estuary. The frequency and intensity of such events is expected to increase due to climate change and result in significant adverse impacts on local population and economy. Airth is a village situated in the south bank of the inner Forth Estuary. It is a residential area that covers 5500 hectares of agricultural land with some woodland as well. Part of it is designated as a conservation area because of its significant historical background. However, it is often subject to coastal and/or surface water flooding. The local authority has launched a management plan strategy for flooding mitigation seeking adaptation solutions. 

 A 2D numerical model has been built in Delft3D-FM to determine the hydrodynamic setup in the Forth estuary. The model encompasses a large area starting from the inland tidal limit and including both the inner and outer Forth estuary. It is forced upstream by river discharge and downstream by water level time series. To account for additional flood drivers such as wave set-up, run-up, and wind-driven surges, a second model is built in SFINCS with a finer resolution and with its extents locally restrained around the Airth coast. Modelling scenarios comprise at first a series of hindcast simulations performed to reproduce the impact of three recent storm events that largely affected the local community by causing extensive inundation and flooding of properties. The simulations are then repeated with bathymetry adaptations to represent interventions (i.e., managed realignment) into the model and compare their effect against flooding. In addition, simulations with future sea level scenarios are considered to assess these interventions efficiency under a changing climate. As events of similar or higher intensity can be expected in the future, model results can give a good indication of how the system responds when the nature-based defences are in place. These can assist, advise, and direct stakeholders and local authorities to consider alternative and state-of-the-art solutions in their fight against coastal flooding impact. 

How to cite: Matsoukis, C., Payo Payo, M., Apine, E., Kaffashi, S., Meschini, M., Becker, A., Garnett, K., Jude, S., Evans, C., Jay, S., Calafat, F. M., Plater, A., Robinson, L., Zawadzka, J., Brown, J., Dunning, R., Gaves, A., Stojanovic, T., and Amoudry, L.: Investigating the efficiency of nature-based solutions against estuarine coastal flooding under present and future conditions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11438, https://doi.org/10.5194/egusphere-egu24-11438, 2024.

EGU24-11959 | ECS | Orals | OS2.5

Future projections of a salt-wedge estuary under a changing climate: impact of the sea level rise and evaluationof a nature-based-solution 

Alessandro De Lorenzis, Giorgia Verri, Vladimir Santos Da Costa, Nadia Pinardi, Giovanni Coppini, Albert Sorolla, Adrian Löchner, and Eugènia Martí

Estuarine zones are particularly vulnerable coastal areas as consequence of the changing climate. The river flow decrease, RD, and the sea level rise, SLR, are leading to: (i) salinization of the surface and subsurface catchment waters, (ii) salt-wedge intrusion SWI moving more and more inland, with a non-linear response to the main drivers of the estuarine dynamics.

 The current study uses a one-dimensional two-layer estuary box model, the so-called CMCC EBM (Verri et al 2020; 2021) which solves the estuarine water exchange by means of two conservation equations for volume and salt fluxes averaged over the diurnal tidal cycle, plus two parametric equations estimating the SWI length and the along-estuary diffusivity.
  The EBM has been applied to the Po di Goro branch of the Po river delta, which is characterised by a river-dominated estuary flowing into the micro-tidal Northern Adriatic Sea. A strength of the EBM here proposed is the extremely low computational time which makes it particularly suitable for climate purposes by bridging the gap between available hydrology and marine hydrodynamics projections which reach at most the mesoscale with high computational costs and without representing the estuarine transitional areas. Additional assets are the minimal data storage and no need to postprocess the results as the SWI length is among the model outcomes. On the other hand, a proper tuning of the parametric equations is required and this was made possible by an accurate in-situ monitoring and a site specific “learning dataset” built upon the outcomes of a 3D unstructured modelling of the Po delta system.

  Considering that there are few studies devoted to the impacts of the local SLR on the SWI and the salinity of estuaries in micro-tidal environments, one of the aims of this study is to expand the knowledge on this topic by proving future projections for the selected test-case.  

  Moreover, the increasing salinization of the Po di Goro estuary threats the local economy and the ecosystem health. Thus, the second aim of this study is to evaluate a Nature-Based-Solution, NBS, to mitigate the SWI, i.e. we assess the salt uptake capability of the Atriplex portulacoides within our modelling study.

Three climate experiments with the EBM have been carried out over 1991-2100 with a ‘mechanistic’ approach: (i) Exp1 is a full-forcing experiment with the river inflow (volume flux at the estuary head) and the seawater inflow (volume flux, salinity and sea level at the estuary mouth) provided by a regional climate model RCM considering RCP 8.5; (ii) Exp2 is a twin experiment of Exp1 but neglecting the sea level among input forcings of the EBM; (iii) Exp3 is a twin experiment of Exp1 but with a reduced salinity of the seawater inflow by assuming that 20% of the estuary water volume interacts with the halophytes planted along the estuary banks.

We propose a discussion on the relative role of the SLR and the RD in determining the future projections of the Po di Goro estuarine dynamics and the potential effect of a site-specific NBS.

How to cite: De Lorenzis, A., Verri, G., Santos Da Costa, V., Pinardi, N., Coppini, G., Sorolla, A., Löchner, A., and Martí, E.: Future projections of a salt-wedge estuary under a changing climate: impact of the sea level rise and evaluationof a nature-based-solution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11959, https://doi.org/10.5194/egusphere-egu24-11959, 2024.

EGU24-12416 | ECS | Orals | OS2.5

Forecasting of atmospheric variables based on ECMWF analysis data using Machine Learning approaches 

Mahmud Hasan Ghani, Francesco Trotta, and Nadia Pinardi

Recent advancements within the arena of Artificial Intelligence have widened the potential applications of Machine Learning (ML) frameworks in climate prediction and weather forecasting. For any modern forecasting system, a core objective is linked with handling uncertainty and scientists are interested in the accuracy of the forecasts.  The time series forecast of air temperature using ML approaches is available in the literature. But for this study, we have selected major atmospheric variables- air temperature, dew point temperature, wind components and mean sea-level pressure (MSL-P) retrieved from the ECMWF analysis system and which are to be used in perturbation of the ocean forecasting system. In our previous approach, we analysed the probability distributions of the selected atmospheric variables. In this study, we intend to forecast those atmospheric variables using machine learning algorithms to compare with the analysis dataset produced by ECMWF. Under the initial approach, a Convolution Neural Network (CNN) approach is built to predict the time series for the atmospheric variables. The predicted results from the forecasts have shown minimal differences in comparison to the observations.  Based on the results produced from the CNN, we would like to apply other ML approaches to compare the accuracy and in the process of selecting a better ML model.  

How to cite: Ghani, M. H., Trotta, F., and Pinardi, N.: Forecasting of atmospheric variables based on ECMWF analysis data using Machine Learning approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12416, https://doi.org/10.5194/egusphere-egu24-12416, 2024.

EGU24-13192 | ECS | Posters on site | OS2.5

The new ICATMAR high-frequency radar network: data analysis and preliminary results on the Catalan Coast turbulence characterization. 

Lucía Quirós-Collazos, Justino Martínez, Lluc Segura-Lladó, Gerard Llorach-Tó, Joaquim Ballabrera-Poy, Concepción Bueno, Emilio García-Ladona, and Jordi Isern-Fontanet

Over the last year 2023, a new high-frequency (HF) radar network has been implemented along the Catalan Coast by the ICATMAR, a cooperative body between the Institute of Marine Sciences (ICM-CSIC) and the Catalan Government that aims to provide scientific advice for the maritime governance in this region. The network consists of 7 CODAR antennas, 5 of which are already operating and the rest will be commissioned before the end of 2024. These antennas provide surface radial velocities and waves measurements along the Catalan Coast, between the coastline and about 40 miles offshore. The radial velocity measurements obtained by two or more antennas are currently being combined using the (unweighted) least-squares fitting method to derive the total current velocity fields. Current data provided by the ICATMAR HF radar network has a spatial resolution of about 9 km2 and is delivered every hour.

The results presented here focus on the characterisation Probability Density Functions (PDFs), statistical moments and structure functions of radial velocities. Quality control standards of JERICO network (defined in JERICO-Next D5.13) have been applied on radial velocity data measured by two antennas (stations CREU and BEGU) over an almost 1-year time series since their installation in 2023. The analysis of the main four moments were performed on validated data in order to characterize the main statistical properties. The derived PDFs differ from a Gaussian distribution by showing heavy tails, characteristic of turbulent flows and ocean observations. Structure functions up to the 15th order were calculated along each radial direction and their scaling were derived, unveiling a spatial variation of the anomalous scaling of the structure functions.

These preliminary results highlight the HF radars value as a tool for sampling surface sub-mesoscale turbulence structures which, in turn, will help improve our understanding of the dynamical properties of ocean flows, specially, in near coastal marine regions where high resolution currents data is scarce.

How to cite: Quirós-Collazos, L., Martínez, J., Segura-Lladó, L., Llorach-Tó, G., Ballabrera-Poy, J., Bueno, C., García-Ladona, E., and Isern-Fontanet, J.: The new ICATMAR high-frequency radar network: data analysis and preliminary results on the Catalan Coast turbulence characterization., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13192, https://doi.org/10.5194/egusphere-egu24-13192, 2024.

The need for skillful seasonal prediction of coastal sea level anomalies has become increasingly evident as climate change has increased the risk of coastal flooding events. Aiming to improve our ability to forecast coastal inundation risk on seasonal and longer time scales, NOAA and NASA initiated the RISE project, a collaborative effort focused on developing and assessing novel dynamical and statistical forecast methods for coastal sea level and inundation risk for US coasts. This presentation is an outgrowth of that project, initially based on a pilot study of monthly sea level anomaly forecast skill assessed at two tide gauge stations, San Diego CA, and Charleston SC. In this study, we evaluate several current forecast systems -- NCAR Community Climate System Model Version 4 (CCSM4), GFDL Seamless System for Prediction and Earth System Research (SPEAR), and ECMWF Seasonal Forecast System 5 (SEAS5) -- by calculating deterministic and probabilistic skill from a few decades (1993-2015) of their retrospective forecasts (“hindcasts”) and for lead times of up to 6-9 months. Additionally, we examine potential local enhancement of hindcast skill by two post-processing downscaling techniques, an observationally-based multivariate linear regression and a hybrid dynamical model approach, using the adjoint model of the Estimating Circulation and Climate of the Ocean (ECCO) system forced by observed and model-predicted surface forcings.

We find that all these approaches face challenges stemming from whether the modeled sea surface height sufficiently represents observed local variations of coastal sea level, because of ocean model limitations and because of inadequacies in both model initialization and ensemble spread. Some of these issues also complicate the ability of the downscaling techniques to improve probabilistic skill, even though they do somewhat improve deterministic skill. In general, while deterministic hindcast skill is considerably higher for San Diego than Charleston, ensemble spread metrics such as forecast reliability and sharpness are mediocre for both locations. Additionally, evaluating how well any technique predicts seasonal coastal sea level variations is considerably complicated by the forced trend component and particularly how it is estimated, especially for Charleston; .essentially, skill assessment of US coastal sea level seasonal prediction is also a trend detection problem. Moreover, these results are largely matched by hindcasts from a Linear Inverse Model (LIM), a simple stochastically-forced linear prediction model constructed from observations, suggesting that substantial improvement still remains for coastal sea level prediction.

How to cite: Newman, M., Long, X., and Shin, S.-I.: Evaluating Current Statistical and Dynamical Forecast Techniques for Seasonal United States Coastal Sea Level Prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14252, https://doi.org/10.5194/egusphere-egu24-14252, 2024.

EGU24-14266 | Orals | OS2.5 | Highlight

Advancing Marine Sustainability through Digital Twin What-If Scenarios in Nature Based Solutions 

Joanna Staneva, Nadia Pinardi, Giovanni Coppini, Benjamin Jacob, Wei Chen, Philip-Neri Jayson-Quashigah, Jacopo Alessandri, Lorenzo Mentaschi, and Yann Drillet

Digitalization, particularly through the utilization of digital twins of the ocean, can play a significant role in advancing the sustainable development of the marine environment. The Digital Twin (DT) creates a digital replica of the ocean, enabling testing of various What-If scenarios, such as the impacts of sea level rise, Nature-Based Solutions (NBS), as well as the effectiveness of mitigation and adaptation plans. DTs provide insights into ocean conditions, ecosystems, and human effects, guiding decisions for sustainable resource use. DT-based What-If scenarios in NBS foster cooperation among stakeholders in shared oceanic spaces, enabling data-driven decisions and collaboration. This platform serves for decision-making and management strategies aimed at fostering the sustainable utilization of ocean resources. Such an application is a Digital Twin strategy in designed experiments for nature-based solutions.  It can be employed to evaluate the effects of sea level rise and wave actions on seagrass meadows; and evaluate different management approaches to enhance resilience, while assessing diverse management tactics for bolstering resilience. We demonstrate how Digital twins of the coastal ocean can contribute by aiding decision-making through the use of Whar-If scenarios for coastal protection against erosion and sediment transport by sea level rise, while also ensuring the preservation of coastal biodiversity. By monitoring and optimizing solutions through digital twins, effectiveness and long-term sustainability are heightened, necessitating collaborative efforts for coastline protection and ecosystem preservation.

To further support the coastal restoration (e.g. of seagrass meadows), digital twin technology can be utilized to monitor and model the climate (e.g. sea level rise) and human induced effects on coastal ecosystems. The collaborative efforts for nature based solution as coastline protection and ecosystem preservation are demonstrated in various coastal areas around the Global coast (e.g., in the North Atlantic, Wadden Sea coast, Danube-western Black Sea, Mediterranean coast, Eastern coast of Ghana) In the context of nature-based solutions, a digital twin help identifying areas where seagrass is most vulnerable to the impacts of sea level rise and evaluate different management strategies to promote resilience. In addition to seagrass restoration, other nature-based solutions can effectively address the impacts of sea level rise. These solutions include the restoration of wetlands, dunes, and mangroves, as well as the implementation of green infrastructure such as bioswales and green roofs. Coastal communities can play a critical role in implementing and supporting nature-based solutions. This includes engaging in community-based monitoring and restoration efforts, as well as advocating for policies that prioritize nature-based solutions for coastal protection. The integration of digital twin technology with community efforts can foster a collaborative and data-driven approach to sustainable coastal management and resilience.

How to cite: Staneva, J., Pinardi, N., Coppini, G., Jacob, B., Chen, W., Jayson-Quashigah, P.-N., Alessandri, J., Mentaschi, L., and Drillet, Y.: Advancing Marine Sustainability through Digital Twin What-If Scenarios in Nature Based Solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14266, https://doi.org/10.5194/egusphere-egu24-14266, 2024.

EGU24-16161 | ECS | Posters on site | OS2.5

Challenges and Strategies in the Development and Operation of High-Frequency Marine Radar Systems in Taiwan 

Huan Meng Chang, Jian Wu Lai, Hsin Yu Yu, Hwa Chien, and Jenq Chi Mau

    The pivotal role of oceanographic parameters in informed decision-making spans a spectrum of marine issues, including resource management, ecological preservation, maritime safety, and national security. Conventional data acquisition methods, such as buoys and survey ships, have become increasingly inadequate in addressing the complex demands of these domains. This insufficiency has propelled the global development of spatially-oriented observational technologies, among which High-Frequency (HF) ocean radar is a standout. Globally, the deployment of HF ocean radar systems has surpassed 1000 units. Taiwan, since the 1990s, has installed 48 HF radar systems, including variants like CODAR, WEAR, and LERA. Despite initial successes, a decline in system performance post-deployment is a recurring issue, often linked to policy discontinuity, fluctuating financial support, team dynamics, technical proficiency, and data application and dissemination challenges. This study explores Taiwan's unique experiences with these impediments in the evolution of HF ocean radar systems, aiming to strategize effective long-term operational planning.

    A case in point is the Taiwan Ocean Radar Observation System (TOROS), established by the Taiwan Ocean Research Institute (TORI) in 2016. This system confronted operational challenges due to insufficient maintenance budgets soon after its inauguration, leading to the cessation of some station operations. Further analysis identified a reactive data dissemination model, requiring user applications and approvals, as a primary issue. This inefficiency, compounded by inadequate promotion, weakened the system's perceived utility, resulting in unsustainable policy support, budget cuts, and the loss of specialized personnel, thereby adversely impacting system functionality in a cyclic manner.

    This paper argues that the ubiquity of data fosters demand, a critical metric for evaluating system utility. Such utility influences administrative decisions, which in turn affect financial commitment, vital for cultivating a skilled technical team. The strategic deployment of this workforce is crucial for consistent system operation and maintenance, ultimately determining operational success. Leveraging insights from past installations and operational experiences, the study proposes methodologies to sustain operational continuity and bolster the efficacy and resilience of HF ocean radar systems.

How to cite: Chang, H. M., Lai, J. W., Yu, H. Y., Chien, H., and Mau, J. C.: Challenges and Strategies in the Development and Operation of High-Frequency Marine Radar Systems in Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16161, https://doi.org/10.5194/egusphere-egu24-16161, 2024.

EGU24-16644 | Orals | OS2.5

Coastline migration and restoring recommendations in China  

Xuege Wang, Fengqin Yan, and Fenzhen Su

Coastal areas are important and functional regions due to their location and abundant natural resources that support human life and certain industries, while these areas are also ecologically vulnerable and have experienced dramatic changes due to both human activities and natural factors. In this article, remote sensing and geographic information system technology are utilized to extract and analyze the spatiotemporal changes in China’s coastline from 1980 to 2018. Additionally, the study introduces the Ecosystem Service Values (ESVs) evaluation method to quantitatively assess the impact of coastline changes on coastal ESVs. Results indicate that from 1980 to 2018, the length of China's mainland coastline increased by 10.2%, characterized by a significant increase in artificial and a sharp decrease in natural coastlines. Aquaculture ponds were the type of coastline with the most increase, followed by construction land and ports. Bedrock coastline was the type of coastline with the most reduction, followed by sandy and muddy coastlines. Over the past four decades, the changes in coastline have led to a decrease of $6.83 billion in ESV in China's coastal zone. Therefore, protecting and restoring China's natural coastline should be highly prioritized. Local authorities should evaluate the ecological environment of specific coastal zones in a timely and effective manner using big data and decision-making tools, and provide feedback to guide the adjustment and implementation of relevant national/regional policies.

How to cite: Wang, X., Yan, F., and Su, F.: Coastline migration and restoring recommendations in China , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16644, https://doi.org/10.5194/egusphere-egu24-16644, 2024.

EGU24-18780 | ECS | Orals | OS2.5

Multi-model statistical system for monitoring the dispersion of pollutants: Mediterranean case study 

Beatrice Maddalena Scotto, Antonio Novellino, Giovanni Besio, and Andrea Lira Loarca

INTRODUCTION

The Mediterranean Sea is facing escalating environmental threats due to increasing maritime activities, resulting in increased marine pollution. Effectively addressing these challenges necessitates an expanded focus on reliable monitoring services to predict and mitigate the impacts of pollution spills. This study aims to comprehensively understand the dynamics of oil spills in the Mediterranean region, with the objective of establishing a robust and user-friendly framework for an application. This application not only assesses historical oil spill events but also elucidates the intricate interplay of environmental factors, serving as a predictive tool for effective monitoring and planning.

METHODOLOGY

The study centers on determining the dispersion velocity of pollutants, accounting for three significant contributions influencing spill movement: surface velocity of currents, Stokes drift induced by waves, and wind influence within the initial 10 meters above the sea surface. These contributions are fine-tuned using coefficients, building on established methodologies. Data integration from three oceanic models—Copernicus Marine Environmental Monitoring Service (CMEMS), Naval Hydrographic and Oceanographic Service (SHOM), and the French Research Institute for the Exploitation of the Sea (IFREMER)—provides a nuanced analysis of surface current velocities, addressing uncertainties within the ensemble.

The dispersion simulation utilizes the OceanParcels Lagrangian Particle Tracking Model (PTM), tailored to specific events. The analysis includes the temporal and spatial evolution of oil slicks, determining particle release parameters, and evaluating centroids at each moment. Comparison with Synthetic Aperture Radar (SAR) satellite imagery refines model precision, offering real-world validation and aiding in model selection for accurate environmental protection decision-making.

RESULTS

Validation with a real-case scenario, a shipping accident off the coast of Corsica in October 2018, reveals distinctive trajectories among models (Figure1). Integrating wind and Stokes drift refines outputs, with notable alignment to observed events, showcasing enhanced predictive capabilities, especially during the detection of hydrocarbons in France on October 16th (Figure2).

Figure 1(left) – Models trajectory simulated with sea surface currents, showing the evolution of the centroid trajectory and particle distribution in space and time. On the right the color bar showing the values of the particles’ experimental distribution. Figure 2 (right) -Trajectories simulated with the contributions of sea surface currents, wind at 10m and stokes drift, showing the evolution of the centroid trajectory and particle distribution in space and time.

Graphical representations illustrate the spatio-temporal evolution of the particle cloud, providing comprehensive insights into oil spill movement.

CONCLUSIONS

Despite evident progress, persistent uncertainties in climate services pose challenges in predicting and mitigating oil spill impacts. Sustained investments in research and development for climate monitoring services are crucial for addressing uncertainties and ensuring the long-term sustainability of the Mediterranean ecosystem. The future lies in refining models, integrating high-resolution data, and advancing climate monitoring to enhance prediction accuracy and minimize environmental repercussions from pollutant spills in the Mediterranean basin.

How to cite: Scotto, B. M., Novellino, A., Besio, G., and Lira Loarca, A.: Multi-model statistical system for monitoring the dispersion of pollutants: Mediterranean case study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18780, https://doi.org/10.5194/egusphere-egu24-18780, 2024.

EGU24-19020 | Orals | OS2.5

The Baltic Sea Observatory – A new holistic approach to understand the coastal ocean 

Peter Holtermann, Jacob Geersen, Robert Mars, Sebastian Neubert, Miriam von Thenen, and Maren Voss

The Baltic Sea, a European semi-enclosed marginal sea, is driven by the estuarine circulation of dense, saline North-Sea water entering the Baltic Sea and mixing with the freshwater input due to rivers and precipitation. The mixed brackish water leaves the Baltic Sea at the surface through the Danish Belts and the Sound. These processes lead to a strong vertical stratification of the Baltic Sea water masses, the halocline. The slow water exchange causes a mean residence time of the water of 30 years, which leads an accumulation of nutrients. A major consequence of the long residence time and the halocline are low oxygen concentrations below the halocline, with virtually permanent anoxic conditions in the deep basins of the Baltic Sea. To what respect climate change, with the warming of the Baltic Sea as one effect, is impacting the Baltic Sea ecosystem is an open and very relevant research question. One potential consequence could be a further spreading of low or anoxic zones towards the coastal areas, which is already being observed. A less well understood part of the Baltic Sea are the shallow coastal zones, but recent research points to the direction of a strong relevance for e.g. the nutrient turnover. To develop a fundamental understanding of the relevant processes and their coupled effect on the biota, it is therefore essential to measure, monitor and predict the shallow water processes along the margins of the Baltic Sea and how they alter the state of the sea at a basin-wide scale.

To address these research questions, the IOW is establishing an interdisciplinary network of long-term and short-term observations in the coastal area of the southern Baltic Sea. This involves deploying moorings in shallow water that send their data to the institute in real time, where they are made immediately available to the general public. The essential ocean parameters (EOP) acquired will be used to control specialized sampling. A measurement program on biogeochemical nutrient turnover, sediment dynamics, geophysics, phytoplankton and zooplankton takes place regularly and is linked to physical data on current patterns, wave intensity and turbulence. The in-Situ measurements are combined with high-resolution numerical modeling to be able to extrapolate the field measurements and to develop numerical experiments.

Different stakeholders groups will be involved to provide society and authorities with the latest findings of the measurement campaigns.

How to cite: Holtermann, P., Geersen, J., Mars, R., Neubert, S., von Thenen, M., and Voss, M.: The Baltic Sea Observatory – A new holistic approach to understand the coastal ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19020, https://doi.org/10.5194/egusphere-egu24-19020, 2024.

EGU24-19023 | ECS | Orals | OS2.5

Projecting future sea-level change along the coast of the Netherlands with a regional ocean model 

Jeemijn Scheen, Dewi Le Bars, Iris J. Keizer, Tim H.J. Hermans, Sophie J.C. Tubbergen, Bert Wouters, Stef Lhermitte, and Aimée B.A. Slangen

Global mean sea level is rising due to anthropogenic climate change, via the thermal expansion of seawater and the mass loss of land ice. Regional sea-level change is also affected by changes in ocean currents due to the changing climate or internal climate variability. We use the Regional Ocean Modeling System (ROMS) to simulate future sterodynamic sea-level change – the combined contribution of thermal expansion and ocean dynamics – on the Northwestern European Shelf. Regional ocean models such as ROMS are suitable to simulate the exchange of deep ocean currents in the Atlantic with the Northwestern European shelf, and can improve the horizontal resolution from the order of 100 by 100 km (typical for global climate models) to the order of 10 by 10 km. The ROMS model is driven by CMIP6 (Coupled Model Intercomparison Project Phase 6) global climate model output at the domain boundaries, and uses dynamical downscaling to produce projections of sterodynamic sea-level change at a 12 by 12 km horizontal resolution with 30 terrain-following depth layers.

We present projections until 2100 based on 2 CMIP6 models and 5 emission scenarios, for Western Europe at this high resolution. Our results show the advantage of dynamical downscaling on projecting annual average sea level and how this differs between the chosen CMIP6 models and the different emission scenarios. In addition, we assess the linkage between regional sea level and freshwater input of European rivers, comparing simulations without river input, with realistic river input (based on observations) and with enhanced river input. This tests whether a potential future increase in river discharge is relevant to consider in projections of regional sea-level change.

How to cite: Scheen, J., Le Bars, D., Keizer, I. J., Hermans, T. H. J., Tubbergen, S. J. C., Wouters, B., Lhermitte, S., and Slangen, A. B. A.: Projecting future sea-level change along the coast of the Netherlands with a regional ocean model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19023, https://doi.org/10.5194/egusphere-egu24-19023, 2024.

EGU24-19232 | ECS | Orals | OS2.5

Oceanographic processes influence the high primary productivity in the Visayan Sea, Philippines   

Aiko Love del Rosario, Adonis Gallentes, Princess Hope Bilgera, and Cesar Villanoy

The mechanisms behind the high productivity of the Visayan Sea (Philippines) need to be understood for better fisheries management. However, current global ocean models are limited to spatial resolution of 1/8° to 1/12° which is around 8-14 km in grid size. Due to the presence of islands, shallow depths and narrow straits surrounding the Visayan Sea, global models cannot resolve and explain the Visayan Sea surface currents. In this paper, we explore the possible reasons for the high productivity in the region through analysis of satellite-derived chl-a and high resolution hydrodynamic models of the Visayan Sea in DELFT3D-Flow and SURF-NEMO.

Tide analysis suggests that the dominant constituents in the Visayan Sea are both semi-diurnal - M2 (principal lunar) and S2 (principal solar). In the larger Philippine Internal Seas which include the Visayan Sea, notably higher M2 and S2 amplitudes are observed in the latter. This can be attributed to the possible resonance of wave-wave interaction by tides coming from surrounding basins. Being a relatively shallow body of water (30-90 m) surrounded by deeper waters (100-1,700 m) and an area where maximum tidal amplitudes are found, stronger vertical mixing and nutrient exchange are ensued, thereby reinforcing productivity. 

Satellite-observed chlorophyll-a concentrations from 2002 to 2022 in the Visayan Sea and adjacent seas are consistently high, regardless of monsoon reversal. Empirical orthogonal function (EOF) analysis of chlorophyll data was also conducted to determine the dominant patterns of chl-a variance. The first 10 modes contribute 65.2 % of the total variance. Mode 1 (18.8 %) is attributed to the seasonal variability (i.e., monsoons). Mode 2 (11.1 %) pattern can be associated with the Nino3.4 ENSO Index, suggesting that primary productivity in the Visayan Sea could be well affected by the changing climate. 

Lastly, this study presents a recommendation of areas that need protection and focused management for better implementation of fishing seasonal closure in the Visayan Sea.

How to cite: del Rosario, A. L., Gallentes, A., Bilgera, P. H., and Villanoy, C.: Oceanographic processes influence the high primary productivity in the Visayan Sea, Philippines  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19232, https://doi.org/10.5194/egusphere-egu24-19232, 2024.

EGU24-19635 | Posters on site | OS2.5

Numerical Study on the Circulation in the Gulf of Thailand and Its Seasonal Water Exchange with the South China Sea 

Changshui Xia, Youting wu, Fangli Qiao, and Chalermrat Sangmanee

      Gulf of Thailand is a semi-closed shallow water basin connected to the South China Sea. The seasonal Circulation patterns in the Gulf of Thailand and its water exchange with the South China Sea are studied using the CROCO model from 2017 to 2020. The simulated temperature, salinity, Sea surface height and current field agree with the observation well.  Based on the model result, the upper flow velocity of the horizontal flow field in the Gulf of Thailand a is greater than the lower flow velocity, which means that the Ekman flow driven by the monsoon dominates the upper flow field. Winter and summer are the strongest periods of the monsoon in the sea area, as well as the strongest periods of water exchange between the Gulf of Thailand and the South China Sea. In winter, the upper layer of South China Sea water flows into the Gulf of Thailand, causing an increase in SSH, causing the middle layer of seawater to sink and flow out from the bottom; In summer, the upper layer of Gulf of Thailand water flows out, SSH decreases, the middle layer of seawater surges up to supplement the surface deficiency, and the bottom layer of South China Sea water flows in to compensate.  

Keywords: Gulf of Thailand, Circulation patterns, Gulf of Thailand, South China Sea

How to cite: Xia, C., wu, Y., Qiao, F., and Sangmanee, C.: Numerical Study on the Circulation in the Gulf of Thailand and Its Seasonal Water Exchange with the South China Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19635, https://doi.org/10.5194/egusphere-egu24-19635, 2024.

EGU24-19811 | ECS | Posters on site | OS2.5

Predicting massive floating macroalgal blooms in the regional sea 

Fucang Zhou, Zhi Chen, Dongyan Liu, Ruishan Chen, Changsheng Chen, Karline Soetaert, and Jianzhong Ge

Increasingly severe and massive floating macroalgal blooms pose significant challenges to the prediction and management of coastal and ocean environment. This study introduces the Floating Macroalgal Growth and Drift Model (FMGDM), a physical-ecological model that tracks, replicates, and extinguishes Lagrangian particles to dynamically simulate the growth and drift pattern of floating macroalgae. The model updates the position, velocity, quantity, and represented biomass of these particles synchronously within its tracking and ecological modules. The macroalgal ecodynamic processes are driven by the oceanic physical-biochemical environments of hydrodynamics, temperature, nutrients, and atmospheric conditions. With the support of the hydrodynamic model and biological macroalgae data, FMGDM can serve as a model tool to forecast floating macroalgal blooms. We developed a forecasting system for large-scale floating macroalgal blooms, which integrates the FMGDM with the Finite-Volume Community Ocean Model (FVCOM). This system is capable of predicting the physical-biogeochemical environment and macroalgal ecodynamic processes in the regional ocean. Biological parameters for this model were specifically derived from culture experiments of Ulva prolifera, a phytoplankton species causing the largest worldwide bloom of green tide in the Yellow Sea, China. With real-time multi-resource satellite data, the system successfully applied to predict green tide events in the Yellow Sea for 2021-2023. The prediction accuracy of coverage can reach 67.0%, and the minimum error of green tide center of mass is 7.39 nautical miles for total coverage of 52.01 km2 and prediction duration of 7 days. Supported by regional marine data and macroalgal physiological characteristics, this system can be expanded to other similar floating macroalgal blooms.

How to cite: Zhou, F., Chen, Z., Liu, D., Chen, R., Chen, C., Soetaert, K., and Ge, J.: Predicting massive floating macroalgal blooms in the regional sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19811, https://doi.org/10.5194/egusphere-egu24-19811, 2024.

EGU24-20826 | ECS | Posters on site | OS2.5

3D high-resolution Romanian Black Sea – Danube Delta coastal geomorphic surveys for change analysis 

Andrei Gabriel Dragos, Monica Palaseanu-Lovejoy, Gabriel Iordache, Irina Stanciu, Florin Pitea, Maria Ionescu, Adrian Gherghe, and Adrian Stanica

The security and wellbeing of a community is partially dependent on a critical understanding of the natural environment, landscape evolution, available resources, vital information communication in response to an event or increasing rates of change. The ability to map flooding, erosion, and habitat loss is a key tool in a country's resilience and strategies for mitigation and adaptation against costly natural hazards, and this cannot be done without high-resolution, accurate 3D data.

Structure-from-Motion (SfM) photogrammetry is a powerful technique for creating high-resolution 3D digital terrain models (DTMs) from overlapping 2D images at a relatively low cost.

We conducted several SfM-photogrammetric surveys in the Romanian Black Sea coastal zone, on the wild protected beaches in front of the Danube Delta - Edighiol barrier beach (July and November 2023) on the southern extent of the Danube Delta, and the Sf. Gheorghe beach immediately North of the southernmost arm of the Danube in the Black Sea (August 2022 and August 2023). Sf. Gheorghe is the only asymmetric active lobe in the Romanian part of the Danube Delta associated with a river-sea confluence barrier island (South of the mouth), which is a very dynamic spit with a large cyclic development. We generated DEMs and orthomosaics at 4 – 5 cm pixel resolution with a vertical mean square error between 5 to 8 cm and a mean error bias of 2 cm or less.

In the case of Sf. Gheorghe beach, between 2012 LiDAR survey and 2022 SfM survey, shoreline erosion up to 100 m was observed immediately adjacent of the northern side of the Sf. Gheorghe branch, at the confluence with the Black Sea. The erosional trend increases closer to the confluence on both Sf. Gheorghe bank and Black Sea shore sides. About 2 km North of the Sf. Gheorghe mouth the 2012 and 2022 shorelines coincide, while on the Sf. Gheorghe branch shore, the two left bank positions coincide after 400 m only. The uneven erosion near the confluence point suggests the impact of Black Sea longshore currents due to insufficient sediment from the Danube. Edighiol SfM surveys analyzed coastal dynamics, emphasizing winter storms, inundation, vegetation changes, sand dune shifts, and beach erosion.

The Danube Delta Black Sea coast erosion is primarily caused by human activities, including reduced sediment supply, altered sediment pathways (resulting from damming, embankments, and canal cutting), and accelerated climate change. Natural factors like subsidence, sea-level rise, and occasional extreme storms also contribute. SfM surveys provide quantitative analysis for assessing short- and long-term changes influenced by episodic and seasonal events in this dynamic environment.

 

Acknowledgements

This work was financed by The Core Program PN 23 30 03 01 and the H2020 DOORS, EC Grant 101000518 -  Developing Optimal and Open Research Support for the Black Sea (DOORS) project.

How to cite: Dragos, A. G., Palaseanu-Lovejoy, M., Iordache, G., Stanciu, I., Pitea, F., Ionescu, M., Gherghe, A., and Stanica, A.: 3D high-resolution Romanian Black Sea – Danube Delta coastal geomorphic surveys for change analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20826, https://doi.org/10.5194/egusphere-egu24-20826, 2024.

EGU24-21569 | Orals | OS2.5

Saving lives at sea: Integration of Oceanographic Models and Observations to Improve Coastguard Search and Rescue Operations 

Cristina Forbes, Mairéad O’Donovan, and Giovanni Coppini

Search and rescue planning tools and programs use surface currents and wind data to perform drift simulations to determine the approximate location of persons lost at sea. Access to accurate ocean and atmospheric modeling forecast data and real-time observations is critical for drift modeling simulations to enable targeted SAR operations and planning, and narrowing of search areas in the marine environment, thus saving lives at sea.

The United States Coast Guard (USCG) employs the Search and Rescue Optimal Planning System (SAROPS) for search and rescue (SAR) and planning. SAROPS accesses more than 100 environmental global and local ocean and meteorological surface currents and wind products through the Environmental Data Server (EDS) to perform thousands of Monte Carlo drift simulations and generate time-evolving probability maps which depict the envelope of the search area.

The accuracy of ocean and atmospheric models combined with observations is essential to save lives. Real-time measurements are critical in:

1) areas covered by two or more models which render current speeds/directions that do not match,

2) areas where one model is not accurate at that particular time and location,

3) remote areas (e.g. small islands in the Pacific Ocean) where ocean dynamics are not adequately represented by the global models available.

Inaccuracy in model data becomes very challenging for SAR of mariners lost at sea because searches will be conducted in wrong locations, thus delaying the rescue and expending resources.

Observations from drifters and observational networks are essential for additional SAR guidance. 95% of SAR cases are within 20 NM from the coast. 

The U.S.C.G. deploys self-locating datum marker buoys (SLDMB), Davis-style oceanographic surface drifters, from aircrafts and vessels to provide real-time currents and assist in determining the best model that matches the observations to use for drift modeling and planning. Other oceanographic measurements useful for SAR are near real-time surface currents from High Frequency Radar (HFR) networks which provide continuous maps of ocean surface currents within 200 km of the coast at high spatial (1–6 km) and temporal resolution (hourly or higher).  HFR surface currents are used for model validations, for assimilation into models, and for input to the Short-Term Predictive System (STPS), a forecast model based on HFR - all products used in SAROPS.

Collaboration between the US Coast Guard and CoastPredict’s Predict-on-Time Core Project is intended to have particular impact in remote areas, e.g. remote islands where low-resolution models restrict the efficacy of drift modeling simulations for SAR. Small islands and atolls of the Pacific rely on ocean resources for their subsistence with limited technology so the likelihood of having a distress incident is higher. Getting search and rescue units (SRUs) to those remote areas requires additional time, so the uncertainty in the location of the lost craft or persons becomes larger. Access to more accurate, high-resolution models is critical and the international network for collaboration established by CoastPredict offers an opportunity to leverage existing knowledge and a shared digital infrastructure to improve capacity in areas currently under-resourced. 

How to cite: Forbes, C., O’Donovan, M., and Coppini, G.: Saving lives at sea: Integration of Oceanographic Models and Observations to Improve Coastguard Search and Rescue Operations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21569, https://doi.org/10.5194/egusphere-egu24-21569, 2024.

EGU24-21906 | Orals | OS2.5 | Highlight

CoastPredict: the GlobalCoast framework for accelerated coordination of an integrated global system for coastal ocean observing and prediction 

Giovanni Coppini, Villy Kourafalou, Joaquín Tintoré, Emma Heslop, Jo Hopkins, Miguel Charcos Llorens, Mairéad O’Donovan, and Nadia Pinardi

The CoastPredict Programme, an endorsed Programme of the Ocean Decade, has established a central framework for coordination and practical implementation called ‘GlobalCoast’. GlobalCoast will coordinate implementation and integration of the science and technology advances from CoastPredict’s six Focus Areas at Pilot Sites in a range of contrasting Regions of the Global Coastal Ocean, using and developing best practice principles in observing, data management, modelling and co-design. The Programme Focus Areas projects address priorities related to coastal resilience including: Integrated observing and modelling for short term coastal forecasting and early warnings; Future Coastal Ocean climates: Earth System observing and modelling; Solutions for integrated coastal management; Coastal information integrated in an open and free international exchange infrastructure; Equitable coastal ocean capacity.

GlobalCoast will overcome a number of existing barriers including: the lack of an international network for Global Coastal Ocean innovation and solutions for integrated observing and prediction, and associated fragmentation of knowledge; the particular challenge regarding open and free data access in the Global South; the lack of end-user (coastal managers / communities) involvement and the long timeframe currently required to demonstrate solutions.  

Through GlobalCoast, CoastPredict will demonstrate (at Pilot Sites) an integrated observing and predicting system for the global coastal ocean and create globally replicable solutions, standards, and applications that enhance coastal resilience. A global digital cloud-based infrastructure will be key to acceleration - the cloud-based computing platform will enable accelerated data collection and open and free data sharing, and advancement of modelling and analysis tools, aligned with best practices.

How to cite: Coppini, G., Kourafalou, V., Tintoré, J., Heslop, E., Hopkins, J., Charcos Llorens, M., O’Donovan, M., and Pinardi, N.: CoastPredict: the GlobalCoast framework for accelerated coordination of an integrated global system for coastal ocean observing and prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21906, https://doi.org/10.5194/egusphere-egu24-21906, 2024.

EGU24-446 | ECS | Posters on site | OS1.11

Untangling the Multi-model Spread in 21st Century AMOC Projections 

Harry Ashton-Key, Jennifer Mecking, and Sybren Drijfhout

The Atlantic Meridional Overturning Circulation (AMOC) plays an important role in the global climate by transporting heat northward. According to the latest IPCC report (AR6) the strength of the AMOC is very likely to weaken by 2100 (Fox-Kemperer et al. 2021). A weaker AMOC would significantly impact local and global climate. However, there is large model spread in the magnitude of the projected reduction in AMOC strength (Weijer et al. 2020) so it is unclear to what extent the AMOC will weaken by the end of the 21st century.

This study investigates the spread in AMOC response among CMIP6 models. As an initial step we investigated the model correlations of AMOC weakening across different ScenarioMIP experiments. Preliminary results show that the decline for similarly forced scenarios, such as ssp370 and ssp585, have stronger correlations than for scenarios with significantly different forcing, such as ssp126 and ssp585.

Further analyses into the relationship between the projected weakening and model biases in ocean temperature,  salinity and meridional density gradients are performed. In addition, we investigate how the weakening correlates with possible drivers. A better understanding of how model biases influence AMOC changes will allow for more accurate projections of future AMOC changes and their impacts, as well as improved understanding of what the driving processes of the weakening are in various models.

How to cite: Ashton-Key, H., Mecking, J., and Drijfhout, S.: Untangling the Multi-model Spread in 21st Century AMOC Projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-446, https://doi.org/10.5194/egusphere-egu24-446, 2024.

EGU24-1969 | ECS | Orals | OS1.11

Crucial role of ocean dynamics for the CMIP models equatorial Pacific warming pattern diversity 

Vincent Danielli, Matthieu Lengaigne, Sadhvi Kwatra, Gopika Suresh, and Jérome Vialard

Coupled Model Intercomparison Project (CMIP) projections indicate a distinct future warming pattern in the tropical Pacific, with enhanced warming in the equatorial Pacific (resembling El Niño warming) and subdued warming in the southeast tropical Pacific. There is currently no consensus on the mechanisms shaping this pattern and its inter-model diversity.

Here, we employ the Sea Surface Temperature (SST) heat budget proposed by Zhang and Li (2014, ZL14), adapted to Relative SST (SST minus its tropical average), a proxy for atmospheric stability and circulation changes. This approach helps uncover the mechanisms that shape the tropical Pacific Multi-Model Mean (MMM) warming pattern and its diversity across historical and unmitigated scenario (RCP85 and SSP585) simulations from 53 CMIP5 and CMIP6 models.

We find that the MMM southeast Pacific relative cooling arises from locally intensified winds, leading to increased latent heat flux cooling. This process also explains the inter-model diversity in this region, alongside the diversity of cloud feedbacks.

Consistent with ZL14 conclusions, our results underscore that the MMM equatorial Pacific relative warming results from a less efficient evaporative cooling feedback over the climatologically cooler central and eastern Pacific. However, our study highlights a pivotal role of ocean dynamics in driving the equatorial Pacific relative warming inter-model diversity. In the eastern Pacific, this diversity is related to the cold tongue bias, with a stronger cold tongue bias leading to a more efficient thermostat mechanism that dampens the MMM relative warming. In the western Pacific, diversity is related to the intensity of the equatorial trade winds relaxation, with stronger westerly anomalies leading to enhanced warming, suggesting a strong role of the Bjerknes feedback.

These results advocate for more comprehensive studies using dynamical approaches to better understand the respective roles of the Bjerknes feedback and cold tongue bias in the equatorial Pacific warming pattern and, ultimately, in the Walker Circulation changes.

How to cite: Danielli, V., Lengaigne, M., Kwatra, S., Suresh, G., and Vialard, J.: Crucial role of ocean dynamics for the CMIP models equatorial Pacific warming pattern diversity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1969, https://doi.org/10.5194/egusphere-egu24-1969, 2024.

Examining the wave climate under climate change scenarios requires a concurrent analysis of both historical and predicted future wave data. This involves using historical wave data to understand seasonal fluctuations and long-term trends, while also utilizing future wave data to predict waves under diverse climate change scenarios. This information is pivotal for evaluating forthcoming risks and formulating strategies for climate change adaptation. This study employs historical wind field data, including ERA5 reanalysis data and CWB/WRF analysis field data, as well as wind field data from the CMIP6 dataset under the SSP5-8.5 extremely high emission scenario. These data are used to drive the WAVEWATCH III wave model for simulating waves. This study initially compared the simulated wave data from the WAVEWATCH III wave model with one year of observed wave data from met-ocean buoys. The results confirmed the high credibility of the simulated waves. Subsequently, extensive data simulations are conducted, encompassing historical wave data (1975-2022) and projected wave data for the future (2025-2100).

This study delves into the long-term temporal variations in wave height in Taiwanese waters and the differential regional trends in spatial changes. Regarding temporal changes, the wave heights are averaged year by year, and then linear regression is performed in units of years. The slope of the regression equation indicates the long-term linear trend of wave height in Taiwanese waters over the years, revealing an increasing trend from the past to the future. Regarding spatial changes, the average wave height at each grid point is calculated, and linear regression is applied to determine the long-term trends in wave height at each grid point from the past to the future. The findings unveil a positive growth trend in Taiwanese waters. Furthermore, Taiwanese watersexperience distinct weather patterns in each season, such as the influence of the northeasterly monsoon in winter and typhoons or southwestern winds in summer. This study further explores the differences and variations of wave during spring (March to May), summer (June to August), autumn (September to November), and winter (December to February of the following year). The analysis results indicate negative growth trends in spring and summer, and positive growth trends are observed in autumn and winter, indicating a noticeable increase in wave height in Taiwanese waters during autumn and winter under the influence of climate change.

How to cite: Fan, Y.-M.: Temporal and spatial varieties of future wave climate under the scenario of climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3018, https://doi.org/10.5194/egusphere-egu24-3018, 2024.

EGU24-3137 | Posters on site | OS1.11

Contrasting future changes in the North Atlantic and Nordic Seas overturning circulations 

Marius Årthun, Helene Asbjørnsen, Leon Chafik, Helen L. Johnson, and Kjetil Våge

The Atlantic meridional overturning circulation (AMOC) carries warm and saline waters northwards near the surface and cold, dense waters southwards at depth. The northward branch of the AMOC terminates north of the Greenland-Scotland Ridge that separates the North Atlantic Ocean from the Nordic Seas and Arctic Ocean. Here, we use large ensemble simulations and CMIP6 models to show that future circulation changes in the subtropical North Atlantic (26.5°N) and in the Nordic Seas show contrasting behavior.

In a high emission scenario (SSP585), CMIP6 models show a gradual weakening of the subtropical AMOC. This weakening can be deconstructed by quantifying changes in the Gulf Stream, Deep Western Boundary Current (DWBC), and gyre recirculation (Asbjørnsen & Årthun 2023). By the end of the century, the Gulf Stream weakens by 29% and the DWBC weakens by 47%. The gyre recirculation component shows a weakening of 12%, indicative of a weakened subtropical gyre. 33% of the Gulf Stream weakening is due to changes in winds.

In contrast to the North Atlantic, the overturning circulation in the Nordic Seas increases throughout most of the 21st century as a result of changes in water mass transformation and horizontal circulation (Årthun et al. 2023). The increased Nordic Seas overturning is furthermore manifested in the overturning circulation in the eastern subpolar North Atlantic (OSNAP-East). A strengthened Nordic Seas overturning circulation could therefore be a stabilizing factor in the future AMOC.

 

Årthun, M., Asbjørnsen, H., Chafik, L.Johnson, H. L., Våge, K. Future strengthening of the Nordic Seas overturning circulation. Nature Communications, 14, 2065 (2023). https://doi.org/10.1038/s41467-023-37846-6

Asbjørnsen, H., & Årthun, M. (2023). Deconstructing future AMOC decline at 26.5°N. Geophysical Research Letters, 50, e2023GL103515. https://doi.org/10.1029/2023GL103515

How to cite: Årthun, M., Asbjørnsen, H., Chafik, L., Johnson, H. L., and Våge, K.: Contrasting future changes in the North Atlantic and Nordic Seas overturning circulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3137, https://doi.org/10.5194/egusphere-egu24-3137, 2024.

EGU24-3144 | ECS | Orals | OS1.11

Overturning Pathways Control AMOC Weakening in CMIP6 Models 

Jonathan Baker, Michael Bell, Laura Jackson, Richard Renshaw, Geoffrey Vallis, Andrew Watson, and Richard Wood

Future projections indicate the Atlantic Meridional Overturning Circulation (AMOC) will weaken and shoal in response to global warming, but models disagree widely over the amount of weakening. We analyse projected AMOC weakening in 34 CMIP6 climate models, in terms of changes in three return pathways of the AMOC. The branch of the AMOC that returns through diffusive upwelling in the Indo-Pacific, but does not later upwell in the Southern Ocean (SO), is particularly sensitive to warming, in part, because shallowing of the deep flow of the AMOC prevents it from entering the Indo-Pacific via the SO. In most models, this Indo-Pacific pathway declines to zero by 2100. Thus, the present-day strength of this pathway provides a strong constraint on the projected AMOC weakening. However, estimates of this pathway using four observationally based methods imply a wide range of AMOC weakening under the SSP5-8.5 scenario of 29%–61% by 2100. Our results suggest that improved observational constraints on this pathway would substantially reduce uncertainty in 21st century AMOC decline. We also present new findings that compare the AMOC response in realistic warming scenarios with those found under more extreme climate forcings, including quadrupled CO2 concentrations and large North Atlantic freshwater forcing.

How to cite: Baker, J., Bell, M., Jackson, L., Renshaw, R., Vallis, G., Watson, A., and Wood, R.: Overturning Pathways Control AMOC Weakening in CMIP6 Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3144, https://doi.org/10.5194/egusphere-egu24-3144, 2024.

EGU24-3561 | Orals | OS1.11

AMOC thresholds in CMIP6 models: NAHosMIP 

Laura Jackson, Alastrue de Asenjo Eduardo, Bellomo Katinka, Danabasoglu Gokhan, Haak Helmuth, Hu Aixue, Jungclaus Johann, Lee Warren, Meccia Virna, Saenko Oleg, Shao Andrew, and Swingedouw Didier

The Atlantic meridional overturning circulation (AMOC) is an important part of our climate system, which keeps the North Atlantic relatively warm. It is predicted to weaken under climate change. The AMOC may have a threshold beyond which recovery is difficult, hence showing quasi-irreversibility (hysteresis). Although hysteresis has been seen in simple models, it has been difficult to demonstrate in comprehensive global climate models.

We present results from the North Atlantic hosing model intercomparison project, where we applied an idealised forcing of a freshwater flux over the North Atlantic in 8 CMIP6 models to explore this threshold. The AMOC weakens in all models from the freshening, but once the freshening ceases, the AMOC recovers in some models, and in others it stays in a weakened state. We will discuss mechanisms behind the different behaviour in the different models. 

 

How to cite: Jackson, L., Eduardo, A. D. A., Katinka, B., Gokhan, D., Helmuth, H., Aixue, H., Johann, J., Warren, L., Virna, M., Oleg, S., Andrew, S., and Didier, S.: AMOC thresholds in CMIP6 models: NAHosMIP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3561, https://doi.org/10.5194/egusphere-egu24-3561, 2024.

EGU24-4017 | ECS | Orals | OS1.11

The weakening AMOC under extreme climate change 

Gaurav Madan, Ada Gjermunsen, Silje C. Iversen, and Joseph H. LaCasce

Changes in the Atlantic Meridional Overturning Circulation (AMOC) in the quadrupled CO2 experiments conducted underthe sixth Coupled Model Intercomparison Project (CMIP6) are examined. Increased CO2 triggers extensive Arctic warming,causing widespread melting of sea ice. The resulting freshwater spreads southward, first from the Labrador Sea and then theNordic Seas, and proceeds along the eastern coast of North America. The freshwater enters the subpolar gyre north of theseparated Gulf Stream, the North Atlantic Current. This decreases the density gradient across the current and the currentweakens in response, reducing the inflow to the deepwater production regions. The AMOC cell weakens in tandem, firstnear the North Atlantic Current and then spreading to higher and lower latitudes. This contrasts with the common perceptionthat freshwater caps the convection regions, stifling deepwater production; rather, it is the inflow to the subpolar gyre thatis suppressed. Changes in surface temperature have a much weaker effect, and there are no consistent changes in local orremote wind forcing among the models. Thus an increase in freshwater discharge, primarily from the Labrador Sea, is theprecursor to AMOC weakening in these simulations.

How to cite: Madan, G., Gjermunsen, A., Iversen, S. C., and LaCasce, J. H.: The weakening AMOC under extreme climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4017, https://doi.org/10.5194/egusphere-egu24-4017, 2024.

EGU24-4310 | ECS | Orals | OS1.11

New Arctic quality metrics based on oceanic transports for CMIP6 

Susanna Winkelbauer, Michael Mayer, and Leopold Haimberger

Oceanic transports of heat, volume and salinity are an integral part of the Earth's energy and mass budgets and play a key role in regulating the Earth's climate. Changes in the ocean’s transport patterns may affect regional as well as global climates. Accurate monitoring is critical and there are several regional measuring lines like the RAPID 26N and OSNAP (Overturning in the Subpolar North Atlantic Program) array, as well as measuring lines across Arctic water straits, which are equipped with moorings and other advanced measuring systems. It is desirable to compare the transports calculated by these instruments with ocean reanalyses and climate models. However, this is challenging because the moorings are not aligned with the model grids, and the ocean model grids get complicated especially towards more northern latitudes.

To address this challenge, we introduce StraitFlux (https://pypi.org/project/straitflux/), a versatile tool enabling precise and mass-consistent calculation of volume, heat, and salinity transports across any oceanic section. We have used StraitFlux to calculate transports from reanalyses and climate models (CMIP6) in the Arctic region and to compare them to available observations. While we find some biases, especially in straits that are narrow and bathymetrically complicated, the results generally show that reanalyses capture the main current patterns quite well. Climate models on the other hand exhibit larger and often systematic deviations from the mooring and reanalysis output. The spread among climate models is 3-5 times larger than the spread between observation-based transports and reanalyses or among reanalyses, and it cannot be explained by natural variability. The large spread in flux quantities is related to mean-state biases in relevant state quantities. It helps to quantify and understand the strong connections between lateral OHT and the mean state as well as changes in the Arctic Ocean and sea ice.

Expanding on our methodology, we develop physically based metrics tailored to the Arctic, to detect outliers from the CMIP6 model ensemble and constrain model projections using a weighting approach incorporating the models’ performance and independence. This effectively reduces the spread of future projections of Arctic change. Further, using StraitFlux, we investigate constrained changes in Arctic volume, heat, and salinity transports for the main SSP scenarios. We examine cross-sections of the main Arctic gateways to assess future changes in the structures and strengths of the main currents and their effects on the Arctic system.

How to cite: Winkelbauer, S., Mayer, M., and Haimberger, L.: New Arctic quality metrics based on oceanic transports for CMIP6, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4310, https://doi.org/10.5194/egusphere-egu24-4310, 2024.

The ability of a coarse-resolution ocean model to simulate the response of the Southern Ocean Meridional Overturning Circulation (MOC) to enhanced westerlies is evaluated as a function of the eddy transfer coefficient (κ), which is commonly used to parameterize the bolus velocities induced by unresolved eddies. The strongest eddy-induced MOC response, accounting for 82% of the reference eddy-resolving simulation, is achieved using a stratification-dependent κ with spatiotemporal variability. By decomposing the eddy-induced velocity into its vertical variation (VV) and spatial structure (SS) components, we find that the intensified eddy compensation response is primarily driven by the enhanced SS term, while the introduced VV term weakens the response. Additionally, the temporal variation of the stratification-dependent κ plays a key role in strengthening the eddy compensation response to intensified westerlies. The stronger eddy compensation response in the experiment with stratification-dependent κ than the constant κ can be attributed to the structure of κ and the vertical variation of the density slope. These findings highlight the significance of accurately representing κ for capturing the response of the Southern Ocean MOC and emphasize the role of the isopycnal slope in modulating the eddy compensation mechanism.

How to cite: Li, Y., Liu, H., Lin, P., Chassignet, E., Yu, Z., and Wu, F.: Quantifying the role of the eddy transfer coefficient in simulating the response of the Southern Ocean Meridional Overturning Circulation to enhanced westerlies in a coarse-resolution model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4971, https://doi.org/10.5194/egusphere-egu24-4971, 2024.

EGU24-5263 | ECS | Posters on site | OS1.11 | Highlight

AMOC tipping under Climate Change in the Community Earth System Model 

René van Westen and Henk Dijkstra

Recent quasi-equilibrium simulations with the Community Earth System Model (CESM) have shown that the Atlantic Meridional Overturning Circulation (AMOC) in a pre-industrial climate is a multi-stable system (van Westen & Dijkstra, 2023). By slowly increasing the surface freshwater forcing strength over the North Atlantic Ocean, the AMOC tips from a northward overturning state (strength of 17 Sv) to a fully  collapsed state (strength of 0 Sv). When reversing the freshwater forcing, the AMOC recovers at  smaller values of this forcing compared to the collapse, giving rise to hysteresis behaviour. Here we analyse AMOC tipping under climate change using the same CESM version. From the hysteresis experiment, we branch off simulations under fixed freshwater forcing values to find the statistical steady states. We follow these states under climate change up to 2100 (historical forcing followed by SSP5-8.5) and then run the simulation into equilibrium under constant year 2100 conditions. We find an AMOC tipping event during the 21st century and we compare this event to the one from the pre-industrial quasi-equilibrium simulation. The rate of AMOC changes and the AMOC-related impacts are comparable to the quasi-equilibrium simulation. However, the initial AMOC weakening and the collapsed AMOC state are very different under climate change. Temperature changes primarily drive the initial AMOC weakening and the collapsed state has a very weak (strength of 1 Sv) and shallow (< 1000 m) northward overturning circulation in the Atlantic Ocean. The results indicate that the strong northward overturning statistical steady states disappear under climate change and that only the collapsed AMOC state exists under a high-end emission scenario.

How to cite: van Westen, R. and Dijkstra, H.: AMOC tipping under Climate Change in the Community Earth System Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5263, https://doi.org/10.5194/egusphere-egu24-5263, 2024.

EGU24-6654 | ECS | Orals | OS1.11

Understanding CMIP6 Inter-model Spread of Projected Change in Tropical Sea Surface Salinity 

Shanshan Pang, Jérôme Vialard, Matthieu Lengaigne, and Xidong Wang

Here, we analyze projected tropical sea surface salinity (SSS) changes in 32 Coupled Model Intercomparison Projects phase 6 (CMIP6) global climate models historical simulations and representative concentration pathway 8.5 (SSP5-8.5) scenario. A robust “fresh gets fresher” pattern emerges by the end of the twenty-first century, with fresher tropical Indian and Pacific Oceans and saltier tropical Atlantic Ocean. We examine the inter-model diversity in this pattern using Empirical Orthogonal Function (EOF) analysis. The first two EOFs explain 45% of the total variance. EOF2 (22%) is a modulation of the multi-model mean SSS change, associated with the tropical-average warming intensity (r=0.61). Higher climate sensitivity leads to a more pronounced El Niño-like (positive IOD-like) warming pattern and stronger rainfall in the equatorial and north subtropical Pacific (west Indian) Ocean, leading to local freshening. In the equatorial Atlantic, an enhanced warming leads to more evaporation through the Clausius–Clapeyron relation, and a stronger SSS saltening. The “fresh gets fresher” SSS pattern inter-model diversity is thus more a response to the SST pattern diversity through the “warmer gets wetter” mechanism than an evidence of the “wet gets wetter” intensification of the hydrological cycle. EOF1 (25%) is characterized by saltening in the Indian Ocean and freshening in the Pacific Ocean, associated with changes in the inter-hemispheric relative SST gradient (r=0.55). Enhanced warming in the south hemisphere shifts the precipitation south, reducing total rainfall and saltening the Indian Ocean, while increasing rainfall and freshening the south Pacific Ocean. Overall, we find a strong influence of SST changes on the rainfall distribution, which influences SSS with some effects related to transport by the oceanic circulation.

How to cite: Pang, S., Vialard, J., Lengaigne, M., and Wang, X.: Understanding CMIP6 Inter-model Spread of Projected Change in Tropical Sea Surface Salinity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6654, https://doi.org/10.5194/egusphere-egu24-6654, 2024.

EGU24-11017 | Orals | OS1.11

Constraining CMIP6 model ensemble spread to reduce uncertainty in the representation of the Atlantic water layer temperature in the Arctic Ocean 

Marion Devilliers, Steffen M. Olsen, Shuting Yang, Helene R. Langehaug, Tian Tian, Chuncheng Guo, and Rashed Mahmood

We aim at reducing the uncertainties in the climate predictions of the Arctic region which is going under rapid changes with global repercussions. We analyse the spread in the Atlantic water core temperature across multi member CMIP6 historical simulations, focusing on different regions of the Arctic Ocean. While the redistribution of heat plays a critical role in the dynamics of the Arctic Ocean basins, it is usually not well represented in climate models, leading to divergent projections of future changes in the Arctic. To address this limitation, we compare CMIP6 model outputs with available reanalysis and observational products, in order to identify the biases within the model simulations and develop new metrics to constrain the model ensemble spread. Such metrics can be used to select the multi model ensemble members and construct a subsample with improved representation of the core temperature evolution over the historical period resulting in a reduced uncertainty in near-term future projections of the Arctic climate.

How to cite: Devilliers, M., Olsen, S. M., Yang, S., Langehaug, H. R., Tian, T., Guo, C., and Mahmood, R.: Constraining CMIP6 model ensemble spread to reduce uncertainty in the representation of the Atlantic water layer temperature in the Arctic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11017, https://doi.org/10.5194/egusphere-egu24-11017, 2024.

EGU24-11172 | ECS | Posters on site | OS1.11

The thermohaline stream function in a changing climate 

Verena Jung and Kristofer Döös

The thermohaline stream function is a powerful tool to analyse water mass transformation (WMT). Traditionally, the meridional overturning circulation is visualised in geographical coordinates with stream functions as a function of latitude whereby the meridional velocity is zonally integrated. Conversely, in the thermohaline framework the entire global ocean is represented in oceanographic well-established coordinates namely absolute salinity and potential temperature. This allows to analyse WMT between cold and warm as well as saline and fresh waters in one single graph. It is generally constituted of a tropical cell, a conveyor belt and a polar cell. Here, we present stream functions from various CMIP6 climate scenarios computed by the EC-Earth model and compare pre-industrial, present-day and climate scenario simulations to study changes in WMT. We further provide background information on how the thermohaline stream function (left panel of the attached Figure) is motivated physically and computed mathematically using Helmholtz decomposition. This allows us to identify sources and sinks of mass in the corresponding thermohaline tendency potential, as shown in the right panel of the attached Figure. The position in the temperature and salinity space of the overturning cells reveal significant differences in the climate scenarios, as well as  differences in the mass sources and sinks revealed by the tendency potentials. These sources are due to the fresh water fluxes through the sea surface  and for the data assimilation data sets, they are also due to mass, heat and salt sources and sinks withing the ocean subsurface domain.


Fig: The thermohaline stream function (left panel) and tendency potential (right panel) computed using data from the ocean component of an EC-Earth model (present-day simulation coloured in red and blue, SSP585-simulation in grey contour lines). They capture the entire ocean circulation in two figures describing the water mass transformation in temperature and salinity.

How to cite: Jung, V. and Döös, K.: The thermohaline stream function in a changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11172, https://doi.org/10.5194/egusphere-egu24-11172, 2024.

EGU24-11529 | ECS | Orals | OS1.11

The impact of Greenland ice sheet melt on the future North Atlantic ocean circulation 

Oliver Mehling, Katinka Bellomo, Federico Fabiano, Marion Devilliers, Jost von Hardenberg, and Susanna Corti

Changes in surface freshwater fluxes are a main factor governing the response of the ocean circulation to future climate change. However, they are not well-represented in the most recent generation of Earth System Models (CMIP6), as most CMIP6 models do not include an interactive ice sheet component. Instead, most of them use a very idealized representation of ice sheets. While this approach may yield the correct order of magnitude for present-day meltwater runoff, it might not accurately extrapolate the increasing ice melt under future global warming.

Here, we address this deficiency by prescribing physically plausible meltwater fluxes from the Greenland ice sheet in a CMIP6 model, EC-Earth3, under a strong global warming scenario (SSP5-8.5) until the 23rd century. The meltwater fields were obtained from a CESM2-CISM simulation in which the Greenland ice sheet was fully coupled. The corresponding meltwater flux reaches about 0.4 Sv by the year 2300, comparable to what is often used in water hosing experiments. Using two EC-Earth ensembles of four members each (with and without Greenland meltwater flux), we compare the impact of this previously underestimated runoff on long-term projections of deep-water formation in the North Atlantic and on the evolution of the Atlantic Meridional Overturning Circulation. Our results allow us to quantify the importance of Greenland meltwater on AMOC weakening under strong global warming.

How to cite: Mehling, O., Bellomo, K., Fabiano, F., Devilliers, M., von Hardenberg, J., and Corti, S.: The impact of Greenland ice sheet melt on the future North Atlantic ocean circulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11529, https://doi.org/10.5194/egusphere-egu24-11529, 2024.

EGU24-775 | ECS | Posters on site | OS1.1

The rapid life of Arctic sea-ice ridge consolidation and melt 

Evgenii Salganik, Benjamin Lange, Christian Katlein, Ilkka Matero, Dmitry Divine, Polona Itkin, Knut Høyland, and Mats Granskog

In this study, we cover observations of the rapid consolidation and enhanced melt of Arctic sea-ice ridges. During the freezing period, the consolidated part of sea ice ridges is usually up to 1.6–1.8 times thicker than surrounding level ice. Meanwhile, during the melt season, ridges are often observed to be fully consolidated, but this process is not fully understood. We present the evolution of the morphology and temperature of a first-year ice ridge studied during MOSAiC from its formation to advanced melt. From October to May, the draft of first-year ice at the MOSAiC coring site increased from 0.3 m to 1.5 m, while from January to July, the consolidated layer thickness in the ridge reached 3.9 m. We observed several types of ridge consolidation. From the beginning of January until mid-April, the ridge consolidated slowly through heat loss to the atmosphere, with a total consolidated layer growth of 0.7 m. From mid-April to mid-June, there was a rapid increase in ridge consolidation rates, despite conductive heat fluxes not increasing. In this period, the mean thickness of the consolidated layer increased by 2.2 m. We also estimated a substantial snow mass fraction (6%–11%) of ridges using analysis of oxygen isotope composition. Our observations suggest that this sudden change was related to the transport of snow-slush inside the ridge keel via adjacent open leads that decreased ridge macroporosity, which could result in more rapid consolidation.

During the summer season, sea ice melts from the surface and bottom. The melt rates substantially vary for sea ice ridges and undeformed first- and second-year ice. Ridges generally melt faster than undeformed ice, while the melt of ridge keels is often accompanied by further summer growth of their consolidated layer, which increases their survivability. We examined the spatial variability of ice melt for different types of ice from in situ drilling, coring, and multibeam sonar scans of the remotely operated underwater vehicle. Six sonar scans performed from 24 June to 21 July were analyzed and validated using seven ice drilling transects. The area investigated by the sonar (0.4 km by 0.2 km) consisted of several ice ridges, surrounded by first- and second-year ice. We show a substantial difference in melt rates for sea ice with a different draft. We also show how ridge keels decay depending on the keel draft, width, steepness, and location relative to the surrounding ridge keel edges. We also use temperature buoy data to distinguish snow, ice surface, and bottom melt rates for both ridges and level ice. These results are important for quantifying ocean heat fluxes for different types of ice during the advanced melt and for estimating the ridge contribution to the total ice mass and summer meltwater balances of the Arctic Ocean.

How to cite: Salganik, E., Lange, B., Katlein, C., Matero, I., Divine, D., Itkin, P., Høyland, K., and Granskog, M.: The rapid life of Arctic sea-ice ridge consolidation and melt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-775, https://doi.org/10.5194/egusphere-egu24-775, 2024.

EGU24-929 | ECS | Posters on site | OS1.1 | Highlight

Potential effects of summer Cryosat-2 sea ice thickness observations on sea ice forecast 

Ruizhe Song, Longjiang Mu, Xianyao Chen, Frank Kauker, Svetlana Loza, and Martin Losch

Skillful Arctic sea ice forecast for the melting season remains a great challenge because there is no reliable pan-Arctic sea ice thickness (SIT) data set for the summertime. A new summer Cryosat-2 SIT observation data set based on an artificial intelligence algorithm may mitigate the situation. We assess the impact of this new data set on the initialization of both short-term and long-term sea ice forecasts in the melting seasons of 2015 and 2016 in a sea-ice couple model with data assimilation. We find that the assimilation of the new summer CryoSat-2 SIT observations can reduce the summer ice edge prediction error. Further, adding SIT observations to an established forecast system with sea ice concentration assimilation leads to a more realistic short-term summer ice edge forecast in the Arctic Pacific sector. The long-term Arctic-wide SIT prediction is also improved especially before the onset of freezing. In spite of remaining uncertainties,  summer CryoSat-2 SIT observations have the potential to enhance Arctic sea ice forecast on multiple time scales.

How to cite: Song, R., Mu, L., Chen, X., Kauker, F., Loza, S., and Losch, M.: Potential effects of summer Cryosat-2 sea ice thickness observations on sea ice forecast, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-929, https://doi.org/10.5194/egusphere-egu24-929, 2024.

The Arctic region is experiencing a notable increase in precipitation, known as Arctic wetting, amidst the backdrop of Arctic warming. This phenomenon has implications for the Arctic hydrological cycle and numerous socio-ecological systems. However, the ability of climate models to accurately simulate changes in Arctic wetting has not been thoroughly assessed. In this study, we analyze total precipitation in the Arctic using station data, multiple reanalyses, and 35 models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6). By employing the moisture budget equation and an evaluation method for model performance with ERA5 reanalysis as a reference, we evaluated the models’ capability to reproduce past Arctic wetting patterns. Our findings indicate that most reanalyses and models are able to replicate Arctic wetting. However, the CMIP6 models generally exhibit an overestimation of Arctic wetting during the warm season and an underestimation during the cold season from 1979 to 2014 when compared to the ERA5 reanalysis. Further investigation reveals that the overestimation of wetting during the warm season is largest over the Arctic Ocean’s northern part, specifically the Canadian Arctic Archipelago, and is associated with an overestimation of atmospheric moisture transport. Conversely, the models significantly underestimate wetting over the Barents-Kara Sea during the cold season, which can be attributed to an underestimation of evaporation resulting from the models’ inadequate representation of sea ice reduction in that region. The models with the best performance in simulating historical Arctic wetting indicate a projected intensification of Arctic wetting, and optimal models significantly reduce uncertainties in future projections compared to the original models, particularly in the cold season and oceanic regions. Our study highlights significant biases in the CMIP6 models’ simulation of Arctic precipitation, and improving the model’s ability to simulate historical Arctic precipitation could reduce uncertainties in future projections.

How to cite: Cai, Z. and You, Q.: Arctic wetting: Performances of CMIP6 models and projections of precipitation changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1673, https://doi.org/10.5194/egusphere-egu24-1673, 2024.

EGU24-1892 | ECS | Orals | OS1.1

Observations of deep near-inertial internal waves in the Eurasian Basin. 

Joel Bracamontes Ramírez and Maren Walter

The Arctic Ocean has a less energetic internal wave climate than other oceans, mainly due to the thick sea ice cover which inhibits wind interaction with the surface. With the continued decrease in summer sea ice extent and the increase in seasonal ice-free areas, wind-driven internal waves, especially in the near-inertial range, are becoming more energetic. Coupled with the fact that most of the Arctic Ocean lies north of the critical latitude for semi-diurnal tides, the shift in ice dynamics implies an increase in the importance of near-inertial waves (NIW) for the internal wave climate. In particular, increased NIW amplitude and kinetic energy in the Canadian Basin and enhanced wind-driven vertical heat fluxes and dissipation rates in the Eurasian Basin have already been observed in the upper column. In the deep ocean beyond the critical latitude, NIWs are expected to drive mixing in the interior, but it is unclear to what extent. Here, we present innovative and unprecedented deep current observations from a mooring in the Gakkel Ridge in the Eurasian Basin at 82.53°N. The presence of barotropic diurnal and semi-diurnal tides and semi-diurnal harmonics enriches the complex interplay of internal waves. By comparing the observed downward and upward NIW kinetic energy with wind speed, sea ice properties and numerical simulations, we discuss the likely surface origin of the NIW. In particular, there is a lagged correlation of <26 days between ice drift speed and downward NIW energy, and of ~15 days between wind factor and downward NIW energy. In addition, the buoyancy frequency is weaker than the local Coriolis frequency, effectively limiting NIW propagation. Evidence for wave reflection is found and also discussed, with a focus on the implications for NIW coming from the surface.

How to cite: Bracamontes Ramírez, J. and Walter, M.: Observations of deep near-inertial internal waves in the Eurasian Basin., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1892, https://doi.org/10.5194/egusphere-egu24-1892, 2024.

The Arctic is one of Earth’s regions most susceptible to climate change. Climate models show that in a warming climate, the Arctic Ocean warms much faster than the global ocean mean, mainly due to the rapid warming of the Atlantic layer, which is called 'Arctic Ocean Amplification.' However, climate models still encounter challenges with large biases and considerable inter-model spread in the Arctic Ocean. For example, the Atlantic layer in the Arctic Ocean, simulated by the climate models, is too thick and too deep. This leads to the warming trend, and inter-annual variability of the simulated Atlantic Water that are too small compared to the observations. Here, we present Arctic Ocean dynamical downscaling simulations and projections based on a high-resolution ice-ocean coupled model, FESOM, and a climate model, FIO-ESM. The historical results demonstrate that the root mean square errors of temperature and salinity in the downscaling simulations are much smaller than those from CMIP6 climate models. The common biases, such as the overly deep and thick Atlantic layer in climate models, are significantly reduced by dynamical downscaling. Dynamical downscaling projections show that the Arctic Ocean may warm faster than the projections made by CMIP6 fully-coupled climate models.

How to cite: Shu, Q. and Wang, Q.: Dynamical downscaling simulations and future projections of the Arctic Ocean based on FESOM and FIO-ESM., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1921, https://doi.org/10.5194/egusphere-egu24-1921, 2024.

EGU24-1922 | Posters on site | OS1.1

Estimation of Sea Ice Production in the North Water Polynya Based on Ice Arch Duration in Winter During 2006–2019 

Fengming Hui, Haiyi Ren, Mohammed Shokr, Xiao Cheng, Xinqing Li, and Zhilun Zhang

The North Water Polynya (NOW) is the largest recurrent Arctic coastal polynya. The formation of the NOW is critically dependent on the development of an ice arch that defines its northern boundary. In this study, high-resolution ENVISAT Advanced Synthetic Aperture Radar data, Sentinel-1A data, and Moderate Resolution Imaging Spectroradiometer data were employed to identify the spatio-temporal characteristics of the ice arch during 2006–2019. Polynya pixels were identified based on the thin ice thickness (TIT), using a threshold of TIT <0.2 m, from which the polynya extent, heat flux, and ice production (IP) were estimated. The results show the different locations of the ice arch in different years, with a mean duration of 132 ± 69 days. The average annual polynya extent over the 14 years is ∼38.8 ± 8 × 103 km2, and we found that it is more closely correlated with wind speed during the winter and air temperature during early spring. The average heat flux drops from about 248 W/m2 in the winter months to about 34 W/m2 in May. The average accumulated IP varies significantly every year, with an average of 144 ± 103 km3, and peak values in March in most years. No apparent interannual trends are shown for the polynya area, heat flux, and IP during 2006–2019. The results also show that IP calculated based on the ice arch data is approximately 25% lower than that obtained by assuming a fixed time, location, and duration for the polynya.

How to cite: Hui, F., Ren, H., Shokr, M., Cheng, X., Li, X., and Zhang, Z.: Estimation of Sea Ice Production in the North Water Polynya Based on Ice Arch Duration in Winter During 2006–2019, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1922, https://doi.org/10.5194/egusphere-egu24-1922, 2024.

Sea ice in the high latitude is an indicator of climate change and has undergone dramatic changes because of recent global warming. Synthetic aperture radar (SAR) is a relatively practical tool for sea ice monitoring because of its low sensitivity to clouds, rain, and fog, as well as its capability for high-resolution earth observation in daylight or darkness. With the progression in SAR systems from single-pol to dual-pol, quad-pol and hybrid-pol, large numbers of parameters have been proposed for sea ice classification. Even though a large number of SAR characteristics have been used to classify sea ice, it remains unclear which parameters are the most effective for different regions and seasonal or environmental conditions. Meanwhile, classification studies for fine sea ice with high spatial resolution and many sub-types of sea ice, particularly in the case of rapidly changing first-year ice (FYI), which includes new ice (NI), young ice (YI), and FYI, are rather few. NI and YI have comparatively thinner thickness, and are often classified as FYI in these studies[1].

A new method of sea ice classification based on feature selection from Gaofen-3 polarimetric SAR observations is proposed. The new approach classifies sea ice into four categories: open water, NI, YI, and FYI. Seventy parameters that have previously been applied to sea ice studies are re-examined for sea ice classification in the Okhotsk Sea near the melting point on 28 February 2020. The ‘separability index’ is used for the selection of optimal features for sea ice classification. Full polarization (σohh, SEi, Ks) and hybrid polarization parameters (σorl, CPSEirh-rv, αs) are determined as optimal. The selected parameters are used to classify NI, YI, and FYI using a SVM machine learning classifier; and classification results are validated by manually interpreted ice maps derived from Landsat-8 data.

 


[1]Sea ice: types and forms - Canada.ca

How to cite: Li, H. and Yang, K.: Fine resolution classification of new ice, young ice, and first-year ice based on feature selection from Gaofen-3 quad-polarization SAR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2666, https://doi.org/10.5194/egusphere-egu24-2666, 2024.

EGU24-2699 | Posters on site | OS1.1

Changes in ocean circulation and dissolved oxygen/nutrient distributions in the Canadian Basin 

Shigeto Nishino, Jinyoung Jung, Kyoung-Ho Cho, William Williams, Amane Fujiwara, Akihiko Murata, Motoyo Itoh, Eiji Watanabe, Mariko Hatta, Michiyo Yamamoto-Kawai, Takashi Kikuchi, Eun Jin Yang, and Sung-Ho Kang

The Arctic Ocean is facing dramatic environmental and ecosystem changes. To obtain the current baseline data, a coordinated multiship and multination pan-Arctic ship-based sampling campaign was implemented for the period between 2020 and 2022 under the project of Synoptic Arctic Survey (SAS). During the 2020 survey, unusually low dissolved oxygen and acidified water (salinity = 34.5) were found in a high-seas fishable area of the western (Pacific-side) Arctic Ocean. The data showed that the Beaufort Gyre (BG) shrunk to the east of the Chukchi Plateau (CP) and formed a front between the water within the gyre and the water from the eastern (Atlantic-side) Arctic. That phenomenon triggered a frontal northward flow along the CP. This flow likely transported the low oxygen and acidified water toward the high-seas fishable area; similar biogeochemical properties had previously been observed only on the shelf-slope north of the East Siberian Sea (ESS). Northward flows were also predominant west of the CP associated with the penetration of the water from the eastern Arctic. The northward flows would transport nutrient-rich shelf water (salinity = 32.5) from the ESS to the southwestern Canadian Basin (CB). Furthermore, the northeastward flow of the shrunk BG during the SAS period (2020-2022) could spread the nutrient-rich ESS shelf water to the northeastern CB. As a result, the nutrient concentration there during the SAS period was higher than the period when the BG enlarged to the west of CP, because the westward flow of the BG that overshot the CP inhibited the northward transport of the nutrient-rich ESS shelf water toward the southwestern CB. As a future study, we would like to combine the data from the Atlantic gateway because the ocean circulation and dissolved oxygen/nutrient distributions in the CB are largely influenced by the penetration of the water from the eastern Arctic. This is a reason why we have applied to present in this session.

How to cite: Nishino, S., Jung, J., Cho, K.-H., Williams, W., Fujiwara, A., Murata, A., Itoh, M., Watanabe, E., Hatta, M., Yamamoto-Kawai, M., Kikuchi, T., Yang, E. J., and Kang, S.-H.: Changes in ocean circulation and dissolved oxygen/nutrient distributions in the Canadian Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2699, https://doi.org/10.5194/egusphere-egu24-2699, 2024.

EGU24-3080 | Posters on site | OS1.1

No emergence of deep convection in the Arctic Ocean across CMIP6 models 

Céline Heuzé and Hailong Liu

As sea ice disappears, the emergence of open ocean deep convection in the Arctic, which would enhance ice loss, has been suggested. Here, using 36 state-of-the-art climate models and up to 50 ensemble members per model, we show that Arctic deep convection is rare under the strongest warming scenario. Only 5 models have convection by 2100, while 11 have had convection by the middle of the run. For all, the deepest mixed layers are in the eastern Eurasian basin. When the models convect, that region undergoes a salinification and increasing wind speeds; it is freshening otherwise. The models that do not convect have the strongest halocline and most stable sea ice, but those that lose their ice earliest -because of their strongly warming Atlantic Water- do not have a persistent deep convection: it shuts down mid-century. Halocline and Atlantic Water changes urgently need to be better constrained in models.  

How to cite: Heuzé, C. and Liu, H.: No emergence of deep convection in the Arctic Ocean across CMIP6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3080, https://doi.org/10.5194/egusphere-egu24-3080, 2024.

EGU24-3635 | Orals | OS1.1

Drivers of interannual salinity variability in the Arctic Ocean 

Antoine Hochet, Camille Lique, Florian Sévellec, and William Llovel

Accurate projections and attributions of Arctic ocean changes in climate models require a good understanding of the mechanisms underlying interannual salinity variability in the region. Although some mechanisms have been extensively studied in idealized settings, in particular for the dynamics of the Beaufort Gyre (BG), their applicability to the more complex system remains unclear. This study introduces a new diagnostic based on the salinity variance budget to robustly assess the mechanisms of salinity variations. The diagnostic is then applied to the Estimating the Circulation and Climate of the Ocean state estimate. 
The results indicate that the advection of salinity anomalies in the direction of the mean salinity gradient, produced by velocity anomalies is the primary source of interannual salinity variability. These velocities are primarily caused by fluctuating winds via Ekman transports.
Fluctuating surface freshwater fluxes from the atmosphere and sea ice are the second most important source of variability and cannot be neglected. The two sinks of interannual salinity variance are associated with the erosion of large-scale  mean circulation gradients by eddies and to a lesser extent to the diffusive terms. Over continental shelves, particularly over the East Siberian Shelf (ESS), ocean surface freshwater fluxes and diffusion play a more important role than in the deep basins.
We also report a strong intensification of all sources and sinks of interannual salinity variability in the BG and an opposite weakening in the ESS in the second decade of the analysis (2004-2014) with respect to the first (1993-2003). 

How to cite: Hochet, A., Lique, C., Sévellec, F., and Llovel, W.: Drivers of interannual salinity variability in the Arctic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3635, https://doi.org/10.5194/egusphere-egu24-3635, 2024.

EGU24-3752 | ECS | Posters on site | OS1.1

Latitudinal distribution of biomarkers across the western Arctic Ocean and the Bering Sea: an approach to assess sympagic and pelagic algal production 

Youcheng Bai, Marie-Alexandrine Sicre, Jian Ren, Vincent Klein, Haiyan Jin, and Jianfang Chen

The drastic decline of Arctic sea ice due to global warming and polar amplification of environmental changes in the Arctic basin profoundly alter primary production with consequences for polar ecosystems and the carbon cycle. In this study, we use highly branched isoprenoids (HBIs), brassicasterol, dinosterol and terrestrial biomarkers (n-alkanes and campesterol) in surface sediments to assess sympagic and pelagic algal production with changing sea-ice conditions along a latitudinal transect from the Bering Sea to the high latitudes of the western Arctic Ocean. Suspended particulate matter (SPM) was also collected in surface waters at several stations of the Chukchi Sea to provide snapshots of phytoplankton communities under various sea-ice conditions for comparison with underlying surface sediments. Our results show that sympagic production (IP25 and HBI-II) increased northward between 62°N and 73°N, with maximum values at the sea-ice edge in the Marginal Ice Zone (MIZ) between 70°N and 73°N in southeastern Chukchi Sea and along the coast of Alaska. They were consistently low at northern high latitudes (>73°N) under extensive summer sea-ice cover and in the Ice-Free Zone (IFZ) of the Bering Sea. Enhanced pelagic sterols and HBI-III occurred in the IFZ across the Bering Sea and in southeastern Chukchi Sea up to 70°N-73°N in the MIZ conditions that marks a shift of sympagic over pelagic production. In surface water SPM, pelagic sterols display similar patterns as Chl a, increasing southwards with higher amounts found in the Chukchi shelf pointing out the dominance of diatom production. Higher cholesterol values were found in the mid-Chukchi Sea shelf where phytosterols were also abundant. This compound prevailed over phytosterols in sediments, compared to SPM, reflecting efficient consumption of algal material in the water column by herbivorous zooplankton.

How to cite: Bai, Y., Sicre, M.-A., Ren, J., Klein, V., Jin, H., and Chen, J.: Latitudinal distribution of biomarkers across the western Arctic Ocean and the Bering Sea: an approach to assess sympagic and pelagic algal production, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3752, https://doi.org/10.5194/egusphere-egu24-3752, 2024.

EGU24-3959 | ECS | Posters on site | OS1.1

Arctic Wintertime Sea Ice Lead Detection from Sentinel-1 SAR Images 

Shiyi Chen, Mohammed Shokr, Lu Zhang, Zhilun Zhang, Fengming Hui, Xiao Cheng, and Peng Qin

Leads in sea ice cover are almost linear fractures within the pack ice, and are commonly observed in the polar regions. In winter, leads promote energy flux from the underlying ocean to the atmosphere. Synthetic aperture radar (SAR) can monitor leads with a fine spatial resolution, regardless of solar illumination and atmospheric conditions. In this paper, we present an approach for automatic sea ice lead detection (SILDET) in the Arctic wintertime using Sentinel-1 SAR images. SILDET is made up of four modules: 1) a segmentation module; 2) a balance module; 3) an optimization module; and 4) a mask module. The validation results presented in this paper show that SILDET has the capability of detecting open and frozen leads at different stages of freezing. The lead map obtained from SILDET was compared to a lead dataset based on Moderate Resolution Imaging Spectroradiometer (MODIS) data and validated by the use of Sentinel-2 images. This shows that SILDET can provide a more detailed distribution of leads and better estimation of lead width and area. Compared with visual interpretation of Sentinel-1 images, the overall detection accuracy is 97.80% and the Kappa coefficient is 0.88 (for all types). The pyramid scene parsing network (PSPNet) in the segmentation module shows a better performance in detecting frozen leads, compared with the deep learning methods of UNet and DeepLabv3+. The optimization module utilizing shape features also improves the precision in detecting frozen leads. SILDET was applied to present the Arctic lead distribution in January and April 2023 with a spatial resolution of 40 m. The Arctic-wide lead width distribution follows a power law with an exponent of 1.64 ± 0.07. SILDET can be expected to provide long-term high-resolution lead distribution records.

How to cite: Chen, S., Shokr, M., Zhang, L., Zhang, Z., Hui, F., Cheng, X., and Qin, P.: Arctic Wintertime Sea Ice Lead Detection from Sentinel-1 SAR Images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3959, https://doi.org/10.5194/egusphere-egu24-3959, 2024.

EGU24-4291 | ECS | Orals | OS1.1

Arctic sea ice drift fields extraction based on feature tracking to MODIS imagery 

Yan Fang, Xue Wang, Gang Li, Zhuoqi Chen, Fengming Hui, and Xiao Cheng

Moderate-resolution optical imagery holds great potential in deriving Arctic sea ice drift fields because of its higher resolution than microwave radiometers and scatterometers, as well as its larger swath widths than most other optical and synthetic aperture radar (SAR) images. However, the application of such imagery is hindered by cloud influences and a lack of texture. In this study, we propose a method of deriving Arctic sea ice drift fields based on applying feature tracking to Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. To enhance the quality of the feature tracking step, a bundle of digital image processing techniques is first introduced, including histogram equalization which is based on the Cumulative Distribution Function (CDF) of the sea ice area, and Laplacian filtering which enhances image texture. Various MODIS bands and A-KAZE parameter settings are subsequently compared to balance the quality of sea ice drifting fields and calculation efficiency. Three pairs of MODIS images observed in different zones of the Arctic Ocean are selected to evaluate the performance of the proposed method. International Arctic Buoy Programme (IABP) buoy data are employed for validating the derived drift vectors with MODIS imagery. The results show that our proposed method effectively increases the number of vectors and their coverage rates of the sea ice drift fields extracted with MODIS images. The coverage rates of sea ice drift fields in three regions increase from 4.8%, 2.3%, and 2.5% to 56.5%, 23.5%, and 53.0% compared to using the A-KAZE algorithm directly, respectively. The MAEs of the derived sea ice motion vectors are 707 m/d in speed and 6.4° in direction, superior to the sea ice drift products based on the Advanced Very High Resolution Radiometer (AVHRR) imagery. The proposed method enables MODIS and other medium-resolution optical data to be utilized in deriving Arctic sea ice drift fields, which is of great significance to the long-term and large-scale Arctic environment, climate, and oceanography research in the future. 

How to cite: Fang, Y., Wang, X., Li, G., Chen, Z., Hui, F., and Cheng, X.: Arctic sea ice drift fields extraction based on feature tracking to MODIS imagery, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4291, https://doi.org/10.5194/egusphere-egu24-4291, 2024.

EGU24-6019 | ECS | Orals | OS1.1

Variability in the Arctic Ocean currents during 1990-2100 

Xiaoyan Wei, Chris Wilson, Sheldon Bacon, and Benjamin Barton

The Arctic Ocean is changing rapidly due to climate change, with significant impacts on subpolar ocean dynamics and mid-latitude regional weather. By utilizing a global, 1/12 degree, ocean sea-ice model (NEMO-SI3), which is forced at its surface by an Earth System Model, UKESM1.1, and simulates from 1981 to 2100 under scenario SSP3-7.0, we will demonstrate significant differences in the spatial structure and energy spectrum of Arctic Ocean currents among the past, the present, and the future. We will then explore the implications of changes in Arctic Ocean currents on mass transport pathways within the Arctic and transport across its boundaries. Subsequently, our study will identify the dominant physical drivers of these changes, such as sea ice melting, freshwater discharge, wind stresses, surface heat fluxes, and tides.

How to cite: Wei, X., Wilson, C., Bacon, S., and Barton, B.: Variability in the Arctic Ocean currents during 1990-2100, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6019, https://doi.org/10.5194/egusphere-egu24-6019, 2024.

EGU24-6330 | Orals | OS1.1

Recent estimates of the sea ice volume and solid freshwater flux across the Arctic’s major export passageways 

Stephen Howell, David Babb, Jack Landy, and Mike Brady

Sea ice export from the Arctic Ocean is important to the ice mass balance and freshwater budget of the Arctic Ocean and the delivery of freshwater to the North Atlantic. Historically, estimates of the sea ice volume and solid freshwater flux across the Arctic’s major export passageways were temporally limited in terms of available ice thickness data together with low spatial resolution satellite derived sea ice motion data. However, observational advances now provide year-round estimates of ice thickness from CryoSat-2 and high spatiotemporal estimates of sea ice motion can be derived from Senitnel-1 and the RADARSAT Constellation Mission (RCM) synthetic aperture radar (SAR) satellites. In this presentation, we present the results of merging these datasets that provide new high-quality annual and monthly estimates of the sea ice volume flux across the Arctic’s major export passageways of Fram Strait, Nares Strait, Davis Strait and the Canadian Arctic Archipelago from 2016-2022. Over our study period, the annual average volume export at Fram Strait was 1586 km3 that agrees with its longer-term decline. The annual average volume export at Nares Strait and the Canadian Arctic Archipelago was 160 km3, and 43 km3, respectively that is in agreement with longer-term increases and indicates a divergent trajectory compared to Fram Strait. The annual average sea ice volume flux through Davis Strait was 816 km3, nearly double previous estimates. Annually, a total of 1912 km3 of solid freshwater was delivered to the North Atlantic from the passageways of Fram Strait and Davis Strait. Overall, our new high-quality estimates of these sea ice variables provide updated quantities for understanding recent changes in ice mass balance and freshwater budget of the Arctic Ocean and the freshwater balance of the North Atlantic, where overturning is critical to the global climate.

How to cite: Howell, S., Babb, D., Landy, J., and Brady, M.: Recent estimates of the sea ice volume and solid freshwater flux across the Arctic’s major export passageways, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6330, https://doi.org/10.5194/egusphere-egu24-6330, 2024.

The surface Arctic Ocean is subject to rapidly changing freshwater inputs, from increasing ice melt and riverine inputs. Close monitoring of inflow waters from the Pacific and Atlantic is also needed for understanding the balance of geochemical cycles and making future predictions in the Arctic.  However, our knowledge of ocean biogeochemical data is very limited, necessitating an expansion of spatial and temporal coverage. However, the acquisition of ocean samples is hindered by the intricate sampling and analytical procedures employed both at sea and on land.

In our recent work [Hatta et al, 2021; 2023], a miniaturized, automated, microfluidic analyzer for nutrient analysis was developed using the programmable flow injection (pFI) technique.  This innovative system achieves accurate measurements with minimal reagent use, computer-controlled manipulations, and auto-calibration techniques, thus it is a promising oceanographic tool for increasing sample acquisition and determination, as well as minimizing human error.  For the pFI technique, the traditional silicate (Si) molybdenum blue method was modified by combining oxalate and ascorbic acid into a single reagent. This new method obtained a limit of detection of 514 nM Si, r.s.d. 2.1%, sampling frequency rate of 40 samples per hour, reagent consumption of 700 microliters per sample, and use of deionized (DI) water as a carrier solution. Phosphate (P) does not interfere significantly in this technique if the Si:P ratio is 4:1 or larger. Additionally, since there is no salinity influence, samples collected from the open ocean, coastal areas, or rivers can all be determined accurately using a DI water-based standard calibration covering a single small range by diluting samples to fall within this limited range.

In this contribution, this new shipboard method using programmable Flow Injection will be presented along with high-resolution Si data from the Chukchi shelf.  These data were obtained every 10-20 minutes by directly connecting the pFI platform to the underway water sampling system during the RV Mirai summer cruises. This new analytical platform will allow us to significantly expand our database and thus help to constrain and quantify geochemical processes and budgets in the Arctic Ocean.

How to cite: Hatta, M., Davis, M., and Measures, C.: Surface silicate distribution in the Chukchi-shelf region during the Arctic summer cruises using programmable flow injection technique, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6998, https://doi.org/10.5194/egusphere-egu24-6998, 2024.

EGU24-7486 | Orals | OS1.1

Sea-ice lead dynamics in the Arctic Ocean and associated drivers 

Sascha Willmes, Günther Heinemann, and Michelle Rasic

Based on a novel sea-ice lead climatology derived from thermal-infrared satellite imagery we identify drivers of wintertime sea-ice dynamics in the Arctic Ocean. ERA-5 atmospheric reanalyses and large-scale sea-ice drift data are used to investigate the causes for prominent spatial patterns and for the inter-annual variability in the occurrence of sea-ice leads. We can show that large-scale atmospheric circulation patterns and the Arctic Oscillation determine where and to which extent leads form on weekly to monthly timescales. Events with strong lead openings can directly be associated with pronounced anomalies in wind divergence and sea-ice drift. We also show the dominant modes in the Arctic sea-ice lead variability and their relation to atmospheric circulation. Moreover, the role of ocean processes in shaping long-term spatial lead patterns in the Arctic Ocean is presented. Implications for sea-ice modelling, forecasts and future trends are discussed.

How to cite: Willmes, S., Heinemann, G., and Rasic, M.: Sea-ice lead dynamics in the Arctic Ocean and associated drivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7486, https://doi.org/10.5194/egusphere-egu24-7486, 2024.

EGU24-8264 * | Orals | OS1.1 | Highlight

Still Arctic? - The changing Barents Sea 

Sebastian Gerland, Randi B. Ingvaldsen, Marit Reigstad, Arild Sundfjord, Bjarte Bogstad, Melissa Chierici, Tor Eldevik, Haakon Hop, Paul E. Renaud, Lars H. Smedsrud, Leif Christian Stige, and Marius Årthun

The Barents Sea is one of the Polar regions where current climate and ecosystem change is most pronounced. In a recent review (DOI: 10.1525/elementa.2022.00088) as a part of the cross-disciplinary Norwegian research project “The Nansen Legacy”, the current state of knowledge of the physical, chemical and biological systems in the Barents Sea is described. Here, we present some of the key findings from this review. Physical conditions in this area are characterized by large seasonal contrasts between partial sea-ice cover in winter and spring versus predominantly open water in summer and autumn. Observations over recent decades show that surface air and ocean temperatures have increased, sea-ice extent has decreased, ocean stratification has weakened, and water chemistry and ecosystem components have changed. In general changes can be described as “Atlantification” and “borealisation,” with a less “Arctic” appearance. In consequence, only the northern part of the Barents Sea can be still called “Arctic”. The temporal and spatial changes have a wider relevance reaching beyond the Barents Sea, such as in the context of large-scale climatic (air, water mass and sea-ice) transport processes. The observed changes also have socioeconomic consequences, such as for fisheries and other human activities. Recent Barents Sea mooring data shows stronger inflow of warm water from the north during winter, affecting the sea ice locally. “The Nansen Legacy” has significantly reduced Barents Sea observation- and knowledge gaps, especially for winter months when field observations and sample collections have been sparse until recent.

How to cite: Gerland, S., Ingvaldsen, R. B., Reigstad, M., Sundfjord, A., Bogstad, B., Chierici, M., Eldevik, T., Hop, H., Renaud, P. E., Smedsrud, L. H., Stige, L. C., and Årthun, M.: Still Arctic? - The changing Barents Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8264, https://doi.org/10.5194/egusphere-egu24-8264, 2024.

EGU24-8828 | Posters on site | OS1.1

Changes of mesoscale eddy activity in the Eurasian Basin from 1-km simulations 

Vasco Müller, Qiang Wang, Nikolay Koldunov, Sergey Danilov, Xinyue Li, Caili Liu, and Thomas Jung

Mesoscale eddies play a crucial role in shaping the dynamics of the Arctic Ocean, making them essential for understanding future Arctic changes and the ongoing 'Atlantification' of the region. In this study, we use simulations generated by the unstructured-mesh Finite volumE Sea ice-Ocean Model (FESOM2) with a 1-km horizontal resolution in the Arctic Ocean.

Our investigation includes multiple simulations, namely a seven-year run representing the present-day climate and a slice simulation for the end of the 21st century, representative for a 4°C warmer world. Through these simulations, we evaluate changes in Eddy Kinetic Energy (EKE) within the Eurasian Basin and analyze their correlation with factors like sea-ice cover, baroclinic conversion rate, and stratification. To deepen our understanding, we combine Eulerian properties like EKE and baroclinic conversion rate with Lagrangian properties obtained from an algorithm that automatically identifies and tracks eddies using vector geometry.

Our findings from the end-of-century slice simulation indicate a significant increase in Arctic eddy activity in the future, accompanied by retreating sea ice. The present-day simulation reveals that the seasonality of EKE is mainly influenced by changes in sea ice, with distinct drivers at different depth levels for monthly anomalies. The mixed layer shows a robust connection to sea ice variability, while deeper levels, protected by stratification, are more significantly influenced by baroclinic conversion.

How to cite: Müller, V., Wang, Q., Koldunov, N., Danilov, S., Li, X., Liu, C., and Jung, T.: Changes of mesoscale eddy activity in the Eurasian Basin from 1-km simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8828, https://doi.org/10.5194/egusphere-egu24-8828, 2024.

EGU24-9183 | ECS | Orals | OS1.1 | Highlight

Thin Ice, Large Impact: Temporal and spatial trends of Arctic thermodynamic and dynamic sea ice thickness change 

Luisa von Albedyll and Robert Ricker

The Arctic Ocean's transition from perennial sea ice to more ice-free summers has halved sea ice thickness in the last six decades, significantly impacting the Arctic climate and ecosystem. Recent trends show a slowing in ice thickness and volume decline, prompting a need to investigate the underlying seasonal and long-term feedback mechanisms of sea ice thickness change. To do so, we use a Lagrangian drift-aware sea ice thickness product (DA-SIT), combined with extensive data on thermodynamic growth conditions and sea ice deformation, to quantify thermodynamic and dynamic thickness change in selected Arctic regions. A key focus is the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, which provided regional-scale analysis of seasonal sea ice thickness change using airborne ice thickness measurements, sea ice deformation, and in-situ snow and thermodynamic growth data. Our study extends these findings to larger temporal and spatial scales, evaluating their pan-Arctic applicability using long-term satellite datasets. We compare the MOSAiC trajectory with different dynamic regimes and ask how representative the conditions were for the “old” and the “new” Arctic. This analysis is key to understanding future sea ice thickness change, which is of great relevance for many climate and ecosystem processes.

How to cite: von Albedyll, L. and Ricker, R.: Thin Ice, Large Impact: Temporal and spatial trends of Arctic thermodynamic and dynamic sea ice thickness change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9183, https://doi.org/10.5194/egusphere-egu24-9183, 2024.

EGU24-9293 | Posters on site | OS1.1

Analyzing Mesoscale Eddy Impact on the West Spitsbergen Current in the Fram Strait 

Hwa Chien, Yen-Chen Chen, Huang-Meng Chang, Ke-Hsien Fu, and Bo-Shian Wang

Accelerated melting of Arctic sea ice, a consequence of global warming, is being exacerbated by increased freshwater inputs. This has led to a significant reduction in the halocline layer within the Fram Strait, enhancing ocean stratification and creating a feedback loop that further accelerates sea ice loss. This process is critical for the formation of North Atlantic Deep Water (NADW), where the West Spitsbergen Current (WSC) plays an essential role in recirculation.

Our study delves into the characteristics and influences of mesoscale eddies in the Fram Strait, particularly focusing on their impact on the WSC recirculation and NADW formation. Conducted over three years (2021-2023) during the months of minimal sea ice cover (August to October), the research involved deploying 36 specialized surface mini buoys across the strait. Analytical methods such as horizontal dispersion coefficients, finite-size Lyapunov exponents (FSLE), Lagrangian eddy identification, and sea surface temperature (SST) e-folding time were employed to assess WSC surface dynamics, eddy activities, and air-sea heat exchange.

Notably, we observed WSC bifurcation and intense mesoscale seawater mixing in the southwest Yermak Plateau and east of Molloy Deep (MD), areas marked by a rise in SST e-folding scale time gradient and considerable heat loss to the atmosphere (approximately 120 W/m²). Surface water convergence and sinking were detected near the western side of Molloy Deep and the Hovgaard (HG) regions, coinciding with high vorticity zones. Analysis of the buoy trajectories identified 682 eddy samples, forming the basis for a statistical examination of their size, period, intensity, and cyclonic features. This analysis was complemented by correlating eddy trajectories with sea surface height anomaly (SSHA) data, showing notable alignment.

Our results reveal a predominance of anticyclonic eddies in the Fram Strait, accounting for nearly 65% of the total eddies. Further, a consistency analysis between these eddies and wind stress curl indicated that about 66% of the anticyclonic eddies in the Molloy Deep region correlate with wind stress curl patterns, suggesting wind influence in their formation

How to cite: Chien, H., Chen, Y.-C., Chang, H.-M., Fu, K.-H., and Wang, B.-S.: Analyzing Mesoscale Eddy Impact on the West Spitsbergen Current in the Fram Strait, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9293, https://doi.org/10.5194/egusphere-egu24-9293, 2024.

EGU24-9304 | ECS | Orals | OS1.1

Distribution and characteristics of subsurface eddies in the Aleutian Basin, Bering Sea 

Kun Zhang, Haibin Song, and Linghan Meng

The subarctic Bering Sea, situated between the Pacific Ocean and Arctic Ocean, stands as one of the world's most productive oceanic regions. While the role of oceanic eddies in material transport and energy transfer has been extensively studied, surface eddies have dominated these investigations owing to advancements in remote sensing technology. Recently, attention has shifted to subsurface eddies for their influence on enhancing oceanic mixing. However, challenges persist in delineating the distribution and characteristics of subsurface eddies in the Bering Sea due to the limited effectiveness of satellite methods and the scarcity of field observation.

Multichannel seismic (MCS) data can provide high-resolution acoustic images of subsurface thermohaline fine structures, known as seismic oceanography. In this study, we integrate MCS with concurrent vessel-mounted Acoustic Doppler Current Profiles (vmADCP), expendable bathythermograph (XBT), and expendable Conductivity Temperature Depth (XCTD) data collected during cruise MGL1111, along with Argo and Copernicus Marine Service Global Ocean Physics Reanalysis data to investigate the distribution and characteristics of subsurface eddies in the Aleutian Basin.

The results underscore the presence of 44 subsurface eddies in the Aleutian Basin, primarily submesoscale with diameters averaging around 20 km. Eddy thickness spans 71.14 - 416.57 m, with eddy core depths ranging from 69.96 - 657.24 m, predominantly concentrated in the 100 - 200 m depth range; only 5 eddies exhibit core depths below 300 m. The cumulative volume of these eddies reaches approximately 434.38 × 109 m3, with the majority exhibiting anticyclonic characteristics, as corroborated by concurrent ADCP data. Analysis of historical CTD data, along with concurrent XBT and XCTD data from cruise MGL1111, delineates distinct water masses—Bering Sea Upper Water (BUW), Bering Sea Intermediate Water (BIW), and Bering Sea Deep Water (BDW)—in the study area. Most identified eddies are characterized as cold core, facilitating the transport of BIW. Trajectory assessments, incorporating concurrent Argo and Copernicus Marine Service Global Ocean Physics Reanalysis data, suggest an eastern and southern origin for these eddies, predominantly propagating westward. Assuming a propagating velocity of 1 cm/s, the estimated total transport of these eddies is approximately 1.76 Sv.

We believe that these findings will contribute essential insights to the fields of marine ecology, and climate studies, enhancing our knowledge of ocean dynamics in this critical region.

How to cite: Zhang, K., Song, H., and Meng, L.: Distribution and characteristics of subsurface eddies in the Aleutian Basin, Bering Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9304, https://doi.org/10.5194/egusphere-egu24-9304, 2024.

EGU24-9400 | ECS | Posters on site | OS1.1

Spatial and temporal distribution of all Arctic Polynyas since 1979 

Hau Man Wong, Céline Heuzé, Luisa Ickes, and Lu Zhou

Polynyas, open water regions within the sea ice cover, have been observed by satellites intermittently in the Arctic region over the past few decades. Their formation is complex, requiring various drivers to precondition and trigger the opening, which then influences local and regional weather significantly. Therefore, understanding Arctic polynyas’ spatial and temporal distribution is crucial to studying the polynyas’ impacts on climate. To date, most research is local and short-term, focusing on the major active Arctic polynyas or specific events; there is a need for pan-Arctic, long-term studies of all polynyas. Here, we use all available sea ice satellite data products to investigate all Arctic polynya events since 1979, in particular their locations for each day. The location preciseness and robustness are examined by sensitivity tests, varying the sea ice concentration (20 – 40%) and thickness (10 – 30 cm) thresholds. In the meantime, polynyas’ daily area extent, event duration, and recurrence are also obtained. The results indicate that the Franz-Josef Land, Eastern Kara Sea, and Nares Strait are the most active polynya formation-prone regions during wintertime. In addition, there is an increasing trend of polynya formation across the observation period. In future work, we plan to use the retrieved locations to determine whether thermodynamics or dynamic forcings contribute most to the Arctic polynyas’ opening.

How to cite: Wong, H. M., Heuzé, C., Ickes, L., and Zhou, L.: Spatial and temporal distribution of all Arctic Polynyas since 1979, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9400, https://doi.org/10.5194/egusphere-egu24-9400, 2024.

EGU24-10445 | ECS | Posters on site | OS1.1

Temporal and spatial variability of the oceanic front between the Atlantic Water and adjacent water masses north of Svalbard 

Stian Vikanes, Frank Nilsen, and Ragnheid Skogseth

The inflow of warm Atlantic Water (AW) into the Arctic Ocean is controlled by
oceanic fronts and air-ocean interactions north of Svalbard. The warm AW has
a significant impact on the sea ice extent and marine ecosystems in the region.
Therefore, it is crucial to understand the variability of the oceanic fronts offshore and
onshore of the AW, including their temporal and spatial characteristics, as well as
the mechanisms that govern them, such as atmospheric forcing, frontal instabilities,
and advection. However, our current understanding of the variability of these fronts
and AW north of Svalbard is limited due to lack of observational data. In this study,
we will use historical and more recent hydrographic data to analyze and describe
surface and subsurface fronts, both offshore and onshore of the AW core, in terms of
their dominant water masses along the continental slope north of Svalbard. We will
also determine the strength and position of these fronts by examining the horizontal
gradients in temperature, salinity, and density, and connect it to known changes in
the wind forcing.

How to cite: Vikanes, S., Nilsen, F., and Skogseth, R.: Temporal and spatial variability of the oceanic front between the Atlantic Water and adjacent water masses north of Svalbard, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10445, https://doi.org/10.5194/egusphere-egu24-10445, 2024.

The polar sea ice cover exhibits narrow bands of increased deformation, resulting in the formation of leads and pressure ridges. They are referred to as linear kinematic features (LKFs). They are important features of the sea ice field as they directly influence the heat and momentum exchange between ocean and atmosphere. By doing so, they influence the development of not only the sea ice cover but also the ocean and the local climate. Conversely, LKFs are also influenced by climate changes as the sea ice cover will be affected by changes in atmospheric and ocean temperature. In this work, the LKFs in the Arctic sea ice cover in current climate are compared to those in a warmer world. An LKF detection and tracking algorithm will be used to create a climate change signal. For this, the number of LKFs as well as their lifetimes are taken into account. The data analyzed in this work is created by the ocean-sea ice model FESOM. As LKFs are highly localized features, using a high spatial resolution is crucial. The resolution used in the analyzed runs is 1km. They span over five years starting at 2010, 2050, and 2090.

How to cite: Gärtner, J.: Detecting Linear Kinematic Features in Arctic Sea Ice in a Warmer World Using High Resolution Model Output, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10598, https://doi.org/10.5194/egusphere-egu24-10598, 2024.

EGU24-11226 | Posters on site | OS1.1

Weak signals of dense shelf water cascading in 2020 during a persisting phase of sporadic Atlantic water intrusions into the deep layer of the SW-Svalbard slope 

Patrizia Giordano, Manuel Bensi, Vedrana Kovacevic, Aniello Russo, and Leonardo Langone

The intensifying influence of warmer Atlantic Ocean waters in the Arctic, known as Arctic Atlantification, amplifies climate change effects by accelerating sea ice melting and altering ecosystems. Long-term data series are indispensable for discerning nuances in climate changes, especially when occurring in the deep ocean. They also provide a crucial temporal foundation for accurate modeling, useful to predict future scenarios and formulate effective strategies to address the challenges of climate change.

Here, we present oceanographic data collected from June 2014 to June 2023 at mooring site S1 (76°N, 14°E, 1040 m water depth), above the continental slope on the southwestern margin of Svalbard Archipelago (Fram Strait). There, the main branch of the West Spitsbergen Current transports Atlantic Water (in the upper layer) and Norwegian Sea Deep Water (below 900 m depth) poleward into the Arctic Ocean. Site S1 strategically lies at the convergence of Atlantic waters, the Arctic Ocean heat source, with waters from Storfjorden (Spitsbergen largest fjord) and shelf waters from the West Spitsbergen continental shelf. The oceanographic mooring S1 is part of the SIOS marine infrastructure network (Svalbard Integrated Arctic Earth Observing System, https://sios-svalbard.org/), and has undergone progressive instrument improvement over time, adding data collection at the intermediate layer since the summer 2022.

We focus on exploring short-term and seasonal variations in thermohaline properties, ocean currents, and particulate fluxes recorded in the deep layer over the last nine years. This analysis is undertaken in conjunction with meteorological conditions and trends in sea ice concentration. Oceanographic mooring data together with repeated Conductivity-Temperature-Depth (CTD) casts during summer surveys, show that the period 2014-2021 was characterized by the absence of dense shelf water exported at the near bottom on the slope, probably due to a limited production of dense water in the fjords, while the wind-induced vertical mixing and the resulting internal oscillations were probably favoured. During this period, a gradual decline in sea ice cover in winter is observed in the S1 area and adjacent fjords. The only exception is the winter 2020, when the sea ice extent returned apparently to pre-2013 levels, and at 1000m depth there were weak signals of cascading of dense shelf water, probably originated in the Storfjorden polynya.

Contrary to what is clearly evident in the literature regarding the increasing propagation of Atlantic waters northwards, temperature and salinity at mooring S1 showed no, or very little, positive trends over the investigated period. However, sporadic intrusions of relatively warm and saline water into the deep layer were observed. These occur most frequently in winter and are associated with the passage of internal waves that promote turbulent mixing of intermediate Atlantic waters with deep waters, facilitating the heat diffusion into the ocean depths.

How to cite: Giordano, P., Bensi, M., Kovacevic, V., Russo, A., and Langone, L.: Weak signals of dense shelf water cascading in 2020 during a persisting phase of sporadic Atlantic water intrusions into the deep layer of the SW-Svalbard slope, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11226, https://doi.org/10.5194/egusphere-egu24-11226, 2024.

EGU24-11917 | Orals | OS1.1 | Highlight

Atlantic Water warming increases melt below Northeast Greenland's last floating ice tongue 

Claudia Wekerle, Rebecca McPherson, Wilken-Jon von Appen, Qiang Wang, Ralph Timmermann, Patrick Scholz, Sergey Danilov, and Torsten Kanzow

Rising sea level poses a significant challenge and threat to our societies, given that coastal regions are densely populated. The Greenland ice sheet has been a major contributor to global sea level rise in the last decades, particularly its marine-terminating glaciers and their extensions into the ocean. The 79 North Glacier (79NG) features Greenland's largest floating ice tongue, stretching over 80 km in length in a 20 km wide fjord. The 79NG and its neighboring glacier, the Zachariæ Isstrøm, drain the Northeast Greenland Ice Stream which covers 12% of the Greenland Ice Sheet area. Its complete melt would lead to a 1.1-m global sea level rise. Though the extent of the 79NG has not changed significantly in recent years, observations have indicated a major thinning of its ice tongue from below.  Both ocean warming and an increase in subglacial discharge from the ice sheet induced by atmospheric warming could increase the basal melt; however, available observations alone cannot tell which of these is the main driver.

In this study, we present a setup of the Finite-volumE Sea ice-Ocean Model (FESOM2.1) which explicitly resolves the ocean circulation in the cavity of the 79NG with 700 m resolution. With this novel methodology, we seamlessly connect the global and regional ocean circulation to the circulation in the cavity. Our simulation with realistic bathymetry and ice shelf geometry covers the period 1970-2021, allowing us to disentangle the drivers of the upward trend and interannual variability of basal melt. We find that ocean warming in the subsurface Atlantic Intermediate Water layer that enters the cavity below the 79NG has played a dominant role in the basal melt rate over the past 50 years. The temperature variability can be traced back across the continental shelf of Northeast Greenland to the eastern Fram Strait with a lag of 3 years, implying a predictability of the basal melt of the 79NG. In contrast, subglacial discharge has a relatively small contribution to the interannual variation of the basal melt.

How to cite: Wekerle, C., McPherson, R., von Appen, W.-J., Wang, Q., Timmermann, R., Scholz, P., Danilov, S., and Kanzow, T.: Atlantic Water warming increases melt below Northeast Greenland's last floating ice tongue, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11917, https://doi.org/10.5194/egusphere-egu24-11917, 2024.

EGU24-12163 | ECS | Orals | OS1.1

Atlantification at the gateway of the Arctic Ocean over the last thousand years 

Francesco De Rovere, Angelo Rubino, and Davide Zanchettin

Atlantification is a major process driving rapid changes in the Arctic Ocean, e.g., sea-ice loss, warming and
salinification of the near-surface, enhanced mixing and changes in the ecosystem structure. The recent
scientific literature highlights the importance of the transport of Atlantic water as a cause of Atlantification,
but fundamental climatic processes driving this phenomenon are far from being fully understood.
Moreover, most studies focused on the analysis of recent observational data covering the last decades,
while recent studies showed that Atlantification had started in the 19th century.


In this contribution, we illustrate scope and progress of the Italian funded project “ATTRACTION: Atlantification dRiven by polAr-subpolar ConnecTIONs in a changing climate”. The project aims to provide a historical perspective on Atlantification by integrating observational evidence over the last decades, paleo-reconstructions and numerical paleoclimate simulations covering the past several centuries. We assess the capability of available tools to robustly describe coupled dynamics at the gateway of the Arctic Ocean (Fram Strait and Barents Sea), and their variations over multi-centennial periods. Furthermore, we provide a solid past reference for attribution of the ongoing Atlantification and discuss how paleoclimate simulations could support the identification of key locations for proxy-based reconstruction of the Atlantification. Toward a mechanistic understanding of Atlantification-like events over the last millennium, our assessment focus on the role of heat and salt redistribution by sub-polar dynamics by its major controls, including the Atlantic Multidecadal Overturning Circulation, the Sub-Polar Gyre and the Greenland Sea Gyre.

How to cite: De Rovere, F., Rubino, A., and Zanchettin, D.: Atlantification at the gateway of the Arctic Ocean over the last thousand years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12163, https://doi.org/10.5194/egusphere-egu24-12163, 2024.

EGU24-12174 | ECS | Posters on site | OS1.1

Feasibility of using C-band Synthetic Aperture Radar datasets for long term (1991-present) sea ice monitoring: towards multi-decadal analysis of sea ice type changes in the Atlantic sector of the Arctic Ocean 

Wenkai Guo, Anthony Paul Doulgeris, Johannes Lohse, Malin Johansson, Polona Itkin, Torbjorn Eltoft, Jack Landy, and Shiming Xu

We present a feasibility assessment of using several publicly available C-band wide-swath SAR datasets to derive sea ice type maps in the Atlantic sector of the Arctic Ocean from 1991 to present. This region is characterized by highly variable and dynamic sea ice conditions, and temporally consistent, large-scale monitoring of sea ice parameters is only possible through satellite remote sensing. We use data from C-band sensors including Sentinel-1, RADARSAT-2, Envisat ASAR and ERS-1/2, which have similar central frequencies and spatial resolution, to cover the study period. We evaluate comparative image classification performances and classification consistency using these datasets with common training datasets in geographically and temporally overlapping scenes and a sea ice classifier correcting for per-class incidence angle (IA) effects. Through this evaluation, we demonstrate the differences in these datasets affecting sea ice classification and the feasibility of using legacy sensors including Envisat ASAR and ERS-1/2 to extend the time series of sea ice type maps back to 1991 in our study area. This study provides theoretical support for the establishment of a multi-decadal SAR-based sea ice type product, which will contribute to the assessment of seasonal and inter-annual sea ice variations, especially the variability in new ice formation, which strongly influences physical and biogeochemical processes across the ocean-ice-atmosphere interface. This study is part of the collaborative project INTERAAC (air-snow-ice-ocean INTERactions transforming Atlantic Arctic Climate) between Norway and China, which aims at generating a reconciled multi-mission Climate Data Record (CDR) for Atlantic Arctic sea ice.

How to cite: Guo, W., Doulgeris, A. P., Lohse, J., Johansson, M., Itkin, P., Eltoft, T., Landy, J., and Xu, S.: Feasibility of using C-band Synthetic Aperture Radar datasets for long term (1991-present) sea ice monitoring: towards multi-decadal analysis of sea ice type changes in the Atlantic sector of the Arctic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12174, https://doi.org/10.5194/egusphere-egu24-12174, 2024.

In this study, we investigate the interannual variability of the sea ice area (SIA) in the Barents-Kara Sea (BKS) region. We explore the contributing factors to this variability, primarily focusing on oceanic influences evident in the Barents Sea Opening (BSO). The BSO, characterized by eastward warm Atlantic Water (AW) inflow, plays a crucial role in shaping the BKS SIA. While the inflow has been extensively studied, the westward-directed outflow known as Bear Island Slope Current (BISC), remains insufficiently observed. Being fed by relatively warm recirculating modified AW (mAW), the BISCs impact on the overall ocean heat transport (OHT) variability is uncertain.

 

Utilizing the global Finite Volume Sea Ice and Ocean Model (FESOM2.1), we derive estimates of the interannual volume transport and temperature variability of the BISC, filling the observational gap. We find that whereas the variability of BSO inflow/BISC volume transport is similar in magnitude, the temperature variability of the BISC exceeds the BSO inflow temperature variability. By linking the simulated BISC variability to BKS SIA, our findings reveal a yet unknown, strong co-variation between the volume transport of the BISC and the BKS SIA at the end of the freezing season, with a short lead time of zero to three months. We thus further examine the role of the BISC in generating interannual anomalies in the BKS SIA. Our model simulations illustrate that the volume transport of the BISC can be modified by the emergence of a secondary mAW recirculation downstream the northern AW path through the BS in the months preceding anomalously large BKS SIA. This secondary mAW recirculation is thereby increasing the volume transport of mAW leaving the BS via the BISC, reducing the amount of AW reaching the northern Barents Sea ice edge downstream. Additionally, we identify a connection between the atmospheric forcing pattern associated with the volume transport variability of the BISC and anomalous sea ice advection into the BKS as a second cause for the BISC volume transport/BKS SIA co-variability.

In general, our study emphasizes the co-variability between BKS SIA and the BISC. We highlight the role of the mAW recirculations in altering the amount of AW, and consequently ocean heat, reaching the ice edge in the northwestern Barents Sea.

How to cite: Heukamp, F. and Wekerle, C.: Variability of the Barents-Kara Sea Sea Ice Area and its Correlation with Atlantic Water Recirculation through the Barents Sea Opening, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12688, https://doi.org/10.5194/egusphere-egu24-12688, 2024.

EGU24-13067 | Orals | OS1.1 | Highlight

Intra- and interannual variability in the Atlantic Water inflow region north of Svalbard: sea ice, hydrography, nutrients and the potential for primary production 

Angelika Renner, Arild Sundfjord, Marit Reigstad, Allison Bailey, Øyvind Lundesgaard, Randi Ingvaldsen, Melissa Chierici, Elizabeth Jones, and Agnieszka Beszczynska-Möller

Atlantic Water (AW) is the major source of heat and nutrients to the Arctic Ocean. Changing AW inflow promotes sea ice decline and borealisation of marine ecosystems and affects primary production in the Eurasian Arctic. North of Svalbard, the AW inflow dominates oceanographic conditions along the shelf break and hence the distribution of heat and nutrients in the region. However, interaction with sea ice and Polar Surface Water determines nutrient supply to the euphotic layer. Using a combination of multidisciplinary approaches such as ship-based measurements and sampling, moored sensors, remote sensing and numerical modelling, we have been monitoring and studying the AW boundary current north of Svalbard since 2012. In this presentation, I will show some of our findings with particular focus on repeated measurements from a transect across the AW inflow at 31°E, 81.5°N. Large interannual variability in hydrography, nutrients and chl a indicates varying levels of nutrient drawdown by primary producers over summer. Sea ice conditions impact surface stratification, light availability, and wind-driven mixing, with a strong potential for steering chl a concentration over the productive season. In early winter, nutrient re-supply through vertical mixing varied in efficiency, again related to sea ice conditions. The autumn re-supply elevated nutrient concentrations sufficiently for primary production but likely happened too late as high-latitude light levels limited potential autumn blooms. Multidisciplinary observations are key to gain insight into the interplay between physical, chemical, and biological drivers and to understand ongoing and future changes. They are particularly important in regions like north of Svalbard that can indicate what we can expect in the central Arctic Ocean in the future.

How to cite: Renner, A., Sundfjord, A., Reigstad, M., Bailey, A., Lundesgaard, Ø., Ingvaldsen, R., Chierici, M., Jones, E., and Beszczynska-Möller, A.: Intra- and interannual variability in the Atlantic Water inflow region north of Svalbard: sea ice, hydrography, nutrients and the potential for primary production, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13067, https://doi.org/10.5194/egusphere-egu24-13067, 2024.

EGU24-13914 | ECS | Orals | OS1.1

Sea Ice Drift Retrieval based on Fengyun-3D Multi-Sensor Data 

Xue Wang, Zhuoqi Chen, Zhizhuo Xu, Ruirui Wang, Ran Lu, Fengming Hui, and Xiao Cheng

Under the background of global warming, sea ice changes rapidly. Sea ice drift is an important indicator for sea ice flux, atmospheric and ocean circulation, and ship navigation. Currently, the large-scale observed sea ice drift datasets are mainly obtained based on single-sensor remotely sensed data, which suffer low spatial resolution or poor spatial continuity. Considering that passive microwave radiometer and medium-resolution optical sensor complement each other in terms of spatial resolution and continuity, this study proposed a novel sea ice drift retrieval method based on Fengyun-3D (FY-3D) multi-sensor data. The proposed method is summarized as follows. First, low resolution sea ice drift fields were obtained from FY-3D Microwave Radiation Imager (MWRI) data based on the normalized cross-correlation pattern-matching method. Then, fine resolution vectors were extracted from FY-3D Medium-Resolution Spectral Imager (MERSI) data based on A-KAZE feature-tracking method. Finally, the low resolution pattern-matching vectors and fine resolution feature-tracking vectors were merged together based on Co-Kriging algorithm to obtain the final sea ice drift result. The proposed method was evaluated by comparing the buoy displacements obtained from the International Arctic Buoy Program (IABP) with the retrieved merged vectors from FY-3D remotely sensed images collected in the Beaufort Sea, the East Siberian Sea, and the Fram Strait on 2020. The results showed that the proposed method can retrieve accurate, fine resolution and spatial continuous sea ice motion fields.

How to cite: Wang, X., Chen, Z., Xu, Z., Wang, R., Lu, R., Hui, F., and Cheng, X.: Sea Ice Drift Retrieval based on Fengyun-3D Multi-Sensor Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13914, https://doi.org/10.5194/egusphere-egu24-13914, 2024.

EGU24-14215 | ECS | Posters on site | OS1.1

Potential of diatoms in sediments as seeds for autumn blooms in the Pacific Arctic shelf 

Yuri Fukai, Amane Fujiwara, Shigeto Nishino, Kohei Matsuno, and Koji Suzuki

The Pacific gateway to the Arctic has a vast continental shelf spanning the northern Bering and the Chukchi Seas. Within this shelf region, diatoms are crucial in sustaining high primary production and facilitating the sinking particulate organic carbon flux from spring to summer. Consequently, the bottom sediments have abundant viable diatoms, including resting stages. Despite the importance of diatoms, our understanding of the dynamics of this organism in sediments and their capacity to initiate primary production in the Pacific Arctic shelf remains limited.

In this study, we delved into the photophysiological capabilities of diatoms in the surface sediments collected from the Chukchi Sea in autumn through a laboratory incubation experiment at 3°C under the light conditions of 300 or 30 µmol photons m-2 s-1 for seven days. This experiment revealed that diatoms, mainly Chaetoceros, quickly resumed photosynthesis after light exposure and reached the maximum photosynthetic carbon fixation rates within only several days. These results suggest that diatoms in sediments have a significant potential to function as “seeds” for bloom formation in the sunlit water column. We further examined diatom communities, including resting spores, in the water column of the Chukchi Sea during autumn using scanning electron microscopy (SEM) and DNA metabarcoding techniques, as well as environmental parameters. Consequently, intense winds and subsequent water turbulence in the shallow Chukchi caused the predominance of Chaetoceros resting spores, probably derived from the sediments, in the diatom assemblages. As speculated from the incubation experiment mentioned above, diatom resting spores from the sediments can germinate immediately in the water column. Thus, settled diatoms could work as seeds for subsequent autumn blooms by being supplied from the seafloor along with nutrient-rich water.

The recent delayed sea ice formation in the autumn Arctic leads to increased storm occurrence over open water and enhanced vertical mixing, resulting in more frequent autumn blooms. Therefore, diatoms in sediments could be one of the critical contributors to autumn blooms in the shallow Pacific Arctic.

How to cite: Fukai, Y., Fujiwara, A., Nishino, S., Matsuno, K., and Suzuki, K.: Potential of diatoms in sediments as seeds for autumn blooms in the Pacific Arctic shelf, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14215, https://doi.org/10.5194/egusphere-egu24-14215, 2024.

EGU24-14505 | ECS | Posters on site | OS1.1

Winter to summer evolution of pCO2 in surface water of northern Greenland fjords  

Camille Akhoudas, Christian Stranne, Karl Adam Ulfsbo, Brett Thornton, and Martin Jakobsson

Ocean acidification induced by the absorption of anthropogenic CO2 and its consequences pose a potential threat to marine ecosystems around the globe. The Arctic Ocean, particularly vulnerable to acidification, provides an ideal region to investigate the progression and impacts of acidification before they manifest globally. Recent documentation of undersaturated surface waters in carbonate minerals in the Sherard Osborn fjord in northwest Greenland, a region visited for the first time in summer 2019, reveals inherent variability in biogeochemical processes. Associated with highly acidic surface waters, the partial pressure of CO2 (pCO2) was undersaturated relative to the atmosphere, indicating this study area as a CO2 sink. To comprehend variations in pCO2 in the northwest Greenland fjords and identify its drivers, we conducted a comparative study between two fjords in the region (Petermann and Sherard Osborn fjords) and used carbonate system data from the temperature minimum layer to examine the winter-to-summer evolution of pCO2 and influencing factors. Additionally, we evaluated pCO2 variations (δpCO2) concerning temperature, freshwater inputs, biological activity, and air-sea CO2 uptake to quantitatively assess the seasonal influencing factors on surface ocean pCO2. In the Sherard Osborn fjord, despite a substantial increase in surface temperature from winter to summer potentially increasing pCO2 and causing CO2 supersaturation relative to the atmosphere, freshwater inflow and biological activity reduced pCO2, resulting in CO2 undersaturation relative to the atmosphere. In the Petermann fjord, pCO2 remained lower than atmospheric levels due to a slight seasonal variation in surface temperature and significant biological activity, reducing pCO2 in surface water.

How to cite: Akhoudas, C., Stranne, C., Ulfsbo, K. A., Thornton, B., and Jakobsson, M.: Winter to summer evolution of pCO2 in surface water of northern Greenland fjords , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14505, https://doi.org/10.5194/egusphere-egu24-14505, 2024.

EGU24-15778 | Orals | OS1.1

Genesis and Decay of Baroclinic Eddies in the Seasonally Ice-Covered Arctic Ocean 

Gianluca Meneghello, John Marshall, Camille Lique, Pål Erik Isachsen, Edward Doddridge, Jean-Michel Campin, Heather Regan, and Claude Talandier

We explore the origin and evolution of mesoscale eddies in the seasonally ice-covered interior Arctic Ocean. Observations of ocean currents show a curious, and hitherto unexplained, vertical and temporal distribution of mesoscale activity. A marked seasonal cycle is found close to the surface: strong eddy activity during summer, observed from both satellites and moorings, is followed by very quiet winters. In contrast, subsurface eddies persist all year long within the deeper halocline and below.

We find that the surface seasonal cycle is controlled by friction with sea ice, dissipating existing eddies and preventing the growth of new ones. In contrast, subsurface eddies, enabled by interior potential vorticity gradients and shielded by a strong stratification at a depth of approximately 50 m, can grow independently of the presence of sea ice. 

We address possible implications for the transport of water masses between the margins and the interior of the Arctic basin, and for climate models’ ability to capture the fundamental difference in mesoscale activity between ice-covered and ice-free regions.

How to cite: Meneghello, G., Marshall, J., Lique, C., Isachsen, P. E., Doddridge, E., Campin, J.-M., Regan, H., and Talandier, C.: Genesis and Decay of Baroclinic Eddies in the Seasonally Ice-Covered Arctic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15778, https://doi.org/10.5194/egusphere-egu24-15778, 2024.

EGU24-16897 | Orals | OS1.1

Assessing changes in winter sea ice deformation – from MOSAiC to the Fram Strait 

Polona Itkin and Dmitry Divine

During winter, sea ice is moving in cohesive clusters of ice plates. These clusters – hereafter named ‘Coherent Dynamic Elements’ (CDE) are composed of several areas of deformed and level ice, that slide coherently along active sea ice fractures. The largest sea ice fractures detectable from medium resolution Synthetic Aperture Radar (SAR) satellites (about 50 m spatial resolution) are the Linear Kinematic Features (LKFs). Sea ice deformation information can be estimated from the strain rates in the LKFs and as well from the geometrical characteristics of the CDEs. However, there is a sudden seasonal transition, at the point where the sea ice warms and loses its internal strength. After this transition the delineation of LKFs and CDEs from SAR becomes challenging. In this contribution we will analyze sea ice deformation during the drift of the MOSAiC expedition from October 2019 to July 2020. During this time, the expedition drifted the entire length of the Transpolar drift from the northern Laptev Sea into the Fram Strait and the sea ice surrounding it underwent numerous deformation events. The MOSAiC sea ice deformation data and the onset of the melt period is compared to the data over the Fram Strait, where the sea ice deformation can was estimated from SAR and upward looking sonar devices on fixed moorings for the period of 2010-2023. We will present the data on the changes in the onset of the melt period and show that MOSAiC year was a typical year representative for the sea ice deformation of the recent decade.

How to cite: Itkin, P. and Divine, D.: Assessing changes in winter sea ice deformation – from MOSAiC to the Fram Strait, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16897, https://doi.org/10.5194/egusphere-egu24-16897, 2024.

EGU24-17166 | ECS | Orals | OS1.1

The Northeast Water Polynya, Greenland; Climatology, Atmospheric Forcing and Ocean Response 

Miriam Bennett, Ian Renfrew, David Stevens, and Kent Moore

The Northeast Water Polynya is a significant annually recurring summertime Arctic polynya, located off the coast of Northeast Greenland. It is important for marine wildlife and affects local atmospheric and oceanic processes. In this study, over 40 years of observational and reanalysis products (ERA5 and ORAS5) are analysed to characterise the polynya's climatology and ascertain forcing mechanisms. The Northeast Water Polynya has high spatiotemporal variability; its location, size and structure vary interannually, and the period for which it is open is changing. We show this variability is largely driven by atmospheric forcing. The polynya extent is determined by the direction of the near-surface flow regime, and the relative locations of high and low sea-level pressure centers over the region. The surface conditions also impact the oceanic water column, which has a strong seasonal cycle in potential temperature and salinity, the amplitude of which decreases with depth. The ocean reanalyses also show a significant warming trend at all depths and a freshening near the surface consistent with greater ice melt, but salinification at lower depths (~ 200 m). As the Arctic region changes due to anthropogenic forcing, the sea-ice edge is migrating northwards and the Northeast Water Polynya is generally opening earlier and closing later in the year. This could have significant implications for both the atmosphere and ocean in this complex and rapidly changing environment.

How to cite: Bennett, M., Renfrew, I., Stevens, D., and Moore, K.: The Northeast Water Polynya, Greenland; Climatology, Atmospheric Forcing and Ocean Response, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17166, https://doi.org/10.5194/egusphere-egu24-17166, 2024.

EGU24-18118 | Posters on site | OS1.1

Arctic Ocean simulations in two high-resolution coupled climate models 

Chuncheng Guo, Mats Bentsen, Aleksi Nummelin, Mehmet Ilicak, Alok Gupta, and Andreas Klocker

Large model spread and biases exist in simulating the Arctic Ocean water mass and circulations from the latest CMIP6 coupled and ocean-sea ice-only simulations. This can be at least partly attributed to large uncertainties due to unresolved key processes in this region, and it is hoped that high resolution can - to a certain extent - come to the rescue.

In this work, we first examined two high-resolution simulations by two CMIP6-class models: 1) a multi-centennial integration of CESM (CESM-HR; ocean resolution 1/10-deg), and 2) a 50-year integration of NorESM (NorESM-MX; ocean resolution 1/8-deg). The two models show clear signs of improvements in simulating the Arctic Ocean compared to their standard 1-deg resolution counterparts, but certain biases remain, such as the incorrect pathway of the Atlantic Water and the too-deep mixed layer depth in NorESM-MX.

We then performed and analysed a similar NorESM-MX simulation, but this time with a newly developed hybrid vertical coordinate (z-density) in the ocean model (the default is isopycnal/density coordinate). ​​Experience from hybrid coordinate testing runs in standard 1-deg resolution shows e.g. much-improved water masses and sea ice extent in the Southern Ocean, mixed layer depths, and importantly more rapid equilibration to energy balance in coupled simulations. When applied in the high-resolution NorESM-MX configuration, the results with the new coordinate show a much-improved representation of the pathway of Atlantic water and the distribution of mixed layer depth in the Arctic Ocean. 

How to cite: Guo, C., Bentsen, M., Nummelin, A., Ilicak, M., Gupta, A., and Klocker, A.: Arctic Ocean simulations in two high-resolution coupled climate models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18118, https://doi.org/10.5194/egusphere-egu24-18118, 2024.

EGU24-18702 | ECS | Posters on site | OS1.1

Observation of temporal and spatial variability of deep near-inertial waves in the western Arctic Ocean 

Chanhyung Jeon, Samuel Boury, Kyoung-Ho Cho, Eun-Joo Lee, Jae-Hun Park, and Thomas Peacock

Near‐inertial waves are waves propagating in the interior of the ocean. Created by surface storms, they have the potential to influence the ocean environment by inducing vertical mixing. Compared to other oceans, the Arctic Ocean has low near-inertial wave activity, but might be changing. It is a challenge, however, to predict near-inertial wave activity in the Arctic Ocean due to its intricate vertical salinity and temperature stratification. Our in-situ campaign has obtained the first direct deep current measurements revealing notable temporal and spatial variability of deep near-inertial waves in the western Arctic Ocean. These observations are an important step towards a clearer depiction of the evolving energy budget, and concomitant mixing, associated with potentially high impact near-inertial wave activity in an increasingly ice-free Arctic Ocean.

How to cite: Jeon, C., Boury, S., Cho, K.-H., Lee, E.-J., Park, J.-H., and Peacock, T.: Observation of temporal and spatial variability of deep near-inertial waves in the western Arctic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18702, https://doi.org/10.5194/egusphere-egu24-18702, 2024.

EGU24-18990 | Posters on site | OS1.1

Extreme sea ice motion -- analysis of ice drifter buoy data in the Gulf of Bothnia  

Henri Vuollekoski, Mikko Lensu, and Jari Haapala

Sea ice and particularly its motion are problematic for vessels and structures in water areas that experience sea ice. For example, several offshore wind farms are planned to be installed in the Gulf of Bothnia, but uncertainty related to extreme sea ice motion is likely to worry potential investors. Winter navigation, particularly in the coastal boundary zone, can be difficult. While climate change is likely to decrease the average ice concentration, extrema may become more severe. 

The motion of sea ice is affected by wind, currents and internal dynamics of the ice field, which are highly complex and inadequately understood. In this study we analyze time-series of data from ice drifter buoys deployed in the Gulf of Bothnia, Baltic Sea, during 2012 - 2023. The combination of data from multiple buoys, ice charts as well as other observations and model forecasts on the atmosphere-sea-ice interaction allows for estimating various parameters for the respective ice fields, such as shear, divergence and deformation, as well as temporal and spatial variability.

How to cite: Vuollekoski, H., Lensu, M., and Haapala, J.: Extreme sea ice motion -- analysis of ice drifter buoy data in the Gulf of Bothnia , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18990, https://doi.org/10.5194/egusphere-egu24-18990, 2024.

Currently freshwater anomaly is building up in the Beaufort gyre of the Arctic Ocean. There is a risk that this freshwater may discharge into the North Atlantic, disrupting the Atlantic Meridional Overturing Circulation (AMOC). Recent changes in Beaufort gyre size and circulation suggest this may occur soon or has already started: the North Atlantic has recently experienced its largest freshening for the last 120 years. In contrast, so far there is only limited evidence of Arctic fresh water impacting freshwater accumulation in the Labrador Sea. The North Atlantic is a region of high variability on interannual to decadal timescales, potentially affecting European and global climates.

The study focuses on changes in oceanic transports through the Arctic gateways under the Carbon Dioxide Removal (CDR) es-SSP5-3.4-ov CMIP6 emission–driven scenario 2015-2100 and analyses UKESM1 simulations. We examine historical and projected periods and compare the model results to the long-term observations in the key Arctic straits. The difference between the present-day and future model transports is in their partitioning between Fram Strait: in the future most of the Atlantic model inflow occurs via the Barents Sea (5.2 Sv northwards); model 2000-2020s and 2040-2090s Fram Strait transports are 2.4 Sv and 4.6 Sv southwards. It is worth noting that the observed Fram Strait volume transport estimates bear a large uncertainty, from 2.0±2.7 Sv southwards from moorings to 1.1±1.2 Sv from inverse modelling and 0.8 ±1.5 Sv from geostrophic analysis.

The model results show that during the increase of CO2 in the 2040s–2060s, the Beaufort Gyre is getting stronger, whereas the North Atlantic Subpolar Gyre (SPG) weakens. At the carbon dioxide removal phase (2060s–2090s) the Beaufort Gyre is strengthened while SPG weakened further. However, the cyclonic gyres in the Nordic Seas (Greenland, Iceland and Norwegian) become stronger. This points to a potential future change in the oceanic pathways between the Arctic and the North Atlantic. The corresponding heat transports due to overturning and gyres present different trends in the North Atlantic and the Arctic Ocean and different reversibility at latitudes between 26°N and 80°N, suggesting loss of immediate oceanic connectivity between the Atlantic and the Arctic via Nordic Seas. The simulations show a hysteresis in the AMOC: AMOC does not recover to the same level as before the mitigation even if the atmospheric CO2 concentration does.

Acknowledgement: We acknowledge funding from the EC Horizon Europe project OptimESM “Optimal High Resolution Earth System Models for Exploring Future Climate Changes”, grant 101081193 and UKRI grant 10039429, from the project EPOC “Explaining and Predicting the Ocean Conveyer”, EU grant 101059547 and UKRI grant 10038003, as well as from NERC highlight topics 2023 project “Interacting ice Sheet and Ocean Tipping - Indicators, Processes, Impacts and Challenges (ISOTIPIC)”. For the EU projects the work reflects only the authors’ view; the European Commission and their executive agency are not responsible for any use that may be made of the information the work contains.

How to cite: Aksenov, Y. and Rynders, S.: Transports through the Arctic gateways linked to the ocean gyres in the Carbon Dioxide removal (CDR) CMIP6 simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19583, https://doi.org/10.5194/egusphere-egu24-19583, 2024.

EGU24-19973 | ECS | Posters on site | OS1.1

Exploring links between Mixed-Layer depth and Sea Ice concentration variability in the Greenland Sea. 

Sonia Domingo, Joan Mateu Horrach, Alfredo Izquierdo, and Ángel Rodriguez

The Greenland Sea is a key player in the Atlantic Meridional Overturning Circulation (AMOC), crucial for forming dense waters through open-water convection and influencing global climate dynamics. Recent changes, such as decreasing sea ice concentration (SIC) and the shoaling of the mixed layer depth (MLD), have spurred detailed research into their impact on the AMOC. Our study, using the latest TOPAZ reanalysis, explores these changes from 1991 to 2021.

To strengthen our findings, we meticulously compare a 10-year observational dataset, validating TOPAZ's ability to reproduce processes like dense water formation and MLD evolution in the Greenland Sea. We find notable agreement, with the MLD reaching intermediate depths, and TOPAZ's overflow water density aligning with observations. Results show a decrease in SIC and a shallowing of the MLD, linked to rising surface water temperatures.

While our results indicate a similar trend, we're not ready to draw final conclusions. Further analysis is needed to understand how observational data compares to TOPAZ findings. Although reanalysis data provides valuable insights, it's crucial to validate everything with observational data. The comprehensive dataset and almost daily temporal resolution of our observational platforms significantly bolster the reliability of our conclusions.

Understanding Greenland Sea variability is vital not only for decoding its role in the AMOC but also for grasping broader implications for the global climate system. By highlighting the intricate relationship between SIC, MLD, temperature, and salinity, our research contributes to the ongoing dialogue on climate change dynamics.

 

How to cite: Domingo, S., Horrach, J. M., Izquierdo, A., and Rodriguez, Á.: Exploring links between Mixed-Layer depth and Sea Ice concentration variability in the Greenland Sea., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19973, https://doi.org/10.5194/egusphere-egu24-19973, 2024.

EGU24-20222 | ECS | Orals | OS1.1

Surface Controls of Freshwater Export through Denmark Strait  

Emma Boland, Yavor Kostov, and Dani Jones

Denmark Strait is a key route for the export of freshwater from the Arctic. Understanding the controls on the amount of freshwater entering the Subpolar North Atlantic is key for understanding the implications of rapid changes in the region, such as recent observed freshening of the Arctic Ocean. We present the results of an adjoint modelling study, which uses the ECCOv4 ocean state estimate to produce a reconstruction of the freshwater transport at Denmark Strait from 1992 to 2017. The reconstruction is formed of contributions from surface fluxes of buoyancy and momentum. We investigate the relative importance of these different contributions on different spatial and temporal scales. We find that surface wind stress at up to 2 years lag dominates variability. We also find a seasonally varying pattern in the dominant lags, with winter fluxes showing peak correlations with contributions from lags of up to 4 years, whereas spring fluxes showing a peak correlations on the scale of weeks.

How to cite: Boland, E., Kostov, Y., and Jones, D.: Surface Controls of Freshwater Export through Denmark Strait , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20222, https://doi.org/10.5194/egusphere-egu24-20222, 2024.

EGU24-20285 | Orals | OS1.1

Export of Greenland Sea Water across the Mohn Ridge as Measured by a Mooring during 2016–2018 

Jinping Zhao, Xusiyang Shen, and Tore Hattermann

Cold and dense water from the Greenland Sea, which has been found in the Lofoten Basin in the Norwegian Sea, is an important contributor to the Greenland–Scotland Ridge overflow, which feeds the deep and bottom waters in the North Atlantic. These two basins are divided by the Mohn Ridge, but there is no clear current connecting them. The aim of this study is to investigate how the Greenland Sea water enters the Lofoten Basin. We deployed a mooring on the western flank of the Mohn Ridge to measure the potential transport across the ridge during two periods: 2016/17 and 2017/18. The observation results indicate that the water above 1500 m in the Greenland Sea can be intermittently transported to the Lofoten Basin. In addition, we observed periods of flow reversal, which indicate bidirectional exchange between the two basins across the ridge. Our data from three consecutive seasons indicate that such inflows in August–September are a typical feature of the exchange across the Mohn Ridge. Net exports during these two periods into the Lofoten Basin were eltimated to be 5.86 Sv and 3.00 Sv, exhibiting noticeable interannual variations. We propose two possible mechanisms that could be driving the export. One is due to passing cyclones, which lower the sea level height along the Mohn Ridge and drive outflow. The second is due to the sudden weakening of the wind in summer, which results in outflow from the Greenland Sea through temporary geostrophic deviation.

How to cite: Zhao, J., Shen, X., and Hattermann, T.: Export of Greenland Sea Water across the Mohn Ridge as Measured by a Mooring during 2016–2018, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20285, https://doi.org/10.5194/egusphere-egu24-20285, 2024.

EGU24-20571 | Posters on site | OS1.1

A New Sea Ice Type Concentration Retrieval Algorithm from Microwave Remote Sensing Data 

Yufang Ye, Yanbing Luo, Mohammed Shokr, Zhuoqi Chen, and Xiao Cheng

Sea ice types, e.g., first-year ice (FYI) and multi-year ice (MYI), can be discriminated based on their radiometric and scattering signatures. However, changes in ice surfaces caused by factors such as ice deformation and melt-refreeze events can lead to extensive ice type misclassification. To solve this problem, a new sea ice type concentration (SITC) algorithm from microwave observations (SITCAM) is proposed in this study. It builds upon a previous algorithm, namely ECICE, but improves from two perspectives. Firstly, a new cost function is employed, with weights indicating the separation efficiencies of microwave parameters. Secondly, a pre-classification scheme is incorporated to account for the bimodal distributions in microwave characteristics. With SITCAM, daily Arctic SITCs are retrieved for the winters of 2002–2011 using passive (AMSR-E) and active (QuikSCAT and ASCAT) microwave data. The results are compared with a sea ice age product (SIA) and evaluated with ice type samples and SAR images. Overall, SITCAM performs well on mitigating the misclassifications induced by the aforementioned factors. The Arctic MYI area agrees well with that from SIA. Compared to ECICE, the retrieval accuracy for MYI and FYI samples increases to 96% and 90%, respectively (increasing by 5% and 15%, respectively), in SITCAM. The bias in MYI concentration between the SITC retrievals and SAR-based results has reduced from 15% to 4%. Furthermore, instead of being limited to specific observations (e.g., Ku-band scatterometer data), SITCAM performs well with various combinations of microwave data, even solely passive microwave data. This universality allows for a long-term record of SITC, which enables the potential of dating SITC back to late 1970s.

How to cite: Ye, Y., Luo, Y., Shokr, M., Chen, Z., and Cheng, X.: A New Sea Ice Type Concentration Retrieval Algorithm from Microwave Remote Sensing Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20571, https://doi.org/10.5194/egusphere-egu24-20571, 2024.

EGU24-1340 | ECS | PICO | NP5.3

The global interdependence patterns of extreme-rainfall events 

Zhen Su, Henning Meyerhenke, and Jürgen Kurths

As a powerful data-driven technology, the complex network paradigm has contributed significantly to the studies of spatio-temporal patterns of climate phenomena at different scales, such as El Niño–Southern Oscillation, Indian Ocean Dipole, and monsoon. In this work, we study the global extreme-rainfall patterns, which can potentially be used to improve the predictability of extreme events. The idea is to identify regions of similar extreme-rainfall patterns. For this, we propose a network-based clustering workflow which includes unsupervised learning. More precisely, this workflow combines consensus clustering and mutual correspondences. By applying this workflow to two satellite-derived precipitation datasets, we identify two main global interdependence structures of extreme rainfall, during boreal summer. These two structures are consistent and robust. From a climatological point view, they explicitly manifest the primary intraseasonal variability in the context of the global monsoon, in particular, the “monsoon jump” over both East Asia and West Africa, and the mid-summer drought over Central America and southern Mexico. We highlight the advantage of network-based clustering in (i) decoding the spatio-temporal patterns of climate variability and in (ii) the intercomparison of these patterns, especially regarding their spatial distributions over different datasets.

How to cite: Su, Z., Meyerhenke, H., and Kurths, J.: The global interdependence patterns of extreme-rainfall events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1340, https://doi.org/10.5194/egusphere-egu24-1340, 2024.

EGU24-6251 | ECS | PICO | NP5.3 | Highlight

An evolving network approach to assess compounding heat and dry extremes in Europe. 

Domenico Giaquinto, Giorgia Di Capua, Warner Marzocchi, and Jürgen Kurths

The probability of incidence of compound events is increasing due to human-induced climate change: in particular, there is high confidence that concurrent heatwaves and droughts will become more frequent with increased global warming1. Hereby, understanding the aggregated impact of multiple and synchronized compound hot and dry events at different spatial regions is a pressing issue, especially when it comes to predicting these extremes. In order to assess the evolution of these climate hazards, it is crucial to identify the synchronization structures of compound hot and dry events. To achieve this goal,  we highlight the hotspot regions where extremes are increasing and analyse the atmospheric precursors driving these anomalous conditions. Complex networks represent a promising tool in this perspective. In this work, we present an evolving network approach to assess the time evolution of synchronized compound hot and dry extremes due to global warming in continental Europe. Under this framework, we identify those regions where the frequency of these events has increased in the past 80 years and we describe their atmospheric drivers. Using ERA5 reanalysis data2 and focusing on the extended summer seasons (from April to September) of the period 1941-2020, we construct an evolving network constituted by 51 consecutive layers. Each layer models the synchronization structure in space of compound hot and dry events for a certain time window. Once the evolving network is established, the 51 layers are analysed to highlight the main changes in the graph structure. In particular, by looking at different centrality and clustering metrics and their evolution, we identify hotspot regions, and consequently we describe the atmospheric conditions which drive the compound events at these key locations. Climate complex networks prove to be a powerful tool to reveal hidden features of climate processes; this approach indeed brings out key aspects concerning the spatial dynamics of hot and dry events, laying the foundations to build a forecasting method for these extremes.

References

1) S.I. Seneviratne, X. Zhang, M. Adnan, W. Badi, C. Dereczynski, A. Di Luca, S. Ghosh, I. Iskandar, J. Kossin, S. Lewis, et al. Weather and climate extreme events in a changing climate; climate change 2021: The physical science basis. contribution of working group i to the sixth assessment report of the intergovernmental panel on climate change, 2021.

2) H. Hersbach, B. Bell, P. Berrisford, G. Biavati, A. Horányi, J. Muñoz Sabater, J. Nicolas, C. Peubey, R. Radu, I. Rozum, D. Schepers, A. Simmons, C. Soci, D. Dee, and J-N. Thépaut. Era5 hourly data on single levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS), 2023.

How to cite: Giaquinto, D., Di Capua, G., Marzocchi, W., and Kurths, J.: An evolving network approach to assess compounding heat and dry extremes in Europe., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6251, https://doi.org/10.5194/egusphere-egu24-6251, 2024.

EGU24-7007 | PICO | NP5.3

Fractional Integral Statistical Model: A new way for climate prediction and projection from the perspective of scaling 

Naiming Yuan, Christian Franzke, Da Nian, Zuntao Fu, Kairan Ying, Feilin Xiong, and Wenjie Dong

It is well recognized that climate memory is one the origins for climate predictability, but how to include the concept of climate memory into the climate prediction, is still an open question. Here in this work, we suggest the Fractional Integral Statistical Model (FISM), a generalized stochastic climate model, as a new way for this purpose. With FISM, one can extract the “forcing-induced direct component ε(t)” and the “memory-induced indirect component M(t)” from a given variable x(t). By predicting ε(t), one can further obtain the predicted x(t) using FISM. Different from traditional prediction approaches which normally focus on x(t), here this new strategy based on FISM clarifies the climate memory impacts. From this new perspective, we have quantified the climate memory induced predictability, and developed a temperature response model that can project the future warming trend. Compared to CMIP6 simulations, our approach projects lower global warming levels over the next few decades. A further examination indicates that many CMIP6 models overestimated the climate memory, which might contribute to the overestimated future warming trend.

How to cite: Yuan, N., Franzke, C., Nian, D., Fu, Z., Ying, K., Xiong, F., and Dong, W.: Fractional Integral Statistical Model: A new way for climate prediction and projection from the perspective of scaling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7007, https://doi.org/10.5194/egusphere-egu24-7007, 2024.

EGU24-10026 | PICO | NP5.3 | Highlight

Modeling the number of hospital admissions for malaria in South Africa by using climate variables as disease drivers 

Suzana Blesic, Milica Tosic, Neda Aleksandrov, Thandi Kapwata, and Caradee Wright

Recently we proposed a regression model for the number of hospital admissions for malaria in the Limpopo province of South Africa. We developed our model using the available weekly epidemiological reports from five districts in this province, in the period 2000-2020. We analyzed number of hospitalizations for malaria time series in relation to time series of temperature, rainfall and evaporation from bare soil ground or satellite data from the same geographical area and developed an algorithm that links combined changes in these three variables with the changes in number of malaria hospitalizations. We used wavelet spectral analysis to determine time lags in their cross-correlations.  

We used this model to provide projections for the Limpopo malaria cases for the next five years (2025-2029). Since there are no future projections available for evapotranspiration, we used three different methods to estimate future values of this variable in our model: 1) a combination of temperature and rainfall data, 2) use of total soil moisture content records and their projections, and 3) use of Hargreaves empirical formula. We will present and compare our results for all three cases.

Our calculations can be used for public health preparedness.  

How to cite: Blesic, S., Tosic, M., Aleksandrov, N., Kapwata, T., and Wright, C.: Modeling the number of hospital admissions for malaria in South Africa by using climate variables as disease drivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10026, https://doi.org/10.5194/egusphere-egu24-10026, 2024.

EGU24-12314 | ECS | PICO | NP5.3

Spatially coherent structure of forecast errors – A complex network approach 

Shraddha Gupta, Abhirup Banerjee, Norbert Marwan, David Richardson, Linus Magnusson, Jürgen Kurths, and Florian Pappenberger

The quality of weather forecasts has improved considerably in recent decades as models can better represent the complexity of the Earth’s climate system, benefitting from assimilation of comprehensive Earth observation data and increased computational resources. Analysis of errors is an integral part of numerical weather prediction to produce better quality forecasts. The Earth’s climate, being a highly complex interacting system, often gives rise to significant statistical relationships between the states of the climate at distant geographical locations. Likewise, correlated errors in forecasting the state of the system can arise from predictable relationships between forecast errors at various regions resulting from an underlying systematic or random process. Estimation of error correlations is very important for producing quality forecasts and is a key issue for data assimilation. However, the size of the corresponding correlation matrix is larger than what is possible to represent on geographical maps in order to diagnose its full spatial variation.

In this work, we propose an approach based on complex network theory to quantitatively study the spatiotemporal coherent structures of medium-range forecast errors of different climate variables. We demonstrate that the spatial variation of the network measures computed from the error correlation matrix can provide insights into the origin of forecast errors in a climate variable by identifying spatially coherent patterns of regions having common sources of error. Notably, the network topology of forecast errors of a climate variable is significantly different from those of random networks corresponding to a deterministic phenomenon which the model fails to simulate adequately. This is especially important to reveal the spatial heterogeneity of the errors – for example, the forecast errors of outgoing long-wave radiation in tropical regions can be correlated across very long distances, indicating an underlying climate mechanism as the source of the error. Additionally, we highlight that these structures of forecast errors may not always be directly derivable from the spatiotemporal co-variability pattern of the corresponding climate variable, contrary to the expectations that the patterns should resemble each other. We further employ other common statistical tools such as, empirical orthogonal functions, to support these findings. Our results underline the potential of complex networks as a very promising diagnostic tool to gain better understanding of the spatial variation, origin, and propagation of forecast errors.

 

How to cite: Gupta, S., Banerjee, A., Marwan, N., Richardson, D., Magnusson, L., Kurths, J., and Pappenberger, F.: Spatially coherent structure of forecast errors – A complex network approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12314, https://doi.org/10.5194/egusphere-egu24-12314, 2024.

EGU24-13178 | PICO | NP5.3

Reliable El Niño forecasting before the spring predictability barrier 

Josef Ludescher, Armin Bunde, and Hans Joachim Schellnhuber

The El Niño Southern Oscillation (ENSO) is the most consequential driver of interannual global climate variability and can lead to extreme weather events like drought or flooding in various parts of the world. Current operational forecasts are hampered by the so-called spring predictability barrier (SPB), which makes forecasts before or during the boreal spring particularly challenging. 

In recent years, we developed several methods based on complex system science that can provide reliable El Niño forecasts well before the SPB, thus about doubling the pre-warning time. The first of these methods is based on a dynamical climate network (CN) consisting of nodes that are reanalysis grid points in the Pacific, and links between them, whose strength is characterized by the cross-correlations of the atmospheric surface temperatures at the grid points. In the calendar year before an El Niño event, the links between the eastern equatorial Pacific and the rest of the tropical Pacific tend to strengthen such that the average link strength exceeds a certain threshold. This property serves as a precursor to forecast the onset of El Niño events. In particular, the CN-based method has already provided 12 real-time forecasts, 11 of which turned out to be correct (p = 5.1*10-3). Here, we discuss an improvement of the CN method as well as the combination with other El Niño forecasting methods. 

Approaches based on information entropy and the zonal temperature gradient in the western Pacific provide additional forecasts with about 1 year lead time for the magnitude and the type of an upcoming El Niño event, respectively. Combining the three methods provides not only more information about an upcoming El Niño, particularly about the risk exposure of a given geographical location, but concurring forecasts can support each other and lead to higher overall confidence in the forecast. This was the case, for instance, at the end of 2022, when the combined method correctly forecasted a moderate-to-strong El Niño of eastern Pacific type for 2023.  

How to cite: Ludescher, J., Bunde, A., and Schellnhuber, H. J.: Reliable El Niño forecasting before the spring predictability barrier, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13178, https://doi.org/10.5194/egusphere-egu24-13178, 2024.

We apply potential forecasting [1,2] to the WISE database that contains water accounts of European river basins [3]. We identify basins under stress and discuss various scenarios of water use. The complexity of water inflows and abstractions introduces sources of uncertainty that require analysis of geophysical, climatic, agricultural and social factors of water use, and this data represents an important case study for development of multivariate data science techniques. We report our findings and projections of hydrological dynamics in European regions.

[1] Livina et al, Physica A 2013

[2] Billuroglu & Livina, Journal of Failure Analysis and Prevention 2022

[3] WISE database, European Environmental Agency, https://www.eea.europa.eu/en/datahub

 

How to cite: Livina, V. N.: Potential forecasting of water accounts of European river basins, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14571, https://doi.org/10.5194/egusphere-egu24-14571, 2024.

EGU24-15381 | ECS | PICO | NP5.3 | Highlight

Understanding and predicting the spread of Phlebotomine sand flies in Europe 

Danyang Wang, Anouschka Hof, Kevin Matson, and Frank van Langevelde

Climate change influences the transmission of vector-borne diseases by affecting the distribution and survival of disease vectors. Numerous diseases are transmitted by phlebotomine sand flies (SFs), including Leishmaniasis. Several major sand fly-borne diseases (SFBDs) are responsible for high global disease burdens and high socio-economic costs. In Europe, 22 known SF vector species are largely confined to the Mediterranean Basin, yet global warming is predicted to drive the spread of SFs to large areas of Europe in the 21th century, an effect likely to be exacerbated by anthropogenic variables. However, the constraints to the geographic distributions of SFs are not well understood. This study aims to increase the understanding of the drivers of the spatial distributions of SFs. To achieve this, we use species distribution modelling (SDM) to assess the role of climate, land-use and socio-economic drivers in shaping the geographic distributions of all endemic SF vectors in Europe. With this knowledge, we predict future hotspots of SFs in Europe. Our predictions are spatially explicit, scenario-based, and informative for surveillance efforts.

How to cite: Wang, D., Hof, A., Matson, K., and van Langevelde, F.: Understanding and predicting the spread of Phlebotomine sand flies in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15381, https://doi.org/10.5194/egusphere-egu24-15381, 2024.

EGU24-17215 | ECS | PICO | NP5.3

Forecasting of Precipitation-Induced Landslides Using Atmospheric Rivers: Opportunities and Challenges 

Sara M. Vallejo-Bernal, Lisa Luna, Norbert Marwan, and Jürgen Kurths

Landslides are particularly costly disasters, causing about 4,500 fatalities and US$20 billion in damages worldwide each year. In Western North America, where intense and frequent precipitation events interact with complex topography and steep slopes, precipitation-induced landslides (PILs) are a serious geological hazard. Recently, it has been revealed that the majority of PILs in the region are triggered by precipitation from atmospheric rivers (ARs), transient channels of intense water vapor flux in the troposphere. However, the synoptic conditions differentiating landslide-triggering and non-triggering ARs remain unknown. In this study, we explore opportunities for improved landslide forecasting in Western North America using catalogs of land-falling ARs and PILs, along with ERA5 climatological data, from 1996 to 2018. First, we employ event synchronization, a non-linear measure specially tailored for event series analysis, to identify landslide-triggering ARs. Based on the AR-strength scale, which ranks ARs in levels from 1 to 5, we further characterize landslide-triggering ARs in terms of intensity and persistence. Subsequently, we spatially resolve the conditional probability of PIL occurrence given the detection of AR-attributed precipitation in the antecedent week, revealing the contribution of each AR level. Lastly, using hourly estimates of integrated water vapour transport, geopotential height, and precipitation at 0.25° spatial resolution, we differentiate the spatio-temporal evolution of synoptic conditions preceding landslide-triggering and non-landslide triggering ARs. Our results constitute a first, fundamental, and necessary step toward AR-based landslide forecasts, contributing crucial insights to improve forecasting accuracy at the short and early medium-range (1–7 days).

How to cite: Vallejo-Bernal, S. M., Luna, L., Marwan, N., and Kurths, J.: Forecasting of Precipitation-Induced Landslides Using Atmospheric Rivers: Opportunities and Challenges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17215, https://doi.org/10.5194/egusphere-egu24-17215, 2024.

Urban environments are especially sensitive to global warming due to their characteristic man-made surfaces and decreased vegetation cover. Elevated temperature in cities can facilitate the pole-wards expansion of arthropod disease vectors, including Phlebotomine sand flies (SFs). No study to date has yet been done to understand the effects of elevated urban temperatures on the distribution range shifts of SFs on continental scale. This study fills that gap and tests the role of urban heat island (UHI) in driving distribution range shifts of Phlebotomus perniciosus in Europe under two climatic scenarios. We find that P. perniciosus can occur more northly in summer due to UHI under both scenarios. Our study suggests that arthropod disease vectors can occur in cities where they are not expected due to UHI.

How to cite: Tak, V., Wang, D., and Matson, K.: The urban heat island effect aggravates the impact of climate change on the spatial distribution shifts of Phlebotomus perniciosus in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17798, https://doi.org/10.5194/egusphere-egu24-17798, 2024.

The recurrence of similar states is a fundamental property of the processes that shape and influence our living and non-living world. There are numerous examples of geological and climatic processes on both short and long time and spatial scales, such as the regular activity of geysers within minutes, the more irregular but still recurrent occurrence of earthquakes (on time scales between weeks and years), the El Niño climate phenomenon occurring every three to five years, the glacial cycles (thousands of years), or the Milanković cycles, which periodically force climate changes up to hundreds of thousands of years. The recurrence of states in such dynamic processes generates typical recurrence patterns that can be used to detect regime changes, to classify the dynamics, or even to predict future changes. I will report on recent achievements in recurrence analysis in recent years, including methodological developments tailored for challenging data in the geosciences, such as irregularly sampled data or extreme event data. The overview includes further important and innovative developments, such as conceptual recurrence plots, ideas for parameter selection, multiscale recurrences, correction schemes, and new perspectives by combining recurrence analysis with machine learning.

How to cite: Marwan, N.: Advances in Recurrence Analysis for Predictive Modeling and Dynamic Classification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21587, https://doi.org/10.5194/egusphere-egu24-21587, 2024.

EGU24-21913 | PICO | NP5.3

Predicting strong local wind with high-resolution nonhydrostatic numerical weather prediction model 

Vladimir Djurdjevic, Milica Tosic, and Irida Lazic

The nonhydrostatic multiscale model on the B grid (NMMB) was employed to forecast an episode of intense local Kosava wind in northeast Serbia. Kosava, a vigorously turbulent local wind, originates from the east or southeast near the Danube's "Iron Gate," moves westward over Belgrade, and then extends northward into the regions of Romania and Hungary. Typically attributed to a jet-effect wind within the narrow gorge of the "Iron Gate," it can reach maximum speeds exceeding 30 m/s. The NMMB model, with a horizontal resolution of 1.2 km, was utilized for the 2019 Kosava episode forecast. The high resolution, that surpasses the typical standards in numerical prediction models used by national meteorological services and other centers, can be crucial for accurately predicting strong wind gusts and capturing the specific dynamics and characteristics of the wind associated with the narrow gorge. The NMMB model results are compared with measured wind data and the results from models with lower resolutions.

How to cite: Djurdjevic, V., Tosic, M., and Lazic, I.: Predicting strong local wind with high-resolution nonhydrostatic numerical weather prediction model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21913, https://doi.org/10.5194/egusphere-egu24-21913, 2024.

CL3.2 – Future Climate – Climate and Society

EGU24-218 | Posters on site | CL3.2.1

Aligning climate scenarios to emissions inventories shifts global benchmarks 

Matthew Gidden, Thomas Gasser, Giacomo Grassi, Nicklas Forsell, Iris Janssens, William Lamb, Jan Minx, Zebedee Nicholls, Jan Steinhauser, and Keywan Riahi

Global mitigation pathways play a critical role in informing climate policies and targets that are in line with international climate goals. However, it is not possible to directly compare modelled results with national inventories used to assess progress under the UNFCCC due to differences in how land-based fluxes are accounted for.

National inventories consider carbon flux on managed land using an area-based approach with managed land-areas determined by nations. Emissions scenarios consider a different managed land area and are calibrated against data from detailed global carbon cycle models that account for natural (indirect) and anthropogenic (direct) fluxes separately by design. 

To disentangle the direct and indirect components of land-based carbon fluxes, we use a reduced complexity climate model with explicit treatment of the land-use sector, OSCAR, one of the models used by the Global Carbon Project. We find the discrepancy between model and NGHGI-based accounting methods globally to be 4.4 ± 1.0 Gt CO2 yr-1 averaged over the 2000-2020 time period, which is in line with existing estimates. We then apply OSCAR to the set of pathways assessed by the IPCC to quantify how this gap evolves over time and estimate how key mitigation benchmarks change.

Across both 1.5°C and 2°C scenarios, LULUCF emissions pathways aligned with NGHGI accounting practices show a strong increase in the total land sink until around mid-century. However, the ‘NGHGI alignment gap’  decreases over this period, converging in the 2050-2060s for 1.5°C scenarios and 2070s-2080s for 2°C scenarios. The convergence is primarily a result of the simulated stabilization and then decrease of the CO2-fertilization effect as well as background climate warming reducing the overall effectiveness of the land sink, which in turn reduces the indirect removals considered by NGHGIs. These dynamics lead to land-based emissions reversing their downward trend in most NGHGI-aligned scenarios by mid-century, and result in the LULUCF sector becoming a net-source of emissions by 2100 in about 25% of both 1.5°C and 2°C scenarios.

Assessing emission pathways using LULUCF definitions from national inventory accounting results in downward revisions to emissions benchmarks derived from scenarios. NGHGI-aligned pathways result in earlier net-zero CO2 emissions by around 2-5 years for both 1.5°C and 2°C scenarios, and 2030 emission reductions relative to 2020 are enhanced by about 5 percentage points for both pathway categories. When incorporating the additional land removals considered by NGHGIs, the assessed cumulative net CO2 emissions to global net-zero CO2 also decreases systematically by 15-18% for both 1.5°C and 2°C scenarios.

We find that increasing removals from direct fluxes in 1.5C scenarios overtake estimated removals using NGHGI conventions in the near term. However, by midcentury, the strengthening of direct removals is balanced by weakening of indirect removals, meaning that, on average, carbon removal on land accounted for using NGHGI conventions in 1.5C scenarios results in about half of the LULUCF removals in current policy scenarios. 

We discuss the implications of our results for future Global Stocktakes and market mechanisms under the Paris Agreement.

How to cite: Gidden, M., Gasser, T., Grassi, G., Forsell, N., Janssens, I., Lamb, W., Minx, J., Nicholls, Z., Steinhauser, J., and Riahi, K.: Aligning climate scenarios to emissions inventories shifts global benchmarks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-218, https://doi.org/10.5194/egusphere-egu24-218, 2024.

EGU24-1645 | ECS | Posters on site | CL3.2.1

Spatial analysis of CDR implications for global biodiversity refugia 

Ruben Prütz, Joeri Rogelj, Sabine Fuss, Jeff Price, Nicole Forstenhäusler, Rachel Warren, Andrey Lessa Derci Augustynczik, Petr Havlík, and Florian Kraxner

Background: Due to ongoing delays in deep global emission reductions, and as more and more countries set national net-zero CO2 targets, carbon dioxide removal (CDR) is continuously gaining importance and attention. Virtually all Paris-aligned AR6 mitigation pathways imply gigatonne-scale CO2 removal even before mid-century, with further upscaling thereafter. Integrated assessment models, used to explore the solution space, currently primarily rely on removals via bioenergy with carbon capture and storage (BECCS) and afforestation, which require massive amounts of land to meet scenario-implied removal scales. This substantial land demand is expected to have severe consequences for biodiversity, which could limit the sustainable scaling potential of these CDR options. Meanwhile, depending on the mode of implementation, afforestation could theoretically benefit habitat conservation in some cases, easing the immense pressure on biodiversity due to ongoing global warming and deforestation.

Objective: By combining spatially-resolved data on biodiversity refugia with spatial time series data from the Global Biosphere Management Model (GLOBIOM) on bioenergy crop plantations and afforestation under different mitigation scenarios, we estimate and compare land use and warming-related pressure on remaining global biodiversity refugia. We compare different biodiversity recovery assumptions after peak warming, consider the land use pressure of ongoing deforestation, and explore additional warming-related refugia loss when excluding CDR from scenarios.

Preliminary results: We show how scenarios with more ambitious temperature outcomes result in higher land use-related pressure on remaining biodiversity refugia areas as more land-intensive CDR is implied in such pathways. Meanwhile, more decisive climate action, including more CDR, substantially reduces the warming-related loss of remaining biodiversity refugia areas. The underlying biodiversity recovery assumptions strongly impact the degree of warming-related refugia loss with considerably less influence on land use-related implications. Generally, the perceived trends are stronger towards 2100 compared to mid-century.

How to cite: Prütz, R., Rogelj, J., Fuss, S., Price, J., Forstenhäusler, N., Warren, R., Derci Augustynczik, A. L., Havlík, P., and Kraxner, F.: Spatial analysis of CDR implications for global biodiversity refugia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1645, https://doi.org/10.5194/egusphere-egu24-1645, 2024.

EGU24-3169 | ECS | Orals | CL3.2.1

Heat impacts during days and nights under climate overshoot: a single hazard multi-impact approach 

Chahan M. Kropf, Kam Lam Leung, and Jamie W. Mc Caughey

Heat stress is a significant threat to human health and well-being, particularly in urban areas, and is expected to worsen in the future due to climate change. This study investigates the impacts of heat stress on human health in Lisbon, Portugal, during both days and nights under climate overshoot scenarios. The study employs a single hazard multi-impact approach to assess the health impacts of heat stress, considering both acute and long-term effects. The results show that the impacts of heat stress on human health are unequally distributed across the population, with some parishes being more affected than others. The study also finds that the impacts of heat stress will increase dramatically under current climate policies. In the daytime, heat stress is primarily driven by heat waves and maximum temperatures, leading to acute effects on human health, such as mortality. These effects are most pronounced in certain parishes and are expected to increase significantly even by 2040. Behavioural adaptation strategies such as adapting working hours have some potential to reduce heat impacts in certain settings. At night, heat stress is primarily driven by minimum daily temperatures, leading to sleep loss and long-term effects on health. Adaptation options for mitigating these impacts might require infrastructure investments. These findings highlight the need for targeted adaptation strategies to address the unequal distribution of heat stress impacts even under climate overshoot.

How to cite: Kropf, C. M., Leung, K. L., and Mc Caughey, J. W.: Heat impacts during days and nights under climate overshoot: a single hazard multi-impact approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3169, https://doi.org/10.5194/egusphere-egu24-3169, 2024.

EGU24-5361 | ECS | Posters on site | CL3.2.1

Implications of biosphere variability for future emission budgets and carbon dioxide removal 

Tom Schürmann, Moritz Adam, and Kira Rehfeld

The biosphere’s first-order response to changing Earth system conditions shifts under future emission pathways. One can anticipate such low-order responses, like rebounding carbon stocks once emissions diminish when forecasting emission budgets. However, the impact of changes in second- and higher-order biosphere variability on emission pathways and the prospective large-scale artificial carbon dioxide removal (CDR) remains unclear. An example of such higher-order responses is the vulnerability of land carbon uptake to more extreme climate forcing. In addition, implementing CDR has notable implications for land use, exerting an influence on spatial and temporal biosphere variability. Thus, constraining the interplay between the biosphere’s variability and the emission pathway could inform future emission accounting.

Here, we leverage state-of-the-art Earth system model simulations to investigate the magnitude and pathway-dependency of interactions between the terrestrial biosphere’s variability and the emission pathway. We characterize biosphere variability under different emission scenarios and with varying degrees of representing CO2 removal. The emission- and concentration-driven simulations cover pathways that reach Paris targets without and with temperature overshoot. CDR is either implicitly represented in emission and land use scenarios or explicitly simulated in the model’s land component to match the respective socio-economic pathway.

To understand the structure of modeled biosphere variability under the different pathways and test the consistency of the joint model system, we investigate regional events like a vegetation expansion event in the Northern Sahara. Here, the objective is to examine the interplay between terrestrial carbon fluxes and CDR utilization in detail on a smaller scale, later expanding to the global level. The following research focuses on identifying and quantifying shifts in biosphere variability over time, their interplay with CDR measures, and their effects on global carbon stocks. We test the model’s sensitivity to design choices (how and where CDR is represented) and pathway (emission target, timing, and duration of temperature overshoot). To this end, we aim to infer the margin of error biosphere variability could cause in emission accounting. Our results will help to evaluate the significance of varying biospheric carbon fluxes for future emission stock-taking in the context of CDR.

How to cite: Schürmann, T., Adam, M., and Rehfeld, K.: Implications of biosphere variability for future emission budgets and carbon dioxide removal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5361, https://doi.org/10.5194/egusphere-egu24-5361, 2024.

EGU24-5522 | Posters on site | CL3.2.1 | Highlight

What does Net Zero mean for reactive gases? 

William Collins

The decrease in carbon dioxide concentrations following a zeroing of emissions leads to a cooling that approximately balances the hidden warming from past emissions, due to the similarity of the timescales of climate response and carbon cycle response. But what are the climate implications of zero emissions of chemically-reactive gases such as nitrous oxide, halocarbons and methane with response timescales that don’t align with those of the climate system?

In this work we invert the analytical formulae used by the IPCC to represent the evolution of climate, to derive the time evolution of radiative forcing needed to stabilise temperatures. We find that stabilising the warming attributable to any gas requires decreases in radiative forcing that depend on the past history of that gas (more rapid historical ramp-up requires stronger future mitigation). We show that for reactive gases the analytically-derived radiative forcing decreases are most closely matched by step-like cuts in emissions, but that even for long-lived gasses such as nitrous oxide the emissions cuts do not need to be 100%. N2O emission cuts of 60-80% are sufficient to stabilise its temperature contribution - depending on the previous emission history.

It has been suggested that a more ambitious goal is to mitigate reactive gases sufficiently that their contribution to temperatures reduces rather than stabilises. We show that the above methodology can equally be applied to a declining temperature profile and so were are able to quantify the cuts in reactive gas emissions consistent with achieving desired cooling goals.

How to cite: Collins, W.: What does Net Zero mean for reactive gases?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5522, https://doi.org/10.5194/egusphere-egu24-5522, 2024.

EGU24-5598 | ECS | Orals | CL3.2.1

Carbon dioxide removal: trade-offs and lags in large perturbed parameter simulations 

Aurich Jeltsch-Thömmes, Giang Tran, Sebastian Lienert, David Keller, Andreas Oschlies, and Fortunat Joos

Carbon Dioxide Removal (CDR) is now widely discussed for offsetting residual greenhouse gas emissions or even reversing climate change. For example, all emissions scenarios of the Intergovernmental Panel on Climate Change that meet the “well below 2°C” warming target of the Paris Agreement include CDR. Ocean alkalinity enhancement (OAE) may be one possible CDR where the carbon uptake of the ocean is increased by artificial alkalinity addition. Here, we apply the Bern3D-LPX and the UVic Earth system models of intermediate complexity in observationally-constrained large perturbed parameter ensembles to investigate the effect of massive OAE on modelled carbon reservoirs and fluxes. OAE is assumed to be technically successful and deployed as an additional CDR in the SSP5-3.4 temperature overshoot scenario. 

Trade-offs involving feedbacks with atmospheric CO2 result in a low efficiency of an alkalinity-driven atmospheric CO2 reduction of -0.35 [-0.37 – -0.33] mol C per mol alkalinity addition (skill-weighted mean and 68% c.i.). The alkalinity-driven ocean carbon uptake is partly offset by the release of carbon from the land biosphere and a reduced ocean carbon sink in response to lowered atmospheric CO2 under OAE.
We further apply the Bern3D-LPX ensemble in idealized simulations, in which ΔSAT increases first to ~2°C and then declines to ~1.5°C, to investigate lags in surface air temperature change (ΔSAT). In these simulations, ΔSAT lags the decline in CO
2-forcing by decades, depending on the equilibrium climate sensitivity of the respective ensemble member.
Finally, we use the Bern3D-LPX ensemble simulations and the, in comparison to earlier studies with the Bern3D-LPX model, updated and longer observational records to assess climate metrics such as the transient climate response to emissions, the transient climate response, and the equilibrium climate sensitivity.
 

Our results suggest that massive OAE, if technically and socio-economically achievable, might be able to lower atmospheric CO2 but considering the trade-offs and lags, not emitting carbon is preferable. 

How to cite: Jeltsch-Thömmes, A., Tran, G., Lienert, S., Keller, D., Oschlies, A., and Joos, F.: Carbon dioxide removal: trade-offs and lags in large perturbed parameter simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5598, https://doi.org/10.5194/egusphere-egu24-5598, 2024.

EGU24-7147 | ECS | Posters on site | CL3.2.1

The variability determining the initial conditions for ensemble spread in the ZEC (CESM2) scenario 

Hyun Seung-Hwon and An Soon-Il

In this study, we analyze the results of a multiple ensemble experiment using a single model (CESM2) for the Zero Emission Commitment (ZEC) scenario, where atmospheric CO2 emissions are initially increased as in a warming scenario and then reduced to zero. We found a significant increase in the ensemble spread of global temperature during the Zero Emission period following the warming phase. 
Ensembles which initially have the relatively higher salinity in the North Atlantic during the early Zero Emission period show the higher North Atlantic temperatures and salinity, along with less Arctic sea ice distribution, in later (ZEC) periods. Conversely, ensembles with initially lower salinity displayed opposite characteristics. We propose that the initial conditions of the Zero Emission period are associated to long-period internal variability that occurred during the previous period of positive CO2 emission fluxes (the warming period). The increase in ensemble spread in the Northern Atlantic is due to the the Atlantic Meridional Overturning Circulation (AMOC) salinity feedback becoming elongated due to strong ocean stratification. This suggests a prolonged period for this feedback mechanism, associated with the internal variability in AMOC.

How to cite: Seung-Hwon, H. and Soon-Il, A.: The variability determining the initial conditions for ensemble spread in the ZEC (CESM2) scenario, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7147, https://doi.org/10.5194/egusphere-egu24-7147, 2024.

EGU24-7826 | ECS | Posters on site | CL3.2.1

How can overshoot risks be included in long-term adaptation planning? 

Emily Theokritoff, Burcu Yesil, Inga Menke, Mariam Saleh Khan, Inês Gomes Marques, Tiago Capela Lourenço, Hugo Pires Costa, and Carl-Friedrich Schleussner

As climate change intensifies, it is essential to take a wide range of climate scenarios and their consequential impacts into account for adaptation planning. Overshoot scenarios, during which global warming will temporarily exceed the 1.5°C Paris Agreement target before it is brought down again in the following decades, are increasingly likely under current emissions trajectories. They would result in complex risks such as limits to adaptation and irreversible impacts and stress the need to prepare long-term adaptation plans under deep uncertainty.

Here, we introduce the latest version of the Overshooting Proofing Methodology, a self-assessment tool designed to guide adaptation planners and policy-makers to integrate overshoot risks into planning processes, and present novel insights from its application with key stakeholders at city and regional levels. We also reflect on how adaptation pathways can allow to adequately plan a sequence of adaptation measures over time based on information collected through this tool. Its initial implementation in selected cities/regions reflects its applicability in varied climatic settings together with a range of climate related challenges. This work provides insights on key data gaps, capacity building needs and avenues for future adaptation planning, policy-making and research.

How to cite: Theokritoff, E., Yesil, B., Menke, I., Saleh Khan, M., Gomes Marques, I., Capela Lourenço, T., Pires Costa, H., and Schleussner, C.-F.: How can overshoot risks be included in long-term adaptation planning?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7826, https://doi.org/10.5194/egusphere-egu24-7826, 2024.

EGU24-10449 | Orals | CL3.2.1

Can ambitious forestation mitigate temperature overshoot? 

Yiannis Moustakis, Tobias Nützel, Hao-Wei Wey, and Julia Pongratz

Even though it has been estimated that country-level commitments on Afforestation/Reforestation (AR) are quite ambitious, amounting globally to 633Mha by 2060, typically modelling studies either apply only moderate levels of AR or are fully idealized, thus not taking into account technoeconomic and biodiversity considerations. Typically, high-end emission trajectories are also employed, yielding strong fertilization of vegetation by elevated CO2 levels and thus enhanced terrestrial carbon stocks, while the CDR potentials over more strongly mitigated pathways remain understudied. This is especially the case for overshoot pathways that are gaining research interest recently, given their relevance for reaching the more ambitious 1.5oC goal.

Here, with the fully coupled MPI-Earth System Model we investigate the mitigation potential of an ambitious yet spatiotemporally plausible AR scenario under an overshoot emission trajectory (SSP5-3.4os). The developed AR scenario employed here is commensurate with country commitments in 2060 and extends to 2100 reaching 935 Mha globally and is constrained by technoeconomic considerations based on a multitude of 1,259 Integrated Assessment Model-generated pathways. To further constrain the scenario, we consider biodiversity and restoration priority maps.

Based on a big ensemble member approach allowing for robust probabilistic analysis, our results demonstrate that ambitious AR can robustly mitigate global temperature in 2100 by 0.2oC, peak temperature by 0.09oC, and reduce temperature overshoot duration by 13 years, while also delaying the land carbon sink-to-source transition by ~10 years, compared to a reference scenario with constant land-use at 2015 levels. Temperature mitigation emerges also at the local scale, where biogeochemically-induced cooling compensates for any biogeophysically-induced local warming.

Overall, ambitious AR should be considered as a useful mitigation tool complementary to drastic emissions reduction even under more strongly mitigated pathways, despite potentially weaker CO2 fertilization.

How to cite: Moustakis, Y., Nützel, T., Wey, H.-W., and Pongratz, J.: Can ambitious forestation mitigate temperature overshoot?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10449, https://doi.org/10.5194/egusphere-egu24-10449, 2024.

EGU24-11759 | ECS | Posters on site | CL3.2.1

Investigating the path dependence of climate changes in a 200-member ensemble of overshoot scenarios 

Mitchell Dickau and H. Damon Matthews

Current policies have global mean temperature (GMT) on track to surpass the temperature thresholds agreed upon in the Paris Agreement. Therefore, if the goals of the Paris Agreement are to be met, there is an increasing likelihood of temporarily overshooting the 1.5°C or well-below 2.0°C thresholds. Using an intermediate complexity global Earth system model, we explore the climate implications of temperature overshoot using ≈100 pairs of multi-gas emissions scenarios from the ENGAGE project, with peak temperatures from ≈1.5°C to ≈2.2°C. For each pair of scenarios, the first is constrained by the remaining carbon budget (RCB) in 2100, which allows for the possibility of overshoot, while the second is constrained by the same RCB irrespective of a time horizon and acts as a baseline scenario. The comparisons of the pairs of scenarios demonstrate that the climate changes that occur at a given GMT are path dependent. In this presentation, we show how the impacts of overshoot vary depending on: 1) peak temperature, 2) the degree of overshoot, 3) the duration of overshoot, and 4) the amount of warming caused by CO2 vs. non-CO2 emissions. Our study expands on the literature by investigating the climate implications of temperature overshoot in an ensemble of ≈200 multi-gas scenarios with a range of temperature targets using a spatially explicit Earth system model.

How to cite: Dickau, M. and Matthews, H. D.: Investigating the path dependence of climate changes in a 200-member ensemble of overshoot scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11759, https://doi.org/10.5194/egusphere-egu24-11759, 2024.

EGU24-12063 | ECS | Orals | CL3.2.1

Long-Term Negative Emissions and Irreversibilities following Temporary Overshoots: An Earth System Model Perspective 

Fabrice Lacroix, Friedrich Burger, Yona Silvy, Regina Rodrigues, Carl F. Schleussner, and Thomas L. Frölicher

Our understanding of impacts and feedbacks associated with temporarily overshooting the Paris Agreement temperature goal - where the 1.5 °C global warming target is exceeded and retraced at a later time period - is currently limited. Such overshoot scenarios are of increasing likelihood and have the potential to be devasting in terms of both their peak impacts and irreversibility, affecting natural and human systems.

Here, we apply the Earth System Model GFDL-ESM2M coupled to the Adaptive Emission Reduction Approach (AERA) in order to perform novel policy-relevant simulations over the 1861 to 2500 period that temporarily overshoot the global warming target of 1.5 °C at various levels of peak global warming (2.0, 2.5 and 3.0 °C), and compare these to a reference scenario that stabilizes at 1.5 °C. We use this framework to isolate features arising from the overshoots, and investigate (1) negative emissions needed to reverse an overshoot and their impacts for cumulative emissions, (2) spatial differences in surface warming and oceanic heat content between overshoot and 1.5°C stabilization case, and (3) impacts that these spatial differences have for precipitation, sea level rise and ocean ecosystem stressors.

Our framework suggests levels of negative carbon emissions of up to 9 Pg C yr-1 to revert the global temperature the most extreme overshoot of 3.0 °C back to 1.5 °C, with less cumulative emissions allowed in the long-term than in the 1.5 °C simulation to maintain global temperature at 1.5°C. We detect long-term high latitude warming of up to 2.1 °C averaged over the North Atlantic and 0.5 °C over the Southern Ocean that persists after the overshoot. We attribute the persistent warming in the high latitudes to the recovery of both Atlantic Meridional Overturning Circulation and Antarctic abyssal overturning, which retrace to even higher levels in the overshoots than in the 1.5 °C stabilization case. These impact the distribution of precipitation, for instance stronger precipitation found in the high latitudes in the overshoots, as wells as the Pacific Walker Cell. The model also shows that due to excess heat storage in the subsurface of low latitudinal oceans, sea level rise does not recover back to 1.5 °C stabilization levels in overshoot scenarios, remaining up to 20 % higher in the strongest overshoot. The persistent long-term changes that the overshoots that we detect imply consequences for regional climates, cryosphere and marine ecosystems lasting for decades or even centuries after the overshoot reversal. 

How to cite: Lacroix, F., Burger, F., Silvy, Y., Rodrigues, R., Schleussner, C. F., and Frölicher, T. L.: Long-Term Negative Emissions and Irreversibilities following Temporary Overshoots: An Earth System Model Perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12063, https://doi.org/10.5194/egusphere-egu24-12063, 2024.

EGU24-12476 | Orals | CL3.2.1 | Highlight

Beyond the Peak: What we know and don't know about temperature overshoot 

Carl-Friedrich Schleussner

Global emission reduction efforts continue to be insufficient to meet the temperature goal of the Paris Agreement. This makes the systematic exploration of so-called overshoot pathways that draw temperatures back down to safer levels in the long term a priority for science and policy.

I will present major insights from the Horizon 2020 PROVIDE project on overshoot pathways. We find that global and regional climate change in a post-overshoot world would be substantially different from a world that avoided overshoot, bearing profound implications for adaptation needs. Irrespective of the peak warming, we find that achieving declining global temperature remains critical for limiting long-term climate risks including sea-level rise and cryosphere changes. Reversal of warming by deploying carbon dioxide removal (CDR) at scale, however, is not guaranteed. In addition to uncertain technical and sustainability limitations of CDR, we find that a preventive CDR capacity of several hundred gigatonnes might be desirable to hedge against strong Earth system feedbacks that amplify warming. Aiming for temperature decline is thus not a robust strategy to achieve a climate objective, but rather one part of a broader approach towards managing long-term climate risks. It is no replacement for stringent near-term emission reductions to limit risks at peak warming in the first place.

How to cite: Schleussner, C.-F.: Beyond the Peak: What we know and don't know about temperature overshoot, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12476, https://doi.org/10.5194/egusphere-egu24-12476, 2024.

EGU24-13448 | Orals | CL3.2.1 | Highlight

Exploring climate stabilisation at different global warming levels in ACCESS-ESM-1.5 

Andrew King, Tilo Ziehn, Matthew Chamberlain, Alexander Borowiak, Josephine Brown, Liam Cassidy, Andrea Dittus, Michael Grose, Nicola Maher, Seungmok Paik, Sarah Perkins-Kirkpatrick, and Aditya Sengupta

Under the Paris Agreement, signatory nations aim to keep global warming well below 2°C above pre-industrial levels and preferably below 1.5°C. This implicitly requires achieving net-zero or net-negative greenhouse gas emissions to ensure long-term global temperature stabilisation or reduction. Despite this requirement, there have been few analyses of stabilised climates and there is a lack of model experiments to address our need for understanding the implications of the Paris Agreement for the Earth system. Here, we describe a new set of experiments using the Australian Community Climate and Earth System Simulator earth system model (ACCESS-ESM-1.5) that enables analysis of climate evolution under net-zero emissions, and we present initial results. Seven 1000-year long simulations were run with global temperatures stabilising at levels in line with the Paris Agreement and at a range of higher global warming levels. We provide a brief overview of the experimental design and show how these model simulations may be used to understand possible net-zero emissions climates. We find major consequences of delayed attainment of global net-zero carbon dioxide emissions for different aspects of the climate system. As the climate stabilises under net-zero emissions, we identify significant and robust changes in temperature and precipitation patterns including continued Southern Ocean warming and reversal of transient mid-latitude drying trends. Regional climate changes under net-zero emissions differ greatly including contrasting trajectories of sea ice extent between the Arctic and Antarctic. While Arctic sea ice extent is projected to stabilise under net-zero emissions, sustained Southern Ocean warming is associated with continued sea ice decline in the Antarctic. We also examine the El Niño-Southern Oscillation (ENSO) and find evidence of reduced amplitude and frequency of ENSO events under climate stabilisation relative to projections under transient warming. An analysis at specific global warming levels shows significant regional changes continue for centuries after emissions cessation. Our findings suggest substantial long-term climate changes are possible even under net-zero emissions pathways. We hope these simulations will be of use to the community and that they motivate further experiments and analyses based on other earth system models.

How to cite: King, A., Ziehn, T., Chamberlain, M., Borowiak, A., Brown, J., Cassidy, L., Dittus, A., Grose, M., Maher, N., Paik, S., Perkins-Kirkpatrick, S., and Sengupta, A.: Exploring climate stabilisation at different global warming levels in ACCESS-ESM-1.5, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13448, https://doi.org/10.5194/egusphere-egu24-13448, 2024.

The constant ratio of global warming to cumulative CO2 emissions underpins the use of remaining carbon budgets as policy tools, and the need to reach net zero CO2 emissions to stabilize global mean temperature. One requirement for this proportionality is that the temperature response to a pulse emission of CO2 is independent of the background emissions scenario, and this property has been explained by a balance between the logarithmic dependence of radiative forcing on CO2 concentration, and the saturation of CO2 sinks at higher CO2 levels. Several studies have argued that this proportionality also arises because heat and carbon are mixed into the ocean by similar physical processes, and this argument was echoed in the Intergovernmental Panel on Climate Change Sixth Assessment Report. However, contrary to this hypothesis, atmosphere-ocean fluxes of heat and carbon evolve very differently to each other in abrupt CO2 increase experiments in five earth system models, and changes in the atmosphere, ocean and land carbon pools all contribute to making warming proportional to cumulative emissions. Moreover, an analytical model only exhibits proportional heat and carbon fluxes and proportional warming to cumulative emissions if the land and atmosphere carbon pools are neglected, among other unrealistic assumptions. These results strongly suggest that this proportionality is not amenable to a simple physical explanation, but rather arises because of the complex interplay of multiple physical and biogeochemical processes.

How to cite: Gillett, N.: What explains the proportionality of global warming to cumulative carbon emissions?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13603, https://doi.org/10.5194/egusphere-egu24-13603, 2024.

EGU24-16039 | ECS | Posters on site | CL3.2.1

Regional climate signals in overshoot scenarios 

Peter Pfleiderer, Carl-Friedrich Schleussner, and Jana Sillmann

Global warming levels are politically relevant targets, and therefore, in public discussion and in climate science, these global warming levels are often taken as a reference for climate states. While the focus on global warming levels is a useful simplification in many cases, it becomes misleading when looking at temperature overshoot (or stabilization) scenarios. In temperature overshoot scenarios, greenhouse gas concentrations are eventually reduced leading to a decrease in global mean temperatures. In such scenarios, lagged effects, feedback mechanisms, and tipping points can result in considerably different climate states after the overshoot as compared to before at the same global warming level.

Here we assess to what extent changes in regional climate signals are reversed in the period after peak warming when global mean temperature decreases. We analyze a multi-model ensemble of CMIP6 simulations of two overshoot scenarios, SSP5-34-OS and SSP119. In many regions, climate signals are decoupled from global mean temperatures in the decades after peak warming, leading to differences in regional climate signals between before and after the overshoot at the same global warming level.

More dedicated climate simulations of overshoot scenarios would be required to better evaluate how long the influence of the overshoot would affect regional climate signals and to better understand the mechanisms behind these changes. The presented overview of regional climate signals in overshoot scenarios until 2100 already suggests that considerable implications of temperature overshoots for climate impacts are to be expected and that these implications need to be considered for adaptation planning and policy making.

How to cite: Pfleiderer, P., Schleussner, C.-F., and Sillmann, J.: Regional climate signals in overshoot scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16039, https://doi.org/10.5194/egusphere-egu24-16039, 2024.

EGU24-16992 | ECS | Posters on site | CL3.2.1

Closing in on Zero Emissions Commitment (ZEC) uncertainty 

David Hohn, Estela Monteiro, Giang Tran, and Nadine Mengis

A stabilisation of global temperature can be achieved by reducing anthropogenic CO2 emissions to zero. Delayed warming or cooling, called zero emissions commitment (ZEC), can still occur after emissions have stopped. The magnitude of ZEC has been estimated to be 0±0.3 degrees Celsius, based on multi-model means. The individual models, however, show a wide range of responses from the climate system to the cessation of emissions, furthering the uncertainties regarding future temperature developments.

Therefore, it is crucial to improve our knowledge of the ZEC uncertainty range in multiple aspects. This study contributes to a better understanding of the leading drivers of uncertainty of ZEC by analyzing a perturbed parameter ensemble of key dynamics of ZEC in ambitious mitigation scenarios. Using an Earth system model of intermediate complexity (UVic ESCM), we quantify how model parameters affect ZEC estimates for zero emissions preceded either by idealised constant emissions (20 and 10 PgC/yr) or by net-negative emissions scenarios. Finally, we analyze how the efficiency of Earth system processes relevant to ZEC, like carbon burial and heat uptake, can vary over different timescales after cessation of emissions.

How to cite: Hohn, D., Monteiro, E., Tran, G., and Mengis, N.: Closing in on Zero Emissions Commitment (ZEC) uncertainty, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16992, https://doi.org/10.5194/egusphere-egu24-16992, 2024.

EGU24-17012 | Posters on site | CL3.2.1

Pacific climate variability and its regional impacts in warmer, stabilised climates 

Andrea Dittus, Nicola Maher, Andrew King, and Aditya Sengupta

The El Niño Southern Oscillation (ENSO) in the tropical Pacific is the main mode of inter-annual climate variability and a key driver of regional climate across much of the globe. Future changes in its behaviour are highly policy-relevant as they would have large impacts across many regions and significantly affect ecosystems and livelihoods. In this presentation, we explore how ENSO variability evolves in multi-century experiments under fixed atmospheric concentrations of greenhouse gases, where global mean surface temperatures are slowly stabilising.
We show how ENSO variability and its teleconnections change in a range of climate models and experimental designs. Idealised projections under fixed atmospheric concentrations of greenhouse gases across multiple levels of global warming, from 1.5°C to 5°C, are evaluated for the UK Earth System Model 1 alongside abrupt forcing experiments with the Community Earth System Model 1. We also include closely related experimental designs, such as emission-driven stabilisation experiments with ACCESS-ESM-1.5. The differences in how ENSO and its teleconnections respond to further warming in long, multi-century experiments under constant or slowly declining forcing conditions are compared and contrasted to the expected ENSO changes in rapidly warming, transient climate change projections. 

These differences are important to understand in the context of ambitious mitigation scenarios that aim to stabilise global temperatures at, or below, the Paris Agreement temperature targets. Preliminary results suggest that future ENSO variability is model dependent, but withing a single model framework independent of the level at which warming is stabilised at. 

How to cite: Dittus, A., Maher, N., King, A., and Sengupta, A.: Pacific climate variability and its regional impacts in warmer, stabilised climates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17012, https://doi.org/10.5194/egusphere-egu24-17012, 2024.

EGU24-17377 | Posters on site | CL3.2.1 | Highlight

Early Warning of Crossing the 1.5°C Global Temperature Change Threshold 

Debbie Rosen, Lawrence Jackson, Piers Forster, and Carl-Friedrich Schleussner

With the human induced increase in global temperatures continuing, the question if and how we might exceed the 1.5°C warming level enshrined in the long-term temperature goal of the Paris Agreement has received increased public and scientific interest. Identifying the level of human induced warming at any given year is subject to a range of uncertainty including from short-term natural variability. A single year, or even several consecutive years, above 1.5°C thus does not imply that the human induced warming level is reached but does provide an early warning of the risk of crossing that threshold.

Here we find that under an emission pathway following current policies, a single year above 1.5°C might imply that a crossing of the global warming threshold could materialise within 11 years thereafter (66% or likely range). For a three (5) year consecutive average, this time window decreases to 5 (2) years. If 1.5°C is reached in 2024, according to our analysis it would mark an unusual event (about 1-in-25 years) under a current policy scenario that reaches 1.5°C around 2040 (central estimate). We find that stringent emission reductions in the near-term can increase the chances of never crossing 1.5°C. Under a scenario of stringent emission decline, an exceedance of 1.5°C in one or several years may be observed without the long-term warming level ever being breached.

The occurrence of a single year at or above 1.5°C should therefore be taken as a final warning for the need for very stringent near term emission reductions to keep the Paris Agreement long-term limit within reach.

How to cite: Rosen, D., Jackson, L., Forster, P., and Schleussner, C.-F.: Early Warning of Crossing the 1.5°C Global Temperature Change Threshold, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17377, https://doi.org/10.5194/egusphere-egu24-17377, 2024.

EGU24-17881 | ECS | Posters on site | CL3.2.1

Uncertainties in climate sensitivity and residual carbon emissions permit for a hothouse climate ahead 

Christine Kaufhold, Matteo Willeit, Stefanie Talento, and Andrey Ganopolski

Given the large ‘very likely’ range of equilibrium climate sensitivity (ECS, 2 to 5 K), as reported by the Intergovernmental Panel on Climate Change (IPCC) and additional carbon cycle feedbacks, we investigate whether the current Earth system has the potential to significantly deviate from pre-industrial levels in the long-term towards a “hothouse” state. We use the fast Earth system model CLIMBER-X to generate an ensemble of simulations for the next millennium with interactive CO2 and CH4 for ECS values between 2 and 5 K, and force our simulations using the extended low-to-intermediate emission scenarios of SSP1-2.6, SSP4-3.4, and SSP2-4.5. These scenarios are normally associated with peak global warming levels of 1.5, 2, and 3°C respectively for a standard ECS of approximately 3 K.

In simulations using an ECS of 5 K, we observe that the global mean temperature increase would more than double compared to the standard ECS of 3 K. Roughly half of this warming is propelled by positive carbon cycle feedbacks in the different scenarios, with equal contributions from both CO2 and CH4. In the SSP2-4.5 “middle of the road” scenario, we find that a high ECS could see global mean temperatures which exceed 7 °C within the next millennium, with some regions experiencing temperature increases up to 20 °C via polar amplification. If we consider unavoidable residual carbon emissions of less than 10% of our present-day value, we find that the CO2 concentration in the atmosphere can be sustained, thereby resulting in a continuous temperature rise until the year 3000 A.D. unless carbon is sequestered. Prolonged periods of high temperatures, as seen in this study, could lead to the breaching of critical thresholds within the Earth system, like the stability of the Greenland and Antarctic ice sheets for example. As high ECS values cannot be disregarded as implausible at the present time, these results hint hint that we could be on track towards an extreme “hothouse” climate in the long-term if there is no carbon removal.

How to cite: Kaufhold, C., Willeit, M., Talento, S., and Ganopolski, A.: Uncertainties in climate sensitivity and residual carbon emissions permit for a hothouse climate ahead, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17881, https://doi.org/10.5194/egusphere-egu24-17881, 2024.

EGU24-17980 | ECS | Posters on site | CL3.2.1

Let’s be SMART about climate goals 

Nadine Mengis

Although largely scientifically robust, there are elements within the politically-negotiated Paris Agreement where defined methods deviate from the best available assessment of what is physically required to achieve its set goals. Fundamentally, one such deviation is about the net zero greenhouse gas (GHG) emissions goal: current interpretations and applications thereof in nationally determined contributions deviate from what is actually required to halt human-induced global warming.

Here I show that, while attempting to be comprehensive, most of the nationally declared climate goals are unspecific if not misleading, do not actually deliver on temperature stabilisation and have a problematic treatment of future carbon removal (CDR) expectations. On the one hand, the net zero CO2-eq goals overemphasise the need for CDR deployment to reach climate targets, since net-negative CO2 emissions are required to compensate for non-CO2 GHGs. On the other hand, accounting for natural sinks as CDR within national net-zero goals overestimates current and future CDR potentials and mitigation actions, and will not actually deliver anthropogenic net zero CO2.

I accordingly propose to re-orient national climate action towards Specific, Measurable, Achievable, Relevant and Time-bound (SMART) goals, such as a net zero fossil fuel CO2 emissions target by mid-century.

How to cite: Mengis, N.: Let’s be SMART about climate goals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17980, https://doi.org/10.5194/egusphere-egu24-17980, 2024.

EGU24-18510 | ECS | Posters on site | CL3.2.1

Temporal dynamics of terrestrial carbon dioxide removal 

Tobias Nützel, Sabine Mathesius, Jens Krause, Sabine Egerer, Conor Ó Beoláin, Daniel Bampoh, Stefanie Falk, Dieter Gerten, Wolfgang Obermeier, and Julia Pongratz

Virtually all future scenarios in the IPCC AR6 keeping climate change well below 2°C include carbon dioxide removal (CDR), often leading to large transformations of global land surface and land use. Re-/afforestation (AR) and bioenergy with carbon capture and storage (BECCS) are the two most prominent CDR measures in those scenarios. The temporal evolution of carbon uptake and storage is very different between bioenergy plants, which are annually harvested to (ideally) permanent storage, and forests, which sequester carbon for decades on site but can be affected by disturbances. Additionally, while AR dominates current CDR deployment as tree seedlings and saplings can be planted right away, BECCS requires further processing and storage infrastructure leading to longer establishment time scales. Thus, BECCS covers only a tiny fraction of existing and announced amounts of CDR. Hence, depending on whether CDR is intended to support rapid, deep reductions of net emissions in the near term (as in the Nationally Determined Contributions of parties to the Paris Agreement) or to counterbalance residual emissions or even reach net negative emissions in the longer term, either AR or BECCS could be more effective. This will also vary across world regions. 

We compare the temporal dynamics of carbon storage efficiency between AR and BECCS with three state-of-the-art terrestrial biosphere models (JSBACH, LPJmL, LPJ-GUESS). We use a global, highly stylized setup where a fixed share per pixel of current agricultural land is replaced by forests or bioenergy plants, respectively. We analyze the effectiveness of the two CDR methods over time and in different world regions depending on the temporal CDR target. Furthermore, we quantify how the temporal dynamics are affected by the chosen start year of CDR (2015, 2030, 2050), background climate and CO2 concentrations (SSP1-2.6, SSP3-7.0),  natural disturbances and assumptions on management and plant parametrizations in the underlying vegetation models. We specifically consider temporal dynamics on current agricultural areas adjacent to biodiversity hotspots, since these could also become relevant for achieving ecosystem restoration targets. There, CDR through restoration of naturally occurring forests or grasslands with support from local communities can bring synergies for multiple ecosystem services, while premature deployment of AR in non-forest areas or crop-based BECCS would likely decrease biodiversity.

How to cite: Nützel, T., Mathesius, S., Krause, J., Egerer, S., Ó Beoláin, C., Bampoh, D., Falk, S., Gerten, D., Obermeier, W., and Pongratz, J.: Temporal dynamics of terrestrial carbon dioxide removal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18510, https://doi.org/10.5194/egusphere-egu24-18510, 2024.

EGU24-18992 | ECS | Orals | CL3.2.1

On the reversibility of Arctic sea ice loss 

Stefanie Rynders, Yevgeny Aksenov, Jörg Schwinger, Timothée Bourgeois, and Chris Jones

It is now expected carbon emissions will follow an overshoot trajectory. A realistic emission-driven overshoot scenario esm-SSP534-over is available from the CMIP6 archive. We analysed the simulations to examine reversibility of the Arctic sea ice cover. Reversibility here means that at the end of the 21st century the sea ice extent is the same as that at the earlier point in the century with the same atmospheric CO2 concentration. Firstly, in an emission driven simulation the system behaves differently on the upward and downward branches of CO2 concentration. We show it is better to use atmospheric CO2 concentration rather than Arctic surface air temperature, as the relation between the two is not linear. Total Arctic sea ice extent shows consistent behaviour in 3 out of 4 models (CNRM-ESM2, MIROC, UKESM1) with a CO2 concentration threshold above which sea ice becomes irreversible. This can be explained by the continued ocean heat transport into the Arctic even though the Atlantic Meridional Overturing Circulation (AMOC) declines. The NorESM model has very different behaviour, sea ice extent is reversible and even overshoots beyond the present-day extent. We suggest this is caused by the known strong AMOC decline in this model. The analysis indicates Arctic air temperature is a result of the changes in sea ice extent rather than the driving factor, as is often assumed, both ultimately controlled by ocean heat transport. From the available simulations we conclude there is large uncertainty in the future Arctic climate state. This uncertainty extends to the future global air temperatures as different models show different inertia on CO2 concentrations, which only materialises in the downward emission branch. This affects many other climate variables with their own time lag. Climate inertia and time delays in the earth system should be investigated further to improve fidelity of future projection. This necessitates the use of emission-driven scenarios instead of concentration-driven ones which do not allow for the full inclusion of internal earth system feedbacks. 

We acknowledge funding from the projects COMFORT (grant agreement no. 820989) and OceanNETs (grant agreement no. 869357) under the European Union’s Horizon 2020 research and innovation programme, and from the EC Horizon Europe project OptimESM “Optimal High Resolution Earth System Models for Exploring Future Climate Changes”, grant 101081193 and UKRI grant 10039429, from the project EPOC, EU grant 101059547 and UKRI grant 10038003. For the EU projects the work reflects only the authors’ view; the European Commission and their executive agency are not responsible for any use that may be made of the information the work contains.

How to cite: Rynders, S., Aksenov, Y., Schwinger, J., Bourgeois, T., and Jones, C.: On the reversibility of Arctic sea ice loss, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18992, https://doi.org/10.5194/egusphere-egu24-18992, 2024.

EGU24-19759 | Orals | CL3.2.1 | Highlight

Revising carbon budgets in a 1.5 degree world 

Benjamin Sanderson, Chris Smith, Charles Koven, Zeb Nicholls, Norman Steinert, and Marit Sandstad

The concept of a remaining carbon budget associated with global warming levels has underpinned mitigation efforts since the Paris Agreement.  However, as observed temperatures near 1.5 degrees, a number of challenges have emerged for the continued use of carbon budgets to frame mitigation needs.  Firstly, while the transient response to cumulative emissions describes the temperature response to constant emissions - Paris-compatible pathways require deep emissions cuts and potentially extended periods of negative emissions, the temperature outcome of which is complicated by zero emissions commitments and non-CO2 responses.  Understanding of Zero emissions commitments has been thus far been primarily informed by idealised experiments which terminate emissions during an idealised concentration ramp - but these metrics are subject to unrealistic termination shocks and model-specific emissions pathways.  Second, non-CO2 responses remain highly uncertain, and recent satellite observations of global radiative imbalance raise further questions on the adequacy of current modeling platforms to describe the warming which should be expected due to aerosol phaseout. 

Here, we consider how two novel developments impact carbon budgets beyond estimates presented in the IPCC 6th Assessment.  Firstly, we present an ESM ensemble of climate reversibility experiments which provides a more realistic proxy for non-TCRE carbon dynamics during a net zero transition for use in carbon budgets.  Secondly, we consider how the inclusion of recent global mean temperature measurements and CERES top of atmosphere radiative flux measurements would impacts the calibration of simple climate models - with subsequent impacts on both estimates of both TCRE and expected warming due to non-CO2 effects.  Synthesising this information, we provide an updated estimate of carbon budgets and timing with respect to the 1.5 and 2 degree thresholds.

How to cite: Sanderson, B., Smith, C., Koven, C., Nicholls, Z., Steinert, N., and Sandstad, M.: Revising carbon budgets in a 1.5 degree world, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19759, https://doi.org/10.5194/egusphere-egu24-19759, 2024.

EGU24-20890 | Orals | CL3.2.1

Exploring risks and benefits of overshooting a 1.5 ◦C carbon budget over space and time 

Nico Bauer, David Keller, Julius Garbe, Kristine Karstens, Franziska Piontek, Werner von Bloh, Wim Thiery, Maria Zeitz, Matthias Mengel, Jessica Strefler, Kirsten Thonicke, and Ricarda Winkelmann

Temperature targets of the Paris Agreement limit global net cumulative emissions to very tight carbon budgets. The possibility to overshoot the budget and offset near-term excess emissions by net-negative emissions is considered economically attractive as it eases near-term mitigation pressure. While potential side effects of carbon removal deployment are discussed extensively, the additional climate risks and the impacts and damages have attracted less attention. We link six models for an integrative analysis of the climatic, environmental and socio-economic consequences of temporarily overshooting a carbon budget consistent with the 1.5 ◦C temperature target along the cause-effect chain from emissions and carbon removals to climate risks and impact. Global climatic indicators such as CO2-concentration and mean temperature closely follow the carbon budget overshoot with mid-century peaks of 50 ppmv and 0.35 ◦C, respectively. Our findings highlight that investigating overshoot scenarios requires temporally and spatially differentiated analysis of climate, environmental and socioeconomic systems. We find persistent and spatially heterogeneous differences in the distribution of carbon across various pools, ocean heat content, sea-level rise as well as economic damages. Moreover, we find that key impacts, including degradation of marine ecosystem, heat wave exposure and economic damages, are more severe in equatorial areas than in higher latitudes, although absolute temperature changes being stronger in higher latitudes. The detrimental effects of a 1.5 ◦C warming and the additional effects due to overshoots are strongest in non-OECD countries (Organization for Economic Cooperation and Development). Constraining the overshoot inflates CO2 prices, thus shifting carbon removal towards early afforestation while reducing the total cumulative deployment only slightly, while mitigation costs increase sharply in developing countries. Thus, scenarios with carbon budget overshoots can reverse global mean temperature increase but imply more persistent and geographically heterogeneous impacts. Overall, the decision about overshooting implies more severe trade-offs between mitigation and impacts in developing countries.

How to cite: Bauer, N., Keller, D., Garbe, J., Karstens, K., Piontek, F., von Bloh, W., Thiery, W., Zeitz, M., Mengel, M., Strefler, J., Thonicke, K., and Winkelmann, R.: Exploring risks and benefits of overshooting a 1.5 ◦C carbon budget over space and time, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20890, https://doi.org/10.5194/egusphere-egu24-20890, 2024.

EGU24-585 | ECS | Orals | CL3.2.2

Stability analysis of sea-cliffs coupling stress strain and hydrodynamic modelling as a tool for modern archeological site preservation strategies 

Federico Feliziani, Gian Marco Marmoni, Denis Istrati, Valentina Gianni, Francesca Bozzano, and Salvatore Martino

Cultural heritage (CH) sites are frequently situated in coastal areas that experience landslide activity, potentially influenced by climatic effects. A growing number of studies have directed their attention toward investigating mitigation strategies for CH sites impacted by landslides. Nevertheless, there is a paucity of quantitative studies dedicated to elucidating the relationships between coastal landslide activity and climate-related factors. Specifically, the comprehensive understanding of the extent to which both preparatory and triggering climate-related factors contribute to slope instabilities remains incomplete. This knowledge gap is particularly pronounced in the case of waves and wind, whose impact is extensively examined in coastal engineering applications.
The Punta Eolo sea-cliff (Ventotene island, Italy) is here analyzed since it is frequently affected by rock-falls and topples that are threatening the vulnerable remnants of the roman archaeological site of Villa Giulia. This latter is one of the pilot sites selected in the framework of the H2020 TRIQUETRA European project, aimed to proposing a methodological framework for mitigating climate-related natural hazards affecting cultural heritage.
To account for the action of sea waves on a sea cliff, a preliminary attempt was made to couple hydrodynamic modeling of sea-related actions with stability analysis managed through limit-equilibrium and stress-strain approaches.  For the hydrodynamic modelling a mesh-based computational fluid dynamics (CFD) method, that had been validated previously for extreme wave impact on coastal structures both in 2D and 3D conditions, was utilized. The results of the hydrodynamic analysis (e.g., stress field applied on the cliff by waves impact) were then used as input data for the stability analysis. The slope stability conditions of Punta Eolo's sea cliff were evaluated for a rock-toppling mechanism; following that, slope stability analyses were carried out under static and pseudo-static conditions. The analysis considered both seismic action and static water pressure within the joint sets. In a subsequent phase of investigation, the sea-wave action was incorporated as a force accountable for an elastic rebound sensu Hutchinson (1988). Through hydrodynamic modeling, the maximum computed force exerted by sea waves against the cliff was converted into a pseudo-static coefficient. This latter served as input for the factor of safety (FOS) calculation.
The quantitative analysis has brought to light the potential occurrence of instability conditions in specific rock blocks when the hydrostatic backpressure resulting from the filling of rock cracks is coupled with a pseudo-static force, originating from the elastic rebound induced by the impact of sea waves. This scenario represents the most frequently encountered action at the examined cliff of Punta Eolo.
Finally, the project of the ongoing installation of a tailor-designed monitoring system in Punta Eolo is presented. This system aims to characterize the physical attributes of sea-related preparatory and triggering factors affecting the cliff, and to assess the deformative response of the cliff itself under the influence of periodic thermal and hydrodynamic stressors.

How to cite: Feliziani, F., Marmoni, G. M., Istrati, D., Gianni, V., Bozzano, F., and Martino, S.: Stability analysis of sea-cliffs coupling stress strain and hydrodynamic modelling as a tool for modern archeological site preservation strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-585, https://doi.org/10.5194/egusphere-egu24-585, 2024.

EGU24-1753 | ECS | Posters virtual | CL3.2.2

Advanced sensing and IoT for monitoring climatic risks and natural hazards at underwater and coastal cultural heritage 

Lampros Pavlopoulos, Panagiotis Michalis, Marios Vlachos, Anastasios Georgakopoulos, and Angelos Amditis

As climate change progresses, shifting weather events are expected to become more severe [1], posing a significant threat to heritage sites but also to connected communities. The monitoring of climatic risks at coastal and underwater heritage sites is considered of significant importance to enhance understanding of degradation processes but it constitutes a resource-intensive and intricate process. Frequently, data collection from devices requires the coordination of expeditions for sensor retrieval and manual data acquisition. The monitoring area's spatial extent is limited due to the utilization of stationary sensors. Another challenge lies in the integration of both subaquatic and terrestrial parameters into an advanced monitoring solution that provides an unobstructed assessment of the hazards encompassing the heritage area.

The development of multiple low-cost sensors endowed with Internet of Things (IoT) capabilities, can facilitate real-time monitoring and positioning for both subaquatic and terrestrial data collection of environmental parameters that amplify the deterioration of heritage assets.

To address subaquatic data acquisition, an IoT Conductivity Depth Temperature (CDT) device has been designed to measure salinity and temperature characteristics with a dual role of a wearable sensor for divers and a static sensor affixed near the seabed. To streamline data transmission beyond aquatic environments, the device is engineered to transmit data when situated outside the water. The second subaquatic sensor developed serves the purpose of crowdsourcing and designed to be attached to vessels from local communities, enabling real-time data collection on salinity, temperature, and chlorophyll concentration. Both subaquatic devices integrate Inertial Measurement Unit (IMU), Narrowband Internet of Things (NB-IoT), and Global Navigation Satellite System (GNSS) technologies within their design.

The proposed coastal monitoring solution incorporates a weather station with the capacity to measure and transmit real-time data on diverse weather parameters, encompassing temperature, humidity, rain volume, wind speed, UV index, and light intensity. The fourth device integrates strain gauges and accelerometers, offering valuable data for both static and dynamic monitoring. This enables the assessment of vibration levels and provides information on the evolution of cracks and tilts within the monitored site. To optimize energy efficiency, all four devices have been engineered with low power consumption capabilities. Furthermore, devices located outside the water are equipped with solar panels to ensure complete energy autonomy.

In conclusion, the development of multiple low-cost sensors with IoT capabilities demonstrates a commitment to overcoming the financial and logistical complexities of data collection. By incorporating advanced technologies such as IMU, NB-IoT, and GNSS into subaquatic devices, we enhance the precision and versatility of real-time monitoring and positioning. By seamlessly integrating technological innovation with practical considerations, we aim to provide a comprehensive and efficient means of safeguarding these invaluable cultural and environmental treasures.

Acknowledgement:

This research has been funded by European Union’s Horizon Europe research and innovation programme under THETIDA project (Grant Agreement No 101095253).

References:

[1] Michalis, P.; Tarantino, A.; Tachtatzis, C.; Judd, M.D. (2015). Wireless monitoring of scour and re-deposited sediment evolution at bridge foundations based on soil electromagnetic properties. Smart Mater. Struct. 2015, 24, 125029.

How to cite: Pavlopoulos, L., Michalis, P., Vlachos, M., Georgakopoulos, A., and Amditis, A.: Advanced sensing and IoT for monitoring climatic risks and natural hazards at underwater and coastal cultural heritage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1753, https://doi.org/10.5194/egusphere-egu24-1753, 2024.

EGU24-1958 | ECS | Posters virtual | CL3.2.2

Unveiling the Hidden Data Ecosystems: A Pathway towards conservation and protection of Cultural Heritage sites 

Aikaterini Karagiannopoulou, Panagiotis Michalis, Chrysovalantis Tsiakos, and Angelos Amditis

Underwater and Coastal Cultural Heritage (CH) sites face unprecedented threats from climatic risks and natural hazards, making their preservation, conservation and protection complex and challenging issues. One primary challenge for designing efficient preservation strategies is the absence of curated open data streams that could allow local authorities to have a better understanding of the evolving degradation parameters at CH sites. The existing data silos and the lack of circular, sustainable and curated open data ecosystems (ODE) also leave the key players (i.e., asset managers, local authorities, etc.) of the heritage sites and their connected communities defenceless as they are usually equipped with obsolete and coarse information, a condition that generates a knock-on effect on the adaptation and mitigation strategies against these threats.

This study focused on providing a methodological approach towards data circularity by leveraging on the Open Data Institute's (ODI) Data Landscape Playbook (DLP) methodology. The ODI DLP serves as a comprehensive guide for developing effective data ecosystems. By adapting this playbook to the unique challenges posed by underwater and coastal cultural heritage preservation, stakeholders can harness the power of data to enhance resilience, response, and recovery efforts in the aftermath of natural disasters. This specific methodology consists of four consecutive steps, involving the investigation of the context of the objectives of each pilot case, the identification of all the relevant Data Assets and Data Owners, and therefore details related to the interfaces/infrastructures and standardised data formats that are commonly adopted. The last pillar of this methodology is declared as a prerequisite towards the data circularity, as it tries to profile heritage sites perspectives regarding the ethical, legal, and regulatory context that is chosen based on the Data Spectrum classification so as to disseminate the data sources through the public. The DLP also emphasises the importance of data quality assurance and control measures, ensuring this way about the credibility of the existing information and acknowledging the best practices so as to succeed.

The engagement of diverse stakeholders under the prism of the ODI-DLP attempts to foster collaboration and partnerships among governments, archaeologists, marine biologists, and local communities, and thus facilitate to formulation of sustainable strategies for risk assessment and mitigation, forming the cornerstone of resilient preservation practices. Towards this process, community involvement not only enriches the data ecosystem but also facilitates the integration of traditional knowledge, ensuring a more holistic and culturally sensitive approach to CHs’ preservation. This ODI-DLP methodology is currently applied to seven underwater and coastal heritage sites of THETIDA project, i.e., Mykonos (Greece), Gallinara and Equa (Italy), Algarve (Portugal), Paralimni (Cyprus), Svalbard (Norway), and Ijsselmeer (Netherlands) and thus, will contribute to the digitalisation of each site, creating this way a framework towards the generation of resilient data ecosystems and pathways to improve and enhance CH protection.

Acknowledgement:

This research has been funded by European Union’s Horizon Europe research and innovation programme under THETIDA project (Grant Agreement No 101095253). 

How to cite: Karagiannopoulou, A., Michalis, P., Tsiakos, C., and Amditis, A.: Unveiling the Hidden Data Ecosystems: A Pathway towards conservation and protection of Cultural Heritage sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1958, https://doi.org/10.5194/egusphere-egu24-1958, 2024.

EGU24-2090 | Posters on site | CL3.2.2 | Highlight

THETIDA: Safeguarding and protecting Europe’s coastal and underwater cultural heritage from the effects of climate change and natural hazards 

Panagiotis Michalis, Claudio Mazzoli, Vassilia Karathanassi, Deniz Ikiz Kaya, Flavio Martins, Michele Cocco, Anaïs Guy, and Angelos Amditis

Climate change and natural hazards pose significant threats to heritage sites, with major impact on people's livelihoods and connected communities. Increased frequency and intensity of extreme weather conditions have a substantial detrimental impact on cultural heritage (CH), both on tangible assets (e.g. monuments, historic buildings, and sites), and intangible elements (e.g. knowledge, cultural practices, and oral traditions) that are inherited from the past. Factors contributing to the deterioration of heritage sites are attributed to sea level rise, ocean acidification, intensified storm activity, temperature elevation, and coastal erosion that put significant stress on the stability, preservation, conservation, and security of both tangible and intangible cultural heritage in underwater and coastal environments.

However, limited knowledge exists on risk assessment and protective measures actions to mitigate these multiple hazards and complex risks posed by climatic conditions and natural disasters. This highlights the need for more integrated assessments that consider the collective impacts of various hazards on cultural heritage and their corresponding protection systems. It is therefore of significant importance to employ and test the effectiveness of novel measures across a spectrum of heritage sites threatened by various climatic conditions and risks.

Addressing these two points, the THETIDA project focuses on the development of a preventive conservation strategy that includes monitoring, risk preparedness and management, for underwater and coastal CH. The main objective is to identify and ward off climatic risks and natural hazards and promote adaptation, reconstruction, and other post-disruption strategies to restore normal conditions to the historic area. THETIDA project also emphasizes long-term strategic approaches to adapt to climate change and to wield policy tools for economic resilience. This is achieved through an interdisciplinary team of researchers, experts and practitioners that will develop, test and validate an integrated multiple heritage risk assessment and protection system with evidence-based monitoring frameworks, innovative tools and instruments and through participatory and crowdsourcing processes. The project actions will be implemented at seven pilot sites across the European continent, linking social innovations with state-of-the-art technologies, including ICT and IoT harmonised tools, to enhance resilience of underwater and coastal heritage sites.

Acknowledgement:

This research has been funded by European Union’s Horizon Europe research and innovation programme under THETIDA project (Grant Agreement No. 101095253) (Technologies and methods for improved resilience and sustainable preservation of underwater and coastal cultural heritage to cope with climate change, natural hazards and environmental pollution).

How to cite: Michalis, P., Mazzoli, C., Karathanassi, V., Ikiz Kaya, D., Martins, F., Cocco, M., Guy, A., and Amditis, A.: THETIDA: Safeguarding and protecting Europe’s coastal and underwater cultural heritage from the effects of climate change and natural hazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2090, https://doi.org/10.5194/egusphere-egu24-2090, 2024.

EGU24-2448 | ECS | Orals | CL3.2.2

Innovative financing strategies for the resilience of cultural landscapes. A literature and practice review 

Dana Salpina, Veronica Casartelli, Angelica Marengo, and Letizia Monteleone

According to the Intergovernmental Panel on Climate Change (IPCC) coastal risks are projected to increase by at least one order of magnitude over the 21st century due to committed sea level rise, impacting cultural and natural heritage in coastal areas. Amidst the urgency of climate change adaptation and mitigation, which often exceeds available public budgets, there is a growing recognition of the vital role played by innovative financing strategies and business models .

The existing body of knowledge on resilience financing for cultural heritage and landscapes is somewhat fragmented and primarily focuses on the conservation or reuse of the built heritage. Few studies addressed the financial strategies for productive cultural landscapes. Unlike conventional cultural heritage categories such as historical monuments, archaeological artefacts, and museum collections, productive cultural landscapes are dynamic socio-ecological systems. Consequently, their resilience demands a holistic approach that addresses not only the physical dimension but also ensures the continuity of underlying activities, such as agriculture, forestry, and fishery.

As part of the  “RescueMe” project – focused on equitable resilience solutions to strengthen the link between cultural landscapes and communities – this study aims to consolidate fragmented knowledge. It seeks to provide an initial state-of-the-art overview of existing financing strategies, with a specific focus on productive cultural landscapes, such as agricultural landscapes. Based on a systematic review of existing literature, databases, and drawing insights from prior projects, this study presents a thorough review of innovative financial strategies. This encompasses economic, financial, and business models that have the potential to leverage regenerative capital investments in landscape resilience.

The study reveals dominant themes and categories of financing strategies for the resilience of productive cultural landscapes. The selected innovative financial strategies will be gathered in the RescueME resilience meta-repository, to offer an integrated searchable database of solutions, elaborated jointly with the researchers from the Università di Bologna and the Conexiones improbables, with the consultation of partners representing resilience landscape laboratories (R- labscapes) of the project.

The findings offer valuable insights for policymakers, businesses, and cultural institutions seeking to develop strategies for scaling up investments. This contribution is instrumental in navigating the complex landscape of innovative financing, providing actionable knowledge for sustainable and effective decision-making. The information available in the meta-repository will be accessible for reuse to a wide-range of stakeholders, including policymakers, researchers and practitioners.

How to cite: Salpina, D., Casartelli, V., Marengo, A., and Monteleone, L.: Innovative financing strategies for the resilience of cultural landscapes. A literature and practice review, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2448, https://doi.org/10.5194/egusphere-egu24-2448, 2024.

EGU24-2539 | Orals | CL3.2.2 | Highlight

R&I solutions and Blue Culture Technology Hubs supporting Underwater Cultural Heritage research 

Lydia Stergiopoulou, Angelos Manglis, Polyvios Raxis, and Stelios Krinidis

This work presents the framework of BCT Hubs project that operates in the space of Blue Culture Technologies (BCT) supporting the Underwater (UW) Cultural Heritage (CH) scientific research. The development of BCT Excellence Hubs and their promoted R&I solutions support, as regional ecosystems, the sustainable protection, restoration, valorization, management, and accessibility of UWCH by consolidating capacities of public sector, research/academia, NGOs, and business stakeholders. An innovative framework is under development that combines sensors information with navigational data and GIS-based software to provide high-quality 3D/4D UW representations. These R&I services will be linked to virtual reality (VR) technologies improving on-site and remote accessibility to UWCH via dry-dive; as well as to an augmented reality (AR) app that based on sensing solutions can augment diving capability. Ongoing additional developments combination of the 3D/4D models with real-time streams and AI algorithms aiming at detecting looting or degradation of UW assets.  

The development of the BCT Excellence Hubs in Greece, Malta, Bulgaria aims at the establishment of regional ecosystems, where R&I actors will offer access to excellence, knowledge transfer and development of entrepreneurial skills. The technical support needed, as well as the digital maturity level of the Blue Culture value chain of the ecosystems will be analysed and assessed, towards receiving tools and support with respect to their UWCH missions. Overall aim is the management of UW heritage under threat, UW documentation, archaeological excavation, safeguarding, promotion and accessibility.

How to cite: Stergiopoulou, L., Manglis, A., Raxis, P., and Krinidis, S.: R&I solutions and Blue Culture Technology Hubs supporting Underwater Cultural Heritage research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2539, https://doi.org/10.5194/egusphere-egu24-2539, 2024.

EGU24-3000 | Orals | CL3.2.2

Monitoring an Arctic cultural heritage site with state-of-the-art remote sensing techniques – Lessons from the THETIDA project 

Ionut Cristi Nicu, Kleanthis Karamvasis, Vassilia Karathanassi, and Paloma Guzman

The Svalbard archipelago lies 1100 km south of the North Pole and 800 km north of the Norwegian coast. The region is one of the most important and strategic terrestrial nodes on Earth, separating the Greenland Sea, the Barents Sea, and the Arctic Ocean. The cultural landscape reflects human life and activity in a harsh and fragile environment.

We present here the preliminary results of the pilot site from the Thetida project – the coal cableway station at Hiorthhamn, 1917 (Taubanestasjonen i Hiorthhamn). The study area was extended to the “town” of Longyearbyen, located across the bay from Hiorthhamn. Longyearbyen is the settlement with the largest number of Svalbard residents (approximately 2500) and with an impressive number of protected cultural heritage sites – approximately 400. The total number of protected cultural heritage sites in Svalbard is 4590.

Previous studies have shown that the main risks to the Hiorthhamn site are coastal erosion, permafrost degradation, rockfall, thaw slumps, snow avalanches, surface erosion and thermo-erosion gullies, weathering, river flooding, and solifluction. Previous data (NPI orthophotos from 1936, 2009 – 2011, field surveys with UAV and total station in 2019 and 2020) and the most recent remote sensing data (Planet Sky Sat images – 2023) are used to assess the risk of degradation. Coastal erosion, calculated with the help of DSAS, for the sector where the site is located, shows high erosion rates of −0.77 m/yr (for the period 1927-2020) when compared to other studies from Svalbard. The latest forecast analysis estimates that the entire area will be eroded over the next two decades.

Furthermore, previous studies have shown that InSAR-based time series of land deformation appears to show continuous subsidence over permafrost regions in recent years. In this study, a method based on persistent scattering interferometry was used to estimate land deformation in the wide area of Longyearbyen, Svalbard. The InSAR-based land deformation estimates were calculated by processing 268 Sentinel-1 images from early 2018 to late 2023. Within the city of Longyearbyen, regions of stable, uplifting, and subsiding ground motion were identified. The land deformation results were interpreted by considering in-situ permafrost data and building characteristics, such as roof material, age, and heating mechanisms under building foundations. The results are important for better understanding the dynamics of the permafrost landscape under a warming climate and for predicting flooding using SAR altimetry data. The study makes a significant contribution to the protection of cultural heritage. The coal cableway station is the most iconic and visible object in Hiorthhamn, so much so that it can be seen from Longyearbyen, encouraging tourists to take a boat or a kayak to visit. Longyearbyen is the main tourist attraction on the island. It is therefore important to assess and monitor the risk of degradation so that, together with the local authorities, the most sustainable and climate-friendly measures can be taken for future generations.

Acknowledgment: This research has been funded by European Union’s Horizon Europe research and innovation funding under Grant Agreement No: 101095253, THETIDA project.

How to cite: Nicu, I. C., Karamvasis, K., Karathanassi, V., and Guzman, P.: Monitoring an Arctic cultural heritage site with state-of-the-art remote sensing techniques – Lessons from the THETIDA project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3000, https://doi.org/10.5194/egusphere-egu24-3000, 2024.

EGU24-3132 | ECS | Orals | CL3.2.2 | Highlight

Living Labs for participatory value, risk and impact assessments in coastal and underwater heritage sites  

Deniz Ikiz Kaya, Paloma Guzman, Cristina Veiga-Pires, Sonia Oliveira, Tina Katika, Anne Veere Hoogbergen, Kevin Pulles, and Ionut Cristi Nicu

Climate change can have detrimental effects on biodiversity and people’s livelihoods and communities. Extreme weather conditions triggered by climate change significantly impact cultural heritage that represents tangible (i.e., historic sites, cultural landscapes) and intangible (i.e., knowledge, cultural practices, oral traditions) assets, especially in coastal areas and underwater sites. Inclusive risk monitoring, preparedness, and management are necessary to identify and ward off additional threats, and to promote inclusive and sustainable adaptation and safeguarding of the heritage sites.  

Stakeholder and end-user engagement is gaining ground in risk mitigation and monitoring impacts of climate change to support co-creation processes for climate adaptation strategies. Stakeholders often have valuable knowledge, insights and expertise, and their engagement allows collection of diverse perspectives and data, which can lead to better-informed decisions and identify potential risks and opportunities. However, it can also be difficult to establish collaboration and open communication among different actors and parties. This paper presents the potential of Living Labs (LL), a participatory social innovative methodology, that functions as multi-stakeholder platforms. LL create interaction spaces in which multiple stakeholders and end users collaborate in creating new solutions to complex problems. 

This paper presents the initial stage of development and testing of the LL methodology to be implemented in seven pilot sites of underwater and coastal heritage across three different Europe oceanic climates that are vulnerable to varied impacts of climate change. Results present common challenges in the identification of diverse range of stakeholders and their engagement in co-creation processes of value and impact assessment, decision and future making, as well as testing and validating of a new crowdsourcing tool in real-life contexts. The goal has been building inclusive multi-stakeholder communities for establishing sustainable participatory processes for co-designing and co-creating risk assessment and adaptation strategies that take sociocultural values at their core. For this purpose, a LL toolkit has been developed that compiles different sets of tested methods that have been applied in the case studies adaptable to local contexts.  

This paper will show the outcomes of a training workshop and the preliminary results of the adopted and tested LL tools and processes in which stakeholders from pilot sites identify heritage inherent values based on sociocultural relationships. Results highlighting diverse understandings of climate impacts and challenges but are also expected to show a shift on peoples’ perspectives when providing meaning to climate change impacts. Such insights and feedback are discussed in terms of strengths and weaknesses that are unique to the site, as well the LL methods and tools employed in each site. Such exercises are increasingly needed to customize participatory methods adapted to fit integrated multiple hazard assessment tools and strengthen sustainable pathways for cultural heritage management. Overall, these processes will contribute to better understanding of the complexity of climate impacts, not only on heritage, but also in related social dynamics. 

Acknowledgement:  This research has been funded by European Union’s Horizon Europe research and innovation funding under Grant Agreement No: 101095253, THETIDA project. 

How to cite: Ikiz Kaya, D., Guzman, P., Veiga-Pires, C., Oliveira, S., Katika, T., Hoogbergen, A. V., Pulles, K., and Nicu, I. C.: Living Labs for participatory value, risk and impact assessments in coastal and underwater heritage sites , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3132, https://doi.org/10.5194/egusphere-egu24-3132, 2024.

EGU24-3517 | Orals | CL3.2.2 | Highlight

Empowering Communities Through Digital Innovation and Crowdsourcing for Cultural Heritage Preservation 

Tina Katika, Konstantinos Koukoudis, Panagiotis Michalis, Deniz Ikiz Kaya, Paloma Guzman, Cristina Veiga-Pires, and Angelos Amditis

Climatic risks and natural hazards pose a serious threat with long lasting impacts on cultural heritage, as well as on people’s livelihoods and connected communities. It is therefore considered of major importance to better understand the multivaried impacts of climate change on coastal and underwater cultural heritage through the active involvement of scientists, citizens and other relevant stakeholders in citizen science to engage them in data collection and involve their diverse perspectives, reflections and relationships with heritage for multi-hazard and risk monitoring.

This study focuses on exploiting the full potential of digital solutions together with co-creation and co-design processes through citizen science, crowdsourcing and participatory Living Lab methodologies. The main goal is to help citizens identify the values of coastal and underwater heritage, to understand the risks, and engage them in monitoring the changes and documenting the impacts of climate change and natural hazards on the heritage elements to collaboratively develop sustainable preservation and adaptation strategies. An immersive mobile application will be developed to raise awareness to citizens and their communities about digitalization and its benefits for cultural heritage protection and preservation. The proposed technological advancement exploits Augmented Reality (AR) technology to seamlessly integrate in-situ and remotely sensed data, effectively bridging the gap between valuable underwater cultural assets and a broader audience, that may not have had the opportunity to experience them otherwise.  

The digital solution is being co-designed and co-developed with citizens and their communities exploiting immersive crowdsourcing techniques using user-centered applied research and open innovation approaches. It employs crowdsourced techniques to promote the appreciation of the tangible and intangible heritage assets, empowering communities to actively participate in preserving and showcasing their cultural treasures. Citizens will be able to share their feedback, observations, comments and other data considered relevant to establish their unique point of view. The mobile application will then facilitate the demonstration and visualization of sensed data obtained by underwater and coastal crowdsensing units provided to the community (e.g. fishing boats, divers) to inform about environmental parameters, providing a comprehensive understanding of heritage dynamics and potential risks. Finally, the proposed digital solution will enhance citizen engagement, creating immersive experiences through AR features that bridge the gap between the past and present, fostering a deeper connection between people and their cultural legacy.

The immersive digital solution is being co-developed with seven different demonstration sites across Europe and will also be made available to a large stakeholder community at the end of 2024 for the first iteration of user feedback. Together, these functionalities establish a powerful tool for the proactive management and protection of heritage while actively involving and raising awareness among connected communities.

Acknowledgement:

This research has been funded by the European Union’s Horizon Europe research and innovation programme under THETIDA project (Grant Agreement No. 101095253) (Technologies and methods for improved resilience and sustainable preservation of underwater and coastal cultural heritage to cope with climate change, natural hazards and environmental pollution).

How to cite: Katika, T., Koukoudis, K., Michalis, P., Ikiz Kaya, D., Guzman, P., Veiga-Pires, C., and Amditis, A.: Empowering Communities Through Digital Innovation and Crowdsourcing for Cultural Heritage Preservation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3517, https://doi.org/10.5194/egusphere-egu24-3517, 2024.

EGU24-3792 | ECS | Orals | CL3.2.2

Augmented Reality localization technology for Ancient Greek Heritage Exploration and Preservation 

Konstantinos Koukoudis, Tina Katika, Spyridon Nektarios Bolierakis, George Karafotias, and Angelos Amditis

CirculAR, an innovative Augmented Reality (AR) application, introduces a gamified and engaging user-environment interaction, creating a unique platform for the exploration of Ancient Greek cultural heritage. Through a blend of educational and entertaining elements, CirculAR immerses end-users in an interactive experience, leveraging localized simulation technology and visual detection to augment information and present three-dimensional (3D) models at two prominent archaeological sites and a museum. 

The AR application seamlessly integrates with the existing infrastructure of archaeological sites, enhancing the overall visitor experience by providing appealing and enjoyable interactions. CirculAR's distinctive features, including visual and audio descriptions, content manipulation, virtual tours, and a virtual agent, contribute to an inclusive and accessible immersive encounter for on-site users. The app incorporates gamified and educational components such as quizzes, animations, visualizations, and scoring mechanisms to enrich the learning experience. 

Moreover, CirculAR extends its impact beyond visitor engagement by offering an authoring tool with a user-friendly interface addressed mainly to institutions, research centers, and organizations. This tool empowers content owners to preserve, curate, and disseminate their cultural heritage data effectively. Augmented storylines within the application faithfully replicate ancient sites, drawing on 3D content design and extensive research conducted by museums and archaeological sites. 

CirculAR’s immersive nature, emphasizing archaeological elements, is positioned to contribute significantly to highlighting existing components and recovering missing fragments crucial for a comprehensive understanding of historical areas. The application aligns with long-term strategic approaches for resilience and sustainability of historical monuments by seamlessly integrating with established infrastructure and supporting the preservation and dissemination of cultural heritage data. By fostering engagement, education, and preservation, the application supports cultural heritage management and proves a valuable tool for heritage conservation and public awareness. 

CirculAR has been tested and evaluated as part of internal testing procedures; evaluating how external parameters (such as, the change of scenery, lighting, angle, and positioning affect the localized content). The application will be tested and evaluated in real-life settings the upcoming spring at the three selected locations. Part of the future advancements of CirculAR include its evolution into formidable crowdsourcing tool, leveraging enhanced algorithms and user participation to collaboratively map climate change and natural hazards affecting cultural heritage sites. This transformation will empower a diverse and interconnected user base to collectively generate valuable insights, fostering a sense of shared responsibility and innovation. 

This research is part of APSIM project and has been co‐financed by the European Union NextGenerationEU under the call RESEARCH – CREATE – INNOVATE 16971 Recovery and Resilience Facility (project code:ΤΑΕΔΚ‐06171).

How to cite: Koukoudis, K., Katika, T., Bolierakis, S. N., Karafotias, G., and Amditis, A.: Augmented Reality localization technology for Ancient Greek Heritage Exploration and Preservation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3792, https://doi.org/10.5194/egusphere-egu24-3792, 2024.

Submerged underwater cultural heritage (UCH) provides insight into past human behavior and history and thus the preservation of these artifacts at the site of discovery is crucial. However, marine environmental conditions such as physical, chemical, and biological processes directly impact the degradation of these underwater historical sites. Under the frame of the Horizon Europe project THETIDA (Technologies and methods for improved resilience and sustainable preservation of underwater and coastal cultural heritage to cope with climate change, natural hazards and environmental pollution), which runs between 2023 and 2026, the current work aims to demonstrate the suitability of process-based numerical models to (1) predict in real-time hazards threatening UCH sites associated with currents and sediment abrasion and (2) to estimate the risks associated with these oceanic conditions. This general approach is demonstrated for the Coast of Algarve (southern coast of Portugal), focusing specifically on the B-24 wreck. This WWII bomber airplane rests on the bottom of the coastal shelf at 20 m deep and approximately three kilometers offshore of Praia de Faro. The methodology couples a wave model (SWAN) to an existing operational hydrodynamic system SOMA powered by the MOHID model, which will provide inputs to run a non-cohesive sediment transport model. In-situ measurements and laboratory experiments will be used to determine deterioration rates that will provide insights into risk categorization and impacts on UCH sites. The final product will be a demonstrative operational ocean model for UCH management, assessment, and emergency response.

Acknowledgement: This research has been funded by the European Union’s Horizon Europe research and innovation programme under THETIDA project (Grant Agreement No. 101095253) (Technologies and methods for improved resilience and sustainable preservation of underwater and coastal cultural heritage to cope with climate change, natural hazards and environmental pollution). The authors also acknowledge Fundação para a Ciência e Tecnologia (FCT), under the project LA/P/0069/2020 granted to the Associate Laboratory ARNET and UID/00350/2020 CIMA (https://doi.org/10.54499/UIDP/00350/2020).

How to cite: Garzon, J. L., Mills, L., and Martins, F.: Operational hydrodynamic modeling as a tool to predict risks on underwater cultural heritage sites. Demonstration for the Algarve Coast., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3913, https://doi.org/10.5194/egusphere-egu24-3913, 2024.

EGU24-5614 | Posters on site | CL3.2.2 | Highlight

Recent past and future climate change over the TRIQUETRA cultural heritage sites and related damage risk 

Aristeidis K. Georgoulias, Dimitris Akritidis, Efstathia Tringa, Haralambos Feidas, and Prodromos Zanis

Within the framework of TRIQUETRA (Toolbox for assessing and mitigating Climate Change risks and natural hazards threatening cultural heritage; https://triquetra-project.eu/) research project, meteorological data from weather stations (observations) as well as simulations from regional climate models (RCMs) have been analyzed to assess recent past and future climate change over eight cultural heritage (CH) sites in six countries. From South to North the CH sites are Choirokoitia in Cyprus, Aegina, Epidaurus, and Kalapodi in Greece, Ventotene in Italy, Les Argilliez in Switzerland, Roseninsel in Germany, and Smuszewo in Poland. The observations were acquired from weather stations (from various networks) with long meteorological records at the proximity of the examined CH sites, while the RCM data come from the EURO-CORDEX. More specifically, 11 sets of high resolution (~12.5 km) RCM simulations were analyzed, covering the historical period 1950-2005 and the future period 2006-2100 under three different Representative Concentration Pathways (RCPs) of the Intergovernmental Panel on Climate Change (IPCC), namely the RCP2.6 (strong greenhouse gas mitigation), RCP4.5 (medium mitigation), and RCP8.5 (no further mitigation). The climate analysis over the recent-past period 1970-2020 revealed a robust warming and increasing of heat stress at the materials of the CH assets. Furthermore, the multi-model climate analysis based on the RCM simulations for the three different future scenarios points towards a hotter and drier future climate for the CH sites at the South and a hotter and wetter climate for the CH sites in the North. Analysis of the Heritage Outdoor Microclimate Risk (HMRout) and Predicted Risk of Damage (PRD) indices over the recent past period indicates notable variations in microclimate conditions with aggravation of heat stress at CH assets made of stone and marble, pointing towards an increase in predicted risk of damage. Analyzing the future changes in HMRout and PRD indices based on the multi-model ensembles of RCM simulations for the three different future scenarios will provide a more comprehensive understanding of how the resilience of materials and the overall preservation of stone and marble CH sites may be affected.

This work is based on procedures and tasks implemented within the project “Toolbox for assessing and mitigating Climate Change risks and natural hazards threatening cultural heritage - TRIQUETRA”, which is a Project funded by the EU HE research and innovation programme under GA No. 101094818.

How to cite: Georgoulias, A. K., Akritidis, D., Tringa, E., Feidas, H., and Zanis, P.: Recent past and future climate change over the TRIQUETRA cultural heritage sites and related damage risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5614, https://doi.org/10.5194/egusphere-egu24-5614, 2024.

EGU24-5619 | Orals | CL3.2.2

The TRIQUETRA Knowledge Base Platform 

Christos Kontopoulos, Anastasia Anastasiou, Efthymios Magkoufis, Apostolos Sarris, Victor Klinkenberg, Miltiadis Polidorou, Styliani Verykokou, and Vasiliki Charalampopoulou

The TRIQUETRA project seeks to establish an evidence-based assessment platform for precise risk assessment. Functioning as a Decision Support Tool, this platform aims to enhance efficiency in risk mitigation and site remediation. The TRIQUETRA project's overall approach is structured around three key elements: (i) Risk Identification, (ii) Risk Quantification, and (iii) Risk Mitigation.

Within this framework, a novel Knowledge Base Platform (KBP) has been created, serving as an electronic repository equipped with advanced search tools and capabilities. It encompasses information on Climate Change (CC), geological, historical, and site-specific data, along with risks and mitigation measures for Cultural Heritage (CH) sites based on the verified data, geographical identification and results obtained from the outputs of the project.

The primary goal of the KBP is to comprehensively integrate and visualize all shared project data, utilizing both a searchable literature database and a sophisticated WebGIS platform that adheres to the standards set by the Open Geospatial Consortium (OGC) and INSPIRE. It also incorporates various features for the deployment, cataloguing and categorisation of the data produced and shared within the project, to enhance the discoverability of the data. The KBP is structured based on two distinct key components, namely the Bibliography inventory and the WebGIS. These distinct sections of the platform gather all the data and information related to the pilot CH sites of the project. The combination of available datasets for each pilot site leads to the creation of a data cube - a multidimensional structure facilitating the efficient representation and analysis of data across various dimensions, including time and location.

It is imperative to point out that the platform will keep evolving throughout the course of the project in order to align with upcoming project outputs, enabling the fusion of different data types and efficient research on each pilot CH site. This, in turn, contributes to advancing knowledge in CH monitoring and facilitating optimal preservation and risk mitigation actions.

How to cite: Kontopoulos, C., Anastasiou, A., Magkoufis, E., Sarris, A., Klinkenberg, V., Polidorou, M., Verykokou, S., and Charalampopoulou, V.: The TRIQUETRA Knowledge Base Platform, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5619, https://doi.org/10.5194/egusphere-egu24-5619, 2024.

EGU24-8951 | ECS | Orals | CL3.2.2

Policy matrices – A tool for reviewing the effectiveness of risk management policies across scales and disciplines.  

Louis Durrant, Jacques Teller, Angela Santangelo, and Benedetta Baldassarre

Policies are a deliberate system that defines action and guides short-term decisions in pursuing a goal. Policy is a fundamental instrument of governance which is extensively used worldwide. However, not all policies are created equally. Contemporary literature is littered with examples of policy failures, and a large research emphasis is dedicated to co-creating ‘good’ policy. This challenge of developing good policy is exacerbated when we consider the rapidly evolving risks related to climate change. The evolving risks can make it difficult to define valid policy goals over the longer term. Furthermore, stakeholders are increasingly needed across policy and practice to overcome siloed working and co-create transdisciplinary risk management policies, considering both long-term strategic objectives and short- to medium-term operational solutions. Risk management policy instruments are relevant across spatial scales and engage with policies from other disciplines (urban planning, heritage conservation, environmental management). The article presents an innovative tool called the policy matrix to address challenges faced by policy experts. The policy matrix capitalises upon the co-creative research of the Organigraphs technique defined by Durrant et al. (2021) to co-create disaster risk management governance maps.  The article compares two policy matrices developed as part of a Horizon 2020-funded project called SHELTER. In its simplest form, a policy matrix arranges risk management policy instruments around an issue depending on their scale of implementation and disciplinary lens. This allows stakeholders to see all the policy instruments considered relevant to some specific issues. It can further provide stakeholders a robust platform to critique those policies.  By way of example, providing them with a tool to clearly “measure” the links between these policies, to identify policy gaps in thematic/operationalisation, or, from a practical perspective, to provide a tool for experts to review the level of participation in the design of these policies or the effectiveness of these policies in practice.

 

How to cite: Durrant, L., Teller, J., Santangelo, A., and Baldassarre, B.: Policy matrices – A tool for reviewing the effectiveness of risk management policies across scales and disciplines. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8951, https://doi.org/10.5194/egusphere-egu24-8951, 2024.

EGU24-10181 | Posters on site | CL3.2.2

Remote sensing techniques for monitoring cultural heritage sites  

Vassilia Karathanassi, Kleanthis Karamvasis, Viktoria Kristolari, Polychronis Kolokoussis, Margarita Skamantzari, and Andreas Georgopoulos

Climate change is likely to have a direct impact on tangible cultural heritage. Cultural heritage sites are already experiencing the impact of variations in temperature, precipitation, atmospheric moisture, and wind strength, along with rising sea levels and shifts in the frequency of extreme events. Leveraging remote sensing tools presents an opportunity for the effective surveillance and detection of potential threats to Cultural Heritage sites, along with monitoring the material deterioration in monuments. Since monuments are not isolated in the geographical space, assessment and evaluation of changes in their broader area are important because they serve as warning signals to the concerned stakeholders and facilitate them to take measures for preventing CH asset damages. Satellite data after appropriate processing provide significant “background” information by pointing out a) hazards with a slow or gradual onset in the broad area of the CH monuments and facilitating change assessment including ground deformation and land cover changes and b) assessing damage on both the surrounding region and the monuments after events like floods, landslides, earthquakes, etc.

Within HYPERION project (https://www.hyperion-project.eu/), RS-based methods have been developed for routine monitoring of the CH sites and were tested at four pilot sites. Routine monitoring includes displacement and land cover change detection maps of the broad area for all the pilot sites that are studied within the Hyperion project (city of Rhodes, Granada, Venice and Tønsberg), flood monitoring maps, three-dimensional models for all the CH assets, and deterioration and material loss estimation for specific parts of the facades of two monuments in the pilot site of the city of Rhodes, the Fort of Saint Nikolas and the Roman bridge in the Rhodes island.

To this end, a) advanced methodologies using PS and SBAS functionalities and Convolutional Neural Network architectures have been applied on satellite data aiming to produce reliable land deformation and land cover change detection maps, respectively, b) time series analysis and classification have been employed to identify changes in backscattering and to map flood occurrences, c) point clouds, light models, texture models and sections have been created in order to obtain a detailed 3D representation of the assets, and c) hyperspectral processing methods have been employed for fast and efficient assessment of the material deterioration level.

The effectiveness of the developed methods has been evaluated through their implementation on the pilot sites and disseminated to the scientific community through relevant publications. This paper presents a comprehensive overview of the results they have achieved and highlights the capabilities of remote sensing as a valuable tool in preserving Cultural Heritage.

Acknowledgement:
This work was implemented in the framework of the HYPERION project (H2020-LC-CLA-2018-2 H2020 program under GA 821054). Funding for participation in the conference has been provided by the HORIZON-CL2-2022-HERITAGE-01 program, with grant agreement number 101095253.

How to cite: Karathanassi, V., Karamvasis, K., Kristolari, V., Kolokoussis, P., Skamantzari, M., and Georgopoulos, A.: Remote sensing techniques for monitoring cultural heritage sites , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10181, https://doi.org/10.5194/egusphere-egu24-10181, 2024.

EGU24-11315 | Posters on site | CL3.2.2

The ARCH Resilience Assessment Dashboard: An Online Scorecard Approach to Assess the Resilience of Historic Areas 

Daniel Lückerath, Katharina Milde, Valerie Wischott, and Anna Klose

The increasing recognition of the importance of resilience in various sectors, such as disaster risk management, climate change adaptation, and urban planning resulted in a growing demand for tools and frameworks that can effectively measure and evaluate resilience. Scorecard approaches for the assessment of resilience have become more prominent in recent years. They provide a structured and quantitative way to assess resilience, allowing a monitoring of the resilience building progress of different systems or communities. In addition, the complexity and interconnectedness of modern systems requires a comprehensive assessment of resilience, considering multiple dimensions and factors. Scorecards offer a holistic view by incorporating various indicators and metrics, providing a more comprehensive understanding of resilience and its strengths and weaknesses. Scorecard approaches also facilitate decision-making and planning by providing clear and actionable information, enabling stakeholders to identify areas of improvement, prioritize interventions, and track progress over time.

Until recently, no scorecard approach for the assessment of the resilience of historic areas existed. The ARCH Resilience Assessment Dashboard (RAD) [1] closes this gap by providing an online scorecard that allows heritage managers, urban planners, disaster risk managers and other actors to jointly self-assess the resilience of their historic area.

The core of the RAD are 221 questions, categorized into ten overarching Essentials – an adapted version of the Ten Essential for Making Cities Resilient [2] – three disaster risk management phases, four topics (disaster risk management, climate change adaptation, heritage management, social justice), and six resilience dimensions (built environment, natural environment, economy, policy, society, and culture). Each question is answered on a 6-point Likert scale and supported by explanatory information, including potential stakeholders who have the information needed to answer the question.

The RAD provides users with a score, which indicates the performance in the different aspects relevant to building resilience. By analyzing the results, users can identify weak points in the resilience of the historic area. Based on these results, users can formulate a list of actions for increasing the resilience. To support this process, the RAD is linked to the ARCH Resilience Measures Inventory, an online database of resilience measures compatible with the Essentials of the RAD. By conducting several resilience assessments, the RAD can also be used to monitor resilience over time.

The RAD was co-developed and evaluated for four historic areas as part of the Horizon 2020 project ARCH (grant agreement No. 820999): the Old Town of Bratislava (Slovakia), the Old Town of Camerino (Italy), the World Heritage Site Speicherstadt and Kontorhausviertel in Hamburg (Germany), and the Huerta de Valencia (Spain).

This contribution will introduce the concept of the RAD and present the results of its trial application in the four historic areas.

References

[1] Fraunhofer IAIS, „Resilience Assessment Dashboard“, https://rad.savingculturalheritage.eu/

[2] UNDRR, “The TEN Essentials for Making Cities Resilient,” https://mcr2030.undrr.org/ten-essentials-making-cities-resilient

How to cite: Lückerath, D., Milde, K., Wischott, V., and Klose, A.: The ARCH Resilience Assessment Dashboard: An Online Scorecard Approach to Assess the Resilience of Historic Areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11315, https://doi.org/10.5194/egusphere-egu24-11315, 2024.

EGU24-12355 | Orals | CL3.2.2

Unveiling Risks and Leveraging the Knowledge Base Platform for Cultural Heritage sites in the Context of the TRIQUETRA Project 

Apostolos Sarris, Prodromos Zanis, Salvatore Martino, Anastasia Anastasiou, Charalabos Ioannidis, Styliani Verykokou, Victor Klinkenberg, and Miltiadis Polidorou

The TRIQUETRA EU research project embarks on a pioneering initiative aimed at enhancing climate change (CC) resilience in Cultural Heritage (CH) sites. Within the scope of TRIQUETRA, certain provisions have been made for studying the geological and historical climatic data towards risk identification that the pilot CH sites of the project are facing.  The geological risk quantification was based on monitoring and modelling approaches to classify the intensity of geohazards related to ground instabilities, earthquake-induced effects, coastal retreat, sea-waves, water runoff, wind storms, wildfires etc. Digital twins derived by in-filed monitoring and surveying are assumed at the basis of geohazard quantification. Similarly, the assessment of historical climatic information has been based on observations and a multi-model ensemble of high-resolution Regional Climatic Model (RCM) simulations, aiming to identify potential risks at the selected CH sites. The datasets will be used for further experimentation, and continuous collection of new data will take place throughout the course of the project, serving towards the proposal of mitigation action against the CC-induced risks. 

Similarly, emphasis was given to gather information from past initiatives and directives to create a node of reference for the future, crucial for understanding the vulnerabilities of CH sites in the face of CC. An extensive literature review on CC and other risks and mitigation measures for CH sites worldwide has been made, in addition to gathering of existing and historical site-specific data, identification of geological conditions at CH sites and classification of geological hazards associated with environmental and climatological data that pose direct or indirect risks to the pilot CH sites.

The development of the TRIQUETRA Knowledge Base platform (an electronic repository) based on the retrieved data, accompanied by advanced search tools and a “Self Service Portal” hosted on the project website (https://triquetra-project.eu/), ensures that contents related to CC, geological conditions, historical data, site-specific information, as well as risks and mitigation measures for CH sites are discoverable for future decision-making actions. The Knowledge Base platform includes a dedicated database and a WEBGIS platform, which store collected data in a common geospatial database providing a secure environment, which has an open access policy and will offer further analysis beyond the end of the project.

The above lay the groundwork for holistic research to CC resilience in CH sites. The findings presented herein not only advance the objectives of the TRIQUETRA project but also offer insights that can guide future research in the preservation of global CH in the face of an ever-evolving climate.

How to cite: Sarris, A., Zanis, P., Martino, S., Anastasiou, A., Ioannidis, C., Verykokou, S., Klinkenberg, V., and Polidorou, M.: Unveiling Risks and Leveraging the Knowledge Base Platform for Cultural Heritage sites in the Context of the TRIQUETRA Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12355, https://doi.org/10.5194/egusphere-egu24-12355, 2024.

EGU24-13431 | Orals | CL3.2.2 | Highlight

Striving for the aspiring UNESCO Global Geopark Algarvensis: Connecting Climate Change Threats with Cultural and Natural Heritage 

Cristina Veiga-Pires, Sónia Oliveira, Lídia Terra, Dália Paulo, Telma Carroço, and Luís Pereira

Since 2019, a team of scientists, technicians, and politicians from Southern Portugal has been planning and implementing a new project aimed at involving the local population in fostering sustainable development alongside the preservation and conservation of natural and cultural assets. This initiative has evolved into the aspiring UNESCO Global Geopark (aUGGp) Algarvensis, reaching maturity earlier this year when its southern territorial boundary was established at sea, aligning with a bathymetric depth of 130 meters, representing the coastline of 20,000 years ago.

Situated in the Algarve region, this territory is facing several threats associated to climate change, the most significant ones being the sea level rise, reduced rainfall and freshwater availability, and the impact of the extreme events.

The natural and cultural heritage assets are abundant, both on land, along the coast, and underwater. Given the diverse stakeholders responsible for their management based on their type, characteristics, size, and location, there has been no global and integrated approach to assessing their vulnerabilities, both specific and common. The aUGGp Algarvensis aims to rectify this by identifying, quantifying, and mitigating risks drived from natural, climatic, anthropogenic, and biological hazards across various types of heritage.

Although relatively unknown, the continental territory of the aUGGp Algarvensis boasts a rich and diverse cultural heritage, featuring over 228 listed and referenced sites encompassing various types of heritage. Over the last decades, several coastal heritage sites have vanished into the sea due to intense coastal erosion, with underwater heritage primarily appreciated by divers..

This study explores how climate change poses risks to the region's geological, cultural, and ecological features. It emphasizes the intricate relationship between environmental changes and heritage preservation within the context of the UNESCO Global Geopark Algarvensis initiative. Our goal is to not only present the survey and compilation data gathered so far under the aUGGp Algarvensis coordination but also to underscore the importance and impact that such a local/regional non-governmental structure can bring to implement an efficient and proactive management strategy in the face of evolving risks to heritage.

 

Acknowledgement:  

This study had the support of national funds through Fundação para a Ciência e Tecnologia (FCT), under the project LA/P/0069/2020 granted to the Associate Laboratory ARNET and UID/00350/2020 CIMA, as well as from the Municipalities of Loulé, Silves and Albufeira.

How to cite: Veiga-Pires, C., Oliveira, S., Terra, L., Paulo, D., Carroço, T., and Pereira, L.: Striving for the aspiring UNESCO Global Geopark Algarvensis: Connecting Climate Change Threats with Cultural and Natural Heritage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13431, https://doi.org/10.5194/egusphere-egu24-13431, 2024.

EGU24-15540 | ECS | Orals | CL3.2.2 | Highlight

Using Impact Chains for Co-creating Cause-Effect Models of Climatic and Anthropogenic Hazards in Cultural Landscapes 

Valerie Wischott, Anna Klose, Katharina Milde, and Daniel Lückerath

Cultural landscapes represent the intersection of natural and cultural heritage, encompassing the physical environment as well as the cultural practices, traditions, and values associated with a specific place. These landscapes often have important socioeconomic and community dimensions, serving as centers of livelihoods, tourism, and community identity. Moreover, these landscapes have intrinsic value and contribute to the overall diversity and richness of our global heritage. They hold stories, knowledge, and traditions that connect us to our past and shape our collective identity.

Climatic and anthropogenic hazards pose significant risks to these landscapes, including the degradation or loss of cultural heritage sites, changes in traditional land-use practices, and the erosion of cultural identities and knowledge systems.

To understand and evaluate these potential impacts, helping to safeguard and preserve the cultural significance and integrity of these landscapes, it is necessary to identify the specific risks and vulnerabilities that cultural landscapes face, allowing for the development of targeted adaptation strategies, enabling proactive measures to mitigate the impacts and ensure the resilience and continuity of these landscapes for future generations.

One widely adopted tool for risk assessments are Impact Chains [1], i.e., cause-effect models that describe the relationship between a hazard (e.g., a storm surge, a heatwave), exposed elements (e.g., residents, birdlife, agricultural practices) and their vulnerability (e.g., dike maintenance practices), and resulting impacts (e.g., coastal erosion). Impact Chains are composed of all these elements and additionally, intermediate impacts, i.e., cascading effects related to hazard and vulnerability elements. Impact Chains are typically developed through participative processes that involve local stakeholders. These stakeholders provide valuable input and feedback for the development of the Impact Chain. The validated Impact Chain provides a structured representation of the cause-effect relationships associated with the investigated risk.

Until now, Impact Chains have mainly been used as a basis for indicator-based Climate Risk and Vulnerability Assessments from the national to the local level, but not for modelling anthropogenic hazards like over-tourism or the abandonment of agricultural practices. In addition, only few Impact Chains for cultural sites have been developed.

In this contribution, we present Impact Chains that have been developed for five cultural landscapes as part of the Horizon Europe project RescueME (GA No. 101094978) and cover both climatic as well as anthropogenic hazards. These Impact Chains have been developed within case studies of the island of Neuwerk in the Waddensea of Hamburg (Germany), the Huerta and Albufera de Valencia (Spain), the Defensive System of the City of Zadar (Croatia), the region of Portovenere, Cinque Terre and the Islands (Italy), and the UNESCO Geopark in Crete (Greece). This contribution will describe the co-creation process for Impact Chain development, the involved stakeholder types, as well as the adaptations made to the standard Impact Chain representations [1].

 

References

[1] GIZ (2016). The Vulnerability Sourcebook. https://www.adaptationcommunity.net/download/va/vulnerability-guides-manuals-reports/vuln_source_2017_EN.pdf.

How to cite: Wischott, V., Klose, A., Milde, K., and Lückerath, D.: Using Impact Chains for Co-creating Cause-Effect Models of Climatic and Anthropogenic Hazards in Cultural Landscapes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15540, https://doi.org/10.5194/egusphere-egu24-15540, 2024.

EGU24-16558 | Posters on site | CL3.2.2

Effects of environmental stresses and climate change on the deterioration of underwater cultural heritage: the THETIDA approach 

Claudio Mazzoli, Ludovica Pia Cesareo, Chiara Coletti, Luigi Germinario, Lara Maritan, Loriano Ballarin, Isabella Moro, Stella Demesticha, Flávio Martins, Fabio Ruberti, and Panagiotis Michalis

This research, conducted within the THETIDA project (https://thetida.eu), focuses on identifying threats posed by climate change to underwater cultural heritage sites, with a specific emphasis on the diverse risks – both direct and indirect – that endanger metallic materials, such as anchors, cannons, and structural elements. Notable pilot sites within THETIDA include the US Army WWII PB4Y-1 bomber aircraft Liberator off the coast of Praia de Faro (Portugal), the sunken submarine chaser Equa near La Spezia, and an Ottoman shipwreck in Famagusta bay, Cyprus. These sites offer varied historical backgrounds, construction materials, and biological ecosystems, enabling a comprehensive comparison between sites protected in bays and those in dynamic open ocean environments with currents, sediment dynamics, and biological actions influencing deterioration processes [1].

Being aware of successive reports of the Intergovernmental Panel on Climate Change (IPCC), documenting climate phenomena such as rising sea levels, ocean surface temperature increases, ocean acidification, changes in ocean circulation, extreme wave events and deoxygenation [2], the objectives of the research are to investigate the deterioration effects associated with climate change, assess their evolution across different environments, and develop prediction models. The ultimate goal is to provide practical recommendations for site preservation. The methodology involves studying the sites, historical backgrounds, material compositions, and deterioration characteristics, including physical, chemical, and biological factors of underwater weathering, classification of decay patterns, biocolonisation and biodeterioration characteristics through a multidisciplinary approach. In underwater heritage sites, materials undergo physical, chemical, and biological changes influenced by water, sediment, and living organisms [3, 4]. The study will consider variables such as temperature, salinity, pH, oxygen levels, and the intensity and direction of currents, alongside the depth and location of the site. Mock-up samples will undergo accelerated weathering and autoclave corrosion tests to observe the degradation related to specific environmental parameters. Mock-up samples will also be placed in the real sites to compare the results with the controlled environment aged samples and explore the early stages of deterioration and biocolonisation.

This research contributes to understanding the impact of climate change on underwater cultural heritage sites, providing valuable insights for preservation efforts in the face of evolving environmental challenges.

Acknowledgement:

This research has been funded by European Union’s Horizon Europe research and innovation programme under the THETIDA project (Grant Agreement No. 101095253) (Technologies and methods for improved resilience and sustainable preservation of underwater and coastal cultural heritage to cope with climate change, natural hazards, and environmental pollution).

 

References

[1] THETIDA project websites https://thetida.eu/#/home

[2] Gregory et al. (2022). Of time and tide: the complex impacts of climate change on coastal and underwater cultural heritage. Antiquity 96.390: 1396-1411 (https://doi.org/10.15184/aqy.2022.115).

[3] Gregory (2009). In situ preservation of marine archaeological sites: Out of sight but not out of mind. In: Situ Conservation of Cultural Heritage: Public, Professionals and Preservation; Richards, V., Mckinnon, J. (Eds) 1-16.

[4] Bethencourt et al. (2018). Study of the influence of physical, chemical and biological conditions that influence the deterioration and protection of Underwater Cultural Heritage. Sci. Total Environ. 613: 98-114 (http://dx.doi.org/10.1016/j.scitotenv.2017.09.007).

 

How to cite: Mazzoli, C., Cesareo, L. P., Coletti, C., Germinario, L., Maritan, L., Ballarin, L., Moro, I., Demesticha, S., Martins, F., Ruberti, F., and Michalis, P.: Effects of environmental stresses and climate change on the deterioration of underwater cultural heritage: the THETIDA approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16558, https://doi.org/10.5194/egusphere-egu24-16558, 2024.

EGU24-17228 | Orals | CL3.2.2 | Highlight

The Green Cluster of Cultural Heritage: Climate Effects TeamEU funded projects  

Athanasios Gerakis, Jens Hemmelskamp, Irena Kowalczyk-Kedziora, and Melpomeni Vyzika

Europe’s built heritage, cultural landscapes and sites are under immediate threat from the effects of climate change, including rising sea levels, prolonged droughts, floods, and strong storms. Acid rain and other environmental pollutants cause wear and defacement of monuments and historic buildings, while soil erosion accelerates the deterioration of underwater and coastal heritage sites. The effects of climate change also affect, directly or indirectly, indoor cultural heritage.

Horizon Europe, the 9th European Framework Programme for Research and Innovation (2021-2027), is a key instrument of the Union to tackle global challenges such as the impact of climate change and natural disasters on cultural assets, as well as to promote cooperation and the influence of research and innovation in the design, support, and implementation of EU policies. To further enhance efficiency and research collaboration, the European Commission (EC) clusters the consortia with similar research objectives during their lifecycle. The idea is to facilitate researchers to share insights and best practices, identify synergies for dissemination and communication actions, and propose integrated feedback recommendations to policy makers in the EC and beyond.

Since 2021, three calls for proposals have invited research teams to respond to the demands for more sustainable methods and technologies to restore monuments and works of art[i], the impact of climate change and natural hazards on cultural heritage[ii], and advanced technologies for remote monitoring in the field[iii]. The eleven projects selected for the EU funding have been encouraged to form the Green Cluster on Cultural Heritage.

Within the Green Cluster, the ‘’Climate Effects’’ Team, currently composed of four active EU projects (THETIDA, RescueME, TRIQUERTA, STECCI), has an overarching aim to address the urgent need to protect monuments, historic buildings, and sites from the diverse impacts of climatic risks, natural and anthropogenic hazards. This is expected to contribute to the conservation and protection of Europe’s heritage by exploiting cutting-edge remote monitoring technologies and modelling tools for multi-hazard risk understanding and better preparedness.

Research within the Green Cluster is complemented by other consortia that develop sustainable methodologies, materials and techniques for the preservation and restoration of art objects and explore the use of advanced and sophisticated technologies for more accurate, targeted, and reliable remote monitoring purposes.

The impact of the scientific research is furthermore amplified by the active involvement of Artificial Intelligence tools, a wide range of community groups, stakeholders, and participants covering the full spectrum of ongoing research activities. This includes participatory and inclusive approaches, such as citizen science and participatory Living Lab methodologies.

The overall goal of the EC is to support transdisciplinary joint efforts of researchers to develop sustainable preservation and adaptation plans, and to bring community involvement and inclusiveness to the forefront of large collaborative research projects funded by the EU. The long-term outcome will be the creation of a sustainable cultural heritage research ecosystem.


[i] https://ec.europa.eu/info/funding-tenders/opportunities/portal/screen/opportunities/topic-details/horizon-cl2-2021-heritage-01-01

[ii] https://ec.europa.eu/info/funding-tenders/opportunities/portal/screen/opportunities/topic-details/horizon-cl2-2022-heritage-01-08

[iii] https://ec.europa.eu/info/funding-tenders/opportunities/portal/screen/opportunities/topic-details/horizon-cl2-2023-heritage-01-01

 

 

How to cite: Gerakis, A., Hemmelskamp, J., Kowalczyk-Kedziora, I., and Vyzika, M.: The Green Cluster of Cultural Heritage: Climate Effects TeamEU funded projects , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17228, https://doi.org/10.5194/egusphere-egu24-17228, 2024.

EGU24-17678 | ECS | Orals | CL3.2.2

A baseline approach for downscaling the Euro-CORDEX data for wind risk assessment of the Metsovo village in Greece 

Akrivi Chatzidaki, Dimitrios Vamvatsikos, Fotios Barmpas, Antti Hellsten, Mikko Auvinen, and George Tsegas

A methodology is presented for downscaling the wind projections of Euro-CORDEX in order to derive temporally and spatially correlated region-wide wind fields that can be used for assessing the wind risk for cultural heritage sites. The coarse spatial and temporal resolutions of the Euro-CORDEX projections prohibit their use as a direct input for such purposes, especially for cultural heritage assets that are spatially distributed within the Euro-CORDEX grid and dynamically respond differently to wind. To improve the temporal resolution of the Euro-CORDEX data, we leverage machine learning tools and weather station measurements, aiming to generate composite “Frankenstein” days at the locations of the weather stations that comprise 144 jigsaw pieces of actually measured 10min wind time-series that are matched together to form a continuous daily record. The “Frankenstein” days are expanded spatially to all locations where critical assets can be found by employing spatially distributed wind fields that are computed via high-fidelity computational fluid dynamics simulations and provide contemporaneous wind values at all locations of interest. This process allows generating “Frankenstein” days and wind fields with a temporal resolution of 10min and spatial resolution that allows assessing the wind risk for spatially distributed assets. As a case study, the Euro-CORDEX wind projections are downscaled for the cultural heritage village of Metsovo that is found at the Western part of Greece. Most of the buildings within this village are made of stone masonry and tiled roofs and are vulnerable to extreme wind actions as wind can cause damages e.g., on the tiled roofs thus making the buildings vulnerable to rainfall, or even lead to their partial or complete failure. Thus, the Frankenstein days and wind fields are employed for assessing the wind risk for the cultural heritage buildings of Metsovo both on an event-basis and in the long-term.

How to cite: Chatzidaki, A., Vamvatsikos, D., Barmpas, F., Hellsten, A., Auvinen, M., and Tsegas, G.: A baseline approach for downscaling the Euro-CORDEX data for wind risk assessment of the Metsovo village in Greece, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17678, https://doi.org/10.5194/egusphere-egu24-17678, 2024.

EGU24-18072 | ECS | Orals | CL3.2.2 | Highlight

Unveiling End Users Needs and Requirements for Coastal and Underwater Heritage Sites under the impacts of Climate Change  

Sónia Oliveira, Cristina Veiga-Pires, Deniz Ikiz Kaya, Panagiotis Michalis, and Claudio Mazzoli

Coastal and underwater cultural heritage play a crucial role in local and regional cultural resources. However, this tangible cultural heritage is under threat due to extreme weather events, changing conditions caused by climate change, natural hazards, and environmental pollution. This study aims to understand how end users (entities or people related to or who interact with heritage sites ) perceive these risks and what they need to better cope, adapt, or be resilient to the anticipated changes. Additionally, it explores how science can address the needs and requirements of local and regional end users.

This research is part of the larger THETIDA project, focusing on technologies and methods for improved resilience and sustainable preservation of underwater and coastal cultural heritage, funded by the European Union’s Horizon 2020 research and innovation programme. The THETIDA project concentrates on seven pilot sites, comprising coastal locations such as Svalbard in Norway, Ijsselmeer in the Netherlands, Mykonos in Greece, and underwater sites including Algarve in Portugal, Gallinara and Spezia in Italy, and Paralimni in Cyprus.

The THETIDA team conducted surveys to analyze threats, needs, and preservation requirements for each pilot site, incorporating data from consortium partners and workshops held with local stakeholders in several pilot sites. The results identified material deterioration and human-induced development interventions as primary threats. Essential needs include assessing risk and exposure to various hazards, implementing conservation measures for buildings and sites, and promoting awareness, education, and training.

Survey responses unanimously emphasize the critical requirement for site assessment and risk evaluation concerning both human-induced and climate changes. These findings offer valuable insights for developing tools and services within the project to support local and regional end users. Furthermore, they underscore the importance of fostering a scientific culture among communities, a role that science centers and museums can fulfill, as verified during the 2023 Portuguese Science and Technology Week.

Finally, the resulting end-user ecology is integrated into the Living Lab methodology, another facet of THETIDA Project research, aiming to co-create, test, and validate a new crowdsourcing tool in real-life contexts.

 

Acknowledgement:  

This research has been funded by European Union’s Horizon Europe research and innovation funding under Grant Agreement No: 101095253, THETIDA project (Technologies and methods for improved resilience and sustainable preservation of underwater and coastal cultural heritage to cope with climate change, natural hazards and environmental pollution). Authors would also like to acknowledge the financial support of the Portuguese Foundation of Science and Technology (FCT) to CIMA through UID/0350/2020

How to cite: Oliveira, S., Veiga-Pires, C., Ikiz Kaya, D., Michalis, P., and Mazzoli, C.: Unveiling End Users Needs and Requirements for Coastal and Underwater Heritage Sites under the impacts of Climate Change , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18072, https://doi.org/10.5194/egusphere-egu24-18072, 2024.

EGU24-19282 | ECS | Orals | CL3.2.2

Risk of falling stone material on the Ramps of Piazzale Michelangelo in Florence 

Anna Palamidessi, Emanuele Intrieri, Teresa Salvatici, Irene Centauro, and Carlo Alberto Garzonio

The Ramps of Piazzale Michelangelo (Michelangelo Square) in Florence are a pedestrian connection between the Arno riverside and the higher Piazzale Michelangelo, leaning against the side of the hill called "Monte alle Croci," a hill delimiting Florence to the south. Over the years, this area has experienced a long series of instabilities that have affected some of the most significant testimonies of the city's architecture. The Ramps of Piazzale Michelangelo are popular both with tourists visiting the city and with the residents of Florence, who use them as a picturesque place to stroll.

The Ramps and contiguous Viale dei Colli (Hills Avenue) are one of the most interesting projects of the architect Giuseppe Poggi during the period when Florence was the capital of Italy (1865-1871). The staircases of the Ramps feature stone balustrades, topped with Pietraforte sandstone caps. Geologically, Pietraforte is a turbiditic sandstone characterized by numerous sedimentary layers typical of the Bouma sequence and by the presence of secondary calcite veins. These features are the main weak points where detachment phenomena can occur.

The action of rainwater leads to the dissolution of calcium carbonate, present both in the calcite veins and in the carbonatic cement within the rock. In the first case, this mechanism can result in the decohesion of the rock with the complete opening of veins and possible detachment and fall of blocks (even blocks with volume up to about 50 dm3). In the second case, detachments occur as a superficial exfoliation rather than detachments of entire portions of material.

Recent restoration works, completed in May 2019, focused on the conservation and recovery of architectural elements. However, in July 2020, a wedge collapsed, hitting a vehicle below. Subsequently, as a temporary countermeasure, the parapets were covered with nets to prevent new possible accidents.

For a long-term countermeasure, this architectural problem has been investigated assimilating it to a rockfall scenario. First of all it was necessary to manually detect and evaluate every block's discontinuity to assess susceptibility. An equation for calculating the risk of each identified block was then implemented. Differentiated interventions were proposed for each block based on its possible kinematics.

Using an approach based on statistical analysis of the rockfall’s susceptibility, this study aims to: 1) Quantify the spatial distribution of rockfalls; 2) Build an equation to identify the more dangerous blocks; 3) Propose safety interventions with minimal impact, diversifying them based on the kinematics of each individual block.

 

Keywords: Cultural Heritage, Stone element risk, rockfall, road safety, susceptibility.

How to cite: Palamidessi, A., Intrieri, E., Salvatici, T., Centauro, I., and Garzonio, C. A.: Risk of falling stone material on the Ramps of Piazzale Michelangelo in Florence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19282, https://doi.org/10.5194/egusphere-egu24-19282, 2024.

EGU24-20296 | Orals | CL3.2.2 | Highlight

The EU R&I Task Force for Climate Neutral and Resilient Historic Areas 

Katherine Peinhardt, Dr. Cristina Garzillo, Dr. Daniel Lückerath, Aitziber Egusquiza, Panagiotis Michalis, and Denis Istrati

Climate change poses a significant and alarming threat to cultural and natural heritage in urban and rural areas, jeopardizing the preservation of tangible and intangible aspects of our shared human history, including cultural traditions, knowledge, and practices. Rising sea levels, extreme weather events, and increased temperatures contribute to the degradation of cultural sites. Coastal regions face the imminent danger of inundation and erosion, endangering landscapes that have withstood centuries. At the same time, Indigenous communities are vulnerable, as their cultural heritage is often intricately connected to specific ecosystems and landscapes. On top of these climatic threats, cultural and natural heritage is also threatened by impacts from anthropogenic stresses, like unsustainable tourism and consumption patterns or environmental pollution.

Against this backdrop the H2020 projects ARCH, HYPERION, and SHELTER founded the EU R&I Task Force for Climate Neutral and Resilient Historic Urban Districts in 2021. The task force aims to bring together diverse groups of practitioners, researchers, and policy makers at the cross section of heritage management, climate change adaptation / mitigation, disaster risk management, and sustainable development. This coincides with the objective to identify and discuss current developments in research and practice; bridge knowledge gaps between these fields; boost collaboration among the cross-sectoral actors involved; and ultimately make our historic areas more climate neutral and resilient. In doing so, the task force aims to provide practical support to European authorities and decision makers for developing harmonised, evidence-based policies, strategies, and procedures. The Task Force has thus far convened three times: June and December 2021, and June 2022, and resulted in a joint white paper, Paving the Way for Climate Neutral and Resilient Historic Districts.

With the successful conclusion of the three funding projects, the work of organizing the task force has been taken over by their follow-up projects RescueME, THETIDA, and TRIQUETRA in 2023, shifting the focus from urban districts to historic areas, encapsulating cultural and natural heritage in urban and rural areas and other cultural landscapes, including coastal and underwater heritage.

In this presentation, we present the last results of the task force, the way forward regarding its development and activities within the updated partnership, and potential collaboration opportunities with other initiatives, projects, and actors.

How to cite: Peinhardt, K., Garzillo, Dr. C., Lückerath, Dr. D., Egusquiza, A., Michalis, P., and Istrati, D.: The EU R&I Task Force for Climate Neutral and Resilient Historic Areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20296, https://doi.org/10.5194/egusphere-egu24-20296, 2024.

Cultural Heritage (CH) monuments are often subject to various environmental threats, with climate change (CC) exacerbating their vulnerability. These historical sites, valuable for their cultural and archaeological significance, face increasing risks of deterioration due to land deformation, flooding, acid rain, erosion, and man-made hazards like illegal excavations. Such threats not only endanger the structural integrity of these monuments but also risk depriving humanity of crucial archaeological information and artifacts, which are key to understanding our collective past.

This article explores a novel approach that leverages the capabilities of satellite-based remote sensing techniques for monitoring CH sites under shallow water conditions. A wide array of data will be used for a more frequent and comprehensive analysis of the site's condition over time, enabling the detection of subtle changes that might go unnoticed with conventional methods.

The case study focuses on the submerged port of Amathous archaeological site along the coast of Cyprus. The site's unique geographical and historical characteristics make it an exemplary model for applying advanced remote sensing technologies.

By integrating satellite data with on-site ground truth measurements (topographical and aerial-born imagery), the study aims to develop a robust framework for the preservation and protection of underwater CH sites. This approach can not only enhances the understanding of the impacts of CC and human activities on these sites but also paves the way for developing proactive measures to safeguard heritage assets. The findings from this study are expected to contribute significantly to the field of heritage conservation, offering scalable and efficient solutions to monitor and protect CH sites worldwide.

How to cite: Abate, D., Kalogeriou, E., Themistocleous, K., and Hadjimitsis, D.: Change detection monitoring of archaeological sites submerged in shallow waters using remote sensing data: the case study of the port of the Ancient Amathous in Cyprus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20439, https://doi.org/10.5194/egusphere-egu24-20439, 2024.

EGU24-20699 | Posters on site | CL3.2.2

Digitalizing historical buildings of Western Greece – from point clouds, to building information modeling and 3D printing 

Theodora Filippa, Panagiotis Tsikas, Aggeliki Kyriou, Panagiotis Triantafyllidis, Epameinondas Lyros, Konstantinos Nikolakopoulos, Ioannis Koukouvelas, and Christoforos Pappas

Cultural heritage worldwide is of great interest for general public and scientific communities across disciplines. In the Mediterranean region, and in Greece in particular, historic buildings and monuments are widespread. Ongoing environmental change, and the increased frequency and severity of climatic extremes and natural hazards in the Mediterranean regions, challenge the protection of cultural heritage, making essential the detailed documentation and digitalization of these monuments in tailored geodatabases. In the present study, example historical buildings of Western Greece were selected, covering a wide environmental gradient from coastal to mountainous landscapes, namely, a 19th century emblematic stone-built lighthouse at Cape Drepano, close to Patras, in Northern Peloponnese, as well as historical buildings in the Aetolia-Acarnania region, including 19th and 20th century monuments in the lagoon region of Messolonghi (the Old Hatzikosta Hospital and the Palamas School), as well as a 18th century post-Byzantine monastery located in a mountainous area near Agrinio. Geodetic field surveys were conducted with Terrestrial Laser Scanning (TLS) and Unmanned Aerial Vehicle (UAV) photogrammetry. The collected point clouds were processed to generate Building Information Models (BIMs) of the examined structures which were then 3D printed at scale. The derived digital database of these monuments offers a detailed documentation and baseline of the present status of these monuments. This baseline, when combined with future field surveys, set the basis for accurate monitoring of the response of these structures to natural and anthropogenic stressors (e.g., costal erosion, land displacement, etc.). Moreover, this documentation could assist the efficient planning of maintenance and restoration interventions, while the derived digital and printed 3D models offer tangible tools for raising public’s awareness and valorizing further these historical buildings. Technological advancements in geodetic instruments as well as the continuous development of numerical tools for BIM applications, 3D modeling and printing, facilitate the seamless digitalization of cultural heritage and its archiving into interactive geodatabases, complementing existing efforts towards coordinated documentation and monitoring of historical buildings at national and international levels.

How to cite: Filippa, T., Tsikas, P., Kyriou, A., Triantafyllidis, P., Lyros, E., Nikolakopoulos, K., Koukouvelas, I., and Pappas, C.: Digitalizing historical buildings of Western Greece – from point clouds, to building information modeling and 3D printing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20699, https://doi.org/10.5194/egusphere-egu24-20699, 2024.

EGU24-20848 | Posters on site | CL3.2.2

TRIQUERTA: Towards next generation risk assessment and mitigation of climate change and natural hazards threatening cultural heritage 

Charalabos Ioannidis, Constantine Spyrakos, Styliani Verykokou, Denis Istrati, Sofia Soile, Vasiliki (Betty) Charalampopoulou, and Panagiotis Georgiadis

Cultural heritage (CH) sites face increasing risks from climate change (CC) and various hazards, posing threats such as rising sea levels, extreme weather events, and environmental degradation, endangering their preservation and long-term existence. A lot of research has been done on protecting CH sites, but we still lack systemic approaches towards identifying and mitigating risks to CH sites. The TRIQUETRA EU research project proposes a technological toolbox and a methodological framework for tackling climate change risks and natural hazards threatening CH, in the most efficient way possible. The main strategic objectives of TRIQUETRA include: the creation of a repository of knowledge on effects of CC and natural hazards on CH, including lessons learnt from existing mitigation measures; the implementation of a systemic approach towards identification of upcoming risks and hazards to CH; and the usage of novel technologies allowing efficient and accurate quantification of threats to CH.

The TRIQUETRA project’s methodology is structured around three fundamental stages: (i) identifying risks, (ii) quantifying risks, and (iii) mitigating risks, forming what is known as the “trifecta” approach. This approach constructs a robust framework for evaluating and addressing the following categories of risks: (i) climate-related risks; (ii) extreme water, snow and ice hazard risks; (iii) geological and geophysical risks; and (iv) chemical and biological hazard risks. Furthermore, it assesses the damage and failure modes of CH structures as well as the compounded effects of various environmental stressors on CH sites. TRIQUETRA will be validated in eight different CH sites across Europe. The main project results can be summarized as follows:

  • a novel risk quantification framework for CH sites;
  • an expanded knowledge base platform;
  • a decision-support platform (TRIQUETRA DSS) including risk severity quantification tools and mitigation measure selection and optimization tools;
  • novel protective materials;
  • a novel flash LiDAR;
  • water quality analysers; and
  • a CH site digitization framework.

How to cite: Ioannidis, C., Spyrakos, C., Verykokou, S., Istrati, D., Soile, S., Charalampopoulou, V. (., and Georgiadis, P.: TRIQUERTA: Towards next generation risk assessment and mitigation of climate change and natural hazards threatening cultural heritage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20848, https://doi.org/10.5194/egusphere-egu24-20848, 2024.

EGU24-21295 | ECS | Posters virtual | CL3.2.2

A framework for Resilient Cultural heritage 

Manal Ginzarly and Jacques Teller

It is acknowledged by International declarations and policy guidance documents that cultural heritage (CH) can contribute directly to many of the Sustainable Development Goals (SDGs), including resilience and adaptation to climate change (SDG 13). CH can support climate change action as it conveys local knowledge that builds resilience for change through mitigation and adaptation. Moreover, the vulnerability of the built environment to climate change possesses inherent resilient properties that allow it to resist damage. The integration of policies and practices of CH conservation into the wider framework of sustainable urban development entails the application of a landscape approach that (i) responds to local cultural contexts and value systems, (ii) integrates distinct theoretical perspectives to address the complex layering of the spatial, mental, and functional process-related dimensions of the landscape, and (iii) addresses policies and governance concerns at international and local levels (Ginzarly et al., 2019). Yet, the application of a landscape approach to CH conservation in the context of climate change is faced with different challenges.
First, while at the turn of the twenty-first century the concept of CH has extended from monuments to cultural landscapes and cities as living heritage, assessment processes have been slow to evolve and address the interdisciplinary nature of heritage (Déom & Valois, 2020). Second, there is a challenge around assessing the vulnerability of CH to climate change and integrating its vulnerability status into the broader context of sustainable urban development. This challenge is imposed by the lack of a framework that addresses landscapes rather than heritage sites in isolation (Cook et al., 2021).
To address the above-mentioned challenges, this presentation presents a landscape people-centered conceptual framework for resilient CH that is applicable at the city scale (i) to map how different stakeholder groups value heritage in the context of climate change, (ii) using social networks as a tool to engage communities and get access to information about heritage values, and (iii) assess the vulnerability of urban heritage and its associated values to climate change.The conceptual framework is structured around four prominent themes: (1) the city is a living heritage that encompasses the physical, mental, and digital heritage landscapes; (2) digitally mediated heritage practices provide new prospects for digitally-enabled forms of co-creation of heritage values; (3) longitudinal records on social media serve as a data source for the assessment of heritage values and their vulnerability to change; and (4) online communities contribute to communities’ disaster resilience.


References
Cook, I., Johnston, R., & Selby, K. (2021). Climate Change and Cultural Heritage: A Landscape Vulnerability Framework. The Journal of Island and Coastal Archaeology, 16(2–4), 553–571.Déom, C., & Valois, N. (2020). Whose heritage? Determining values of modern public spaces in Canada. Journal of Cultural Heritage Management and Sustainable Development, 10(2), 189–206.
Ginzarly, M., Houbart, C., & Teller, J. (2019). The Historic Urban Landscape approach to urban management: A systematic review. International Journal of Heritage Studies, 25(10), 999–1019.

How to cite: Ginzarly, M. and Teller, J.: A framework for Resilient Cultural heritage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21295, https://doi.org/10.5194/egusphere-egu24-21295, 2024.

EGU24-1823 | ECS | Orals | CL3.2.3

Estimating Breakpoints between Climate States in Paleoclimate Data  

Kathrine Larsen, Mikkel Bennedsen, Eric Hillebrand, and Siem Jan Koopman

This study presents a statistical approach for identifying transitions between climate states, referred to as breakpoints in the econometric literature, using well-established econometric tools for breakpoint detection. We analyze a record of the stable oxygen isotope ratio 𝛿18O, covering 67.1 million years, derived from benthic foraminifera. The dataset is presented in Westerhold et al. (2020) [Science 369, 1383-1387], where the authors use recurrence analysis to identify six climate states: Warmhouse I, Hothouse, Warmhouse II, Coolhouse I, Coolhouse II, and Icehouse, and thus five transitions.

Estimation necessitates a constant observation frequency. We employ mean binning. We explore three model specifications. The first model is a state-dependent mean model, which is equivalent to modeling an abrupt break in the mean of 𝛿18O for each climate state. The second model expands this by including a state-independent autoregressive term, which can be interpreted as making the transitions between states more gradual. The final model expands on the second model by letting the autoregressive term be state-dependent as well, allowing for state-specific autoregressive dynamics. All models incorporate an error term with state-dependent variance.

Fixing the number of breakpoints to five, the resulting breakpoint estimates closely align with those identified by Westerhold et al. (2020) across various binning frequencies and model specifications, demonstrating the robustness of the approach and corroborating the dating of the climate states of Westerhold et al. (2020) with time series analysis. Our approach offers the advantage of constructing confidence intervals for the breakpoints, providing a measure of estimation uncertainty, and it allows testing for the number of breakpoints in the time series.

In conclusion, our study presents a statistically rigorous approach to identifying transitions between climate states as well as their confidence intervals and the number of breakpoints.

How to cite: Larsen, K., Bennedsen, M., Hillebrand, E., and Koopman, S. J.: Estimating Breakpoints between Climate States in Paleoclimate Data , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1823, https://doi.org/10.5194/egusphere-egu24-1823, 2024.

EGU24-1911 | ECS | Orals | CL3.2.3

From Global Mean Temperature to Regional Climate Impacts 

Christopher Wells and Christopher Smith

There is strong motivation in Integrated Assessment Modelling to generate methods for quickly approximating regional climate impacts. Here, we use climate impacts from the Inter-Sectoral Impacts Model Intercomparison Project phase 2b (ISIMIP2b) to emulate impacts based on global mean surface temperature anomaly, beginning with crop yields and extending the analysis to other sectors. Unlike many existing methods, we emulate impacts directly, rather than first emulating regional climate. We find that a second order polynomial function of global mean temperature is a very good predictor of changes in regional crop yield, in line with existing research on damage function literature. Socio-economic and other drivers must be treated with care in the process. By using multiple driving climate models and impact models that are available for many impacts in ISIMIP, we are also able to sample uncertainty in the severity in changes in impacts with increasing warming.

We built our climate impacts emulator for the 10 regions considered by the IPCC for the Sixth Assessment Working Group 3 report, but the selection of regions is flexible, and could be applied to any existing IAM. Our impacts emulator can also be used to construct updated damage functions for use in economic models and cost-benefit IAMs.

This approach will be used to generate climate impact functions within the newly created FRIDA integrated assessment model, which seeks to account for feedbacks between all components of the human-Earth system – such as the climate, food systems, and energy production – as these are key drivers of the response to anthropogenic forcing.

How to cite: Wells, C. and Smith, C.: From Global Mean Temperature to Regional Climate Impacts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1911, https://doi.org/10.5194/egusphere-egu24-1911, 2024.

EGU24-1944 | ECS | Posters on site | CL3.2.3

Climate Shifts: Measuring the Impact on Overnight Stays in Italy 

Nguyen Thanh Thanh Duong, Andrea Guizzardi, and Flavio Maria Emanuele Pons

This research quantitatively assesses the impact of climate change on Italy's tourism industry, emphasizing the consequential effects on enterprise turnover and local authorities' fiscal revenues. The study aims to enhance stakeholder capabilities through diagnostic skills, addressing both immediate and long-term climate impacts on overnight stays. Employing innovative statistical and predictive tools, supported by cutting-edge ICT technologies, the research explores the symbiotic relationship between climate dynamics and regional income.

Utilizing a comprehensive database merging socio-economic and meteorological data, an econometric framework is established. Overnight stays serve as the dependent variable, with GDP and CPI as economic factors and climate data sourced from the ERA5 reanalysis dataset. Atmospheric variables include monthly climate indicators of 2-meter temperature, solar radiation and cumulated precipitation at the NUTS 2 level, and monthly weather regimes indices obtained from EOF analysis. Additionally, a categorical variable incorporating extreme events (floods, storms, heatwaves, cold spells) from the EM-DAT database is considered. The study spans January 1990 to August 2023, offering insights into the intricate relationships between climate change, economic impacts on tourism, and the historical and present causal links with overnight stays. These findings contribute to strategies promoting sustainability and resilience in tourism destinations amid climate change challenges.

How to cite: Duong, N. T. T., Guizzardi, A., and Pons, F. M. E.: Climate Shifts: Measuring the Impact on Overnight Stays in Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1944, https://doi.org/10.5194/egusphere-egu24-1944, 2024.

EGU24-6786 | ECS | Orals | CL3.2.3 | Highlight

Flipping the cost of tipping? Economic impacts of reduced AMOC carbon drawdown 

Felix Schaumann and Eduardo Alastrué de Asenjo

Social cost of carbon (SCC) research has paid increasing attention to climate tipping points and feedback mechanisms. The weakening of the Atlantic Meridional Overturning Circulation (AMOC) is currently treated as a global benefit, as it would lower Northern Hemisphere surface temperatures and thereby offset parts of global warming and its associated economic damages. We add to the literature on economic impacts of AMOC weakening by, for the first time, adding a second impact channel which acts through carbon cycle changes. A weaker AMOC directly leads to a reduced export of carbon-rich surface waters to the deep ocean, such that, conversely, more carbon remains in the atmosphere and acts to increase global temperatures and associated economic damages. By drawing on carbon cycle feedback and freshwater hosing experiments, we provide climate modelling evidence on the magnitude of this AMOC-induced carbon feedback, and develop an emulator with which to include these estimates into a simple integrated assessment model. Based on these IAM calculations calibrated to ESM results, we find that carbon cycle feedbacks lead to an SCC increase of around 1%, which is in the same order of magnitude as the SCC decrease caused by AMOC-induced temperature changes. Taking into account this carbon effect could thus flip the overall economic effect of AMOC weakening from a net benefit into a net cost.

How to cite: Schaumann, F. and Alastrué de Asenjo, E.: Flipping the cost of tipping? Economic impacts of reduced AMOC carbon drawdown, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6786, https://doi.org/10.5194/egusphere-egu24-6786, 2024.

EGU24-8415 | Posters on site | CL3.2.3

Transparent framework to assess the revision of climate pledgesafter the first Global Stocktake 

Katsumasa Tanaka, Kushal Tibrewal, Philippe Ciais, and Olivier Boucher

To assess the impact of potential future climate pledges after the first Global Stocktake, we propose a simple, transparent framework for developing emission and temperature scenarios by country. We show that current pledges with unconditional targets lead to global warming of 1.96 (1.39-2.6)°C by 2100. Further warming could be limited through i) commitment to mid-century net-zero targets for all countries and earlier net-zero targets for developed countries, ii) enhancement of the Global Methane Pledge, and iii) ambitious implementation of the Glasgow Leaders’ Declaration on Forests and Land Use. Our analysis further shows that overshooting 1.5°C is unavoidable, even with supplementary climate engineering strategies, suggesting the need for strategies to limit further overshoot and ultimately reduce the warming towards 1.5°C.

Reference
Tibrewal, K., K. Tanaka, P. Ciais, O. Boucher (2023) Transparent framework to assess the revision of climate pledges after the first Global Stocktake.     arXiv:2312.16326 http://arxiv.org/abs/2312.16326

How to cite: Tanaka, K., Tibrewal, K., Ciais, P., and Boucher, O.: Transparent framework to assess the revision of climate pledgesafter the first Global Stocktake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8415, https://doi.org/10.5194/egusphere-egu24-8415, 2024.

EGU24-9046 | ECS | Posters on site | CL3.2.3

PRIME: Probabilistic Regional Impacts from Model patterns and Emissions  

Camilla Mathison, Eleanor Burke, Gregory Munday, Eszter Kovacs, Chris Huntingford, Chris Jones, Christopher Smith, Andy Wiltshire, Norman Steinert, Laila Gohar, and Rebecca Varney

We present PRIME, a framework for analysis of scenarios of regional impacts for user-prescribed future emissions. PRIME combines global mean temperature and CO2 concentrations from the emissions driven FaIR simple climate model, as used in the IPCC Sixth Assessment Report, with patterns of climate change from CMIP6 Earth System models to drive the JULES land model. This simulation system projects regional changes to the land surface and carbon cycle. We evaluate PRIME by running it with Shared Socioeconomic Pathways and illustrate its robustness by comparing these known scenarios with ESMs that have also been run for the same scenarios. PRIME correctly represents the climate response for these known scenarios, which gives us confidence that PRIME will be useful for rapidly providing probabilistic spatially resolved information for novel climate scenarios; substantially reducing the time between the scenarios being released and being used in impact assessments. Therefore PRIME fulfills an important need, providing the capability to include the most recent models, science and scenarios to run ensemble simulations on multi-centennial timescales and include analysis of many variables that are relevant and important for impact assessments.

How to cite: Mathison, C., Burke, E., Munday, G., Kovacs, E., Huntingford, C., Jones, C., Smith, C., Wiltshire, A., Steinert, N., Gohar, L., and Varney, R.: PRIME: Probabilistic Regional Impacts from Model patterns and Emissions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9046, https://doi.org/10.5194/egusphere-egu24-9046, 2024.

EGU24-10993 | ECS | Orals | CL3.2.3

Climate Tipping Points and Optimal Emissions  

Andrea Titton

As the world temperature rises, due to carbon dioxide (CO2) emissions from human economic activities, the risk of tipping points in the climate system becomes more concrete. This risk affects the social cost of carbon, that is, the marginal damage of increasing carbon emissions. In this paper, I study the relationship between the risk of tipping, optimal emissions, and the social cost of carbon. To do so, I solve a social-planner integrated model (Hambel et al., 2021), with a stylised ice-albedo feedback in the climate dynamics (Ashwin & Von Der Heydt, 2020). I model a tipping point induced by the ice–albedo feedback and study how this affects optimal abatement. The tipping point affect temperature dynamics, and as a consequence optimal emissions, in three ways. First, it introduces a non-linear increase in temperature. Second, it makes positive temperature shocks more persistent than negative ones. Third, it introduces a jump in the abatement necessary to revert temperatures to the pre-tipping-point level. I show that, in this context, it is crucial not only to quickly reachnet-zero emissions, but to also flatten the emission curve to reduce the risk of tipping

 

How to cite: Titton, A.: Climate Tipping Points and Optimal Emissions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10993, https://doi.org/10.5194/egusphere-egu24-10993, 2024.

EGU24-12642 | Posters on site | CL3.2.3

First applications of the Rapid Impact Model Emulator 

Edward A. Byers, Michaela Werning, Volker Krey, and Keywan Riahi

Climate model emulation has long been applied to IAM emissions scenarios, but is typically limited to first-order climate variables like mean air temperature. Recently, approaches have been developed to reproduce a growing number of climate variables, also with spatial, even gridded, resolution, such as the MESMER (Beusch et al., 2020) and STITCHES (Tebaldi et al., 2022) models.

 Here we demonstrate a recently-released post-processing software package, that takes the global mean surface air temperature trajectory, and calculates a range of climate impacts and exposure indicators (25+) in gridded spatial and tabular formats. The Rapid Impact Model Emulator uses a combination of pattern-scaling and time-sampling approaches and can be used on indicators that have been prepared at global warming levels, such as for hydrology and crop yields.

Using a database of such indicators (Werning et al 2023.), including outputs of global climate and hydrological models and a fire weather index, we show how batches of climate indicators can be quickly provided as outputs for new IAM scenarios. Combined with population exposure and vulnerability layers, we present new insights on the climate risk burden of different IPCC scenarios to illustrate how such approaches can bridge the IPCC WGII and WGIII communities, and take us beyond the constraints of RCP pathways.

How to cite: Byers, E. A., Werning, M., Krey, V., and Riahi, K.: First applications of the Rapid Impact Model Emulator, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12642, https://doi.org/10.5194/egusphere-egu24-12642, 2024.

EGU24-13134 | ECS | Posters on site | CL3.2.3

DAC technologies implementation as a function of oil and gas price 

Stuart Jenkins, James McElhinney, Yoga Pratama, Myles Allen, and Volker Krey

It is widely accepted that to achieve net zero emissions a portion of CO2 production must be offset by CO2 removals of some kind. It is highly suboptimal to squeeze every fossil fuel use out of society entirely, where some valuable processes continue to demand fossil fuel resources even with carbon prices of more than $200510,000/tCO2. Hence, a small residual of CO2production exists in the majority of ambitious mitigation scenarios analysed by the IPCC[1] which need offsetting with carbon removal.

The scale of residual CO2 production depends on several macro-economic and technological factors which remain uncertain at present day, principally: the rate of, and limit of, market penetration for various renewable and low carbon substitution technologies; the marginal cost between a unit of fossil-fuel-derived final energy and its equivalent low-carbon alternatives, and the trajectories for these marginal costs across the mitigation period; the cost, potential scale of, and speed of deployment for novel carbon removal technologies, along with co-benefits of their deployment.

Previous research has considered the impact of varying oil and gas prices on mitigation outcomes in isolation. For example, one recent study suggests that fixing oil prices at the extremes observed over the decade 2005-2015 (low of $40/bbl, high of $110/bbl) results in mitigation outcomes shifting by the equivalent of 5-20% of the remaining carbon budget to 2°C, on an otherwise 2°C-compatible price-driven mitigation trajectory.[2] Such uncertainty in the future price of fossil fuel resources represents a large uncertainty for the trustworthiness of our modelled mitigation scenarios to date.

One way that this 'CO2 impact of a collapse in oil and gas prices' could be avoided is if this low fossil fuel price scenario came alongside a trajectory of rapid deployment and learning in various DAC technologies. But how realistic is this scenario, and under what conditions does it occur? Here we use the MESSAGEix[3] integrated assessment modelling framework to determine the relationships between novel DAC technologies market penetration and the price of readily-extractible fossil fuel resources. The study uses the MESSAGEix energy system model, a perfect foresight model with 11 regions and representations of a wide range of primary, secondary, useful and final energy technologies, along with endogenous resource and technology prices, and demand/supply curves. We vary the fossil fuel resource curves, both cost of extraction and scale of available resources, alongside key parameters describing novel DAC technologies, to determine the relationship between DAC implementation and the price of oil and gas in high ambition mitigation scenarios for the 21st century.

 

References

[1] – IPCC AR6 scenarios database (2023). https://data.ece.iiasa.ac.at/ar6/

[2] – McCollum et al. (2016). Nature Energy. Quantifying uncertainties influencing the long-term impacts of oil prices on energy markets and carbon emissions.

[3] – MESSAGEix modelling framework (2023). https://docs.messageix.org/en/latest/

How to cite: Jenkins, S., McElhinney, J., Pratama, Y., Allen, M., and Krey, V.: DAC technologies implementation as a function of oil and gas price, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13134, https://doi.org/10.5194/egusphere-egu24-13134, 2024.

   As global temperatures continue to rise, the world faces a challenge in managing energy demand. With more frequent and severe heatwaves, the demand for cooling solutions surges, increasing electricity consumption and investments in cooling infrastructure. A growing number of researchers are focusing their efforts on comprehending the economic impacts of these shifts in energy demand. Nevertheless, many of these studies have predominantly relied on partial climatic factors, such as solely using daily mean temperature to estimate trends in cooling energy demand. Daily mean temperature, however, may not fully capture the building's thermal environment. Additionally, traditional methods, which do not comprehensively capture all relevant climatic conditions, have revealed regional variations in damage costs that may lead to biased results.

  This paper addresses three main research questions:

  • What influences the economic impacts of cooling energy demand variations when including daily maximum and minimum temperatures and humidity in calculating Cooling Degree Days(CDD)?
  • How much does the new Cooling Degree Days (CDD) calculation affect regional variation?
  • How can the economic impacts of cooling energy demand variations be sensitive to shifts in the thermal comfort zone?

   Three CDD estimation methods were compared: 1) ASHRAE(traditional method) 2) UKMO(by daily maximum and minimum temperature), and 3) UKMO with HUMidex(adjusting temperature with relative humidity). We used three representative concentration pathways (RCP2.6, RCP4.5, RCP8.5) with four general circulation models to represent climate conditions. Using AIM/Hub, a CGE-based integrated assessment model, we estimated energy demand changes and GDP loss due to rising cooling energy investment. We assumed that these investments have constant elasticity of substitution between value added in capital, labor, and land, directly leading to GDP loss in AIM/Hub. We also simulated by adjusting the setpoint temperature in the thermal comfort zone with temperature and humidity conditions.

   Results reveal ASHRAE's higher CDD values in most regions but a comparable global GDP loss of about 0.61% by 2100 (compared to current emission trends and 2℃ goals), similar to other methods (0.55-0.57). However, regionally, ASHRAE and UKMO with HUMidex show reverse outputs. For instance, Japan, with a hot and humid summer, experiences a 1.53% GDP loss in ASHRAE but -1.01% in UKMO with HUMidex. These findings suggest less future cooling energy investment is needed in prior hot and humid regions, reducing economic impacts. Similar trends occur in most hot and humid regions, while hot and arid regions like Turkey and Australia experience opposite outcomes. Adjusting setpoint temperature shows that lifestyle change or building energy efficiency enhancement, which can affect cooling setpoint temperature, can avoid these economic impacts. However, more consideration should be needed in estimating adaptation costs for these changes.

 
 
 

How to cite: Choi, Y. and Park, C.: Rethinking the Economic Impact of Future Cooling Energy Demand Variations: Insights from Comprehensive Climatic Conditions on Thermal Comfort, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14787, https://doi.org/10.5194/egusphere-egu24-14787, 2024.

EGU24-16863 | Orals | CL3.2.3 | Highlight

Long-Term Legacy of Climate Overshoot on Economic Productivity: An Emulator-Based Modeling Approach 

Carl-Friedrich Schleussner, Sarah Schöngart, Moritz Schwartz, Jonas Schwaab, and Felix Pretis

Most climate change mitigation scenarios aimed at limiting end-of-century warming to 1.5°C involve overshoots, that is they temporarily exceed 1.5°C of warming. Despite the prevalence of overshoot pathways, their effects on economic productivity have not been systematically assessed yet. Furthermore, existing assessments of future economic risks do not systematically explore the full spectrum of physically plausible outcomes under given emission pathways and thereby run the risk of underestimating high-end risks. In this study, we rely on coupled climate model emulators representing the full physical climate uncertainty chain to assess the GDP per capita growth under a range of policy relevant emission scenarios, seven of which are characterized by overshoot.

Using the emulators FaIR and MESMER, the emission scenarios were translated into a large ensemble of spatially resolved annual temperatures that captures both model uncertainty and natural variability on both global and local scales. Building on standard approaches to empirically estimate the effect of temperature on GDP per capita growth, we incorporate parametric uncertainties in the economic response and link these empirical estimates with the overshoot scenarios. The resulting dataset allows for the examination of local and regional impacts (and associated uncertainties) of overshoot scenarios on economic productivity, including the timing and magnitude of temperature threshold exceedance.

We find a legacy of overshoot in future GDP gains way beyond the end of the temperature overshoot. We also report heavy tailed risks of economic damages when considering the full range of plausible physical outcomes. Under all but the most stringent scenarios there is a non-negligible risk for near-stalling of 21st century per capita growth for particularly vulnerable countries.

We find that near-term warming rates (2020-2040) play a pivotal role in shaping future GDP per capita gains. Across overshoot scenarios, by 2100 GDP per capita levels are lower with rising warming rates, while the magnitude of the GDP per capita gain is linked to the extent of the overshoot. Our results highlight the critical importance of near-term emission reductions to limit economic risks posed by climate change over the 21st century. A temperature overshoot poses substantial risks of a long-term legacy of economic damages for decades to come.

How to cite: Schleussner, C.-F., Schöngart, S., Schwartz, M., Schwaab, J., and Pretis, F.: Long-Term Legacy of Climate Overshoot on Economic Productivity: An Emulator-Based Modeling Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16863, https://doi.org/10.5194/egusphere-egu24-16863, 2024.

EGU24-16997 | ECS | Posters on site | CL3.2.3 | Highlight

Risks of unavoidable impacts on forests at 1.5 with and without overshoot 

Gregory Munday, Chris Jones, Norman Steinert, Camilla Mathison, Eleanor Burke, Chris Smith, Chris Huntingford, and Rebecca Varney

Regional climate impacts studies are usually predicated on output from fully-coupled Earth system models, which, due to computational constraints, can only simulate a limited number of scenarios and ensemble members. Using the PRIME system, we can simulate spatially resolved impacts quickly - emulating the response of 34 CMIP6 models, and generating ensemble members that capture the IPCC assessed range of equilibrium climate sensitivity (ECS). We assess the tail risks associated with high ECS simulations on critical tropical and boreal forest ecosystems over the 21st century and beyond, using three policy-relevant strong-mitigation IPCC WG3 emissions scenarios with different relationships to 1.5°C global warming. We quantify the future resilience and risk of dieback across these ecosystems, focus on the reversibility of loss using a temperature overshoot-and-return scenario and delineate hazardous climatic space for the Amazon basin, with climate-boundaries consistent with the literature. We show that despite using emissions scenarios which achieve 1.5 and 2 degrees Paris Agreement targets, uncertainty in ECS exhibits unavoidable risk of Amazon forest health decline and dieback, further highlighting the requirement for urgent, focused, global mitigative actions.

How to cite: Munday, G., Jones, C., Steinert, N., Mathison, C., Burke, E., Smith, C., Huntingford, C., and Varney, R.: Risks of unavoidable impacts on forests at 1.5 with and without overshoot, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16997, https://doi.org/10.5194/egusphere-egu24-16997, 2024.

EGU24-18731 | Orals | CL3.2.3

Using regional ESM emulators to assess climate feedbacks to IAMs: The "FASTMIP" experimental protocol 

Sonia Seneviratne, Yann Quilcaille, Michael Windisch, Lukas Gudmundsson, Bianca Biess, Felix Jaeger, Matthias Hauser, and Martin Hirschi

Changes in regional climate extremes belong to the most impactful consequences of the human-induced climate crisis (Seneviratne et al. 2021). However, they are generally not or only partially considered in Integrated Assessment Models (IAMs) which are used to derive emissions scenarios underlying climate change projections. This has important implications for the assessment of plausible emissions pathways and associated policy decisions, in particular in the context of reports of the Intergovernmental Panel on Climate Change (IPCC).

Recently, new regional Earth System Model (ESM) emulators such as the Modular Earth System Model Emulator with spatially Resolved output (MESMER; Beusch et al. 2020, 2022; Quilcaille et al. 2022) and STITCHES (Tebaldi et al. 2022), have been developed to allow the emulation of regional ESM features when driven with output from global climate emulators. The resulting emulator chains (e.g. Beusch et al. 2022) can derive plausible geographically-resolved trajectories for mean and extreme climate variables associated with given IAM emission pathways. This fast computation of regional projections could help assess and increase the realism of emissions pathways from IAMs, e.g., with respect to afforestation, the implementation of bioenergy with carbon capture and storage (BECCS), or projected changes in agriculture and population.

This contribution presents a new experimental protocol (“FASTMIP”) building on global and regional ESM emulators and allowing the fast derivation of geographically-resolved climate change projections for new emissions scenarios, in coordination with other existing tools (e.g. Nicholls et al. 2020, Kikstra et al. 2022). The proposed FASTMIP experiment could help inform the choice of emission scenarios within the 7th phase of the Coupled Model Intercomparison Project (CMIP7), and provide new insights towards to the integration of climate feedbacks in IAMs. First analyses showing the potential of the FASTMIP experiment for constraining IAM projections will be presented.

 

References:

Beusch, L., L. Gudmundsson, S.I. Seneviratne, 2020, Earth System Dynamics, 11, 139-​159

Beusch, L., Z. Nicholls, L. Gudmundsson, M. Hauser, M. Meinshausen, and S.I. Seneviratne, 2022, Geoscientific Model Development, 15 (5), 2085-2103, doi: 10.5194/gmd-15-2085-2022.

Kikstra, J.S., et al., 2022, Geosci. Model Dev., 15, 9075–9109.

Nicholls, Z.R.J., et al., 2020, Geosci. Model Dev., 13, 5175–5190.

Quilcaille, Y., L. Gudmundsson, L. Beusch, M. Hauser, and S.I. Seneviratne, 2022, Geophysical Research Letters, 49, e2022GL099012.

Seneviratne, S.I., X. Zhang, M. Adnan, W. Badi, C. Dereczynski, A. Di Luca, S. Ghosh, I. Iskandar, J. Kossin, S. Lewis, F. Otto, I. Pinto, M. Satoh, S.M. Vicente-Serrano, M. Wehner, and B. Zhou, 2021: Chapter 11: Weather and Climate Extreme Events in a Changing Climate. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V. et al. (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1513–1766, doi:10.1017/9781009157896.013. (https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter11.pdf)

Tebaldi, C., A. Snyder, and K. Dorheim, 2022, Earth System Dynamics, 13, 1557–1609.

How to cite: Seneviratne, S., Quilcaille, Y., Windisch, M., Gudmundsson, L., Biess, B., Jaeger, F., Hauser, M., and Hirschi, M.: Using regional ESM emulators to assess climate feedbacks to IAMs: The "FASTMIP" experimental protocol, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18731, https://doi.org/10.5194/egusphere-egu24-18731, 2024.

EGU24-19046 | Orals | CL3.2.3

Trade-offs and Social Cost Estimates: Focus on CO2 and Contrail Cirrus 

Daniel Johansson, Christian Azar, Susanne Pettersson, and Thomas Sterner

Governments worldwide are confronted with a need to curtail emissions of greenhouse gases to achieve the global climate targets outlined in the Paris Agreement. While carbon dioxide (CO2) remains the primary greenhouse gas targeted in climate policies, it is important to address emissions of non-CO2 forcers.

Trade-offs between CO2 and other climate forcers are often determined based on Global Warming Potentials (GWP). An alternative approach is to use climate-economic approaches, estimating the social cost of different forcers. Here we focus particularly on aviation CO2 emissions and contrail cirrus. Specifically, we explore how the social cost of contrail cirrus can be estimated using a revised version of the integrated assessment model DICE. We analyze contrail forcing from a flight-specific model that considers their spatio-temporal variability. Further, DICE has been revised in particular with respect to the geophysical model (being based on the emulator FaIR 2.0.0), and also with changes in the parameterization of the discounting and damage functions. Additionally, we examine how the social cost of short-lived forcers (contrail cirrus) and long-lived emissions (CO2) is influenced by the discount rate and the future temperature pathway.

Concerning spatio-temporal variability, we observe that both energy forcing and the social cost of contrail cirrus are strongly dependent on flight specific conditions, including as a strong diurnal variability. Furthermore, we find that the comparison between the social costs of contrail cirrus and the social cost of CO2 depends very strongly on the discount rate and the climate path the economy is following. This follows from the fact that the climate impacts of contrail cirrus are short lived, making their social cost less contingent than CO2 on how future climate impacts are valued through the discount rate, and correspondingly less affected by the long-term changes in global mean surface temperature. 

We also explore the additional insights gained from analyzing the ratio of the social cost of contrail cirrus to the social cost of CO2, beyond the information provided by analyzing the corresponding GWP values. Finally, the potential policy implications of the variability of the social cost of contrail cirrus are discussed.

How to cite: Johansson, D., Azar, C., Pettersson, S., and Sterner, T.: Trade-offs and Social Cost Estimates: Focus on CO2 and Contrail Cirrus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19046, https://doi.org/10.5194/egusphere-egu24-19046, 2024.

EGU24-19478 | ECS | Orals | CL3.2.3

Comparing mitigation, adaptation and residual damage costs under different socio-economic and climate scenarios 

Kaj-Ivar van der Wijst, Andries Hof, Kelly de Bruin, and Detlef van Vuuren

Future socio-economic development plays a crucial role in both climate policy and the impacts of climate change. In this study, we for the first time systematically compare the costs of mitigation, adaptation, and residual damage for different socio-economic and climate scenarios known as the Shared Socio-economic Pathways (SSPs). For this, we combine recent damage estimates with adaptation costs and introduce differences in the effectiveness of adaptation based on the SSP projection. The results can be presented in terms of SSP/RCP matrix, with optimal climate outcomes as a function of SSP. The results can also be used to identify critical factors determining the optimal temperature, including socio-economic development, technology development and limits to mitigation and adaptation. The socio-economic limits to adaptation lead to damage costs that are 15% to 60% higher than if optimal adaptation had been possible. Overall, this study demonstrates that the socio-economic developments assumed in the SSP, including inequality reduction and institutional strength, can be equally important for the optimal outcome as the factors typically studied such as discount rate.

How to cite: van der Wijst, K.-I., Hof, A., de Bruin, K., and van Vuuren, D.: Comparing mitigation, adaptation and residual damage costs under different socio-economic and climate scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19478, https://doi.org/10.5194/egusphere-egu24-19478, 2024.

The history of Holocene fire evolution and its influencing factors are hot scientific issues. The middle (Xinjiang) and eastern (Xi'an-Dunhuang) parts of the Silk Road were affected by different climatic systems, and there are obvious differences in the mode and intensity of human activities in the middle and late Holocene. Research on the history of paleo-fires in this region and their relationship with climate change and human activities has received extensive attention. Based on the analysis of black carbon in the sediments of two alpine lakes, and combining the available paleo-climatic results, archaeological and historical literature, we reconstructed the paleo-fire history of the middle and late Holocene in the  area. We revealed the relationship between paleo-fires and the changes in climate, vegetation, and human activities in different regions, and explored the differences in the patterns of paleo-fires in the study area in terms of temporal and spatial variations, and their possible driving mechanisms. The above work will help to understand the pattern and mechanism of ancient fires in the mid-eastern Silk Road on a centennial and millennial scale, which is of great theoretical value and practical significance for future fire prevention and control measures in the context of climate change, and also provides a valuable case study for understanding the impact of human activities on the environment.

How to cite: Zhang, S. and Dong, G.: Fires history and the human impact during the mid-late Holocene in the mid-eastern Silk Roads, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7343, https://doi.org/10.5194/egusphere-egu24-7343, 2024.

Tibetan antelope is the only genus of large mammal endemic to the Tibetan Plateau. In the past decades, the antelope population has been significantly affected by human activities, including massive illegal hunting, followed by strict protection policies and establishments of natural reserves. Various techniques and many efforts have been devoted to monitoring changes in antelope population as well as migration recently. However, it remains unclear how the antelope population changed in the past, and how it varied with climate and environment. Here, we present sedimentary records at Lake Zonag, one of the major calving grounds for the Tibetan antelope, to study past changes in antelope population and response to environment changes. The sedimentary fecal sterols, produced by antelopes, captured the sudden decrease in antelope due to illegal hunting in past decades, as well as the recent recovery. The antelope population varied significantly during the past 9000 years, generally following environment changes revealed by geochemical elements in the same sediment core. Large antelope population likely lived in environment with relatively warm, humid and dense vegetation cover, while small antelope population occurred in adverse environment with relatively cold, dry and sparge vegetation cover. Two periods with notably low antelope population were observed at 5100-4500 and 4100-3700 cal yr before present. The increase in antelope population in the past 400 years likely result from protection from early Tibetans. This study provides a perspective method to reconstruct past changes in antelope population, to study its response to environment changes, and to provide historical comparison for wildlife protection.

How to cite: Hou, J.: Responses of Tibetan antelope population to environment changes during the Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11012, https://doi.org/10.5194/egusphere-egu24-11012, 2024.

EGU24-14344 | ECS | PICO | CL3.2.4

BrGDGTs-based seasonal paleotemperature reconstruction for the last 15,000 years from a shallow lake on the eastern Tibetan Plateau 

Xiaohuan Hou, Nannan Wang, Zhe Sun, Kan Yuan, and Xianyong Cao

Understanding Holocene temperature changes is vital for resolving discrepancies between proxy reconstructions and climate models. The intricate temperature variations across the Tibetan Plateau (TP) add complexity to studying continental climate change during this period. Discrepancies between model-based and proxy-based reconstructions might stem from seasonal biases and environmental uncertainties in the proxies. Employing multiple proxies from a single sediment core for quantitative temperature reconstructions offers an effective method for cross-validation in terrestrial environments. Here, we present an ice-free-season temperature record for the past 15 ka from a shallow, freshwater lake on the eastern TP, based on brGDGTs (branched glycerol dialkyl glycerol tetraethers). This record shows that the Holocene Thermal Maximum lags the pollen-based July temperature recorded in the same sediment core. We conclude that the mismatch between the brGDGTs-based and pollen-based temperatures is primarily the result of seasonal variations in solar irradiance. The overall pattern of temperature changes is supported by other summer temperature records, and the Younger Dryas cold event and the Bølling–Allerød warm period are also detected. A generally warm period occurred during 8–3.5 ka, followed by a cooling trend in the late Holocene. Our findings have implications for understanding the seasonal signal of brGDGTs in shallow lakes, and provide critical data for confirming the occurrence of seasonal biases in different proxies from high-elevation lakes. To further investigate the significance of the brGDGTs and temperature patterns on the TP, we examined existing brGDGTs-based Holocene temperature records, which interpret these compounds as indicators of mean annual or growing season temperatures. The existing/available temperature records show complicated patterns of variation, some with general warming trends throughout the Holocene, some with cooling trends, while some with warm middle Holocene. We analyzed the possible reasons for the diverse brGDGTs records on the TP and emphasize the importance of considering lake conditions and modern investigations of brGDGTs in lacustrine systems when using brGDGTs to reconstruct paleoenvironmental conditions.

How to cite: Hou, X., Wang, N., Sun, Z., Yuan, K., and Cao, X.: BrGDGTs-based seasonal paleotemperature reconstruction for the last 15,000 years from a shallow lake on the eastern Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14344, https://doi.org/10.5194/egusphere-egu24-14344, 2024.

EGU24-14850 | ECS | PICO | CL3.2.4

Hydrological evolution and differential response of the eco-environment recorded in Lake Maozangtianchi, eastern Qilian Mountains, over the past 900 years 

Shilong Guo, Duo Wu, Tao Wang, Lin Chen, Youmo Li, Tianxiao Wang, Shuai Shao, and Aifeng Zhou

The Qilian Mountains (QLMs) serve as an 'eco-security barrier' in western China, substantially impacting downstream ecosystems and water resource utilization. However, the hydrological evolution characteristics of the QLMs during the last millennium remain controversial, and the ecological response to climate change remains poorly understood. Here, we present a pH record based on the brGDGTs (branched glycerol dialkyl glycerol tetraethers) of 14C-dated sediments from Lake Maozangtianchi and compare it with X-ray fluorescence elemental data and grain size to reconstruct the history of summer monsoon precipitation variability during the last 900 years. The history of eco-environment changes was also reconstructed from the total n-alkane contents. Our results show that, on a centennial timescale, precipitation in the watershed was high during the periods 1100‒1300 CE, and 1750‒2000 CE, while precipitation was low during the period 1400‒1750 CE; there was an abrupt decrease during the MWP (Medieval Warm Period) to LIA (Little Ice Age) transition (1300‒1400 CE). This result, coherent with hydroclimate records from the monsoonal margin of northern China, is likely forced by a combination of El Niño‒Southern Oscillation related to tropical Pacific sea-surface temperature and the meridional shift of the Intertropical Convergence Zone. In addition, there was a coupled relationship between plant biomass in the watershed and monsoon precipitation variation, with higher plant biomass during 1100‒1200 CE, 1750‒1900 CE, and 1950‒2000 CE, and lower values during 1200‒1400 CE and 1900‒1950 CE. In contrast, plant biomass was decoupled with monsoon precipitation during 1400‒1750 CE and exhibited a slightly increase trend. Precipitation is a key climatic factor controlling plant biomass in the QLMs; however, during LIA, nutrients carried by dust and decreased evapotranspiration played important roles in increasing plant biomass. Our research emphasizes the significant moderating effects of exogenic dust on vegetation changes in alpine ecosystems under a context of climatic deterioration.

How to cite: Guo, S., Wu, D., Wang, T., Chen, L., Li, Y., Wang, T., Shao, S., and Zhou, A.: Hydrological evolution and differential response of the eco-environment recorded in Lake Maozangtianchi, eastern Qilian Mountains, over the past 900 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14850, https://doi.org/10.5194/egusphere-egu24-14850, 2024.

EGU24-15973 | ECS | PICO | CL3.2.4

Synchronized responses of lake and vegetation dynamics to climate change 

Shengqian Chen, Yanan Su, and Fahu Chen

Arid central Asia, the largest non-zonal arid zone globally, serves as a crucial region for the westerlies-dominated climate regime (WDCR). Despite observing a warm-wet trend in recent years, the response of surface landscape elements such as lakes and vegetation to this climate change remains uncertain. In this study, we conduct an analysis of long-term trends (1992-2020) in lake area and NDVI across arid central Asia while comparing them with key climate factors including precipitation, drought index, and soil moisture. Our findings reveal that lakes are expanding and vegetation is greening in most regions situated at elevations exceeding 100 meters. Conversely, lakes are shrinking and vegetation is browning solely in low-altitude areas (<100m). The changes observed in water body area and NDVI exhibit robust spatiotemporal consistency that aligns with the ongoing warm-wet trend represented by the WDCR. Climate factors, particularly precipitation, exert a pivotal influence on the variations observed in surface water and vegetation within arid central Asia. 

How to cite: Chen, S., Su, Y., and Chen, F.: Synchronized responses of lake and vegetation dynamics to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15973, https://doi.org/10.5194/egusphere-egu24-15973, 2024.

EGU24-18320 | ECS | PICO | CL3.2.4

A Paleoenvironmental record from Lake Gosainkunda, Nepal 

Sudip Acharya, Darwin Rana, Maximilian Prochnow, Katharina Dulias, Binod Dawadi, Antje Schwalb, and Roland Zech

The Himalayan region is a key area for climate and environmental change and has experienced rapid and pronounced changes over the past decades. Paleoenvironmental studies from this region are crucial to understand natural climate variability. Here we investigate a ~150 cm long sediment core, spanning over the last ~7 cal. ka BP, from a small high-altitude Lake Gosainkunda (surface area ~2.3 km2, 4300 m elevation) in the central Himalayas using a multiproxy approach. Several maxima in allochthonous elements such as Ti and K, sand, as well as white layers indicate increased erosion, possibly related to flood events. Low input of allochthonous elements and sand from ~7 to 6 cal. ka BP, and from ~5 to 1.8 cal. ka BP implies reduced erosion interpreted to be associated with low precipitation. Contemporaneously, high values of log(Si/Ti), log(Ca/Ti), BSi, and inc/coh indicate high aquatic productivity, mainly controlled by higher growing season temperature and shorter duration of ice cover. High allochthonous and sand input from ~6 to 5 cal. ka BP and from ~1.8 to 1 cal. ka BP indicate increased erosion related to high precipitation. Concurrently, low aquatic productivity and authigenic carbonate production as well as positive excursion in bulk δ13C and δ15N values suggest reduced growing season temperatures and longer ice-cover. In the last ~1 ka, increased allochthonous input is related to increased anthropogenic activity in the catchment. We are now aiming to apply a suite of lipid biomarkers including the compound-specific hydrogen isotopic composition of n-alkanes for paleohydrological reconstruction as well as polycyclic aromatic hydrocarbons and faecal biomarkers to investigate paleo-fires and human impacts.

How to cite: Acharya, S., Rana, D., Prochnow, M., Dulias, K., Dawadi, B., Schwalb, A., and Zech, R.: A Paleoenvironmental record from Lake Gosainkunda, Nepal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18320, https://doi.org/10.5194/egusphere-egu24-18320, 2024.

EGU24-18450 | PICO | CL3.2.4 | Highlight

High-resolution palaeoclimate simulation over China in the last millennium 

Elena Xoplaki, Liang Zhang, Mingyue Zhang, Eva Hartmann, Sebastian Wagner, and Juerg Luterbacher

The Earth's climate is currently undergoing significant transformations, marked by increasing temperatures, more frequent extreme events, and shifts in precipitation patterns. To comprehend these changes on decadal to centennial time scales and contextualize current climate change, it is essential to leverage paleoclimatic data spanning centuries to millennia. This analytical approach enhances our insight into natural climate variability, trends, and extremes, facilitating projections, planning, and preparation for the future.

Paleoclimate reconstructions, utilizing physical, chemical, biological, or detailed documentary records, offer valuable insights into climate conditions and variability across different historical periods. In contrast, climate models provide comprehensive information and data describing the entire climate system. Paleoclimate models specifically simulate the climate of past centuries to millennia by reconstructing the forcings influencing Earth's energy and, consequently, its climate. However, global circulation models with low horizontal resolution fall short in fully elucidating atmospheric pattern interactions and linking potential climate impacts contributing to significant societal events in history.

Recognizing these limitations, regional climate models emerge as promising tools for a more realistic representation of topography and regional climate information pertinent to paleoclimate studies. In our investigation, we employ the fully paleoclimate-adjusted regional climate model COSMO-CLM over China on a 0.22° resolution. This model incorporates external forcings such as solar, orbital, volcanic, greenhouse gas, and land-use changes, aiming to reduce reliance on input from coarse-resolution General Circulation Models (GCMs). The goal is to produce simulations that better capture climate changes over the past 2000 years at the regional scale.

Focusing on specific periods during the Little Ice Age and major tropical volcanic eruptions, we compare our model results with climate reconstructions from various regions in China. The COSMO-CLM successfully reproduces the impact of volcanic eruptions on China's climate, particularly regarding temperature changes. However, the intricate topography introduces complexities that affect the regional model's performance, leading to notable differences compared to other reconstructions, along with inherent uncertainties in the results.

How to cite: Xoplaki, E., Zhang, L., Zhang, M., Hartmann, E., Wagner, S., and Luterbacher, J.: High-resolution palaeoclimate simulation over China in the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18450, https://doi.org/10.5194/egusphere-egu24-18450, 2024.

EGU24-19201 | PICO | CL3.2.4 | Highlight

Early humans migration and adaptation in the Palaeolithic Tibetan Plateau 

Fahu Chen, Hao Li, Dongju Zhang, Huan Xia, and Zhenxiu Jia

 Due to the unique environmental conditions of the Tibetan Plateau, understanding when and how the Palaeolithic ancestors migrated and adapted in the region is a key issue in the course of human evolution. In recent years, along with the increased findings of archaeological evidence and a series of high-level studies, our knowledge regarding the prehistorical human activities on the plateau has been dramatically changed. Evidence from the Baishiya Cave in northeastern plateau have shown that Denisovans occupied the cave since at least 200 ka years ago and stayed in the cave for a relatively longer time. The site of Piluo which is located in southeastern side of the plateau indicates that humans possessing handaxe technology dispersed to the plateau at a time older than 130 ka year ago. In addition, a new lithic technological type called Quina technology has also been identified in the southern part of the Hengduanshan Mountains in Yunnan Province, which is probably related to the emergence of a new human group. Altogether, these findings indicate that different types of archaic humans have ever lived on the plateau. The earliest evidence for the arrival of modern humans is from the Nwya Devu site (~4600 m), given the diagnostic blade products excavated from the site. The site has been dated to ca. 40 ka years ago. Based on current evidence, we propose some possible routes for the migration of humans into the plateau. Denisovans may disperse to the plateau from the northeast direction, handaxe population and Quina population may disperse from the southeastern side, while early modern humans may come from the western side, with two possible sources of Central Asia and Southwest Asia. Overall, it is clear that the Palaeolithic Tibetan Plateau consists of an important region for the exchanges of early humans in different areas.

Keywords: Tibetan Plateau, Palaeolithic, Denisovans, Early modern human, Human migration and adaptation

How to cite: Chen, F., Li, H., Zhang, D., Xia, H., and Jia, Z.: Early humans migration and adaptation in the Palaeolithic Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19201, https://doi.org/10.5194/egusphere-egu24-19201, 2024.

EGU24-21523 | PICO | CL3.2.4

Replicated stalagmite records revealed orbital and millennial-scale hydroclimate changes in arid central Asia across the MIS 5 stadial-interstadial transition 

Xiaokang Liu, Xianfeng Wang, Chuan-Chou Shen, Hanying Li, Jiaoyang Ruan, Guangxin Liu, Yan Yang, and Fahu Chen

Hydroclimate in arid central Asia (ACA) exhibited unique variability due to the dominance of mid-latitude westerlies over the Holocene, yet ACA climate variations during the last interglacial (Marine Isotope Stage (MIS) 5) remain elusive. Here, we present stable isotopes and trace elemental ratios of two coeval stalagmites in Xinjiang (northwest China), to address the orbital and millennial-scale climate shifts of ACA during MIS 5. The isotopic records of Baluk Cave (42°26' N, 84°44' E), spanning from 101.9 ka to 78.3 ka BP (before 1950 CE), show distinctly negative δ18O and δ13C values in the interstadials (i.e., MIS 5a and 5c), relative to the values in the stadial (MIS 5b). Such variations well correspond to the element data (X/Ca, X=Mg, Sr, and Ba), which exhibit values relatively higher in 5c and 5a compared with the 5b. These jointly suggest a key role of precession in orbital-scale climate evolution in ACA, closely following the insolation changes in warm-season (May to September) at 50°N.

Specifically, the X/Ca ratios suggested relatively dry climate in 5c and 5a while wetter climate in 5b, supporting a ‘warm/dry and cold/wet’ pattern in ACA during the last interglacial. This pattern is further supported by the simulated precipitation variation using the CESM general circulation model. Moreover, the millennial-scale climate shift across the MIS 5b/5a transition is evidenced by depleted isotopic values in Baluk Cave (i.e., ~2.5‰ in δ18O and ~1.9‰ in δ13C), initiating at 87.2±0.5 ka BP and terminating at 84.1±0.4 ka BP. The onset and termination of this millennial event in ACA are comparable with those recorded by speleothems in eastern China and northern India, and with changes in northern hemispheric temperature, atmospheric methane and CO2 concentrations as inferred by the bi-polar ice cores. Our multi-proxy study suggests a close coupling between the large-scale westerly jet circulation, as suggested by δ18O, and local effective moisture in ACA, as documented by X/Ca, on orbital and millennial- scales.

How to cite: Liu, X., Wang, X., Shen, C.-C., Li, H., Ruan, J., Liu, G., Yang, Y., and Chen, F.: Replicated stalagmite records revealed orbital and millennial-scale hydroclimate changes in arid central Asia across the MIS 5 stadial-interstadial transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21523, https://doi.org/10.5194/egusphere-egu24-21523, 2024.

India finds itself in the throes of an unprecedented water crisis, posing a severe threat to millions of lives and livelihoods. Currently, a staggering 600 million Indians grapple with high to extreme water stress, leading to approximately two lakh deaths annually attributed to insufficient access to safe water. The gravity of the situation is exacerbated by projections indicating that, by 2030, the country’s water demand will surpass twice the available supply. This foretells a dire scenario of acute water scarcity affecting hundreds of millions of people and culminating in an estimated ~6% decline in the nation’s GDP. In light of these alarming statistics, the need for a localised, culturally infused, and literary approach to communicate scientific data on water scarcity to the general populace has become more crucial than ever. Contemporary Indian graphic novelist Sarnath Banerjee’s graphic narrative All Quiet in Vikaspuri (2015) has been read for this study to analyse the embodied experiences of water scarcity faced by the thirsty population in India’s one of the most polluted megacities who are in the quest, both mythical and physical, of finding and retaining water supply in Delhi. Through an experimental amalgamation of scientific data and graphic media, Banerjee explores how stories play crucial roles both in unveiling the historical consciousness of the postcolonial hydro-modernity marked by the resource extraction and hydrological exhaustion and in framing scarcity, not as natural but as socio-political production in twentieth and twenty-first-century India. This study does not merely engage with the data, research, and discussions around climate change and water crisis, which often remain abstract, full of jargon, and far removed from everyday lived realities. Rather, it underscores the urgency of visual communication in conferring long-lasting co-benefits upon the people and socio-ecological systems of which they are part.

How to cite: Rakshit, N. and Gaur, R.: Climate Disasters and Postcolonial Narratives: Mapping India’s Water Crisis in the Contemporary Indian Graphic Novels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-773, https://doi.org/10.5194/egusphere-egu24-773, 2024.

EGU24-1575 | Orals | EOS1.8 | Highlight

Resources to give facts a fighting chance against misinformation 

Bärbel Winkler and John Cook

Skeptical Science is a volunteer-run website publishing refutations of climate misinformation. Some members of the Skeptical Science team actively research best-practices refutation techniques while other team members use the provided materials to share debunking techniques effectively either in writing or through presentations. In this submission, we highlight several of our publications and projects, designed to help to give facts a fighting chance against misinformation. While some of the resources are directly related to climate change such as the rebuttals to common climate myths, the employed techniques apply across different topics. They include the “FLICC-framework” which features a taxonomy of science denial rhetorical techniques (FLICC standing for fake experts, logical fallacies, impossible expectations, cherry picking, and conspiracy theories), the Debunking Handbook 2020 which summarizes research findings and expert advice about debunking misinformation, and the Conspiracy Theory Handbook distilling research findings and expert advice on dealing with conspiracy theories. We will also introduce the Cranky Uncle smartphone game,  which uses critical thinking, gamification, and cartoons to interactively explain science denial techniques and build resilience against misinformation.

How to cite: Winkler, B. and Cook, J.: Resources to give facts a fighting chance against misinformation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1575, https://doi.org/10.5194/egusphere-egu24-1575, 2024.

EGU24-2157 | Orals | EOS1.8

Unseen heat, a story about the potential heat extremes in the Netherlands 

Lisette Klok, Jan-Willem Anker, Sophie van der Horst, Timo Kelder, and Daniël Staal

Recent years have seen record-shattering extreme heat all over the world. Outliers have even surprised climate scientists. In the Netherlands too, it could get extremely hot in the near future. What could the impacts be if intense temperatures hit the Netherlands? For such a scenario, we developed the climate story ‘Unseen heat’ (unseenheat.com). With this story, about a young family in the Dutch city of Eindhoven, we want to depict what could happen if we face an unprecedented heat crisis.

The target audience of the story are professionals. With storytelling, matching pictures and sound, we want to make professionals aware of the possible risks of extreme heat. The aim is to start the conversation about how to prepare for a heat crisis.

In this presentation we would like to share our experiences regarding the developement of the storyline. The story is based on the latest scientific insights on exceptional weather events and impacts in the Netherlands, and numerous interviews. We will also explain how the story is currently being used by professionals, and we will present our lessons learned  on how the climate story can help to prepare for a heat crisis.

How to cite: Klok, L., Anker, J.-W., van der Horst, S., Kelder, T., and Staal, D.: Unseen heat, a story about the potential heat extremes in the Netherlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2157, https://doi.org/10.5194/egusphere-egu24-2157, 2024.

EGU24-3116 | Orals | EOS1.8 | Highlight

Design as a participatory foundation for impactful climate communications 

Morelli Angela and Gabriel Johansen Tom

When addressing the intricacies of climate change and its profound impact on humanity and nature, we encounter extraordinary complexity. Whether the goal is to present scientific information to support decision-making processes, create seamless digital stories that capture the imagination of an audience, or produce data visualisations that help us discern, distinguish, learn and understand, Design can offer a systematic tool to tackle this complexity. Design provides the solid foundation of human-centered methodologies that equip us with the tools needed to meet our audience where they are, ensuring the participation of multiple stakeholders and the inclusion of diverse perspectives. This is key to building solutions that resonate with an audience, upholding principles of justice, equality, fairness, and transparency.

How to cite: Angela, M. and Tom, G. J.: Design as a participatory foundation for impactful climate communications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3116, https://doi.org/10.5194/egusphere-egu24-3116, 2024.

EGU24-3182 | ECS | Orals | EOS1.8

AI-Enhanced Academic Entrepreneurship in K-12 Climate Education in China 

Xiuli Chen and Joohan Ryoo

The main objective of this research is to establish the possible strategies that can be used in order to increase the number of people especially in K-12 education who are involved in climatology. The purpose is to analyze the creative utilization of artificial intelligence (AI) and academic entrepreneurship for teachers’ creation and sale of AI-based customized narrations on climate change issues. This is done by two means namely, application of AI tools through live streaming classes and e-training on content in teaching as well as mentoring them on business skills of disseminating and selling out such materials. There are three major areas where teachers require assistance such as producing better resource materials, generating income through them, and promoting students’ environmentally-related learning outcomes.

The research design involves both qualitative and quantitative approaches. Questionnaires given to 150 respondents who undertook online training will enable the collection of quantitative data indicating how effective the program is and whether AI tools are user-friendly. Thus, more than eighty percent of educators admitted that they could facilitate personalized climate stories using these programs; moreover, 85 percent said they were able to create personalized stories with their assistance. Furthermore, more than seventy percent anticipate an increase in interest among students about studying climate change. Interviews were conducted among various stakeholders including ten teacher entrepreneurs, ten students, and ten parents so as to collect qualitative data. These interviews aim at illustrating trust building through AI-infused materials which improve how we talk about climate change as well as encouraging sustainable behaviors among young people who learn. For instance eight out ten respondents confessed that they “knew nothing about global warming” but today they have knowledge concerning power plants discharging greenhouse gasses into the environment.. Thus this indicates a decline in numbers of children who perceive environmental conservation as a normal thing thus demonstrating that AI based instruction is efficient towards changing students attitudes for sustainability actions caused by it.

This study emphasizes that AI supports presentation of scientific knowledge to young people in an exciting way. Therefore, it is concerned with equipping teachers with competences in content development and entrepreneurship. Thus, climate education’s pedagogical efficiency, which improves its economic viability by presenting a way of imparting scientific truths on the subject matter, is thus also developed through this model.

How to cite: Chen, X. and Ryoo, J.: AI-Enhanced Academic Entrepreneurship in K-12 Climate Education in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3182, https://doi.org/10.5194/egusphere-egu24-3182, 2024.

EGU24-3634 | ECS | Posters on site | EOS1.8

Homeopathy in Greece: A critical evaluation of institutional support versus scientific evidence 

Stamos Archontis and Andronikos Koutroumpelis

Our investigation presents a comprehensive fact-checking analysis of the standing of homeopathy in Greece, juxtaposing the support it receives from some official institutions with the prevailing scientific consensus. This work was prompted by a recent controversy surrounding the sponsorship of a homeopathic conference by the Ministry of Health and the Athens Medical Association. Notably, the official website of the organization hosting the event published articles making bold assertions about the effectiveness of homeopathy in treating COVID-19 and casting doubts on the safety of mRNA vaccines. Furthermore, the event highlighted a presentation claiming to treat a supposed case of vaccine-induced autism with homeopathy.

To address these claims, we conducted a detailed inquiry involving requests for official statements from relevant Greek authorities and professional associations. Our approach included a thorough review of national regulations, an extensive examination of medical literature, and an analysis of international medical recommendations regarding homeopathy. The findings revealed a stark contrast between institutional endorsements and the lack of empirical evidence supporting homeopathy’s efficacy in treating diseases.

Our work discusses the consequences of such a disparity between institutional support and scientific validation. The findings highlight the necessity of aligning health policies and endorsements with scientifically validated practices to maintain public trust and ensure the credibility of medical recommendations.

How to cite: Archontis, S. and Koutroumpelis, A.: Homeopathy in Greece: A critical evaluation of institutional support versus scientific evidence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3634, https://doi.org/10.5194/egusphere-egu24-3634, 2024.

EGU24-5397 | Orals | EOS1.8

How to make droughts newsworthy: lessons from the 2022/2023 snow deficit in the Italian Alps 

Francesco Avanzi, Marina Mantini, Annalisa Marighella, Silvia Porcu, Anna Romano, Luca Salvioli Mariani, Marina Caporlingua, Michela Finizio, Luca Galimberti, Ferdinando Cotugno, Federico Grazzini, Nicolas Lozito, Nick Breeze, Edoardo Cremonese, Marta Galvagno, Sara Favre, Paolo Pogliotti, Umberto Morra di Cella, Lauro Rossi, and Luca Ferraris

Winter 2021-2022 and 2022-2023 were characterized by extreme drought conditions across the Italian Alps, with a –60% in Snow Water Equivalent at peak accumulation compared to recent years. During summer 2022, this deficit in snow compounded the ongoing precipitation deficit and temperature anomaly in dictating historical lows in water supply across the Po river basin. In this context, in January 2022 CIMA Research Foundation initiated periodic communication actions on social media and its website (https://www.cimafoundation.org/en/) to report on the ongoing snow-drought conditions and the potential implications for water security. This effort started from dissemination on social media, such as threads on Twitter/X (https://twitter.com/CIMAFoundation/status/1646451722968088577) and on LinkedIn, and ended up in triggering a significant media coverage in the form of national/international newspapers, all-news TV outlets, blogs, podcasts, and official reports at various levels. The communication became a campaign that influenced drought storytelling in Italy, creating an unexpected “snowball effect”. In this case study, CIMA’s researchers got together with some of the journalists and science communicators who covered this event to discuss reasons for its newsworthiness and mediatic lessons learned for the future of the scientific communication in a warming climate. Working at the science-media interface, we learned the role that key messages, regularity in information release, visual identity, and simplicity play in driving communication. We also confirm the central role of a two-step methodology in which scientists create content that is delivered to the public by a mediator (whether a journalist or an organization), and the importance both for scientists to actively engage with such mediators to get the message across and for journalists to look at, and trust, specific sources of information. This activity is continuing in 2023/24 as snow conditions face increasing pressure from warming temperatures and aridity. In the long run, it will bring awareness to the citizenship on the crucial role of immediate and credible climate-change adaptation strategies at multiple levels. 

How to cite: Avanzi, F., Mantini, M., Marighella, A., Porcu, S., Romano, A., Salvioli Mariani, L., Caporlingua, M., Finizio, M., Galimberti, L., Cotugno, F., Grazzini, F., Lozito, N., Breeze, N., Cremonese, E., Galvagno, M., Favre, S., Pogliotti, P., Morra di Cella, U., Rossi, L., and Ferraris, L.: How to make droughts newsworthy: lessons from the 2022/2023 snow deficit in the Italian Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5397, https://doi.org/10.5194/egusphere-egu24-5397, 2024.

EGU24-8129 | Orals | EOS1.8 | Highlight

Bridging disciplines, shaping futures: the power of networking for climate change communication 

Ottavia Carlon, Alessandra Mazzai, Agnese Glauda, Davide Michielin, Francesco Bassetti, Selvaggia Santin, and Arianna Acierno

Facilitating meaningful cross-sectoral conversations is essential for the successful integration of various disciplines in climate change communication. To address the key challenges of our times, the exchange of ideas and best practices can be highly beneficial in a collaborative effort to enhance public engagement around climate science and solutions. By creating networks that bring together scientists, experts, and communication professionals, research institutions can collaboratively shape future climate narratives based on information trustworthiness. 

The CMCC Foundation’s approach to disseminating frontier science and showcasing exemplary climate change communication initiatives serves as a cutting-edge case study. With the biennial CMCC Climate Change Communication Award “Rebecca Ballestra”, CMCC aims to highlight innovative science-based communication projects worldwide, raising awareness about the changing climate and its societal impacts, through art, journalism, education and integrated campaigns. An ever-growing digital platform (www.cmccaward.eu) collects the best grassroots and upscaled initiatives that communicate threats and opportunities of current and future climate scenarios, empowering new voices and promoting interdisciplinary dialogue to trigger action. The first two editions of the Award have assembled over 300 initiatives from all around the globe, thus allowing to build a wide network of communication professionals and providing them with the opportunity to engage in dialogue and collaboration.

Building upon these connections, the Foresight Dialogues (https://www.cmccaward.eu/foresight-dialogues/), a series of online and in-person conversations with international experts, scientists and communication professionals, create a space for more in-depth discussions on the multifaceted role of communication in accelerating the climate transition. The topics covered include sociology in dialogue with Rebecca Huntley of the Australian agency 89 Degrees East; journalism, with Sarah Kaplan, climate reporter at Washington Post, and representatives from the American Climate Central network; disinformation, with Australian John Cook, founder of Skeptical Science, and the European Digital Media Observatory (EDMO); arts, with the Serbian Center for the Promotion of Science (CPN) and Carolina Aragon, past CMCC Award Winner and professor at UMass Amherst; photography, with authors of the projects “The Cooling Solutions” and “On the Trails of the Glaciers”; solutions, with the Futerra change agency and Ione Anderson, from Brasil; public engagement, with the European Science Engagement Association (EUSEA) and the Barcelona SuperComputing Center (BSC); architecture with the Stefano Boeri Architetti firm; and podcasts and films with the Italian authors of Bello Mondo, and the second edition Award winner from India, Faces of Climate Resilience. 

The Foresight Dialogues are an integral part of the CMCC’s editorial project, Foresight (https://www.climateforesight.eu/), an online multimedia magazine that combines in-house climate change expertise with external knowledge. Foresight gathers ideas from international climate experts, offering insights into the potential future of our society, economy, and planet by bridging science, policy, and public narratives.

Together, these initiatives contribute to framing the discourse on the communication of climate research, linking interdisciplinary knowledge to actionable outcomes. As the CMCC Foundation continues to enlarge its network and spotlight impactful climate communication projects, it cultivates a shared understanding of climate challenges, promoting a collective response for a sustainable future.

How to cite: Carlon, O., Mazzai, A., Glauda, A., Michielin, D., Bassetti, F., Santin, S., and Acierno, A.: Bridging disciplines, shaping futures: the power of networking for climate change communication, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8129, https://doi.org/10.5194/egusphere-egu24-8129, 2024.

EGU24-8799 | ECS | Orals | EOS1.8

Surfing the Climate Wave: Laura and Joan's Expedition in the Delta  

Anna Boqué-Ciurana, Josep Maria López Madrid, Eloi Carbonell, Enric Aguilar, and Carlos Lozano

Embark on a compelling narrative that chronicles the experiences of Laura and Joan, students participating in a field trip to the Delta del Ebre, responding to a collaborative initiative spearheaded by the Center for Climate Change (C3) at the Universitat Rovira i Virgili (URV). This narrative is shaped by the surf-centric climate services thesis of Dr. Anna Boqué, emphasizing the seamless integration of academic research into pragmatic climate mitigation measures. 

 Notably, the realization of this initiative is indebted to the steadfast support of the Department of Research and Universities of the Generalitat de Catalunya. Laura and Joan, guided by insights from the URV's Climate Change Research Center, engage in data analysis and strategic formulation of climate crisis interventions, exemplifying the transformative potential of interdisciplinary collaboration. 

 This story, available in both Catalan and English, forms an integral part of a collection disseminated to educational institutions and libraries. The accompanying website offers a didactic guide and a diverse array of materials for a thorough exploration, underscoring the intersection of academic research, climate services, and community-driven initiatives. Join us in acknowledging the catalyzing impact of collaboration and recognizing the pivotal role played by the Generalitat de Catalunya in empowering students to contribute meaningfully to a resilient and sustainable future. 

We acknowledge Carlos Lozano, Montse Español, Xavier Gómez Cacho, and Jordi Sales for their contribution to this work. 

 

How to cite: Boqué-Ciurana, A., López Madrid, J. M., Carbonell, E., Aguilar, E., and Lozano, C.: Surfing the Climate Wave: Laura and Joan's Expedition in the Delta , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8799, https://doi.org/10.5194/egusphere-egu24-8799, 2024.

The presentation intends to reflect about the relevance of narrating the climate crisis, by taking into account an ongoing initiative promoted by the Department of Environmental, Land and Infrastructure Engineering (DIATI) of Politecnico di Torino (PoliTo) called, indeed, “Narrare la crisi climatica”.

“Narrare la crisi climatica” is this year edition of an 8-year long initiative called “Conversazioni in Biblioteca” (Conversations in the Library). The Conversations aim to stimulate dialogue between hard sciences and social and human sciences, on topics related to environmental issues in the broader sense. The Conversations are open to the public, but they are also addressed to the wide PoliTo student community, to enhance their transdisciplinary skills.

With this year edition (the title can be translated into “Narrating the climate crisis”), we, as curator of the initiative, decided to invite, besides hard and social-human scientists, also people coming from what is usually called the “creative” domain (art, design, storytelling and writing, music, filmmaking, theater, etc.).

The presentation will analyze and discuss the way in which these three different forms of knowledge come together to dialogue around climate crisis and the way to narrate it.

We, as curators, have chosen the words “narrating” and “storytelling” knowing that human beings think, reason, understand and plan by telling stories to each other, and also knowing that the stories they tell themselves are not necessarily lies, quite the contrary. Even a scientific article, when it has to give an account of a transformation, a process, and the actions that have led to circumscribe it, highlight it, describe it, compare it, define it and perhaps explain it, will inevitably rely on a narrative.

We know that one of the strengths of narration is precisely its capacity to involve, to affabulate, to engage in a world, shared between the storyteller and those who participate in the narration and enjoy it, in order to come out, in the end, somewhat transformed - a transformation, therefore, that does not only concern the characters, events and facts narrated, but, on another level, also those who narrate and are narrated by them.

We know that these properties of narration do not only take place through words, which is why we decided to include in the conversation other expressive languages capable of creating a point of contact between scholars and the public.

Our interest in narration started also by considering Amitav Ghosh’s reflection about the inability of literature and art in general to deal with climate change and to narrate it, as a real imaginative failure (see Ghosh, The Great Derangement: Climate Change and the Unthinkable (2017)). We somehow wanted to probe if from 2017, when Ghosh published his reflection, up to now something was changed and if further change could be initiated by putting together three people for two hours discussing their experiences with the issue.

The presentation will analyze and reflect upon the interaction between the three forms of knowledge generated through the conversations.

How to cite: Vanin, E. and Mattozzi, A.: “Narrating the climate crisis” – an experiment in the form of a series of conversations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11888, https://doi.org/10.5194/egusphere-egu24-11888, 2024.

EGU24-12511 | Orals | EOS1.8

Justice and urban transformation in light of accelerating climate change  

Karsten Haustein, Hannes Zacher, Katja Liebal, Marie Eichholz, and Ulrike Mühlhaus

Climate change adaptation in urban spaces will only be successful if societal actors from science, politics and public find common ground, and join forces on a local level. One of the sectors that is notoriously difficult to transform in a sustainable way is transportation, and linked to it the way we design our cities. Bike infrastructure is almost universally under-developed (apart from notable exceptions such as Utrecht, NL, or Copenhagen, DK), putting marginalised people at a massive disadvantage in that they cannot freely choose which mode of transport to use. The structural privilege for motorists in virtually all post-war western societies is so prevalent, that even mentioning of the shear existence of those privileges is considered offensive and met with huge outcry and media frenzy in support of the status quo.

So how to address the issue, given the fact that a host of transformative steps are undoubtedly required to make urban spaces future proof? How are we raising awareness to the fact that the externalised costs of excessive car use in cities are vastly underappreciated - be it health related costs due to noise and air pollution, accidents, lack of exercise; environmental costs due to carbon emissions; infrastructural investments; or the lack of greenery due to parked cars, and so on? In short, how can we change the conversation such that justice and visionary thinking (rather than fear) become front and center of the discourse?

We show how tailored science communication can help to expose preconceived notions and thus reduce conflict between various actors. The strategy is based on solid evidence, which highlights the hidden costs of currently privileged modes of transport. Also, it demonstrates why certain arguments in support of the status quo are deeply flawed. Using expertise from colleagues in the social sciences (organizational psychology), we aim at understanding why decision makers act so hesitantly. Ultimately, a list of guiding principles when it comes to constructive dialogue - and identifying bad faith actors - will be developed (with the help of experienced societal actors) and disseminated amongst decision makers but also colleagues in disciplines with similar levels of public controversy. First results are presented at EGU’24.

How to cite: Haustein, K., Zacher, H., Liebal, K., Eichholz, M., and Mühlhaus, U.: Justice and urban transformation in light of accelerating climate change , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12511, https://doi.org/10.5194/egusphere-egu24-12511, 2024.

The University of Graz Wegener Center has recently opened a new data portal termed Graz Climate Change Indicators (GCCI). It is accessible via https://gcci.earth (present version v2) and is currently receiving a substantial further upgrade (to GCCI v3) that will be released later in 2024. The data portal helps to bridge climate science, narratives and action and provides, in an easy-to-use way with focus on informative time series, reliable recent-past monitoring information jointly with current-state nowcasting and Paris-compliant future projection information, over the critical climate change timeframe from 1960 via the present to 2050.

In doing so, the GCCI portal focuses on three indicator classes that span the climate change problem, and projected solution pathways, from causes to impacts: greenhouse gas emissions (GEM-GHG Emissions Monitoring), global warming (CWM-Climate Warming Monitoring), and climate change impacts in terms of weather and climate extremes (EWM-Extreme Weather Monitoring, released spring 2024). The geographic domains included (GeoDomains) range from Global (GLO) via Europe (EUR) to Austria (AT), with the countries and regions within a domain (GeoRegions) covered by relevant indicator time series (GCCI v2 including GLO-EUR-AT domains for GEM and GLO for CWM).

We briefly introduce the overall GCCI design, including its open data and open science approach, which is made to enable broad uptake and to support climate solution narratives on “pathways to Paris”, also linking to the co-developed climate solutions framework “Carbon Management – carbsmart2Paris” (website https://carbmanage.earth). We then discuss climate action and policy relevant example use cases, from backing emission reduction policymaking to creating awareness for and understanding the links from emissions via greenhouse gas concentrations and radiative forcing to global warming in terms of global surface temperature increase and other changes. These exemplary uses and related narratives intend to highlight how the easy-to-use availability, and simple-to-add expandability, of scientifically reliable recent, current, and projected climate change key data may encourage and empower actors to exercise more climate-change-aware and climate-solutions-oriented decision making.

Overall, the GCCI data portal wants to bring, besides its value also for research and teaching, a clear added-value to policy makers, other stakeholders and the broader public, by helping science-back their climate narratives and action efforts towards reaching the Paris climate goals.

How to cite: Kirchengast, G. and Pichler, M.: Graz Climate Change Indicators: A data portal backing climate narratives towards reaching the Paris climate goals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12998, https://doi.org/10.5194/egusphere-egu24-12998, 2024.

Scientific news in Bulgaria is not a high priority as there are not many specialised media to systematically cover the information flow, and scientific discoveries in the daily news are mostly covered by editors of international news and often appear in the sections titled Curiosity. The present study does not go into an analysis of the causes and consequences of these biases, although the problem of misinformation in science is largely rooted in the lack of professionalism in the field, as science news is not directly related to political misinformation, but could influence the societal reception. Still, mis/disinformation often permeates science news as well. Till now, the misinformation in scientific news in the Bulgarian linguistic field has not been research topic, exceptions are the analyses related to the provocations around the Green Deal (CSD, 2023) and indirectly to climate change.

This study tries to identify and compare the main narratives related to misinformation and science in the online space and analyzes some interesting cases of fake news in the media space in Bulgaria. Lewandowsky defines several disinformation strategies in science news: undermine and question the scientific consensus, highlight scientific uncertainty and demand certainty as a condition for climate action, attack individual scientists to undermine their credibility, undermine institutions in general, such as peer review, pseudoscientific alternatives through a network of blogs (Lewandowsky, 2021). These strategies are also visible in the Bulgarian space, and identifying the main narratives can serve as a possible inoculation against future misinformation.

The methodology involves, on the one hand, the manual monitoring and identification of controversial news related to science from Bulgarian online media. Specific cases are analyzed in an attempt to typify the narratives. On the other hand, technology has also been used to extract the topics by keywords related to science and climate change from very large online media platforms. The results of both approaches provide a picture of possible narratives and issues related to the representation of scientific news in the Bulgarian linguistic field.

Among the most shared news stories emerged not those that were scientific, but pseudoscientific ones related to dubious health advice, astrology and conspiracy theories. In this sense, the strategy of questioning the scientific consensus, undermining institutions and usining pseudoscientific alternatives is obvious. Scientific hoaxes related to Bulgarian history, as well as to everything Bulgarian, have emerged as a characteristic feature of Bulgarian social networks. Generative artificial intelligence is also a frightening topic. On the other hand, a topic like Global Information Systems is hardly touched upon, except by highly profiled publications, which can be considered a good sign.

Based on the narratives found, future prebunking and inoculation could be done. The narratives can be compared with those emerging in the post-Soviet space in other European countries and Europe in general, and in this sense, the study is a step toward a more general understanding of the processes of mis and disinformation in the scientific news flow not only in Bulgarian.

How to cite: Margova, R.: Misinformation in scientific news in Bulgarian for future inoculation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15618, https://doi.org/10.5194/egusphere-egu24-15618, 2024.

EGU24-15895 | ECS | Orals | EOS1.8

GeoTraductores: one translation at a time 

Daniela Navarro-Perez, Anthony Ramírez-Salazar, Sofía Barragán-Montilla, Mariela Garcia Arredondo, Caryl-Sue Micalizio, Angelique Rosa Marín, and María Alejandra Gómez Correa

GeoTraductores, a collaborative initiative involving Eos.org, GeoLatinas, and Planeteando, aims to overcome the language barrier in climate change and Earth science communication within Spanish-speaking communities. To accomplish this, science articles from Eos.org have been translated into Spanish by approximately 40 volunteers as part of the Eos en Español project. Around 85% of our team comprises  Latin women,  who have translated over 150 articles, contributing to expanding the Spanish-speaking audience of Eos.org and solidifying the initiative’s success. This strategic translation effort not only enhances accessibility but also promotes the representation of Latin American Early Careers Scientists, many of whom reside and work in predominantly English-speaking countries.

Since 2020, the GeoTraductores initiative has been co-led by (1) members of the non-profit organization GeoLatinas dedicated to embracing, empowering, and inspiring Latinas in Earth and Planetary Sciences; (2) Planeteando, a Mexican scientific and social outreach project in Earth and Environmental Sciences; and (3) Eos.org, the science news magazine published by AGU. Each party plays a distinct role in the initiative: (1) volunteer recruitment of translators is handled by GeoLatinas and Planeteando, (2) proofreading and editing of the translated articles is mainly led by Planeteando, and (3) the articles and platforms to make the final Spanish translation available are provided by Eos.org. In a broader effort, all involved collaborators utilize their social media platforms to make this bilingual content more accessible to a wider readership.

Throughout this initiative, the GeoTraductores volunteers benefit by improving their English and translation skills, gaining visibility on social media, and making an altruistic contribution to the Latin American general public. Collaborators also benefit from engaging and gaining a wider audience to communicate science, as they foster the capacity building of volunteers, promoting a science communication co-production, and boosting each other. Overall, GeoTraductores is forging a pathway to democratize science, particularly in Latin America. Through establishing and strengthening a network of expert bilingual science communicators, this initiative addresses historical language barriers that impede the accessibility and dissemination of scientific information to the general public. By empowering volunteers and embracing diversity, GeoTraductores paves the way for expanding multilingual spaces within Earth and Planetary sciences one translation at a time.

How to cite: Navarro-Perez, D., Ramírez-Salazar, A., Barragán-Montilla, S., Garcia Arredondo, M., Micalizio, C.-S., Rosa Marín, A., and Gómez Correa, M. A.: GeoTraductores: one translation at a time, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15895, https://doi.org/10.5194/egusphere-egu24-15895, 2024.

“Writing The Earth” was an interdisciplinary and collaborative programme between the Irish Writers Centre and the SFI Research Centre in Applied Geosciences, which brought six creative writers and ten geoscientists together to research and write about climate and geoscience in various genres or narrative forms to reach new public audiences.

In a collaborative process of talks, facilitated workshops and mentoring across six months, the programme brought the worlds of geoscience and creative writing together. New writings to have been created and performed for the public through the programme included: scenes from two new plays that explore the health of the planet and mass extinction through razor-sharp satire and earnest pathos. Other writings explored the intimate human connection between worker and object, consumer and extracted raw materials, and our relationship with groundwater through the lens of family history, mythology and science.

Writing the Earth sought to explore the commonality between geoscientists and writers as both narrators and observers of our world, and to create a safe space for deliberation, dialogue and creative expression on what can sometimes be complex, and contentions, geoscience topics. Central to the success of the programme, and in the creation of the new narrative writings, was the geoscientist-writer relationship. What a geoscientist does is to research and investigate a topic methodically, and to reach conclusions based on a series of observations which are often complex to explain to a general audience. What a writer often does is to make sense of our world, often the indecipherable parts of our existence, through language, imagery and emotion.  Whether scientist, or writer, both ultimately use the written word to describe the world to the reader.

We will share our experiences of running a creative, interdisciplinary programme, short extracts from the new writings, the results of the pre-, mid- and post-evaluation, and key takeaways on how to run a similar programme.

How to cite: McAuliffe, F., Bistany, V., and O'Rourke, F.: Writing the Earth: what happens when you bring creative writers and geoscientists together to explore climate and sustainability issues?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16502, https://doi.org/10.5194/egusphere-egu24-16502, 2024.

EGU24-17203 | ECS | Orals | EOS1.8 | Highlight

A Digital Academy against Climate Change Disinformation featuring trustworthy and fact-checked information and resources on climate change and media literacy. 

Spyridoula Markou, Adam Doulgerakis, Anna Triantafillou, Arianna Acierno, Mauro Buonocore, and Alfredo Reder

This paper reports on the design and development of a Digital Academy against Climate Change Disinformation providing citizens with trustworthy information and resources on climate change, as well as fact-checked information from credible sources. The objective of the Digital Academy is to enable citizens to browse through: a) trustworthy information, such as articles and scientific publications; b) fact-checks that debunk climate change disinformation; c) relevant resources, such as media literacy material; and d) reports on the state of disinformation around climate change.

The Digital Academy against Climate Change Disinformation is part of the AGORA project’s digital tools, delivered through the AGORA project’s Digital Agora living digital environment that enables stakeholders, scientists, experts, media and citizens to network and communicate, to find peers and other communities from other geographical or societal contexts to share challenges and needs, facilitating multidisciplinary, integrated approaches to societal transformation. Aspiring to play a crucial role in the collective efforts to tackle climate-related disinformation and drive societal transformation, the Digital Academy aims to enhance individual skills, foster collaboration, and provide credible sources for empowering local communities in addressing the climate crisis. 

The material (modules and resources) that is made available through the Digital Academy is structured in three main sections, namely (i) Climate Change, (ii) Media Literacy, and (iii) Resources. The Climate Change section includes modules, focusing on climate change, climate communication, and climate disinformation, and aims to equip users with a comprehensive understanding of climate-related challenges. Additionally, the Digital Academy actively counters climate change disinformation by providing debunks and reliable information. Recognizing the importance of media literacy in the digital age, the Media Literacy section includes modules on critical thinking, digital literacy, fact-checking, and verification, aspiring to empower users to navigate the digital landscape with confidence. The Resources section encompasses climate fact checks, reports on climate change and adaptation, and a wealth of tools and approaches. Case studies and stories within this section share experiences, highlighting enablers, barriers, and lessons learned from ongoing implementations.

In summary, the Digital Agora stands as a comprehensive platform, promoting informed decision-making, climate resilience, and media literacy. Through its diverse modules and extensive library of resources, the Digital Agora aims to create a resilient community equipped to address the challenges of climate change and disinformation.

Acknowledgement: The presented work is part of the AGORA Project and it is funded by the European Union through the European Union’s Horizon Europe Research and Innovation Actions under grant agreement No 101093921. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.

How to cite: Markou, S., Doulgerakis, A., Triantafillou, A., Acierno, A., Buonocore, M., and Reder, A.: A Digital Academy against Climate Change Disinformation featuring trustworthy and fact-checked information and resources on climate change and media literacy., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17203, https://doi.org/10.5194/egusphere-egu24-17203, 2024.

EGU24-17910 | Orals | EOS1.8 | Highlight

We Are the Possible: New Narratives Connecting Science, Health, Education and the Arts 

Cecilia Manosa Nyblon and Sally Flint

Our future is unwritten, it will be shaped by who we choose to be and the actions we take now individually and collectively. At the University of Exeter (UoE) we have pioneered a new way of communicating climate science that really engages people intellectually and emotionally in the lead up to and at major international negotiations to feel the drive to respond to the call to action. Building on the long term legacy, narrative, and impact of our UoE’s  We Are the Possible (UAE 2023), We Still Have a Chance (Egypt 2022) and One Chance Left  (UK 2021), delivered successfully at the diplomatic and public spaces at COP, we have connected the UK and our global partners at the heart of the international conversation on confronting the climate crisis with determination, imagination, and hope, bridging the gap between science and the public.

 

Our purpose is to use the platform of COP to communicate new climate narratives, linking science, health, arts, and education and build strategic partnerships to raise awareness of the urgent need for collective climate action among children, young people, policy makers and the public. To achieve our purpose, we co-create new narratives underpinned by world-class science. These new narratives are the bedrock for translation into sustainable theatre performances, large scale murals, music and soundscapes, digital visualisations and animation, education toolkits, workshops, storytelling events, and more. We will discuss the power of linking storytelling and new media possibilities to catalyse climate action and solutions with diverse audiences locally and globally.

How to cite: Manosa Nyblon, C. and Flint, S.: We Are the Possible: New Narratives Connecting Science, Health, Education and the Arts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17910, https://doi.org/10.5194/egusphere-egu24-17910, 2024.

EGU24-18318 | Posters on site | EOS1.8

A co-production methodology for high-quality climate services: An example from the health sector.  

Inés Martín del Real, Marta Terrado, Diana Urquiza, Paula Checchia Adell, Alba Llabrés-Brustenga, and Antonia Frangeskou

Appropriate co-production of climate services with a wide range of knowledge- and stakeholders, as well as optimal networking and the creation of lasting partnerships, has been identified as crucial for the success of climate services solutions. This requires the involvement of both providers and end users, enabling a multi-way knowledge exchange and continuous joint learning. Continuous engagement with diverse actors, including stakeholders, climate scientists, science communicators, social scientists and user experience experts, facilitates the production of quality, fit-for-purpose and reliable knowledge for climate risk management and the improvement of adaptive capacities (Bojovic et al. 2021).

This poster explains the application of the knowledge co-production framework for climate services developed by the Knowledge Integration Team (KIT) of the Earth System Services group at the Barcelona Supercomputing Center (BSC). It addresses the crucial role of participation, collaboration and communication in achieving successful co-production between climate service providers and users. Using an example from the health sector and illustrated through a cartoon, the poster explains what climate services are. Our approach not only enables user empowerment (who, in the case of this narrative, are health practitioners) but also encourages transformative learning for all involved in the process. 

The creation of high-quality climate services is fostered by the development of ‘standards’ for climate services. These standards should ensure relevance, credibility, legitimacy and authority, thus creating a two-way trust between the provider and the end user. Due to the complexity of climate services, to address their standardisation, Baldissera Pacchetti, M & St. Clair, A.L. (2023) proposes to break them into some high-level components, such as decision context, coproduction, knowledge systems and delivery mode. In terms of delivery, different products and services will be created to serve and accompany a variety of end users with specific needs. 

When considering health practitioners, Early Warning Advisory Systems as a delivery product support early actions to protect the region from existing and emerging climate-related health threats and help target effective interventions, if needed. Climate change together with other environmental and socio-economic changes influences the activity of vectors capable of transmitting infectious diseases in Europe. This poster will introduce the process of co-creating a seasonal indicator platform linking seasonal climate predictions with new climate change and eco-epidemiology indicators for different vector-borne diseases. This provides an example of good co-production practices connecting providers and end users through a more integrated OneHealth approach, and facilitating the uptake of climate services by society. 

 

References:

Baldissera Pacchetti, M & St. Clair, A.L. (2023), Framework to support the equitable standardisation of climate services, D1.2 of the Climateurope2 project

Bojovic, D., Clair, A. L. S., Christel, I., Terrado, M., Stanzel, P., Gonzalez, P., & Palin, E. J. (2021). Engagement, involvement and empowerment: Three realms of a coproduction framework for climate services. Global Environmental Change, 68, 102271.

How to cite: Martín del Real, I., Terrado, M., Urquiza, D., Checchia Adell, P., Llabrés-Brustenga, A., and Frangeskou, A.: A co-production methodology for high-quality climate services: An example from the health sector. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18318, https://doi.org/10.5194/egusphere-egu24-18318, 2024.

 

Climate change is seriously affecting glaciers across the entire planet and particularly the Alpine regions. Frequency and intensity of natural disasters as landslides, flash floods and avalanches are increasing and the dramatic retreat of Alpine glaciers inevitably compromises the water reserves endangering both economic activities and ecosystem services.

The Adamello glacier is the largest and deepest glacier in Italy: it represents one of the most valuable archives of the climatic, environmental, and human history of the Italian Alps. The ClimADA project (2022-2023), financed by Cariplo Foundation, Lombardy Region, and other public and private organizations is being developed by an extensive cooperation between universities and institutional bodies, coordinated by the Lombardy Foundation for the Environment, aiming at reconstructing its geo-ecological history and its dynamics in terms of mass and energy balances on the basis of field data, climate projections and mathematical models.  The ice cores extracted through a deep drilling that reached the bottom bedrock (225 m below the ice surface) are providing unique records of the glacier’s physical, chemical and biological history of the last 1000 years. Innovative optical fibre techniques have been employed to trace temperature and strain of the 3D ice mass profile providing relevant information of the glacier present and future dynamics.

The unfavourable projections based on plausible climate change scenarios are predicting an ever-increasing loss of ice mass and surface with a complete fusion of the entire glacier within the present century. The environmental, social and economic consequences of this scenario are raising great concern among the local communities, the tourism operators and the public opinion. To cope with this threat and to better exploit new potential opportunities for the local Alpine communities, the project has been promoting a intense dialogue between the scientific  community involved in the project, the local policy makers and the stakeholder organizations in order to design, discuss and develop an integrated climate change adaptation strategy capable to harmonize the local economic sustainable development and a more effective policies to protect the natural capital and the related ecosystem services.

For these reasons, the ClimADA project, organized a dense and effective campaign to raise awareness of the territory, of the public administrations and all citizens: the awareness campaign was structured into distinct but complementary and closely interconnected activities. The final objective of the project is to make the effects of climate change and its consequences on the territory, the environment and current and future water availability clear and understandable, stimulating important reflections on respect and protection of the environment in which we live and motivating adequate behaviours and actions.

Through the analysis of historical images and an intense photographic field surveys activity, the project has developed a large amount of information material: photographic comparisons, data, and analyses on the glacier, information panels (installed near the alpine refuges) and multimedia material (time -lapse videos, glaciological animations) to be used for educational (schools) and informative purposes. The involvement of local and national television media was also fundamental, with which the ClimADA project reached millions of viewers across the nation.

How to cite: Picco, S., Lapi, M., and Ballarin Denti, A.: ClimADA Project: a successful interaction between science community, decision makers and citizen to raise awareness and train expertise around the impact of climate change on the Alpine environment., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18744, https://doi.org/10.5194/egusphere-egu24-18744, 2024.

Fondazione Lombardia per l‘Ambiente (FLA) - Lombardy Foundation for the Environment is an Italian private, non profit, foundation established in 1986 by the Lombardy Regional Administration and five major universities of Lombardy.

 

The foundation's work is functional to promote regional Environmental Education initiatives, to enhance and give them visibility. It is also precious to facilitate communication between Lombardy Region and the local entities dealing with these issues, as well as between educational supply and demand, from a networking and subsidiarity perspective.

 

It is a real mission, carried out through training activities, events, publications, collaborations aimed especially at schools, students and the younger generation.

 

In this context, correct information is promoted to this public and, more generally, to the citizenship, enhancing the foundation's vast scientific heritage. The goal is to support the growth of the culture of sustainability with trustable information.

 

This is a real antidote to the spread of fake news and misleading information, which is increasingly widespread in Italy in relation to climate change issues. The development of initiatives aimed at educators and students is also crucial to combat this problem at its root.

 

FLA organizes several initiatives annually, often in cooperation with organizations and associations in the sector, e.g. Regional Environmental Education Fair (Fiera di Educazione alla Sostenibilità Ambientale) that support the creation of the regional Environmental Education network and program and engaged one thousand students last October. Other activities are The Astronomy week with conferences and exhibition dedicated to the study of space.

 

FLA also promotes a tender on Environmental Education proposals to select high quality education projects for the development of environmental education and sustainability education on the territory. Around 200 projects were submitted at the three annual editions.

 

At the institutional level, FLA manages the regional environmental education portal on behalf of the Lombardy Region. It is a communication channel intended for a plurality of actors also and precisely to strengthen communication between the protagonists of this system of education and dissemination of a correct environmental culture, through the dissemination of documents, publications, and informative materials.

 

FLA also launched a journalism project called Redact-Us and developed in collaboration with Association Together and the newspaper Il Sussidiario.net, which trains students in the profession of journalist and communicator by providing the appropriate tools to communicate sustainability. As part of this activity, a survey was conducted on the interest and commitment of the younger generations in the environmental field.

 

In the last ten years, environmental education activities promoted by Lombardy Foundation for the Environment engaged more than 23.000 students in Lombardy and other Italian Regions.

 

This work is useful not only to promote correct information, but also to develop a special, evidence-based sensitivity towards nature.

How to cite: Picco, S. and macalli, S.: Environmental education and correct scientific information on climate change and natural issues: the case of Lombardy Foundation for the Environment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19620, https://doi.org/10.5194/egusphere-egu24-19620, 2024.

EGU24-20900 | Orals | EOS1.8 | Highlight

Climate Narratives: Empowering Voices for a Sustainable Future.  

Gaura Naithani

How a pan-European training programme is supporting scientists, journalists and content creators to reach younger audiences with their climate stories.

As heat records continue to be broken across Europe, hard-hitting, impactful climate and environmental journalism has never been more sorely needed. The European Journalism Centre (EJC) thus identified that investigating these topics and discussing potential solutions for environmental issues is a crucial public service, especially given the role played by the media in shaping the discourse around the climate crisis. 

However, the way Europeans are getting their news is also changing. More than a third (34%) of 15-24-year-olds in the EU follow news primarily on YouTube or other video platforms, compared to only 8% of people aged 55+, according to the Eurobarometer Media & News Survey 2022. With young people rapidly migrating from traditional print, broadcast, and digital to social and streaming platforms, independent journalists and freelancers need to keep up if they want to reach audiences where they are. Additionally, as climate science evolves, journalists must navigate interdisciplinary research and solutions-oriented approaches to communicate compelling stories to diverse audiences. EJC strongly believes that interdisciplinary collaboration between climate scientists,journalists and content creators is a stronger approach to respond to this critical global issue and counter news fatigue simultaneously.

To achieve this, in 2023, the EJC partnered with YouTube to develop an in-person training program that explored the vibrant intersection between journalism and climate science. For this, 21 video-first news creators, climate scientists, and journalists across Europe were mentored by EJC and experts from Deutsche Welle, Vice News, and YouTube. The main objective was to equip the participants with tools and knowledge to:

  • Debunk misinformation around climate change.
  • Develop creative storytelling formats to simplify complex climate stories.
  • Identify sustainable revenue models for their YouTube channels.
  • Navigate the platform’s algorithms to counter filter bubbles.
  • Collaborate with each other (journalists and non-journalists).

As a result:

  • UK-Based climate scientist Ella Gilbert recorded a 7.5% increase in the "Click Through Rate" on her videos after updating her thumbnails. Her content focuses on debunking climate fake news.
  • Dr. Adam Levy, a doctor in atmospheric physics at the University of Oxford, who runs the YouTube channel “Climate Adam,” collaborated with Germany-based “Migration Matters.” Together they produced a 10-minute-long video explaining climate migration across the globe. The video currently has over 23K views!
  • PhD scholar and freelance video presenter Roshan Salgado, who runs the YouTube channel “All About Climate,” also shared inputs from his research that focuses on communicating climate change in modern media. The bootcamp helped him transform his climate change facts into a compelling newsworthy script.

This bootcamp contributes towards EJC’s larger vision to foster a resilient digital news ecosystem in Europe, in which trustworthy climate content stands out and is trusted over disinformation.

 

How to cite: Naithani, G.: Climate Narratives: Empowering Voices for a Sustainable Future. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20900, https://doi.org/10.5194/egusphere-egu24-20900, 2024.

EGU24-3603 | ECS | Posters on site | EOS4.3

Bridging the gap between climate scenarios and law - a roadmap for mutual contributions 

Haomiao Du, Edward Brans, Murray Scown, Hsing-Hsuan Chen, Vassilis Daioglou, Mark Roelfsema, Annisa Triyanti, Dries Hegger, Leila Niamir, Marleen van Rijswick, Liping Dai, Peter Driessen, Yann du Pont, Dennis van Berkel, and Detlef van Vuuren

To bridge the knowledge gap between climate scenarios and law, this presentation is aimed to demonstrate currently demanded mutual contributions by legal professionals and integrated assessment modellers on 1) how legal knowledge can be integrated into climate scenarios and 2) how scientific evidence generated from climate scenarios can better guide climate litigation cases. We expect that this could support judges in making trade-offs in climate-related court cases and could contribute to the acceptance of decisions by judges in such cases. Given the emissions gap and the measures that must be taken to comply with the Paris Agreement, the latter is likely becoming more relevant.

Regarding the first part, the results are based on an empirical research project on Improving the Integration of Legal Knowledge and Scholars in Climate Scenario Assessments (https://www.uu.nl/en/research/sustainability/improving-the-integration-of-legal-knowledge-and-scholars-in-climate-scenario-assessments) and a workshop  (https://www.uu.nl/en/research/sustainability/workshop-report-promoting-the-mutual-understanding-between-legal-and-governance-scholars-and-climate) resulted from this project held in May 2023. Via interviews and focus-group discussions with 24 experts in climate modelling, climate law and politics, and ethics, our research highlights four legal aspects for integration, which are: 1) implementation end enforcement of climate targets, 2) key normative principles, 3) legal uncertainties, and 4) the applicability of scenarios in regional and local legal contexts. Considering the challenges of integration due to epistemic distinctions between disciplines, experts held different opinions on the feasibility of integrating those four aspects. Regarding actionable steps for the short term, revising narratives and a ‘legal reality check’ are the most agreed ones. The former refers to adding legal obligations that safeguard justice, fairness and fundamental human rights - traceable to various treaties - to narratives of the global futures. The latter refers to scrutinising the ‘shared feasibility space’ between law on the one hand and modelled scenarios and emission reduction pathways on the other: it can be the compatibility of legal principles with modelled scenarios based on different assessment criteria (e.g. fair share of burdens), or to compare scenarios with and without regulatory boundary conditions in a specific jurisdiction on a specific mitigation solution (e.g. BECCS scenarios).

Regarding the second part, the currently ongoing research focuses on the adoption of authoritative scientific evidence from climate scenarios - typically the projections referred to in the IPCC reports - in climate litigation cases. First, inspired by the Daubert Criteria, this research explores the possibility of developing guidelines for judges to deal with scientific uncertainties contained in multiple projected futures and determining admissibility of scientific evidence. Second, seeing the increasing reference to ‘open norms’ (e.g. due diligence, fair share) and fundamental human rights (to private life or a healthy environment) in court cases, modelled scenarios could provide information for guiding judges in their interpretation of key concepts such as carbon budgets, fair share, emission gap, appropriate emission reduction obligations, and climate-induced harm and loss and damage. We expect that this could be beneficial to the supportability of judges' decisions in climate cases.

How to cite: Du, H., Brans, E., Scown, M., Chen, H.-H., Daioglou, V., Roelfsema, M., Triyanti, A., Hegger, D., Niamir, L., van Rijswick, M., Dai, L., Driessen, P., du Pont, Y., van Berkel, D., and van Vuuren, D.: Bridging the gap between climate scenarios and law - a roadmap for mutual contributions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3603, https://doi.org/10.5194/egusphere-egu24-3603, 2024.

EGU24-5662 | ECS | Posters on site | EOS4.3

Litigation challenging over-reliance on carbon dioxide removal requires quantitative feasibility assessment 

Oliver Perkins, Peter Alexander, Almut Arneth, Calum Brown, James Millington, and Mark Rounsevell

Carbon dioxide removal (CDR) is an emerging frontier in climate change litigation1. CDR must play an important role in achieving global climate targets, by compensating for hard-to-abate emissions (such as from international transport). Yet, over-reliance on CDR in government and corporate decarbonisation plans may serve as a strategy to commit to climate action on paper, whilst making inadequate present-day emissions’ reductions. Therefore, litigation may be necessary to highlight where CDR commitments contribute to a credible decarbonisation plan, and where they are primarily employed as a delaying tactic. Hence, litigation arguing that a given level of CDR deployment represents an unacceptable risk to the achievement of legal climate targets must have clarity around plausible levels of real-world delivery.

Land-based CDR methods, such as afforestation and bioenergy with carbon capture and storage, frequently appear in both modelled decarbonisation scenarios and government policies. Here, we argue that quantitative assessment of the feasible potential of land-based CDR is vital to the success of CDR-focused litigation. Firstly, we highlight key land system processes that will constrain real-world CDR delivery to levels well-below the techno-economic assessments presented in the IPCC 6th Assessment Report (AR6). These constraining processes include land tenure and food insecurity, monitoring and verification, and impermanence due to biophysical disturbances and policy change. Quantifying the likely impact of such factors can fast-track successful CDR litigation by demonstrating the scale of the gap between CDR pledges and plausible real-world potentials.

Further, after Perkins et al., 2, we outline research frameworks that can deliver a quantified feasible potential for land-based CDR within the IPCC AR7 process, and highlight emerging trans-disciplinary methods making progress towards this goal. These methods include geospatial coupled socio-ecological model ensembles, which can capture interactions and feedbacks between socio-economic and biophysical drivers in the land system at global scale. Typically, such ensembles include coupling of spatial agent-based models of land user behaviour with dynamic global vegetation models and non-equilibrium agricultural trade models - which can represent system shocks such as geopolitical instability and extreme weather events. We conclude by arguing that quantitative feasibility assessment must be made a high priority in CDR research to prevent widespread over-reliance on CDR in decarbonisation policies.

1. Stuart-Smith, R.F., Rajamani, L., Rogelj, J., and Wetzer, T. (2023). Legal limits to the use of CO2 removal. Science 382, 772–774. 10.1126/science.adi9332.

2. Perkins, O., Alexander, P., Arneth, A., Brown, C., Millington, J.D.A., and Rounsevell, M. (2023). Toward quantification of the feasible potential of land-based carbon dioxide removal. One Earth 6, 1638–1651. 10.1016/j.oneear.2023.11.011.

How to cite: Perkins, O., Alexander, P., Arneth, A., Brown, C., Millington, J., and Rounsevell, M.: Litigation challenging over-reliance on carbon dioxide removal requires quantitative feasibility assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5662, https://doi.org/10.5194/egusphere-egu24-5662, 2024.

EGU24-8458 | ECS | Posters on site | EOS4.3

Save the Climate but Don’t Blame Us: Corporate Responses to Climate Litigation 

Noah Walker-Crawford

Fossil fuel companies are no longer denying anthropogenic climate change in recent climate litigation but question the validity of climate science for establishing legal responsibility. Past research on social movement legal mobilization has primarily focused on plaintiffs’ perspectives, showing how they use the judicial process as a site of knowledge production. Drawing attention to the other side, I conduct an analysis of scientific disputes in major climate change lawsuits and develop a typology for studying defendants’ evidentiary arguments. Defendants build evidentiary counter-narratives, challenge the substantive quality of plaintiffs’ claims, and attack the scientific integrity of compromising evidence. Litigants’ legal narratives and factual claims are linked to broader normative concerns about how the underlying issues should be resolved. Fossil fuel companies’ legal arguments reflect broader strategies to evade responsibility for climate change.

How to cite: Walker-Crawford, N.: Save the Climate but Don’t Blame Us: Corporate Responses to Climate Litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8458, https://doi.org/10.5194/egusphere-egu24-8458, 2024.

EGU24-12601 | ECS | Posters on site | EOS4.3

Towards Evaluating the Financial Responsibility of Carbon Majors for Climate-Related Damages 

Marina Andrijevic, Carl-Friedrich Schleussner, Jarmo Kikstra, Richard Heede, Joeri Rogelj, Sylvia Schmidt, and Holly Simpkin

In light of the global energy crisis and escalating climate change impacts, the liability of major fossil fuel companies is receiving heightened scrutiny, particularly in the context of climate litigation. This study initially establishes the feasibility of attributing climate damages to these companies. Utilizing the social cost of carbon methodology, we evaluate the damages inflicted by the top 25 oil and gas emitters from 1985 to 2018, comparing these to their financial profits. Our central estimate suggests partial damages of approximately 20 trillion USD, with the companies’ financial gains surpassing this by 50%, totaling around 30 trillion USD. This indicates the potential of carbon majors to cover their attributed damages while maintaining significant profits. In our analysis, we also explore how varying approaches to assigning responsibility and handling uncertainties in climate damages can markedly influence these findings. Additionally, we explore the role of sovereign wealth funds in perpetuating fossil-fuel derived wealth and the ensuing liability questions.

How to cite: Andrijevic, M., Schleussner, C.-F., Kikstra, J., Heede, R., Rogelj, J., Schmidt, S., and Simpkin, H.: Towards Evaluating the Financial Responsibility of Carbon Majors for Climate-Related Damages, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12601, https://doi.org/10.5194/egusphere-egu24-12601, 2024.

EGU24-15814 | ECS | Posters on site | EOS4.3

Quantifying the human-induced climate change impact on heat-related mortality events in Europe with Extreme Event Attribution Methods  

Thessa M Beck, Lukas Gudmundsson, Dominik L Schumacher, Sonia I Seneviratne, Hicham Achebak, and Joan Ballester

Numerous Extreme Event Attribution (EEA) studies have consistently shown that human-induced climate change has increased the likelihood of extreme heat events. The increasing relevance of these studies in the context of climate litigation underscores the demand for the quantification of climate change impacts. Heat, as the primary contributor to weather-related mortality on the European continent, has caused more than 61,000 heat-related deaths in Europe during the 2022 summer. We carry out this proof-of-concept study in which we apply Extreme Event Attribution methods combined with epidemiological models to quantify how anthropogenic warming has influenced extreme heat-related mortality events in Europe. In contrast to most health impact studies, we utilize open-access mortality data from Eurostat, which is available in near-real time.

Because of the complex, non-linear relationship between temperature and mortality, we conduct separate Extreme Event Attribution analyses for (i) temperature extremes and (ii) associated heat-related mortality events in 232 distinct administrative regions spanning over 35 European countries. Our findings reveal that the probability of the maximum weekly values observed in 2022 has increased 12-fold [95th CI 3.51-147.15] for temperature and tripled [95th CI 1.02-18.63] for mortality compared to the pre-industrial baseline. Notably, we identify significant geographical disparities, e.g. in Spain the mortality risk is even 30 times higher [95th CI 3.33 – 1218.14] due to anthropogenic warming.

We find a statistically significant trend in 70% [90%] of the regions at the 0.95 [0.90] significance level, and across all age and sex groups, except for women aged 65 years or less, indicating that anthropogenic warming affects almost the entire European population.

This study establishes a foundation for subsequent analyses, not only for heat-related mortality events observed on different temporal and spatial scales but also for enabling an examination of other weather events and associated health impacts. By combining climate sciences and techniques with epidemiology and health data, it is possible to calculate the contribution of climate change to changes in health risks and mortality burdens by sociodemographic categories, such as sex, age, socioeconomic level, or comorbidities, especially in vulnerable groups. This transdisciplinary work has to potential to provide key information for climate-related health lawsuits and opens the door to inter- and transdisciplinary perspectives on how to integrate geoscience and epidemiology insights in litigation.

How to cite: Beck, T. M., Gudmundsson, L., Schumacher, D. L., Seneviratne, S. I., Achebak, H., and Ballester, J.: Quantifying the human-induced climate change impact on heat-related mortality events in Europe with Extreme Event Attribution Methods , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15814, https://doi.org/10.5194/egusphere-egu24-15814, 2024.

EGU24-16721 | ECS | Posters on site | EOS4.3

Does climate change violate children’s rights? Investigating the use of scientific evidence in child and youth-led climate litigation 

Rosa Pietroiusti, Sam Adelman, Annalisa Savaresi, and Wim Thiery

Climate change is already increasing the frequency, intensity and duration of many extreme weather events around the world, as well as driving impacts on communities through slow-onset changes, and will continue to do so with each additional degree of warming. Young and future generations will face an ever-greater number of such events during their lifetimes, raising concerns regarding the intergenerational inequity inherent in climate change. In response to these concerns, child and youth-led climate litigation is emerging as an avenue to push for more ambitious climate policies at national and regional scales, by applying legal duties and obligations in a forward-looking way and presenting courts with  scientific evidence of observed and projected climate risks and impacts. Recent complaints led by young people, including, for example, Sacchi et al. v. Argentina et al., lodged in 2019 with the United Nations Committee on the Rights of the Child and Duarte Agostinho et al. v. Portugal et al., which was heard in 2023 by the European Court of Human Rights, have broken new ground by bringing the rights of children and future generations to the fore. Based on a review of recent and ongoing cases, we will investigate (i) what harms are claimed by youth plaintiffs, and (ii) whether, how and to what extent scientific evidence is used to support their claims. By comparing the cases in relation to their claims, jurisdictional frameworks, reference to human and/or children’s rights, and status, we will shed light on how youth applicants have addressed the main challenges of this specific category of climate litigation, including meeting the victimhood requirement, and what role evidence from the geosciences and other scientific fields has played.

How to cite: Pietroiusti, R., Adelman, S., Savaresi, A., and Thiery, W.: Does climate change violate children’s rights? Investigating the use of scientific evidence in child and youth-led climate litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16721, https://doi.org/10.5194/egusphere-egu24-16721, 2024.

EGU24-17250 | ECS | Posters on site | EOS4.3

From Glaciers to Courtrooms: Translating Natural Science Concepts into Legal Frameworks for Climate Litigation 

Randy Muñoz, Christian Huggel, Wilfried Haeberli, Martin Mergili, Adam Emmer, Lukas Arenson, and Matthieu Sturzenegger

The integration of natural science concepts into climate change litigation, particularly in cases related to glacier lake outburst floods (GLOFs) in mountainous regions like the Andes, faces significant challenges due to the differing nature of scientific and legal frameworks.

Scientific understanding of climate change impacts on phenomena such as GLOFs relies heavily on scenarios, modeling, and projections that evolve over time with advancements in technology and knowledge. These models need to be comprehensive, and consider an array of factors including glacier retreat, temperature changes and various risk factors. However, legal standards often require definitive proof of causation. There may arise a discrepancy creating  a gap in case of prevailing uncertainties inherent to high-mountain processes which may not always meet the exacting evidentiary requirements of litigation.

An illustrative example of this challenge is the case of a citizen in Huaraz, in the Andes of Peru, using a major German energy producer over the risks of a catastrophic flood from a GLOF at Lake Palcacocha. The German court’s decision to admit this case is groundbreaking in climate litigation. It implies a recognition of legal responsibilities of large emitters for potential losses and damages caused by anthropogenic climate change globally, provided a causal relation between emissions and risk can be established. This case exemplifies the challenge in linking complex scientific causation with legal accountability.

In the Palcacocha case, the German court defined to distinguish between i) the hazard and risk posed to the plaintiff in Huaraz, and ii) the attribution to anthropogenic climate change and the emissions produced by the defendant. Here we report on the geoscientific studies undertaken to analyze the hazard situation posed by potential rock and ice avalanches, impacting the glacial lake and producing potentially devastating floods in the city of Huaraz. Critical among other are concepts and methods to quantify probability of occurrence of an event, and the effect of cascading slope and mass flow processes.

In conclusion, the challenges in adapting natural science concepts for climate change litigation, particularly regarding GLOFs, stem from different concepts, standards of proof, and conceptual understandings in science and law. Bridging this gap is essential for effective climate litigation and requires innovative interdisciplinary approaches that facilitate the translation of scientific findings into legally cogent arguments. The framework, methods and standards we applied in the case of Palcacocha could serve for other litigation cases in similar environments, highly impacted and vulnerable to anthropogenic climate change. 

How to cite: Muñoz, R., Huggel, C., Haeberli, W., Mergili, M., Emmer, A., Arenson, L., and Sturzenegger, M.: From Glaciers to Courtrooms: Translating Natural Science Concepts into Legal Frameworks for Climate Litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17250, https://doi.org/10.5194/egusphere-egu24-17250, 2024.

EGU24-18367 | ECS | Posters on site | EOS4.3

Contributions of carbon majors to historical heatwaves 

Yann Quilcaille, Lukas Gudmundsson, Thomas Gasser, and Sonia I. Seneviratne

While human-induced climate change shows no sign of slowing down, calls to steer to a more sustainable path grow louder. Countries are sued for their lack of ambitious climate action, and high-emitting companies for their responsibilities. However, climate litigation is often impeded by the lack of scientific evidence directly relevant to the legal cases. Available attribution research can provide support for claims, but some key elements are still missing. First, event attribution studies are limited to a few selected events, depending on available researchers’ time and interests. Second, the contributions of high-emitting companies to recent extreme events has not yet been quantified. Here, we fill in both of these gaps. We present the first collective attribution of 149 historical heatwaves reported over the 2000-2021 period. We apply a well-established extreme weather attribution (Philip et al., 2020) to heatwaves reported in the EM-DAT database (EM-DAT, 2023). For each listed heatwave, we identify the event in observational data (ERA5, BEST) and CMIP6 data, then we estimate its occurrence probabilities for present and pre-industrial climate conditions. Subsequently, we calculate the contributions in global mean surface temperature of 110 fossil fuels and cement companies using their CO2 and CH4 emissions (Heede, 2014) and the reduced-complexity Earth system model OSCAR (Gasser et al., 2017). These contributions combined to the collective attribution allow for the calculation of the contributions of these carbon majors to all of the analyzed historical heatwaves. These carbon majors represent 76% of the CO2 emissions over 1850-2021, and half of this 76% is due to only six actors (nation-state of China for coal & cement; nation-state of the Former Soviet Union for coal, oil and gas; Saudi Aramco; Chevron; ExxonMobil; Gazprom). In terms of global mean surface temperature, these six majors contribute to 0.30°C, while the others contribute to an additional 0.34°C. The majority of heatwaves are made substantially more probable and intense due to these six carbon majors. Though, other carbon majors cannot be neglected, as their sole contribution may be enough to make some heatwaves possible. This attribution of a large number of heatwaves and the link to the contributions of the carbon majors will provide useful resources for climate litigation, paving the way towards their legal responsibility.

 

EM-DAT, CRED / UCLouvain: www.emdat.be, last access: 09.01.2024.

Gasser, T., Ciais, P., Boucher, O., Quilcaille, Y., Tortora, M., Bopp, L., and Hauglustaine, D.: The compact Earth system model OSCAR v2.2: Description and first results, Geoscientific Model Development, 10, 271-319, 10.5194/gmd-10-271-2017, 2017.

Heede, R.: Tracing anthropogenic carbon dioxide and methane emissions to fossil fuel and cement producers, 1854–2010, Climatic Change, 122, 229-241, 10.1007/s10584-013-0986-y, 2014.

Philip, S., Kew, S., van Oldenborgh, G. J., Otto, F., Vautard, R., van der Wiel, K., King, A., Lott, F., Arrighi, J., Singh, R., and van Aalst, M.: A protocol for probabilistic extreme event attribution analyses, Adv. Stat. Clim. Meteorol. Oceanogr., 6, 177-203, 10.5194/ascmo-6-177-2020, 2020.

How to cite: Quilcaille, Y., Gudmundsson, L., Gasser, T., and Seneviratne, S. I.: Contributions of carbon majors to historical heatwaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18367, https://doi.org/10.5194/egusphere-egu24-18367, 2024.

EGU24-19683 | Posters on site | EOS4.3

Four roles for geoscientists in climate litigation 

Wim Thiery, Rosa Pietroiusti, Annalisa Savaresi, and Stefaan Smis

The number of climate change lawsuits is exploding,  and so is the need for scientific evidence on climate change in courtrooms. Here we identify four roles that climate researchers can take up in light of these recent developments: expert witness, party support, amicus curiae, and litigation-relevant research. For each role, we highlight recent examples and best practices, as well as pitfalls and their overcoming. These examples overall highlight the urgent need for interdisciplinary research between climate science and legal scholars to bring both research communities closer together. In addition, and in activities where exchange with litigators takes place, it is critical that ingestion of scientific information occurs right from the start of the litigation process.

How to cite: Thiery, W., Pietroiusti, R., Savaresi, A., and Smis, S.: Four roles for geoscientists in climate litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19683, https://doi.org/10.5194/egusphere-egu24-19683, 2024.

EGU24-20599 | Posters on site | EOS4.3

How stocks judge COPs: market impacts of climate conferences 

Robin Lamboll and Alaa Al Khourdajie

This study investigates the impact of Conference of the Parties (COP) meetings on the stock prices of oil companies and the broader implications for renewable energy sectors to examine the relationship between international climate negotiations and market responses in the energy sector. The analysis focuses on stock price movements and volatility within the oil and renewable energy industries. We look at the data of the 10 largest stocks in each category and investigate their behaviour during COP. The findings indicate that, with the exception of notable negative stock price movements during COPs 20 and 21 (before and during the signing of the Paris Agreement), COP meetings generally do not significantly influence the value of oil companies. There is also no impact on oil prices during COP itself, though some sign of disturbance in the period immediately afterwards. The study also addresses the renewable energy sector, finding no strong effects from most COP meetings but a notable decrease in stocks during COP6's failure. We conclude that the majority of COPs have not produced market signals indicating a green transition, although these signals are potentially detectable.

How to cite: Lamboll, R. and Al Khourdajie, A.: How stocks judge COPs: market impacts of climate conferences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20599, https://doi.org/10.5194/egusphere-egu24-20599, 2024.

The Climate Litigation Network supports national organisations that are taking litigation action against their governments in respect of the adequacy and implementation of national climate policies and targets. This presentation will provide an overview of the role in science in climate cases that challenge governments’ overall emissions reductions (“framework cases”) – of which there are more than 100 globally. Drawing from a litigator’s perspective, it will address common legal questions (i.e., harm, causation, foreseeability and remedies) that arise in such cases, and provide examples of how science has been used in case studies. 

Across framework cases, scientific evidence has been critical to success. For example, many cases, including those based on human rights or tort law, require claimants to show how they have been impacted or have suffered harm. In this regard, supporting studies range widely, depending on the facts of the case. These could include studies concerning extreme weather events, flooding, landslides, impacts on crop production and availability to water, and impacts on health or culture. To establish legal liability, claimants typically must show that the government’s actions can be causally linked to the harm, and that the harm was foreseeable. In this regard, attribution science and climate science generally can play a role in evidencing why government action (or lack of action) is contributing to climate change impacts. In terms of remedies, several cases have sought to push governments to adopt emissions reduction targets that reflect their “fair share” of the remaining global carbon budget. Numerous fair share methodologies have been developed by academics, many of which seek to reflect obligations and principles set out in the United Nations Framework Convention on Climate Change and international environmental law. In some cases, there may also be questions concerning loss and damage, which could require detailed analyses of how much damage has been incurred, or could be incurred in future, due to the impacts of climate change.

Drawing on case studies from specific cases, this presentation will highlight the current deployment of science in climate cases against governments and explore new frontiers.

How to cite: Williamson, A.: Challenging governments’ response to the climate crisis: the role of science in climate litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21949, https://doi.org/10.5194/egusphere-egu24-21949, 2024.

Natural disasters, a consequence of climate change in recent years, are becoming more frequent. We are witnessing more and more earthquakes, floods, and long periods of drought, affecting everyone on the planet. In this context, teaching specific content on climate change to schoolchildren is essential for building specific skills towards protecting nature. In recent years, Erasmus+ projects have become an opportunity for exchanges of experience between educational institutions to support children and young people in developing into responsible adults. Starting in 2021, as a result of the Erasmus+ accreditation obtained, the "Otilia Cazimir" Secondary School is an institution that supports students in the formation of specific skills to prevent natural disasters, a consequence of climate change. Thus, the three projects implemented so far, "Supporting Teachers for Implementing Leadership", "Hands on Our Future" and the one currently underway, pursue the objectives of sustainable development, thus supporting the formation of sustainable communities. The Romanian students, together with students from Germany, Portugal, and Lithuania, and their teachers, carried out activities to understand the effects of irresponsible environmental behavior and the consequences of these actions on climate change. Collaborative videos, inter-school visits, training courses for students and teachers, discussions with experts, and non-formal education clubs are some examples of relevant activities to train primary and secondary school students to develop the necessary skills for a sustainable future. Inclusion of all participants was ensured in the learning experiences, thus meeting diversity and responding to individual needs. In addition, the eTwinning project "Artificial Environment Resistant to Natural Disasters" implemented in the school year 2022-2023 started as a result of the earthquake in Turkey. Romanian students, together with Turkish and Georgian ones, learned more about natural disasters, how they occur, their causes, and how they can be prevented. They created experiments, drawings, videos, posters, and logos to understand how earthquakes, floods, vegetation fires, and droughts occur and proposed specific solutions to prevent them in the future. The results of the projects implemented in our school have been disseminated over time through social media, workshops, posters, and billboards, becoming sources of inspiration for other institutions to teach young generations. Therefore, Erasmus+ and eTwinning projects represent added value in the educational process, being an important contribution to the formation of generations responsible for the environment and climate change.

 

How to cite: Opria, S.: Erasmus+ and eTwinning projects in developing school students' specific skills related to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2186, https://doi.org/10.5194/egusphere-egu24-2186, 2024.

EGU24-2253 | Posters on site | EOS5.2

 Aware of Climate Change 

Ruzhica Jagurinoska

 

Aware of Climate Change

Lifting аwareness for climate change and understanding of environmental issues among students in classroom is essential. GLOBE Pedosphere protocols were integrated into my classroom by teaching methodologies as an innovative approach to enhance climate change education. The Pedosphere, which encompasses the soil as a crucial component of the Earth's system, offers a unique perspective to comprehend climate change.

My strategy is to take students out of the classroom and let them be in charge in collecting data by respecting the protocols and practical activities.

Practical activities such as soil sampling, analysis, and understanding soil structure, temperature, texture, humidity or soil color as health indicators can elucidate the relationship between soil dynamics and climate change processes. GLOBE visualization system helps the students to explore the relation between elevation and temperature and begin learning how to make important patterns evident in visualizations, or to compare and detect data distinction on the GLOBE net all over the world.

Leveraging and comparing data with real-world data by GLOBE Visualisation System make students achieve deeper understanding of environmental processes. New knowledge encourages critical thinking and problem-solving skills among students.

By fostering a deeper connection with the Pedosphere, students become informed and proactive contributors to sustainable solutions addressing climate change on a local and global scale.

How to cite: Jagurinoska, R.:  Aware of Climate Change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2253, https://doi.org/10.5194/egusphere-egu24-2253, 2024.

EGU24-2803 | Posters on site | EOS5.2

My plan - responsibility and action for a green future! 

Marcu Hajnal and Branzei Daniela

        Education can encourage people to change their attitudes and behavior; it also helps them to make informed decisions. In the classroom, young people can be taught the impact of global warming and learn how to adapt to climate change. Education empowers all people, but especially motivates the young to take action. Not having a subject related to the ecology of the environment, we teachers are obliged to carry out actions to protect the environment in which we live and carry out our activities. For many years our school co-opted students in the international project PORTI VERZI-GREEN GATES, but We  have expanded this topic by getting involved in an eTwinning project My Plan@. During the My plan@ project, students from the 9 participating countries interacted and carried out activities through online meetings using the Zoom platform, through digital materials created with the help of teachers using different applications and tools web 2.0. such as Bookcreator, Canva, Postermywall, Genially, StoryJumper.The purpose of this project was to accumulate new knowledge about science and nature, combining art, to increase students' interest in educational activities in which they can use their knowledge of the English language. Among the objectives of the project are the following: receiving a scientific and age-appropriate education based on evidence, informing the target group: students and teachers about climate change, accustoming the child to correct recycling behaviors and the use of materials for making of useful objects in school activities, and the use of the English language in various contexts, the integration of technology in the teaching-learning process. In order to achieve the educational objectives of the project, we used means and teaching methods adapted to the age characteristics of the students.The project was conceived primarily through a transdisciplinary approach: science and art. The integrated approach of all activities (science, literature, art, music, English, IT) allowed our students to develop creativity, communication, research and decision making.The activities carried out were in accordance with the proposed general objective, and the results of the project exceeded our expectations. General purpose: the project connects art and science to encourage more open-minded and creative students. Students are artists, scientists and entertainers at the same time. At the beginning of the project, the logos were created by each of us partners, and then the winner was chosen by the vote. The logo created by Veronica Florea, our student, won the attention of the partners. Collaborative activities were carried out by making a journal THE FUTURE HISTORY, which captures pictures from nature and stories about the nature of the future without destruction and in harmony with man. We celebrated together WATER DAY - March 22 and EARTH DAY - April 22 with planting, recycling and games (puzzle) activities. Project dissemination was achieved through the organization and celebration of EUROPE DAY, eTWINNING DAY on May 9.We believe that the objective was achieved within the activities, the final products of the activities can be found both on Twinspace and on the school website. 

How to cite: Hajnal, M. and Daniela, B.: My plan - responsibility and action for a green future!, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2803, https://doi.org/10.5194/egusphere-egu24-2803, 2024.

EGU24-2935 | Posters on site | EOS5.2

Eco-STEAM Challenge Green Hotel 

Danilo Borovnica and Miroslav Grujic

It is important to study climate change from the earliest school days. It is also a great opportunity for a STEM approach to learning and learning science through hands-on experiences. In this article, we will present some of our experiences in working with students.

With our students we participated in the Eco-STEAM Challenge together with 11 other schools from Serbia, Croatia and Bosnia and Herzegovina.

This competition, within the Scientik network, aimed to raise awareness about climate change and possible mitigation measures.

In the course of a month, students regularly measured the temperature and humidity of the air around our school in four selected places. Using the Arduino set, we made a temperature and air humidity device. We later processed the obtained data and made a proposal for improving the school environment in order to mitigate at least a little the effect of climate change in our micro environment.

Our school is located in the center and is surrounded on three sides by busy streets.

During April, the students also conducted an experiment testing the air quality in different parts of the school yard. They came to the conclusion that the air is most polluted in the part of the park that is next to the main street and the large parking lot.

Knowing that the air is not heated directly by the sun's rays, but rather by the foundation, which later emits the energy it has absorbed, we realize that it is important what materials we are surrounded by. Asphalt, concrete, brick are among those that heat the air the most. Guided by that knowledge, we came up with the idea of how to adjust our space (school yard) and thereby reduce heating, but also enable other species to come and live in our environment.

By measuring during the project, we came to the conclusion that in some days, in addition to high temperatures, we also had extremely low humidity. Plants have the effect of increasing air humidity, so our proposal for adjusting the yard will also take this into account.

We would make a natural environment (hotel) for insects out of metal construction and wood. In this way, we will encourage the presence of insects for which our climate is a natural habitat and strengthen urban biodiversity.

That's how the whole project got the name "Hotel in our school for insects is cool".

We had the opportunity to share our experience with colleagues from Serbia, Turkey and Portugal within the project Learn and Experience Science Together Online (lestoproject.com) where we created learning scenarios. One of the scenarios was created precisely on the topic of global warming.

How to cite: Borovnica, D. and Grujic, M.: Eco-STEAM Challenge Green Hotel, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2935, https://doi.org/10.5194/egusphere-egu24-2935, 2024.

The water cycle plays an important part in climate change. This activity games the construction of the water cycle by students taking the role of a water molecule as it moves between reservoirs. The processes involved will be described and explained, however, students will have to work collaboratively in order to complete the water cycle in its entirety.

The factors that power the movement (gravity and state changes) will be determined and linked to changes in the amount of water found in each reservoir. Although gravity can’t be changed, the heat budget can, and this will affect the change in state of water, leading to unbalancing the water cycle.

Thought experiments and discussion on possible effects of climate change, especially through global warming, will allow students to understand its effects on the water cycle and the subsequent effects on the climate, in particular:

  • Positive feedback of decreasing albedo and increased water vapour in the atmosphere.
  • Increase in liquid water resulting in sea level rise and flood risk.

After using the Water Cycle Game, students will have a better understanding of the complexities in the water cycle, its effect on the climate, and have an appreciation of how climate change can have a local and global effect in a highly likely future.

How to cite: Blue, K.: Gaming the Water Cycle: a student-led activity to explore climate change., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2936, https://doi.org/10.5194/egusphere-egu24-2936, 2024.

EGU24-3094 | Posters on site | EOS5.2

Green School Project 

Lara García

The fight against climate change is often associated with large-scale actions in urban areas. However, the school serves as an engine for change, where all staff, both teaching and non-teaching, can alter their attitudes, values, and behaviors regarding environmental education.
With this project, we aim to raise awareness and promote good environmental practices within our school. The objectives of our project include:

1. Promoting awareness among students about their role in the fight against climate change by emphasizing the value of plants as CO2 reducers.
2. Involving the families of students in the design and implementation of proposals.
3. Encouraging public discourse on utilizing private and public spaces as CO2 sinks.
 4. Integrating the fight against climate change into all areas of secondary education.

This project comprises some activities, ranging from awareness talks to planting vegetables in the green areas of the school and establishing a compost bin.

The main activity of this project involves experimentation.  In this activity, students measure CO2 and temperature values under different conditions, such as the presence or absence of plants. 

Analyzing the results allows them to become aware of the importance of plants as CO2 sinks, and thus, as tolls in the fight against climate change. 

How to cite: García, L.: Green School Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3094, https://doi.org/10.5194/egusphere-egu24-3094, 2024.

EGU24-3179 | Posters on site | EOS5.2

Fisrt edition of an “Ocean Readings Prize, a better knowledge for a better preservation”. 

Helene Spilmont, Sophie Van Ommeslaeghe, Nathalie Jarnier, Katy Masset, and Aline Klawinski

Like the Goncourt for high school students, the aim is to have a book prize awarded by pupils on the theme of the environment and more particularly the Ocean.
The objectives of this project are:
- Get pupils to read / awaken the pleasure of reading in pupils
- Provide knowledge on ocean ecosystems, in partnership with Nausicaa, the largest aquarium in Europe located in Boulogne Sur Mer.
- Create a link between collège and lycée (key stage 4 and 5 pupils)
- Develop oral skills by arguing choices (when choosing the winner of the prize) and presenting their final work in Nausicaa.

The books (one manga, one novel, one graphic novel, one graphic documentary and one comic) were selected last June by the instigators of the project.

 

Set up :

A call for proposals was launched in June 2023 to secondary schools (collèges and lycées, key stage 4 and 5 pupils) in Boulogne sur Mer and the surrounding area. Thirteen colleagues from five different schools responded favorably (in total the project gathers 190 pupils).

Pupils from these schools work on these readings all along the school year. Various activities are carried out with their librarian teachers, science and French teachers.

Examples of activities carried out at the Branly high school are: cards game to discover the books, reading sheets, “speed reading”, and the production of a “bestiary” around the animals found in the books as final task.

At the same time, all these classes regularly visit Nausicaa during the school year, which is an occasion to supplement the knowledge provided by the readings, and to enrich the final works.

A collège-lycée meeting is planned for next April. On this occasion, pupils will present their final work and discuss about the readings to elect the winner of the prize.

The high point of the project will be on World Oceans Day (7th of june) in Nausicaa.

The winning author of the prize will be invited, as well as all the students who participated in the project. This day will be an opportunity to highlight work carried out during the year and to meet the prize-winning author. 

How to cite: Spilmont, H., Van Ommeslaeghe, S., Jarnier, N., Masset, K., and Klawinski, A.: Fisrt edition of an “Ocean Readings Prize, a better knowledge for a better preservation”., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3179, https://doi.org/10.5194/egusphere-egu24-3179, 2024.

As a biology and geology teacher, I have followed virtually, with some of my students, the HIPER campaign off the coast of Ecuador in 2022-2023, and from the 28th of january 2024 to the 23rd of february 2024, I have the honnor to take part in the SUPER MOUV campaign on the french oceanographic ship Pourquoi pas ? in Ecuador.

The scientists left me an additional place on one of the most innovative ship in the Ifremer fleet, in order to spread geology tools use on board in destination to teachers and their students in college and highschool, not only in France but also all over the world in the french schools abroad or the french classes abroad : http://edumed.unice.fr/data-center/oceano/supermouv.php

During this campaign, the aim is to prepare some challenges connected to SUPER MOUV activities for schools :

- students can indeed discover geodynamic in Ecuador west coast which is located in the ring of fire, and shaken by several earthquakes due to the subduction of Nazca tectonic plate under south-america tectonic plate,

- they can also discover how rocks or fluids are collected by Nautile submarine, how sediments are collected by coring, how highligths geo-mechanical properties of rocks or methods for fluids analysis,…

- and furthermore, they can learn about life on board a deep sea vessel (way of life, different jobs,..) during videoconferencings between the ship and the pupils in their classrooms ! 

How to cite: Gendron, F.: Teacher on board the deep sea vessel Pourquoi pas ?  for SUPER MOUV campaign off the coast of Ecuador , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3220, https://doi.org/10.5194/egusphere-egu24-3220, 2024.

EGU24-3241 | Posters on site | EOS5.2

Hands-On Climate: Engaging the Public with 3D Geo-Data 

Annamaria Lisotti

Despite the abundance of data on climate change, there remains a significant gap in public awareness and action. Recent trends in data communication have introduced the concept of data physicalization, which transcends traditional written and visual methods by engaging multiple senses, including touch and hearing. This innovative approach has shown potential in reaching diverse audiences and enhancing public engagement.

Our project, "Tangible Statistics" at IIS Cavazzi (Liceo scientifico), involved students aged 16-18 and demonstrated the successful impact of data physicalization. A key method employed was the translation of geolocalized data into 3D models using QGis, followed by 3D printing. This technique was showcased at Science on Stage Italia in Naples (September 22-24, 2023) and has proved applicable also to younger students as it was immediately replicated in a junior secondary school.

The project utilizes freely available tools such as QGis, Blender, FreeCad, and Cura for slicing. Training students in these tools, specifically for model creation and printing, is efficient (approximately 4 hours of lab work plus home application). This investment enriches curriculum across diverse subjects, facilitating the study and dissemination of data related to geography, environment, and more together with fostering data literacy of future responsible citizens.

Environmental monitoring data, such as extreme temperatures, precipitation, and fire risk indices, are particularly suitable for this technique. Beyond presenting raw data, the focus is on narration– a critical factor in making data resonate with the public. The creation of physical artifacts for storytelling enhances public exhibitions, outreach, and awareness campaigns. These artifacts foster emotional engagement in an otherwise distracted or statistically unskilled population. The tactile experience of touching these models enables deeper understanding and accessibility of complex data.

Moreover, these models, either scanned from the artifact with a cell phone free app or directly produced in digital format, can be integrated with data journalism pieces through QR codes. This integration allows readers to engage with augmented reality models while reading, providing a hands-on experience of data manipulation.

The potential of data to bring people together to address societal issues is huge. By understanding and improving our communities through data, we can spark civic dialogue, hold institutions accountable, and foster effective communication. Our project is a contribution in demonstrating that through creative data physicalization, we can transform the abstract into the tangible, making climate data more accessible and impactful for the general public starting from Education.

How to cite: Lisotti, A.: Hands-On Climate: Engaging the Public with 3D Geo-Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3241, https://doi.org/10.5194/egusphere-egu24-3241, 2024.

EGU24-3256 | Posters on site | EOS5.2

Using digital technology to teach climate science 

Lydia Ait Ouferoukh

Understanding contemporary climate change requires studying the climate system, how it works and evolves.

Various tools, such as palynological studies, oxygen isotope ratios, numerical modelling, etc. can be used to trace the evolution of the climate. Much of this data is accessible through the publication of databases and numerical modelling. In addition, the increasingly powerful numerical tools are mainly available to classrooms: use of spreadsheets, graphs, free softwares such as SimClimat, etc.

Leveraging these tools in my lessons and the training of my students seemed natural to me in a world where digital technology and information are available to all.

The poster I am presenting showcases some numerical activities carried out with students from the Groupe scolaire Sainte Louise, in Paris, aimed at helping them grasp those fundamental concepts of climate system.

The integration of digital technology not only enhances the dynamism of learning but also motivates students to actively participate, opening up exciting educational possibilities.

How to cite: Ait Ouferoukh, L.: Using digital technology to teach climate science, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3256, https://doi.org/10.5194/egusphere-egu24-3256, 2024.

EGU24-3347 | Posters on site | EOS5.2

ECOding: Putting climate solutions at the heart of tech education 

Selcuk Yusuf Arslan

Coding education is gaining more and more importance today. Coding improves general thinking skills by giving individuals the ability to solve problems. It also encourages creativity and innovation, giving students the opportunity to develop their own projects and create new solutions. One area where coding can be used is the climate crisis problem that threatens our planet. ECOding aims to integrate environmental and climate change education with an interdisciplinary approach while providing coding education to students. Within the scope of the project carried out in a vocational high school in Türkiye, while teaching coding to students in Object Oriented Programming, Internet of Things (IoT), Robotics, Artificial Intelligence and Machine Learning courses, the focus was on the environmental problems that our world faces. Coding examples shared with students, homework assignments, and project studies focused on the climate crisis. This situation not only raised students' awareness but also supported them to create technology-supported solutions to the climate crisis. Students measured their carbon footprints with the software they prepared and gave suggestions on how to reduce their carbon footprints according to their answers. A project that enables students to open the right waste bin in seconds for easier recycling of a waste shown on a camera with object recognition gave students the opportunity to participate in an international project competition. The students, who designed an educational software introducing hydrogen fuel cells using gamification, succeeded in winning the first prize in an international project competition. Within the scope of the project, which has been carried out for about 3 years, more than 200 students have received coding training with this approach. At the end of the academic year, the opinions of the students were taken and all of the students stated that seeking solutions to the climate crisis through coding made them happy, fun and instructive. More than half of the students stated that they developed a project idea for the climate crisis at the end of the course. The successes in the implementation process made the project visible in the international arena in a short time. In 2021, the project coordinator was awarded the Green Skills Award organised by the European Training Foundation (ETF) and UNESCO. Finally, the project coordinator was selected by JCI as one of the Ten Successful Young People of the World in the category of Environmental Protection and Moral Leadership. The project, which is frequently shared both in Türkiye and Europe, has started to be implemented in many schools.

How to cite: Arslan, S. Y.: ECOding: Putting climate solutions at the heart of tech education, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3347, https://doi.org/10.5194/egusphere-egu24-3347, 2024.

EGU24-3374 | Posters on site | EOS5.2

Hot spot in the schoolyard 

Isabelle Veltz and Virginie Bour

Defined by Howard in 1818, an “Urban Heat Island” corresponds to an urbanized area where the temperature is higher than in natural or surrounding environments. With climate change, this phenomenon affects more than 80% of urban populations and is linked to the storage of heat in the asphalt during the day and the stagnation of air between homes. Water runs off the surface of the waterproofed soil and the vegetation must be watered constantly.

With the regular increase in temperatures, the Roosevelt high school in the city center of Reims (Champagne, France) becomes a furnace from spring to autumn. In fact, with its tarmac square schoolyard surrounded by high dark red brick buildings, we measure recurring morning temperatures above 30°C and afternoon peaks above 40°C in classrooms.

This work, carried out by students, aims to define adaptation strategies and propose feasible modifications in this enclosure, which is classified as a “historic monument” and which must therefore maintain its total integrity. Roosevelt high school contains the “War Room” which is the surrender room where the end of the Second World War was signed on May 7, 1945 and it’s impossible to change its appearance.

After identifying the causes favouring the “Heat Island” effect in their highschool, the student carried out measurements of albedo, runoff and impact of the scare vegetated areas were carried out. Analog and computer-assisted experiments have been developed to propose solutions to limit heat accumulation and soil drying and promotes humidification and CO2 trapping in the ground.

This work conducted by the students allowed them to propose non-invasive solutions improving the quality of life in their work environment.

Through its local and experimental approach, this work has made concrete highly mediatized notions whose causes and consequences are not always well associated. Moreover, the major role of soil and soil preservation, in modulating climate change, has been clearly highlighted.

How to cite: Veltz, I. and Bour, V.: Hot spot in the schoolyard, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3374, https://doi.org/10.5194/egusphere-egu24-3374, 2024.

EGU24-3396 | Posters on site | EOS5.2

Struggling with climate changes 

Karolina Damjanoska

STRUGGLING WITH CLIMATE CHANGES
 
Karolina Damjanoska
Master of Science in Physics Education and Physics Teacher in High School “Orde Chopela”,
Prilep, North Macedonia.
 
e-mail: kdamjanoska08@gmail.com
My students from SOU "Orde Chopela" have participated in many projects as citizen scientists,
such as the Globe at night project, which has been going on for sixteen years. The project is
enables students to do light pollution measurements by observing diverse constellations in the
night sky. That way, they get educated about the importance of maintaining a healthy
environment as well as the human impact on a changing climate. Over the years, I have gotten a
significant experience in the field and my students have achieved excellent results in domestic
and international competitions, which has motivated me to continue passing on my knowledge to
colleagues in my country and abroad.
For many years, I have been a leader and SOU "Orde Chopela" school coordinator for the
GLOBE project. Additionally, I am an official trainer for the GLOBE project and its Atmosphere
protocol. Measurements made during this protocol closely relate to those in the GLOBE project,
due to the importance of the visibility of the night sky. Besides that, while implementing the
project, the students have had the chance to delve into taking care and contributing to a healthy
environment.
Active participation in projects like these, give the students a chance to be properly formed as
individuals who advocate for a healthy environment and are able to think and act appropriately.
Their awareness of preserving the environment is at a very high level, they work on authentic
problems for which they seek and find solutions. Ultimately, the goal is contributing to the
common good.

How to cite: Damjanoska, K.: Struggling with climate changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3396, https://doi.org/10.5194/egusphere-egu24-3396, 2024.

EGU24-3803 | Posters on site | EOS5.2

Climate change and Cosmography  

Athanasios Vagenas

CLIMATE CHANGE AND COSMOGRAPHY

Introduction

A beautiful universe, with the small earth at its center mediating knowledge and carrying it everywhere. From schools, universities and science museums. In our museum this year, the theme of our museum is extantas and cosmography in general. In addition, climate change has unexpectedly arisen, following the heavy rainfall that characterizes our planet and especially our region (Mouzaki-Karditsas 2019).

https://kpem.gr/kyrio/mm/mm.html

Many times there are events that outweigh our personal promote and require collective efforts to get better results. Our school is directly connected to our society, because our students live in it almost all day long. Their concerns are our concerns. Thus, in the events that occurred in the Municipality of Karditsa and the Municipality of Mouzaki concerning the floods, as a school with published educational activities we will give the historical and social dimension of the problem. Our pedagogical approach is intended as another message to be a reminder of the mechanisms that can help our region. Students exhibit their photographic material.

Climate change. Recent Historical Document

It is very important, especially after the continuous disasters in recent years in Greece, neighboring countries and around the world caused by floods. It is also important in planning related to the environmental management of water resources and as applications of ecological engineering, which is necessary for our region and our country in general.

The effects of global warming are not evenly distributed over all latitudes and longitudes. Climatic phenomena such as droughts, floods are expected to occur more frequently. The picture I encounter on the way to my school where, farms still have water, plants muddy is nightmarish. The Headmaster of the school on the morning calling after a week of suspension only asked who has no books due to water ingress at home. There are rumors of students who have lost their homes. After the second week was over we began to discuss the damage everyone has suffered, and it is normal to have lost part of your home, furniture and clothing.

Social dimension of the European project OSOS (Open Schools for open Societies)

Everything that is happening today should end quickly. The school to find its normal rhythm. The idea of OSOS has entered our lives as a basic tool and not as an accumulated knowledge or as an interactive tool for solving exercises in various forums. That is how we will try to continue our coursework. To approach the physical teaching of the classroom with complementary activities outside of it. So we too offer interactively as a classroom group, as a school and as a science museum to our local community, to worry to hope for something better.

Five years later 2023 in the region of Trikala, Farkadona and Karditsa(Palamas) exactly the same flooding events occur. The photographic material describes IANOS and DANIEL.

The OSOS logo contained in four words captures a new vision for schools : Feel - Imagine - Create - Share.  

Thank you

How to cite: Vagenas, A.: Climate change and Cosmography , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3803, https://doi.org/10.5194/egusphere-egu24-3803, 2024.

The « Climate Fresk » is a french innovative educational tool designed to raise awareness about the challenges of climate change. Developed by the French organization CliMates in 2018, it engages students in an interactive and collaborative learning experience.

This activity lasts around 3 hours and takes the form of a board game where students organized into groups of 4 to 7, working together to understand the complex dynamics of climate change. The game incorporates a set of 44 cards representing various factors related to climate change (e.g. greenhouse gas emissions, sea level rise, deforestation, ocean acidification, aerosol). The course is organized as follows:

  • Step 1: The students’ goal is to place cards on the board, creating connections between different aspects of climate change. Behind the cards lay explanations about the item to help them solving some complex issues (e. is ice melting and sea level rise connected?).
  • Step 2: The students will be given some sheet and materials to stick the cards on it, draw the links and add additional decorations of their choice.
  • Step 3: The different Fresks are displayed on the classroom walls, and the group can present them, explaining their layout choices or items that particularly moved them.
  • Step 4: A discussion about the solutions is engaged

The primary objective of the Climate Fresk is to enhance participants' understanding of the causes and consequences of climate change while fostering discussions about possible solutions. By actively involving individuals in the learning process, this activity aims at empowering them with knowledge and inspire collective action.

Teachers often find the Climate Fresk to be a valuable resource for education in high school settings. Additionaly to scientific knowledge, this approach encourages critical thinking, collaborative problem-solving but also creativity since the students will take some time to do a nice and efficent layout. The visual and interactive nature of the Climate Fresk makes it an effective tool for conveying complex scientific concepts in a simple and accessible educational tool. Moreover, it promotes active learning and brings a different learning experience based on creation of an mural fresco.

Other similar works have been created since, such as the Plastic Fresk, the Soil Fresk, the Digital Fresk.

How to cite: Widmann, M.: Exploring the Complexity of Climate Change with an Interactive and Collaborative Learning Tool: The "Climate Fresk", EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3871, https://doi.org/10.5194/egusphere-egu24-3871, 2024.

EGU24-3943 | Posters on site | EOS5.2

Miedwie Lake as a source of life. Implementing SDGs in STEM lessons. 

Ryszard Markowicz

The Project is based on the Miedwie Lake, which is 5th largest lake in Poland and it was conducted by 6 13yo students. The project had a lasting impact on the community, ensuring sustainable water use practices, and reducing the impact of climate change on the environment. The  objective of this project was to create awareness among the community about the importance of water resources from the Miedwie Lake. This project aims to educate the community about the negative impacts of climate change on water resources and how sustainable water use practices can mitigate these effects. Also, to show young people that they have a huge impact on their communities and they actually can change the world.

The project was focused on different stages.

  • Meeting with the Head of Kobylanka Municipality Mrs. Julita Pilecka. The mayor shared with us the problems as well as the development plans of the Kobylanka municipality, as well as gave us a glimpse of the threads concerning the city of Stargard.
  • TRIP TO THE WATER PRODUCTION PLANT IN ŻELEWO. The trip was held for educational purposes, to learn more about how water is purified and what needs to be done so that the water from Lake Miedwie can be brought to the inhabitants of Szczecin. 
  • Presentations and workshops for junior classes 1-3. Junior students were able to actively participate in the presentation.
  • Professor of hydrology Hubert H.G. Savenije from Delft University visited our school. Our meeting with the professor of hydrology was aimed at introducing and explaining why water is the blood of the Earth. 
  • Meeting with  Mr. Zenon Wiśniowski.  DIRECTOR OF THE POLISH GEOLOGICAL INSTITUTE – NATIONAL RESEARCH INSTITUTE 
  • Next was making a podcast. One of the project’s participants, conducted an interview with her grandfather, who’s the chief of Stargard District Fishing Guard. The interview was recorded and was played on the official conference.
  • FIRST STUDENTS CONFERENCE FOR ADULTS Observing and monitoring the key variables governing the global water cycle is essential to our understanding of the Earth’s climate, forecasting weather, predicting floods and droughts, and improving water management.  It was a summary of all work done in the project. Every student could show adults how much he has done and how much efort gave to make the project succesful.

Using SDGS:

  • Our activities helped us see that the health of residents cannot be threatened by poor water quality.
  • Educated themselves at all times during all activities in areas such as science, technology, math, engineering, hydrology, geology.
  • Our entire project involves researching, learning and exploring.. All our activities were about convincing ourselves of the safety of the population and making sure the water around us is clean.
  • In the laboratory we researched and learned about a whole list of vegetation and animals that live thanks to water.
  • The study of water and conversation with a geohydrologist showed us what life on land looks like and how the chain of life functions.

We did not sleep, we lost our tempers, but it was worth it. And this is what STEM education should like.

How to cite: Markowicz, R.: Miedwie Lake as a source of life. Implementing SDGs in STEM lessons., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3943, https://doi.org/10.5194/egusphere-egu24-3943, 2024.

Our planet's changing climate is a diverse topic that allows students to brainstorm, discuss, and think about the best ways to protect our planet Earth. This project will be created by students in the seventh grade, age 12-13.Solar energy is the main source of life found on Earth. My  students and I will work together to develop a project based on solar energy, the types of energy that arise from it, and finally how we can use this energy while preserving the environment from pollution and preserving the natural ecosystem.Open discussion: Solar energy and how we can use it in our lives without harming our planet.Students will explain why food energy comes from the Sun.We will deal with the process of photosynthesis. Thanks to this process, plants receive energy from the Sun in orderto grow. The students will accompany this information with a graph where they show that the Sun is a source of energy for the plants and animals that we eat.We will talk about the importance of vegetation in our lives. For a planet to be as green and forested as possible as well as a rich atmosphere full of oxygen.We will use and discuss the Sun as a fuel energy source. Students will learn how biofuels and fossil fuels are created.A discussion on the benefits and negative consequences that have come as a result of their use by mankind.We will prepare sensitizing inform posters which we will stick around the city to make people aware of environmental protection and that changes will start with us. We will discuss the greenhouse effect, how we can help reduce the greenhouse effect, and how to regulate the climate on Earth.Wind and water energy and their importance in human life.Students will explain how wind and rain are formed thanks to solar energy. Students will answer the question: How can we use these energies for the benefit of humanity without harming the environment? They will give different ideas. These ideas will be illustrated with examples from everyday life. They will describe several methods of producing electricity from wind and water energy.Students will also collect information on the use of solar energy directly. Discussion on solar panels and the benefits of their use. Assess the importance of using solar panels by evaluating the preservation of the environment from pollution as well as the preservation of the natural ecosystem.We will visit a complex where solar panels are installed. Students will observe the construction of a solar panel. They will discuss with each other their construction, parts, and energy conversions in the solar panel. The tools for building the solar panel model will be prepared. Open discussion: How a solar panel is built. Students will bring the materials for the construction of the solar panel and will receive information about the types of panels, their use and purpose, and their advantages. They will build their own solar panel.

How to cite: Kaçi, L.: Solar energy, the types of energy that arise from it, and how we can use this energy while preserving the environment from pollution and preserving the natural ecosystem., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4043, https://doi.org/10.5194/egusphere-egu24-4043, 2024.

Energy and climate changes are complex issues with rapidly developing science and the potential for controversy. The amount of time teachers are spending on these topics is going up significantly, but how can educators effectively bring these important subjects into their classrooms? My response applied to 11-14 year-old students is to start from plots nearly without any discussion before. Simple plots that show the most important indicators of climate change (i.e., time-behaviour of concentration of CO2, surface temperature, sea level, arctic sea ice extent, etc.).

Time plots do not end in the present time but are extrapolated to the next 20-30-40 years using models from qualified scientific literature, that show how the choices of decision-makers and also our behaviour can affect the climate changes. This becomes a powerful starting point for a discussion that will arise from students as soon as they realize on how the situation is rapidly changing. The discussion will naturally end-up with students that focus that a combination of strategies is needed to reduce greenhouse gas emissions. The most immediate strategy is conservation of oil, gas, and coal, which we rely on as fuels for most of our transportation, heating, cooling, etc. In students life that means to modify some habits in order to save energy and limit gas emissions. Student achieve this conclusion by their selves, while the teacher has only the role to coordinate the work.

Some strategies to keep this subject interesting and stimulating are used: plots are done by students not in their notebooks during desk-work but in high dimensions in the school-gym, using when possible the lines of basket of volleyball pitches and completing them with paper tape. This involves the students usually less interested in the activities in traditional classroom work and allows team work in groups of 3-4 students. This also reinforces math abilities and demonstrates how math theory merges with reality, a link that is not always caught by young students.

How to cite: Martelli, M.: From plots to theory: young students build their good practice on climate changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4148, https://doi.org/10.5194/egusphere-egu24-4148, 2024.

EGU24-4396 | Posters on site | EOS5.2

The Role of Interdisciplinary PBL Activities: Climate of the Past 

Nuno Correia, Vanessa Neves, and Alexandre Gandra

Nowadays, in Portugal, the challenge of Natural Sciences (NS) for middle and high school teachers is to make science education more attractive to young students. One way to achieve that is through practical work. Unfortunately, this kind of work is not very common in geology teaching. 

The Curricular Autonomy and Flexibility Project (DACP) with Biology/Geology, Mathematics and Physical/Chemistry was intended to increase the quality of teaching and learning, based on the Students Profile at Completion of Compulsory Education reference document and the guiding documents for Essential Learnings, which will provide help in the planning and assessment of teaching and learning.

This work is an example carried out through the interaction of different learning environments, inside the classroom, and outdoors, and of different types of practical work, namely laboratory and fieldwork.  The organisation of the activities followed a pattern: the field trip to the Valongo Anticline (North of Portugal) and Problem-Based Learning (PBL).

The Valongo Anticline allows  the observation of evolution of life during the Paleozoic, based on animal and plant fossils, as well as the possibility of dating the strata from the fossils they contain. It also presents some particular lithology evidence, namely the presence of icebergs, the existence of submarine volcanism, and the presence of beaches. The tectonic action is evidenced by the existence of folds and faults.

The Problem Question (PQ) was based on an outcrop from the Paleozoic where we have the geo-trails that cover rocks of different ages of the region of Valongo. In this site it is possible to observe the variation in sedimentation environments (marine and continental) from nearly 540 to 300 M.y. Also, in this region we can find several outcrops with diamictites beds.  This   glaciomarine record of the Hirnantian (end-Ordovician) glaciation is evidence of the climate changes that occurred over Earth's history.  

In this poster we discuss some ideas about what students learn from different activities and which other factors influence their learning process as students. The idea of interdisciplinary learning is to allow students to realize that certain fundamental concepts don’t belong to a single science subject. On the contrary, these concepts can be applied in many subjects.

In conclusion, this poster presents some formal and non-formal educational practical activities that the students developed, in groups, during the year 2023 and 2024 and that can be used in the teaching of geology. 

How to cite: Correia, N., Neves, V., and Gandra, A.: The Role of Interdisciplinary PBL Activities: Climate of the Past, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4396, https://doi.org/10.5194/egusphere-egu24-4396, 2024.

EGU24-4421 | Posters on site | EOS5.2

The Greenhouses Affect 

Gülperi Selcan Öncü

Recently, in the news programs on TV channels, we frequently come across news such as the melting of glaciers, weather events such as sudden and heavy rains and storms, the increase in atmospheric temperature and the increase in forest fires. At the same time, we observe some of these events in our immediate surroundings. There is also a sentence frequently mentioned by the public: the seasons are changing. The students asked questions such as why all these events occur and what has changed between the past and the present.

We all know that they need to understand global warming in order to understand these changes, but as a science teacher, I guided them on how to achieve this so that they can have the ability to use experimental methods within the project-based learning approach. They first conducted a preliminary literature review and then designed an experiment. In the experiment, they tested the hypothesis that the water inside a glass bowl covered with black cardboard heats up more than the transparent glass bowl. Thus, they tried to investigate the impact of greenhouse gases on climate change.

 In the experiment, two glass bell jars were used to represent the atmospheric layer. The inside of one of them was covered with pieces cut from black cardboard at intervals. Black cardboard was used to represent greenhouse gases because black color absorbs light. The same amount of water was filled into two beakers of the same size. A thermometer was placed inside them and the bell jars were turned upside down on the beakers and closed. Two thermometers were used to measure the temperature of the water in the beakers. The first mechanism (not coated) is also the control group. The second device (covered with black cardboard) is the experimental group.

 In the experiment and observation phase, the independent variable is the bell jars and the dependent variable is the water temperature. Control variables are bell jar size, beaker size, amount of water and environmental conditions. After the installation of the mechanisms, the initial temperature of the water was measured and recorded. The students carried out this research by placing the mechanisms in a sunny place on a sunny day. They recorded the data in tables they prepared at certain time intervals.

Later, they shared the results with the participants at the science festival. Thus, they tried to explain the causes of the global warming problem and draw attention to the necessary measures to prevent this problem.

How to cite: Öncü, G. S.: The Greenhouses Affect, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4421, https://doi.org/10.5194/egusphere-egu24-4421, 2024.

EGU24-4432 | Posters on site | EOS5.2

Teaching Climate Change: using Earth Learning Ideas 

Pete Loader, Giulia Realdon, Guillaume Coupechoux, Xavier Juan, and Gina P. Correia

Global anthropogenic climate change is real and so it is essential to include this topic in our curricula to enable students to understand the scientific evidence and the possible effects this might have on our lives.

This poster provides an insight into some of the practical ways that climate change topics might be taught using the free online ‘Earthlearningidea’ website (https://www.earthlearningidea.com/English/Resources_and_Environment.html#clchange). As such, it is designed to reflect the GIFT 2024 workshop run by our EGU Geoscience Education Field Officers and to demonstrate the range of ELIs undertaken in their respective countries. It is also presented in fond memory of Professor Chris King who was the instigator and inspiration of this and so many other geoscience education projects in the UK and abroad.                                   

These climate change activities and others are available at the Earth learning website (https://www.earthlearningidea.com/), a repository containing more than 400 activities ready to use and translated into different languages. All are designed to develop students’ critical thinking and research skills, while developing their knowledge and understanding of Earth processes and products.

EGU Geoscience Education Field Officers (GEFO) are a team of geoscience teachers and researchers who provide professional development to schoolteachers who have elements of geoscience in their teaching curricula, through interactive hands-on workshops. The team is supported by the European Geosciences Union Education Committee and is active in eleven countries around Europe. (https://www.egu.eu/education/).

How to cite: Loader, P., Realdon, G., Coupechoux, G., Juan, X., and P. Correia, G.: Teaching Climate Change: using Earth Learning Ideas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4432, https://doi.org/10.5194/egusphere-egu24-4432, 2024.

EGU24-4440 | Posters on site | EOS5.2

HIPER motivated students follow the SUPER-MOUV sea campaign 

Jean Luc Berenguer, Faustine Gendron, Christelle Saliby, and Julien Balestra

The coasts of Ecuador and Colombia have been hit by several earthquakes of magnitude greater than 7.5 over the course of the 20th century. An earthquake of magnitude 7.8 struck near the town of Pedernales in April 2016. It was the most powerful earthquake to hit Ecuador in 70 years, claiming hundreds of lives and causing hundreds of millions of dollars in economic losses. The seismic data revealed the complex slip behaviour of this part of Ecuador's subduction zone. The shallow part of the megafault is characterised by slow-slip earthquakes that can last from a few days to a few months and do not generate seismic waves (asismic rupture), so are not felt by the population. What controls these slip events is still poorly understood, even though they play an important role in the seismic cycle that governs the periodic loading and release of the megafault. The aim of recent oceanographic missions (the HIPER and SUPER-MOUV expeditions) is to understand how structure, temperature and fluids affect slip behaviour and the transition from seismic to asismic rupture. Many schoolchildren were involved in these scientific missions, following the mission's progress on a daily basis. Each following school was in contact with an education team on board and on land. Working closely with the researchers, the pupils were able to follow the work on board the ships, solve weekly scientific puzzles and take part in live video conferences from the oceanographic ship. Allowing students, the future citizens of the world, to experience first-hand how science works... these are essential elements in strengthening the link between science and society. 

How to cite: Berenguer, J. L., Gendron, F., Saliby, C., and Balestra, J.: HIPER motivated students follow the SUPER-MOUV sea campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4440, https://doi.org/10.5194/egusphere-egu24-4440, 2024.

EGU24-4443 | Posters on site | EOS5.2

Insight Education : When highschool students and teachers are involved in the science team. 

Jean Luc Berenguer, Christelle Saliby, and Julien Balestra

InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a discovery program, lead by NASA, that has landed a single lander on Mars and other sensors, such as a seismometer, a heat flow probe, and more others sensors that provided a lot of data.

The main payload is the seismometer called SEIS, that is the first seismometer (after Viking fail) to record signal with a very deep precision. The goal of this mission is to investigate the dynamics of Martian tectonic activity and understand all the processes that shaped the Red Planet.

Students were able to benefit from the data recorded by SEIS, and transmitted, with little delay, to schools by the science team. In this presentation, we will show all the practical activities done with kids, teens and students in France and other countries during the space mission (2018-2022).

This work has been done by a French team of teachers, in international cooperation with others countries (with UK, USA, Switzerland, Spain, Romania ...) and can be found on this specific website: https://insight.oca.eu

As the InSight mission draws to a close, a survey was conducted within the Education community to assess the impact of such an education component in a research programme.

How to cite: Berenguer, J. L., Saliby, C., and Balestra, J.: Insight Education : When highschool students and teachers are involved in the science team., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4443, https://doi.org/10.5194/egusphere-egu24-4443, 2024.

EGU24-4448 | Posters on site | EOS5.2

Take a photo, post it, alert it! 

Mite Ristov

Encouraged by the problem of constantly air pollution, especially in the winter mounts, a group of students from the Josip Broz – Tito High School from Bitola, North Macedonia, under the mentorship of the geography teacher and in cooperation with the NGO Geosfera, conducted a school project. The main objectives of the project were: raising awareness among pupils about the harmful effects of PM particles on human health, identifying the city's air polluters, measuring PM particles concentrations in different locations around the city and informing the public and preparing draft mitigation measures of air pollution.

First, the students held an educative lecture in front of the rest of the pupils at the school about the harmful effects of PM particles on human health. Then, we started a campaign to involve students and all citizens of Bitola in identifying the city's air polluters. Through the social networks, instructions were given, such as through an online Аpp and the GPS signal from the smart phone, to take a picture from a suspicious air polluter and to post the image with the given geographic coordinates on our Facebook group. A working group of students, according to the given coordinates of the citizens, put the polluters on an interactive map of Google Maps. A link from the map was sent to the authorized environmental inspector in the municipality, with the goal of faster response and inspection to those polluters.

The absence of multiple measuring stations created numerous speculations among the citizens, but also with the institutions in the city, where the enormous air pollution originated, whether from the Thermal Power Plant Bitola or from the city itself.

Therefore, in cooperation with the NGO Geosfera, we decided to measure the current concentrations of PM10 particles in two periods of the day, between 14 and 15, and between 19 and 20 hours. The measurements were made with a mobile particle detector at 14 locations. After the measurements were made, using the Google Earth, two maps were created, showing the results of the measurements. The obtained results confirm the suspicions that the cause of enormous air pollution in Bitola is not TPP Bitola, but households that mostly warm their homes with firewood (over 60%, Source: State Statistical Office). Also, a large number of citizens of our Facebook group have commented that part of the problem are Forest enterprises, which usually supply wet firewood. According to the US EPA, wet wood produces three times more PM particles compare with dry wood.

The students from the school, in cooperation with the NGO Geosfera and the geography teacher, developed and submitted to the Municipality measures for reduction of air pollution. All these proposed measures were placed on an interactive map on Google Maps, through which all the citizens of Bitola will be able to visualize them.

The action received positive reviews from the public in the city and achieved the desired effect, which is raising awareness among young people and alerting the competent institutions to solving the accumulated problems.

How to cite: Ristov, M.: Take a photo, post it, alert it!, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4448, https://doi.org/10.5194/egusphere-egu24-4448, 2024.

EGU24-4452 | Posters on site | EOS5.2

GIS for Gist of Europe 

Crina Aurelia Elefteriu

             

 

               In the context of global climate change, the importance of understanding and effectively managing the environment is becoming more urgent. The digitization of geography, through Geographic Information Systems (GIS), is an essential methodological component for identifying, monitoring and managing geographical phenomena with major impact on climate. Teaching climate change at school is based on examples of good practice, learned and applied through the Erasmus+ project "GIS for Gist of Europe".

             The project addresses the issue of climate change by including GIS in the curricular area sciences, the objectives and priorities of action being in the field of school education.The partners of the Erasmus + project ” GIS for Gist of Europe” bring to our project diversified experience and invaluable resources, these being EUROGEO VZW from Belgium, Riga Secondary School No. 25 from Latvia, Universidad de Zaragoza from Spain, Yenilikçi Eğitim Derneği from Turkey, Sint-Lodewijkscollege from Belgium. Each partner brings a unique perspective and meaningful skills to achieve our common goals.

            Through the LMS-Gis for Future platform, teachers are taught to digitize geography, as well as how to understand, use and apply geospatial technology. Topics related to exploiting desert infrastructure, climate migration of people, supporting alternative resources and desertification are easy to apply as a result of completing this course.

            The second product of the project materializes in a learning module because the technology of geographic information systems allows us to model and see very complicated relationships and ways to respond more intelligently. As there is a need to promote GIS knowledge, monitor elements of local interest and centralize urban issues, this climate change learning module can support the teaching of geosciences. Learning the working methodology in disciplines such as meteorology and synoptic, remote sensing and photointerpretation and applied informatics in geosciences.

            The third product of the project is based on case studies related to climate change. With the help of GIS, the integration of climate change leads to the formation of a new generation of young people prepared to understand and face the challenges of climate change.

            The project is not only limited to providing theoretical knowledge, but also provides the tools to turn this knowledge into concrete actions. By facilitating the understanding, monitoring and management of geographical phenomena associated with climate change, a generation of young people responsible and involved in environmental conservation is prepared.

            Thus, integrating GIS into school curricula is not only a necessity, but also an opportunity to actively contribute to the formation of a conscious society. Students become change agents, able to propose innovative solutions and participate in global efforts to combat climate change. In the end, this project not only achieves its goals, but also represents an investment in a sustainable future, where education plays a central role in saving our planet.

            Keywords: GIS, Erasmus+, climate change

How to cite: Elefteriu, C. A.: GIS for Gist of Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4452, https://doi.org/10.5194/egusphere-egu24-4452, 2024.

EGU24-4568 | Posters on site | EOS5.2

Augmented Reality Supported Renewable Energy Game 

Gülsüm Yasemin Uz

The aim of this project is to investigate the impact of game design with AR-VR-supported cards on elementary school students' knowledge of Energy Resources and to explore students' opinions about the game. The project used a single-group pre-test-post-test quasi-experimental model, with a sample of 12 students from the 5th grade. A game designed to be played using AR-VR-supported cards was created in the project. Unity software was used for the design of AR-VR-supported cards, and 3D apk files that can be loaded onto phones were generated. AR-VR target images for this application were selected from visuals in the Canva program. Physical environment prints necessary for the game were also printed on hard cardboard.

The designed game was played with 12 5th-grade students in different sessions. Before and after the game, an Energy Resources Information Survey and a Game Feedback Form were administered to the students to assess changes in their knowledge. The application steps of AR-VR cards and opinions about the game were also collected.

As a result of the project, it was concluded that the game with AR-VR-supported cards increased students' knowledge of energy resources, made them aware of the positive and negative characteristics of resources, and received positive feedback from the students regarding the designed game. The project also contributed to the educational environment by introducing a game design incorporating AR-VR-supported cards.

How to cite: Uz, G. Y.: Augmented Reality Supported Renewable Energy Game, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4568, https://doi.org/10.5194/egusphere-egu24-4568, 2024.

EGU24-4603 | Posters on site | EOS5.2

"The changing climate of Our Planet" 

Fatbardha Sulaj

"The changing climate of Our Planet"

Autor : Fatbardha Sulaj ( teacher to Biology – chemistry) email: fatbardhasulaj@yahoo.com

Shkolla e Mesme e Bashkuar “Dervish Hekali” Hekal,Mallakatër,Albania.

 

To talk about a climate that is changing on Earth, we have to look back at school. because the School is the factory that produces global citizens and who must think globally, not individually.

Educating in students the love for the Earth and instilling the key concepts that play a role in stopping climate change on earth to new generations.. Their thinking should always be critical, always looking at the opposite side of the coin. Our people say: "whatever you sow, you will reap." 'so how do we treat the earth, we will get that behavior. Man's behavior towards it is like tribute. Which means if we abuse with technological booms for some benefits for the human being, then this is where the scary legend of climate change begins. This is where it starts. To think about our longevity and health, we must first think about the earth itself, the longevity of its systems and ecosystems.

If you see a fire, think about how much CO2 is added to the atmosphere, how the temperature increases, how the glaciers melt, how the sea level rises. Think of the greenhouse effect, think of everything with plants, animals and a series of links in the food chain.. If you are going to kape the time, then run to find a solution that the pollution increases in parallel with  ozone  broken,  with the smog burdens above  the cities

So try to listen to the cries of the our Planet, but to hear this you must first love the Earth, our Planet, and this is what a Global Citizen does.

Roosevelt said: A nation that destroys its soil destroys itself.

It is important to note that climate change today is driven by human activities and partly as a result of climate variations that occurred in the past. Studies focus on the extinction of species and the evolution of living things, changing ecosystems, industrial revolutions and technological booms. , the change of temperatures, is an exclusive panorama of the human creature.

So we create good things for life, forgetting that we become destroyers of the Globe

Climate change is not a segment, or a film sequence that happens somewhere and ends there, but a phenomenon that causes chain consequences.

Methodology to involve students in the topic"The changing climate of Our Planet "

  Tailor teaching methods to their interests and learning styles, fostering a sense of urgency, empowerment and personal connection to the subject. Some of the methods that are important to students about changing climate and make the topic attractive are:

1-Visual appearance

2-Interactive activities

3-Show documentaries or short films

4-Personal history

5-Data in real time

6-Gamification

7- Field trips

8-Invite climate specialist speakers or environmental activists

9-Emphasize the solutions

10-Emphasize the success stories of individuals

11-Open discussion

12- Call to action

This constitutes the final phase of the entire lecture to "The changing climate of Our Planet ".

How to cite: Sulaj, F.: "The changing climate of Our Planet", EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4603, https://doi.org/10.5194/egusphere-egu24-4603, 2024.

EGU24-4698 | Posters on site | EOS5.2

Microplastic Pollution Projects and Participatory Science 

Agnès Pointu

Plastics include different types of polymers, often mixed with additives which give them the desired properties (flexibility, rigidity, color, fire resistance, etc.). The diversity of properties and possible uses of plastics, combined with their strength and lightness, have made them a preferred material in many sectors (packaging, medical, construction, etc.). Their use has grown exponentially since the 1950s, today reaching 400 million tons per year.

Plastics are therefore present everywhere, whether in aquatic environments or in terrestrial environments. Today, the omnipresence of plastic waste at sea and on the coast has become a subject of major public, scientific and public health concern.

"Microplastic" refers to tiny plastic particles that measure less than 5 millimeters and that can be found in landfills, rivers, soils and mostly in oceans. These microplastics come from various sources such as the breakdown of larger plastic items (bags, tyres, bottles), microbeads in personal care products, and synthetic fibers from textiles. This widespread contamination rises a serious threat to marine life, ecosystems and human healthcare.

 Although microplastic pollution is major environmental concern, this topic is not yet included in school programs. In order to involve students to this crucial pollution problem, we are experimenting a science club with all volunteer students since September 2023.

The club is part of two national participatory science projects which consist in collecting data, conducting experiments, and analyzing results and communicate with researchers. The first project has been initiated by the Tara Ocean foundation. This project is an educational operation serving education in science and sustainable development which offers students the opportunity to contribute to the inventory of plastic pollution on beaches and banks in France.The database created feeds scientific research and contributes to political decision support at different levels. We had to choose a sampling site on the banks of the Seine which has to be approved by scientists. The, we will collect plastic samples and, back at school, we will sort plastic according to their size. The data collected are used to complete a database which is freely accessible by any researcher.

The second participatory project in which the club is involved is the “Plastizen” project, lead by the CNRS . It aims to study the fate of biodegradable plastic bags in the soil by taking into account different ecological factors (temperature, humidity, pH). Some samples of conventional plastic and biodegradable plastic are buried in the soil. pH of the soil is measured. Then, each month, the samples have to be removed, measured, pictured and the results are sent to CNRS.

These two projects allow discussing the scientific contents and methodologic approach of science with the students.  But we also plan to organize local cleanup events, and awareness campaigns (creation of informational posters, comic strips, …).

The poster will describe the challenges of this work, the way it has been driven and the first results. The exchanges with the students and their perception of these participatory projects will be summarized and discussed.

 

How to cite: Pointu, A.: Microplastic Pollution Projects and Participatory Science, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4698, https://doi.org/10.5194/egusphere-egu24-4698, 2024.

EGU24-4721 | Posters on site | EOS5.2

Teaching evolution for sustainability in the era of climate change: the Socio-Scientific Issues (SSI) approach 

Giulia Realdon, Patricia Pessoa, and Xana Sá-Pinto

The concept of sustainable development has been at the centre of public debate since the 1980s, but the challenges to sustainability have become more urgent in recent years due to rapid environmental changes that threaten the planet's biological support systems (United Nations, 2015). These threats include, but are not limited to, global warming, with a growing number of extreme weather events causing natural disasters, rising sea levels and ocean acidification, environmental degradation, biodiversity loss, resource depletion and international migration driven by these factors.

Against the backdrop of a rapidly changing world, new approaches to sustainability education are needed. One such approach is based on the teaching of evolution using socio-scientific issues (SSI). In fact, understanding evolution is necessary to understand and predict ecosystem responses to rapid environmental change and their consequences for human societies, so that to devise possible solutions informed by evolutionary biology.

SSIs are ill-structured problems and dilemmas, controversial in nature, without immediate and clear solutions, which require evidence-based considerations and can be informed by various ideas and perspectives, such as economic, political, and ethical ones (Zeidler, 2014).

The SSI-based pedagogical approach uses controversial and personally relevant issues that require scientific reasoning but include social aspects that require "students to engage in dialogue, discussion, debate and argumentation; they integrate implicit and/or explicit ethical components that require some degree of moral reasoning" (Pessoa et al. in Sá-Pinto et al., 2023).

In this session, we intend to present a teaching resource produced within the COST Action EuroScitizen project.

This resource is an open access e-book entitled "Learning evolution through socio-scientific issues" http://www.euroscitizen.eu/2023/02/03/learning-evolution-through-socioscientific-issues/

It is the result of contributions from 34 authors and 29 reviewers from 15 different countries. The authors of this poster were involved as editors, authors and reviewers (Sá-Pinto and Pessoa) or as reviewer and coordinator of the Italian translation (Realdon).

The e-book comprises two parts:

- chapters addressing theoretical and methodological issues related to science literacy, SSI education approach and evolution education;

- chapters presenting good practice examples with the use of the SSI approach in formal and non-formal evolution education.

The resource focuses on a number of examples (biodiversity conservation, health issues, e.g. pandemics, antibiotic resistance, agriculture and pesticide resistance, ...), but the SSI approach can be profitably exploited in other diverse and interdisciplinary contexts, such as natural resource use (water, minerals, fossil fuels), energy production, land management, waste disposal, climate change mitigation and many others, all of which are related within the framework of sustainability education.

 

References

  • Sá-Pinto, X., Beniermann, A., Børsen, T., Georgiou, M., Jeffries, A., Pessoa, P., Sousa, B., & Zeidler, D.L. (Eds.). (2022) - Learning Evolution Through Socioscientific Issues. UA Editora, 219 pp.
  • United Nations. (2015) - Transforming our world: The 2030 agenda for sustainable development department of economic and social affairs. United Nations
  • Zeidler, D.L. (2014) - Socioscientific Issues as a Curriculum Emphasis: Theory, Research and Practice. In N. G. Lederman & S. K. Abell (Eds.), Handbook of Research on Science Education, Volume II, Routledge, 697- 726

How to cite: Realdon, G., Pessoa, P., and Sá-Pinto, X.: Teaching evolution for sustainability in the era of climate change: the Socio-Scientific Issues (SSI) approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4721, https://doi.org/10.5194/egusphere-egu24-4721, 2024.

Can the 3Rs approach combat the escalating waste problem and the climate change? Are bio-based products the solution for a sustainable future? Through this project students will learn about bioeconomy, using their STEM skills and the results of the labs activities, they try to solve some challenges: to give new life to obsolete material. They were divided into working groups to explore the problem, develop labs activities and propose their ideas.

Keratin from wool

Sheep’s wool has always been used as an agricultural product by pastoral communities, but in recent years, it went from agricultural product to waste. Shearing the flocks is an act that farmers must perform at least once a year to maintain the animal welfare, but as wool has diminished its economic power, it has become just a cost. In 2015 it has been calculated that around 200,000 tonnes of coarse wool are produced each year in Europe, the disposal of which is a problem. It is no longer possible to abandon the wool in the pastures or left to burn slowly, with the consequent release of toxic gases and carbon dioxide into the atmosphere. In recent years, to revalue the product and the market, there has been increasing academic and industrial research aimed at exploiting wool particles as textile materials, filtration adsorbents, cosmetic materials, and biomaterials.

Wool fibers consist of 95%−98% proteins (about 80%−85% keratin), lipids (0.1%), and minerals (0.5%), using chemical and mechanical methods, it can be utilized as a natural source of keratin. The natural keratin can be used to produce a variety of cosmetics, creams, shampoos, hair conditioners and biomedical products. Several methods for keratin extraction and production of hydrolyzed keratin have been proposed in the scientific literature. They vary depending on the intended uses of the obtained product, whether for cosmetic, pharmaceutical, food use.

The activity proposed to the students is to explore the wool economy and the chemical composition and to develop experimental activities to extracts  keratin from wool using a suitable extraction solution and use keratin to prepare cosmetics.

Pectine from citrus peel

Pectin is yellowish, odorless powder soluble in pure water. It is an important cell wall polysaccharide that allows primary cell wall extension and plant growth. Pectin is used for different applications in dairy, confectionary, pharmaceutical and food and the industrial application of it is increasing.

A factory producing flavor, near our school, proposed to the students the challenge to reuse the citrus peel coming from a strong extraction of essential oils. Students analysedd the composition of peel and proposed to extract pectin using HCl solution and precipitation with ethanol.

Conclusion

The proposed activities fit a broader project on the valorization of waste. These are simple experiments that fail to exhaust the extensive literature related to the use of biomass from waste material but start from a material that is known to all and easy to find.

How to cite: Zambrotta, M.: Climate change and sustainability resources: making materials from biomass, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4722, https://doi.org/10.5194/egusphere-egu24-4722, 2024.

EGU24-4734 | Posters on site | EOS5.2

Reducing our school's carbon footprint through composting the canteen food waste 

Marta Molinos Solsona

Over one-third of global food production is estimated to contribute to the waste stream, leading to greenhouse gas emissions. Composting food waste emerges as a sustainable solution, effectively mitigating emissions by sequestering carbon in the soil, while also offering various environmental, economic and social benefits. However, food waste management pathways are mainly landfilling and controlled combustion, only a little fraction ends up being composted.

Our secondary school is actively engaged in promoting recycling and sustainability within the scholar and local communities. With the active collaboration of students, we initially focused on separating light packing and paper, but we recognized that a substantial portion, approximately 40%, of our waste was organic waste from the school canteen. In response, we launched a composting initiative to convert this organic waste into valuable fertile soil.  Presently, four composters are consistently fed twice a week, yielding compost that enriches the soil in our school vegetable garden.

This poster shows the comprehensive procedure, detailing the collection of food waste and the employed composting methods, including vermicomposting. The final product is a nutrient-rich organic material that enhances soil structure, fertility, ad moisture retention.

This experience has not only significantly reduced our school’s waste output but has also played a pivotal role in raising awareness and educating students about climate change, waste-related issues, and the importance of local actions. Through active collaboration, we aim to install a sense of responsibility and environmental consciousness among students, fostering a sustainable mindset for the future.

How to cite: Molinos Solsona, M.: Reducing our school's carbon footprint through composting the canteen food waste, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4734, https://doi.org/10.5194/egusphere-egu24-4734, 2024.

Teaching about the ongoing climate crisis feels many times emotionally exhausting. This is particularly because it is often sensed that a large number of our students are hopeless about climate change and its impact. In our experience, we have also recognized that classroom discussions may result in misleading conclusions, namely that “if there is hope, is not for us”.  

Therefore, in recent years, I have been trying to explore new methods to approach this subject. I have searched how students' interest about climate crisis, i.e., global warming and climate change, as well as their engagement as citizens to deal with climate crisis could be awakened.

The aspects that I have particularly explored are as follows:

1).Geological field studies together with scientists provides new insights into climate crisis

Since 2013, I have been working on several projects in collaboration with researchers at the Department of Geological Sciences at Stockholm University. This collaboration began when I participated in a Research Council. Since then, I have been co-leading several projects, which had resulted in that many of my students participated in scientific activities, including making observations, collecting data, and doing fieldwork. By doing fieldwork my students have got new insights into and the time to reflect over the present as well as the past climate changes. This is a way of learning that the “climate crisis” is in fact “a geological problem”.

2). Engagement creates hope

I have been involving my students in several cultural projects where they had the opportunity to express their thoughts about climate crisis to politicians, dream about future solutions, and to search why other people in the society make their voice heard through climate demonstrations. By participating and expressing their thoughts in such activities, my students realized that they could contribute making “Earth a wonderful planet to live on”. For examples, a group of them participated in a workshop co-organized by Stockholm University, the Researchers’ Desk, and Lava at Kulturhuset Stadsteatern. The students created textile messages to politicians and decision makers about climate change.

In another project, my students have participated in the research project “Utopian stories”, a collaboration between the Department of Literary Studies and the Centre of Digital Humanities at the University of Gothenburg and the Bolin Centre for Climate Research at Stockholm University and the Nobel Prize Museum.

How to cite: Bredberg, C.: “Climate crisis and its impact: New ways to awaken curiosity and hope in the classroom environment”, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4750, https://doi.org/10.5194/egusphere-egu24-4750, 2024.

In France, during the COVID—19 pandemic, I received many questions from my students while we were “at home”, like “I have read that, is it true?” or “I am aware because I have read that …”. This questioned me a lot, especially since they spend more than 7 hours a day on their phones and social media!

In response, for their last grade in French curriculum focusing on the theme of climate change, I decided to have an approach based on what they read on social media, to warn them not about what they read but more about “how could you know this information is true?”, “How could you trust what you are reading?” or “Why do we want to trust this information (which is eventually wrong)?”. As I am also a user of their social media, I felt it was a good way.

My approach is based on the book “La démocratie des crédules” and “Apocalypse cognitive” written by Gerald Bronner, a famous French sociologist. This book adresses misinformation and cognitive biases and has received awards such as the “Europe Social Sciences Award”. It explains for example that nowadays, fake news are more and more present because we don’t have enough motivation to fight fake news online, allowing misinformation and their consequences to spread.

The lessons begin with students analyzing recent and controversial news. Then they must raise cards indicating, for example, the need for verification or identifying logical errors. They have several cards in hands, and they need to choose the better ones according to the information I show them. This interactive process forms the basis for further discussions, linking the lessons to the overarching theme.

One of the projects also involves students creating a forward-looking climate report, and it needs to be futuristic (for example, as if they made it in 2050). I will show some videos they made thanks to QR-code in the poster. Linked to that, the course incorporates elements inspired by the movie “Don’t look up”, offering a perspective on the challenges the world must face in order to trust scientists or to be really warned by the climate change. It’s also interesting for them because my high school is renowned for offering an artistic curriculum.

The culmination of the course is a Fake News competition, testing students' ability to discern misinformation within the context of climate change. This project not only evaluates their critical thinking skills but also empowers them to actively combat the spread of false information.

To resume, the goal of this lesson is to equip students with the tools to critically evaluate information not only information related to climate change, but also future scientific information they will encounter (vaccination, DNA editing …).

How to cite: Dubreu, E.: Critical thinking in high school science education: a focus on Fake News and Climate Change., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4753, https://doi.org/10.5194/egusphere-egu24-4753, 2024.

EGU24-4765 | ECS | Posters on site | EOS5.2

Simulating and Studying Greenhouse Effect in your classroom with Arduino UNO 

Konstantinos Louvaris and Antonia - Zoi Mammi

The lesson employs a hands-on approach, involving a Greenhouse Effect Simulation using an Arduino UNO. This approach, following the principals of J. Bruno’s learning by discovery and trying to avoid the criticism to the original greenhouse effect experiments raised by a recent paper (M. Bertò et al, 2014) aims to make the subject more interesting for students, fostering practical skills in science and technology. Students experiment with modifying variables in a simulation setup, which includes a glass basin with limestone gravel, an infrared lamp, and a sprayer. The simulation introduces the concept of acid rain and its interaction with limestone, resulting in the release of CO2. Three scenarios are explored: one without CO2, one with water vapor but no CO2, and one with "acid rain on limestone," generating CO2. The sources of atmospheric CO2, including natural and anthropogenic processes, are discussed within this context.

To monitor temperature changes in the simulation, students use Arduino, a temperature sensor and an infrared sensor allowing them to analyze and understand the impact of different scenarios on temperature patterns. The lesson emphasizes the importance of monitoring temperature changes in correlation with climate patterns, providing students with a tangible connection to real-world challenges. Note that basic Arduino concepts are introduced to familiarize students with microcontrollers, sensors, and programming.

 

Subject: Geology - Geography, Chemistry, Informatics

Grade: 12-14 years old

Duration:  two class periods

General Objectives:

This lesson includes a brief overview of greenhouse effect and its causes and impacts on temperature patterns and climate change.

Lesson Plan - Objectives:

  • The students get familiar with greenhouse effect and systemic correlations.
  • The students experimenting with a Greenhouse Effect Simulation.
  • The students monitor the Temperature in Simulation

How to cite: Louvaris, K. and Mammi, A.-Z.: Simulating and Studying Greenhouse Effect in your classroom with Arduino UNO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4765, https://doi.org/10.5194/egusphere-egu24-4765, 2024.

EGU24-6146 | Posters on site | EOS5.2

CLIMAte change teachers’ acaDEMY (CLIMADEMY) 

Emmanouil Kartsonakis

The CLIMAte change teachers’ acaDEMY (CLIMADEMY) aims to create a European partnership of teacher’s education and training providers across Europe in order to develop the European and international dimensions of teacher’s education, contributing to the achievement of the objectives of the European Education Area. CLIMADEMY aims to offer a comprehensive program where teachers will interact and learn how to educate the next generation of European citizens on climate change issues.

Climate change is unequivocally attributed to human activities and is already affecting Europe, leading to heat waves, extreme drought and flood events, forest fires, biodiversity loss, decreasing crop yields and affect human health. The European Parliament acknowledges that ‘education for young people represents one of the most effective tools for compacting climate change’. However, climate change is not yet broadly incorporated in school science curricula.

CLIMADEMY aims to fill this gap by developing and establishing a network and community of practice to create innovative strategies and programs for preparatory and continuous professional development for serving and student teachers on climate change and its impacts. The consortium consists of four EU countries (Finland, Germany, Greece and Italy) and once operationally established, it will be open to new members.

Educational material focused on the drivers causing the human-induced climate perturbations, the impacts of climate change and the measures for sustainability, will be tailored for initial education and professional development and made openly available to all education institutions across Europe.

The material will be jointly developed, designed to be easily accessed, adopted and replicated, using modern educational practices and tools, with teachers acting both as trainees and co-designers. It will be the basis for the Teachers’ Academy for climate change education to be established through one common virtual Climate Auditorium (CLAUDI) and four hubs in separate countries with specific foci driven by the regional particularities.

The CLAUDI platform will host the material, online courses, and the forum where all teachers and learners meet and exchange ideas and experiences, thus building the Teachers'. The material will be developed in English, German, Italian, Greek and Finnish.

During the three years of CLIMADEMY, the first 200 serving and student teachers across Europe will have piloted the activities through online, physical and blended training and will be the seed that will lead to the growth of the network and distribute its aims. Substantially more teachers will be virtually trained and schools involved, contributing to the Education for Climate Coalition of the European Environment Agency.

Further information

CLIMAte change teacher’s academy (CLIMADEMY)

Programme: ERASMUS2027 (Teacher’s Academy)

Project ID: 101056066 EUROPEAN EDUCATION AND CULTURE EXECUTIVE AGENCY (EACEA)

Duration: 36 months (1 June 2022-31 May 2025)

Location: Greece, Italy, Germany, Finland

Webpage: https://climademy.eu

How to cite: Kartsonakis, E.: CLIMAte change teachers’ acaDEMY (CLIMADEMY), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6146, https://doi.org/10.5194/egusphere-egu24-6146, 2024.

EGU24-6609 | Posters on site | EOS5.2

NASA GPM Mentorship Program - Educator Track 

Lisa Milani, Raffaella Barozzi, Michele Bononi, Ennio Cantoresi, Giulia Ciantra, Pancrazio di Angelo, Andrea Davì, Laura Insogna, Sara Milan, Anita Paganelli, Tania Patrizio, Ilaria Piccioni, Elisabetta Ricci, Luca Samiolo, Carla Ventura, Michela Zanella, Andrea Portier, Vasco Mantas, and Dorian Janney

The NASA’s Global Precipitation Measurement Mission (GPM) Mentorship Program from 2023 hosts a spin-off program dedicated to teachers and educators. During its first year this pilot effort connected a GPM expert with Italian middle- and high-school teachers to learn about the water cycle, climate change and precipitation through the lens of the GPM mission. Given the success of the first year, for the 2023-2024 school year the program has been extended to every school grade, from kindergarten to high school, involving students from 5 to 18 years old. The main focus of the project is to provide information and tools to teachers in order to be able to pass the scientific knowledge to their students. After three lectures about water cycle, weather and climate, and the GPM mission and its applications, the teachers aided by the GPM expert develop a practical project with the students. The project is multidisciplinary and focused on precipitation, from measurement using rain gauges deployed in the school yard, to data analysis comparing measured data with GPM satellite retrievals. Classroom discussions on precipitation trends and changes lead to climate change awareness and link this project to other programs on sustainability developed by the schools. This paper will provide an outline of the program and an overview of the practical projects led by the teachers. The program is in constant development, expanding into Portuguese-speaking communities and other countries such as Turkey, to develop educational material in different languages to reduce language barriers and increase exposure opportunities of Earth observation data.

How to cite: Milani, L., Barozzi, R., Bononi, M., Cantoresi, E., Ciantra, G., di Angelo, P., Davì, A., Insogna, L., Milan, S., Paganelli, A., Patrizio, T., Piccioni, I., Ricci, E., Samiolo, L., Ventura, C., Zanella, M., Portier, A., Mantas, V., and Janney, D.: NASA GPM Mentorship Program - Educator Track, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6609, https://doi.org/10.5194/egusphere-egu24-6609, 2024.

EGU24-6621 | Posters on site | EOS5.2

World climate simulation 

Soumaya Thabet

The IPCC experts attribute unequivocal human influence to the observed climate change. The global temperature has increased by approximately 1.1 degrees celsius compared to the preindustrial era, with negative impacts on worldwide populations and ecosystems.

A world climate simulation is an in-person role-playing excercice of the UN climate change negotiations. The simulation aims to rise awarness among students about the issue of climate change by having them take on roles of responsability, allowing them to become active participants during the mock UN summit. Participants work in groups, with each group representing a specific nation, negociating bloc or an interest group. To achieve the objective of staying below 2 degrees celsius of warming above the preindustrial levels, participants must discuss strategies, negociate, make decisions and collaborate to propose greenhouse gaz emissions reductions, land use changes and climate finance pledges. They can predict the impact of their proposals on the global temperature by using a computer simulation of the dynamics of the climate C-ROADS.

The project unfolds in three parts :

  • Understanding climate change : students engage in activities about the reality of climate change and its origins.
  • Negociating at the international level : preparing for negociation and participating in a negociation simulation.
  • Taking action locally and globally for the climate : discovering projects to take action for the climate.

How to cite: Thabet, S.: World climate simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6621, https://doi.org/10.5194/egusphere-egu24-6621, 2024.

EGU24-6738 | Posters on site | EOS5.2

Eco-Enigma Expedition Escape Room - The soils and climate change.  

Elsa Salzedas and Kelly O'Hara

Present an ongoing project named “ Eco-Enigma Expedition Escape Room”. The aim is
to an immersive escape room experience designed to raise awareness and promote
action against climate change. The storyline is about a critical mission, 60 minutes to
Rescue the Planet. By solving a series of puzzles and challenges within a limited
timeframe to prevent an impending environmental catastrophe caused by climate
change. Each puzzle/challenge/enigma reveals important pieces of information or/and
action that can help mitigate the crisis. The Escape room is composed by 6 activities,
each of then relates action for change the climate or behavior to do it and a specific
ODS substantiable goal. In each activity, players will collect a code that will be use to
open the door that drove them to a healthy planet. The escape room will be created
with students from Hight School, given this project a Win-Win situation, not only the
have to investigate, gather information, be creative, reflecting STEAM experiental
learning context, and at the same time, we produce a game that can be played by all
school, representing more that 1000 students.

How to cite: Salzedas, E. and O'Hara, K.: Eco-Enigma Expedition Escape Room - The soils and climate change. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6738, https://doi.org/10.5194/egusphere-egu24-6738, 2024.

EGU24-6739 | Posters on site | EOS5.2

Erasmus+ project and Geoparks for dissemination of Geology 

Ana Rosa Aragón

An Erasmus+ project is a great opportunity to promote Science and Interculturality in schools. That kind of project connects interdisciplinary learning with a strong emotional context of friendship across the borders. Particullarly, I’ve already run two successful e-Twinning projects in the past (“Our S-COOLest world-2012” and “Knitting our Common European Future with Threads of our National Culture-2015”). Students and teachers keep  unforgetable feelings and learning experiences from those projects.

The Middle School IES Nuñez de Arce in Valladolid (Spain) has received funds from the Erasmus+ programme. Taking advantage of that chance, the Biology and Geology department is really interested in disseminating Geology and having geoparks as our main focus.

Objectives of our Erasmus+ partnership:

  • Stimulating scientific experiences and promoting passion for Geology and Earth Sciences
  • Appreciating our geological heritage (Geoparks are devoted to global understanding and sustainability)
  • Transnational exchanges and visits in different geological and cultural environments
  • To deep the understanding of climate change, both in the Earth history and in last decades, natural and human-induced climate change)
  • Students will develop various competences (autonomy, organization, cultural awareness, communication strategies, foreign languages)
  • Teaching innovation and developing good practices at school

Our school and the closest Geopark to us:

  • IES Nuñez de Arce (Valladolid, Spain) has about 1,000 middle-class students without any behavioral problems and education-concerned.
  • The students involved in the project would be 15 to17 year-old.
  • Las Loras Geopark is a bit more than one-hour far from our school.
  • Las Loras Geopark covers an area of 95,076 ha. and its nature, biological diversity and art are outstanding.
  • Some of the most relevant geological features of the area include limestone moors, fluvial canyons, karst and structural reliefs, Mesozoic  sedimentary palaeoenvironments, statigraphic sequences of the western edge of the Vascocantábrica basin, alpine folds, faults, diapiric structures, oil fields and active geological processes.

The project outlines:

  • Short international exchanges (1 week) between students (about 20 students aged 15–17 each country), 2 participant schools at a time.
  • Working on the project within international teams (PBL).
  • Several educational programmes have been developed by the Geopark over the years to support school teachers on site.

Not only teachers of languages are concerned in Erasmus+ projects: if you’re a teacher of Science, don’t hesitate to involve in an Erasmus+ team.

How to cite: Aragón, A. R.: Erasmus+ project and Geoparks for dissemination of Geology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6739, https://doi.org/10.5194/egusphere-egu24-6739, 2024.

EGU24-7367 | Posters on site | EOS5.2

Teaching Climate change at school: increasing sustainable minded students and communities. 

Elena Porazzi, Antonio Maiolino, Maria Martorana, and Paola Marra

The high school “Liceo Scientifico V. Sereni” teachers are aware of climate change impacts and aim, through their teachings, to increase students' awareness and attention towards this issue. This year students are involved in two main projects on climate change: “Green School” and “Green It Up”. The “Green School” project aims to reduce schools' environmental impact through the implementation of sustainable practices and environmental education to promote ecological awareness among students and school staff. Last year, the entire school participated led by the 4LES class; this year, the entire school is involved again, coordinated by the 2LES and 4A classes in Laveno and 4C in Luino. The main activities that engaged students included:

  • Initial analysis of water, energy, and paper consumption; interviews with school staff and class representatives to understand any difficulties in implementing serious waste separation.
  • Contacts with the Municipality to highlight issues (water leaks, lack of suitable bins for waste collection).
  • Creation of news broadcasts to inform about proposed good practices.
  • Meetings with experts on various subjects: bloggers for textile impact, a lake expert on temperature rise consequences.
  • Designing and implementing a challenge in various classes to identify and reward the most eco-friendly class.
  • Designing sustainable packaging for take-away food.

This year our school participates also to "Green It Up" with two classes: 2A in Luino and 3A in Laveno. “Green It Up” is an interdisciplinary educational project addressing biodiversity loss and climate change. It engages students in understanding the causes and effects of these issues while offering practical solutions for sustainable development. Through workshops and hands-on activities, students learn about environmental and social impacts of human actions and develop their own project on biodiversity. Community involvement is crucial: the project not only educates students but also encourages their active engagement in promoting sustainable practices within the school and the community. The project's impact is twofold: it educates and empowers students as change agents. Participants become ambassadors for eco-friendly solutions, positively influencing their communities and advocating for responsible lifestyles. The aim of both projects is to move students from climate change awareness to action.

How to cite: Porazzi, E., Maiolino, A., Martorana, M., and Marra, P.: Teaching Climate change at school: increasing sustainable minded students and communities., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7367, https://doi.org/10.5194/egusphere-egu24-7367, 2024.

The study of Natural Science, covering Biology, Chemistry, and Earth Sciences, is mandatory in Italian Upper Secondary Schools, lasting 2 to 5 years, guided by National Guidelines (D.M. no. 211 of 7/10/2010), with a specific 4-year mandate for Earth Sciences activities. These activities emphasize "observation and experimentation in the classroom and in the field," employing multidisciplinary approaches. Despite the emphasis on Earth Sciences, research suggests Italian teachers tend to neglect this field compared to Chemistry and Biology. This bias may arise from a perception that the latter subjects are more crucial for university enrolment (Greco e Gualtieri, 2010; Occhipinti, 2014). Such attitudes may result from the diverse academic backgrounds of Natural Science educators, spanning Biology, Chemistry, Geology, and Agriculture (DPR 19/2016 and DM 259/2017).  

To understand the challenges in teaching Earth Science, a survey was conducted among Italian upper secondary school teachers last year (Gravina T. & Iannace A., 2023). Results highlighted the need for new teaching materials in Earth Science to align with National Guidelines, especially concerning the hours dedicated to Earth Science lessons.  

Consequently, we initiated the development of a specialized 5-year Earth science curriculum tailored for Liceo students (Classico, Linguistico, Scientifico, Scienze Umane). Here, we present the curriculum, designed to address the challenges faced in particular by teachers without a geological background, offering support in creating engaging and hands-on Earth science lessons. The curriculum underwent review by a group of Italian upper secondary school teachers to gather feedback and finalize it before implementation in schools next year. 

  

Gravina, T., & Iannace, A. (2023). Earth science teaching in Italian Upper secondary school: the floor to Natural Science teachers. In The Geoscience paradigm: resources, risk and future perspectives. Congresso congiunto SIMP, SGI, SOGEI, AIV, Potenza (Italy), 19-21 settembre 2023.  

Greco, R., & Gualtieri, A. F. (2010). Studio geologia perché... Risultati preliminari sull’indagine quali-quantitativa relativa alla scelta del corso di laurea in Scienze Geologiche. Geoitalia, 30, 38-41. 

Ministry of Education, Universities and Research. (2010). Ministerial Decree No. 211 of October 7, 2010. Official Gazette of the Italian Republic, General Series No. 292, December 12, 2010. 

Ministry of Education, Universities and Research. (2017). Ministerial Decree No. 259 of May 9, 2017. Official Gazette of the Italian Republic, General Series No. 126, May 31, 2017. 

Occhipinti, S. (2014). Models and guidelines for more effective tools and paths in active teaching-learning in Earth sciences: looking for a unifying principle (Dissertation). University of Camerino, International School of Advanced Studies (XXVI cycle).

How to cite: Gravina, T. and Iannace, A.: Revitalizing Earth Science Education in Italian Upper Secondary Schools: Crafting New Educational Materials Aligned with National Guidelines , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7797, https://doi.org/10.5194/egusphere-egu24-7797, 2024.

The GLOBE Program (www.globe.gov) presents protocols delving into biosphere studies, emphasizing biometry, phenology, and the GLOBE Observer application. These protocols offer a multifaceted approach to understanding and monitoring global ecosystems. Biometry involves precise measurement and analysis, fostering a global network of students, educators, and citizen scientists. Standardized biometric protocols contribute invaluable data to scientific research, unraveling the intricate web of life.

In phenology, GLOBE introduces protocols to observe and record life cycle events, deepening understanding of interconnected relationships in ecosystems. Participants contribute to a comprehensive grasp of the biosphere's dynamic nature through systematic data collection and analysis, recognizing patterns and trends.

The GLOBE Observer application is pivotal, empowering global scientific participation. Users engage in real-time observations, capturing vital information related to land cover, clouds, and the urban environment. Democratizing scientific involvement, the application enhances spatial and temporal resolution of biosphere data.

In summary, GLOBE Program's biosphere protocols provide a systematic framework for studying our planet's living systems. Incorporating biometry and phenology methodologies, along with the GLOBE Observer application, the initiative fosters scientific literacy and contributes to a global understanding of the biosphere. Amidst the challenges of a changing world, GLOBE biosphere protocols stand as a beacon, guiding a more informed and interconnected global community.

Keywords: GLOBE Program, biosphere protocols, biometry, phenology, GLOBE Observer application, ecosystem monitoring, scientific literacy, global collaboration, citizen science, data collection.

How to cite: Aceska, N.:  Unveiling the Biosphere: A Comprehensive Overview of GLOBE Program Protocols, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9584, https://doi.org/10.5194/egusphere-egu24-9584, 2024.

Miyagi Prefecture, in Japan, where my students and I live, faces the Pacific Ocean, named Sanriku east offing fishing ground, where we can see the "tidal current" where the Kuroshio and Oyashio currents meet. Therefore, both warm-water and cold-water fish species can be seen in the coastal waters. Miyagi Prefecture is also a place where different terrains intersect, such as the submerged coast of the Rias coast and the emergent coast of the coastal plain. Matsushima, one of the Three Views of Japan, is also a gift of such complex terrain. So, several fishing ports boasting some of the largest catches in Japan can be seen, and seafood is essential to our daily lives.

One of the brokers at the Shiogama wholesale market has always said this in recent years, "The sea is strange lately, the kinds of fish that are usually landed are often not landed." This is corroborated by data from the Fisheries Agency and others. The catch of cold-water fish species such as salmon is decreasing, and the catch of warm-water fish species such as yellowtail and gazami-Japanese blue crab- is increasing. The rise in sea temperature in coastal waters since 2014 also corroborates this. In other words, climate change is having an impact on the status of seafood landings.

On the other hand, this sea area has undergone significant crustal changes due to The 2011 off the Pacific coast of Tohoku Earthquake, and the seabed has been eroded by tsunamis, or conversely, inflow from land has been deposited on the seabed. As a result, the ecosystem of the seabed has changed significantly.

It is impossible to learn all of this in the curriculum of high school social studies geography in Japan, and collaboration with other subjects such as science is necessary. However, not only that, but I propose to learn with students about the impact of climate change from changes in the ocean using the learning method "Mystery" that originated in the UK, which can capture the complex relationship between the global environment and human life. This is because geography is a subject to learn about “RELATIONSHIPS WITHIN PLACES: Humans and Environments”.

How to cite: Yamauchi, H.: Lesson Proposal for Climate Change in geography: Utilization of "Mystery" as a Learning Method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9953, https://doi.org/10.5194/egusphere-egu24-9953, 2024.

EGU24-10910 | Posters on site | EOS5.2

School life as an ecological background for principled citizenship 

Edgar Fernandes and Maria João Rebola

The European Commission, in its guidelines for Learning for the green transition and sustainable development, encourages Member States to integrate sustainability across educational institutions and operations. Since 2022, Member States are urged to establish supportive learning environments that foster hands-on, interdisciplinary teaching and are relevant to local contexts. The Commission emphasizes active involvement of students, staff, local authorities, youth organizations, and the research and innovation community in promoting sustainability in education. This initiative aims to instill a comprehensive understanding of sustainability, aligning educational practices with the broader goals of environmental consciousness and climate action.

The Shire and the Real Food Garden: a students-based Eco-Team effort

CLIP's Eco-Team, comprising students and teachers, transformed an adjacent land into The Shire, focusing on planting endemic species strategically chosen with geospatial digital tools and expert databases, and the Real Food Garden, an organic vegetable garden. This initiative, involving students from Pre-K to Upper School, aimed at maximizing ecosystem services, enhancing climate change remediation strategies, and ensuring food security based on local produces. Regular curricular and extracurricular outdoor activities promoted physical sensory learning, fostering a more empirical and long-lasting understanding on how the environment works, and how they can be a part of its conservation and management. The students have been responsible for planning and managing these spaces and delivering the produce to the school bar and canteen, this way promoting ownership and emotional connection to their natural surroundings.

CLIP student: an environmentally conscient citizen

Throughout their academic path, students develop conceptual knowledge on their environment, entangling interdependence between its elements, and how human societies impact over it. However, in CLIP, year 9 students engage in the Ecothon, where they are invited to spend a whole school day researching about ecological issues related to areas like Resources Management, Sustainable Mobility and Waste Management, choose one to focus on, come up with an innovative solution, and pitch it to a jury. The winners bring their projects to national and international contests.

This inspires students to pursue subjects like Environmental Management, that demand not only for a theorical understanding of ecosystems processes and the dynamic interconnection and interdependence between biotic and abiotic factors, but a more experimental approach to learning about ecological management issues, with consequent elaboration of an investigative report. This Coursework results from fieldwork activities in natural environments in the region the school is located in. Samples are collected, and qualitative and quantitative data gathered and analysed through the application of in loco and lab techniques.

With the work done within these subjects and initiatives, CLIP students grow their ecological awareness while working on skills like organization of information, definition of coherent methodologies, analysis of results, taking conclusions over initial hypothesis and evaluating the work done, as well as improving their presentation and communication abilities. They are not afraid to feel challenged, they assume themselves as life-long learners, they think globally while acting locally, developing as principled and active citizens.

How to cite: Fernandes, E. and Rebola, M. J.: School life as an ecological background for principled citizenship, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10910, https://doi.org/10.5194/egusphere-egu24-10910, 2024.

EGU24-11644 | Posters on site | EOS5.2

The Importance of “Hands-On” Training for Basic and Secondary Level Science Teachers. 

Francisco Fatela, Teresa Drago, Tanya Silveira, M. Conceição Freitas, Rui Taborda, João Cascalho, Jacqueline Santos, and Marcos Rosa

Awareness about coastal environments and concerns over its behaviour and evolution has recently become a main issue in several countries around the world which have dealt with rapidly changing coastlines owing to climate change. In Portugal this theme was introduced in curricula of basic and secondary schools, some years ago, highlighting the variety of coastal landforms and their changing patterns. However such as with other subjects, students are quite limited to book contents, and practical coastal observation and monitoring (in a perspective of citizen science) are usually absent from the pupils activities, preventing the schools communities from realizing that they may be part of the solution. With this in mind, the EDUCOAST project, funded by EEAGrants (https://www.eeagrants.gov.pt/en/programmes/blue-growth/projects/projects/educoast/) realized three editions of a training course under the theme “The Coastal Zones: a changing world”, specially conceived for teachers of these levels. It´s a hands-on course that aims to provide teachers with the necessary qualifications in coastal related subjects, contributing to updating of their knowledge and equipping them with field and lab-based teaching skills and tools.

The courses were taught at the Portuguese Institute for Sea and Atmosphere (IPMA) Tavira Station, that lies adjacent to the unique nature-based setting of Ria Formosa lagoonal system (South of Portugal). The 25 hours training focused, in four modules: (i) theorical sessions about morphodynamic characteristics of coastal zones, its evolution from the Last Glacial Maximum to the present day, and the prospective scenarios of its future; (ii) Field work on beach and salt marsh study methods guided by a know-how approach, using alternative methodologies that may be easily used and build by students; (iii) Lab treatment of sediment samples, and observation under binocular microscope; (iv) data processing of the obtained results, including altimetric beach profile and estuarine water parameters survey. Following each training course, participants evaluation was based on a final report corresponding to a field guide and subsequent lab protocols oriented for the students. These reports included direct application in school interdisciplinary activities from the classroom to the field work of STEAM. The final survey to assess the effectiveness of these course show that 100% of the teachers consider the overall formation activities excellent. The quality of teachers final outputs show that they are very enthusiastic, motivated, and even passionate about coastal zones study, when they feel their selves comfortable with field and laboratory methodology, as well as data processing. These activities, undoubtably contributed to the improvement of training, interest, and awareness of teachers in teaching their students about coastal geosciences and it also showed a positive outcome for the continuation of these or similar initiatives between schools and the scientific communities.

This is a contribution of the EDUCOAST (EEAGrants, PT-INNOVATION-0067) and EMSO-PT (PINFRA/ 22157/2016) projects.

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020), UIDP/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020).

How to cite: Fatela, F., Drago, T., Silveira, T., Freitas, M. C., Taborda, R., Cascalho, J., Santos, J., and Rosa, M.: The Importance of “Hands-On” Training for Basic and Secondary Level Science Teachers., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11644, https://doi.org/10.5194/egusphere-egu24-11644, 2024.

EGU24-11736 | Posters on site | EOS5.2

If there is a problem, we are the solution 

seyran esen

 

If there is a problem, we are the solution

As a physics teacher for seven years, I have discovered that students learn best by doing and enjoying the subject when they love it. By using the project-based learning (PBL) method, I observed that when they encountered a problem, they made the best use of their knowledge and skills and produced solutions. We discussed the problem of global warming for our world, and throughout the year, we aim to find solutions together as students by researching alternative solutions to solve this problem. Every year, we exhibit our work at the school's science fair and provide the opportunity for other students to examine the work done. In this way, they learn different solutions together. That's why I chose the topic "if there is a problem, we are the solution" for the poster session.

I plan to show examples of the projects my students have done, what problems or challenges they solved, how they worked and eventually developed a product or presentation, and how I guided them in my poster.

How to cite: esen, S.: If there is a problem, we are the solution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11736, https://doi.org/10.5194/egusphere-egu24-11736, 2024.

EGU24-11909 | Posters on site | EOS5.2

An educational strategy to Climate Change integrating three interconnected Perspectives 

Carole Larose, Gérard Vidal, Eric Le Jan, and Charles-Henri Eyraud

The format, illustrations and organization of the 6th assessment reports of the Intergovernmental Panel on Climate Change (IPCC) have changed to fit the evolution of people's perception on Climate Change (CC). Educators face the same changes in the educational world even though CC remains an abstract concept that is challenging for learners to understand. To facilitate the educational process, we propose to tackle simultaneously three complementary perspectives:

  • Climate,
  • Biodiversity,
  • Meteorology.

When carefully limited to a corresponding level of abstraction or difficulty, all the elements of one perspective enhance the understanding of the others, contributing to the consolidation of global knowledge. The pathway to CC is divided into three progressive conceptual leaps that correspond roughly to primary, middle and high school.

In primary school is built the basement of CC conceptual tower. Pupils rely mainly on their feelings and observations as they discover their planet: understanding the latitudinal and altitudinal zonation of "environments" from both biological and climatological perspectives. They perceive the effects of warm/cold dry/wet status of the atmosphere on life.

In middle school, they learn to measure temperatures, precipitations and describe meteorological situations, understand the origin of the climate zonation and the effects of solar radiation; they also learn how to recognize plants and biomes and discover the strong links between weather, seasons and ecological systems. They have a fist contact with risks threatening ecosystems.

In high school, students are initiated into models, come to understand that observations of the past can lead to formalizations and equations that enable to explain past phenomenon and open a window to the future. It's time to understand that the climate has changed in the earth's history, that the atmospheric behavior can be modeled for accurate weather forecast and long term climate projections, and time to understand that the evolution of ecological systems is linked to climate change.

A multidisciplinary approach carries many benefits and provide a transversal consolidation of knowledge, facilitating the understanding of Climate Change. It should maintain and gain a greater place in secondary school programs and teacher's training sessions.

How to cite: Larose, C., Vidal, G., Le Jan, E., and Eyraud, C.-H.: An educational strategy to Climate Change integrating three interconnected Perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11909, https://doi.org/10.5194/egusphere-egu24-11909, 2024.

EGU24-11943 | Posters on site | EOS5.2

InsegnaciETNA 2023 

Carole Larose and Jean-Luc Berenguer

The 2023 edition of the Insegnaci Etna School brings together a number of schools from Eastern Sicily. It aims to teach various aspects of geosciences directly in the field, not only about the nearby Etna volcano, but also about earthquakes, tsunamis, meteorology, geo-environment and the relationships between all these elements and the inhabitants of this area. There were scientific conferences on Etna's eruptions, active faults, earthquakes and ground deformation and also presentations by students from local schools. There were three laboratories where teachers can carry out various practical didactic activities on earthquakes, seismic data analysis, the "Sismobox" experiments, and satellite images analysis. And finally, there was an excursion to the slopes of Etna above Bronte with the support of the Bronte section of the Club Alpino Italiano.

I am going to detail one of these laboratories organised by EduMed an educational observatory supported by the University of the Côte d'Azur in Nice, France.  This observatory and its European partners have extended the scope of their educational activities to all aspects of geosciences and geohazards in the Mediterranean.

In this workshop, the main goal is to allow teachers to analyse data from seismometers stations in Etna’s area.

How to cite: Larose, C. and Berenguer, J.-L.: InsegnaciETNA 2023, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11943, https://doi.org/10.5194/egusphere-egu24-11943, 2024.

EGU24-12128 | Posters on site | EOS5.2

Understanding Climate change within a sustainable school in Community of Madrid (Spain) 

Isabel Lopez Perez, Laura Garcia Sevilla, Ana Martinez García, David Martinez Serrano, and Mariano Leon Colmenarejo

Our high school belongs to the network of Sustainable Schools of the Community of Madrid, so we develop lines of work in all the sustainable development goals (SDGs), with a transversal approach (SDG4 Quality Education) in a general goal named Planet (SDG6 Clean water and sanitation, SDG12 Responsible consumption and production, SDG13 Climate action, SDG14 Life below water and SDG15 Life on land) that we show in our poster.

We offer information of the facilities and the experiences that we do with our students, for example:

• Urban garden: study and caring of species that are more resilient to water scarcity.

• Amphibian pond: to mitigate the effect of loss of these spaces in urban or rural environments due to global warming.

• Insect hotel: refuge for insects in an urban environment.

• Composting of organic waste.

• Regeneration of the garden trees with species better adapted to high temperatures.

• Vertical garden: more efficient irrigation systems for extreme heat or cold (continental climate in the area).

• Bicycle parking to encourage the use of sustainable transport.

• Selective waste collection and recycling at the high school.

• Awareness of reducing energy and water consumption: electricity, heating, etc.

• Adaptation of the buildings to the increase in temperatures in summer.

instagram.com/marquesostenible

https://site.educa.madrid.org/ies.marquesdesantil.colmenarviejo/index.php/ecoescuela

How to cite: Lopez Perez, I., Garcia Sevilla, L., Martinez García, A., Martinez Serrano, D., and Leon Colmenarejo, M.: Understanding Climate change within a sustainable school in Community of Madrid (Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12128, https://doi.org/10.5194/egusphere-egu24-12128, 2024.

EGU24-12559 | Posters on site | EOS5.2

A geoday in our town 

Mª Inmaculada Benito

One of the challenges we secondary school teachers face is the difficulty that younger pupils have in imagining how an outcrop or geological structure has formed or explaining why certain geological hazards occur in certain areas. On the other hand, climate change is often associated with rising temperatures, but not with how it affects geologically related aspects, such as the depletion of aquifers through massive water extraction or subsidence. Presenting a field trip as a geoday can motivate pupils to learn geology.

A geoday, as explained on their website https://geolodia.es, is an outreach event in which geological field trips are conducted guided by expert geologists, free of charge, and open to the general public. The information about the chosen site, which is of great geological interest, allows us to see and understand how the Earth works and helps us to understand the value of our geological heritage and the need to protect it. 

The Baix Empordà region, in the province of Girona, is an area where it is easy to locate rocks from different periods, as well as landforms related to orogenies and distensions. Thus, with a simple explanation of the geological history, 3D representations using QGIS software, topographic and geological maps - students will be able to locate and identify the types of materials present in the town and surrounding area. They will also identify deformations and geological structures and discover how this knowledge has been used to exploit mineral resources. For example, a small outcrop allows them to see a fold, erosion, stratigraphic discontinuity, graded stratification, and a quartz dyke. Here students can apply the concepts seen in class and learn to deduce the series of events that gave rise to this set of structures. The teacher's task will be to provide clues to arrive at a good deductive result.

Geosciences must be understood in a transversal way. Thus, the geoday will be included in a transversal project -in preparation- on the Gavarres mountain range -https://n9.cl/7vshu-, which relates knowledge about forestry or agricultural exploitation according to the type of soil and climate, historical settlement of populations in high areas due to the incidence of floods, or exploitation of mineral deposits in specific areas. Similarly, geological risks can be studied by associating the massive extraction of groundwater and subsidence that can be detected in some areas of the town using online viewers.  Students will have to discuss whether climate change, which we have been experiencing for years, will bring about any noticeable changes in the management of natural resources and risk prevention. Finally, they should think of possible actions to slow down the loss of natural resources in our area.

Subject: Biology and Geology

Grade: 11-14 years old

Duration: 4 hours

Objectives: Students will: learn to identify geological structures, rocks, explain geological history by using topographic and geological maps and 3D printed terrains, and think about climate change and natural resources.

The poster presents photos of this activity.

How to cite: Benito, M. I.: A geoday in our town, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12559, https://doi.org/10.5194/egusphere-egu24-12559, 2024.

EGU24-12636 | Posters on site | EOS5.2

Sustainable development training and outcomes (poster only session) 

Burcu Özdemir

Environmental education is a type of education that aims to increase individuals' environmental awareness, raise awareness on sustainability issues and use natural resources more effectively. Providing environmental education to students provides many advantages and this education has both short-term and long-term outcomes. Some of these outcomes can be listed as sustainable life skills, social responsibility, innovation and solution orientation.

 

In the short term, effects such as students' awareness, application to daily life, social participation, and basic environmental knowledge can be seen. In the long term; Students are expected to see effects such as sustainable living habits, leadership, innovation, environmentally friendly professions, and ecosystem protection.

 

Finally, regarding climate change education in schools, which is this year's theme, it can be used to raise awareness among students about climate change awareness, sustainable energy use, environmental footprint awareness, climate justice, and sustainable use of natural resources. These connections between environmental education and global warming enable individuals to act more consciously, responsibly and effectively against environmental problems. This can contribute to society's greater resilience against major environmental threats such as global warming and climate change.

 

Sustainable development training will be provided within the scope of science course. The training consists of various sub-headings. The duration of the training is determined as 20 lesson hours. Since the science course has 4 lesson hours each week, the training will be completed in a total of 5 weeks. As for the training implementation calendar, the practices will start after the semester break. The educational contents will be created by the researcher by scanning different sources and considering the science curriculum. The age level and readiness levels of the students will also be considered.

 

Teaching activities will be alternated individually or as a group according to the characteristics of the activities. During the creation of the groups, different applications designed by the researcher will be organized in order to enable students to interact with different people in the class. A student-centered approach will be adopted in the teaching process.

 

The aim of the training to be given is to raise awareness about the economical use of water resources, household solid waste materials, household liquid waste materials, recycling and reuse. In addition, local and global environmental problems, endangered living creatures, endangered species, unconscious hunting and conservation of species are among the targets. Finally, students are expected to be informed about energy resources and energy consumption. In line with these goals, it is expected that the cooperative learning of the students will develop in a positive way.

How to cite: Özdemir, B.: Sustainable development training and outcomes (poster only session), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12636, https://doi.org/10.5194/egusphere-egu24-12636, 2024.

EGU24-13038 | Posters on site | EOS5.2

ClimActiC Project  

Carla Freitas, Marco Silva, Eugénia Martins, and Ana Carvalho

           Climate change is a recurring content in Natural Science and Biology/Geology programs. Despite being discussed almost daily in the media, the lack of perception among most students regarding the importance of their role as agents in resolving the problems associated with global warming is notable.

            The relevance of the topic leads to debates and the development of strategies in which the necessary awareness of the evident changes and of changing attitudes occurs, in an attempt to mitigate their consequences. To empower our young citizens to make decisions, the Basic and Secondary School of Macedo de Cavaleiros was part of the ClimActiC project - Citizenship for the Climate – Creating Bridges between Citizenship and Science for Climate Adaptation promoted by 4 Research Centers (Sciences of Education, Psychology, Physics, and Engineering) from the University of Porto. Our school was one of the 8 schools in the North of Portugal that participated in this initiative, which aimed to create spaces for co-creation between young people, scientists, activists, economic agents, and political decision-makers.

             During the 2021/2022 and 2022/2023 academic years, students and teachers of the school subject “A Nossa Terra”, taught by Natural Science teachers of 8th-year classes, administered questionnaires and participated in laboratories climate collaboratives; sessions with partners belonging to the Terras de Trás-os-Montes Intermunicipal Community; Environmental Non-Governmental Organizations and Higher Education Institutions and seminars where they presented the results of research work and awareness-raising actions in the community. Teachers also participated in training and education workshops on climate change through community profiles and research partnerships. During the 2 years of the project our country suffered successive heat waves and a lack of precipitation, with extreme drought situations in several regions. In our opinion this was the turning point in changing awareness about the consequences of climate change. We were able to prove this by analysing the questionnaires (with questions about global warming; agricultural techniques; water saving measures...) created by the students, with supervision from partners, and applied to around a hundred members of the educational community in each year. The impact of the drought was more visible in the second year, with a clear trend toward the need to save water in all age groups. After this diagnosis, co-creation spaces were created where young people could be heard and awareness-raising strategies were outlined. Throughout the year, young people created online games; theatre performances; conducted interviews and videos as community awareness strategies to change attitudes towards climate change, particularly drought. All students involved in the project participated in several actions to reduce the Greenhouse Effect with exhibitions and awareness sessions for younger students on the importance of preserving the native forest, sowing acorns and planting hundreds of native trees in areas destroyed by fires. This was a unique opportunity for more than 200 students to develop teamwork skills and become aware of the importance of changing attitudes towards climate change, internalizing the idea that each person's action can effectively make a difference.

How to cite: Freitas, C., Silva, M., Martins, E., and Carvalho, A.: ClimActiC Project , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13038, https://doi.org/10.5194/egusphere-egu24-13038, 2024.

EGU24-13071 | Posters on site | EOS5.2

Lithium: a problem or a contribution to reducing climate change? 

Sofia Marques and José Belo

Portugal has some of the world's most important lithium reserves. Its exploitation in the country has been the target of public opposition. However, is this an informed opposition?

The work presented was developed with 10th year students within the scope of a DAC (Domain of Curricular Autonomy) involving the disciplines of Biology and Geology and Physics and Chemistry A.

Using lithium, its exploitation and applications as a basis, the aim was to work on essential learning in Physics and Chemistry A, studying the characteristics of metals, and in Biology and Geology, studying the impact of lithium exploitation on ecosystems. The applications of lithium were correlated with its potential to mitigate climate change and its effects on biodiversity.

The students carried out a group research project in class, produced a final product in the form of a powerpoint or using another tool of their choice and finally presented their work to the class in a joint lesson between the two subjects.

The assessment of the final product and presentation was carried out using an assessment rubric previously discussed with the students, resulting in a grade on a scale of 0 to 20 for the written communication and another for the oral communication. The grading was agreed between the Physics and Chemistry A and Biology and Geology teachers, and was integrated into the field of science communication in each of the subjects. There was also a formative assessment of the students' performance during the work and feedback was given by the teachers who accompanied the work. The students also carried out a self- and hetero-assessment of their performance.

How to cite: Marques, S. and Belo, J.: Lithium: a problem or a contribution to reducing climate change?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13071, https://doi.org/10.5194/egusphere-egu24-13071, 2024.

EGU24-13105 | Posters on site | EOS5.2

Raising awareness of global climate change through a school eco-team 

Roman Veselsky

The importance of the topic of global climate change is on the rise, so nowadays in most schools in the world we try to implement topics related to this change into our school curricula. Other means of raising awareness of this topic can be school activities that do not take place directly in the classroom. Undoubtedly, the work of the school's eco team ranks among them.

We founded the eco team at our school two years ago. Since its establishment, our eco team organized many interesting activities for students and teachers of our school, which are connected with concepts such as sustainability, ecology and, last but not least, global climate change.

We are aware that the creation and systematic work of a school eco-team must be well thought out. With this presentation, we want to point out the pitfalls of ecoteam work and introduce colleagues to the concept for managing and cooperation within an ecoteam. We will also present the activities that the eco team can offer to the school and from which both students and teachers can profit in their subjects. The work of a high-quality eco-team certainly has a positive impact on the knowledge, skills and attitudes of pupils in matters of environmental protection.

How to cite: Veselsky, R.: Raising awareness of global climate change through a school eco-team, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13105, https://doi.org/10.5194/egusphere-egu24-13105, 2024.

The issue of climate change is a critical topic.  In particular, for the current generation of school age children, who need to be fully informed with the facts. However, in the English national secondary curriculum climate change may not follow a coherent path as it is currently spread over various subjects. For example, the evidence for climate change placed in the Science curriculum and the impact in Geography.

The argument has been made that the teaching of the causes and impacts of climate change should go beyond a basic understanding of how the climate system works. Within the Science curriculum, climate change is placed into the end of the GCSE Chemistry (ages 14-16) topics within a section on the Earth’s Atmosphere. The allocation of curriculum time within the exam syllabus suggests that no more than three hours teaching time should be used.  Another issue it that as Geography is not compulsory from the age of 14, the impacts are often taught well before the causes and the evidence. 

With the topic of climate change appearing at the end of the Chemistry GCSE curriculum, the implication is that it should be taught at the end of the course in year 11 (age 16).  A major barrier to the delivery is that in England, 32% of schools have insufficient numbers of Chemistry teachers. This shortage of chemistry teachers means there is a strong possibility that a non-specialist will be teaching climate change. Many schools move the topic into year 9 (age 14) as it perceived as easy to teach and easy for the students to understand. However, in the textbooks for example, where it is placed near the end of the book, the topic brings together concepts such as combustion and hydrocarbons.  These are concepts that the students have not yet been taught at the beginning of their GCSE course and so they may not be able to fully understand the evidence and causes for climate change at that stage.

The new Natural History GCSE, which is planned to be offered from 2025, will address some of the issues, but it will be a non-compulsory subject.  It has been suggested that leaving environmental education to non-compulsory subjects and to the final years of secondary education tells the students that it is not important and is not something they need to know.   The other major issue is that schools will only be able to offer it if they have the staff with a background in biology, geography and chemistry.  As there is already a increasing shortage of teachers in these subjects, it would appear unlikely that many schools will be able to introduce it in the near future.

How to cite: Parry, S.: The challenges of teaching climate change within the school science curriculum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13130, https://doi.org/10.5194/egusphere-egu24-13130, 2024.

EGU24-13145 | Posters on site | EOS5.2

Exploring climate change: A graphical journey through time 

Olaia Iglesias

Commonly, efforts to raise students' awareness of global warming often involve impactful videos or images that focus on consequences rather than causes. However, these resources, while realistic, can feel distant from students' daily lives, falling short of instigating the environmental consciousness educators seek. To address this challenge, we propose an alternative approach—utilizing graphs of real data records and their interpretation. This method could be even more impactful than images and allows us to work on various mathematical skills, such as graph description, pattern identification, and trend analysis.

This poster introduces an activity designed to be carried out over two or three sessions of one hour, and utilizing two famous graphs: The Keeling Curve and the Vostok ice core record. The prerequisite concepts needed to carry out the activity are the energy balance and the greenhouse effect. Initially, we must erase the CO2 values from the Y-axis of both graphs.

The Keeling Curve serves as the foundation for introducing concepts such as instrumental data and variation patterns, allowing us to observe the continuous increase in CO2 concentration throughout the entire record. The teacher assumes the role of a skeptic, posing the question: "Can we unequivocally attribute this increase to human activity?" This query prompts students to consider the data needed for certainty, leading them to the realization that preindustrial CO2 concentration data are crucial to answering the question.

Following this, we present the paleoclimatic record of atmospheric CO2 extracted from the Vostok ice core in Antarctica, covering the past 800,000 years. However, we omit the current outlier data (since 1950 to present), leaving it for participants to complete at the conclusion of the activity. During the session, students are guided to understand core concepts through graph interpretation. Upon observing the glacial-interglacial pattern, students are tasked with predicting CO2 fluctuations for the next 100,000 years by extending the graph. After that, they receive the erased CO2 Y-axis values from the graph and are tasked with finding the corresponding CO2 concentration for that specific day to add to the chart. This value entirely disrupts the predicted pattern, and the resulting graph often prompts cognitive dissonance, leaving a lasting impact on students.

This activity enhances scientific understanding of climate change and also emphasizes the seriousness of the current environmental emergency.

 

How to cite: Iglesias, O.: Exploring climate change: A graphical journey through time, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13145, https://doi.org/10.5194/egusphere-egu24-13145, 2024.

This study aims to instill environmental awareness and sustainable consumption habits among 5th-grade gifted students over a three-month period. The primary objective is to investigate the impact of classroom activities on reducing carbon footprints and promoting respectful consumption. The research question guiding the study is whether altering eating habits toward sustainable choices can contribute to minimizing plastic waste and fostering healthier, environmentally friendly lifestyles.

The research begins with students conducting a comprehensive analysis of their classroom and school waste disposal habits, focusing particularly on plastic-packaged food and fruit waste. Using statistical data collected before and after the activities, students question the sustainability of their current consumption patterns and explore alternatives to decrease their carbon footprint. Utilizing tables and graphs, students compare the prevalence of packaged food versus natural fruits before and after the study.

The investigation takes a deeper dive into the sustainability of natural fruits by examining the life cycle of plants, including seed germination, plant growth, and the relationship between flowers and fruits.

The study extends beyond the classroom as students organize a school-wide campaign to raise awareness about the detrimental effects of plastic-packaged food on nature and personal health. Through the design of posters, slogans, and brochures, students advocate for a reduction in plastic consumption and an increase in the consumption of natural fruits and vegetables. The campaign also encourages all students to collect and deposit seeds from consumed fruits and vegetables into seed banks in their respective classrooms.

To further contribute to sustainable practices, students design and implement a microcontroller system using Arduino Uno to germinate the collected seeds. The system, equipped with humidity and heat sensors, ensures optimal conditions for seed germination. This innovative approach not only fosters a hands-on understanding of technology but also emphasizes the practical application of electronics in environmental sustainability.

The research concludes with the students planting the germinated seeds near the school premises, actively engaging in a campaign that promotes the importance of ecological responsibility and sustainable living to decrease the carbon footprint. The findings of this study suggest that integrating practical, student-driven activities into the curriculum can be an effective way to nurture environmentally conscious attitudes and behaviors in young learners.

How to cite: Gökce, A.: Fostering Sustainable Habits: A Classroom Initiative on Reducing Carbon Footprint by Decreasing Plastic and Increasing Seeds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13203, https://doi.org/10.5194/egusphere-egu24-13203, 2024.

EGU24-13234 | ECS | Posters on site | EOS5.2

What future for our beaches? 

Carla Crisostomo and Ana Nunes

Climate change is a global concern of society and, in particular, of the populations living in coastal areas. Individual awareness and collective actions must be promoted to prevent cliffs, slopes and beaches, unique geological formations, transformed into natural beauties, from disappearing in the short term.

With this in mind, our 11th grade Science and Technology students, as part of the disciplines of Physics and Chemistry A and Biology and Geology, of the portuguese curriculum, attended a lecture and visited an exhibition entitled "Do you know where you lay down your towel?" The exhibition focused on the geodiversity of the Municipality of Alcobaça was developed under the anual theme of the Blue Flag Programme, bringing to the local community, the results of a scientific research guided by Prof. Doctor Paulo Trincão, Director of the Science Museum of the University of Coimbra.

Following this visit, the 26 students, working in groups of 3 to 4 elements, collaboratively created scientific posters, interconnecting key learnings from Physics and Geology.

Physics explains the fall of debris from cliffs by the analysis of real rectilinear movements of free fall or on inclined planes. By rechearching and data collecting on the position of the debris in cliffs (considering a given reference frame and the inclination of the geological formations, as well as the forces to which they are subjected), Students realise the necessary precautions we must take, when choosing the right spot to lay down our towel or when walking along the cliffs.

On the other hand, Geology explains geological deformations based on the mobility of the lithosphere and the behaviour of the materials we learn to identify at local cliffs and landscapes.

The geological context of São Martinho do Porto, located in the municipality of Alcobaça, was the learning scenario, linking the curriculum to reality.

Following the scientific posters task, students will carry out a case study on coastal intervention, considering the vulnerability scenarios for the region and climate change. Using an application,[1] developed by researchers from the Faculty of Sciences in University of Lisbon, Students will discuss, in the form of Role-play, as local decision-makers in 2050, about prevention and mitigation strategies to climate change in the near future (eg. Heavy engineering works, dune protection, tourist pressure on local coastal ecossistems, walkways construction, building permits, etc).

Students will presente their work, at the end of the school year, to the educational community and municipality council.

Please note that students have laptops provided under the government program PADDE[2].


[1]Antunes C., Rocha C. e Catita C. (2017) Cenários de Subida do Nível do mar para Portugal Continental. In: www.snmportugal.pt, IDL/FCUL.

[2]The Action Plan for the Digital Development of Schools (PADDE) is based on the conceptual framework of the guiding documents developed by the European Commission, namely  DigCompEdu and  DigCompOrg. In this way, the areas of intervention of the PADDE will focus on the different domains of school organization in the field of digital technologies: Professional Engagement, Teaching and Learning, Learning Assessment, Continuous Professional Development and Leadership. Plan - Digital School (agrupspc.pt) 

How to cite: Crisostomo, C. and Nunes, A.: What future for our beaches?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13234, https://doi.org/10.5194/egusphere-egu24-13234, 2024.

EGU24-13443 | Posters on site | EOS5.2

Do you hear the noise pollution? 

Natalija Budinski

Petro Kuzmjak school is a small school in rural area and it is attended by 500 students from 7 to 18 years old and it is always something going on. Last yea,r in April, we have been part of one international project organized by Serbian Center for Science Promotion where students explored the level of noise pollution in our school.

Noise pollution is excessive, undesirable, or disturbing noise that interferes with normal activities and disrupt the balance of human or animal life. It is considered as a form of environmental pollution and some of the source of noise pollutions are: traffic, industry, aircrafts, public events, or household appliances. Constant exposure to noise can cause health issues, sleep disturbance, reduce quality of life, but also disrupt wildlife habitats, affecting animal communication, migration patterns, and overall well-being.

Implementation of noise regulations, sound barriers, and development of quieter technologies potentially mitigate noise pollution. To diminish noise pollution we need to raise public awareness and involve community, and that why is the project that we conducted in the school related to noise pollution has a great importance.

The role of researchers was taken by our eight grade students (15 years) who measured the level of noise in our school with the help of NOIXAPP application in the scope of their mathematical lessons. First step was introduction of application and setting the rules of the use of phone in the school.  NOIXAPP is an application developed by the National Institute of Oceanography and Applied Geophysics and it measures acoustic pollution in urban environments. The application uses mobile phone microphones to collect data on urban background noise and sends it to a platform that allows a full picture of the acoustic space of an area to be reconstructed. The solution is based on mobile application software, where it is possible to record, calculate the average values ​​of the sound pressure level. Georeferenced data is transferred and anonymized, integrated, validated and mapped on an open data web portal. Beside the measurement itself, students learned about noise pollution, which is one of the least discussed, although it is very important for people's health.

With this measurement, students evaluated the level of noise in our school. It was an additional motivation for students to take part in the research and to find out if our school is a pleasant and safe place in terms of noise. Students measured the noise in various parts of our school to get a more realistic picture. Measurements were made in the hall, school yard, corridor, hallway, etc. The results were presented graphically, and it was a way to connect collected real life data with mathematical knowledge.

How to cite: Budinski, N.: Do you hear the noise pollution?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13443, https://doi.org/10.5194/egusphere-egu24-13443, 2024.

EGU24-14601 | ECS | Posters on site | EOS5.2

The Green Curriculum To Fight Against Climate Change 

Hayriye Olğun

In the socioeconomically challenged Narlıdere Boarding Middle School, a project addressing environmental challenges was implemented. This self-sufficient model engaged students and parents in decision-making, focusing on UN Sustainable Development Goals. In this case, I improved a Green curriculum, including some implementations towards school and science lessons. These activities were implemented during one school year for 6th, 7th, and 8th-grade students. Here are the key concepts and applications of these implementations:

Waste management at school was the main goal. Within this scope, recycling bins were placed in the school based on the idea that not all waste is garbage. The recyclable waste was sent to the nearby Bitlis Solid Waste Management Facility (BIKA).

Domestic waste generated in the school canteen was evaluated as compost, and greenery was grown with the produced compost.

Soap was made from the accumulated waste oil in the school canteen, and the soaps produced were used in the school. In this context, students brought the waste oil accumulated in their homes to the waste oil collection point at the school to be evaluated in the same context.

An educational trip to BIKA for waste management and recycling was organized. Scientific knowledge was provided to the students in this field.

We conducted an analysis of local water sources and mapped them with students.

To be aware of our environment, we created a plant map of our local area using mobile applications. We collected rocks, classified them, and made an exhibition from them.

We also built an insect hotel to raise awareness of the little animals that we share our lives with. I aimed to make my students aware of nature.

The project notably increased environmental initiatives, aided national exhibition participation, and improved students' expressive abilities. Positive feedback and student engagement laid the foundation for broader project dissemination. This study highlights the significance of green skills in combating climate change for a sustainable future.Steps aligned with the Sustainable Development Goals enhanced students' environmental awareness and waste perception. Soap production from waste oil contributed to the economy and improved students' skills. There was a noticeable increase in environmental projects at school. Educational activities facilitated students' participation in national exhibitions. The science fair strengthened students' expression skills. Positive feedback throughout the process laid the groundwork for wider project dissemination. Embracing sustainable steps became the primary motivation for students. This study can be seen as a valuable step towards a sustainable future, emphasizing the importance of green skills in fostering awareness regarding climate change.

How to cite: Olğun, H.: The Green Curriculum To Fight Against Climate Change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14601, https://doi.org/10.5194/egusphere-egu24-14601, 2024.

EGU24-14665 | ECS | Posters on site | EOS5.2

Creating School Seismology Labs For the Development of Students’ 

Cristina Simionescu

Creating School Seismology Labs For the Development of Students’

Cristina Simionescu1,2, Dragos Tataru1, Eduard Nastase1, Bogdan Cerbu1, Adina Vanciu-Rau1 & SEISMOLAB project team

 

1National Institute for Earth Physics, Romania

2University of Bucharest, Faculty of Geology and Geophysics

 

Using the topic of seismology in school education allows teachers and students to dive into scientific topics and concepts while practicing and improving intellectual and soft skills (i.e. science understanding and knowledge, scientific reasoning, computational thinking and skills, geospatial understanding, collaborative problem solving, creativity, critical thinking, communication, etc.). 

Throughout the Erasmus Plus project, SEISMOLAB - Creating School Seismology Labs For the Development of Students’, over 2000 students and 100 teachers in 5 countries benefited from activities that reinforced their interest in science and were offered access to content tools and services for personalized science learning and citizen science.

One of the aims of this project is to bring together seismologists, pedagogues, curriculum developers, local authorities, advanced educational developers, and schools to join forces during the implementation and co-design, develop and validate an innovative professional development program for supporting the in-service training of teachers on topics related, but not limited to seismology education. 

In 2023 students had the opportunity to work with scientific concepts, handle and study specific seismological equipment and participate in meaningful and motivating science inquiry activities on earthquake disaster mitigation. They were guided to use concepts such as energy transfer, wave properties, and resonance to understand elementary models of earthquakes' causes and effects.

Teachers participated in a specially designed training program that supported them in the establishment and implementation of the SEISMO-Labs, including training on innovative methods such as inquiry-based and experiential learning and were given the specially created material - Seismo-Lab Demonstrators (educational scenarios for seismology). They were then able to develop “bottom-up” STEAM curricula, related to seismology, for their schools. 

In Romania, we organized 5 regional multiplier events in order to achieve a greater impact by accessing a more significant number of beneficiaries, national coverage, and the chance for teachers from rural areas to travel to participate in the workshops. From the 152 participants from over 60 school units, we selected 20 schools that were further engaged in the SEISMO-Lab network. The chosen schools also joined the Romanian Educational Seismic Network and responsible teachers participated in workshops and online support meetings that offered them the knowledge to implement seismology innovative activities with their students. Also, 20 semi-professional Raspberry seismometers were installed in the selected school units, allowing teachers to use data from the international Raspberry Shake network, in their lessons. 

Teachers received training on the approach and the pedagogical methodologies and they participated in an evaluation activity for mapping and monitoring the impact and effectiveness, both quantitatively and qualitatively, at the student, teacher, and school/institution level of the SEISMO-Labs.

 

ACKNOWLEDGEMENTS

This work was done in the framework of the project “Seismo-Lab” which has been funded with support from the European Commission under the Erasmus+ programme (Grant agreement number 2021-1-EL01-KA220-SCH-000032578).

How to cite: Simionescu, C.: Creating School Seismology Labs For the Development of Students’, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14665, https://doi.org/10.5194/egusphere-egu24-14665, 2024.

EGU24-15679 | Posters on site | EOS5.2

Collect and analyze data to make informed choices 

Elena Rizzi

Good data collection is among the first phases of a correct scientific method. During the 2023/2024 school year, in two classes of the "Ilaria Alpi" secondary school in Chiavari (Genoa, Italy), we collected data on the consumption of water, food, energy and on the methods of travel of the pupils and their families. The objective was to understand the extent and type of consumption, with the aim of proposing positive daily actions to reduce consumption.

We created questionnaires and collected data. We then represented the data with different graphical methods and discussed them. We then moved on to the discussion and the proposal of actions, which we disseminated within our school and, in the case of mobility, to the administrators of our Municipality.

How to cite: Rizzi, E.: Collect and analyze data to make informed choices, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15679, https://doi.org/10.5194/egusphere-egu24-15679, 2024.

EGU24-17091 | Posters on site | EOS5.2

GEO-Academy: GEO-Hub for Teachers in Europe 

Henry Boeree, Annalisa Donati, Alkyoni Baglatzi, Afroditi Riga, Gustavo A. Rojas, Nikolaus Albrecht, Seda Özdemir-Fritz, Gina P. Correia, Loukas Katikas, Angelos Lazoudis, Alexandra Moshou, Marinos Kavouras, and Maria Bezerianou

GEO-Academy is an Erasmus+ Teachers Academies initiative developing a blended competence-based network for teaching sustainable development using innovative geospatial technologies and modern pedagogical methodologies. Over the course of three years, GEO-Academy will collaborate to create a range of teaching materials and training resources, and also establish national GEO-Hubs connecting an international network of teachers across Europe. The overarching goal is to provide training activities to support teachers both in their professional development and learning as well as in educating the next generation of European citizens on sustainable development topics. The project draws from geospatial, climate science, and education expertise from across Europe (Austria, Bulgaria, Cyprus, France, Greece, Portugal, and Sweden).

Green, digital, and spatial competences based on highlighted skill needs in “Education for Sustainable Development (ESD)” will be addressed and developed. The project is aimed to establish evidence-based pedagogical models, along with a range of training activities and resources utilising cutting edge geo-technologies, such as Geographic Information Systems (GIS), Global Positioning Systems (GPS), Remote Sensing (RS) and Earth Observation (EO), data acquisition and processing, image analysis, and related location-based technologies. Materials and activities will be structured along five GEO-Concepts, designed to meet curricular demands and skill gaps. These GEO-Concepts are: (a) Cartography and development of spatial thinking skills, (b) Geographic Information Systems (GIS), Tools and techniques for Earth Sciences (c) Remote Sensing (RS), Earth Observation (EO) and Satellite applications (d) Visualisation and synthesis of information through the use of mapping technologies – Map Storytelling, and (e) STEAM education and robotics, coding for Urban Sustainability.

Considering teachers’ pivotal role in the whole process, the training material will be developed with small groups of teachers to ensure the highest effectiveness and relevance and will then be scaled up to larger audiences. The establishment of GEO-Hubs as school-based nodes will form a large community of practice, coordinated at the national level and linked at the project level under the GEOBSERVE Platform. This central hub, developed in seven languages, will host materials, training activities and serve as a central community hub for teachers to share examples and best practices. GEO-Hubs will also receive a suite of materials, including sensors for Arduino/Raspberry Pi/micro:bit, for incorporating them into practical projects with students.

Here we provide an overview of the project, explain its methodology and aims, and present the GEOBSERVE Platform, set to be launched in March 2024. Teachers present will be guided through how to connect to the platform and shown the possibilities of engaging through example materials. Finally, they will be invited to join the project as a GEO-Hub with their school/students, for which the process and benefits will be explained.

How to cite: Boeree, H., Donati, A., Baglatzi, A., Riga, A., Rojas, G. A., Albrecht, N., Özdemir-Fritz, S., Correia, G. P., Katikas, L., Lazoudis, A., Moshou, A., Kavouras, M., and Bezerianou, M.: GEO-Academy: GEO-Hub for Teachers in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17091, https://doi.org/10.5194/egusphere-egu24-17091, 2024.

EGU24-17945 | ECS | Posters on site | EOS5.2

Education for sustainable development within the geography curriculum 

Laura Cristea

In the ever-changing world of education, the swift progress of technology requires a transformation in teaching methods to meet the evolving needs of learners. The significance of open education resources becomes crucial in such a scenario. At the same time, there is an increasing acknowledgment that more educated citizens play a vital role in reshaping the education paradigm towards sustainable development. There is a need therefore to adapt our educational systems. This involves embracing formal, non-formal, and informal approaches facilitated by Open Schooling and Open Learning activities. The ultimate objective is to nurture a lifelong learning process that corresponds to the dynamic demands of our changing society, enabling individuals to actively contribute to sustainable development throughout their lives.

Geography, with its interdisciplinary nature, offers a comprehensive perspective through which students can grasp the interconnectedness of environmental, social, and economic aspects. This presentation seeks to investigate how integrating geography into Open Learning can enrich students' holistic comprehension of sustainable development.

This presentation offers a perspective of  how the integration of geography within Open Learning environments for secondary schools can effectively contribute to Education for Sustainable Development, aiming to equip students to address contemporary global challenges and cultivate a lifelong commitment to sustainability.

How to cite: Cristea, L.: Education for sustainable development within the geography curriculum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17945, https://doi.org/10.5194/egusphere-egu24-17945, 2024.

EGU24-18773 | Posters on site | EOS5.2

Climademy: The Erasmus+ Climate Change Teachers’ Academy  

Maria Kanakidou, Nikos Kalivitis, Olivia Levrini, Giulia Tasquier, Laura Riuttanen, Mihalis Vrekoussis, Thalia Tsaknia, Athina Ginoudi, Giorgia Bellentani, Dimitris Stavrou, Emily Michailidi, Marius Dan, Jari Lavonen, Katja Lauri, Taina Ruuskanen, Annette Ladstätter-Weißenmayer, Emmanouil Zouraris, Simon Bittner, and Ioannis Pavlidis

Climademy is the Erasmus+ Climate Change Teachers’ Academy, which aims to provide a comprehensive framework where educators can learn how to teach the next generation of European citizens about climate change drivers, impacts and mitigation and adaptation measures, using an efficient methodology. Climademy aims to create a network of initial training and professional development organizations that will offer formal and non-formal education and training opportunities for in-service and training teachers.  The network supports and provides the necessary infrastructure, digital tools and resources, and promotes the educators’ climate competences.

In Climademy four national hubs have been established to offer training activities for teachers, with specific foci driven by the regional particularities: the Greek hub in the Mediterranean, focusing on the chemistry of the atmosphere, the Finnish hub in the Arctic, focusing on atmospheric physics, the German hub in continental Europe, focusing on satellite observations and modelling tools for climate change projections, and the Italian hub on the transformation of all information to knowledge and awareness through the environmental education process. The CLAUDI digital platform is at the heart of Climademy and hosts all educational material, online courses, provides links to open data, and supports the community forum. Material is available in English and in the national language inside each national hub areas. CLAUDI is openly available after registration and can be assessed through the Climademy website (https://climademy.eu)  and directly through http://claudi.chemistry.uoc.gr.

The Climademy activities carried out in the hubs have been enriched with a «pedagogical identity» through the development of a model to convey the message that the teachers do not only have to teach new scientific content, but also use new pedagogical approaches. Additionally, a Climademy competence framework was developed, combining the GreenComp and the University of Helsinki’s Competence Framework for Climate Change.

The first teachers who participated in the training activities also served as co-developers of the content and the methodology. The following 100 teachers to participate in the Climademy training activities have been recruited from the 4 countries.

How to cite: Kanakidou, M., Kalivitis, N., Levrini, O., Tasquier, G., Riuttanen, L., Vrekoussis, M., Tsaknia, T., Ginoudi, A., Bellentani, G., Stavrou, D., Michailidi, E., Dan, M., Lavonen, J., Lauri, K., Ruuskanen, T., Ladstätter-Weißenmayer, A., Zouraris, E., Bittner, S., and Pavlidis, I.: Climademy: The Erasmus+ Climate Change Teachers’ Academy , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18773, https://doi.org/10.5194/egusphere-egu24-18773, 2024.

EGU24-19968 | ECS | Posters on site | EOS5.2

SpaceEDUnity: Introducing natural hazards to younger generations utilizing advanced technologies 

Eleftherios Theodoropoulos, Stavroula Sigourou, Foteini Salta, Eleni Loulli, Marianna Hadjichristodoulou, Christiana Papoutsa, and Charalampos (Haris) Kontoes

Natural hazards constitute significant risks for both the society and the environment. Thus, it is essential to emphasize in educating younger generations against the consequences of climate change. Addressing this crucial need, the SpaceEDUnity/Erasmus+ project*, was launched in May 2023. This innovative educational initiative strategically utilizes remote sensing and geoinformatics to provide a learning experience regarding natural hazards. SpaceEDUnity targets secondary education school students and teachers, having already reached over 700 students in Greece and Cyprus. The project's core lies in its approach to tailor content specifically to the geographical areas of the participating schools. This strategy focuses on natural disasters relevant to each region, significantly enhancing student engagement and understanding. The project's methodology integrates interactive presentations, quizzes and hands-on workshops. These workshops are particularly focused on applications, such as the monitoring of wildfires and mapping of flooded areas utilizing tools like the EO Browser, GIS, and SNAP software. This approach not only introduces students to the technological aspects of studying natural hazards, but also equips them with practical skills in satellite data processing. A key component of SpaceEDUnity is the development of extensive, user-friendly tutorials for teachers. The purpose of this educational material is to give teachers the opportunity to replicate each activity easily in classroom and therefore ensure sustainability and long-term impact of the project. By empowering teachers with these tools, SpaceEDUnity fosters a continuous learning environment, enhancing the resilience of local communities against natural disasters. SpaceEDUnity stands as a model for integrating science into school curriculums by focusing on localized natural hazards and providing hands-on experience with cutting-edge technologies. In addition, the project not only increases awareness of climate change, but also actively involves young citizens in the protection of their communities.

*SpaceEDUnity is co-funded by the European Union

How to cite: Theodoropoulos, E., Sigourou, S., Salta, F., Loulli, E., Hadjichristodoulou, M., Papoutsa, C., and Kontoes, C. (.: SpaceEDUnity: Introducing natural hazards to younger generations utilizing advanced technologies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19968, https://doi.org/10.5194/egusphere-egu24-19968, 2024.

EGU24-20057 | ECS | Posters on site | EOS5.2

Aeolus Satellite: A Breath of Fresh Air for Climate Change Education 

Panagiota Asimakopoulou, Ioanna Tsikoudi, Maria Tsichla, Panagiotis Nastos, Clara Cruz Niggebrugge, Maurane Gisiger, Thorsten Fehr, and Tommaso Parrinello

The field of Earth Observation (EO) is perpetually evolving attaining remarkable advancements that improve our understanding of the underlying physical phenomena behind climate change. One of the latest EO advancements is the Aeolus mission of the European Space Agency (ESA). Aeolus is the first satellite to deploy a Doppler wind lidar instrument, utilising laser technology to accurately measure wind profiles. This innovation significantly improved weather forecasting, atmospheric modeling, and climate research, enabling better predictions of extreme weather events and advancing our knowledge of atmospheric circulation patterns.

By following the rapid advancements in Earth Observation (EO), climate change and sustainability education has a promising opportunity to capitalize on these developments for the mutual benefit of EO and climate literacy. In this context, we designed an innovative educational programme, the "AeolusEdu[1]", with the support of the ESA Education office and the Greek ESERO office. We implemented AeolusEdu during the Aeolus Science Conference in Rhodes (May 2023), which attracted 150 6th grade students from the 1st, 12th, and 13th Primary Schools of Rhodes.

Throughout the program, students were engaged in an interactive learning experience, delving into the factors influencing winds, understanding the underlying physical principles of atmospheric circulation, and exploring the "Doppler Wind Lidar" technology employed for space-based wind monitoring through thoughtfully designed hands-on experiments. Additionally, students were able to interact with both historic and  modern ground-based instruments used in wind monitoring. At the program's conclusion, students had the unique opportunity to meet some of the world’s leading space and  weather experts involved in the Aeolus mission and discuss, in a notably extended Q&A session, their work and the motivations driving their careers as scientists.

According to the feedback received from participating teachers and students and the overwhelming applause and farewell scientists received, AeolusEdu admittedly captivated students and ignited their curiosity for EO and Earth System Science (see relevant ESA article[2]). The implementation of AeolusEdu illustrated that young school students can not only comprehend the fundamental concepts and principles behind atmospheric circulation, extreme weather events, and groundbreaking satellite technology but also find them genuinely exciting. The success of the first AeolusEdu pilot programme inspires us for future development of freely available EO-based information material for all teachers.


[1] https://www.aeolus2023.org/education

[2] https://www.esa.int/Education/Students_blown_away_by_Aeolus 

 

 

How to cite: Asimakopoulou, P., Tsikoudi, I., Tsichla, M., Nastos, P., Cruz Niggebrugge, C., Gisiger, M., Fehr, T., and Parrinello, T.: Aeolus Satellite: A Breath of Fresh Air for Climate Change Education, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20057, https://doi.org/10.5194/egusphere-egu24-20057, 2024.

EGU24-20061 | Posters on site | EOS5.2

Ecological transition, what does it really mean? 

Claretta Christille, Marie Claire Courthod, and Susanna Occhipinti

Ecological transition is a process that aims to initiate a new economic, cultural and social system that will make human societies more sustainable. 
Important tool for the implementation of this transition is the United Nations 2030 Agenda, which sets out in detail the urgent ecological measures required to combat climate change and protect the environment; these include the reduction of greenhouse gas emissions, complete decarbonization, the adoption of advanced technological solutions and the use of renewable sources. Schools are called upon to raise students' awareness of these issues.
As part of teacher training, an experimental course was undertaken with experimental activities to reflect on some of the causes and consequences of environmental warming in order to gain a greater awareness of how seemingly disjointed phenomena are actually interdependent within the Earth's complex ecosystem. The course provided an opportunity to experiment with different teaching approaches including IBSE (inquiry-based science education).

How to cite: Christille, C., Courthod, M. C., and Occhipinti, S.: Ecological transition, what does it really mean?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20061, https://doi.org/10.5194/egusphere-egu24-20061, 2024.

EGU24-1188 | ECS | Posters on site | ERE1.3

Stone decay in the underwater environment: examples from Mediterranean archaeological sites 

Luigi Germinario, Isabella Moro, Fabio Crocetta, Patrizia Tomasin, Emanuela Moschin, Franca Cibecchini, Stella Demesticha, Enrico Gallocchio, Judith Gatt, and Claudio Mazzoli

This contribution presents one of the research directions of the project WATERISKULT (https://wateriskult.geoscienze.unipd.it), involving the decay of underwater archaeological sites, in particular of submerged structures and artifacts made of stone. The pilot sites of this project are located in the western, central, and eastern Mediterranean Sea, and include the Roman complex of Baia in Italy, the Hellenistic harbor of Amathus in Cyprus, and the Roman port structures of Anse des Laurons in France. Diving and sampling campaigns were organized therein in the first half of 2023, and were followed by laboratory analyses that explored the state of conservation of different archaeological stone materials (limestones, marbles, tuffs, sandstones, etc.). Microscopic techniques were applied for investigating the stone composition, biofouling, and chemical alteration, observing the surface and stratigraphic features of the sampled materials. Moreover, 3D morphometric techniques allowed for the quantification of the physical damage of the archaeological surfaces. The analytical results were combined with site-specific topographic information collected during the dives and environmental data provided by seawater monitoring agencies. In that way, the interaction between ancient materials and the underwater environment was explored, discussing the relationship between deterioration and a range of different stone and seawater properties.

How to cite: Germinario, L., Moro, I., Crocetta, F., Tomasin, P., Moschin, E., Cibecchini, F., Demesticha, S., Gallocchio, E., Gatt, J., and Mazzoli, C.: Stone decay in the underwater environment: examples from Mediterranean archaeological sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1188, https://doi.org/10.5194/egusphere-egu24-1188, 2024.

EGU24-1312 | ECS | Orals | ERE1.3

Thermo-hygric weathering of Carrara Gioia marble monitored with Nonlinear Resonant Ultrasound Spectroscopy 

Marie-Laure Chavazas, Philippe Bromblet, Jérémie Berthonneau, and Cédric Payan

Carrara marble is widely used, in buildings and sculptures, in ancient and recent works. Yet, it can develop deteriorations over time, such as bowing, cracks, expansion, reduction of mechanical strength, when it is exposed to environmental conditions. Previous studies have shown that these deteriorations can result from exposure to temperature variations, and that they can be enhanced by additional humidity variations. However, the mechanisms at stake at the microstructure level are still not well-understood.

This work is therefore focused on the understanding of the degradation mechanisms induced on marble by temperature and humidity fluctuations. Laboratory experiments are carried out on Carrara marble samples first heated at different temperatures and then undergoing thermal, hygric, and thermo-hygric cycles. The temperature investigated during cycling belongs to the mild temperature range (40 – 105 °C) in order to simulate outdoor exposure conditions.

The mechanical state of Carrara marble samples is non-destructively monitored during the cycles with Nonlinear Resonant Ultrasound Spectroscopy (NRUS), through the evolution of resonant frequency and of nonclassical nonlinearity. The first parameter is related to sample stiffness, and the latter is highly sensitive to any change occurring at the microstructure level (micro cracks, friction, capillary effects, etc.). Additionally, microstructural characterization (mercury intrusion porosimetry, optical microscope and SEM observations) is made on marble samples to link the evolution of the NRUS parameters to the changes occurring in marble microstructure.

The impact of heating on marble is first studied for temperatures between 40 and 250 °C, and the progressive granular decohesion of the material is monitored with NRUS. Marble state is also characterized during adsorption-desorption cycles, which shows that relative humidity fluctuations alone do not induce permanent damage. Finally, the influence of thermal cycling at mild temperatures and the impact of combined temperature and relative humidity cycling are studied with NRUS.

How to cite: Chavazas, M.-L., Bromblet, P., Berthonneau, J., and Payan, C.: Thermo-hygric weathering of Carrara Gioia marble monitored with Nonlinear Resonant Ultrasound Spectroscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1312, https://doi.org/10.5194/egusphere-egu24-1312, 2024.

EGU24-2818 | Posters on site | ERE1.3

A multidisciplinary approach for the diagnostics of the stone building materials of architectural structures 

Giuseppe Casula, Silvana Fais, Francesco Cuccuru, Maria Giovanna Bianchi, Paola Ligas, and Luciano Cannas

The integrated use of non-destructive geomatic and geophysical techniques such as close-range digital photogrammetry, laser scanner techniques, thermography, sonic and ultrasonic methods, resistivity, etc... for the diagnostics of the stone building materials of architectural structures has become increasingly dependent on the integration of different disciplines of applied research. As is well known many historic monuments are characterized by severe damage due to temporal degradation, problems caused by differential settlements of the foundations and various types of natural hazards. Therefore it is of great interest to test and develop effective, integrated non invasive procedures to detect the conservation state of the building materials of historic structures, and identify and prevent their potential vulnerability in order to preserve their intrinsic characteristics for a long time.

For extensive applications, as well as for investigations on monuments or large architectural elements, scanning and digital high resolution images are particularly useful, thanks to their limited cost, high production and relatively simple reproducibility of the tests. These techniques give useful information on the shallow conditions of the investigated materials. Geophysical techniques such as the ultrasonic and resistivity methods are non-invasive and are considered the most appropriate to evaluate the internal structure and assess the quality of the stone materials of the architectural heritage.

This paper presents an integrated approach that combines advanced geomatic survey procedures, such as close-range photogrammetry (CRP) based on high resolution images and Terrestrial Laser Scanner (TLS) techniques with a few geophysical techniques such as the ultrasonic and resistivity ones in order to test the effectiveness of the integrated approach in providing an effective diagnosis of stone building materials in the Basilica di San Saturnino (Cagliari – Italy). This Basilica is the oldest monument of the town of Cagliari (Italy) and represents an interesting synthesis of different construction techniques with heterogeneous stone materials of different origins. CRP and TLS were applied to the investigated elements with the aim of obtaining a natural colour texturized 2D-3D model with a calibrated scale and coordinates. The geometrical anomaly and reflectivity maps derived from the data of the CRP-TLS survey show the presence of some anomalies worthy of attention, but they were referred to the shallow materials. A further investigation on site using the ultrasonic pulse velocity (UPV) and electrical resistivity techniques were performed to investigate the materials in depth. The results of the CRP and TLS techniques allowed the best design of the ultrasonic and electrical techniques and also proved to be useful in the data interpretation phase.

Acknowledgements: The authors would like to thank the Ministero della Cultura - DIREZIONE GENERALE MUSEI - DIREZIONE REGIONALE MUSEI SARDEGNA (ITALY) for their kind permission to work on the San Saturnino Basilica.

How to cite: Casula, G., Fais, S., Cuccuru, F., Bianchi, M. G., Ligas, P., and Cannas, L.: A multidisciplinary approach for the diagnostics of the stone building materials of architectural structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2818, https://doi.org/10.5194/egusphere-egu24-2818, 2024.

EGU24-4340 | ECS | Posters on site | ERE1.3

Black Crusts as Geochemical Archives: Preliminary Results from Antwerp, Belgium 

Sofia Deboli, Silke Visschers, Blanca Astray Uceda, Adela Šípková, Katrin Wilhelm, and Tim De Kock

Interaction between the historical built environment and environmental pollution can result in the accumulation of weathering crust on building material surfaces. A subgroup of weathering crusts are black crusts, which consist of gypsum layers formed by sulfation on calcium-rich substrates. These crusts occur more often and are more pronounced in polluted environments such as urban settings. As a result, they can incorporate particulate matter, polyaromatic hydrocarbons, and heavy metals. Black crusts can act as non-selective passive samplers, accumulating distinct layers of air contaminants depending on historical pollution levels.
Existing studies provide only coarse-resolution reconstruction of pollution, differentiating solely between inner and outer crust layers. Just a few explore the correlation between different periods of exposure to pollution and the variation of the composition of these crusts. This study focuses on the stratigraphic analysis of black crusts to assess their potential as a reliable geochemical archive for the reconstruction of past anthropogenic pollution within urban settings.
Following technological developments in transportation and combustion, the composition of pollutants in the atmosphere has evolved over the centuries, likely reflected within weathering crusts where pollutants accumulate. For the identification of past air pollution signatures, lead can serve as a useful tracer due to its isotopes, their presence is the result of different historical pollution sources. Variations in the ratios of lead isotopes provide a means to attribute and differentiate among these pollution sources. For lead isotope analysis, high-resolution laser ablation mass spectrometry will be used to distinguish between 206Pb, 207Pb, and 208Pb.
This study deepens the understanding of localized pollution levels in urban settings, allowing the implementation of conservation interventions including cleaning and consolidation, strategies to mitigate the impact on human health, local ecosystems, and biodiversity, and to support urban planning.

How to cite: Deboli, S., Visschers, S., Astray Uceda, B., Šípková, A., Wilhelm, K., and De Kock, T.: Black Crusts as Geochemical Archives: Preliminary Results from Antwerp, Belgium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4340, https://doi.org/10.5194/egusphere-egu24-4340, 2024.

EGU24-7547 | ECS | Posters on site | ERE1.3

Biodeterioration of historical buildings and sites in north of Lake Tana, Ethiopia: a preliminary investigation 

Ayenew Demssie, Tim De Kock, Natalia Ortega-Saez, and Blen Gemeda

Lake Tana is the largest lake in Ethiopia and the source of the Blue Nile. The lake is protected as a natural heritage site. It is surrounded by wetlands that provide a sanctuary to a diverse set of flora and fauna some of which are endemic to the region. It is also a culturally significant area. Surrounding the lake and on the islands are found tens of stone built monasteries, churches, bridges and palaces built in the Gondarine period (17th and 18th Century AD) and earlier. However, these buildings are subjected to biological growth in many different types that cause  discoloration and  degradation. The short and intense rainy season contributes to the nature, diversity and intensity of biological colonization of these stone structures. Biofilms, fungi, mosses, lichen and higher plants can be observed, while also small animals such as mites and rodents are agents of bio-deteriorative process. While micro-organisms alter the visual appearance, roots of higher plants are responsible for more severe physical decay on the site and building level, increasing also the impact of moisture-related weathering in decayed locations. However, micro-organisms can also alter the surface properties of materials, like water absorption and retention, and it is currently not well understood to what extend these contribute to the observed forms of degradation, like chipping, fissuring, cracking, etc. 

This poster aims to address some of the key challenges of managing cultural heritage sites found in a complex, evolving and vulnerable ecosystem, i.e. Lake Tana. Factors such as intense rainfall, humidity, the state of the structures, intensification of agriculture and the perspectives of local communities and stakeholders will be evaluated.

How to cite: Demssie, A., De Kock, T., Ortega-Saez, N., and Gemeda, B.: Biodeterioration of historical buildings and sites in north of Lake Tana, Ethiopia: a preliminary investigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7547, https://doi.org/10.5194/egusphere-egu24-7547, 2024.

EGU24-10672 | Orals | ERE1.3

Creating a holistic view on the situation of historic parks and gardens 

Jürgen Moßgraber, Tobias Hellmund, Jürgen Reuter, Lola Kotova, and Katharina Matheja

Extreme weather events due to climate change not only affect nature, but can also impact historical buildings, collections, and historic parks and gardens. Assessing the extent to which cultural heritage is threatened by such weather and climate events is an interdisciplinary task that requires the collaboration of experts from heritage preservation and restoration, climate research, natural and engineering sciences, social and economic sciences, landscape architecture, informatics, and more.

Due to this complexity and the abundance of available information, modern IT tools are crucial in explaining the condition of cultural heritage sites to decision-makers and providing insights into future developments. To get a better understanding of the situation of historic parks and gardens, a knowledge platform can offer map-based visualization of data. The biggest challenge in developing such a platform was the integration and processing of relevant data. Due to the interdisciplinary nature of the field and the heterogeneity of the data, it was designed to be able to flexibly integrate and process various types of data. For example, the platform incorporates:

- (Live) sensor data,

- Severe weather risk maps,

- Climate projections and models,

- Expert knowledge incl. tree cadasters,

- Image and video materials, and

- Unstructured documents

This integration aims to provide users with a comprehensive view of their properties.

As part of the project, soil moisture sensors were deployed in Sanssouci Park in Potsdam Germany to monitor soil moisture levels over an extended period of time. These sensors allow for the measurement of soil moisture and temperature at a depth of one meter. A total of 10 sensors were placed at representative locations to provide insights into the irrigation needs of the property. The sensors transmit their data using LoRaWAN (Long Range Wide Area Network), a wireless communication technology that can reliably transmit smaller amounts of data over long distances with low energy consumption. Given the vastness of the Sanssouci Park case study, this approach is suitable as it allows the sensors to be placed in relevant locations without having to consider technical constraints.

The collected data is stored using a FROST server, which is an open-source software project that enables the capture of time series data, including their metadata. The FROST server implements the SensorThings API, a standard of the Open Geospatial Consortium, which aims to standardize the description of sensor data and simplify their reuse. For the visualization of the captured sensor data, a map view has been developed that allows for the positioning of the sensors and the display of their measured data.

How to cite: Moßgraber, J., Hellmund, T., Reuter, J., Kotova, L., and Matheja, K.: Creating a holistic view on the situation of historic parks and gardens, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10672, https://doi.org/10.5194/egusphere-egu24-10672, 2024.

EGU24-11004 | Orals | ERE1.3

ERODEM: Exploring Carbonate Rock Recession through Data Fusion of Extensive Experimental Data via Machine Learning 

Claudio Mazzoli, Chiara Coletti, Luigi Germinario, Lara Maritan, Riccardo Pozzobon, Nereo Preto, and Dimitrios Kraniotis

Pollution and climate change raise increasing concerns about the vulnerability of cultural heritage. In carbonate rocks, the primary concern is surface recession, which severely impacts the readability of details, preventing us from transmitting our legacy to future generations. Recession equations available in the literature are highly inadequate due to the complex relationship between climate conditions, hygrothermal (HT) behaviour, and stone textures. This is related to the limited set of parameters used by different authors and to the basic statistical approach used in their fitting processes.

Through this research, we aim to develop a robust and reliable model to predict stone recession, employing Machine Learning algorithms supported by Multivariate Statistical Analysis. We will examine a large database of surface recession measurements obtained from different types of carbonate rocks, which differ in their textural features (e.g. grain size, porosity) and HT behaviour (e.g. water vapour permeability), and of the relative micro-climate conditions under which they have been exposed during outdoor experiments. Additional recession data will be derived from laboratory experiments using an autoclave, allowing precise regulation of pH and temperature of water in contact with stone samples. Validation of the predictive model will involve comparing the recession predictions based on the time series of climate data and material characteristics with the observed recession obtained through the meticulous comparison of historical plaster replicas with the original monuments. This comprehensive analysis aims to ensure the model accuracy in capturing the real-world complexities of carbonate rock surface recession under varying environmental conditions.

 

Acknowledgement:

ERODEM project was funded by the Department of Geosciences through the “Progetto Premiale” call. This initiative is part of the larger project "Le Geoscienze per lo Sviluppo Sostenibile," funded by the Italian Ministry of University and Research (MUR) within the frame of the “Progetti di Eccellenza 2023-2027”.

How to cite: Mazzoli, C., Coletti, C., Germinario, L., Maritan, L., Pozzobon, R., Preto, N., and Kraniotis, D.: ERODEM: Exploring Carbonate Rock Recession through Data Fusion of Extensive Experimental Data via Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11004, https://doi.org/10.5194/egusphere-egu24-11004, 2024.

EGU24-12505 | Posters on site | ERE1.3

Sustainability and cultural heritage conservation: re-use of sand from deconstruction renders 

Beatriz Menéndez, Victor Yameogo, and Elhem Ghorbel

The European project SCORE (Sustainable COnservation and REstoration of built cultural heritage, GA 101007531) deals with a two-way assessment of impacts of the environment on materials and of materials on the environment. Indeed, climate conditions and atmosphere composition determine built cultural heritage (BCH) materials’ behaviour and, at the same time, BCH conservation processes (products and techniques) impact greenhouse gases emissions and then climate change.

The objective of this work is to study the feasibility of recycling old mortars and plasters from an existing building to extract the sand with the aim of reusing it to produce new mortars for the renovation of the built heritage. Old mortars and plasters were mainly made with "natural" sands, generally alluvium and river sands, available near the site. These sources of sand may no longer be available or have become scarce. The use of different sands from the original ones in restoration plasters has consequences on the aesthetic properties of the new plasters applied during the renovation, which often requires the use of additives and dyes. To solve this problem, one possibility is to extract the original sand from deconstruction mortars, taken for example from renovation sites.

We tested the proposed method on a site in Paris. Deconstruction mortars were crushed and the sand was recovered, characterized and used for the formulation of new mortars by adding lime and water. Washing methods with water and acid washing solutions have been tested in order to obtain sands free of debris and lime agglomerates. Citric acid was used because it presents good lime dissolution results and is quite easy to employ in restoration works. Microscopic observations were made to determine the effectiveness of each washing solution. Sands washed only with water show some remains of lime on the grain surfaces whereas washing the grains with citric acid solution (2 %) produces excellent results.

In addition, mortars formulations with different grain size of recycled sands were made. These formulations consist of a mixture of recycled sand, water and an additive lime in equal proportions. Specimens of 4 x 4 x 16 cm were produced and their mechanical properties were measured at 28 days of age. During the maturation time, the samples are kept in an environment with constant humidity and temperature, to optimize the conditions of hydration, carbonation and maturation.

The results obtained show that the mechanical properties of mortars made from recycled sand are acceptable and that these are intrinsically linked to the grain size and quality of the sands. The mechanical properties of mortars formulated with recycled sands of the right grain size are similar to those formulated with commercial natural sand. A large part of the recycled sand, after just washing with water, can be used in the formulation of new mortars with regard to standards and aesthetic properties.

How to cite: Menéndez, B., Yameogo, V., and Ghorbel, E.: Sustainability and cultural heritage conservation: re-use of sand from deconstruction renders, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12505, https://doi.org/10.5194/egusphere-egu24-12505, 2024.

EGU24-13376 | Posters on site | ERE1.3

Durability of Built Cultural Heritage Materials under different climate conditions 

Luis Valdeon, Beatriz Menendez, Javier Reyes, and Inge Rörig-Dalgaard

The European project SCORE (Sustainable COnservation and REstoration of built cultural heritage, GA 101007531) deals with a two-way assessment of impacts of the environment on building materials and of materials on the environment. Indeed climate conditions and atmosphere composition determine built cultural heritage (BCH) materials’ behaviour and, at the same time, BCH conservation processes (products and techniques) impact greenhouse gases emissions and eventually climate change.

This contribution presents a characterization of the effects of different climate conditions on several traditional restoration mortars, bricks and calcareous stones. A common strategy plan was designed in order to compare the results of weathering exposition experiments in several location: North of Spain, North-West of France, Denmark and Calakmul Biosphere Reserve in Mexico. Some of the presented results correspond to real conditions experiments started before the common exposition campaign but they will be presented because of their interest.

The exposition support is a frame with a plate surface of 1mx1m, placed at 1m height under two exposure conditions: inclination of 10° and at horizontal position. The exposition frame is oriented facing the predominant wind direction. For comparison we chose to expose two kinds of hydraulic lime mortars from Saint Astier company, bricks from Denmark and Mayan calcareous stone from Campeche area treated with Ca(Zn (OH)3)2·2H2O nanoparticles (CZ) in order to improve their behaviour under the exposure conditions.  Mortar coupons had dimensions of 20 x 10 x  3 cm, while the stone samples ones were 5 x 5 x 3.5 cm. A first set of mortars consisting of two-layer sample was tested with a base of a salt protection mortar and a 1 cm upper layer with a finishing mortar. A second set of mortars consists of a monolayer of a masonry restoration mortar. In each specific site, local or recipe mortars have been also exposed. 

Samples have been characterized before exposition and at regular time intervals during the exposition period, that is not finished. Weight, hardness, deterioration patterns, colour and P wave velocity have been measured at different sample locations. Results indicate that in French locations commercial mortars become better than home-made ones, probably due to the absence of any additive in the home-made recipes. First results for the Spanish exposition site show that velocity measurements start detecting some points where layers begin to separate from each other. Some microcracks start to develop at the surface of one type of mortar respecting the monolayer one.  Finally colour changes have been detected in the two layers masonry mortar.

Such gradual (also visible) degradation has previously also been documented in laboratory examination of fired clay bricks submerged in liquids with varying pH (3,5,7,9,11) and varying duration up to more than one year (432 days). Increasing submersion duration resulted in increased degradation, whereas the different pH values representing exposure to various conditions (acid rain, traditional rain, connection with alkaline mortar) revealed different degradation patterns.

The stone coupons improve some of their properties due to CZ addition at initial periods, but they tend to decrease over time.

How to cite: Valdeon, L., Menendez, B., Reyes, J., and Rörig-Dalgaard, I.: Durability of Built Cultural Heritage Materials under different climate conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13376, https://doi.org/10.5194/egusphere-egu24-13376, 2024.

EGU24-13920 | ECS | Orals | ERE1.3

Vulnerability Index of Critical Infrastructure in Greater Kuala Lumpur Fault Zone, Malaysia 

Rabieahtul Abu Bakar, Nurin Faiqah Noorazri, Zakaria Mohamad, Anggun Mayang Sari, and Zamri Ramli

The Greater Kuala Lumpur (Greater KL) region, a pivotal hub of Malaysia's economic growth, confronts a burgeoning challenge amid rapid urbanization. Unprecedentedly, it is vulnerable to seismic reactivation possibilities from the dormant Kuala Lumpur Fault Zone (KLFZ). With a comprehensive integration of geospatial technologies, to dissect the geological intricacies of the KLFZ and assess the vulnerability of critical infrastructure within Greater KL. The research aims to bridge the realms of geology and infrastructure engineering, providing actionable insights for policy decisions and urban planning to enhance the region's resilience to seismic events. The problem statement underscores the urgent need for a comprehensive investigation into the interplay between the geological characteristics of the KLFZ and the vulnerabilities in infrastructure. Despite the economic significance of Greater KL, a notable research gap hinders effective mitigation and preparedness strategies. The aim is to unravel the distinctive features of the KLFZ, assess infrastructure vulnerability, and inform policies for safeguarding against potential seismic threats. The methodology unfolds systematically, employing geospatial analysis, remote sensing, and geological data. The research adopts a meticulous data acquisition approach, integrating Sentinel-2 imagery and a seismotectonic map of Malaysia to delineate the fault zone. The extraction of critical infrastructure is conducted with precision, considering the guidelines from the U.S. Cybersecurity and Infrastructure Security Agency. The subsequent steps involve buffer zone creation, overlay analysis, and data classification to develop a vulnerability index. The expected outcome revolves around a comprehensive understanding of the KLFZ and its implications on infrastructure vulnerability. The methodology employs detailed mapping and geospatial analysis, providing insights into fault characteristics, seismic hazards, and critical infrastructure susceptibility. The research aims to contribute a robust foundation for disaster preparedness, urban planning, and engineering strategies, fostering the safety and stability of Greater KL against seismic risks. This research contributes to the broader discourse on urban resilience and disaster management, emphasizing the significance of geomatics in addressing the complex challenges posed by active fault zones or the possibilities of reactivated fault zones. The findings hold practical implications for policymakers, urban planners, and geospatial professionals, offering a nuanced perspective on the intricate relationship between geological factors and infrastructure vulnerabilities in dynamic urban landscapes. In conclusion, this research endeavours to unravel an inform evidence-based decision-making, contributing to the sustainable development and safety of the Greater KL region.

How to cite: Abu Bakar, R., Noorazri, N. F., Mohamad, Z., Sari, A. M., and Ramli, Z.: Vulnerability Index of Critical Infrastructure in Greater Kuala Lumpur Fault Zone, Malaysia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13920, https://doi.org/10.5194/egusphere-egu24-13920, 2024.

EGU24-15733 | Orals | ERE1.3

Condition assessment of limestone tombs Theban Necropolis (Luxor, Egypt) 

Ákos Török and Tamás Zomborácz

The Theban Mountain, on the west bank of the river Nile, near Luxor is internationally known as the burial site of Egyptian Dynasties. The current study focuses on four tombs dating back to the late Old Kingdom and the First Intermediate Period. The tombs are located on the hill's southern slope and were cut into the rock. Their geometry is characteristic since at least six horizontal rows were excavated above one another. Sedimentary rocks of the study area form parts of Tarawan Cretaceous, Esna Shale and Theba Limestone formations. All four tombs were once lavishly decorated with wall paintings and reliefs carved directly into the carbonatic rocks. Until now, these structures have gone through considerable erosion in addition to the occurring damages resulting from their reuse as modern habitations until the late 20th century. Thus, most of the tombs’ decorations have perished or heavily deteriorated. Since 1983 a Hungarian Archaeological Mission has been exploring the site. Numerous attempts have been made to reconstruct the fragmented walls and conserve the remaining works of art, however, very little effort has been made to understand the deterioration process and its origins. This research describes the geological conditions, petrology and sedimentology of local carbonates, fracture pattern, micro-climatic conditions of the tombs, and decay forms. Stratification, micro-cracking and discontinuities were also mapped. The painted and carved surfaces were documented, and the condition of the walls was assessed. On-site tests included moisture content measurements (vertical profiling) and the detection of surface strength by non-destructive methods. Sensors were placed at various parts of the tombs, recording temperature and relative humidity. The main trigger mechanisms of deterioration processes were identified and preservation measures were made. This study aims to provide an example that helps assess the conditions of rock-cut tombs in arid climates and the changes linked to micro-climatic conditions.

How to cite: Török, Á. and Zomborácz, T.: Condition assessment of limestone tombs Theban Necropolis (Luxor, Egypt), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15733, https://doi.org/10.5194/egusphere-egu24-15733, 2024.

EGU24-15931 | Posters on site | ERE1.3

Mapping Vertical Greenery on Historic Buildings in Neighbourhoods with High Environmental Risks: A Case Study in Antwerp, Belgium 

Eda Kale, Marie De Groeve, Lena Pinnel, Yonca Erkan, Piraye Hacıgüzeller, Scott Allan Orr, and Tim De Kock

Ongoing urbanization has increased the impact of the urban heat island effect, air pollution, and noise pollution while limiting the space for green areas. Therefore an urgent action is required to mitigate these environmental risks. Vertical Greenery (VG) has emerged as a sustainable and viable solution across diverse contexts, but it is generally not always accepted for historic buildings by experts. The scepticism is rooted in concerns about the potential adverse effects on conservation practices and heritage values. Contrary to expert concerns, VG on historic buildings is seen as a response to reducing the urban heat island effect in high environmental risk areas by the users.

We conducted a comprehensive study in Antwerp (Belgium), a city actively advocating for VG solutions. We selected three neighbourhoods, namely Historical Centre, Oud Berchem, and Borgerhout Intra Muros Zuid, where air pollution, noise, and heat stress are above the risk level. We documented the VG implementations in these three neighbourhoods through the use of GIS and field survey methods. The prevalence of VG in case sites was analysed based on factors such as the heritage status of buildings and the morphology of streets, which could pose challenges to the implementation of VG.

The results suggest that VG is present in up to 14% of all buildings in the selected neighbourhoods. While in the Historical Centre, 59% of the buildings with VG have a heritage designation. As such, narrow streets and heritage designation do not prevent VG implementation in densely built neighbourhoods with green space deficits.

While this study provides site-specific results, the analysis methods we used can guide policymakers and urban planners to explore VG's adaptability to historic buildings in the development of effective integration strategies.

How to cite: Kale, E., De Groeve, M., Pinnel, L., Erkan, Y., Hacıgüzeller, P., Orr, S. A., and De Kock, T.: Mapping Vertical Greenery on Historic Buildings in Neighbourhoods with High Environmental Risks: A Case Study in Antwerp, Belgium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15931, https://doi.org/10.5194/egusphere-egu24-15931, 2024.

EGU24-16698 | ECS | Posters on site | ERE1.3

The influence of orientation and leaf area indices of a vertical green wall on historic building materials 

Marie De Groeve, Eda Kale, Scott Allan Orr, and Tim De Kock

Built heritage is a vital component of urban environments and is rich in cultural and economic values. These buildings are abundant in city centres and have been the site of development for several centuries. They have created dense urban environments, exhibiting strong urban heat island effects. Ground-based vertical greening is a widely used green initiative in dense urban environments to mitigate the current climate stressors due to its small footprint and its ability to cover a large surface area with vegetation. The impact of this green initiative on the materials and structural integrity of built heritage is currently poorly understood and thus the focus of this research.


Several studies have already proven the efficacy of ground-based vertical greening in fostering a more stabilized condition on the underlying wall surface, characterized by reducing the amplitude of temperature and relative humidity fluctuations and the amount of solar irradiation. More stable conditions can imply a lower risk of common degradation processes, such as freeze-thaw weathering and salt crystallization, in historic building materials. 


Since the extent of the vertical greening performance and the deterioration of building façades strongly depend on the orientation of the façade, part of this research aims to establish a relationship between those two variables while considering the orientation of a building façade. Monitoring case studies in the historic city centre of Antwerp during summer develops an understanding of the shading performances of vertical greening and characterises the boundary conditions, such as orientation or leaf area index (LAI), that signify the extent of efficacy. The current case studies reveal a positive correlation between the LAI and the shading potential of vertical greening and highlight the significant role of orientation in mitigating the environmental parameters on the wall surface, as the cooling processes of vegetation mainly depend on the amount of solar irradiation. More specifically, the highest leaf area index and a south or west orientation show us the most significant cooling behaviour during the day which can reduce the risk of salt crystallization the most. The shading performance of vertical greening is only one of the several mechanisms determining the impact of vertical greening on the local environment and the subjected historic materials. 

How to cite: De Groeve, M., Kale, E., Orr, S. A., and De Kock, T.: The influence of orientation and leaf area indices of a vertical green wall on historic building materials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16698, https://doi.org/10.5194/egusphere-egu24-16698, 2024.

EGU24-18747 | Posters on site | ERE1.3

Insight to the effect of adding cow hair and pig bristles to lime mortars: Towards obtaining more sustainable construction products recycling waste animal byproducts. 

Eduardo Molina-Piernas, María Jesús Pacheco-Orellana, Salvador Domínguez-Bella, Javier Martínez-López, and Ángel Sánchez-Bellón

The increase in demand for natural resources due to the growth of the world population is generating an unprecedented increase in waste, and the unsustainability of this situation has induced the change towards a more environmentally friendly economy, the so-called “Green Economy”. Through the new policies for waste management, its reuse in other industrial processes is being encouraged, favouring “Zero Waste” initiatives. This aims to minimize the emission of greenhouse gases that could accelerate climate change, as well as to the reduction of associated energy expenditure. In Spain, two of the sectors that generate the most waste are construction and agriculture, especially linked to animal by-products not intended for human consumption (SANDACH, by its Spanish acronym). In line with these new trends, new initiatives are required to promote the reuse of this waste and the development of more sustainable construction products that involve the reduction of the carbon footprint. Therefore, the main goal of this work is to better understand the effect of adding natural fibres of animal origin, in this case cow hair and pig bristles, to lime mortars for their use both in modern construction and its application in repair historical mortars. In this way, we aim to achieve a double goal: on the one hand, to obtain information about the quality of the result of combining these products; and on the other hand, to reduce CO2 production by avoiding the incineration of animal by-products not usable in other sectors, finally producing a more sustainable mortar. The specific objectives proposed are: 1) to compare the quality of lime mortars considering the addition of hairs, bristles or with combined proportions of both fibres, with respect to control samples without fibres; 2) to evaluate if the speed and degree of carbonation are affected by the addition of fibres; 3) to identify deterioration processes that may reduce the quality of lime mortars due to aging in the laboratory and outdoors; and 4) to establish optimal production and handling conditions in collaboration with regional or national companies interested in the use of this product. To achieve these goals, in this first stage we will present the preliminary results comparing a mortar without fibres as control sample, with 3 sets of samples with different fibre proportions (containing 10 g or 20 g of cow hair or pig hair per 2 kg), as well as a mixture of both types of fibres (5+5 g and 10+10 g per 2 kg). Based on these results, it will be possible to consider the possibility of increasing the quantity of fibres until reaching an acceptable limit of workability and usefulness without compromising the quality of these mortars.

Acknowledgements: This study was financially supported by the Research Project TED2021-132417A-I00 funded by MCIN/AEI /10.13039/501100011033 and by the European Union NextGenerationEU/ PRTR and E. Molina-Piernas acknowledges co‑funding from the European Social Fund (D1113102E3) and Junta de Andalucía.

How to cite: Molina-Piernas, E., Pacheco-Orellana, M. J., Domínguez-Bella, S., Martínez-López, J., and Sánchez-Bellón, Á.: Insight to the effect of adding cow hair and pig bristles to lime mortars: Towards obtaining more sustainable construction products recycling waste animal byproducts., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18747, https://doi.org/10.5194/egusphere-egu24-18747, 2024.

Cultural heritage in Sweden is increasingly at risk from a number of climate change related factors. These include the direct effects of erosion, flooding, landslides, melting permafrost and related threats, but also increasing industrial activity in the Arctic associated with energy production and the extraction of minerals for 'green' technologies. Whilst much of the physical science of climate related threats is well understood, the practical implications at the local and regional level, as well as the hands-on management of these risks has been somewhat neglected. In a recent pilot study we exposed problems in government planning processes, and in particular that even though the general risks and potential consequences are known, Sweden lacks any form of coordinated system for the prioritisation of sites in terms of conservation, protection, documentation or abandonment. On an international level, we also identified a tendency to focus on above ground archaeological remains and high status sites and monuments. Cultural landscapes, preserved organic and palaeoecological archives, and as yet undiscovered sites are, on the other hand, are less frequently studied and often neglected in planning processes.

Many important cultural heritage sites and landscapes are in close proximity to, and potentially impacted by, transport infrastructure. As the climate warms, roads in particular are increasing in number and traffic volume in the northern areas of Scandinavia. In cooperation with the Swedish Transport Administration we developed a prototype GIS system for assisting in the evaluation of climate related threats to sites in close proximity to transport infrastructure. Three areas were investigated in more detail, ranging from temperate coastal to sub-Arctic rural settings and including a broad variety of cultural heritage types from prehistoric to historical. Case studies looked at particular secondary risks, including the expanding use road salt, and the use of specific datasets (e.g. historical maps, erosion models). This work exposed not only the potential for using such a system in research and planning, but also a number of issues in the uncritical use of publicly available national databases for transport infrastructure, climate threats, and cultural heritage. For example, the poor spatial resolution of risk maps in the Arctic and the poor locational accuracy of many older archaeological and historical investigations can lead to an incorrect assessment of threats. Similarly, much of the rural north of Sweden is poorly surveyed, and existing predictive models for locating unknown sites are inadequate. There is thus a potential bias between risk assessment in the south and the north, and between urban and rural areas. A clear potential exists for the further development of GIS based models with a greater capacity for visualizing and, to an extent compensating for, variability in the quality of the underlying data.

This presentation will show some results and conclusions from these studies, as well as some preliminary findings from ongoing research into the reasons behind problems of implementing strategies for the prioritisation of cultural heritage threatened by future climate change.

How to cite: Buckland, P. and Antonson, H.: Challenges and potential for predicting and managing climate threats to cultural heritage in Sweden, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18769, https://doi.org/10.5194/egusphere-egu24-18769, 2024.

Treatments intending to prevent stone damage sometimes accelerate deterioration unexpectedly. It would be meaningless if the use of protective agents in a more severe deterioration than originally intended. A combination of the properties between agents and stones determines the ability of protective agents to penetrate the stone. In particular, it is expected to depend on the pore diameter distribution of the stone. The present study focuses on freeze-thaw and salt weathering tests were carried out by using several types of tuffs to verify this. The stone materials used were Oya tuff, Nikka tuff, Tatsuyama tuff, Ashino tuff, and Towada tuff, which have different pore size distributions, different strengths, and different durability to salt weathering. In rocks with a high proportion of micro-pores and low resistance to salt weathering, the use of protective agents (water repellents) can delay the onset of surface deterioration. On the other hand, rocks with a high proportion of large pores (>100.5 µm) and not less resistant to salt weathering were found to be more likely to deteriorate more severely with an earlier onset of surface deterioration than untreated stones. It is considered to be because the salts crystallize at greater depths when protective agents are applied, whereas they crystallize only at the surface in the case of untreated rocks, and the crystalline pressure causes fracture from the deeper layers. Therefore, when using protective agents, it is necessary to understand the combination of rock properties such as rock structure, pore size, and strength of the rock sample with crystal pressure.

How to cite: Oguchi, C. and Ikeda, Y.: Effect of pore size distribution on the application of water repellent for preventing deterioration of stone materials., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19171, https://doi.org/10.5194/egusphere-egu24-19171, 2024.

Identifying and determining buried archaeological structure limits are crucial for archaeological prospection surveys. The archaeological prospection surveys can shed light on protecting cultural heritage. Magnetic is one of the most applied methods in archaeological surveys to plan the excavation process. It aims to identify buried temples, graves, city walls, and other structures by interpreting the data obtained from magnetic measurements, which is one of the non-destructive geophysical exploration methods. In the process of interpretation of magnetic data, many methods have been developed, such as Horizontal Gradient Magnitude, Analytical Signal, Theta Map, and Tilt Angle methods, which can generate information about the boundaries of potential subsurface features. By analyzing the gradients of the magnetic field data, inferences can be made to determine the edges of subsurface potential archeological structure distributions.

The Olympos is an important ancient city in Antalya (the south of Turkey) and contains many structures from the Byzantine period. This research aims to detect the pipe drain as a water system of the Episkopeion region in the Olympos ancient city. To this end, Tilt Angle (TA) and Edge detection field (ED) methods were tested on the magnetic map of the synthetic model. The horizontal boundaries of the potential pipe drain elements of the region were analyzed by applying the same procedures on the magnetic map obtained from the magnetic measurements on the area that has not been excavated in the Episkopeion archaeological excavation area. Magnetic measurements were carried out in 4 different regions within the Episkopeion area, and each area was numbered and analyzed separately. Combining the results obtained, an integrated visualization of the water system in the area was achieved.

Keywords: Archaeological Prospection, Edge Detection, Olympos, Tilt, Angle, Pipe drains.

 

How to cite: Deniz Toktay, H.: Edge detection of magnetic data: Preliminary results of application to Episkopeion region in Olympos Ancient City (Antalya), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19203, https://doi.org/10.5194/egusphere-egu24-19203, 2024.

EGU24-391 | ECS | PICO | HS7.3

Explaining agricultural land use changes in Spain (2004 – 2021): Markets, climate and water resources. 

Gabriel Arbonès Domingo, Lucia De Stefano, and Alberto Garrido

In Spain, from 2004 to 2021, irrigation has increased by 500,000 hectares, the percentage of cultivated land with irrigation has increased from 18% in 2004 to 23% in 2021. The literature points to intensive irrigated agriculture as one of the main causes of the destruction of biodiversity, the worsening of the quality of water bodies, changes in the rural economy, among others. The study analysis the dynamics of land use changes in Spain particularly in irrigated crops, from 2004 to 2021 at provincial level. It aims to understand and promote sustainable land use transitions by identifying factors influencing farmers' decisions in altering land use and crop surfaces. To this end, several public open-access databases were used to analyse, on one hand, the land use changes at a detailed level, and on the other hand, guided by the literature to examine the factors behind the observed land use change. Findings reveal agricultural intensification trends in Spain, marked by the abandonment of less productive croplands and the intensification of highly productive lands, through the implementation of irrigation. The intensification, driven by the introduction of irrigated woody crops, mostly olives, vineyards, and almonds, predominantly occurred in the water-constrained southern region of the country. This was achieved by overcoming water limitations through increased exploitation of groundwater, and the widespread adoption of drip irrigation technology. Additionally, market trends driving increased demand for these commodities and changes in the Common Agricultural Policy (CAP) have further contributed to their expansion. We explain why some provinces intensify, via more irrigated and intensive crops, and reduce cultivated land, whereas others intensify and expand the total cultivated land. The study suggests that agricultural land change is a complex dynamic process, resulting from a combination of policy impact, market incentives, mature technologies, available resources and changing climate.

How to cite: Arbonès Domingo, G., De Stefano, L., and Garrido, A.: Explaining agricultural land use changes in Spain (2004 – 2021): Markets, climate and water resources., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-391, https://doi.org/10.5194/egusphere-egu24-391, 2024.

EGU24-697 | ECS | PICO | HS7.3 | Highlight

Rainfall accumulation as a driver of higher Leptospirosis risk in northern South America 

Alejandro Builes-Jaramillo, Clara Susana Arias-Monsalve, Juliana Valencia, Carolina Florian, and Hernán D. Salas

Rainfall accumulation during wet seasons in Northern South America can be enhanced during La Niña ENSO phases.  Leptospirosis is a zoonotic waterborne disease that affects humans, domestic animals, and wildlife associated with occupational and recreational water activities, natural disasters, and socioeconomic conditions for which rainfall plays a key role in its transmission. We analyzed the incidence of leptospirosis, and relative risk of changes on the incidence of the disease due to rainfall accumulation in Northern Colombia during the period 2007-2021. The rainfall accumulation analysis was done for 7, 14 and 21 days based on the periods of incubation of the disease, biology of transmission, and thresholds of rainfall accumulation above the mean values. We found a statistically significant association between excess rainfall and leptospirosis at different lags for cities in Northern Colombia (Barranquilla, Santa Marta, Cartagena) and the levels of accumulated rainfall exceedance associated with leptospirosis were specific for each city. Our findings give insight into the association between leptospirosis and excess accumulated rainfall and provide climate services and local health authorities with tools to act on and prevent this important zoonotic disease.

How to cite: Builes-Jaramillo, A., Arias-Monsalve, C. S., Valencia, J., Florian, C., and Salas, H. D.: Rainfall accumulation as a driver of higher Leptospirosis risk in northern South America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-697, https://doi.org/10.5194/egusphere-egu24-697, 2024.

Environmental protection is of global interest to earth’s inhabitants with increasing concerns related to climate change. Solid wastes constitute an undeniable source of environmental degradation and a possible disaster to human health. In Jos Metropolis, a number of arable lands double as waste dumpsites and are at risk of heavy metal pollution. Shallow groundwater used for domestic purposes and plants cultivated near these dumpsites are prone to contamination and the prolonged consumption of unsafe concentrations of heavy metals through edibles and/or water may trigger numerous biochemical alterations in the human body. Subsurface geophysical investigation using 2D electrical survey and the assessment of soil and water quality has been carried out in the arable land and at close geological proximity to a solid waste dumpsite located at Utan, Jos, Plateau State, Nigeria. This study focus on delineating the lateral extent and depth of leachate migration into the subsurface from the waste dumpsite. 2D resistivity survey was carried out along three traverse (A, B and C) using Wenner–Schlumberger configuration. Qualitative interpretation of the inverse resistivity models revealed low resistivity zones of < 44 Ωm to be regions of leachate accumulation. The extent of downward migration through the vertical stratigraphic interval exceeds 15.6 m trending laterally in the eastern direction of traverse A. The analysis of heavy metal determination for water samples was aided by the use of Atomic Absorption Spectrophotometer while the soil samples were analyzed using X-ray fluorescence (XRF) analytical method. The concentrations of Pb and Ni in the analyzed water samples were above the permissible limit for drinking water and concentration of heavy metals in soil samples varies significantly. This study revealed the concentration of heavy metals in soil and water samples in close geographical proximity to the waste dumpsite and the uncontrolled disposal of waste over time poses great threat to the environment and its inhabitants. Waste management practices have to be improved upon to mitigate pollution.

How to cite: Obasuyi, F. O., Oladimeji, A. M., and Yusuf, T. A.: Investigation of the lateral extent and depth of contamination using 2D electrical resistivity and the assessment of soil and water quality in the vicinity of a Waste Dumpsite in Utan Jos, Plateau State. Nigeria., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1287, https://doi.org/10.5194/egusphere-egu24-1287, 2024.

EGU24-2496 | PICO | HS7.3

Effect of intermittent drainage on the emission of two greenhouse gases (CO2 and CH4) from three paddies in South Korea 

Seunghun Hyun, Wonjae Hwang, Minseok Park, Youn-Joo An, Sunhee Hong, and Seung-Woo Jeong

In this field pot study, effect of irrigation practice (continuous flooding (CF) and intermittent drainage (ID) treatment) on greenhouse gas (GHGs, CO2 and CH4) emission was determined from three Korean paddies (BG, MG, and JS series), varying soil properties such as soil texture, labile carbon, and mineral types.  Emission of GHGs was evidently influenced by irrigation practices, to a different extent, depending on paddy’s redox response to flooding events.  The Eh decline upon flooding was slower in JS pot, where pore-water concentration of ferric and sulfate ions is the highest (~ up to 3-fold) among three paddies.  MG pot was 2- to 3-fold percolative than others and the Eh drop during flooding period was the smallest (remaining above -50 mV) among three pots.  By adopting ID, CH4 emission (t CO2-eq ha-1 yr-1) was reduced in a wide range by 5.6 for JS pot, 2.08 for BG pot, and 0.29 for MG pot relative to CF, whereas CO2 emissions (t CO2-eq ha-1 yr-1) was increased by 1.25 for JS pot, 1.07 for BG pot, and 0.48 for MG pot due to the enhanced carbon oxidation upon drainage.  Grain yield and aboveground biomass production from ID were no less than those from CF (p < 0.05).  Consequently, benefit of global warming potential (S GWP) by ID varied as in order of JS (37%) > BG (14%) > MG (~0 %) pots, and negligible effect observed for MG pot was due to the equivalent trade-off between CO2 and CH4. Our findings imply that that the efficacy of drainage on GHG mitigation depends on the redox response of paddies.

Keyword

Climate Change, Greenhouse gas, Paddy, Intermittent drainage

 

Acknowledgement

This research was in part supported by the Korea Environment Industry & Technology Institute (KEITI), funded by Korea Ministry of Environment (MOE) (No. 2022002450002 (RS-2022-KE002074)) and in part supported by Korea University Grant.

How to cite: Hyun, S., Hwang, W., Park, M., An, Y.-J., Hong, S., and Jeong, S.-W.: Effect of intermittent drainage on the emission of two greenhouse gases (CO2 and CH4) from three paddies in South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2496, https://doi.org/10.5194/egusphere-egu24-2496, 2024.

Agricultural development in Kinmen region has long suffered from the absence of a corresponding management unit responsible for irrigation planning and infrastructure maintenance, resulting in the majority of local farmlands relying on natural rainfall for cultivation. Unfortunately, this method is highly susceptible to the impacts of climate change. To address this pressing issue, the government plans to utilize reclaimed water from domestic sources as a supplementary irrigation resource. Within this context, this study aims to devise an irrigation water allocation model to optimally harness the limited water resources.

In this study, we simulate the crop rotation of local sorghum and wheat, considering soil, crop, and historical meteorological data. We calculate the variations in crop yield under different irrigation schemes. Additionally, we use historical meteorological data from Kinmen to calculate various simulated climates, testing the benefits of this irrigation plan under more extreme weather conditions. In conclusion, guided by the simulation outcomes and considerations of factors like cost and government procurement prices, we undertake a comparative analysis of the economic benefits under various scenarios and irrigation plans. This analysis aims to pinpoint the optimal irrigation water allocation plan that can be feasibly implemented by local farmers.

For this study, we have chosen a 100-hectare demonstration area located in Jinsha Town, Kinmen, as our study area. We will utilize 750 tons of reclaimed water provided daily by the Ronghu Water Resources Recycling Center as the irrigation water source, and the government has already established six agricultural ponds in the area to store water. Following this, our study will proceed with the implementation of the irrigation water allocation plan in the designated demonstration area. Our ultimate aim is for this initiative to serve as a starting point, enabling the systematic expansion of the irrigation water allocation plan to other regions in Kinmen, thereby enhancing the overall irrigation quality.

Keywords: Irrigation Water Allocation Model; Reclaimed Water; Rotation Irrigation; Kinmen; Sorghum

How to cite: Su, Y., Yu, H.-L., and Chang, T.-J.: Agricultural Irrigation Water Allocation Planning and Economic Benefit Assessment – A Case Study of Kinmen County, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2737, https://doi.org/10.5194/egusphere-egu24-2737, 2024.

EGU24-3235 | ECS | PICO | HS7.3

Estimating the risk of crop yield loss due to changing regional air temperatures 

Poornima Unnikrishnan, Kumaraswamy Ponnambalam, and Keith Hipel

Agricultural produce’s yield can be heavily impacted by changes in the weather patterns. With the current global warming scenario, the extremes temperature anomalies are expected to occur more frequently, posing a significant threat to the crop yields. To better plan the agricultural practices and crop rotation, it would be highly beneficial to understand the impact of temperature anomalies on crop yields. Here in this study, we investigated the impact of changing air temperature extremes on the yields of strawberries in farms in California's Central Valley. By using a copula modeling framework, the study has identified the risks of crop yield loss associated with temperature extremes. Based on this analysis, various scenarios of crop yield loss have been identified, and the likelihood of encountering those scenarios based on changes in temperature extremes has been estimated. The results of this study can be immensely helpful in planning agricultural practices and implementing appropriate measures to mitigate the risks. With air temperature forecasts readily available from various sources, nature-based solutions can be effectively implemented to combat the negative effects of temperature extremes on crop yields.

How to cite: Unnikrishnan, P., Ponnambalam, K., and Hipel, K.: Estimating the risk of crop yield loss due to changing regional air temperatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3235, https://doi.org/10.5194/egusphere-egu24-3235, 2024.

Vegetation restoration such as human-induced and natural growth has seen a significant increase over the past two decades. However, this surge has raised concerns regarding its potential impact on water resources and its consequential hindrance to local social and economic development. Policymakers are particularly focused on mitigating the negative hydrological effects of vegetation restoration. Nevertheless, the implications for water yields in the context of forest management types, such as planted and natural forests, remain unclear. In this study, we explored hydrological responses to forest expansion in both planted and natural forest watersheds, utilizing evapotranspiration data synthesized from 12 data products, forest management maps, and climate datasets. Our analysis, based on the Budyko framework, revealed that water yield reduction in arid watersheds with planted forests (PFs) exceeded that in watersheds with expanding natural forests (NFs). Interestingly, vegetation restoration, whether in PFs or NFs watersheds, could even lead to an increase in water yield. Attribution analysis highlighted ecological restoration, rather than climate conditions, as the primary contributor to the observed water yield decrease. In NFs watersheds, the decrease was primarily linked to underlying characteristics, while in PFs watersheds, changes in water yield sensitivity to the land surface played a crucial role. It is noteworthy that vegetation restoration in humid zones exhibited a negligible impact on water yield. Even in NFs watersheds where water yield decreased due to tree cover expansion in drylands, natural growth emerged as a viable option to mitigate local hydrological effects in arid zones.

How to cite: Yan, Y., Liu, Z., and Jaramillo, F.: The distinct hydrological responses to vegetation restoration between planted and natural forests watersheds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3708, https://doi.org/10.5194/egusphere-egu24-3708, 2024.

The study focuses on assessing the impact of climate change on water balance components in the Upper Ghatprabha River Basin in India. The Soil Water Assessment Tool (SWAT) is utilized to simulate streamflow in the basin. Calibration and validation of SWAT are performed across multiple sites using the Sequential Uncertainty Fitting Algorithm (SUFI 2). Performance assessment relied on metrics such as the Nash-Sutcliffe efficiency (NSE) and coefficient of determination (R2). Future climate projections are based on an ensemble mean of 13 bias-corrected GCM models for the Shared Socioeconomic Pathways (SSP) scenarios SSP245 and SSP585. The simulation of future basin water balance components involves segmenting the entire timeframe into S1 (2015-2040), S2 (2041-2070), and S3 (2071-2100). Projections indicate an increase in maximum and minimum temperatures, with precipitation potentially rising by up to 47% in the basin under the SSP245 scenario by the end of the century. Hydrological simulations reveal increased surface runoff and evapotranspiration under the SSP245 scenario compared to historical data. The percentage change in blue water components under both SSP scenarios shows an increase of more than 50% compared to the historical data. In comparison, that of green water components only increases to a maximum of 8% in all the timeframes (S1, S2 and S3). Notably, the impact of climate change is more pronounced under the SSP585 scenario compared to SSP245. These changes significantly impact the water resources of the Upper Ghatprabha River Basin; necessitating focused attention on future planning and management strategies for water resources.

How to cite: Jain, S. and Jain, M. K.: Assessment of Blue and Green Water Availability in the Upper Ghatprabha River Basin under Climate Change Impacts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4988, https://doi.org/10.5194/egusphere-egu24-4988, 2024.

EGU24-5462 | ECS | PICO | HS7.3

Influencing factors of durum wheat productivity under current and future climatic conditions 

Malin Grosse-Heilmann, Elena Cristiano, Francesco Viola, and Roberto Deidda

Durum wheat is a critical staple crop in arid and semi-arid regions worldwide, that plays a significant role in local food security. Providing essential nutrients and a high protein content, it is widely used for the production of pasta and couscous. Various constraints and drivers affect durum wheat productivity, including biotic and abiotic stressors, agronomic practices, and CO2 concentrations. Their influence varies based on duration and intensity of the stressor, as well as the durum wheat growth phase in which they occur. Drought and heat were shown to act as primary yield limiting factors. Furthermore, the water footprint, a comprehensive measure for the volume of water associated with crop production, helps to analyse durum wheat cultivation from a water-food nexus perspective. Given that climate change is affecting the main influencing factors of durum wheat’s productivity and of its water footprint, such as precipitation, temperature, and atmospheric CO2 levels, its cultivation is expected to undergo alterations as well. In this context, we explore the present state of durum wheat productivity and the potential influence of changing climatic conditions on its future cultivation worldwide. The current state of research on future durum wheat production is characterised by contradictory results, compromising projections of significant declines due to heat and drought stress as well as strong increases in productivity as a consequence of the CO2-fertilisation effect, for the same or nearby locations. Understanding the complex interactions between climate change, durum wheat productivity and the associated water footprint is of great importance to derive sustainable adaptation strategies and move one step closer into ensuring future food and water security.

How to cite: Grosse-Heilmann, M., Cristiano, E., Viola, F., and Deidda, R.: Influencing factors of durum wheat productivity under current and future climatic conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5462, https://doi.org/10.5194/egusphere-egu24-5462, 2024.

Mobile phones, televisions, computers and other liquid crystal devices have become the electronic products widely used by humans in modern society. Liquid crystal monomers (LCMs) are the key material of liquid crystal display and considered as potential persistent, bioaccumulative, and toxic (PBT) substances in recent years, but there is a limited of information regarding their occurrence in human body. We used EPI suite software from USEPA to evaluate its physical and chemical properties, analyzed its concentration in serum and urine by GC-MS, and finally assessed its health risk to humans through the calculation of daily intake. In this paper, 15 LCMs were detected in serum and urine samples of the general population, with median concentrations ranging from 9.7 to 124.8 and 2.68 to 36.98 µg/L, respectively. The correlation of LCM in serum and urine suggests that they have potential common applications and similar sources. The results showed that the CLrenal of LCMs in the Northwest China population was 0.61, 7.79, 6.04, 4.81, 9.37, 4.85, 19.94, 10.64, 3.80, 7.44, 8.26, 15.39, 7.52, 10.17, 13.54 mL/kg/day for EBCN, BCBP, PBIPHCN, DFPrB, FPrCB, BEEB, BMBC, DFPCB, DFEEB, EPrCPB, EEPrTP, EDFPB, DFPrPrCB, EFPeT, TeFPrT, respectively. The daily intake for ∑LCMs in the adult of northwest China was 22.35 ng/kg bw/day, indicating a potential exposure risk to the general population. This study provides the first evidence for the presence of LCM in serum and urine in the daily population and finds a correlation between LCMs, but the differences in B/U ratio and renal clearance indicate the need for further investigation of its metabolism and clearance in the human body.

How to cite: Yang, K., Cheng, H., Quan, W., Gong, Y., and Ai, Y.: Human health risks estimations from Liquid crystal monomers(LCMs)in Northwest China : partitioning, clearance and exposure in paired human serum and urine, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7771, https://doi.org/10.5194/egusphere-egu24-7771, 2024.

EGU24-8378 | ECS | PICO | HS7.3

Optimizing irrigation practices for sustainable olive production in semi-arid areas: A comparative analysis of the efficiency of Subsurface and Surface drip irrigation systems  

Sara Ourrai, Bouchra Aithssaine, Abdelhakim Amazirh, Salah Er-raki, Lhoussaine Bouchaou, Frederic Jacob, Mohamed Hakim Kharrou, and Abdelghani Chehbouni

Abstract : Irrigated olive trees constitute the main arboricultural component of orchards in semi-arid regions, and the optimization of irrigation practices is crucial to sustain the production, increase agricultural water productivity and reallocate water savings to other higher-value uses. Numerous technical strategies have been implemented in the last two decades, to promote water conservation in irrigated agriculture, namely the adoption of subsurface drip irrigation system. This study delves into a comprehensive comparative analysis between subsurface (SDI) and surface (DI) drip irrigation systems over an olive orchard, with an emphasis on the evolution of evaporative fraction (EF) and the ratio of transpiration (T) to evapotranspiration (ET), soil moisture distribution patterns, as well as water use efficiency and water productivity. The experiment was carried out over two irrigated olive plots located in the Tensift basin (Morocco), from May to October 2022. Each plot is subjected to a specific irrigation pattern, and equipped with an Eddy-Covariance system to quantify the energy balance components, along with Time-Domain-Reflectometry (TDR) sensors installed at various depths, to monitor the soil water content. Besides, the partitioning of ET into T and evaporation (E) over the two irrigation systems was performed using the Conditional Eddy-Covariance (CEC) scheme and validated using sap flow measurements collected over SDI plot during April 2023. The ET of the DI system was higher than that of the SDI one, with diurnal ET values ranging between 0.58-3.02 (mm/day) and 0.48-2.74 (mm/day) for DI and SDI systems, respectively. Our findings suggest that although a smaller irrigation water amount was applied in SDI (194 mm) compared to DI (320 mm), crop yield revealed no significant differences. This thorough assessment intends to add substantial knowledge to the lasting debate about sustainable irrigation practices over olive orchards and assist policymakers in making informed decisions to enhance water use efficiency while sustaining overall agricultural production.

Keywords: subsurface and surface drip irrigation; evapotranspiration; water productivity; water use efficiency; olive trees; semi-arid areas.

How to cite: Ourrai, S., Aithssaine, B., Amazirh, A., Er-raki, S., Bouchaou, L., Jacob, F., Kharrou, M. H., and Chehbouni, A.: Optimizing irrigation practices for sustainable olive production in semi-arid areas: A comparative analysis of the efficiency of Subsurface and Surface drip irrigation systems , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8378, https://doi.org/10.5194/egusphere-egu24-8378, 2024.

EGU24-8539 | ECS | PICO | HS7.3

Design of a low-cost autonomous seawater measurement buoy to scale and optimize a green-powered desalination plant 

Zachary Williams, Manuel Soto Calvo, and Han Soo Lee

Climate change and water scarcity has pushed more countries with direct ocean access to seek desalination solutions to face part of their need for domestic water networks or industrial usage, while conserving coastal ecosystems. Seawater monitoring is crucial in implementing a desalination plant as it ensures the efficiency and sustainability of the desalination process, especially in the case of a plant powered by renewable energy sources. Seawater is the main input of desalination processes and coastal areas are the locations of the release of the salty waste. An autonomous buoy can be used to monitor the seawater parameters which are essential to sizing a desalination plant.

There have been recent developments of autonomous buoy systems for monitoring different water parameters, however lacking in certain aspects. Some of the elements of these buoys include limited range of data transmission, high-cost designs, immobility and limited number and types of sensors. Also, there has been lacking implementation of autonomous buoys used in development of desalination plants. 

The proposed low-cost autonomous buoy is designed and constructed using cost effective materials. It increases the possibility of multiplying the sensor count to have a more accurate data mapping system. The low cost provides the opportunity of having more devices where there is a higher probability of equipment loss due to possible theft or remoteness of travel. The power supply is an oversized solar array with a backup battery and solar charger. An Arduino microcontroller is connected to two probes and a GPS sensor. The data is logged on a SD memory card with data transmitted via the Iridium satellite constellation, consisting of 75 satellites. There are two parts of construction involved in the project: the construction of the outer shell of the buoy and the design of the inner circuitry and components. The project involves multiple steps of experimentation: first in a laboratory/controlled area then deployed in the Seto Inland Sea, Japan. The various steps ensure the data collected by the sensors is reliable, valid, and suitable for scientific research. After this successful implementation, the buoy will be adapted and deployed in the Caribbean Sea surrounding Jamaica.

Initial results show a promising possibility of measuring seawater parameters such as GPS location, salinity, and sea surface temperature for any body of water. Utilizing the span of the Iridium satellite communication system, this ensures that virtually all regions of the Earth can be measured. The sizing of the solar powering components allows for at least 1 year of monitoring in the worst-case scenario and 4-5 years in the best-case scenario. The integration of autonomous buoys in the desalination process enhances efficiency in the plant design stages and reduces potential costs which contributes to the optimization of the desalination system. The environmental integration and the operation of the plant will be improved as a result of the enhanced assessment of the input and waste release conditions.

 

Keywords: Seawater Monitoring, Remote Sensing, Desalination, Autonomous buoy, Autonomous measurements

 

How to cite: Williams, Z., Soto Calvo, M., and Lee, H. S.: Design of a low-cost autonomous seawater measurement buoy to scale and optimize a green-powered desalination plant, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8539, https://doi.org/10.5194/egusphere-egu24-8539, 2024.

Reduced rainfall has been identified as a highly probable consequence of climate change in certain regions of Zambia. This is particularly concerning for small-holder farmers, who heavily rely on rainfall and are the primary producers of the country’s staple food, such as maize. The resulting decrease in production significantly impacts national food security. Recognizing the potential of irrigated agriculture to improve food security and sustain production levels, the Zambian Agricultural Research Institute (ZARI) has been actively engaged in research since 2021. Their focus is on enhancing irrigation and soil fertility management under conditions of reduced water availability.

To address these challenges, a research trial was initiated at the ZARI research station in 2021. This trial aims to identify the optimal and sustainable water and nitrogen application for achieving maximum maize production in irrigated crop systems. Access tubes were installed in each subplot to monitor soil moisture to a depth of 1 m before and after irrigation on a weekly basis.

This paper assesses the stored water in the root zone (up to 1 m) with interplay between amount of nitrogen fertilizer  applied and water application level.

In the 2021 season, the results indicate that significantly more water was retained averagely throughout the growing season  in treatments with higher nitrogen levels, especially under reduced irrigation water applications (50% and 75% ETc). A similar trend was observed in the 2022 season, albeit only for 50% ETc. The increased stover yield may have contributed to reduced evaporation, minimizing losses. As nitrogen application levels rise, the ability to store soil water in the profile appears to increase. However, further analyses of soil moisture depth and root systems are needed to determine whether excess water in deficit-irrigated treatments is obtained from lower depths or if (and how much) water is lost in optimally irrigated treatments.

How to cite: Mwape, M., Said Ahmed, H., Phiri, E., and Dercon, G.: Enhancing Maize Production in Irrigated Crop Systems: Optimizing Water and Nitrogen Application for Sustainable Agriculture in Zambia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8734, https://doi.org/10.5194/egusphere-egu24-8734, 2024.

EGU24-9386 | ECS | PICO | HS7.3

Food security in a changing climate - how can Earth observation and machine learning help?  

Emanuel Bueechi, Milan Fischer, Laura Crocetti, Miroslav Trnka, Ales Grlj, Luca Zappa, and Wouter Dorigo

Climate change is threatening food security. To ensure food security, we do not only have to safeguard agricultural production - crop yields also need to be optimally distributed. For that, decision-makers need reliable crop forecasts so that they can plan which regions are likely to experience crop yield losses and which regions will produce a surplus. Earth observation and machine learning are key tools to calculate such forecasts. However, extreme crop yield losses, for example caused by severe droughts, are often underestimated. To test this, we developed a machine learning-based crop yield anomaly forecasting system for the Pannonian Basin and examined its performance, with a focus on drought years. We trained the model (XGBoost) with crop yield data from 43 regions in southeastern Europe and predictors describing soil moisture, vegetation, and meteorological conditions. Maize and winter wheat yield anomalies were forecasted with different lead times (zero to three months) before the harvesting season. Our results show that the crop yield forecasts are significantly more reliable from 2 months before the harvest than before in both, drought and non-drought years. The models have their clear strength in forecasting interannual variabilities but struggle to forecast differences between regions within individual years. This is related to spatial autocorrelations and a lower spatial than temporal variability of crop yields. In years of severe droughts, the wheat yield losses remain underestimated, but the maize forecasts are fairly accurate. The feature importance analysis shows that in general wheat yield anomalies are controlled by temperature and maize by water availability during the last two months before harvest. In severe drought years, soil moisture is the most important predictor for the maize model and the seasonal temperature forecast becomes key for wheat forecasts two months before harvest. 

How to cite: Bueechi, E., Fischer, M., Crocetti, L., Trnka, M., Grlj, A., Zappa, L., and Dorigo, W.: Food security in a changing climate - how can Earth observation and machine learning help? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9386, https://doi.org/10.5194/egusphere-egu24-9386, 2024.

EGU24-13506 | ECS | PICO | HS7.3

The impact of drought on the water-food nexus at the global scale 

Tobia Rinaldo, Elena Ridolfi, Benedetta Moccia, Flavia Marconi, Paolo D'Odorico, Fabio Russo, and Francesco Napolitano

The demand for farmland products is increasing worldwide, causing unprecedented stress on the global agricultural system and, consequently, on water resources. Here we analyse the impact of drought events on rainfed agriculture, a topical issue given the prolonged and severe drought events currently occurring around the world and thus including highly productive areas. We investigate the agricultural yields of key crops that represent 61% of the world’s production of proteins for human consumption (i.e. corn, wheat, rice, and soybeans). Our analysis spans from the early 1900s to 2022, allowing us to assess the total agricultural area under drought stress per year and the most vulnerable types of crops. We identify significant trends in the extent of agricultural land under stress, considering both historical and recent periods. This comprehensive analysis enables us to estimate the frequency of occurrences of crop-specific cultivated areas under stress over time, unravelling the pattern of drought impact on global agriculture.

How to cite: Rinaldo, T., Ridolfi, E., Moccia, B., Marconi, F., D'Odorico, P., Russo, F., and Napolitano, F.: The impact of drought on the water-food nexus at the global scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13506, https://doi.org/10.5194/egusphere-egu24-13506, 2024.

Continued population growth, changing climate and increased pressure on water resources will dramatically increase the pressure on Chinese agriculture in the coming decades. Although there have been some reports of yield stagnation in the world’s major cereal crops, including maize, rice and wheat, the reasons for stagnation have not been quantified thoroughly. Here, we use statistical data to examine the trends in crop yields for two key Chinese crops: maize and wheat and their drivers in China’s drylands. Results showed that although yields continue to increase in many areas, we found that across 70.2% of maize- and 51.9% of wheat- growing prefectures or provinces, yields either never improved, stagnated or collapsed. The reasons for the decline and stagnation of crop yield were mainly caused by the change of growing season precipitation and irrigation fraction. New investments such as increased irrigation fraction in underperforming regions, as well as strategies to continue increasing yields in the high-performing areas, are required.

How to cite: Zi, S.: Recent patterns of crop yield growth, stagnation and their drivers in China’s dryland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13868, https://doi.org/10.5194/egusphere-egu24-13868, 2024.

EGU24-18617 | ECS | PICO | HS7.3

Climate change impact on wheat yield in India: Study using CERES-wheat model 

Achanya Lakshmanan, Yogendra Shastri, and Riddhi Singh

Agriculture is highly dependent on climate because rainfall, temperature and sunlight are the primary determinants of crop development. Climate change driven effects such as variation in precipitation and changes in temperatures are likely to affect agricultural yields. Systematic planning of agricultural activities considering these effects is essential. As a first step towards this longer term objective, this work quantifies the effect of climate change on crop in short and long term in India. Wheat is chosen as the crop of interest. Madhya Pradesh, one of the leading wheat producing states in India, is the region under focus, and Betul district is selected for a initial studies. The CERES-wheat model in the Decision Support System for Agrotechnology Transfer (DSSAT) tool is used to estimate the impact of climate change on wheat yield. The CERES-wheat model has been calibrated and validated, and the calibrated parameters have been used to simulate wheat yield in the future. The base period for calculating base wheat yield is 2009-2019. Future wheat yields are calculated for two periods (2025-2055 and 2056-2085). The projected changes in precipitation, maximum temperature (Tmax) and minimum temperature (Tmin) in future compared to the base period are calculated using four different General Circulation Models (GCMs) and four Shared Socioeconomic Pathways (SSPs). To increase the study's robustness, 1000 samples are systematically generated using Latin Hypercube Sampling (LHS). A stochastic weather generator (WG), WeaGETS, is used to create a synthetic time series of climate variables. Using the 1000 different combinations of changes in climate variables, 1000 climate scenarios are generated using WeaGETS. The climate variables used to determine the relationship between climate and wheat yield were mean rainfall, rainfall variance, Tmax, and Tmin. Wheat yield ranged from 2065 to 3207 kg/ha during the baseline period, and it is expected to vary from 1629 to 3638 kg/ha between 2025 and 2055. Looking ahead to 2056-2085, wheat yields are estimated to range from 1363 to 3555 kg/ha. The sensitivity analysis results between climate variables and wheat yield for both periods suggest that wheat yield is positively correlated with mean rainfall and rainfall variance and negatively correlated with Tmax and Tmin. Maximum temperature has a significant negative correlation with wheat yield in both periods after excluding the effect of other climate variables. However, in the last stage of wheat yield development, the grain filling stage, Tmin is more critical than Tmax. These results highlight the need for systematic planning to manage negative impacts of climate change on wheat cultivation in India. These results will used as a basis for suggesting adaptation strategies to manage the impact of climate change on wheat yield.

How to cite: Lakshmanan, A., Shastri, Y., and Singh, R.: Climate change impact on wheat yield in India: Study using CERES-wheat model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18617, https://doi.org/10.5194/egusphere-egu24-18617, 2024.

EGU24-19902 | PICO | HS7.3

Estimating and Suggesting measures to reduce carbon emissions and water footprint linked to water collection, agriculture, and tourism in the Canary Islands (Spain) 

Juan C. Santamarta, Noelia Cruz-Pérez, Joselín R. Rodríguez-Alcántara, Jesica Rodríguez-Martín, Alejandro García-Gil, Samanta Gasco-Cavero, and MIguel Á. Marazuela

The Canary Islands constitute an archipelago of Spain, also being a European outermost region composed of eight islands. Overall, these islands face a high risk of experiencing the impacts of climate change, particularly rising sea levels, floods, temperature increases, and a decrease in water resources, factors that significantly affect the daily life of the population in the islands. As the effects of climate change are linked to greenhouse gas emissions, it is crucial to measure the emissions from the main sectors of the Canary Islands to implement effective mitigation and reduction measures, as well as to increase energy production through renewable sources. For this reason, the Government of the Canary Islands has commissioned the project to determine the carbon footprint and water footprint of the main sectors of the region, including the production of drinking water and wastewater management, agriculture, and tourism. The results indicate that seawater desalination for drinking water, being a significant energy consumer with low penetration of renewable energy in the Canary Islands' electricity mix, is the facility contributing the most to greenhouse gas generation in the water cycle in the region. It is followed by wastewater treatment plants and extraction wells from the aquifer. In the case of agriculture, focusing on the consumption of tropical crops such as avocados and bananas, key export crops, it is noteworthy that avocados are major water consumers, slightly exceeding the water consumption of bananas. This poses challenges in the face of an uncertain future due to reduced natural precipitation resulting from climate change. Lastly, the analysis of tourism emissions highlights that hotel activities and rental vehicles are significant contributors to greenhouse gas emissions. Although these emissions are indirect for the archipelago, other studies have emphasized the high emissions associated with the arrival of tourists by air to the islands. This study stands as the first to analyze the emissions of the main sectors in the Canary Islands, providing an opportunity for governmental actions to reduce these emissions and mitigate climate change in the islands.

Keywords: Climate change; outermost region; vulnerability; sustainable development

Acknowledgements

This research was supported by the European Union's Horizon 2020 Research and Innovation Programme under grant agreement 101037424 and Project ARSINOE (Climate Resilient Regions Through Systems Solutions and Innovations).

How to cite: Santamarta, J. C., Cruz-Pérez, N., Rodríguez-Alcántara, J. R., Rodríguez-Martín, J., García-Gil, A., Gasco-Cavero, S., and Marazuela, M. Á.: Estimating and Suggesting measures to reduce carbon emissions and water footprint linked to water collection, agriculture, and tourism in the Canary Islands (Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19902, https://doi.org/10.5194/egusphere-egu24-19902, 2024.

EGU24-20643 | PICO | HS7.3

The use of crop models to assess crop production and food security 

Yohanne Gavasso Rita, Simon Papalexiou, Yanping Li, Amin Elshorbagy, Zhenhua Li, and Corinne Schuster-Wallace

The global food supply and food security are altered by field, soil, and weather conditions during crop production. Researching food productivity became crucial as the global population increased. In particular, crop losses bring low food supply and price instabilities at the regional and global levels. With that in mind, we reviewed ten crop models and the most simulated impacts from soil-crop-atmosphere interactions in maize, rice, and wheat production. Since 2012, modellers have mainly used APSIM to predict water availability, temperature changes and Greenhouse Gas  (GHG) concentration to predict crop phenology, growth and development, grain filling and nutrient content, and yield. Since 2013, AquaCrop has been used to simulate scenarios focused on water balance in crop production systems, water stress and irrigation planning. Interestingly, Biome-BGCMuso was developed as a biogeochemical model and was not considered good by crop modellers. However, After updates, version v6.2 can simulate different management and field conditions for fifteen crops, considering heat, nitrogen and drought stress. Since 2008, crop modellers used CropSyst to evaluate water availability, nitrogen use efficiency (UE), temperature shifts and GHG concentration in rainfed and irrigated crop systems. Since 2002,  crop modellers have used DAISY to predict crop growth, nitrogen and water UE, grain content, yield gap, and losses. Since 2011, researchers have used DSSAT-CERES for mitigation strategy planning by predicting crop growth, soil characteristics, changes in land use, and nitrogen and water UE. Since 2015, JULES has been used to determine land-atmosphere interactions, changes in land use and GHG impacts on agriculture. Since 2008, ORYZA modellers have mainly predicted nitrogen and water UE, salinity impacts, and toxicity to rice. STICS was developed in 1996, and since 2008, it has been primarily used to simulate fertilization and irrigation systems, nitrogen leaching, and water availability. Since 2000, researchers have used WOFOST to analyze water availability, crop growth, and productivity under temperature changes. Crop models are fast and reliable resources when simulating crop production and food availability.

How to cite: Gavasso Rita, Y., Papalexiou, S., Li, Y., Elshorbagy, A., Li, Z., and Schuster-Wallace, C.: The use of crop models to assess crop production and food security, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20643, https://doi.org/10.5194/egusphere-egu24-20643, 2024.

EGU24-20876 | ECS | PICO | HS7.3

Application of Machine Learning Approaches for Cotton Seasonal Yield Estimation  

Lisa Umutoni, Vidya Samadi, Jose Payero, Bulent Koc, and Charles Privette

Estimating crop yield can help farmers plan for equipment, labor, and other crop production input requirements. Forecasting crop yield is also useful for analyzing weather-related variability to guide decisions such as irrigation water and fertilizer management. This work discusses the application of Gated Recurrent Unit (GRU) and Long Short-Term Memory (LSTM) machine learning algorithms for seasonal cotton yield prediction. Simulation results from the crop model AquaCrop, consisting of irrigation depth, soil moisture content, and crop growth stage data from 2003 to 2021 were used to train the algorithms. The two developed yield-prediction models were tested against data collected from an irrigated cotton field located at Clemson University Edisto Research and Education Centre (EREC), near Blackville, South Carolina, USA during the 2023 growing season. The values of hidden layers, hidden units, dropout, learning rate and batch size hyperparameters were set to respectively, 3, 64, 0.2, 10E-3 and 64 for the GRU model and 3, 128, 0.4, 10E-3 and 64 for the LSTM model. Analysis suggested that the tested algorithms resulted in very good to excellent performance. We concluded that machine learning algorithms are useful tools that can provide insights into how much yield to expect in an upcoming season and help farmers optimize energy, water, and fertilizers applications.

How to cite: Umutoni, L., Samadi, V., Payero, J., Koc, B., and Privette, C.: Application of Machine Learning Approaches for Cotton Seasonal Yield Estimation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20876, https://doi.org/10.5194/egusphere-egu24-20876, 2024.

EGU24-21145 | ECS | PICO | HS7.3

Climate Risk and Vulnerability Assessment (CRVA) for the Port of Heraklion in Greece  

Anastasios Perdios, Antonios Boutatis, Andreas Langousis, Panagiotis Biniskos, Eva Kypraiou, Konstantina Korda, and Alexandros Zacharof

Climate change is expected to impact the maritime sector, including the port industry. Ports are on the frontline when it comes to experiencing operational challenges from the increased sea levels and extreme weather conditions, associated with increased infrastructure investments. For instance, rising sea water levels are expected to change the accessibility of channels and increase the need for higher quay walls, while the increased intensity or/and frequency of events, such as fog, high winds, and waves, may increase the frequency of port operation disruptions; but changes are uncertain, and with regional variation.

The present study focuses on the Port of Heraklion, one of the main ports of national importance in the Greek Maritime Network, located in the North side of the island of Crete, and aims at assessing the impacts of climate change on port operations associated with: 

  • Changes in mean sea level, storm surges and wave characteristics (i.e. wave height, period, frequency of occurrence).
  • Reduced visibility caused by intense precipitation and/or fog.
  • Disruption of port operations due to high wind speeds, drainage system induced flooding, as well as river discharges and sediment transfer in the harbor basin.

To assess the effects of climate change on winds we use climate change factors (CCFs) obtained using climate model data at 3-hourly temporal resolution over the Island of Crete (i.e. sub-country level) from EURO-CORDEX ensemble, and more in particular from HIRHAM5 RCM (Regional Climate Model) nested in (downscaled from) EC-EARTH GCM (Global Climate model), for two Representative Concentration Pathways of future emissions: RCP 4.5 for the period 2071-2100 and RCP 8.5 for the period 2041-2070. These are also the RCM-GCM combination and time periods used to assess the effects of climate change on the sea state and wave characteristics.

For rainfall, we make direct use of the climate change factors reported in the context of SWICCA program (Service for Water Indicators in Climate Change Adaption, 2015 - 2018), which was financed by the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the European Copernicus Agency within the framework of the Copernicus climate change service (C3S). Over the island of Crete, the corresponding factors are available for 9 GCM - RCM combinations (i.e. 5 for the RCP 4.5 scenario and 4 for the RCP 8.5 scenario).

We find that the increase of the mean sea level, as well as the increase in the frequency of intense storms significantly affect the frequency of port operation disruptions, particularly due to breakwater overtopping, storm induced flooding, as well sediment deposition in the harbor basin.

Acknowledgements

The presented work has been conducted under the project Climate Risk and Vulnerability Assessment (CRVA) for the Heraklion Port Authority" (project code: AA 011391-002/CC15302), which has been financed by the EIB under the InvestEU Advisory Hub. 

How to cite: Perdios, A., Boutatis, A., Langousis, A., Biniskos, P., Kypraiou, E., Korda, K., and Zacharof, A.: Climate Risk and Vulnerability Assessment (CRVA) for the Port of Heraklion in Greece , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21145, https://doi.org/10.5194/egusphere-egu24-21145, 2024.

EGU24-1647 | ECS | Orals | NH11.2

Decision-Relevant Climate Storylines: Using Seasonal Decision-Scaling to Identify Flood Changes in Uncertain GCM Trends 

Ted Buskop, Frederiek Sperna Weiland, and Bart van den Hurk

As global climate patterns shift, Europe faces increasing challenges from key risks such as floods. However, translating this knowledge into locally usable risk information presents a significant challenge. A primary reason is the large variability associated with climate projection outcomes, particularly in precipitation patterns. This paper introduces a seasonal decision-scaling approach to identify decision-relevant climate storylines for regional discharge patterns, which are crucial in assessing flood risks. We sample scenarios within the uncertainty space of future projections and employ a statistical weather generator to determine probabilistic flow changes. Through the analysis of flow changes across various climate scenarios, we identify the most impactful seasonal climate parameters. These parameters are then used to cluster Global Climate Models, from which we create a set of decision-relevant climatological storylines for floods. A case study in Latvia demonstrates that river flows depend on only a few key seasonal parameters, indicating that the uncertainty can be effectively captured with a select number of distinct climatological storylines. This study not only simplifies the complexity of analysing future climate risks but also enhances the practicality of climate information at the regional level. Our novel seasonal approach to decision-scaling and the selection of decision-relevant climate storylines can be applied globally in areas where GCMs indicate varying climate trends and can also be used for drought analyses. This methodology leads to simpler climate risk information, thereby fostering improved and more robust adaptation strategies.

How to cite: Buskop, T., Sperna Weiland, F., and van den Hurk, B.: Decision-Relevant Climate Storylines: Using Seasonal Decision-Scaling to Identify Flood Changes in Uncertain GCM Trends, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1647, https://doi.org/10.5194/egusphere-egu24-1647, 2024.

EGU24-1978 | ECS | Orals | NH11.2

Forecast-based attribution for midlatitude cyclones 

Shirin Ermis, Nicholas Leach, Sarah Sparrow, Fraser Lott, and Antje Weisheimer

The widespread destruction incurred by midlatitude storms every year makes it an imperative to study how storms change with climate. The impact of climate change on midlatitude windstorms, however, is hard to evaluate due to the small signals in variables such as wind speed, as well as the high interannual variability in Atlantic storms.

Here, we compare multiple severe midlatitude cyclones with both wind and precipitation impacts using forecast-based event attribution. We use a recent version of the ECMWF IFS ensemble prediction system which is demonstrably able to predict the storms, significantly increasing our confidence in its ability to model the key physical processes and their response to climate change.

The comparably high resolution of our simulations, and the focus on individual case studies are particularly useful for dynamically driven events like storms. Our approach is able to combine a dynamical analysis of the storm in question with an analysis of past and future changes.

Our results confirm trends of increased severity in storm impacts found in climate projections but add reliability to the forecasted structure and impacts of the storm. This indicates that forecast-based attribution is viable for reliable and fast attribution systems.

How to cite: Ermis, S., Leach, N., Sparrow, S., Lott, F., and Weisheimer, A.: Forecast-based attribution for midlatitude cyclones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1978, https://doi.org/10.5194/egusphere-egu24-1978, 2024.

EGU24-2476 | ECS | Orals | NH11.2

TC-induced Increases in Extreme Rainfall over the Northeast United States  

Bor-Ting Jong, Hiroyuki Murakami, and Thomas Delworth

The Northeast US has faced the most rapidly increasing occurrences of extreme rainfall within the US in the past few decades. The latest fully-coupled 25-km GFDL SPEAR simulation, possessing 10 ensemble members, presents a good opportunity to study changes in regional extreme rainfall and relevant physical processes in both current and future climates. The surge in extreme rainfall over the Northeast US since the 1990s is primarily linked to events associated with tropical cyclones (TCs). In a future warming climate, the 25-km GFDL SPEAR SSP5-8.5 simulations project unprecedented rainfall events over the Northeast US, driven by increasing anthropogenic radiative forcing and distinguishable from natural variability, by the mid-21st century. Also, the occurrences of extreme rainfall related to both atmospheric rivers and TCs are projected to increase, even though the number of TC in the North Atlantic is projected to decrease in the 25-km GFDL SPEAR SSP5-8.5 simulations. Factors such as enhancing TC intensity, strengthening TC-related rainfall, or/and westward shift in TC tracks may offset the influence of declining TC numbers in the model projections, leading to more frequent TC-related extreme rainfall over the Northeast US in the future. On the other hand, the increase in extreme rainfall linked to atmospheric rivers is projected to outpace that associated with TCs. Given the distinct spatial patterns of rainfall resulting from atmospheric rivers and TCs, shifts in their relative contributions carry profound implications for risk prevention and mitigation strategies.

How to cite: Jong, B.-T., Murakami, H., and Delworth, T.: TC-induced Increases in Extreme Rainfall over the Northeast United States , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2476, https://doi.org/10.5194/egusphere-egu24-2476, 2024.

EGU24-2771 | ECS | Posters on site | NH11.2

Population exposure to extreme precipitation under a changing climate in Eastern China 

Hemin Sun, Ruozi Yang, and Lin Li

Under the global warming, the frequency of extreme precipitation has increased, and the return period of it has changed. The original extreme analysis method based on stationary theory will underestimate the risk of extreme precipitation. Based on observed hourly precipitation data during 1960 to 2019, a non-stationary frequency analysis of the annual maximum (AM) precipitation for China was conducted, then estimate the difference between stationary and non-stationary estimated return periods using Bayesian inference. After that, projected the extreme precipitation risk under different SSP-RCPs scenarios by the CMIP6 models. The results shown that the trends of 1-, 2-, 3-, 6-, 12-, 24-, 48-, 96- and 168-hr AM precipitation in China are complex. The shorter the duration, the more stations that show an upward trend. For a 20-yr to 100-yr return period of 1-hr extreme precipitation, the difference between the non-stationarity and stationarity extreme precipitation is large, and at the station with the upward trend that a stationary assumption may lead to underestimation of extreme precipitation about 32%; the average difference over 24-hr is relatively small, and the difference at station with downward trend is about -17%~-23%. The difference between the extreme precipitation return period under non-stationarity and stationarity assumption decreases with the extension of the duration, and the uncertainty increases as the return period increases in all conditions. The ensembled GCMs show that the precipitation in the 21st century show a fluctuating upward trend in China. The 100-yr return period of 24 -, 48 -, 96 - and 168-hr extreme precipitation changed differently under different scenarios in the early period (2021-2040), the middle period (2041-2060) and the later period (2081-20100). The area exposed to extreme precipitation with 1995 to 2014 100-yr return period under different scenarios varies greatly, among which SSP5-8.5 is the largest and SSP1-1.9 is the smallest. In the short, medium and long period, with the increase of extreme precipitation intensity, the exposure area is increasing. Because of the population change, the characteristics of the exposed population and the exposed area are different. In the medium period, the exposed population is also the largest as the population reaches the peak. Under the assumption of a non-stationary climate, the social-economic exposure of extreme precipitation return level and return period providing new methods and scientific information for design, decision-making, and assessing the impacts of climatic events.

How to cite: Sun, H., Yang, R., and Li, L.: Population exposure to extreme precipitation under a changing climate in Eastern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2771, https://doi.org/10.5194/egusphere-egu24-2771, 2024.

The impacts of the western North Pacific (WNP) tropical cyclone (TC) on East and Southeast Asian inland regions are analyzed. Here, based on a stringent TC selecting criterion, robust increase of TC-related inland impacts between 1979 and 2016 over East and Southeast Asian regions have been detected. The storms sustained for 2–9 h longer and penetrated 30–190 km further inland, as revealed from different best track datasets. The most significant increase of the TC inland impacts occurred over Hanoi and South China. The physical mechanism that affects TC-related inland impacts is shortly discussed. First, the increasing TC inland impacts just occur in the WNP region, but it is not a global effect. Second, besides the significant WNP warming effects on the enhanced TC landfall intensity and TC inland impacts, it is suggested that the weakening of the upper-level Asian Pacific teleconnection pattern since 1970s may also play an important role, which may reduce the climatic 200 hPa anti-cyclonic wind flows over the Asian region, weakening the wind shear near the Philippine Sea, and may eventually intensify the TC intensity when the TCs across the basin. Moreover, the TC inland impacts in the warming future are projected based on a high-resolution (20 km) global model according to the Representative Concentration Pathway 8.5 scenario. By the end of the 21st century, TC mean landfall intensity will increase by 2 m/s (6%). The stronger storms will sustain 4.9 h (56%) longer and penetrate 92.4 km (50%) farther inland, thereby almost doubling the destructive power delivered to Asian inland regions. More inland locations will therefore be exposed to severe storm–related hazards in the future due to warmer climate. Long-term planning to enhance disaster preparedness and resilience in these regions is called for.

How to cite: Chen, J., Tam, C.-Y., Chueng, K., and Wang, Z.: Changing impacts of tropical cyclones on East and Southeast Asian inland regions in the past and a globally warmed future climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3003, https://doi.org/10.5194/egusphere-egu24-3003, 2024.

EGU24-3643 | ECS | Orals | NH11.2 | Highlight

Storylines of Hurricane Sandy under climate change to assess compound coastal flooding impacts in New York City 

Henrique Moreno Dumont Goulart, Irene Benito Lazaro, Karin van der Wiel, Linda gavras-van Garderen, Dewi Le Bars, Elco Koks, and Bart van den Hurk

While high impact weather events pose considerable challenges to society, we have limited understanding of their risks and potential impacts due to their rare nature. Climate change, in combination with internal climate variability, increases the uncertainty around these events and their impacts in the future. Storylines offer a non-probabilistic approach into estimating and understanding such events and their impacts conditioned on specific assumptions and scenarios, such as climate change and internal climate variability. Our study presents storylines of Hurricane Sandy (2012) to assess compound coastal flooding's impact on New York City's critical infrastructure under different scenarios. These include the effects of climate change, such as changes in storm dynamics and sea-level rise, as well as internal climate variability, accounting for variations in storm intensity and location. We use a comprehensive modelling framework, spanning from the driving climatological conditions to compound flooding and societal impacts. Our findings indicate that a 1m sea level rise could increase flood volumes by an average of 4.2 times, while internal climate variability could lead to a 2.5-fold increase in flood volumes. We find that impacts on critical infrastructure depend not only on flood volume, but also on the predominant flood hazard in each storyline, like storm surge or local precipitation. This study highlights the importance of developing societal-relevant scenarios that consider both climate change and internal variability. Such scenarios, coupled with a comprehensive modelling framework, provide useful information for decision making when preparing for high impact events in the future.

How to cite: Moreno Dumont Goulart, H., Benito Lazaro, I., van der Wiel, K., gavras-van Garderen, L., Le Bars, D., Koks, E., and van den Hurk, B.: Storylines of Hurricane Sandy under climate change to assess compound coastal flooding impacts in New York City, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3643, https://doi.org/10.5194/egusphere-egu24-3643, 2024.

The study focuses on the distribution of landslide susceptibility in the future under climate change in the Laonong river watershed (abbreviated as LRW) in southwestern Taiwan. LRW is a mountainous watershed prone to sediment disaster and had caused serious sediment disaster during 2009 Typhoon Morakot. The study used the downscaled daily rainfall data provided by Taiwan Climate Change Estimation Information and Adaptation Knowledge Platform (TCCIP) as the daily rainfall data in the future in LRW. We combined the daily rainfall data and the landslide susceptibility model in the LRW to assess the distribution of landslide susceptibility in the future in the LRW.

The landslide susceptibility model was composed of 9 landslide-related factors, including elevation, slope, aspect, geological setting, landuse, Topographic Wetness Index, distance from the rivers, landslide frequency, and daily rainfall. This study built the landslide susceptibility model of LRW based on the daily rainfall data and landslide inventory after 2009 Typhoon Morakot. The AUC (area under receiver operating characteristic curve) of the landslide susceptibility model is 0.712, and the accuracy by using the confusion martix is 0.731.

The study also compared the rainfall characteristic in the past (the rainfall data from 1998 to 2022) and the future (the downscaled rainfall data from 2023 to 2100) in the LRW. No significant difference shows between the characteristic of average annual rainfall in the past and the future, but the monthly rainfall is obviously concentrated in the rainy season, i.e. from May to October. The occupied percentage of accumulated rainfall in the rainy seasons to annual rainfall in the future is larger by 0.3% to 4.1% than that in the past. The daily rainfall with 50 years return period in the future is larger by 56% to 125% than that in the past.

The study combined the daily rainfall data in the future under climate change scenarios SSP126 and SSP585 and the landslide susceptibility model based on 2009 Typhoon Morakot to assess the distribution of landslide susceptibility in the LRW in the future. The area of middle-high and high landslide susceptibility in the LRW increased obviously based on the distribution of landslide susceptibility in the future under climate change. The average landslide susceptibility value in the future in the LRW is larger by 1.7 times than that in the past.

How to cite: Wu, C.: Assessment of Landslide Susceptibility under Climate Change in the Laonong river watershed in Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3729, https://doi.org/10.5194/egusphere-egu24-3729, 2024.

Boreal summer circulation over the Eastern Mediterranean is characterized by background subsidence, which is linked to both mid-latitude wave activity and to convective activity generated in the tropical belt. Background subsidence is accompanied by northerly winds over the Aegean Sea and the Eastern Mediterranean basin, which bring cooler air from the Eurasian landmass towards the Middle East and northeast Africa. These winds, also known as Etesians, can thus mitigate heatwaves in the region. Using the Peter and Clark momentary conditional independence (PCMCI) algorithm, the causal drivers of the Etesians have been identified (Di Capua et al. in preparation). This set of causal drivers consists of (i) Rossby waves propagating from North America via the North Atlantic and (ii) convective activity over the Indian summer monsoon (ISM) region, which affects the Eastern Mediterranean circulation via a geopotential height ridge forming over the Middle East. In this new work, the aim is first to quantify the effect of enhanced Etesians in mitigating heatwaves in the Middle East. Secondly, given the causal pathway identified between the Etesians and the ISM, the aim is to quantify the effect of interannual ISM activity as a potential amplifying (or inhibiting) factor of heatwaves activity. As future projection under different anthropogenic global warming scenarios predict an intensification of rainfall activity in the ISM region, it is crucial to understand how the ISM-Mediterranean teleconnection can affect heatwave activity in the Eastern Mediterranean.

 

Di Capua G., Tyrlis E., Matei D., Donner R. “Tropical and mid-latitude causal drivers of the summer Etesians in the eastern Mediterranean” (in preparation)

How to cite: Di Capua, G.: Indian summer monsoon as a driver of summer heatwaves in the Eastern Mediterranean , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5266, https://doi.org/10.5194/egusphere-egu24-5266, 2024.

How can we best apply our science to predicting risks of extreme behaviour in a system as complex as the climate? It would be desirable to be able to represent all of our knowledge about the risks so that it can be applied to enable effective decision-making. Risk assessments often consider only the range of behaviour displayed by climate models, but a substantial part of the risk seems likely to be due to the possibility of the real world veering outside this range. It will be illustrated how implicitly ignoring this component would lead to risks being systematically underestimated, and how multi-model and initial condition large ensembles can be misleading. Recent work on storyline methods has illustrated potential ways to think beyond numerical model simulations, but downplays the quantification of event risks. But since we generally lack clear bounds on how intense extreme events can be, this seems to leave open the question of just how intense should the events be that are considered in analyses. It also does not seem to satisfy decision analyses that seek to quantitatively trade off protection against extremes against other benefits. This presentation considers how we can go beyond counting events in simulations, using tools such as climate models to inform our future projections without being constrained to ignore possible outcomes that they cannot simulate, whilst also retaining as much quantitative knowledge about event risks as possible and acknowledging when ambiguities become very large. Frameworks from philosophy and decision analysis will be surveyed and it will be discussed how these may help to show a way forward in our climate prediction predicament. It will be suggested that climate science should aim to be pluralistic in the knowledge frameworks it considers, to be of use to the broadest possible range of decision making.

How to cite: Watson, P.: Frameworks for considering extreme weather risks in future climates given major uncertainties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5428, https://doi.org/10.5194/egusphere-egu24-5428, 2024.

EGU24-6217 | ECS | Orals | NH11.2

An outlook into Iberia’s population exposure to hot and dry extreme weather events at the end of the century 

Virgílio A. Bento, Daniela C.A. Lima, and Ana Russo

Climate change is a pressing concern impacting contemporary society, with anticipated global warming trends poised to exacerbate environmental challenges. This study explores the implications for the Iberian Peninsula (IP) at the close of the 21st century, exploring the effects of warming and drying trends on population exposure to hot and dry extreme weather events (HDEs). Despite a potential decline in overall population across the IP, warming and drying trends are expected, as highlighted by various studies. Projections indicate increased temperatures and aridity, and a surge in the frequency and intensity of droughts and heatwaves.

For this research, two EURO-CORDEX experiments (13 simulations RCM-GCM (Regional Climate Models – Global Climate Models)) were considered, encompassing different time periods, namely the historical period from 1971 to 2000 and the projected end of the century period spanning 2066 to 2095, aligned with two distinct emission scenarios: RCP4.5 and RCP8.5. The Standardized Precipitation-Evapotranspiration Index (SPEI) is used to quantify the duration of droughts, and the number of hot days is used to quantify warm months. Two representative concentration pathways (RCPs), specifically RCP4.5 and RCP8.5, are employed to delineate distinct greenhouse gas emission trajectories. A weighted multi-variable multi-model ensemble was used with the aim of improving climate simulations and providing reliable projections over the IP.

The findings of this study reveal a notable projected surge in population exposure to both droughts and warm months throughout the entire IP by the close of the century, with climate change identified as the predominant factor for this escalation. Specific regions may undergo a particularly pronounced increase in drought exposure, while instances of exposure to warm months may surpass the 500% mark. Assessment of exposure to future droughts and warm months indicates that climate change plays a predominant role, accounting for a significant percentage of exposure in both Portugal and Spain.

In conclusion, population exposure to droughts and warm months is projected to escalate significantly in the IP by the end of the century, primarily driven by climate change. The study also emphasizes the critical need for mitigation and adaptation strategies to address the potential consequences, particularly in sectors such as water resources, agriculture, human health, and wildfire management. The findings underscore the urgency for regional authorities, policymakers, and society to prioritize adaptation planning and develop a comprehensive understanding of the vulnerabilities and potential strategies to cope with the challenges posed by hot and dry extreme events.

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020), UIDP/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020). This work was performed under the scope of project https://doi.org/10.54499/2022.09185.PTDC (DHEFEUS) and supported by national funds through FCT. DL and AR acknowledge FCT I.P./MCTES (Fundação para a Ciência e a Tecnologia) for the FCT https://doi.org/10.54499/2022.03183.CEECIND/CP1715/CT0004 and https://doi.org/10.54499/2022.01167.CEECIND/CP1722/CT0006, respectively.

How to cite: Bento, V. A., Lima, D. C. A., and Russo, A.: An outlook into Iberia’s population exposure to hot and dry extreme weather events at the end of the century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6217, https://doi.org/10.5194/egusphere-egu24-6217, 2024.

EGU24-6242 | ECS | Orals | NH11.2 | Highlight

Global warming increases the proportion of more damaging heat extremes 

Yinglin Tian, Axel Kleidon, Corey Lesk, Sha Zhou, Xiangzhong Luo, Sarosh Alam Ghausi, Guangqian Wang, Deyu Zhong, and Jakob Zscheischler

Extreme heat events often result in considerable harm to both ecosystems and human populations. Heat extremes arise from diverse processes, resulting in heatwaves with distinct characteristics and therefore potentially strongly varying impacts and trends. Relying on the surface energy balance decomposition of temperature, we categorize terrestrial summer heat extremes from 1979 to 2020 into four types: Sunny-humid (36.5%), Sunny–dry (24.5%), Advective (25.0%), and Adiabatic (14.0%). Sunny-humid and Sunny-dry heat extremes are characterized by high-pressure systems and diminished cloud cover, resulting in heightened solar radiation. However, they diverge concerning soil moisture and latent heat fluxes. Conversely, the latter two types emerge from advective heating due to anomalies in the horizontal wind and adiabatic heating from air subsidence, respectively. Both are correlated with an upsurge in downward longwave radiation. Sunny-dry and Advective heat extremes lead to more detrimental effects on terrestrial ecosystem production (reducing net ecosystem uptake by 0.09 gC/m2/d and decreasing maize yield by 7.6%) and human health (raising the thermal stress index by 8.6 K and increasing human mortality by 3.3%), respectively.

State-of-the-art climate models (CMIP6) generally replicate the relative proportions and the geographical distributions of the four types of heatwaves but tend to underestimate the Advective heatwave days. Under a high emission scenario (SSP585), the proportion of Sunny-dry and Advective heat extremes increases by 3.4% and 1.5%, respectively, while Sunny-humid and Adiabatic heatwave days decrease by 3.2% and 1.7%, respectively. This suggests, on top of the already expected increase in heatwaves, additional heat stress on both terrestrial carbon uptake potential and human populations. Our findings underscore the importance of distinction among different types of heat extremes and their impacts, paving the way to develop tailored adaptive.

How to cite: Tian, Y., Kleidon, A., Lesk, C., Zhou, S., Luo, X., Alam Ghausi, S., Wang, G., Zhong, D., and Zscheischler, J.: Global warming increases the proportion of more damaging heat extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6242, https://doi.org/10.5194/egusphere-egu24-6242, 2024.

EGU24-7321 | ECS | Posters on site | NH11.2

Physical Drivers and Future Risks of the 2014-like Southeast Asia Drought 

Shuping Ma, Xiao Peng, and Xiaogang He

The Western Malay Archipelago undergoes a severe drought in early 2014, with Singapore experiencing its longest recorded drought period of 62 days from January 13 to March 15, a record dating back to 1929. Here we conduct in-depth analysis to examine the physical drivers of this unprecedented drought. We find that the 2014 drought is primarily due to anomalously high pressure over Southeast Asia. This condition induces the convergence of mid-to-upper level airflows, which then intensifies the subsidence. Simultaneously, the dry and cold airflows from the western and northern continents further exacerbated the subsidence. Anomalous geopotential heights are closely related to the North Atlantic Oscillation (NAO) and the Madden-Julian Oscillation (MJO): during the drought, Atlantic sea temperatures exhibit an abnormal tripole pattern, with the MJO in phases 7 and 8. The wave activity flux analysis show that, the NAO induces an eastward-propagating wave train at mid to low latitudes, leading to suppressed convection over the tropical Indian Ocean and a positive anomaly in geopotential height over Southeast Asia. In addition, we find that the seasonal averaged vertical motion (Omega) and relative humidity (RH) anomaly during 2014 Jan-Mar is unprecedented in the observational record from 1980 to 2020, with a return period of Omega and RH likely (>66% probability) in the range of 43~98 years with a median of 147 years. Climate projections based on the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) models indicate that dynamical component under global warming is the main driver increasing the frequency of 2014-like droughts in the future.

How to cite: Ma, S., Peng, X., and He, X.: Physical Drivers and Future Risks of the 2014-like Southeast Asia Drought, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7321, https://doi.org/10.5194/egusphere-egu24-7321, 2024.

EGU24-7944 | ECS | Orals | NH11.2

Anticipating the unseen: a community review on how to better prepare for exceptional weather events 

Timo Kelder, Lisette Klok, Louise Slater, Vikki Thompson, Henrique M. D. Goulart, Laura Suarez-Gutierrez, Rob Wilby, Dorothy Heinrich, Erin Coughlan de Perez, Liz Stephens, Ed Hawkins, Stephen Burt, Bart van den Hurk, Hylke de Vries, Karin van der Wiel, and Erich Fischer

Extreme weather events of unprecedented intensity in historical records can have major impacts on society and ecosystems. While adaptation plans often consider past trends in extreme weather events, few consider the possibility of exceptional extremes. This oversight leaves society underprepared and ill-equipped to handle ‘surprising’ events. There is a long history of science inquiry into the question of what low likelihood weather events are possible. Here, we present an overview of the methods used to identify exceptional weather events. We discuss tools for scientists, practitioners and policy-makers to ‘see the unseen’ and evaluate unexpected yet plausible disruptive events. We first discuss existing approaches for estimating rare extremes; then give an example for exceptional heat in The Netherlands; and finally outline how this knowledge can be leveraged to strengthen resilience and adaptation efforts.

How to cite: Kelder, T., Klok, L., Slater, L., Thompson, V., Goulart, H. M. D., Suarez-Gutierrez, L., Wilby, R., Heinrich, D., Coughlan de Perez, E., Stephens, L., Hawkins, E., Burt, S., van den Hurk, B., de Vries, H., van der Wiel, K., and Fischer, E.: Anticipating the unseen: a community review on how to better prepare for exceptional weather events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7944, https://doi.org/10.5194/egusphere-egu24-7944, 2024.

EGU24-11146 | ECS | Orals | NH11.2

Projections of the large-scale drivers influencing the North Atlantic tropical cyclones 

Naveen Goutham, Hiba Omrani, Lila Collet, and Carole Legorgeu

Understanding the evolution of tropical cyclones (TC) over the 21st century under a changing climate is essential to improve the resilience of the North American electricity system. In this regard, several studies have projected future changes in TC behavior by detecting and tracking their evolution using climate simulations. One of the key limitations of climate models, specifically attributed to their limited spatial resolution, is that they are unable to simulate all the non-linear interactions between various components of the Earth system. Hence, in this study, instead of tracking TCs in the coarse spatial-resolution climate models, we investigate the evolution of the large-scale drivers influencing the North Atlantic TCs over the mid-future (2041-2060) and far-future (2081-2100). We use five bias-corrected simulations under two shared socio-economic pathway scenarios from the 6th generation Coupled Model Intercomparison Project. In particular, we examine the changes in the large-scale thermodynamic and atmospheric dynamic indicators favorable for TCs, namely sea surface temperature, wind shear, and lapse rate. 

Our results show an increase in the seasonal mean North Atlantic sea surface temperature (between +1 and +3°C), the length of the TC season (between +2 and +5 months), and the ocean heat content (3-6 times) relative to the historical period (1995-2014), while a decrease in the temperature lapse rate (between -0.8% and -1.45%) over both the mid-future and far-future. We find no significant changes in the vertical wind shear under a changing climate. These results suggest an increase in both the frequency and intensity of TCs over the North Atlantic, the latter by 2.6%-5.2% on average. Additionally, our results show a plausible reduction in the conditions favorable for TCs by mitigating from high-emission to moderate-emission scenarios.

How to cite: Goutham, N., Omrani, H., Collet, L., and Legorgeu, C.: Projections of the large-scale drivers influencing the North Atlantic tropical cyclones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11146, https://doi.org/10.5194/egusphere-egu24-11146, 2024.

EGU24-11579 | ECS | Orals | NH11.2

Climate Risk Projections with Pattern Scaling 

Sally Woodhouse, Nicholas J. Leach, Jonathan J. Davies, and James Brennan

The financial sector is becoming increasingly interested in understanding how it is exposed to the risks due to climate change. At Climate X our multi-disciplinary team of hazard and climate scientists work to generate useful projections of risk for a variety of users.

To assess future changes in weather-related hazards we use publicly available climate model outputs from projects such as CMIP and CORDEX. However, these experiments are often not designed with decision-makers and risk assessment at the forefront. Most global climate models are still run at relatively low resolution, whereas decision makers are interested in very local changes (down to asset level). Projects that are run at high resolution, such as HighResMIP and CORDEX, often do not include all the scenarios that decision-makers are interested in and have limited ensemble members.

This talk will explore how the use of pattern scaling can address these limitations. Pattern scaling extracts the signal from local changes in atmospheric variables to global mean temperatures (GMT). It can therefore be used to explore emissions scenarios for which there are limited (or no) GCM runs. This allows us to generate custom scenarios such as global warming levels or a client’s individual projections with only a trend in GMT. Additionally, by extracting temperature uncertainty in the climate sensitivity, local hazard responses and internal variability can be separated.

How to cite: Woodhouse, S., Leach, N. J., Davies, J. J., and Brennan, J.: Climate Risk Projections with Pattern Scaling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11579, https://doi.org/10.5194/egusphere-egu24-11579, 2024.

EGU24-12765 | Posters on site | NH11.2

Assessment of tropical cyclone hazard and risk in a changing climate by means of a new global hybrid model 

Mathieu Boudreault, Roberto Ingrosso, and Francesco Pausata

The future evolution of tropical cyclones (TCs) in a warming world is an important issue, considering their potential socio-economic impacts on the areas hit by these phenomena. Understanding the natural variability and sources of uncertainties over present and future climates and modelling the impacts of TCs remains an important challenge as climate projections do not always provide robust responses about their future evolution. With questions arising about the insurability of coastal communities in the future, risk management requires more robust quantification as to how climate change affects TCs dynamics. It is therefore important to develop TC models that are computationally efficient to provide a full distribution of outcomes for the present and future.

Here, we present a global TC wind model based upon statistical models forced with 10 variables from the 40 members of the Community Earth System Model (CESM) Large Ensemble (LE). The model provides a full description of the frequency, spatial cyclogenesis patterns, tracks and intensities from 1980 to 2060 under the RCP 8.5 emissions scenario. The resulting event sets can therefore be used for risk management in the financial services industry. We find that future frequency of TCs in the North Atlantic is heavily dependent upon how Sea Surface Temperature (SST) and vorticity are accounted for to generate cyclogenesis patterns. Nevertheless, we obtain a larger proportion of Cat. 4-5 storms in the future independently on how SST and vorticity are accounted for with greater intensification along the Gulf of Mexico and the east coast of the U.S. This is consistent with a projected increase (decrease) in the SST (wind shear) over those regions in the CESM-LE. Finally, we find that, especially for Cat. 4+ hurricanes, population growth and climate change should both contribute significantly to the increase in TC risk.

How to cite: Boudreault, M., Ingrosso, R., and Pausata, F.: Assessment of tropical cyclone hazard and risk in a changing climate by means of a new global hybrid model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12765, https://doi.org/10.5194/egusphere-egu24-12765, 2024.

EGU24-13248 | ECS | Orals | NH11.2

On the connection between the jet stream and high-impact, extreme storms in midlatitudes 

Hilla Afargan Gerstman and Daniela I.V. Domeisen

Extreme storms are a major natural hazard in the extratropics. These storms can cause substantial economic damage due to strong winds and flooding, interrupt transportation networks and electricity supply and lead to casualties. Future climate projections predict an extension of the storm track further into Europe posing a potential for increased risk with climate change, especially in winter. However, despite its importance, the connection between extreme, high-impact extratropical storms in midlatitudes and changes in the jet stream remains uncertain. 

Using reanalysis data and multi-model ensemble of climate models under future socio-economic scenarios, we examine the variability of extreme and high-impact storms in the northern hemisphere midlatitude and investigate the connection between jet stream intensity and extreme storm impacts. For this purpose, extreme storm events are diagnosed using the wind field (defined as spatially organized clusters exceeding the 98th percentiles of wind speeds over a specific area for a specific duration). High-impact storms, on the other hand, are identified according to the Emergency Events Database, a global database on natural and technological disasters, for the period 1998 to 2023. This comparison provides insights on extreme storm damage variability in midlatitudes and allows us to explore regional differences in storm damage and future changes. Understanding and connecting the dynamical processes controlling the variability of the jet stream and extreme, high-impact storms in midlatitudes is essential for skillful prediction of these extreme hazards under climate change and for assessing their potentially devastating impacts.

How to cite: Afargan Gerstman, H. and Domeisen, D. I. V.: On the connection between the jet stream and high-impact, extreme storms in midlatitudes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13248, https://doi.org/10.5194/egusphere-egu24-13248, 2024.

EGU24-15240 | Orals | NH11.2

Extreme climatic events and public health in the UK 

Michael Sanderson, Kimberley Eastaugh, Rosa Barciela, and Dan Bernie

Extreme events such as storms, heatwaves and flooding are increasing in severity worldwide owing to climate change. This study evaluates impacts of future projected climate events that could pose a threat to public health in the UK. An aging population means more people will be susceptible to trips and falls during and following extreme climatic events, such as being blown over during high winds. Data from the UK Climate Projections 2018 (UKCP18) were used to analyse daily extreme events for the current climate and assess projected changes in these events during the remainder of the 21st century. The hazards studied are heat and cold waves, heat stress related events, extreme precipitation and extreme wind speeds and gusts. The use of the latest convection-permitting climate model simulations (2.2 km resolution) from UKCP18 allows better simulation of localised events which could lead to differing levels of impact on public health across the UK. Under a high emission scenario (RCP8.5), extreme heat and precipitation events are projected to increase in frequency (and in some cases duration) throughout the 21st century. Alternately, extreme cold and cold wave events could reduce in frequency, although extreme cold events could still occur and thus monitoring annually would be advised. Little change is projected in extreme wind speeds and gusts. Many of the existing hazards that the UK is already vulnerable to are therefore likely to increase in severity in most cases, which therefore escalates the threat to public health. Although this study focuses on public health in the UK, a similar approach could be used for hazards in other countries.

How to cite: Sanderson, M., Eastaugh, K., Barciela, R., and Bernie, D.: Extreme climatic events and public health in the UK, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15240, https://doi.org/10.5194/egusphere-egu24-15240, 2024.

EGU24-15708 | ECS | Orals | NH11.2

Towards a storyline approach for examining future flood risk: A Central American case study 

Jennifer Dentith, Paul Young, Valeriya Filipova, James Butler, Anya Hawkins, David Leedal, Meredith Pascoe, Kirsty Styles, and Andrew Walkden

Climate change will impact the probabilities of different weather conditions and make new weather conditions possible, with implications for societal exposure to extreme weather hazards. While there is agreement that the frequency and intensity of many hazards will increase at the global scale, there is uncertainty in the spatial distribution of the changes, which needs to be considered in assessments of future extreme weather risk. Typically, this uncertainty is quantified by exploring the range of hazard intensities across a climate model ensemble for a given climate forcing. An alternative approach is to consider the range of atmospheric circulation changes across an ensemble – the driver of much of the relevant uncertainty – and extract a limited set of “physical storylines”. Rather than viewing an ensemble as a continuum of possibilities from which percentiles can be drawn, this physical storyline approach identifies “scenarios within scenarios”, thereby enabling risk modelers to work with more tractable amounts of climate data, end users to explore a “plausible worst case”, and scientists to focus their efforts on which circulation changes might be most likely.

Here, we demonstrate a prototype storyline approach for future flood risk in Central America. We consider how the frequency and intensity of flooding might change by using a pattern-scaling approach to extract the climate signal from climate model output. As a first step towards quantifying the uncertainty in our future flood risk data, we use output from three CMIP6 models that span the range of climate sensitivities and provide different flood storylines for Central America because of their distinct precipitation and temperature trends. We show how return periods for precipitation and streamflow may change under a range of policy-relevant global warming levels, providing useful insights about future surface water and river flooding for the financial, insurance, and development sectors.

How to cite: Dentith, J., Young, P., Filipova, V., Butler, J., Hawkins, A., Leedal, D., Pascoe, M., Styles, K., and Walkden, A.: Towards a storyline approach for examining future flood risk: A Central American case study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15708, https://doi.org/10.5194/egusphere-egu24-15708, 2024.

EGU24-17261 | ECS | Posters on site | NH11.2

Severe heat waves in Islamabad and its links with global mitigation benchmarks 

Cristian Zuniga, Peter Pfleiderer, Niels Souverijns, Fahad Saeed, and Carl-Friedrich Schleussner

Anthropogenic climate change encompasses shifts in weather and climate patterns that result in more severe extreme weather events such as tropical storms and heat waves. Observations and climate model simulations show that compound heat waves are becoming more frequent and intense with increasing global mean temperatures. Nevertheless, appropriate local and actionable climate information is scarce and may hinder an adequate adaptation response.

Here, we use a reversal of the traditional impact chain methodology to find emissions constraints that avoid severe heat waves in Islamabad, Pakistan. We use high-resolution urban climate simulations from UrbClim, global climate simulations from CMIP6, and climate simulations from the simple climate model FaIR to estimate local risk threshold exceedances for a large set of emission scenarios. By doing so, we can link specific levels of local climatic impact-drivers to global climate trajectories and assess emission constraints that would avoid severe heat events in Islamabad.

Connecting local risk threshold exceedance to global emission benchmarks can clarify the benefits of reduced emissions for society and decision-makers. Furthermore, our modeling framework allows to investigate different combinations of heat thresholds with occurrence frequencies and can easily be used to answer specific questions from various stakeholders.

How to cite: Zuniga, C., Pfleiderer, P., Souverijns, N., Saeed, F., and Schleussner, C.-F.: Severe heat waves in Islamabad and its links with global mitigation benchmarks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17261, https://doi.org/10.5194/egusphere-egu24-17261, 2024.

EGU24-17837 | Orals | NH11.2 | Highlight

Changing risk from extratropical windstorms in Europe 

Jennifer Catto, Matthew Priestley, and Alexander Little

Future projections of European windstorms and the resultant socioeconomic losses are subject to large uncertainties associated with model differences, internal variability, and emissions scenarios. Here we have used a dataset of objectively identified extratropical cyclones from reanalysis and a multi-model ensemble of climate models under different future warming scenarios. We have applied two storm severity indices; one that is only a measure of the severity of the windstorms; and one that takes into account the population (and its projected future changes) to better understand projections of losses from windstorms. Over northern and central Europe the storm severity itself more than doubles, but the losses estimated from the population-weighted index more than triple due to projected population increases. We also consider an idealised adaptation scenario, where future damage thresholds are used that take into account the increasing future wind speeds. This indicates that adaptation can only partially offset the increased losses. Considering different emissions scenarios, future increase in risk is reduced when following a lower emissions scenario. We show that to understand the future changing risk associated with European windstorms, there is a need to go beyond physical hazard modelling to consider risk and adaptation from a socio-economic perspective.

How to cite: Catto, J., Priestley, M., and Little, A.: Changing risk from extratropical windstorms in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17837, https://doi.org/10.5194/egusphere-egu24-17837, 2024.

EGU24-18675 | Orals | NH11.2 | Highlight

Future changes in weather and climate hazards to aviation 

Paul Williams, Mark Prosser, and Isabel Smith

The human impacts of weather and climate hazards are usually felt at ground level. Aviation is perhaps unique, however, in the sense that the impacts often occur in the upper atmosphere at cruising altitudes of around 40,000 feet. Anthropogenic climate change is occuring at those altitudes in the upper troposphere and lower stratosphere, too. Weather-related hazards such as turbulence already cause a large fraction of commercial aircraft accidents. This presentation will review how these hazards are changing over time because of the changing climate.

Turbulence currently causes 71% of weather-related aircraft accidents, injuring hundreds of passengers and flight attendants annually and costing hundreds of millions of dollars. Recent evidence shows that clear-air turbulence that is strong enough to lift passengers from their seats has increased by 55% since 1979 over the North Atlantic, with similar increases over the USA and elsewhere. Climate model projections indicate a doubling or trebling in turbulence this strong around the midlatitudes in the coming decades, as the jet streams become more sheared in response to anthropogenic temperature changes at cruising altitudes.

Other weather and climate hazards to aviation that will be reviewed in this presentation include the propsect of more lightning strikes; rising sea levels and storm surges flooding coastal airports with increasing frequency; and warmer air on the runway reducing lift generation and making it more difficult for aircraft to take-off.

How to cite: Williams, P., Prosser, M., and Smith, I.: Future changes in weather and climate hazards to aviation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18675, https://doi.org/10.5194/egusphere-egu24-18675, 2024.

Rising global temperatures have been linked to changes in rainfall patterns and an increase in extreme rainfall-related weather events worldwide. Because of its fluctuating precipitation, Bangladesh, a nation susceptible to natural catastrophes, has experienced and will continue to confront more catastrophic calamities. Among these hazards, drought is a more concerning issue for an agriculture-dependent country like Bangladesh. This study has addressed this issue and analyzed the drought condition for the historical period (1985–2014) and near future (2025–2054) by estimating the SPI index in the north-west region of Bangladesh. In this study, an investigation has been done for future projections under various scenarios, such as SSP-245 and SSP-370, using seven suitable Coupled Model Intercomparisons Project 6 (CMIP6). Also, the SPI index has been predicted using a feed-forward backpropagation algorithm in an artificial neural network (ANN). This study has compared the results from two analyses (7 CMIP6 models) and machine-learning-based predictive output. For this study, the drought index was determined to be the Standard Precipitation Index (SPI) on three timescales: three months, six months, and twelve months. For the analysis, a three-layer artificial neural network model was used. In order to determine the most accurate predictive model for the SPI, this model was trained utilizing the SPI timescales with varying lag durations. The correlation coefficient indicated a high accuracy range (75%–85%) in predictive values, demonstrating the model's effectiveness. Additionally, the comparison of observed versus predicted curves for the SPI index across the three timescales also revealed similar trends. The SPI index, derived from 7 CMIP6 models, shows that in the near future, drought events for SSP-370 scenarios are more frequent than SSP-245 scenarios. For the historical period, Chirps precipitation data has been used along with CMIP6 model data, and it has also shown an increasing trend in drought frequencies with time. This study has analyzed the historical and future drought conditions, which can benefit policymakers by improving infrastructure for giving early warning to farmers and taking necessary precautions to protect the losses due to drought.

How to cite: Sarkar, I. and Islam, T.: Comparative Analysis of SPI Index for Drought Conditions in North-West Bangladesh: A Study of CMIP6 Model Data and Machine Learning-Based Predictions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18895, https://doi.org/10.5194/egusphere-egu24-18895, 2024.

EGU24-21161 | Orals | NH11.2 | Highlight

Regional Information for Society within the World Climate Research Programme 

Naomi Goldenson, Bruce Hewitson, Sara Pryor, Silvina Solman, Lincoln Alves, Paul Block, Dragana Bojovic, Louis-Philippe Caron, Alessandro Dosio, Luke Harrington, Kevin Horsburgh, Morten Larsen, and Jemimah Maina

The World Climate Research Programme (WCRP) has created a new core project: Regional Information for Society (RIfS), which has begun to plan its inaugural activities. Recognizing a gap between core disciplinary projects of WCRP and societal impact, RIfS seeks to foster community exchange around the practices of creating and utilizing climate information. The members of the Scientific Steering Group and International Project Office see this as a collaborative process with stakeholders from various sectors of society. Rather than reproducing more climate services, we are focused on identifying best-practices, building worldwide capacity and equity, and contributing to existing projects at the regional scale, particularly in regions where there are limited resources for such services. This RIfS presentation will focus on the identification of best-practices, particularly in the assessment of climate information. Currently there is no systematic, consistent, or accepted approach to assessing which climate information is robust and actionable, at regional or global scales. This recognizes the multiplicity of non-congruent data and information sources that may be used, the choice of which depends often on subjective selections that can lead to different decision outcomes and the commensurate consequences. At the same time, the volumes of data and demand for information are only growing, and new organizations are emerging offering products to decision-makers with varying levels of transparency about methods. Decisions are being made that affect the global distribution of resources, for example in finance and the insurance sectors. No professional organization has so far managed to establish widely accepted standards and guidelines for what constitutes robust information appropriate for various types of decision-making. This is the central challenge of the moment for the community of climate researchers interested in societal applications. RIfS will begin a process of consensus-building with an expert meeting on robustness of climate information just after the EGU meeting this year, to be followed by additional opportunities to come together around these questions.

How to cite: Goldenson, N., Hewitson, B., Pryor, S., Solman, S., Alves, L., Block, P., Bojovic, D., Caron, L.-P., Dosio, A., Harrington, L., Horsburgh, K., Larsen, M., and Maina, J.: Regional Information for Society within the World Climate Research Programme, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21161, https://doi.org/10.5194/egusphere-egu24-21161, 2024.

CL4 – Climate studies across timescales

The estimation of reference evapotranspiration (ETo) holds significant importance for the hydrological cycle, necessitating an extensive understanding of the various climate variables and their influence on ETo variability. This study aims to examine spatio-temporal variations in Penman Monteith based ETo estimations and the factors contributing to their changes over the Indian subcontinent in the historic and future climate change. Using climate variables from the ERA5 reanalysis and CMIP6 simulations this study focuses on the changes in ETo across different aridity zones in the study area. Further, the partial least squares (PLS) regression was employed to determine the relative contribution of different climate variables on ETo trends. Results show that the majority (70%) of the areas in the subcontinent exhibited decreasing ETo trends in the historical past. Zonal analysis of ETo trends revealed all zones except the humid zone exhibited a significant decreasing trend for ETo. Contribution analysis shows that, across the study area, temperature and radiation are the most significant factors influencing ETo, followed by wind speed and relative humidity. Further, temperature and ETo were found to be having opposing tendencies, highlighting an “evapotranspiration paradox” that encompasses the majority of the study area. CMIP6 simulations show that ETo is projected to increase significantly across the Indian subcontinent, especially in the semi-arid and arid regions with temperature and radiation being the dominant factor contributing to increases in ETo.

How to cite: Varghese, F. C. and Mitra, S.: Spatio-temporal variation of reference evapotranspiration and its contributing factors over the Indian subcontinent under historic and future climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-675, https://doi.org/10.5194/egusphere-egu24-675, 2024.

EGU24-878 | ECS | Orals | CL4.1

Land-Climate Nexus: Unravelling Extremes with Attention Networks 

suchismita subhadarsini, D. Nagesh Kumar, and S. Govindaraju Rao

The intricate interplay between land use, climate dynamics, and other contributing factors significantly influences the occurrence of extreme events such as droughts, floods, and heatwaves. Modeling this complex system in a high-dimensional space poses a formidable challenge, given incomplete understanding and limited availability of data. This study explores the application of deep learning approaches, specifically leveraging transformer architectures, to capture long-range dependencies in spatiotemporal data. These mechanisms are then employed to encapsulate the complex interactions between land use, climate, and other factors influencing extreme events. The proposed approach incorporates attention mechanisms, enhancing interpretability by highlighting crucial spatial and temporal features essential for forecasting. To evaluate the effectiveness of this methodology, a case study was conducted on the Godavari River Basin in India. Utilizing vegetation indices as a representation of crop type and land use, alongside climate data spanning from 2000 to 2020, the results provide valuable insights into the driving factors behind land use change and climate extremes in the region. The study not only demonstrates predictive capabilities of the proposed approach but also offers insights into the intricate relationships within the land-atmosphere feedback system. The extracted information is useful for making informed decisions related to land management, climate adaptation, and disaster risk reduction.

How to cite: subhadarsini, S., Kumar, D. N., and Rao, S. G.: Land-Climate Nexus: Unravelling Extremes with Attention Networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-878, https://doi.org/10.5194/egusphere-egu24-878, 2024.

EGU24-1608 | Orals | CL4.1

Forest Canopy Transpiration: A Key Moderator of Hydroclimate Variability and Extreme Rainfall in the Maritime Continent 

Min-Hui Lo, Ting-Hui Lee, Jason Hsu, Chun-Lien Chiang, and Yan-Ning Kuo

This study investigates the interannual variability of evapotranspiration (ET) in the Maritime Continent (MC), focusing on the dynamics behind its minimal fluctuations despite significant changes in precipitation due to the El Niño-Southern Oscillation. We analyze ET components - canopy evaporation (CE), canopy transpiration (CT), and soil evaporation (SE) - and uncover a self-compensating mechanism between CE and CT. During El Niño, increased CT offset decreased CE and SE, maintaining ET's stability. Conversely, La Niña shows an inverse pattern. Additionally, the research examines the impacts of deforestation on extreme precipitation in MC. Deforestation disrupts the ET balance by removing CT's stabilizing effect, amplifying ET variability, and altering precipitation patterns. Our findings propose a new precipitation paradigm in MC under deforestation: "rich-get-richer, poor-get-poorer, and the middle-class-also-get-poorer," marked by increased variability in extreme precipitation events. The study highlights the critical role of MC's forest canopy transpiration in moderating ET variability and its significant influence on the hydroclimatological cycle, especially under deforestation. This intricate interplay between deforestation, ET, and precipitation emphasizes the need to consider both local land use and broader climatic changes in understanding and managing the region's water cycle and extreme climate events.

How to cite: Lo, M.-H., Lee, T.-H., Hsu, J., Chiang, C.-L., and Kuo, Y.-N.: Forest Canopy Transpiration: A Key Moderator of Hydroclimate Variability and Extreme Rainfall in the Maritime Continent, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1608, https://doi.org/10.5194/egusphere-egu24-1608, 2024.

EGU24-1973 | ECS | Orals | CL4.1

Global South most affected by socio-ecosystem productivity decline due to compound heat and flash droughts 

Lei Gu, Erich Fischer, Jiabo Yin, Louise Slater, Sebastian Sippel, and Reto Knutti

Flash droughts (FDs) and heatwaves are posing disproportionate biophysical and social losses worldwide, particularly threatening the disadvantaged communities in the Global South. However, the underlying physical mechanisms behind compound heat-flash drought (CHFD) events and their impacts on global socio-ecosystem productivity remain elusive. Here using satellites, reanalysis, reconstructions, and field measurements, we find more dry regions (53%~62%) with above-average ratios of FDs accompanied by extreme heat than humid regions (50%~57%), due to asymmetric effects by synoptic weather systems. The CHFDs associated with strong soil moisture-temperature coupling aggravate the constraint on plant photosynthesis in dry regions, whereas this coupling-related vegetation stress is not significant in humid regions. We further develop a global risk framework that integrates CHFD hazards, population/agriculture exposures, and vulnerability, and find the Global South is the primary region affected by CHFDs, contributing to greater-than-usual carbon uptake reduction, 90%~94% and 76%~86% of risks to world population and agriculture over the past four decades. We reveal the Global South is severely affected by the impacts of CHFDs on socio-ecosystem productivity decline and underscore the importance of efforts to monitor, predict, and mitigate the rise in CHFDs. 

How to cite: Gu, L., Fischer, E., Yin, J., Slater, L., Sippel, S., and Knutti, R.: Global South most affected by socio-ecosystem productivity decline due to compound heat and flash droughts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1973, https://doi.org/10.5194/egusphere-egu24-1973, 2024.

The land-atmosphere coupling is responsible for flash droughts as the reduced soil moisture increases sensible heat and consequently the lifting condensation level, which ultimately reduces convective precipitation. Meanwhile, the decrease in atmospheric humidity increases the evaporation demand, facilitates the drying of the land surface, and triggers flash droughts with rapid onset and devastating impact. However, whether the role of the land-atmosphere coupling is enhanced or weakened under climate change remains elusive, as previous studies are usually based on unconditional analysis without discriminating dry or wet extremes. Here, we start the investigation from a mega-flash drought occurred over the Yangtze River basin in southern China during the summer of 2022. Both the offline high-resolution land surface model simulations and the CMIP6 climate model data are used for the analysis. It is found that high temperature aggravates the 2022 flash drought onset speed and intensity, highlighting the importance of climate warming. Even under natural climate forcings, the land-atmosphere coupling increases the risks of flash drought intensity and onset speed. The synergy of coupling and anthropogenic climate change would further increase the risks. The synergistic effect on the long-term trends of flash droughts is also being explored, shedding light on the mechanism of flash droughts in a changing climate.

How to cite: Yuan, X.: Synergistic effect of land-atmosphere coupling and climate change on flash droughts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2848, https://doi.org/10.5194/egusphere-egu24-2848, 2024.

EGU24-3079 | ECS | Orals | CL4.1

Causal analysis of Heatwaves in India: Impact of Remote Soil Moisture 

Abhirup Banerjee, Armin Koehl, and Detlef Stammer

Heatwaves are a significant threat to human health, agriculture, and infrastructure; particularly in India, where they are prevalent during the pre-monsoon months. May is a critical period for heatwave occurrences, severely impacting the Indian subcontinent. This work delves into the underlying mechanisms driving heatwaves in India, specifically focusing on those that occur in May. Utilizing an intermediate complexity earth system model, PLASIM1, and its adjoint2 for sensitivity analysis3, we systematically investigate the causal role of remote soil moisture in heatwave formation. We find that variations in remote soil moisture significantly influence the strength and duration of pre-monsoon heat waves in India. Our analysis shows that at a lead time of 10-15 days, higher soil moisture particularly over the Middle East, can prolong heatwave conditions over India. On the other hand, high soil moisture over India suppresses the development of heatwaves with no lag. The delayed mechanism of remote soil moisture works through the altered atmospheric circulation patterns induced by heat flux forcing modulated by soil moisture anomalies, leading to enhanced subsidence and reduced moisture transport to India. Our study provides valuable insights into the mechanisms driving heatwaves in India, particularly those in May. These insights are crucial for developing effective early warning systems, enhancing disaster preparedness, and implementing mitigation strategies to reduce the adverse impacts of these extreme events.

1The Planet Simulator (PlaSim): a climate model of intermediate complexity for Earth, Mars and other planets.

2Marotzke, Jochem, et al. "Construction of the adjoint MIT ocean general circulation model and application to Atlantic heat transport sensitivity." Journal of Geophysical Research: Oceans 104.C12 (1999): 29529-29547.

3Köhl, Armin, and Andrey Vlasenko. "Seasonal prediction of northern European winter air temperatures from SST anomalies based on sensitivity estimates." Geophysical Research Letters 46.11 (2019): 6109-6117.

How to cite: Banerjee, A., Koehl, A., and Stammer, D.: Causal analysis of Heatwaves in India: Impact of Remote Soil Moisture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3079, https://doi.org/10.5194/egusphere-egu24-3079, 2024.

Assessing the impacts of anthropogenic land use and land cover change (LULCC) on climate extremes is of public concern, calling for the use of state-of-the-art experiments and datasets to update our knowledge. Here, we used the CMIP6-LUMIP experiment results to depict the realistic LULCC effects on extreme temperature and extreme precipitation over both historical and future periods. We pointed out some interesting findings over the historical period: Approximately 1oC decrease in the maximum temperature, and up to nearly 2oC decrease in the minimum temperature in the mid-high latitude of the North Hemisphere. About 10 annual heatwave days can be avoided by LULCC effects in 10% of specific LULCC-intense regions. Three LULCC-intense regions in the North Hemisphere have experienced cooling effects in intensity, frequency, and duration aspects. The precipitation displayed a clear contrast change between the North Hemisphere (wetter) and the South Hemisphere (drier), especially on light rainy days (R1mm). Results of the future period indicate that the tropical deforestation regions are projected to induce a remarkably hotter and drier trend. However, the climate responses averaged globally to deforestation have no obvious changes due to the colder and wetter compensation responses in other regions. The maximum temperature increase in deforestation regions is prominent in intensity, frequency, and duration aspects, while the drought is mainly manifested by frequency and duration reduction of precipitation. Seasonal cycle of changes in temperature indices can be discovered in the North Hemisphere mid-latitude deforestation region, tropical region shows year-round consistency. Changes in LULCC induced climate extremes are more obvious under the low-emission scenario in general. Our work is devoted to portraying the latest and more realistic picture of LULCC impacts on climate extremes and gives early warning information to policymakers and the public.

How to cite: Zhang, M. and Gao, Y.: Impacts of anthropogenic land use and land cover change on climate extremes based on CMIP6-LUMIP experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4834, https://doi.org/10.5194/egusphere-egu24-4834, 2024.

EGU24-5226 | Posters on site | CL4.1

Using HydroTiles to represent different hydrological regimes in a global Earth System model 

Tobias Stacke, Philipp de Vrese, Veronika Gayler, and Victor Brovkin

Land surface regions that are of crucial importance for climate dynamics, such as Arctic permafrost landscapes, are often extremely heterogeneous. In these areas, hydrological processes and heat fluxes, which are influenced by topographic features on the scale of a few meters, can affect processes such as permafrost thaw over large regions. Despite the emergence of Earth system models that can operate at a resolution down to one kilometer, hydrological heterogeneity at smaller scales is often overlooked. In addition, high-resolution models are computationally intensive, making them unsuitable for the time scales required to study the climate impacts of processes such as permafrost thaw.

In this study, we present an extension to the tiling infrastructure of the ICON Earth system model that enables the representation of different hydrological regimes within individual grid cells. This innovative approach facilitates the representation of lateral water flow connections between different areas within grid cells and the simultaneous representation of different surface water and soil moisture states, such as dry and wet conditions, within a single grid cell. The impact of this improvement is twofold. First, it provides a more accurate representation of surface and soil hydrology. Second, it is expected to improve the representation of land-atmosphere coupling, allowing us to better capture feedbacks across landscapes affected by strong hydrologic contrasts.

By enabling the representation of hydrological features in subgrids through tiles, which we call HydroTiles, we hypothesize that the HydroTiles setup could replicate some features of high-resolution simulations even at lower resolutions. This approach offers the potential to make simulations more computationally cost-efficient. In our presentation, we would like to highlight the advantages and disadvantages of the HydroTile setup compared to high-resolution simulations.

How to cite: Stacke, T., de Vrese, P., Gayler, V., and Brovkin, V.: Using HydroTiles to represent different hydrological regimes in a global Earth System model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5226, https://doi.org/10.5194/egusphere-egu24-5226, 2024.

EGU24-5392 | ECS | Posters on site | CL4.1

Examining the impact of extreme land surface temperature and land cover on heatwave occurrence: The case of MENA region  

Mohammadsaeed asghariian, Parvin Azizi, Milad Aminzadeh, and Nima Shokri

The increase in Land Surface Temperature (LST) in a changing climate is expected to alter the intensity and frequency of heatwaves by shifting the energy partitioning over the land surface. The relationship between LST and hot air temperatures, influenced by land cover and associated changes in surface properties is not fully understood, particularly in dry regions of the world experiencing prolonged droughts. Extremely high LSTs and their projected changes [1] may stress resilience and adaptive capacities of the growing population in the Middle East and North Africa (MENA). We thus investigate the evolution of extremely high LSTs in MENA over the past two decades to identify its coupling with hot air temperatures considering different land cover types. Our preliminary results highlight the difference in warming rates of LST and air temperature across different land covers thus enabling to identify the role of land temperature extremes in triggering heatwave events. We observed that variation of land temperature arising from land cover changes (affecting soil moisture dynamics and surface thermal and radiative properties) may significantly influence the occurrence and the intensity of heatwaves in this region. The study offers valuable insights into the complex interplay between land and air hot extremes that are particularly important in local climate investigations, agricultural practices, and ecosystem functions.

Reference

[1] Aminzadeh, M., Or, D., Stevens, B., AghaKouchak, A., & Shokri, N. (2023). Upper bounds of maximum land surface temperatures in a warming climate and limits to plant growth. Earth's Future, 11, e2023EF003755. https://doi.org/10.1029/2023EF003755

How to cite: asghariian, M., Azizi, P., Aminzadeh, M., and Shokri, N.: Examining the impact of extreme land surface temperature and land cover on heatwave occurrence: The case of MENA region , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5392, https://doi.org/10.5194/egusphere-egu24-5392, 2024.

EGU24-5644 | ECS | Orals | CL4.1 | Highlight

The relationship between forest fragmentation and extreme high temperature 

Ran Du and Yanhong Gao

Warming lead to a surge in extreme climate events, including heatwaves, droughts, flooding, and wildfires. Numerous studies demonstrate that these occurrences have become more frequent, which exerts notable influences on socio-economic development and human health. Besides natural climate changes, land use and land cover changes (LULCC) play a crucial role in shaping extreme climates. As the most extensive land use type globally, forest has experienced great changes since the industrial evolution. Deforestation is one of the most notable global environmental issues. Besides the decrease of the coverage, fragmentation is one of the appearances of deforestation. Many studies have demonstrated that forest distribution shows high agreements with climate regimes generally, however, the relationship between forest fragmentation and extreme climate events remain unclear. This study analyzes the relation between forest fragmentation and main extreme high temperature indices in 2000-2020. Global continental areas are categorized into regions with increased and decreased forest fragmentation index. Regions with increased index, such as the southeast Amazon, Congo Basin, and parts of the Southeast Asia are emphasized. The 11 extreme temperature indices are analyzed responded to the forest fragmentation index change. This study could provide insights for forest management strategies adapting to climate change in the future.

How to cite: Du, R. and Gao, Y.: The relationship between forest fragmentation and extreme high temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5644, https://doi.org/10.5194/egusphere-egu24-5644, 2024.

The Vietnamese Mekong Delta (VMD) is the most productive region in Vietnam in terms of agriculture and aquaculture. Unsurprisingly, droughts have emerged as a persistent concern for stakeholders throughout the VMD in recent decades. In the evolution and intensification of droughts, local feedbacks in the Land-Atmosphere (LA) interactions were considered to play a crucial role. Previous studies mainly focused on the water cycle feedback loop (e.g., soil moisture-evaporation-precipitation) in the LA interactions. However, there is a noticeable gap in the feedback loop of coupled water and energy balances (e.g., soil moisture-sensible heat-precipitation) associated with the anomalies in sensible heat and precipitation. Therefore, deep understanding of the roles of key variables and their inter-relationships in the LA interactions is of great significance for local communities and authorities. In this study, a deep learning model, named Long- and Short-term Time-series Network (LSTNet), was applied to simulate the LA interactions over the VMD. With the ERA5 data as modelling inputs, the role of each key variable (e.g., soil moisture, sensible and latent heat) in the LA interactions over the past decade (2011-2020) was investigated, and the variations of these variables and their inter-relationships in the future period (2015-2099) were also analyzed based on the Coupled Model Intercomparison Project Phase 6 (CMIP6) data. The LSTNet model has demonstrated that the deep learning algorithm can effectively capture the relative importance of key variables in the LA interactions. We found it is crucial to evaluate the effect of coupled temperature and sensible heat on the LA interactions, particularly for the regions that are susceptible to concurrent droughts and heatwaves, as the co-occurrence of dry and hot weather conditions would inhibit the formation of precipitation and intensify the drought severity. Moreover, the decline in soil moisture and the rise in sensible heat under a changing climate are anticipated to further diminish precipitation in the future. This study would not only enhance our knowledge of the feedback mechanisms in the LA interactions during the drought evolution and intensification, but also provide valuable insights for further development and advancement of hydrologic models for drought monitoring and forecasting.

How to cite: Zhou, K., Shi, X., and Renaud, F.: Deep Learning-Based Analyses of Feedback Mechanisms in the Land-Atmosphere Interactions during Droughts over the Vietnamese Mekong Delta, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5756, https://doi.org/10.5194/egusphere-egu24-5756, 2024.

EGU24-6099 | ECS | Orals | CL4.1

How strong is land-atmosphere coupling in global storm-resolving simulations? 

Junhong Lee and Cathy Hohenegger

The debate on the sign of land-atmosphere coupling has not been solved so far. On the one hand, studies using global coarse-resolution climate models have claimed that the land-atmosphere coupling is positive. But, such models use convective parameterizations, which is a source of uncertainty. On the other hand, studies using regional climate models with explicit convection have reported negative coupling. Yet, the large-scale circulation is prescribed in such models, and interactions with the ocean are neglected. In this study, we revisit the land-atmosphere coupling using a global fully coupled storm-resolving simulation that has been integrated at a grid spacing of 5 km over a full seasonal cycle, and we compare these results to a coarse-resolution climate model simulation using parameterized convection. We find that the coupling between soil moisture and precipitation is weaker and more negative in the storm-resolving than in the coarse-resolution simulation. Further analysis indicates that not only the feedback between soil moisture and evapotranspiration but also between evapotranspiration and precipitation is weaker in the storm-resolving simulation, in better agreement with observations. Reasons for the differences will be mentioned.

How to cite: Lee, J. and Hohenegger, C.: How strong is land-atmosphere coupling in global storm-resolving simulations?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6099, https://doi.org/10.5194/egusphere-egu24-6099, 2024.

EGU24-7942 | ECS | Orals | CL4.1

The cooling effect induced by the Three Gorges Reservoir operation in observations and model simulations 

hongbin li, weiguang wang, and giovanni forzieri

The Three Gorges Dam, the world's largest hydropower project, and its impoundment reservoir have notably modified land cover, with potential implications for regional hydroclimate. However, the seasonal dynamic climate feedbacks arising from variations in water body areas managed by the Three Gorges Reservoir (TGR) remains poorly understood. Based on data-driven analysis and regional climate simulations, we depict the impact of the TGR regulation activities on local land surface temperature (LST) and biophysical processes across different spatiotemporal dimensions, determine the spreading extent of this effect to external territories, and further identify the quantitative attributions between regional climate variabilities and the TGR operation. Results indicate that the TGR induces more pronounced daytime cooling from May to October, particularly in June-August (JJA) with -2.41±0.23 K. The influence of TGR on nighttime LST transitions to warming effects in most regions from November to April (NDJFMA). The significantly increased latent heat (LH) from evaporation growth dominates cooling effects, particularly during daytime, while in JJA, the effects of evaporation are constrained to some extent by abundant precipitation. Albedo exerts a comparatively significant dominance on the nighttime LST in NDJFMA. The TGR-induced surroundings LST changes are notably discernible within an approximately 10 km buffer. The simulations amplify the magnitude and extent of the TGR cooling effect. The simulation results reveal significant reductions in LST of 6.08% (-1.42 K, JJA) and 4.58% (-1.04 K, December-January-February, DJF). respectively, TGR-induced LH variations are dominant for cooling (contributions: -52.09% in JJA; -71.98% in DJF, respectively) among the diverse energy components. This study is valuable for providing scientific guidance in reservoir planning under changing climate.

How to cite: li, H., wang, W., and forzieri, G.: The cooling effect induced by the Three Gorges Reservoir operation in observations and model simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7942, https://doi.org/10.5194/egusphere-egu24-7942, 2024.

EGU24-8546 | Orals | CL4.1

Role of infiltration on land–atmosphere feedbacks in Central Europe: WRF-Hydro simulations evaluated with cosmic-ray neutron soil moisture 

Joel Arnault, Benjamin Fersch, Martin Schrön, Heye Reemt Bogena, Harrie-Jan Hendricks-Franssen, and Harald Kunstmann

The skill of climate models partly relies on their ability to represent land–atmosphere feedbacks in a realistic manner, through the coupling with a land surface model. However, these models often suffer from insufficient or erroneous information on soil hydraulic parameters. In this study, the land–atmosphere model WRF-Hydro driven with ERA5 reanalysis is employed to reproduce the regional climate over Central Europe with a horizontal resolution of 4 km, for the period 2017-2020 during which cosmic-ray neutron sensor (CRNS) soil moisture is available at three Terrestrial Environmental Observatories. The soil hydraulic parameter datasets referred to as SoilGrids and EU-SoilHydroGrids, together with Campbell and van Genuchten–Mualem retention curve equations, are used to assess the role of infiltration on modeled land–atmosphere feedbacks. After calibration of the percolation parameter to better capture observed discharge amounts in the observatories, it is found that WRF-Hydro with Campbell and SoilGrids gives the lowest mean temperature and mean precipitation differences compared to the E-OBS product from European Climate Assessment & Dataset, by reducing soil moisture in the rootzone, increasing temperature, and decreasing precipitation through a positive soil moisture–precipitation feedback process. WRF-Hydro with van Genuchten–Mualem and EU-SoilHydroGrids best reproduces CRNS soil moisture daily variations, despite enhanced positive biases that generate a larger proportion of convective precipitation favored over wet soils and spurious discharge peaks. The question remains open whether an infiltration modeling option that better captures CRNS soil moisture dynamics can also lead to a clear improvement of the simulated climate.

How to cite: Arnault, J., Fersch, B., Schrön, M., Bogena, H. R., Hendricks-Franssen, H.-J., and Kunstmann, H.: Role of infiltration on land–atmosphere feedbacks in Central Europe: WRF-Hydro simulations evaluated with cosmic-ray neutron soil moisture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8546, https://doi.org/10.5194/egusphere-egu24-8546, 2024.

EGU24-9084 | ECS | Posters on site | CL4.1

Sensitivity of the simulated regional climate to changes in the prescribed soil type distributions: Insights from Coupled Regional Climate Model EBU-POM 

Irida Lazic, Vladimir Djurdjevic, Ivana Tosic, and Milica Tosic

In previous studies, it was noticed that many high-resolution Regional Climate Models (RCMs) simulations within the state-of-the-art EURO-CORDEX multi-model ensemble tend to overestimate air temperature and underestimate precipitation in summer leading to the so-called summer drying problem. One of the possible and considerable sources of uncertainty in simulated regional climate is the choice of soil texture database and its soil parameter values. This is crucial because soil hydrophysical properties, influenced by such choices, have an impact on soil moisture and therefore affect the partitioning of surface fluxes [1]. These properties among others play a role in controlling the evolution of soil and air temperature, evapotranspiration, runoff, and precipitation. 

To better understand one of the possible reasons for this problem, we performed two simulations with the coupled regional climate model EBU-POM with two different prescribed soil type distributions. One simulation used the soil type dataset derived from the Zobler dataset and in the second simulation, we used FAO/STATSGO dataset. Two 11-year EBU-POM simulations were conducted, spanning the period from 2000 to 2010. These simulations were initiated in 1998, allowing a two-year spin-up time to reduce the impact of initial fields. The area of interest was Central Europe with a focus on Pannonian Basin because previous studies indicated pronounced dry and warm biases during summer and autumn in low-lying areas, especially in south-eastern Europe. 

The soil moisture capacity is influenced by its hydrophysical characteristics, wherein the size of soil grains plays a crucial role. In this investigation, we emphasized and analyzed the significance of soil hydrophysical properties in shaping surface fluxes. We performed the comprehensive analysis with a focus on the most common specific soil category transitions related to changes in soil parameters and bias changes in surface and near-surface variables and fluxes. The main goal of this study is not to inspect the accuracy of the soil texture map but rather to comprehend the impact on modeled surface and near-surface variables when employing one soil texture dataset versus the other. 

On the other hand, Seneviratne et al. [2] suggested that a new transitional zone characterized by strong land-atmosphere interactions shifted northwards to central and eastern Europe as a consequence of global warming. Their findings highlighted that increased temperature variability in this region is mainly due to land-atmosphere feedbacks. Hence, we analyzed bias in surface and near-surface variables and fluxes and their relation to extreme events such as the heat wave occurred in 2007 to determine their influence on heat wave formation.

[1] Dennis, E. J., and Berbery, E. H. (2021). The role of soil texture in local land surface–atmosphere coupling and regional climate. Journal of Hydrometeorology22(2), 313-330.

[2] Seneviratne, S. I., Lüthi, D., Litschi, M., and Schär, C. (2006). Land–atmosphere coupling and climate change in Europe. Nature, 443(7108), 205-209.

Keywords: regional climate modelling, soil moisture, soil texture, land-atmosphere interactions

Acknowledgement: This research was supported by the Science Fund of the Republic of Serbia, No. 7389, Project Extreme weather events in Serbia - analysis, modelling and impacts” - EXTREMES

How to cite: Lazic, I., Djurdjevic, V., Tosic, I., and Tosic, M.: Sensitivity of the simulated regional climate to changes in the prescribed soil type distributions: Insights from Coupled Regional Climate Model EBU-POM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9084, https://doi.org/10.5194/egusphere-egu24-9084, 2024.

EGU24-9091 | ECS | Orals | CL4.1

Analysis of trends in surface energy fluxes under hot conditions using remote sensing products 

Almudena García-García and Jian Peng

Studying land-atmosphere interactions is important for understanding the mechanisms leading to changes in temperature and precipitation extremes. However, the non-conservation of energy and water in most products and their coarse spatial and temporal resolution hamper the study of land-atmosphere feedbacks. The combination of remote sensing data and modelling frameworks allows to greatly improve the spatial coverage and resolution of data products. Here, we investigate trends in surface fluxes over Europe using the new data product generated with the high-resolution land surface fluxes from satellite and reanalysis data (HOLAPS) framework. HOLAPS is a one dimensional modelling framework that solves the energy and water balance at the land surface, providing consistent surface and soil variables derived from remote sensing data and reanalysis products as forcings. The evaluation of the HOLAPS product against eddy covariance measurements shows slightly better results than other ET and H products at daily scales in summer (KGE > 0.0 for ET and KGE > -0.3 for H) and during hot extremes (KGE > -0.15 for ET and KGE >-0.7 for H), while the state-of-the-art products show KGE > -0.49 for ET and KGE > -1.2 for H in summer and KGE > -0.49 for ET and KGE > -1.5 for H during hot extremes. These results together with the 1D conservation of energy and water in the modeling framework makes this product the perfect tool for the analysis of trends in surface energy and water fluxes during the last decades. Preliminary results for the period 2001-2016 reveals a larger increase in the energy reaching the surface during the hottest month of the year than during summer over central Europe and the Mediterranean coast. This extra energy is released as sensible heat over dry areas during the hottest month of the year. In areas where soil water is available, the extra energy available during the hottest month is released as latent heat flux, adding it to the already large latent heat flux during summer. These results support previous analyses indicating an increase of latent heat flux during hot conditions at monthly scales. However, trends at higher temporal resolutions should be examined to improve the robustness of this conclusion. 

How to cite: García-García, A. and Peng, J.: Analysis of trends in surface energy fluxes under hot conditions using remote sensing products, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9091, https://doi.org/10.5194/egusphere-egu24-9091, 2024.

EGU24-11141 | ECS | Posters on site | CL4.1

The drought response of European ecosystem processes via multiple components of the hydrological cycle 

Christian Poppe Terán, Bibi Naz, Harry Vereecken, and Harrie-Jan Hendricks Franssen

Droughts have become more frequent and severe in Europe over the last decade - a trend expected to continue. Recent studies have shown widespread responses of energy, water, and carbon fluxes in ecosystems to single drought years from flux observations. 

However, to better understand how ecosystems react to droughts, we need to gain explicit knowledge about the different factors that influence their response. In this light, it is crucial to associate the influence of droughts on diverse ecosystem types with particular compartments of the hydrological cycle (atmosphere, surface, soil, and groundwater reservoirs). For instance, during a drought, atmospheric dryness might be the dominant factor in arid regions as opposed to dry soils in humid regions.

Here, we use states and fluxes of water and carbon (vapor pressure deficit, surface runoff, soil moisture, and water table depth) from the Community Land Model 5 in a 3 km resolution over Europe from 1995 to 2018 to determine the drought anomalies of ecosystem processes (gross primary production and evapotranspiration). Importantly, we apply a systematic drought concept integrating lags between deficits in a network of multiple sections of the hydrological cycle during a drought.

Our analyses indicate that the dominance of a particular water resource in controlling ecosystem processes converges regionally and is predominantly consistent across drought events. This finding emphasizes using more comprehensive drought indices incorporating time lags and multiple water resources when analyzing ecosystem responses. Lastly, it identifies areas potentially threatened by droughts and their controlling water resource.

How to cite: Poppe Terán, C., Naz, B., Vereecken, H., and Hendricks Franssen, H.-J.: The drought response of European ecosystem processes via multiple components of the hydrological cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11141, https://doi.org/10.5194/egusphere-egu24-11141, 2024.

EGU24-11163 | ECS | Orals | CL4.1

Examining the influence of forest changes on drought across time scales in Europe through multiple regional climate model simulations 

Yan Li, Bo Huang, Chunping Tan, Yi Liu, and Henning W. Rust

Land cover changes, notably forest alterations, have been observed across Europe due to extensive land management policies. These changes have significant influence on local climates through diverse biophysical mechanisms, given the crucial role of forests in the land ecosystem. While modeling studies have emphasized the impact of forest changes on regional temperature and precipitation in recent decades, their effects on drought conditions in this region remain largely unexplored. To address this gap, our study analyzes multiple simulations with regional climate models to comprehensively investigate how forest changes impact drought across various timescales in Europe. Specifically, we explored seven models, each simulated two extreme scenarios: maximum forest coverage and grass coverage in the region. The comparison between extreme forest coverage and grass coverage serves to evaluate the impact of deforestation on drought. The Standardized Precipitation Evapotranspiration Index was chosen as our metric to assess drought conditions. Our findings reveal considerable variation among the models in depicting the response to deforestation in terms of drought, particularly notable in Scandinavia and Eastern Europe. Our results suggest an increase in aridity on the Iberian Peninsula following deforestation. In Scandinavia the response varies during the year: winter months tend toward increased dryness, while summer months display a tendency toward greater wetness post-deforestation. Our primary objectives encompass quantifying the potential impacts of deforestation in Europe, identifying resilient model responses, and unraveling the sources of uncertainty within these simulated impacts. Through a meticulous analysis of model responses across regions and timescales, we aim to offer insights into the nuanced effects of forest change on drought conditions. This exploration is crucial in guiding future land management policies and devising strategies to mitigate potential adverse impacts of deforestation on regional drought susceptibility in Europe. Ultimately, our study seeks to contribute to informed decision-making regarding land use practices and their implications for climate and ecosystems.

How to cite: Li, Y., Huang, B., Tan, C., Liu, Y., and Rust, H. W.: Examining the influence of forest changes on drought across time scales in Europe through multiple regional climate model simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11163, https://doi.org/10.5194/egusphere-egu24-11163, 2024.

Extreme climate events such as droughts and heatwaves significantly impact the stability of ecosystem function and are expected to intensify in the future. The mid-high latitude regions of the Northern Hemisphere (23.5° to 90°N) exhibit pronounced seasonality and are highly sensitive to climate variations. However, further research is needed to understand the vegetation decline and its changing trends driven by extreme hydroclimatic and their compound events in this region. This study, based on multi-source data including NDVI, LAI, and GPP from 1982 to 2015 as vegetation growth indicators, amid to identify vegetation decline during the growing season and explore its temporal trends, and to further reveal the seasonal response. The research supported the importance of drought and high temperature compared to extreme wet and cold conditions. Due to the high frequency, wide impact and long duration of impact, independent low SM dominated the cumulative vegetation decline, followed by low SM and high VPD compound events. High VPD caused stronger negative impacts on vegetation growth than high T and that it was more strongly coupled to SM. We further found a turning point in vegetation decline. Because of the significant increase in VPD and its enhanced coupling with low SM, low SM and its compound events, especially SM- & VPD+ & T+ compound events, led to a significant enhancement of the vegetation decline after about the 21st century. Furthermore, the sensitivity of vegetation growth to extreme hydroclimatic has also significantly increased, with stronger intensity of vegetation decline. Seasonally, early growing season vegetation was more vulnerable (with the strongest continuous decline) due to experiencing the longest duration of negative impacts, while summer vegetation was more sensitive to extreme hydroclimatic, with the strongest intensity. Notably, compound events of high VPD and low SM primarily affected summer vegetation growth. Additionally, there was a significant lag time in vegetation response to extreme hydroclimatic, especially to high VPD and high T. In over half of the regions, the vegetation response to high T and high VPD had a lag time exceeding two months, which may be associated with seasonal legacy. In the context of global warming, further investigation is needed to explore the inter-seasonal connections. This research significantly contributes to a deeper understanding of ecosystem responses to extremes hydroclimatic and its future changes.

How to cite: Du, R. and Wu, J.: The turning point in vegetation decline in the Northern Hemisphere driven by hydroclimatic extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11693, https://doi.org/10.5194/egusphere-egu24-11693, 2024.

EGU24-12392 | ECS | Posters virtual | CL4.1

Heatwaves and Droughts in Europe: A multi-year analysis using MODIS Land Surface Temperature Anomalies 

Foteini Karinou, Ilias Agathangelidis, and Constantinos Cartalis

In recent decades, European societies and ecosystems have faced recurrent extreme temperatures that contribute to a significant number of impacts, such as wildfires, heat-related illnesses, and crop losses. As heat extremes are further projected to increase in frequency and intensity, a better understanding and close monitoring of these events is necessary. In this study, remotely-sensed Land Surface Temperatures (LSTs) from the Moderate Resolution Imaging Spectroradiometer (MODIS) are used to assess recent heatwaves and droughts in Europe (2003 – 2023). Our results reveal that surface heat extremes are intensifying and becoming more frequent. Moreover, a strong coupling is found between surface thermal extremes, heatwaves (based on near-surface air temperatures) and droughts. Finally, surface LST anomalies are investigated in the context of shifts in energy partitioning under heatwaves/droughts, using eddy covariance flux measurements from the Integrated Carbon Observation System network.

How to cite: Karinou, F., Agathangelidis, I., and Cartalis, C.: Heatwaves and Droughts in Europe: A multi-year analysis using MODIS Land Surface Temperature Anomalies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12392, https://doi.org/10.5194/egusphere-egu24-12392, 2024.

EGU24-12955 | ECS | Posters on site | CL4.1

The influence of temperature–moisture coupling on the occurrence of compound hot and dry events over South America: historical and future perspectives 

João L. Geirinhas, Ana Russo, Renata Libonati, Diego G. Miralles, Daniela C. A. Lima, Andreia F. S. Ribeiro, and Ricardo M. Trigo

The strong global warming observed in the past 50 years has intensified the Earth’s water cycle, triggering more frequent and severe rainfall and drought episodes, a trend that is expected to be aggravated in many regions1,2. Consequently, significant changes in the distribution of temperature, precipitation and evaporation are foreseen. Such changes will likely cause disturbances to the physical coupling between temperature and moisture and, ultimately, to the occurrence of compound hot and dry (CDH) extremes, leading to severe environmental and socio-economic impacts3–5. These coupling interactions can be conceptualized by (1) the correlation between temperature and precipitation to characterize atmospheric coupling, and (2) the correlation between temperature and evaporation, as a proxy for land–atmosphere coupling.

Data from ERA5 reanalysis and from a weighted CORDEX-CORE ensemble6 assuming two different emission scenarios (RCP2.6 and RCP 8.5), was used to assess, for seven climate regions in South America, the influence of these coupling interactions on the occurrence of CDH conditions.

Results obtained by applying multivariate regression models for the historical period (1980–2005) demonstrate that the dependence of CDH conditions on these two metrics of coupling varies considerably from region to region. While in some areas of South America a monotonical influence of a particular coupling mechanism dominates, in other regions of the continent a jointly impact of both coupling processes in the occurrence of CDH conditions is present.  We also investigate how the distribution levels of these two coupling processes will change in future due to long-term disturbances expected by climate change in temperature and in the water balance, and how a higher or lower occurrence of CDH episodes can be explained by changes in the type and strength of the dominant coupling mechanism.  

References

  • Chagas, V. B. P. et al. Climate and land management accelerate the Brazilian water cycle. Nat. Commun. 13, 5136 (2022).
  • Donat, M. G. et al. More extreme precipitation in the world’s dry and wet regions. Nat. Clim. Chang. 6, 508–513 (2016).
  • Berg, A. et al. Interannual Coupling between Summertime Surface Temperature and Precipitation over Land: Processes and Implications for Climate Change. J. Clim. 28, 1308–1328 (2015).
  • Miralles, D. G. et al. Land–atmospheric feedbacks during droughts and heatwaves: state of the science and current challenges. Ann. N. Y. Acad. Sci. 1436, 19–35 (2019).
  • Lesk, C. et al. Stronger temperature–moisture couplings exacerbate the impact of climate warming on global crop yields. Nat. Food 2, 683–691 (2021).
  • Lima, D. C. A. et al. A multi-variable constrained ensemble of regional climate projections under multi-scenarios for Portugal – Part I: An overview of impacts on means and extremes. Clim. Serv. 30, 100351 (2023).

Acknowledgments:

JG is grateful to Fundação para a Ciência e a Tecnologia I.P./MCTES (FCT) for the PhD Grant 2020.05198.BD. JG, AR, RMT, and DCAL also thank FCT I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020). AR, RMT, RL, JG and AFSR thank also FCT for project DHEFEUS (https://doi.org/10.54499/2022.09185.PTDC). AR was supported by FCT through https://doi.org/10.54499/2022.01167.CEECIND/CP1722/CT0006. DCAL was supported by FCT through https://doi.org/10.54499/2022.03183.CEECIND/CP1715/CT0004. DGM acknowledges support from the European Research Council (HEAT, 101088405).

How to cite: Geirinhas, J. L., Russo, A., Libonati, R., Miralles, D. G., Lima, D. C. A., Ribeiro, A. F. S., and Trigo, R. M.: The influence of temperature–moisture coupling on the occurrence of compound hot and dry events over South America: historical and future perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12955, https://doi.org/10.5194/egusphere-egu24-12955, 2024.

EGU24-13027 | ECS | Posters on site | CL4.1

Unveiling the influences of soil moisture on moist heat stress extremes: a global assessment using CMIP6 data 

Jingwei Zhou, Dragan Milosevic, and Adriaan Teuling

Soil moisture is a key variable in land-atmosphere interactions, as it affects the partitioning of near-surface energy fluxes and thereby temperature and humidity of the lower atmosphere. Both ambient temperature and humidity play a crucial role in the removal of heat from the human body through direct heat transfer and sweat evaporation, therefore these two factors are commonly used in measuring moist heat stress. As moist heat stress describes the combined effects of temperature and humidity on human health and well-being, understanding the intricate relationship between soil moisture and moist heat stress is crucial for accurately assessing and mitigating moist heat extremes. Whereas the impact of soil moisture on temperature is well understood, previous research has found non-trivial and complex relations between soil moisture and moist heat stress due to humidity feedbacks. We selected two metrics among four widely used metrics which involve both temperature and humidity, indoor and open-air wet-bulb globe temperature, heat index, and humidex, to represent the heat stress in our study. We use different levels to describe the significance of the heat stress and tolerance level among the population.

In this study, we aim to investigate the impacts of soil moisture on moist heat stress at the global scale using the Land Surface, Snow and Soil moisture Model Intercomparison Project (LS3MIP) dataset within the sixth phase of the Coupled Model Intercomparison Project (CMIP6). We use the historical and future simulations from LS3MIP to analyze the spatial and temporal variations of soil moisture-heat stress coupling, and to identify the regions that are most susceptible to moist heat stress. Interactions between soil moisture and moist heat stress tend to be particularly pronounced in hot and humid regions,. These regions are likely to experience more frequent events with higher moist heat stress, posing serious challenges for human health and adaptation.

To our best knowledge, this study is the first to show a global picture of the interactions between soil moisture and moist heat stress using CMIP6 dataset. The pattern of heat stress in relation to soil moisture in perspectives of the time of day, season, and soil moisture regime will be investigated. Our study provides a novel insight into the role of soil moisture in modulating moist heat stress, and highlights the need for more accurate representation of land surface processes and feedbacks in climate models. The findings are crucial for developing effective strategies in managing moist heat stress risks and protecting vulnerable populations.

How to cite: Zhou, J., Milosevic, D., and Teuling, A.: Unveiling the influences of soil moisture on moist heat stress extremes: a global assessment using CMIP6 data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13027, https://doi.org/10.5194/egusphere-egu24-13027, 2024.

EGU24-13484 | ECS | Orals | CL4.1

Seasonal Variability of Deforestation-Induced Warming in the Congo Basin Using Remote-Sensing Data 

Coralie Adams and Luis Garcia-Carreras

Deforestation impacts in the Congo Basin remain significantly understudied compared to other tropical regions. The main driver of Congo Basin deforestation is small-scale industrial agriculture, which leads to the formation of the rural complex; a mosaic patch of deforested land comprising small fields at different stages of regrowth being deforested repeatedly. Transition from primary forest to rural complex may induce lesser changes in albedo, Bowen ratio, and surface roughness than primary forest to cropland, suggesting the impacts of deforestation on temperatures in the Congo Basin will differ from those in other rainforest regions. The Basin's long-term warming trend and possible ongoing drying could exacerbate warming due to deforestation. It is therefore essential that we understand how the specific nature of deforestation in the Congo Basin influences temperatures, and how this is affected by changes in the large-scale conditions driven by global climate change.

In this study, we used MODIS satellite data for LST and EVI, CHIRPS2 for rainfall, and the Global Forest Change dataset for deforestation analysis from 2000 to 2019 to assess how observed deforestation is affecting LST in the Congo Basin and how the deforestation-induced warming varies with climate anomalies, LST and rainfall (SPI), and Δ EVI (deforested EVI – surrounding forest EVI). Due to limited data availability, caused by the prevalence of cloud cover throughout much of the year, our focus narrowed to the most data-consistent dry season (DJF), where land-atmosphere interactions are also likely to be strongest.

We found a linear relationship between cumulative deforestation and warming over deforested land, which varied in intensity by month. A typical 1 km rural complex pixel within the region will warm by +0.33 °C in December, +0.85 °C in January, and +1.54 °C in February, relative to the surrounding forest. We then assessed the cause of the strong seasonal differences by looking at the deforestation-induced warming as a factor of the climate anomalies and Δ EVI. The amount of warming of a typical 1 km rural complex pixel did not show a relationship with the LST anomaly or SPI for the individual months. However, when considering all months collectively, a correlation emerged with the LST anomaly, suggesting a seasonal evolution where the LST anomaly acts as a proxy. We then found a link between the warming of a typical 1 km rural complex pixel and Δ EVI which is present for each month; this partially explains the interannual variability of the results, but it doesn’t explain the seasonal evolution. Comprehensive and high-quality observations are needed over the Congo Basin to fully untangle these relationships. Accurate soil moisture data could be crucial in understanding the pronounced seasonal differences in warming. These findings suggest that even though the rural complex differs from cropland, and might be expected to have a smaller impact, the additional warming can still be substantial (+1.54 °C), although it has a strong seasonal dependency.

How to cite: Adams, C. and Garcia-Carreras, L.: Seasonal Variability of Deforestation-Induced Warming in the Congo Basin Using Remote-Sensing Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13484, https://doi.org/10.5194/egusphere-egu24-13484, 2024.

EGU24-14184 | ECS | Orals | CL4.1

Links between seasonal precipitation intermittency and soil moisture variability 

Woon Mi Kim, Isla Simpson, Clara Deser, Flavio Lehner, and Angeline Pendergrass

Precipitation is an important control of soil moisture on land. Thus, many studies have focused on understanding the influences of mean or total precipitation variability on soil moisture. However, the relationship between precipitation intermittency (the temporal distribution of rainfall events) and soil moisture variability remains largely underexplored. This question requires more attention as climate models are known to be deficient in their representation of precipitation intermittency (PI), and PI is projected to increase in a future warmer climate, potentially affecting soil moisture variability. In this study, we examine the associations between seasonal PI and soil moisture (SM) across the globe in observation-based datasets (ERA5, MSWEP, and GLEAM) and model simulations (CESM2 Large Ensembles – LENS2) for the period 1981–2020. As a methodology to quantify the associations between PI and SM, we use a conditional regression analysis of 10cm soil moisture onto a metric of PI (reverted number of wet days in a season) after the removal of the influence of total seasonal precipitation from each variable. 

The result suggests that in many regions, higher PI leads to decreases in SM under the same amount of seasonal precipitation. These associations are explained by increased runoff under higher PI. Therefore, the spatial patterns of the magnitude and sign of the linkage between PI and SM align with the global patterns of PI-runoff interactions. Additionally, the regions where evapotranspiration (ET)–SM correlations are high (>0.5) present higher SM sensitivity to changes in PI. CESM2 exhibits spatial consistency in the PI–SM associations with ERA5, although noticeable differences exist in the magnitudes of the regression coefficients between the two datasets. In general, the PI–SM associations are weaker in CESM2. This disparity is attributed to the different runoff sensitivity to changes in precipitation and PI. CESM2 exhibits reduced runoff sensitivity to PI than ERA5 over the entire globe. This finding implies that how runoff is modeled and constrained in climate models will affect future projections of soil moisture.

How to cite: Kim, W. M., Simpson, I., Deser, C., Lehner, F., and Pendergrass, A.: Links between seasonal precipitation intermittency and soil moisture variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14184, https://doi.org/10.5194/egusphere-egu24-14184, 2024.

Land-atmosphere interactions are crucial in both weather and climate extremes. Studies have revealed certain large atmospheric circulation patterns such as amplified circumglobal wave 5 and 7 play important role in generating and maintaining surface extremes. These extremes can occur at the same time but different locations, for example in 2010, the wave 5 pattern was the driver for Russian heatwave and Pakistan flooding. But how soil moisture and land-atmosphere interactions affect the climatology states of jetstreams, amplified waves, and hence persistent extremes still remains unclear.

Here, we employ large ensemble simulations from climate model EC-Earth 3 to study the role of soil moisture in affecting large-scale atmospheric circulation for the period of 2009 to 2016. Three sets of experiments (each set has 100 ensemble members) are carried out with perturbed atmosphere-soil moisture interactions and one reference run (100 members) in which the interaction between the atmosphere and the land is fully interactive. We show that atmosphere-soil moisture interactions strongly influence the climatological mean states of atmospheric circulation in the Northern Hemisphere during the summer season (June to August) and especially in July. With the same soil moisture climatology, the reference run showed an overall land warming that led to poleward migration of jet and a more Arctic front jet state.

 Additionally, West Russia is chosen for the case study area as it is a hotspot for both amplified wave 5 and wave 7 heat extremes. We define the long duration heatwave event as near-surface temperature exceeding 30oC for at least eight days. The results show that with the soil-atmosphere interaction, the probability of such events increased from 2.2% to 5.8% for wave 5 and 0.47% to 4.5% for wave 7.

How to cite: Luo, F., Selten, F., and Coumou, D.: The role of soil moisture on summer atmospheric circulation climatology and persistent heatwaves in the Northern Hemisphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14484, https://doi.org/10.5194/egusphere-egu24-14484, 2024.

EGU24-14774 | Orals | CL4.1

Drought Changes Growing Season Length and Vegetation Productivity 

Josh Gray, Eunhye Choi, Mark Friedl, and Patrick Griffiths

Meteorological droughts are increasing in intensity, frequency, and duration due to climate change. These events may have substantial impacts on vegetation productivity that influence the global carbon balance. Effects vary considerably, however, with the intensity of the drought as well as local abiotic and biotic conditions such as vegetation type, soil type, and the timing of the drought. Productivity is primarily reduced because droughts decrease the efficiency with which plants can convert atmospheric CO2 into carbohydrates, largely because of stomatal closure when energy is not limiting. However, another aspect by which droughts can reduce productivity is by shortening the growing season length (GSL). GSL reduction may be particularly pronounced in vegetation communities already sensitive to precipitation variability, in particular, short-rooted grassland and croplands ecosystems. Here, we use evidence from satellite observations of ecosystem activity, meteorological measurements, and data from eddy-covariance flux towers to reveal the impact of several large-scale meteorological droughts on vegetation productivity on natural and managed ecosystems. In particular, we show that the timing of the drought is important, with late droughts being particularly diminishing to productivity. We also demonstrate that while plant physiological responses to drought dominate the reduction in productivity, the diminishment of GSL plays an underappreciated role. These results have wide implications for the future carbon balance under a changing climate, and suggests that ecosystem models could better explain productivity by incorporating the effects of droughts on GSL.

How to cite: Gray, J., Choi, E., Friedl, M., and Griffiths, P.: Drought Changes Growing Season Length and Vegetation Productivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14774, https://doi.org/10.5194/egusphere-egu24-14774, 2024.

EGU24-15546 | ECS | Orals | CL4.1

Challenges in simulating ground surface temperature based on remote sensing land surface temperature over mountain grasslands 

Raul-David Șerban, Giacomo Bertoldi, Paulina Bartkowiak, Mariapina Castelli, and Andrea Andreoli

Ground surface temperature (GST), measured at a depth of around 5 cm below the ground surface, is essential for understanding the climate change impacts in the Earth Critical Zone. Large spatiotemporal variations of GST have been reported in mountain regions due to the heterogeneity of surface cover and topography. This work aims to improve the monitoring of GST using a physical land-surface model driven by satellite-based land surface temperature (LST). In this regard, GST was simulated using the physical GEOtop model at 1500 m elevation in Matsch Valley, north-eastern Italian Alps, from 2014 to 2017 during the phenological cycle, between April and October. The model was forced only by the LST derived from the Terra MODerate resolution Imaging Spectroradiometer (MODIS). The 1-km MODIS LST was first downscaled to a finer spatial resolution of 250-m using data-driven sharpening from random forest algorithm. The simulated GSTs correlate well with the in-situ observations with a Pearson correlation of 0.88 and a coefficient of determination of 0.77. However, the model overestimated the GST for the whole period with a mean bias of 8.72 °C. These overestimations are similar to the differences between in-situ GST and MODIS LST which range from 4.8 to 19 °C with an average of 8.5 °C. They are mainly caused by the low temporal resolution of LST data with only one observation per day which is additionally limited by frequent cloud cover contamination and the low spatial resolution of the MODIS thermal channels. Modelling the damping of the LST signal in the first centimeters of soil to simulate GST in very heterogeneous areas like alpine pastures is still challenging. This is mainly due to the resolution mismatch between ground and remote sensing observations and the poor knowledge of soil and vegetation properties needed to parametrize physical models.

How to cite: Șerban, R.-D., Bertoldi, G., Bartkowiak, P., Castelli, M., and Andreoli, A.: Challenges in simulating ground surface temperature based on remote sensing land surface temperature over mountain grasslands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15546, https://doi.org/10.5194/egusphere-egu24-15546, 2024.

EGU24-16559 | Orals | CL4.1 | Highlight

Assessing extreme temperature volatilities across Germany between 1990 and 2022 

Elisa Jordan, Ankit Shekhar, and Mana Gharun

Climate change causes a global rise in mean air temperature and increased frequency of temperature extremes. Recent studies link sharp temperature changes between consecutive days to increased mortality, reduced economic growth, and negative effects on ecosystems. While climatological analyses predominantly focus on mean temperatures, extreme temperatures have higher impacts on human health. This study assesses the variability of the daily maximum air temperature between two consecutive days (i.e., volatility) across Germany from 1990 to 2022. We used observation-based raster data of the maximum daily temperature assessed volatility regarding: 1) magnitude, 2) seasonality, 3) the direction of temperature change, and 4) trends during the entire period. As changes of land use and land cover have a direct impact on local temperatures, we analysed the land cover changes during the same period and examine its correlation to extreme volatilities.

The results showed a higher magnitude of rapid temperature decreases compared to temperature increases. Extreme volatilities increased with further distance to the coast from north of Germany to south. Overall, abrupt day-to-day temperature changes occurred mostly during the warming half-year (from March to August). During the study period, significant trends of 0.5 °C and 0.2 °C per decade showed a widening range of extreme volatility in spring and autumn. Compared to unchanged areas, changing land cover was predominantly liked to increasing volatilities of up to 0.5 °C. Understanding rapid temperature changes is crucial for climate change mitigation strategies and limiting impacts on human health and on the environment.

How to cite: Jordan, E., Shekhar, A., and Gharun, M.: Assessing extreme temperature volatilities across Germany between 1990 and 2022, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16559, https://doi.org/10.5194/egusphere-egu24-16559, 2024.

EGU24-16729 | ECS | Posters on site | CL4.1

Poleward migration of soil moisture–temperature coupling hotspots under global warming 

Daniel F.T. Hagan, Diego Miralles, Guojie Wang, Alan T. Kennedy-Asser, Mingxing Li, Waheed Ullah, and Shijie Li

Global hotspot regions where soil moisture (SM) constrains temperature changes are expected to migrate and change in intensity under climate change, impacting hydroclimatic events; however, the nature of these changes is still uncertain. Using multiple model outputs from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we assessed potential future changes in the coupling between boreal summer SM and near-surface mean air temperature (T) across the globe under four Shared Socioeconomic Pathways (SSPs, 2015–2100). We find weakening SM impacts on T (SM-T coupling) in semi-arid, low-latitude regions with increasing emission scenarios due to reduced sensitivity of evaporation to SM. However, our results showed intensifying SM-T coupling primarily over humid regions with increasing precipitation yet decreasing SM due to increasing evaporation. We demonstrate that these changes could be linked to the poleward expansion of the Hadley cells and water-limiting conditions, shifting SM controls on partitioning the surface net radiation and subsequently on T under global warming. These results suggest a higher likelihood of extreme hydroclimatic events, such as heatwaves in higher latitudes associated with the SM–T coupling, which could impact food and water security.

How to cite: Hagan, D. F. T., Miralles, D., Wang, G., Kennedy-Asser, A. T., Li, M., Ullah, W., and Li, S.: Poleward migration of soil moisture–temperature coupling hotspots under global warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16729, https://doi.org/10.5194/egusphere-egu24-16729, 2024.

EGU24-17393 | Orals | CL4.1

Investigating the Climate Impacts of Afforestation and Deforestation in Europe via 5 km climate model simulations 

Luca Caporaso, Gregory Duveiller, Matteo Piccardo, Emanuele Massaro, Caspar Roebroek, Mirco Migliavacca, and Alessandro Cescatti

In the context of the European Green Deal framework, understanding the intricate and varied impacts of afforestation and deforestation across different regions is paramount. A complex interplay of environmental factors shapes the resulting climate effects. Evaluating these impacts and their spatial variability is crucial for formulating effective and context-specific climate mitigation and adaptation strategies.

This study takes a comprehensive approach, investigating both local and non-local effects of afforestation and deforestation within Europe, with a specific emphasis on the radiative budget and temperature dynamics.  Utilizing the cutting-edge Regional Climate Model (RegCM5) in conjunction with the Community Land Model version 4.5 (CLM4.5), we conducted simulations at a fine-scale, convective-permitting resolution of 5 km. This granular approach allows for an in-depth understanding of climate dynamics, shedding light on the distinct climate responses to forest cover alterations at various locations.

We conducted three simulations spanning the period 2004-2014: a control run and two scenarios involving afforestation and deforestation.  We concentrated on analyzing climatic changes through variables such as land surface temperature, near-surface air temperature, and the energy fluxes at the Earth's surface and the top of the atmosphere (TOA). Results suggest that afforestation/deforestation can yield substantial impacts on the climate system. It underscores the critical importance of evaluating biophysical effects at a high resolution, emphasizing the need to incorporate such considerations into climate change mitigation strategies.

Recognizing the location-dependent nature of afforestation and deforestation climate impacts, combined with the capabilities of advanced modeling tools, underscores the importance of flexible and adaptable land use planning. The practical implications of our findings extend to policymaking, offering insights that can inform sustainable land use decisions. These insights can guide the formulation of resilient and sustainable land use policies, aligning with the ambitious objectives of the European Green Deal.

How to cite: Caporaso, L., Duveiller, G., Piccardo, M., Massaro, E., Roebroek, C., Migliavacca, M., and Cescatti, A.: Investigating the Climate Impacts of Afforestation and Deforestation in Europe via 5 km climate model simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17393, https://doi.org/10.5194/egusphere-egu24-17393, 2024.

EGU24-17662 | ECS | Orals | CL4.1

Large biases in soil moisture limitation across CMIP6 models 

Francesco Giardina, Ryan S. Padrón, Benjamin D. Stocker, Dominik L. Schumacher, and Sonia I. Seneviratne

Accurate soil moisture representation is crucial in climate modeling, due to its significant role in land-atmosphere interactions. Our study focuses on water storage dynamics and analyzes how soil moisture limitation is represented in simulations from the land component (land-hist experiment) of seven models within the Coupled Model Intercomparison Project phase 6 (CMIP6). We quantified the annual maximum depletion in soil moisture, contrasting model results with observations of terrestrial water storage from the Gravity Recovery and Climate Experiment (GRACE). Our analysis shows that CMIP6 models mostly underestimate these annual extremes in soil moisture reductions, with the Amazon consistently emerging as the most biased region. We further computed the critical soil moisture thresholds and quantified the frequency of soil moisture limitation in CMIP6 simulations, comparing model estimates against solar-induced fluorescence (SIF) and GRACE observations. We found consistent results with the annual maximum depletion in soil moisture, with models almost always overestimating the frequency of soil moisture limitation globally compared to observations. We validated our findings with data from 128 eddy-covariance sites from eight biomes worldwide. Our study illuminates the biases in soil moisture storage and dynamics between CMIP6 models and empirical observations, highlighting the importance of improving the representations of soil moisture and land-atmosphere interactions in Earth System Models.

How to cite: Giardina, F., Padrón, R. S., Stocker, B. D., Schumacher, D. L., and Seneviratne, S. I.: Large biases in soil moisture limitation across CMIP6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17662, https://doi.org/10.5194/egusphere-egu24-17662, 2024.

EGU24-17860 | Orals | CL4.1

The International Soil Moisture Network (ISMN): providing a permanent service for earth system sciences 

Matthias Zink, Fay Boehmer, Wolfgang Korres, Kasjen Kramer, Stephan Dietrich, and Tunde Olarinoye

Soil moisture is recognized as an Essential Climate Variable (ECV), because it is crucial to assess water availability for plants and hence food production. Having long time series of freely available and interoperable soil moisture data with global coverage enables scientists, practitioners (like farmers) and decision makers to detect trends, assess the impacts of climate change and develop adaptation strategies.

The collection, harmonization and archiving of in situ soil moisture data was the motivation to establish the International Soil Moisture Network (ISMN) at the Vienna University of Technology in 2009 as a community effort. Based on several project funding periods by the European Space Agency (ESA), the ISMN became an essential means for validating and improving global land surface satellite products, climate and hydrological models. In December 2022, the ISMN was transferred to a new hosting facility the International Centre for Water Resources and Global Change (ICWRGC) and the German Federal Institute of Hydrology (BfG) in Koblenz (Germany). ISMN data are successfully provided from the new host since then and will be for decades to come as the German government committed to its long-term funding.

This presentation is going to showcase the International Soil Moisture Network (ISMN). Beyond offering comprehensive in situ soil moisture data, ISMN freely disseminates additional environmental variables, including soil temperature, snow depth, snow water equivalent, precipitation, air temperature, surface temperature and soil water potential if they are available from our data providers. With a global reach, ISMN has already accumulated 3000 stations with observations at various depths, while about 1000 stations are updated on a daily basis. Ongoing efforts are concentrated on expanding the database by incorporating additional stations and networks from institutional or governmental sources. Substantial resources are directed towards fortifying the operational system and improve usability to better serve our users. Additional efforts are undertaken to include ISMN in the data-to-value chain by contributing to international initiatives like WMO, FAO and GCOS. One example is the contribution to WMO’s yearly Global State of the Water Resources report.

How to cite: Zink, M., Boehmer, F., Korres, W., Kramer, K., Dietrich, S., and Olarinoye, T.: The International Soil Moisture Network (ISMN): providing a permanent service for earth system sciences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17860, https://doi.org/10.5194/egusphere-egu24-17860, 2024.

EGU24-18231 | ECS | Orals | CL4.1

Summer Drought Prediction in Europe combining Climate Simulations and Remote Sensing 

David Civantos Prieto, Jesús Peña-Izquierdo, Lluis Palma, Markus Donat, Gonzalo Vilella, Mihnea Tufis, Arjit Nandi, Maria Jose Escorihuela, and Laia Romero

The occurrence of droughts is ruled by the interplay of complex processes with very different natures and spatio-temporal scales. Different modes of climate variability, like the North Atlantic Oscillation or ENSO (El Niño-Southern Oscillation), set the prevalence of distinct weather regimes providing sources of predictability at large-scale. On the other hand,  land-atmosphere feedbacks play a crucial role in climate extremes, and particularly, in the evolution and amplification of droughts. However, the weak predictability of the former large-scale variability in the extratropics together with the poor representation of these feedbacks in current seasonal predictive systems lead to a limited capability of predicting droughts months in advance. In this study (part of the AI4Drought project, funded by ESA), we aim to enhance summer drought prediction in Europe from spring conditions by the combination of state-of-the-art climate simulations and remote sensing.

A hybrid model combining climate simulations and high-resolution remote sensing data is proposed to boost the predictability signal at seasonal time-scale through the integration of two machine learning (ML) models. The first model (model-A) enhances large-scale predictability. It consists of a generative model (conditional variational auto-encoder, based on Pan et al., 2022), which is trained with 10.000s years of CMIP6 climate simulations to empirically learn the probability distributions between global spring fields; e.g., sea surface temperatures and 500 hPa geopotential height; and summer drought conditions (SPEI3). A local-scale model for extremes amplification is developed (model-B). A pixel-based (multi-layer neural network) model aims to capture land-atmosphere feedbacks; integrating local conditions from satellite-based products and reanalysis data, e.g. soil moisture (SM), temperatures and NDVI together with information from the large-scale predictions from model-A in order to predict SM anomalies for the whole summer season.

Preliminary results highlight the significance of local conditions in enhancing drought predictions, particularly in the Mediterranean region, where land-atmosphere feedbacks are pronounced. Experiments conducted under ideal conditions, knowing the future large-scale conditions in advance, demonstrate improved prediction skill when local conditions (e.g., soil moisture, NDVI) are included as predictors.

Moreover, a DeepSHAP analysis (eXplainableAI-based method) is performed to understand which are the most important drivers for the local-scale model prediction of summer SM anomalies. As expected, the spring’s SM anomalies are the most important input features; together with the large-scale conditions described by August SPEI-3. Additionally, temperature anomalies have a relatively high importance when predicting summer drought conditions.

This research underscores the potential of a hybrid approach integrating climate simulations and remote sensing data to advance the understanding and prediction of summer droughts in Europe.

How to cite: Civantos Prieto, D., Peña-Izquierdo, J., Palma, L., Donat, M., Vilella, G., Tufis, M., Nandi, A., Escorihuela, M. J., and Romero, L.: Summer Drought Prediction in Europe combining Climate Simulations and Remote Sensing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18231, https://doi.org/10.5194/egusphere-egu24-18231, 2024.

EGU24-18682 | ECS | Posters on site | CL4.1

Uncovering the moisture and heat sources to croplands during agricultural failure events 

Hao Li, Jessica Keune, and Diego Miralles

Dry and hot climate anomalies threaten rainfed agricultural productivity worldwide. Land–atmosphere feedbacks play a critical role during these abnormal weather events; for example, dry soils reduce evaporation and enhance sensible heating over the land surface, thereby amplifying air temperatures and water deficits for crops, consequently leading to agriculture failure. Moreover, these anomalies of moisture and heat upwind can be translated into downwind regions, thus leading to the spatial propagation of crop-adverse climate conditions. 

In this presentation, we analyse precipitation and temperature anomalies associated with crop failure events over the world’s largest 75 rainfed breadbaskets. Then the spatio-temporal origins of moisture and heat over these breadbaskets are determined using a novel atmospheric Lagrangian modelling framework along with satellite observations. Results indicate that upwind and local land–atmosphere feedbacks together cause lower moisture and higher heat transport into these breadbaskets, leading to decreases in yield of up to 40%. By zooming into the Southeastern Australia wheat belt as an example, known for experiencing recurrent droughts and heatwaves, we provide a detailed analysis of the anomalies of water and energy fluxes and atmospheric circulation and their impacts on moisture and heat sources. We find a substantial impact of advection of dry and hot air from upwind terrestrial regions, particularly during crop failure events, i.e., 1994, 2002, and 2006. Persistent high-pressure systems significantly alter moisture and heat imports into the wheat belt during these events, with upwind drought conditions intensifying rainfall deficits and heat stress in the agricultural region.

Our study suggests the potential for upwind land management to mitigate agricultural losses in rainfed, water-limited regions. Further understanding the intricate relationships between upwind and local influences on global breadbaskets, and specific regions like Southeastern Australia, may provide crucial insights for developing adaptive measures to avert food shortages in the face of a changing climate.

How to cite: Li, H., Keune, J., and Miralles, D.: Uncovering the moisture and heat sources to croplands during agricultural failure events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18682, https://doi.org/10.5194/egusphere-egu24-18682, 2024.

EGU24-19126 | Orals | CL4.1

Development of a land model for the next generation MIROC climate model and evaluation of its simulated land-atmosphere coupling 

Tomoko Nitta, Takashi Arakawa, Akira Takeshima, Dai Yamazaki, and Kei Yoshimura

We have been developing Integrated Land Simulator as a land model for the next generation of the MIROC climate model. Using a general-purpose coupler, ILS couples various land component models with minimum modifications and makes a land model independent from the atmospheric model. The major changes from the previous version of the land model in MIROC6 are the method of coupling land and atmosphere, the independent grid system and spatial resolution for the land model, and the river model. In MIROC6, the land model was part of the physical process of the atmospheric model and was run sequentially, but in the new model (MIROC-ILS), the land and atmospheric models are run in parallel. We have confirmed the MIROC-ILS meets the requirements such as water balance closure and computation time. In the presentation, we will show how the changes of land-atmosphere coupling method and coupling frequency affects the simulated atmosphere field.

How to cite: Nitta, T., Arakawa, T., Takeshima, A., Yamazaki, D., and Yoshimura, K.: Development of a land model for the next generation MIROC climate model and evaluation of its simulated land-atmosphere coupling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19126, https://doi.org/10.5194/egusphere-egu24-19126, 2024.

EGU24-19526 | ECS | Orals | CL4.1

Exploring the influence of land-atmosphere interactions on humid heat extremes in a convection permitting model simulation 

Guillaume Chagnaud, Chris Taylor, Cathryn Birch, Lawrence Jackson, John Marsham, and Cornelia Klein

Ambient humidity reduces the ability of the body to cool down through sweating, adding to the heat 
stress caused by elevated air temperature alone. Indeed, humid heat waves (HHWs) are already a threat
for humans, livestock and wildlife, and their impacts are projected to increase with global warming.
HHWs result from the combination of thermodynamic and dynamic processes interacting on a range of 
time and space scales and whose relative importance may vary according to location and time of year.

Africa is one continent where HHWs, defined here as extremes of wet-bulb temperature (Twb), are 
expected to become more important under global warming. Local-scale humid heat extremes may occur 
within more moderate larger-scale events across much of the continent. Yet, climatological 
characteristics of these smaller-scale events such as location and timing (in year and day) are poorly 
documented in the current climate, due to a lack of high-resolution data and research focus. Moreover, 
a comprehensive understanding of their meso- to synoptic-scale drivers is still lacking. Here, we explore 
these two issues using a 10-year pan-African convection-permitting model simulation that explicitly 
resolves land-atmosphere interactions, and particularly those involving moist processes that are 
instrumental to HHWs.

We find humid heat extremes in semi-arid regions occurring in the core of the rainy season, on length 
scales down to a few tens of kilometers. During HHWs, Twb peaks several hours 
later than the climatological peak in the late morning. This diurnal cycle shift is likely due to HHWs 
typically developing in the aftermath of a rainfall event: the resulting positive anomaly in soil moisture 
induces increased latent heat fluxes, low level divergence, and a reduced PBL height, all ingredients
displaying sharp spatial gradients conducive to locally high Twb values. These results have implications 
for the improvement of localized HHW predictability based on local soil moisture conditions, a key step 
towards climate change adaptation through e.g., early-warning systems.

How to cite: Chagnaud, G., Taylor, C., Birch, C., Jackson, L., Marsham, J., and Klein, C.: Exploring the influence of land-atmosphere interactions on humid heat extremes in a convection permitting model simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19526, https://doi.org/10.5194/egusphere-egu24-19526, 2024.

EGU24-20049 | ECS | Orals | CL4.1

Impact of soil moisture data assimilation on short-term numerical weather prediction 

Zdenko Heyvaert, Michel Bechtold, Jonas Mortelmans, Wouter Dorigo, and Gabriëlle De Lannoy

Land-atmosphere (LA) coupling describes the dynamic interaction between the Earth’s land surface and (the bottom of) the atmosphere. This coupling involves the exchange of energy, water, and momentum between the two systems and its strength varies depending on several factors (e.g., season, land cover, topography, and climate zone). Several metrics that quantify the strength of the LA coupling, both physical and statistical, have been developed and explored extensively in the literature.

Coupled systems that model the atmosphere, the land surface, and their interaction require an initialization of both the atmospheric and the land components. For the latter, a land surface model (LSM) is typically spun up in a so-called ‘offline’ manner, i.e., not coupled to the atmospheric model but forced by an atmospheric reanalysis product. So far, little research has focused on the potential impact of satellite-based soil moisture data assimilation (DA) during this spin-up period on the subsequent forecast by the coupled system. However, several studies in the land surface modeling community have demonstrated the potential benefit of soil moisture DA to improve estimates of hydrological variables and land surface fluxes in offline simulations.

In this study, soil moisture retrievals from the 36 km Soil Moisture Active/Passive (SMAP) Level 2 product are assimilated into the Noah-MP LSM with dynamic vegetation, forced by the MERRA-2 atmospheric reanalysis. This is done using a one-dimensional Ensemble Kalman Filter (EnKF) within the NASA Land Information System (LIS). The DA updates the moisture in each of the four soil layers of the LSM. The resulting land reanalysis provides consistent estimates of land surface variables and fluxes from 1 January 2016 through 31 December 2020 on an 18 km grid over the contiguous United States.

This land reanalysis is subsequently used to initialize the land component of an experiment where the Noah-MP LSM and the Weather Research & Forecasting (WRF) atmospheric model are coupled within the NASA Unified WRF (NU-WRF) framework. The atmospheric component is initialized with MERRA-2, which also serves as the boundary condition for the atmospheric model. We compare the results in terms of short-term atmospheric estimates (e.g., of evaporative fraction, growth of the planetary boundary layer, screen-level temperature and humidity) with an initialization that uses a purely model-based land spin-up. 

Our study allows the quantification of land DA impact during spin-up and the assessment of its relationship with the LA coupling strength. The results will provide important insights into where and when short-term atmospheric forecasts may benefit from assimilating satellite-based soil moisture retrievals.

How to cite: Heyvaert, Z., Bechtold, M., Mortelmans, J., Dorigo, W., and De Lannoy, G.: Impact of soil moisture data assimilation on short-term numerical weather prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20049, https://doi.org/10.5194/egusphere-egu24-20049, 2024.

EGU24-5301 | ECS | Posters on site | CL4.2

Seasonal Diversity of Indo-Pacific Warm Pool Volume Expansion: The Role of Climatological Subsurface Temperature Patterns 

Qiuying Gan, Jeremy Cheuk-Hin Leung, Wenjie Dong, Lei Wang, Weijing Li, Weihong Qian, and Banglin Zhang

The Indo-Pacific warm pool (IPWP) expansion under global warming has huge impacts on global climate. While recent studies have revealed the seasonal diversity of IPWP surface expansion and its impacts under greenhouse warming, understanding the changes in seasonality of the IPWP volume is of greater importance, especially given the crucial role of subsurface ocean temperature in climate systems. This poster presents the seasonal diversity of Indo-Pacific warm pool volume expansion.

In this study, we find a significant difference of IPWP volume expansion rate across seasons from 1950–2020, although the oceanic warming is rather seasonally uniform. The expansions of IPWP volume during boreal autumn and winter are faster compared to boreal spring and summer. This consequently weakens the seasonality of IPWP volume, particularly in the upper-layer, with a significant decreasing trend of -0.54×107 km3/decade. Further analyses suggest that this seasonal diversity in IPWP volume expansion is primarily caused by the seasonality of capacity for IPWP volume change, which is determined by the seasonal climatological subsurface temperature pattern over the Indo-Pacific Ocean. Furthermore, these variations may exert varied impacts on the troposphere and East Africa precipitation in rainy seasons. Namely that the larger expansion of IPWP in short rains is more closely related to the enhanced ascending motion and increased precipitation over East Africa, comparing with the long rains. This study emphasizes the crucial impacts of climatic subsurface Indo-Pacific Ocean temperature properties on the change of IPWP volume seasonality, which may have crucial effects on the precipitation in East Africa rainy seasons, and may hold important clues about how greenhouse warming affect oceanic seasonal cycle.

How to cite: Gan, Q., Leung, J. C.-H., Dong, W., Wang, L., Li, W., Qian, W., and Zhang, B.: Seasonal Diversity of Indo-Pacific Warm Pool Volume Expansion: The Role of Climatological Subsurface Temperature Patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5301, https://doi.org/10.5194/egusphere-egu24-5301, 2024.

EGU24-5689 | ECS | Orals | CL4.2

South Pacific hydroclimate response to multi-decadal modes of variability in the IGCM4 climate model 

Daniel Skinner, Manoj Joshi, Adrian Matthews, and Timothy Osborn

The South Pacific Convergence Zone (SPCZ) dominates the climate dynamics of the tropical South Pacific, significantly influencing global climate dynamics. The magnitude, slope, and spatial extent of the SPCZ's precipitation pattern, are responsive to changes in both trade winds and the Southern Hemisphere subtropical jet. These changes are, in turn, driven by modes such as the MJO and ENSO. Whilst the drivers of SPCZ variability on subseasonal to interannual timescales are well-documented, understanding of its variability over multi-decadal to millennial timescales remains limited.

Quantitative reconstructions of South Pacific hydroclimate reveal rapid, and as yet unexplained, changes in the SPCZ over recent millennia that do not align with large-scale climate forcing. This study proposes that large-scale multi-decadal modes of variability may play a crucial role in driving SPCZ variability.

Using an Intermediate General Circulation Model (IGCM4), we investigate the SPCZ's response to sea surface temperature (SST) forcing corresponding to the Atlantic Multi-decadal Variability (AMV) and Interdecadal Pacific Oscillation (IPO). Applying monthly varying SST anomalies at a range of magnitudes and in different combinations, we assess the linearity of the SPCZ response to these multi-decadal modes. Additionally, we explore the pathways associated with each response by applying SST anomalies both globally and within the respective basin.

This research aims to enhance our understanding of the interaction between the SPCZ and multi-decadal modes of variability, providing insights into past changes in the proxy record and contributing to the development of future SPCZ projections.

How to cite: Skinner, D., Joshi, M., Matthews, A., and Osborn, T.: South Pacific hydroclimate response to multi-decadal modes of variability in the IGCM4 climate model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5689, https://doi.org/10.5194/egusphere-egu24-5689, 2024.

EGU24-5817 | ECS | Orals | CL4.2

Indo-Pacific basin interactions and their impacts on Austral-Asian hydroclimate over the last millennium 

Shouyi Wang, Caroline Ummenhofer, Delia Oppo, and Rhawn Denniston

Rainfall associated with the Austral-Asian monsoons affect the livelihoods of over half of the world’s population, yet the impacts of anthropogenic forcings on regional hydroclimate trends in the coming decades remains uncertain. Observation-based studies have found that monsoonal rainfall over Austral-Asia is influenced on interannual-decadal timescales by tropical sea surface temperature (SST) patterns in the adjacent Indian and Pacific Oceans. In recent years, interactions between the tropical Indian and Pacific Ocean (tropical basin interactions) have been recognized as important in understanding Austral-Asian hydroclimate variability. However, instrumental observations are too short to clarify the relationships between Austral-Asia rainfall and Indo-Pacific basin interactions on longer (multidecadal-centennial) timescales.

Here we utilize last millennium climate model simulations, Indo-Pacific SST and hydroclimate multi-proxy (e.g., stalagmites, corals, marine and lacustrine sediments) archives and various climate field reconstruction methods (e.g., composite plus scale, offline data-assimilation) to investigate low-frequency tropical basin interactions over the last millennium. Specifically, we assess whether the zonal SST gradients in the Indian and Pacific Oceans, which reflect basin-wide Walker Circulation strength, are coupled on multidecadal-centennial timescales. Preliminary analysis suggests intervals of decoupling between the two basins which coincided with simultaneous changes in the strength of the Australian and Asian monsoons. These findings provide dynamical insights into interpreting hemispherically in-phase hydroclimate records as well as long-term context for climate-risk management over Austral-Asia.

How to cite: Wang, S., Ummenhofer, C., Oppo, D., and Denniston, R.: Indo-Pacific basin interactions and their impacts on Austral-Asian hydroclimate over the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5817, https://doi.org/10.5194/egusphere-egu24-5817, 2024.

EGU24-6517 | ECS | Posters on site | CL4.2

Bootstrapping Image Histogram for Simplifying Climate Snapshots: Exploring the Application to Indo-Pacific Warm Pool Expansion Research 

Jeremy Cheuk-Hin Leung, Qiuying Gan, Shengyuan Liu, Hoiio Kong, and Banglin Zhang

Thanks to the recent advancements in climate observation methods and numerical simulation performance, there has been a significant increase in the availability climate datasets, which offer finer resolutions and broader coverage of variables than ever before. In contrast to the past, when scientists faced challenges due to limited data, the challenge now lies in extracting meaningful information from high-dimensional climate data. In climate analyses, each timestep of data provides a snapshot of atmospheric/oceanic conditions, analogous to a photograph. In such sense, techniques from the field of computer vision can serve as valuable tools for analyzing these climate snapshots.

This presentation aims to introduce the concept of the Bootstrapping Image Histogram, a fundamental idea in computer vision, and demonstrate its usefulness in simplifying climate snapshots and reducing the dimensionality of climate data. Additionally, given the crucial role of the Indo-Pacific warm pool (IPWP) in driving the global climate system, this presentation also showcases two applications of the Bootstrapping Image Histogram approach to IPWP expansion research, as recently published.

(1) Recent observed weakening of IPWP seasonality: We find that the amplitude of seasonal cycle of the IPWP size has decreased significantly since 1950, despite the sea surface warming being rather uniform across seasons. Analysis results suggest that the climatological spatial pattern of sea surface temperature (SST) over the Indo-Pacific Ocean is the primary factor contributing to the weakening IPWP seasonality. (https://doi.org/10.1088/1748-9326/acabd5)

(2) Overestimated IPWP expansion under greenhouse warming: The IPWP drives the global climate system by consistently supporting and maintaining atmospheric deep convection. For this reason, the IPWP is defined as the region where the SST exceeds a pre-condition necessary to favor deep convection (σconv). Previous conclusions regarding the rapid expansion of the IPWP were based on a constant σconv (typically 28°C). However, our analysis results reveal that σconv is indeed increasing under climate change, which corresponds to a slower IPWP expansion speed. This highlights the necessity of considering the response of the relationship between deep convection and SST to climate change when studying the long-term variability of the IPWP and its impacts on the climate system. (https://doi.org/10.1038/s41612-022-00315-w)

How to cite: Leung, J. C.-H., Gan, Q., Liu, S., Kong, H., and Zhang, B.: Bootstrapping Image Histogram for Simplifying Climate Snapshots: Exploring the Application to Indo-Pacific Warm Pool Expansion Research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6517, https://doi.org/10.5194/egusphere-egu24-6517, 2024.

EGU24-7665 | ECS | Posters on site | CL4.2

Reduced ENSO Variability During the Onset of 4.2ka Event 

Shaohua Dang, Kefu Yu, and Zhongfang Liu

It is widely believed that anomalies in the state of tropical Sea Surface Temperature (SST), manifested as intensified ENSO variability, triggered the collapse of the Northern Hemisphere monsoon that occurred from 4500 to 3900a BP, known as the 4.2ka event. However, explicit records of ENSO variability, including events and variance, during the onset of 4.2ka event were still lacking to show how it changed and related to this climatic event. Here, we present a century-length (104-year) monthly coral record from the South China Sea (SCS) combined with modeling data to show that reduced ENSO variability was associated with an intensified Pacific Walker circulation ranging from 4400 to 4300 years BP, precisely corresponding to the onset of 4.2ka event. We hypothesize that such a mean state of tropical Pacific climate might not have triggered the development of the 4.2ka event, but rather responded to it.

How to cite: Dang, S., Yu, K., and Liu, Z.: Reduced ENSO Variability During the Onset of 4.2ka Event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7665, https://doi.org/10.5194/egusphere-egu24-7665, 2024.

EGU24-8966 | ECS | Posters on site | CL4.2

Reconstructing South Pacific Convergence Zone precipitation over the past 60 ka using plant wax biomarkers 

Mark Peaple, Gordan Inglis, Pete Langdon, Manoj Joshi, Daniel Skinner, Adrian Mattews, Timothy Osborn, William Roberts, and David Sear

Hydroclimate in the tropical South Pacific is dominated by the South Pacific Convergence Zone (SPCZ), a region of low-level atmospheric convergence responsible for providing fresh water to 11 million people. The SPCZ is known to change in orientation and intensity in response to interannual climate phenomena, including El Niño Southern Oscillation (ENSO) and the interdecadal Pacific Oscillation (IPO), principally through modulation of trade wind strength (i.e., Walker circulation strength), and the resultant moisture inflow. Understanding how the orientation and intensity of the SPCZ changed under past climate states is important to predict future SPCZ changes, currently poorly represented in existing GCM’s. However, our knowledge of the dynamics of the SPCZ beyond the last 1000 years is limited by a lack of proxy archives and a large spread in climate model ensembles. We present a 60 ka plant wax record of paleoprecipitation collected from a peat sediment core from the island of Nuku Hiva, French Polynesia, located in the northeastern margin of the SPCZ. We demonstrate that Nuku Hiva was drier during the last glacial maximum (LGM) and wetter during the early Holocene compared to modern conditions. This indicates that the SPCZ was located further to the south during the LGM and further to the north during the early Holocene. We find a strong correlation between our SPCZ precipitation record and foraminifera based reconstructions of western Pacific warm pool thermocline depth. Given that both modern western Pacific thermocline depth and Nuku Hiva precipitation are influenced by easterly trade wind speed, we deduce that trade wind speeds were likely lower during the LGM and higher during the early Holocene, highlighting the long term dependence of SPCZ orientation on Walker circulation strength. This study, will help constrain future predictions of SPCZ precipitation change.

How to cite: Peaple, M., Inglis, G., Langdon, P., Joshi, M., Skinner, D., Mattews, A., Osborn, T., Roberts, W., and Sear, D.: Reconstructing South Pacific Convergence Zone precipitation over the past 60 ka using plant wax biomarkers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8966, https://doi.org/10.5194/egusphere-egu24-8966, 2024.

EGU24-9887 | ECS | Posters on site | CL4.2

Sea surface temperatures across the low-latitude Indo-Pacific Ocean during the Holocene, Last Interglacial and Marine Isotope Stage 11 

Martina Hollstein, Matthias Prange, Lukas Jonkers, and Mahyar Mohtadi

The Indo-Pacific Warm Pool (IPWP) holds the largest warm water body on Earth. With sea surface temperatures (SST) above 28°C, it promotes deep atmospheric convection in the rising limb of the Hadley and Walker circulation cells, and is a major source of heat and moisture to the global atmosphere with far-reaching climate impacts. Spatiotemporal changes in SST influence the location and strength of atmospheric convection and thus the atmospheric circulation. Despite its importance for the global climate, long-term SST variability across the IPWP is not well understood yet. Compilations of proxy-based reconstructions of SST during previous interglacials combined with climate models provide ideal means to study the SST variability in response to varying astronomical forcing. Hitherto, global compilations of interglacial SST anomalies and data-model comparisons have mostly focused on the Holocene and the Last Interglacial (LIG) period. The available studies reveal a striking mismatch between proxy-derived and modelled SST anomalies across low latitudes. However, the data coverage across the low-latitude Indo-Pacific is poor with little to no data from the IPWP. Here, we compare a proxy network of SST anomalies from the low-latitude Indo-Pacific during Holocene, LIG and MIS 11 time slices to the output of CESM 1.2 climate model simulations. We find large discrepancies between the proxy network and CESM output, concerning the magnitude and pattern of SST change including zonal gradients across the tropical Pacific. For instance, proxy data indicate highest SSTs during the LIG, with a slight warming as compared to the preindustrial reference period, while CESM indicates lowest SSTs during the LIG. By performing individual forcing experiments with CESM, we disentangle the roles of astronomical forcing, greenhouse gas concentration and vegetation cover in shaping interglacial tropical SST patterns. In particular, we find that an expanded Northern Hemisphere vegetation cover during interglacials mitigates model-data discrepancies in IPWP temperatures. 

How to cite: Hollstein, M., Prange, M., Jonkers, L., and Mohtadi, M.: Sea surface temperatures across the low-latitude Indo-Pacific Ocean during the Holocene, Last Interglacial and Marine Isotope Stage 11, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9887, https://doi.org/10.5194/egusphere-egu24-9887, 2024.

EGU24-9897 | ECS | Orals | CL4.2

­Drivers of Indo-Pacific upper ocean heat and freshwater variability using a synthesis of coral proxies and ocean models  

Sujata Murty, Caroline Ummenhofer, Shouyi Wang, Laura Gruenburg, Arne Biastoch, and Claus Böning

The Maritime Continent provides pathways for heat and freshwater transport from the Pacific to the Indian Ocean, serving as an important oceanic teleconnection for Indo-Pacific climate. Yet, the short length of robust observational datasets limits examination of past Maritime Continent and Indo-Pacific Warm Pool variability and the resulting implications for Indo-Pacific climate. Coral proxy records allow insights into variability on seasonal to multi-decadal timescales prior to the period of satellite and in situ observations. Here, we synthesize published coral δ18O records, in situ observations, and simulated ocean variability (salinity, temperature, thermocline depth, heat content) from the Nucleus for European Modeling of the Oceans (NEMO) ocean model simulations to explore drivers of seasonal to multi-decadal variability across the Indo-Pacific Warm Pool (western Pacific, Maritime Continent and central Indian Ocean). This proxy-model synthesis allows for examination of thermohaline vertical variability along key oceanic pathways. We identify the role of key climate modes, including the Interdecadal Pacific Oscillation, in driving upper ocean Indo-Pacific variability. The proof-of-concept provided by these results suggest that the paleoproxy records capture important features of regional hydrography and the associated variability in upper ocean heat and freshwater budgets. Such proxy-model comparison at a broader spatial scale is critical for understanding the drivers of variability related to changes in Indo-Pacific oceanic teleconnections over recent centuries and provides important context for projecting future changes in the region.

How to cite: Murty, S., Ummenhofer, C., Wang, S., Gruenburg, L., Biastoch, A., and Böning, C.: ­Drivers of Indo-Pacific upper ocean heat and freshwater variability using a synthesis of coral proxies and ocean models , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9897, https://doi.org/10.5194/egusphere-egu24-9897, 2024.

EGU24-10821 | ECS | Orals | CL4.2

Indian Ocean Dipole, El Niño-Southern Oscillation, and large-amplitude internal waves recorded in Andaman Sea corals during the satellite era 

Hana Camelia, Thomas Felis, Jessica Hargreaves, Martin Kölling, and Sander Scheffers

The Indian Ocean is surrounded by highly populated areas that are susceptible to climate extremes, such as floods, droughts, and heatwaves. Timing and severity of these climate extremes are influenced by ocean-atmosphere interactions of the Asian Monsoon, Indian Ocean Dipole (IOD), and El Niño-Southern Oscillation (ENSO), all of which are influenced by global warming. Continuous remote sensing by satellites of surface ocean temperature, one of the main drivers of basin-wide climate extremes, are limited to the upper few mm of the water column making assessments of broader scale understanding beneath the surface difficult. The carbonate skeletons of massive shallow-water corals provide continuous monthly-resolved proxy records of subsurface temperature that may complement available satellite-based sea surface temperature (SST) products, and may provide insights into the water column dynamics of the shallow ocean and its atmospheric forcing.

Here we present monthly-resolved records of the Sr/Ca-temperature proxy from shallow-water Porites corals collected in the southern Andaman Sea (Ko Racha Yai, Thailand, ~7.6°N), northeastern Indian Ocean. Coral Sr/Ca tracks the variability and annual cycle of high-resolution (~5 km x 5 km) monthly satellite SST during 1985-2010 fairly well, including a double-peak in spring and fall SST resulting from regular monsoon forcing. Interestingly, coral Sr/Ca indicates prominent events of exaggerated cooling in some winters that are not apparent in the satellite SST product. These prominent cooling events in coral Sr/Ca occur in winters coinciding either with years of positive IOD (pIOD), combined pIOD and El Niño, or La Niña. Consequently, we report for the first time a distinct IOD signal in a temperature (proxy) record from the northeastern Indian Ocean, a region normally considered too far north of the IOD core region off western Sumatra-Java, in the equatorial eastern Indian Ocean.

We suggest the difference between substantially lower coral Sr/Ca temperature relative to satellite SST in specific winters can be best explained by differences in temperature between coral depth (5-10 m) and sea surface (upper few mm) where satellite SST are monitored. Importantly, the Andaman Sea is characterized by large, eastward-travelling large-amplitude internal waves (LAIW), which carry cold subpycnocline water into shallower coral reef areas. These upslope intrusions of cold waters rarely extend to the sea surface, and are not visible in satellite SST. The effect of cooling of subsurface waters by LAIW is strongest during periods with shallower pycnocline, such as during the Northeast Monsoon (winter) season. We investigate if changes in pycnocline depth, as suggested by coral Sr/Ca temperatures relative to satellite SST, are modulated by changes in the intensity of the Asian Monsoon on interannual to decadal timescales.

Our results may provide unique insights into the atmospheric modulation of northeastern Indian Ocean shallow subsurface temperatures by the interaction of the Asian Monsoon, IOD, and ENSO since the start of the satellite era, not available from any instrumental source of observation. Extending these coral records beyond the satellite era will further improve our understanding of the complex interaction between ocean and atmosphere variability in this region under past, present, and future climate change.

How to cite: Camelia, H., Felis, T., Hargreaves, J., Kölling, M., and Scheffers, S.: Indian Ocean Dipole, El Niño-Southern Oscillation, and large-amplitude internal waves recorded in Andaman Sea corals during the satellite era, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10821, https://doi.org/10.5194/egusphere-egu24-10821, 2024.

EGU24-11409 | ECS | Orals | CL4.2

Forcing mechanisms of the half-precession cycle in western tropical Pacific temperature 

Zhipeng Wu, Qiuzhen Yin, André Berger, and Zhengtang Guo

The western equatorial Pacific (WEP) plays an important role on global and regional climate. Its temperature reconstructions during the Quaternary display orbital-scale variations, containing major cycles of ~100, 40 and 20 kyr. In addition to these longer cycles, the half-precession cycle is also reported in a recent reconstruction, but the forcing mechanism deserves further study. Here we perform a systematic study on the half-precession cycle in the WEP temperature and related mechanisms. We first analyze existing temperature reconstructions to test whether there is robust half-precession cycle through time. We then use transient climate simulations to investigate its forcing mechanism. Our results show that the half-precession cycle is a robust feature in the long-term evolution of the WEP temperature, but its strength varies in time. Our model results further show that the half-precession cycle in the WEP temperature is mainly driven by maximum equatorial insolation, and its strength is modulated by eccentricity and the conditions of CO2 and ice sheets. Our simulated half-precession cycles in the WEP temperature provide a possible explanation for the half-precession signal recorded in proxy records.

How to cite: Wu, Z., Yin, Q., Berger, A., and Guo, Z.: Forcing mechanisms of the half-precession cycle in western tropical Pacific temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11409, https://doi.org/10.5194/egusphere-egu24-11409, 2024.

EGU24-13006 | Posters on site | CL4.2

Central equatorial Pacific climate change over the last 7,000 years using a coral ensemble approach 

Alyssa R Atwood, Kim M Cobb, Pamela M Grothe, Hussein R Sayani, Sydney Garber, John R Southon, and R Lawrence Edwards

Identifying the processes that control tropical Pacific climate variations on long timescales is a pressing problem in climate research, given the outsized impacts of the El Niño/Southern Oscillation (ENSO) on global climate and the uncertainty in future ENSO behavior under anthropogenic climate change. By studying the characteristics of tropical Pacific climate under different climate states in the past, we can better assess its sensitivity to external forcing. Such paleoclimate constraints can serve as critically important test beds for coupled climate models that underlie future climate projections. In this talk, I will present a new set of climate reconstructions from the central equatorial Pacific spanning a range of timescales from seasonal to interannual to millennial, based on a large ensemble of coral oxygen isotope measurements from Kiritimati (aka Christmas Island) that span the past 7,000 years. Each of these timescales yields unique and complementary information about the climate of this region. We implement several new techniques to minimize the uncertainty in the climate reconstructions, which show a trend toward cooler and/or drier conditions and a reduced annual cycle going back in time that provide much needed context for understanding low-frequency changes in ENSO variability over the Holocene.

How to cite: Atwood, A. R., Cobb, K. M., Grothe, P. M., Sayani, H. R., Garber, S., Southon, J. R., and Edwards, R. L.: Central equatorial Pacific climate change over the last 7,000 years using a coral ensemble approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13006, https://doi.org/10.5194/egusphere-egu24-13006, 2024.

EGU24-14008 | ECS | Orals | CL4.2

Pan-regional characterization of the variability in the Indonesian Seas 

Yuan Wang and Huijie Xue

The Indonesian Seas feature a wide-spectrum of variations in hydrography and circulation. This study applies a simple frequency-based time series decomposition method on the 20-year model outputs without data-assimilation, and demonstrates the spatial distribution of the variations in intra-seasonal, semi-annual, annual, and inter-annual bands, respectively. The four bands of variations are further used in K-mean clustering to investigate the inherent dynamical similarities/dissimilarities for a pan-regional characterization. The clusters based on the variations of the sea-level/thermocline emphasize the competing impacts of the annual and inter-annual variations in the Indonesian Seas, which lays on a "cross-road" of the inter-annual variation dominated NE-SW oriented deep-ocean regime and the annual variation dominated NW-SE oriented marginal sea regime. The annual variation is primarily driven by the regional monsoon wind. Moreover, profiles of annual current variations show a significant difference between the main and east branch of the Indonesian Throughflow (ITF), where annual variations play a major role above (below) the thermocline in the main (east) branch. In general, the ITF variability is mainly influenced by the remotely generated inter-annual variability, regional annual forcings by monsoon, and local flow instability and fluctuations, with the semi-annual variation being minor but non-trivial.

How to cite: Wang, Y. and Xue, H.: Pan-regional characterization of the variability in the Indonesian Seas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14008, https://doi.org/10.5194/egusphere-egu24-14008, 2024.

EGU24-14611 | Posters on site | CL4.2

Millennial scale monsoon variability over the last 250,000 years in the Arabian Sea 

Andreas Lückge, Martina Hollstein, Mahyar Mohtadi, Enno Schefuß, and Stephan Steinke

Dansgaard-Oeschger oscillations and Heinrich events described in Greenland ice cores are also visible in the climate of the monsoon realm as documented in Arabian Sea sediments. However, little is known about these millennial scale fluctuations beyond the reach of the Greenland ice cores. Here, we present high-resolution geochemical and micropaleontological data from two sediment cores located offshore Pakistan, extending the monsoon record to the past 250,000 years in millennial scale resolution.

The stable oxygen isotope (d18O) record of the planktic foraminifera G. ruber shows a strong correspondence to Greenland ice core d18O, whereas the d18O signal of benthic foraminifera (U. peregrina and G. affinis) reflects patterns similar to those observed in Antarctic ice core records. Distinct shifts in benthic d18O during stadials are interpreted to show frequent injections of oxygen-rich intermediate water masses of Southern Ocean origin into the Arabian Sea. Alkenone SSTs show variations between 23 and 28°C. Millennial scale SST changes of 2°C are modulated by long-term SST fluctuations. Interstadials and the cold phases of interglacials are characterized by sediments enriched in organic carbon (TOC) whereas sediments with low TOC contents appear during stadials. Abrupt shifts (50-60 year duration) at climate transitions, such as interstadial inceptions, correlate with changes in productivity-related and anoxia-indicating proxies. Interstadial inorganic data consistently show that enhanced fluxes of terrestrial-derived sediments are paralleled by productivity maxima, and are characterized by an increased fluvial contribution from the Indus River. The hydrogen isotopic composition of terrigenous plant waxes indicates that stadials are dry phases whereas humid conditions seem to have prevailed during interstadials. In contrast, stadials are characterized by an increased contribution of aeolian dust probably from the Arabian Peninsula. Heinrich events are especially dry and dusty, indicating a dramatically weakened Indian summer monsoon and increased continental aridity.

These results strengthen the evidence that North Atlantic temperature changes and shifts in the hydrological cycle of the Indian monsoon system are closely coupled, and had a massive impact on regional environmental conditions such as river discharge and ocean margin anoxia. These shifts were modulated by changes in the supply of water masses from the Southern Hemisphere.

How to cite: Lückge, A., Hollstein, M., Mohtadi, M., Schefuß, E., and Steinke, S.: Millennial scale monsoon variability over the last 250,000 years in the Arabian Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14611, https://doi.org/10.5194/egusphere-egu24-14611, 2024.

EGU24-15391 | ECS | Posters on site | CL4.2

Reconstructing the Indonesian Throughflow variability and its climatology using long corals from the North-western coast of Australia 

Padmasini Behera, Jens Zinke, Arnoud Boom, Paul A Wilson, and Bastian Hambach

The Indonesian Throughflow (ITF) is the primary tropical current, which transfers heat and salinity to the tropics and extratropics region. Crucial to the global ocean circulation system, the ITF is a major component of the tropical and global climate pattern. Re-analysis of instrumented data together with the results of coupled ocean-atmosphere model experiments, provide an understanding of the linkages between ITF variability and inter-annual modes of climate variability such as the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). However, the lack of longer climatic records of ITF variability makes it challenging to isolate the anthropogenic signal from natural variability. Here we present preliminary new, absolutely dated, seasonally resolved proxy records of sea surface salinity and temperature from the Timor Sea, northwest coast of Australia using cores taken from long-lived corals (~240 years) on the Hibernia-Ashmore reef. The Timor Sea is a proximal location for the ITF outlet into the eastern Indian Ocean, where temperature and salinity anomalies are greatest and ITF control is unequivocal. Herein we report sea surface temperature and the oxygen isotopic composition of seawater reconstructed using paired analyses of skeletal Sr/Ca and oxygen isotope composition for the last 40 yr. The resulting bimonthly coral record aids in understanding the linkage between ENSO, IOD and ITF strength. Comparison of the long ITF records with the marine and terrestrial records from around the region and world further reveals the relationship between ITF variability and Austral-Asian-African monsoon rainfall changes.

How to cite: Behera, P., Zinke, J., Boom, A., Wilson, P. A., and Hambach, B.: Reconstructing the Indonesian Throughflow variability and its climatology using long corals from the North-western coast of Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15391, https://doi.org/10.5194/egusphere-egu24-15391, 2024.

EGU24-16398 | Orals | CL4.2

Eccentricity forcing on Tropical Indo-Pacific Ocean Seasonality 

Luc Beaufort and Anta-Clarisse Sarr

The amount of radiative energy received at the Earth's surface depends on two factors: Earth-Sun distance and sunlight angle. Because of the former factor, high eccentricity cycles can induce the appearance of seasons in the tropical ocean. To describe this phenomenon, we used the Earth System Model IPSL-CM5A2 and its ocean biogeochemistry component PISCES-v2 to simulate Sea Surface Temperature (SST) and Primary Production (PP) with various eccentricity configuration. We performed simulations under six precession configurations at high eccentricity (0.053), and one simulation at the low eccentricity (0.006), representing the two eccentricity extremes of the Quaternary period. The results revealed that high eccentricity induced enhanced seasonal variability in SST, resulting in an annual thermal amplitude of approximately 2.2°C, compared to less than 0.5°C at low eccentricity, in low latitude ocean surface waters. PP displayed inherent seasonality under low eccentricity conditions, which significantly intensified during periods of high eccentricity. Consequently, we found that on long timescales, SST seasonality followed only the eccentricity cycles, while PP seasonality also exhibited variability at precessional scale. We introduce the term "eccentriseasons" to describe distinct annual thermal differences observed in tropical oceans exclusively during high eccentricity periods, leading to a gradual shift of seasons throughout the calendar year. Our findings were further corroborated by coccolithophore proxy records from the Indo-Pacific Ocean, strengthening the validity of the simulations. These results have significant implications for understanding climatic phenomena in low latitudes affected by seasons, including the El Niño-Southern Oscillation and monsoons.

How to cite: Beaufort, L. and Sarr, A.-C.: Eccentricity forcing on Tropical Indo-Pacific Ocean Seasonality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16398, https://doi.org/10.5194/egusphere-egu24-16398, 2024.

EGU24-17513 | Orals | CL4.2

Decreased precipitation intensity in the South Pacific Convergence Zone during the Little Ice Age inferred from dinosterol hydrogen isotope ratios 

Nemiah Ladd, Ashley Maloney, Daniel B Nelson, Julie N Richey, Amanda Witt, Polly Sobeck, Matthew Prebble, Mark Peaple, David A Sear, Peter G Langdon, Nathalie Dubois, and Julian P Sachs

The South Pacific Convergence Zone (SPCZ) is the most prominent precipitation feature in the southern hemisphere, extending southeast from Papua New Guinea to French Polynesia. Changes in SPCZ precipitation dynamics can have major impacts on local communities and ecosystems, as well as the global hydrologic balance and ocean circulation. Variability in SPCZ precipitation can be characterized as changes in precipitation intensity throughout the entire rainfall band, or as changes in its mean annual position. Proxy reconstructions of precipitation rates from single sites within the SPCZ region cannot distinguish changes in SPCZ intensity from changes in SPCZ location, and the low density of proxy-based precipitation records from the pre-instrumental era makes it challenging to characterize past SPCZ dynamics.

To address this gap, we present quantitative records of rainfall rates derived from sediment cores collected from five freshwater lakes in the western portion of the SPCZ (from Tetepare and Rendova Islands in Solomon Islands, and from Thion Island in northern Vanuatu), spanning the past 500 to 1000 years, depending on the site. Our records are based on the hydrogen isotope composition of the dinoflagellate biomarker dinosterol, which is quantitatively related to mean annual precipitation. Our dinosterol records are complemented by analyses of magnetic susceptibility, pollen, and leaf wax hydrogen isotopes. We pair our new dinosterol-based precipitation reconstructions with previously published, comparable records from lakes in Samoa, Wallis, and southern Vanuatu to demonstrate that precipitation rates were systematically lower throughout the western and central SPCZ during the Little Ice Age (1450 – 1850 CE), indicating a decrease in precipitation intensity. The earlier Medieval Climate Anomaly (950 – 1250 CE) is also characterized by a tendency to drier conditions than in the modern period, but with more spatial heterogeneity. This networked reconstruction of precipitation rates in the SPCZ region provides the opportunity to better assess how rainfall dynamics in the region have changed through time, and how modes of variability within the SPCZ are related to global climate change.

How to cite: Ladd, N., Maloney, A., Nelson, D. B., Richey, J. N., Witt, A., Sobeck, P., Prebble, M., Peaple, M., Sear, D. A., Langdon, P. G., Dubois, N., and Sachs, J. P.: Decreased precipitation intensity in the South Pacific Convergence Zone during the Little Ice Age inferred from dinosterol hydrogen isotope ratios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17513, https://doi.org/10.5194/egusphere-egu24-17513, 2024.

EGU24-18460 | Posters on site | CL4.2

Surface and thermocline variability in the tropical eastern Indian Ocean since the Last Glacial Maximum 

Henrik Sadatzki, Mahyar Mohtadi, Martina Hollstein, Andreas Lückge, Yusuke Yokoyama, and Delia Oppo

The tropical eastern Indian Ocean is part of Earth´s largest warm pool and its surface and thermocline temperatures exert strong control on deep atmospheric convection and play a critical role for the development of basin-wide, zonal climate anomalies across the Indian Ocean. However, the nature, timing, and mechanisms of changes in the Walker circulation in the tropical Indian Ocean since the Last Glacial Maximum (LGM) are poorly constrained owing to a lack of suitable proxy records and proxy-model disagreements (DiNezio et al. 2016; Mohtadi et al., 2017). Here we reconstruct surface and thermocline temperature and hydrographic changes in the tropical eastern Indian Ocean based on high-resolution, planktic foraminiferal (G. ruber and P. obliquiloculata) d18O and Mg/Ca records from three sediment cores retrieved offshore west Sumatra along a latitudinal transect across the equator. These records are put into a chronological framework based on numerous radiocarbon ages of surface-dwelling planktic foraminifera and cover the last 22 ka.

Sea surface temperatures at all three sites show a stepwise warming of ~3°C with an ‘Antarctic timing’ between 18 ka and 11 ka. The thermocline temperature variability is also consistent among the three core sites but distinctly different from the sea surface temperature variability. Thermocline temperatures show a major warming of 2–3°C between ~13 ka and ~10 ka, while differences between LGM and Holocene temperatures are rather small. The resulting surface-thermocline temperature gradient reveals not only a difference between LGM and Holocene thermocline depth levels, but also a major breakdown pointing at a rapid deepening of the thermocline at ~12 ka. This thermocline deepening might have been associated with a strengthened convective activity and Walker circulation, with its timing suggesting a connection to feedbacks related to inundation of the large Sahul Shelf during deglacial sea level rise. Supplemented by deuterium isotope analyses of leaf waxes, our new set of proxy records will provide unprecedented insights into sea surface and thermocline dynamics in the tropical eastern Indian Ocean since the LGM, their relationship to local rainfall, and whether and how basin-wide circulation and rainfall anomalies were shaped by sea level rise and deglacial climate change.

 

DiNezio et al., 2016, Paleoceanography 31, 866–894, doi:10.1002/2015PA002890

Mohtadi et al., 2017, Nature Communications 8, 1015, doi:10.1038/s41467-017-00855-3

How to cite: Sadatzki, H., Mohtadi, M., Hollstein, M., Lückge, A., Yokoyama, Y., and Oppo, D.: Surface and thermocline variability in the tropical eastern Indian Ocean since the Last Glacial Maximum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18460, https://doi.org/10.5194/egusphere-egu24-18460, 2024.

Sea surface salinity and its hydrological influences are important variables in global ocean and atmospheric circulation. In the Indian Ocean, particularly the Southwestern region, observational records of salinity are not well constrained before the early 2000’s making any understanding of decadal to interdecadal changes in sea surface salinity difficult. Current reconstructions of hydroclimate variability associated with ocean currents and salinity variability in the Southwestern Indian Ocean region are limited mainly to the Aguhlas current region, with a limited number of reconstructions capturing wider open ocean variability. Where reconstructions of this nature do exist across the wider southwest Indian Ocean, these records have limited ground-truthing due to short observational records and lack of replication.

Here we present a paired Sr/Ca and δ18O, bimonthly resolved record of a shallow water coral from the southwest Indian Ocean (Mauritius Island, 20.34°S, 57.55°E), extending from 1882 to 1989 to provide invaluable information about hydroclimate in the region. The reconstructed coral Sr/Ca-temperature proxy tracks the SST of the region very well, providing additional confidence to the current coral temperature reconstructions. Our record highlights the strong increasing SST trend across the southwest Indian Ocean, with an increase of +0.55°C since 1883. The paired analysis of Sr/Ca and δ18Oallows for the calculation of δ18Osw (hydrology) at bimonthly resolution, developing the first high-resolution hydroclimate record which extends past the start of the 20th century and captures wider open ocean variability. The coral δ18Osw record captures Mauritius rainy season (austral summer) precipitation, with a strong relationship between austral summer precipitation at stations on the island during the short period of observation. It is suggested that this relationship to Mauritius's rainy season captures wider-scale precipitation variability associated with the tropical rainfall belt. It is also suggested the non-rainy season (austral winter) δ18Osw variability is controlled by oceanic processes as Mauritius lies along the South Equatorial Current, one of the major oceanic currents in the Indian Ocean and an important connection between the Pacific and Indian Ocean basins.

By using a network of current coral reconstructions from the wider southwest Indian Ocean, and the newly developed Mauritius coral record we hope to reveal variability in both ocean current variability and precipitation across this important region. Extending these coral records beyond the satellite era will further improve our understanding of the complex interaction between ocean and atmosphere variability in this region under past, present, and future climate change. This study uses legacy data as part of the DFG-Priority Programme “ Tropical Climate Variability & Coral Reefs” (SPP 2299).

How to cite: Hargreaves, J. A., Felis, T., and Kölling, M.: Hydrologic variability in the southwest Indian Ocean from Mauritius corals since the late 19th century (and connections to the Indo-Pacific throughflow), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18898, https://doi.org/10.5194/egusphere-egu24-18898, 2024.

The latest assessment report (AR6) of the Intergovernmental Panel on Climate Change includes a new element to climate research, i.e. the Interactive Atlas (IA), which is very useful for users from different sectors. As the new CMIP6 global climate model simulations use the brand-new SSP-scenarios paired with the RCP-scenarios, the latest climate change projections should be evaluated in order to update the regional and national adaptation strategies. Keeping this in mind we focused on Europe, with a special emphasis on Hungary in our study.

Our aim was to analyse the potential future changes of different temperature indices for Europe, in order to recognize spatial patterns and trends that may shape our climate in the second half of the 21st century. For this purpose, multi-model mean simulation data provided by the IPCC AR6 WG1 IA were downloaded on a monthly base. We chose two climate indices beside the mean temperature values, which represent temperature extremes, namely, the number of days with maximum temperature above 35 °C and the number of frost days (i.e. when daily minimum temperature is below 0 °C). We focused on the end of the 21st century (2081–2100) with also briefly considering the medium-term changes of the 2041–2060 period (both compared to the last two decades of the historical simulation period, i.e. 1995–2014 as the reference period). For both future periods we used all scenarios provided in the IA, namely, SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5.

Several zonal and meridional segments over the continent were defined, where we analysed the projected changes of the indices. The zonal segments provide an insight on two different effects that may induce spatial differences between future regional changes. (i) Continentality can be recognized as an increasing effect from the western parts of the segment towards the east. (ii) Topography also appears as the influence of mountains, plains, and basins emerge. The meridional segments provide information about the north-to-south differences as well, as the effects of sea cover. The changes in the indices are plotted on diagrams representing the different months, where the differences in the scenarios are also shown. These diagrams are compared to their respective landscape profiles, furthermore, statistical parameters were calculated. In addition, a monotony index was defined as the cumulative direction of differences between the neighbouring grid cells and analysed within the study.

Our results show that in the changes of mean temperature, both the zonal location and sea cover will play a key role in forming spatial differences within Europe. However, for the extreme temperature indices, topography and continentality are likely to become more dominant than sea cover, while the zonal location remains an important factor. 

Acknowledgements: This work was supported by the Hungarian National Research, Development and Innovation Fund [grant numbers PD138023, K-129162], and the National Multidisciplinary Laboratory for Climate Change [grant number RRF-2.3.1-21-2022-00014]. 

How to cite: Divinszki, F., Kis, A., and Pongrácz, R.: Analysing the projected monthly changes of temperature-related climate indices over Europe using zonal and meridional segments based on CMIP6 data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-389, https://doi.org/10.5194/egusphere-egu24-389, 2024.

EGU24-868 | ECS | Posters on site | CL4.3

Relationship of the predictability of North Pacific Mode and ENSO with predictability of PDO 

Jivesh Dixit and Krishna M. AchutaRao

PDO and ENSO are most prominent variability modes in the Pacific Ocean at decadal and interannual timescales respectively. Mutual independence between ENSO and PDO is questionable (Chen & Wallace, 2016). Linear combination of the first two orthogonal modes of SST variability in our Study Region (SR; 70oN - 20oS, 110oE - 90oW) i.e. mode 1 (interannual mode, we call it, IAM; ENSO like variability) and mode 2 (North Pacific Mode (NPM; Deser & Blackmon (1995)); a decadal mode) produces a PDO like variability (Chen & Wallace, 2016). It suggests that PDO is not independently hosted in the Pacific Ocean and can be represented by two linearly independent variability modes.

To produce credible and skillful climate information at multi-year to decadal timescales, Decadal Climate Prediction Project (DCPP), led by the Working Group on Subseasonal to Interdecadal Prediction (WGSIP), focuses on both the scientific and practical elements of forecasting climate by employing predictability research and retrospective analyses within the Coupled Model Intercomparison Project Phase 6 (CMIP6). Component A under DCPP experiments concentrates on hindcast experiments to examine the prediction skill of participating models with respect to actual observations.

As linear combination of  IAM and NPM in SR produces PDO pattern and timescales efficiently, we compared the  ability of DCPP-A hindcasts to predict  IAM, NPM, and  PDO. In this analysis we use output from 9 models (a total of 128 ensemble members), initialised every year from 1960 to 2010. To produce the prediction skill estimates.

At lead year 1 from initialisation, the prediction of NPM,  IAM and PDO is quite skillful as the models are initialised with observations. In subsequent years, skill of either IAM or NPM or both drop significantly and that leads to drop in skill of predicted PDO index. Both the deterministic estimates and probabilistic estimates of prediction skill for DCPP hindcast experiments suggest that the ability of hindcast experiments to predict NPM governs the prediction skill to predict PDO index.

Keywords: PDO, ENSO, NPM, CMIP6, DCPP, hindcast

References

Chen, X., & Wallace, J. M. (2016). Orthogonal PDO and ENSO indices. Journal of Climate, 29(10), 3883–3892. https://doi.org/10.1175/jcli-d-15-0684.1

Deser, C., & Blackmon, M. L. (1995). On the Relationship between Tropical and North Pacific Sea Surface Temperature Variations. Journal of Climate, 8(6), 1677–1680. https://doi.org/10.1175/1520-0442(1995)008<1677:OTRBTA>2.0.CO;2

How to cite: Dixit, J. and AchutaRao, K. M.: Relationship of the predictability of North Pacific Mode and ENSO with predictability of PDO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-868, https://doi.org/10.5194/egusphere-egu24-868, 2024.

EGU24-1757 | Posters on site | CL4.3

Is the NAO signal-to-noise paradox exacerbated by severe winter windstorms? 

Lisa Degenhardt, Gregor C. Leckebusch, Adam A. Scaife, Doug Smith, and Steve Hardiman

The signal-to-noise paradox is known to be a limitation in multiple seasonal and decadal forecast models where the model ensemble mean predicts observations better than individual ensemble members. This ‘paradox’ occurs for different parameters, like the NAO, temperature, wind speed or storm counts in multiple seasonal and decadal forecasts. However, investigations have not yet found the origin of the paradox. First hypotheses are that weak ocean – atmosphere coupling or a misrepresentation of eddy feedback in these models is responsible.

Our previous study found a stronger signal-to-noise error in windstorm frequency than for the NAO despite highly significant forecast skill. In combination with the underestimation of eddy feedback in multiple models, this led to the question: Might the signal-to-noise paradox over the North-Atlantic be driven by severe winter windstorms?

To assess this hypothesis, the signal-to-noise paradox is investigated in multiple seasonal forecast suites from the UK Met Office, ECMWF, DWD and CMCC. The NAO is used to investigate the changes in the paradox depending on the storminess of the season. The results show a significant increase of the NAO-signal-to-noise error in stormy seasons in GloSea5. Other individual models like the seasonal model of the DWD or CMCC do not show such a strong difference. A multi-model approach, on the other hand, shows the same tendency as GloSea5. Nevertheless, these model differences mean that more hindcasts are needed to conclusively demonstrate that the signal-to-noise error arises from Atlantic windstorms.

How to cite: Degenhardt, L., Leckebusch, G. C., Scaife, A. A., Smith, D., and Hardiman, S.: Is the NAO signal-to-noise paradox exacerbated by severe winter windstorms?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1757, https://doi.org/10.5194/egusphere-egu24-1757, 2024.

EGU24-1940 | ECS | Orals | CL4.3

Study of the Decadal Predictability of Mediterranean Sea Surface Temperature Based on Observations 

Xiaoqin Yan, Youmin Tang, and Dejian Yang

Sea surface temperature (SST) changes in the Mediterranean Sea have profound impacts on both the Mediterranean regions and remote areas. Previous studies show that the Mediterranean SST has significant decadal variability that is comparable with the Atlantic multidecadal variability (AMV). However, few studies have discussed the characteristics and sources of the decadal predictability of Mediterranean SST based on observations. Here for the first time we use observational datasets to reveal that the decadal predictability of Mediterranean SST is contributed by both external forcings and internal variability for both annual and seasonal means, except that the decadal predictability of the winter mean SST in the eastern Mediterranean is mostly contributed by only internal variability. Besides, the persistence of the Mediterranean SST is quite significant even in contrast with that in the subpolar North Atlantic, which is widely regarded to have the most predictable surface temperature on the decadal time scale. After the impacts of external forcings are removed, the average prediction time of internally generated Mediterranean SST variations is more than 10 years and closely associated with the multidecadal variability of the Mediterranean SST that is closely related to the accumulated North Atlantic Oscillation forcing.

How to cite: Yan, X., Tang, Y., and Yang, D.: Study of the Decadal Predictability of Mediterranean Sea Surface Temperature Based on Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1940, https://doi.org/10.5194/egusphere-egu24-1940, 2024.

EGU24-3190 | ECS | Orals | CL4.3

Seasonal forecasting of the European North-West shelf seas: limits of winter and summer sea surface temperature predictability 

Jamie Atkins, Jonathan Tinker, Jennifer Graham, Adam Scaife, and Paul Halloran

The European North-West shelf seas (NWS) support economic interests and provide environmental services to several adjacent populous countries. Skilful seasonal forecasts of the NWS would be useful to support decision making. Here, we quantify the skill of an operational large-ensemble ocean-atmosphere coupled dynamical forecasting system (GloSea), as well as a benchmark persistence forecasting system, for predictions of NWS sea surface temperature (SST) at 2-4 months lead time in winter and summer. We also identify sources of- and limits to NWS SST predictability with a view to what additional skill may be available in the future. We find that GloSea NWS SST skill is generally high in winter and low in summer. Persistence of anomalies in the initial conditions contributes substantially to predictability. GloSea outperforms simple persistence forecasts, by adding atmospheric variability information, but only to a modest extent. Where persistence is low – for example in seasonally stratified regions – both GloSea and persistence forecasts show lower skill. GloSea skill can be degradeded by model deficiencies in the relatively coarse global ocean component, which lacks a tidal regime and likely fails to properly fine-scale NWS physics. However, using “near perfect atmosphere” tests, we show potential for improving predictability of currently low performing regions if atmospheric circulation forecasts can be improved, underlining the importance of development of atmosphere-ocean coupled models for NWS seasonal forecasting applications.

How to cite: Atkins, J., Tinker, J., Graham, J., Scaife, A., and Halloran, P.: Seasonal forecasting of the European North-West shelf seas: limits of winter and summer sea surface temperature predictability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3190, https://doi.org/10.5194/egusphere-egu24-3190, 2024.

EGU24-4538 | ECS | Orals | CL4.3

Statistical downscaling of extremes in seasonal predictions - a case study on spring frosts for the viticultural sector 

Sebastiano Roncoroni, Panos Athanasiadis, and Silvio Gualdi

Spring frost events occurring after budburst of grapevines can damage new shoots, disrupt plant growth and cause large economic losses to the viticultural sector. Frost protection practices encompass a variety of vineyard management actions across timescales, from seasonal to decadal and beyond. The cost-effectiveness of such measures depends on the availability of accurate predictions of the relevant climate hazards at the appropriate timescales.

In this work, we present a statistical downscaling method which predicts variations in the frequency of occurrence of spring frost events in the important winemaking region of Catalunya at the seasonal timescale. The downscaling method exploits the seasonal predictability associated with the predictable components of the atmospheric variability over the Euro-Atlantic region, and produces local predictions of frost occurrence at a spatial scale relevant to vineyard management.

The downscaling method is designed to address the specific needs highlighted by a representative stakeholder in the local viticultural sector, and is expected to deliver an actionable prototype climate service. The statistical procedure is developed in perfect prognosis mode: the method is trained with large-scale reanalysis data against a high-resolution gridded observational reference, and validated against multi-model seasonal hindcast predictions.

Our work spotlights the potential benefits of transferring climate predictability across spatial scales for the design and provision of usable climate information, particularly regarding extremes.

How to cite: Roncoroni, S., Athanasiadis, P., and Gualdi, S.: Statistical downscaling of extremes in seasonal predictions - a case study on spring frosts for the viticultural sector, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4538, https://doi.org/10.5194/egusphere-egu24-4538, 2024.

EGU24-4873 | ECS | Orals | CL4.3

Why does the Signal-to-Noise Paradox Exist in Seasonal Climate Predictability? 

Yashas Shivamurthy, Subodh Kumar Saha, Samir Pokhrel, Mahen Konwar, and Hemant Kumar Chaudhari

Skillful prediction of seasonal monsoons has been a challenging problem since the 1800s. However, significant progress has been made in Indian summer monsoon rainfall prediction in recent times, with skill scores reaching 0.6 and beyond, surpassing the estimated predictability limits. This phenomenon leads to what is known as the “Signal-to-noise Paradox.” To investigate this paradox, we utilized 52 ensemble member hindcast runs spanning 30 years.

Through the application of ANOVA and Mutual Information methods, we estimate the predictability limit globally. Notably, for the boreal summer rainfall season, the Indian subcontinent exhibited the paradox, among several other regions, while the Equatorial Pacific region, despite demonstrating high prediction skill, does not have the Signal-to-Noise paradox. We employed a novel approach to understand how sub-seasonal variability and their projection in association with predictors are linked to the paradoxical behavior of seasonal prediction skill.

We propose a new method to estimate predictability limits that is free from paradoxical phenomena and shows much higher seasonal predictability. This novel method provides valuable insights into the complex dynamics of monsoon prediction, thereby creating opportunities for expanded research and potential improvements in seasonal forecasting skill in the coming years.

How to cite: Shivamurthy, Y., Saha, S. K., Pokhrel, S., Konwar, M., and Chaudhari, H. K.: Why does the Signal-to-Noise Paradox Exist in Seasonal Climate Predictability?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4873, https://doi.org/10.5194/egusphere-egu24-4873, 2024.

EGU24-7134 | ECS | Orals | CL4.3

Towards the Predictability of Compound Dry and Hot Extremes through Complexity Science 

Ankit Agarwal and Ravikumar Guntu

Compound Dry and Hot Extremes (CDHE) have an adverse impact on socioeconomic factors during the Indian summer monsoon, and a future exacerbation is anticipated. The occurrence of CDHE is influenced by teleconnections, which play a crucial role in determining its likelihood on a seasonal scale. Despite the importance, there is a lack of studies unravelling the teleconnections of CDHE in India. Previous investigations specifically focused on teleconnections between precipitation, temperature, and climate indices. Hence, there is a need to unravel the teleconnections of CDHE. This study presents a framework combining event coincidence analysis (ECA) with complexity science. ECA evaluates the synchronization between CDHE and climate indices. Subsequently, complexity science is utilized to construct a driver-CDHE network to identify the critical drivers of CDHE. A logistic regression model is employed to evaluate the proposed drivers' effectiveness. The occurrence of CDHE exhibits distinct patterns from July to September when considering intra-seasonal variability. Our findings contribute to the identification of drivers associated with CDHE. The primary driver for Eastern, Western India and Central India is the indices in the Pacific Ocean and Atlantic Ocean, respectively, followed by the indices in the Indian Ocean. These identified drivers outperform the traditional Niño 3.4-based predictions. Overall, our results demonstrate the effectiveness of integrating ECA and complexity science to enhance the prediction of CDHE occurrences.

How to cite: Agarwal, A. and Guntu, R.: Towards the Predictability of Compound Dry and Hot Extremes through Complexity Science, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7134, https://doi.org/10.5194/egusphere-egu24-7134, 2024.

EGU24-8028 | ECS | Orals | CL4.3

Constraining near to mid-term climate projections by combining observations with decadal predictions 

Rémy Bonnet, Julien Boé, and Emilia Sanchez

The implementation of adaptation policies requires seamless and relevant information on the evolution of the climate over the next decades. Decadal climate predictions are subject to drift because of intrinsic model errors and their skill may be limited after a few years or even months depending on the region. Non-initialized ensembles of climate projections have large uncertainties over the next decades, encompassing the full range of uncertainty attributed to internal climate variability. Providing the best climate information over the next decades is therefore challenging. Recent studies have started to address this challenge by constraining uninitialized projections of sea surface temperature using decadal predictions or using a storyline approach to constrain uninitialized projections of the Atlantic Meridional Overturning Circulation using observations. Here, using a hierarchical clustering method, we select a sub-ensemble of non-initialized climate simulations based on their similarity to observations. Then, we try to further refine this sub-ensemble of trajectories by selecting a subset based on its consistency with decadal predictions. This study presents a comparison of these different methods for constraining surface temperatures in the North-Atlantic / Europe region over the next decades, focusing on CMIP6 non-initialized simulations.

How to cite: Bonnet, R., Boé, J., and Sanchez, E.: Constraining near to mid-term climate projections by combining observations with decadal predictions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8028, https://doi.org/10.5194/egusphere-egu24-8028, 2024.

EGU24-9049 | Posters on site | CL4.3

Constraining internal variability in CMIP6 simulations to provide skillful near-term climate predictions 

Rashed Mahmood, Markus G. Donat, Pablo Ortega, and Francisco Doblas-Reyes

Adaptation to climate change requires accurate and reliable climate information on decadal and multi-decadal timescales. Such near-term climate information is obtained from future projection simulations, which are strongly affected by uncertainties related to, among other things, internal climate variability. Here we present an approach to constrain variability in future projection simulations of the coupled model intercomparison project phase 6 (CMIP6). The constraining approach involves phasing in the simulated with the observed climate state by evaluating the area-weighted spatial pattern correlations of sea surface temperature (SST) anomalies in individual members and observations. The constrained ensemble, based on the top ranked members in terms of pattern correlations with observed SST anomalies, shows significant added value over the unconstrained ensemble in predicting surface temperature 10 and also 20 years  after the synchronization with observations, thus extending the forecast range of the standard initialised predictions. We also find that while the prediction skill of the constrained ensemble for the first ten years is similar to the initialized decadal predictions, the added value against the unconstrained ensemble extends over more regions than the decadal predictions. In addition, the constraining approach can also be used to attribute predictability of regional and global climate variations to regional SST variability.

How to cite: Mahmood, R., G. Donat, M., Ortega, P., and Doblas-Reyes, F.: Constraining internal variability in CMIP6 simulations to provide skillful near-term climate predictions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9049, https://doi.org/10.5194/egusphere-egu24-9049, 2024.

There is an ongoing discussion about the contributions from forced and natural sources to the Atlantic Multi-decadal Variability (AMV).  As the AMV influences the general climate in large regions, this question has important consequences for climate predictions on decadal timescales and for a robust estimation of the influence of climate forcings.

Here, we investigate the Atlantic Multi-decadal Variability (AMV) in observations and in a large CMIP6 historical climate model ensemble. We compare three different definitions of the AMV aimed at extracting the variability intrinsic to the Atlantic region. These definitions are based on removing from the Atlantic temperature the non-linear trend, the part congruent to the global average, or the part congruent to the multi-model ensemble mean of the global average. The considered AMV definitions agree on the well-known low-frequency oscillatory variability in observations, but show larger differences for the models. In general, large differences between ensemble members are found.

We estimate the forced response in the AMV as the mean of the large multi-model ensemble.  The forced response resembles the observed low-frequency oscillatory variability for the detrended AMV definition, but this definition is also the most inefficient in removing the forced global mean signal. The forced response is very weak for the other definitions and only few of their individual ensemble members show oscillatory variability and, if they do, not with the observed phase.

The observed spatial temperature pattern related to the AMV is well captured for all three AMV definitions, but with some differences in the spatial extent. The observed instantaneous connection between NAO and AMV is well represented in the models for all AMV definitions. Only non-significant evidence of NAO leading the AMV on decadal timescales is found.

How to cite: Christiansen, B., Yang, S., and Drews, A.: The Atlantic Multi-decadal Variability in observations and in a large historical multi-model ensemble: Forced and internal variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9100, https://doi.org/10.5194/egusphere-egu24-9100, 2024.

EGU24-9274 | ECS | Orals | CL4.3 | Highlight

The Role of the North Atlantic for Heat Wave Characteristics in Europe 

Sabine Bischof, Robin Pilch Kedzierski, Martje Hänsch, Sebastian Wahl, and Katja Matthes

The recent severe European summer heat waves of 2015 and 2018 co-occurred with cold subpolar North Atlantic (NA) sea surface temperatures (SSTs). However, a significant connection between this oceanic state and European heat waves was not yet established.

We investigate the effect of cold subpolar NA SSTs on European summer heat waves using two 100-year long AMIP-like model experiments: one that employs the observed global 2018 SST pattern as a boundary forcing and a counter experiment for which we removed the negative NA SST anomaly from the 2018 SST field, while preserving daily and small-scale SST variabilities. Comparing these experiments, we find that cold subpolar NA SSTs significantly increase heat wave duration and magnitude downstream over the European continent. Surface temperature and circulation anomalies are connected by the upper-tropospheric summer wave pattern of meridional winds over the North Atlantic European sector, which is enhanced with cold NA SSTs. Our results highlight the relevance of the subpolar NA region for European summer conditions, a region that is marked by large biases in current coupled climate model simulations.

How to cite: Bischof, S., Pilch Kedzierski, R., Hänsch, M., Wahl, S., and Matthes, K.: The Role of the North Atlantic for Heat Wave Characteristics in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9274, https://doi.org/10.5194/egusphere-egu24-9274, 2024.

EGU24-9690 | ECS | Orals | CL4.3

Hybrid statistical-dynamical seasonal prediction of summer extreme temperatures over Europe 

Luca Famooss Paolini, Paolo Ruggieri, Salvatore Pascale, Erika Brattich, and Silvana Di Sabatino

Several studies show that the occurrence of summer extreme temperatures over Europe is increased since the middle of the twentieth century and is expected to further increase in the future due to global warming (Seneviratne et al., 2021). Thus, predicting heat extremes several months ahead is crucial given their impacts on socio-economic and environmental systems.

In this context, state-of-the-art dynamical seasonal prediction systems (SPSs) show low skills in predicting European heat extremes on seasonal timescale, especially in central and northern Europe (Prodhomme et al., 2022). However, recent studies have shown that our skills in predicting extratropical climate can be largely improved by subsampling the dynamical SPS ensemble with statistical post-processing techniques (Dobrynin et al., 2022).

This study assesses if the seasonal prediction skill of summer extreme temperatures in Europe in the state-of-the-art dynamical SPSs can be improved through subsampling. Specifically, we use a multi-model ensemble (MME) of SPSs contributing to the Copernicus Climate Change Service (C3S), analysing di hindcast period 1993—2016. The MME is subsampled by retaining a subset of members that predict the phase of the North Atlantic Oscillation (NAO) and the Eastern Atlantic (EA), typically linked to summer extreme temperatures in Europe. The subsampling relies on spring predictors of the weather regimes and thus allows us to retain only those ensemble members with a reasonable representation of summer heat extreme teleconnections.

Results show that by retaining only those ensemble members that accurately represent the NAO phase, it not only enhances the seasonal prediction skills for the summer European climate but also leads to improved predictions of summer extreme temperatures, especially in central and northern Europe. Differently, selecting only those ensemble members that accurately represent the EA phase does not improve either the predictions of summer European climate or the predictions of summer extreme temperatures. This can be explained by the fact that the C3S SPSs exhibits deficiencies in accurately representing the summer low-frequency atmospheric variability.

Bibliography

Dobrynin, M., and Coauthors, 2018: Improved Teleconnection-Based Dynamical Seasonal Predictions of Boreal Winter. Geophysical Research Letters, 45 (8), 3605—3614, https://doi.org/10.1002/2018GL07720

Prodhomme, C., S. Materia, C. Ardilouze, R. H. White, L. Batté, V. Guemas, G. Fragkoulidis, and J. Garcìa-Serrano, 2022: Seasonal prediction of European summer heatwaves. Climate Dynamics, 58 (7), 2149—2166, https://doi.org/10.1007/s00382-021-05828-3

Seneviratne, S., and Coauthors, 2021: Weather and Climate Extreme Events in a Changing Climate, chap. 11, 1513—1766. Cambridge University Press, https://doi.org/10.1017/9781009157896.013

How to cite: Famooss Paolini, L., Ruggieri, P., Pascale, S., Brattich, E., and Di Sabatino, S.: Hybrid statistical-dynamical seasonal prediction of summer extreme temperatures over Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9690, https://doi.org/10.5194/egusphere-egu24-9690, 2024.

EGU24-9905 | ECS | Orals | CL4.3

Optimization-based driver detection and prediction of seasonal heat extremes 

Ronan McAdam, César Peláez Rodríguez, Felicitas Hansen, Jorge Pérez Aracil, Antonello Squintu, Leone Cavicchia, Eduardo Zorita, Sancho Saldez-Sanz, and Enrico Scoccimarro

As a consequence of limited reliability of dynamical forecast systems, particularly over Europe, efforts in recent years have turned to exploiting the power of Machine Learning methods to extract information on drivers of extreme temperature from observations and reanalysis. Meanwhile, the diverse impacts of extreme heat have driven development of new indicators which take into account nightime temperatures and humidity. In the H2020 CLimate INTelligence (CLINT) project, a feature selection framework is being developed to find the combination of drivers which provides optimal seasonal forecast skill of European summer heatwave indicators. Here, we present the methodology, its application to a range of heatwave indicators and forecast skill compared to existing dynamical systems. First, a range of (reduced-dimensionality) drivers are defined, including k-means clusters of variables known to impact European summer (e.g. precipitation, sea ice content), and more complex indices like the NAO and weather regimes. Then, these drivers are used to train machine learning based prediction models, of varying complexity, to predict seasonal indicators of heatwave occurrence and intensity. A crucial and novel step in our framework is the use of the Coral Reef Optimisation algorithm, used to select the variables and their corresponding lag times and time periods which provide optimal forecast skill. To maximise training data, both ERA5 reanalysis and a 2000-year paleo-simulation are used; the representation of heatwaves and atmospheric conditions are validated with respect to ERA5. We present comparisons of forecast skill to the dynamical Copernicus Climate Change Service seasonal forecasts systems. The differences in timing, predictability and drivers of daytime and nighttime heatwaves across Europe are highlighted. Lastly, we discuss how the framework can easily be adapted to other extremes and timescales.



How to cite: McAdam, R., Peláez Rodríguez, C., Hansen, F., Pérez Aracil, J., Squintu, A., Cavicchia, L., Zorita, E., Saldez-Sanz, S., and Scoccimarro, E.: Optimization-based driver detection and prediction of seasonal heat extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9905, https://doi.org/10.5194/egusphere-egu24-9905, 2024.

EGU24-10539 | ECS | Orals | CL4.3

Exploring multiyear-to-decadal North Atlantic sea level predictability using machine learning and analog methods 

Qinxue Gu, Liwei Jia, Liping Zhang, Thomas Delworth, Xiaosong Yang, Fanrong Zeng, and Shouwei Li

Long-term sea level rise and multiyear-to-decadal sea level variations pose substantial risks of flooding and erosion in coastal communities. The North Atlantic Ocean and the U.S. East Coast are hotspots for sea level changes under current and future climates. Here, we employ a machine learning technique, a self-organizing map (SOM)-based framework, to systematically characterize the North Atlantic sea level variability, assess sea level predictability, and generate sea level predictions on multiyear-to-decadal timescales. Specifically, we classify 5000-year North Atlantic sea level anomalies from the Seamless System for Prediction and EArth System Research (SPEAR) model control simulations into generalized patterns using SOM. Preferred transitions among these patterns are further identified, revealing long-term predictability on multiyear-to-decadal timescales related to shifts in Atlantic meridional overturning circulation (AMOC) phases. By combining the SOM framework with “analog” techniques based on the simulations and observational/reanalysis data, we demonstrate prediction skill of large-scale sea level patterns comparable to that from initialized hindcasts. Moreover, additional source of short-term predictability is identified after the exclusion of low-frequency AMOC signals, which arises from the wind-driven North Atlantic tripole mode triggered by the North Atlantic Oscillation. This study highlights the potential of machine learning methods to assess sources of predictability and to enable efficient, long-term climate prediction.

How to cite: Gu, Q., Jia, L., Zhang, L., Delworth, T., Yang, X., Zeng, F., and Li, S.: Exploring multiyear-to-decadal North Atlantic sea level predictability using machine learning and analog methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10539, https://doi.org/10.5194/egusphere-egu24-10539, 2024.

The inter-annual to multi-decadal variability of recurrent, synoptic-scale atmospheric circulation patterns in the Northern Hemisphere extratropics, as represented by the Jenkinson-Collison classification scheme, is explored in reanalysis data spanning the entire 20th century, and in global climate model (GCM) data from the historical, AMIP and DCPP experiments conducted within the framework of CMIP6. The aim of these efforts is to assess the effect of coupled vs. uncoupled and initialised vs. non-initialized GCM simulations in reproducing the observed low-frequency variability of the aforementioned circulation patterns.

Results reveal that the observed annual counts of typical recurrent weather patterns, such as cyclonic or anticyclonic conditions and also situations of pronounced advection, exhibit significant oscillations on multiple time-scales ranging between several years and several decades. The period of these oscillations, however, is subject to large regional variations. This is in line with earlier studies suggesting that the extratropical atmospheric circulation’s low frequency variability is essentially unforced, except in the Pacific-North American sector where the forced variability is enhanced due to ENSO teleconnections. Neither the periods obtained from historical nor those obtained from AMIP experiments align with observations. Likewise, not even the periods obtained from different runs of the same GCM and experiment correspond to each other. Thus, in an non-initialized model setup, ocean-atmosphere coupling or the lack thereof essentially leads to the same results. Whether initialization and/or augmenting the ensemble size can improve these findings, will also be discussed.

Acknowledgement: This work is part of project Impetus4Change, which has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101081555.

How to cite: Brands, S., Cimadevilla, E., and Fernández, J.: Low-frequency variability of synoptic-scale atmospheric circulation patterns in the Northern Hemisphere extratropics and associated hindcast skill of decadal forecasting systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10551, https://doi.org/10.5194/egusphere-egu24-10551, 2024.

EGU24-10574 | Orals | CL4.3 | Highlight

Will 2024 be the first year above 1.5 C? 

Nick Dunstone, Doug Smith, Adam Scaife, Leon Hermanson, Andrew Colman, and Chris Folland

Global mean surface temperature is the key metric by which our warming climate is monitored and for which international climate policy is set. At the end of each year the Met Office makes a global mean temperature forecast for the coming year. Following on from the new record 2023, we predict a high probability of another record year in 2024 and a 35% chance of exceeding 1.5 C above pre-industrial. Whilst a one-year temporary exceedance of 1.5 C would not constitute a breech of the Paris Agreement target, our forecast highlights how close we are now to breeching this target. We show that our 2024 forecast can be largely explained by the combination of the continuing warming trend of +0.2 C/decade and the lagged warming affect of a strong tropical Pacific El Nino event. We further highlight 2023 was significantly warmer than forecast and that much of this warming signal came from the southern hemisphere and requires further understanding.

How to cite: Dunstone, N., Smith, D., Scaife, A., Hermanson, L., Colman, A., and Folland, C.: Will 2024 be the first year above 1.5 C?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10574, https://doi.org/10.5194/egusphere-egu24-10574, 2024.

EGU24-11485 | ECS | Orals | CL4.3

Summer drought predictability in the Mediterranean region in seasonal forecasts 

Giada Cerato, Katinka Bellomo, and Jost von Hardenberg

The Mediterranean region has been identified as an important climate change hotspot, over the 21st century both air temperature and its extremes are projected to rise at a rate surpassing that of the global average and a significant decrease of average summer precipitation is projected, particularly for the western Mediterranean. On average, Mediterranean droughts have become more frequent and intense in recent years and are expected to become more widespread in many regions. These prolonged dry spells pose a substantial threat to agriculture and impact several socio-economic sectors. In this context, long-range weather forecasting has emerged as a promising tool for seasonal drought risk assessment. However, the interpretation of the forecasting products is not always straightforward due to their inherent probabilistic nature. Therefore, a rigorous evaluation process is needed to determine the extent to which these forecasts provide a fruitful advantage over much simpler forecasting systems, such as those based on climatology. 

In this study, we use the latest version of ECMWF’s seasonal prediction system (SEAS5) to understand its skill in predicting summer droughts. The Standardized Precipitation Evapotranspiration Index (SPEI) aggregated over different lead times is employed to mark below-normal dryness conditions in August. We use a comprehensive set of evaluation metrics to gain insight into the accuracy, systematic biases, association, discrimination and sharpness of the forecast system. Our findings reveal that up to 3 months lead time, seasonal forecasts show stronger association and discrimination skills than the climatological forecast, especially in the Southern Mediterranean, although the prediction quality in terms of accuracy and sharpness is limited. On the other hand, extending the forecast range up to 6 months lead time dramatically reduces its predictability skill, with the system mostly underperforming elementary climatological predictions. 

This approach is then extended to examine the full ensemble of seasonal forecasting systems provided by the Copernicus Climate Change Service (C3S) to test their skill in predicting droughts. Our findings can help an informed use of seasonal forecasts of droughts and the development of related climate services.

How to cite: Cerato, G., Bellomo, K., and von Hardenberg, J.: Summer drought predictability in the Mediterranean region in seasonal forecasts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11485, https://doi.org/10.5194/egusphere-egu24-11485, 2024.

EGU24-11930 | ECS | Posters on site | CL4.3

A global empirical system for probabilistic seasonal climate prediction based on generative AI and CMIP6 models  

Lluís Palma, Alejandro Peraza, Amanda Duarte, David Civantos, Stefano Materia, Arijit Nandi, Jesús Peña-Izquierdo, Mihnea Tufis, Gonzalo Vilella, Laia Romero, Albert Soret, and Markus Donat

Reliable probabilistic information at the seasonal time scale is essential across various societal sectors, such as agriculture, energy, or water management. Current applications of seasonal predictions rely on General Circulation Models (GCMs) that represent dynamical processes in the atmosphere, land surface, and ocean while capturing their linear and nonlinear interactions. However, GCMs come with an inherent high computational cost. In an operational setup, they are typically run once a month and at a lower temporal and spatial resolution than the ones needed for regional applications. Moreover, GCMs suffer from significant drifts and biases and can miss relevant teleconnections, resulting in low skill for particular regions or seasons. 

In this context, the use of generative AI methods that can model complex nonlinear relationships can be a viable alternative for producing probabilistic predictions with low computational demand. Such models have already demonstrated their effectiveness in different domains, i.e. computer vision, natural language processing, and weather prediction. However, although requiring less computational power, these techniques still rely on big datasets in order to be efficiently trained. Under this scenario, and with sufficiently high-quality global observational datasets spanning at most 70 years, the research trend has evolved into training these models using climate model output. 

In this work, we build upon the work presented by Pan et al., 2022, which introduced a conditional Variational Autoencoder (cVAE) to predict global temperature and precipitation fields for the October to March season starting from July initial conditions. We adopt several pre-processing changes to account for different biases and trends across the CMIP6 models. Additionally, we explore different architecture modifications to improve the model's performance and stability. We study the benefits of our model in predicting three-month anomalies on top of the climate change trend. Finally, we compare our results with a state-of-the-art GCM (SEAS5) and a simple empirical system based on the linear regression of classical seasonal indices based on Eden et al., 2015.

 

Pan, Baoxiang, Gemma J. Anderson, André Goncalves, Donald D. Lucas, Céline J.W. Bonfils, and Jiwoo Lee. 'Improving Seasonal Forecast Using Probabilistic Deep Learning'. Journal of Advances in Modeling Earth Systems 14, no. 3 (1 March 2022). https://doi.org/10.1029/2021MS002766.


Eden, J. M., G. J. van Oldenborgh, E. Hawkins, and E. B. Suckling. 'A Global Empirical System for Probabilistic Seasonal Climate Prediction'. Geoscientific Model Development 8, no. 12 (11 December 2015): 3947–73. https://doi.org/10.5194/gmd-8-3947-2015.

How to cite: Palma, L., Peraza, A., Duarte, A., Civantos, D., Materia, S., Nandi, A., Peña-Izquierdo, J., Tufis, M., Vilella, G., Romero, L., Soret, A., and Donat, M.: A global empirical system for probabilistic seasonal climate prediction based on generative AI and CMIP6 models , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11930, https://doi.org/10.5194/egusphere-egu24-11930, 2024.

EGU24-12969 | ECS | Orals | CL4.3

How unusual is the recent decade-long pause in Arctic summer sea ice retreat? 

Patricia DeRepentigny, François Massonnet, Roberto Bilbao, and Stefano Materia

The Earth has warmed significantly over the past 40 years, and the fastest rate of warming has occurred in and around the Arctic. The warming of northern high latitudes at a rate of almost four times the global average (Rantanen et al., 2022), known as Arctic amplification, is associated with sea ice loss, glacier retreat, permafrost degradation, and expansion of the melting season. Since the mid-2000s, summer sea ice has exhibited a rapid decline, reaching record minima in September sea ice area in 2007 and 2012. However, after the early 2010s, the downward trend of minimum sea ice area appears to decelerate (Swart et al., 2015; Baxter et al., 2019). This apparent slowdown and the preceding acceleration in the rate of sea ice loss are puzzling in light of the steadily increasing rate of greenhouse gas emissions of about 4.5 ppm yr−1 over the past decade (Friedlingstein et al., 2023) that provides a constant climate forcing. Recent studies suggest that low-frequency internal climate variability may have been as important as anthropogenic influences on observed Arctic sea ice decline over the past four decades (Dörr et al., 2023; Karami et al., 2023). Here, we investigate how unusual this decade-long pause in Arctic summer sea ice decline is within the context of internal climate variability. To do so, we first assess how rare this is deceleration of Arctic sea ice loss is by comparing it to trends in CMIP6 historical simulations. We also use simulations from the Decadal Climate Prediction Project (DCPP) contribution to CMIP6 to determine if initializing decadal prediction systems from estimates of the observed climate state substantially improves their performance in predicting the slowdown in Arctic sea ice loss over the past decade. As the DCPP does not specify the data or the methods to be used to initialize forecasts or how to generate ensembles of initial conditions, we also assess how different formulations affect the skill of the forecasts by analyzing differences between models. This work provides an opportunity to attribute this pause in Arctic sea ice retreat to interannual internal variability or radiative external forcings, something that observation analysis alone cannot achieve.

How to cite: DeRepentigny, P., Massonnet, F., Bilbao, R., and Materia, S.: How unusual is the recent decade-long pause in Arctic summer sea ice retreat?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12969, https://doi.org/10.5194/egusphere-egu24-12969, 2024.

EGU24-14341 | Posters on site | CL4.3

Compound Heat and Dry Events Influenced by the Pacific–Japan Pattern over Taiwan in Summer 

Szu-Ying Lin, Wan-Ling Tseng, Yi-Chi Wang, and MinHui Lo

Compound dry and hot events, characterized by elevated temperatures and reduced precipitation, pose interconnected challenges to human social economics, necessitating comprehensive strategies for mitigation and adaptation. This study focuses on the Pacific-Japan (PJ) pattern, a significant climate variability influencing summer climates in East Asia. While previous research has explored its impact on Japan and Korea, our investigation delves into its effects on Taiwan, a mountainous subtropical island with a population of approximately 24 million. Utilizing long-term temperature and rainfall data, along with reanalysis dynamic downscaling datasets, we examine the interannual impacts of the PJ pattern on summer temperature and compound heat and dry events. Our findings reveal a significant temperature increase during the positive phase of the PJ pattern, characterized by anticyclonic anomalous circulation over Taiwan. Additionally, both the Standardized Precipitation Index and soil water exhibit a decline during this phase, reflecting meteorological and hydrological drought conditions. A robust negative correlation (-0.7) between drought indices and temperature emphasizes the compound effect of heat and dry events during the PJ positive phase. This study enhances the understanding of the PJ pattern as a climate driver, describing its role in hot and dry summers over Taiwan. The insights gained, when integrated into seasonal prediction and early warning systems, can aid vulnerable sectors in preparing for potential heat and dry stress hazards.

How to cite: Lin, S.-Y., Tseng, W.-L., Wang, Y.-C., and Lo, M.: Compound Heat and Dry Events Influenced by the Pacific–Japan Pattern over Taiwan in Summer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14341, https://doi.org/10.5194/egusphere-egu24-14341, 2024.

EGU24-14379 | Posters on site | CL4.3

Linkage between Temperature and Heatwaves in Summer Taiwan to the Pacific Meridional Mode 

Chieh-Ting Tsai, Wan-Ling Tseng, and Yi-Chi Wang

Over the past century, Taiwan has gradually recognized the hazards posed by extreme heat events (EHT), prompting the development of mid-term adaptation strategies to address challenges in the coming decades. However, our understanding of decadal-scale temperature variations remains insufficient, requiring further research into influencing factors. Our study reveals the crucial role of the Pacific Meridional Mode (PMM) in modulating decadal-scale variations in summer temperatures in Taiwan. During the positive phase of PMM, warm sea surface temperature anomalies trigger an eastward-moving wave train extending into East Asia. This leads to the development of high-pressure circulations near Southeast Asia and Taiwan, enhancing the temperature increase. This mechanism has been reproduced in experiments using the Taiwan Earth System Model. Moreover, our study utilizes the calendar day 90th percentile of maximum temperature (CTX) as the threshold for extreme high-temperature events (EHT), while also employing the heatwaves magnitude scale (HWMS) as the criterion for defining heatwaves. During the positive phase of PMM, the frequency and duration of EHT increase, with variations observed across different regions. The overall intensity of heatwave events also strengthens, primarily due to extended durations. Notably, in a single city, this results in exposure of up to 800,000 person-days to EHT, presenting a tenfold increase compared to the annual effect observed in the long-term warming trend. These findings on the decadal-scale relationship between summer temperatures in Taiwan and PMM contribute to a deeper understanding of EHT and heatwaves events impacts, providing more nuanced insights for future regional strategies in mitigating heatwave disasters.

How to cite: Tsai, C.-T., Tseng, W.-L., and Wang, Y.-C.: Linkage between Temperature and Heatwaves in Summer Taiwan to the Pacific Meridional Mode, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14379, https://doi.org/10.5194/egusphere-egu24-14379, 2024.

EGU24-14688 | ECS | Orals | CL4.3

Exploring ML-based decadal predictions of the German Bight storm surge climate 

Daniel Krieger, Sebastian Brune, Johanna Baehr, and Ralf Weisse

Storm surges and elevated water levels regularly challenge coastal protection and inland water management along the low-lying coastline of the German Bight. Skillful seasonal-to-decadal (S2D) predictions of the local storm surge climate would be beneficial to stakeholders and decision makers in the region. While storm activity has recently been shown to be skillfully predictable on a decadal timescale with a global earth system model, surge modelling usually requires very fine spatial and temporal resolutions that are not yet present in current earth system models. We therefore propose an alternative approach to generating S2D predictions of the storm surge climate by training a neural network on observed water levels and large-scale atmospheric patterns, and apply the neural network to the available model output of a S2D prediction system. We show that the neural-network-based translation from large-scale atmospheric fields to local water levels at the coast works sufficiently well, and that several windows of predictability for the German Bight surge climate emerge on the S2D scale.

How to cite: Krieger, D., Brune, S., Baehr, J., and Weisse, R.: Exploring ML-based decadal predictions of the German Bight storm surge climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14688, https://doi.org/10.5194/egusphere-egu24-14688, 2024.

Atlantic meridional overturning circulation (AMOC) is one of the mechanisms for climate predictability and one of the properties that decadal climate predictions are attempting to predict. The starting point for AMOC decadal predictions is sensitive to the underlying data assimilation and/or initialization procedure. This means that different choices during the data assimilation procedure (e.g., assimilation method, assimilation window, data sources, resolution, nudging terms and strength, full field vs anomaly initialization/assimilation, etc) can result in a different mean and even variability of reconstructed ocean circulation. How coherent the AMOC initial states should be among the CMIP-like decadal prediction experiments? How good in general should the initial AMOC be for decadal predictions? And do initialization issues of the ocean circulation influence the prediction skill of other variables that are of interest for application studies? These are the questions that we were attempting to address in our study, where we analyzed twelve decadal prediction systems from the World Meteorological Organization Lead Centre for Annual-to-Decadal Climate Prediction project. We identify that the AMOC initialization influences the quality of predictions of the subpolar gyre (SPG). When predictions show a large initial error in their AMOC, they usually have low skill for predicting the internal variability of the SPG five years after the initialization.

How to cite: Polkova, I. and the Co-Authors: Initialization shock in the ocean circulation reduces skill in decadal predictions of the North Atlantic subpolar gyre, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15358, https://doi.org/10.5194/egusphere-egu24-15358, 2024.

EGU24-15476 | Posters on site | CL4.3

Statistics of sudden stratospheric warmings using a large model ensemble 

Sarah Ineson, Nick Dunstone, Adam Scaife, Martin Andrews, Julia Lockwood, and Bo Pang

Using a large ensemble of initialised retrospective forecasts (hindcasts) from a seasonal prediction system, we explore various statistics relating to sudden stratospheric warmings (SSWs). Observations show that SSWs occur at a similar frequency during both El Niño and La Niña northern hemisphere winters. This is contrary to expectation, as the stronger stratospheric polar vortex associated with La Niña years might be expected to result in fewer of these extreme breakdowns. We show that this similar frequency may have occurred by chance due to the limited sample of years in the observational record. We also show that in these hindcasts, winters with two SSWs, a rare event in the observational record, on average have an increased surface impact. Multiple SSW events occur at a lower rate than expected if events were independent but somewhat surprisingly, our analysis also indicates a risk, albeit small, of winters with three or more SSWs, as yet an unseen event.

How to cite: Ineson, S., Dunstone, N., Scaife, A., Andrews, M., Lockwood, J., and Pang, B.: Statistics of sudden stratospheric warmings using a large model ensemble, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15476, https://doi.org/10.5194/egusphere-egu24-15476, 2024.

EGU24-15709 | ECS | Orals | CL4.3

Predicting Atlantic and Benguela Niño events with deep learning  

Marie-Lou Bachelery, Julien Brajard, Massimiliano Patacchiola, and Noel Keenlyside

Extreme Atlantic and Benguela Niño events continue to significantly impact the tropical Atlantic region, with far-reaching consequences for African climate and ecosystems. Despite attempts to forecast these events using traditional seasonal forecasting systems, success remains low, reinforcing the growing idea that these events are unpredictable. To overcome the limitations of dynamical prediction systems, we introduce a deep learning-based statistical prediction model for Atlantic and Benguela Niño events. Our convolutional neural network (CNN) model, trained on 90 years of reanalysis data incorporating surface and 100m-averaged temperature variables, demonstrates the capability to forecast the Atlantic and Benguela Niño indices with lead times of up to 3-4 months. Notably, the CNN model excels in forecasting peak-season events with remarkable accuracy extending up to 5 months ahead. Gradient sensitivity analysis reveals the ability of the CNN model to exploit known physical precursors, particularly the connection to equatorial dynamics and the South Atlantic Anticyclone, for accurate predictions of Benguela Niño events. This study challenges the perception of the Tropical Atlantic as inherently unpredictable, underscoring the potential of deep learning to enhance our understanding and forecasting of critical climate events. 

How to cite: Bachelery, M.-L., Brajard, J., Patacchiola, M., and Keenlyside, N.: Predicting Atlantic and Benguela Niño events with deep learning , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15709, https://doi.org/10.5194/egusphere-egu24-15709, 2024.

EGU24-15974 | ECS | Posters virtual | CL4.3

Recalibrating DWD’s operational climate predictions: towards a user-oriented seamless climate service 

Alexander Pasternack, Birgit Mannig, Andreas Paxian, Amelie Hoff, Klaus Pankatz, Philip Lorenz, and Barbara Früh

The German Meteorological Service's (Deutscher Wetterdienst DWD) climate predictions website  (www.dwd.de/climatepredictions) offers a centralized platform for accessing post-processed climate predictions, including subseasonal forecasts from ECMWF's IFS and seasonal and decadal predictions from the German climate prediction system. The website design was developed in collaboration with various sectors to ensure uniformity across all time frames, and users can view maps, tables, and time series of ensemble mean and probabilistic predictions in combination with their skill. The available data covers weekly, 3-month, 1-year, and 5-year temperature means, precipitation sums and soil moisture for the world, Europe, Germany, and particular German regions. To achieve high spatial resolution, the DWD used the statistical downscaling method EPISODES. Moreover, within the BMBF project KIMoDIs (AI-based monitoring, data management and information system for coupled forecasting and early warning of low groundwater levels and salinisation) the DWD provides climate prediction data of further hydrological variables (e.g. relative humidity) with corresponding prediction skill on a regional scale.

However, all predictions on these time scales can suffer from inherent systematic errors, which can impact their usefulness. To address these issues, the recalibration method DeFoReSt was applied to decadal predictions, using a combination of 3rd order polynomials in lead and start time, along with a boosting model selection approach. This approach addresses lead-time dependent systematic errors, such as drift, as well as inaccuracies in representing long-term changes and variability.

This study highlights the improved accuracy of the recalibration approach on decadal predictions due to an increased polynomial order compared to the original approach, and its different impact on global and regional scales. It also explores the feasibility of transferring this approach to predictions with shorter time horizons of the provided variables.

How to cite: Pasternack, A., Mannig, B., Paxian, A., Hoff, A., Pankatz, K., Lorenz, P., and Früh, B.: Recalibrating DWD’s operational climate predictions: towards a user-oriented seamless climate service, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15974, https://doi.org/10.5194/egusphere-egu24-15974, 2024.

EGU24-16366 | ECS | Orals | CL4.3

Decadal predictions outperform projections in forecasting winter precipitation over the Mediterranean region 

Dario Nicolì, Silvio Gualdi, and Panos Athanasiadis

The Mediterranean region is highly sensitive to climate change, having experienced an intense warming and drying trend in recent decades, primarily due to the increased concentrations of anthropogenic greenhouse gases. In the context of decision-making processes, there is a growing interest in understanding the near-term climate evolution of this region.

In this study, we explore the climatic fluctuations of the Mediterranean region in the near-term range (up to 10 years ahead) using two different products: projections and decadal predictions. The former are century-scale climate change simulations initialized from arbitrary model states to which were applied anthropogenic and natural forcings. A major limitation of climate projections is their limited information regarding the current state of the Earth’s climate system. Decadal climate predictions, obtained by constraining the initial conditions of an ensemble of model simulations through a best estimate of the observed climate state, provide a better understanding of the next-decade climate and thus represent an invaluable tool in assisting climate adaptation.

Using retrospective forecasts from eight decadal prediction systems contributing to the CMIP6 Decadal Climate Prediction Project (CMIP6 DCPP) and the corresponding ensemble of non-initialized projections, we compare the capabilities of the state-of-the-art climate models in predicting future climate changes of the Mediterranean region for some key quantities so as to assess the added value of initialization. 

Beyond the contribution of external forcings, the role of internal variability is also investigated since part of the detected predictability arises from internal climate variability patterns affecting the Mediterranean. The observed North Atlantic Oscillation, the dominant climate variability pattern in the Euro-Atlantic domain, as well as its  impact on wintertime precipitation over Europe are well reproduced by decadal predictions, especially over the Mediterranean, outperforming projections. We also apply a sub-sampling method to enhance the respective signal-to-noise ratio and consequently improve precipitation skill over the Mediterranean.

How to cite: Nicolì, D., Gualdi, S., and Athanasiadis, P.: Decadal predictions outperform projections in forecasting winter precipitation over the Mediterranean region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16366, https://doi.org/10.5194/egusphere-egu24-16366, 2024.

EGU24-16985 | Posters on site | CL4.3

Investigating signals in summer seasonal forecasts over the North Atlantic/European region 

Julia Lockwood, Nick Dunstone, Kristina Fröhlich, Ramón Fuentes Franco, Anna Maidens, Adam Scaife, Doug Smith, and Hazel Thornton

The current generation of seasonal forecast models struggle to skilfully predict dynamical circulation over the North Atlantic and European region in boreal summer.  Using two different state-of-the-art seasonal prediction systems, we show that tropical rainfall anomalies drive a circulation signal in the North Atlantic/Europe via the propagation of Rossby waves.  The wave, however, is shifted eastwards compared to observations, so the signal does not contribute positively to model skill.  Reasons for the eastward shift of the Rossby wave are investigated, as well as other drivers of the signal in this region.  Despite the errors in the waves, the fact that seasonal forecast models do predict dynamical signals over the North Atlantic/Europe signifies seasonal predictability over this region beyond the climate change trend, and understaning the cause of the errors could lead to skilful predictions.

How to cite: Lockwood, J., Dunstone, N., Fröhlich, K., Fuentes Franco, R., Maidens, A., Scaife, A., Smith, D., and Thornton, H.: Investigating signals in summer seasonal forecasts over the North Atlantic/European region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16985, https://doi.org/10.5194/egusphere-egu24-16985, 2024.

EGU24-17418 | Posters on site | CL4.3

Strengthening seasonal forecasting in the Middle East & North Africa (MENA) through the WISER Programme. 

Stefan Lines, Nicholas Savage, Rebecca Parfitt, Andrew Colman, Alex Chamberlain-Clay, Luke Norris, Heidi Howard, and Helen Ticehurst

In this presentation, we introduce the WISER MENA projects SeaFOAM (Seasonal Forecasting Across MENA) and SeaSCAPE (Seasonal Co-Production and Application in MENA). These projects explore both the improvement to the regional-level seasonal forecast in the MENA region, as well as how to tailor the information in ways useful to a range of climate information stakeholders. SeaFOAM works alongside Maroc Meteo, Morocco's National Meteorological and Hydrological Service (NMHS) and the Long Range Forecasting node of the Northern Africa WMO Regional Climate Centre (RCC), to develop a framework for objective seasonal forecasting. This approach will blend techniques such as bias correction via local linear regression and canonical correlation analysis (CCA), with skill-assessed sub-selected models, to improve forecasting accuracy. Multiple drivers of rainfall variability, including the North Atlantic Oscillation (NAO) and Mediterranean Oscillation (MO), are investigated for their calibration potential. SeaSCAPE works with the WMO and various partners across MENA to understand the use of seasonal information in multiple sectors, exploring existing gaps and needs. Through stakeholder engagement workshops, training and bespoke support for the Arab Climate Outlook Forum (ArabCOF), SeaSCAPE operates collaboratively to tailor regional and national-level climate information to improve accessibility and usability of climate information on seasonal timescales.

How to cite: Lines, S., Savage, N., Parfitt, R., Colman, A., Chamberlain-Clay, A., Norris, L., Howard, H., and Ticehurst, H.: Strengthening seasonal forecasting in the Middle East & North Africa (MENA) through the WISER Programme., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17418, https://doi.org/10.5194/egusphere-egu24-17418, 2024.

EGU24-17585 | Orals | CL4.3

Skill of wind resource forecasts on the decadal time scale 

Kai Lochbihler, Ana Lopez, and Gil Lizcano

Accurate forecasts of the natural resources of renewable energy production have become not only a valuable but a crucial tool for managing the associated risks of specific events, such as wind droughts. Wind energy, alongside with solar power, now provide a substantial part to the renewable energy share of the global energy production and growth in this sector will most likely further increase. The naturally given fluctuations of wind resources, however, pose a challenge for maintaining a stable energy supply, which, at the end of the chain, can have an impact on the energy market prices.
Operational short-term forecasting products for the wind energy sector (multiple days) are already commonly available and seasonal to sub seasonal forecasting solutions (multiple months) can provide valuable skill and are gaining in popularity. On the other side of the spectrum, typically on a time scale of multiple decades, we find risk assessment based on climate change projections. In between the long and short term time scales, however, there is a gap that still needs to be filled to achieve seamless prediction of risks that are relevant for the energy sector: decadal predictions.

Here, we present the results of an evaluation study of a multi-model decadal prediction ensemble (DCPP) for a selection of wind development regions in Europe. The evaluation is based on multiple decades long hindcasts and carried out with a focus on the skill of predicting specific event types of wind resource availability in a probabilistic context, alongside with basic deterministic skill measures. We further investigate specific event constellations and their large-scale drivers that, in combination, can provide windows of opportunity with enhanced predictive skill. We conclude with a discussion on how this hybrid approach can be used to potentially increase not only forecast skill but also the trust of the end user.

How to cite: Lochbihler, K., Lopez, A., and Lizcano, G.: Skill of wind resource forecasts on the decadal time scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17585, https://doi.org/10.5194/egusphere-egu24-17585, 2024.

EGU24-19229 | ECS | Orals | CL4.3

Comparing the seasonal predictability of Tropical Pacific variability in EC-Earth3 at two different horizontal resolutions 

Aude Carreric, Pablo Ortega, Vladimir Lapin, and Francisco Doblas-Reyes

Seasonal prediction is a field of research attracting growing interest beyond the scientific community due to its strong potential to guide decision-making in many sectors (e.g. agriculture and food security, health, energy production, water management, disaster risk reduction) in the face of the pressing dangers of climate change.

Among the various techniques being considered to improve the predictive skill of seasonal prediction systems, increasing the horizontal resolution of GCMs is a promising avenue. There are several indications that higher resolution versions of the current generation of climate models might improve key air-sea teleconnections, decreasing common biases of global models and improving the skill to predict certain regions at seasonal scales, e.g. in tropical sea surface temperature.

In this study, we analyze the differences in the predictive skill of two different seasonal prediction systems, based on the same climate model EC-Earth3 and initialized in the same way but using two different horizontal resolutions. The standard (SR) and high resolution (HR) configurations are based on an atmospheric component, IFS, of ~100 km and ~40 km of resolution respectively and on an ocean component, NEMO3.6, of ~100 km and ~25 km respectively. We focus in particular on the Tropical Pacific region where statistically significant improvements are found in HR with respect to SR for predicting ENSO and its associated climate teleconnections. We explore some processes that can explain these differences, such as the simulation of the tropical ocean mean state and atmospheric teleconnections between the Atlantic and Pacific tropical oceans. 

A weaker mean-state bias in the HR configuration, with less westward extension of ENSO-related SST anomalies, leads to better skill in ENSO regions, which can also be linked to better localization of the atmospheric teleconnection with the equatorial Atlantic Ocean. It remains to be assessed if similar improvements are consistently identified for HR versions in other forecast systems, which would prompt their routine use in seasonal climate prediction.

How to cite: Carreric, A., Ortega, P., Lapin, V., and Doblas-Reyes, F.: Comparing the seasonal predictability of Tropical Pacific variability in EC-Earth3 at two different horizontal resolutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19229, https://doi.org/10.5194/egusphere-egu24-19229, 2024.

EGU24-19251 | Orals | CL4.3 | Highlight

The opportunities and challenges of near-term climate prediction 

Hazel Thornton

Accurate forecasts of the climate of the coming season and years are highly desired by many sectors of society. The skill of near-term climate prediction in winter in the North Atlantic and European region has improved over the last decade associated with larger ensembles, improving models and boosting of the prediction signal using intelligent post processing. International collaboration has improved the availability of forecasts and promoted the uptake of forecasts by different sectors. However, significant challenges remain, including summer prediction, understanding the risk of extremes within a season, multi-seasonal extremes and how best to post process the forecasts to aid decision making. This talk will summarise recent near-term climate prediction research activities at the UK Met Office and will detail our experience of providing such forecasts to the energy and water sectors.  

How to cite: Thornton, H.: The opportunities and challenges of near-term climate prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19251, https://doi.org/10.5194/egusphere-egu24-19251, 2024.

This study focuses on applying machine learning techniques to bias-correct the seasonal temperature forecasts provided by the Copernicus Climate Change Service (C3S) models. Specifically, we employ bias correction on forecasts from five major models: UK Meteorological Office (UKMO), Euro-Mediterranean Center on Climate Change (CMCC), Deutscher Wetterdienst (DWD), Environment and Climate Change Canada (ECCC), and Meteo-France. Our primary objective is to assess the performance of our bias correction model in comparison to the original forecast datasets. We utilise temperature-based indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI) to evaluate the effectiveness of the bias-corrected seasonal forecasts. These indices served as valuable metrics to gauge the predictive capability of the models, especially in forecasting natural cascading hazards such as wildfires, droughts, and floods. The study involved an in-depth analysis of the bias-corrected forecasts, and the derived indices were crucial in understanding the models' ability to predict temperature-related extreme events. The results of this research contribute valuable information for decision-making and planning across various sectors, including disaster risk management and environmental protection. Through a comprehensive evaluation of machine learning-based bias correction techniques, we enhance the accuracy and applicability of seasonal temperature forecasts, thereby improving preparedness and resilience to climate-related challenges. 

How to cite: Mbuvha, R. and Nikraftar, Z.: Machine Learning Approaches to Improve Accuracy in Extreme Seasonal Temperature Forecasts: A Multi-Model Assessment , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19297, https://doi.org/10.5194/egusphere-egu24-19297, 2024.

EGU24-19359 | ECS | Posters on site | CL4.3

Seasonal forecast of the late boreal winter temperature based on solar forcing and QBO 

Mikhail Vokhmianin, Antti Salminen, Kalevi Mursula, and Timo Asikainen

The ground temperature variability in the Northern Hemisphere winter is greatly influenced by the state of the polar vortex. When the vortex collapses during sudden stratospheric warmings (SSWs), rapid changes in stratospheric circulations propagate downward to the troposphere in the subsequent weeks. The ground effect following SSWs is typically manifested as the negative phase of the North Atlantic Oscillation. Our findings reveal a higher frequency of cold temperature anomalies in the Northern part of Eurasia during winters with SSWs, and conversely, warm anomalies in winters with a strong and stable vortex. This behavior is particularly evident when temperature anomalies are categorized into three equal subgroups, or terciles. Recently, we developed a statistical model that successfully predicts SSW occurrences with an 86% accuracy rate. The model utilizes the stratospheric Quasi-Biennial Oscillation (QBO) phase and two parameters associated with solar activity: the geomagnetic aa-index as a proxy for energetic particle precipitations and solar irradiance. In this study, we explore the model's potential to provide a seasonal forecast for ground temperatures. We assess the probabilities of regional temperature anomalies falling into the lowest or highest terciles based on the predicted weak or strong vortex state. Additionally, we demonstrate that the QBO phase further enhances the forecast quality. As the model provides SSW predictions as early as preceding August, our results carry significant societal relevance as well, e.g., for the energy sector, which is highly dependent on prevailing weather conditions.

How to cite: Vokhmianin, M., Salminen, A., Mursula, K., and Asikainen, T.: Seasonal forecast of the late boreal winter temperature based on solar forcing and QBO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19359, https://doi.org/10.5194/egusphere-egu24-19359, 2024.

EGU24-1089 | ECS | Posters on site | CL4.5

Evaluation of Mesoscale Eddy-Ice Interaction in the Southern Ocean using High-Resolution Models 

Stephy Libera, Hugues Goosse, and Dian Putrasahan

Antarctic sea ice plays an important role in the global climate through its influence on local and global oceanic and atmospheric circulations, planetary radiative balance, and the crucial support it provides for Southern Ocean ecosystem. Understanding the physical processes influencing Antarctic sea ice, and the drivers of its change are therefore of broad interest. The sea ice–covered the Southern Ocean, has relatively weak stratification in the upper ocean, where a relatively thin halocline separates the cold winter mixed layer from significantly warmer ocean interior. When warmer waters from the ocean interior enter the mixed layer, it can melt sea ice at its base. Features in the upper ocean, like mesoscale eddies can impact the thermohaline structure and stratification in this region and can impact the heat delivered to the surface. However, the mesoscale dynamics in the polar regions, especially under sea ice cover, is little known due to the limited observations and the inability of many numerical models to resolve mesoscale processes in the high latitudes.   

This study aims to understand better the interaction between ocean mesoscale eddies and sea ice using high-resolution European Eddy RIch Earth System Models (EERIE) models. We investigate the effect of mesoscale eddies locally, and the integrated effect of eddy-sea ice interaction in the circumpolar Southern Ocean. Previous studies have identified eddy ice interactions to vary within regions of varying sea ice concentrations, such as in the high concentration pack ice and low-concentration marginal ice zones. The variations in the eddy-sea ice interaction in the Southern Ocean, within the open ocean, pack ice, and marginal ice zones are further investigated in this study.  

How to cite: Libera, S., Goosse, H., and Putrasahan, D.: Evaluation of Mesoscale Eddy-Ice Interaction in the Southern Ocean using High-Resolution Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1089, https://doi.org/10.5194/egusphere-egu24-1089, 2024.

EGU24-1430 | Orals | CL4.5

Evaluation of the K-scale model hierarchy across MetOffice models. 

Claudio Sanchez, Huw Lewis, Richard Jones, James Warner, and Dasha Shchepanovska

Models resolving km-scale processes, such as deep convection, improve the representation of precipitation associated to several processes at sub-synoptic scales, e.g. diurnal cycle, mesoscale convective systems or tropical cyclones. These models generally improve extremes and add value to hazard forecasting, in particular over the tropics. However, these models have been unaffordable to run on a pseudo-global scale until recently and thus their impact in large scale processes is not well known.

Aiming to develop the next generation of Met Office weather and climate prediction systems, the UK K-scale project has been established to evaluate the technical challenges, the scientific improvements and the predictability benefits of km-scale models. The first step of the program is the development of a K-scale “model hierarchy”, a family of simulations across several resolutions and two scientific configurations under the same MetOffice Unified Modelling framework (MetUM). Such hierarchy comprises a generic global model at 12km resolution, realizations at different resolutions of the Cyclic Tropical Channel (CTC), which is a global model in the zonal with north and south boundaries at 26N and 44S respectively, and limited area models (LAMS) over several locations at 2.2km. The two scientific configurations are (i) a global-like aimed at global resolutions above 10km, which includes a parametrization of shallow and mid-level convection, and (ii) a regional-like aimed to km- and sub-km-scale LAM which does not parametrize convection at any level.

Our results from simulations of the 40-day DYAMOND summer and winter periods show than differences between global-like and regional-like configurations at the same resolution can be as large as differences between models at 12km and 4.4km resolution with the same configuration. When all convective processes are not parametrized in the whole tropics at km-scale resolution, the PDF of precipitation shift towards higher intensities, the diurnal cycle improves in several regions, and the wet and dry biases around the E-W boundaries of LAMs are reduced.

The African tropical easterly jet is represented differently across the simulations; with a stronger jet in global-like configurations with convective parametrization. A significant change in mean-state upper wind over the Indian Ocean has potential implications on both subsidence over East Africa, and wind shear over West Africa. These are both tied to widespread rainfall patterns over Africa.

Regional-like configurations at km-scale resolution capture the kinetic energy spectra slope -5/3, poorly represented by the global-like model at 12km. The uncertainty growth across the kscale hierarchy is explored with the use of a twin experiment methodology, and in particular the role of equatorial waves in the error growth across resolutions and science configurations.

How to cite: Sanchez, C., Lewis, H., Jones, R., Warner, J., and Shchepanovska, D.: Evaluation of the K-scale model hierarchy across MetOffice models., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1430, https://doi.org/10.5194/egusphere-egu24-1430, 2024.

EGU24-2040 | ECS | Posters on site | CL4.5

The representation of tropical cyclones in high resolution coupled climate simulations 

Paolo Ghinassi and Paolo Davini

Tropical cyclones (TCs) are one of the most impactful weather phenomena on Earth. Their formation and development depends on small-scale processes like air-sea interaction and convection. These processes pose challenges for climate models since they are often misrepresented and act as sources of uncertainty. Additionally, TCs interact with both tropical and extratropical large-scale circulation, contributing to the upscale error propagation. The accurate representation of such physical processes in climate models therefore is crucial for the correct simulation not only of TCs but of the entire climate system. Until a few years ago, these small scale processes could not be resolved explicitly in traditional state-of-the-art coupled climate simulations due to a too coarse horizontal resolution. Nowadays that we are able to run climate simulations at a very high resolution (less than 10 km) and explicitly resolve such processes we expect to have a much more realistic representation of the intensity, frequency, and structure of TCs in climate models.

For this study, we consider data from the nextGEMS and Climate Digital Twin (part of the Destination Earth initiative) experiments (with an horizontal resolution up to 2.5 km), assessing model performance comparing them with both ERA5 reanalysis and with observational data sets such as IBTrACS to detect model biases. An algorithm for the detection and tracking of TCs based on the TempestExtremes library is used to detect and track TCs at first on a coarser resolution grid on a single time step (e.g., every 6 hours). Then, a series of variables at the original model resolution are saved in the vicinity of the TC centres, to allow examining their finer structure with an unprecedented level of detail. This diagnostic is part of the Application for Quality assessment and Uncertainty quAntification (AQUA) model evaluation framework developed within the Destination Earth project. Our analysis considers the TCs intensity (e.g. cyclones classification, wind pressure relationship), TCs structure (e.g. examining wind gusts and rain bands) and TCs temporal and spatial distribution (computing and analysing TCs trajectories). Preliminary results enlight the ability of these very high-resolution climate simulations to represent TCs features in a much more realistic way, especially close to the smallest resolved scales. Moreover, an increased horizontal resolution is beneficial to reduce model biases, enabling climate models to simulate TCs with a magnitude comparable to the observations.

How to cite: Ghinassi, P. and Davini, P.: The representation of tropical cyclones in high resolution coupled climate simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2040, https://doi.org/10.5194/egusphere-egu24-2040, 2024.

EGU24-2359 | ECS | Posters on site | CL4.5

Simulating the Earth system with interactive aerosols at the kilometer scale 

Philipp Weiss and Philip Stier

Aerosols originate from natural processes and human activities. They scatter and absorb radiation but also act as condensation nuclei in clouds. How these interactions influence the climate is still uncertain. New climate simulations at the kilometer-scale allow us to examine long-standing questions related to these interactions such as the complex effects on convective clouds. To perform kilometer-scale simulations with interactive aerosols, we developed the reduced-complexity aerosol module HAM-lite and coupled it to the climate model ICON-Sapphire. HAM-lite is based on and fully traceable to the complex aerosol module HAM. Aerosols are represented as an ensemble of log-normal modes with prescribed sizes and compositions.

We present first global simulations with ICON-Sapphire and HAM-lite at resolutions of about five kilometers and over periods of a few months. The sea surface temperature and sea ice are prescribed with boundary conditions of AMIP, and the initial conditions of the atmosphere and land are derived from the operational analysis of ECMWF. The aerosols are represented by two pure modes, one of dust and one of sea salt, and two internally mixed modes, both of organic carbon, black carbon, and sulfate. The first mixed mode represents aerosols from biomass burning emissions and the second mixed mode represents aerosols from anthropogenic and volcanic emissions.

The simulations capture key elements of the global aerosol cycle, of which some are missing entirely in coarse-scale simulations. For example, cold pool fronts drive intense dust storms over the Sahara and tropical cyclones interact with sea salt aerosols in the Pacific. We observe the transport of dust aerosols across the ocean, the wash out of sea salt aerosols by rain bands, and the updraft of biomass burning aerosols over land. We evaluate the observations with a combination of remote-sensing and in-situ data. We also compare the results to coarse-scale climate simulations. To understand processes like updraft by convection or deposition by rain, we examine the distribution of aerosols throughout the vertical column.

How to cite: Weiss, P. and Stier, P.: Simulating the Earth system with interactive aerosols at the kilometer scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2359, https://doi.org/10.5194/egusphere-egu24-2359, 2024.

We propose a protocol for observational intensive intercomparison experiments of global storm-resolving models, targeting for evaluation by the EarthCARE satellite, the new satellite scheduled to be launched in May 2024. Previously, a month-long or 40-day simulation of an intercomparison of global storm-resolving models was conducted under the DYAMOND (the DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains) project. Global storm-resolving models can simulate meso-scale systems in the global domain, and it has been shown that the month-long simulations under the DYAMOND project reproduce the evolution of meso-scale convective systems comparable to nature in many aspects. As a next step of the feasibility of the global storm-resolving models, two directions of the intercomparison experiments are considered. One is to extend the simulation time to cover a longer period, such as a one-year experiment with a seasonal march (Takasuka et al. 2024, in preparation). The other is to evaluate with intensive observations. Here, we propose a possible protocol for the short-term (a few weeks to a month) intercomparison experiment to evaluate GSRM results with observation by the EarthCARE satellite and the coordinated grand observation campaign called ORCESTRA.

The EarthCARE satellite will enable the world's first observations of Doppler velocities from space using radar. This groundbreaking capability allows for the observational understanding of global snow and raindrop falling velocities. In numerical climate and weather forecasting models, falling velocities of snow and raindrops have traditionally relied on empirical formulas based on fragmented observations, lacking comprehensive validation through global observations. These falling velocities have frequently been used as tuning parameters for numerical models. The falling velocity of upper-level clouds directly impacts radiation balance through variations in cloud amount. In contrast, the raindrop velocity influences the formation of cold pools and the organization of convective clouds. After obtaining Doppler velocity observations from the EarthCARE satellite, reliance on these falling velocities as tuning parameters becomes obsolete, introducing observational constraints. Conversely, altering these falling velocities from traditional prescribed values in numerical models leads to deviations in model climatology and equilibrium states from observations, necessitating refinement of other processes, which require the resolution of new compensatory errors. This presentation analyzes the characteristics of Doppler velocities using the global non-hydrostatic model NICAM and discusses the impact of snow and raindrops falling velocities. Specifically, utilizing the EarthCARE-like simulated data based on a global 220m mesh NICAM simulation, we aim to comprehend the global view of falling velocity characteristics and gain insights to analyze the EarthCARE satellite observational data.

How to cite: Satoh, M., Roh, W., and Matsugishi, S.: Proposal for an Intensive Short-term Intercomparison Experiment of Global Storm Resolution Models for Evaluation by EarthCARE Satellite Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3359, https://doi.org/10.5194/egusphere-egu24-3359, 2024.

EGU24-5731 | ECS | Orals | CL4.5

Identifying cloud objects in the km-scale earth system model ICON 

Vanessa Rieger, Paul Splechtna, and Aiko Voigt

Clouds crucially impact Earth’s climate. The distribution of clouds, horizontally and vertically, influences the radiative transfer through the atmosphere. Hence, to correctly compute the radiative transfer, it is important to understand the horizontal and vertical distribution of clouds.  Km-scale earth system models enable to resolve convection explicitly and offer the potential to represent cloud patterns more realistically. We investigate simulations of the earth system model ICON with a horizontal resolution of 5 km performed within the project nextGEMS. We identify cloud objects using connected component labelling. The method is applied to the vertically integrated cloud field as well as to the global three-dimensional cloud field. We analyse the distribution of cloud objects, their water and ice content as well as their fractal dimension on a global and regional scale. The choice of the threshold for identifying cloud objects strongly influences the analysis of the objects.

How to cite: Rieger, V., Splechtna, P., and Voigt, A.: Identifying cloud objects in the km-scale earth system model ICON, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5731, https://doi.org/10.5194/egusphere-egu24-5731, 2024.

EGU24-6596 | ECS | Orals | CL4.5

Improved northern hemispheric atmospheric blocking properties in two storm-resolving climate models 

Edgar Dolores Tesillos and Olivia Martius

Atmospheric blocking and its associated extreme phenomena, such as hot and cold spells represent a risk to society. Current climate models struggle to simulate the atmospheric blocking properties, making it difficult to understand the underlying physical processes and raising uncertainty about their evolution under warming. Today, several climate models attempt to better resolve small-scale processes and have demonstrated their ability to convincingly simulate them; however, few studies have evaluated the impact of these tunings on large-scale flow.

Here, we investigate the representation of Atmospheric blocking characteristics in the two new generations of storm-resolving Earth-system models (nextGEMS), consisting of the Icosahedral Nonhydrostatic Weather and Climate Model (ICON) and the ECMWF Integrated Forecasting System (hereafter only IFS). These models are run at high horizontal resolution, ICON at 5 km (convective parameterization off) and IFS at 4.4 km and 28 km (convective parameterization on). Both models are fully coupled models with eddy-resolving ocean models. The five years of simulations are compared with the reanalysis ERA5 and one CMIP6 model (MPI-ESM1-2-LR). Atmospheric blockings are identified and tracked using a Lagrangian approach based on the geopotential height anomaly at 500 hPa. Properties such as intensity, size, and zonal speed are evaluated.

The nextGEMS showed an increased skill in reproducing atmospheric blocking at the system scale. Firstly, the Atmospheric blocking intensity, spatial extension, and zonal speed are closer to the ERA5 than the CMIP6 model. However, the block intensity and size in the IFS model are simulated better than in the ICON model, and its improvement increases at the finest resolution, 4.4 km. This improvement at higher resolution coincides with more precipitation upstream to the block center than at lower resolution during the onset phase. The latter is consistent with recent studies, indicating that increased moist processes contribute to stronger and bigger blocks. Thus, we provide insights into how the large-scale flow can benefit from the storm-resolving climate models by increasing their skill to simulate atmospheric blocking characteristics and the diabatic processes at higher resolution in a fully coupled system. A more comprehensive evaluation of the large-scale flow in the nextGEMS models will be performed with longer runs.

How to cite: Dolores Tesillos, E. and Martius, O.: Improved northern hemispheric atmospheric blocking properties in two storm-resolving climate models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6596, https://doi.org/10.5194/egusphere-egu24-6596, 2024.

EGU24-7170 | Orals | CL4.5

Projections of future climate changes from the cloud-permitting greenhouse warming simulations 

Sun-Seon Lee, Ja-Yeon Moon, Axel Timmermann, Jan Streffing, Tido Semmler, and Thomas Jung

Assessing the future risk of natural disasters, securing sustainable energy and water resources, and developing strategies for adapting to climate change remain challenging due to the large uncertainties in regional-scale climate projections. Recent efforts to address this issue include km-scale coupled climate model simulations that resolve mesoscale processes in the atmosphere and ocean, as well as their interactions with the large-scale environment and small-scale topographic features. Our presentation shows the first results from a series of global 9 km-scale greenhouse warming simulations using the AWI Climate Model Version 3 which is based on the OpenIFS atmosphere model at TCO1279 resolution and 137 vertical levels and the FESOM2 ocean model at 4-15 km resolution. By comparing a set of consecutive 10-year time-slice simulations forced by the CMIP6 SSP585 scenario with a transient simulation at a lower-resolution (31 km in the OpenIFS), we identify key differences in weather and climate-related phenomena, including tropical cyclones, ENSO, and regional climate change features that can be attributed to km-scale dynamics in clouds and atmospheric circulation patterns. The findings from our cloud-permitting climate simulations provide valuable insights into the role of small-scale processes in the sensitivity of the regional and global climate.

How to cite: Lee, S.-S., Moon, J.-Y., Timmermann, A., Streffing, J., Semmler, T., and Jung, T.: Projections of future climate changes from the cloud-permitting greenhouse warming simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7170, https://doi.org/10.5194/egusphere-egu24-7170, 2024.

EGU24-8254 | ECS | Orals | CL4.5

Demonstrating the potential of km-scale multi-annual coupled global simulations in nextGEMS: a (urban) surface perspective 

Xabier Pedruzo-Bagazgoitia, Tobias Becker, Sebastian Milinski, Thomas Rackow, Irina Sandu, Souhail Boussetta, Emanuel Dutra, Ioan Hadade, Joao Martins, Joe McNorton, Birgit Sützl, and Nils Wedi

The nextGEMS project is dedicated to develop global coupled earth-system models for multidecadal climate projections at a kilometre-scale resolution. By harnessing the strengths of high spatial resolution, the project seeks to improve the representation of physical processes and provide climate information at spatial scales that align with real-world measurements. Preparing for 30-year production runs, nextGEMS has achieved significant milestones, including the successful completion of five-year global coupled runs with a 5 km spatial resolution by two different Earth-System models: ICON, and ECMWF’s Integrated Forecasting System (IFS) coupled to the sea ice-ocean model FESOM. In this work we focus on the km-scale IFS-FESOM configuration, along with a comparable set of coarser IFS simulations coupled to either FESOM or NEMO ocean models.

We first provide a brief overview of the most relevant scientific modifications on IFS and FESOM through the development cycles needed to perform multi-annual simulations: a reduction of the global water and energy imbalance by orders of magnitude, as well as the modification in cloud physics parameters to provide a stable climate, improved coupling of ocean surface currents and fluxes, and the addition of improved high-resolution land use and land cover maps.

We further investigate the impact that the new refined surface maps have on the representation of climate at the surface and near-surface. We first explore the spatio-temporal surface-atmosphere coupling in these km-scale simulations. We then focus on more local phenomena: In particular, we pioneer the study of urban climate via coupled global multiannual simulations and explore surface-atmosphere interactions over urbanized areas, by combining refined land use/land cover maps with the active urban scheme in IFS. We find a more realistic spatial distribution of surface temperature in both urban and rural areas, especially noticeable at spatial resolutions of 9km and finer. By showing that the diurnal cycle of urban heat island intensity exhibits improved accuracy in numerous large European urban areas, our global simulations can provide local granularity at the scale of individual cities The enhancements in representing urban climate features are quantified through reduced bias, root-mean square error, and increased correlation with successively increasing model resolution.

How to cite: Pedruzo-Bagazgoitia, X., Becker, T., Milinski, S., Rackow, T., Sandu, I., Boussetta, S., Dutra, E., Hadade, I., Martins, J., McNorton, J., Sützl, B., and Wedi, N.: Demonstrating the potential of km-scale multi-annual coupled global simulations in nextGEMS: a (urban) surface perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8254, https://doi.org/10.5194/egusphere-egu24-8254, 2024.

EGU24-8565 | Orals | CL4.5

Ocean Eddy-rich Climate Simulation with IFS-FESOM 

Rohit Ghosh, Suvarchal K Cheedela, Nikolay Koldunov, Amal John, Jan Streffing, Vasco Müller, Sebastian Beyer, Thomas Rackow, Dmitry Sidorenko, Sergey Danilov, and Thomas Jung

Efforts to enhance climate model simulations by achieving higher resolutions to explicitly capture sub-grid scale processes constitute a central objective in contemporary climate modeling. In this pursuit, our focus is on resolving a pivotal element of the climate system—the ocean meso-scale eddies. At the Alfred-Wegener-Institute, we are working towards this objective by employing the ocean-sea ice model FESOM at approximately 5km horizontal resolution (NG5), coupled with the atmospheric model IFS at a 9km horizontal resolution (tco1279).

This presentation showcases preliminary results from the control simulations of IFS-FESOM under 1950 radiative conditions. Furthermore, we provide an initial glimpse into results from a historical simulation starting in 1950 with the same model configuration. Our analysis illuminates how ocean eddy-rich regions are portrayed in our simulations relative to observations. We delineate the changes and improvements in key climate components, encompassing North Atlantic/Southern Ocean temperatures, NAO, atmospheric blocking, midlatitude storm tracks, ENSO, Monsoon, ITCZ, Hadley/Walker Cells, MJO, meridional overturning, gyre circulations, as well as Arctic/Antarctic Sea ice dynamics under such high resolution.

Moreover, we endeavor to demonstrate how regional high-frequency weather and climate processes can be accurately represented in such simulations, including capturing the nature of regional extremes. In essence, our goal is to illustrate how advancing model resolution to resolve ocean eddies contributes to a more comprehensive representation of the climate system.



How to cite: Ghosh, R., Cheedela, S. K., Koldunov, N., John, A., Streffing, J., Müller, V., Beyer, S., Rackow, T., Sidorenko, D., Danilov, S., and Jung, T.: Ocean Eddy-rich Climate Simulation with IFS-FESOM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8565, https://doi.org/10.5194/egusphere-egu24-8565, 2024.

EGU24-8603 | Orals | CL4.5

Cloud-feedbacks in global km-scale earth system model simulations 

Ja-Yeon Moon, Sun-Seon Lee, Axel Timmermann, Jan Streffing, Tido Semmler, and Thomas Jung

Clouds are an important regulator of earth’s radiation balance. Therefore, future changes in clouds and corresponding feedbacks are likely to influence global climate sensitivity. How clouds respond to greenhouse warming on global and regional scales is still not well understood. Here we present first results from a km-scale, cloud-permitting greenhouse warming simulation conducted with the coupled OpenIFS-FESOM2 model (AWI-CM3) with ~9 km atmosphere resolution, 137 vertical levels and  4-15 km variable ocean resolution. Our analysis is based on a  set of 10-year time-slice simulations, which branched off from a lower-resolution (31 km) SSP585 transient scenario run with relatively high climate sensitivity. We will quantify the effect of atmosphere resolution and cloud granularity on cloud radiative feedbacks. We will further present results from the calculation of radiative kernels to determine the role of high cloud feedbacks in polar amplification. 

How to cite: Moon, J.-Y., Lee, S.-S., Timmermann, A., Streffing, J., Semmler, T., and Jung, T.: Cloud-feedbacks in global km-scale earth system model simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8603, https://doi.org/10.5194/egusphere-egu24-8603, 2024.

EGU24-9221 | ECS | Orals | CL4.5

Autocorrelation – A Simple Diagnostic for Tropical Precipitation in Global Kilometer-Scale Climate Models 

Dorian Spät, Aiko Voigt, Michela Biasutti, and David Schuhbauer

Tropical precipitation is the result of a complex interplay of processes across a wide range of atmospheric scales and is highly variable from place to place. A particularly interesting geographical pattern is obtained for the lag 1 autocorrelation of daily precipitation. Generally, this metric displays a relatively uniform distribution of positive values throughout the tropics. However, certain land regions, such as the Sahel, stand out due to exceptionally low autocorrelation values. These low values correspond to a dominance of high frequency precipitation events in the power spectrum.

In accordance with previous work, we show that CMIP6 climate models struggle to create a similar autocorrelation pattern. Global kilometer-scale models circumvent many of the shortcomings of the conventional coarse models, by resolving deep convection. We find that the two global kilometer-scale models developed as part of the nextGEMS project produce an autocorrelation pattern that is quite similar to the observations. These models also provide an opportunity to study the processes associated with the autocorrelation pattern.

We compare simulations with deep convection parameterization turned on and off to investigate how the parameterization scheme affects the autocorrelation pattern and the underlying power spectrum. Additionally, we perform a precipitation variance analysis based on filtering of convectively coupled equatorial waves to study the genesis of the autocorrelation pattern.

How to cite: Spät, D., Voigt, A., Biasutti, M., and Schuhbauer, D.: Autocorrelation – A Simple Diagnostic for Tropical Precipitation in Global Kilometer-Scale Climate Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9221, https://doi.org/10.5194/egusphere-egu24-9221, 2024.

EGU24-10275 | ECS | Posters on site | CL4.5

Precipitation impacting upper-ocean currents: an analysis using a km-scale Earth System model 

Hans Segura, Angel Peinado, Swantje Bastin, Marius Winkler, Rodomyra Schevchenko, Ian Dragaud, and Divya Patruri

In this study, we assess the impact of precipitation on the ocean current acceleration using an Earth System model resolving deep convection and ocean eddies using a horizontal grid spacing of 5 km. Punctual studies using observations show that precipitation events with intensities higher than 24 mm d^-1 could impact the upper-ocean dynamics. Basically, the increase in buoyance flux equals half buoyancy resulting in the absorption of shortwave radiation (200 W m-2) under clear sky conditions. Due to the spatial sparse of observational sites, there is still the question of whether this number holds only in specific locations. With a grid spacing of 5 km, the simulation shows that precipitation events in the tropical Atlantic with a mean intensity greater than 20 mm d-1 impact tremendously in the stratification due to salinity in the upper ocean with two consequences. First, the mixed layer depth shallows, even in cases with strong wind forcing. Second, the momentum trapped in this shallow layer accelerates the surface currents. This is also accompanied by an increase in the turbulent kinetic energy in the mixed layer depth. These results point to the fact that precipitation, in particular in the deep tropics, could impact the upper ocean dynamic.

How to cite: Segura, H., Peinado, A., Bastin, S., Winkler, M., Schevchenko, R., Dragaud, I., and Patruri, D.: Precipitation impacting upper-ocean currents: an analysis using a km-scale Earth System model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10275, https://doi.org/10.5194/egusphere-egu24-10275, 2024.

EGU24-10935 | ECS | Orals | CL4.5

AQUA: a novel quality assessment tool for km-scale simulations in the Destination Earth Climate Digital Twin - the core framework 

Matteo Nurisso, Jost von Hardenberg, Silvia Caprioli, Supriyo Ghosh, Nikolay Koldunov, Bruno P. Kinoshita, Natalia Nazarova, Paolo Ghinassi, and Paolo Davini

Destination Earth (DestinE) is a major initiative by the European Commission aiming to create a highly accurate global digital twin of Earth. The Climate Adaptation Digital Twin in DestinE is an ambitious project of several different climate simulations at the km-scale producing a large amount of heavy dataset, difficult to access and analyse with standard data processing  pipelines. Each project and each model produces data that may differ in format (NetCDF, GRIB, Zarr), structure and metadata, leading to the necessity of tweaks and complex pipelines in order to prepare data for analysis.

We thus introduce AQUA, an Application for Quality assessment and Uncertainty quAntification. AQUA is composed of a core engine facilitating data access, combined with a series of modular and independent diagnostics to be run continuously to monitor and evaluate climate simulations. In this contribution we present the core engine and its features. 

Though many available suites already exist to analyse data from global climate models, AQUA has been specifically developed to deal with large km-scale datasets, with the goal of unifying and simplifying climate data access for all users. AQUA responds to the need for users to have the focus on the development of their data analysis, while datasets are found, retrieved and homogenised by an external tool to which they can connect their pipeline. 

Developed in Python, leveraging the power of Dask and Xarray libraries, AQUA prioritises efficiency through lazy data access. Noteworthy is the utilisation of cdo for one-time weight computation, enhancing performances in regridding and averaging operations. A key strength lies in its ability to handle high-resolution, high-frequency data, loading into memory only when necessary. AQUA not only unifies and simplifies climate data access for users but also addresses the crucial need for responsive feedback to climate model developers.

How to cite: Nurisso, M., von Hardenberg, J., Caprioli, S., Ghosh, S., Koldunov, N., P. Kinoshita, B., Nazarova, N., Ghinassi, P., and Davini, P.: AQUA: a novel quality assessment tool for km-scale simulations in the Destination Earth Climate Digital Twin - the core framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10935, https://doi.org/10.5194/egusphere-egu24-10935, 2024.

EGU24-11230 | ECS | Orals | CL4.5

AQUA: a novel quality assessment tool for km-scale simulations in the Destination Earth Climate Digital Twin - the diagnostics suite 

Silvia Caprioli, Jost von Hardenberg, Paolo Ghinassi, Supriyo Ghosh, Lukas Kluft, Nikolay Koldunov, François Massonnet, Natalia Nazarova, Matteo Nurisso, Pablo Ortega, Susan Sayed, Tanvi Sharma, and Paolo Davini

Destination Earth (DestinE) is a major initiative by the European Commission aiming to create a highly accurate global digital twin of Earth. This model, supported by advanced high-performance computing and artificial intelligence, will monitor and simulate interactions between natural phenomena and human activities with unprecedented accuracy. Developed within the Climate Adaptation Digital Twin of the Destination Earth project, AQUA (Application for Quality assessment and Uncertainty quAntification) is a specialized model evaluation framework for running climate data diagnostics.

While existing diagnostic suites for global climate model data are already available, AQUA stands out by specifically addressing extensive kilometer-scale datasets, to simplify climate data access for all possible users. AQUA features two diagnostic families:

  • "state-of-the-art” diagnostics, which compare low-resolution data with observations to assess general model performance and to identify biases and drifts (performance indices, radiation budget, atmospheric global mean time series and biases, teleconnection indices, ocean circulation evaluation, tropical cyclones detection, tracking and zoom-in)
  • “frontier” diagnostics, which exploit new high-resolution (i.e., km-scale hourly) climate data to provide insight at climatological scales of physical/dynamical processes that could not be investigated before (sea surface height variability, tropical rainfall) 

Beyond offering a flexible and efficient framework for processing and analyzing large volumes of climate data, AQUA’s modular design offers the possibility of seamless integration of new diagnostic tools, with plans for further expansion in the future phases of the project.
In this contribution, we will introduce the current suite of AQUA diagnostics and outline its planned future developments.

How to cite: Caprioli, S., von Hardenberg, J., Ghinassi, P., Ghosh, S., Kluft, L., Koldunov, N., Massonnet, F., Nazarova, N., Nurisso, M., Ortega, P., Sayed, S., Sharma, T., and Davini, P.: AQUA: a novel quality assessment tool for km-scale simulations in the Destination Earth Climate Digital Twin - the diagnostics suite, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11230, https://doi.org/10.5194/egusphere-egu24-11230, 2024.

EGU24-11656 | ECS | Posters on site | CL4.5

Climate storylines using the spectral nudged simulations with IFS-FESOM 

Amal John, Sebastian Beyer, Marylou Athanase, Antonio Sánchez Benítez, Helge Goessling, and Thomas Jung

We are presenting our efforts to incorporate spectral nudging capabilities into the development and assessment of model-driven storyline scenarios using a km-scale coupled climate model. Working within the framework of the EU’s Destination Earth project, we are working towards this objective by employing the ocean sea-ice model FESOM coupled with the atmospheric model IFS.

We showcase our preliminary results from the nudged runs of IFS-FESOM for the present day which will eventually lead the way into the storyline scenarios where the same winds would be imposed in different climates. We also show a glimpse of how the nudged simulations for the present-day climate serve to assess model quality against observations based on relatively short simulations, incorporating field campaign data like MOSAiC. In the future, these capabilities could be used to produce “storylines” that help to address the question of how recent extreme events would unfold in preindustrial, +1.5K, +2K, +3K and +4K climates.

Ultimately, our novel storyline scenarios have the potential to illustrate the impact of climate change on extreme events in a way that is more tangible and relatable and nicely complements the probabilistic approach. Since they are based on recent extreme events and explore probable variations in diverse plausible climates, these storylines establish a more profound connection to users' experiences. When these scenarios are presented to users it can foster discussions on future activities and necessary adaptation measures.

How to cite: John, A., Beyer, S., Athanase, M., Sánchez Benítez, A., Goessling, H., and Jung, T.: Climate storylines using the spectral nudged simulations with IFS-FESOM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11656, https://doi.org/10.5194/egusphere-egu24-11656, 2024.

The amplitude of precipitation extremes across Europe is expected to increase through the 21st century under most climate change scenarios. Current CMIP-style global climate models broadly project increased flooding and drought extremes; however, they often rely on parametrization schemes or downscaling methods for inferring about potential future extreme events. These methods often introduce errors leading to high levels of uncertainty for policymakers and infrastructure planning. The need for accurate extreme event projections became further evident after the July 2021 floods and summer 2022 record-breaking heatwaves and droughts across Western Europe.

The ongoing H2020 Next Generation Earth Modelling Systems (nextGEMS) project aims to address these issues with the development of storm-resolving, fully-coupled, Earth-system models. Using the latest Cycle 3 runs from the Integrated Forecast System from ECMWF and ICON from MPI-M, we examine the dynamical representation of extreme precipitation events across Europe and compare it against a suite of observations (station and satellite based), reanalysis datasets, and CESM2 simulations. Focusing on tail-end extremes, the results focus on the realism of high precipitation extremes, value of upscaling to CMIP6 resolution, representation of precipitation drivers, and dry extremes (dry day percentages and consecutive dry days). Overall, both ICON and IFS perform reasonably well in representing high precipitation extremes although issues related to the ICON non-parameterized, deep convection causes overly frequent precipitation events.

How to cite: Wille, J. and Fischer, E.: Representation of extreme precipitation events in storm-resolving global climate models within the nextGEMS project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11797, https://doi.org/10.5194/egusphere-egu24-11797, 2024.

EGU24-12427 | ECS | Posters on site | CL4.5

Km-scale climate simulations with IFS-FESOM 

Sebastian Beyer, Dmitry Sidorenko, Rohit Ghosh, Amal John, Thomas Rackow, Jan Streffing, Suvarchal Kumar Cheedela, Bimochan Niraula, Nikolay Koldunov, and Thomas Jung

Within the EU’s Destination Earth (DestinE) initiative we are developing a digital climate twin with km-scale resolution. This enables us to resolve physical processes that, so far, have only been represented by approximations. This core model setup (called digital twin engine)  is able to run multidecadal simulations for historic periods as well as different future scenarios in unprecedented resolution which will be used by decision makers.

In phase one of DestinE, our goal is to run a control simulation (under 1950 pre industrial conditions), a historic simulation from 1990 to 2020 and finally, projection simulations from 2020 to 2040. The control run will be performed with a global atmospheric resolution of 9km, while the projection simulations use 4km. The ocean component uses the unstructured NG5 mesh, which means an approximate resolution of 5km.

In this work we present the latest iteration of the IFS-FESOM model, the Integrated Forecasting System coupled to the Finite volumE Sea Ice-Ocean Model FESOM2. We explain its components and recent improvements, including  the integration of ECMWF’s IO-server and post processing toolkit multio into the FESOM2 component and the introduction of a novel runoff mapper. Preliminary results from our kilometre-scale simulations are shown and compared to preindustrial conditions, with the primary objective to quantify effects of a ~1K warming world.

How to cite: Beyer, S., Sidorenko, D., Ghosh, R., John, A., Rackow, T., Streffing, J., Cheedela, S. K., Niraula, B., Koldunov, N., and Jung, T.: Km-scale climate simulations with IFS-FESOM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12427, https://doi.org/10.5194/egusphere-egu24-12427, 2024.

Global nonhydrostatic models that cover the globe with a kilometer (km)-scale mesh have been developed by various organizations worldwide and are expected to be next-generation models that can explicitly calculate deep convective clouds. However, it is known that convective upward motions are not sufficiently represented at the km-scale resolution, and the mesh size of O(100m) is required to obtain convergence of upward motions. To understand the limitation of global km-scale models, we investigate the representation of cloud, precipitation, and circulation with the resolution in the global simulations between km-scale to sub-km-scales.

We conduct the global atmospheric simulations by the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) for the mesh size of 3.5 km, 1.7 km, 870 m, 440 m, and 220 m using the Supercomputer "Fugaku."  The 3.5 km experiment started on August 1, 2016, the same day as DYAMOND-summer, and the next higher resolution was run using the lower resolution simulation results as initial conditions. We analyzed data on August 5, 2016. We conducted the global 220m simulation for 8 hours.

The resolution dependence of cloud, precipitation, and convection was investigated. Lower clouds decrease with increasing resolution. High cloud increased or decreased with respect to resolution depending on the turbulence scheme. The precipitation distribution and zonal mean humidity do not change significantly, but the precipitation intensity changes with resolution. For the grid spacing of less than km, it eliminates overconcentration of precipitation, and the rain area widens as the resolution becomes finer. The coarse-grained rainfall distribution is smoother in the sub-km scale model than in the km scale model. A finer scale convection core is reproduced in the sub-km scale model. Vertical wind speed at grid point scales increases with increasing resolution. However, when horizontally averaged over a few-degree grid, the vertical wind speed decreases, and the circulation becomes weaker with higher resolution. We found that the km-scale model may be creating large strong convection. Uncertainties resulting from the turbulence scheme also appear to be large in the km/sub-km models.

How to cite: Matsugishi, S., Ohno, T., and Satoh, M.: Differences in the cloud, precipitation, and convection representation between the global sub-km mesh simulation and km simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14676, https://doi.org/10.5194/egusphere-egu24-14676, 2024.

EGU24-15657 | ECS | Orals | CL4.5

Towards a global km-scale flood forecasting system 

Jasper Denissen, Gabriele Arduini, Ervin Zsoter, Cinzia Mazzetti, Christel Prudhomme, Shaun Harrigan, Gianpaolo Balsamo, Iria Ayan-Miguez, Peter Dueben, Irina Sandu, and Benoit Vanniere

River discharge has direct influence on the water-food-energy-environment nexus and can have devastating impacts during extreme events with rapid onsets such as floods. Floods often occur after extreme precipitation events, which are challenging to forecast accurately, both in time and space. Unresolved small-scale processes and features, including convection and orography, have a detrimental effect on precipitation and consequently hydrological forecast skill. This calls for a spatial resolution increase in Numerical Weather Prediction (NWP) models, including their land component.

The Destination Earth programme of the European Commission addresses this with globally coupled forecasts at spatial resolutions down to the km-scale with lead times of 5 days: the Digital Twin on Weather-Induced Extremes (EDT). These meteorological forecasts are used to force ECMWF’s Land Surface Modelling System (ECLand), the land component of the Integrated Forecasting System (IFS), to generate runoff. Subsequently, the river-routing scheme CaMa-Flood, effectively 1-way coupled to the IFS, is used to route runoff in rivers and to produce hydrological simulations. Essentially, CaMa-Flood will be part of the continuous component of the EDT, which in phase 2 of Destination Earth will provide daily high-resolution forecasts to monitor extreme events, such as floods, in real time. As river discharge acts as a natural integrator of the water cycle, CaMa-Flood can be used as a diagnostic tool to assess the hydrological response to increases in spatial resolution of the forcing and the river-routing network.

In this study, two data products are derived: i) long-term hydrological simulations forced by atmospheric analysis data (e.g. ERA5 or ECMWF operational analysis) and ii) hydrological forecasts (daily forecasts in June - July 2021 and January - February 2022 as well as selected flood cases). To assess their quality, these data are validated with point-observed river-discharge time series. Analysis shows that the long-term hydrological simulations benefit from spatial resolution increases in the meteorological forcing and to a lesser extent from spatial resolution increases in the river-routing network. This is evidenced by higher Kling-Gupta Efficiency (KGE), higher correlations and lower biases across 876 river stations in Europe. Further, hydrological forecasts also benefit from higher spatial resolution meteorological forcing, evidenced both by higher correlations of the continuous summer/winter forecasts against river discharge observations from 798 river stations across Europe and by more pronounced flood peak magnitude for selected flood cases. These results highlight the added value of high resolution for hydrological forecast accuracy.

How to cite: Denissen, J., Arduini, G., Zsoter, E., Mazzetti, C., Prudhomme, C., Harrigan, S., Balsamo, G., Ayan-Miguez, I., Dueben, P., Sandu, I., and Vanniere, B.: Towards a global km-scale flood forecasting system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15657, https://doi.org/10.5194/egusphere-egu24-15657, 2024.

Cloud microphysics are a prime example of processes that remain unresolved in atmospheric modelling with storm-resolving resolution. In this study, we explore how uncertainties in the representation of microphysical processes affect the tropical energy budget in a global storm-resolving model (SRM). We use the global SRM ICON with a one-moment or a two-moment microphysics schemes and do several sensitivity runs, where we vary one parameter of the applied microphysics scheme in its range of uncertainty. We find that the two microphysics schemes have distinct signatures, e.g., in how condensate is distributed among the different hydrometeor categories or in the intensity distribution of precipitation, but their tropical mean cloud fraction and total condensate profiles are rather robust. Precipitation efficiency sets the amount of condensate in the atmosphere and thereby links microphysical processes to the radiative properties of the atmosphere. Uncertainties in the representation of microphysical processes cause substantial spread in the top-of-the-atmosphere (TOA) energy balance. In agreement with the robustness of the cloud fraction, changes in the radiative balance at TOA are dominated by changes in the radiative properties of cloudy points. A shift towards higher cloud-ice concentrations in simulations with the two-moment microphysics scheme leads to more reflected shortwave radiation that is not fully compensated by less outgoing longwave radiation and results in a slight cooling of the atmospheric column. Overall, microphysical sensitivities at storm-resolving resolution are substantial and resemble part of the inter-model spread of a multi-model ensemble.

How to cite: Naumann, A. K., Esch, M., and Stevens, B.: How the representation of microphysical processes affects the tropical energy budget in a global storm-resolving model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16801, https://doi.org/10.5194/egusphere-egu24-16801, 2024.

EGU24-17906 | ECS | Orals | CL4.5

Multifractal analysis for evaluating the representation of clouds in global km-scale models 

Lilli Freischem, Philipp Weiss, Hannah Christensen, and Philip Stier

Clouds are one of the largest sources of uncertainty in climate predictions. Emerging next-generation km-scale climate models need to simulate clouds and precipitation accurately to reliably predict future climates. To isolate issues in their representation of clouds, and thereby facilitate their improvement, km-scale models need to be thoroughly evaluated via comparisons with observations.

Traditionally, climate models are evaluated using spatio-temporally averaged observations. However, aggregated evaluation loses crucial information about underlying physical processes, such as convective updrafts, and the resulting cloud macrophysical structures. We postulate that a novel spatio-temporal evaluation strategy using satellite observations provides direct constraints on physical processes.

Here, we introduce multifractal analysis as a method for evaluating km-scale simulations. We apply it to top-of-atmosphere outgoing longwave radiation (OLR) fields to investigate structural differences between observed and simulated clouds in the tropics. For this purpose, we compute structure functions from OLR fields to which we fit scaling exponents. We then parameterise the scaling exponents to compute scaling parameters. The parameters compactly characterise OLR variability and can be compared across simulations and observations. We use this method to evaluate the ICON-Sapphire and IFS-FESOM simulations run for cycle 3 of the nextGEMS project via comparison with data from the geostationary satellite GOES-16.

We find that clouds in both models exhibit multifractal scaling from 50 to 1000km. However, the scaling parameters are significantly different between ICON and IFS, and neither match observations. In the ICON model, multifractal scaling exponents are lower than in observations whereas in IFS, they are larger. The observed differences indicate how the modelling approaches in ICON and IFS impact the organisation of clouds. More specifically, the deep convection scheme in ICON is switched off completely whereas it is still active in IFS, which could explain the difference in scaling behaviour we observed.

Our results show that spatio-temporal analysis is a promising new way to constrain global km-scale models. It can provide key insights into model performance and shed light on issues in the representation of clouds.

How to cite: Freischem, L., Weiss, P., Christensen, H., and Stier, P.: Multifractal analysis for evaluating the representation of clouds in global km-scale models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17906, https://doi.org/10.5194/egusphere-egu24-17906, 2024.

In recent years, great efforts have been made to reduce the horizontal grid spacing of atmospheric models to a few kilometers to build so-called Global Storm-Resolving Models (GSRMs). However, the vertical grid spacings used in these models are generally of the same order of magnitude as those used in classical climate models with horizontal grid spacings of a few hundred kilometers. From previous sensitivity experiments with a variety of model types, from direct numerical simulations to these classical climate models, it is known that especially the simulation of clouds can strongly depend on the vertical model resolution. To test the importance of the vertical grid spacing in GSRMs we have performed simulations with the ICON atmospheric model at 5 km horizontal grid spacing and with between 55 and 540 vertical layers, corresponding to maximum tropospheric vertical grid spacings between 800 and 50 m.  

Here we present results of these simulations. They results show that for most of the variables considered, halving the vertical grid spacing by half has a less pronounced impact than halving the horizontal grid spacing, but the effect is not negligible. For example, for each halving of the vertical grid spacing, coupled with necessary reductions in the time step length, cloud liquid water increases globally by approximately 7%, while it decreases by roughly 16% when halving the horizontal grid spacing. Both the grid spacing and the time step contribute to these effects. Comparison of selected climate variables with observations shows that model biases are only in some cases reduced by higher vertical resolution, because of the dominance of model biases with other origins.

How to cite: Schmidt, H.: Exploring the impact of the vertical grid spacing for the climate simulated in a global storm-resolving model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18060, https://doi.org/10.5194/egusphere-egu24-18060, 2024.

EGU24-18483 | Posters on site | CL4.5

Eulerian and Lagrangian Perspectives on Mesoscale Air-Sea Interactions 

Dian Putrasahan and Jin-Song von Storch
Mesoscale ocean eddies can be likened to weather events of the sea, influencing a multitude of coupled air-sea processes that help in regulating heat and carbon uptake and consequently the climate. With the advancements in high-performance computing, we can now employ multi-decadal kilometre-scale coupled global climate models (GCMs) that effectively captures the intricacies of mesoscale ocean-atmosphere interactions and shed light on their implications at larger scales. While low resolution CMIP-type GCMs show a dominance of atmospheric-forced coupled variability, e.g. faster winds over ocean surface can enhance turbulent heat flux and thus cool sea surface temperatures (SSTs), satellite observations and eddy-resolving coupled models show a prevalence of mesoscale ocean-forced coupled variability over eddy-rich regions like SST front areas. Two ocean mesoscale dynamical processes can promote such ocean-forced coupled variability, namely through thermal feedback and current feedback. Consider the thermal feedback as an example; the destabilisation of the atmosphere above warm mesoscale anomalies amplifies the downward transfer of momentum from higher-altitude winds to the surface, known as the vertical or downward mixing mechanism. This, in turn, leads to enhanced surface winds and increased turbulent heat flux over warm SST anomalies. We employ a coupled 5km-ocean 10km-atmosphere ICON model to assess the global distribution of mesoscale air-sea coupling associated with these feedbacks and their implications on wind work and eddy-induced Ekman upwelling. Additionally, we show examples of such mesoscale coupling from a Lagrangian perspective through composites of tracked eddies, their impact on ocean upwelling/downwelling and their imprint on the overlying atmosphere beyond the surface like precipitation.

How to cite: Putrasahan, D. and von Storch, J.-S.: Eulerian and Lagrangian Perspectives on Mesoscale Air-Sea Interactions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18483, https://doi.org/10.5194/egusphere-egu24-18483, 2024.

EGU24-18761 | Posters on site | CL4.5

Modelling of the Hunga Tonga eruption for testing the GPU port of ICON 

Luis Kornblueh and the Port ICON to Lumi

Porting weather and climate models such as ICON to GPU-based computer production systems requires serious testing of the code adapted to the
additional hardware and its software stack. The high resolution of storm resolving models poses problems for porting ICON and very short simulations facilitate this task.

The 2022 eruption of the Hunga Tonga–Hunga Haʻapai submarine volcano had a very strong water vapour signal, which is modelled by adjusting the model initial conditions to include a cylindrical water vapour plume: a very simple setup to implement, but one that reflects the strong signal in the model results. This plume is visible in the model for years. For the test case we focus on the first time steps. These support the detection of technical errors in the porting of the model code in very short simulations at the final model resolution of 5 km.

We present the scientific use case, the model configuration and some results from test simulations on Lumi.

How to cite: Kornblueh, L. and the Port ICON to Lumi: Modelling of the Hunga Tonga eruption for testing the GPU port of ICON, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18761, https://doi.org/10.5194/egusphere-egu24-18761, 2024.

EGU24-18964 | ECS | Posters on site | CL4.5

On the detection and tracking of mesoscale ocean eddies: Parameter sensitivity 

Stella Bērziņa, Nicolas Gruber, and Matthias Münnich

The characteristics of coherent mesoscale eddies are an important point of evaluation for high-resolution ocean and coupled climate models. Mesoscale eddies are rotating features in the ocean on horizontal scales from 10 to 100 km that transport physical, chemical and biological properties of the ocean water. There are many possible ways to identify and track eddies (sea surface height anomalies, sea surface temperature anomalies, vorticity, etc.) and even within one method parameters can be adjusted to lead to different eddy identification results, for example, the allowed shape error of eddies.  

Here we explore systematically the sensitivity of the identification and tracking results to choices made with regard to data, allowed eddy size and shape error and the use of different high-pass filters. Additionally, eddy identification and tracking are done on a regular latitude-longitude grid rather than the native model grid, therefore, the impact of the chosen grid size is assessed.

To this end, we use “py-eddy-tracker” (Mason et al. 2014) a commonly used open-source geometry-based approach. The algorithm uses sea level anomaly data and several adjustable parameters to identify eddies. It then joins the identified eddies to form tracks by using the ellipsoid method described in Chelton et al. 2011, where the two closest lying eddies in subsequent time steps are connected if they occur within a restricted search region.

We apply this identification and tracking algorithm to high frequency output from different high-resolution coupled climate models run as part of the EERIE project and compare the results of eddy characteristics to observations. This study will help to make more informed and study-specific choices when setting threshold values in eddy identification algorithms for model assessment or creating eddy observational data set from satellite altimetry data.

How to cite: Bērziņa, S., Gruber, N., and Münnich, M.: On the detection and tracking of mesoscale ocean eddies: Parameter sensitivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18964, https://doi.org/10.5194/egusphere-egu24-18964, 2024.

EGU24-19072 | ECS | Orals | CL4.5

Surface irradiance variability over land in storm-resolving models. 

Menno Veerman and Chiel van Heerwaarden

With increasing horizontal resolution in global models, we may expect an increasingly more realistic representation of cloud development over land as both large-scale circulations and local surface heterogeneities, such as orography and land use type, are better resolved. As clouds are a dominant contributor to inter- and intra-diurnal variations in both solar and thermal surface irradiance, the spatiotemporal irradiance variability should then be better represented than in conventional climate models. Here, we use the 5-year coupled atmosphere-ocean global simulations performed in Cycle 3 of the nextGEMS project to evaluate the surface irradiance variability over land. These 5-year simulations were performed at different resolution, from 4.4 to 28 km, and with two different global models, the Integrated Forecasting System (IFS) and the Icosahedral Nonhydrostatic model (ICON), allowing us to separate the impacts of horizontal resolution and of implementation choices concerning model physics. We select a couple of representative locations with varying climate and land surface characteristics where high-quality irradiance observations from the Baseline Surface Radiation Network (BSRN) are available. While first results show some benefits of increased horizontal resolution, higher resolutions simulations do not consistently produce more accurate surface irradiances than simulations at lower resolution. Furthermore, differences between the IFS and ICON models are often larger than differences between the IFS simulations at varying resolutions. These results suggest that if realistic surface irradiance predictions are concerned, e.g. for solar energy applications, the road to model improvement by increasing horizontal resolution is not straightforward. 

How to cite: Veerman, M. and van Heerwaarden, C.: Surface irradiance variability over land in storm-resolving models., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19072, https://doi.org/10.5194/egusphere-egu24-19072, 2024.

EGU24-19735 | ECS | Posters on site | CL4.5

Network of extremes in ocean eddy-resolving climate models 

Emma Ferri, Nicolas Gruber, Matthias Münnich, and Dian Putrasahan

Marine extreme events, such as marine heatwaves, have a disproportional impact on marine organisms and ecosystems, shaping many of their characteristics. Even though such extremes have become the focus of much research in the last few years, our understanding of the processes that give rise to extreme conditions is still relatively poor. Mesoscale processes have been shown to structure and shape extremes, but also not much is known about their role. Here we use graph theory to detect the correlation between extreme marine events and distant occurrences of atmospheric extremes in the context of mesoscale variability. The data stem from a set of mesoscale resolution model simulation results obtained from the European Eddy RIch Earth System Models (EERIE) project. Common statistical tests such as the Pearson correlation coefficient and the Granger causality will be used to build the graph object. This will permit us to build a network of different oceanographic and atmospheric variables in an attempt to detect teleconnections, such as, for example, the impact of El Niño, on the onset, persistence, and demise of extremes. Our initial networks correlate various variables, such as precipitation and sea surface temperature (SST), eddy kinetic energy and SST, and global SST variations.

How to cite: Ferri, E., Gruber, N., Münnich, M., and Putrasahan, D.: Network of extremes in ocean eddy-resolving climate models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19735, https://doi.org/10.5194/egusphere-egu24-19735, 2024.

EGU24-21956 | ECS | Posters on site | CL4.5

Storm Tracks and Jet Streams in ICON: Unravelling Climate Change Responses through Aquaplanet Horizontal Grid Spacing Sensitivity Experiments 

Angel Peinado Bravo, Tiffany Shaw, Daniel Klocke, and Bjorn Stevens

General Circulation Models (GCMs) are widely used to understand our climate and to simulate and predict the effects of global warming, revealing the dynamical convergence of storm tracks and jet streams at horizontal grid spacing of 50 km (e.g., Lu et al. 2015). Nevertheless, they have shown persistent biases in the large-scale features of the general circulation and basic climate statistics, which are attributed mainly to the parameterization, specifically, convection parameterization. To address this, Global storm-resolving models (GSRMs) provide an alternative approach to parameterization by explicitly resolving convection and its interaction with other processes,  through the refinement of the horizontal grid, thus, offering new insights into the climate system. In a prior study, we showed the physical convergence of the tropical and general circulation structure at horizontal grid spacing of 2.5 km using aquaplanets. However, questions linger: Does the response under climate change of the storm tracks and jet streams converge at similar horizontal grid spacing, and what mechanism controls this convergence?

 

We will present the effect of increasing horizontal grid spacing on the convergence of the storm tracks and jet stream location and intensity using the global storm-resolving model ICON. Control runs and idealised climate change experiments (increasing sea-surface temperature by 4 Kelvin) were conducted at horizontal grid spacing from 160 km to 2.5 km using an aqua-planet configuration. We adopt an aqua-planet configuration to focus on atmospheric phenomena, specifically convection and cloud feedback, meanwhile reducing the effect of complex interaction with land, topography, sea ice, and seasons. We will discuss the convergence rate of the eddy driven jet, subtropical jet, storm track, and large-scale circulation and their response to climate warming, characterised by the location, width, and intensity. 

How to cite: Peinado Bravo, A., Shaw, T., Klocke, D., and Stevens, B.: Storm Tracks and Jet Streams in ICON: Unravelling Climate Change Responses through Aquaplanet Horizontal Grid Spacing Sensitivity Experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21956, https://doi.org/10.5194/egusphere-egu24-21956, 2024.

The warming of the Arctic region is a significant global concern, and its repercussions extend far beyond polar and mid-latitudes. Rapid changes in sea ice have the potential to significantly impact atmospheric circulation, leading to variations in precipitation patterns across India at different spatial and temporal scales. The present study attempts to characterize the influence of Arctic Sea ice on the monthly precipitation over meteorologically homogeneous regions in India. To consider the regional variability of sea ice, the Arctic region is divided into the Pacific Arctic sector (PAS) and the Atlantic Arctic sector (AAS). The monthly precipitation in India and Arctic Sea ice concentration (SIC) at a monthly scale were decomposed using Maximum overlapping discrete wavelet transform (MODWT). The correlation between precipitation and SIC was analyzed to understand the multiscale association between SIC in the Arctic and precipitation in India. Our results indicate that the Pacific and the Atlantic Arctic sectors exert distinct influences on India. Alterations in sea ice, especially in the Atlantic Arctic sector, profoundly impact Indian precipitation. Notably, the Pacific Arctic sector does not exhibit any influence on the Northeast region across various time scales. The results enhance our nuanced comprehension of the intricate interplays between the climates of India and the Arctic, playing a pivotal role in advancing our ability to predict global climate.

How to cite: kulkarni, S. and Agarwal, A.: Deciphering the Multiscale Association between Indian Precipitation-Arctic Teleconnections Using Wavelet Analysis. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-522, https://doi.org/10.5194/egusphere-egu24-522, 2024.

EGU24-1280 | ECS | Orals | CL4.6

Prediction of the Interannual Rainfall Variability in the Sahel: Insights from Atmospheric Circulation Patterns  

Manuel Rauch, Jan Bliefernicht, and Harald Kunstmann

The Sahel region is characterized by significant rainfall variability and has experienced hydrological changes, including a major drought from 1968 to the 1990s, followed by a subsequent period of rainfall recovery since the 1990s. Addressing this variability, this study introduces a statistical approach for predicting interannual rainfall anomalies within the region. Initially, k-means is used to classify daily atmospheric circulation patterns over West Africa, based on key variables like the V-component of wind at 700 hPa and wind speed at 200 hPa. The two high-altitude wind fields are crucial for understanding the monsoon dynamics due to their direct linkage with African Easterly Waves and the Tropical Easterly Jet. Subsequently, the annual occurrence frequencies of the atmospheric circulation patterns, along with the annual rainfall conditions in the Sahel region, are used as inputs for a multi-class logistic regression model. This model is designed to predict dry, normal, or wet years relative to the climatology. Moreover, the research presents the spatial composites of the atmospheric circulation patterns, along with a detailed explanation of the logistic regression model, an analysis of seasonal pattern occurrences, and their meteorological interpretations. The model has shown success in predicting annual rainfall variability, achieving an average proportion correct of 0.77. This level of accuracy establishes the model as a reliable tool for predicting annual rainfall amounts in the Sahel zone, offering significant insights into the climate of the region. 

How to cite: Rauch, M., Bliefernicht, J., and Kunstmann, H.: Prediction of the Interannual Rainfall Variability in the Sahel: Insights from Atmospheric Circulation Patterns , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1280, https://doi.org/10.5194/egusphere-egu24-1280, 2024.

EGU24-2006 | ECS | Posters on site | CL4.6

Analysis of correlations between the South Atlantic Convergence Zone and Climate Indices Derived from the Pacific and Atlantic Oceans for Evaluating Teleconnections 

Louise da Fonseca Aguiar, Vitor Luiz Galves, Marcio Cataldi, David Marcolino Nielsen, Lívia Sancho, and Elisa Passos

The South Atlantic Convergence Zone (SACZ) is one of the most important phenomena that influences the precipitation patterns in Brazil’s Southeast and Midwest regions during the spring and summer. These regions play a major role for the country’s economy, particularly in terms of agriculture and industrial production. It is estimated that the SACZ is responsible for approximately 25% of the total volume of rain in Southeast Brazil from October to April. The conditional probability of a natural disaster occurring when the SACZ is present in the region is around 24%, while, in the case of a disaster occurring in the Southeast, the conditional probability of observing the presence of SACZ is 48%. This work provides an initial understanding of how different teleconnection patterns can influence the configuration, position, and intensity of the SACZ. The goal is to investigate potential correlations between the SACZ index, the El Niño Southern Oscillation (ENSO) indexes, the Atlantic Sea surface temperatures (SST) between Central America and Africa, the Brazil-Malvinas Confluence (BMC) and the Antarctic Oscillation (AAO). For the SACZ indexes, the monthly data was derived by summing the values for each month. This process utilized data spanning from 1980 to 2010 to establish the monthly climatology. The monthly indexes and anomalies were compared with the monthly climatology values from January 1999 to December 2022. For daily indexes of BMC, Niño1+2, Niño 3, Niño 3.4, Niño 4, Atl_N, Atl_NL, Atl_C and Atl_CL sea surface temperature (SST) anomalies were referenced against a climatology spanning from 1971 to 2000. In these cases, monthly data was obtained through the average of the daily indexes. Finally, AAO indexes were already obtained monthly. In this case, the time series were normalized using the standard deviation of the monthly index, based on the 1979-2000 period. Three Pearson correlations were calculated monthly for the period from 1999 to 2022. These correlations were evaluated for the average from October to March, October to December, and from January to March. The preliminary results showed that colder anomalies of the Equatorial Pacific (La Niña), the North Equatorial Atlantic, and the CBM, in conjunction with a positive phase of the AAO and warmer waters of the Central Equatorial Atlantic, are associated with the occurrence and configuration of the SACZ (and vice versa). This signal is most pronounced in the period from October to December and during the October to March timeframe, while it weakens in the months from January to March.

How to cite: da Fonseca Aguiar, L., Galves, V. L., Cataldi, M., Marcolino Nielsen, D., Sancho, L., and Passos, E.: Analysis of correlations between the South Atlantic Convergence Zone and Climate Indices Derived from the Pacific and Atlantic Oceans for Evaluating Teleconnections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2006, https://doi.org/10.5194/egusphere-egu24-2006, 2024.

EGU24-3098 | Orals | CL4.6 | Highlight

Remote mechanisms for shifting the tropical Pacific warming pattern 

Sarah M. Kang, Masahiro Watanabe, Matthew Collins, Yen-Ting Hwang, Shayne McGregor, and Malte F. Stuecker

Changes in the sea surface temperature (SST) pattern in the tropical Pacific modulate radiative feedbacks to greenhouse gas forcing, the pace of global warming, and regional climate impacts.  Therefore, elucidating the drivers of the pattern is critically important for reducing uncertainties in future projections.  However, the attribution of observed changes over recent decades, an enhancement of the zonal SST contrast coupled with a strengthening of the Walker circulation, has not been successful.  Here, we review existing mechanisms of the forced response, categorized as either an energy perspective that adopts global/hemispheric energy budget constraints or a dynamical perspective that examines the tropical atmosphere-ocean coupled processes. We then collectively discuss the relative contributions to the past and future SST pattern changes to propose a narrative that reconciles them. Despite uncertainties, the balance of evidence suggests that the mechanisms leading to strengthening the zonal SST contrast have been efficient in the past and those leading to a weakening were less efficient but will become dominant in a future climate. We particularly focus on the role of Southern Ocean SST changes in shifting the tropical Pacific warming pattern. Finally, we present opportunities to resolve the model-observation discrepancy regarding the recent trend.

How to cite: Kang, S. M., Watanabe, M., Collins, M., Hwang, Y.-T., McGregor, S., and Stuecker, M. F.: Remote mechanisms for shifting the tropical Pacific warming pattern, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3098, https://doi.org/10.5194/egusphere-egu24-3098, 2024.

EGU24-3261 | ECS | Posters on site | CL4.6

Decadal variability of extreme precipitation in northern of Oman 

Salma Al Zadjali, Peter Sammonds, Simon Day, and Ian Phillips

Climate variability and climate change are major drivers for extreme precipitation patterns on a global scale. However, under the application of weather engineering techniques such as cloud seeding, the climate variability signals must be analysed before concluding the benefits of these seeding operations in arid and semi-arid regions. The primary aim of this study is to gain insights on the drivers that contribute to extreme precipitation variability in northern Oman. In this research, the monthly high-resolution precipitation data from Climate Research Unit (CRU) Time Series (TS) version 4.05 dataset for northern Oman from 1950-2019 are analysed. The quantile perturbation method and the non-parametric Monte Carlo simulations are employed to compute high decadal and seasonal anomalies, and their statistical significance respectively. The teleconnections of Optimum Interpolation Sea Surface Temperature (OISST), Mean Sea Level Pressure (MSLP) and decadal variability patterns represented by the North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Pacific Decadal Oscillation (PDO), and El Niño-Southern Oscillation (ENSO) with extreme precipitation anomalies are conducted. The severity and spatial and temporal variability of precipitation and deep convection are investigated using outgoing longwave radiation (OLR) as a proxy for extreme precipitation. These findings address the role of internal forcing on precipitation variability in the Al Hajar Mountains, an area characterised by natural convective precipitation. The extreme precipitation variability analysis is conducted to understand better whether cloud seeding operations induce the occurrence of extreme precipitation in the Al Hajar Mountains.

How to cite: Al Zadjali, S., Sammonds, P., Day, S., and Phillips, I.: Decadal variability of extreme precipitation in northern of Oman, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3261, https://doi.org/10.5194/egusphere-egu24-3261, 2024.

The relationships between the El Niño-Southern Oscillation (ENSO), Asian-Pacific region summer precipitation and its corresponding atmospheric circulations exhibit interdecadal changes. From the early 1990s to the early 2000s, these relationships were significant. Therefore, we divided this time frame into three periods for analysis: 1979–1991 (P1), 1992–2005 (P2), and 2006–2019 (P3). The possible mechanism underlying these relationships is as follows: the southern Indian Ocean sea surface temperature (SST) over the east of Madagascar exhibits interdecadal variation. During P2, the SST was relatively cold, which induced an anomalously high Mascarene High (MH). The strengthened MH enhanced the Somali jet and Indian monsoon westerlies, which intensified the strong center of the Indian Ocean Walker circulation. Therefore, owing to the strength and location changes of the Indian Walker circulation and the Walker circulation, the connection between the ENSO and the western Pacific vertical motions strengthened, resulting in the close relationship of the ENSO with the atmospheric circulation over the Asian-Pacific region. Hence, ENSO can influence a north-south tripole pattern of precipitation over the Asian-Pacific monsoon region through local vertical activities and meridional Hadley circulation over western Pacific. Numerical experiments using an atmospheric general circulation model, with prescribed three times southern Indian Ocean SST anomalies of 1995–2005 relative to 1979–2019, also lend support to the southern Indian Ocean SST’s contribution to modulating the relationship between ENSO and summer precipitation over the Asian-Pacific monsoon region.

How to cite: Gao, Y.: Effect of interdecadal variation in southern Indian Ocean SST on the relationship between ENSO and summer precipitation in the Asian-Pacific monsoon region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6947, https://doi.org/10.5194/egusphere-egu24-6947, 2024.

EGU24-7293 | Posters on site | CL4.6

 Role of Korea Strait Volume Transport in the East/Japan Sea Deep Water Circulation under the Mid-Holocene Climate Equilibrium 

Eun Young Lee, Dong Eun Lee, Hye-Ji Kim, Young-gyu Park, Jang Jun Bahk, and Haedo Baek

The East Sea, having its own meridional circulation system like that of the Atlantic Ocean but with a shorter periodicity, is known to be sensitive to climate change, with important implications for future changes in the ocean environment.

The meridional circulation system of the East Sea is known to be maintained, by 1) heat and salt supply from the Tsushima Warm currents, 2) ocean-atmosphere heat and freshwater exchange in the northern part of the East Sea, and 3) sea ice formation in the Tatar Strait, but it is not yet known which of these factors will most dominate the changes and variability of the East Sea circulation under different climate equilibria, and there has been no quantitative study of the path and strength of the deep circulation in the East Sea induced by each factor.

In this study, we explore the distinct characteristics of the East Sea’s deep circulation in the past compared to the present, to understand better the future climate change in the region. Through the simulations using the ocean regional model system (ROMS) with results from PMIP4/CMIP6 experiments as surface forcing, we investigate the factors influencing the response of deep circulation to the past by analyzing both the present and the past climate conditions. Specifically, we conducted quantitative analyses to investigate how the path and intensity of deep circulation in the East Sea vary due to the different conditions. This was achieved through model experiments (Surface bar, VT bar) in which we altered both the volume transport through the Korea Strait and the air-sea interaction through the surface.

The results reveal that the deep circulation of the East Sea was approximately 5% weaker 6000 years ago compared to the present. During this period, the seasonal temperature difference was larger than in the present climate, and the volume transport through the Korea Strait was higher. The weakening of the deep circulation is attributed to the higher temperatures in the southern part of the East Sea causing ocean stratification 6000 years ago. The heat transported by the Tsushima Warm currents as it entered the East Sea further intensified the stratification in the southern part, leading to a weakened deep circulation. In the northern part of the East Sea, increased density resulted from the increased salt delivered by the Eastern Korea Warm Current, strengthening the northern circulation along with the brine rejection. However, this effect is overwhelmed by surface warming through air-sea interaction in the East Sea, resulting in the net weakening of the meridional circulation. Also, the processes and characteristics of the linkages between sea ice formation, the variability of the volume transport and atmospheric conditions are analyzed. Finally, this study presents insights into the sensitivity of the East Sea meridional circulation system to future climate change with less uncertainty helped by better understanding paleoclimate in the region.

How to cite: Lee, E. Y., Lee, D. E., Kim, H.-J., Park, Y., Bahk, J. J., and Baek, H.:  Role of Korea Strait Volume Transport in the East/Japan Sea Deep Water Circulation under the Mid-Holocene Climate Equilibrium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7293, https://doi.org/10.5194/egusphere-egu24-7293, 2024.

EGU24-8579 | Orals | CL4.6

Investigation of Future Climate Change Over the British Isles using Weather Patterns 

James Pope, Kate Brown, Fai Fung, Helen Hanlon, Robert Neal, Erika Palin, and Anne Reid

For those involved in planning for regional and local scale changes in future climate, there is a requirement for climate information to be available in a context more usually associated with meteorological timescales. Here we combine a tool used in numerical weather prediction, the 30 weather patterns produced by the Met Office, which are already applied operationally to numerical weather prediction models, to assess changes in the UK Climate Projections (UKCP) Global ensemble. Through assessing projected changes in the frequency of the weather patterns at the end of the 21st Century, we determine that future changes in large-scale circulation tend towards an increase in winter of weather patterns associated with cyclonic and westerly wind conditions at the expense of more anticyclonic, settled/blocked weather patterns. In summer, the results indicate a shift towards an increase in dry settled weather types with a corresponding reduction in the wet and windy weather types. Climatologically this suggests a shift towards warmer, wetter winters and warmer, drier summers; which is consistent with the headline findings from the UK Climate Projections 2018. This paper represents the first evaluation of weather patterns analysis within UKCP Global. It provides a detailed assessment of the changes in these weather patterns through the 21st Century and how uncertainty in emissions, structural and perturbed parameters affects these results. We show that the use of these weather patterns in tandem with the UKCP projections is useful for future work investigating changes in a range of weather-related climate features such as extreme precipitation, or impacts on the energy sector. 

How to cite: Pope, J., Brown, K., Fung, F., Hanlon, H., Neal, R., Palin, E., and Reid, A.: Investigation of Future Climate Change Over the British Isles using Weather Patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8579, https://doi.org/10.5194/egusphere-egu24-8579, 2024.

An intermediate-complexity moist general circulation model is used to disentangle changes in the large-scale zonally asymmetric circulation due to rising GHGs. We run multiple idealized experiments in order to isolate, and subsequently synthesize, the physical processes driving these changes. In particular, we examine stationary wave changes forced by land–sea contrast, horizontal heat fluxes in the ocean, and orography, in response to a quadrupling of CO2 concentrations. A particular focus is on the anomalous ridge in the Mediterranean region associated with the decline in precipitation in this heavily populated region. 

 Our results suggest a combination of two mechanisms is responsible for future Mediterranean drying. The first is a global phenomena, a lengthening of intermediate-scale stationary waves due to strengthening of subtropical upper-tropospheric zonal mean zonal winds, shown previously to account for hydroclimatic changes in the western US. We find this mechanism to be dominated by change in waves forced by ocean horizontal heat fluxes. The second mechanism is a regional one, a strengthening of large-scale stationary wave modes over Europe and the north Atlantic, dominated by changes in stationary waves forced by land-sea contrast. This second mechanism is strongly tied to an altered temperature gradient between the North Atlantic and Europe, in response to rising GHGs. Our work demonstrates how large-scale upper-tropospheric circulation changes are directly tied to regional hydroclimate.

How to cite: Keller, B. and Garfinkel, C.: Disentangling projected stationary wave changes: implications for future drying of the Mediterranean region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9099, https://doi.org/10.5194/egusphere-egu24-9099, 2024.

Different North Atlantic winter climate regimes force different circulation patterns in the Baltic Sea. Furthermore, as the atmospheric circulation, to a large extent, controls patterns of water circulation and biophysical aspects relevant for biological production, such as the vertical distribution of temperature, salinity and oxygen, alterations in weather regimes may severely impact the trophic structure and functioning of marine food webs (Hinrichsen et al. 2007). To understand the processes linking changes in the marine environment and climate variability of the Baltic Sea, it is essential to investigate all components of the climate system which of course include also the large-scale atmospheric circulation variability. Here we focus on the link between changes/shifts in the large-scale atmospheric conditions and their impact on the regional scale variability over the Baltic Sea area for the period 1950-2022. This work is mostly an extension of previous studies which focused on the response of the Baltic Sea circulation to climate variability for the period 1958-2008 (Lehmann et al. 2011, Lehmann et al. 2014). Now extended time series ECMWF ERA 5 reanalysis for 7 decades are available, highlighting recent changes in atmospheric conditions over the Baltic Sea area. The main focus of this work is to identify predominant large scale atmospheric circulation patterns (North Atlantic winter climate regimes) on a monthly/seasonal time scale controlling the development of regional atmospheric weather types over the Baltic Sea area, which in turn can be associated with different Baltic Sea circulation patterns and water mass exchange with the North Sea.

How to cite: Lehmann, A. and Post, P.: Changing impact of large-scale atmospheric circulation variability on the water mass exchange and circulation of the Baltic Sea for the period 1950-2022, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9354, https://doi.org/10.5194/egusphere-egu24-9354, 2024.

Classification of atmospheric circulation patterns has been a major powerful tool in synoptic climatology for a long time. Recently, its generalization has been introduced, which consists in developing geographically sliding classifications, i.e., independent classifications centred over individual gridpoints of a regular grid.

We employ such a tool in an attempt to explain the asymmetry of day-to-day temperature differences (DTDs). DTD is defined simply as a difference of daily temperature between two consecutive days. DTD in Europe is asymmetric: its skewness is negative over most of Europe in summer, while in winter, there is a tendency for a positive skewness to occur in the north and for negative skewness to occur in the south and over the British Isles.

We employ the ERA5 reanalysis as a major data source of both circulation and temperature data and the ECA&D station database for verification of temperature skewness in ERA5. Daily maximum temperature in summer and daily minimum temperature in winter are analyzed. Atmospheric circulation is characterized by sea level pressure, which is subject to classification by the Jenkinson-Collison (JC) method at all gridpoints over the European continent with spatial resolution of 2.5° x 2.5°. The JC method is based on types pre-defined by the strength, direction, and vorticity of geostrophic flow. We utilize its versions with 27 types (full version) and 11 types (with 8 directional types, two vorticity-based types and one undetermined for a weak flow). Under each type and at every gridpoint, we count small negative and small positive DTDs (small DTDs defined approximately as central 50% of its distribution). Types with the largest difference between small positive and small negative DTDs (i.e., with the largest asymmetry in small DTDs) are then identified.

A general behaviour, characteristic for the majority of European landmass, can be summarized as follows: Anticyclonic types, types with weak flow, and types with warm advection from south to southwest directions contribute to the asymmetry of Tmax DTD in summer, while anticyclonic types and types with cold northerly to northeasterly advection contribute to the Tmin DTD asymmetry in winter. Nevertheless, under specific conditions (upwind or leeward side of mountains, seashore, valley), any of the 11 JC types can occur among the three that most support the DTD asymmetry.

How to cite: Huth, R., Stryhal, J., and Krauskopf, T.: Classifications of atmospheric circulation patterns as a tool for explaining asymmetry of day-to-day temperature difference, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10222, https://doi.org/10.5194/egusphere-egu24-10222, 2024.

EGU24-11748 | Orals | CL4.6

Impact of multidecadal climate’ modes variability on the Northern Hemisphere temperature trend in the recent decades 

Abhishek Savita, Joakim Joakim Kjellsson, Mojib Latif, Hyacinth Nnamchi, and Sebastian Wahl

In recent decades, the Northern Hemisphere (NH) exhibits a long-term regional cooling (central Eurasia) and warming (Arctic and Northern America) trend caused by human-induced anthropogenic forcing and internal decadal variability. In this study, we quantify the contribution of internal decadal variability to recent NH temperature trend using an atmosphere general circulation model (OpenIFS) by designing some sensitivity experiments for the period 1950-2014. In the reanalysis dataset (ERA5), we find a significant teleconnection between Interdecadal Pacific Variability (IPV) and surface air temperature (SAT) over Eastern Eurasia, the Barents Sea, and the Kara Sea for the periods 1950-2014 and 1993-2014, whereas we have not seen such a significant teleconnection with Atlantic Multidecadal Variability (AMV). The model simulates temperature anomalies associated with the IPV consistent with the ERA5, except for northern Eurasia where the sign of the temperature anomaly is reversed compared to ERA5. The model simulates AMV teleconnection with SAT is positive and significant over most of the places during 1950-2014, and it is significant over central Asia during 1993-2014. By analyzing the sensitivity experiments, in which we removed the decadal variability associated with IPV and AMV, we find that Eurasian cooling significantly increases without IPV and there is not much change without AMV. This indicates that some of the recent cooling over the Eurasian region is not driven by the IPV at least in the OpenIFS model, which shows IPV contributes to warm the Eurasian region. The preliminary results of this study suggest the potential importance of the internal variability of the Pacific Ocean is not only crucial on a regional scale but also crucial on a on a hemispheric scale (high latitudes).

How to cite: Savita, A., Joakim Kjellsson, J., Latif, M., Nnamchi, H., and Wahl, S.: Impact of multidecadal climate’ modes variability on the Northern Hemisphere temperature trend in the recent decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11748, https://doi.org/10.5194/egusphere-egu24-11748, 2024.

EGU24-12323 | ECS | Orals | CL4.6

High-frequency Intraseasonal Variability of Precipitation in South America and its link with Southern Hemisphere Teleconnection Patterns 

Francisca Aguirre Correa, Francisco Suárez, and Massimo Bollasina

The long-distance linkage between weather and climate conditions in different regions, i.e., teleconnection patterns, is crucial for understanding and predicting climate variability. In South America (SA), atmospheric Rossby waves originating in the maritime continent play a key role in triggering the South American Monsoon System across different timescales. Current studies have mainly focused on the long-term variability, mostly associated with seasonal, interannual and interdecadal temporal scales. On the contrary, intraseasonal variability has remained underexplored, especially the higher frequency relevant for the under two-week weather prediction. In this research, we investigate the high-frequency intraseasonal variability (HFISV, 8 – 20 days) of precipitation in SA by performing an empirical orthogonal function (EOF) analysis. For this, we use the CPC precipitation data for the summer period between 1979 – 2018. We also track its origin on teleconnection patterns in the Southern Hemisphere (SH) and local processes in SA by using lead and lag regression techniques based on ERA5 reanalysis data and NOAA outgoing longwave radiation. For this analysis, we give particular emphasis on describing active and break rainfall phases over SA. Our results show that HFISV significantly contributes to the total precipitation variability in the region (∼28%). We also found that extreme precipitation events in SA, which can lead to floods and droughts, are closely linked to anomalous high and low-pressure systems over the SH, demonstrating strong connections with Rossby waves in the mid-latitudes originated in the South Pacific Convergence Zone. At a local scale, spatial maps and cross-sectional analysis provided further insights, confirming that local processes feed back and enhance the extreme event, where low-level winds play a critical role in transporting moisture across the region. Local processes are afterwards able to reverse the winds and redistribute the moisture leading to a change in the monsoon phase. Our work highlights that predicting teleconnections, which modulate circulation anomalies and weather patterns, is a potential tool for precipitation subseasonal predictability. This is particularly relevant in arid areas where water is primarily available in the form of seasonal convective storms (e.g., in the Altiplano region), but also in a wider range as continents like Africa, which depend on the SA monsoon.

How to cite: Aguirre Correa, F., Suárez, F., and Bollasina, M.: High-frequency Intraseasonal Variability of Precipitation in South America and its link with Southern Hemisphere Teleconnection Patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12323, https://doi.org/10.5194/egusphere-egu24-12323, 2024.

EGU24-12351 | Posters virtual | CL4.6

The comparative study on the effects of NAO and GBO on the Hydroclimate in Southeastern Europe 

Ileana Mares, Constantin Mares, Venera Dobrica, and Crisan Demetrescu

The present investigation refers to the teleconnections of two climate indices with the observational data of the precipitation along the Danube River and of the Lower Danube Basin discharge.  Besides the well-known climate index associated with the North Atlantic Oscillation (NAO), a relatively new index was considered that reflects the baric contrast between the Balkan and the Greenland zones, the so-called the Greenland–Balkan Oscillation (GBO). This index was calculated as the difference of the normalized sea level pressure (SLP) at Nuuk and Novi Sad.

The influence of the GBO on the climate in southeastern Europe is stronger than that of the NAO. The comparative analysis was carried out for the entire 20th century, separately for each season.

The analysis of the effects of the two modes of variability was performed for precipitation, both punctually considering data from 15 meteorological stations along the Danube basin, as well as through the first principal component of precipitation (PC 1), and with regard to the discharge, the data were considered from the Orsova station located at the entrance of the Danube River in Romania.

For the precipitation in the middle and lower basin, as well as for the discharge of the Danube in the lower basin, the GBO signal is higher than that of the NAO. The intensity of this signal depends on the season. The highest difference between the GBO and NAO signals was evident in the winter season. The GBO is by construction almost complementary to the NAO, and considered together they can be good predictors for larger areas in Europe.

How to cite: Mares, I., Mares, C., Dobrica, V., and Demetrescu, C.: The comparative study on the effects of NAO and GBO on the Hydroclimate in Southeastern Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12351, https://doi.org/10.5194/egusphere-egu24-12351, 2024.

EGU24-13128 | Orals | CL4.6

How Greenland Ice Melt Could Influence Atmospheric Variability 

Jens H. Christensen, Camilla Andresen, Christine Hvidberg, and Larissa Van der Laan

The climate patterns across Northwest Europe are shaped by the transportation of warm and moist air from the North Atlantic Ocean, driven by large-scale atmospheric circulation. A possible key to this system is the variability in sea surface temperatures (SST) southeast of Greenland, possibly influencing the trajectory of weather systems.

A hypothesis suggests that the melting of the Greenland Ice Sheet plays a role in altering deep ocean convection in the Labrador Sea, leading to cooling in the ocean region southeast of Greenland. Studies propose that a substantial increase in meltwater from the Greenland Ice Sheet could potentially slow down the Atlantic Meridional Overturning Circulation (AMOC), impacting the Atlantic Storm track. In a worst-case scenario, this could shift Northwest Europe's climate from mild to subarctic conditions, reminiscent of glacial periods.

However, conflicting model studies suggest a different outcome, proposing that subpolar gyre cooling induced by freshwater fluxes might intensify the North Atlantic storm track.

To establish a robust connection between Greenland Ice Sheet melt and climate fluctuations in Northwest Europe, extended time series data beyond the instrumental record is essential. Additionally, a comprehensive understanding of specific climatic modes and associated storm track paths influenced by freshwater from the Greenland Ice Sheet is needed.

Preliminary evidence suggests a link between Greenland Ice Sheet melt variations and climate fluctuations in Northwest Europe. If fully validated, this connection holds significant implications for accurate climate predictions, particularly given the anticipated rise in melt rates of the Greenland Ice Sheet in the future. Ensuring precise climate predictions is critical for comprehending and preparing for potential shifts in weather patterns that could impact the region's climate and ecosystems

How to cite: Christensen, J. H., Andresen, C., Hvidberg, C., and Van der Laan, L.: How Greenland Ice Melt Could Influence Atmospheric Variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13128, https://doi.org/10.5194/egusphere-egu24-13128, 2024.

    The trend of global climate warming is strengthening. During the 20th century, climate warming has increased more than it was at any other time in history, seriously affecting water security and food supply. With global climate warming, extreme temperature events have occurred continuously in many regions of the world and have seriously damaged the ecological environment and human health. In this context, it is crucial to strengthen the understanding of regional extreme temperatures, analyze their changing characteristics and understand their impact on global climate warming. As one of the regions most affected by climate warming, the Tianshan Mountains has suffered several ecological crises, including retreating glaciers and water deficits. The climate warming in the Tianshan Mountains is considered to be mostly caused by increases in minimum temperature and winter temperature, while the influence of the maximum temperature is unclear. Here, a 300-year tree-ring chronology developed from Western Tianshan Mountains, China was used to reconstruct the summer (June–August) maximum temperature (Tmax6-8) variations from 1718 to 2017. The reconstruction explained 53.1% of the variance in the observational records. Over the past 300 years, the Tmax6-8 reconstruction showed obvious interannual and decadal variabilities and experienced roughly six warm periods (1723–1732 AD, 1768–1785 AD, 1818–1834 AD, 1841–1898 AD, 1911–1929 AD and 1973–2012 AD) and five cold periods (1733–1767 AD, 1786–1817 AD, 1835–1840 AD, 1899–1910 AD, and 1930–1972 AD). Our reconstructed Tmax6-8 showed a significant warming trend (0.183℃/decade) after the 1950s, which was close to the increasing rates of the minimum temperature and mean temperature. We found that this significant warming of maximum temperature was also present in the whole Tianshan Mountains. The impact of the maximum temperature on climate warming has increased and cannot be ignored. Our reconstruction was found to be reliable and representative according to spatial correlation analysis. Additionally, the extremely cold years in the Tmax6-8 reconstruction were due to the cooling effect of strong volcanic eruptions. The reconstructed Tmax6-8 series was positively correlated with solar activity and negatively correlated with the summer North Atlantic Oscillation (SNAO) index. Combined with the periodic analysis, these results demonstrated that the Tmax6-8 variations in the Western Tianshan Mountains, China was influenced by volcanic eruptions at high frequency and synergistically influenced by solar activity at low frequency. This study revealed the significant influence of maximum temperature variability on global climate warming and clarified the climate mechanism, which will aid in future climate change prediction.

How to cite: Ren, M. and Liu, Y.: Maximum summer temperatures for the Western Tianshan Mountains of China inferred from tree rings over the past 300 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14076, https://doi.org/10.5194/egusphere-egu24-14076, 2024.

The Arctic Sea plays a pivotal role in Earth's climate system by modulating ocean-atmospheric interactions, influencing heat exchange, with potential implications for regional phenomena such as Indian Summer Monsoon Rainfall (ISMR). We assess the performance of 26 Coupled Model Intercomparison Project Phase 6 (CMIP6) models in simulating Arctic Sea Ice based on historical data and climatology. The evaluation of selected models focus on their fidelity in accurately representing the intricate dynamics of Arctic Sea Ice by employing various statistical skill metric parameters. Additionally, we will investigate the potential connections between Arctic Sea Ice variability and ISMR using CMIP6 models. A multi-model ensemble mean of the top-performing models will be conducted to illuminate these associations. Further, the study will provide teleconnections and potential correlations through sea-level pressure (SLP) anomalies and velocity potential during ISMR. Overall, the research aims to evaluate the tropical-polar teleconnection and its predictive capacity for ISMR through CMIP6 models, thereby ensuring a better understanding of the critical climate dynamics.

How to cite: Sardana, D. and Agarwal, A.: Investigating CMIP6 Models for Arctic Sea Ice Dynamics and Predictive Links with Monsoon Precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14093, https://doi.org/10.5194/egusphere-egu24-14093, 2024.

The planet is warming due to the burning of fossil fuels, but the geographical pattern of the observed temperature change over the Pacific Ocean over the past ~40 years is profoundly different from our expectations based on the CMIP5/6 climate model simulations of both historical and future warming. Here we will present an argument that the observed pattern of warming is consistent with a forced response to increasing atmospheric carbon dioxide shaped by two-way atmospheric teleconnections between the Southern Ocean and tropical Pacific Ocean. The same two-way atmospheric teleconnections might also be capable of yielding low-frequency natural variability in sea surface temperature and sea level pressure anomalies resembling the observed trend patterns. We will offer reasons why the observed pattern of warming is not simulated by the climate models. The observed pattern of warming in the Pacific has first-order implications for climate sensitivity as well as for the projected changes in global-scale precipitation.

How to cite: Battisti, D., Armour, K., and Dong, Y.: The perplexing warming trend over the Pacific Ocean and the key role of two-way teleconnections between the Southern Ocean and the tropical Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14452, https://doi.org/10.5194/egusphere-egu24-14452, 2024.

The spatial distribution of summer rainfall anomalies over eastern China often shows a tripole pattern with rainfall anomalies over the Yangtze River basin varies in opposite phase with North China and South China. It is not clear whether this tripole pattern is an intrinsic atmospheric mode or it is remotely forced. Using two sets of model-outputs from 20 models participating in the fifth Coupled Model Inter-comparison Project (CMIP5), this paper investigates the driving mechanisms of this leading rainfall mode and its major influencing factors. One set (piControl) is fully coupled atmosphere-ocean simulations under constant pre-industrial forcing and the other (sstClim) is atmosphere-alone models forced by prescribed climatological sea surface temperatures (SSTs). By comparing results from these two different sets of simulations, it is found that the tripole pattern is the leading mode of summer precipitation variability over eastern China with or without oceanic forcing. It can be regarded as an intrinsic atmospheric mode although air-sea interaction can modify its temporal variability. The cyclonic/anti-cyclonic atmospheric circulation anomaly over the northern North Pacific is identified as a key factor in both experiments. As atmospheric internal variability, it is related to a circum-global zonal wave train propagating along the westerly jet stream. When air-sea interactions involved, modulation from SST anomalies is exerted through the meridional Pacific-Japan/ East Asia Pacific wave train propagating along the East Asian coast. Our results suggest that the North Pacific could be another key region providing potential predictability to the East Asian monsoon in addition to the Indo-Pacific.

How to cite: Duan, Y.: Disentangling the driving mechanisms of tripole mode of summer rainfall over eastern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14473, https://doi.org/10.5194/egusphere-egu24-14473, 2024.

EGU24-14656 | Orals | CL4.6

Connecting North American and European Weather Regimes 

Gabriele Messori and Joshua Dorrington

Weather regimes are recurrent and quasi-stationary atmospheric circulation patterns, typically linking to surface weather and extremes. Despite their widespread use, little is known on whether or how regimes defined in different regions relate to each other and reflect long-distance teleconnection patterns. Here, we shed light on this knowledge gap, focussing on North American and Euro-Atlantic regimes. The selection of these two regions is motivated by recent evidence pointing to a systematic connection between winter weather in North America and Europe. We find that specific pairs of North American and Euro-Atlantic regimes show a close statistical correspondence and that their joint analysis can provide medium-range statistical predictability for anomalies in their occurrence frequencies. Conditioning on North American weather regimes also results in anomalies in both the large-scale circulation during specific Euro-Atlantic regimes, and the associated European surface weather. We conclude that there is a benefit in conducting joint analyses of North American and European weather regimes, as opposed to considering the two in isolation.

How to cite: Messori, G. and Dorrington, J.: Connecting North American and European Weather Regimes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14656, https://doi.org/10.5194/egusphere-egu24-14656, 2024.

EGU24-15725 | Orals | CL4.6

Causal networks for quantifying the links of boreal winter atmospheric variability with Mediterranean climate on multiple temporal scales 

Maria Hatzaki, Giorgia Di Capua, Ioannis Chaniotis, Platon Patlakas, Reik Donner, and Helena A. Flocas

Large-scale atmospheric circulation is the major driver of near surface climatic variability and extremes, with teleconnection patterns being a significant component by connecting climates in remote locations. The recently developed powerful concept of causal effect networks (CENs) enables the detection of causal relationships among a set of actors by removing the confounding effects of autocorrelation, indirect links, and common drivers, retaining eventually only the actual causal links.

In this study, we apply the causal discovery algorithm to analyze the causal links among teleconnection patterns and other circulation features of the North Hemisphere and their influence on Mediterranean winter climate variability. We employ different sets of actors and multiple-scale temporal resolution reanalysis datasets to examine the consistency of the CENs across different timescales and to uncover the underlying mechanisms of their links. By investigating the strength of the different remote drivers compared to local drivers, this analysis contributes to a better understanding of the mechanisms controlling the intraseasonal variations in boreal winter circulation over the Mediterranean. In addition, we find that the strength of the causal links is affected by interannual and multidecadal variability, suggesting the potential involvement of external physical mechanisms.

How to cite: Hatzaki, M., Di Capua, G., Chaniotis, I., Patlakas, P., Donner, R., and Flocas, H. A.: Causal networks for quantifying the links of boreal winter atmospheric variability with Mediterranean climate on multiple temporal scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15725, https://doi.org/10.5194/egusphere-egu24-15725, 2024.

EGU24-15764 | ECS | Posters on site | CL4.6

Analysis of Sea Surface Pressure Climatology and Cyclogenesis Patterns over the Black Sea 

Büşra Öztürk and Mikdat Kadıoğlu

Semi-permanent low-pressure centers form as a result of topographical features and atmospheric flows. The precise location and intensity of these centers significantly influence the weather patterns in the surrounding countries. In the same context, the occurrence of cyclogenesis over the Black Sea, often mentioned as the Black Sea Low, significantly impacts the weather conditions in Türkiye. A cyclone must persist throughout the year to be classified as a semi-permanent pressure system, however, the literature indicates the potential existence of high-pressure areas in the Black Sea as well. This study aims to investigate the presence of the Black Sea Low by examining low-pressure centers over the region, to determine the frequency and seasonality of cyclonic activity. The ERA5 dataset with 0.25° resolution is used for the analysis, covering the period from 1940 to 2023. Related variables like mean sea level pressure, sea surface temperature, temperature, wind speed, and total precipitation are examined to investigate the persistence and seasonal variations of the low-pressure center over the Black Sea through synoptic pattern categorizations of cyclogenesis over the Black Sea. The preliminary results indicate a low-pressure pattern on the southeastern Black Sea, which is seasonal and forms during the summer months over the region.

How to cite: Öztürk, B. and Kadıoğlu, M.: Analysis of Sea Surface Pressure Climatology and Cyclogenesis Patterns over the Black Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15764, https://doi.org/10.5194/egusphere-egu24-15764, 2024.

EGU24-15940 | ECS | Posters on site | CL4.6

Validation of Mediterranean cyclones in GCM simulations against reanalysis 

Emília Dolgos, Rita Pongrácz, and Judit Bartholy

Mid-latitude cyclones have a great influence on the weather and the climate of the Mediterranean region. This study focuses on the western Mediterranean region, where we aim to identify changes in the number of cyclones and their characteristics based on ERA5 reanalysis data and historical simulations of global climate models from the CMIP6 project covering the period before 2014. For this purpose, mean sea level pressure is analysed to identify low-pressure systems, and these potential cyclone centres are then connected through timesteps to produce trajectories. Model data is regridded to 1° spatial resolution, with temporal resolution of 6-hour. Mediterranean cyclones not only affect the close vicinity of the Mediterranean Sea, but other parts of Europe as well, including Hungary, where the amount of the precipitation can be highly affected by the presence of Mediterranean cyclones (particularly in winter). For this reason, we aim to quantify what portion of the annual total precipitation is connected to the Mediterranean cyclones.

 

Acknowledgements: The study contributes to the COST CA19109 action (MEDCYCLONES). Research leading to this study has been supported by the following sources: the Hungarian National Research, Development and Innovation Fund (under grant K-129162), and the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014).

How to cite: Dolgos, E., Pongrácz, R., and Bartholy, J.: Validation of Mediterranean cyclones in GCM simulations against reanalysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15940, https://doi.org/10.5194/egusphere-egu24-15940, 2024.

EGU24-16824 | ECS | Orals | CL4.6

Global changes in low-level circulation types under future anthropogenic forcing 

Juan Antonio Fernandez de la Granja, Ana Casanueva, Joaquín Bedia, Swen Brands, and Jesús Fernández

Large-scale atmospheric circulation determines regional near-surface climate and, ultimately, causes diverse impacts on ecosystems and societies. Possible modifications of such large-scale features due to global warming would inevitably lead to changes in the weather regimes, affecting the local-to-regional climate response. Weather Type (WT) classification methods, such as the one proposed by Jenkinson and Collison (1977), provide a way to summarize mid-latitude, low-level circulation at a regional-scale (Jones et al, 2013; Fernández-Granja et al, 2023). JC-WTs classify sea-level pressure into 27 WTs spanning different local air flow directions and shear vorticities. This methodology can be used to evaluate Global Climate Models (GCMs), which stand as a key tool in the study of past and future climate evolution. Despite obvious biases, historical GCM simulations show a reasonable representation of the frequency of WTs worldwide (Brands 2022; Brands et al, 2023) and the newest model generation shows consistent improvements in the representation of WT occurrence (Fernández-Granja et al, 2021). This leads to the question of how WTs will evolve along the century under anthropogenic forcing. In this work, we address this question by considering an ensemble of GCMs from the CMIP5 and CMIP6 initiatives under different emission scenarios. We focused on evaluating the variations of the JC-WT frequencies under climate change, considering how they emerge from natural variability. Also, we analyzed the consistency between CMIP5 and CMIP6 WT projections and their associated uncertainties. The JC-WT classification was applied globally, so our findings can inform any climate impact research where changes in large-scale circulation play a fundamental role.

Acknowledgement: This work is part of project CORDyS (PID2020-116595RB-I00) funded by MCIN/AEI/10.13039/501100011033. J.A.F. acknowledges support from project ATLAS (PID2019-111481RB-I00) and grant PRE2020-094728 funded by MCIN/AEI/10.13039/501100011033 and ESF investing in your future.

References:

Brands, S., 2022. A circulation-based performance atlas of the CMIP5 and 6 models for regional climate studies in the Northern Hemisphere mid-to-high latitudes. Geoscientific Model Development 15, 1375–1411. DOI: 10.5194/gmd-15-1375-2022

Brands S, Fernández-Granja JA, Bedia J, et al (2023) A global climate model performance atlas for the southern hemisphere extratropics based on regional atmospheric circulation patterns. Geophysical Research Letters 50(10). DOI: 10.1029/2023GL103531

Fernández-Granja JA, Casanueva A, Bedia J, et al (2021b) Improved atmospheric circulation over Europe by the new generation of CMIP6 earth system models. Climate Dynamics 56:3527–3450. DOI: 10.1007/s00382-021-05652-9

Fernández-Granja, J. A., Brands, S., Bedia, J., et al (2023) Exploring the limits of the Jenkinson–Collison weather types classification scheme: a global assessment based on various reanalyses. Climate Dynamics. DOI: 10.1007/s00382-022-06658-7

Jones P.D., Harpham C., Briffa K.R. (2013) Lamb weather types derived from reanalysis products. International Journal of Climatology 33(5):1129–1139. DOI: 10.1002/joc.3498

Jenkinson A., Collison F. (1977) An initial climatology of gales over the north sea. synoptic climatology branch memorandum. Meteorological Office, 62

Keywords: Jenkinson–Collison classification, weather types, global climate models, climate change.

How to cite: Fernandez de la Granja, J. A., Casanueva, A., Bedia, J., Brands, S., and Fernández, J.: Global changes in low-level circulation types under future anthropogenic forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16824, https://doi.org/10.5194/egusphere-egu24-16824, 2024.

Weather regimes (WRs) provide useful information about large scale variability over relatively large regions, and they can be linked to extreme events occurring at the land surface, such as heat waves and extreme precipitations. Studies in this direction have shown how e.g., Euro-Atlantic WRs modulate flow dependent variability in North America and Europe and their links to extreme precipitation events. To date, the relationship of weather regimes specific to the Mediterranean with extreme events have not been sufficiently explored. The Mediterranean region is a hotspot for climate change and for its peculiar position, at the frontier between very different systems, it is influenced by a complex mix of large-scale variability processes. Under the hypothesis that these processes are explained better by considering atmospheric fields over the Mediterranean region, we proceed by extracting EOFs over the Mediterranean domain (25 to 50 North, and −10 to 40 East), and we identify, for the first time in this region, year-round weather regimes. This allows for a systematic detection of extremes that is not limited to a specific season but throughout the year. After describing each regime pattern and corresponding average conditions (temperature, precipitation), we explore their links to extreme precipitations in the area and finally compare results with EAT-WRs to assess which WR domain is more closely related to these events.

How to cite: Giuntoli, I. and Corti, S.: Year-round Mediterranean Weather Regimes for exploring the occurrence of extreme precipitations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17290, https://doi.org/10.5194/egusphere-egu24-17290, 2024.

EGU24-18438 | ECS | Posters on site | CL4.6

Data Density Effects on North Antlantic Oscillation Reconstruction: Analysis and Application 

Larissa van der Laan, Anna Kirchner, Simon P. Heselschwerdt, and Jens Hesselbjerg Christensen

A deep understanding of the climate system and its variability is essential for the development of reliable climate predictions. Over the North Atlantic, the North Atlantic Oscillation (NAO), characterized by pressure differences between Iceland and the Azores, is the dominant mode of near-surface atmospheric circulation variability. It explains approximately half of the interannual variability in winter atmospheric pressure in the North Atlantic sector and affects jet streams, storm tracks, and surface climate conditions in surrounding areas. In order to improve understanding of the NAO, its teleconnections and longer-term patterns, multiple means of reconstruction have been employed over time, both model- and proxy-based. Due to the point-based nature of proxy data, the applicability of these reconstructions on a wider spatial scale is difficult to estimate.

We investigate the relationship between spatial data density and reconstruction accuracy through conducting a series of principal component-based NAO reconstructions from temperature and precipitation data. The amount of data available to reconstruct from is thinned through spatial hyperslabbing. Using ERA5 temperature data, the correlation between the reconstructed and observed NAO index for 1990-2020 decreases only little, from 0.80 to 0.79 and 0.78, when thinning the original amount of data (N = 78,899 data points) to 17% and 0.09%, respectively. The variability however is lowered significantly, limiting information on the strength of the NAO. The impact of data density and location is then applied to create a ranking of the utility and estimate biases in existing proxy-based NAO reconstructions and potential future ones. Using this information, we finally create a multi-proxy NAO reconstruction for the past two millennia.

How to cite: van der Laan, L., Kirchner, A., Heselschwerdt, S. P., and Hesselbjerg Christensen, J.: Data Density Effects on North Antlantic Oscillation Reconstruction: Analysis and Application, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18438, https://doi.org/10.5194/egusphere-egu24-18438, 2024.

Previous research has extensively explored the “stilling” and “reversal” phenomena in annual near-surface wind speed (NSWS). However, the variations in the strengths of these phenomena between different months remain unclear. Here the monthly changes in observed NSWS from 769 stations across China during 1979–2020 were analyzed. The analysis reveals a consistent decline in NSWS that ceased around 2011, followed by an increasing trend detected in all months except March, where a distinct hiatus is observed. The hiatus in March NSWS is primarily attributed to a significant reduction in NSWS over North and Northwest China. This reduction can be linked to the southward shift of the East Asian subtropical jet (EASJ), which resulted in a decreased meridional temperature gradient and weakened transient eddy activities across northern China. These findings emphasize the importance of considering changes in the EASJ to gain a comprehensive understanding of NSWS changes at a regional scale.

How to cite: Shen, C.: East Asian Subtropical Jet Impact on Monthly Near-surface Wind Speed Change over China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20851, https://doi.org/10.5194/egusphere-egu24-20851, 2024.

EGU24-21134 | ECS | Orals | CL4.6

No consistent improvement in tropical Pacific sea surface temperature pattern in high-resolution climate models 

Shreya Dhame, Dirk Olonscheck, and Maria Rugenstein

Most of the coarse resolution Coupled Model Intercomparison Project (CMIP) climate models simulate a weakening of the equatorial Pacific east-west sea surface temperature (SST) gradient, contrary to the observation since the mid-1970s. Proposed reasons for this model-observation discrepancy are the equatorial Pacific cold tongue bias and the underestimation of equatorial trade wind strength in enhancing the upwelling in the central to eastern Pacific Ocean. Higher oceanic resolution has been known to improve eddy-induced heat transport, equatorial Pacific mean state SSTs, and precipitation. Here, we assess SST mean state biases and trend responses in a multi-model and multi-resolution ensemble from the High-Resolution Model Intercomparison Project (HighResMIP). Some models show an alleviation of the cold tongue bias in simulations of higher resolution compared to their respective low-resolution simulations, however, there is no consistent improvement across models in the trend response of the equatorial eastern Pacific SSTs at a higher resolution. Models are deficient in simulating the synchrony of trends and the causal relationships between surface zonal wind, SSTs, and thermocline structure in the eastern equatorial Pacific Ocean on multidecadal timescales. An underestimated ocean thermostat mechanism might explain climate models’ inability to simulate equatorial Pacific SST patterns since the mid-1970s. Simulating air-sea coupling correctly on multidecadal timescales in models might reduce the uncertainty of the projected tropical Pacific SST gradient.

How to cite: Dhame, S., Olonscheck, D., and Rugenstein, M.: No consistent improvement in tropical Pacific sea surface temperature pattern in high-resolution climate models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21134, https://doi.org/10.5194/egusphere-egu24-21134, 2024.

It is expected that sea level rise and resulting coastal flooding will cost us over 1 trillion dollars annually by 2050. Therefore, understanding and monitoring coastal sea level rise is vital. Tide Gauges are in-situ instruments that have been providing sea level measurements since the 1800s, but they are sparse, and data availability is limited. Therefore, ocean altimetry has been the preferred observational tool for monitoring global sea levels.  

Satellite altimetry has been providing extensive and continuous global sea level data for more than three decades now. However, extracting reliable data close to the coast has been problematic due to signal contamination from land or calm water and lack of accurate geophysical corrections. Recently dedicated coastal altimetry products were proposed to provide better coastal sea level change product.   

In this study, we compare coastal altimetry products XTRACK-1Hz, XTRACK/ALES-20Hz in observing Sea Level Anomalies (SLA) with Tide Gauges (TG) along the global coastline from 2002-2019. 458 stations were selected for the study after applying several selection criteria that address data gaps, data availability from TG, altimetry, and correction products. The SLA signals from TG were decomposed into non-linear trend, seasonal, and residual components using Seasonal-Trend Decomposition using Loess (STL) method. The correlation coefficient, Root Mean Square Error (RMSE), and Index of Agreement (IOA) were computed for interannual and residual signals from TG and coastal altimetry products. Linear sea level trends at each station were also estimated from altimetry and TG observations after correcting for GPS-derived vertical land motion (VLM). 

When using altimetry for sea level signals near the coast, it is important to select point observations carefully instead of using a search radius that may take points from adjacent regions that could behave differently due to different coastal ocean processes. We developed a dynamically varying search radius for each TG, a function of the coastal shelf width near that station, to collate satellite observations as a representative of coastal sea level change. All the altimetry observations that fall within the search radius and are less than 25 km along the coast are used for comparison. In several cases, due to the sharp changes in the coastal morphology, the sea level signals seen by the adjacent TG stations are quite different, and thus, the reliability of altimetry suffered. 

With our analysis approach, we found good agreement between all altimetry products (XTRACK, XTRACK/ALES), and TG at residual and non-linear trend scales. A few stations near the fault lines and other tectonic regions disagree with altimetry trend estimates due to strong VLM signals that are not completely resolved by the VLM product used for correction. Around 70% of stations had a good agreement (r > 0.7) with trend and 55% with residual components. High-resolution (20Hz) XTRACK/ALES provided more observations near the coast. Nevertheless, both XTRACK/ALES-20Hz and XTRACK-1Hz performed well. This novel approach to select representative observation points from altimetry for a coastal zone will provide improved coastal sea level products from satellites, which can be considered at par with TG observations. 

How to cite: Sukumaran, V. and Vishwakarma, B. D.: Comparing altimetry-derived coastal sea level anomaly with tide gauge observations along the global coastline by accounting for shelf-width , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1007, https://doi.org/10.5194/egusphere-egu24-1007, 2024.

Worldwide geological markers of former sea-level (SL), such as wave-cut benches (raised, drowned), reveal a ~3-metre(m) SL rise, loosely carbon-dated post-50AD/pre-600. This "Rottnest Transgression" is the youngest of several m-scale rises, interspersed with m-scale falls, on Fairbridge's (1961) global-compilation Holocene-interglacial SL curve.

Copious British archaeological evidence (email me for sources), far better-dated (pottery-sherds/dendrochronology/Roman coins), confirms the Rottnest ("Romano-British marine transgression" of Godwin 1955), verifies its amplitude (~3m), and shows it spanned only ~70 years(y), ~430-500AD (early Dark Ages; Romans abandoned Britain 410AD). (An equally fast global SL rise, ~3m in decades, is proven by last-interglacial reef-facies relationships in tectonically stable Yucatan.) The Rottnest explains 5th-Century(C) mass-migration, underway by 450AD (dendro/artefacts/skeletal-DNA), of Saxon- and Angle civilians to SE Britain ('pre-subjugated' by rebellious Saxon mercenaries by 441AD), their North-Sea-coastal-plain homelands intolerably 'squeezed' between west-advancing Huns and rapid eastward shore-retreat. Among other British evidence: (1) Pevensey sea-fort (Roman-built ~290AD) straddles a promontory pointing NE into Pevensey Levels (reclaimed former tidal-flat embayment, beside English Channel). Indicating that high-spring-tide-level (HSTL) rose >2m in the 5thC, a defensive-ditch fronting the fort's SW gate contains "tidal" mud, dated early-5thC (sherds), whose top is ~1m higher than the NW-wall foundation and <0.5m higher than the SE foundation. This explains wall-collapse in both sectors (outward-toppled slabs visible on GoogleEarth), undermined by waves/currents, no later than mid-or-late 5thC (age of Early-Saxon-style sherd in sediment draping excavated wall-stump). Subsequent HSTL fall enabled William the Conqueror's 1066AD disembarkation at Pevensey fort; (2) excavated remnant stumps of Londinium's Thames-estuary-side city-wall (~270-300AD), up to 2.5m tall, show their entire outer face eroded (wall thinned ~50%), implying HSTL rose 3+m post-construction. Confirming this rise and its likely 5thC timing, across the Thames (Southwark) a peat layer containing 4thC sherds is capped by 2.8m of barren "river clay", reaching 3.2m higher than Londinium's lowest-known Thames-side wall-foundation. Proving HSTL soon fell 2+m, 1km upstream, in Lundenwic (Saxon port founded late-5thC), a building-floor dated ~700-750AD (sherds) is 1.6m lower than Londinium's highest-known wall erosion, and 1.5m below the top of the river-clay.

Such a large/fast global SL rise implies a peri-Antarctic 'MICI' ice-cliff-collapse event (Greenland lacks requisite >1km-deep grounding-line). Regarding causation, the Rottnest rise began (~430AD) only ~25y after the ~405AD warmest Arctic temperature-spike of the period 1-2000AD. This spike followed ~100y after the Sun's 310AD strongest magnetic-grand-maximum (MGM) peak of the interval 1-1885AD. The ~100y lag is attributable to ocean-thermal-inertia. The additional ~25y lag in SL response (Rottnest start) may reflect AMOC 'conveyor-belt' oceanic-circulation, specifically the time needed for ocean-surface-water, 'overwarmed' by the MGM (Svensmark effect, reduced cloudiness), to down-well in the north-Atlantic (Arctic fringe), then travel south, then up-well and encircle Antarctica, unleashing ice-collapse. The resulting iceberg-armada would cool the ocean, hence the atmosphere, causing increased global snowfall (ice build-up), intrinsically lowering SL.

Due to anthropogenic warming, the Arctic's average-surface-air-temperature exceeds, since 2005, the 405AD peak. This portends another rapid, metre-scale SL rise, beginning ~2030 (25y lag, above). Before 2100 the time-lagged effect of the Sun's even-stronger 1991 MGM peak will exacerbate warming.

How to cite: Higgs, R.: British archaeology verifies 5th-Century rapid multi-metre sea-level rise and portends another before 2100, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1322, https://doi.org/10.5194/egusphere-egu24-1322, 2024.

Sea level in the Southeast Asia (SEA) seas is driven by various phenomena at global,  regional and local scales. The latest tide gauge and satellite data revealed its most recent spatial and temporal patterns. The trend of global sea level rise in Singapore region is hindered by dominant variability of El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Indian Ocean Dipole (IOD), as well as associated modulation of Asian Monsoon. It was confirmed that positive sea-level anomalies in the southern and western areas of Southeast Asia seas were significantly high (~10 cm) during the northeast monsoon, especially in the Gulf of Thailand (~25 cm). The sea level trends for these regions were basically reversed during the southwest monsoon but with a smaller magnitude of negative sea-level anomalies. The regional sea-level trend in the Sunda Shelf differed from region to region, with the rates varied greatly from 1.4 to more than 4.8 mm/year. Interestingly, the rates on the east-western side of the region were roughly 3.0-4.5 mm/year, which were higher than the ones at other regions, being 2.5-3.5 mm/year. The presentation discuss the causes and consequences of sea level rise and variability in SEA and Singapore region in particular.

This Research is supported by Singapore’s National Research Foundation and National Environment Agency under the National Sea Level Programme Funding Initiative (Award No. USS-IF-2020-4).

How to cite: Tkalich, P. and Luu, Q.-H.: Recent Sea Level Rise and Variability in Singapore Region Derived from Tide Gauges and Satellite Altimetry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2288, https://doi.org/10.5194/egusphere-egu24-2288, 2024.

Dynamical downscaling employing high-resolution ocean models is widely considered as an efficient approach for modelling of regional ocean dynamics and sea-level changes using output of original coarse-resolution global general circulation models (GCMs). In this study, the historical dynamic variability and trends of sea level in the South China Sea (SCS) and the Southeast Asia Seas (SEAS) are investigated using the high-resolution regional ocean model (NEMO). Two hindcast ocean modelling experiments are conducted for the period 1960-2014. One is driven by global reanalysis data (ERA5 and ORAS5) forcings at the lateral and surface boundaries. The other is driven by global modelling oceanic data (EC-EARTH3) at the lateral boundary and by WRF-based downscaled atmospheric fields from the same parent model (EC-Earth3) at the surface boundary. Using the hindcast model runs, variability and trends of low-frequency sea-levels, as well as the driving mechanisms and the related processes are discussed, and the model performance and biases are analysed.

This Research is supported by Singapore’s National Research Foundation and National Environment Agency under the National Sea Level Programme Funding Initiative (Award No. USS-IF-2020-4).

How to cite: Ma, P., Gangadharan, N., and Tkalich, P.: Modelling of Low Frequency Sea Level Variability Over the Maritime Continent: Historical Dynamic Variability and Changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2405, https://doi.org/10.5194/egusphere-egu24-2405, 2024.

EGU24-3440 | ECS | Orals | CL4.9

Quantifying the impact of near-surface winds on the occurrence of extreme sea level rises along the Swedish Baltic coastline: A statistical analysis 

Lorenzo Minola, Alice Re, Shalenys Bedoya-Valestt, Corrado Motta, Cesar Azorin-Molina, Alessandro Pezzoli, and Deliang Chen

Sea level rises pose significant risks to densely populated coastal regions, threatening human lives and vital infrastructures. Coastal societies, economies, and properties face acute vulnerability from saltwater intrusion, coastal erosion, and flooding resulting from extreme sea level variations. These occurrences are a confluence of factors, including local sea level rises, tidal changes, storm surges, waves, and shifts in coastal morphology.

In the Baltic Sea basin, where tides and North Atlantic storm surges are mitigated by the Danish Straits due to its semi-enclosed nature, coastal extreme sea levels are primarily driven by storm surges propelled by atmospheric pressure and surface winds from extratropical cyclones. Consequently, the surge in extreme sea levels here is predominantly wind-induced, regulated by meteorological processes.

This research focuses on the meteorological conditions, specifically wind patterns, that contribute to sudden sea level rises along the Swedish Baltic coastline. By integrating observations and model data like the ERA5 reanalysis, the study correlates the rapid increase in relative sea levels across 14 tide-gauge stations with wind and wave data. The aim is to exclusively utilize meteorological information for identifying extreme sea level occurrences, thereby enhancing the prediction of such events through weather forecasting.

How to cite: Minola, L., Re, A., Bedoya-Valestt, S., Motta, C., Azorin-Molina, C., Pezzoli, A., and Chen, D.: Quantifying the impact of near-surface winds on the occurrence of extreme sea level rises along the Swedish Baltic coastline: A statistical analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3440, https://doi.org/10.5194/egusphere-egu24-3440, 2024.

EGU24-3445 | ECS | Posters on site | CL4.9

Are multi-decadal sea-level oscillations augmenting rates of mean sea level? 

Erin Robson, Luke Jackson, and Sophie Williams

There is evidence to show sea-level change is accelerating, with a departure from Holocene rates in the late-19th century, to more than a doubling of the rate of global mean sea-level change over the past 25-years. Although the effect of anthropogenic forcing on sea level is certain, the influence of natural internal variability on augmenting rates of change remains an important area of research. This is especially significant at ocean-climate response timescales (>30-years). Using tide-gauge data, we apply empirical mode decomposition (EMD) to separate both the global and regional sea-level records into a series of intrinsic mode functions (IMFs) that are quasi-periodic in character. From them, we identify the dominant modes of variability that are common to each ocean basin, and compare these to recognised modes of climate variability to determine the causal factors of sea-level oscillations. We also conduct a sensitivity analysis with sub-sampled tide-gauge data to test the feasibility of this approach with high-resolution proxy-based sea-level reconstructions.

How to cite: Robson, E., Jackson, L., and Williams, S.: Are multi-decadal sea-level oscillations augmenting rates of mean sea level?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3445, https://doi.org/10.5194/egusphere-egu24-3445, 2024.

EGU24-3503 | Orals | CL4.9 | Highlight

Improving, evaluating and sharing projections of global mean sea level rise 

Tamsin Edwards, Fiona Turner, and Victor Malagon Santos and the EU PROTECT project
Projections of the ice sheet and glacier contributions to sea level rise to 2100 in the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report were made by representing physical models with statistical "emulators" or machine learning techniqes (Edwards et al., 2021). This allowed estimation of the impacts of several kinds of model uncertainty on sea level projections: multiple models for the ice sheets and glaciers, multiple settings determining ice sheet sensitivity to climate change, and multiple estimates of global warming, as well as uncertainty from the emulators themselves.
 
However, there were some limitations, including: predicting each year of the century independently (i.e. not providing smooth timeseries or the possibility to assess rates of change), beginning physical model simulations in 2015 (not allowing evaluation with observations), and exploring a small number of possible model settings. Projections beyond 2100 also had to be estimated for the IPCC with other methods. These limitations presented difficulties for users.
 
We improve on these projections here in their usefulness and robustness for coastal impacts communities and decision-makers. Usefulness: by predicting ice sheet and glacier changes to 2300, not 2100; providing smooth timeseries; and incorporating the emulators into the community FACTS sea level calculation framework (Kopp et al., 2023) for use by others. Robustness: by systematically exploring many more model settings than before (including, for the first time, those for glacier models), and beginning in the past to allow calibration of the projections with observations. The result is more meaningful trajectories of sea level contribution from each land ice source, in which we have greater confidence. We combine these in FACTS with estimates of thermal expansion and land water changes to show new projections of global mean sea level rise. This work was carried out by the EU Horizon 2020 project PROTECT.
 
References:
 
Edwards et al. (2021) Projected land ice contributions to twenty-first-century sea level rise, Nature, 593, 74–82.
 
Kopp et al. (2023) The Framework for Assessing Changes To Sea-level (FACTS) v1.0: a platform for characterizing parametric and structural uncertainty in future global, relative, and extreme sea-level change, Geosci. Model Dev., 16, 7461–7489. 
 

How to cite: Edwards, T., Turner, F., and Malagon Santos, V. and the EU PROTECT project: Improving, evaluating and sharing projections of global mean sea level rise, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3503, https://doi.org/10.5194/egusphere-egu24-3503, 2024.

EGU24-4335 | ECS | Orals | CL4.9

Uncertainties in the projection of dynamic sea level in CMIP6 and FGOALS-g3 large ensemble 

Chenyang Jin, Hailong Liu, Pengfei Lin, and Yiwen Li

Decision-makers need reliable projections of future sea level change for risk assessment. Untangling the sources of uncertainty in sea level projections will help narrow the projection uncertainty. Here, we separate and quantify the contributions of internal variability, intermodel uncertainty, and scenario uncertainty to the ensemble spread of dynamic sea level (DSL) at both the basin and regional scales using Coupled Model Intercomparison Project Phase 6 (CMIP6) and FGOALS-g3 large ensemble (LEN) data. For basin-mean DSL projections, intermodel uncertainty is the dominant contributor (>55%) in the near- (2021-2040), mid- (2041-2060), and long-term (2081-2100) relative to the climatology of 1995-2014.  Internal variability is of secondary importance in the near- and mid-term until scenario uncertainty exceeds it in all basins except the Indian Ocean in the long-term. For regional-scale DSL projections, internal variability is the dominant contributor (60~100%) in the Pacific Ocean, Indian Ocean and western boundary of the Atlantic Ocean, while intermodel uncertainty is more important in other regions in the near-term. The contribution of internal variability (intermodel uncertainty) decreases (increases) in most regions from mid-term to long-term. Scenario uncertainty becomes important after emerging in the Southern, Pacific, and Atlantic oceans. The signal-to-noise (S/N) ratio maps for regional DSL projections show that anthropogenic DSL signals can only emerge from a few regions. Assuming that model differences are eliminated, the perfect CMIP6 ensemble can capture more anthropogenic regional DSL signals in advance. These findings will help establish future constraints on DSL projections and further improve the next generation of climate models.

How to cite: Jin, C., Liu, H., Lin, P., and Li, Y.: Uncertainties in the projection of dynamic sea level in CMIP6 and FGOALS-g3 large ensemble, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4335, https://doi.org/10.5194/egusphere-egu24-4335, 2024.

EGU24-5010 | ECS | Orals | CL4.9

Mid Holocene relative sea-level changes from coral microatolls of Pulau Biola, Singapore  

Jennifer Quye-Sawyer, Jing Ying Yeo, Wan Lin Neo, Zihan Aw, Lin Thu Aung, Nurul Syafiqah Tan, Junki Komori, Ke Lin, Xianfeng Wang, and Aron J. Meltzner

Coral microatolls are precise proxies of relative sea-level (RSL) change in low-latitude coastal regions. These coral colonies live in the intertidal zone where partial mortality due to low-water events produces a characteristic planform ring structure. Since ring elevations reflect changes in local RSL during a coral’s lifetime, we can use the surface profiles of microatolls to quantify short-term (decadal) rates of RSL change. Therefore, Holocene fossil microatolls can produce sea-level index points (SLIPs) with relatively high spatial and temporal resolution. In this study, we present preliminary sea-level reconstructions from Pulau Biola (Violin Island), Singapore, based upon several Porites sp. and Diploastrea heliopora fossil microatolls. We calculated the difference in elevation between the fossils and local living microatolls of the same genus to quantify the magnitude of past water level. We also combined U-Th ages, structure-from-motion photogrammetry and LiDAR 3D models, and survey data to generate a RSL history spanning more than two centuries in the mid Holocene. The highest-elevation fossil microatolls at Pulau Biola are consistent with an overall rise in sea level, from 0.2 to 0.7 m above present, between 7.7 and 7.4 kyr BP. In addition, decimetre-scale sea-level fluctuations during this period are inferred from decreasing and increasing ring elevations within corals. These fluctuations indicate a more complex sea-level history than resolved by other proxies or glacial isostatic adjustment models, and ongoing work aims to reconcile conflicting Holocene sea-level models and datasets in the Singapore region.

How to cite: Quye-Sawyer, J., Yeo, J. Y., Neo, W. L., Aw, Z., Aung, L. T., Tan, N. S., Komori, J., Lin, K., Wang, X., and Meltzner, A. J.: Mid Holocene relative sea-level changes from coral microatolls of Pulau Biola, Singapore , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5010, https://doi.org/10.5194/egusphere-egu24-5010, 2024.

Southern Hemisphere observational records of sea-level change are rare prior to ~1950, making it difficult to close historical regional sea-level budgets and quantify individual contributions to sea level (e.g. barystatic, thermosteric). Recent work generated four microfossil-based high-resolution sea-level reconstructions from southeastern Australia, all of which indicated rapid regional rates of 20th century sea-level rise compared to the global average. However, unlike analogous work in the North Atlantic (for which there is a high-density network of high-resolution reconstructions), there remains a paucity of proxy data from the Southern Hemisphere, hindering a probabilistic estimate of regional drivers of relative sea level using a spatio-temporal model.

We generate two new reconstructions using salt-marsh foraminifera from King Island, Tasmania, and Venus Bay, Victoria, to add to a growing database of Common Era sea-level reconstructions from southeastern Australia (and indeed wider Australasia). Fossil foraminifera indicate a rising palaeomarsh over the last ~150 years of ~0.15-0.25 m (average); this is interpreted as relative sea-level rise consistent with patterns observed in recent reconstructions. A chronology for the core is developed using both 14C and lead isotopes. Ongoing efforts to supplement the regional database will allow us to determine local and regional drivers of relative sea-level change in the region.

How to cite: Williams, S., Carvalho, R., Perry, P., Reef, R., and Sefton, J.: Drivers of Common Era sea-level change in southeastern Australia: extending tide-gauge records and developing a network of high-resolution reconstructions for regional analyses., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5258, https://doi.org/10.5194/egusphere-egu24-5258, 2024.

EGU24-6564 | Orals | CL4.9

Emulating Thermosteric Sea-Level Rise Using a Three-Layer Energy Balance Model 

Víctor Malagón-Santos, Aimée Slangen, Tim Hermans, Tamsin Edwards, and Fiona Turner

Although the mass loss of land ice is projected to be the largest contribution to sea-level rise in the coming centuries, thermal expansion will also be an important contributor and its accurate projection is primordial to understanding sea-level change over (multi-)centennial timescales. Earth System Models (ESMs) are the main tools for projecting thermosteric sea-level rise. ESMs, however, are computationally demanding and therefore long, multi-centennial simulations are challenging. In this study, we use a physical-based emulator that simplifies the climate system by using three vertically stacked layers, allowing us to mimic the energy balance response of ESMs to reproduce their thermal expansion simulations. We use this emulator to extrapolate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) from 2100 to 2300 and validate our method with CMIP6 runs that are available over that time scale. Overall, the three-layer emulator outperforms its two-layer predecessor in simulating thermal expansion up to 2300, providing a reduction of up to 78% in cumulative error for the projection period covering 2100 to 2300. Finally, we demonstrate how using temperature output from the three-layer model can help us capture non-linearities in dynamic sea-level change better than its two-layer counterpart. The latter is a first step towards building more reliable emulation approaches for oceanic processes affecting regional sea-level change.

How to cite: Malagón-Santos, V., Slangen, A., Hermans, T., Edwards, T., and Turner, F.: Emulating Thermosteric Sea-Level Rise Using a Three-Layer Energy Balance Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6564, https://doi.org/10.5194/egusphere-egu24-6564, 2024.

EGU24-6921 | Posters on site | CL4.9

Modelling dependence between the ice-sheet components of sea-level rise 

Benjamin S. Grandey, Justin Dauwels, Svetlana Jevrejeva, Antony J. Payne, Zhi Yang Koh, Benjamin P. Horton, and Lock Yue Chew

Sea-level projections are sensitive to statistical dependence between the East Antarctic, West Antarctic, and Greenland ice-sheet components.  The dependence is produced by climate uncertainty and ice-sheet process uncertainty.  To investigate this dependence, we model the dependence using copulas.  We use a vine copula to couple the ice-sheet components of projected sea level in 2100 under the SSP5-8.5 scenario.  Assumptions about rank correlation and copula family influence both the centre and the tails of the total ice-sheet contribution.  For example, rank correlation can influence the 95th percentile by approximately 50%.  We explore three alternative approaches for specifying the dependence: shared dependence on global-mean surface temperature, dependence derived from ice-sheet model ensembles, and dependence derived from expert judgement.  Shared dependence on global-mean surface temperature produces little dependence between the ice-sheet components.  In contrast, ice-sheet model ensembles suggest that the dependence between the East and West Antarctic ice-sheet components may be strong, amplifying the uncertainty in future sea-level rise.

How to cite: Grandey, B. S., Dauwels, J., Jevrejeva, S., Payne, A. J., Koh, Z. Y., Horton, B. P., and Chew, L. Y.: Modelling dependence between the ice-sheet components of sea-level rise, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6921, https://doi.org/10.5194/egusphere-egu24-6921, 2024.

EGU24-7891 | Orals | CL4.9

Revisiting the relation between ocean heat storage and thermal expansion from a water mass perspective 

Robin Waldman, Benoît Meyssignac, Sébastien Fourest, Robin Guillaume-Castel, Karina von Schuckmann, and Jean-Baptiste Sallée

The excess anthropogenic ocean heat is causing thermal expansion, which has driven approximately 40% of the industrial-era global mean sea level rise. This relation between ocean heat uptake H and thermosteric sea level rise hθ is mediated by the so-called expansion efficiency of heat (EEH=hθ/H, in m/YJ) which characterises the expansion of a water-mass under a unit increase of its enthalpy. The EEH of a water-mass depends on its temperature, salinity and pressure. At global scale the EEH has been characterized in both historical observations and climate simulations, but the the role of regional EEH and of individual water-mass layers in the formation of this global expansion efficiency remains undocumented. Here we propose a new approach where the EEH is decomposed in temperature coordinate into a temperature plus a pressure contribution to seawater thermal expansion. We show that the temperature contribution largely dominates the global signal. We also show that the global EEH can be interpreted as a weighted global average thermal expansion coefficient.

We make use of the global EEH decomposition in temperature coordinate to estimate the contribution of individual water-mass layers to global thermal expansion in both historical reference observational datasets and Climate Model Intercomparison Project (CMIP5-6) historical and scenario simulations. Results show a contrasting picture of water mass contributions to global thermal expansion and sea level rise. Whereas ocean warming is distributed between mode, intermediate and deep waters, a disproportionate share of global ocean expansion occurs within tropical waters and subtropical mode waters. Regionally, tropical Pacific waters and subtropical north Atlantic mode waters appear as key contributors to global thermal expansion. These results show that the regional distribution of ocean heat uptake is a key driver of thermal expansion and sea level rise not only at regional scale but also at global scale. We also show that projections of future sea level rise at global scale critically depend on the ability of climate models to simulate both the regional water mass properties and their heat uptake.

How to cite: Waldman, R., Meyssignac, B., Fourest, S., Guillaume-Castel, R., von Schuckmann, K., and Sallée, J.-B.: Revisiting the relation between ocean heat storage and thermal expansion from a water mass perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7891, https://doi.org/10.5194/egusphere-egu24-7891, 2024.

EGU24-8462 | ECS | Posters on site | CL4.9

Eddy variability contribution to decadal regional sea level trends 

Benoit Laurent, William Llovel, Anne-Marie Treguier, and Antoine Hochet

Sea level rise is one of the most direct consequences of the actual global warming. Over the 20th century, global mean sea level rises at a rate of 1.5-2 mm. yr-1. Since the beginning of the 1990s, satellite altimetry measure the changes of sea level with a near global coverage (from 66oS to 75oN). The use of satellite altimetry has, for the first time, highlighted large regional variability in sea level trends that significantly differ from the global mean estimate. If global ocean warming and land ice melting (mountain glaciers and ice sheets from Greenland and Antarctica) are the main processes explaining the observed global mean sea level rise, at regional scales, other processes are involved, such as changes in salinity or temperature associated with ocean circulation or air-sea fluxes at the ocean surface.

 

Sea level projections used in IPCC reports are based primarily on coarse-resolution coupled climate models. Current projections are based on climate models in which ocean-eddy variabilities are parameterized and results deviate from observations especially in the Southern Ocean. Mesoscale processes transport heat/freshwater over very large distances in the ocean (both horizontally and vertically). They also regulate energy, moisture and carbon exchanges between the oceans and the atmosphere via coupling. Understanding these processes and how they might change in the future is critical for portraying robust regional sea level change.

 

Recently, new generations of climate models have been integrated at spatial resolutions of ¼° and 1/12°, which is sufficient to partially resolve the mesoscale eddy variability. These higher resolutions enable the study of the impact of mesoscale eddies on regional sea level changes and how these processes may change in the future.

 

In this work, we will take advantage of a suite of climate model simulations based on HadGEM3-GC3.1 at different spatial resolution (1°, ¼° and 1/12°) to assess the contribution of eddy-variability on regional sea level trends. We first present the ability of such climate models to reproduce regional sea level trends observed by satellite altimetry over decadal to multi-decadal time periods. Second, temperature and salt budget will be presented to quantify the contribution of eddy variability on these regional sea level trends.

How to cite: Laurent, B., Llovel, W., Treguier, A.-M., and Hochet, A.: Eddy variability contribution to decadal regional sea level trends, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8462, https://doi.org/10.5194/egusphere-egu24-8462, 2024.

EGU24-9008 | Posters on site | CL4.9

Sea-level projections in recent IPCC reports: how we got here, where we are and where we’re going  

Aimée Slangen, Matthew Palmer, Carolina Camargo, John Church, Tamsin Edwards, Tim Hermans, Helene Hewitt, Gregory Garner, Jonathan Gregory, Robert Kopp, Victor Malagon Santos, and Roderik van de Wal

Sea-level science has seen many recent developments in observations and modelling of the different contributions and the total mean sea-level change. Here, we focus on sea-level projections in the recent IPCC reports, and discuss (1) the evolution in IPCC projections (“how we got here”), (2) how the projections compare to observations (“where we are”) and (3) the outlook for further improving projections (“where we’re going”). We start by discussing how the model projections of 21st century sea-level change have changed from the IPCC AR5 report (2013) to SROCC (2019) and AR6 (2021), highlighting similarities and differences in the methodologies and comparing the global mean and regional projections. This shows that there is good agreement in the median values, but also highlights some differences. In addition, we discuss how the different reports included high-end projections. We then show how the AR5 projections (from 2007 onwards) compare against the observations, and find that they are highly consistent with each other. Finally, we discuss how to further improve sea-level projections in future studies.

How to cite: Slangen, A., Palmer, M., Camargo, C., Church, J., Edwards, T., Hermans, T., Hewitt, H., Garner, G., Gregory, J., Kopp, R., Malagon Santos, V., and van de Wal, R.: Sea-level projections in recent IPCC reports: how we got here, where we are and where we’re going , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9008, https://doi.org/10.5194/egusphere-egu24-9008, 2024.

EGU24-9762 | ECS | Orals | CL4.9

The interannual and decadal sea level variabilities over the Indo-Pacific Oceans in the Reanalysis and CMIP6 Historical Simulations and Projections 

Ponni Maya, José Antonio Álvarez Antolínez, Deepa Js, and Chellappan Gnanaseelan

In climatological research, understanding past and accurately simulating future sea level variability is paramount due to the considerable risk that sea level changes pose to low-lying regions, coupled with their significant influence on the occurrence and severity of extreme meteorological events  . This research insights are vital in evaluating the potential impact on renewable energy sources, particularly offshore wind, wave, and tidal energy, where changes in sea level can significantly alter the efficiency and viability of these energy converters. This study comprehensively analyses sea level variability on interannual and decadal scales in the Indo-Pacific region, integrating data from the Ocean Reanalysis System 5 (ORAS5), CMIP6 historical simulations spanning from 1850-2014, and future projections under the CMIP6 future intermediate emission scenario (rcp245/ssp245) for the period 2015 to 2100. Our investigation spans key areas such as the Northwest Central Pacific Ocean (NWCPO), the Eastern Equatorial Pacific Ocean (EEPO), and the Thermocline Ridge of the Indian Ocean (TRIO), among others.
We report findings on interannual and decadal Sea Level Anomaly (SLA) variability, especially highlighting the TRIO region and various Pacific Ocean zones such as the SWPO, NWCPO, EEPO, and NWNPO. Our study identifies a substantial increase in interannual variability in the NWNPO. We also observe consistent sea-level variability patterns across these regions, extending into future projections under moderate emission scenarios.
We find that the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole, and the Pacific Decadal Oscillation are key drivers of these variabilities. Our study reveals a strong connection between sea levels in the Equatorial Pacific and the Niño 3.4 index, suggesting its potential as a sea level-based indicator for El Niño and La Niña events.
Our research highlights the critical role of atmospheric forcing in driving sea level variability. We link high sea-level variability regions to significant wind stress curl anomalies, with distinct differences between hemispheres. We explore the mechanics of equatorial variability, emphasizing the role of equatorial Kelvin waves and local and remote Rossby waves in different oceanic regions.
Our study concludes that most CMIP6 models, despite large model uncertainty, predict an increase in sea level variability for the upcoming century, particularly in the Pacific Ocean, emphasizing the need for heightened attention to this dynamic region in the context of global climate change .

How to cite: Maya, P., Álvarez Antolínez, J. A., Js, D., and Gnanaseelan, C.: The interannual and decadal sea level variabilities over the Indo-Pacific Oceans in the Reanalysis and CMIP6 Historical Simulations and Projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9762, https://doi.org/10.5194/egusphere-egu24-9762, 2024.

EGU24-9936 | ECS | Posters on site | CL4.9

Linking the Permanent Service for Mean Sea Level’s (PSMSL) global mean sea level dataset to the ellipsoid  

Chanmi Kim, Andrew Matthews, and Elizabeth Bradshaw

The Permanent Service for Mean Sea Level (PSMSL) is the internationally recognised global sea level data bank for long term sea level change information from tide gauges, responsible for the collection, publication, analysis and interpretation of sea level data. The PSMSL was founded 90 years ago, and today operates from the Liverpool site of the UK’s National Oceanography Centre. 

The PSMSL’s main product, a dataset of monthly and annual means from over 2000 locations worldwide aggregated from over 200 suppliers, is a cornerstone in our understanding of changes in sea level over the two centuries. For our highest quality Revised Local Reference (RLR) dataset, we ensure the data can all be referred to a fixed point on land, ensuring a consistent vertical reference frame is used throughout the record. Also, we provide GNSS solutions near the guage to estimate the ellipsoidal height and rate of movement of the site in our website.

Here we introduce the PSMSL mean sea level dataset, and explain how we present these ellipsoidal ties on our website. We also discuss ongoing efforts to improve the breadth of metadata we supply, and attempts to ensure they meet FAIR data practices (Findable, Accessible, Interoperable and Reusable). 

 

How to cite: Kim, C., Matthews, A., and Bradshaw, E.: Linking the Permanent Service for Mean Sea Level’s (PSMSL) global mean sea level dataset to the ellipsoid , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9936, https://doi.org/10.5194/egusphere-egu24-9936, 2024.

EGU24-10137 | ECS | Posters on site | CL4.9

Reconstruction of the global ocean heat content and thermosteric sea-level rise with an improved configuration of the ISAS interpolation tool 

Rémy Asselot, Nicolas Kolodziejczyk, William Llovel, Kevin Balem, and Annaïg Prigent-Mazella

Anthropogenic greenhouse gas emissions have caused an imbalance in the energy content of the Earth's system, warming the atmosphere, the land surface, the cryosphere and the ocean. On a global scale, over the last five decades, the ocean has stored more than 90% of the heat excess associated with the Earth energy imbalance. This absorption of heat by the ocean leads to an increased Oceanic Heat Content (OHC). As the OHC rises, the global mean sea-level increases due to thermal expansion, a mechanism known as the global mean thermosteric sea-level (TSL) rise. In order to monitor accurately the global OHC and global mean TSL, one of the main sources of data is in situ Temperature and Salinity profiles. These profiles need to be interpolated on a regular grid to prevent any bias due to regional over or under-sampling. However, to date, OHC and TSL estimates and their associated uncertainties are sensitive to the parameterization and a priori assumption of the interpolation tools. To address this issue in a controlled framework, we run sensitive experiments where we adjust the configuration of the In Situ Analysis System (ISAS) interpolation tool. To do so, we extracted “synthetic profiles” of Temperature and Salinity from NEMO simulations, integrated over the 1980-2020 period.  We interpolated these profiles with ISAS and compared them with the original model outputs. This comparison allows us to improve the parameterization and a priori assumption of ISAS in order to, ultimately, provide a better understanding of the sensitivity of the global and regional OHC and TSL estimates. Here we present the first results of this work.

How to cite: Asselot, R., Kolodziejczyk, N., Llovel, W., Balem, K., and Prigent-Mazella, A.: Reconstruction of the global ocean heat content and thermosteric sea-level rise with an improved configuration of the ISAS interpolation tool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10137, https://doi.org/10.5194/egusphere-egu24-10137, 2024.

EGU24-10576 | ECS | Orals | CL4.9 | Highlight

Extreme sea-level projections along European coasts for climate adaptation services  

Maialen Irazoqui Apecechea, Angelique Melet, Guillaume Reffray, and Goneri Le Cozannet

Sea-level rise is one of the most hazardous climate-change impacts and is projected to trigger dramatic increases of coastal flooding frequency in Europe in the current century and beyond.  As such, adaptation-related effective decision making relies on the availability of authoritative and locally relevant information on future coastal sea-levels and their extremes, which include uncertainty quantification. However, current available sea-level projections are typically limited by either too low spatial resolution and therefore missing physical processes relevant at the coast, they account for only part of the sea-level signal (e.g. storm surges), and/or are typically limited to the downscaling of a single atmospheric model and therefore offer no quantification of the potentially significant inter-model uncertainty.   

In response to this knowledge gap, we present a novel extreme sea-level (ESL) projection dataset which focuses on the North-east Atlantic region. The dataset consists of a CMIP6-forced multi-model ensemble of downscaled projections until the end of the century, generated with a regional 3-dimensional ocean model at ~7km resolution. As such, the model captures not only storm-surge and tide induced ESLs, typically captured in barotropic 2-dimensional models, but also accounts for the contribution of circulation and density-driven modulations to extremes. Therefore, the ensemble dataset offers an excellent opportunity to explore ESL drivers at different spatio-temporal scales, their projected future changes, and associated uncertainties.

This dataset will help to advance scientific knowledge on climate-change induced coastal flood risk changes, but also to increase confidence in quantitative assessments of impacts of sea-level rise through its contribution to the Coastal Climate Core Service (CoCliCo), a decision-oriented platform which will inform users on present-day and future coastal risks, and which is currently under development as part of a European Union’s Horizon 2020 project.

The CoCliCo project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101003598

How to cite: Irazoqui Apecechea, M., Melet, A., Reffray, G., and Le Cozannet, G.: Extreme sea-level projections along European coasts for climate adaptation services , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10576, https://doi.org/10.5194/egusphere-egu24-10576, 2024.

EGU24-10716 | Posters on site | CL4.9 | Highlight

Exploring multi-century sea level rise commitments from 21st century cumulative emissions to inform minimum coastal adaptation needs 

Alexander Nauels, Zebedee Nicholls, Uta Klönne, Tim Hermans, Matthias Mengel, Christopher J. Smith, and Matthew D. Palmer

It is crucial to explore multi-century sea level responses under different emissions scenarios despite underlying physical uncertainties that rapidly increase over time, because resulting coastal risks fully manifest only on these longer timescales. Here, we use a set of climate and sea level emulators to investigate sea level rise commitments out to 2300 for cumulative emission levels at the start of every remaining 21st century decade under the five illustrative SSP-RCP scenarios. Our results indicate that emissions until 2030 “lock in” around 1.0 m (66% model range: 0.8 to 1.3 m) of global mean sea level rise in 2300 relative to 1995-2014. Under an intermediate emissions scenario roughly in line with current climate policies (SSP2-4.5), median 2300 global mean sea level commitments for cumulative emissions in 2050 (1.2 m) and 2100 (1.7 m) would be around 0.1 m and 0.6 m higher than under a very low emissions scenario (SSP1-1.9). Global results are also downscaled to selected regional sites and highlight that particularly vulnerable regions like low-lying Pacific Islands will experience higher local committed sea level rise than the global average. By attributing projected sea level rise commitments in 2300 to different cumulative emission levels in the 21st century, the study aims to more clearly link mitigation efforts in the near term to longer term coastal risk and to inform minimum adaptation requirements under different climate futures.

How to cite: Nauels, A., Nicholls, Z., Klönne, U., Hermans, T., Mengel, M., Smith, C. J., and Palmer, M. D.: Exploring multi-century sea level rise commitments from 21st century cumulative emissions to inform minimum coastal adaptation needs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10716, https://doi.org/10.5194/egusphere-egu24-10716, 2024.

EGU24-11869 | Orals | CL4.9

Relative sea level rise trends and projections up to 2150 along the Italian coasts: implications for coastal flooding 

Marco Anzidei, Antonio Vecchio, Tommaso Alberti, Enrico Serpelloni, and Anita Grezio

We focus on the current and future sea level (SL) trends along the Italian coasts which are affected by spatially variable rates of Vertical Land Movements (VLM) in response to tectonics and anthropic activities. Since VLM play a crucial role in local sea level rise along the coasts, they need to be estimated and incorporated in the analysis for more affordable sea level rise projections.

To estimate the current VLM rates we used geodetic data from about 27 years of continuous GNSS observations at a set of stations belonging to Euro-Mediterranean networks located within 5 km from the coast. Revised SL projections up to the year 2150 are provided at a set of points on a geographical grid and at the location of some tide gauges belonging to the PSMSL network, by including the estimated VLM in the SL projections released by the IPCC in the AR6 Report. Our results show that the current IPCC projections are not representative of the expected future sea levels since they do not properly consider the effects of tectonics and other local factors. Here we show that revised multi-temporal sea level projections at 2030-2050-2100 and 2150 show significant differences with respect to those of the IPCC for different Shared Socio-economic Pathways and global warming levels. Finally, our results indicate that about 1600 km of length and 10.000 km2 of the considered Italian coasts are yet exposed to flooding risk, with enhanced impacts on the environment, human activities and coastal infrastructures, in particular in 39 coastal plains. With the above scenarios, and especially in case of eventual instabilities of the Greenland and west Antarctica ice sheets, the effects of extreme meteorological events and tsunamis, will soon amplified along the Italian coasts, with serious concerns for main and small islands. Therefore, actions are needed to support vulnerable populations to adapt to the expected relative sea level rise by the end of this century and beyond.

How to cite: Anzidei, M., Vecchio, A., Alberti, T., Serpelloni, E., and Grezio, A.: Relative sea level rise trends and projections up to 2150 along the Italian coasts: implications for coastal flooding, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11869, https://doi.org/10.5194/egusphere-egu24-11869, 2024.

EGU24-13354 | ECS | Posters on site | CL4.9

GravIS Portal: User-friendly Ocean Bottom Pressure data from GRACE and GRACE-FO 

Christoph Dahle, Eva Boergens, Henryk Dobslaw, Ingo Sasgen, Thorben Döhne, Sven Reißland, and Frank Flechtner

The German Research Centre for Geosciences (GFZ), together with the Alfred-Wegener-Institute (AWI) and the Technische Universität Dresden, maintains the ‘Gravity Information Service’ portal (GravIS, gravis.gfz-potsdam.de). GravIS facilitates the dissemination of user-friendly data of mass variations in the Earth system, based on observations of the US-German satellite missions GRACE (Gravity Recovery and Climate Experiment, 2002-2017) and its successor GRACE-FO (GRACE Follow-On, since 2018).

The portal provides ocean bottom pressure (OBP) data on a global 1° grid. Two versions of the product are provided, based on spherical harmonic coefficients taken from either the most recent GRACE/GRACE-FO release from GFZ or from the International Combination Service for Time-variable Gravity Fields (COST-G). Corrections applied to the data include the insertion of estimates of the geocentre motion, replacement of the C20 and C30 coefficients, corrections of the co- and postseismic deformations after the three megathrust earthquakes (Sumatra-Andaman 2004, Chile 2010, Japan-Tohoku 2011), and the correction for glacial isostatic adjustment with the ICE-6G model.

The data product consists of barystatic sea-level pressures calculated from the gravity data using the sea-level equation. Residual ocean circulation is provided as well. Besides the gridded products, regional average time series are also available for predefined ocean regions.

In addition to the OBP data, GravIS provides terrestrial water storage (TWS) variations over the continents and ice mass variations over Greenland and Antarctica. These data sets are also provided either as grids or regional averages.

The data sets of all Earth system domains can be interactively displayed within the portal and are freely available for download. This contribution aims to show the features of the GravIS portal and its potential benefit to sea-level and ocean science applications.

How to cite: Dahle, C., Boergens, E., Dobslaw, H., Sasgen, I., Döhne, T., Reißland, S., and Flechtner, F.: GravIS Portal: User-friendly Ocean Bottom Pressure data from GRACE and GRACE-FO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13354, https://doi.org/10.5194/egusphere-egu24-13354, 2024.

EGU24-14249 | ECS | Posters on site | CL4.9

Mid-Holocene relative sea-level reconstruction from digital surface models of coral microatolls at Pulau Semakau, southwestern Singapore  

Lin Thu Aung, Nural Syafiqah Tan, Jennifer Susan Quye-Sawyer, Fangyi Tab, Junki Komori, Zihan Aw, Jing Ying Yeo, Wan Lin Neo, Maya Baltz, and Aron Maltzner

Coral microatolls are coral colonies that grow with distinct morphologies consisting of living polyps on their outer perimeters and dead upper surfaces with concentric rings in planform. Their upward growth is limited by the lowest tides, allowing them to be used as precise indicators of relative sea-level (RSL) change. Therefore, detailed morphological investigation of fossil microatolls provides an important proxy for the reconstruction of past RSL. We present a preliminary RSL reconstruction from Pulau Semakau (Semakau Island), southwestern Singapore, based on digital surface models (DSMs) of fossil corals captured by portable iPhone LiDAR integrated with field survey data and radiocarbon analysis. Pulau Semakau is the largest field site in Singapore, with an intertidal flat extending more than 2 km long by 0.4 km wide, on which we observed 79 living and 65 fossil microatolls containing well preserved, concentric rings. In this study, we reconstruct mid-Holocene RSL using seven fossil, Diploastrea heliopora microatolls, relative to living counterparts on the island. DSMs indicate that three of these fossil corals are lower in elevation at the center with higher outer rings, indicating gradual RSL rise between ~7700 and 7500 cal yr BP. Conversely, three fossil corals are observed to decrease in elevation from the innermost to outermost rings, indicative of RSL fall between ~7350 and 7200 cal yr BP. These observations are consistent with but more well constrained than the existing sea-level curve of Singapore based on sea-level index points (SLIPs) and limiting dates from intertidal mangrove and shallow marine sediments. RSL records between ~7500 and 7350 cal yr BP are largely uncertain due to erosion of a fossil coral, and this remains as future work. The initial results reflect mid-Holocene RSL fluctuations at Pulau Semakau, from ~7700 to 7200 cal yr BP.

How to cite: Aung, L. T., Tan, N. S., Quye-Sawyer, J. S., Tab, F., Komori, J., Aw, Z., Yeo, J. Y., Neo, W. L., Baltz, M., and Maltzner, A.: Mid-Holocene relative sea-level reconstruction from digital surface models of coral microatolls at Pulau Semakau, southwestern Singapore , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14249, https://doi.org/10.5194/egusphere-egu24-14249, 2024.

EGU24-14926 | ECS | Posters on site | CL4.9

Sea level projections for the German Coast 

Corinna Jensen, Frank Janssen, Jens Möller, and Tim Kruschke

Sea level rise is a certain consequence and one of the most important threats associated with climate change. It increases the risk of flooding of low-lying land at the German Coast.

In cooperation of the “Network of Experts” of the German Federal Ministry for Digital and Transport and the DAS core service “climate and water”, we aim to provide high-quality projections of relative sea level change for the German coastal areas, both in terms of spatial data as well as time series for specific stations. Most of the drivers for sea level change must be considered on a continental or global scale. The main exception for this in northern Europe is land uplift as its impacts are regional and dependent on glacial isostatic adjustment as well as local processes. We therefore created a new set of sea level projections for the North Sea and Baltic Region. This dataset is based on the IPCC 6th Assessment Report (AR6) projections of absolute sea level change, which we combine with a new and high-resolution land elevation model over Fennoscandia (instead of the coarse land elevation model for this region used in the IPCC AR6). The data will eventually be published via the “DAS core service”.

 

How to cite: Jensen, C., Janssen, F., Möller, J., and Kruschke, T.: Sea level projections for the German Coast, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14926, https://doi.org/10.5194/egusphere-egu24-14926, 2024.

EGU24-15877 | ECS | Posters on site | CL4.9 | Highlight

Regional variations in relative sea level changes influenced by non-linear vertical land motion  

Julius Oelsmann, Marta Marcos, Marcello Passaro, Laura Sanchez, Denise Dettmering, Sönke Dangendorf, and Florian Seitz

Vertical land movements can cause regional relative sea level changes to differ substantially from climate-driven absolute sea level changes. While absolute sea level has been accurately monitored by satellite altimetry since 1992, there are limited observations of vertical land motion. Vertical land motion is generally modeled as a linear process, despite some evidence of non-linear motion associated with tectonic activity, changes in surface loading, or groundwater extraction. As a result, the temporal evolution of vertical land motion, and its contribution to projected sea level rise and its uncertainty, remains unresolved. Here, we present a probabilistic vertical land motion reconstruction from 1995-2020 and determine the impact of regional scale and non-linear vertical land motion on relative sea level projections up to 2150. We show that regional variations in projected coastal sea level changes are equally influenced by vertical land motion and climate-driven processes, with vertical land motion causing relative sea level changes of up to 50 cm by 2150. Accounting for non-linear vertical land motion increases the uncertainty in projections by up to 1 m on a regional scale. Our results highlight the uncertainty in future coastal impacts and demonstrate the importance of including non-linear vertical land motions in sea level change projections. In addition to its application to regional sea level projections, the vertical land motion estimate is an important source of information for various sea level studies focusing on the analysis of tide gauge or satellite altimetry observations in coastal areas.

How to cite: Oelsmann, J., Marcos, M., Passaro, M., Sanchez, L., Dettmering, D., Dangendorf, S., and Seitz, F.: Regional variations in relative sea level changes influenced by non-linear vertical land motion , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15877, https://doi.org/10.5194/egusphere-egu24-15877, 2024.

EGU24-15948 | ECS | Posters on site | CL4.9

Drivers of Late Holocene relative sea-level change in the Sunda Shelf: new insights from coral microatolls in Singapore 

Fangyi Tan, Benjamin Horton, Ke Lin, Tanghua Li, Maeve Upton, Yucheng Lin, Jennifer Walker, Trina Ng, Jennifer Quye-Sawyer, Joanne TY Lim, Shi Jun Wee, Nurul Syafiqah Tan, and Aron Meltzner

Existing Late Holocene relative sea-level (RSL) records from the Sunda Shelf suffer from spatial and temporal discontinuities and/or a lack of precision, hindering an understanding of the drivers of RSL change. Here, we present the first RSL record from fossil coral microatolls in Singapore, which has high vertical (<± 0.20 m, 2𝜎) and temporal (<± 26 yrs, 95% highest density region) precision.

We applied a novel approach to produce sea-level index points and infer sea-level tendencies by combining (1) the use of photogrammetry with traditional levelling techniques; (2) 230Th dating; and (3) surface morphologies of the fossil coral microatolls. The fossil corals reveal a gradual, 0.31 ± 0.18 m (2𝜎) fall in RSL between 2.8 kyrs BP and 0.6 kyrs BP, with rates averaging 0.15 ± 0.10 mm/yr (2𝜎). Our coral record lies within uncertainty of some of the published RSL records from the region but disagrees with others, suggesting that local to regional processes may be driving spatial variability in RSL in the region. Misfits of the data with glacial isostatic adjustment (GIA) models may be explained by the influence of non-GIA processes, such as vertical land motion, and/or the need to fine-tune GIA model parameters. Work is ongoing to decompose the drivers of relative sea-level change within the region.

How to cite: Tan, F., Horton, B., Lin, K., Li, T., Upton, M., Lin, Y., Walker, J., Ng, T., Quye-Sawyer, J., Lim, J. T., Wee, S. J., Tan, N. S., and Meltzner, A.: Drivers of Late Holocene relative sea-level change in the Sunda Shelf: new insights from coral microatolls in Singapore, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15948, https://doi.org/10.5194/egusphere-egu24-15948, 2024.

EGU24-16146 | Posters on site | CL4.9

Spatially variable sea level response to erosion and deposition in Aotearoa New Zealand 

Gregory Ruetenik, John D. Jansen, and Ken L. Ferrier

Surface processes alter sea level by warping Earth’s surface and modifying the gravitational field. Recent studies show that paleo-sea level indicators are depressed by sedimentation near major depocenters, such as the Mississippi and Indus deltas, and raised by the erosion of rock in rapidly eroding coastal regions such as Taiwan. The South Island of Aotearoa New Zealand poses an interesting combination of these endmembers because the Southern Alps are eroding rapidly on the west coast, while high sediment loads are deposited along the eastern margin. Here, we use a global, gravitationally self-consistent sea-level model to demonstrate that sediment redistribution on the South Island drastically alters interpretations of sea level change since the Last Interglacial (Marine Isotope Stage 5e) by as much as +100 m on the west coast and –30 m on the east coast. The influence of sediment redistribution on sea level is highly sensitive to geodynamic properties such as effective elastic thickness, which we reconcile using the abundance of paleo-shoreline markers available.

How to cite: Ruetenik, G., Jansen, J. D., and Ferrier, K. L.: Spatially variable sea level response to erosion and deposition in Aotearoa New Zealand, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16146, https://doi.org/10.5194/egusphere-egu24-16146, 2024.

EGU24-16387 | Posters on site | CL4.9

Sea-level scenarios for coastal adaptation: the example of France 

Rémi Thiéblemont and Gonéri Le Cozannet

Climate change scenarios are a typical request of adaptation practioners. Within its third national adaptation plan, France is developing a consistent set of climate scenarios based on global warming levels. The scenario currently under consideration would lead to a global mean temperature increase of 3°C with respect to the preindustrial period, which is consistent with the current climate policies to 2100. Later on, these scenarios would be integrated in the regulation, for example in order to update risk assessment guidance.

Here, we present how sea-level rise scenarios aligned with this global warming level were produced. We selected emulated simulations for each component of future sea-level rise consistently, including ocean and ice components, following a method similar to that of the 6th assessment report of the IPCC, yet with specific attention to the consistency of uncertainty treatment before and after 2100. This responds to the needs to consider impacts of sea-level rise over hundred years, that is, to 2125 within coastal risk prevention plans. Furthermore, we added simulations considering a potential collapse of ice-sheets at 3°C of global warming levels in 2100. We consider only vertical land motions related to the Glacial Isostatic Adjustment as new observations from the Copernicus Land Motion service are now available for local stakeholder’s use.

The results show that the 87th percentile of projections is close to 80cm in 2100 with respect to 1995-2014 for the majority of mainland and overseas French regions, whether ice-sheets collapse is considered or not. Conversely, median values display differences of about 10cm depending whether ice sheet collapse is hypothesized or not. In the context of the development of these new scenarios, simplicity was considered a key criterion of success to ensure that all users - and not only those with high climate literacy - can effectively use scenarios. Hence, we propose to use one single scenario corresponding to the 87th percentile of the projections. This corresponds to a cautious approach consistent with the risk prevention policy in France. This does not preclude advanced users considering additional scenarios such as low-likelihood/high-impact scenarios voluntarily.

This work was performed within a project supported by the ministry in charge of Environment. We thank the steering and scientific committees of this project for useful comments and inputs.

How to cite: Thiéblemont, R. and Le Cozannet, G.: Sea-level scenarios for coastal adaptation: the example of France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16387, https://doi.org/10.5194/egusphere-egu24-16387, 2024.

EGU24-16743 | ECS | Posters on site | CL4.9

Inferring climatic sea-level variations from microatolls in tectonically active regions 

Sophie Debaecker, Mikhail Karpytchev, Mélanie Becker, Nathalie Feuillet, and Kenji Satake

Coral microatolls are often used to reconstruct the relative sea-level (RSL) along tropical coastlines. They grow at a constant rate, developing each year a growth band that can be observed in their internal stratigraphy. As their development is limited by the water height, they record annual variations of the relative sea-level once they have reached the sea surface. These changes are related to both climate and tectonic, and several criteria are used to decipher both signals. For example, it is commonly accepted that a local signal would rather correspond to a tectonic event, and inversely. However, majority of the criteria such as regrowth of the coral, amplitude of the RSL anomaly or matches with seismic or climatic events catalogs are mainly qualitative and most of the time, incomplete. In our study, we seek to develop a mathematically sound method to separate the climatic signal recorded by a series of microatolls. We focused on the region of the Ryukyus islands in south-west Japan, where the Philippine sea plate plunges under the Eurasia plate. In this area, up to 15 modern and living corals have been collected previously; and their RSL records extend from 1762 to 2018. They extend over 900 km along the subduction zone. Despite the seismic activity of the area, it is possible to infer that any signal common to all microatolls can be considered as climatic. We used a statistical method over the corals dataset to extract a common-mode RSL signal over the island arc. We found a long term sea-level rise for the last 200 years. We further analyze shorter time trends and annual anomalies, and compare our results from the RSL records that include years where only minimum RSL was recorded. Additionally, to refine our method we aim to compare sea level changes recorded by tide gauge in the Ryukyus with the estimates from inferred from the coral microatolls from seismically stable regions in the Pacific Ocean.

How to cite: Debaecker, S., Karpytchev, M., Becker, M., Feuillet, N., and Satake, K.: Inferring climatic sea-level variations from microatolls in tectonically active regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16743, https://doi.org/10.5194/egusphere-egu24-16743, 2024.

EGU24-17955 | ECS | Posters on site | CL4.9

Sea-level storylines to inform coastal adaptation planning and decision-making for the UK, South Africa and Southeast Asia 

Jennifer Weeks, Matthew D. Palmer, Benjamin P. Horton, Trina Ng, Susan M. Parnell, and Antony Payne

Implementing responses to sea-level rise requires accessible, credible and relevant sea-level information to facilitate effective use by practitioners and decision-makers. However, recent consultations have highlighted the need to better translate sea-level information to meet the physical and cultural diversity of decision-making and planning across the world. This includes communicating sea-level rise across a range of timescales, providing information tailored to different risk tolerances and better linking sea-level rise to impacts analysis to provide useful and usable metrics (e.g., Weeks et al., 2023, Environ. Res. Commun.). 


The presence of ambiguity in sea-level projections means there are limitations in the use of probabilistic approaches in coastal planning and decision-making (Kopp et al., 2023, Nature Climate Change). Storylines (physically consistent and plausible pathways of future climate events) are increasingly being used as a distillation tool presented alongside probabilistic sea level projections, for example to address the challenge of “deep uncertainty” associated with the future response of the ice sheets. Here, we focus on the regionalisation of sea-level projections into a set of discrete, actionable future pathways, to meet the needs of coastal adaptation planners and decision-makers. Building on the work of Palmer et al., (2020) (Earth’s Future), we generate a set of sea-level storylines for coastal city locations in the UK, South Africa and Southeast Asia, constrained by different emissions scenarios and high-end sea-level rise estimates. Locations are chosen based on their population density and geographical spread, whilst the regions allow consideration of the different risk profiles and contexts for decision-making. This work explores a range of decision-making contexts and how the storyline framework can be tailored to different user needs. 

How to cite: Weeks, J., Palmer, M. D., Horton, B. P., Ng, T., Parnell, S. M., and Payne, A.: Sea-level storylines to inform coastal adaptation planning and decision-making for the UK, South Africa and Southeast Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17955, https://doi.org/10.5194/egusphere-egu24-17955, 2024.

EGU24-18361 | Orals | CL4.9

New sea level scenarios for the Netherlands 

Sybren S. Drijfhout, Dewi Le Bars, and Iris Keizer

We present the framework used to develop a new set of sea level scenarios for the Dutch coast published by KNMI in October 2023, to help the Netherlands adapt to sea level rise. Based on interactions with stakeholders, the development of the scenarios focused on two main areas: the connection between observations and projections and the development of low-likelihood high-impact scenarios up to 2300. We developed a local sea level budget for the period 1993-2021 to better understand past observations and to constrain the scenarios. In particular, the contribution of Ocean Dynamic Sea Level was important in the benchmark period 1993-2021, and observational evidence was used to select CMIP6 models that were close to the observations. For the low-likelihood high-impact scenarios three lines of evidence were used: structured expert judgement, a numerical model including Marine Ice Cliff Instability, and a physical evidence discussion. We also discuss some practical applications of these scenarios.

How to cite: Drijfhout, S. S., Le Bars, D., and Keizer, I.: New sea level scenarios for the Netherlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18361, https://doi.org/10.5194/egusphere-egu24-18361, 2024.

EGU24-18660 | ECS | Orals | CL4.9

Understanding the Regional Disparity of the Sea Level Rise during Altimetry Era 

Rong Deng and Wenjie Dong

The application of satellite altimetry allows us to acquire global sea level height data with higher spatial and temporal resolution, enabling a systematic understanding of spatial differences in sea level rise. In our study, we reconstructed the barystatic sea level and steric sea level change during the altimetry era (1993-2022). This involved utilizing mass change data and ocean heat content data from various sources. Notably, we incorporated the latest observation and model-simulation data, ensuring coverage of the entire altimetry era compared with previous reconstructions. Based on altimetry-observed relative sea level change, the global sea level rise rate is 3.38 [3.09 3.68] mm/yr, the global barystatic and steric sea level change is 1.80 [1.45 2.15] mm/my, and 1.02 [0.67 1.37] mm/yr, respectively. Subsequently, we further analyzed the regional characteristics of these sea level rises.

Over the past three decades, sea levels have exhibited a faster rate of increase in the western basins, as well as in the equatorial and mid-latitude region, surpassing the global average. Conversely, sea level rise at higher latitudes has been relatively slower than the global average. In the mid-low latitude regions, the higher rate of sea level rise is primarily dominated by the expansion of ocean water due to its heating. In high-latitude regions, the lower sea level rise rate is primarily attributed to the far-field effects of the melting of land ice. The distribution of halosteric sea level changes is nearly uniform across latitudes. However, in the western Atlantic, a significant counteracting effect against the rise in thermosteric sea level is observed. This is linked to the weakening Atlantic Meridional Overturning Circulation (AMOC).

Furthermore, we selected 8 regions, North Pacific (NP), South China Sea (SCS), Western Tropical Pacific (WTP), Bay of Bengal (BOB), Tropical Indian Ocean (TIO), Southwest Pacific (SWP), Gulf of Mexico (GOM), and North Atlantic (NA), with sea level rise rates faster than the global average. We analyzed the contributions of different components to the sea level rise in these areas. These regions are all adjacent to land or have a significant number of islands, the faster sea level rise poses a greater threat to the corresponding coastal areas. The contributions of barystatic and steric sea level components are approximately equal in most of these regions. However, in SCS and GOM, the contributions of the barystatic component exceed 60%. The halosteric sea level has a significant negative contribution to the sea level rise in the GOM and NA. The Antarctic Ice Sheet and Greenland Ice Sheet melting contribute to sea level rise in these regions by less than 15%, and more than 15%, respectively. The highest contribution of glacier melting is in the SCS, approximately 23%. Compared to the melting of land ice, changes in land water contribute limitedly to sea level rise in these regions. The contribution is less than 10%, except for in NA.

How to cite: Deng, R. and Dong, W.: Understanding the Regional Disparity of the Sea Level Rise during Altimetry Era, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18660, https://doi.org/10.5194/egusphere-egu24-18660, 2024.

EGU24-18693 | ECS | Posters on site | CL4.9

Loss of safe land on atolls highlights need for immediate emissions reductions to support coastal adaptation 

Tessa Möller, Rosanne Martyr-Koller, Scott Kulp, Tabea Lissner, Benjamin H Strauss, Zebedee Nicholls, and Alexander Nauels

The impacts of climate change and sea level rise are posing substantial threats to the long-term habitability of low-lying atolls. As of today, the sparse data coverage of these islands limits the ability to assess and respond to climate change related risks.

Advances in coastal digital elevation models provide data for very remote coastal regions with low vertical bias. Here, we combine the Intergovernmental Panel on Climate Change regional sea level rise projections under its illustrative emissions scenarios, with the coastal digital elevation model CoastalDEM and COAST-RP, a dataset of storm tide return periods to assess the exposure to rising sea levels and coastal flooding of 166 atolls. Our results show that in 2050 and under a very low emissions scenario (SSP1-1.9), atoll area exposure to SLR and coastal flooding will amount to 35% [34-36%] and that only 64% of atoll area can still be considered safe. By the end of century and under the same scenario, only 61% can be considered safe. Under an intermediate emissions scenario (SSP2-4.5), a scenario roughly capturing projected warming under current policies and actions, the share of safe land further reduces to 58% by 2100. By 2150, only 58% or 51% of the land can still be considered safe under the very low and intermediate emissions scenario respectively. Our results show that the habitability of atolls is already threatened in the near future, but that near-term mitigation can limit the pace at which atolls are flooded in particular beyond 2100. Our results imply that in addition to immediate and rapid emission reductions in line with the Paris Agreement, remaining adaptation options must be enabled and implemented today to reduce the future exposure of atolls.

How to cite: Möller, T., Martyr-Koller, R., Kulp, S., Lissner, T., Strauss, B. H., Nicholls, Z., and Nauels, A.: Loss of safe land on atolls highlights need for immediate emissions reductions to support coastal adaptation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18693, https://doi.org/10.5194/egusphere-egu24-18693, 2024.

Future sea-level rise on shallow continental shelves differs in one important aspect from open ocean sea-level rise: the local steric effect, that is the change in the water column height due to changes in sea water density, plays a minor role compared to the much deeper open ocean. Instead, the bulk of oceanic sea-level rise on continental shelves arises from an increase in ocean water mass that is being imported from the open ocean – the so-called shelf mass loading (SML). This redistribution is mainly driven by thermal expansion of water masses below shelf depth and magnifies as the subsurface ocean layers continue to warm.

 

Few studies have tried to detect SML as the signal is only expected to become dominant over decadal to multidecadal periods given the large natural variability in shallow regions.

Here, we combine hydrographic data from a section crossing the Norwegian shelf, with observations of total sea-level change from altimetry and estimates of mass changes from GRACE gravity missions to estimate the strength of SML over the past decades. We compare the residual of total sea level (from altimetry) and steric height (from hydrography) with GRACE estimates from three different solutions. Over the common period (2002 -2020), both estimates show a consistently higher trend over the shallow shelf area compared to the deep ocean. We estimate the shelf mass contribution in the order of 0.5 – 1.0 mm/yr, depending on the GRACE solution selected.

How to cite: Richter, K., Mangini, F., Bonaduce, A., and Raj, R.: Estimating the long-term sea-level contribution from shelf mass loading on the Norwegian shelf using hydrographic in-situ data, satellite altimetry and GRACE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19016, https://doi.org/10.5194/egusphere-egu24-19016, 2024.

EGU24-19452 | Posters on site | CL4.9

The barystatic contribution to multi-decadal sea-level change in the 19th century. 

Luke Jackson, Sophie Williams, Fiona Hibbert, Sönke Dangendorf, Ed Garrett, Andrew Sole, and Roland Gehrels

Understanding long-term trends in mass loss is vital for assessing the (in)stability of ice sheets and glaciers and their subsequent contribution to global mean sea level. Observational estimates of mass loss from the Greenland and Antarctic Ice Sheets are scarce before the satellite era (i.e., 1990s), and from glaciers before the 1950s. A variety of modelling techniques (process-driven and statistical) have been employed to synthesise and extend observational estimates, so that much of the 20th century sea-level budget is closed within uncertainty. Despite this work, uncertainty remains, particularly for contributions prior to ~1940 and the 19th century. 

Sea-level fingerprinting exploits the fact that the geometry of land-based water masses (i.e., ice sheets, glaciers, hydrological storage) and any changes (via loss or gain) will generate a unique gravitational equipotential surface (fingerprint). We apply this technique in a Monte-Carlo-based linear inversion model to isolate the globally averaged barystatic contribution from Greenland, Antarctica and glaciers over pentadal periods since 1813. We use a selection of long-duration tide gauges and high-resolution proxy-based sea-level reconstructions, with model-based glacio-isostatic adjustment (GIA), stero-dynamic, and terrestrial water storage corrections. 

Our initial findings confirm the validity of the approach when comparing barystatic contributions to observed estimates for the last 50 years. Whilst uncertainty is significant for the 19th century, the barystatic contribution deviates from zero in different pentads. We also conduct a sensitivity analysis to evaluate the idealised locations/corrections required to enhance confidence in the inversion procedure.

How to cite: Jackson, L., Williams, S., Hibbert, F., Dangendorf, S., Garrett, E., Sole, A., and Gehrels, R.: The barystatic contribution to multi-decadal sea-level change in the 19th century., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19452, https://doi.org/10.5194/egusphere-egu24-19452, 2024.

EGU24-19505 | Orals | CL4.9

Progress in the Global Sea Level Fingerprints since the 20th century 

Yuxin Liu, Shanshan Deng, Wenxi Zhang, and Ange Hu

Ocean mass change is the primary driver of sea level rise. Understanding the mechanisms of mass sea level change can help coastal areas scientifically respond to climate change. Under combined the self-attraction and loading effect and the Earth's rotational feedback, land-source freshwater input leads to global spatiotemporal heterogeneity of mass sea level, known as Sea Level Fingerprints. In this study, Sea Level Fingerprints were simulated under three different scenarios, covering periods from January 1901 to July 2019, January 1981 to June 2020, and July 1979 to June 2020. These scenarios encompassed: (1) consideration of climate variability alone; (2) consideration of both climate variability and actual glacial mass balance; and (3) alignment with recent climate change trends. The study aimed to analyze the contribution of Sea Level Fingerprints to satellite-derived mass sea level across these three scenarios. Results showed that in all three scenarios, the significant seasonal amplitude regions include the South China Sea and the Bay of Bengal, with peak values ranging from 42.60 to 45.20 mm. Changes in mass sea level are primarily caused by climate variability. Sea Level Fingerprints, which considered only precipitation and temperature as key indicators of climate variability, best reproduced the variation signal of the GRACE-derived data and the Altimetry-derived mass component. The spatial similarity coefficient derived between their global change range distributions were 0.67 and 0.87, respectively. Sea Level Fingerprints, which additionally considered glacial mass balance, provided a more accurate depiction of the spatial distribution and long-term trend of mass sea level derived from Altimetry satellites and Argo systems. This was demonstrated by the similarity between the sea-level fingerprints and altimetry-derived mass components across global long-term trend distribution patterns, with a spatial similarity coefficient of 0.75. The main contributing regions to these patterns include the Greenland Ice Sheet, Alaska, the Southern Andes, the Caucasus, the Middle East, and West Antarctica.

How to cite: Liu, Y., Deng, S., Zhang, W., and Hu, A.: Progress in the Global Sea Level Fingerprints since the 20th century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19505, https://doi.org/10.5194/egusphere-egu24-19505, 2024.

EGU24-20096 | ECS | Orals | CL4.9

Attributing low-frequency variations in ocean water mass redistribution during 2002-2020 

Shanshan Deng, Yuxin Liu, Wenxi Zhang, and Ange Hu

Studying how ocean water mass is redistributed can help with a better understanding of the regional sea level change. This study investigates the roles of the different physical processes involved in low-frequency ocean water mass, including the sea level fingerprint and the dynamic ocean mass change, from regional to global scales over the period 2004-2021. Global water mass redistribution data from the GRACE and GRACE-FO satellites were used, as well as surface wind and sea surface temperature data from the ERA5 reanalysis. The sea-level equation is used to simulate the sea level fingerprint, and the maximum covariance analysis is used to extract possible signals of the wind-forcing and temperature-gradient-forcing ocean mass redistribution. The results show that the low-frequency ocean water mass is dominated by the long-term trend and the decadal-like fluctuation. Sea level fingerprint significantly contributes to the open ocean. Compared with temperature gradients, wind forcing plays a more important role in dynamic ocean mass redistribution. The wind-forcing dynamic processes significantly drive the anomalies near the North Indian Ocean, North Atlantic Ocean, South Pacific Ocean, and some marginal seas. After removing the sea level fingerprint and ocean dynamics, some non-negligible noise, located in seismic zones, was also found, suggesting the misestimation of seafloor deformation resulting from earthquakes in the GRACE/GRACE-FO data processing. These findings may improve our understanding of the long-term anomalies in regional and global sea levels.

How to cite: Deng, S., Liu, Y., Zhang, W., and Hu, A.: Attributing low-frequency variations in ocean water mass redistribution during 2002-2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20096, https://doi.org/10.5194/egusphere-egu24-20096, 2024.

EGU24-21090 | ECS | Orals | CL4.9

Fast recovery of North Atlantic sea level in response to atmospheric CO2 removal 

Sunhee Wang, Yechul Shin, Ji-Hoon Oh, and Jong-Seong Kug

Human-induced increases in atmospheric carbon dioxide (CO2) cause global warming, which leads global mean sea level rise. Previous research has shown that even with the reduction or removal of atmospheric CO2, the global mean sea level will not return to its initial level. However, the regional effects of reducing or removing atmospheric CO2 on sea level change have not been extensively studied. In this study, we analyzed global and regional sea level changes over a 560-year period, including 140 years of a linear increase in atmospheric CO2 of 1% per year, followed by 140 years of a linear decrease, and finally 280 years of maintenance at pre-industrial CO2 levels. Our analysis showed that the sea level in the North Atlantic region increased rapidly relative to the global mean, and then recovered rapidly. We attribute these variations to fluctuations in the Atlantic Meridional Overturning Circulation (AMOC). As the AMOC weakened, heat and salt were trapped in the lower latitudes of the North Atlantic region, resulting in a slower transfer of these elements to higher latitudes. As the AMOC recovered and overshoot, the accumulated heat and salt were rapidly transferred to higher latitudes, resulting in changes in sea level. Our results suggest that the North Atlantic region is more sensitive to changes in atmospheric CO2 compared to the global mean. The North Atlantic region has a high population density and is expected to suffer significant damage as a result of sea level change. Therefore, continuous research on sea level change in this region is needed, and our study could help improve the ability to predict future sea level change in this area.

How to cite: Wang, S., Shin, Y., Oh, J.-H., and Kug, J.-S.: Fast recovery of North Atlantic sea level in response to atmospheric CO2 removal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21090, https://doi.org/10.5194/egusphere-egu24-21090, 2024.

EGU24-21107 | ECS | Orals | CL4.9

The defining roles of sterodynamic sea level in future climate projections 

Jan-Erik Tesdal, John Krasting, Robert Kopp, Praveen Kumar, Stephen Griffies, and William Sweet

Our ability to characterize and quantify the complex uncertainties surrounding future sea-level changes is crucial for coastal risk assessments and adaptation strategies. This study focuses on the role of steric and dynamic changes (i.e., sterodynamics) in sea level projections, particularly regarding their contribution to the uncertainty of global and regional sea level changes in relation to other components such as ice sheet dynamics. A probabilistic framework is used to estimate probability distributions of sea-level change for each component. Through variance decomposition, the total uncertainty in sea-level change is dissected into its constituent sources. Subsequently, the relative contribution of sterodynamics uncertainty is quantified across various regions, time frames, emission scenarios, and projection methodologies utilized to estimate future sea-level distributions. The contribution of sterodynamics to overall uncertainty reduces over time as the contribution from ice sheets becomes more pronounced. The spatiotemporal pattern of sterodynamic significance is not strongly dependent on future greenhouse gas emissions, yet its overall role is highly dependent on the representation (e.g., emulation) of ice sheets. When high-end, low-probability estimates of future Antarctic ice sheet contributions are excluded, sterodynamics remain a dominant source of regional sea-level uncertainty at the end of this century, particularly along the US East Coast and European coast. These regions are also identified as hotspots for future sea-level rise, indicating that sterodynamic processes will play a significant role in assessing coastal vulnerabilities there. This study suggests that ocean model development can most effectively reduce the overall uncertainty in future sea-level projections by focusing on these areas.

How to cite: Tesdal, J.-E., Krasting, J., Kopp, R., Kumar, P., Griffies, S., and Sweet, W.: The defining roles of sterodynamic sea level in future climate projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21107, https://doi.org/10.5194/egusphere-egu24-21107, 2024.

EGU24-995 | ECS | Posters on site | CL4.10 | Highlight

Assessing the predictability of Euro-Mediterranean droughts through seasonal forecasts 

Thomas Dal Monte, Andrea Alessandri, Annalisa Cherchi, and Marco Gaetani

Droughts are characterized by prolonged and severe deficits in precipitation that can extend in time, over a season, a year or more. They are confined to specific climatic zones but can manifest in both high and low rainfall regions. Contributing factors include temperatures, strong winds, low relative humidity, and the characteristics of rainfall. Drought events are characterized through indices that can be categorized based on the specific impacts they are associated with, such as meteorological, agricultural, or hydrological effects. Using such indices for drought characterization serves multiple purposes, including detection, assessment, and representation of drought conditions within a particular region. Seasonal precipitatio is essential for social and economic development and activities, hence. Reliable seasonal forecasts, especially regarding extreme precipitation events, become crucial for sectors like agriculture and insurance. Europe, and in particular the Mediterranean region, is expected to be considerably affected under climate change. The northern regions are anticipated to exhibit higher variability, increasing the risk of floods, while the southern areas may face decreased rainfall, prolonged dry spells, and intensified evaporation, potentially leading to more frequent drought occurrences.

This research aims to evaluate the prediction skill for extreme drought events at the seasonal time-scale using the SPI and SPEI indices over the EURO-Mediterranean area. The use of SPEI also takes into account the effect of temperature on the water balance, given by the calculation of potential evapotranspiration within it, which can be crucial in a context of global warming. We consider the seasonal forecasts provided by the Copernicus multi-system and we use the Brier Skill Score metric for the assessment of the performance. The objective is to understand potential predictability factors of these indices within the study area. The results show a positive performance for most of the areas examined, between 60 and 80 percent of the entire area for both indices. This led us to investigate possible optimization strategies to increase the skill in the area.

Using the multi-model approach we optimize the prediction skill obtaining considerable performance in forecasting drought conditions. Different multi-model strategies are compared, including the selection or aggregation of available forecasts to achieve the best overall performance in the area. We show that multi-model optimization can indeed provide valuable probabilistic predictions of seasonal drought events in many areas of the Euro-Mediterranean that could be useful for the decision-making process of the affected end users.

How to cite: Dal Monte, T., Alessandri, A., Cherchi, A., and Gaetani, M.: Assessing the predictability of Euro-Mediterranean droughts through seasonal forecasts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-995, https://doi.org/10.5194/egusphere-egu24-995, 2024.

EGU24-1120 | ECS | Orals | CL4.10

Effects of the realistic vegetation cover representation on the large-scale circulation and predictions at decadal time scale. 

Emanuele Di Carlo, Andrea Alessandri, Fransje van Oorschot, Annalisa Cherchi, Susanna Corti, Giampaolo Balsamo, Souhail Boussetta, and Timothy Stockdale

Vegetation is a highly dynamic component of the Earth System. Vegetation plays a significant role in influencing the general circulation of the atmosphere through various processes. It controls land surface roughness, albedo, evapotranspiration and sensible heat exchanges among other effects. Understanding the interactions between vegetation and the atmosphere is crucial for predicting climate and weather patterns. This study explores how better representation of vegetation dynamics affects climate predictions at decadal timescale and how surface characteristics linked to vegetation affect the general circulation at local, regional and global scales. We used the latest satellite datasets of vegetation characteristics and developed a new and improved parameterization for effective vegetation cover. We implemented the new parameterization in the land surface scheme Hydrology Tiled ECMWF Scheme for Surface Exchanges over Land (HTESSEL), which is embedded in the EC-Earth model. 

The enhancement of the model's vegetation variability significantly improves the prediction skill of the model for several parameters, encompassing both surface and upper-level elements such as 2-metre temperature, zonal wind at 850 hPa and mean sea level pressure. The improvement is particularly evident over Euro-Asian Boreal forests. In particular, a large-scale effect on circulation emerges from the region with the most 2-metre temperature improvement, over Eastern Europe. 

The incorporation of an effective vegetation cover also introduces heightened realism in surface roughness and albedo variability. This, in turn, leads to a more accurate representation of the land-atmosphere interactions. The regression analysis of surface roughness and albedo with 2-metre temperature, mean sea level pressure and wind (both at surface and 850 hPa) reveals a robust relationship across the entire northern hemisphere. This relation between the surface and the atmosphere is notably absent in the standard configuration model, where the vegetation is prescribed by a dynamical vegetation module.

These findings underscore the substantial impact of vegetation cover on the general circulation, particularly in the northern hemisphere, and emphasise its crucial role in improving prediction skills. Furthermore, they highlight the challenges faced by modern earth system models in accurately representing several processes connecting the land surface and the atmosphere.

How to cite: Di Carlo, E., Alessandri, A., van Oorschot, F., Cherchi, A., Corti, S., Balsamo, G., Boussetta, S., and Stockdale, T.: Effects of the realistic vegetation cover representation on the large-scale circulation and predictions at decadal time scale., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1120, https://doi.org/10.5194/egusphere-egu24-1120, 2024.

EGU24-1407 | ECS | Posters on site | CL4.10 | Highlight

Time Lag and Cumulative Effects of Extreme Climate on Coastal Vegetation in China 

Dong Tong and Dahai Liu

Rapid global changes are altering regional hydrothermal conditions, especially in ecologically vulnerable regions such as coastal areas of China. The response of vegetation growth to extreme climates and the time lag-accumulation relationship still require further exploration. We characterize the vegetation growth status by solar-induced chlorophyll fluorescence (SIF), analyzed the vegetation dynamic in coastal areas of China from 2000 to 2019, also explored the spatiotemporal pattern of vegetation, and assessed the response of vegetation to extreme climate in term of time lag-accumulation by combines gradual analysis and abrupt analysis. The results showed that (1) Coastal areas of China were sensitive to global climate change, with extreme high temperatures and extreme precipitation increasing from 2000 to 2019, and the warming in high latitudes was greater than in low latitudes, while the increase in precipitation was concentrated in the southern regions, which are already water-rich. (2) The vegetation in coastal areas of China improved significantly, with gradual analysis showed that the vegetation improvement area accounts for 94.12% of the study area, and the abrupt analysis showed that the majority (69.78%) of the vegetation change types were "monotonic increase", with 11.77% showing "increase with negative break" and 9.48% "increases to decreases." (3) Significant lag-accumulation relationships were observed between vegetation and extreme climate in coastal areas of China, and the time-accumulation effects was stronger than time-lag effects. The accumulation time of extreme temperatures was typically less than one month, and the accumulation time of extreme precipitation was 2-3 months. These findings contribute to filling gaps in understanding the time lag-accumulation effects of extreme climates on vegetation in sensitive coastal regions. It provides a foundational basis for predicting the growth trend of coastal vegetation, environmental changes and ecosystem evolution, which is essential for a comprehensive assessment of coastal ecological security.

How to cite: Tong, D. and Liu, D.: Time Lag and Cumulative Effects of Extreme Climate on Coastal Vegetation in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1407, https://doi.org/10.5194/egusphere-egu24-1407, 2024.

EGU24-3134 | Orals | CL4.10

Decadal predictability of seasonal temperature distriubutions 

André Düsterhus and Sebastian Brune

Climate predictions focus regularly on the predictability of single values, like means or extremes. While these information offer important insight into the quality of a prediction system, some stakeholders might be interested in the predictability of the full underlying distribution. These allow beside evaluating the amplitude of an extreme also to estimate their frequency. Especially on decadal time scales, where we verify multiple lead years at a time, the prediction quality of full distributions may offer in some applications important additional value.

In this study we investigate the predictability of the seasonal daily 2m-temperature on time scales of up to ten lead years within the MPI-ESM decadal prediction system. We compare yearly initialised hindcast simulations from 1960 onwards against estimates for climatology and uninitialised historical simulations. To verify the predictions we demonstrate a novel approach based on the non-parametric comparison of distributions with the integrated quadratic distance (IQD).

We show that the initialised prediction system has advantages in particular in the North Atlantic area and allow so to make reliable predictions for the whole temperature distribution for two to ten years ahead. It also demonstrates that the capability of initialised climate predictions to predict the temperature distribution depends on the season. Finally, we will also discuss potential opportunities and pitfalls of such approaches.

How to cite: Düsterhus, A. and Brune, S.: Decadal predictability of seasonal temperature distriubutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3134, https://doi.org/10.5194/egusphere-egu24-3134, 2024.

EGU24-3274 | ECS | Orals | CL4.10

 A Multi-year Climate Prediction System Based on CESM2 

Yong-Yub Kim, June-Yi Lee, Axel Timmermann, Yoshimitsu Chikamoto, Sun-Seon Lee, Eun Young Kwon, Wonsun Park, Nahid A. Hasan, Ingo Bethke, Filippa Fransner, Alexia Karwat, and Abhinav R.Subrahmanian

Here we present a new seasonal-to-multiyear earth system prediction system which is based on the Community Earth System Model version 2 (CESM2) in 1° horizontal resolution. A 20- member ensemble of temperature and salinity anomaly assimilation runs serves as the initial condition for 5-year forecasts. Initialized on January 1st of every year, the CESM2 predictions exhibit only weak climate drift and coupling shocks, allowing us to identify sources of multiyear predictability. To differentiate the effects of external forcing and natural climate variability on longer-term predictability, we analyze anomalies calculated relative to the 50-member ensemble mean of the CESM2 large ensemble. In this presentation we will quantify the extent to which marine biogeochemical variables are constrained by physical conditions. This analysis provides crucial insights into error growth of phytoplankton and the resulting limitations for multiyear predictability.

How to cite: Kim, Y.-Y., Lee, J.-Y., Timmermann, A., Chikamoto, Y., Lee, S.-S., Kwon, E. Y., Park, W., A. Hasan, N., Bethke, I., Fransner, F., Karwat, A., and R.Subrahmanian, A.:  A Multi-year Climate Prediction System Based on CESM2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3274, https://doi.org/10.5194/egusphere-egu24-3274, 2024.

EGU24-4083 | Posters virtual | CL4.10 | Highlight

Enhancing Subseasonal Climate Predictions through Dynamical Downscaling: A Case Study in the Southern Plains of the United States 

Yoshimitsu Chikamoto, Hsin-I Chang, Simon Wang, Christopher Castro, Matthew LaPlante, Bayu Risanto, Xingying Huang, and Patrick Bunn

Predicting extreme precipitation events at subseasonal timescales is a critical challenge in Earth system science. This study advances climate predictability by employing dynamical downscaling, specifically focusing on convection-permitting modeling in the Southern Plains of the United States. Two contrasting extreme precipitation periods in Texas, the extremely dry May of 2011 and the abnormally wet May of 2015, were selected for analysis. To enhance subseasonal climate forecasting, we integrated the Weather Research and Forecasting (WRF) model with the decadal climate prediction system based on the Community Earth System Model (CESM). Evaluating the impact of dynamical downscaling on the prediction of extreme precipitation events, our study demonstrates how high-resolution downscaling enhances model skill in capturing these events. The findings hold the potential to significantly contribute to improving climate predictions and assessing regional climate-related risks, aligning with the session's goals.

How to cite: Chikamoto, Y., Chang, H.-I., Wang, S., Castro, C., LaPlante, M., Risanto, B., Huang, X., and Bunn, P.: Enhancing Subseasonal Climate Predictions through Dynamical Downscaling: A Case Study in the Southern Plains of the United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4083, https://doi.org/10.5194/egusphere-egu24-4083, 2024.

Accurate seasonal streamflow forecasts (SSF) are crucial for disaster prevention, water management, agriculture, and hydropower generation. A global approach becomes imperative in regions lacking forecast systems. The Météo-France seasonal prediction system (MF System 8 - SYS8), contributing to Copernicus Climate Change Services (C3S), employs a fully coupled Atmosphere-Ocean General Circulation Model (AOGCM) with an advanced river routing component (CTRIP) interacting with the ISBA land-surface scheme. This study evaluates the skill of the SYS8 global SSF through hindcast river discharges. This work is part of the European project CERISE, which aims to enhance the C3S seasonal forecast portfolio by improving land initialisation methodologies.

SYS8 derives land initial conditions from a historical initialisation run where land (such as soil moisture and river discharges) is weakly constrained, contrasting with the atmosphere and ocean counterparts, which are nudged to the ERA5 and GLORYS re-analysis. This study improves the initialisation run by relaxing soil moisture to fields reconstructed from an offline land simulation.  Daily streamflow ensemble hindcasts of 25 members are generated in a  0.5° grid, with a lead time of up to 4 months initialised on the first day of May and August between 1993-2017. May and August initialisations allow forecasting of summer (JJA) and fall (SON) seasons. Actual forecast skill is assessed against streamflow observations in 1608 monitored basins worldwide (with areas > 3000 km2) using deterministic and probabilistic metrics. The classical Ensemble Streamflow Prediction approach (ESP) serves as a benchmark to evaluate the control SYS8 SSF skill and the additional skill of soil moisture nudging.

Globally, hindcast skill improves with enhanced land-surface initial conditions, especially during summer. Lower latitudes (<50°N) exhibit increased skill, while higher and cooler latitudes may lead to overestimated streamflow magnitude and oscillation amplitude due to soil moisture constraints. Local skill degradation will be discussed. Still, positive results support ongoing efforts to enhance land initialisation through a global land data assimilation system.

How to cite: Narváez, G. and Ardilouze, C.: Global Streamflow Seasonal Forecasts: Impact of soil moisture initialization in a novel two-way AOGCM-River Routing coupling approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5484, https://doi.org/10.5194/egusphere-egu24-5484, 2024.

EGU24-6494 | Posters virtual | CL4.10 | Highlight

Seasonal predictions of summer humid heat extremes in the southeastern United States driven by sea surface temperatures 

Liwei Jia, Thomas Delworth, and Xiaosong Yang

Humid heat extreme (HHE) is a type of compound extreme weather event that poses severe risks to human health. Skillful forecasts of humid heat extremes months in advance are essential for developing strategies to help communities build more resilience to the risks associated with extreme events. This study demonstrates that the frequency of summertime HHE in the southeastern United States (SEUS) can be skillfully predicted 0-1 months in advance in the SPEAR (Seamless system for Prediction and EArth system Research) seasonal forecast system. The sea surface temperature (SST) at the tropical North Atlantic (TNA) basin is found as the primary driver of the prediction skill. The responses of large-scale atmospheric circulation and winds to anomalous warm SSTs in TNA favor the heat and moisture flux transported from the gulf of Mexico to the SEUS. This research demonstrates the role of slowly-varying sea surface conditions in modifying large-scale environments that contribute to the predictions of HHE in SEUS. The results are potentially applicable for developing early warning systems of HHE. 

How to cite: Jia, L., Delworth, T., and Yang, X.: Seasonal predictions of summer humid heat extremes in the southeastern United States driven by sea surface temperatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6494, https://doi.org/10.5194/egusphere-egu24-6494, 2024.

“Synergistic Observing Network for Ocean Prediction (SynObs)” is a project of the United Nations Decade of Ocean Science for Sustainable Development. SynObs aims to find the way to extract maximum benefits from the combination among various ocean observation platforms, including satellite and in situ observations. A major ongoing effort led by SynObs is the international multi-system OSEs/OSSEs. In this activity, various operational centers and research institutes participating will conduct Observing System Experiments (OSEs) and Observing System Simulation Experiments (OSSEs) using a variety of ocean or coupled ocean-atmosphere prediction systems with the common setting to evaluate ocean observation impacts which are robust for most ocean prediction systems. More than 10 ocean prediction systems with various model resolutions and diverse data assimilation methods are used in this activity, and impacts of various observation data, including satellite sea surface temperature and height, Argo floats, and tropical mooring buoys, will be evaluated.

The activity is divided into two parts. The first part is the ocean prediction OSEs. In this part, we run several ocean reanalysis runs assimilating different observation datasets at least for 2020 (preferably extended to 2022), and conduct 10-day ocean predictions from the reanalysis fields of every 5 days. Three-dimensional oceanic temperature, salinity, and velocity fields with the 1/10-degree resolution, and several two-dimensional diagnostics with the 1/4-degree resolution will be analyzed. The second part is the subseasonal-to-seasonal (S2S) OSEs. Here, we run several ocean reanalysis runs for 2003-2022, and conduct 1-month (4-month) coupled predictions from the reanalysis fields of every month (twice a year). We will evaluate the impacts of ocean observation data on the long-term reanalysis and S2S predictions using the coupled prediction systems. We also plan to conduct OSSEs using multiple ocean prediction systems in order to assess newly emerging or future observing systems, such as SWOT, ocean gliders, etc. 

We are currently conducting the S2S OSEs using a Japanese operational global ocean data assimilation and coupled prediction system for S2S forecasts. We are now conducting OSEs assimilating no in situ observations and withholding temperature and salinity profiles observed by Argo floats. In the presentation, we will introduce the results and the perspective of the collaborative activities.

How to cite: Fujii, Y., Ishikawa, I., and Hirahara, S.: Early results of OSEs conducted for the SynObs international multi-system OSE effort using an Japanese operational system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6970, https://doi.org/10.5194/egusphere-egu24-6970, 2024.

EGU24-7918 | ECS | Orals | CL4.10

Generation of sea ice initial conditions for the next Météo-France seasonal forecasting system 

Fousiya Thottuvilampil Shahulhameed, Jonathan Beuvier, and Damien Specq

Research and development activities around the current Météo-France operational seasonal forecasting system (System 8) are underway to upgrade it to the next version (System 9), along with efforts to improve the initialization of its components. Among these components, sea ice is particularly challenging to initialize. At present, a coupled-nudged initialisation strategy, based on a high-resolution configuration of the CNRM-CM6 climate model, is employed to initialise the System 8, except for the sea-ice. In order to get initial states of sea ice that are consistent with the forecasting model, our procedure consists in making a preliminary continuous run where the ocean and sea ice models are integrated in stand-alone mode, with forcing at the surface from an atmosphere reanalysis.

However, in the current operational System 8 – based on the NEMO 3.6 ocean model and the GELATO sea ice model – the initial states of sea ice generated with this procedure are not fully realistic. Results show that the sea ice thickness over the Arctic region in the System 8 initial states is underestimated compared to the reference data. Numerous sensitivity experiments were carried out with the current NEMOv3.6-GELATO system, leading to some minor improvements. Thus, an upgraded version of the ocean model (NEMO version 4.2) coupled to a new sea-ice component (SI3) has been tested (in stand-alone mode, not coupled to the atmosphere) to see if the use of more recent versions of ocean and sea-ice models leads to some improvements in the Arctic sea ice representation. The results are encouraging as the representation of sea ice variables in the Arctic is improved compared to the old version.

This incites our team to foresee that System 9 will indeed incorporate the NEMO4.2 and SI3 models, and that the same initialization procedure as before (using these new models) will provide sea-ice initial states closer to those observed.

 

 

How to cite: Thottuvilampil Shahulhameed, F., Beuvier, J., and Specq, D.: Generation of sea ice initial conditions for the next Météo-France seasonal forecasting system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7918, https://doi.org/10.5194/egusphere-egu24-7918, 2024.

EGU24-11927 | Posters virtual | CL4.10 | Highlight

Seasonal prediction of solar energy resources in the United States 

Xiaosong Yang, Thomas Delworth, Liwei Jia, Nathaniel Johnson, Feiyu Lu, and Colleen McHugh

Solar energy plays a crucial role in the transition towards a sustainable and resilient energy future. One challenge that remains is the considerable year-to-year variation in solar energy resources. As a result, precise seasonal solar energy predictions become pivotal for effective energy system planning and operation.  This study employs GFDL’s GFDL’s Seamless System for Prediction and Earth System (SPEAR) to evaluate seasonal solar irradiance prediction across the United States.  Notably, SPEAR demonstrates high skill in predicting solar irradiance particularly in the western United States. Furthermore, we conduct an advanced predictability analysis to pinpoint the underlying physical drivers contributing to this skillful solar energy prediction.  The outcomes of this research offer substantial potential benefits to stakeholders within the energy sector by providing predictable information regarding year-to-year fluctuations in solar energy resources.

How to cite: Yang, X., Delworth, T., Jia, L., Johnson, N., Lu, F., and McHugh, C.: Seasonal prediction of solar energy resources in the United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11927, https://doi.org/10.5194/egusphere-egu24-11927, 2024.

EGU24-11948 | Posters on site | CL4.10

What is the Target for Multi-Model and Perturbed-Physics Ensembles? 

David Stainforth

Much effort goes into studying the causes of systematic errors in Earth System Models (ESMs). Reducing them is often seen as a high priority. Indeed, the development of Digital Twin approaches in climate research is founded on the idea that a sufficiently good model would be able to provide reliable and robust, conditional predictions of climate change (predictions conditioned on scenarios of future greenhouse gas emissions). Here, “reliable” encapsulates the idea that the predictions are suitable for use by society in anticipating and planning for future climate change, and “robust” encapsulates the idea that they are unlikely to change as the models are improved and developed.

Such an approach, however, begs the question, when is a model sufficiently realistic to be able to provide reliable, detailed predictions? A physical processes view of current ESMs suggests that they are not close to this level of realism while a nonlinear dynamical systems perspective raises questions over whether it will ever be possible to achieve such reliability for the types of regionally-specific, extrapolatory, climate change predictions that we may think society seeks.

Given this context, multi-model and perturbed-physics ensembles are often seen as a means to quantify uncertainty in conditional, climate change predictions (commonly referred to as “projections” in the scientific community). In the IPCC atlas (https://interactive-atlas.ipcc.ch/) the most easily accessible output is the multi-model median with the 10th, 25th, 75th and 90th percentiles of the multi-model distribution also prominent. This presentation in terms of probabilities implies that the probabilities themselves have meaning to the users of the data - most users are likely to take them as probabilities of different outcomes in reality. Unfortunately multi-model ensembles cannot be interpreted that way because we have no metric for the shape of model space nor any idea of how to explore it, so the ensemble members cannot be taken as independent samples of possible models. Perturbed-parameter ensembles work in a more defined space of possible model-versions but the shape of that space is also undefined and as a result the ensemble-based probabilities are again arbitrary.

When seeking the best possible information for society, multi-model and perturbed physics ensembles would benefit from targeting diversity: the greatest possible range of responses given a particular model structure. Model emulators could be used to systematise this process. Such an approach would provide more reliable information. It changes the question, however, from “when is a model sufficiently realistic” to “how unrealistic does a model have to be to be uninformative about extrapolatory future climatic behaviour?”

In this presentation I will discuss and elaborate on these issues.

 

References:

Stainforth, D., “What we do with what we’ve got”, Chapter 21 in “Predicting Our Climate Future: What we know, what we don’t know and what we can’t know”, Oxford University Press, 2023.

Stainforth, D.A. et al., Confidence, uncertainty and decision-support relevance in climate predictions, Phil.Trans.Roy.Soc., 2007.

Stainforth, D.A. et al., Issues in the interpretation of climate model ensembles to inform decisions, Phil.Trans.Roy.Soc., 2007.

How to cite: Stainforth, D.: What is the Target for Multi-Model and Perturbed-Physics Ensembles?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11948, https://doi.org/10.5194/egusphere-egu24-11948, 2024.

EGU24-12988 | ECS | Posters on site | CL4.10

A CNN-based Downscaling Method of C3S Seasonal Forecast: Temperature and Precipitation 

Qing Lin, Yanet Díaz Esteban, Fatemeh Heidari, Edgar Fabián Espitia Sarmiento, and Elena Xoplaki

Copernicus Climate Change Service provides seasonal forecasts for meteorological outlooks several months in advance and can provide indications of future climate risks on a global scale. Using downscaling techniques, global variables can be transferred to the high-resolution regional scale, allowing the information to be elaborated for extreme events detection and further implementing and coupling with hydrological models for regional hazard prediction, thus serving agriculture and energy, improving planning for tourism and other sectors.

In this study, we applied a new CNN-based architecture for temperature and precipitation downscaling. Both variables are downscaled from 1 degree to 1 arcminute to fulfill the requirements as an input to the hydrological models. The architecture implements an auto-encoder/decoder structure to extract the data relations. The system is trained with seasonal forecast inputs and observation data to establish the relation between both scales. The model is then evaluated with the validation period from the observation data to achieve the best performance, changing network structures and tuning different network hyper-parameters. The results show a good fit for the observation data on the monthly scale, providing enough details in the downscaling product. Finally, the best-performing networks for downscaling temperature and precipitation are selected and could be extended for further utilization.

How to cite: Lin, Q., Díaz Esteban, Y., Heidari, F., Espitia Sarmiento, E. F., and Xoplaki, E.: A CNN-based Downscaling Method of C3S Seasonal Forecast: Temperature and Precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12988, https://doi.org/10.5194/egusphere-egu24-12988, 2024.

EGU24-13811 | ECS | Posters on site | CL4.10

Estimating Seasonal to Multi-year Predictability of Statistics of Climate Extremes using the CESM2-based Climate Prediction System 

Alexia Karwat, June-Yi Lee, Christian Franzke, and Yong-Yub Kim

Climate extremes, such as heat waves, heavy precipitation, intense storms, droughts, and wildfires, have become more frequent and severe in recent years as a consequence of human-induced climate change. Estimating the predictability and improving prediction of the frequency, duration, and intensity of these extremes on seasonal to multi-year timescales are crucial for proactive planning and adaptation. However, climate prediction at regional scales remains challenging due to the complexity of the climate system and limitations in model accuracy. Here we use a large ensemble of simulations, assimilations, and reforecasts using Community Earth System Model version 2 (CESM2) to assess the predictability of statistics of climate extremes with lead times of up to 5 years. We show that the frequency and duration of heat waves during local summer in specific regions are predictable up to several months to years. Sources of long-term predictability include not only external forcings but also modes of climate variability across time scales such as El Niño and Southern Oscillation, Pacific Decadal Variability, and Atlantic Multidecadal Variability. This study implies opportunities to deepen our scientific understanding of sources for long-term prediction of statistics of climate extremes and the potential for the associated disaster management.

How to cite: Karwat, A., Lee, J.-Y., Franzke, C., and Kim, Y.-Y.: Estimating Seasonal to Multi-year Predictability of Statistics of Climate Extremes using the CESM2-based Climate Prediction System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13811, https://doi.org/10.5194/egusphere-egu24-13811, 2024.

EGU24-15488 | ECS | Orals | CL4.10

Phytoplankton predictability in the Tropical Atlantic - triggered by nutrient pulses from the South 

Filippa Fransner, Marie-Lou Bachèlery, Shunya Koseki, David Rivas, Noel Keenlyside, Nicolas Barrier, Matthieu Lengaigne, and Olivier Maury

The variability and predictability of the Tropical Atlantic primary productivity remains little explored on interannual-to-decadal time scales. Here, we  present the results of two studies, in which find a decadal scale variability in phytoplankton abundance that can be predicted three years ahead. The predictions are made with NorCPM, which is a fully coupled climate prediction model with ocean biogeochemistry that assimilates temperature and salinity to reconstruct past variability. From these reconstructions, predictions are initialized that are run freely ten years ahead. We find that the predictability is a result of nutrient pulses that are advected with the southern branch of the South Equatorial Current from the most southern part of the Atlantic, and that then get caught in the Equatorial undercurrent before they reach the surface in the Tropical Atlantic Ocean. A more detailed analysis is being done in order to pinpoint the underlying mechanisms in a forced ocean model, where we find a link to the Pan-Atlantic decadal oscillation.

How to cite: Fransner, F., Bachèlery, M.-L., Koseki, S., Rivas, D., Keenlyside, N., Barrier, N., Lengaigne, M., and Maury, O.: Phytoplankton predictability in the Tropical Atlantic - triggered by nutrient pulses from the South, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15488, https://doi.org/10.5194/egusphere-egu24-15488, 2024.

EGU24-15829 | Posters on site | CL4.10

The role of realistic vegetation variability in climate predictability and prediction 

Andrea Alessandri, Emanuele Di Carlo, Franco Catalano, Bart van den Hurk, Magdalena Alonso Balmaseda, Gianpaolo Balsamo, Souhail Boussetta, and Tim Stockdale

Vegetation is a relevant and highly dynamic component of the Earth system and its variability – at seasonal, interannual, decadal and longer timescales – modulates the coupling with the atmosphere by affecting surface variables such as roughness, albedo and evapotranspiration. In this study, we investigate the effects of improved representation of vegetation dynamics on climate predictability and prediction at the seasonal timescale. To this aim, the observational constraints from the latest generation satellite dataset of vegetation Leaf Area Index (LAI) have been integrated in the modeling, including a parameterization of the effective vegetation cover as a function of LAI. The improved vegetation representation is implemented in HTESSEL, which is the land surface model included in the seasonal forecasting (ECMWF SEAS5) systems used in this work.

Our results show that the realistic representation of vegetation variability has significant effects on both potential predictability and actual prediction skill at the seasonal time scale. It is shown a significant improvement of the skill in predicting boreal winter (December-January-February; DJF) 2m Temperature (T2M) at 1-month lead time especially over Euro-Asian boreal forests; the improvement is at least in part due to the more realistic representation of the interannual albedo variability that is related to the changes in vegetation shading over snow. Remarkably, from the region with the most considerable T2M improvement originates a large-scale ameliorating effect on circulation encompassing Northern Hemisphere middle-to-high latitudes from Siberia to the North Atlantic. The results indicate that the coupling with the improved vegetation might operate by amplifying locally the signal originating from the North Atlantic sector, therefore improving both potential predictability and actual skill over the region. Concurrently, the improved predictability and skill over the Euro-Asian forests appears to feedback to the large-scale circulation enhancing the representation of the circulation pattern and associated interannual anomalies.

How to cite: Alessandri, A., Di Carlo, E., Catalano, F., van den Hurk, B., Balmaseda, M. A., Balsamo, G., Boussetta, S., and Stockdale, T.: The role of realistic vegetation variability in climate predictability and prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15829, https://doi.org/10.5194/egusphere-egu24-15829, 2024.

EGU24-16402 | Orals | CL4.10

On the stationarity of the global spatial dependency of heat risk on drought. 

Matteo Zampieri, Karumuri Ashok, Andrea Toreti, Davide Bavera, and Ibrahim Hoteit

Compound climate anomalies pose escalating risks in the context of climate change, with anomalous heat and drought presenting significant stressors to both ecosystems and society. The simultaneous occurrence of these events can be influenced by land surface processes such as the soil moisture – air temperature coupling. However, the long-term variability of this coupling remains unexplored. Here, using a combination of observations and multi-model ensemble forecasts dating back to the 1980s, we examine the global land exposure to higher than normal probabilities of concurrent hot temperature anomalies and drought on a monthly scale. Our findings confirm that drought substantially shapes the spatial distribution of heat-related risks on a global scale, offering a crucial predictive factor for these combined events. Traditionally, defining heat anomalies for non-adaptive systems involves fixed reference temperature thresholds. Using this method, our analysis reveals that the portion of global land experiencing drought-conditioned hot temperature anomalies has tripled in less than three decades. Surprisingly, the global level of spatial coupling appears to be declining. However, this outcome heavily depends on the specific definition of heat risk employed. By employing a time-dependent temperature threshold that considers changes in the climate's mean state due to both global warming and natural variability, a different picture emerges. Using the latter method, the level of spatial coupling demonstrates persistence and stability. Importantly, this method is better suited to assessing risks for adaptive systems and is more consistent with our current understanding of the underlying processes. Our study strongly advocates for tailoring hazard definitions to the specific processes and systems under investigation. Additionally, it underscores the pivotal role of operational sub-seasonal and seasonal forecasts in early warning systems, crucial for societal adaptation in the face of global warming.

How to cite: Zampieri, M., Ashok, K., Toreti, A., Bavera, D., and Hoteit, I.: On the stationarity of the global spatial dependency of heat risk on drought., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16402, https://doi.org/10.5194/egusphere-egu24-16402, 2024.

EGU24-16456 | Orals | CL4.10

Advancements and Challenges in Assessing and Predicting the Global Carbon Cycle Variations Using Earth System Models 

Hongmei Li, Tatiana Ilyina, István Dunkl, Aaron Spring, Sebastian Brune, Wolfgang A. Müller, Raffaele Bernardello, Laurent Bopp, Pierre Friedlingstein, William J. Merryfield, Juliette Mignot, Michael O'Sullivan, Reinel Sospedra-Alfonso, Etienne Tourigny, and Michio Watanabe

The imperative to comprehend and forecast global carbon cycle variations in response to climate variability and change over recent decades and in the near future underscores its critical role in informing the global stocktaking process. Our study investigates CO2 fluxes and atmospheric CO2 growth through ensemble decadal prediction simulations using Earth System Models (ESMs) driven by CO2 emissions with an interactive carbon cycle. These prediction systems provide valuable insights into the global carbon cycle and, therefore, the variations in atmospheric CO2. Assimilative ESMs with interactive carbon cycles effectively reconstruct and predict atmospheric CO2 and carbon sink evolution. The emission-driven prediction systems maintain comparable skills to conventional concentration-driven methods, predicting 2-year accuracy for air-land CO2 fluxes and atmospheric CO2 growth, with air-sea CO2 fluxes exhibiting higher skill for up to 5 years. Our multi-model predictions for the next year, along with assimilation reconstructions, for the first time contribute to the Global Carbon Budget 2023 assessment. We plan regular updates and the involvement of more ESMs in future assessments. Ongoing efforts include implementing seasonal-scale predictions for skill improvement. Furthermore, we assess uncertainty contributions to CO2 flux and growth predictions, revealing the comparable impacts of internal climate variability and diverse model responses, particularly at a lead time of 1-2 years. Notably, the effect of CO2 emission forcing rivals internal variability at a 1-year lead time. Large uncertainties in CO2 responses to initial states of ENSO are observed, stemming from both model responses and internal variability. The challenge lies in addressing the scarcity and uncertainty of data for initialization and obtaining precise external forcings to enhance the reliability of predictions. The further advancements involve not only addressing comprehensive bias correction but also implementing statistical methods to enhance dynamical predictions.

How to cite: Li, H., Ilyina, T., Dunkl, I., Spring, A., Brune, S., Müller, W. A., Bernardello, R., Bopp, L., Friedlingstein, P., Merryfield, W. J., Mignot, J., O'Sullivan, M., Sospedra-Alfonso, R., Tourigny, E., and Watanabe, M.: Advancements and Challenges in Assessing and Predicting the Global Carbon Cycle Variations Using Earth System Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16456, https://doi.org/10.5194/egusphere-egu24-16456, 2024.

EGU24-16842 | Posters on site | CL4.10 | Highlight

Exploring Sources of Multi-year Predictability of Terrestrial Ecosystem 

June-Yi Lee, Yong-Yub Kim, and Jeongeun Yun

The demand for decision-relevant and evidence-based near-term climate information is increasing. This includes understanding and explaining the variability and changes in ecosystems to support disaster management and adaptation choices. As climate prediction from seasonal to decadal (S2D) expands to encompass Earth system dimensions, including terrestrial and marine ecosystems, it is crucial to deepen our scientific understanding of the long-term predictability sources for ecosystem variability and change. Here we explore to what extent terrestrial ecosystem variables are driven by large-scale - potentially predictable -climate modes of variability and external forcings or whether regional random environmental factors are dominant. To address these issues, we utilize a multi-year prediction system based on Community Earth System Model version 2 (CESM2).  The system consists of 50-member uninitialized historical simulations, 20-member ocean assimilations, and 20-member hindcast initiated from every January 1st integrating for 5 years from 1961 to 2021. The key variables assessed are surface temperature, precipitation, soil moisture, wildfire occurrence, and Gross Primary Productivity. Our results suggest that land surface processes and ecosystem variables over many parts of the globe can be potentially predictable 1 to 3 years ahead originating from anthropogenic forced signals and modes of climate variability, particularly El Nino and Southern Oscillation and Atlantic Multi-decadal variability. These global modes of climate variability shift regional temperature and precipitation patterns, leading to changes in soil moisture, wildfire occurrence, and terrestrial productivity.  

How to cite: Lee, J.-Y., Kim, Y.-Y., and Yun, J.: Exploring Sources of Multi-year Predictability of Terrestrial Ecosystem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16842, https://doi.org/10.5194/egusphere-egu24-16842, 2024.

EGU24-18766 | Orals | CL4.10

Deciphering Prediction Windows of Opportunity: A Cross Time-Scale Causality Framework   

Stefano Materia, Constantin Ardilouze, and Ángel G. Muñoz

While subseasonal forecasts often exhibit limited skill across mid-latitudes, occasional improvements are observed in specific locations during certain periods, known as "windows of opportunity." Understanding the causal factors behind these windows is complex due to the diverse and interdependent nature of predictors, their spatial and temporal variability, and the challenges in establishing causality relationships. 

Traditional lagged-correlations methods provide only a partial view, lacking insights into causality. Based on previous work on the role of land surface processes, multi-model subseasonal model skill assessment and the use of causality metrics in predictions across timescales (e.g. Ardilouze et al., 2020, 2021; Materia et al 2020, 2022; Muñoz et al., 2023), here we propose an approach based on the Liang-Kleeman information flow, allowing the assessment of statistically significant causal links across various lead times.

Applied to reforecast and reanalysis data, our framework successfully identifies significant predictability drivers -involving sea-surface temperatures, atmospheric circulation and remote and local land-surface processes-, revealing their interference (interplay), evolving patterns and prevalence from seasonal to subseasonal scales. 

Furthermore, the comparison between reanalysis and reforecast results aids in assessing the capability of models to capture these causality features, suggesting additional ways to conduct model diagnostics. We illustrate here the theoretical background by showcasing the causal factors influencing a window of opportunity identified from a multimodel subseasonal reforecast.

 

References

Ardilouze, C., Materia, S., Batté, L., Benassi, M., & Prodhomme, C. (2020). Precipitation response to extreme soil moisture conditions over the Mediterranean. Climate Dynamics, 1, 1–16. https://doi.org/10.1007/S00382-020-05519-5/TABLES/2

Ardilouze, C., Specq, D., Batté, L., & Cassou, C. (2021). Flow dependence of wintertime subseasonal prediction skill over Europe. Weather and Climate Dynamics, 2(4), 1033-1049. https://doi.org/10.5194/wcd-2-1033-2021 

Materia, S., Muñoz, Á. G., Álvarez-Castro, M. C., Mason, S. J., Vitart, F., & Gualdi, S. (2020). Multi-model subseasonal forecasts of spring cold spells: potential value for the hazelnut agribusiness. Weather and Forecasting. https://doi.org/10.1175/waf-d-19-0086.1 

Materia, S., Ardilouze, C., Prodhomme, C., & et al. (2022). Summer temperature response to extreme soil water conditions in the Mediterranean transitional climate regime. Climate Dynamics, 58, 1943–1963. https://doi.org/10.1007/s00382-021-05815-8

Muñoz, Á. G., Doblas-Reyes, F., DiSera, L., Donat, M., González-Reviriego, N., Soret, A., Terrado, M., & Torralba, V. (2023). Hunting for “Windows of Opportunity” in Forecasts Across Timescales? Cross it. EGUGA, EGU-15594. https://doi.org/10.5194/EGUSPHERE-EGU23-15594 

How to cite: Materia, S., Ardilouze, C., and Muñoz, Á. G.: Deciphering Prediction Windows of Opportunity: A Cross Time-Scale Causality Framework  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18766, https://doi.org/10.5194/egusphere-egu24-18766, 2024.

EGU24-699 | ECS | Orals | CL4.12

Decline of water resources in Northern Hemisphere Mediterranean Climate Regions based on satellite observations. 

Vincenzo Senigalliesi, Andrea Alessandri, Emanuele Di Carlo, and Annalisa Cherchi

The Mediterranean Climate Regions (MCRs) share similarities in terms of experienced temperatures and precipitation patterns, resulting in similar vegetation, i.e. farms and agricultural approaches/strategies. Recent findings suggest that groundwater levels in the Euro-Mediterranean may experiencing negative trends, resulting from decreasing precipitation, increasing evapotransipration and/or increasing withdrawal. This suggests a potential dry transition in MCRs, affecting biodiversity and ecosystems. By focusing on the Euro-Mediterranean and California, this work characterizes the dry transition through soil water content analysis from observation. The Total Water Storage (TWS) variable provided by the GRACE/GRACE-FO mission is utilized, carrying information about groundwater, soil moisture, surface water, snow water equivalent, and water stored in biomass. Furthermore, the contribution related to the variability of TWS due to associated drivers, precipitation, and potential evapotranspiration (PET) is quantified. The methodology framework relies on Empirical Orthogonal Function (EOF) analysis and a Multivariate Linear Regression model (MLR) to characterize, respectively, the modes of variability of TWS and the relative influence of the drivers to the total variance of the field. Our results highlight a general drying trend for both regions; furthermore, they suggest that in certain domains, variations in TWS are more sensitive to specific drivers than others: the western Euro-Mediterranean (Spain, Portugal, and parts of North Africa) is more susceptible to precipitation variability than PET, as it is more influenced by Atlantic flows and the effects of the North Atlantic Oscillation; in contrast, the TWS in the eastern Euro-Mediterranean (Greece and Turkey) is predominantly affected by the increase in PET due to the temperature increase; on the other hand he central EuroMed (Italy and Tunisia) exhibit a mixed behaviour with influences of both precipitation and PET on TWS. Regarding California, similar to the Euro-Mediterranean, there is a negative trend in TWS in equatorward regions, where PET is the major source of variability. Conversely, starting from 43°N in the poleward regions, there is a positive trend in TWS, mostly due to the increase in precipitation in that area.

How to cite: Senigalliesi, V., Alessandri, A., Di Carlo, E., and Cherchi, A.: Decline of water resources in Northern Hemisphere Mediterranean Climate Regions based on satellite observations., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-699, https://doi.org/10.5194/egusphere-egu24-699, 2024.

EGU24-1072 | Orals | CL4.12

Assessing the interactions between extreme weather systems and the marine environment in the Mediterranean Sea      

Babita Jangir, Marco Reale, Milena Menna, Alok Kumar Mishra, Riccardo Martellucci, Gianpiero Cossarini, Stefano Salon, Elena Mauri, and Ehud Strobach

In this study, the impacts of a specific class of extreme weather systems in the Mediterranean region (Medicanes) on the physical and biogeochemical parameters of the marine environment are thoroughly investigated. A comprehensive analysis based on 14 systems that occurred between 2007 and 2021 was carried out, with a specific focus on the impact on the different regions of the Mediterranean Sea (MS). The analysis showed some consistent patterns in the response of the marine environment to the passage of the system: surface concentrations of Chlorophyll-a (Chl-a), phytoplankton, nutrients, and oxygen tend to increase above the MLD, while temperature tends to decrease. Significant increments of these parameters were observed in the presence of Warm Core Eddies (WCEs) and Cold Core Eddies (CCEs). The interaction with WCEs enhanced the intensity of the weather system and related mixing and upwelling in the upper layer, leading to the increase in Chl-a, phytoplankton, and oxygen concentrations .. Cyclone-induced local mixing injects nutrients into the ocean’s upper layer that can drive significant phytoplankton blooms. Moreover, strong winds frequently lead to a drop in sea surface temperature (SST), which is a key factor in primary productivity. The analysis of mean sea level pressure (MSLP) and wind speed (WS) along the path of the cyclones revealed a sudden drop (rise) in MSLP and rise (drop) in WS at WCEs (CCEs) locations. It is observed that a few medicanes, such as Zissi, Anton, and Xandra, show exceptional behavior. Among them, Zissi exhibited an exceptionally high translational speed. The fast evolution of Zissi resulted in limited interaction with the underlying ocean, which is responsible for its unique characteristics during the event.

How to cite: Jangir, B., Reale, M., Menna, M., Mishra, A. K., Martellucci, R., Cossarini, G., Salon, S., Mauri, E., and Strobach, E.: Assessing the interactions between extreme weather systems and the marine environment in the Mediterranean Sea     , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1072, https://doi.org/10.5194/egusphere-egu24-1072, 2024.

EGU24-1843 | ECS | Posters on site | CL4.12

Assessment of Future Precipitation Changes in Mediterranean Climate Regions from CMIP6 ensemble 

Patricia Tarín-Carrasco, Desislava Petrova, Laura Chica-Castells, Jelena Lukovic, Xavier Rodó, and Ivana Cvijanovic

Previous studies have indicated a large model disagreement in the future projections of precipitation changes over the regions featuring Mediterranean climate. Many of these highly populated regions have been experiencing major droughts in the recent decades, raising concerns about future precipitation changes and their impacts. Here we investigate precipitation projections across five Mediterranean climate regions in the CMIP6 ensemble, and study their respective model agreements on the sign of future precipitation changes. We focus on the period 2050-2079 relative to 1970-1999, and consider two climate change scenarios (ssp2-4.5 and ssp5-8.5) over the Mediterranean Basin (MED), California (CAL), the central coast of Chile (SAA), the Cape Province area of South Africa (SAF) and southwest Australia (AUS).

The CMIP6 ensemble mean suggests that annual mean cumulative precipitation will decrease over all the regions studied with the exception of northern California. In most cases, this decline is primarily attributed to a reduction in winter precipitation, except over the Mediterranean Basin, where the most significant decrease occurs in autumn. The model agreement on the sign of future precipitation changes is generally high over the regions and seasons where the ensemble mean indicates the precipitation decline in the future, and low over the regions showing the precipitation increase or no change. Specifically, the model agreement is low in southern California during all seasons, in northern Mediterranean during winter and autumn, and in southwest Australia during austral summer and autumn. CMIP6 ensemble means also indicate that the consecutive dry days (CDD) will increase in the future in all regions, but again the model agreement on this increase is low over southern and central California, the southern Mediterranean, and parts of southwest Australia. Similarly, the ensemble mean of consecutive wet days (CWD) indicate a decrease in all regions, with weak model agreement on the sign of future changes over CAL, northeast AUS and part of the MED region. The ensemble mean maximum one-day precipitation increases over all the regions, the most over the parts of southwest Australia and the Mediterranean.

We conclude that despite substantial improvements to the new CMIP6 generation of models, the intermodel differences in future projections of precipitation changes continue to be high across parts of California, the Mediterranean Basin and southwest Australia. Impact studies need to account for these uncertainties and consider the whole intermodel range of projected precipitation changes.

How to cite: Tarín-Carrasco, P., Petrova, D., Chica-Castells, L., Lukovic, J., Rodó, X., and Cvijanovic, I.: Assessment of Future Precipitation Changes in Mediterranean Climate Regions from CMIP6 ensemble, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1843, https://doi.org/10.5194/egusphere-egu24-1843, 2024.

EGU24-1864 | ECS | Posters on site | CL4.12

Comparison and analysis of drought indices SPI and SPEI for Belgrade (Serbia) 

Lazar Filipovic and Ivana Tosic

Quantifying the intensity of a drought is not an easy task, as one has to take into
account multiple parameters, for example rainfall, temperature, soil water content, etc.
Numerous indices have been developed to tackle this issue, and some of the most widely
used are standard precipitation index (SPI) and standard precipitation evapotranspiration index
(SPEI), which, as the name implies, standardize precipitation and evapotranspiration over a
point for a certain time period and use that as a reference for an estimate of available water.
The goal of this work is to analyze these drought indices for a long-term time period,
take a look at their correlation and compare them with available records. The theoretical
difference between the two indices is in the fact that SPEI takes (potential) evapotranspiration
into account, while SPI does not. Since sufficient measured evapotranspiration data was not
available, potential evapotranspiration was used, calculated by the Thorntwaite method
(taking into account temperature and geographical position). Precipitation and temperature
data was acquired from the station network ran by the Republic Hydrometeorological Service
of Serbia, for the time period of 1961-2020. Since the SPI and SPEI can be computed for
different timescales, in this study the indices for 3-, 6- and 12-months were compared.
The results show that despite high correlation between SPI and SPEI (r > 0.9), their
behavior in regards to drought events shows an important difference. This is visible in the
temporal spread of the dry months. SPEI depicts the last two decades as much drier than SPI
does, and inversely, the sixties and the seventies as much wetter. Also, for the whole time
period, SPEI shows a trend towards more dry conditions, while SPI shows no clear trend.
This is a consequence of rising potential evapotranspiration, which in itself is a consequence
of rising average temperatures.
The conclusion is that the indices should not be used interchangeably and with
temperature data being as available as precipitation data, SPEI is more representative of
water budget in the area in question.

How to cite: Filipovic, L. and Tosic, I.: Comparison and analysis of drought indices SPI and SPEI for Belgrade (Serbia), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1864, https://doi.org/10.5194/egusphere-egu24-1864, 2024.

EGU24-2544 | ECS | Orals | CL4.12

A synoptic circulation patterns evaluation framework for CMIP6 GCMs over the Euro-Mediterranean region 

Matias Olmo, Diego Campos, Cos Pep, Muñoz Ángel, Soret Albert, and Doblas-Reyes Francisco

In a global warming scenario, there is a growing need to understand why the Euro-Mediterranean region is a hotspot for both warming and drying signals and the seasonal and regional details, thus providing improved climate information required by decision makers. This work focuses on the design of an evaluation framework for climate simulations based on a classification of synoptic circulation patterns (CPs). A set of 30 CMIP6 global climate models (GCMs) is evaluated in terms of how well they reproduce the spatio-temporal variability of a CPs classification within the region. CPs are constructed through a hierarchical clustering procedure, using daily mean sea level pressure (SLP) during 1950-2014 against the ERA5 reanalysis. The link with surface variables -including precipitation, minimum and maximum temperatures- is also studied. Model performance is quantified based on different metrics for the spatial and temporal representation of the SLP patterns and the associated surface conditions, allowing a ranking of the best-performing GCMs.

GCMs adequately reproduce the annual cycle of the CPs frequency, with a dominant synoptic structure during summertime enhancing warm and dry conditions. Best-performing models in this regard include MPI-ESM1-2-LR, EC-Earth3-CC and MRI-ESM2-0. However, the correct timing of this CP and the transitional patterns are often misrepresented, such as in GFDL-ESM4 and NorESM2-LM. The analysis of the surface patterns associated with each CP show good model skills, better for the extreme temperatures than for rainfall and particularly during the transition seasons, for which the GCMs spread also increases. In this sense, the models EC-Earth3-Veg, EC-Earth3-CC and GFDL-CM4 present the best scores, whereas INM-CM5-0, KIOT-ESM and NorESM2-LM show the lower skills. By blending both the spatial and temporal features of the CPs, the EC-Earth3-CC, EC-Earth3-Veg, GFDL-CM4 and MRI-ESM2-0 arise as the best-performing GCMs over the Euro-Mediterranean region.

Overall, it is highlighted that not all models perform best in all the aspects considered, emphasizing the need of a complete process-based model evaluation. This is a way to constrain the future projections in order to reduce uncertainty and come up with coherent climate information at a regional scale.

How to cite: Olmo, M., Campos, D., Pep, C., Ángel, M., Albert, S., and Francisco, D.-R.: A synoptic circulation patterns evaluation framework for CMIP6 GCMs over the Euro-Mediterranean region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2544, https://doi.org/10.5194/egusphere-egu24-2544, 2024.

EGU24-4782 | Orals | CL4.12

Recent and near-term future changes in impacts-relevant seasonal hydroclimate in the world's Mediterranean climate regions 

Richard Seager, Yutian Wu, Annalisa Cherchi, Isla Simpson, Timothy Osborn, Yochanan Kushnir, Jelena Lukovic, Haibo Liu, and Jennifer Nakamura

Change over recent decades in the world's five Mediterranean Climate Regions (MCRs) of quantities of relevance to water resources, ecosystems and fire are examined for all seasons and placed in the context of changes in large-scale circulation. Near-term future projections are also presented.   It is concluded that, based upon agreement between observational data sets and modeling frameworks, there is strong evidence of radiatively-driven drying of the Chilean MCR in all seasons and southwest Australia in winter.  Observed drying trends in California in fall, southwest southern Africa in fall, the Pacific Northwest in summer and the Mediterranean in summer agree with radiatively-forced models but are not reproduced in a model that also includes historical sea surface temperature (SST) forcing, raising doubt about the human-origin of these trends. Observed drying in the Mediterranean in winter is stronger than can be accounted for by radiative forcing alone and is also outside the range of the SST-forced ensemble. It is shown that near surface vapor pressure deficit (VPD) is increasing almost everywhere but that, surprisingly, this is contributed to in the southern hemisphere subtropics to mid-latitudes by a decline in low level specific humidity.  The southern hemisphere drying, in terms of precipitation and specific humidity, is related to a poleward shift and strengthening of the westerlies with eddy-driven subsidence on the equatorward side. Model projections indicate continued drying of southern hemisphere MCRs in winter and spring, despite ozone recovery and year-round drying in the Mediterranean.  Projections for the North American MCR are uncertain, with a large contribution from internal variability, with the exception of drying in the Pacific Northwest in summer.  Overall the results indicate continued aridification of MCRs other than in North America with important implications for water resources, agriculture and ecosystems. 

How to cite: Seager, R., Wu, Y., Cherchi, A., Simpson, I., Osborn, T., Kushnir, Y., Lukovic, J., Liu, H., and Nakamura, J.: Recent and near-term future changes in impacts-relevant seasonal hydroclimate in the world's Mediterranean climate regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4782, https://doi.org/10.5194/egusphere-egu24-4782, 2024.

EGU24-5891 | ECS | Posters on site | CL4.12

An operational prototype for seasonal drought prediction in a Mediterranean region 

Miguel Ángel Torres-Vázquez, Andrina Gincheva, Amar Halifa-Marín, Juan Pedro Montavez, and Marco Turco

Droughts create significant societal and environmental challenges. Accurate seasonal drought forecasting can provide early insights into potential impacts, serving as a vital resource for informed decision-making. An operational prototype with high spatial resolution is presented to predict seasonal meteorological drought in Spain (4SPAIN).

The prediction system is inspired by an empirical method known as Ensemble Streamflow Prediction (ESP; Day, 1985). The model forecasts drought using the Standardized Precipitation Index (SPI6; Mckee et al., 1993) based on accumulated monthly precipitation data over 6 months (Turco et al., 2017). Due to the near real-time availability of ERA5 and its high similarity with the Spanish Meteorological Agency Spanish database (Torres-Vázquez et al., 2023), this database was chosen for the development and implementation of 4SPAIN. The validation of the model shows that it has predictive skill generally up to four-month lead time, whereas worse results come from predicting the wet season.

Finally, an online operational prediction system called "Drought forecast monitor for Spain" was implemented. This low computational cost tool can provides users and competent authorities with an interactive interface to make early decisions based on updated information about the magnitude of the drought, uncertainty, alert level, and the probability of moderate drought occurrences (https://matv.shinyapps.io/app_4SPAIN/).

References

Day, G. N. (1985). Extended streamflow forecasting using NWSRFS. Journal of Water Resources Planning and Management, 111(2), 157–170.

McKee, T. B., Doesken, N. J., y Kleist, J. (1993). The relationship of drought frequency and duration to time scales. In Eighth Conference on Applied Climatology, January, Anaheim, California, 1993, pages 17–22. American Meteorological Society.

Torres-Vázquez, M. Á., Halifa-Marín, A., Montávez, J. P., & Turco, M. (2023). High resolution monitoring and probabilistic prediction of meteorological drought in a Mediterranean environment. Weather and Climate Extremes, 40, 100558.

Turco, M., Ceglar, A., Prodhomme, C., Soret, A., Toreti, A., & Francisco, J. D. R. (2017). Summer drought predictability over Europe: empirical versus dynamical forecasts. Environmental research letters, 12(8), 084006.

Acknowledgements 

A.G. thanks  to the Ministerio de Ciencia, Innovación y Universidades of Spain for PhD contract FPU19/06536. M.T. acknowledges funding by the Spanish Ministry of Science, Innovation and Universities through the Ramón y Cajal Grant Reference RYC2019-027115-I and through the project ONFIRE, Grant PID2021-123193OB-I00, funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”.

How to cite: Torres-Vázquez, M. Á., Gincheva, A., Halifa-Marín, A., Montavez, J. P., and Turco, M.: An operational prototype for seasonal drought prediction in a Mediterranean region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5891, https://doi.org/10.5194/egusphere-egu24-5891, 2024.

EGU24-6769 | ECS | Orals | CL4.12

Climate Change in the Mediterranean: Assessing Changes in Different Circulations and the Impacts on the Mediterranean Hydroclimate 

Roshanak Tootoonchi, Simona Bordoni, and Roberta D'Agostino

Changes in the hydroclimate of the Mediterranean region by the end of the 21st century are studied using phase 6 of the Coupled Model Intercomparison Project (CMIP6) projections. More specifically, we examine how changes in the different terms of the atmospheric moisture budget in this region, namely the moisture flux convergence due to the zonally averaged flow, and stationary and transient eddies, contribute to changes in the climatological net precipitation (precipitation minus evaporation, P – E), in the annual, seasonal, and zonal mean over land and sea.

According to the ensemble-mean of ten CMIP6 models, the climatological annual mean P – E is projected to decrease drastically by the end of the 21st century over northern Mediterranean land regions as well as the sea. The drying is predominantly due to increased total stationary-eddy moisture flux divergence, which arises from increased divergence of the zonally averaged moisture by the zonally-anomalous circulation. For both land and sea, the annual mean pure stationary eddy term is projected to bring wetter conditions within the Mediterranean, except for northwestern Africa and the Iberian Peninsula. This wettening tendency is, however, not large enough to offset the drying caused by the zonally-anomalous circulation.

By the end of the 21st century, the annual mean transient eddies are projected to cause increased drying over the northern Mediterranean land regions and the western Mediterranean Sea, and increased moistening over the eastern Mediterranean. The drying due to the annually and zonally averaged circulation, associated with the descending branch of the Hadley cell, is very small, and appears to be a weaker signal with respect to the others.

While increased moisture divergence due to transient eddies during winter is a contributing factor to the Mediterranean drying, it is not the main cause of year-round drying by the end of the 21st century. In fact, there are slight increases of moisture convergence over Portugal, Spain, and northern Turkey. Rather, it is the increase in the divergent stationary eddies during summer and winter that drives the aridification phenomenon in the Mediterranean. Recent studies using CMIP5 models have reported similar results (Seager et al. 2014; Seager et al. 2019), pointing to the robustness of the projected signal.

 

References:

  • Seager, R., Liu, H., Henderson, N., Simpson, I., Kelley, C., Shaw, T., Kushnir, Y., & Ting, M. (2014). Causes of increasing aridification of the mediterranean region in response to rising greenhouse gases. Journal of Climate, 27(12), 4655–4676. https://doi.org/10.1175/JCLI-D-13-00446.1
  • Seager, R., Osborn, T. J., Kushnir, Y., Simpson, I. R., Nakamura, J., & Liu, H. (2019). Climate Variability and Change of Mediterranean-Type Climates. Journal of Climate, 32(10), 2887–2915. https://doi.org/10.1175/JCLI-D-180472.1

How to cite: Tootoonchi, R., Bordoni, S., and D'Agostino, R.: Climate Change in the Mediterranean: Assessing Changes in Different Circulations and the Impacts on the Mediterranean Hydroclimate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6769, https://doi.org/10.5194/egusphere-egu24-6769, 2024.

The Eastern Mediterranean region has seen significant changes in climate conditions over the last few decades. Enhanced changes are anticipated for the coming decades, fully justifying the region’s assignment as a “climate change hot spot”. Even though, contributing only marginally to greenhouse gas (GHG) emissions on the global scale, the need for effective mitigation measures and a comprehensive adaptation strategy are urgently needed.

A recent study evaluates the currently declared mitigation commitments under the United Nation’s Framework Convention on Climate Change (UNFCCC) and planned adaptation plans for six countries in the Eastern Mediterranean: Cyprus, Egypt, Greece, Israel, Palestine and Türkiye (Lange, subm.). This is compared to concretely ongoing activities, as well as additional needs to device measures aimed to reduce the adverse consequences of ongoing and future climate change in these countries.

All of the named countries are parties to the UNFCCC and have signed and ratified the UN-Paris Agreement of 2015. However, their current emissions as well as their GHG reduction goals (Nationally Determined Contributions, NDC) differ significantly. Current annual emissions vary between a minimum of 3 200 Gg CO2equ. (Palestine) to a maximum of 459 102 Gg CO2equ. (Türkiye; UNFCCC, 2016; https://unfccc.int/resource/docs/2015/cop21/eng/10.pdf#page=30). As to the NDCs, the differences between the countries considered here are even more drastic. While reduction targets amounted to 24%, appr. 38% and 27% (relative to recent emission values) by 2030 for Cyprus, Greece and Israel, respectively, emissions are expected to increase significantly during this period for Egypt, Palestine and Türkiye.

Following recent studies (see: Konrad Adenauer Stiftung; series “Climate Change Mitigation in the Eastern Mediterranean”, https://www.kas.de/en/web/remena), different suggestions/recommendations for mitigation and adaptation measures have been outlined for each of the countries considered here. These publications basically address the impacts of climate change through national strategies and specific measures including: the utilization of renewable energy sources; enhancing energy efficiency; sustainable development, in general, and sustainable seawater desalination, in particular; smart and water saving irrigation technologies; reducing the threats of biodiversity losses and forest fires; and devising adaptation measures to safeguard the tourism sector. Given the current crisis in Israel and Palestine and uncertain future prospects for a less disturbed development in the region, projections for mitigation and adaptation measures for Palestine, in particular, remain largely hypothetical.

However, a common theme in recent studies addressing measures to reduce adverse climate change impacts, is the need for more cooperation, both bi- and multi-laterally. While the EU members Cyprus and Greece follow the European Green Deal of the European Commission and the mitigation strategy outlined therein, the other countries strive to develop closer ties to their neighboring countries and/or the European Union. The “Eastern Mediterranean and Middle East Climate Change Initiative”, proposed by the Republic of Cyprus, offers a possible mechanism to advance such cooperation in the region.

How to cite: Lange, M.: Climate Change Mitigation and Adaptation in the Eastern Mediterranean: The Need for Cooperation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8085, https://doi.org/10.5194/egusphere-egu24-8085, 2024.

EGU24-8253 | ECS | Posters on site | CL4.12 | Highlight

Categorization Framework of Adaptation Measures in Urban Dry Arid Climate  

Shiran Nadler Realpe and Yosef Jabareen

Since the rise of the global climate change crisis, it has become urgent that cities apply climate-change-oriented adaptation measures as an integral part of their planning and development endeavors. Specifically, this study focuses on arid-dryland climate regions that are considered with high confidence to face a disproportionately high risk due to climate change impacts. A critical review of the literature on urban adaptation measures reveals that adaptation measures applicable to the context of the arid urban environment are spread out across various studies. Yet, there needs to be a comprehensive framework that unifies, categorizes, and further contextualizes them regarding planning parameters. Therefore, this paper aims to provide a unified framework for adaptation measures that constitute the scientific knowledge base for climate-focused city planning and development and are adjusted to the requirements of hot and dry arid environments. The review of adaptation measures for arid urban areas identified four major adaptation categories: The building code, the urban design category, the green infrastructure category, and the sustainable water management category. The outcome of our proposed procedure is the construction of inclusive adaptation categories tables that include arid-oriented climate change adaptation measures and their related planning parameters. Here, we provide the necessary landmarks for applying adaptation measures to cope with climate change threats regarding the planning of hot and dry arid climate cities.

 

How to cite: Nadler Realpe, S. and Jabareen, Y.: Categorization Framework of Adaptation Measures in Urban Dry Arid Climate , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8253, https://doi.org/10.5194/egusphere-egu24-8253, 2024.

Mediterranean coastal lagoons play a pivotal role in the environmental, social, and economic facets of the coastal areas.  In general, coastal lagoons serve as biodiversity hotspots, supporting diverse ecosystems, including wetlands, marshes, seagrass beds, and unique fauna. They function as carbon sinks, sequestering substantial amounts of atmospheric carbon dioxide. Coastal lagoons also act as hydrological regulators, serving as natural buffer zones during extreme weather events, regulating hydrological cycles, and minimizing the impacts of flooding.  Mediterranean coastal lagoons hold significant socio-economic value, providing essential fishing grounds and supporting local fishing communities, and as tourist. Finally, coastal lagoons have been integral to Mediterranean cultures for centuries, holding historical and cultural significance. Understanding the impacts of climate change on coastal lagoon is crucial for coastal planning and adaptation strategies. In this study artificial neural networks (ANNs)are applied to estimate the impacts of anthropogenic climate change on water masses characteristics of coastal lagoon. Specifically, ANNs are used to model the associations between climate variables and water mass properties (namely temperature and salinity), which can be used for future projections. The developed ANNs approach can be applied to generic coastal lagoons, if sufficient in situ data of temperature, salinity and sea level are available for developing the model. The driving meteorological variable can be extracted from meteorological reanalysis and model climate projections if their resolution is sufficient to describe the relevant mesoscale features. The method is applied to the Venice Lagoon, the largest Mediterranean lagoon. The Venice lagoon is an ecologically and socio-economically relevant environment with notable susceptibility and a comprehensive description of climate change impacts is essential for its conservation and sustainable management. An advantage of the Venice lagoon is the relative richness of in situ observations, because of extensive past field campaigns. Here we provide and estimate of the expected changes of its temperature and salinity that are produced by low and high climate change scenario, with corresponding uncertainties. The ANN was parameterized using a combination of field data of temperature, salinity, and sea level, along with reanalysis data for ground temperature, wind speed (v and u components), temperature at 2 m, precipitation, evaporation, and humidity. Field data were obtained from a 10-year monitoring campaign, during which 30 stations within the lagoon were sampled. Reanalysis data were downloaded from the Copernicus ERA5 database. The climate scenarios used for projections were obtained from the Med-CORDEX network.

How to cite: Bozzeda, F., Sigovini, M., and Lionello, P.: Application of artificial neural networks for modeling the climate change impacts on Mediterranean coastal lagoons:  the Venice Lagoon example., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12335, https://doi.org/10.5194/egusphere-egu24-12335, 2024.

EGU24-13371 | ECS | Posters on site | CL4.12 | Highlight

Emerging extreme climate-related stresses over croplands and wheat-harvested areas in the southern Mediterranean region during the 21st century 

Behnam Mirgol, Bastien Dieppois, Jessica Northey, Jonathan Eden, Lionel Jarlan, Saïd Khabba, Michel Le Page, and Gil Mahé

The frequency and intensity of extreme weather events have noticeably risen in recent decades across the globe, especially over the southern Mediterranean region. This trend poses a threat to plant growth, affecting both the physical and metabolic aspects of plants. With the global necessity to double food production by 2050 to meet growing population demands and changing diets, it becomes crucial to understand further how and when significant changes affecting multiple climate-stress indicators may emerge over croplands and some strategic crops for the southern Mediterranean region, such as wheat.

This paper, therefore, aims to identify the spatial distributions and timings of significant positive and negative climate-related stresses affecting croplands and wheatlands. Using 17 bias-corrected climate models from the Coupled Model Intercomparison Project phase 6 (CMIP6) under the SSP370 scenario, we examine a series of agronomically-relevant climate indicators, characterising the intensity of heatwaves, coldwaves, drought, and heavy rainfall, as well as the frequency of such event to combine at the annual scale and during the reproductive phase of winter wheat. Using observed and projected land-use land-cover scenarios, we then quantify the fraction of croplands and wheat-harvested areas that could potentially be affected by positive and negative changes in these climate-stress indicators.

Overall, our analysis revealed predominantly consistent upward trends in heatwave intensity, maximum drought intensity, and the occurrence of compound Dry and Hot (DH) events expected to emerge in the early future (before 2030). Similarly, the number of Wet and Hot (WH) events exhibits an increasing trend, although not as uniform as the indicators above, and is expected to emerge predominantly in the mid-future (before 2050). Conversely, maximum frost intensity, the number of Wet and Cold (WC) and Dry and Cold (DC) events reveal consistent declining trends over the region emerging mostly in the early future (before 2030).

How to cite: Mirgol, B., Dieppois, B., Northey, J., Eden, J., Jarlan, L., Khabba, S., Le Page, M., and Mahé, G.: Emerging extreme climate-related stresses over croplands and wheat-harvested areas in the southern Mediterranean region during the 21st century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13371, https://doi.org/10.5194/egusphere-egu24-13371, 2024.

EGU24-15023 | ECS | Posters on site | CL4.12

Changes in Holocene sediment deposition in the Aegean Sea: climatic versus early anthropogenic forcing 

Daniela J. M. Müller, Andreas Koutsodendris, Stefanie Kaboth-Bahr, and Jörg Pross

Since the Lateglacial, the Eastern Mediterranean region has been subject to repeated climatic and environmental change. It is also home to some of the earliest cultural centres in human history. These cultures have closely interacted with their environment, but it is still unclear to what extent climatic change has influenced their evolution. At the same time, the onset and extent of early anthropogenic impact on terrestrial and notably in marine ecosystems is still poorly constrained. In order to decipher the impact of early societies on sediment deposition in the Aegean Sea versus climatically driven changes in sedimentation, we have analyzed five sediment cores from coastal settings in the Aegean Sea retrieved during METEOR expeditions M144 (in 2017/18) and M195 (2023), as well as Eurofleets+ cruise ‘MYRTOON’ (2021). Spanning the entire Holocene and partially even dating back to ~13 ka, these cores exhibit extraordinarily high sedimentation rates. We have carried out grain-size analysis at decadal resolution to obtain insight into the different processes underlying sediment transport and deposition (e.g., fluvial versus aeolian, naturally versus anthropogenically induced).

For all cores, the application of end-member modelling shows clusters of grain-size distributions of c. 2 µm and 21 µm with distinct variability over time linked to changes in fluvial  and dust input. The finer grain-size end-member is interpreted to represent fluvial input, with the coarser material having been deposited proximally near the river mouths and the finer fraction remaining in suspension and being transported over longer distances into more distal settings. We find finer sediments during the deposition of sapropel S1 at ~10–6 ka BP, suggesting higher fluvial input into the Aegean Sea during that time. In contrast, a stronger prevalence of coarser-grained sediments from ~6 ka BP onwards suggest a decrease in fluvial input at that time. Notably, intervals with finer sediments appear during the past ~4 ka at sites located closer to the coast, whereas such intervals do not occur at sites from more distal settings. This suggests that the proximal sites are sensitive recorders of early anthropogenic forcing during the Late Holocene, as a result of erosion due to deforestation. These sedimentological results are currently augmented by ongoing x-ray fluorescence (XRF) core scanning and x-ray diffraction (XRD) analyses that will provide element geochemical insight into changes in detrital input connected to sediment provenance.

How to cite: Müller, D. J. M., Koutsodendris, A., Kaboth-Bahr, S., and Pross, J.: Changes in Holocene sediment deposition in the Aegean Sea: climatic versus early anthropogenic forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15023, https://doi.org/10.5194/egusphere-egu24-15023, 2024.

EGU24-15909 | ECS | Posters virtual | CL4.12

Holocene Sapropel Deposition in The Gulf of Kuşadası: Evidence from Sediment Cores Multi-Proxy Data 

Furkan Hoşer, Kürşad Kadir Eriş, Gülsen Uçarkuş, Nurettin Yakupoğlu, Dursun Acar, Asen Sabuncu, Denizhan Vardar, Devrim Tezcan, and Derman Dondurur

Holocene sedimentary records were obtained by three sediment cores retrieved from Gulf of Kuşadası (Aydın, Turkey), located in the SW part of the Aegean Sea. The sediment cores taking several depths were examined by using multi-proxy analyses to investigate paleoclimatic and palaeoceanographic changes, took place during the last 12 ka before present (BP). The µ-XRF data together with Total Organic Carbon (TOC) contents of the sediment cores reveals the deposition of two discrete sapropels in the gulf that timely coincide with the middle (SMH) and early Holocene (S1) sapropel layers previously described elsewhere from the Aegean and Mediterranean seas. The deposition of those sapropels is associated with high climate oscillations that gave rise to different palaeoceanographic conditions in the gulf as inferred from the multi-proxy dataset. The beginning of the Holocene is represented by elevated lithogenous elements (e.g. K and Ti in µ-XRF) values whereas gradual increases in biogenic calcite production together with partly higher TOC content imply marine organic productivity that was possibly provided by warm and wet climate conditions until the deposition of early Holocene sapropel (S1). The remarkable high value in µ-XRF Sr could be attributed to elevated salinity during the post-glacial warming that in turn may have given rise to increasing marine organic productivity. The climatic deterioration to a cooler and drier phase during the early to middle Holocene is assigned to the deposition of the S1 sapropel based on the TOC content of the core that is subdivided into two halves, S1a and S1b, respectively. The prominent increase in µ-XRF Fe/Mn in the initial half of the S1 implies that deposition of the S1a took place under a relatively poorly-oxygenated deep water condition in the gulf whereas it becomes relatively sub-oxic during the latter half of the sapropel deposition (S1b). The mid-to-late Holocene is represented by the deposition of the younger sapropel layer (SMH) in the gulf which is represented by a lower TOC content in comparison to the older sapropel layer (S1). Its initial deposition in the gulf is associated with more oxygenated deep water conditions under warmer and drier climates as depicted by higher µ-XRF Sr and lower Ca element values. After a short-term interruption, the deposition of the latter half of the SMH is represented by a lesser TOC content and increasing lithogenous elements (e.g., µ-XRF K and Ti) as a result of a relatively wetter climate during the latest Holocene. In contrast, the lower µ-XRF Ca and Ca/Ti values strongly suggest decreased marine organic productivity, thus, the main source of the organic matter was possibly derived from the detrital supply in contrast to the older sapropel (S1). The SMH sapropel deposition in the gulf was followed by increasing humidity with warmer climatic conditions, even though oxygenated deep-water conditions could not have allowed for better preservation of marine organic matter.

How to cite: Hoşer, F., Eriş, K. K., Uçarkuş, G., Yakupoğlu, N., Acar, D., Sabuncu, A., Vardar, D., Tezcan, D., and Dondurur, D.: Holocene Sapropel Deposition in The Gulf of Kuşadası: Evidence from Sediment Cores Multi-Proxy Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15909, https://doi.org/10.5194/egusphere-egu24-15909, 2024.

EGU24-16866 | Posters on site | CL4.12

Mediterranean Climate Regions in CMIP6 experiments: assessment of future changes and associated uncertainties 

Annalisa Cherchi, Andrea Alessandri, Valerio Lembo, Simone Gelsinari, and James Renwick

The mean climate characteristics of the Mediterranean region with temperate, wet winter and warm (or hot) dry summer is common to other regions of the world, like the west coast of North America, central Chile, the far southwest tip of Southern Africa and southwest Australia, which are all identified as Mediterranean climate regions (MCRs). Following from the Koppen-Geiger classification of climates, they share similar location and lie on the western edge of continents in the subtropics to mid-latitude thus being overall transition areas between wet and dry climates. In a previous work, with a probabilistic approach, we have quantified the risk of a poleward shift of MCRs, mostly over the Mediterranean region and western North America, with the equatorward margins replaced by arid climate type using CMIP5 21st century projections.

Following on from the above and using newly available CMIP6 simulations we have designed an update of the assessment of future climate changes in MCRs. The objective is to identify how MCRs are projected to change in CMIP6 simulations either in terms of hydroclimate conditions and of expansion or retreat of the areas considering the high impact these changes may have on water resources, ecosystem and human livelihood over these vulnerable climate regions. On top of the overall picture of hydroclimate changes over the regions with commonalities and differences, as expected from current dynamical understanding, we will provide an evaluation of the uncertainties in the projections and estimates of the models’ reliability in representing observed past changes. 

How to cite: Cherchi, A., Alessandri, A., Lembo, V., Gelsinari, S., and Renwick, J.: Mediterranean Climate Regions in CMIP6 experiments: assessment of future changes and associated uncertainties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16866, https://doi.org/10.5194/egusphere-egu24-16866, 2024.

EGU24-17641 | ECS | Posters on site | CL4.12

Environmental conditions controlling Cold-water corals occurrence in western Melilla (western Mediterranean) since the last deglaciation. 

Mar Selvaggi, Maria de la Fuente, Albert Català, José Noel Pérez-Asensio, Claudio Lo Iacono, Negar Haghipour, Sergi Trias-Navarro, Guillem Corbera, Letizia Di Bella, and Isabel Cacho

Cold-water coral (CWC) mounds are widely distributed in the eastern Alboran Sea (westernmost Mediterranean), specifically in the so-called East and West Melilla CWC mound provinces (EMCP, WMCP). Here we present a study on the environmental changes that occurred in the WMCP since the last deglaciation (~14 kyr BP), based on the analysis of the sediment core MD13-3451 (370 m water depth). The reconstructed palaeoceanographic changes allowed for the identification of diverse circulation patterns, which potentially influenced the life and demise of CWC communities in the WMCP. The analyses performed include sediment grain-size, geochemical measurements in foraminifera coating (U/Mn ratio) and calcite (stable isotopes, Mg/Ca-derived Deep Water Temperatures; DWTs), and the assessment of benthic foraminiferal species assemblages tolerating low-oxygen conditions (relative abundance of Globobulimina affinis). Furthermore, seawater δ18O (δ18Osw) and seawater δ18O corrected for the ice volume signal (δ18Ow-ivc) have been estimated via paired analyses of Mg/Ca and δ18Ocarbonate. Our findings suggest: i) the occurrence of pulses of relatively high DWTs, moderate to strong bottom water hydrodynamics and well-oxygenated waters favored a suitable environment for CWCs during the Early Holocene (EH), ii) a rapid freshening of the waters occurred during the EH, indicating major oceanographic changes. These results, when combined with available records from neighboring sites, reveal that such flourishing stage is closely coupled to a re-organization of the Alboran Sea water column structure. More precisely, the emergence of a newly formed water mass probably originated in the Gulf of Lion (northwestern WM) most likely replaced the older Levantine Intermediate Water (LIW) and might have also promoted the reactivation of CWC growth. Overall, our results highlight the crucial role of the Mediterranean circulation and stratification in controlling the temporal development of CWC mounds in the southern Alboran Sea, and also emphasize the importance of integrating a wide range of environmental variables and spatial scales when investigating these complex ecosystems.

How to cite: Selvaggi, M., de la Fuente, M., Català, A., Pérez-Asensio, J. N., Lo Iacono, C., Haghipour, N., Trias-Navarro, S., Corbera, G., Di Bella, L., and Cacho, I.: Environmental conditions controlling Cold-water corals occurrence in western Melilla (western Mediterranean) since the last deglaciation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17641, https://doi.org/10.5194/egusphere-egu24-17641, 2024.

EGU24-17746 | Orals | CL4.12

Large-scale atmospheric circulation changes in the northern Mediterranean realm during the Younger Dryas: new insights from Lago Grande di Monticchio (Italy) 

Cecile Blanchet, Marc-André Cormier, Zuobing Liang, Xueru Zhao, Tjallingii Rik, Arne Ramisch, Sabine Wulf, Markus Schwab, Achim Brauer, and Dirk Sachse

The Mediterranean region is recognized as a climate change hotspot, where temperatures increase faster than the global average. Modelling experiments suggest that such rapid and drastic changes will induce droughts and extreme rainfall events in this vulnerable region. Records of past climatic changes are useful to determine the speed and mode of regional responses and climatic sensitivities. We examine here the response of southern European hydroclimate to large-scale oceanic disturbances and rapid climatic changes during the Younger Dryas (YD) interval (e.g., 14-11 ka BP).

We present new results from Lago Grande di Monticchio (Italy) that allow us to explore the dynamics of precipitation at high temporal resolution. By combining multiple tracers (hydrogen isotope ratios of leaf waxes, X-ray fluorescence scanning, microfacies analyses, tephrochronology), we were able to determine both rainfall dynamics and sedimentary and environmental responses. We identified a pronounced positive shift in hydrogen isotope ratios (expressed as δD values) during the YD cold period of ca. 20 ‰ between 12.6 and 11.5 ka BP. We interpret this to reflect to a decrease in the input of north Atlantic moisture (a significant contributor to annual rainfall at present) and lower overall precipitation amount. This coincides with an increase in the varve thickness and occurrence of organic-clastic microfacies. The presence of marker tephra layers in the record (esp. the Neapolitan Yellow Tuff and Pomici Principali) provides important temporal tie-points that enable us to compare local hydroclimatic responses across the wider region. In particular, the observed drying trend at Monticchio is in striking contrast to more humid conditions north of the Alps in western, central and eastern Europe, potentially reflecting the southward migration of synoptic climatic systems (westerlies) and the presence of sea-ice in the moisture source region.

How to cite: Blanchet, C., Cormier, M.-A., Liang, Z., Zhao, X., Rik, T., Ramisch, A., Wulf, S., Schwab, M., Brauer, A., and Sachse, D.: Large-scale atmospheric circulation changes in the northern Mediterranean realm during the Younger Dryas: new insights from Lago Grande di Monticchio (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17746, https://doi.org/10.5194/egusphere-egu24-17746, 2024.

EGU24-18396 | Orals | CL4.12 | Highlight

Projected Increases in Population Exposure to Droughts in the Iberian Peninsula under 1.5ᵒ and 2ᵒC Global Warming Levels 

Ana Russo, Virgílio A. Bento, Andreia Ribeiro, Daniela C.A. Lima, João A. Careto, Pedro M.M. Soares, Renata Libonati, Ricardo M. Trigo, and Célia M. Gouveia

Increasingly frequent and intense drought events at a global scale emphasize the heightened vulnerability and exposure of ecosystems and human populations. In Southern Europe, identified as a significant climate change 'hotspot', particularly within the Iberian Peninsula (IP), droughts are a recurring and impactful type of extreme weather events. Anticipated shifts in climate patterns and the occurrence of extreme weather events are expected to cause profound environmental and socio-economic consequences. This study investigates the impacts of 1.5ᵒ and 2ᵒC Global Warming Levels (GWL) at the end of the 21st century on drought events and population exposure to dry extreme events in the IP.

For this research, EURO-CORDEX experiments (13 simulations) were considered and aggregated as a weighted multi-variable multi-model ensemble, encompassing different time periods, namely the historical period from 1971 to 2000, 30-year periods centred on the 1.5ᵒ and 2ᵒC GWL years, and the projected end of the century period spanning 2066 to 2095. Two drought indicators, the Standardized Precipitation Index (SPI) and the Standardized Precipitation-Evapotranspiration Index (SPEI) are used to characterize droughts. Three representative scenarios are employed to delineate distinct greenhouse gas emission trajectories. This study uses Eurostat's demographic projections covering the period up to 2100 with 5-year intervals starting in 2020 for Portugal and Spain. The study supplements historical population values with The World Bank data until 2011.

For the RCP8.5 scenario, changes in the number of moderate, severe, and extreme droughts are projected to grow throughout the century, with 24 to 33 % (58 to 69 %) in the case of SPI (SPEI). This escalation reflects an overwhelming growth of drought occurrences in the IP because of the 0.5°C additional warming. Population exposure to extreme droughts is higher under the 2ᵒC scenario than under the 1.5ᵒC scenario, particularly as measured by SPEI, reflecting again the importance of the expected increase of the temperature in the IP. Population exposure to extreme droughts in the end of the century can vary between an increase of 50 % and more than 600 % for SPEI with timescales of 3 to 12-months under RCPs 4.5 and 8.5.

The findings of this study reveal a notable projected surge in population exposure to droughts throughout the entire IP, particularly by the end of the century, with climate change identified as the predominant factor for this escalation. The findings underscore the urgency for regional authorities, policymakers, and society to prioritize adaptation planning and develop a comprehensive understanding of the vulnerabilities and potential strategies to cope with the challenges posed by dry extreme events.

 

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020), UIDP/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020). This work was performed under the scope of project https://doi.org/10.54499/2022.09185.PTDC (DHEFEUS) and supported by national funds through FCT. DL and AR acknowledge FCT I.P./MCTES (Fundação para a Ciência e a Tecnologia) for the FCT, 2022.03183.CEECIND/CP1715/CT0004 (https://doi.org/10.54499/2022.03183.CEECIND/CP1715/CT0004) and (https://doi.org/10.54499/2022.01167.CEECIND/CP1722/CT0006 (Complex), respectively.

How to cite: Russo, A., Bento, V. A., Ribeiro, A., Lima, D. C. A., Careto, J. A., Soares, P. M. M., Libonati, R., Trigo, R. M., and Gouveia, C. M.: Projected Increases in Population Exposure to Droughts in the Iberian Peninsula under 1.5ᵒ and 2ᵒC Global Warming Levels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18396, https://doi.org/10.5194/egusphere-egu24-18396, 2024.

EGU24-18437 | Orals | CL4.12 | Highlight

A Later Onset of the Rainy Season in California 

Jelena Lukovic, John Chiang, Dragan Blagojevic, and Aleksandar Sekulic

Californian hydroclimate is strongly seasonal and prone to severe water shortages. Recent changes in climate trends have induced shifts in seasonality, thus exacerbating droughts, wildfires, and adverse water shortage effects on the environment and economy. Previous studies have examined the timing of the seasonal cycle shifts mainly as temperature driven earlier onset of the spring season. In this paper, we address quantitative changes in the onset, amounts, and termination of the precipitation season over the past 6 decades, as well as the large-scale atmospheric circulation underpinning the seasonal cycle changes. We discover that the onset of the rainy season has been progressively delayed since the 1960s, and as a result the precipitation season has become shorter and sharper in California. The progressively later onset of the rainy season is shown to be related to the summer circulation pattern extending into autumn across the North Pacific, in particular, a delay in the strengthening of the Aleutian Low and later southward displacement of the North Pacific westerlies.

How to cite: Lukovic, J., Chiang, J., Blagojevic, D., and Sekulic, A.: A Later Onset of the Rainy Season in California, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18437, https://doi.org/10.5194/egusphere-egu24-18437, 2024.

EGU24-19598 | Posters on site | CL4.12

Heat content and temperature trends for different depth layers in the Mediterranean Sea 

Sebastian Mieruch, Elisabeth Kubin, Milena Menna, Elena Mauri, Giulio Notarstefano, and Pierre-Marie Poulain

The Mediterranean Sea is very sensitive to climatic changes due to its semi-enclosed nature and is therefore defined as one of the hotspots in future climate change projections. In this study, we use Argo float data to assess climatologies and trends in temperature and Ocean Heat Content (OHC) throughout the Mediterranean Sea and for specific sub-basins (e.g. Western and Eastern Mediterranean, Gulf of Lion, South Adriatic). The amount of the OHC, spatially averaged in bins of 1°x1° over the period from 2001 to 2020, increases from west to east in the Mediterranean Sea. Time series of temperature and OHC from 2005 to 2020, estimated in the surface and intermediate layers (5-700 m) and deeper layer (700-2000 m), reveal significant warming trends and an increase of OHC. The upper 700 m of the Mediterranean Sea show a temperature trend of 0.041±0.012 °C·yr-1, corresponding to an annual increase in OHC of 3.59±1.02 W·m-2. The Western Mediterranean Sea (5-700 m) is warming fastest with an increase in temperature at a rate of 0.070±0.015 °C·yr-1, corresponding to a yearly increase in OHC of 5.72±1.28 W·m-2. Mixing and convection events within convection sites and along boundary currents transport and disperse the temperature and OHC changes. Significant warming trends are evident in the deeper layers (700-2000 m) of the two deep convection sites in the Mediterranean Sea (Gulf of Lion, South Adriatic), with an exceptionally strong warming trend in the South Adriatic from 2013 to 2020 of 0.058±0.005 °C·yr-1, corresponding to a yearly increase in OHC of 9.43±0.85 W·m-2

The warming of the different water masses will show its feedback on ocean dynamics and air-sea fluxes in the next years, decades, and even centuries as these warming waters spread or re-emerge. This will provide more energy to the atmosphere, resulting in more extreme weather events and will also stress ecosystems and accelerate the extinction of several marine species. This study contributes to a better understanding of climate change in the Mediterranean region, and should act as another wake-up call for policy makers and society.

How to cite: Mieruch, S., Kubin, E., Menna, M., Mauri, E., Notarstefano, G., and Poulain, P.-M.: Heat content and temperature trends for different depth layers in the Mediterranean Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19598, https://doi.org/10.5194/egusphere-egu24-19598, 2024.

EGU24-20558 | Orals | CL4.12

Learning from past changes in Mediterranean Thermohaline Circulation 

Isabel Cacho, Leopoldo Pena, Jaime Frigola, Albert Català, Maria de la Fuente, Sergi Trias, Sara Campderrós, Mar Selvaggi, Judit Torner, Giulia Margaritelli, José Noel Pérez-Asensio, Guillem Corbera, Dimitris Evangelinos, and Fabrizio Lirer

Mediterranean thermohaline circulation is a very sensitive system to changes in regional climate conditions. The current warming conditions have already been transferred into the deep water properties, and future projections indicate an overall weakening of this circulation system. In this context, it becomes extremely relevant understanding the natural range of variability of this system and the interplay between the different basins and sub-basins controlling deep and intermediate convection in the Mediterranean Sea. Here we use the past record as a natural laboratory to learn on the impact that different climate forcings had in this circulation system, and also evaluating its consequences in the Mediterranean Outflow Water (MOW) and thus in the Atlantic oceanography. These are the main results of the ERC-Consolidator grant TIMED, devoted to understanding of past changes in Mediterranean thermohaline circulation. This new data set is based in a variety of proxies that are sensitive to ocean circulation changes such as U/Mn ratios measured in the foraminifera diagenetic coatings, Nd isotopes, absolute dating on deep sea corals, among other geochemical and sedimentological tools applied in sediment cores from both E- and W-Med. The obtained results indicate the deglacial development of an intense minimum oxygen zone in the W-Med associated to the LIW which extended down to at least 950m. These evidences support by the first time, that the formation of the deglacial Organic Rich Layer was also connected to a weakening of E-Med convection, this would indicate a long pre-conditioning prior to the last Sapropel (S1) that would start with last Heinrich event in the North Atlantic and fully develop with the onset of the African humid period. We identify that an intense aridification and cooling of the E-Med driven by the AMOC weakening of the Younger Dryas was responsible of a strong reactivation of E-Med convection that resulted in a stronger MOW, and also triggered enhanced deep intermediate convection in the W-Med. This circulation change pushed out an old water mass previously accumulated in the Med for several centuries with major consequences in deep ecosystems sustained by deep sea corals. The onset of the last S1 in the E-Med led to major changes in deep convection in both E and W-Med, but with opposite sign in their response. These results highlight the tide connection between the AMOC and E-Med convection and rise questions on the potential role that the associate changes in the MOW could have on the AMOC, particularly during weak stages.

How to cite: Cacho, I., Pena, L., Frigola, J., Català, A., de la Fuente, M., Trias, S., Campderrós, S., Selvaggi, M., Torner, J., Margaritelli, G., Pérez-Asensio, J. N., Corbera, G., Evangelinos, D., and Lirer, F.: Learning from past changes in Mediterranean Thermohaline Circulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20558, https://doi.org/10.5194/egusphere-egu24-20558, 2024.

EGU24-435 | Posters on site | CL4.14

Updating the assessment of climate change at decadal scale and consolidating with CMIP6 future projections 

María Ofelia Molina, Pedro MM Soares, Miguel M Lima, Daniela CA Lima, Tomás Gaspar, and Ricardo Trigo

NASA’s scientist James E. Hansen (named ‘The father of climate change’) has become widely recognized due to his many relevant contributions to climate change topics. In particular, his studies of recent changes of temperature at the decadal-scale published in 2012 and 2016, detected the emergence of a new kind of summertime extremely hot events which would not have occurred in the absence of global warming. Here, we update and extend the analysis of these studies using the latest reanalysis data from ECMWF (ERA5) from 1951 to 2020, at a higher spatial resolution. In addition, we put these results in context of state-of-the-art climate change modelling studies by considering future climate projections through the Coupled Model Intercomparison Project Phase 6 (CMIP6) Global Climate Models (GCMs).

Climate spatio-temporal variability for each continent is studied by evaluating the decadal frequency distributions of monthly 2-m temperature anomalies for the 1951-2020 historical period and for 2015-2100 future period. To achieve this, monthly averaged daily temperature data from ERA5, and the historical, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 future climate scenarios from an ensemble of CMIP6 GCMs are used. For producing spatial analyses, all ERA5 and CMIP6 data were previously regridded to a common 100 km lat/lon regular grid using conservative remapping.

The results of ERA5 show a decadal shift in the mean temperature anomalies towards warmer values at continental scale, much more pronounced in the last decade (2011-2020), and larger in summer than in winter. By using a frequency distribution-based score, it is seen that the CMIP6 model ensemble is able to reproduce this historical warming, at a climatological timescale, with a large degree of agreement for all continents. Furthermore, climate projections strongly indicate that this warming will continue in the future under any climate change scenario and will be larger by the end of the century. The two most likely scenarios (SSP2-4.5 and SSP3-7.0) show significant evidences that extremely hot temperatures (anomalies of more than three standard deviations (3σ) warmer than the climatology of the 1951–1980 base period) will become the normal climate in Africa and South America regions for the 2071-2100 period. In this work, it is seen that the regional mean temperature anomalies will increase in weak, moderate and strong forcing scenarios, reaching climatic extremes with expected major implications on the water cycle, agriculture, ecosystems, society and human health.

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 and the DRI/India/0098/2020 project (https://doi.org/10.54499/DRI/India/0098/2020).

How to cite: Molina, M. O., Soares, P. M., Lima, M. M., Lima, D. C., Gaspar, T., and Trigo, R.: Updating the assessment of climate change at decadal scale and consolidating with CMIP6 future projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-435, https://doi.org/10.5194/egusphere-egu24-435, 2024.

EGU24-1703 | Orals | CL4.14

Origins of Barents-Kara sea-ice interannual variability modulated by the Atlantic pathway of ENSO 

Binhe Luo, Cunde Xiao, Dehai Luo, Aiguo Dai, Ian Simmonds, and Lixin Wu

Winter Arctic sea-ice concentration (SIC) decline plays an important role in Arctic amplification which, in turn, influences Arctic ecosystems, midlatitude weather and climate. SIC over the Barents-Kara Seas (BKS) shows large inter- annual variations, whose origin is still unclear. Here we find that interannual variations in winter BKS SIC have significantly strengthened in recent decades likely due to increased amplitudes of the El Niño-Southern Oscillation (ENSO) in a warming climate. La Niña leads to enhanced Atlantic Hadley cell and a positive phase North Atlantic Oscillation-like anomaly pattern, together with concurring Ural blocking, that transports Atlantic ocean heat and atmospheric moisture toward the BKS and promotes sea-ice melting via intensified surface warming. The reverse is seen during El Niño which leads to weakened Atlantic poleward transport and an increase in the BKS SIC. Thus, interannual varia- bility of the BKS SIC partly originates from ENSO via the Atlantic pathway.

How to cite: Luo, B., Xiao, C., Luo, D., Dai, A., Simmonds, I., and Wu, L.: Origins of Barents-Kara sea-ice interannual variability modulated by the Atlantic pathway of ENSO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1703, https://doi.org/10.5194/egusphere-egu24-1703, 2024.

EGU24-2183 | Posters on site | CL4.14

Climate sensitivity to extreme temperature changes 

Xiaodan Guan, Chenyu Cao, and Yanli Ma

In recent decades, a high frequency of extreme high temperature has occurred in many regions worldwide with serious impacts on society and the economy. As the temperature increases, the sensitivity of extreme high temperatures to changing thresholds in the northern mid-latitudes exhibits a different performance response. The results of this study show that extreme high temperature in the increasing phase is more sensitive to changes in the threshold in both observations and simulations (the largest difference in the speed of temperature increase occurs at 3.5 days and 25 days/decade), primarily in North America and Central Asia. This finding highlight that the old definition of being in the increasing temperature phase in modern climate history is problematic today. At the same time, when the old base period is selected, the frequency of extreme high temperatures will become a common event (close to 98% in a year) by 2100. Using 1961-1990 as the base period is not suitable for calculating extreme temperatures in the future from the perspective of adapting to climate change. The increasing temperature threshold means there will be more frequent hot days, indicates that agriculture and species will be negatively affected, more wildfires will occur, resulting in increased risks to humanity.

How to cite: Guan, X., Cao, C., and Ma, Y.: Climate sensitivity to extreme temperature changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2183, https://doi.org/10.5194/egusphere-egu24-2183, 2024.

EGU24-2235 | Orals | CL4.14

Impact of solar activity on extreme weather and climate events 

Ziniu Xiao and Liang Zhao

Extreme weather and climate events are the result of interaction of multiple scale anomalous signals. Solar activity presents a remarkable 11-year cycle, which is an important decadal background affecting the occurrence of extreme weather and climate events. A lot of study works show that the periodic variation of solar activity has a modulating effect on the ocean-atmosphere system. The decadal variation of major atmospheric and oceanic modes, such as ENSO, has a phase-locked relationship with the periodic variation of solar activity. A significant solar footprint can be found in the tropical Pacific and the North Atlantic. The analysis shows that the solar activity also modulates the regional temperature, precipitation and typhoon activity as well.

How to cite: Xiao, Z. and Zhao, L.: Impact of solar activity on extreme weather and climate events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2235, https://doi.org/10.5194/egusphere-egu24-2235, 2024.

EGU24-2283 | Orals | CL4.14

How Does Mei-yu Respond to Climate Change? 

Bo Sun

Mei-yu is an important weather phenomenon in the middle-lower Yangtze River valley (YRV) region. For instance, in 2020, extreme precipitation events frequently occurred in the YRV region during the Mei-yu period, which caused flood and resulted in over 200 deaths/missing persons and over 170 billion CNY of direct economic losses. Whereas in 2022, persistent high temperature and drought events occurred in the YRV region, which greatly affected the agriculture, hydropower, and human health in the YRV region. These extreme events during the Mei-yu period have brought severe challenges to the government for combating climate change.

This study investigates the changes in the characteristics of Mei-yu under global warming and the potential reasons based on observation and reanalysis data during 1961–2022. It is found that the number of days without rainfall (NDWOR), intensity of rainfall event, and frequency and intensity of extreme precipitation events (EPE) in the YRV region have increased significantly during the Mei-yu period (June 15–July 10) over past decades. These trends indicate that the weather during the Mei-yu period is becoming more unstable and extreme under global warming. Particularly, the increasing trends in intensity of rainfall events and EPE (NDWOR) account for a relatively large (small) portion of the variability of corresponding variables, suggesting that the increased rainfall intensity is a key feature in the response of Mei-yu to climate change.

The increasing trend of NDWOR during Mei-yu is attributed to decreased relative humidity. According to the Clausius-Clapeyron equation, the saturation specific humidity (qs) would dramatically increase as the global warming continues, at an increasing rate of approximately 7% per℃ rise in temperature. As qs increases more dramatically than q under global warming, the RH is decreased, which may lead to more days without rainfall during the Mei-yu period.

The increased intensity of rainfall event, and frequency and intensity of EPE may be correspond to the thermodynamic and dynamic effects in the YRV region during the Mei-yu period. Through analyzing the regional rainfall events in the relatively cold period of 1961–1980 and in the relatively warm period of 2001–2022, it is found that the transient southerly water vapor transport, water vapor convergence and enhanced convection in the troposphere associated with the regional rainfall events in the YRV region during the relatively warm period are notably larger than that during relatively cold period during the Mei-yu period.

Furthermore, the response of Mei-yu to 2℃ of global warming with respect to pre-industrial climate is analyzed using CMIP6 models. The results suggest that the NDWOR, intensity of rainfall events, and frequency of EPE will increase in the YRV region during the Mei-yu period under the 2℃ warming scenario, which imply a more challenging climate risk management in the future.

How to cite: Sun, B.: How Does Mei-yu Respond to Climate Change?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2283, https://doi.org/10.5194/egusphere-egu24-2283, 2024.

Daytime-nighttime compound heat waves (HWs) (i.e. concurrent occurrence of HWs both in daytime and nighttime) were documented to amplify the damages of high temperatures during daytime or nighttime. Nevertheless, the future change in compound HWs remains an open issue. This research presents the projected changes in compound HWs and associated population exposure in China under the shared socioeconomic pathway (SSP)2-4.5 and SSP5-8.5 scenarios based on the Coupled Model Intercomparison Project phase 6 simulations. The results generally indicate an aggravated risk of compound HWs in China in the future under warmer scenarios. Compound HWs in China are projected to increase significantly toward the end of the 21st century, with larger increase under SSP5-8.5 than that under SSP2-4.5. The greatest changes occur in northwestern China and southern China. Compared with the daytime HWs (i.e. occurring only in daytime) or nighttime HWs (i.e. occurring only in nighttime), the projected increase in compound HWs is the greatest. Accordingly, the proportion of compound HWs to the total HW events tends to increase and that of daytime HWs tends to decrease toward the end of the 21st century. Due to substantial increases in compound HWs, the population exposure to compound HWs will increase significantly across the entire country. The projected increase of nationally averaged population exposure is 12.2-fold (7.9-fold) of the current in the mid-century (2046–2065) and further enhances to 16.3-fold (12.4-fold) in the end-century (2081–2100) under SSP5-8.5 (SSP2-4.5). The largest increases are distributed in western China and southern China. These findings raise the necessity and urgency for policy-makers and the public to develop measurements to address compound HW risks.

How to cite: Xie, W.: Substantial increase in daytime-nighttime compound heat waves and associated population exposure in China , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2422, https://doi.org/10.5194/egusphere-egu24-2422, 2024.

EGU24-2635 | ECS | Posters on site | CL4.14

Intraseasonal Variability of Anticyclonic Rossby Wave Breaking and Its Impact on Tropical Cyclone Activity over the Western North Pacific 

Yitian Qian, Pang-chi Hsu, Hiroyuki Murakami, Gan Zhang, Huijun Wang, and Mingkeng Duan

The intraseasonal variations in anticyclonic Rossby wave breaking (AWB) events, which are characterized by synoptic-scale irreversible meridional overturning of potential vorticity over the North Pacific, and their modulations on tropical cyclone (TC) activity over the western North Pacific (WNP), were investigated in this study. Spectral analysis of the AWB frequency shows significant variability within a period of 7–40 days, closely linked to the subseasonal variability of the jet stream intensity. When the jet stream weakens at its exit region over the North Pacific, the AWB occurs along with an equatorward Rossby wave flux. This AWB is preceded by an intensified Rossby wave train across Eurasia 12 days earlier. Simultaneously, a high potential vorticity intrusion is advected in the upper troposphere from the North Pacific toward the WNP, and suppressed TC activities are observed over the WNP open ocean where decreased moisture and temperature, subsidence, and increased vertical wind shear prevail. In contrast, anomalously enhanced convection, positive relative vorticity, and ascending motion are found in the southwestern quadrant of the AWB, facilitating enhanced TC activities over the South China Sea (SCS). Further analysis indicates that the impact of the AWB on TC activities over the WNP is robust and independent of the tropical intraseasonal convection over the tropical Indian Ocean and SCS, even though it accompanies the increased AWB frequency.

How to cite: Qian, Y., Hsu, P., Murakami, H., Zhang, G., Wang, H., and Duan, M.: Intraseasonal Variability of Anticyclonic Rossby Wave Breaking and Its Impact on Tropical Cyclone Activity over the Western North Pacific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2635, https://doi.org/10.5194/egusphere-egu24-2635, 2024.

Accurate sub-seasonal (2-8 weeks) prediction of monsoon precipitation is crucial for mitigating flood and heatwave disasters caused by intra-seasonal variability (ISV). However, current state-of-the-art sub-seasonal-to-seasonal (S2S) models have limited forecast skills beyond one week when predicting ISV events. Here, we find, regardless of models, that the prediction skills for ISV events depend on the propagation stability of events’ preceding signals. This allows us to identify opportunities and barriers (OBs) within S2S models, understanding what the models can and cannot achieve in ISV event prediction. Focusing on the complex East Asian summer monsoon (EASM), we discover that stable propagation of Eurasian and tropical atmospheric wave trains towards East Asia serves as an opportunity, providing skillful prediction up to 13 days ahead. However, the Tibetan Plateau barrier highlights the limitation of EASM predictability. Identifying these OBs will help us gain confidence in making accurate sub-seasonal prediction.

How to cite: Liu, F.: Identifying opportunities and barriers for skillful sub-seasonal prediction of East Asian summer monsoon precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2659, https://doi.org/10.5194/egusphere-egu24-2659, 2024.

In the summer of 1998, heavy rainfall persisted throughout the summer and resulted in a severe prolonged flooding event over East Asia. Will a similar rainy summer happen again? To date, many studies have investigated projected changes in the seasonality or daily extreme precipitation events over East Asia; however, few studies have focused on the changes in extreme summer-averaged East Asian rainfall. This type of summer is referred to as a “heavy rainy summer (HRS)” in this study, and an investigation of future changes in its probability is performed by analyzing CMIP5 model outputs in historical climate simulation (HIST) and under RCP4.5 and RCP8.5.

All models project increased probabilities of HRS by a factor of two to three. The projected East Asian summer rainfall (EASR) (EASRRCPs−EASRHIST) in both climatology and HRS is expected to intensify significantly. The increased EASR could be attributed to significantly intensified water vapor transport (WVT) originating from the tropical Indian Ocean (TIO) and the eastern subtropical North Pacific (SNP), which is a result of the thermodynamic component. The WVT from the TIO would supply more moisture for EASR because of its stronger intensity and faster rate of increase. Meanwhile, the EASR anomaly in HRS relative to climatology (EASRHRS−EASRCLM) would increase by approximately 11%–33%. In HIST, the associated WVT anomaly, caused only by the dynamic component, converges moisture from adjacent land and ocean. However, under the RCPs, the WVT anomaly from the TIO, resulted from the thermodynamic component, would appear and increase by a factor of three to be comparable to the WVT anomaly from the eastern SNP. The latter would result from the dynamic component but increase by only half.

How to cite: Fu, Y.: Projected Increase in Probability of East Asian Heavy Rainy Summer in the 21st Century by CMIP5 Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2663, https://doi.org/10.5194/egusphere-egu24-2663, 2024.

EGU24-2996 | Orals | CL4.14

Intercomparison of multi-model ensemble-processing strategies within a consistent framework for climate projection in China 

Zhihong Jiang, Huanhuan Zhu, Laurent Li, Wei Li, Sheng Jiang, Panyu Zhou, Weihao Zhao, and Tong Li

Climate change adaptation and relevant policy-making need reliable projections of future climate. Methods based on multi-model ensemble are generally considered as the most efficient way to achieve the goal. However, their efficiency varies and inter-comparison is a challenging task, as they use a variety of target variables, geographic regions, time periods, or model pools. Here, we construct and use a consistent framework to evaluate the performance of five ensemble-processing methods, i.e., multimodel ensemble mean (MME), rank-based weighting (RANK), reliability ensemble averaging (REA), climate model weighting by independence and performance (ClimWIP), and Bayesian model averaging (BMA). We investigate the annual mean temperature (Tav) and total precipitation (Prcptot) changes (relative to 1995–2014) over China and its seven subregions at 1.5 and 2 °C warming levels (relative to pre-industrial). All ensemble-processing methods perform better than MME, and achieve generally consistent results in terms of median values. But they show different results in terms of inter-model spread, served as a measure of uncertainty, and signal-to-noise ratio (SNR). ClimWIP is the most optimal method with its good performance in simulating current climate and in providing credible future projections. The uncertainty, measured by the range of 10th–90th percentiles, is reduced by about 30% for Tav, and 15% for Prcptot in China, with a certain variation among subregions. Based on ClimWIP, and averaged over whole China under 1.5/2 °C global warming levels, Tav increases by about 1.1/1.8 °C (relative to 1995–2014), while Prcptot increases by about 5.4%/11.2%, respectively. Reliability of projections is found dependent on investigated regions and indices. The projection for Tav is credible across all regions, as its SNR is generally larger than 2, while the SNR is lower than 1 for Prcptot over most regions under 1.5 °C warming. The largest warming is found in northeastern China, with increase of 1.3 (0.6–1.7)/2.0 (1.4–2.6) °C(ensemble’s median and range of the 10th–90th percentiles) under 1.5/2 °C warming, followed by northern and northwestern China. The smallest but the most robust warming is in southwestern China, with values exceeding 0.9 (0.6–1.1)/1.5 (1.1–1.7) °C. The most robust projection and largest increase is achieved in northwestern China for Prcptot, with increase of 9.1%(–1.6–24.7%)/17.9% (0.5–36.4%) under 1.5/2 °C warming. Followed by northern China, where the increase is 6.0%(–2.6–17.8%)/11.8% (2.4–25.1%), respectively. The precipitation projection is of large uncertainty in southwestern China, even with uncertain sign of variation. For the additional half-degree warming, Tav increases more than 0.5 °C throughout China. Almost all regions witness an increase of Prcptot, with the largest increase in northwestern China.

How to cite: Jiang, Z., Zhu, H., Li, L., Li, W., Jiang, S., Zhou, P., Zhao, W., and Li, T.: Intercomparison of multi-model ensemble-processing strategies within a consistent framework for climate projection in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2996, https://doi.org/10.5194/egusphere-egu24-2996, 2024.

EGU24-3060 | ECS | Posters on site | CL4.14

Capability of regional climate models to reproduce three-dimensional (3D) characteristics of heat waves 

Ondřej Lhotka, Eva Plavcová, and Jan Kyselý

In this study, we evaluate capabilities of 9 CORDEX regional climate models (RCMs) with lateral boundary conditions provided by the ERA-Interim reanalysis to reproduce three-dimensional (3D) structures of heat waves in several European regions in the 1989–2008 period. Heat waves are defined based on positive temperature anomalies from the 95th percentile in near-surface, 850 hPa, and 500 hPa levels with temporal and spatial criteria imposed. Based on predominant locations of positive temperature anomalies, heat waves are classified into four types: i) near-surface, ii) lower-tropospheric, iii) higher-tropospheric, and iv) omnipresent. Characteristics of individual types (e.g. frequency, severity, typical length and occurrence within a summer season) are evaluated against the ERA5 reanalysis. We show contrasting patterns among individual RCMs, pointing to different roles of processes governing heat waves across these simulations.    

How to cite: Lhotka, O., Plavcová, E., and Kyselý, J.: Capability of regional climate models to reproduce three-dimensional (3D) characteristics of heat waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3060, https://doi.org/10.5194/egusphere-egu24-3060, 2024.

The atmospheric circulation significantly influences the snowpack over mid-high-latitude Eurasia. This study examines the characteristics of the leading subseasonal variability mode of boreal winter sea level pressure (SLP) and its influence on snowpack over mid-high-latitude Eurasia, using the fifth generation of European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) data and different snowpack datasets. The leading mode, characterized by a monopole pattern with a strong surface anomalous high centered near the Ural Mountains, exhibits a barotropic structure and extends from the surface to the tropopause. Above SLP and geopotential height anomalies propagate southeastward from the Barents-Kara Sea to East Asia. This leading SLP mode contributes to surface air temperature (SAT) and snowfall circulation anomalies over mid-high-latitude Eurasia. The latter two both directly influence on snowpack anomalies in situ. Over high latitude region, snowfall circulation anomaly is the dominant factor to control the snow depth anomaly. Over middle latitude region, both SAT and snowfall circulation anomalies lead to the snowpack anomaly. Furthermore, the response of snow depth to the leading subseaonal SLP mode occurs 2-5 days earlier than the response of snow cover to the same mode. In addition, it is suggested that the Arctic Oscillation (AO), East Atlantic/West Russia (EAWR) and Polar/Eurasia (PEU) pattern may contribute to the development of the leading SLP mode and subsequently influence snowpack anomalies.

How to cite: Yalu, R. and Xuejuan, R.: Subseasonal Variability of Sea Level Pressure and Its Influence on Snowpack over Mid-High-Latitude Eurasia during Boreal Winter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3314, https://doi.org/10.5194/egusphere-egu24-3314, 2024.

EGU24-3741 | ECS | Posters on site | CL4.14

Irreversibility of Extreme Precipitation in East Asia under Multi-Scenario to Carbon Neutrality 

Min-Uk Lee, Jong-Yeon Park, Han-Kyong Kim, Young-Hwa Byun, Hyun-Min Sung, Ji-Sook Park, and Woo-Jin Jeon

Extreme precipitation refers to a bipolar climate phenomenon in which a high amount of precipitation occurs in a short period or a drought persists for a long period. In a future climate with increased CO2 concentrations, the characteristics of extreme precipitation can undergo significant variations. This study focuses on East Asia (110°-150°E, 20°-50°N) and employs six indices from the Expert Team on Climate Change Detection and Indices (ETCCDI) to assess the reversibility of extreme precipitation events. The Carbon Dioxide Removal (CDR) experiment, simulated by the National Institute of Meteorological Sciences and the Korea Meteorological Administration (NIMS-KMA) climate model, involves increasing the CO2 concentration by 1% per year from the Pre-Industrial (PI) level and decreasing it from four different carbon-neutral points: A (44 years), B (51 years), C (70 years), and D (140 years) from the initial year. The NIMS-KMA simulation proves most effective among eight models from the Coupled Model Intercomparison Project Phase 6 (CMIP6). Results indicate that extreme precipitation indices respond nonlinearly to CO2 concentration, with intensity and frequency indices showing hysteresis. Reversibility is limited, and delayed carbon neutrality leads to increased irreversibility. Notably, the R99 frequency index exhibits the highest irreversibility, ranging from 10.61% to 29.50% from point A to point D. This suggests that postponing carbon neutrality may strengthen the central Pacific warming pattern, intensify subtropical high pressure in the northwest Pacific, and increase water vapor flow into East Asia.

 

How to cite: Lee, M.-U., Park, J.-Y., Kim, H.-K., Byun, Y.-H., Sung, H.-M., Park, J.-S., and Jeon, W.-J.: Irreversibility of Extreme Precipitation in East Asia under Multi-Scenario to Carbon Neutrality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3741, https://doi.org/10.5194/egusphere-egu24-3741, 2024.

A significant and striking seesaw pattern of winter surface air temperature (SAT) has emerged, featuring pronounced warming Arctic and cooling Eurasian (referred to as WACE). This study investigates the subseasonal SAT modes across the mid- and high-latitudes of Eurasia and their possible mechanisms based on daily reanalysis data from 1979 to 2022. Our results reveal that Eurasian winter SAT exhibits two distinct subseasonal modes, characterized by a correlated southeastward propagation of temperature and geopotential height anomalies (GHAs) in the middle and lower troposphere. Notably, 8 phases of the subseasonal SAT modes are identified to form a comprehensive life cycle from the Arctic to East Asia. The sixth phase of the subseasonal SAT modes is proved to be the key transition phase from the WACE pattern to its counterpart. Further analysis indicates that the subseasonal tropospheric potential height anomalies over the Arctic are determined by the anomalies of stratospheric potential height and the surface turbulent heat fluxes anomalies in the north Atlantic.

How to cite: Li, S., Hu, H., and Ren, X.: Subseasonal Modes of Winter Surface Air Temperature in Eurasia's Mid- and High-Latitudes: Contributions from the North Atlantic and Arctic Regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3810, https://doi.org/10.5194/egusphere-egu24-3810, 2024.

Containing elevated topography, the Tibetan Plateau (TP) has significant thermodynamic effects for regional weather and climate change, where understanding energy and water exchange process (EWEP) is an important prerequisite. However, estimation of the exact spatiotemporal variability of the land-atmosphere energy and water exchange over heterogeneous landscape of the TP remains a big challenge for scientific community. Focused on the above scientific question, a series of atmospheric scientific experiments and research programs have been conducted since the 1960s, quantitatively evaluating both the spatial distribution and the multi-timescale variation of EWEP via observation, remote sensing, and numerical simulation. Based on the three main approaches, the major advances on EWEP over the past 30 years are systematically summarized in this work. All these results advanced the understanding of different aspects of EWEP over the TP by using in situ measurements, multisource satellite data and numerical modeling. Future studies are recommended to focus on the optimization of the current three-dimensional comprehensive observation system, the development of advanced parameterization schemes and the investigation of EWEP on weather and climate changes over the TP and surrounding regions.

How to cite: Ma, Y.: The energy and water exchange and its effect on the weather and climate over the Tibetan Plateau and surrounding regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3834, https://doi.org/10.5194/egusphere-egu24-3834, 2024.

This study investigated the differences in the changes in the quasi-biweekly oscillation (QBWO) intensity over the western North Pacific during the developing late-summer (1982, 1997 and 2015) of three super El Niño events and the possible reasons. The late-summer QBWO intensity was enhanced in these three years and the enhanced QBWO intensity in 2015, which was the strongest during 1980–2017, was remarkably stronger than that in 1982 and 1997. This mainly resulted from the differences in the anomalous late-summer background atmospheric conditions over the northwestern tropical Pacific, which were further modulated by the differences in the sea surface temperature anomalies in the Pacific. While strong warming appeared in the central and eastern equatorial Pacific (CEEP) in these three years, the warming and its center extended further west in 2015. More importantly, the warming in the central and eastern North Pacific (CENP) in 2015 was the strongest during 1980–2017, whereas there was cooling in 1982 and moderate warming in 1997. In 2015, the strong and westward-extended warming in the CEEP and the strongest warming in the CENP led to the strongest increased lower-level moisture and anomalous easterly vertical shear over the northwestern tropical Pacific during 1980–2017, favoring the strongest QBWO intensity. Numerical experiments confirmed the role of warming in the CENP in 2015. Besides, the frequency of extreme precipitation events over southern China during the late-summer of 2015 was the maximum of 1980–2017 and was closely related to the enhanced QBWO intensity over the western North Pacific.

How to cite: Xu, Z. and Fan, K.: Comparison of changes in quasi-biweekly oscillation intensity over the western North Pacific during the developing late-summer of super El Niño events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3963, https://doi.org/10.5194/egusphere-egu24-3963, 2024.

Heavy Meiyu-Baiu rainfall occurred over central-east China and Japan in June-July 2020. This study analyzes observational and reanalysis data and performs atmospheric model simulations to investigate its causes. It is found that low Arctic sea ice cover (SIC) in late spring-early summer of 2020 along the Siberian coast was an important factor. The low SIC caused local warming and high pressure, resulted in excessive atmospheric blockings over East Siberia, which caused cold air outbreaks into the Meiyu-Baiu region, stopped the seasonal northward march of the Meiyu-Baiu front, and increased the thermal contrast across the front, leading to record-breaking rainfall in June-July 2020. Our results suggest that the 2020 extreme Meiyu-Baiu was partly caused by the low SIC around the Siberian coast through its impact on East Siberian blockings. Further analysis shows that Indian Ocean warming and the Arctic sea-ice loss has combined effect on the particularly heavy rainfall in July 2020.  Their effects are interdependent rather than additive. Strong IO warming is rarely observed alongside severe Arctic sea-ice loss before 2020 because of their discordant interannual variations. In the future, the combined effects of IO warming and Arctic sea-ice loss on the Meiyu-Baiu rainfall may become more pronounced as their long-term trends continue. 

How to cite: Chen, X., Wen, Z., and Dai, A.: Contributions of Arctic Sea-ice Loss and East Siberian Atmospheric Blocking to 2020 Record-breaking Meiyu-baiu Rainfall, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4868, https://doi.org/10.5194/egusphere-egu24-4868, 2024.

The western North Pacific subtropical high (WNPSH) is a crucial circulation system affecting weather and climate over China. To quantitatively measure its strength and spatial pattern, the geopotential height was firstly used to define WNSPH indices (H indices). However, due to global warming, the H indices have shown significant increasing trends in recent decades, causing some disturbance to reveal the interdecadal variation of WNPSH. Then, the eddy geopotential height (He indices) and stream function (R indices) have been successively used to redefine WNPSH indices to reflect the WNPSH’s actual interdecadal variation. Here, for further understanding the performances of these three types of WNPSH indices in the interannual variability, some comparisons have been made by using various statistical methods and machine learning models. The results show that, in the statistical characteristics, the He and R indices have normal distributions and are stationary time series with no systematic changes over time, while the H indices do not. Regarding the indication for summer precipitation in eastern China, the R indices perform well generally, but the other two types of indices are better in indicating regional precipitation. Also for predictability, the temporal correlation coefficients between the prediction results and the R indices are above 0.80, the same as the H indices which are used in operational applications until now. Overall, the R indices have obvious advantages whatever statistical characteristics or indication for precipitation. Using R indices as a benchmark to further improve indication of regional precipitation can provide more references for future operational applications. 

How to cite: Li, D. and Hu, S.: Which type of WNPSH indices can be better applied, defined by the geopotential height, the eddy geopotential height, or the stream function?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5060, https://doi.org/10.5194/egusphere-egu24-5060, 2024.

In recent years, the eastern China and even the whole northern hemisphere have suffered from frequent extreme climate events in summer. For example, the extremely hot summer of 2018 over East Asia, the abnormal precipitation in eastern China in the midsummer of 2021, and the high summer temperature in the Northern hemisphere in 2022 August. These extreme climate events have brought severe challenges to human life, economic development and ecological environment. Revealing the physical mechanism of such events is of great significance for disaster prevention and mitigation and policy making.

In fact, atmospheric circulation anomalies play an important role in regulating extreme climate events on a regional scale. However, the existing research mainly focus on the influence of the horizontal vortex circulations processes such as blocking and wave train, but the effects of local vertical circulations, especially the interaction between the local vertical and horizontal circulations, are still lacking. To explore a dynamic approach that considers the actual atmospheric circulation as a whole, Hu et al. (2017,2018a, 2018b, 2020) proposed a novel method called the three-pattern decomposition of global atmospheric circulation (3P-DGAC). Unlike the traditional two-dimensional decomposition method, which ignores the effects of the horizontal motion of low-latitudes and the vertical motion of mid-high latitudes, this method considers the effects of mid-high latitude divergent circulation and low latitude vortex circulation on the actual atmospheric circulation, which is conducive to the study of the dynamics of the actual atmospheric circulation from the global perspective. Specifically, the 3P-DGAC extends Rossby wave at mid-latitudes, Hadley circulation and Walker circulation at low latitudes to the global scale, and argues that the actual atmospheric circulation can be understood as the sum of the superposition of the horizontal vortex circulation, the meridional and zonal circulation. Thus, the 3P-DGAC provides a suitable tool for studying the dynamics of three-dimensional structure of local atmospheric circulation.

Using the 3P-DGAC method, we have studied the dynamics of the extreme climate events that have occurred in recent years and revealed the corresponding physical mechanisms, the findings suggest that local vertical circulations play a non-negligible role in extreme climate events. This study is expected to provide a reliable theoretical reference for the prediction of extreme climate events.

How to cite: Peng, J. and Hu, S.: Dynamic study of extreme climate events based on the three-pattern decomposition of global atmospheric circulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5067, https://doi.org/10.5194/egusphere-egu24-5067, 2024.

EGU24-5352 | ECS | Posters on site | CL4.14

Detection and Characterization of Climate Extremes with Deep Learning 

Anne Durif and Christian Pagé

Over the past few years, the consequences of climate extremes have become increasingly concerning. According to IPCC projections (Intergovernmental Panel on Climate Change), such events are to keep increasing in frequency, intensity, and duration. We aim at characterizing those changes, depending on carbon emission scenarios. But the analysis of climate simulations requires a huge computational power: data are available at a daily frequency, at a global scale at a ~125km spatial resolution, and depend on each realization of different climate models and scenarios.

We propose a novel method, a deep learning model, to address such big geospatial data sets. The state of the art for climate extreme detection with Artificial Intelligence focuses on satellite imagery, past events, or short-term forecasting. It is less prolific for future events or simultaneous analysis of several climate models and scenarios. In 2020, Sinha et al. developed an anomaly detection model to spot avalanches in satellite images. She tackled the same issue as ours: an unsupervised anomaly detection problem, with numerous unlabeled pictures of both normal snow surfaces and avalanche deposits.

The algorithm is based on a Convolutional Variational AutoEncoder (CVAE), a Neural Network that learns in an unsupervised setup. It is fed with plenty of images, with a small proportion of abnormal images, and learns how to compress and reconstruct them. The network has no information about whether the image is an anomaly or not. At the end of the training phase, it does a good job reconstructing normal images, but it struggles (high reconstruction error) with unusual samples.

In our case, the model is trained for each season on observations of a specific climate variable (e.g. temperature), on a given geographical zone. It is then applied to projection data (IPCC scenarios) on the same variable for the same location. The output images and losses are then post-processed as time series to extract statistical characterizations of the events, such as their frequency, intensity, or duration. The results are validated with several members (realizations) of the same climate model, and compared with analytical indices over a historical sample.

This work was supported by InterTwin project. InterTwin is funded by the European Union (Horizon Europe) under grant agreement No 101058386.

How to cite: Durif, A. and Pagé, C.: Detection and Characterization of Climate Extremes with Deep Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5352, https://doi.org/10.5194/egusphere-egu24-5352, 2024.

EGU24-5904 | Orals | CL4.14

Climate variability in the atmospheric moisture supply during meteorological drought episodes over La Plata Basin 

Rosmeri Porfírio da Rocha, Anita Drumond, Marina de Oliveira, Milica Stojanovic, and Raquel Nieto

This study aims to analyze variations in atmospheric moisture supply from major remote Brazilian hydrological basins during meteorological drought episodes in the La Plata Basin (LPB). The analyses were conducted for the period 1980-2018, using a Lagrangian diagnostic methodology that estimates the contribution of atmospheric moisture to the water balance in the region. The method relies on the Lagrangian model FLEXPART integrated with ERA-Interim reanalysis data. The technique calculates the difference between evaporation and precipitation by computing temporal variations in specific humidity of air parcels identified over the major Brazilian basins along their trajectories forward in time towards the LPB. During the analysis period, a total of 49 meteorological drought episodes were identified over the LPB through the time series of the monthly SPEI-1 (Standardized Precipitation-Evapotranspiration Index). Linear regression analysis indicates a relationship between variations in atmospheric moisture supply by air parcels traveling from several basins (Amazon, North Atlantic, and Tocantins) and the duration, severity and peak of drought episodes over LPB. This implies that more severe, longer, and higher peak dry episodes in the LPB were associated with a decrease in atmospheric moisture supply from the air parcels traveling from these basins. 

How to cite: Porfírio da Rocha, R., Drumond, A., de Oliveira, M., Stojanovic, M., and Nieto, R.: Climate variability in the atmospheric moisture supply during meteorological drought episodes over La Plata Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5904, https://doi.org/10.5194/egusphere-egu24-5904, 2024.

EGU24-6615 | Orals | CL4.14

Precursors of summer heatwaves in the Eastern Mediterranean 

Chaim Garfinkel, Dorita Rostkier-Edelstein, Efrat Morin, Assaf Hochman, Chen Schwartz, and Ronit Nirel

Reanalysis and observational data are used to identify the precursors of summertime
heatwaves over the Eastern Mediterranean over the historical period. After compiling
a list of heatwaves using objective criteria, we identify robust precursors present 7 to 10
days before the onset of the heatwave, longer than the typical horizon for trustworthy
weather forecasts. If these precursors are present, there is a significant warming over
the Eastern Mediterranean over the following 10 days that then persists for weeks
after. These precursors include a weakened Indian monsoon, warm West/Central
Mediterranean Sea surface temperatures, and a low disturbance from the west. Further,
horizontal temperature advection is the proximate cause of the heatwave in the days
before the extreme, and in particular a weakening of the Etesian winds that would
otherwise advect relatively cool maritime air inland accounts for around half of the
warming. There is a clear tendency for more heat extremes in recent years. These
results have implications for the forecasting of summer heatwaves in the Eastern
Mediterranean, and the framework developed here can be applied in other regions as
well.

How to cite: Garfinkel, C., Rostkier-Edelstein, D., Morin, E., Hochman, A., Schwartz, C., and Nirel, R.: Precursors of summer heatwaves in the Eastern Mediterranean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6615, https://doi.org/10.5194/egusphere-egu24-6615, 2024.

Recent land and marine heatwaves, extreme precipitation events and even monthly global mean temperature anomalies shattered previous observed records by large margins and reached intensities that many would have conceived impossible based on observations so far.

Here, I first demonstrate how in recent decades the frequency of such record-breaking and record-shattering extremes strongly deviates from expectations in a stationary climate and demonstrate how the current high rate of forced warming contributes to the current high occurrence record-shattering extremes. I further identify and discuss the extremes of the last two decades with the highest record margins.

Furthermore, I review different ways of estimating the probability and potential intensity of future record-shattering extremes. Different approaches including statistical approaches, such as Statistical Weather Generators or the use of Generalized Extreme Value distributions with process-based covariates as well as climate model-based approaches such as initialized hindcasts, single-model initial condition large ensembles and ensemble boosting have been proposed to estimate the potential intensity of future record-shattering extremes. I review the strengths and weaknesses of these approaches and argue that combining different lines of evidence is crucial to increase confidence in such estimates.

Finally, I will discuss how some of these methods also reveal how physical mechanisms differ between very extreme events and more moderate ones, and how they help to evaluate potential process-based constraints to upper bounds of the intensity of future record-shattering extremes.

How to cite: Fischer, E.: Understanding and quantifying recent and potential future record-shattering extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8077, https://doi.org/10.5194/egusphere-egu24-8077, 2024.

EGU24-10648 | ECS | Orals | CL4.14 | Highlight

Recent extreme heatwaves dwarfed by projected future events 

Philipp Aglas-Leitner, Sarah E. Perkins-Kirkpatrick, and Daithi Stone

In recent decades, unprecedented heatwaves have resulted in substantial impacts on human health and their environment. Previously, heatwave trend analysis has largely focused on trends across global warming thresholds or on specific regions. Furthermore, a variety of diverse heatwave parameters has been applied across separate studies, hampering direct comparison. What is more, there has been limited information on how future projections of individual events compare to recent extreme heatwaves.

In our study, we define heatwaves as periods of at least three consecutive days where daily area-weighted mean temperature exceeds the regional 90th percentile. We utilize a comprehensive analysis framework based on four heatwave parameters and additional sub-parameters where appropriate: (1) heatwave duration in days, (2) heatwave severity, an intensity index enabling interpreting excess heat relative to the regional climatology, (3) cumulative heat, and (4) percentage of locally affected area. The latter is an area-based parameter providing information on the exceedance of local (grid cell level) climatology thresholds during the course of an individual heatwave in percent of the respective region’s overall area. For parameters (2) and (4) we, moreover, investigate two sub-parameters, namely median and maximum values. The first sub-parameter refers to the median value of the entire heatwave, whereas the second indicates that this maximum value is being reached for at least one day during the event. This analysis framework greatly increases the ability for individual heatwave-based and regional intercomparison, and, furthermore, explores both regional as well as local scale trends, thereby providing critical human-impact-oriented information. In addition to daily output from multi-model ensembles from models taking part in the Coupled Model Intercomparison Project Phase 5 and 6 and large initial-condition ensembles (CanESM5 and ACCESS-ESM1-5), we employ our framework to 14 regional events observed during the period of 2010-2021 and analyzed based on Berkeley Earth and ERA5. This provides crucial insights into how future heatwaves compare to recent events.

Our results indicate that recently observed extreme heatwaves are dwarfed by projected 21st century events. Moreover, without even moderate reduction in greenhouse gas emissions the probability of reoccurrence or exceedance of these recent extreme reference values is significantly increasing, and they are still plausible under aggressive emission reduction scenarios.

In conclusion, we can see that a lack of mitigation and adaptation measures could considerably increase human exposure to extreme heat. In particular as we found, depending on the scenario, significant increases in the percentage of locally affected area and the heatwave severity. Thus, these findings stress the necessity for substantial and ambitious mitigation efforts and for considering heatwaves well outside the lived experience for effective adaptation measures.

How to cite: Aglas-Leitner, P., Perkins-Kirkpatrick, S. E., and Stone, D.: Recent extreme heatwaves dwarfed by projected future events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10648, https://doi.org/10.5194/egusphere-egu24-10648, 2024.

EGU24-11057 | ECS | Orals | CL4.14

Future shifts in timing of regional extreme precipitation 

Donghe Zhu, Patrick Pieper, Stephan Pfahl, Erich Fischer, and Reto Knutti

Despite the high confidence in the overall intensification of the hydrological cycle in response to global warming, future changes in the spatiotemporal distribution of extreme precipitation remain uncertain. We here explore how climate change affects the seasonality and timing of extreme precipitation, which potentially alters its impact on society, economy and ecosystems substantially. Extreme precipitation events are defined as an exceedance of the all-day 98th percentile of daily precipitation.

Most of the CMIP6 models capture the historical timing of extreme precipitation compared to the REGEN observational data. With climate change, we find distinct regional shifts in extreme precipitation across models. The most pronounced signal is a distinct shift of extreme precipitation from summer into the shoulder seasons, spring and autumn, or even into winter at latitudes between about 45°N and 75°N in Eurasia and northeast America.  These regions, which are climatologically characterized by extreme precipitation predominantly occurring during the summer, are projected to experience a strongly reduced fraction of extreme precipitation in summer during the second half of the 21st century.

Preliminary synoptic analysis in individual models indicates a combined effect of limited moisture supply and weaker updrafts during the core summer extreme precipitation events. Further analysis is required to disentangle the relative role of thermodynamic and dynamic contribution to impact-relevant changes in seasonality of extreme precipitation.

How to cite: Zhu, D., Pieper, P., Pfahl, S., Fischer, E., and Knutti, R.: Future shifts in timing of regional extreme precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11057, https://doi.org/10.5194/egusphere-egu24-11057, 2024.

EGU24-15936 | Orals | CL4.14

Antarctic extreme seasons under 20th and 21st century climate change 

Tom Bracegirdle, Thomas Caton Harrison, Caroline Holmes, Hua Lu, Patrick Martineau, and Tony Phillips

Extreme seasons (climate extremes) are of particular relevance to impacts, as they can produce accumulated effects on, for example, surface melt of ice shelves and penguin breeding. There is a gap in knowledge on how extreme seasons may change over Antarctica and the Southern Ocean under future climate forcing scenarios, with Antarctica not included in the IPCC AR6 WG1 Chapter 11 on extremes. In this presentation, available large ensemble datasets in the Coupled Model Intercomparison Phase 6 (CMIP6) archive were used to provide the first multi-variate overview of the evolution of extreme seasons over Antarctica and the Southern Ocean during the 20th and 21st centuries, with projections following medium-to-high radiative forcing scenarios (SSP2-4.5 and SSP3-7.0 forcing experiments). The variables assessed were near-surface temperature, surface precipitation rate and near-surface westerly wind. The results show significant differences between simulated changes in background mean climate and changes in low (10th percentile) and high (90th percentile) extreme seasons. Regional winter warming is most pronounced for cold extremes, particularly over or near to areas of climatological 20th century sea ice cover. In summer there are more pronounced increases in high extremes in precipitation and westerly wind during the ozone hole formation period (late 20th century) affecting coastal regions and in particular the Antarctic Peninsula. At sub-polar latitudes (between 50 and 60 degrees South) there is an approximately 20% reduction in the range of summer season wind extremes. Potential mechanisms/processes responsible for these differences will be discussed.

How to cite: Bracegirdle, T., Caton Harrison, T., Holmes, C., Lu, H., Martineau, P., and Phillips, T.: Antarctic extreme seasons under 20th and 21st century climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15936, https://doi.org/10.5194/egusphere-egu24-15936, 2024.

EGU24-17194 | Orals | CL4.14 | Highlight

Emergence of strong trends in humid heat intensity and duration in recent decades over South Asia 

Jitendra Singh, Erich Fischer, Deepti Singh, and Sebastian Sippel

The far-reaching impacts of humid heat extremes on public health and ecosystems underscore a necessity for a comprehensive investigation. South Asia is a global hotspot where humid heat reaches some of  the highest levels globally in a densely populated region, and climatologically highly interesting since temperatures typically peak in the pre-monsoon period, and humid heat only several weeks later during the monsoon period. This study examines the historical trends in humid heat extremes, and their underlying drivers and mechanisms during the pre-monsoon (Mar-May) and monsoon (June-September) seasons over South Asia. Our findings reveal a notable surge in the warming trends of humid heat extremes since 2000, exhibiting a rate exceeding twice that of observed long-term trends since 1950 in the monsoon season across South Asia. During the pre-monsoon season, short-term trends (trends since 2000) exhibit diverse regional patterns, indicating cooler heat extremes in western South Asia, while the rest of the region experiences increasing trends in heat extremes. This contrasts with the consistent and regionally coherent long-term warming trends in humid extremes since 1950 across South Asia. 

We further show that the seasonal evolution of daily maximum wet-bulb temperature in South Asia is closely linked with humidity levels, indicating that the occurrence of high humidity events governs the timing of humid heat extremes. During the monsoon season, higher humidity in Southern and Central South Asia occurs ~2 weeks earlier since 2000 compared to the climatological period (1950-1979). This elevated humidity aligns with several ℃ higher temperatures occurring earlier in the season, intensifying humid heat extremes. In western South Asia, changing humidity trends notably impact humid heat extremes: rising trends intensify them during the monsoon season, while declining trends cool pre-monsoon extremes. Further, we show that precipitation variability modulates humidity levels and, thereby, the intensity of humid heat extremes over western South Asia. Moreover, our study notes a significant increase in the duration of monsoon season humid heat extremes, expanding from ~2 days in the 1950s to several weeks in recent decades across South Asia. This prolonged and sustained occurrence is predominantly associated with consistent and high humidity levels. The emergence of such strong trends emphasizes the need to expedite adaptation and mitigation measures to align with the substantial escalation in humid heat intensity and duration.

How to cite: Singh, J., Fischer, E., Singh, D., and Sippel, S.: Emergence of strong trends in humid heat intensity and duration in recent decades over South Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17194, https://doi.org/10.5194/egusphere-egu24-17194, 2024.

EGU24-19636 | ECS | Orals | CL4.14

In-depth analysis of extreme event of rainfall erosivity over mainland China 

Liutong Chen, Yuanyuan Xiao, Shuiqing Yin, Wenting Wang, Stefan Strohmeier, Cristina Vásquez, Andreas Klik, and Peter Strauß

The majority of soil loss was triggered by several extreme rainfall events. Global warming may lead to an intensification of the surface water cycle and an increase in the probability and intensity of extreme rainfall events. An in-depth analysis of extreme event rainfall erosivity is valuable to help decision-makers take targeted measures to deal with future risks to soil and water resources protection. Cumulative rainfall erosivity from extreme events and characteristics of the 20- largest extreme events were analyzed based on the hourly rainfall data of 2420 meteorological stations over mainland China from 1951 to 2020. We sorted events at each site in descending order and calculated the percentage of events with accumulated erosivity (rainfall) accounting for 80% of total erosivity (rainfall) to all events (D80). Analysis on D80 shows 57% and 27% of extreme events of total events contribute 80% of rainfall and rainfall erosivity averaged over China, respectively, which indicates the impact of extreme erosivity is more predominant than that of extreme rainfall. The northern rock soil region (NR) and southwestern rock mountain region (SWR) were two regions with the least D80 among the six water erosion regions, which indicated fewer extreme events contributed to 80% of rainfall or rainfall erosivity compared with the other regions. D50 varies from 3% to 25% with a mean of 8% averaged over mainland China, which is more extreme than Europe (from 1% to 24 with a mean of 11%). TOP20_erosivity for extreme events with a descending order of event erosivity accumulates 29% of total erosivity, which is compared with 12% of TOP20_erosive for extreme events with a descending order of event rainfall. The average amount, duration and peak hourly intensity for TOP20_erosivity extreme events in summer are 14.6 mm,2.8 h, and 5.0 mm/h, respectively, while those for TOP20_rainfall are 16.5 mm, 4.4 h, and 3.4 mm/h, respectively, which indicate extreme erosive events are with a larger amount, shorter duration and greater peak intensity, comparing with extreme rainfall events. We further compared the synchronicity of the month with the maximum occurring frequency of extreme erosivity events and extreme rainfall events and found there are 33% of stations with not the same month. There were 19% of stations with the maximum month for erosive events preceding that for rainfall events and 14% of stations with the maximum month for erosive events lag behind rainfall events. 

How to cite: Chen, L., Xiao, Y., Yin, S., Wang, W., Strohmeier, S., Vásquez, C., Klik, A., and Strauß, P.: In-depth analysis of extreme event of rainfall erosivity over mainland China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19636, https://doi.org/10.5194/egusphere-egu24-19636, 2024.

A fundamental characteristic of extreme precipitation events (EPEs) is the horizontal scale of the associated vertical motions, called “extreme ascent.” This horizontal scale can influence the intensity of an EPE through its effect on the temporal and spatial scales of an EPE as well as its effect on the strength of convective feedbacks. Thus, to have confidence in future projections of extreme precipitation, the horizontal scale of extreme ascent and EPEs in GCMs should be evaluated. Analyzing daily output from 27 models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6), including 13 models participating in the High Resolution MIP (HighResMIP), we computed the horizontal scales of EPEs and extreme ascent for annual maximum EPEs during 1981-2000. We found that the horizontal scale of both EPEs and extreme ascent are resolution dependent, and the horizontal scales decrease as the horizontal model resolution increases. Further analysis reveals that this resolution-dependence is due to the fact that the precipitation during the EPEs is almost entirely resolved (rather than parameterized) precipitation. However, the EPEs are not simply grid-box storms and analysis of the horizontal scales of geopotential anomalies suggests that the large-scale dynamics in GCMs is not resolution dependent. Thus, the dominance of resolved precipitation during EPEs is more likely due to convection on the model grid or formation of strong fronts, and additional work is needed to explore these possibilities further and find a solution for the resolution dependence. This work is currently undergoing revision for consideration by Journal of Geophysical Research-Atmospheres.

How to cite: Tandon, N. and Ali, A.: Influence of horizontal model resolution on the horizontal scale of extreme precipitation events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20716, https://doi.org/10.5194/egusphere-egu24-20716, 2024.

EGU24-778 | ECS | Posters on site | AS1.19

The Record-Breaking Precipitation Event of December 2022 in Portugal: Synoptic Background 

Tiago Ferreira, Ricardo M. Trigo, Alexandre M. Ramos, Tomás Gaspar, and Joaquim G. Pinto

Extreme precipitation over western Iberia is mostly concentrated in the winter half-year. While relatively rare, intense precipitation events can disrupt and are often associated with major human, social and economic damages. Most of the time these extreme precipitation events are triggered by intense extratropical cyclones and associated frontal systems. However, in the last decade a number of studies have shown the important role played by Atmospheric Rivers (ARs) in the occurrence of extreme precipitation events in western Europe, particularly in the Iberia Peninsula.

In this study we analyse the all-time 24h record-breaking precipitation values recorded in Lisbon, Portugal between the 12 and 13 December 2022 in terms of the synoptic background. We obtained a comprehensive synoptic characterization of the atmospheric circulation between the 1st and 15th of December, considering a wide range of meteorological fields, such as vertically integrated water vapor flux, sea level pressure, geopotential height and divergence at the 850 hPa isobar, divergence at the 200 hPa, vertical velocity at the 500 hPa and temperature and specific humidity at 900 and 600 hPa.

Results show that on the 8 December by 06 UTC an extratropical cyclone was present in the middle of the North Atlantic, with a high moisture content and that by 18 UTC on the following day a cut-off low was formed in the northwest Atlantic. This cut-off system was well characterized by relatively high vertical velocities and convergence at the low levels, combined with high rates of evaporation acquired over the Gulf Stream, intensifying the moisture content to its south side. Both systems converged on 10 December by 12 UTC and by the 18 UTC the algorithm detected an AR located southward of the extratropical cyclone. The combination between high IVT values, with maxima ranging between 947 kg m-1 s-1 and 1227 kg m-1 s-1, with a dynamical component characterised by winds above 20 m/s, as well as a suitable vertical motion, allowed the system to evolve and maintain the AR characteristics for 72 h. The AR progressed towards Iberia, affecting Portugal and central Spain as an extreme AR event, leading to the 24h precipitation record of 134.6 mm measured at the Geophysical Institute in Lisbon, the highest value since continuous measurements started in the 1860. The previous record was registered on the 18 February 2008, with a value of 118.4 mm.

This work was supported by the Portuguese Science Foundation (FCT) through the project AMOTHEC (DRI/India/0098/2020) with DOI 10.54499/DRI/India/0098/2020 and also through national funds (PIDDAC) – UIDB/50019/2020. Tiago Ferreira was supported by FCT through PhD grant UI/BD/154496/2022.

How to cite: Ferreira, T., M. Trigo, R., M. Ramos, A., Gaspar, T., and G. Pinto, J.: The Record-Breaking Precipitation Event of December 2022 in Portugal: Synoptic Background, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-778, https://doi.org/10.5194/egusphere-egu24-778, 2024.

One of the challenges in climate change studies is understanding the moisture source, oceanic or terrestrial, responsible for the recent increase in global land precipitation evident by ERA-5 reanalysis data.  To explain the moisture source responsible for increase in the land precipitation we have used the d-excess value of precipitation which distinctly inherits the signature of various processes in the hydrological cycle and has been widely used for the validation of general circulation models. We created a global monthly time series of d-excess value (1978-2021) using precipitation isotope data (n= 62,665) from 913 sites. Since 1996, the enigmatic surge in the d-excess value aligns with the rise in the global land precipitation which cannot be explained by the already known moisture source of the global water cycle. Such a huge spike in d-exces value suggests an increase in contribution from the terrestrial moisture, especially from the evaporation of irrigated groundwater, a component which was not considered in the global hydrologic cycle. To feed the growing population, introduction of multiple cropping seasons and a decrease in the frequency of global land precipitation led to an increase in the groundwater-dependent agricultural practice. Previous studies have shown that the extraction of groundwater for irrigation is so huge and significant that it has been held responsible for global sea level rise  and drift of Earth’s rotation axis. In Spite of that, the remotely sensed data and land surface models partition the moisture sources of water cycle in the various components; such as transpiration, open water evaporation,  canopy interception, bare soil evaporation and  snow sublimation, however, never considered the coupling of groundwater with atmosphere. Therefore, to understand the global hydrological cycle, the moisture and energy exchange between groundwater and atmosphere, via evaporation of irrigated water, should be considered. Here, the enigmatic rise in d-excess value, equivalent to glacial-interglacial scale variation, signifies human domination in the global hydrological cycle.

 

 

How to cite: Ajay, A. and Sanyal, P.: Coupling of Groundwater with Atmosphere: A New Anthropogenic Component in the Global Hydrological Cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-963, https://doi.org/10.5194/egusphere-egu24-963, 2024.

EGU24-1442 | ECS | Orals | AS1.19

Extreme atmospheric rivers in a warming climate 

Shuyu Wang, Xiaohui Ma, Shenghui Zhou, Lixin Wu, Hong Wang, Zhili Tang, Guangzhi Xu, Zhao Jing, Zhaohui Chen, and Bolan Gan

Extreme atmospheric rivers (EARs) are responsible for most of the severe precipitation and disastrous flooding along the coastal regions in midlatitudes. However, the current non-eddy-resolving climate models severely underestimate (~50%) EARs, casting significant uncertainties on their future projections. Here, using an unprecedented set of eddy-resolving high-resolution simulations from the Community Earth System Model simulations, we show that the models’ ability of simulating EARs is significantly improved (despite a slight overestimate of ~10%) and the EARs are projected to increase almost linearly with temperature warming. Under the Representative Concentration Pathway 8.5 warming scenario, there will be a global doubling or more of the occurrence, integrated water vapor transport and precipitation associated with EARs, and a more concentrated tripling for the landfalling EARs, by the end of the 21st century. We further demonstrate that the coupling relationship between EARs and storms will be reduced in a warming climate, potentially influencing the predictability of future EARs.

How to cite: Wang, S., Ma, X., Zhou, S., Wu, L., Wang, H., Tang, Z., Xu, G., Jing, Z., Chen, Z., and Gan, B.: Extreme atmospheric rivers in a warming climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1442, https://doi.org/10.5194/egusphere-egu24-1442, 2024.

The northwest China (NWC) is situated in an arid and semi-arid inland, rendering its ecosystem highly susceptible to precipitation changes. Previous studies have revealed the wetting trend and potential moisture sources of the NWC, while not clearly quantified the moisture (water vapor and precipitation) sources and its interannual variability. Here, by performing and analyzing CAM5.1 simulation for 40 years, with a coupled atmospheric water tracer algorithm (AWT), we find that the dominant sources of summer moisture over NWC are from terrestrial sources (81.8% of vapor and 77.4% of precipitation), i.e. from the North Asia (NA), Europe (EUP), southern Tibetan Plateau (STP), and southeastern China (SEC), rather than the oceanic sources. Due to the influence of synoptic patterns, the precipitation-conversion efficiency of water vapor from the southwest airflow (STP and SEC) is higher than that from the northwest airflow (NA and EUP). We also find that despite a general increasing trend in humidification, the fluctuation from relatively dry to wet years still persists in the NWC influenced by the increased transport of moisture from terrestrial sources (NA and STP).

How to cite: Qian, P.: Quantifying the moisture and precipitation sources over Northwest China and investigating the source differences in dry and wet summer seasons, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1515, https://doi.org/10.5194/egusphere-egu24-1515, 2024.

EGU24-3270 | ECS | Orals | AS1.19

New insights into the Pacific Walker Circulation from an 800-year-long water isotope-based reconstruction ensemble  

Georgina Falster, Bronwen Konecky, Sloan Coats, and Samantha Stevenson

The Pacific Walker Circulation (PWC) has a major influence on weather and climate worldwide. But our understanding of 1) its response to external forcings; and 2) its internal variability across timescales remain unclear. This is in part due to the length of the observational record, which is too short to disentangle forced responses from internal variability. 

Here we assess the internal variability of the PWC as well as its response to the two largest external forcings of the Common Era: volcanic eruptions and anthropogenic forcing. We do this using a new annually-resolved, multi-method, palaeoproxy-derived PWC reconstruction ensemble spanning 1200-2000. The reconstruction is derived from 59 palaeoclimate proxy records, mostly from the Iso2k database of water isotope proxy records (Konecky et al., 2020). The basis for the reconstruction is previous work by Falster et al. (2021), demonstrating that global water isotope variability has a strong mechanistic link with the PWC via its major influence on the global water cycle. The PWC reconstruction ensemble comprises 4800 members that sample uncertainty from observational data, reconstruction method, and record chronologies. 

We identify a significant PWC weakening in the 1-3 years following large volcanic eruptions, similar to the response seen in some climate models. However, we find no significant industrial-era (1850-2000) PWC trend relative to the preceding 650 years, which contrasts the PWC weakening simulated by most climate models. In fact, the strength of the PWC is not correlated with global mean temperature across timescales. We also find that the 1992-2011 PWC strengthening—previously attributed either to volcanic or anthropogenic aerosol forcing—was indeed anomalous, but not unprecedented as compared to the past 800 years. Hence it may have occurred due to decadal internal variability. The one place we did identify an industrial-era PWC change is in the power spectrum, where a post-1850 shift to lower-frequency variability suggests a subtle anthropogenic influence. 

References:

Konecky, B. L., McKay, N. P., Churakova (Sidorova), O. V., Comas-Bru, L., Dassié, E. P., DeLong, K. L., Falster, G. M., Fischer, M. J., Jones, M. D., Jonkers, L., Kaufman, D. S., Leduc, G., Managave, S. R., Martrat, B., Opel, T., Orsi, A. J., Partin, J. W., Sayani, H. R., Thomas, E. K., Thompson, D. M., Tyler, J. J., Abram, N. J., Atwood, A. R., Cartapanis, O., Conroy, J. L., Curran, M. A., Dee, S. G., Deininger, M., Divine, D. V., Kern, Z., Porter, T. J., Stevenson, S. L., von Gunten, L., and Iso2k Project Members: The Iso2k database: a global compilation of paleo-δ18O and δ2H records to aid understanding of Common Era climate, Earth Syst. Sci. Data, 12, 2261–2288, 2020.

Falster, G., B. Konecky, M. Madhavan, S. Stevenson, and S. Coats: Imprint of the Pacific Walker Circulation in Global Precipitation δ18O. J. Climate, 34, 8579–8597, 2021.

How to cite: Falster, G., Konecky, B., Coats, S., and Stevenson, S.: New insights into the Pacific Walker Circulation from an 800-year-long water isotope-based reconstruction ensemble , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3270, https://doi.org/10.5194/egusphere-egu24-3270, 2024.

EGU24-3622 | ECS | Orals | AS1.19

Diabatic Amplification of Atmospheric River Intensity by Marine Heatwaves: Multi-Scale Air-Sea Interaction and Implications for Marine Heatwave Dissipation 

Christoph Renkl, Hyodae Seo, Élise Beaudin, Anthony Wilson, Art Miller, and Emanuele Di Lorenzo

The climate along the US West Coast is profoundly affected by the extratropical ocean and air-sea interaction near the coast, influencing moisture transport and valuable precipitation that play an important role in agricultural and water resource management efforts. On a basin scale, seasonal to interannual anomalies in the atmospheric circulation can create persistent upper-ocean temperature anomalies known as marine heatwaves (MHWs). These anomalous SST conditions have direct impact on air-sea fluxes, thereby influencing diabatic processes associated with synoptic-scale weather patterns, such as atmospheric rivers (ARs). Given the heat and moisture pickup by the ARs from the oceans, these multi-scale MHW-AR interactions may also represent a potential mechanism for dissipation of MHWs. This study examines diabatic multi-scale coupled air-sea interaction processes between persistent MHWs and synoptic-scale ARs, and evaluate their downstream effects on the coastal and inland climate.

Here, we present a comprehensive analysis based on observations and high-resolution, large-ensemble regional coupled model simulations targeting a series of landfalling ARs that interacted with warm SST anomalies during the Northeast Pacific MHW event in winter 2014/2015. Sensitivity simulations are conducted where various aspects of the observed MHW feature are removed from the ocean component of the coupled model to quantify the diabatic modification of the AR moisture and energy budgets. Our results show that MHWs exert diabatic forcing of the lower troposphere via enhanced latent heat flux from the ocean to the atmosphere and an associated increase in evaporation. This ultimately represents a nontrivial moisture source leading to an amplification of ARs indicated by a robust increase in rainfall intensity. Furthermore, the model results suggest noticeable shifts in the precise landfalling locations of the AR, the statistical significance of which is being assessed via ongoing ensemble simulations. The implications of MHW dissipation arising from the diabatic interaction between ARs and MHW will be discussed.

How to cite: Renkl, C., Seo, H., Beaudin, É., Wilson, A., Miller, A., and Di Lorenzo, E.: Diabatic Amplification of Atmospheric River Intensity by Marine Heatwaves: Multi-Scale Air-Sea Interaction and Implications for Marine Heatwave Dissipation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3622, https://doi.org/10.5194/egusphere-egu24-3622, 2024.

EGU24-6878 | ECS | Orals | AS1.19

Using stable water isotopes to improve our understanding of snow processes across scales 

Sonja Wahl, Benjamin Walter, Hans Christian Steen-Larsen, Franziska Aemisegger, Laura J. Dietrich, and Michael Lehning

Cryospheric processes and interactions between the cryosphere and other Earth system components are complex, host important climate feedbacks and are often difficult to measure. Yet their understanding is crucial for predicting the evolution of the cryosphere in a changing climate. Stable water isotopes are natural tracers of phase change processes within the hydrological cycle. The variability of the individual and combined isotope species offer a way to constrain environmental climatic conditions during phase change processes. Thus, they are a prime tool to investigate air-snow interactions, which are at the core of one of the most uncertain but eminently important climate feedbacks. In polar settings these phase change processes are predominantly vapor deposition and snow or ice sublimation. However, the principle of isotopic fractionation during sublimation has been controversially discussed and the usefulness of tracing stable water isotopes in cryospheric processes is thus debated.
Here we demonstrate through field observations and laboratory experiments that air-snow humidity exchange leaves an isotopic fingerprint in the snow isotopic composition. We present in-situ data from the Greenland Ice Sheet and new results from cold-laboratory wind tunnel experiments. The measurements comprise isotopic signatures of snow, vapor and of the humidity flux itself. We show that snow sublimation is a fractionating process and outline how this information can be used to improve cryospheric process understanding. Specifically, we investigate the process of drifting and blowing snow by observing the evolution of both vapor and snow isotopic composition during cold-laboratory wind tunnel experiments. We document the existence of hitherto unobserved airborne snow metamorphism; a process observable on the macro-scale only through the lens of stable water isotopes. Based on the combined observations of in-situ surface humidity fluxes and wind tunnel experiments we discuss a physical explanation for the observed isotopic fractionation during snow sublimation. These insights and the data set will be the basis for determining the fractionation factors associated with airborne snow metamorphism. Our results have important implications for the interpretation of stable water isotope signals from snow and ice cores and challenge the translation of the second-order parameter d-excess signal in polar regions as moisture source signal.

How to cite: Wahl, S., Walter, B., Steen-Larsen, H. C., Aemisegger, F., Dietrich, L. J., and Lehning, M.: Using stable water isotopes to improve our understanding of snow processes across scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6878, https://doi.org/10.5194/egusphere-egu24-6878, 2024.

A 25-year record from the United States Network for Isotopes in Precipitation (USNIP) using data from seventy-three sampling sites reveals the dynamic role of moisture sources and storm tracks in controlling the precipitation geochemistry at a continental scale. Our study provides a fresh perspective on processes governing the water isotope cycle beyond the classic role of temperature. We report that Climate Oscillations (COs) combine to influence synoptic climatology and atmospheric transport patterns, thereby driving spatiotemporal distribution of precipitation 18O, 2H and d-excess values. The relationship between the individual COs and the isotopic composition of precipitation is spatially, temporally, and geographically inconsistent with varying time periods of linear (positive/negative), non-linear, or no coherence. The interactions between COs drive variations in isotope fractionation associated with evaporation (moisture source dynamics) and transport (storm track pathways and degree of rainout) of moisture. These are mirrored in the spatiotemporal precipitation isotope patterns across contiguous USA and supported by airmass trajectory analysis. We use the USNIP observational dataset to validate and test process representation in the variable-resolution isotope-enabled Community Earth System Model-version 2 (VR-iCESM2) with regional grid refinement to ~12.5 km over the contiguous US. To explore the relative influences of origin, transport, and condensation of water vapor on precipitation isotope patterns, we use process-oriented water tags in the VR-iCESM2 that track physical properties at the evaporation source locations, Rayleigh rainout effect, and precipitation condensation temperature. We find the model prediction to be deficient in coastal regions which improves in the continental interior, but ‘nudging’ the model with atmospheric thermodynamic properties and grid refinement leads to an overall enhancement in model performance relative to low resolution (~100 km) iCESM simulations. Evaluating and improving water cycling processes in climate models using spatially dense, long-term observational datasets of water isotopes, such as USNIP, will improve interpretations of paleoclimate records and predictions of future changes.

How to cite: Dar, S. S., Macarewich, S., Klein, E., and Welker, J.: 25 years of precipitation isotopic composition across the USA: Assessment of non-linearities associated with moisture source dynamics and storm track variations in the Community Earth System Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7663, https://doi.org/10.5194/egusphere-egu24-7663, 2024.

EGU24-11548 | Posters on site | AS1.19

Adjustment of the Marine Atmospheric Boundary-Layer to the North Brazil Current during the EUREC4A-OA Experiment 

Hervé Giordani, Carlos Conejero, and Lionel Renault

The EUREC4A-OA experiment (January - February 2020. Bony et al., 2017) took place in the Northwest Tropical Atlantic. Atmospheric simulations were performed at kilometric scale during the EUREC4A-OA experiment (47 days) in order to estimate the sensitivity of the Marine Atmospheric Boundary-Layer (MABL) thermodynamics and circulation to the SST front associated with the North Brazil Current (NBC) and to the SST diurnal cycle. It will be shown that the NBC SST front and associated eddies «Couloir des Tourbillons» strongly control the MABL properties (Surface Pressure, Surface Heat Fluxes, Temperature, Wind, Vertical Shear, Precipitable Water, Liquid Water Content ...), while the diurnal cycle of the SST alters these properties by 5 to 10%.

A full MABL water budget has shown that the precipitable water (PW) results of the balance between the total Advection and entraiment at the MABL top, which drains water out the MABL, and surface evaporation that fills in the MABL. It will be shown that the NBC increases the loss of water by advection and by entrainment and increases the gain of water by surface evaporation, by 80 mm in 47 days. The diurnal cycle of SST amplifies these responses by 30 mm in the NBC.

Some components of the MABL energy budget will be also presented.

How to cite: Giordani, H., Conejero, C., and Renault, L.: Adjustment of the Marine Atmospheric Boundary-Layer to the North Brazil Current during the EUREC4A-OA Experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11548, https://doi.org/10.5194/egusphere-egu24-11548, 2024.

EGU24-11684 | Orals | AS1.19

A New Lens on Atmospheric Rivers 

Shakeel Asharaf, Bin Guan, and Duane Waliser

This presentation introduces the ROTated Atmospheric river coordinaTE (ROTATE) system – a storm-centric coordinate system designed specifically for analyzing long, narrow filamentary regions of intense water vapor transport in the lower atmosphere or so-called atmospheric rivers (ARs). It effectively preserves key AR signals in the time mean that may be lost or obscured in simple averaging due to diverse AR orientations and shapes. We used ROTATE to look at crucial characteristics of atmospheric rivers such as how wet the air is, how fast the wind blows, how much water vapor is being transported, and how much rain falls. We found more apparent AR patterns with ROTATE compared to the conventional non-rotated AR centroid-based compositing approach. The new method also helps us see finer details in rain distributions over land versus over the oceans. It is further apparent that the ROTATE system more distinctly delineates the finer details in precipitation distributions for landfalling and oceanic ARs. Overall, the ROTATE system has the potential to serve as a valuable tool for better comparing and understanding the characteristics, processes, and impacts of ARs across different regions. Details about the analysis and challenges associated with the current results will be discussed in this presentation.

How to cite: Asharaf, S., Guan, B., and Waliser, D.: A New Lens on Atmospheric Rivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11684, https://doi.org/10.5194/egusphere-egu24-11684, 2024.

EGU24-12550 | ECS | Orals | AS1.19

Seeking consensus between Eulerian and Lagrangian moisture tracking methods for precipitation origin analysis in Atmospheric Rivers 

Alfredo Crespo-Otero, Damian Insua-Costa, and Gonzalo Míguez-Macho

Global warming is increasingly aggravating hydro-climate extremes, such as floods and droughts. In this context it is essential to understand the complex dynamics of the atmospheric branch of the water cycle, including the link between evaporation and precipitation. For this reason, many studies have investigated the origin of the moisture that feeds precipitation, which has led to a better understanding of atmospheric water transport. However, the lack of observations has prevented a direct validation of the different moisture tracking tools used for this purpose, and it is common to find large discrepancies between the results they provide.

To fill this gap, we compare two different Lagrangian methodologies for moisture tracking based on the FLEXible PARTicle dispersion model (FLEXPART) against the Eulerian “Water Vapor Tracers” technique based on WRF (WRF-WVTs). Considering the results of WRF-WVTs as “ground truth”, we explore the discrepancies between the Eulerian and Lagrangian approaches for five precipitation events associated with ARs and, based on that, propose some physics-based adjustments to the Lagrangian tools. Our results show that Lagrangian methodologies using evaporation data instead of specific humidity data provide results much closer to those of WRF-WVTs. Specifically, they reduce large biases that underestimate remote sources (such as tropical ones), while overestimating local contributions. When we introduce our physical corrections, both methods improve remarkably, which means that these biases are strongly reduced and the results provided by the different techniques reach a consensus.

How to cite: Crespo-Otero, A., Insua-Costa, D., and Míguez-Macho, G.: Seeking consensus between Eulerian and Lagrangian moisture tracking methods for precipitation origin analysis in Atmospheric Rivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12550, https://doi.org/10.5194/egusphere-egu24-12550, 2024.

EGU24-14310 | Posters on site | AS1.19

Atmospheric moisture transport in Central Europe – rivers or streams 

Agnieszka Wypych

The diversity of water vapor content in the air is crucial for the regional analysis of atmospheric precipitation occurrences. The amount of water vapor carried by the air mass over a specific area can vary significantly depending on the current characteristics of air circulation, with a key role played by atmospheric rivers. These rivers originate from the meridional transport of water vapor and have a significant impact on Europe through the interaction with extratropical cyclones.
The aim of the work is to assess the intensity of water vapor transport over Europe and the extent of its inland penetration.
Atmospheric rivers/streams will be identified based on ECMWF ERA5 reanalyses data from 1991 to 2023 and CMIP6 future projections until the year 2100.
Selected cases of intense water vapor transport over the European region, especially Central Europe, will be compared with the occurrence of atmospheric precipitation.

How to cite: Wypych, A.: Atmospheric moisture transport in Central Europe – rivers or streams, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14310, https://doi.org/10.5194/egusphere-egu24-14310, 2024.

EGU24-14966 | Orals | AS1.19

From atmospheric water isotopes measurement to firn core interpretation in coastal sites: A method for isotope-enabled atmospheric models in East Antarctica 

Christophe Leroy-Dos Santos, Elise Fourré, Cécile Agosta, Mathieu Casado, Alexandre Cauquoin, Martin Werner, Simon Alexander, Marshall Lewis, Vincent Favier, Tessa Vance, Derryn Harvie, Olivier Cattani, Benedicte Minster, Frédéric Prié, Olivier Jossoud, Leila Petit, and Amaëlle Landais

In a context of global warming, it is key to estimate the evolution of the atmospheric hydrological cycle and temperature in the polar regions. Since records are only available from satellite data for the last 40 years, one of the best ways to access longer records is to use climate proxies in firn cores. The water isotopic composition of firn cores is widely used to reconstruct past temperature variations. However, both temperature and atmospheric water cycle (origin of the precipitation, deposition and post-deposition effects) influence the isotopic composition of snow. We present a 2-year long time series of vapor and precipitation isotopic composition measurement at Dumont D’Urville (DDU), a coastal station in Adélie Land. This unique data set is first used to study the link between hydrological cycle and weather regimes at DDU. It is found that both continental and oceanic air masses impact the signal. Then, this record is used to evaluate the Global Climate Model ECHAM6-wiso equipped with water stable isotopes which is able to reproduce the observed isotopic signal. This result permits further use of ECHAM6-wiso to interpret water isotopic profiles on short firn cores. Using this methodology, we evaluate ECHAM6-wiso atmospheric outputs at two other East Antarctic coastal sites: Davis  and Neumayer stations.

How to cite: Leroy-Dos Santos, C., Fourré, E., Agosta, C., Casado, M., Cauquoin, A., Werner, M., Alexander, S., Lewis, M., Favier, V., Vance, T., Harvie, D., Cattani, O., Minster, B., Prié, F., Jossoud, O., Petit, L., and Landais, A.: From atmospheric water isotopes measurement to firn core interpretation in coastal sites: A method for isotope-enabled atmospheric models in East Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14966, https://doi.org/10.5194/egusphere-egu24-14966, 2024.

EGU24-15660 | ECS | Posters on site | AS1.19

Machine learning analysis for predicting spatial distribution and key influencers of stable isotope patterns in European precipitation 

Dániel Erdélyi, Zoltán Kern, István Gábor Hatvani, Polona Vreča, Klara Žagar, Frederic Huneau, Aurel Perșoiu, Markus Leuenberger, Sonja Lojen, Oliver Kracht, Astrid Harjung, Pekka Rossi, Kaisa-Riikka Mustonen, and Jeffrey Welker

Natural abundance variations in stable isotope ratios of hydrogen and oxygen are important environmental tracers with a significant range of applications  (e.g., the exploration of the present water cycle, paleoclimate reconstructions, ecology, and food authenticity). These applications and research themes are often based on spatially explicit predictions of precipitation isotopic variations obtained from point sample collections and measurements through various interpolation techniques. The derivation of spatially continuous and georeferenced isotope databases, known as isotopic landscapes (isoscapes), has been considered most effective through regression kriging for precipitation beginning in the early 2000s. However, the number of interpolation methods used in geostatistics has increased rapidly in recent decades, with new machine learning algorithms becoming increasingly important and proving more successful than conventional methods for certain isotopic parameters. In the present research we present a monthly 10 x 10 km European isoscape based on state-of-the art hybrid machine learning method that combines LASSO Regression and Random Forest (Zhang et al., 2019) for spatial predictions for 1973-2022. Data were retrieved from the IAEA/WMO Global Network of Isotopes in Precipitation (no. of stations: 329) and other national datasets from about 10 countries (no. of stations: ~150).

A pilot study (for 2008-2017; Erdélyi et al. 2023) indicated the highest prediction error for the northern premises. This suggested the incorporation of sea ice as an additional predictor, since a Pan-Arctic precipitation stable isotope study pointed out that sea ice cover change is a key driver of oceanic moisture sources (Mellat et al., 2021). Results indicate an overwhelming importance of minimum temperature with the variable representing sea ice cover, ranking among the least influential parameters. The analysis fails to consider moisture source effects, transport distances, and secondary processes of recycling associated with evaporation and transpiration from landscapes across Europe. These results provide a more refined prediction due to the higher station density compared to previous models and thanks to the hybrid model, a more accurate prediction of monthly precipitation stable isotope compositions is expected for the critical areas including the latitudinal margins as well as the mountainous zones.

Activities for this presentation were supported by the IAEA (CRP F31006, CRP F33024, TC-project RER7013, Contract 23550/R0) and WATSON Cost Action 19120. This research was also funded by UEFISCDI Romania, grants number PN-III-P2-2.1-PED-2019-4102, PN-III-P4-ID-PCE-2020-2723 and ARIS (Grants P1-0143, N1-0054, N1-0309, J6-3141, J6-50214).

 

Erdélyi, D., Kern, Z., Nyitrai, T., et al. (2023). Predicting the spatial distribution of stable isotopes in precipitation using a machine learning approach: a comparative assessment of random forest variants. International Journal of Geomathematics, 14:14. doi:10.1007/s13137-023-00224-x

Mellat, M., Bailey, H., Mustonen, K-R., Marttila, H., Klein, E. S., Gribanov, K., ... Welker, J. M. (2021). Hydroclimatic Controls on the Isotopic (δ18 O, δ2 H, d-excess)  Traits of Pan-Arctic Summer Rainfall Events. Frontiers in Earth Science, 9:651731. doi:10.3389/feart.2021.651731

Zhang, H., Nettleton, D., & Zhu, Z. (2019). Regression-enhanced random forests. arXiv preprint arXiv:1904.10416.

How to cite: Erdélyi, D., Kern, Z., Hatvani, I. G., Vreča, P., Žagar, K., Huneau, F., Perșoiu, A., Leuenberger, M., Lojen, S., Kracht, O., Harjung, A., Rossi, P., Mustonen, K.-R., and Welker, J.: Machine learning analysis for predicting spatial distribution and key influencers of stable isotope patterns in European precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15660, https://doi.org/10.5194/egusphere-egu24-15660, 2024.

EGU24-16154 | ECS | Orals | AS1.19

Unraveling the moisture transport in the North Atlantic trade-wind region using passive tracers and stable water isotopes 

Svetlana Botsyun, Stephan Pfahl, Franziska Aemisegger, Leonie Villiger, and Ingo Kirchner

The atmospheric hydrologic cycle and the formation of shallow cumulus clouds in the marine trade-wind region are important for the Earth’s radiative budget and climate sensitivity. Furthermore, the understanding of air mixing and transport processes in the atmosphere is crucial for interpreting measurements and records of stable water isotopes. However, the representation of these processes in climate models is subject to large uncertainties. Here we investigate moisture transport and its impact on the isotopic signature in the North Atlantic trade-wind region. We use the regional COSMO model equipped with stable water isotopes and passive water tracers to quantify the contributions of the different evaporation sources to moisture contents and their isotope signals in the free troposphere of the western tropical Atlantic. For the time period of the EUREC4A field campaign (January-February 2020), convection-resolving high-resolution (5 km) nudged simulations are performed, allowing a comparison with field data. Passive tracers (water tagging) are combined with prognostic water isotope simulations to determine the specific isotopic fingerprints of the diagnosed moisture pathways. In January and February 2020, the tropical Atlantic region is characterized by alternating large-scale circulation regimes with distinct isotopic signatures. Humid conditions in the middle troposphere (300-650 hPa) over the island of Barbados are related to easterly and south-easterly moisture transport, while dry conditions correspond to extratropical transport from the north and west. Our modeling approach, together with the unprecedented observational data from the EUREC4A campaign, offers exciting new opportunities to evaluate and ultimately improve the representation of the tropical water cycle in climate models.

How to cite: Botsyun, S., Pfahl, S., Aemisegger, F., Villiger, L., and Kirchner, I.: Unraveling the moisture transport in the North Atlantic trade-wind region using passive tracers and stable water isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16154, https://doi.org/10.5194/egusphere-egu24-16154, 2024.

EGU24-16667 | ECS | Posters on site | AS1.19

Impact of increased evaporation from an increasingly ice-free Arctic on land precipitation 

Yubo Liu and Qiuhong Tang

The loss of Arctic sea ice is conducive to more Arctic evaporation, which can alter precipitation through moisture cycling and transport. However, the extent of this influence remains uncertain. Our work focuses on Arctic seas where seasonal sea ice has retreated significantly. The Arctic evaporation was tracked to establish a link between changes in both sea ice and precipitation over land during the cold season (October to March). Our results show a significant one-third increase in Arctic moisture contribution to land precipitation. Despite Arctic moisture comprising a relatively small proportion of land precipitation, its heightened contribution significantly influenced the precipitation, especially over lands adjacent to the Arctic. Our findings highlight that the progressively ice-free Arctic tends to contribute to a gradual yet discernible shift in the climatological land precipitation, which may lead to an elevated risk of extreme disasters.

How to cite: Liu, Y. and Tang, Q.: Impact of increased evaporation from an increasingly ice-free Arctic on land precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16667, https://doi.org/10.5194/egusphere-egu24-16667, 2024.

EGU24-17899 | ECS | Orals | AS1.19

Decade-Long Isotopic Analysis (18O & 2H) of Daily Precipitation in the Malaya Peninsula: Understanding the Complex Hydrometeorology 

Harsh Oza, Ludvig Löwemark, George Kontsevich, Akkaneewut Jirapinyakul, Sakonvan Chawchai, Helmut Duerrast, Mao-Chang Liang, Midhun Madhavan, and Chung-Ho Wang

The Malaya Peninsula, uniquely positioned between the South China Sea to the east and the Indian Ocean to the west presents a unique geographic vantage point for the study of ocean-ocean and ocean-atmosphere-land interactions, particularly in the context of climate change. Its proximity to the Indo-Pacific Warm Pool (IPWP) makes the region a critical nexus where global temperature rise intersects with significant ocean-atmosphere processes, such as Hadley and Walker circulations, El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Madden–Julian Oscillation (MJO). These processes and their teleconnections play a pivotal role in shaping the regional climate, profoundly influencing rainfall patterns and freshwater availability in the peninsula. 

In our research, we conducted a decade-long analysis of oxygen and hydrogen isotopes in daily rainfall samples collected from Krabi, Thailand, a region situated in the northern Malaya Peninsula. Krabi faces the Andaman Sea and is characterized by a tropical monsoon climate. The region's climate is predominantly influenced by the North-South migration of the Intertropical Convergence Zone (ITCZ), which governs the patterns of summer and winter monsoonal rainfall. The diverse topography of Krabi plays a critical role in local weather patterns, potentially intensifying the complexity of the region's dual monsoon system. The time series analysis of isotopic data brings to light three distinct patterns superimposed over the daily variability. There's a clear seasonal cycle, primarily driven by changes in moisture sources, indicating shifts in atmospheric moisture transport with the seasons. Additionally, multi-year patterns suggest the influence of complex ocean-atmospheric processes, likely reflecting teleconnections between the Western Pacific and Indian Oceans. Intriguingly, we also observed a long-term trend of isotopic depletion without corresponding changes in rainfall volume, hinting at the potential impacts of ocean warming and broader climate change.

This study underscores the importance of understanding the nuanced interplay of land, ocean, and atmospheric systems in regional rainfall dynamics. It has significant implications for regional climate models and paleoclimatic research. It highlights the sensitivity of the Malaya Peninsula's climate to both local topographical features and global oceanic phenomena, offering crucial insights into the regional responses to ongoing global climatic changes.

How to cite: Oza, H., Löwemark, L., Kontsevich, G., Jirapinyakul, A., Chawchai, S., Duerrast, H., Liang, M.-C., Madhavan, M., and Wang, C.-H.: Decade-Long Isotopic Analysis (18O & 2H) of Daily Precipitation in the Malaya Peninsula: Understanding the Complex Hydrometeorology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17899, https://doi.org/10.5194/egusphere-egu24-17899, 2024.

EGU24-18497 | ECS | Posters on site | AS1.19

Changes in the concurrence of atmospheric rivers and explosive cyclones in the North Atlantic 

Ferran Lopez-Marti, Mireia Ginesta, Davide Faranda, Anna Rutgersson, Pascal Yiou, Lichuan Wu, and Gabriele Messori

The explosive development of extratropical cyclones and the presence of atmospheric rivers play a crucial role in driving some types of extreme weather in the mid-latitudes, like compound flood-windstorm events. Although these phenomena are individually well-established and their relationship has been studied previously, there is still a gap in our understanding of how a warmer climate may affect their concurrence. Here, we focus on evaluating the current climatology and assessing changes in the future climate of the concurrence between atmospheric rivers and explosive cyclones in the North Atlantic.

We use both the ERA5 and ERA-Interim reanalysis between 1980 to 2009 from October to March to evaluate the concurrence of atmospheric rivers and explosive cyclones in the current climate. To accomplish this, we first independently detect and track atmospheric rivers and extratropical cyclones. Next, we classify each cyclone as either explosive or non-explosive and define concurrence with an atmospheric river if the latter is detected within 1500 km of the minimum sea level pressure of the cyclone. We further analyse several CMIP6 climate models for the historical scenario (1980-2009) and for the future scenarios SSP1-2.6, SSP2-4.5 and SSP5-8.5 at the end of the century (2070-2099).

Our findings reveal that atmospheric rivers are more often detected in the vicinity of explosive cyclones than non-explosive cyclones in all datasets. Moreover, we identified a significant increase in the concurrences and the atmospheric river intensity in all the future scenarios analysed. As such, our work provides a novel statistical relation between explosive cyclones and atmospheric rivers in climate projections, a characterization of both in future climates and a new climatology of the concurrences for a higher-resolution reanalysis.

How to cite: Lopez-Marti, F., Ginesta, M., Faranda, D., Rutgersson, A., Yiou, P., Wu, L., and Messori, G.: Changes in the concurrence of atmospheric rivers and explosive cyclones in the North Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18497, https://doi.org/10.5194/egusphere-egu24-18497, 2024.

EGU24-18507 | ECS | Orals | AS1.19

Quantifying the contribution of oceanic evaporation to tropical cyclone development with WRF-age  

Jianhui Wei, Patrick Olschewski, Qi Sun, Yu Li, Patrick Laux, and Harald Kunstmann

Global warming is accelerating the global water cycle. On a short temporal scale, such acceleration may modify weather regimes and, thus, potentially increase the number of compound weather and climate events. Among them, tropical cyclones can bring destructive high winds, torrential rain, storm surges and occasionally tornadoes in association with a variety of hazards, especially in coastal urban regions. In this study, we apply a newly developed WRF-age model, i.e., the Weather Research and Forecasting model enhanced with an age-weighted water tracking approach, to a coastal urban region in Southeast China. The source and transport of atmospheric water vapor in one Northwest Pacific Ocean cyclone, here, Hato in August 2017, are exemplarily examined by means of tracking oceanic evaporation. Two indices, i.e., the contribution ratio and the atmospheric water residence time, are used to better understand how much and how fast the oceanic evaporation contributes to the development of tropical cyclone Hato. Our simulation results show that, within 24 hours, the contribution ratio of the tagged oceanic evaporation to the total water vapor researches up to around 25%. In addition, the spatial pattern of the atmospheric water residence time shows that the oceanic evaporation below the rainbands of Hato (around 9 hours) fuels faster in its development than the oceanic evaporation from the surrounding region (15 hours). These findings emphasize the important role of oceanic evaporation to tropical cyclone development. Our study demonstrates that the WRF-age model can be applied to quantify the acceleration of tropical cyclone development under global warming.

How to cite: Wei, J., Olschewski, P., Sun, Q., Li, Y., Laux, P., and Kunstmann, H.: Quantifying the contribution of oceanic evaporation to tropical cyclone development with WRF-age , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18507, https://doi.org/10.5194/egusphere-egu24-18507, 2024.

EGU24-18906 | ECS | Posters on site | AS1.19

Computing precipitations with a 1D vertical (radiative-convective) model using zero parameterizations. 

Quentin Pikeroen and Didier Paillard

The main philosophy in building a climate model is to represent the most possible number of phenomena, with the purpose of answering the most possible number of questions, with one unique perfect model. For this purpose, climate models have historically evolved from energy balance models, to radiative-convective models, to general circulation models, to the earth system model, with growing complexity. While this approach is relevant in some domains (e.g. climate services), more simple models could answer simple questions (e.g. calculate the mean temperature or precipitations for paleoclimates). Moreover, all climate models use parameterizations to represent the processes with unknown or not numerically solvable physical laws. Moreover, to make them accurate, all climate models tune their parameters. For example, in the atmosphere in the vertical direction, the energy flux often obeys a Fourier-like law with a "conductivity" coefficient tuned to fit observations. The approach we use is entirely different, and because of that, we need to rebuild everything from scratch. We want to construct a simple atmospheric model with no parameterizations (the ultimate goal could be to couple it to a vegetation or an ice model and run long simulations).

We use the MEP hypothesis (maximum entropy production) to do so. This hypothesis has been used in realistic cases with parameterizations, or without parameterizations in more theoretical cases (like 2-box models). However, we aim to construct a full climate model with the MEP hypothesis. First, we restrict ourselves to a vertical tropical atmosphere: a radiative-convective model. Only stationary states are considered. Also, the relative humidity is fixed at 100%. A realistic radiative code is used, and convection is computed with the MEP hypothesis. The computed temperatures fit well with the observations. Also, precipitations can be computed and are coherent with observations. This means that almost only the knowledge of radiative transfer is needed to obtain a good order of magnitude of precipitations. In recent developments, the model has allowed deep convection, leading to slightly different precipitations. When relative humidity is allowed to vary; in the simple convection case, the MEP solution gives a 100% relative humidity almost everywhere; and the deep convection case gives a non-trivial relative humidity profile.

Because MEP is only a hypothesis, we still need to find out if the MEP solution is the exact solution. However, it must represent some upper bound in the system because it corresponds to a maximum. It is already interesting to explore what this upper bound is.

How to cite: Pikeroen, Q. and Paillard, D.: Computing precipitations with a 1D vertical (radiative-convective) model using zero parameterizations., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18906, https://doi.org/10.5194/egusphere-egu24-18906, 2024.

EGU24-19539 | ECS | Posters on site | AS1.19

Antarctic water stable isotopes in the global atmospheric model LMDZ6: from climatology to boundary layer processes 

Niels Dutrievoz, Cécile Agosta, Camille Risi, Étienne Vignon, Sébastien Nguyen, Amaelle Landais, Elise Fourré, Christophe Leroy-Dos Santos, Mathieu Casado, Inès Ollivier, Jean Jouzel, Didier Roche, Benedicte Minster, and Frédéric Prié

Water-stable isotopic compositions of snow or ice (here δ18O and δD) represent the main way to reconstruct past temperature in Antarctica, and one way to interpret these isotopic signals is through the use of isotope-enabled atmospheric general circulation models. In this study, we combine isotopic observations from surface snow samples, daily precipitation and water vapour to evaluate the LMDZ6iso model in Antarctica from climatic to seasonal and sub-daily time scale. Time-averaged δ18O in precipitation from LMDZ6iso for the period 1980-2022 is in excellent agreement with δ18O of surface snow samples across the continent, but there is a strong disagreement for d-excess at cold temperature sites. For sub-annual time scale analyses, we focus on two sites in East Antarctica: the coastal station Dumont d'Urville and the continental station Concordia. The model accurately reproduces the seasonal isotopic cycle of daily precipitation at both stations, with better performances at Concordia. Moving from statistical evaluation to process analyses, we use water vapour isotopes to study water exchanges in the boundary layer. LMDZ6iso performs well in representing the observed diurnal isotope cycle at both sites. However, the model simulates a larger vapour δ18O depletion than observed during the night at Concordia. We analyse the contribution of each physical process affecting isotope concentrations in LMDZ6iso to show what controls the vapour isotope signal. At Concordia, surface sublimation during the day is the main driver of the diurnal cycle of vapour isotopes, whereas at Dumont d'Urville, daily isotope variations are driven by surface sublimation and turbulence during the day and by air advection from the katabatic flow during the night.

 

How to cite: Dutrievoz, N., Agosta, C., Risi, C., Vignon, É., Nguyen, S., Landais, A., Fourré, E., Leroy-Dos Santos, C., Casado, M., Ollivier, I., Jouzel, J., Roche, D., Minster, B., and Prié, F.: Antarctic water stable isotopes in the global atmospheric model LMDZ6: from climatology to boundary layer processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19539, https://doi.org/10.5194/egusphere-egu24-19539, 2024.

EGU24-19562 | ECS | Posters virtual | AS1.19

The role of Dry Intrusions in the formation and intensification of Atmospheric Rivers impacting France 

Kim Andreas Weiss, Tomás Gaspar, Albenis Pérez-Alarcón, Shira Raveh-Rubin, Joaquim G. Pinto, and Alexandre M. Ramos

Extra-tropical storms over the North Atlantic often leads to socio-economic impacts over Western Europe, associated with strong winds and precipitation. Such storms can be associated with so-called Atmospheric Rivers (ARs) which are relatively narrow regions of concentrated water vapor (WV) and strong winds where intense horizontal moisture transport can take place. In turn, the moisture availability along the cyclone path and the ARs lifetime can be impacted by boundary layer processes. For example, the occurrence of Dry Intrusions (DI) associated with previous cyclones can strongly destabilize the planetary boundary layer (PBL) leading to enhanced moisture uptake over the ocean. This can support the formation and/or intensification of the ARs themselves.

The objective of this study is to understand the influence of DI on the moisture uptake in the PBL and transport associated with ARs impacting France.

With this aim, an adapted version of the detection algorithm developed by Ramos et al. (2015), was applied to ERA-5 reanalysis targeting events impacting the Atlantic coast of France. A total of 300 AR-events were detected over the extended winter (ONDJFM) spanning the years 1979 to 2023. Indeed, the most intense landfalling ARs are associated with intense precipitation and high wind speeds over western France.

For a subset of these AR-events, occurring between 1992 and 2022, the Lagrangian FLEXPART model using ERA5-data was applied to calculate the moisture sources for these events. This approach allows for the tracking of air masses 10 days backward in time from the target region (5°W to 0.5°E and 43.75°N to 50°N). 

Additionally, the occurrence of DI outflows (from 1979 onward) was based on its Lagrangian detection in ERA5 to assign possible DI outflows overlapping with the source regions of moisture uptake.

Our results suggest a relationship between the areas of DIs and moisture uptake, indicating the possibility of the DI exerting influence on the formation and intensification of ARs. Overall, this work serves as a preliminary investigation for the upcoming North Atlantic Waveguide, Dry Intrusion, and Downstream Impact Campaign (NAWDIC) recently endorsed by the World Weather Research Programme (WWRP).

How to cite: Weiss, K. A., Gaspar, T., Pérez-Alarcón, A., Raveh-Rubin, S., Pinto, J. G., and Ramos, A. M.: The role of Dry Intrusions in the formation and intensification of Atmospheric Rivers impacting France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19562, https://doi.org/10.5194/egusphere-egu24-19562, 2024.

EGU24-1999 | ECS | Posters on site | AS1.35

Elevation-dependent warming in the Alps estimated from MAR simulations over 1961-2100 

Ian Castellanos, Martin Ménégoz, Juliette Blanchet, and Julien Beaumet

Regional imprints of global warming have to be investigated to predict the impact of climate change on a local scale and inform mitigation and adaptation policies. The rate of warming as a function of elevation in mountainous regions is yet to be fully characterized and understood. This study aims to identify elevation-dependent warming features in the Alps as well as its physical drivers, using MAR (Modèle Atmosphérique Régional) simulations with a 7kmx7km resolution over 1961-2100, under different climate scenarios. Different seasonal patterns have been found, most notably a maximum of warming at intermediate elevation (~1500m to 1800m) in Spring related to earlier snow melting in future projections. This maximum of warming moves towards higher elevations over the XXIst century. Elevation-dependent warming is found to be different in the free-atmosphere and along the slopes of the mountains, highlighting the major impact of surface processes, such as changes in albedo, in the drivers of climate change in the Alps.

How to cite: Castellanos, I., Ménégoz, M., Blanchet, J., and Beaumet, J.: Elevation-dependent warming in the Alps estimated from MAR simulations over 1961-2100, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1999, https://doi.org/10.5194/egusphere-egu24-1999, 2024.

EGU24-2067 | Orals | AS1.35

Extreme rainfall characteristics and its simulations in the Yarlung Tsangbo Grand Canyon, China 

Xuelong Chen, Dianbin Cao, Qiang Zhang, Xin Xu, and Yaoming Ma

The Yarlung Tsangbo Grand Canyon (YGC), one of the world’s deepest canyons, is located in the southeastern Tibetan Plateau (SETP). The YGC exhibits the highest frequency of convective activity in China. Due to frequent rainstorms in the wet season, natural disasters such as landslides and debris flows frequently occur, and often block traffic corridors. Thus, understanding the relationship between water vapor changes, convective cloud activity, and extreme rainfall events in the YGC is critical. A comprehensive observation network for water vapor variations, cloud activity, local circulation, and land-air interactions in the YGC was installed to help us to determine the relationship between the water vapor transport and heavy precipitation in the YGC and the physical process that determines the precipitation intensity, especially for cases of strong precipitation.

More than three years data collected from a rain gauge network, disclose that the spatial pattern of rainfall distribution. There are two regions (500 m and 2500 m AMSL) with high precipitation in the YGC. Diurnal cycles showed some variations among sites, but a clear floor was visible around afternoon and peak values exhibited in the early morning. The monthly precipitation in the YGC region shows two peaks in April and July. Vertical convection and vapor transport are important for extreme rainfall in this region.

We analyzed 35 years observation data of daily precipitation to objectively classify the weather systems responsible for the SETP heavy precipitation. Hierarchical clustering method divided the atmospheric circulation of the regional heavy precipitation into two representative patterns: the Tibetan Plateau vortex type (TPVT, accounting for 56.6% of the heavy precipitation events) and the mid-latitude trough type (MLTT,43.4%). The comprehensive analysis of the two patterns shows a clear connection between the heavy precipitation and positive vorticity anomaly, moisture convergence and the southeastward shift of the westerly jet core. Specifically, TPVT heavy precipitation events are caused by potential vorticity dry-to-wet processes during its eastward movement, while MLTT events are associated with the intrusion of deeply extratropical trough-ridge circulations into the SETP.

We used the Weather Research and Forecasting (WRF) model to simulate the water vapor flux during extreme rainfall events. The general shortcoming of the WRF precipitation simulation nudged with the European Centre for Medium-Range Weather Forecasts’ reanalysis dataset version 5 (ERA5), is that it cannot capture strong rainfall period. We tested many WRF parameterization schemes at a 1 km grid resolution. It was found that when an optimized combination of parameterization schemes in WRF can better capture the variations in the wind and water vapor concentration in the YGC channel, the model produced the best simulation results for extreme rainfall in the YGC.

These analyses have help us understanding the impacts of YGC valley on the water vapor transport and extreme rainfall outbreak mechanism.

How to cite: Chen, X., Cao, D., Zhang, Q., Xu, X., and Ma, Y.: Extreme rainfall characteristics and its simulations in the Yarlung Tsangbo Grand Canyon, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2067, https://doi.org/10.5194/egusphere-egu24-2067, 2024.

The Tibetan Plateau (TP) directly heats the middle tropospheric atmosphere, and accurate simulation of its surface temperature is of great concern for improving climatic prediction and projection capabilities, but climate models always exhibit a cold bias. Based on the Coupled Model Intercomparison Project Phase 6 (CMIP6) models and in-situ observations during 1981-2014, this study elucidates the impact of the snow overestimation on the temperature simulation over the TP in CMIP6 from the perspective of local radiation processes and atmospheric circulation. On the one hand, more snow in the CMIP6 models not only directly cools the surface more, but also makes the surface receive less shortwave radiation due to the higher surface albedo, and thus has lower ground surface temperature (GST), and the more snow/albedo-low temperature process is particularly evident in the westerly region due to more uncertainty at high elevations. This process contributes 87% to the annual GST cold bias. Lower GST corresponds to less latent heat transfer and thereby lower surface air temperature (SAT). In addition, the more snow in the CMIP6 models leads to the weaker the South Asian summer monsoon and the westerlies, and brings less warm and moist air (less integrated water vapor flux), as well as less clear-sky downward longwave radiation (less water vapor amount and lower tropospheric air temperature) to the TP (contributing 58% to the annual GST cold bias). These processes will result in less both precipitation and surface latent heat loss, which offsets a 35% annual GST cold bias. Besides, the physical mechanism of snow on GST and SAT differs with season over the westerly and monsoon regions of the TP. The research highlights the importance of topography and snow parameterization schemes for optimizing CMIP6 models.

How to cite: Wu, F. and You, Q.: Understanding of CMIP6 surface temperature cold bias over the westerly and monsoon regions of the Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2463, https://doi.org/10.5194/egusphere-egu24-2463, 2024.

EGU24-3382 | ECS | Posters on site | AS1.35

An ensemble of meteorological stations for estimating daily air temperature time series at Jungfraujoch since 1864 

Marco Bongio, Carlo De Michele, and Riccardo Scotti

Air temperature is a pivotal factor influencing numerous chemical, physical, and biological processes. However, there is a notable scarcity of long-term data, especially at high elevations, exceeding 2000 m a.s.l. This study focuses on reconstructing the daily maximum, mean, and minimum temperatures at Jungfraujoch (3571 m a.s.l.) since 1864. The approach involves daily data from 10 meteorological stations within the ECA&D (6) and Meteo Swiss (4) databases. All selected stations are situated above 2000 m a.s.l. (in the range 2140-3109 m a.s.l.), providing uninterrupted observations spanning at least from 1961 to 2022. The methodology includes these steps: 1) for each meteorological station, in the calibration period 1980-1999, it was modeled the daily temperature at Jungfraujoch as the sum of the temperature at the selected station plus a deterministic and a stochastic component; the deterministic component is the product of the temperature lapse rate (TLR) and the elevation difference between the reference and selected station, and the stochastic component is a “noise” which comes from the statistical distribution of the residuals. The seasonality requires parameters with monthly variability which are different considering minimum, mean and maximum temperature. The calibration phase consists in the estimation of TLR and the statistical distribution of residuals (among Normal, GEV, Stable and Tlocscale distributions). The evaluation of model performances was based on the calculation of Pearson correlation coefficients (ρP) and Root mean squared errors (RMSE) within the two validation periods (1961-1979 and 2000-2022). High correlation coefficients (greater than 0.9 in both calibration and validation periods) and low values of RMSE (from 1.56°C to 3.32 °C in the calibration period and from 1.56°C to 3.42°C in the validation) confirm the model’s accuracy. The same high performances were found before (1961-1979) and after (2000-2022) the calibration period, for every meteorological stations. 2) Then the 10 simulated time series at Jungfraujoch were sorted according to the lowest values of the RMSE, and the first three was mediated to define an “ensemble” daily temperature time series, which was able to obtain these performances: (ρP=0.96,0.98,0.97; RMSE=1.97,1.46,1.68 °C respectively for max, mean and min temperature). The study was then extended from the year 1864. Comparing the results with the existing literature we highlighted: i) high performances without the need of modeling the observed trend due to the climate change (subjected to high uncertainty in the future), ii) very parsimonious model without the need of any other variables (relative humidity, cloud cover, wind velocity, weather patterns); iii) the importance of selecting high stations elevations (above 2000 m a.s.l.) rather than considering closer stations but subjected to the thermal inversion phenomena; iv) maximum temperature is affected by higher errors, especially from 2000-2022 which is probably due to the higher increasing of the summer and winter temperatures at high elevation accordingly to an elevation warming dependence; v) This method could be easily extended in many regions of the world and these results could be used to make a back ward analysis of many environmental processes (glacio-hydrological and permafrost), within the Jungfrau-Aletsch UNESCO World Heritage Site. 

How to cite: Bongio, M., De Michele, C., and Scotti, R.: An ensemble of meteorological stations for estimating daily air temperature time series at Jungfraujoch since 1864, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3382, https://doi.org/10.5194/egusphere-egu24-3382, 2024.

EGU24-5260 | ECS | Posters on site | AS1.35

The frequency of summer light rain projections in typical terrain over eastern China constrained by surface wind speed 

Xuechen Dong, Daoyi Gong, and Cuicui Shi

The variation of near surface wind speed is a key dynamic parameter in the orographic effect of precipitation over eastern China. In this study, we used the latest high-resolution outputs from six GCMs in CMIP6-HighResMIP to evaluate the performance of high-resolution models in simulating the orographic precipitation characteristics of typical mountainous areas in summer over eastern China. Combined with observational results, the orographic precipitation under warming scenarios was projected and constrained. The results indicated that during the contemporary climate reference period (1979-2009), although the relationship between model-simulated near surface wind speed and the orographic light rain frequency was consistently stable, the sensitivity of the orographic light rain frequency to surface wind variability was generally underestimated, with a deviation approximately 24.1% lower than the observational values. Comparison of model-simulated wind speed with observational records showed that the negative bias of the sensitivity value was mainly contributed by the overestimated wind speed in models. Based on observed near-surface wind speed to constrain and correct the orographic light rain frequency, the constrained estimates revealed a 36.1% reduction in orographic light rain frequency under a 1.5°C warming scenario, which is 8.6 times greater than the original predictions (4.2%). The MRI-AGCM3-2-S model, with a longer dataset, demonstrated a relatively stable reduction in orographic light rain frequency under different warming scenarios (1.5°C, 2°C, 3°C, and 4°C) after wind speed constraints, all of which are exceeding the original predictions.

How to cite: Dong, X., Gong, D., and Shi, C.: The frequency of summer light rain projections in typical terrain over eastern China constrained by surface wind speed, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5260, https://doi.org/10.5194/egusphere-egu24-5260, 2024.

EGU24-6068 | ECS | Posters on site | AS1.35

21st Century climate change in the European Alps and its elevation dependency 

Anna Napoli, Michael Matiu, Sven Kotlarski, Dino Zardi, Alberto Bellin, and Bruno Majone

Climate change is a global phenomenon with regionally varying peculiarities. It is well known that mountainous regions are highly sensitive to climate change. Furthermore, the complex orography exerts a strong control on the expected impacts that often depend on several controlling factors such as elevation, slope, land use etc.. In addition, climate models introduce errors in reproducing local physical processes due to their coarse spatial resolution and partly poorly constrained parameterisations.

Elevation Dependent Climate Change has been observed in the European Alps as a consequence of the interplay of global warming and the specific Alpine orography. The Alpine region is considered as a climate change hot-spot given that a large portion of this region has warmed about twice as much as the global average with warming rates characterised by a strong dependence on elevation. On the contrary, observed precipitation trends show very high spatial variability, sometimes with significant dependence on the elevation. In this study we analyse these complex Alpine temperature and precipitation change patterns with the elevation in the EURO-CORDEX ensemble of regional climate models at 0.11° resolution including CORDEX-Adjust (bias-adjusted CORDEX simulation) and compare these results to different model outputs characterised by coarse grid resolution (GCMs, e.g. CMIP5 ) and selected convection permitting models. The future trends of climate indices covering both the mean the extremes are explored across spatial scales and different RCPs. This study includes also analysis of the effects of different bias-adjustment techniques on the trend reproduction.

How to cite: Napoli, A., Matiu, M., Kotlarski, S., Zardi, D., Bellin, A., and Majone, B.: 21st Century climate change in the European Alps and its elevation dependency, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6068, https://doi.org/10.5194/egusphere-egu24-6068, 2024.

EGU24-6607 | ECS | Orals | AS1.35

Modelling the mountain boundary layer: Does higher resolution improve model performance? 

Brigitta Goger and Anurag Dipankar

The horizontal grid spacing of numerical weather prediction models keeps decreasing towards the hectometric range, where topography, land-use, and other static parameters are well-resolved. Still, models have to be evaluated over complex terrain, because it cannot be assumed that higher horizontal resolution automatically yields better model performance. In this study, we perform limited-area simulations with the ICON model across horizontal grid spacings (1 km, 500 m, 250 m, 125 m) in the Inn Valley, Austria. Simulations are ran with two turbulence schemes - a 1D parameterization and a 3D Smagorinsky-type scheme. We evaluate the model across scales with observations of the valley boundary layer from the CROSSINN measurement campaign. This allows us to investigate whether increasing the horizontal resolution automatically improves the representation of the thermally-induced circulation, surface exchange, and other mountain boundary layer processes. Results suggest that the valley topography is already well-represented at the kilometric range, but the simuations in the hectometric range show a more detailed representation of the vertical valley atmosphere structure and the up-valley flow. Across resolutions, the model struggles with the correct representation of interactions between larger and smaller scales. The two turbulence schemes show a similar performance, but the 3D Smagorinsky scheme simulates a delayed evening transition of the up-valley flow. It is argued that the major difference between schemes actually emerges from the different surface transfer schemes, and the choice of boundary layer parameterization is secondary.

How to cite: Goger, B. and Dipankar, A.: Modelling the mountain boundary layer: Does higher resolution improve model performance?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6607, https://doi.org/10.5194/egusphere-egu24-6607, 2024.

Redistribution of snow by the wind has been shown to greatly influence local snow accumulation in alpine terrain. Due to the small-scale nature of this process, previous studies either concentrated on short case studies over small areas or relied on highly simplified wind fields. To bridge the gap towards an assessment of the importance of snow drift over alpine glaciers on seasonal scales we present a new approach using simulations with the Weather Research and Forecasting (WRF) model and deep learning as a computationally efficient downscaling tool for near-surface winds and snow redistribution over complex topography.

We created a training data set of high-resolution (dx=50 m) WRF simulations coupled to a novel drifting-snow module that is representative for winter-time alpine environments. The idealized setup allows us to control the degrees of freedom that the final model has to learn. We developed a new technique to create synthetic topographies with similar spectral information as real terrain employing inverse Fourier transforms of scaled fields of random noise. Initial conditions for the WRF simulations are taken to represent the distribution of atmospheric and snow conditions over a winter season. This training data set we feed into a U-Net shape architecture using convolutional neural networks.

Here we present first results using a training data set with a reduced number of degrees of freedom as a prove of concept. Future developments will involve adding more complexity to the initial conditions as well as applying it to real-world settings. For this we will couple the model to a glacier mass balance model and run it with real-world atmospheric fields in order to asses the overall importance of drifting snow for alpine glaciers.

How to cite: Saigger, M. and Mölg, T.: Welcome to Fourier-Land: Deep-Learning based downscaling of near-surface winds and drifting snow using WRF simulations over synthetic topographies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8087, https://doi.org/10.5194/egusphere-egu24-8087, 2024.

EGU24-9427 | ECS | Posters on site | AS1.35

Climatic drivers of elevation-dependent warming (EDW): A concerted field and modeling assessment for an alpine national park 

Simon Zitzmann, Benjamin Fersch, and Harald Kunstmann

Mountain regions, such as the Alps, play a crucial role in providing ecosystem services, e.g., by acting as ‘water towers’ and substantially contributing to the discharge of the main European rivers. However, global warming is causing significant changes to the cryosphere, biodiversity and ecosystems in these regions. Hence, understanding the microclimatic changes in mountainous areas is essential, particularly the phenomenon of elevation-dependent warming (EDW), describing an amplified warming trend predominantly at higher elevations compared to adjacent lowlands. In the scientific community multiple drivers of EDW are being discussed, among them snow-albedo feedback, changes in cloud properties, and aerosols. The contribution of the individual drivers varies regionally and the role of surface energy balance components, especially ground heat flux, is rarely examined.

Therefore, this study focuses on investigating the elevation-dependency of temperature trends and surface energy balance components, as well as its driving mechanisms in the Berchtesgaden National Park, Germany. This area in the northern limestone Alps is characterized by a highly variable topography, diverse landscapes and numerous ecosystems. Preliminary results from this ongoing study are presented, emphasizing the methodological approach and initial insights gained:

Extensive data from the meteorological measuring station network, covering elevations from 600 to 2700 m.a.s.l., is analyzed to identify EDW patterns in the national park and its surroundings.

Additionally, from fall 2023 to 2025, a transect of three meteorological stations is established at different elevations (600 to 2000 m.a.s.l.) for a detailed investigation of land surface energy balance. Besides measuring the radiative components in highly variable terrain, the field observations focus especially on ground heat flux, obtained at multiple positions within each station site to capture the small-scale variance and aspect dependency of ground heat flux. Additionally, at one of the stations the turbulent heat fluxes are assessed, using the Modified Bowen Ratio Method.

To gain a holistic picture of the processes within the national park, the land surface model Noah-MP is employed to simulate the surface energy exchange processes at a high spatial resolution of 100 m. To improve the understanding of the development over time, model runs covering several decades in the past and a run during the measurement period (2023–2025) are performed, with results validated against the observational data.

How to cite: Zitzmann, S., Fersch, B., and Kunstmann, H.: Climatic drivers of elevation-dependent warming (EDW): A concerted field and modeling assessment for an alpine national park, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9427, https://doi.org/10.5194/egusphere-egu24-9427, 2024.

EGU24-10043 | ECS | Orals | AS1.35

Using Novel Lake-based Snowfall Measurements in the Alps and Himalayas to optimise Cloud and Precipitation processes in a Regional Atmospheric Model (MetUM) 

Siddharth Gumber, Andrew Orr, Paul Field, Hamish Pritchard, Federico Covi, Pranab Deb, Marc Girona-Mata, Martin Widmann, and Emily Potter

Complex mountain orography induces sharp gradients in precipitation accumulation locally. The associated complexity in understanding these events depends on local orographic, microphysical, and dynamical conditions, which makes simulating snowfall a major challenge for regional atmospheric models. This study addresses these deficiencies by using a unique repository of snowfall measurements at a range of ‘super sites’ in the European Alps and Himalayas, which are used to produce a precipitation-optimised version of the atmosphere-only UK Met Office Unified Model (MetUM) at a spatial resolution of 1.5 km. The snowfall measurements involve using the winter time-series of water pressure in frozen lakes to measure the mass of falling snow during extreme precipitation events directly over the lake area, which are comparable in size to the model’s grid cells. Development of the precipitation-optimised version of the MetUM involves undertaking a series of model sensitivity experiments focused on varying the physical representation of cloud and precipitation microphysics, with the aim of better capturing the onset and end periods, and amounts of received snowfall during these extreme events. The MetUM is configured to use a double moment cloud microphysical scheme (CASIM: Cloud AeroSol Interacting Microphysics) with prescribed hydrometeor spectral attributes necessary to quantify both the auto-conversion rates and thresholds for the cloud conversion to take place. Results from these experiments suggest that local microphysical processes, often subsumed within small spatial scales, can influence dynamics at larger scales, impacting gradients in precipitation. Cloud radiative properties, including the hydrometeor effective radii and optical depths are further validated against satellite-based observations.

How to cite: Gumber, S., Orr, A., Field, P., Pritchard, H., Covi, F., Deb, P., Girona-Mata, M., Widmann, M., and Potter, E.: Using Novel Lake-based Snowfall Measurements in the Alps and Himalayas to optimise Cloud and Precipitation processes in a Regional Atmospheric Model (MetUM), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10043, https://doi.org/10.5194/egusphere-egu24-10043, 2024.

EGU24-11038 | ECS | Orals | AS1.35

Investigating a local windstorm using measurements and large-eddy simulations 

Nicolai Krieger, Christian Kühnlein, Michael Sprenger, Heini Wernli, Philipp Bättig, Maxime Hervo, and Ulrich Krieger

During a winter storm in January 2007, a train derailed due to strong winds in a narrow valley in northeastern Switzerland. The accident was attributed to the Laseyer, a local windstorm characterized by flow reversal that manifests as easterly to southeasterly winds at the valley floor during strong prevailing northwesterly winds above. We analyze case studies of the local windstorm using sonic anemometer and Doppler lidar measurements. The data reveal a highly turbulent flow in the narrow valley and extreme wind speeds exceeding 45 m/s during Laseyer conditions.

Additionally, we use a newly developed large-eddy simulation (LES) atmospheric model to improve our understanding of the local windstorm. The model is implemented in a Python environment with the GT4Py (GridTools for Python) domain-specific library to enable performance portability.  Robust and efficient solution of the nonhydrostatic compressible equations is achieved using a finite-volume semi-implicit discretization following ECMWF’s IFS-FVM. LESs are performed above the highly complex terrain of northeastern Switzerland, which leads to extremely steep slopes exceeding 70°. With these LESs, we identify the mechanism behind the local windstorm, study its sensitivity to ambient flow conditions, and characterize the flow conditions in the narrow valley.

How to cite: Krieger, N., Kühnlein, C., Sprenger, M., Wernli, H., Bättig, P., Hervo, M., and Krieger, U.: Investigating a local windstorm using measurements and large-eddy simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11038, https://doi.org/10.5194/egusphere-egu24-11038, 2024.

EGU24-12631 | Orals | AS1.35

The Inn Valley exit jet: results of the TEAMx pre-campaign 

Katrin Sedlmeier, Meinolf Kossmann, Ivan Paunovic, Astrid Eichhorn-Müller, Oliver Nitsche, Ronny Leinweber, Eileen Päschke, and Gudrun Mühlbacher

Previous studies have found a pronounced nocturnal low-level jet at the exit of the Inn Valley north of the valley contraction near Schwaigen which reaches into the Alpine foreland (e.g. Pamperin and Stilke, 1985 as part of the MERKUR experiment or a model study by Zängl, 2004). The exit jet forms under nocturnal stably stratified atmospheric conditions and is interpreted as a transition from subcritical to supercritical hydraulic flow.

As part of the pre-campaign of the TEAMx programme in June-August 2022, we have conducted measurements to corroborate the previous findings on the formation and maintenance of the Inn valley exit jet and learn more about its turbulence structure, which has not been studied in previous experiments. For this purpose, a wind lidar was deployed in Brannenburg, north of the valley constriction. TKE profiles were derived from the Lidar measurements using the method described in Smalikho and Banakh (2017).  Furthermore, 3-hourly radiosondes were launched at the site of the wind lidar, accompanied by drone measurements during an IOP (18/19 July 2022) in high pressure weather conditions with low cloud cover.  

Upper air and surface wind measurements during the IOP captured a well pronounced Inn valley exit jet which is analyzed in detail in this contribution. Additionally, a statistical analysis of the occurrence and characteristics of nocturnal low-level jets within the whole pre-campaign period is presented.

 

References:

TEAMx: http://www.teamx-programme.org/

Smalikho, I.N., and V.A. Banakh. "Measurements of wind turbulence parameters by a conically scanning coherent Doppler lidar in the atmospheric boundary layer." Atmospheric Measurement Techniques 10.11 (2017): 4191-4208.

Pamperin, H., and G. Stilke. "Nächtliche Grenzschicht und LLJ im Alpenvorland nahe dem Inntalausgang." Meteorologische Rundschau 38.5 (1985): 145-156

Zängl, G. "A reexamination of the valley wind system in the Alpine Inn Valley with numerical simulations." Meteorology and Atmospheric Physics 87.4 (2004): 241-256.

How to cite: Sedlmeier, K., Kossmann, M., Paunovic, I., Eichhorn-Müller, A., Nitsche, O., Leinweber, R., Päschke, E., and Mühlbacher, G.: The Inn Valley exit jet: results of the TEAMx pre-campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12631, https://doi.org/10.5194/egusphere-egu24-12631, 2024.

EGU24-13294 | ECS | Orals | AS1.35

A new dataset of daily observations from a dense network of weather stations covering the Extended Alpine Region 

Giulio Bongiovanni, Michael Matiu, Alice Crespi, Anna Napoli, Bruno Majone, and Dino Zardi

Several observational products of key climate variables have been widely used to evaluate the extent of the ongoing effects of climate change in the Alpine area, one of the most vulnerable and sensitive regions to the continuous warming of climate. However, a limited spatial coverage in most observational products and quality issues of data may strongly impact climate and hydrological studies results in terms of reliability, accuracy and precision. Even though the collection and management of meteorological data for the whole Alpine area is a challenging task due to strong fragmentation and diversity of data sources, further efforts need to be dedicated to produce new harmonised, high-quality and high-resolution products able to permit a more robust assessment of climate change and its impacts.  

Here we present a new observational dataset gathering in-situ measurements of meteo-climatic variables provided by a variety of meteorological and hydrological services within the extended Alpine region. The observational network consists of about 10000 in-situ weather stations, measuring key climate variables up to 2020 at daily time resolution, resulting in an extended and homogeneous coverage, both in space and elevation. Data collected are screened, inspecting the presence of most important critical issues in terms of data quality. A deep quality control of collected time series has been performed by checking internal, temporal and spatial consistency of time series, exploiting the problem of outlier removal. Inhomogeneities in time series are detected by a multi-methods approach and significant inhomogeneous periods are corrected. 

A climatological and trend analysis, in terms of both mean and extreme values, was carried out on a selection of homogenised time series extending over the period 1961-2020. The most common climate indices and statistics are used to perform the analysis at different time frequencies and spatial scales. A further analysis concerned the relationship between climate variables and main teleconnection patterns.

The present dataset addresses the most important issues affecting state-of-the-art observational products and it represents a powerful tool for better understanding Alpine climate changes over the last decades and improving the reliability of future scenarios.

How to cite: Bongiovanni, G., Matiu, M., Crespi, A., Napoli, A., Majone, B., and Zardi, D.: A new dataset of daily observations from a dense network of weather stations covering the Extended Alpine Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13294, https://doi.org/10.5194/egusphere-egu24-13294, 2024.

EGU24-13935 | ECS | Posters on site | AS1.35

Future Projections of Summer precipitation-driving Mechanisms over the South American Altiplano 

Jhoana Agudelo, Jhan-Carlo Espinoza, Clementine Junquas, and Paola A. Arias

The South American Altiplano is a high-altitude plateau (3800 m MSL) located in the central Andes between 15ºS and 22ºS. Bounded to the west by the coastal desert of Peru-Chile and to the east by the hyper-humid lowlands of Peru-Bolivia, the Altiplano exhibits a semi-arid climate, following a pronounced annual cycle, with over 70% of rainfall occurring during the austral summer (December-January-February). Associated with factors such as convective activity occurring west of the Amazon Basin, the generation of convective clouds over the central Andes occurs when eastward winds encounter the orographic barrier on the eastern slope of the Andes. This process represents the primary mechanism governing precipitation variability in the Altiplano. Previous studies analyzing future projections anticipate that the central Andes will become warmer during the 21st century, impacting the population, ecosystems, and glaciers of the South American Altiplano. This is particularly relevant since agriculture is the main economic activity in this region and depends directly on precipitation.

Summer precipitation over the Altiplano has shown a strong dependence on the magnitude of zonal flow in the free troposphere (200 - 300hPa). Nevertheless, General Circulation Models (GCMs) suggest a continuous increase in westerly flow over the central Andes, hindering moisture transport from the interior of the continent. Minvielle and Garreaud (2011) suggest a significant reduction (10%-30%) in Altiplano precipitation by the end of this century under moderate to strong greenhouse gas emission scenarios. More recently, Segura et al., (2020) found that precipitation variability in the Altiplano is also associated with upward motion over the western Amazon (WA). Thus, DJF precipitation over the Altiplano seems to respond directly and primarily to the upward motion over the WA, since the early 21st century.

Using a set of 13 GCMs, this study aims to explore possible future projections in precipitation processes under the SSP3-7.0 scenario. This study focuses on the evolution of two previously established mechanisms driving austral summer precipitation over the Altiplano: 1) easterly winds at upper levels over the central Andes, and 2) upward motion over the WA. As preliminary conclusions of this work, models indicate that both mechanisms appear to weaken for the future period analyzed (2050-2084), suggesting a reduction in summertime precipitation by the mid-21st century. Additionally, models project a more stable atmosphere over the central Andes for the future period, also indicating a reduction in precipitation in the region, reinforcing the initial conclusion.

How to cite: Agudelo, J., Espinoza, J.-C., Junquas, C., and Arias, P. A.: Future Projections of Summer precipitation-driving Mechanisms over the South American Altiplano, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13935, https://doi.org/10.5194/egusphere-egu24-13935, 2024.

EGU24-14519 | ECS | Posters on site | AS1.35

Automatic identification of systematic model failures in ensemble precipitation forecasts 

Yuliya Kazachkova and Annette Miltenberger

Quantiative precipitation forecasting remains a major challenge even for kilometre-scale ensemble forecasating systems. However, operational high-resolution ensemble systems provide a large data-set from which - if combined with observational data - insight into systematic issues in the model physics can be gained. Here, we explore statistical methods to automatically identify systematic error patterns and their relation to the larger-scale conditions at example problem of precipitation at the Harz mountain range in northern Germany. For the analysis COSMO-D2-EPS forecasts for the years 2011-2018 are combined radar-derived and station-calibrated surface precipitation estimates provided by the German Weather Service (DWD). For the identification of common precipitation error patterns, empirical orthogonal function (EOF) analysis has been employed. For the winter season the leading order principal components show error features located on the elevated topography in the Harz region. Analysis of large-scale conditions (derived from ERA5) for each principal component shows systematic differences in upstream wind direction and speed, temperature, and specific humidity. In the summer seasons patterns are less localised, but some regional structure is maintained especially for the first principal component. Also the differentiation in large-scale conditions between EOFs is less. The challenges in summer are presumably related to a large contribution of convective precipitation. Overall, the leading 5 principal components explain 70,4% (48,2%) of the variance in winter (summer). To gain a better understanding of the relationship of error models to larger-scale conditions, as well as the physical mechanisms of model errors, simulations of precipitation at representative dates for principal components 1 and 2 were performed using the ICON-D2 model.

How to cite: Kazachkova, Y. and Miltenberger, A.: Automatic identification of systematic model failures in ensemble precipitation forecasts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14519, https://doi.org/10.5194/egusphere-egu24-14519, 2024.

Complex terrain is often characterized by mechanical sources, which force the initiation of convection in unstable atmospheric conditions, resulting in severe weather such as thunderstorms and hail, etc. With respect to the synoptic prevailing wind, the terrain can also cause heavy precipitation by converging flow and stationary rain bands. Rain gauges can provide a direct measure of accurate precipitation at a point station. However, low accessibility and high maintenance costs limit the ability to install high-resolution rain gauge networks in mountainous regions. Thus, quantitative precipitation estimation (QPE) through remote sensing using weather radar plays an important role in securing observation information on rainfall amounts in mountainous areas. 
In this study, we first analyzed the statistics of hazardous weather events retrieved from radar-based rainfall estimates over the Korean Peninsula according to complex topography. In order to analyze the frequency of occurrence of each type of hazardous weather such as torrential rain, hail, and snowfall according to orographic conditions, we used radar-based QPE. We investigated the correlation between topographic characteristics such as terrain altitude, wind direction, and downwind side and the frequency of occurrence and development of hazardous weather phenomena. 
We also examined the accuracy of QPE relating to rainfall mechanisms including radar echo top height for each warm and cold season. We analyzed the accuracy of QPEs according to various methods using radar reflectivity, dual-polarization parameters, and radar attenuation. We analyzed precipitation estimation error factors that may be caused by terrain shielding and high radar beam height in mountainous areas. We explored QPE errors based on radar beam height and echo intensity to improve the accuracy of QPE. 
Furthermore, in order to provide hazardous weather information specialized for the mountainous region, we have planned to develop an algorithm to estimate the probability of severe weather due to topographic characteristics by merging terrain altitude, atmospheric instability, and radar echo intensity by calculating Froude number using radar-based three-dimensional wind (Wind Synthesis System using Doppler Measurements, WISSDOM). In conjunction with the technology for calculating stationary precipitation information using radar echo image processing techniques, we aim to strengthen the ability to respond to dangerous weather by providing information on possible areas of heavy rain, snowfall, and extreme wind due to complex terrain.

 

How to cite: Lee, S., Park, J.-W., Mo, S.-J., and Gu, J.-Y.: Statistical Analysis of Radar-based Quantitative Precipitation Estimation over Complex terrain in Korea and Development of User-oriented Services for Mountainous Regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14813, https://doi.org/10.5194/egusphere-egu24-14813, 2024.

EGU24-16067 | ECS | Posters on site | AS1.35

High-resolution model evaluation with self-supervised neural network approach targeted on severe storms over the Alps 

Daniele Corradini, Claudia Acquistapace, and Paula Bigalke

As climate change advances, the Alps are expected to experience increasingly intense thunderstorms, which are likely to cause more damage due to floods and landslides. This study aims at evaluating extreme precipitation in weather models over complex terrains where orography causes the hardest challenges to precipitation prediction. 

Our preliminary analysis assessed which infrared and visible satellite channels are most effective in predicting precipitation, by examining the MSG satellite channels and radar-derived rain products. This assessment considered the influence of terrain by comparing data from flatlands and more complex topographies.

We will then use a combination of the selected channels to train a self-supervised machine learning (ML) algorithm for both observations and model outputs. We will exploit the space where cloud classes are identified, known as feature space, in two distinct ways to evaluate the ICON-GLORI model. Firstly, we pinpoint significant cases of extreme precipitation and simulate them using the ICON-GLORI model. This data is then input into the observation-trained ML algorithm to determine the cluster within the feature space where the simulated cases will be categorized. Secondly, we construct a feature space using the ensemble ICON-GLORI model. A showcase of the ML algorithm trained using the cloud optical thickness from 2015 imagery over Germany will demonstrate the potential of this approach.

How to cite: Corradini, D., Acquistapace, C., and Bigalke, P.: High-resolution model evaluation with self-supervised neural network approach targeted on severe storms over the Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16067, https://doi.org/10.5194/egusphere-egu24-16067, 2024.

EGU24-18557 | ECS | Orals | AS1.35

Testing the capability of the WRF model on representing temperature inversions in alpine basins and valleys 

Katharina Perny, Herbert Formayer, and Imran Nadeem

Persistent inversions and associated low wind situations during the winter months often lead to air pollution problems in alpine basins and valleys, regardless of emission levels. The aim of this work is to determine how well high-resolution simulations with the Weather Research and Forecasting (WRF) model are able to reproduce the occurrence and weather conditions during temperature inversions in complex topography.

The city of Graz in south-eastern Austria often experiences increased strength and persistence of winter inversions due to its location and local topography. Experiments in this area with the WRF model show a better reproduction of these weather conditions when the shortwave radiation scheme Dudhia is used instead of the RRTMG, while variations in the microphysics and planetary boundary schemes did not lead to relevant changes in the model results.

In a next step, additional basins and alpine valleys will be investigated to determine the influence of shape and extent of the topography on the results.

The model is forced with the ECMWF-IFS analysis data with a spatial resolution of 9 km. Two one-way nested domains with resolutions of 3 and 1 km are used to investigate what resolution is required to adequately represent the local topographic effects. The model results are compared with station and radiosonde observations as well as with the analysis and nowcasting system INCA for Austria.

How to cite: Perny, K., Formayer, H., and Nadeem, I.: Testing the capability of the WRF model on representing temperature inversions in alpine basins and valleys, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18557, https://doi.org/10.5194/egusphere-egu24-18557, 2024.

EGU24-19261 | Posters on site | AS1.35

Analysis of surface temperature and precipitation trends and climate indices in Spanish mountain areas 

Ramón Viloria and Verónica Tricio

Several studies and observations suggest that global warming processes are more prevalent in mountain areas, showing higher rates of warming and more pronounced changes in precipitation than in average land data. Snow and ice are highly sensitive to variations in climate. The importance of mountain areas as water reservoirs for the surrounding land and valleys at lower altitudes justifies paying special attention to this type of behaviour and to the changes brought about by global warming. This interest is enhanced by the special environmental sensitivity of mountain ecosystems, and the difficult balance between these fragile ecosystems and their use as tourist resources or winter resorts.

In this paper we analyse climate data collected at mountain weather stations in Spain in time series up to 80 years. Stations in mountain areas are not numerous and are sometimes very scattered; nevertheless, we have selected the available data on temperatures, precipitation and other meteorological variables at stations located in the various mountain ranges throughout the Iberian Peninsula. For the selected stations, trends in temperatures (mean, maximum and minimum) have been studied and a seasonal analysis has been carried out. In addition, the data were processed with RClimDex, statistical and climatic software package, to evaluate Climate Extreme Indices. Cooling and warming patterns have been detected, and changes in precipitation have been analysed, trying to address the distinctive characteristics of mountain areas in the studies conducted. Monthly and seasonal assessments have also been carried out to detect changes in behaviour patterns. In general, good agreement with previously published data has been obtained, although not many studies have been carried out systematically in Spain, except in the Pyrenees area.

How to cite: Viloria, R. and Tricio, V.: Analysis of surface temperature and precipitation trends and climate indices in Spanish mountain areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19261, https://doi.org/10.5194/egusphere-egu24-19261, 2024.

Mountains play a crucial role in the climate system at various temporal and spatial scales. Additionally, they serve as vital sources of resources, such as fresh water, and host a diverse range of biodiversity. This influence on development and natural ecosystems is particularly significant in semi-arid regions like the Sierra de Guadarrama. This mountain range is located in the Iberian Peninsula and has been the subject of official meteorological observations since the mid-20th century. Nevertheless, there is a gap in the knowledge of the rainfall and temperature variability and its drivers in this important region. TROPA-UCM group has been intensively observing and studying this range since 1998 and recently, a methodology has been developed to extend the observations from 1900 to present using data from the ERA20C and in-situ observations. This has enabled longer time series and a deeper analysis of large-scale teleconnection patterns and climate variability, unlike ever before. The analysis includes trends in temperature, snow precipitation, and snowpack duration. Variations in precipitation and temperature have been identified, providing valuable information for estimating potential changes in seasonal runoff and rainfall intensity. This information can be of great use to organizations responsible for the management of this area, for developing adaptation strategies for new scenarios and to improve seasonal to decadal predictions.

 

 

How to cite: Durán, L., González-Cervera, Á., and Rodríguez-Fonseca, B.: Analysis of climate variability and teleconnection patterns in Sierra de Guadarrama (Iberian Peninsula) using 120-year observed and reconstructed time series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19545, https://doi.org/10.5194/egusphere-egu24-19545, 2024.

Analysis of surface precipitation accumulations upstream, near-shore, and adjacent to the Olympic mountains from the 17 December 2015 case during OLYMPEX using Weather Research and Forecasting (WRF) simulations, the NPOL dual-polarization radar, and high-resolution soundings investigates the role of low-level blocking on upstream precipitation enhancement. Past work shows that frontal systems often slow while approaching complex terrain if the Froude number is sufficiently low. Low-level blocking of stable air ahead of a front can modify precipitation distributions by frontal deformation, slowing, splitting, or merging. Observed coastal sounding-derived vertical stability profiles indicate high levels of low-level stability and significant vertical wind shear, which showed little change while a warm front propagated northeastward and stalled as the stable air mass likely dammed against the terrain. Radial velocity from the NPOL radar and simulated wind fields indicate strong down-valley flow coupled with a frontal jet also contributed to long-lasting Kelvin-Helmholtz (KH) waves extending offshore.

Using WRF simulations along with OLYMPEX observations, we examined the evolution of precipitation upstream of complex terrain by breaking down the distribution of pre-frontal and frontal precipitation accumulations as the warm front approached the Olympic Peninsula. Through dividing the event into regions upstream of NPOL and into timeframes relative to landfall, results indicate pre-warm frontal precipitation accumulations decrease with distance upstream of the coast with the highest accumulations present over the terrain. As the front's translation speed slowed and eventually stalled, the warm frontal period accumulations are highest far upstream of the coast and over the terrain, with lesser accumulations in the middle region. These results indicate that upstream precipitation enhancement upstream is an indirect effect of the terrain influencing the frontal shape and propagation, resulting in enhanced frontal precipitation accumulations.

How to cite: Hence, D. and James, S.: Evolution of Surface Precipitation Accumulations Upstream of the Olympic Mountains using Observations and Simulations: An OLYMPEX Case Study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20124, https://doi.org/10.5194/egusphere-egu24-20124, 2024.

EGU24-268 | ECS | Orals | AS1.18

Heavy-Precipitating Mid-Tropospheric Cyclonic Systems of the Indian Summer Monsoon in a Warming Climate 

Sumit K. Mukherjee, Ayantika Dey Choudhury, and Raghavan Krishnan

Since the last couple of decades, western India has been experiencing persistent, intense rain episodes frequently during the summer monsoon season. Most of the pluvial episodes are accompanied by diverse convective systems modulated by the background monsoon circulation. As the climate warms, the changing environmental conditions affect the nature and intensity of the weather systems. This study discusses the evolving large-scale conditions under global warming, along with the recent changes in the occurrence of a special class of heavy-precipitating synoptic systems, the mid-tropospheric cyclones (MTCs). Observed particularly over the Northeast Arabian Sea, MTCs exhibit pronounced mid-level vorticity with minimal signature at the surface. Observational results suggest significant increasing trends in deep convection and heavy precipitation over western India during the summer monsoon season. The background conditions are dominated by warming in the Arabian Sea and the Indian Ocean, accompanied by strengthening of cyclonic circulation and ascending motion at mid-level over western India. An objective vortex identification using reanalysis dataset indicates a rise in the seasonal frequency and duration of heavy precipitating mid-tropospheric cyclonic systems over western India, resulting in a significant amplification of precipitation from these systems. Furthermore, outputs from seven global climate models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) are used to assess the potential changes in the large-scale patterns conducive to the development and sustenance of mid-tropospheric cyclonic systems over western India with continued global warming following the Shared Socioeconomic Pathway 5-8.5 (SSP5-8.5) scenario. The models project stronger moisture transport over western India that triggers greater moisture convergence along the Indian west coast, aided by elevated water vapor content due to local sea surface warming. We also notice an increase in seasonal mean ascent and relative vorticity, particularly, at the middle troposphere, thereby creating a favorable setting for the occurrence of MTCs and the deep convective clouds in the late 21st century. This interplay between circulation–convection–precipitation on different spatiotemporal scales over the South Asian monsoon domain carries significant implications for assessment of regional hydrological extremes in a warming climate.

How to cite: K. Mukherjee, S., Dey Choudhury, A., and Krishnan, R.: Heavy-Precipitating Mid-Tropospheric Cyclonic Systems of the Indian Summer Monsoon in a Warming Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-268, https://doi.org/10.5194/egusphere-egu24-268, 2024.

EGU24-823 | ECS | Orals | AS1.18 | Highlight

What drives variability of the Australian summer monsoon? 

Hanna Heidemann, Josephine Brown, and Sugata Narsey

The variability of northern Australian rainfall is related to local processes and remote teleconnections, which operate on subseasonal to interdecadal timescales. This includes the Madden-Julian Oscillation, Indian Ocean Dipole, El Niño-Southern Oscillation (ENSO) and Interdecadal Pacific Oscillation. The influence of these climate drivers and local sea surface temperatures (SSTs) on northern Australian rainfall evolves during the wet season, from austral spring through to autumn. Our study shows that ENSO as well as SSTs in the Timor Sea, Arafura Seas and Coral Sea are the key sources of rainfall variability in the pre-monsoonal months September to November. SST indices explained up to 50% of variance in observed northern Australian rainfall in October and November between 1940 and 2023. However, the teleconnection between northern Australian rainfall and ENSO, and also the influence of local SSTs, breaks down with the onset of the Australian summer monsoon in late December. This leads to 0% explained variance in northwestern Australian rainfall and 9% explained variance in northeastern Australian rainfall in January using SST indices only. This presentation will discuss which processes and feedbacks might instead drive rainfall variability over northern Australia during the monsoon season and how they differ from pre- and post-monsoonal conditions.

How to cite: Heidemann, H., Brown, J., and Narsey, S.: What drives variability of the Australian summer monsoon?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-823, https://doi.org/10.5194/egusphere-egu24-823, 2024.

EGU24-962 | ECS | Posters on site | AS1.18

Shifting precipitation pattern during Indian summer monsoon 

Akanksha Sharma and Ashok Priyadarshan Dimri

Precipitation has a significant degree of temporal and spatial variability over the Indian region. A small change in precipitation frequency and its distribution may affect agriculture and water resources and can lead to extreme events such as flood and drought. Number of precipitating days and their spatial distribution has significant impact on many aspects of the socio-economic environment. In present study, 91-days climatology is used to enhance robustness and to reduce uncertainty of the time series. Further, Mann Kendall trend test and Pettitt’s test for change point detection is used for analysis of the number of precipitating days and corresponding precipitation over India and its sub-regions. India Meteorological Department (IMD) gridded dataset and ERA5 reanalysis dataset having resolution 0.25° x 0.25° is used for the period 1902-2020 and 1940-2020 respectively. Our results show that there is a positive trend of number of precipitating days and precipitation over northwest and negative trend over central northeast and northeast India. Indicating a westward shift of precipitation during monsoon season. Change point analysis shows majority of these changes occur after 1970. Positive precipitation anomaly is observed in the month of September over India, with the exception of the hilly and central northeast showing extension of higher precipitation from month of July-August to July-August-September. This extension is probably due to the strengthening of wind during recent time (1971-2020) which brought more moisture to the Indian landmass. Furthermore, increased moisture transfer from the Bay of Bengal has also been seen compared to the early period (1940-1970). Overall, the results of this study will help in understanding the impact of climate change on Indian summer monsoon that will assist in policy making and adapting water management practices.

How to cite: Sharma, A. and Dimri, A. P.: Shifting precipitation pattern during Indian summer monsoon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-962, https://doi.org/10.5194/egusphere-egu24-962, 2024.

EGU24-1774 | Orals | AS1.18

Impact of AMV on rainfall intensity distribution and timing of theWest African Monsoon in DCPP-C-like simulations 

Elsa Mohino, Paul-Arthur Monerie, Juliette Mignot, Moussa Diakhaté, Markus Donat, Christopher David Roberts, and Francisco Doblas-Reyes

Previous studies agree on an impact of the Atlantic Multidecadal Variability (AMV) on total seasonal rainfall amounts over the Sahel. However, whether and how AMV affects the distribution of rainfall or the timing of the West African Monsoon is not well known. Here we seek to explore these impacts by analyzing daily rainfall outputs from climate model simulations with an idealized AMV forcing imposed in the North Atlantic, which is representative of the observed one. The setup follows a protocol largely consistent with the one proposed by the Component C of the Decadal Climate Prediction Project (DCPP-C). We start by evaluating model's performance in simulating precipitation, showing that models underestimate it over the Sahel, where the mean intensity is consistently smaller than observations. Conversely, models overestimate precipitation over the Guinea Coast, where too many rainy days are simulated. In addition, most models underestimate the average length of the rainy season over the Sahel, some due to a too late monsoon onset and others due to a too early cessation. In response to a persistent positive AMV pattern, models show an enhancement in total summer rainfall over continental West Africa, including the Sahel. Under a positive AMV phase, the number of wet days and the intensity of daily rainfall events are also enhanced over the Sahel. The former explains most of the changes in seasonal rainfall in the northern fringe, while the latter is more relevant in the southern region, where higher rainfall anomalies occur. This dominance is connected to the changes in the number of days per type of event: the frequency of both moderate and heavy events increases over the Sahel’s northern fringe. Conversely, over the southern limit, it is mostly the frequency of heavy events which is enhanced, affecting the mean rainfall intensity there. Extreme rainfall events are also enhanced over the whole Sahel in response to a positive phase of the AMV. Over the Sahel, models with stronger negative biases in rainfall amounts compared to observations show weaker changes in response to AMV, suggesting systematic biases could affect the simulated responses. The monsoon onset over the Sahel shows no clear response to AMV, while the demise tends to be delayed and the overall length of the monsoon season enhanced between 2 and 5 days with the positive AMV pattern. The effect of AMV on the seasonality of the monsoon is more consistent to the west of 10ºW, with all models showing a statistically significant earlier onset, later demise and enhanced monsoon season with the positive phase of the AMV. Our results suggest a potential for the decadal prediction of changes in the intraseasonal characteristics of rainfall over the Sahel, including the occurrence of extreme events.

How to cite: Mohino, E., Monerie, P.-A., Mignot, J., Diakhaté, M., Donat, M., Roberts, C. D., and Doblas-Reyes, F.: Impact of AMV on rainfall intensity distribution and timing of theWest African Monsoon in DCPP-C-like simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1774, https://doi.org/10.5194/egusphere-egu24-1774, 2024.

EGU24-1908 | ECS | Orals | AS1.18 | Highlight

Future land use influences on the global monsoon: An energetic perspective 

Nora L. S. Fahrenbach, Robert Jnglin Wills, and Steven J. De Hertog

Understanding the impact of future land use changes on the global monsoon system is crucial for the economy, water supply and food security. Here, we use future deforestation and afforestation simulations under different SSP scenarios from 10 CMIP6 models participating in the Land Use Model Intercomparison Project (LUMIP). We apply an energy flux potential (EFP) framework to connect shifts in the Intertropical Convergence Zone and regional monsoons to changes in the atmospheric energy transport, and examine the contribution from individual flux components (latent heat flux, sensible heat flux, shortwave and longwave radiation). The linearity of this method allows us to attribute atmospheric EFP changes to different land and ocean regions without the need for additional simulations.

We find consistent zonal-mean precipitation shifts over oceanic regions across models in the deforestation and afforestation scenarios. However, changes in the global monsoon (as represented by zonal-mean precipitation changes over land) show large model dependence. The energy flux analysis reveals a consistent mechanism across models: The surface latent heat flux is the dominant driver of land use-induced changes in EFP in the tropics. In most regions and models, an increase in the latent heat flux component of EFP corresponds to tropical precipitation decrease and vice versa.

Our regional analysis reveals that remote oceanic energy-budget anomalies are the main contributor to the global EFP patterns and monsoon precipitation anomalies for all models, while land energy-budget anomalies modulate both patterns over land. Decomposing the EFP pattern into the contribution from different land regions indicates model consensus regarding the strong contribution from North and South America to the land-only anomaly, while inter-model differences primarily stem from different model responses to African land use change. These findings highlight the complexity of rainfall shifts to future land use change scenarios and also emphasize the value of the energy flux potential method to quantitatively link remote forcing to regional rainfall changes.

How to cite: Fahrenbach, N. L. S., Jnglin Wills, R., and De Hertog, S. J.: Future land use influences on the global monsoon: An energetic perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1908, https://doi.org/10.5194/egusphere-egu24-1908, 2024.

EGU24-3014 | Posters on site | AS1.18

Multidecadal variability and decadal prediction of wintertime surface air temperature over the East Asian winter monsoon domain 

Jianping Li, Tiejun Xie, Xinxin Tang, Hao Wang, Cheng Sun, Juan Feng, Fei Zheng, and Ruiqiang Ding

This paper studies the influence of the winter NAO on the multidecadal variability of winter East Asian surface air temperature (EASAT) and its decadal prediction. The observational analysis shows that the winter EASAT and East Asian minimum SAT (EAmSAT) display strong in-phase fluctuations and a significant 60–80-year multidecadal variability, apart from a long-term warming trend. The winter EASAT experienced a decreasing trend in the last two decades, which is conducive to the occurrence of winter extremely cold events in East Asia in recent years. The winter NAO leads the detrended winter EASAT by 12–18 years with a maximumly significant positive correlation at the leading time of 15 years. Further analysis shows that ENSO may affect winter EASAT interannual variability, but does not affect the robust leading relationship between the winter NAO and EASAT. We present the coupled oceanic-atmospheric bridge (COAB) mechanism of the NAO influences on winter EASAT multidecadal variability through its accumulated delayed effect of ~15 years on the Atlantic Multidecadal Oscillation (AMO) and Africa–Asia multidecadal teleconnection (AAMT) pattern. BaseThis paper studies the influence of the winter NAO on the multidecadal variability of winter East Asian surface air temperature (EASAT) and its decadal prediction. The observational analysis shows that the winter EASAT and East Asian minimum SAT (EAmSAT) display strong in-phase fluctuations and a significant 60–80-year multidecadal variability, apart from a long-term warming trend. The winter EASAT experienced a decreasing trend in the last two decades, which is conducive to the occurrence of winter extremely cold events in East Asia in recent years. The winter NAO leads the detrended winter EASAT by 12–18 years with a maximumly significant positive correlation at the leading time of 15 years. Further analysis shows that ENSO may affect winter EASAT interannual variability, but does not affect the robust leading relationship between the winter NAO and EASAT. We present the coupled oceanic-atmospheric bridge (COAB) mechanism of the NAO influences on winter EASAT multidecadal variability through its accumulated delayed effect of ~15 years on the Atlantic Multidecadal Oscillation (AMO) and Africa–Asia multidecadal teleconnection (AAMT) pattern. Based on the COAB mechanism an NAO-based linear model for predicting winter decadal EASAT is constructed, with good hindcast performance. The winter EASAT for 2020–2034 is predicted to keep on fluctuating downward until ~2025, implying a high probability of occurrence of extremely cold events in coming winters in East Asia, and then turn towards sharp warming. The predicted 2020/21 winter EASAT is almost the same as the 2019/20 winter.d on the COAB mechanism an NAO-based linear model for predicting winter decadal EASAT is constructed, with good hindcast performance. The winter EASAT for 2020–2034 is predicted to keep on fluctuating downward until ~2025, implying a high probability of occurrence of extremely cold events in coming winters in East Asia, and then turn towards sharp warming. The predicted 2020/21 winter EASAT is almost the same as the 2019/20 winter.

How to cite: Li, J., Xie, T., Tang, X., Wang, H., Sun, C., Feng, J., Zheng, F., and Ding, R.: Multidecadal variability and decadal prediction of wintertime surface air temperature over the East Asian winter monsoon domain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3014, https://doi.org/10.5194/egusphere-egu24-3014, 2024.

This study identifies break events of the South China Sea (SCS) summer monsoon (SCSSM) based on 42 years of data from 1979 to 2020, and investigates their statistical characteristics and associated atmospheric anomalies. A total of 214 break events are identified by examining the convection evolution during each monsoon season. It is found that most events occur between June and September and show a roughly even distribution. Short-lived events (3–7 days) are more frequent, accounting for about two thirds of total events, with the residual one third for long-lived events (8–24 days).

The SCSSM break is featured by drastic variations in various atmospheric variables. Particularly, the convection and precipitation change from anomalous enhancement in adjoining periods to a substantial suppression during the break, with the differences being more than 60 W m−2 for outgoing longwave radiation (OLR) and 10 mm d−1 for precipitation. This convection/precipitation suppression is accompanied by an anomalous anticyclone in the lower troposphere, corresponding to a remarkable westward retreat of the monsoon trough from the Philippine Sea to the Indochina Peninsula, which reduces the transportation of water vapor into the SCS. Besides, the pseudo-equivalent potential temperature (θse) declines sharply, mainly attributable to the local specific humidity reduction caused by downward dry advection. Furthermore, it is found that the suppressed convection and anomalous anticyclone responsible for the monsoon break form near the equatorial western Pacific and then propagate northwestward to the SCS.

How to cite: Bi, M., Xu, K., and Lu, R.: Monsoon Break over the South China Sea during Summer: Statistical Features and Associated Atmospheric Anomalies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3424, https://doi.org/10.5194/egusphere-egu24-3424, 2024.

The Tibetan Plateau (TP), known as Earth's “Third Pole”, has experienced significant warming since 1980. As an important component of the summer monsoon, the TP rapid warming profoundly impacts both Asian and global climate systems. While previous studies focused on surface temperature, our research uses multiple reanalysis datasets to investigate atmospheric temperature changes over the TP. All three reanalysis datasets revealed an upper tropospheric warming above the TP centered around 250 hPa. The upper tropospheric warming rate is approximately 0.3 K/decade over the 1980-2021 period, faster than those at the same latitude. An energy budget analysis is performed to attribute this warming to different processes. The primary contribution arises from the convection process, contributing around 0.4K/decade. Cloud warms the upper troposphere by an additional 0.2K/decade. Other radiative processes and adiabatic processes play counterpart roles that weaken the upper tropospheric warming. The warming center is most significant in spring. In contrast to other seasons, warming in spring primarily results from the adiabatic process, rather than the convection process. Although different in specific values, all three reanalysis datasets show a similar contribution ratio of each physical process.

How to cite: Wei, Y. and Wang, Y.: Quantifying Contributions from Different Physical Processes to the Atmospheric Warming over the Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3865, https://doi.org/10.5194/egusphere-egu24-3865, 2024.

EGU24-4467 | ECS | Orals | AS1.18

The Impacts of Inundating Australia on Australian Monsoon 

Zhiyuan Yang, Sugata Narsey, Dongryeol Ryu, Murray Peel, Min-Hui Lo, and Kaighin McColl

Large-scale perturbations in land surface characteristics have been found to induce disturbances in the overlying atmosphere via land-atmosphere coupling. The perturbations can lead to changes in hydroclimatic variables, such as precipitation and air temperature, or in atmospheric circulation patterns. However, the local and remote atmospheric responses to continental-scale changes in land surface water have not been well studied in Australia. In this study, using the Community Earth System Model 2 (CESM2) of the National Center for Atmospheric Research (NCAR), we investigate the changes in Australian monsoon, which primarily impacts the northern Australian climate, in response to an extreme surface condition: the whole Australia being treated as a shallow lake in model simulations. The simulation results show that a continental-scale lake would extend the Australian monsoon season via earlier onset and later end. We find that the most significant changes in the simulated precipitation occur during the pre-monsoon period (e.g., early October to mid November). Considering that the traditional scheme used to explain monsoonal rainfall by the theory of land-sea thermal contrasts is not consistent with the simulated precipitation patterns, this study analyzes the changes in moist static energy (MSE) budget, the simulation with a hypothetical lake features an atmospheric condition that favors the formation of precipitation: increased moisture convergence and dry static energy divergence, which might be associated with the increased net energetic forcing and export of MSE. We also confirm the dominant role of atmospheric circulation in determining the variability of precipitation over northern Australia in wet season via examining the regional moisture recycling. A relative impact computation upon components in the moisture budget shows that the dynamic component of the vertical advection of moisture contributes the most to the temporal evolution of precipitation over northern Australia in wet season.

How to cite: Yang, Z., Narsey, S., Ryu, D., Peel, M., Lo, M.-H., and McColl, K.: The Impacts of Inundating Australia on Australian Monsoon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4467, https://doi.org/10.5194/egusphere-egu24-4467, 2024.

EGU24-4822 | Orals | AS1.18 | Highlight

Climate change is not the primary cause of extreme monsoons in Pakistan 

Moetasim Ashfaq, Nathaniel Johnson, Fred Kucharski, Noah Diffenbaugh, Adnan Abid, and Katherine Evans

Monsoons have been frequently severe in Pakistan in the last few decades, leading to extreme droughts and floods of unprecedented proportions. The wide belief is that these changing precipitation patterns are mainly due to climate change. However, considering this region's long history of floods and droughts, it is unwise to rule out the role of natural climate variability without a careful diagnosis. This study examines the contribution of oceanic and atmospheric variability to unusual precipitation distributions in Pakistan. We find that variations in sea surface temperatures in the tropical Pacific and northern Arabian Sea and internal atmospheric variability related to the circumglobal teleconnection pattern and the subtropical westerly jet stream account for 74% of monthly summer precipitation variability in the 21st century. Several of these forcings have co-occurred with record strength during episodes of extreme monsoons, compounding the overall effect. Climate change may have contributed to increased variability and the in-phase co-occurrences of the identified mechanisms, but further research is required to confirm any such connection.

How to cite: Ashfaq, M., Johnson, N., Kucharski, F., Diffenbaugh, N., Abid, A., and Evans, K.: Climate change is not the primary cause of extreme monsoons in Pakistan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4822, https://doi.org/10.5194/egusphere-egu24-4822, 2024.

EGU24-5941 | ECS | Orals | AS1.18

Future changes in South Asian summer monsoon circulation under global warming: Role of the Tibetan Plateau heating 

Haolin Luo, Ziqian Wang, Chao He, Deliang Chen, and Song Yang

The South Asian summer monsoon (SASM) is a significant monsoon system that exerts a profound impact on climate and human livelihoods. According to 38 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), the SASM circulation is projected to weaken significantly under global warming as seen in the weakened low-level westerly wind over the northern tropical Indian Ocean; however, the associated climate dynamics is still under debate. Here, we identify that the weakened low-level westerly wind is closely related to the enhanced diabatic heating over the Tibetan Plateau (TP), which corresponds with increased summer precipitation in the future. Further analyses and numerical experiments suggest that the intensified TP heating triggers an anomalous meridional circulation with ascending motions over the plateau and descending motions to the south, leading to an anomalous low-level anticyclone over the northern tropical Indian Ocean. This anticyclone greatly weakens the prevailing low-level westerly wind of the SASM through easterly anomalies at the anticyclone’s southern flank. Moisture budget analysis further reveals that increased atmospheric water vapor, rather than the vertical dynamic component, makes the largest contribution to the increased precipitation over the TP. This result confirms that the enhanced TP heating is a driver of atmospheric circulation change and contributes to weakening the SASM circulation.

How to cite: Luo, H., Wang, Z., He, C., Chen, D., and Yang, S.: Future changes in South Asian summer monsoon circulation under global warming: Role of the Tibetan Plateau heating, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5941, https://doi.org/10.5194/egusphere-egu24-5941, 2024.

EGU24-7033 | ECS | Orals | AS1.18 | Highlight

The role of midlatitude dry air during the withdrawal of the Indian monsoon 

Akshay Deoras, Andrew Turner, Ambrogio Volonté, and Arathy Menon

The Indian summer monsoon (ISM) supplies over 75% of the country’s annual precipitation, profoundly impacting lives of over a billion people. Significant variability in the timing of its onset and withdrawal has a direct impact on the agricultural sector and other users of water resources. Previous studies have shown that a wedge of mid-tropospheric dry air emanating from the midlatitudes is present over India during early summer, which is much shallower in the vertical toward the southeast of India. Following the strengthening of low-level monsoon winds during the onset, the dry air retreats from the southeast due to increased moistening by shallow cumulus congestus clouds, driving the north-westward progression of the ISM. The withdrawal of the ISM is observed to progress in a southeast direction during September–October, but there is a lack of a conceptual model. In this study, we use observations and the ERA5 reanalysis to understand the dynamics and thermodynamics of the withdrawal. We find that a mid-level dry intrusion re-appears over the northwest of India around mid-September. Vertical profiles associated with this dry air show how the most unfavourable environment for deep convection occurs in the northwest, where the withdrawal occurs first. As the withdrawal progresses, the wedge of dry air deepens throughout its horizontal extent and descends. This stabilises the troposphere, suppressing deep convection and ultimately driving the withdrawal toward the southeast. By mid-October, the dry air engulfs most of India, causing the ISM to withdraw from the entire country. Thus, the strengthening of the mid-level dry advection from the midlatitudes can explain the withdrawal of the ISM, and the mechanism driving the local withdrawal can be considered as the reverse of that at play during the progression of the onset. This work establishes a new paradigm for the withdrawal of the Indian monsoon in terms of midlatitude interactions, which could be tested for other monsoon regions.

How to cite: Deoras, A., Turner, A., Volonté, A., and Menon, A.: The role of midlatitude dry air during the withdrawal of the Indian monsoon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7033, https://doi.org/10.5194/egusphere-egu24-7033, 2024.

EGU24-7080 | ECS | Posters on site | AS1.18

Summer monsoon transition induced microseisms observed at the South China Sea seabed 

Yulong Zhou, Fansheng Kong, Han Zhang, Zhangju Liu, Weiwei Ding, and Jiabiao Li

It has long been recognized that complex interactions and energy conversions between the atmosphere-ocean system and the solid Earth can generate strong ambient noise field, known as microseisms which can be detected worldwide. Under the vast majority of circumstances, such seismic energy is believed to be induced by tropical cyclones. Whether unidirectional propagating winds, such as monsoons, can generate microseisms lacks solid seismic evidence. Here we utilize broadband seismic data recorded by seven ocean-bottom seismometers (OBSs) deployed in the South China Sea basin and 17 terrestrial stations to systematically investigate possible influences of the summer monsoon transition on the microseisms. Spectral analyses over time reveal significant seismic energy in the secondary microseisms frequency band (0.1−0.5 Hz) during 18th to 29th May, coinciding with the period of the summer monsoon transition occurring in the South China Sea. Polarization analyses and time-space variation of offshore surface wind field indicate that the source region of the observed secondary microseisms is located at the South China Sea. Given the absence of tropical cyclones during this time, we attribute the observed strong secondary microseisms to the summer monsoon transition. When the near-surface wind field is transformed to be southwest, ocean waves are driven to propagate northeastward and interact with an opposing wave train which represents precursor waves and is reflected by coastlines, generating the secondary microseisms. This study provides solid evidence for a causal link between the monsoon transition and microseisms, highlighting the potential of applying ocean bottom seismic observations for monitoring and characterizing monsoon transition and ocean activities.

How to cite: Zhou, Y., Kong, F., Zhang, H., Liu, Z., Ding, W., and Li, J.: Summer monsoon transition induced microseisms observed at the South China Sea seabed, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7080, https://doi.org/10.5194/egusphere-egu24-7080, 2024.

EGU24-7210 | Posters on site | AS1.18

Drought risks based on changes in atmospheric evaporative demand due to plant response to CO2 levels 

Kyung-Ja Ha, Ji-Hye Yeo, Daeha Kim, and Hyeonho Lee

The temperature and CO2 increase due to global warming are expected to exacerbate atmospheric water demand, worsening future drought conditions. Recent studies have revealed that evapotranspiration is regulated by stomatal response in response to CO2 increase. However, understanding droughts defined based on evapotranspiration remains incomplete as it does not adequately integrate plant responses to anticipated drought conditions. In this study, we aimed to evaluate the frequency and extent of future drought events by comparing the Evaporative Stress Index (ESI) using two potential evapotranspiration (Ep) values capturing atmospheric evaporative demand. The first Ep utilized past data and predictions from the Coupled Model Intercomparison Project Phase 6, assuming a constant surface resistance (rs) without considering plant responses. The second Ep accounted for the sensitivity of rs to increased CO2. Our findings indicate a significant increase in rs due to elevated CO2, leading to substantial changes in drought frequency and extent. While both non-vegetative response and plant response are expected to increase in future scenarios, an ESI that ignores plant responses tends to overestimate drought risk. Therefore, our study emphasizes the importance of integrating the sensitivity of rs to evaporative demand and CO2 level increases when assessing drought risk.

How to cite: Ha, K.-J., Yeo, J.-H., Kim, D., and Lee, H.: Drought risks based on changes in atmospheric evaporative demand due to plant response to CO2 levels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7210, https://doi.org/10.5194/egusphere-egu24-7210, 2024.

EGU24-7608 | Posters on site | AS1.18

Future projection of East Asian Summer Monsoon precipitation under 1.5°C, 2°C, and 3°C global warming levels 

MinAh Sun, Hyun Min Sung, Jisun Kim, Jae-Hee Lee, Sungbo Shim, and Young-Hwa Byun

The East Asian summer monsoon (EASM) is an influential climate system that contributes to approximately 70% of the annual precipitation in the Asia region. Extensive research has been conducted on monsoon changes in response to future climate. In this study, we analyzed the characteristics of the EASM considering specific global warming level (GWL) using Coupled Model Inter-comparison Project 6 (CMIP6) simulations. The 30 CMIP6 models effectively captured the migration of the monsoon in present-day (PD), showing a pattern correlation coefficient of 0.91, which represents an improvement over values reported in previous studies. Dividing the monsoon period into P1 (first primary peak; 33-41 pentad) and P2 (from P1 to the withdrawal; 42-50 pentad), the frequency and amount of weak to moderate precipitation rates are predominantly higher in P2, while the frequency and amount of moderate to extreme precipitation rates are notably higher in P1. The CMIP6 models project a significant increase in precipitation under a warming climate, accompanied by a longer duration due to earlier onset and delayed termination. Under the three GWLs, the projected precipitation frequency decreases below moderate precipitation rates, while it significantly increases above strong precipitation rates. Additionally, the precipitation tendencies in both P1 and P2 are similar to those of the total period, with significant changes evident at the 3.0 °C GWL. These precipitation changes are associated with an increase in precipitation amount above the 97th percentile and influence the future changes in the EASM under a warmer climate. 

How to cite: Sun, M., Sung, H. M., Kim, J., Lee, J.-H., Shim, S., and Byun, Y.-H.: Future projection of East Asian Summer Monsoon precipitation under 1.5°C, 2°C, and 3°C global warming levels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7608, https://doi.org/10.5194/egusphere-egu24-7608, 2024.

EGU24-7759 | Orals | AS1.18

What advances monsoon onset over India? 

Bidyut Bikash Goswami and Caroline Muller

In the monsoon regions, atmospheric convection is typically stronger over the oceans than over land. Rainfall over land is potentially affected by the dynamic response of the atmosphere to deep convection over the adjacent oceans. Here, we show, in the case of the Indian summer monsoon, that enhanced atmospheric deep convection over the Bay of Bengal ∼2 weeks before onset, advances monsoon onset over India. Since the sea surface temperature of the Bay of Bengal is already hot during spring, warm anomalies further enhance convection that drives a convergence of low-level winds. A part of this circulation response blows from central India to the Bay of Bengal. It paves the way for monsoon circulation over India and advances the onset of monsoon. We tested this hypothesis using an atmospheric model forcing it by warm sea surface temperature anomalies over the Bay of Bengal 10-15 days before monsoon onset.

How to cite: Goswami, B. B. and Muller, C.: What advances monsoon onset over India?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7759, https://doi.org/10.5194/egusphere-egu24-7759, 2024.

Locust infestation has been a serious threat to agriculture and its occurrence of locust infestation is closely related to the climate condition, especially drought. Because agriculture was the main economic activity of China in historical time, damages on agricultural produce due to locust infestation had been recorded continuously in national chronicles for more than 2000 year. In this study, we will utilize the locust infestation records in Chinese historical documents in 1358-1911 to form temporal and spatial series, perform statistical analyses and infer possible changes in East Asian monsoon climate during this period.

We will utilize the digitized meteorological record database in China, called REACHES (Reconstructed East Asian Climate Historical Encoded Series. See Wang et a., 2018, Nature: Scientific Data, 5, 180288), to extract locust records in 1358-1911 corresponding to Ming and Qing dynasties of China to perform analysis. In a previous study (Lin et al., 2020) we had shown that the locust infestation is closely related to the general drought condition in Qing dynasty (1644-1911). In the present study we expand the total period length to include Ming dynasty. We will perform time series analysis as well as spatial analysis to understand the relation of locust infestation and other climate variables.

Previous studies of locust infestation in East Africa by United Nations show that the movement6s of locust swarms are closely related to monsoon fronts. Our preliminary analysis shows that this also appears to be the case in the movements of East Asian locusts. Thus it is possible that we can use the locust infestation series to reconstruct past changes in East Asian monsoon climate.

How to cite: Wang, P. K.: Locust infestation in China in 1358-1911 and its relation with changes in East Asian monsoon climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7856, https://doi.org/10.5194/egusphere-egu24-7856, 2024.

Seasonal prediction of East Asia summer monsoon rainfall (EASMR) is in great demand but remains challenging, because the relationships between the Asian monsoon system and precursors are nonstationary and exhibit significant decadal changes. The present study aims to 1) examine decadal variations of the relationships between the EASMR and predictors used in previous studies and 2) establish a new prediction model using a Bayesian dynamical linear model (DLM), which is capable of capturing the time-evolving relationships between the predictand and predictors whereas the conventional static linear model cannot.

Two predictors were selected previously to predict the EASMR. One is the sea level pressure tendency anomalies over the tropical eastern Pacific from late spring to early summer, which represents remote forcing related to ENSO and has a stable effect on EASMR throughout the analysis period. The other is the sea surface temperature anomaly difference between the northern Indian Ocean (IO) and the WNP during spring through early summer (called IOWPSST), which denotes local air-sea interaction that affects the WNP subtropical high. Results show that the IOWPSST has strong influence on EASMR during 1979 to 2003 (period 1), while from 2004-2017 (period 2) its connection to EASMR evidently weakens. This nonstationary relationship is due to the non-persistence of the enhanced WNP subtropical high during period 2, which is associated with the positive-to-negative phase transition of the Interdecadal Pacific Oscillation since ~2000.

A new prediction model was established using the two predictors with Bayesian DLM. The cross-validation method and a 9-yr independent forward-rolling forecast is applied to test the hindcast and actual forecast ability. Results show that the Bayesian DLM has higher hindcast/forecast skill and lower mean square error compared with static linear model, suggesting that the DLM has advantage in predicting EASMR and is a promising method for seasonal prediction.

How to cite: Xing, W., Han, W., and Zhang, L.: Improving the prediction of East Asia summer monsoon precipitation using a Bayesian dynamic linear model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8515, https://doi.org/10.5194/egusphere-egu24-8515, 2024.

The Siberian High (SH), an important atmospheric system over Eurasia, exhibits notable seasonality—forming in autumn and peaking in the boreal winter. Many previous studies have revealed the characteristics of the SH in its peak phase; however, the SH formation process remains unclear. This study examined the climatological characteristics of SH formation with a cumulative sea-level-pressure series over the Siberian region based on observational data. First, the SH formation dates were objectively detected in both the climatology (October 1, 55th pentad) and individual years. Then, the thermodynamic processes around SH formation were investigated based on these formation dates. The results indicated that, in the lower troposphere, an anticyclonic circulation dominates over the Eurasian continent after SH formation. In the middle troposphere, an anomalous northeast–southwest-oriented ridge and trough appear over upstream of the SH and the coast of Northeast Asia, respectively. In the upper troposphere, the subtropical westerly jet, with its entrance located over the SH, intensifies and migrates southward, accompanying the amplification of its secondary circulation that features downward (upward) motion over Siberia (south of the Tibetan Plateau). The combined effects of the jet-associated circulation, negative vorticity advection and cold advection associated with the ridge and trough, and diabatic cooling contribute to high-level convergence and large-scale subsidence over the SH area, thereby resulting in SH formation. Further diagnosis reveals that dynamic processes play a more important role in SH formation than the thermal processes do.

How to cite: Chen, L.: Processes and mechanisms of the initial formation of the Siberian High during the autumn-to-winter transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8860, https://doi.org/10.5194/egusphere-egu24-8860, 2024.

EGU24-9447 | ECS | Posters on site | AS1.18

Role of Anthropogenic Forcing and Decadal Oscillations on the Delayed Withdrawal of Indian Summer Monsoon 

Aneesh Sundaresan, Tamás Bódai, Sivarajan Sijikumar, and Susmit Subhransu Satpathy

            The mean Indian summer monsoon (ISM) rainfall as well as the duration of monsoon spell have a profound impact on the agriculture practice in the country. Due to the recent increase in surface temperature, global circulation patterns exhibit considerable changes which also affects the characteristics of ISM. The present study aims to find out any long-term changes in the monsoon onset and withdrawal dates over different parts of India and the possible mechanisms behind it. During the last four decades, the trend analysis of ISM onset dates over south India and north-west (NW) India shows an early onset in both regions. However, the trends are statistically less significant. In the case of the monsoon withdrawal dates, trends over NW India and south India show a statistically significant delay of about 6 days/decade and 3.25 days/decade, respectively. As a result, the monsoon season over NW India and south India shows a lengthening of about 7.8 days/decade and 3.5 days/decade, respectively. During the withdrawal phase of the ISM, a stronger monsoon low-level jet and an enhancement of the ISM rainfall have been observed in recent decades. The enhancement in rainfall activity and the strengthening of the low-level jet in the withdrawal phase reaffirms the delayed withdrawal of the ISM in recent decades.

            The role played by factors such as Indian Ocean warming, Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO) on the ISM withdrawal is examined. The AMO has changed its phase from negative to positive in recent decades, particularly after about 1998, which might have played a key role in enhancing the meridional tropospheric temperature gradient. The stronger meridional tropospheric temperature gradient and the Eurasian surface warming observed in recent decades might played a key role in the delayed monsoon withdrawal over NW India. The CESM2 large ensemble data analysis shows that both the external forcing as well as the decadal phase shift of the AMO and PDO, favour the delayed withdrawal, while the latter plays a dominant role.

How to cite: Sundaresan, A., Bódai, T., Sijikumar, S., and Satpathy, S. S.: Role of Anthropogenic Forcing and Decadal Oscillations on the Delayed Withdrawal of Indian Summer Monsoon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9447, https://doi.org/10.5194/egusphere-egu24-9447, 2024.

EGU24-9454 | ECS | Posters on site | AS1.18

Trend and Variability in the Long-Term Relationship Between Eurasian Snow Cover and Indian Summer Monsoon Rainfall 

Dr Pushpa Pandey, Dr Michael Kunz, Dr Suneet Dwivedi, and Dr Bhupendra Nath Goswami

The predictability of Indian Summer Monsoon Rainfall at any given time period depends on the strength of its relationship with predictable drivers like the El Nino–Southern Oscillation (ENSO) that are known to undergo significant epochal variations. While the relationship between Eurasian snow cover fraction and Indian Summer Monsoon Rainfall has also shown a similar epochal variability in recent decades, its stationarity on centennial or longer timescales remains unknown. In the present work two indices of snow cover fraction have been unraveled, on the basis of the observed relationship between the dominant modes of Indian Summer Monsoon Rainfall variability and snow cover fraction over a period of 115 years (1901–2015), that encapsulate its spatio-temporal variability. It has been observed that the relationship between the snow cover fraction indices and Indian Summer Monsoon rainfall have a statistically significant increasing trend with a weak multidecadal variability superimposed on it, making significant positive correlation between the two highly probable in the coming decades. With snow cover fraction driving the North Atlantic Oscillation (NAO) that subsequently drives the Indian Summer Monsoon Rainfall variability, it has been demonstrated that the NAO plays a pivotal role in modulating the teleconnection between the Indian Summer Monsoon Rainfall and snow cover fraction on a multidecadal time scale.

Keywords: El Nino–Southern Oscillation, North Atlantic Oscillation

How to cite: Pandey, D. P., Kunz, D. M., Dwivedi, D. S., and Goswami, D. B. N.: Trend and Variability in the Long-Term Relationship Between Eurasian Snow Cover and Indian Summer Monsoon Rainfall, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9454, https://doi.org/10.5194/egusphere-egu24-9454, 2024.

EGU24-10229 | ECS | Orals | AS1.18

Synchronization patterns of heavy rainfalls between North India and the Sahel Zone on daily timescales 

Felix Strnad, Kieran Hunt, Niklas Boers, and Bedartha Goswami

The dominant drivers of boreal summer precipitation variance in tropical and subtropical regions are the Asian and the North African Summer Monsoon. 
Despite extensive investigation into regional precipitation dynamics, the interaction between these monsoon systems remains hardly understood.
This study employs a complex climate network approach based on extreme rainfall events to uncover synchronously occurring heavy rainfall patterns. 
We identify a synchronization trend during the peak monsoon period in July, linking the rainfall in North India to that in the Sahel Zone.
Our findings indicate that La Ni\~na-like conditions in combination with the Boreal Summer Intraseasonal Oscillation (BSISO) foster the synchronization. 
The convective clouds are subsequently transported by an intensified tropical easterly jet toward North Africa, introducing unusual convection over the Sahel region.

How to cite: Strnad, F., Hunt, K., Boers, N., and Goswami, B.: Synchronization patterns of heavy rainfalls between North India and the Sahel Zone on daily timescales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10229, https://doi.org/10.5194/egusphere-egu24-10229, 2024.

EGU24-10455 | Orals | AS1.18

Monsoon precipitation biases in storm-resolving NextGEMS Earth System Models 

Simona Bordoni and Adrian M. Tompkins

Global Earth System Models at storm-resolving resolutions (SR-ESM, with horizontal resolutions of ~4km) are being developed as part of the nextGEMS collaborative European EU’s Horizon 2020 programme.  Within the Storms & Ocean theme, we are exploring how resolving convective storms, ocean mesoscale eddies, and air-sea interaction on these scales influences tropical circulations and associated precipitation, and their variability.

In this talk, we evaluate the representation of the characteristics of the wet season over core monsoon regions in these SR-ESM, which include assessment of the seasonal cycle of precipitation, the timing of monsoon onset and retreat, and the total accumulated precipitation. These existing biases are compared to those seen in CMIP6 models and  interpreted through the lens of both local and remote moist energy diagnostics based on modern theories of monsoons. Local diagnostics include relative moist static energy (MSE) defined as the difference between local and tropical-mean near surface MSE, which has been recently introduced as a simple measure of the lower and upper-level influences on convective stability and shown to correlate well with monsoon onset dates in both CMIP6 simulations (Bombardi and Boos 2021) and idealized aquaplanet simulations we have conducted. The influence of possible remote biases, such as those of extratropical origin, are explored through analysis of the equator-to-pole MSE gradient. This contrast is central to vertically integrated energy budget frameworks that link changes in monsoonal precipitation to changes in meridional energy fluxes, which in turn scale with the meridional near-surface MSE gradients under diffusive approximations. Biases in this gradient result in smaller or greater advection of low-level MSE into monsoon regions, hence resulting in wet or dry biases, respectively, in monsoonal rainfall.

How to cite: Bordoni, S. and Tompkins, A. M.: Monsoon precipitation biases in storm-resolving NextGEMS Earth System Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10455, https://doi.org/10.5194/egusphere-egu24-10455, 2024.

EGU24-10696 | ECS | Posters on site | AS1.18 | Highlight

African monsoon changes in the Late Cenozoic from the climate modelling perspective 

Daniel Boateng and Sebastian G. Mutz

Africa's climate underwent significant hydroclimate changes in the Late Cenozoic. For instance, the repeated phases of aridification across the continent played a crucial role in shaping the region’s biodiversity and hominid evolution. Consequently, understanding the historical climate variations in the region becomes essential for reconstructing its paleoenvironment and paleobiological history. Moreover, past climates can be used as analogues for potential future climates and thus help us understand the implications of future climate scenarios. The precipitation seasonality and variability in the region are predominantly driven by the African monsoons, which exhibit intricate climate dynamics controlled by both regional and large-scale atmospheric teleconnections. However, due to the complexity of these dynamics and teleconnections, even state-of-the-art General Circulation Models (GCMs) still struggle to accurately reconstruct its past climate variability and provide reliable future projections.

Here, we simulate the response of the African monsoons to different late Cenozoic paleoenvironmental changes, such as atmospheric CO2 concentration (pCO2), orbital forcing, palaeogeography, vegetation, and orography (including the topographic evolution of the East African Rift System (EARS)). We performed time-specific simulations with a high-resolution setup of the GCM ECHAM5-wiso and the paleoenvironmental boundary conditions for the Middle Miocene climate optimum (MMCO; 16.9-14.7 Ma), Middle Miocene climate transition (MMCT; 14.7-13.8 Ma), Mid-Pliocene (MP; ~3 Ma), the Last Glacial Maximum (LGM; ~21 ka), the Mid-Holocene (MH; ~6 ka), and the pre-industrial (PI; the reference year 1850).

Furthermore, we conducted topographic sensitivity experiments of the EARS under the MMC and MMCT conditions to understand the role of tectonics in the evolution of Africa’s climate and atmospheric dynamics. We focused our analysis on disentangling the thermodynamic effects (e.g., water vapour content changes) and dynamic effects (e.g., Hadley circulation) on the monsoon changes and associated atmospheric dynamics (e.g., African Easterly Jet, Somalia Jet, Tropical Easterly Jets, low-level westerlies). Overall, the study provides an overview of hydroclimate and climate dynamics changes over Africa for the past 20 Ma, contributing to the understanding of the feedback between changes in pCO2, orbital forcing, and tectonic events that are relevant for improving future climate prediction.

How to cite: Boateng, D. and G. Mutz, S.: African monsoon changes in the Late Cenozoic from the climate modelling perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10696, https://doi.org/10.5194/egusphere-egu24-10696, 2024.

EGU24-10904 | ECS | Posters on site | AS1.18

Future changes in the South American Monsoon System and its consequences over south-eastern Peru 

Santos J. González-Rojí, Martina Messmer, Christoph C. Raible, and Thomas F. Stocker

Tropical regions in South America are characterized by rich biodiversity, diverse climatic zones and heterogenous weather. This heterogeneity is caused by the South American Monsoon System (SAMS) and the atmospheric low-level jets (LLJ). Both atmospheric circulation features have a critical role in the distribution of moisture and precipitation. The regions located where the rainforest meets the Andes are highly affected by these LLJs. One example is the department of Madre de Dios, located in south-eastern Peru. Its economy and the well-being of the population are highly dependent on natural resources provided by the ecosystem. Hence, understanding how the SAMS and the associated LLJs will change under global warming is important for water management in the region. To investigate the climate change signals, we employ the Weather Research and Forecasting model (WRF; version 3.8.1) at convection-permitting scales (up to 1 km). Two 30-year periods of a global climate simulation are dynamically downscaled for the present (1981–2010) and the future (2071–2100). Thereby, we consider the mitigation scenario representative concentration pathway (RCP) 2.6 and the high-emission scenario RCP8.5.

The validation of the simulation for the present period indicates that while precipitation amounts fall within the range of observational datasets such as PISCO or CHIRPS, a cold bias is found from April to July compared to ERA5 or CRU. The bias in temperature is potentially caused by biases in the driving global climate simulations and by the difference in land elevation between WRF and observational datasets.

The comparison of present and future simulations shows changes in both temperature and precipitation in Madre de Dios. The climate projections indicate an increase in temperature of 1 and 3 °C under the RCP2.6 and RCP8.5 scenarios, respectively. Precipitation is projected to overall decrease in Madre de Dios. During the rainy season from September to April, the average decrease is 5 and 12 % under the RCP2.6 and RCP8.5 scenarios, respectively. During the dry season from May to August, the rain is reduced by more than 50 % in both scenarios. The general reduction in precipitation seems to be related to the changes in the SAMS under climate change, which include a less intense Bolivian High during the peak months of December and January (particularly in RCP8.5), a less intense Chaco Low in February, and a more intense Atlantic Tropical High that extends much further into the continent in both climate scenarios from April to August. These changes reduce the occurrence of LLJ events under both climate scenarios, and consequently, affecting precipitation east of the Andes.

How to cite: González-Rojí, S. J., Messmer, M., Raible, C. C., and Stocker, T. F.: Future changes in the South American Monsoon System and its consequences over south-eastern Peru, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10904, https://doi.org/10.5194/egusphere-egu24-10904, 2024.

EGU24-11517 | ECS | Orals | AS1.18

Distinct response of Asian summer precipitation and monsoon circulation to orbital forcing during Heinrich events 

MingQiang Liang, Qiuzhen Yin, Yong Sun, Chao Zhang, Zhipeng Wu, and Wei Liu

Climatic fingerprint of Heinrich (H) events was characterized by widespread megadroughts over the Asian monsoon region, accompanied by a systemic weakening of Asian summer monsoon. However, recent hydroclimate proxies suggest that South China experienced increased precipitation contrasting with the prevalent megadrought conditions during the Heinrich events. Our simulations performed with the HadCM3 model show that changes in insolation alone can induce spatiotemporal discrepancies in precipitation over the Asian summer monsoon region. During the H1, 3, 4, 5, 6 events, the amplification of the land-sea pressure contrast in response to a positive solar insolation gradient during boreal summer intensifies moisture transport from the ocean to the Asian monsoon region. The ensuing moisture divergence, combined with anomalous downdrafts, results in decreased precipitation in the South Asian Summer Monsoon (SASM) region, but converse situation for the East Asian Summer Monsoon (EASM) region. During the H2 event, the increased precipitation across the Yangtze River Valley sharply contrasts with the widespread drought over the ASM region. This is attributed to an enhancement of a southerly warm-moist vapor transport along the western edge of the subtropical Western North Pacific anticyclone and an enhancement of a northerly cold-dry vapor transport along the western edge of the Aleutian cyclone, which converge over the Yangtze River Valley. Our results further show an in-phase relationship between the SASM and EASM circulation strengths in response to orbital forcing. This is driven by the combined influence of the land-sea thermal contrast and the migration of the Intertropical Convergence Zone, supporting Kutzbach's hypothesis.

How to cite: Liang, M., Yin, Q., Sun, Y., Zhang, C., Wu, Z., and Liu, W.: Distinct response of Asian summer precipitation and monsoon circulation to orbital forcing during Heinrich events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11517, https://doi.org/10.5194/egusphere-egu24-11517, 2024.

EGU24-11919 | ECS | Orals | AS1.18

Impact of Hindu Kush Himalayan snow cover change on Monsoon Circulation 

Manuel Tobias Blau, Pratik Kad, Jenny V. Turton, and Kyung-Ja Ha

Mountain snow cover is an integral part of our climate system that impacts ecosystems and the biosphere that rely on river systems. In recent years, the Hindu Kush-Himalayan regions have experienced a significant decline in snow cover, which is primarily attributed to global warming. However, understanding the nonlinear trends associated with these changes remains a challenge. Here, we explore the relationship between snow cover change and monsoon dynamics within the context of a changing climate, specifically examining the role of land-atmosphere interaction. The study's findings reveal a clear connection between the declining snow cover and monsoon circulation, which is explained through multiple models and grounded in mean state changes. This result highlights the crucial role of snow cover in the dynamics of monsoon.

How to cite: Blau, M. T., Kad, P., Turton, J. V., and Ha, K.-J.: Impact of Hindu Kush Himalayan snow cover change on Monsoon Circulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11919, https://doi.org/10.5194/egusphere-egu24-11919, 2024.

Although the South American monsoon (SAM) is the main source of precipitation over most of the continent, the effects of anthropogenic climate change on it remain unclear. Most recent projections from CMIP6 multimodel ensembles show very weak signal of total SAM precipitation change, and sometimes climate change information from different sources seems confusing and contradictory for the public and decision makers. As SAM affects the most populated areas and those with largest contribution to agricultural production and hydroelectric power generation, its future behavior should be clearly detailed and supported by a dynamical framework able to explain it, so as to better serve decision-makers in planning actions to respond to climate change and adopt effective policies for climate adaptation.

The existence of a dynamic framework that explains the major climate changes projected by the best-performing models gives coherence to the different monthly changes throughout the monsoon season, which otherwise seem incomprehensible and can lead to discrepant interpretations if not understood within a correct dynamic context. The lack of significant future change in total monsoon precipitation does not mean that there are no changes of great interest in different phases of the monsoon season.

There are two aspects that prompted the approach of the present study: i) model projections of future SST indicate an El Niño-like warming pattern in the central-east equatorial Pacific; ii) the impacts of the present climate El Niño events on South America (SA) display a tendency to spring-summer reversal of precipitation anomalies in central-east SA (CESA), which results in little or no change in the total monsoon precipitation in this region.

Twelve CMIP6 selected models were evaluated not only for their simulation of South American climatology, but also for their simulation of ENSO and its impacts on SA. Several of them did not produce satisfactory ENSO. The changes projected by the ensemble of seven models that best reproduced ENSO and the climatology of SA indicate a more EN-like future climate. Consistently, the main climate changes projected for the SAM resemble the observed EN impacts, remarkably including the tendency to spring-summer reversal of precipitation anomalies in CESA, from dryer spring to wetter summer. While the total monsoon precipitation shows little or no change in this region, there is reduction of early monsoon rainfall and increase of the peak season rainfall, which results in a delay and shortening of the monsoon season. The dynamical effect of the EN-like SST changes shapes the spring response via teleconnection, and thermodynamical processes trigger the changes from spring to summer in CESA, which is part of the core monsoon region. Also coherently with EN impacts, drier conditions prevail in central-northern-eastern Amazon throughout the monsoon season thanks to changes in the Walker circulation, while in southeast SA, precipitation increases due to tropics-extratropics teleconnection.

The changes projected by the all-model ensemble are much weaker and confusing. This clear description of climate change throughout the monsoon season and its connection with intensified EN effects is easy to understand and use, as these effects are reasonably known.

How to cite: Grimm, A. M. and Padoan, D.: Towards robust and actionable information on monsoon climate change in South America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13343, https://doi.org/10.5194/egusphere-egu24-13343, 2024.

A weak Indian summer monsoon (ISM) strengthens an El Niño via generating a cyclonic circulation over the northwestern Pacific. The westerly anomaly on the southern flank of this cyclone generates eastward anomaly in the mixed layer, induces warm zonal advection, and excites oceanic downwelling Kelvin waves, deepening the thermocline in equatorial eastern Pacific and resulting in cold vertical advection. The influence of monsoon-induced Pacific wind anomaly on ENSO is mainly achieved by changing the zonal advective feedback and thermocline feedback. CMIP6 models show a large diversity for the impact of ISM on ENSO, related to the diverse amplitudes of ISM among the models. Models simulating a stronger ISM display more robust features of ISM-induced anomalous circulation over the northwestern Pacific, and the larger equatorial wind anomalies on the south flank of the anomalous circulation affect ENSO evolution more significantly by causing stronger ocean-atmosphere coupling processes.

       The future changes in the ISM’s impacts on ENSO also exhibit a large spread among the CMIP6 models. The uncertainty in the projections is linked to the diverse changes in the response of anomalous circulation over the northwestern Pacific to ISM. The models showing an increased (decreased) sensitivity of anomalous circulation over the northwestern Pacific to ISM simulate enhanced (weakened) ISM’s impacts on ENSO under global warming, even though the amplitudes of ISM remain unchanged

How to cite: Yang, S., Lin, S., and Dong, B.: Dynamical Processes of the Impact of Indian Summer Monsoon on ENSO: Observation, Model Simulation and Future Change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13998, https://doi.org/10.5194/egusphere-egu24-13998, 2024.

The interannual variability (IAV) of All India summer rainfall (AIMR) is low, with a Coefficient of variation (COV) around 9% of the long-term mean. Though regulated by global and regional sea surface temperatures, we explore the cause of low COV of AIMR due to the spatial distribution of rainfall. We find that the variability of AIMR is affected by the spatial covariance between the subregions with different rainfall characteristics, such as the arid western and wet northeast regions. By removing regions, one at a time, from the Indian region, we find that COV increases after removing the Northeast (NE) region due to negative covariance between NE and other sub-regions of India, especially Central India (CI). Further research is ongoing to explore the moisture distribution over the subregions and understand the negative covariance using a moisture tracking algorithm. We plan to investigate the contributions to rainfall distribution from oceanic and terrestrial sources. This study may reveal how the spatial distribution of rainfall influences the IAV of AIMR, emphasizing the significance of terrestrial and oceanic moisture contributions.

How to cite: Chandel, V. and Ghosh, S.: Role of spatial covariance in regulating interannual variability of Indian Summer Monsoon rainfall, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14603, https://doi.org/10.5194/egusphere-egu24-14603, 2024.

The pattern of Monsoon rainfall across the Ganga-Brahmaputra-Meghna (GBM) basin is crucial for supporting various farming and ecological systems and play a significant role in affecting the basin’s food-water security, well-being, and prosperity. However, the understanding of Monsoon activity is limited due to the poor representation of large-scale processes in the climate models and their coarser resolution. This study utilises sub-daily precipitation from finer resolution CMIP6 HighResMIP models to study the changes in properties of monsoon rainfall based on the timing (onset/offset/duration) of the Monsoon and the trend in rainfall (total and extreme rainfall). All models show a delay in the monsoon but there is disagreement in trends in retreat and duration of the monsoon. Also, CMCC models project a decline in magnitude of rainfall whereas NERC models project an increasing trend. The models output is also evaluated against the reference datasets like MSWEP and ERA5 reanalyses. Our study highlights the uncertainty in climate models to capture the monsoon rainfall and disagreements in results across different horizontal resolutions and nature of models. Importantly, the delay in future Monsoon supported by all models have a strong implication on agriculture and economy of the delta.

How to cite: Ali, H. and Fowler, H.: Understanding the future Monsoon activity across the Ganga-Brahmaputra-Meghna basin using CMIP6 HighResMIP models  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15435, https://doi.org/10.5194/egusphere-egu24-15435, 2024.

EGU24-15851 | ECS | Posters on site | AS1.18 | Highlight

Monsoon Planet: Studying Monsoon Dynamics in an Idealized Setup 

Anja Katzenberger, Stefan Petri, Georg Feulner, and Anders Levermann

Monsoon systems transport water and energy across the globe, making them a central component of the global circulation system. Each monsoon system has its own regional characteristics ranging from particular continental shapes to dynamic vegetation patterns and the influence of mountain ranges. This individuality makes it difficult to access the common core meridional monsoon dynamics by only using observations or realistic simulations. Idealized frameworks have proven to be useful approaches to study monsoon systems with regard to their commonalties. Here, we present the latest insight of our work on the Monsoon Planet – an aquaplanet setup with an idealized circumglobal land stripe.

How to cite: Katzenberger, A., Petri, S., Feulner, G., and Levermann, A.: Monsoon Planet: Studying Monsoon Dynamics in an Idealized Setup, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15851, https://doi.org/10.5194/egusphere-egu24-15851, 2024.

EGU24-16112 | ECS | Posters on site | AS1.18

The impacts of northern hemisphere high-latitude climate on northeastern Australian summer monsoon evolution during the Holocene 

Ge Shi, Hong Yan, Wenchao Zhang, John Dodson, Henk Heijnis, and Mark Burrows

Influenced by the northern hemisphere high-latitudes, many of the millennial-centennial scale climate changes originating in the North Atlantic have been detected even in southern hemisphere. However, the linkage between hemispheres on orbital-suborbital time scales has not been firmly examined due to the absence of records from the Southern Hemisphere. Here we present such a record from Bromfield Swamp in tropical northeastern Australia. The Australian Summer Monsoon index (AuSMI) of the last 13.5 ka was reconstructed basd on the principal component analysis (PCA) of five proxies, the Rb/Sr, Ti/Ca, Al/Ca, mean grain size and organic content. The results reflected a weak AuSM influence during the Bolling-Allerod event and with a somewhat stronger influence during the YD event. During the Holocene, there was a decreasing AuSM before ~7.8 cal kyr BP, and then it enhanced from middle to late Holocene. The AuSM change was out of phase/ in phase with the East Asian summer monsoon/ East Asian winter monsoon during the Holocene, and all of them changed parallel with the northern-southern hemisphere temperature gradient. This implied the dominance of interhemispheric thermal contrast to the highly coupled East Asian-Australian monsoon changes, by modulating the Intertropical Convergence Zone migration, which was influenced by the retreat of northern hemisphere ice sheet from early to middle Holocene and the local summer insolation changes during the late Holocene. The study highlights the likelihood that high latitude northern hemisphere played a major role in the evolution of the northeastern Australian summer monsoon.

How to cite: Shi, G., Yan, H., Zhang, W., Dodson, J., Heijnis, H., and Burrows, M.: The impacts of northern hemisphere high-latitude climate on northeastern Australian summer monsoon evolution during the Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16112, https://doi.org/10.5194/egusphere-egu24-16112, 2024.

Tropical and subtropical precipitation impact millions of people via agriculture and rainfall driven disasters. However, a wide spread remains in future regional projections of low-latitude precipitation, dominated by uncertain shifts in rainfall, and models continue to show a variety of biases in the location and intensity of rain.

The Energy Flux Equator framework has emerged as a powerful tool in interpreting the location of low-latitude rainfall via atmospheric heat transport (AHT), which in turn can be understood through the top of atmosphere and surface energy fluxes. Recent work using a novel decomposition of the zonal-mean AHT suggests that its spatial structure is dominated by the meridional structure of the latent heat flux. Here, we apply this decomposition to investigate intermodel differences in AHT on the seasonal timescale.

We find that throughout the year, intermodel differences in total AHT and the latitude of maximum zonal mean precipitation both correlate strongly with the heat transport contribution attributed to evaporation. Curiously, spatial regressions appear to suggest that evaporation over land provides a key contribution to this spread, despite the net surface heat flux over land being close to balanced. To interrogate the causality underlying this correlation with land evaporation, we make use of the 1pctCO2-bgc simulations, in which only the carbon cycle responds to increasing carbon dioxide, with one consequence being altered evapotranspiration.

How to cite: Geen, R., Laguë, M., and Fajber, R.: Exploring the role of evaporation in atmospheric heat transport and seasonal low-latitude precipitation biases in CMIP6, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16770, https://doi.org/10.5194/egusphere-egu24-16770, 2024.

In a retrograde Earth simulation using the fully coupled MPI-ESM, we find that the climate in the Sahara goes from arid to monsoonal. By understanding this transition of the Sahara, we can gain insights into some of the key processes necessary for the existence of monsoons. We find that theories of monsoons based on land-sea thermal contrast and meridional shifts in the interhemispheric convergence zone (ITCZ) are not adequate to explain this change in the climate of the Sahara. Hence, we use the energetics of monsoons, which is based on local moist static energy and moisture budgets. In the regular forward-rotating Earth, the net energy input into the atmospheric column (NEI) is negative over the Sahara, implying a net energy import over the region. The reversed winds in the retrograde simulation advect moisture from the Arabian Sea and the equatorial Atlantic into the Sahara during the boreal summer. The greenhouse effect of water vapor instantaneously reduces the outgoing longwave radiation, thereby increasing the NEI. As NEI becomes positive, the Sahara exports energy, increasing convection (and, hence, monsoon precipitation). The increased cloud cover further enhances NEI through cloud radiative feedback, strengthening the monsoon. Therefore, we conclude that the radiative effects of water vapor and clouds are an essential ingredient for monsoons.

How to cite: Jalihal, C. and Mikolajewicz, U.: The role of water vapor and cloud radiative effects in monsoons: Perspectives from retrograde Earth simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16987, https://doi.org/10.5194/egusphere-egu24-16987, 2024.

EGU24-17834 | ECS | Orals | AS1.18

Onset Periods: a novel approach to understand the onset of the monsoon season 

Marcia Zilli, Neil Hart, and Francesca Morris

In recent decades, several studies have proposed different methodologies to reliably identify the onset of the rainy season in monsoon climates, considering either a single variable, usually precipitation, or a combination of rainfall with other dynamic and thermodynamic variables (e.g. wind, specific humidity). These methodologies tend to define a single onset date, which can fail to diagnose critical characteristics of early season rainfall such as wet/dry spell phasing and intensity. Here, we propose a novel approach to identify the transition from dry to wet seasons as a period (6-8 weeks on average) with a positive gradient of the FFT-filtered precipitation, indicative of a steady increase in rainfall. This approach allows the characterisation of critical onset period rainfall characteristics, including information about wet and dry spell frequency and total precipitation, which is a valuable advance on typical single-date onset methods. Preliminary results considering observational and reanalysis datasets indicate a good agreement between the onset day identified using a traditional methodology and the onset periods over South America and Africa. A more in-depth analysis of the identified onset periods can provide further insights into the role of intraseasonal and interannual variability on the precipitation regimes. We also identified regions with distinct changes in the onset periods timing and related precipitation characteristics when considering present and future climate simulations, including simulations using convective-permitting models. For example, the method is able to distinguish that parts of eastern Brazil are projected to have a later onset period with more intense wet days, whereas in eastern Amazon the key signal is more dry days during the onset period, leading to a weaker intensity of onset. In addition to identifying the rainy season onset periods, this approach also identifies other onset periods, further classified as false onset (interval with positive filtered precipitation gradient followed by the onset period), second onset (interval with a secondary increase in the filtered precipitation gradient after the onset period), or wet spells (occurring during the dry season). These periods provide valuable information about spells of increased precipitation outside the rainy season onset, such as wet spells during the dry seasons or false onsets before the primary rainy season. When recurrent, they can indicate the influence of interannual or intraseasonal variability in off-season precipitation. As the core statistics that emerge from this approach are related to the intensity and phasing of rainfall rather than absolute amounts, future developments will focus on implementing the method in a seasonal forecast system, where only a few months of data are available, with the potential to obtain forecast skill which circumvents absolute rainfall biases.

How to cite: Zilli, M., Hart, N., and Morris, F.: Onset Periods: a novel approach to understand the onset of the monsoon season, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17834, https://doi.org/10.5194/egusphere-egu24-17834, 2024.

EGU24-18707 | ECS | Orals | AS1.18

Role of Dynamical and Thermodynamical processes in shaping Diurnal Cycle of Rainfall over the Western Ghat of India 

Utkarsh Verma, Samir Pokhrel, and Subodh Kumar Saha

Diurnal Variability is one of the most fundamental modes of the global climate system arising from solar radiation variations. The precipitation over the Indian subcontinent region has significant diurnal variation as per the topographical settings of the landmass. Among the various regions with the maximum diurnal amplitude (MDA) of precipitation over India, MDA over Western Ghat (WG) is perfectly aligned along the coastal boundary.

The peculiarity of the WG region is the position of the coastally aligned mountain range stretching from Gujarat to Kerala with an average elevation of 1200m and during monsoon season with the presence of speedy low-level jet (LLJ), this range acts as a barrier to anchor precipitation over them. The MDA over this region tends to be positioned slightly inland, on the windward side of the hills and is closely associated with the geographic locations of mountain peaks over WG. Here we have attempted to understand the phase and amplitude of diurnal precipitation variation on two distinct physical regimes predominantly governed either by dynamics (DR) or thermodynamics (TR). Based on the speed of the (LLJ) we have identified 370 and 458 days from the monsoon season of 21 years, with dominant physical processes being dynamical and thermodynamical respectively. We found a substantial enhancement of MDA over the entire span of the WG region encompassing the region over the sea, coast, and land during TR which is in stark contrast to DR where MDA is concentrated mostly over the coastal side northern and central western Ghat region. This difference is also visible in the diurnal phase with gradual (abrupt) changes in TR (DR). During TR the weakened LLJ leads to the local thermodynamics to dominate, and very strong land and sea breezes are initiated, along with an unstable hot and humid boundary layer making favorable conditions for diurnal precipitation to take place. This is entirely different in DR wherein the stronger LLJ does not allow to establish a stronger temperature gradient between land and ocean leading to a lessening of diurnal rain. The storm-top height indicates the presence of low-level congestus (deep congestus) clouds during DR (TR). Thus, the diurnal rain, along with cloud types and involved microphysics is totally different in these two physical regimes. This study will be very useful for identifying the errors in the diurnal rain simulated by models segregated by dynamical or thermodynamical processes separately.

How to cite: Verma, U., Pokhrel, S., and Saha, S. K.: Role of Dynamical and Thermodynamical processes in shaping Diurnal Cycle of Rainfall over the Western Ghat of India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18707, https://doi.org/10.5194/egusphere-egu24-18707, 2024.

EGU24-19848 | Posters on site | AS1.18

Mid-Latitude Controls on Monsoon Onset and Progression (the MiLCMOP project) 

Andrew Turner, Ambrogio Volonte, Akshay Deoras, and Arathy Menon

The monsoon onset typically starts in southern India by 1 June, taking around 6 weeks to cover the country.  During the monsoon, intraseasonal variations give rise to active and break periods in the rains.  Being able to better predict the monsoon onset, its progression, and active and break events would be of great interest to society.  The onset timing is already known to be influenced by tropical intraseasonal variability, but new research has shown that the mid-latitudes exert a powerful control, the full extent of which is not properly quantified or understood. 

The MiLCMOP project aims to answer the following: (1) How are the pace and steadiness of monsoon progression affected by interactions with the extratropics? (2) What are the mechanisms of extratropical control on monsoon progression and variability? (3) How do the causal extratropical and tropical drivers of monsoon progression offset or reinforce each other? 

Our initial work has tested a new hypothesis that monsoon progression can be described as a “tug-of-war” between tropical and extratropical airmasses.  This “tug-of-war” is unsteady, with a back and forth of the two airmasses before the moist tropical flow takes over for the season.  We demonstrate this for a case study of the 2016 season for India, while also drawing analogies with other monsoon regions, such as for the East Asian monsoon, in which we show the competition between extratropical and tropical flows in establishing the Mei Yu front as it progresses across China.

Current activities revolve around the identification of statistical relationships between monsoon onset and progression and perturbations to the subtropical westerly jet, including blocking anticyclones, meridionally propagating troughs and cyclonic features near the Tibetan Plateau.  Additional focus is also devoted to the relationship between the monsoon advancement and the strength, extent and orientation of the intrusion of mid-tropospheric dry air flowing towards India from westerly and northwesterly quadrants.

Other methods will include use of vorticity budgets and Lagrangian feature tracking in case studies of fast and slow onsets, to suggest the dominant mechanisms by which extratropical drivers affect monsoon onset and progression.  Model experiments will help isolate these mechanisms.  Finally, novel causal inference techniques will help disentangle the effects of extratropical drivers from those in the tropics. 

How to cite: Turner, A., Volonte, A., Deoras, A., and Menon, A.: Mid-Latitude Controls on Monsoon Onset and Progression (the MiLCMOP project), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19848, https://doi.org/10.5194/egusphere-egu24-19848, 2024.

The Himalayas is the main water source for two major river systems in South Asia, the Ganges and the Brahmaputra. Rivers from this region are predominately fed by precipitation associated with the Indian Summer Monsoon (ISM) which is variable and influenced by large-scale atmospheric circulation patterns and anomalies, where El Niño-Southern Oscillation (ENSO) plays a dominant role. Here, we use a causal discovery method to assess the relationships and causal links associated with the influence of ENSO on ISM precipitation over the Himalayas, and how this is regulated by the Walker and Hadley circulation cells. In particular, we aim to clarify the direction and strength of causal linkages involving four time series/ indices representing ENSO, the Walker circulation, the monsoon Hadley circulation, and  summer monsoon Himalayan precipitation.   Apart from ENSO data, which is available for a longer period, the rest other data are from ERA5 that cover longer records, starting from 1940 to 2022. We demonstrate that the influence of ENSO on Himalayan precipitation mediated by the circulation dynamics can be quantified on monthly timescales (i.e., at few months lag). Starting from the two-way interaction between two parameters, we increased the complexity of the causal effect network analysis in steps and finally ended with all four indices. Our results show that it is possible to identify causal links with corresponding time delays and the links are moderately robust in most cases. Our findings also indicate that the influence of ENSO on the regional summer monsoon Hadley cell can arise via the pathways of regional Walker cell in the Himalayan sector. Improving our understanding of Himalayan precipitation and relevant regulatory mechanisms play an important role in India’s socioeconomic structure though it is still a neglected area compared to the vast amount of research those focused on all India rainfall. Our analyses using the sophisticated approach of causal network analyses will advance our knowledge on ISM and complement the gap.

How to cite: Muszynski, G., Orr, A., and Roy, I.: Using a causal discovery approach to analyse linkages among ENSO, circulation fields, and summer monsoon precipitation over the Himalayas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20701, https://doi.org/10.5194/egusphere-egu24-20701, 2024.

EGU24-832 | ECS | Posters on site | AS3.12

Aerosol-cloud interactions constrain climatic trends in rainfall and temperature of India 

chandan sarangi, Pradeep Rai, Sunny Kant, Arun Nair, Soumendra Kuiry, Eric Wilcox, and Ruby Leung

Aerosol-cloud interactions (ACI) is a key uncertainty in our ability to forecast future climate. Robust evidences of aerosol-induced modifications to the structure and lifetime of both, rain bearing and non-rain bearing clouds has emerged from satellite observations across the globe in last two decades. These observations were also substantiated by many process-level simulation studies using weather models at cloud resolving scales in last decade. Thus, the significance of ACI at process scale on short-term meteorological perturbations is well agreed. However, the role of aerosol-cloud interactions on trends at climate scale is not evident yet. For example, if cloud occurrence is increasing over India, it is not clear if there is any substantial role of ACI in comparison to other governing factors. Here, we will present our analysis on the association of ACI with the recent trends in clouds, temperature and rainfall over India using satellite observations and global climate model simulations.

First, we will discuss data analysis of simulations from CMIP5 models, to quantify the importance of ACI on extreme climate indices over Indian monsoon region. The climate models were grouped based on whether the models represent only aerosol-radiation interactions (REMADE) or the full suite of aerosol-radiation-cloud interactions (REMALL). Compared to REMADE, including all aerosol effects significantly improves the model skills in simulating the observed historical trends of all three climate indices over India. Specifically, AIE enhances dry days and reduces wet days in India in the historical period, consistent with the observed changes. However, by the middle and end of the 21st century, there is a relative decrease in dry days and an increase in wet days and precipitation intensity. Further, we will also illustrate unprecedented satellite evidences of aerosol induced positive trends in marine cloud occurrences and surface temperature during pre-monsoon over the Bay of Bengal (BOB) region. In last 15 years, increased aerosol emissions over North India have led to an increase in aerosol loading till 3 km over the BOB outflow region in monsoon onset period. The elevated aerosol loading stabilizes the lower troposphere over the region in recent years and leads the low-level cloud occurrences (below 3 km) to increase in recent years by ~20%. Incidentally, the sea surface over entire BOB is steadily warming under climate change except the pollution outflow region, suggesting potential contributing to the observed non-intuitive cooling trends in sea surface temperatures.

Our findings underscore the crucial role of ACI in trends and future projections of the Indian hydroclimate and emphasizes the crucial need for improved aerosol representations in coupled models for accurate predictions of regional climate change over South Asia.

How to cite: sarangi, C., Rai, P., Kant, S., Nair, A., Kuiry, S., Wilcox, E., and Leung, R.: Aerosol-cloud interactions constrain climatic trends in rainfall and temperature of India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-832, https://doi.org/10.5194/egusphere-egu24-832, 2024.

Understanding the link between emissions, atmospheric chemistry and the Earth’s radiative budget remains a challenge in climate research. Such linkage arises from the fact some aerosols are produced chemically in the atmosphere. Unlike well-mixed greenhouse gases, anthropogenic aerosols are heterogeneously distributed because of localised emissions and the short atmospheric residence time. Over the historical period emissions of greenhouse gases, and near-term climate forcers (NTCFs) including aerosol precursors, O3 precursors and CH4 have broadly increased. We ask how changes in anthropogenic emissions over the historical period feed through aerosol and cloud radiative forcing.  This is important because a lack of understanding of regionally heterogeneous aerosol-climate effects is hampering our understanding of historical climate change. It also limits our confidence in future climate projections and the assessment of their impacts, as aerosol emissions are expected to decline in many regions over the coming decades.

Using the UK Earth System Model 1 (UKESM1), we investigate how sulfate aerosols form under emission and oxidant changes between 1850 and 2014. We analyse simulation output from the Aerosol Chemistry Model Intercomparison Project (AerChemMIP) atmosphere-only transient experiment which was designed to evaluate NTCF transient effective radiative forcing. These simulations target each NTCF thus suitable for isolating the effects of NTCF on the Earth system responses such as aerosol and cloud formation. First, we investigate the effect of emission location on oxidation, aiming to characterise regional sulfate aerosol formation. Two regions, Europe and Eastern Asia region, were chosen to allow comparison between two regions with different emission profiles in different periods. In the UKESM1, SO2 reacts with OH in the gas phase and O3 and H2O2 in the aqueous phase. We show that emissions location and timing determine oxidation tendency via the available oxidant and meteorological properties such as clouds. Both regions see up to 80% of total sulfate production via gas phase oxidation in summer when high OH and low cloud cover are observed. The opposite is true for wintertime when aqueous phase reactions with O3 and H2O2 form up to 90% of aerosol. Each region also shows distinct characteristics, for example, H2O2 oxidation in the European region is generally lower than that of the Eastern Asia region but it is more variable with bimodal features showing peaks in spring and autumn. Second, we investigate the effects of O3 precursors and CH4 on SO2 oxidation to quantify the regional contribution of NTCFs. Influence from O3 precursors is localised while CH4 affect SO2-OH oxidation on a more global scale. This work shows that the same amount of SO2 emitted at different regions does not form aerosol at the same amount or with the same aerosol size distribution.

We present an analysis of monthly changes of oxidants and emissions to sulfur oxidation, aerosol and cloud properties. Ultimately, this work contributes to the improvement of our process-level understanding of Earth system models that interactively simulate aerosol from precursors and aims to improve the accuracy of aerosol radiative forcing predictions.

How to cite: Sakulsupich, V., Griffiths, P., and Archibald, A.: Historical sulfate aerosol formation in earth system model with interactive-chemistry: interplay between emission location, seasonality, meteorology and available oxidants, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1018, https://doi.org/10.5194/egusphere-egu24-1018, 2024.

High Mountain Asia (HMA) has experienced a spatial imbalance in water resources in recent decades, partly because of a dipolar pattern of precipitation changes known as South Drying–North Wetting. These changes can be influenced by both human activities and internal climate variability. Although climate projections indicate a future widespread wetting trend over HMA, the timing and mechanism of the transition from a dipolar to a monopolar pattern remain unknown. Here we demonstrate that the observed dipolar precipitation change in HMA during summer is primarily driven by westerly- and monsoon-associated precipitation patterns. The weakening of the Asian westerly jet, caused by the uneven emission of anthropogenic aerosols, favoured a dipolar precipitation trend from 1951 to 2020. Moreover, the phase transition of the Interdecadal Pacific Oscillation induces an out-of-phase precipitation change between the core region of the South Asian monsoon and southeastern HMA. Under medium- or high-emission scenarios, corresponding to a global warming of 0.6–1.1 °C compared with the present, the dipolar pattern is projected to shift to a monopolar wetting trend in the 2040s. This shift in precipitation patterns is mainly attributed to the intensified jet stream resulting from reduced emissions of anthropogenic aerosols. These findings underscore the importance of considering the impact of aerosol emission reduction in future social planning by policymakers.

How to cite: Jiang, J.: Precipitation regime changes in High Mountain Asia driven by cleaner air, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1924, https://doi.org/10.5194/egusphere-egu24-1924, 2024.

EGU24-3279 | Posters on site | AS3.12

Observational Constrained Attribution of Regional Aerosol Simulation Biases in the AerChemMIP models 

Tianyi Fan, Xiaohong Liu, Chenglai Wu, and Yi Gao

     Regional aerosol simulation biases in climate models have been noted since the CMIP5 era. The biases can cause noticeable error in the radiative forcing estimations. In this research, we investigate the aerosol optical depth (AOD) biases over China from 2002 to 2015 in nine climate models that participate the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP) of CMIP6. The AerChemMIP ensemble mean is high biased over four populated regions in winter and low biased in two populated regions compared to the MODIS satellite retrievals. The patterns of model biases were persistent over years. Large inter-model spread is found in the high AOD regions. We decompose AOD to the product of emission rate, lifetime and mass extinction coefficient such that the AOD biases can be attributed to the errors of each term and their cross error term. The error of each term is analyzed by first regressing to several observable predictors, such as precipitation, Angström exponent, and relative humidity, followed by constraining the predictors by observational or reanalysis data. The results show that error due to emission dominates for many models, followed by lifetime and MEC errors. Furthermore, we argue that for regional analysis, due to imbalance between emission and removal fluxes, the removal/emission ratio should be further constrained by observations. This study provides a diagnosis for climate models to improve their simulation in aerosol loading on regional scale by optimizing the modeling of meteorology as well as aerosol properties and life cycle. 

How to cite: Fan, T., Liu, X., Wu, C., and Gao, Y.: Observational Constrained Attribution of Regional Aerosol Simulation Biases in the AerChemMIP models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3279, https://doi.org/10.5194/egusphere-egu24-3279, 2024.

EGU24-3748 | ECS | Posters on site | AS3.12

Evaluation of CMIP6 model simulations of PM2.5 and its components over China 

Fangxuan Ren, Jintai Lin, Jamiu A. Adeniran, Jingxu Wang, Randall V. Martin, Aaron van Donkelaar, Melanie S. Hammer, Larry W. Horowitz, Steven T. Turnock, Naga Oshima, Jie Zhang, Susanne Bauer, Kostas Tsigaridis, Øyvind Seland, Pierre Nabat, David Neubauer, Gary Strand, Twan van Noije, Philippe Le Sager, and Toshihiko Takemura and the ACM Group

Earth system models (ESMs) participating in the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) simulate various components of fine particulate matter (PM2.5) as major climate forcers. Yet the model performance for PM2.5 components remains little evaluated due in part to lack of observational data. Here, we evaluate near-surface concentrations of PM2.5 and its five main components over China as simulated by fourteen CMIP6 models, including organic carbon (OC, available in 14 models), black carbon (BC, 14 models), sulfate (14 models), nitrate (4 models), and ammonium (5 models). For this purpose, we collect observational data between 2000 and 2014 from a satellite-based dataset for total PM2.5 and from 2469 measurement records in the literature for PM2.5 components. Seven models output total PM2.5 concentrations, and they all underestimate the observed total PM2.5 over eastern China, with GFDL-ESM4 (–1.5%) and MPI-ESM-1-2-HAM (–1.1%) exhibiting the smallest biases averaged over the whole country. The other seven models, for which we recalculate total PM2.5 from the available components output, underestimate the total PM2.5 concentrations, partly because of the missing model representations of nitrate and ammonium. Concentrations of the five individual components are underestimated in almost all models, except that sulfate is overestimated in MPI-ESM-1-2-HAM by 12.6% and in MRI-ESM2-0 by 24.5%. The underestimation is the largest for OC (by –71.2% to –37.8% across the 14 models) and the smallest for BC (–47.9% to –12.1%). The multi-model mean (MMM) reproduces fairly well the observed spatial pattern for OC (R = 0.51), sulfate (R = 0.57), nitrate (R = 0.70) and ammonium (R = 0.75), yet the agreement is poorer for BC (R = 0.39). The varying performances of ESMs on total PM2.5 and its components have important implications for the modeled magnitude and spatial pattern of aerosol radiative forcing.

How to cite: Ren, F., Lin, J., Adeniran, J. A., Wang, J., Martin, R. V., van Donkelaar, A., Hammer, M. S., Horowitz, L. W., Turnock, S. T., Oshima, N., Zhang, J., Bauer, S., Tsigaridis, K., Seland, Ø., Nabat, P., Neubauer, D., Strand, G., van Noije, T., Le Sager, P., and Takemura, T. and the ACM Group: Evaluation of CMIP6 model simulations of PM2.5 and its components over China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3748, https://doi.org/10.5194/egusphere-egu24-3748, 2024.

Past decades witnessed strong spatial changes in the emissions of anthropogenic aerosols and their precursors resulting in a global redistribution of maxima in the anthropogenic aerosol optical depth. This study investigates the response of the circulation to the different anthropogenic aerosol patterns around the 1970s and 2000s with focus on the meridional heat transport. Our analysis uses 309 historical model experiments of the Coupled Model Intercomparison Project Phase 6 and 94 single-forcing experiments for anthropogenic aerosols from the Detection and Attribution Model Intercomparison Project (DAMIP). We substantially reduce the influence of internal variability by computing multi-model multi-realization means and additional averaging over time periods of 15 years. The results highlight the influence of anthropogenic aerosol radiative effects on the total northward heat transport. Around the 1970s, most anthropogenic aerosols were located over Europe, North America and the North Atlantic. At that time, the anthropogenic aerosol increase explains almost half of the total change in the summertime northward heat transport in the tropics compared to pre-industrial times. In polar regions, the anthropogenic aerosols around the 1970s counteracted the induced response of the northward heat transport to greenhouse gas forcing. It suggests that changes induced by the aerosol pattern until the 1970s delayed the increase in Arctic warming in CMIP6, later known as Arctic amplification. The later change in the anthropogenic aerosol pattern between the 1970s and the 2000s led to different hemispheric asymmetries in the anthropogenic aerosol optical depth and hence the reflected shortwave radiation. Due to the associated different regional radiative effect, the change in the summertime northward heat transport in the polar region is now qualitatively similar for anthropogenic aerosols and greenhouse gas forcings for the 2000s against the 1970s. Specifically, the heat transport to the Arctic during summer increases for the 2000s compared to the 1970s consistent with emergence of Arctic amplification in the late 1970s.   

How to cite: Varma, V. and Fiedler, S.: Response of the northward heat transport depends on regional anthropogenic aerosol effects in CMIP6, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5070, https://doi.org/10.5194/egusphere-egu24-5070, 2024.

Reanalysis data show the summertime circulation in the Northern Hemisphere midlatitudes has weakened significantly in the satellite era. Recent work shows the circulation weakening is not significantly affected by Arctic Amplification and Arctic Sea ice loss, but did not examine the role of other anthropogenic forcings such as aerosols. Here we use Detection and Attribution Model Intercomparison Project (DAMIP) simulations, which capture the weakening trend in reanalysis data, to quantify the impact of anthropogenic forcing due to aerosols and greenhouse gases. The DAMIP simulations show aerosol forcing dominates the weakening of the circulation across the Eurasia-Pacific sector, including the Pacific jet and storm track. Aerosol and greenhouse gases contribute equally to weakening the Atlantic jet and storm track. We use an energetic framework to understand the impact of aerosols on the storm track. In particular we show aerosol forcing leads to an increasing surface shortwave radiation trend over Western Europe and a decreasing surface shortwave trend over South and East Asia. These shortwave trends induce a weakening trend of the equator-to-pole energy gradient that leads to a weaker downstream storm track. Overall, our results show aerosol forcing is a dominant factor in regional circulation trends during Northern Hemisphere summertime in the satellite era. They have important implications for interpreting summertime heatwave trends in the Northern Hemisphere midlatitudes during summertime.

How to cite: Shaw, T., Kang, J., and Sun, L.: Anthropogenic aerosol forcing has significantly weakened regional summertime storminess in the Northern Hemisphere in the satellite era, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5265, https://doi.org/10.5194/egusphere-egu24-5265, 2024.

EGU24-7692 | ECS | Posters on site | AS3.12

Aligning experimental and model perspectives on atmospheric nanoparticle growth 

Dominik Stolzenburg, Runlong Cai, Sara Blichner, Jenni Kontkanen, Putian Zhou, Risto Makkonen, Veli-Matti Kerminen, Markku Kulmala, Ilona Riipinen, and Juha Kangasluoma

The process of new particle formation from gas-phase precursors holds significant importance in Earth's atmosphere and introduces a notable source of uncertainty in climate change predictions. The growth of freshly formed molecular clusters should in theory be crucial for the climate impact of new particle formation, influencing the survival probability of these particles exponentially and determining their ability to act as cloud condensation nuclei. However, defining the fundamental aspects of nanoparticle growth is intricate. It involves a complex interplay of condensational and reactive vapor uptake, aerosol coagulation, sink processes, and a diverse array of potential gaseous precursors. Observational nanoparticle growth rates, derived from the evolution of the particle-size distribution, portray growth as a collective phenomenon. However, models often interpret these rates at a single-particle level, integrating them into simplified size-distribution representations (Stolzenburg et al., 2023). dditionally, many models only consider a limited subset of condensable vapors, while recent experimental observations identify an increasing number of potential contributors to new particle growth.

Our objective here is to bridge the gap between experimental and modeling studies on nanoparticle growth. We compare three large-scale models (NorESM, ECHAM, and TM5) regarding their sensitivity to organic nanoparticle growth processes. Surprisingly, we find a much lower sensitivity than anticipated from box models. Through the inclusion of a sectional scheme into NorESM, we demonstrate that representing the complexity of size distribution dynamics leads to significantly different cloud condensation nuclei (CCN) levels. Furthermore, our results suggest that, on regional scales, sensitivity to organic growth is much higher. Inclusion of additional growth processes and/or a scaling of condensable vapor concentrations could yield a significantly altered climate response. In turn, comprehensive experimental observations from e.g. the open oceans are still lacking and we show that continental data exhibit surprisingly little variation in measured particle growth rates. The latter indicates limited sensitivity in current experimental approaches and potential unaccounted multi-phase chemistry in the growth process.

Consequently, we propose specific guidance for future research to address questions regarding the buffered climate response in large-scale models and the unexpectedly low variation observed in global growth measurements. We advocate for more sensitivity studies and improved model-measurement comparisons.

References:

Stolzenburg, D., Cai, R., Blichner, S. M., Kontkanen, J., Zhou, P., Makkonen, R., Kerminen, V.-M., Kulmala, M., and Kangasluoma, J.: Atmospheric nanoparticle growth, Rev. Mod. Phys., 95, 045002, https://doi.org/10.1103/RevModPhys.95.045002, 2023.

 

How to cite: Stolzenburg, D., Cai, R., Blichner, S., Kontkanen, J., Zhou, P., Makkonen, R., Kerminen, V.-M., Kulmala, M., Riipinen, I., and Kangasluoma, J.: Aligning experimental and model perspectives on atmospheric nanoparticle growth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7692, https://doi.org/10.5194/egusphere-egu24-7692, 2024.

EGU24-7782 | ECS | Orals | AS3.12

The Local and Remote Impacts of Asian Aerosol Forcings on the East Asian Winter Monsoon and ENSO 

Zixuan Jia, Massimo Bollasina, and Wenjun Zhang

The East Asian winter monsoon (EAWM) is a prominent feature of the northern hemisphere atmospheric circulation during boreal winter, which has a large influence on the weather and climate of the Asian-Pacific region. At interannual time scales, the strength of the EAWM is strongly influenced by the El Niño-Southern Oscillation (ENSO). With the increasing influence of human activities, the greenhouse gas-driven changes in the climate mean state and the interannual variability of the EAWM received widespread attention. However, the impact of anthropogenic aerosols has been considered only in a few studies, which may accelerate or counteract greenhouse gas-driven climatic changes over different regions. Using fixed sea surface temperature and atmosphere–ocean coupled simulations from the Precipitation Driver Response Model Intercomparison Project (PDRMIP), the local and remote impacts of Asian aerosol forcings on the broad East Asian-Pacific region are examined. Results indicate that increased sulfate concentrations over Asia by a factor of 10 strengthen the EAWM through the regional aerosol‐induced cooling first, then extend the EAWM circulation southeastward through the broader cooling over the Maritime Continent and the North Pacific. Remotely, the cooler Northern Hemisphere shifts the Intertropical Convergence Zone (ITCZ) toward the south, and the warmer sea surface temperature (SST) over the equatorial eastern Pacific leads to western-central equatorial Pacific westerly wind anomalies. These changes contribute to the increase in the ENSO’s amplitude, mainly through strengthening the Bjerknes or zonal wind feedback. Furthermore, in response to the increase in extreme El Niño and La Niña frequency, the interannual variability of the EAWM increases, with more extreme strong and weak EAWM years.

How to cite: Jia, Z., Bollasina, M., and Zhang, W.: The Local and Remote Impacts of Asian Aerosol Forcings on the East Asian Winter Monsoon and ENSO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7782, https://doi.org/10.5194/egusphere-egu24-7782, 2024.

Current and expected future aerosol emission changes are particularly strong in East and South Asia, where high population densities imply high potential climate risk. Hence, there is an urgent need for improved knowledge about the near-term influences of changes in aerosol emissions. Here we have developed a set of Systematic Regional Aerosol Perturbations (SyRAP) using the reduced complexity climate model FORTE 2.0 to explore the effects of aerosol-driven climate change. Results show that the increased Black Carbon(BC) concentrations over China and India lead to decreased local surface Temperature (Ts) and precipitation, with seasonal differences in the spatial distribution. Chinese (Indian) BC emissions also impact on Indian (Chinese) climate in specific seasons. The changes of shortwave radiation (SW) dominate the surface cooling and the lower tropospheric warming due to the absorption of BC. The reductions of column-intergrated diabatic cooling lead to the decreased local precipitation, while the changes in atmospheric circulation play an opposite role (weakened EAWM, enhanced EASM and ISM). The horizontal/vertical distributions of air temperature anomalies can induce the changes in cloud cover and atmospheric circulation, which further impact on the radiation flux and precipitation. Additionally, the increased surface albedo in winter is helpful to decrease Ts and precipitation.

How to cite: Luo, F.: Physical processes influencing the Asian climate due to the black carbon emissions over China and India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8099, https://doi.org/10.5194/egusphere-egu24-8099, 2024.

EGU24-12414 | ECS | Orals | AS3.12

The fast response of precipitation to historical black and sulfate aerosols in the GFDL ESM4 climate model 

Yanda zhang, Tom Knutson, Elena Shevliakova, and Daniel Westervelt

Aerosol effects on precipitation are crucial factors in climate change, yet they remain poorly understood, representing a large source of uncertainty in climate models. In the GFDL Earth System Model 4 (ESM4), simulated historical century-scale trends of global land precipitation demonstrate significant dry biases compared to observations, even with observed historical variations of sea surface temperature and sea ice concentrations (LongAMIP simulation). The biases manifest as overestimated decreasing precipitation trends over tropical-subtropical land and underestimated increases in higher latitudes. In this study, we investigate the “fast response” of precipitation to historical anthropogenic aerosol emissions and its contributions to the model trend biases, by conducting idealized ESM4 LongAMIP experiments with emissions of either black carbon (BC) sulfate (SO4) aerosol precursors set to near-pre-industrial levels (1850). Aerosol direct radiative effects emerge as critical drivers of excessive precipitation declines in some regions: (1) over East Asia, the negative SO4 effect and positive BC effect contribute to changes in historical precipitation and the associated model responses lead to the simulation bias. (2) For regions of Africa, the negative fast response to SO4 partially contributes to the overestimated precipitation decline. (3) Over west-central North America, the negative fast response to BC in the model contributes toward underestimating a modest observed increasing precipitation trend. However, over eastern North America and Northwest Eurasia, the fast responses of precipitation to aerosols cannot account for the opposite direction of model bias, indicating the dominant influence of other factors.

How to cite: zhang, Y., Knutson, T., Shevliakova, E., and Westervelt, D.: The fast response of precipitation to historical black and sulfate aerosols in the GFDL ESM4 climate model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12414, https://doi.org/10.5194/egusphere-egu24-12414, 2024.

EGU24-15079 | Posters on site | AS3.12

An uncertain future for anthropogenic aerosols in Africa, and their climate and health impacts 

Marianne T. Lund, Joe A. Amooli, Sourangsu Chowdhury, Ane N. Johansen, Bjørn H. Samset, and Daniel M. Westervelt

We explore the wide spread in projections of African mid-century anthropogenic air pollution levels, and associated health impacts, resulting from the large diversity in available future emission pathways for the region.

While emissions of aerosols and their precursors have declined in some regions, first in North America and Europe, more recently in China, many low- and middle-income countries, including much of Africa, are increasing their emissions and are projected to continue to do so with future industrialization, although the evolution depends in socioeconomic and technological factors. This is likely to drive changes in climate hazards as well as deterioration of air quality, increasing risks for under-resourced, vulnerable populations. The impacts of African aerosols on regional temperature, hydroclimate, and extreme events are, however, less well studied and quantified than for other historical emission hotspots. Moreover, very limited data availability and distinct regional characteristics of sources result in high uncertainties in estimates of African emissions. This uncertainty translates into future projections, which exhibit a striking spread in magnitudes and trends. For instance, available estimates for emissions of sulfur dioxide and black carbon in 2050 differ by up to 70% and 90% between the Shared Socioeconomic Pathways (SSPs) and scenarios developed for the UN Environmental Programme’s (UNEP) Integrated Assessment of Air Pollution and Climate Change in Africa.

Here we explore implications of this spread for downstream modeled quantities of relevance for climate and health impact assessments. We use emissions from 10 different pathways as input to the chemical transport model OsloCTM3 and simulate the distribution of anthropogenic aerosols across the African continent in 2050. The associated impact on premature mortality is calculated. Preliminary results show surface PM2.5 concentrations differing by up to a factor 2 between the highest and lowest scenario when averaged over the African continents, with markedly higher local spread. Sub-continental differences are substantial, pointing to the need to consider Africa in more geographical detail than often done.

How to cite: Lund, M. T., Amooli, J. A., Chowdhury, S., Johansen, A. N., Samset, B. H., and Westervelt, D. M.: An uncertain future for anthropogenic aerosols in Africa, and their climate and health impacts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15079, https://doi.org/10.5194/egusphere-egu24-15079, 2024.

EGU24-16012 | ECS | Posters on site | AS3.12

Apportionment of absorption in complex aerosols in South Africa 

Clarissa Baldo, Brigitte Language, Tommaso Isolabella, Virginia Vernocchi, Dario Massabò, Claudia Di Biagio, Pieter Van Zyl, Stuart Piketh, and Paola Formenti

South Africa, with its industrialised economy, faces unique air pollution challenges. Our study investigates aerosol composition and absorption in the Highveld region. Understanding aerosol absorption is critical as it affects climate, air quality, and public health. Aerosol absorption in the lower atmosphere affects the evolution of the boundary layer and the dispersion of pollutants, which in turn affects air quality and public health. Aerosol filter samples (PM10 fractions) were collected from residential, traffic, and industrial sites during the dry season. Chemical analyses, including X-ray fluorescence, thermo-optical analysis, and ion chromatography, were carried out to determine elemental species, carbonaceous species, and water-soluble ions, respectively. Based on this, a mass closure calculation was performed to define the contribution of five major aerosol components. The calculated aerosol mass concentrations were in good agreement with the measurements (Normalised Mean Bias, NMB < 7%). No significant variation in PM10 concentration was observed between site types. Mineral dust appeared to be the main contributor to PM10, varying from about 48%-60% at different sites, followed by organic matter (OM, 22%-35%), secondary inorganic aerosols (SIA, 9%-12%), elemental carbon (EC, 4%-7%), and sea salt (ss, 1%-2%).

Aerosol spectral absorption was obtained from multi-wavelength absorbance analysis (MWAA) measurements at 375, 407, 532, 635, and 850 nm. High absorption was measured in the following order: industrial> residential> traffic sites. The estimated absorption Ångström exponent (AAE) varied from 0.8 to 2 at different sites, indicating the contribution of several sources. At 850 nm absorption correlates well with EC as expected (r = 0.85). The obtained mass absorption efficiency (8 m2/g) is in line with expectations. Specific tracers were used to determine the contribution of the main absorbing aerosol components - black carbon (BC), brown organic carbon (BrC) from incomplete biomass combustion, and mineral dust - using correlations between estimated mass and measured absorption. Preliminary results indicate that although BC is the major contributor to absorption, accounting for 30%-60% absorption at 375 nm, followed by BrC 10%-50%, the contribution of the less absorbing but more abundant mineral dust is not negligible and can range from 2% to 50% in different samples. These results underline the complexity of aerosols in the region and their high absorption properties, and the need for a comprehensive understanding of its various components to accurately assess its impact.

How to cite: Baldo, C., Language, B., Isolabella, T., Vernocchi, V., Massabò, D., Di Biagio, C., Van Zyl, P., Piketh, S., and Formenti, P.: Apportionment of absorption in complex aerosols in South Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16012, https://doi.org/10.5194/egusphere-egu24-16012, 2024.

EGU24-18153 | ECS | Orals | AS3.12 | Highlight

Why climate models underestimate the exacerbated summer warming in Western Europe 

Dominik L. Schumacher, Jitendra Singh, Mathias Hauser, Erich M. Fischer, Martin Wild, and Sonia I. Seneviratne

Since 1980, mean summer temperatures in Western Europe have warmed three times faster than global mean temperatures. This strong warming of about 2.3 °C tends to be underestimated in model simulations, affecting both global and in particular regional climate models (RCMs). We demonstrate that the majority of global and regional climate model simulations exhibit weaker circulation-related warming contributions than observed, partly accounting for the discrepancy between observations and models. Crucially, most RCMs from the Coordinated Regional Downscaling Experiment (CORDEX) additionally underestimate the thermodynamic contribution to warming that occurs primarily in response to anthropogenic forcings. Because the driving global climate models of the CORDEX RCM simulations all provide at least sufficient, and typically even excessive global background warming, this partly compensates for the frequent lack of regional thermodynamic warming. We find that the main cause of the latter is the widespread use of constant aerosol concentrations in RCM simulations, such that the regional brightening and associated warming in Europe due to aerosol reductions in the past decades is not captured. 

We infer a summer warming underestimation of about 0.5 °C since 1980 when relying on RCMs with constant rather than evolving aerosols over Western Europe, although this depends on the GCM–RCM ensemble subset. Locally, in parts of Eastern Europe with stronger aerosol reductions than further west, the discrepancies can exceed 1 °C. The use of constant aerosol representations not only contributes to the summer warming discrepancy in Europe but also impacts other seasons except winter. At the timescales of heat extremes, the aerosol representation-inflicted mismatch manifests even more clearly: heatwave intensity changes since 1980 are already underestimated by RCMs with constant aerosols by about 1°C in western Europe, and the warming discrepancies grow even larger in projections, exceeding 2 °C in large parts of Europe and at the end of the ongoing century. Our work highlights the importance of representing all relevant external forcings and associated responses in RCM simulations, as the added value of high-resolution climate projections is questionable when the strong regional brightening and warming in Europe and other regions is by design omitted.

How to cite: Schumacher, D. L., Singh, J., Hauser, M., Fischer, E. M., Wild, M., and Seneviratne, S. I.: Why climate models underestimate the exacerbated summer warming in Western Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18153, https://doi.org/10.5194/egusphere-egu24-18153, 2024.

Current extremes within regional water cycles, extensive drought periods and torrential flooding, are   associated in literature and media to first indicators of greenhouse gas driven climate change. Indeed, they are among major threats to be expected from climate change model results. The main obvious physical process behind such global warming water cycle extremes, is the temperature dependent water vapor content of air (Clausius Clapeyron, 1834, CC) and it’s increase by ~ 7% per degree C. Naturally the water vapor input into the atmosphere via evapotranspiration is dependent on shortwave radiation reaching the surface, a process controlled partially by fine particles, partially by clouds. Here the ultrafine, invisible, fraction of the aerosols is becoming important.

Ultrafine particles (UFP) acting as cloud condensation nuclei (CCN) are the driving force behind cloud modification and changing rainfall patterns. However, the sources and budgets of anthropogenic primary and secondary particles were not well known. Based on airborne measurements we identified as a major contribution modern fossil fuel flue gas cleaning techniques to cause a doubling of global primary UFP number emissions. The subsequent enhancement of CCN numbers has several side effects. It’s changing the size of the cloud droplets and delays raindrop formation, suppressing certain types of rainfall and increasing the residence time of water vapor in the atmosphere. This additional latent energy reservoir is directly available for invigoration of rainfall extremes. Additionally it’s a further contribution to the column density of water vapor as a greenhouse gas and important for the infrared radiation budget. The localized but ubiquitous fossil fuel related UFP emissions and their role in the hydrological cycle, may thus contribute to regional or continental climate trends, such as increasing drought and flooding, observed within recent decades.

We discuss the impact of the ultrafine fraction on the hydrological cycle and its historical timeline. Ultrafine particles (UFP) initially don’t interact with radiation like fine ones. However, a significant increase of the ultrafine particle burden may serve similar to CC to more water vapor molecules, respectively more latent energy in the troposphere, especially in the altitude range of convective clouds. We also discuss the origin of the majority of UFP, whether a simple dependence of ultrafine particles on the atmospheric sulphur load is a reasonable and valid assumption and what should be taken additionally into account for future UFP szenarios.

Junkermann, W. & Hacker, J., 2022, Unprecedented levels of ultrafine particles, major sources, and the hydrological cycle, Nature Scientific Reports, 12:7410 https://doi.org/10.1038/s41598-022-11500-5

Junkermann, W. (2022). Ultrafine particle emissions in the Mediterranean region. In F. Dulac, S. Sauvage, & E. Hamonou (Eds.), Atmospheric chemistry in the Mediterranean region (Vol. 2, From air pollutant sources to impacts). Springer, 21 pp. https://doi.org/10.5445/IR/1000154173

How to cite: Junkermann, W. and Hacker, J.: Invisible, overlooked, climate relevant? Unprecedented levels of ultrafine particles and the hydrological cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20286, https://doi.org/10.5194/egusphere-egu24-20286, 2024.

EGU24-20552 | Posters on site | AS3.12

Concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans in Kuala Lumpur urban environment and their potential risk to human health 

Mohd Talib Latif, Sharifah Mazrah Syed Zain, Norfazrin Mohd Hanif, Md Firoz Khan, and Jivantiran Myilravanan

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are persistent organic pollutants that affect human health. This study aimed to quantify the concentrations of 17 PCDDs/PCDFs congeners in ambient air in the urban environment of Kuala Lumpur and their potential risk to humans. PM2.5 and TSP were collected on quartz microfibre using separate high-volume samplers, whereas the gaseous phase and passive samples were captured on polyurethane between December 2021 and October 2022. The results show the Ʃ17PCDD/PCDF concentration in ambient air is 736 ± 375 fg WHO-TEQ m-3, whereas PM2.5, TSP, and gaseous phase concentrations are 223 ± 161 fg WHO-TEQ m-3, 337 ± 213 fg WHO-TEQ m-3 and 507 ± 273 fg WHO-TEQ m-3, respectively. The hepta- and octa-group congeners dominated up to 80% of the Ʃ17PCDDs/PCDFs and are more likely to bind with the particle phase than the gaseous phase. The Ʃ17PCDDs/PCDFs displayed a significant difference between gaseous and particle concentrations (p <0.001). Exposure to the gaseous phase of Ʃ17PCDDs/PCDFs resulted in a greater inhalation lifetime cancer risk (1.58E06-5.28E-06). This study found that the toxic equivalent (TEQ) concentrations are dominant in the gaseous phase, while cancer risks from exposure to PCDDs/PCDFs in the air are tolerable in children and adults.

How to cite: Latif, M. T., Zain, S. M. S., Mohd Hanif, N., Khan, M. F., and Myilravanan, J.: Concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans in Kuala Lumpur urban environment and their potential risk to human health, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20552, https://doi.org/10.5194/egusphere-egu24-20552, 2024.

EGU24-20722 | Posters on site | AS3.12

Enhanced aerosol-induced near-term Arctic warming due to remote regional aerosol perturbations in RAMIP 

Daniel Westervelt, Yanda Zhang, Joe Adabouk Amooli, Kostas Tsigaridis, Larissa Nazarenko, Bjørn Samset, Laura Wilcox, and Robert Allen

The climatic implications of regional aerosol and precursor emissions reductions implemented to protect human health are poorly understood. However, quantitative estimates of climate responses to emission perturbations are needed by the climate assessment and impacts community. The Regional Aerosol Model Intercomparison Project (RAMIP) project builds on recent CMIP5 and CMIP6-era studies to help address this knowledge gap. Briefly, RAMIP will use contrasting SSP aerosol emissions (SO2, BC, OC) scenarios (SSP3-7.0 and SSP1-2.6) to isolate the impact of realistic, near term aerosol changes on climate and air quality over rapidly developing regions of South Asia, East Asia, and Africa, and over North America and Europe. At least 9 CMIP6-generation global climate models are contributing to this new MIP, which uniquely focuses on specific regional aerosol emissions changes rather than simultaneous global changes. This presentation will specifically present the first results from several participating models in RAMIP, namely the NASA Goddard Institute for Space Studies (GISS) ModelE, UKESM, CESM2, and NorESM. All Tier 1 simulations of RAMIP are included, with 10 ensembles for each simulation. Initial analysis at the time of writing confirms the anticipated changes in aerosol optical depth, downwelling shortwave radiation, and aerosol mass concentration over each of the regions. The warming response to a decrease in SO2, BC, and OC is strongest in the US and Europe perturbation simulations, both globally and regionally, with Arctic warming up to 0.3 K due to a removal of US and European anthropogenic aerosol emissions alone; however, even emissions from regions more remote to the Arctic, such as South Asian aerosols, can significantly warm the Arctic up to 0.2 K. In most regions, temperatures are most sensitive to emissions perturbations within that region. Arctic warming is the most robust model response across the regional aerosol emissions perturbations. 

How to cite: Westervelt, D., Zhang, Y., Amooli, J. A., Tsigaridis, K., Nazarenko, L., Samset, B., Wilcox, L., and Allen, R.: Enhanced aerosol-induced near-term Arctic warming due to remote regional aerosol perturbations in RAMIP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20722, https://doi.org/10.5194/egusphere-egu24-20722, 2024.

EGU24-20840 | Orals | AS3.12

The Tables of Aerosol Optics (TAO) 

Gregory L. Schuster, Elisabeth Andrews, Eduard Chemyakin, Mian Chin, Jacek Chowdhary, Cheng Dang, Yevgeny Derimian, Arlindo da Silva, Fabrice Ducos, William Reed Espinosa, Philippe Lesueur, Richard Moore, Hans Moosmuller, Nobuhiro Moteki, Greema Regmi, Masanori Saito, Snorre Stamnes, Bastiaan van Diedenhoven, and Ping Yang

There is a need to quickly convert aerosol microphysical properties into optical properties for global modeling, data assimilation, and remote sensing applications. This is generally accomplished through look-up tables (LUTs) of aerosol mass extinction coefficients (MEC), mass absorption coefficients (MAC), asymmetry parameters, normalized phase functions, etc. Unfortunately, many scientists are using outdated LUTs that are based upon measurements and computational techniques first published by Shettle and Fenn (1979) and later updated by Hess et al. (1998). Thus, the computations in common use are still largely based upon Mie theory and in situ information that has not been updated during this century.

The Table of Aerosol Optics (TAO) is an open relational database (under construction) that expands upon existing LUTs by including recent measurements and new computational techniques for non-spherical particles (https://science.larc.nasa.gov/mira-wg/topics/tao/). The ‘open’ aspect of TAO is important, since the measurements and techniques of today will undoubtedly yield to different values in the future. This open architecture allows specialists to add new tables and gain exposure for their work and benefits modelers and remote sensing scientists by giving them easy access to computations that utilize the latest techniques. Quality is controlled by requiring methods to be peer-reviewed in the scientific literature.

Thus far, we have computed mass extinction coefficients, mass absorption coefficients, lidar ratios, etc., at 73 wavelengths ranging from 0.25-40 µm for black carbon (BC), brown carbon (BrC), non-absorbing organic carbon, and mineral dust. For mineral dust, we use hexahedra shapes and mineral mixtures of montmorillonite, illite, hematite, and goethite. The illite volume fraction varies from 0 to 59% to capture the range of real refractive indices found in AERONET climatologies; the sum of the hematite and goethite mass fractions are ~2%. Additional mixtures will be added as appropriate.

We have also computed optical properties for 22 size distributions of bare aggregated BC using the Multi-Sphere T-Matrix (MSTM) code (https://github.com/dmckwski/MSTM) at several remote sensing wavelengths. Our MSTM computations use aggregates of 20-nm spherules with particle-cluster growth. We obtained mass absorption coefficients (MACs) of 7.2-7.5 m2/g at a mid-visible wavelength (532 nm) when the BC fractal dimension was fixed at Df = 1.8 (i.e., fresh BC), consistent with values commonly recommended in literature reviews.

We will present the TAO vision and example results for several aerosol types. TAO is part of the Models, In situ, and Remote sensing of Aerosols (MIRA) working group. MIRA seeks to build collaboration, consistency, and openness amongst the aerosol disciplines. We seek community feedback from aerosol scientists regarding the construction and content of TAO, especially  in this early phase. Check out the MIRA webpage at https://science.larc.nasa.gov/mira-wg/ and subscribe to our mailing list at https://espo.nasa.gov/lists/listinfo/mira.

Hess et al. (1998): Optical properties of aerosols and clouds: The software package OPAC, BAMS, 79, 831–844.

Shettle and Fenn (1979): Tech. Rep. AFGL-TR-790214, Air Force Geophysics Laboratory, 1979.

How to cite: Schuster, G. L., Andrews, E., Chemyakin, E., Chin, M., Chowdhary, J., Dang, C., Derimian, Y., da Silva, A., Ducos, F., Espinosa, W. R., Lesueur, P., Moore, R., Moosmuller, H., Moteki, N., Regmi, G., Saito, M., Stamnes, S., van Diedenhoven, B., and Yang, P.: The Tables of Aerosol Optics (TAO), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20840, https://doi.org/10.5194/egusphere-egu24-20840, 2024.

EGU24-20865 | Posters on site | AS3.12

Relational database construction for Table of Aerosol Optics 

Yevgeny Derimian, Fabrice Ducos, Philippe Lesueur, and Gregory L. Schuster

This effort is dedicated to construction of a relational database and an interactive web system that organizes and communicates aerosol optical and microphysical characteristics assembled in the Table of Aerosol Optics (TAO) community repository. The TAO project (https://science.larc.nasa.gov/mira-wg/topics/tao/) is an extension of historical efforts (e.g., Shettle and Fenn, 1979; d’Almeida et al., 1991; Koepke et al., 1997; Hess et al., 1998) on providing libraries of aerosol characteristics for applications in global chemical transport modeling and remote sensing. Aerosol characteristics such as size distribution, complex refractive index, shape, mixing state, extinction, absorption, single-scatter albedo, lidar ratio, etc. are provided for different aerosol types, wavelengths, be originated from laboratory measurements, in situ or remote sensing observations. Combination of aerosol characteristics, their origins, types, spectral domains, computational techniques used for single-scatter properties become quickly very complex and is expected to evolve in future. The open access and interactive principles of TAO implies increasing complexity of its database structure that requires involvement of dedicated computer science technics for its organization and management. The relational database conception, for instance, is widely used in many domains that require such data organization and naturally appropriates to TAO. The relational database consists in structuring the data in multiple tables, with so-called primary or foreign keys that relates between entity types, parameters and their value in unique or multiple connections. We therefore started development of tools for uploading of the TAO data into the format of relational database and creation of a web interface for an interactive communication with the community. This work is expected to be presented as complimentary to a more general presentation about the TAO project by G. L. Schuster and gather valuable feedbacks from modelers, in situ and remote sensing experts on the data needs, convenient exchange formats and potential applications.

How to cite: Derimian, Y., Ducos, F., Lesueur, P., and Schuster, G. L.: Relational database construction for Table of Aerosol Optics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20865, https://doi.org/10.5194/egusphere-egu24-20865, 2024.

EGU24-21847 | Orals | AS3.12 | Highlight

Climate responses to a rapid phaseout of sulfur in shipping emissions: A large ensemble study 

Duncan Watson-Parris, Bjørn H. Samset, Robert Allen, Massimo Bollasina, Annica Ekman, Carley Iles, Manoj Joshi, Anna Lewinschal, Marianne T. Lund, Joonas Merikanto, Kalle Nordling, Geeta Persad, Camilla W. Stjern, Dan Westervelt, Laura J. Wilcox, and Andrew Williams

In 2020, motivated by improving air quality in major ports and shipping lanes, the International Maritime Organization imposed strict new regulations on the sulfur content of shipping fuel. This led to a rapid reduction in the number of observed ship tracks (linear tracks of clouds brightened by aerosol perturbations; Watson-Parris et al. 2022), and presumably a commensurate reduction in anthropogenic aerosol forcing. The magnitude of this forcing, and the resulting temperature change, are uncertain however. The recent confirmation that 2023 was the hottest year on record can only partly be explained by the onset of the El Niño phase of the El Niño-Southern Oscillation (ENSO). Such warming, in addition to the sizable warming in NH ocean basins- geographically collocated with shipping- raise the question of how much shipping emissions changes might have contributed to this signal, and any extreme weather events associated with it.

 

In this study we aim to answer this question by utilizing a large ensemble of fully-coupled Community Earth System Model version 2 (CESM2) simulations with and without the shipping emissions changes. We leverage the CESM2 large ensemble and choose 20 simulations with varying ENSO conditions from which to branch off with shipping emissions reduced to 20% of their baseline value. These are integrated forward for another 20 years, while non-shipping emissions follow the SSP3-7.0 scenario, in order to robustly explore the transient climate response.

In this talk we will highlight the forced climate response, focusing on temperature (T), precipitation (P), and atmospheric circulation, both globally and in key regions such as the North Atlantic. Given the change in ENSO phase during 2023, we will also describe how this climate response is modulated by different ENSO conditions, the Atlantic Multidecadal Variability and other modes of climate variability. The underlying relevant climate processes, including cloud dynamics, radiative imbalances at the top of the atmosphere, and daily variability will be summarized to link our single model study to observed changes.

References:

[1] Watson-Parris, D., Christensen, M., Laurenson, A., Clewley, D., Gryspeerdt, E., Stier, P. “Shipping regulations lead to large reduction in cloud perturbations”. PNAS 119 (41) e2206885119: https://doi.org/10.1073/pnas.2206885119 (2022)

How to cite: Watson-Parris, D., Samset, B. H., Allen, R., Bollasina, M., Ekman, A., Iles, C., Joshi, M., Lewinschal, A., Lund, M. T., Merikanto, J., Nordling, K., Persad, G., Stjern, C. W., Westervelt, D., Wilcox, L. J., and Williams, A.: Climate responses to a rapid phaseout of sulfur in shipping emissions: A large ensemble study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21847, https://doi.org/10.5194/egusphere-egu24-21847, 2024.

EGU24-93 | ECS | PICO | AS3.9

Late Pleistocene East Asian monsoon intensity variations and driving mechanisms: Evidence from a multi-proxy analysis of loess deposits on an East China Sea island 

Zhigang Wang, Laurent Marquer, Yuanyu Cheng, Xiuxiu Ren, Hao Long, Shaofang Ren, Peng Qian, and Xiangmin Zheng

Shengshan Island (SSD), located in East China Sea, contains loess deposits that serve as an excellent carrier for recording environmental changes in the eastern subtropical region of China. Different from the continental Loess Plateau, SSD loess possesses distinctive characteristics due to its coastal location. Here we conducted the first pollen analysis to reconstruct vegetation dynamics in the SSD region during the middle to late Late Pleistocene period (75-40 ka). Biological indicators (i.e., total organic concentration and δ13Corg), along with geochemical proxies (i.e., quartz grain size, magnetic susceptibility, iron oxide ratios, clay minerals, and trace elements), were employed to reconstruct climatic dynamics in the SSD area. The study identified two stages in the evolution of the East Asian Monsoon. In Stage I (75-60 ka), various indicators (i.e., pollen concentration, Pinus concentration, magnetic susceptibility, C4 abundance, K/(I+Ch), Illite crystallinity, CII, Hm/Gt, quartz median grain size, Zr/Rb) increased, suggesting a strengthening of both winter and summer monsoons. In Stage II (60-40 ka), some indicators (i.e., pollen concentration, Pinus concentration, quartz median grain size, Zr/Rb) continued to increase while others (i.e., magnetic susceptibility, C4 abundance, K/(I+Ch), Illite crystallinity, CII, Hm/Gt) decreased, indicating a continued intensification of the winter monsoon but a weakening of the summer monsoon. Further, we explored the driving forces behind variations in monsoon intensity, analyzing changes in various δ18O proxies and sea-level fluctuations. The findings suggest that different mechanisms influence the winter and summer monsoons. Summer monsoon intensity is linked to changes in summer solar radiation at mid-latitudes in the Northern Hemisphere, while winter monsoon dynamic is affected by changes in ice volume and ice sheets. These insights contribute to our understanding of environmental changes related to the East Asian Monsoon, offering valuable perspectives on how these mechanisms could respond to future climate changes.

How to cite: Wang, Z., Marquer, L., Cheng, Y., Ren, X., Long, H., Ren, S., Qian, P., and Zheng, X.: Late Pleistocene East Asian monsoon intensity variations and driving mechanisms: Evidence from a multi-proxy analysis of loess deposits on an East China Sea island, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-93, https://doi.org/10.5194/egusphere-egu24-93, 2024.

EGU24-430 | ECS | PICO | AS3.9

West African dust load modeling and its impact on solar radiation forecast during the dry season 

Léo Clauzel, Sandrine Anquetin, Christophe Lavaysse, Guillaume Siour, Gilles Bergametti, Béatrice Marticorena, Christel Bouet, Rémy Lapere, and Jennie Thomas

The expected growth of solar photovoltaic (PV) production in West Africa over the coming decades poses challenges to the electrical network requiring accurate solar forecasts for both energy producers and power grid managers. Furthermore, solar radiation is affected by dust aerosols which play a significant role in West African meteorology, due to the proximity of this region to the Sahara desert, which is the world's largest source of mineral dust aerosols emissions.

In this general context, our research aims at identifying the impact of mineral dust on solar energy production. Thus, this study focuses on evaluating the influence of dust aerosols on solar radiation forecasts for the Zagtouli solar plant in Burkina Faso. 

Employing a coupled approach between a meteorological model (WRF) and a chemical transport model (CHIMERE), two dust events that are representative of the dry season are simulated in line with West African climatology. While one event is linked to dust emissions from the Bodélé plateau (Chad), the other is related to dust sources located within the South Atlas area.

The model undergoes rigorous assessment in regards to dust life cycle parameters (Aerosol Optical Depth (AOD), PM10, size distribution) and variables essential for solar energy production (Global Horizontal Irradiance (GHI), temperature) using in-situ measurements from long-term observatories (AERONET, INDAAF, AMMA-CATCH) and from the solar farm (GHI), satellite observations (AQUA/TERRA-MODIS, CALIPSO-CALIOP), and reanalysis data (CAMS). This evaluation shows a robust performance of the model.

In addition, sensitivity studies are implemented to evaluate the respective impacts of direct and indirect effects of dust aerosols on the amount of solar radiation available at the surface.

Overall, this study provides strong support for a modeling approach that couples meteorological processes with the dust life cycle to refine solar forecasts in the West African region.

How to cite: Clauzel, L., Anquetin, S., Lavaysse, C., Siour, G., Bergametti, G., Marticorena, B., Bouet, C., Lapere, R., and Thomas, J.: West African dust load modeling and its impact on solar radiation forecast during the dry season, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-430, https://doi.org/10.5194/egusphere-egu24-430, 2024.

EGU24-989 | ECS | PICO | AS3.9 | Highlight

Atmospheric radioisotopes in cryoconite from the Flade Isblink ice cap, NE Greenland 

Dylan Beard, Giovanni Baccolo, Caroline Clason, Geoffrey Millward, Edyta Łokas, Sally Rangecroft, Dariusz Sala, Przemysław Wachniew, and William Blake

Under climatic warming and increased melting, glaciers and ice caps are becoming secondary sources of contaminants deposited decades ago. Cryoconite, an organic-rich material found on the surface of many glaciers, is particularly efficient at accumulating airborne contaminants due to biogeochemical exchanges with the organic matter within cryoconite. Atmospherically derived radioactive isotopes, commonly referred to as fallout radionuclides, have now been found to accumulate in cryoconite globally. However, data from the polar regions, especially ice sheets and ice caps, is scarce. This study helps to address this regional gap in understanding fallout radionuclide accumulation in glacial settings. We present the first radioactivity dataset from cryoconite on a Greenlandic ice cap and assess the role of cryoconite in the distribution of radioactive species in the High Arctic. Forty-six cryoconite samples were collected from the Flade Isblink ice cap (NE Greenland) in August 2022. These samples were analysed via alpha and gamma spectrometry for atmospheric radionuclides, including 137Cs, 241Am, 210Pbexc., 207Bi, 7Be, and several plutonium isotopes. The results of this study confirm cryoconite's exceptional ability to accumulate fallout radionuclides, even in remote and relatively pristine regions such as Northern Greenland. The activities of radionuclides in cryoconite from Flade Isblink are among the highest reported across the High Arctic and the highest ever reported from Greenland. Flade Isblink's radioactivity source is compatible with the stratospheric reservoir established during atmospheric nuclear tests and with weapon-grade fissile fuel, likely originating from Novaya Zemlya. Our findings emphasise the necessity for continued research efforts on the release of legacy contaminants from glaciers, particularly given accelerated global warming and consequent glacier retreat.

How to cite: Beard, D., Baccolo, G., Clason, C., Millward, G., Łokas, E., Rangecroft, S., Sala, D., Wachniew, P., and Blake, W.: Atmospheric radioisotopes in cryoconite from the Flade Isblink ice cap, NE Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-989, https://doi.org/10.5194/egusphere-egu24-989, 2024.

EGU24-1776 | PICO | AS3.9 | Highlight

Assessment of the Impact of Coarse and Fine Dust on Solar Devices in the Middle East 

Suleiman Mostamandi, Georgiy Stenchikov, Ahmed Balawi, Illia Shevchenko, Dania Kabakebji, and Thomas Altmann

Dust in the Middle East (ME) significantly impacts regional climates and negatively affects the operation of solar farms in the ME region. Suspended dust particles attenuate downward short wave (SW) radiation, while dust deposited on the solar devices decreases effectiveness. This study theoretically assesses dust's attenuation and soiling effects on solar panels within the ME, employing a Weather Research Forecasting Model coupled with the aerosol-chemistry module, WRF-Chem, constrained by observed dust depositions. By analyzing the size distribution of dust deposition samples, we found that a major part of the deposited mass resulted from the deposition of dust particles with radii > 10 um. However, the models usually consider only particles with radii < 10 um.

We corrected this deficiency and conducted a year-long simulation using WRF-Chem. We found that the dust (primarily fine particles with radii < 3 m) reduces the downward SW radiation near the surface by 5-10%. Meanwhile, dust deposition (mostly coarse dust particles with radii > 6 m) imposes soiling losses of 12 to 36 % in different parts of the ME, assuming a weekly cleaning cycle.

Our findings unveil a complex interplay between dust size and its multifaceted impact on solar energy production. This novel insight could lead to optimized maintenance strategies and novel mitigation approaches tailored to the unique dust burden of the Middle East. Ultimately, this study aims to advance solar energy resource assessment and pave the way for enhanced photovoltaic efficiency in dust-prone regions.

How to cite: Mostamandi, S., Stenchikov, G., Balawi, A., Shevchenko, I., Kabakebji, D., and Altmann, T.: Assessment of the Impact of Coarse and Fine Dust on Solar Devices in the Middle East, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1776, https://doi.org/10.5194/egusphere-egu24-1776, 2024.

EGU24-1827 | PICO | AS3.9

Investigation of the mineralogical composition of desert dust particles during a transboundary pollution episode in the UK and implications for health effects  

Stavros Solomos, Christina Mitsakou, Samuel Thompson, Helen Macintyre, Karen Exley, Stuart Aldridge, Christos Zerefos, Nikolaos S. Bartsotas, Christina Kalogeri, and Christos Spyrou

Toxicological and epidemiological studies have supported links between desert dust particles and health impacts, such as worsened asthma, hospitalization for respiratory infections, and seasonal allergic rhinitis. Airborne desert dust particles could serve as a medium for interacting with chemicals on their surfaces, potentially enhancing the bioreactivity of fine particles during episodes of dust storms. The role of the different mineralogical composition (e.g. quarz, iron, feldspars) on the biological effects of mineral dust remains to be determined. In this work we analyze the severe dust event that affected the UK on 15 and 16 March 2022 in terms of the synoptic situation leading to this event, the spatiotemporal distribution of the dust plumes over UK and the chemical/mineralogical composition of the particles. We employ the METAL-WRF model to investigate the atmospheric properties and the quantification of particle concentrations in ambient air but also in dry and wet depositions of dust. The METAL-WRF model includes prognostic fields for ten (10) minerals: illite, kaolinite, smectite, calcite, quartz, feldspar, hematite, gypsum, phosphorus and iron. We also investigate the health impacts linked to the desert dust transport on the population in UK regions. Our results are discussed across similar findings at more frequently dust-affected regions such as the Mediterranean.  

Acknowledgment This study is partially supported by the Hellenic Foundation for Research and Innovation project Mineralogy of Dust Emissions and Impacts on Environment and Health (MegDeth - HFRI no. 703) and the project Bioclimatic urban design for the sustainability and resilience of the urban environment in the context of climate change (BIOASTY)

How to cite: Solomos, S., Mitsakou, C., Thompson, S., Macintyre, H., Exley, K., Aldridge, S., Zerefos, C., Bartsotas, N. S., Kalogeri, C., and Spyrou, C.: Investigation of the mineralogical composition of desert dust particles during a transboundary pollution episode in the UK and implications for health effects , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1827, https://doi.org/10.5194/egusphere-egu24-1827, 2024.

EGU24-2280 | ECS | PICO | AS3.9

Different orbital rhythms in loess grain-size records across the Chinese Loess Plateau 

Deai Zhao, Guoqiao Xiao, Qingzhen Hao, Shaohua Tian, Zhipeng Wu, Hao Lu, Gaowen Dai, Shuzhen Peng, Chunjv Huang, and Qiuzhen Yin

The thick loess-paleosol sequences on the Chinese Loess Plateau (CLP) are among the best terrestrial archives for the understanding of the global paleoenvironment and East Asian monsoon changes. In particular, orbital-scale variations characterized by major periodicities of ~100 kyr, ~40 kyr and ~20 kyr are recorded by various proxies in the loess, which is often suggested to reflect the orbital control on East Asian climate. However, whether these climate periods could be affected by the signals from the dust source areas remains unknown. Here we present the spectrum results of grain size records from the Baoji loess section spanning the past 400 ka in the southeastern part of the CLP, and compare with the previous results in the western CLP (to the west of the Liupanshan Mts.), including Gulang, Menyuan, Lanzhou, Linxia, Jingyuan loess sections, and loess sections in the eastern CLP (to the east of the Liupanshan Mts.), including Luochuan, Xifeng, Lantian, and Weinan sections. The results show that the dominant periods in different sections are spatially different, and the ~20-kyr precession cycle from the western CLP is significantly stronger than that in eastern CLP. Albeit dust accumulation rates in the Jingbian loess section from the eastern CLP are very high, the lack of precession signal suggests that high sedimentation rate is not the main factor for occurrence of precession cycle in grain size records. The results also suggest that the dust source areas for the eastern and western CLP are different, specifically, the loess deposits in western CLP were mainly sourced from the NE Tibetan Plateau, while the loess deposits in eastern CLP were significantly fed by the deserts to the north CLP (including deserts in Northern China and Southern Mongolia). As the dust production and transportation in NE Tibetan Plateau and the deserts to the north CLP were significantly driven by the ~20-kyr local summer insolation and the ~100-kyr ice age cycle, respectively, we argue that the climate cycle in loess grain size of the CLP indeed reflects the climate signals of their source areas, rather than the deposition areas. Our results suggest that caution should be taken when explaining the meaning of the loess grain size records.

How to cite: Zhao, D., Xiao, G., Hao, Q., Tian, S., Wu, Z., Lu, H., Dai, G., Peng, S., Huang, C., and Yin, Q.: Different orbital rhythms in loess grain-size records across the Chinese Loess Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2280, https://doi.org/10.5194/egusphere-egu24-2280, 2024.

EGU24-3106 | PICO | AS3.9 | Highlight

African dust transport and deposition modelling verified through a successful citizen science campaign in Finland   

Outi Meinander, Rostislav Kouznetsov, Andreas Uppstu, Mikhail Sofiev, Anu Kaakinen, Johanna Salminen, Laura Rontu, Andre Welti, Diana Francis, Ana A. Piedehierro, Pasi Heikkilä, Enna Heikkinen, and Ari Laaksonen

On 21–23 February 2021, dust from a sand and dust storm (SDS) in northern Africa was transported to Finland, north of 60°N. The episode was predicted 5 days in advance by the Finnish Meteorological Institute (FMI) global operational SILAM forecast (silam.fmi.fi), and its key features (e.g., spatial distribution of wet and dry deposition amounts and particle sizes) were confirmed and detailed by a retrospective analysis. SILAM is among the dust forecast models included in the Word Meteorological Organization Sand and Dust Storm Warning Advisory and Assessment System WMO SDS-WAS.  

Dust deposition was observed on 23 February over a large area in the Southern and Central Finland from 60°N to >63.8°N. The ground was covered with snow making dust more easily detectable. The coloured snow caused people to contact FMI asking what is happening. FMI launched a citizen science campaign on Saharan dust with the help of social media, and people were asked to report their observations and to collect dust-containing snow and to extract the dust according to the guidelines. The campaign gained wide national interest in television, radio, newspapers and social media, and resulted in success in receiving citizen samples from 525 locations, with one to over ten samples in each.

The amounts of deposition calculated from the citizen samples were found to be up to 1.1 g/m2 and such maximum amounts per unit area agree with the SILAM calculations. The SILAM model and particle magnetic properties confirmed that dust came from a wide Sahara and Sahel area, from 5000 km away. The median diameters of the dust particles were in the modes of <10 µm and >20 µm. The mineral composition was dominated by quartz, feldspars, and soft phyllosilicates such as micas and clay minerals.

To extract dust from snow, Meinander et al. (2023) protocol recommends: 1. Collect snow samples within one week of the deposition event to minimize post-deposition changes. 2. Evaporate snow under 75oC to preserve the magnectic properties (particles should not be subjected to temperatures higher than 90oC). 3. Keep the remaining particles in the container in which the evaporation took place (e.g., a sheet of aluminium folio on a large oven tray and evaporating the snow in the oven) to best preserve all the particle sizes. 

Reference: Meinander, O., Kouznetsov, R., Uppstu, A. et al. African dust transport and deposition modelling verified through a citizen science campaign in Finland. Sci Rep 13, 21379 (2023). https://doi.org/10.1038/s41598-023-46321-7. 

 

 

How to cite: Meinander, O., Kouznetsov, R., Uppstu, A., Sofiev, M., Kaakinen, A., Salminen, J., Rontu, L., Welti, A., Francis, D., A. Piedehierro, A., Heikkilä, P., Heikkinen, E., and Laaksonen, A.: African dust transport and deposition modelling verified through a successful citizen science campaign in Finland  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3106, https://doi.org/10.5194/egusphere-egu24-3106, 2024.

Dust storms are severe and disastrous weather events that typically occur in arid and semi-arid desertification areas. The frequent occurrences of spring dust storms in East Asia in recent years have drawn widespread attention in the context of the significant achievements in ecological management and sand prevention. Identifying the source and transport of dust storms in East Asia is key to comprehending the ecological environment and climate. In this study, the MODIS annual product MCD12C1 is used as labels to classify the land cover of Landsat 8/9 images using the Random Forest method in order to obtain the dynamic distribution of dust source areas. The land cover results are processed to the WRF model to provide the meteorological field, after which a Lagrangian transport model FLEXPART-WRF is used to simulate the horizontal and vertical transport of particles from five dust source regions in East Asia during the March 22, 2023 dust storm event. The source apportionments for regions on the transmission path of different dust sources are revealed by an online tracer-tagged of air quality model NAQPMS. The results show that the total area of the East Asian dust source regions in March 2023 is 1.5×106 km2. Cold high pressure from Siberia and the Mongolian cyclone are key synoptic situations for dust emission and transport from dust source areas. The Taklimakan Desert and the Tarim Basin mainly affect northwestern China. The Badain Jaran Desert and Horqin Sandy Land have a greater impact on northern China, with longer transmission distances, and can even affect southeast and Northeast China. The Gobi Desert affects northern China by influencing the dust source areas in Inner Mongolia. The vertical transport height is up to 500m from the ground. The PM2.5 source apportionments show that the Badain Jaran Desert contribution of Beijing-Tianjin-Hebei and its surrounding areas accounted for 45.5 %, while the Gobi Desert accounted for 1.4 %.

How to cite: Li, Y. and Wu, Q.: How dust sources affect downstream regions in East Asia during a dust storm event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3981, https://doi.org/10.5194/egusphere-egu24-3981, 2024.

EGU24-4003 | ECS | PICO | AS3.9

New insights into the atmospheric dust dynamics in the Carpathian and Wallachian Basin during MIS 1-MIS 2 

Zoran Perić, Helena Alexanderson, Slobodan Marković, Milica Radaković, Petar Krsmanović, and Cathal Ryan

Fine-grained windblown deposits, known as loess, in which fossil soils (palaeosols) are preserved, serve as excellent records of past climate. However, paleoclimate reconstruction studies on loess-palaeosol sequences (LPS) in Southeastern Europe have primarily focused on climate changes during the last one or two glacial-interglacial cycles. Surprisingly, little attention has been given to the climate of the current interglacial, the Holocene. This oversight may be attributed to the prevailing notion that, based on ice core and marine isotope records, the Holocene is considered a climatically stable period. Additionally, the scarcity of LPS with well-preserved Holocene loess has contributed to this lack of attention until now. Three recently discovered loess-palaeosol sequences in the Eastern Carpathian and the Wallachian Basins present fully preserved loess covering MIS 1-MIS 2 offering the potential to unveil new and detailed information about Holocene climate. In this study, we present initial results from two of these LPS: Kisiljevo (44°44′0'' N and 21°25′0'' E) in the Carpathian Basin, and Velika Vrbica (44°35’1.70’’N, 22°43’15.97’’E) in the Wallachian Basin. For both sequences, detailed optically stimulated luminescence (OSL) chronologies using 63-90 µm quartz have been constructed. Age models based on the OSL ages were constructed using the r.bacon software (Blaauw & Christen, 2011), following which dust accumulation rates (MAR) for the last approximately 30,000 years were calculated. The initial results from Kisiljevo reveal a significant loess accumulation during the Holocene, amounting to approximately 120 cm. The highest MARs were observed between 10 and 12 ka (10,000-8,000 BC) with a mean value of 148 g m2 a-1. A similar trend is evident at the Velika Vrbica LPS, where the average calculated MARs during the early Holocene (8 – 11.7 ka) were 189 g m2 a-1, showing a decreasing trend toward the later part of this period (3.1 – 8 ka) with average values reaching 132.1 m2 a-1. Interestingly, at this site, the mean MARs during Marine Isotope Stage 1 (MIS) were higher than during the cold, stadial MIS 2, where the recorded values averaged 177 g m2 a-1. These initial results suggest that the Holocene dust dynamics in this region was more variable than what generally accepted models suggest.

References: Blaauw & Christen (2011). Flexible paleoclimate age-depth models using an autoregressive gamma process. Bayesian Analysis, 6(3), 457–474.

How to cite: Perić, Z., Alexanderson, H., Marković, S., Radaković, M., Krsmanović, P., and Ryan, C.: New insights into the atmospheric dust dynamics in the Carpathian and Wallachian Basin during MIS 1-MIS 2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4003, https://doi.org/10.5194/egusphere-egu24-4003, 2024.

Colour is a fundamental morphological feature commonly documented during the description of loess layers and soils developed on loesses – both contemporary and fossil. These colours are typically identified directly in the field, matching specific hues from the Munsell Soil Colour Chart. However, this method is highly subjective, with accuracy hinging on the observer's expertise and weather conditions. Introducing digital spectrometers for colour analysis, conducted in the lab on powdered samples, enhances objectivity. This approach was applied to samples from the Middle-Upper Pleistocene loess-palaeosol sequences (L2-S1-L1-S0) in Ukraine's Dnieper basin.

The laboratory work aimed to pinpoint chromatic parameters that typify each loess layer, considering their distinct features and stratigraphic positions, as well as various soil horizons, each with unique degrees of pedogenic alteration. Key colour metrics included lightness (L*), redness (a*), yellowness (b*), chroma (c*), and the R-index. The resultant database of spectrophotometric data helps identify colour patterns characteristic of different sequence components.

Our analysis revealed considerable variation across all measured parameters, yet maintained the distinct coloration typical of loess and soils. We also created a digital colour record corresponding with the analogue Munsell scale, lending further objectivity to colour descriptions. Notably, digital colour identification often markedly differs from traditional, "analogue" methods. Applying RGB tuning, we devised models that realistically replicate colours observed in the field.

The documented chromatic parameters enable geological profile analysis in both vertical and spatial dimensions – following the Dnieper valley's sub-meridian and sub-latitudinal orientations across the river basin. These colour profiles mirror the diverse litho-, pedo-, and diagenetic processes across different genetic stages. Crucially, we identified diagnostic colour characteristics unique to primary loesses (L2 vs. L1), various soil types, their development stages (full-profile vs. reduced), and preservation forms (modern vs. ancient).

Thanks to the high resolution and sensitivity of our spectrophotometric analysis, we detected nuanced chromatic shifts, often abrupt. This revealed otherwise invisible erosional surfaces and concealed boundaries, shedding light on changes in loess lithology or the progression of pedogenic processes. The documented colour shifts illustrate the dynamic evolution of the natural environment, from loess accumulation (cold phases) to soil formation (warm periods).

It should be noted that primary loesses of varying ages, collected from different geological sites, which are primarily described as light yellow, show significant differences in the L*, a*, b*, c* parameters in light of spectrophotometric analyses. This variability aligns well with the findings of geochemical analyses.

Research carried out as part of the grant of National Science Centre, Poland as the project no. 2018/31/B/ST10/01507 entitled “Global, regional and local factors determining the palaeoclimatic and palaeoenvironmental record in the Ukrainian loess-soil sequences along the Dnieper River Valley - from the proximal areas to the distal periglacial zone”.

How to cite: Mroczek, P., Łanczont, M., and Komar, M.: Loess chromaticity as an environmental change recorder: spectrophotometric study of aeolian dust and its role in paleoclimate studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4619, https://doi.org/10.5194/egusphere-egu24-4619, 2024.

EGU24-4749 | PICO | AS3.9 | Highlight

Recent developments in dust electrification research  

Keri Nicoll and R. Giles Harrison

Electrification of dust in the atmosphere is abundant, observed by helicopter blades glowing from corona discharge in dusty environments, and sparks from barbed wire fences during the US Dust Bowl.  Electrification of particles in blowing sand, dust devils and dust storms can result from contact charging/triboelectrification during dust generation or through its atmospheric transport, causing particles to accumulate large amounts of charge on their surface.  Strong electrostatic forces can affect the lofting of dust particles from the ground, as well as the transport of dust particles, however the details of such effects are still largely unexplored.  The charging of dust particles, and separation of the charge by mechanical processes yields large electric fields (E-fields, up to tens of kV m1).  Satellite remote sensing of dust is based on measurements of electromagnetic wave propagation, which can be attenuated by large electric fields, thereby the accuracy of dust measurements can be affected by electric fields arising from charge separation in dusty environments. Such E-fields are also expected to alter the orientation of dust particles, changing the effective optical depth of dust layers, existing calculations for which assume randomly oriented particles.

Although the existence of dust electrification has been known about for over a century, the details of the electrification mechanisms, and impact of dust electrification on particle behaviour are not yet fully understood.  This is partly due to a lack of observations of coincident space charge, E-field and particle measurements in dusty regions, particularly at altitudes above the surface.  This presentation will discuss recent research in understanding dust electrification processes, including surface observations of dust electrification in the United Arab Emirates (UAE), and measurements of charge in high altitude dust layers above the surface.

How to cite: Nicoll, K. and Harrison, R. G.: Recent developments in dust electrification research , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4749, https://doi.org/10.5194/egusphere-egu24-4749, 2024.

EGU24-4799 | ECS | PICO | AS3.9

Modeling the Mercury Cycle in the Sea Ice Environment: A Buffer between the Polar Atmosphere and Ocean 

Shaojian Huang, Feiyue Wang, Tengfei Yuan, Zhengcheng Song, Peipei Wu, and Yanxu Zhang

Sea ice (including overlying snow) is a dynamic interface between the atmosphere and the ocean, influencing the mercury (Hg) cycling in polar oceans. However, a large-scale and process-based model for the Hg cycle in the sea ice environment is lacking, hampering our understanding of regional Hg budget and critical processes. Here, we develop a comprehensive model for the Hg cycle at the ocean–sea ice–atmosphere interface with constraints from observational polar cryospheric data. We find that seasonal patterns of average total Hg (THg) in snow are governed by snow thermodynamics and deposition, peaking in springtime (Arctic: 5.9 ng/L; Antarctic: 5.3 ng/L) and minimizing during ice formation (Arctic: 1.0 ng/L, Antarctic: 0.5 ng/L). Arctic and Antarctic sea ice exhibited THg concentration peaks in summer (0.25 ng/L) and spring (0.28 ng/L), respectively, governed by different snow Hg transmission pathways. Antarctic snow-ice formation facilitates Hg transfer to sea ice during spring, while in the Arctic, snow Hg is primarily moved through snowmelt. Overall, first-year sea ice acts as a buffer, receiving atmospheric Hg during ice growth and releasing it to the ocean in summer, influencing polar atmospheric and seawater Hg concentrations. Our model can assess climate change effects on polar Hg cycles and evaluate the Minamata Convention’s effectiveness for Arctic populations.

How to cite: Huang, S., Wang, F., Yuan, T., Song, Z., Wu, P., and Zhang, Y.: Modeling the Mercury Cycle in the Sea Ice Environment: A Buffer between the Polar Atmosphere and Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4799, https://doi.org/10.5194/egusphere-egu24-4799, 2024.

EGU24-5430 | PICO | AS3.9

A near-global multiyear climate data record of the fine-mode and coarse-mode components of atmospheric pure-dust 

Emmanouil Proestakis, Antonis Gkikas, Thanasis Georgiou, Anna Kampouri, Eleni Drakaki, Claire L. Ryder, Franco Marenco, Eleni Marinou, and Vassilis Amiridis

Dust aerosols play a key role in the Earth’s radiation budget, in climate system, environmental conditions, and human health. However, the complex role of dust depends not only on the physical and chemical properties, but in addition to the particle size distribution, spanning from less than 0.1 μm to more than 100 μm in diameter. Larger mineral dust particles are more efficiently removed through dry deposition close to the source regions and act more efficiently as CCN and/or IN than fine-mode dust particles, whereas fine dust particles are more prominent to long-range transport, resulting to degradation of air-quality and induced negative disorders on human health.
Here, a new four-dimensional, multiyear, and near-global climate data record of the submicrometer and supermicrometer (in terms of diameter) components of atmospheric pure-dust, is presented. The separation of the two modes of dust is based on a combination of (1) the total pure-dust product provided by the ESA-LIVAS database and (2) the supermicrometer-mode component of pure-dust provided by the first-step of the two-step POLIPHON technique, developed in the framework of EARLINET. The submicrometer-mode component of pure-dust is extracted as the residual between the LIVAS total pure-dust and the supermicrometer-mode component of pure-dust. The decoupling scheme is applied to CALIPSO observations at 532nm. The final products consist of the submicrometer-mode and supermicrometer-mode of atmospheric pure-dust, of quality-assured profiles of backscatter coefficient at 532nm, extinction coefficient at 532nm, and mass concentration. The datasets are established primarily with the original L2 horizontal (5 km) and vertical (60 m) resolution of CALIOP along the CALIPSO orbit-path, and secondly in averaged profiles of seasonal-temporal resolution, 1o×1o spatial resolution, and with the original vertical resolution of CALIPSO, between 70oS and 70oN and covering more than 15-years of Earth Observation (06/2006-12/2021).
The climate data record is unique with respect to a wide range of potential applications, including climatological, time-series, and trend analysis over extensive geographical domains and temporal periods, validation of atmospheric dust models and reanalysis datasets, assimilation activities, and investigation of the role of airborne dust on radiation and air quality.

How to cite: Proestakis, E., Gkikas, A., Georgiou, T., Kampouri, A., Drakaki, E., Ryder, C. L., Marenco, F., Marinou, E., and Amiridis, V.: A near-global multiyear climate data record of the fine-mode and coarse-mode components of atmospheric pure-dust, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5430, https://doi.org/10.5194/egusphere-egu24-5430, 2024.

EGU24-5573 | ECS | PICO | AS3.9

Stronger early-spring dust outbreaks across the Northern Hemispheric mid-latitudes in a warmer climate 

Yiting Wang, Yan Yu, Ji Nie, and Paul Ginoux

This research focuses on changes in early-spring dust emissions from Northern Hemispheric mid-latitudes, in the context of global warming. Our study was motivated by the abnormally early and strong dust storms across East Asia in March 2021 and March 2023. These two recent dust extremes opposed the decadal decline of East Asian dust activities. Past studies have attributed this dustiness decline to expanded vegetation cover and resultant weaker near-surface winds in April and May; while in March, dust source regions in the Northern Hemispheric mid-latitudes have been mainly covered by snow or frozen soil instead of vegetation. Inspired by the abnormally warm and snow-free conditions associated with both the 2021 and 2023 early-spring dust extremes, our study examines an alternative hypothesis on dust regimes over the Northern Hemispheric mid-latitudes: in a warmer climate, earlier snow melt may cause stronger early-spring dust outbreaks. Here, using multiple observational datasets and model simulations, we show a 10-35% increase in March dust emission across the East Asian, Central Asian and North American drylands, from the 1980s towards the end of the 21st century, bringing ~20% extra PM10 to Beijing and Denver. This hemispherical enhancement in early-spring dust emission is primarily caused by reduced snow cover in response to warming, and further promoted by dynamical coupling between snow, wind, and soil moisture changes. The increased amount of dust, a light absorbing aerosol, may in turn accelerate larger-scale snow melt when it deposits, thereby triggering positive feedbacks between snow melting, dust emission, and warming. Our findings call for adaptation to the anticipated stronger early-spring dust storms across the North Hemispheric mid-latitudes in the upcoming decades.

How to cite: Wang, Y., Yu, Y., Nie, J., and Ginoux, P.: Stronger early-spring dust outbreaks across the Northern Hemispheric mid-latitudes in a warmer climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5573, https://doi.org/10.5194/egusphere-egu24-5573, 2024.

EGU24-6384 | PICO | AS3.9

Trade-offs of simplified versus comprehensive representation of mineralogy when studying dust impacts on Earth’s climate systems 

Paul Ginoux, Qianqian Song, María Gonçalves Ageitos, Ron L. Miller, Vincenzo Obiso, and Carlos Pérez García-Pando

The intensity and direction of dust impacts on Earth’s climate systems depend on mineral composition. For example, the presence or absence of a few percent of iron oxides in dust will determine if dust is warming or cooling the atmosphere. Similarly, feldspar will enhance ice cloud formation, while acid gases in the atmosphere will react on the surface of dust calcite limiting acid rain. Still, most climate models use a simplified representation of dust mineralogy. They assume a fixed composition at emission which stays invariant during transport and removal. Such simplification assumes spatially and temporally constant physical and chemical properties of dust, and appears to provide satisfactory results when comparing some properties with observations. The trade-off is their lack of spatial gradients, which will fail to induce circulation, cloud and precipitation changes. The two reasons to omit mineral variations are the uncertainty of current atlases of soil mineral composition in arid regions, and, more practically, an improved runtime efficiency. The former reason is losing ground with the recent launch (July 2022) of a dedicated mission (NASA/JPL EMIT) to retrieve global soil mineralogy of dust sources at high spatial resolution.

While the EMIT science team is finalizing a satisfactory global map of mineral composition of dust sources, we analyzed the interaction of dust mineralogy on radiation and its impact on the fast temperature response using different representations of mineral composition from detailed and spatially varying to simplified and globally uniform, assuming different hematite contents and methods to calculate optical properties.  

Our results show that resolving dust mineralogy reduces dust absorption, and results in improved agreement with observation-based single scattering albedo (SSA), radiative fluxes from CERES (the Clouds and the Earth’s Radiant Energy System), and land surface temperature from CRU (Climatic Research Unit), compared to the baseline bulk dust model version. It also results in distinct radiative impacts on Earth’s climate over North Africa. From our 19-year simulation, we will show that it leads to a reduction of over 50% in net downward radiation at top of atmosphere (TOA) across the Sahara and an approximately 20% reduction over the Sahel. We will explain how the surface temperature response affects the monsoon flow from the Gulf of Guinea.

Interestingly, we find similar results by simply fixing the hematite content of dust to a globally uniform value of 0.9% by volume. We will discuss the underlying reasons for such results and show that they may be unrelated to the distribution of soil mineralogy. Still, an accurate representation of soil mineralogy is necessary to better understand dust impacts on the Earth’s climate systems.

How to cite: Ginoux, P., Song, Q., Gonçalves Ageitos, M., Miller, R. L., Obiso, V., and Pérez García-Pando, C.: Trade-offs of simplified versus comprehensive representation of mineralogy when studying dust impacts on Earth’s climate systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6384, https://doi.org/10.5194/egusphere-egu24-6384, 2024.

EGU24-7235 | ECS | PICO | AS3.9

Quantifying dust emission following wildfires on the global scale 

Xianglei Meng, Yan Yu, and Paul Ginoux

Wildfires can reduce vegetation cover and soil adhesivity, thus expanding bare grounds susceptible to wind erosion. Although in situ observations have confirmed dust emission following wildfires, a quantitative and mechanistic understanding of post-fire dust emissions is limited. Here, on the basis of satellite observations of active fires, aerosol abundance, vegetation cover and soil moisture from 2003 to 2020, we found that 91% and 54% of large wildfires are followed by reduced vegetation cover and enhanced dust emission, leaving intensive dust loadings for 1-25 days over normally dust-free regions. Furthermore, small wildfires, which naturally occur more widespread and frequently than large wildfires, lead to more considerable post-fire dust emissions, mostly global semi-arid regions. The occurrence and intensity of post-fire dust emission are regulated primarily by the extent of precedent wildfires and resultant vegetation anomalies, and modulated secondarily by pre-fire drought conditions. Despite the episodic nature of post-fire dust events, the amount of post-fire dust emission has shown an upward trend over the past two decades, especially over the Northern Hemispheric mid-latitudes, where droughts and wildfires are intensifying. These post-fire dust events impose greater socioeconomic and health impacts than dryland dust, due to the closer location of the former to populated areas. With an ongoing enhancement of extreme wildfires and concurrent droughts under global warming, our results emphasize the emerging importance of post-fire dust emissions on global and regional scales.

How to cite: Meng, X., Yu, Y., and Ginoux, P.: Quantifying dust emission following wildfires on the global scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7235, https://doi.org/10.5194/egusphere-egu24-7235, 2024.

EGU24-7871 | ECS | PICO | AS3.9

Wind erosion in Western Sahel : Quantifying the impact of land use and land management 

Paul-Alain Raynal, Caroline Pierre, Béatrice Marticorena, Jean-Louis Rajot, Abdourahmane Tall, Issa Faye, Diouma Cor Fall, Bineta Amar, Antoine Couedel, Gatien Falconnier, Jean-Alain Civil, Olivier Roupsard, and Sidy Sow

It is currently estimated that around 15% of the global mineral dust load comes from the Sahel. In this area, rainfed agriculture and livestock grazing play a crucial role in the livelihood of its rapidly growing population. Cropland is likely to be a main source of anthropogenic dust emissions in this region, as this land use type can favor wind erosion if land management deprives the soil of vegetation cover.

Yet, in situ measurements of wind erosion fluxes are scarce in the Sahel, and usually monitor only one type of land use and an associated land management (eg. whether or not to harvest crop residues, intercropping, etc.). Thus, there is room to improve the assessment of the Sahelian anthropogenic contribution to the global dust load, especially through a regional modelling approach relying on field measurements.

In this study, we combined in situ measurements from Sahelian Senegal with a modelling approach to estimate the effect of the main Sahelian land uses on wind erosion. Furthermore, we monitored contrasting land management per land use, representative of the last decades (1960-2020). Here we present the results for one groundnut field over two years (2020-2021), four different fallowed fields over one year (2022/2023), four millet fields over one year (2023/2024). All 1ha-plots were located near the town of Bambey in central Senegal (Groundnut Basin). The observations included sand-traps monitoring (for each 1ha-plot, 5 masts of 5 « Modified Wilson And Cooke » or MWAC sand traps each; collected every 2 weeks), meteorological data (e.g., wind and temperature profiles, and rainfall; at 5-minutes resolution) and vegetation monitoring (aboveground biomass, surface cover, height; weekly to monthly).

For each land use and land management, we estimated the aerodynamic surface roughness length and the wind friction velocity to simulate the horizontal flux of aeolian sediments using a dedicated model (the Dust Production Model – DPM). We then combined the wind erosion model (DPM) with vegetation models (STEP for fallows and STICS for crops) to simulate the vegetation growth and the associated horizontal flux of aeolian sediment. These simulations are compared to the in situ monitoring from the sand traps. Finally, we used ERA5 meteorological time series from the ECMWF to simulate the horizontal flux for the 1960–2020 period over a typical plot from the study area, for different realistic scenarios of land uses and land management.

Our study revealed the variability of wind erosion horizontal flux for the main Sahelian land use types (400 kg/m/yr for bare soil, 200 kg/m/yr for cropland, less than 10kg/m/yr for fallows), as well as slighter differences related to land management for a same land use. These results help to understand the link between wind erosion and agropastoral practices in Sahelian conditions over multi-decadal periods of time.

How to cite: Raynal, P.-A., Pierre, C., Marticorena, B., Rajot, J.-L., Tall, A., Faye, I., Fall, D. C., Amar, B., Couedel, A., Falconnier, G., Civil, J.-A., Roupsard, O., and Sow, S.: Wind erosion in Western Sahel : Quantifying the impact of land use and land management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7871, https://doi.org/10.5194/egusphere-egu24-7871, 2024.

EGU24-8628 | PICO | AS3.9 | Highlight

Impact of Saharan mineral dust layers on cloud formation and cloud properties 

Silke Gross, Martin Wirth, and Florian Ewald

Mineral dust contributes strongly to the global aerosol load. The largest source region of mineral dust is the Sahara. But mineral dust cannot be treated as a regional phenomenon. Once lifted in the air, it can be transported thousands of kilometers over several days. The main transport pathway spans over the Atlantic Ocean from Africa towards the Caribbean; with its peak season during the summer months. But transatlantic dust transport can also happen during wintertime, however with less frequency. In addition, the dust particles can be transported northward over the Mediterranean and Europe. In rare events, it can even reach the Arctic region. All the way during transport the dust layer has an impact on the Earth’s radiation budget, by direct interaction with the incoming and outgoing radiation by scattering and absorption, and by indirect interaction as dust can impact cloud formation and cloud properties.

To study long-range transported Saharan dust as well as the dust’s impact on cloud formation and properties, airborne lidar measurements with the WALES lidar system onboard the German research aircraft HALO have been performed over the western sub-tropical North-Atlantic Ocean during NARVAL-II in August 2016 and EUREC4A in January/February 2020. We observed dust transport during the summertime in the clearly separated and well-defined Saharan Air Layer (SAL) as well as during wintertime, when dust transport happens at lower altitudes and the SAL is less separated. In addition, we were also able to capture an event of dust long-range transport into the Arctic during the HALO-(AC)3 campaign in spring 2022. From our measurements we could show, that small amount of water vapor embedded in the SAL has a strong impact on the atmospheric stability and thus also impacts the formation and properties of clouds during long-range transport. Additionally, dust particles are known to act as ice nuclei and with that lead to ice formation at different environmental conditions, changing the ice cloud’s microphysical properties.

In our presentation we will give an overview of the performed WALES measurements. We use these measurements to study dust long-range transport and its impact on the atmospheric stability, cloud formation and cloud properties.

How to cite: Gross, S., Wirth, M., and Ewald, F.: Impact of Saharan mineral dust layers on cloud formation and cloud properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8628, https://doi.org/10.5194/egusphere-egu24-8628, 2024.

EGU24-8749 | ECS | PICO | AS3.9

Influence of aerosol deposition on snowpack evolution in simulations with the ORCHIDEE land surface model  

Sujith Krishnakumar, Samuel Albani, Martin Ménégoz, Catherine Ottlé, and Yves Balkanski

Simulating seasonal snow with state-of-the-art global general circulation models (GCMs) is still challenging. Snow provides fresh water to billions of people and plays an important role in the energy budget of the earth through albedo, which affects not only local but also remote and global climate/hydrological patterns. Therefore, changes in snow amount and length of the season are crucial when investigating climate variability.  One key aspect often overlooked in GCMs is the inclusion of Light Absorbing Particles (LAPs) in snow simulations. LAPs dramatically reduce snow albedo, particularly for visible solar radiation, leading to considerable implications for climate modeling. The intention is to lay the foundations for addressing the issues across different climate conditions through simulations, by adding the snow darkening effect to a multilayered intermediate complexity scheme within ORCHIDEE, the land surface model embedded in the IPSL Earth System Model.

LAPs are commonly deposited on the surface of fresh snow and progressively become embedded into deeper layers of the snowpack.  The LAP species taken into account include four log-normal modes of dust, soot, and organic carbons. These tracers allow for the movement of LAPs through different layers of the snowpack, adjusting with snow accumulation or melting. In order to simulate the movement of LAPs, ORCHIDEE has been enhanced with a tracer flow mechanism that carry LAPs from the top snow layer following deposition and move through various layers as snow thickens or flushes with meltwater flow. Our approach to snow albedo deviates from the default method in ORCHIDEE as a function of snow aging through an exponential decay function with dependence on the degree of water saturation and the occurrence of fresh snow deposition. Instead, it integrates the Warren and Wiscombe snow radiative transfer scheme with Kokhanovsky's single scatter properties of snow crystals and the optical properties of LAPs to compute the albedo of impure snow. This study conducted site-level offline ORCHIDEE simulations using observed atmospheric conditions and MERRA2 aerosol deposition data. The integration of LAPs and related processes has led to improved simulations of seasonal snow, achieving more realistic representations of snow albedo compared to pure snow. Our results also show that LAPs play an important role in determining the local snow season length.

How to cite: Krishnakumar, S., Albani, S., Ménégoz, M., Ottlé, C., and Balkanski, Y.: Influence of aerosol deposition on snowpack evolution in simulations with the ORCHIDEE land surface model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8749, https://doi.org/10.5194/egusphere-egu24-8749, 2024.

EGU24-8796 | PICO | AS3.9 | Highlight

Potential environmental impacts of natural and mining related dust in Greenland and Svalbard 

Jens Søndergaard, Christian Frigaard Rasmussen, Hanne Hvidtfeldt Christiansen, and Christian Juncher Jørgensen

Dispersion and deposition of mineral dust from natural or anthropogenic sources such as proglacial rivers, mines and haul roads can have both positive and negative effects on the environment, depending on the geochemical and mineralogical composition of the dust. Some elements in dust may act as nutrients for, for example, plants, lichens and soil communities, while other elements may act as pollutants with negative impacts on growth or reproduction or cause diseases in animals and plants.

To support the sustainable development of environmentally safe mining in sensitive Arctic land areas and reduce airborne environmental pollution, an improved understanding of processes leading to the dispersion of mineral dust in a changing Arctic is needed. This involves improved methods for monitoring dust emissions and dust deposition in a cold environment as well as analytical tools and methods to source trace and differentiate between natural and mining related dust. Accurate identification of individual dust sources subsequently makes it possible to mitigate emissions and target the regulation of mining activities towards these sources.

In this study, we present preliminary results from two new arctic dust monitoring stations in West Greenland and Svalbard. In Kangerlussuaq, West Greenland, mineral dust has been collected using a wide array of passive and active dust samplers, including a continuously operated high volume dust sampler at a weekly sampling frequency over 2022/2023. In Svalbard, mineral dust has been collected in Adventdalen using passive dust collectors in a transect along the haul road to the active coal mines. Samples have been collected on a weekly sampling frequency in the period September to November 2023 to investigate the temporal and spatial variations in dust deposition rates, as well as the impact of haul road traffic relative to the natural dust emissions and depositions.

How to cite: Søndergaard, J., Frigaard Rasmussen, C., Hvidtfeldt Christiansen, H., and Juncher Jørgensen, C.: Potential environmental impacts of natural and mining related dust in Greenland and Svalbard, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8796, https://doi.org/10.5194/egusphere-egu24-8796, 2024.

EGU24-9570 | ECS | PICO | AS3.9

On the importance of Mongolian cyclones to East Asian dust storm activities 

Feifei Mu and Stephanie Fiedler

Desert-dust aerosols affect the climate, human health, and socio-ecomomic activities. In East Asia, the passage of Mongolian cyclones induce dust-emitting winds in the Gobi Desert. While cyclones are known as driver of dust outbreaks, the relative contribution of Mongolian cyclones to the total East Asian dust emission amount and the dust aerosol optical depth has not been quantified from a climatological perspective. To address this gap in knowledge, the present study systematically assesses the co-occurrence of Mongolian cyclones and dust aerosols in East Asia for 2001 to 2022. This study pairs output of the automated detection algorithm for extra-tropical cyclones in ERA5 re-analysis from the ETH Zürich with data for dust aerosols from multiple sources. Through the use of multiple dust data sets, we account for the substantial data uncertainty for dust aerosols in term of the spatial pattern and the absolute emission magnitudes, which can differ by an order of magnitude. The climatological analysis shows a high frequency and intensity for the occurrence of Mongolian cyclones in the lee of the Altai-Sayan Mountains (100Eo–125Eo and 37No–53No), favouring the seasonal dust activity in the Gobi Desert. The results highlight a tight constraint on the mean Mongolian cyclone contribution to the total dust emission amount of 39-47% in the spatial mean for spring based on data from MERRA-2 and Wu et. al. (2022), despite substantial differences in the absolute emission magnitudes. The dust-laden air from the Gobi Desert during such events typically moves southeastwards over China in the wake of the cyclones affecting the aerosol optical depth. For southern Mongolia and Northeastern China (105Eo–130Eo and 37No–52No), we estimate 34% (MERRA-2) to 43% (CAMS) of the dust aerosol optical depth (DOD) being associated with Mongolian cyclones. A decrease in dust emission fluxes and dust storm frequencies have been reported for Northern China in the past two decades and is thought to be connected to decreasing near-surface winds. Our results point to a negative trend in the dust emission flux and DOD associated with the occurrence of Mongolian cyclones. However, our results also point to the co-occurrence of particularly intense Mongolian cyclones, measured by the 99th percentile of the wind speed, with exceptionally strong dust storms in recent years, e.g., in March 2021, despite a mean negative trend in dust activity. Given the connection of Mongolian cyclone to high-impact dust storms in East Asia, the potential future development of such events should be addressed in future research.

How to cite: Mu, F. and Fiedler, S.: On the importance of Mongolian cyclones to East Asian dust storm activities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9570, https://doi.org/10.5194/egusphere-egu24-9570, 2024.

Water-soluble organic carbon (WSOC) and its brown carbon (BrC) components in the cryosphere have significant impact on the biogeochemistry cycling and snow/ice surface energy balance. In this study, snow samples were collected across regional area of northern Xinjiang, China to investigate the chemical composition, optical properties, and radiative forcing (RF) of WSOC. Based on the geographic differences and proximity of emission sources, the sampling sites were grouped as urban (U), remote (R), and soil-influenced (S) sites, for which WSOC concentrations were measured as 1968±953 ng g-1 (U), 885±328 ng g-1 (R), and 2082±1438 ng g-1 (S), respectively. The S sites showed the higher mass absorption coefficients at 365 nm (MAC365) of 0.94±0.31 m2 g-1 compared to those of U and R sites (0.39±0.11 m2 g-1 and 0.38±0.12 m2 g-1, respectively). Molecular-level characterization of WSOC using high-resolution mass spectrometry (HRMS) provided further insights into chemical differences among samples. Specifically, much more reduced S-containing species with high degree of unsaturation and aromaticity were identified in U samples, suggesting an anthropogenic source. Aliphatic/proteins-like species showed highest contribution in R samples, indicating their biogenic origin. The WSOC components from S samples showed high oxygenation and saturation levels. The WSOC-induced RF were estimated as 0.04 to 0.59 W m-2, which contribute up to 16% of that caused by BC, demonstrating the important influences of WSOC on the snow energy budget. Furthermore, the molecular composition and light-absorbing properties of BrC chromophores were unraveled by application of a high-performance liquid chromatography (HPLC) coupled to photodiode array (PDA) detector and HRMS. The chromophores were classified into five major types, i.e., (1) phenolic/lignin-derived compounds, (2) flavonoids, (3) nitroaromatics, (4) oxygenated aromatics, and (5) other chromophores. Identified chromophores account for ~23% – 64% of the total light absorption measured by the PDA detector in the wavelengths of 300 – 370 nm. In the representative U and R samples, oxygenated aromatics and nitroaromatics dominate the total absorbance. Phenolic/lignin-derived compounds are the most light-absorbing species in the S sample. Chromophores in two remote samples exhibit ultraviolet-visible features distinct from other samples, which are attributed to flavonoids. Identification of individual chromophores and quantitative analysis of their optical properties are helpful for elucidating the roles of BrC in snow radiative balance and photochemistry.

How to cite: Zhou, Y., Wang, X., and Laskin, A.: Molecular composition, optical properties, and radiative forcing of water-soluble brown carbon in seasonal snow samples from northern Xinjiang, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9995, https://doi.org/10.5194/egusphere-egu24-9995, 2024.

EGU24-10547 | ECS | PICO | AS3.9

Development of a dusty cirrus calendar based on satellite data 

Samaneh Moradikian, Sanaz Moghim, and Gholam Ali Hoshyaripour

Mineral dust particles have the potential to serve as natural nuclei for cirrus cloud formation in the upper troposphere. Several studies demonstrate that dust aerosol plays a pivotal role in initiating cirrus clouds and forming extended optically thick cirrocumulus decks known as “dusty cirrus”. Despite this, our ability to accurately identify and predict these climatically significant clouds is still limited. In this work, we propose an algorithm to identify dusty cirrus clouds based on satellite data over the Aral Sea region between 2006 and 2021. The algorithm uses the CALIOP Vertical Feature Mask (VFM) to verify the coexistence of dust particles and cirrus clouds and determine the occurrence of dusty-cirrus. To enhance the accuracy of the algorithm, temperature obtained from an external source (the GEOS-5 data product supplied to CALIPSO) is also incorporated as a constraint for cirrus cloud identification. A random selection of identified dusty cirrus events (5% of the data, 90 events) is cross-validated against other data sources including cloud top temperature (MODIS), cloud top height (MODIS), and AOD (MODIS and VIIRS). The cross-validation confirms approximately 97% of the events to be associated with dusty-cirrus. This confirms that the developed algorithm can be used for developing a dusty cirrus calendar using available CALIOP data. This calendar reveals different facts about the dusty-cirrus occurrence in the study area. Out of the 4407 available samples, 2709 cirrus cloud events are identified, with approximately 65% (1790 events) of them being associated with dusty cirrus. The average values obtained for summer, fall, winter, and spring are 54%, 63%, 66% and 75%, respectively. Annual and seasonal trend analysis reveals different increasing rates for this region. Despite the important uncertainties, our analysis and results suggest that the proposed algorithm can be used for first-order identification and statistical analysis of dusty cirrus.

How to cite: Moradikian, S., Moghim, S., and Hoshyaripour, G. A.: Development of a dusty cirrus calendar based on satellite data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10547, https://doi.org/10.5194/egusphere-egu24-10547, 2024.

EGU24-11462 | ECS | PICO | AS3.9

Seasonal effects of wind-blown dust emissions on size-resolved aerosol acidity over the U.S 

Stylianos Kakavas, Evangelia Siouti, Athanasios Nenes, and Spyros Pandis

Wind-blown dust emitted by the Earth’s surface is one of the major sources of dust emissions especially in non-vegetated areas like deserts and can affect both climate and human health. Acidity is an important property of atmospheric aerosols impacting a series of related processes and can be affected by these emissions of alkaline dust. In this work, we use a wind-blown dust emissions model to quantify the wind-blown dust emissions over the continental United States during February and July 2017. The modeling domain covers a region of 4752 × 2952 km2 including northern Mexico and southern Canada with a horizontal grid resolution of 36 × 36 km. Then, the hybrid version of aerosol dynamics in PMCAMx (Particulate Matter Comprehensive Air-quality Model with Extensions) chemical transport model is used to simulate size-resolved aerosol acidity. In this version of PMCAMx for fine (PM1) particles, bulk equilibrium is assumed, while for larger particles a dynamic model is used to simulate the mass transfer to each size section. Two cases of simulations are performed. The first is the base case simulation and includes the wind-blown dust emissions for both months. The second one neglects these emissions in order to study their effects on aerosol acidity during a wintertime and a summertime period as a function of particle size and altitude.

How to cite: Kakavas, S., Siouti, E., Nenes, A., and Pandis, S.: Seasonal effects of wind-blown dust emissions on size-resolved aerosol acidity over the U.S, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11462, https://doi.org/10.5194/egusphere-egu24-11462, 2024.

EGU24-11544 | ECS | PICO | AS3.9

Abundance of giant mineral dust particles: Insights from measured emitted dust size distributions during the J-WADI campaign 

Hannah Meyer, Andres Alastuey, Sylvain Dupont, Vicken Etyemezian, Jessica Girdwood, Cristina González-Flórez, Adolfo González-Romero, Tareq Hussein, Mark Irvine, Konrad Kandler, Peter Knippertz, Ottmar Möhler, George Nikolich, Xavier Querol, Chris Stopford, Franziska Vogel, Frederik Weis, Andreas Wieser, Carlos Pérez García-Pando, and Martina Klose

Gaining a precise understanding of the particle size distribution (PSD) of mineral dust at emission is critical to assess its climate impacts. Despite its importance, comprehensive measurements at dust sources remain scarce and usually neglect part of the super-coarse (particle diameter d between 10 and 62.5 μm) and the entire giant (d > 62.5 μm) particle size ranges. Measurements in those size ranges are particularly challenging due to expected relatively low number concentrations and low sampling efficiencies of instrument inlets.

This study aims to better constrain the abundance of super-coarse and giant dust at emission as part of the Jordan Wind erosion And Dust Investigation (J-WADI, https://www.imk-tro.kit.edu/11800.php) field campaign conducted north of Wadi Rum in Jordan in September 2022. The goal of J-WADI is to improve our fundamental understanding of the emission of desert dust, in particular its full-range size distribution and mineralogical composition.

To capture the dust PSD across the entire size spectrum, we deployed multiple aerosol spectrometers, including active, passive, and open-path devices, such that in combination, a size range from approximately 0.4 to 200 μm was covered. Here we investigate the variability of the PSD in the super-coarse and giant ranges from observed dust events, address instrumental uncertainties and the impact of different inlets on the resulting PSDs. Our preliminary results reveal a mass concentration peak at around 30 μm, potentially limited toward larger sizes by substantially reduced inlet efficiencies. Giant dust particles were generally detected during active dust emission starting from friction velocities larger than around 0.2 m s-1.

Based on our results, we will investigate the mechanisms facilitating super-coarse and giant dust particle emission and transport. Quantifying the conditions for and the amount of super-coarse and giant dust at emission will lay the foundation to incorporate its impacts in weather and climate models.

How to cite: Meyer, H., Alastuey, A., Dupont, S., Etyemezian, V., Girdwood, J., González-Flórez, C., González-Romero, A., Hussein, T., Irvine, M., Kandler, K., Knippertz, P., Möhler, O., Nikolich, G., Querol, X., Stopford, C., Vogel, F., Weis, F., Wieser, A., Pérez García-Pando, C., and Klose, M.: Abundance of giant mineral dust particles: Insights from measured emitted dust size distributions during the J-WADI campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11544, https://doi.org/10.5194/egusphere-egu24-11544, 2024.

EGU24-12203 | ECS | PICO | AS3.9

Black Carbon and Dust in the snow of Chilean Central Andes: From albedo reductions to radiative forcing 

Maria Florencia Ruggeri, Ximena Fadic, Gonzalo Barcaza, and Francisco Cereceda-Balic

The cryosphere, a vital component of the Earth's climate system, holds substantial importance in both the hydrological cycle and the energy balance. Current apprehension turns around alterations in the cryosphere linked to the reduction in Surface Snow Albedo (SSA).

The decrease in SSA is primarily attributed to the presence of light-absorbing particles (LAPs) and the growth of snow grain size (SGS). The quantitative assessment of these SSA reductions' climatic impact is reflected through their Radiative Forcing (RF), indicating the change they induce in the net radiative flux at the tropopause or the top of the atmosphere. LAPs, mainly composed of Black Carbon (BC) and Mineral Dust (MD), contribute to albedo reduction at visible wavelengths. BC originates from the incomplete combustion of fossil fuels and biomass, while MD primarily emanates from arid and semi-arid regions with low vegetation cover. Precise RF calculations resulting from SSA reductions gain significance, particularly in regions where snow cover governs freshwater availability. Chile exemplifies such a concern, possessing the largest portion of the Andean cryosphere, highly responsive to climate change. This has significant implications for water resources, impacting freshwater availability for Chile's residents and key economic activities.

To quantify the Radiative Forcing RF generated by LAPs in the Chilean Central Andes, snow samples were collected at Portillo, from 2017 to 2022. NUNATAK-1 is a portable, flexible, collaborative scientific platform belonging to the Centre for Environmental Technologies (CETAM-UTFSM), specially designed for research campaigns under extreme conditions, equipped with different automatic and real-time monitoring instruments to measure meteorology, net albedo, solar radiation, gases and aerosols, among others. The samples underwent analysis to determine BC and MD concentrations, following the methodologies outlined in Cereceda-Balic et al. (2022). Snow albedo was modeled using the SNow, ICe, and Aerosol Radiation (SNICAR). Evaluating the singular and combined effects of LAPs, snow albedo was simulated for four scenarios: clean snow (without LAPs), BC only, dust only, and BC + dust. RF represents the variance in absorption between LAP-influenced scenarios and clean snow. For RF calculation, measured solar irradiance specific to each sampling date at the designated site was used. BC concentrations ranged from 2.6 to 717.2 ng g-1, while MD concentrations varied between 1.6 and 181.3 mg kg-1, leading to SSA reductions of up to 21% relative to clean snow. Notably, it was observed that the absorption produced by BC and MD could be comparable, underscoring the significant role of MD in this semiarid location. Moreover, even with relatively moderate or low LAP concentrations in the snow, substantial RF values are generated, emphasizing the heightened climatic influence of LAPs in the region.

Acknowledgments: ANID-Fondecyt Projects 11220525 and 1221526, ANID ANILLO ACT210021, FOVI 230167.

How to cite: Ruggeri, M. F., Fadic, X., Barcaza, G., and Cereceda-Balic, F.: Black Carbon and Dust in the snow of Chilean Central Andes: From albedo reductions to radiative forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12203, https://doi.org/10.5194/egusphere-egu24-12203, 2024.

EGU24-12289 | ECS | PICO | AS3.9

Image-based nowcasting of dust storms by predicting SEVIRI desert dust RGB composites 

Kilian Hermes, John Marsham, Martina Klose, Franco Marenco, Melissa Brooks, and Massimo Bollasina

Dust storms are frequent high-impact weather phenomena that directly impact human life, e.g., by disrupting land and air traffic, posing health threats, and affecting energy delivery from solar-energy systems. Timely and precise prediction of these phenomena is crucial to mitigate negative impacts.

Currently operational numerical weather prediction (NWP) models struggle to reliably reproduce or resolve dynamics which lead to the formation of convective dust storms, making short-term forecasts based on observations (“nowcasts”) particularly valuable. Nowcasting can provide greater skill than NWP on short time-scales, can be frequently updated, and has the potential to predict phenomena that currently operational NWP models do not reproduce.  However, despite routine high frequency and high resolution observations from satellites, as of January 2024, no nowcast of dust storms is available.

In this study, we present an image-based nowcasting approach for dust storms using the SEVIRI desert dust RGB composite. We create nowcasts of this RGB composite for a large domain over North Africa by adapting established optical-flow-based methods as well as a machine learning approach based on a U-net. We show that our nowcasts can predict phenomena such as convectively generated dust storms (“haboobs”) which currently operational NWP may not reliably reproduce. Furthermore, we show that a machine learning model offers crucial advantages over optical-flow-based nowcasting tools for the application of predicting complete RGB images.

Our approach therefore provides a valuable tool that could be used in operational forecasting to improve the prediction of dust storms, and indeed other weather events. Due to the technical similarity of RGB composite imagery from geostationary satellites, this approach could also be adapted to nowcast other RGB composites, such as those for ash, or convective storms.

How to cite: Hermes, K., Marsham, J., Klose, M., Marenco, F., Brooks, M., and Bollasina, M.: Image-based nowcasting of dust storms by predicting SEVIRI desert dust RGB composites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12289, https://doi.org/10.5194/egusphere-egu24-12289, 2024.

Two billion tons of dust are annually transported in our atmosphere all around the world. High latitudes include active desert regions with at least 5 % production of the global atmospheric dust. Active High Latitude Dust (HLD) sources cover > 1,600,000 km2 and are located in both the Northern (Iceland, Alaska, Canada, Greenland, Svalbard, North Eurasia, and Scandinavia) and Southern (Antarctica, Patagonia, New Zealand) Hemispheres. Recent studies have shown that HLD travels several thousands of km inside the Arctic and > 3,500 km towards Europe. In Polar Regions, HLD was recognized as an important climate driver in the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate in 2019. In situ HLD measurements are sparse, but there is increasing number of research groups investigating HLD and its impacts on climate in terms of effects on cryosphere, cloud properties and marine environment.

Long-term dust in situ measurements conducted in Arctic deserts of Iceland and Antarctic deserts of Eastern Antarctic Peninsula in 2018-2023 revealed some of the most severe dust storms in terms of particulate matter (PM) concentrations. While one-minute PM10 concentrations is Iceland exceeded 50,000 ugm-3, hourly PM10 means in James Ross Island, Antarctica exceeded 300 ugm-3 in 2021-22. The largest HLD field campaign was organized in Iceland in 2021 where 11 international institutions with > 70 instruments and 12 m tower conducted dust measurements (Barcelona Supercomputing Centre, Darmstadt, Berlin and Karlsruhe Universities, NASA, Czech University of Life sciences, Agricultural University of Iceland etc.). Additionally, examples of aerosol measurements from Svalbard and Greenland will be shown. There are newly two online models (DREAM, SILAM) providing daily operational dust forecasts of HLD. DREAM is first operational dust forecast for Icelandic dust available at the World Meteorological Organization Sand/Dust Storm Warning Advisory and Assessment System (WMO SDS-WAS). SILAM from the Finnish Meteorological Institute provides HLD forecast for both circumpolar regions. 

Icelandic dust has impacts on atmosphere, cryosphere, marine and terrestrial environments. It decreases albedo of both glacial ice/snow similarly as Black Carbon,  as well as albedo of mixed phase clouds via reduction in supercooled water content. There is also an evidence that volcanic dust particles scavenge efficiently SO2 and NO2 to form sulphites/sulfates and nitrous acid. High concentrations of volcanic dust and Eyjafjallajokull ash were associated with up to 20% decline in ozone concentrations in 2010. In marine environment, Icelandic dust with high total Fe content (10-13 wt%) and the initial Fe solubility of 0.08-0.6%, can impact primary productivity and nitrogen fixation in the N Atlantic Ocean, leading to additional carbon uptake.

Sand and dust storms, including HLD, were identified as a hazard that affects 11 of the 17 Sustainable Development Goals. HLD research community is growing and Icelandic Aerosol and Dust Association (IceDust) has > 110 members from 57 institutions in 22 countries (https://icedustblog.wordpress.com, including references to this abstract). IceDust became new member aerosol association of the European Aerosol Assembly in 2022. New UArctic Thematic Network on HLD was established in 2023.   

How to cite: Dagsson Waldhauserova, P., Meinander, O., and members, I.: High Latitude Dust (HLD) measurements in Iceland, Antarctica, Svalbard, and Greenland, including HLD impacts on climate and HLD networking, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13103, https://doi.org/10.5194/egusphere-egu24-13103, 2024.

EGU24-13462 | ECS | PICO | AS3.9

Local anthropogenic factors contributing to constrasting glacier response in two mountain glaciers, located in Central Andes, Chile 

Felipe McCracken, María Florencia Ruggeri, Gonzalo Barcaza, Ximena Fadic, and Francisco Cereceda-Balic

Contrasting behaviour of neighbouring mountain glaciers, sharing similar mass balance gradients, have been observed, suggesting the influence of local anthropogenic factors altering the surface energy balance and then explaining larger down-wasting trends in glacier response. It is in this context that for this work the comparison of two contrasting glaciers was used to analyze these differences: considering the Paloma Norte Glacier (PNG), exposed to anthropogenic emissions from local mining activities, and the Yeso Glacier (YG), isolated of these sources. The objective of this research is to combine the remote analysis of light-absorbing particles, such as Black Carbon (BC), Organic Carbon (OC), as well as the estimation of area and albedo, together with the analysis of local climatic trends of each glacier according gridded data, in order to evaluate their differences and the influence of each of these parameters on the surface variation of each glacier.

We determined glacier shrinkage, interannual albedo reduction and black carbon estimates using satellite images over the last 22 years for the Paloma Norte and Yeso glaciers. The results show that in the range 2000-2022, the GPN experienced a 27.11% greater surface loss than the GY, 83.49% higher albedo change rates, and almost 23 times higher BC+OC concentrations compared to the GY. Furthermore, the multivariate regression analysis identified that the most influential parameters was BC-OC, which is consistent with the disparities in glacial retreat observed in this period.

These results are part of an ongoing research, where, in addition, it is intended to contrast these values with measured data at ground stations, where we will use the data from NUNATAK-1 (-32,844, -70,129) and 2 (- 33,665, -70,086) refuge laboratories in the Central Andes. NUNATAK-1 is a portable, flexible, collaborative scientific platform belonging to CETAM, specially designed for research campaigns under extreme conditions equipped with different automatic and real-time monitoring instruments to measure meteorology, net albedo, solar radiation, gases and aerosols, among others. Which are parameters that will also be used to compare with glacial ablation and radiative transfer models, to evaluate the scenarios of albedo change under a pristine environment and another under the scenario of aerosol deposition on the surfaces of the glaciers of interest. All the above mentioned is being carried out to determine to whether these differences are purely due to the orientation of each glacier or the local anthropogenic influence to which they are exposed, and thus decouple the natural effect of climate change from the local anthropogenic effect.

In summary, the results of this work will aim to guide decision-makers, to guarantee greater protection and awareness of the effects that local emissions may (or may not) have on the conservation of these important reservoirs of drinking water, which will allow for a decoupling of the influence and/or impact of local anthropogenic activity from the natural effect of climate change.

Acknowledgments: This research has been carried out with the financial support of CETAM-UTFSM, and the ANID projects: Fondecyt Initiation 11220525, Fondecyt Regular N° 1221526, ANID Anillo ACONCAGUA Project N°ACT210021 and FOVI230167.

How to cite: McCracken, F., Ruggeri, M. F., Barcaza, G., Fadic, X., and Cereceda-Balic, F.: Local anthropogenic factors contributing to constrasting glacier response in two mountain glaciers, located in Central Andes, Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13462, https://doi.org/10.5194/egusphere-egu24-13462, 2024.

EGU24-14539 | ECS | PICO | AS3.9

Exploring the effects of mineral dust acidification on oxidative potential and limiting nutrient solubility 

Andrea Baccarini, Carolina Molina, Christos Kaltsonoudis, Katerina Seitanide, Maria Georgopoulou, Ali Waseem, Georgia Argyropoulou, Adolfo Gonzalez-Romero, Xavier Querol, Carlos Pérez García-Pando, Dimitrios Papoulis, Satoshi Takahama, Kalliopi Violaki, Spyros N. Pandis, and Athanasios Nenes

Mineral dust aerosol particles are ubiquitous in the atmosphere; they contribute to more than half of the total atmospheric aerosol burden and have far-reaching impacts on biogeochemical cycles, air quality and Earth’s radiative budget. Much of the impact of dust is linked to its mild alkalinity and metal content, which directly influence atmospheric reactivity. However, metals and other trace nutrients (TN), such as phosphorous, are largely insoluble in freshly emitted dust and exhibit limited bioavailability for ecosystems upon deposition. The same metals can induce considerable oxidative stress upon inhalation, but mostly if in soluble form. Previous studies have found that atmospheric processing and, in particular, acidification of dust (caused by reactions with sulfuric, nitric, hydrochloric and organic acids) can promote TN solubility and increase the adverse health effects of population exposure to dust. Atmospheric processing also influences dust hygroscopicity and cloud-forming ability, directly affecting Earth’s radiative budget and deposition patterns.

Previous experiments investigating the effect of atmospheric processing on mineral dust properties were mainly conducted in bulk materials and samples. The dissolution kinetics of metals and TN remains poorly constrained under real atmospheric conditions. To address this issue, we have developed an atmospheric simulation chamber facility where mineral dust particles from a wide range of soils can be generated and aged by any mechanisms relevant to the atmosphere (e.g., acidification through photooxidation and/or nocturnal chemistry).

This study provides a detailed characterization of the chamber facility and explores how acidification alters the properties of mineral dust. In particular, we examine the effect of nitrate and sulfate aging on the solubility of TN and the oxidative potential (measured with a DTT assay) of the dust, under atmospherically relevant conditions. We conclude by relating these findings to field observations and discussing the implications for biogeochemical cycles and air quality.

How to cite: Baccarini, A., Molina, C., Kaltsonoudis, C., Seitanide, K., Georgopoulou, M., Waseem, A., Argyropoulou, G., Gonzalez-Romero, A., Querol, X., Pérez García-Pando, C., Papoulis, D., Takahama, S., Violaki, K., N. Pandis, S., and Nenes, A.: Exploring the effects of mineral dust acidification on oxidative potential and limiting nutrient solubility, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14539, https://doi.org/10.5194/egusphere-egu24-14539, 2024.

EGU24-16299 | PICO | AS3.9 | Highlight

Diverse and high pollution of microplastics in seasonal snow across Northeastern China 

Xin Wang and Hanxuan Wen

Snow scavenging is recognized as one of the major sinks for atmospheric microplastics (MPs). However, little is known about the properties of MPs in large-scale surface snow. Using Nile Red staining and micro-Fourier transform infrared spectroscopy, we identified the shapes, sizes, and polymer components of MPs in seasonal snow across northeastern (NE) China, a major industrial area. The average concentration of MPs was (4.52 ± 3.05) × 104 MPs L−1 , and the highest contamination (6.65 ± 3.89) × 104 MPs L−1 was observed in Changbai Mountains, which was the highest concentration observed in surface snow to the extent of literature. The majority of snow MPs were smaller than 50 μm and composed primarily of fragments. Ethylene vinyl acetate and polyethylene were the dominant contributors to their chemical components. Investigation with positive matrix factorization revealed that the MPs were primarily generated by debris from packaging materials, followed by industrial and construction activities. In addition, the winter atmospheric circulation over the northwestern Siberian and Mongolian plateaus likely dominated the wide-range dispersion and deposition of the MPs across NE China. These results provide a first comprehensive perspective of MPs from sources to removal associated with snow in a large geographic region.

How to cite: Wang, X. and Wen, H.: Diverse and high pollution of microplastics in seasonal snow across Northeastern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16299, https://doi.org/10.5194/egusphere-egu24-16299, 2024.

EGU24-16833 | ECS | PICO | AS3.9

Cumulative and relative impact of aerosol species on snowmelt runoff from the Hindu Kush Himalayan glaciers 

Sauvik Santra, Shubha Verma, and Shubham Patel

Himalayan glaciers are a significant contributor to the global supply of snowmelt water and serve as the primary source for major rivers in South Asia. In this study, we have evaluated the effect of aerosol species on glaciers in the Hindu Kush Himalayan (HKH) region and identified the glaciers most affected, as well as the relative and cumulative impact of different aerosol species, including black carbon (BC). We estimate the surface concentration of organic carbon (OC), sulfate (Sul), and dust aerosols in the HKH region. We also measured the concentration of these aerosol species in the snow of nine glaciers and investigated their influence on annual glacier runoff. Furthermore, we identified the source regions and sectors that are responsible for aerosol loading in the region. In this study, we combined free-running (freesimu) and constrained (constrsimu) aerosol simulations with an atmospheric general circulation model, an aerosol-snow radiative interaction model, and a novel hypsometric glacier energy mass balance model. The freesimu estimates of aerosol species concentrations were more accurate at high-altitude (HA) stations than at low-altitude (LA) stations. However, the constrsimu estimates performed significantly better at LA stations. A hotspot location of high concentration of aerosol species was identified near Manora Peak, located almost at a central location in the HKH region. Although the concentration of other aerosol species was 2 to 5 times higher than BC (< 70 μg kg-1), they caused significantly less reduction in snow albedo than BC over the HKH glaciers. The cumulative snow albedo reduction (SAR) due to all aerosol species, including BC, was estimated to be as much as 7 to 8% over the Gangotri and Chorabari glaciers, with Gangotri being one of the most important glaciers responsible for the formation of the Ganges River. The Pindari glacier was found to have the highest annual runoff increase (ARI) of all glaciers studied despite having a lower aerosol-induced SAR than the Gangotri and Chorabari glaciers. Five of the nine glaciers (Pindari, Sankalpa, Milam, Gangotri, and Chorabari) had ARI higher than 300 mm w.e. y-1 due to aerosol-induced SAR. Glaciers located in the HKH region were found to be two to three times more sensitive to SAR than cold Tibetan glaciers. This, combined with the recent increase in temperature due to global warming, paints a worrying picture for the future. Analysis of the fractional contribution of aerosol species revealed that BC aerosols, although having a less than 15% contribution to the total aerosol loading, contribute 55 to 70% of total aerosol-induced ARI, followed by dust (20 to 30\%), Sul and OC aerosols respectively. Analysis of region- and source-tagged simulation data revealed that the main sources of OC and Sul aerosols south of 30°N were biomass burning and open burning (for OC), and fossil fuel burning (for Sul) from the nearby Indo-Gangetic plain. For regions located north of 30°N and for dust aerosols, the main contributor was identified as long-range intercontinental transport from far-off regions of Africa and West Asia.

How to cite: Santra, S., Verma, S., and Patel, S.: Cumulative and relative impact of aerosol species on snowmelt runoff from the Hindu Kush Himalayan glaciers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16833, https://doi.org/10.5194/egusphere-egu24-16833, 2024.

EGU24-16834 | ECS | PICO | AS3.9

Characterisation of algal blooms on seasonal snowfields through a combination of field spectrometry, drone imagery and radiative transfer modeling at Hardangerjøkulen (Hardanger glacier), Southern Norway 

Lou-Anne Chevrollier, Adrien Wehrlé, Joseph M. Cook, Alexandre M. Anesio, Liane G. Benning, and Martyn Tranter

Pigmented microalgae bloom on glaciers and snowfields worldwide, contributing to carbon storage and enhanced surface melt through surface darkening. The darkening impact of snow algal blooms is being increasingly studied on terrestrial glaciers and ice sheets but less attention has been given to seasonal snowfields, despite their ecological and climatic relevance. Algal blooms are typically widespread but heterogeneously distributed and therefore high resolution airborne observations provide important insights to better understand the spatial patterns and impact of the blooms. Here, we present 130 field spectra colocated with low-cost and light-weight drone imagery acquired over 6 different snowfields in July and August 2023 around Hardangerjøkulen (Hardanger glacier), Southern Norway. We combine these high-resolution measurements with radiative transfer modeling to provide estimates of abundance, carbon storage and albedo impact of snow algal blooms on seasonal snowfields.

How to cite: Chevrollier, L.-A., Wehrlé, A., M. Cook, J., M. Anesio, A., G. Benning, L., and Tranter, M.: Characterisation of algal blooms on seasonal snowfields through a combination of field spectrometry, drone imagery and radiative transfer modeling at Hardangerjøkulen (Hardanger glacier), Southern Norway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16834, https://doi.org/10.5194/egusphere-egu24-16834, 2024.

EGU24-17044 | PICO | AS3.9

Inaugural dust and climate model simulations with the new EMIT global mineral abundance maps 

María Gonçalves Ageitos and the EMIT team

Minerals in dust shape the interaction of this ubiquitous aerosol with relevant components of the Earth system. Iron oxides absorb short-wave radiation, while quartz or k-feldspars act as efficient ice nuclei, contributing to the formation of mixed-phase clouds. In addition, iron and phosphorus containing minerals transport nutrients to terrestrial and marine ecosystems. Other minerals, like calcite, affect aerosols’ pH and intervene in atmospheric chemistry processes. Incorporating these complex effects into Earth System Models (ESM) has proven challenging due to our limited knowledge about the mineralogy of dust sources and its particle size distribution at emission.

The ongoing NASA Earth Surface Mineral Dust Source investigation (EMIT) project has produced a first version of a global mineral abundance map at an unprecedented resolution based on spaceborne imaging spectroscopy observations from the International Space Station. Using this new product, we have conducted multi-annual simulations with several ESMs that explicitly represent dust mineralogy. Our study characterizes the relevance of the new map in the ESM results by comparison with our previous baseline simulations. We conduct a thorough evaluation against a global mineral fraction compilation derived from concentration and deposition measurements. Our results are also compared against single scattering albedo (SSA) retrievals from dusty AERONET sites. Our focus is primarily iron oxides, hematite and goethite, which, together with particle size, control the dust SSA in the short-wave.

By providing a first set of simulations with the new EMIT mineral abundance maps and their evaluation, our work contributes to advancing the representation of this key aerosol within ESMs and to further assessing its significance within the global climate system.

How to cite: Gonçalves Ageitos, M. and the EMIT team: Inaugural dust and climate model simulations with the new EMIT global mineral abundance maps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17044, https://doi.org/10.5194/egusphere-egu24-17044, 2024.

EGU24-17082 | PICO | AS3.9

Underestimation of desert dust ingested by aircraft from the CAMS reanalysis compared to CALIOP retrievals 

Claire Ryder, Clement Bezier, Helen Dacre, Rory Clarkson, Vassilis Amiridis, Eleni Marinou, Emmanouil Proestakis, Zak Kipling, Angela Benedetti, Mark Parrington, Samuel Remy, and Mark Vaughan

Atmospheric mineral dust aerosol constitutes a threat to aircraft engines from deterioration of internal components. Here we fulfil an outstanding need to quantify engine dust ingestion at worldwide airports.  The vertical distribution of dust is of key importance since ascent/descent rates and engine power both vary with altitude and affect dust ingestion. We use representative jet engine power profile information combined with vertically and seasonally varying dust concentrations to calculate the ‘dust dose’ ingested by an engine over a single ascent or descent. Using the Copernicus Atmosphere Monitoring Service (CAMS) model reanalysis, we calculate climatological and seasonal dust dose at 10 airports for 2003-2019. Dust doses are mostly largest in summer for descent, with the largest at Delhi (6.6 g). Beijing’s largest dose occurs in spring (2.9 g). Holding patterns at altitudes coincident with peak dust concentrations can lead to substantial quantities of dust ingestion, resulting in a larger dose than the take-off, climb and taxi phases. We compare dust dose calculated from CAMS to spaceborne lidar observations from two dust datasets derived from the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP). In general, seasonal and spatial patterns are similar between CAMS and CALIOP though large variations in dose magnitude are found, with CAMS producing lower doses by a mean factor of 2.4±0.5, particularly when peak dust concentration is very close to the surface. We show that mitigating action to reduce engine dust damage could be achieved, firstly by moving arrivals and departures to after sunset and secondly by altering the altitude of the holding pattern away from that of the local dust peak altitude, reducing dust dose by up to 44% or 41% respectively.

How to cite: Ryder, C., Bezier, C., Dacre, H., Clarkson, R., Amiridis, V., Marinou, E., Proestakis, E., Kipling, Z., Benedetti, A., Parrington, M., Remy, S., and Vaughan, M.: Underestimation of desert dust ingested by aircraft from the CAMS reanalysis compared to CALIOP retrievals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17082, https://doi.org/10.5194/egusphere-egu24-17082, 2024.

EGU24-17880 | PICO | AS3.9

Unveiling the provenance of dust in the EPICA Dronning Maud Land Ice Core (Antarctica) throughout the Last Deglaciation (7–27 kyr BP): A Quantitative Record Using a Novel Rare Earth Element Mixing Model 

Steeve Bonneville, Aubry Vanderstraeten, Laruelle Goulven, Sibylle Boxho, Bory Aloys, Gabrielli Paolo, Gili Stefania, and Nadine Mattielli

Antarctic ice cores have provided valuable insights into the intricate interplay between dust and climate dynamics in the Southern Hemisphere. However, until now, a continuous and quantitative record detailing the origin of dust during the last deglaciation is lacking. In this study, we utilized a novel database comprising 207 Rare Earth Element (REE) patterns obtained from dust and fine sediment/soil fractions collected from well-known potential source areas (PSA) in the Southern Hemisphere. By combining this comprehensive dataset of REE patterns, we developed a robust statistical model to best match the REE patterns measured in the Epica Dronning Maud Land (EDML) ice core in East Antarctica. Among the 398 samples analyzed in the EDML core, 386 have been un-mixed with statistical significance. When coupled with data on total atmospheric deposition, our findings enable the first quantification of the dust flux from the various PSA reaching the EDML region between 7,000 and 27,000 years before present (kyr BP). Our results unveil that, despite a substantial decrease in atmospheric deposition at the onset of deglaciation around 18,000 years ago, the dust composition remained relatively uniform throughout the Last Glacial Maximum (LGM, 18-27 kyr BP) and Heinrich Stadial 1 (HS1, between 14.7-18 kyr BP). During this period, approximately 68% of the total dust deposition was coming from Patagonian sources, with the remaining contributions originating from Australia (14-15%), Southern Africa (~9%), New Zealand (~3-4%), and Puna-Altiplano (~2-3%). A significant shift in dust provenance occurred around 14.5 kyr BP, marked by a drop in Patagonian contribution to below 50%, while low-latitude PSAs increased their contributions, accounting for 21-23% from Southern Africa, 13-21% from Australia, and ~4-10% from Puna-Altiplano. We propose that this shift is linked to enduring alterations in the hydrology of Patagonian rivers, including Atlantic-Pacific drainage reversals and the decline of braided planform, along with the sudden submersion of the Patagonian shelf. Indeed, between 15 and 14.0 kyr BP, the PAT shelf surface area was halved and by ∼13 kyr BP, it had shrunk by 70% from to its former maximum glacial expansion, with most of the PAT shelf south of 40°S submerged. The drastic reduction of the area subjected to aeolian deflation coupled with the reduction of fine sediment supply of eastern plains in PAT induced an overall decline in dust emission from Patagonian sources. Our finding emphasizes an important feedback between dust composition in Southern Hemisphere and eustatic sea level during the Last Glacial-Interglacial Transition. The early Holocene dust composition reveals heightened variability, with a prevalent contribution from Patagonia at ~50%. Post 11.5 kyr BP, as Puna-Altiplano experienced persistent aridity, our records demonstrate a noticeable increase in dust contribution. Leveraging a comprehensive coverage of both local and distal PSA, our statistical model, based on REE patterns, provides a straightforward and cost-effective method for tracing dust sources in ice cores.

How to cite: Bonneville, S., Vanderstraeten, A., Goulven, L., Boxho, S., Aloys, B., Paolo, G., Stefania, G., and Mattielli, N.: Unveiling the provenance of dust in the EPICA Dronning Maud Land Ice Core (Antarctica) throughout the Last Deglaciation (7–27 kyr BP): A Quantitative Record Using a Novel Rare Earth Element Mixing Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17880, https://doi.org/10.5194/egusphere-egu24-17880, 2024.

EGU24-17990 | ECS | PICO | AS3.9

Impactor-Based Size Fractionation of Aerosol Particles over the Tropical Atlantic Ocean: Source Identification using Nd, Sr, and Pb Isotopes  

Oriol Teruel-Cabello, Leo Pena, Ester Garcia-Solsona, Eduardo Paredes, Isabel Cacho, Antoni Rosell-Melé, and Joan Villanueva

Airborne mineral dust is a significant constituent of the Earth's climate system that warrants detailed investigation to comprehend its impact on climate processes. This work presents a comprehensive multiproxy approach, utilizing Sr-Nd-Pb isotopes, to discern mineral dust source areas from North Africa, a region contributing approximately 55% of the global annual dust load. Our research not only focuses on identifying provenance but also explores the relationship between climate processes in source areas and aerosol properties at remote locations. We collected samples during three oceanographic campaigns in the tropical Atlantic Ocean conducted in 2020, 2021, and 2022, spanning late winter and entire spring periods. The interannual aspect allows us to capture variations, enhancing our understanding of dust emission and transport dynamics. The implementation of a sampling device that separates aerosol particles of different sizes allows for the detailed isotopic characterization of particles in each size range. Our results indicate the existence of diverse origin and transport patterns depending on the particle size. Differentiation based on particle size uncovers compelling insights into the dynamics of dust dispersion, revealing size-dependent variations in dust behavior. Notably, we observe distinctive pathways for the mass of elements at each size, elucidating the complex interplay between Nd, Sr, and Pb. 

How to cite: Teruel-Cabello, O., Pena, L., Garcia-Solsona, E., Paredes, E., Cacho, I., Rosell-Melé, A., and Villanueva, J.: Impactor-Based Size Fractionation of Aerosol Particles over the Tropical Atlantic Ocean: Source Identification using Nd, Sr, and Pb Isotopes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17990, https://doi.org/10.5194/egusphere-egu24-17990, 2024.

Vegetation fires represent a major, mostly anthropogenically-driven, component of the Earth system that are affecting different landscapes in multiple regions of the globe and are supposed to increase further in number and severity with the ongoing climate change. Measurements and conceptional model studies have already shown that the fire-induced disturbance of the near-surface wind patterns allow for the mobilization of soil dust particles and their injection into the atmosphere through the pyro-convective updrafts related to the fires. However, the dust emission schemes of the current generation of aerosol-climate models do not consider this fire-related emission pathway and focus on wind-driven dust emissions of mostly unvegetated landscapes such as deserts only. This can result in an underrepresentation of dust particles in the fire-affected regions with consequences regarding a correct representation of aerosol-atmosphere interactions such as the radiation budget.

Therefore, the present study aims to provide more insights concerning the importance of fire-driven dust emissions in the climate system. In order to achieve this, the process was implemented as a new emission pathway into the aerosol module HAM (Hamburg Aerosol Module) of the newly coupled aerosol-climate model ICON-HAM. Information about the behavior of the fire-affected wind fields and their potential to overcome typical emission thresholds have been used to set the dust emission fluxes in relation to data of the global fire activity, expressed by the fire radiative power (FRP), and to land-surface characteristics such as soil type and surface roughness.

Multi-year global simulations of ICON-HAM were analyzed to quantify the impacts of the additional dust emissions caused by the fire activity and their injection parameterization on a seasonal and continental scale. It was found that the strength of the fire-related dust emissions strongly depends on the region where the fire occurs, which is determined by the local soil-surface conditions and not only by the fire strength. However, the vegetation fires can lead to an increase of the atmospheric dust load even in regions far away from those commonly known as dust source areas, highlighting that fire-driven dust emissions can substantially contribute to the total aerosol load and in particular its composition within fire-prone regions or also within a fire-prone climate.

How to cite: Wagner, R. and Schepanski, K.: Fire-driven dust emissions – applying a newly developed parameterization scheme in a global aerosol-model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18339, https://doi.org/10.5194/egusphere-egu24-18339, 2024.

EGU24-18556 | PICO | AS3.9

EMIT Global Dust Source and Emission Mineral Abundance Maps for Dust and Climate Modeling 

Carlos Pérez García-Pando and the EMIT Team

Soil dust aerosols, comprised of diverse minerals with varying relative abundances, particle size distribution (PSD), shape, surface topography, and mixing state, exert a significant influence on climate. Despite this complexity, conventional Earth System Models tend to assume a globally uniform dust aerosol composition, overlooking well-documented regional variations in the mineralogy of their sources. Existing models addressing dust mineralogical variations often rely on mineral abundance maps extrapolated from an insufficient and non-uniform set of soil sample analyses, especially scarce in arid and semiarid regions.

This study introduces the first version of a series of global dust source and emission mineral abundance maps for dust and climate modelling built upon data from the Earth Surface Mineral Dust Source Investigation (EMIT) imaging spectrometer that is currently operational on the International Space Station (ISS). EMIT measures the spectral range from 0.38 to 2.50 microns through 285 contiguous spectral channels at a high spatial resolution of approximately 60 meters per pixel and ~77 km swath width. The EMIT ground system, utilizing Tetracorder, enables material identification and mapping on mineral spectra. EMIT provides quantitative maps for 10 critical minerals over dust sources pivotal for understanding interactions with the Earth System, with a specific emphasis on mapping iron oxides (hematite and goethite) to constrain the dust direct radiative effect.

Our study offers a comprehensive overview of the diverse methods explored, challenges faced, and key assumptions made to provide quantitative dust source mineralogy. Notably, addressing the absence of information on quartz and feldspar, whose absorption features extend beyond the measured spectral range, poses a significant challenge. Methodologies range from a model that linearly relates mineral abundance to absorption-feature band depth, to more advanced models solving the non-linear multiple scattering radiative transfer problem, providing abundances across a broader range of conditions.

Furthermore, the study provides insights into key assumptions guiding the derivation of mineral abundance maps for both clay and silt fractions of the soil. It also details methods rooted in brittle fragmentation theory, essential for estimating emitted size-resolved mineralogy, which is the critical input for Earth System Models.

This research contributes to advancing our understanding of soil dust aerosols, laying the foundation for improved climate models that account for nuanced regional variations in mineralogical composition.

How to cite: Pérez García-Pando, C. and the EMIT Team: EMIT Global Dust Source and Emission Mineral Abundance Maps for Dust and Climate Modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18556, https://doi.org/10.5194/egusphere-egu24-18556, 2024.

EGU24-18893 | ECS | PICO | AS3.9

Size segregation process along the soil-saltation-dust continuum: observations in southern Tunisia  

Rizewana Marécar, Béatrice Marticorena, Gilles Bergametti, Jean Louis Rajot, Christel Bouet, Servanne Chevaillier, Anais Féron, Bouthaina Khalfallah, Stéphane Alfaro, Mohamed Taieb Labiadh, Thierry Henry des Tureaux, Saad Sekrafi, and Mohsen Lifti

The particle size segregation processes occurring between the soil, the saltation layer and the dust layer close to the surface are not well described while they are key steps for a precise assessment of dust emission. Improving our understanding and quantifying the role of the processes acting in these three compartments should significantly enhance the consistency of dust emission models.

Data obtained during the WIND-O-V (WIND erOsion in presence of sparse Vegetation) field campaign that took place in spring 2017 in southern Tunisia have been analyzed. Eight saltation events of durations from 1 to 4 hours were sampled and corresponded to a range of wind friction velocities between 0.28 and 0.46 m s-1. The dispersed and non-dispersed size distributions of the soil and of the saltation fluxes were characterized and the micrometeorological conditions were also analyzed. Simultaneous measurements of size resolved saltation fluxes and size-resolved vertical dust fluxes were carried out. The combined analysis of size distributions of the parent-soil and of the horizontal and vertical fluxes reveals an enrichment of fine particles that increases with height. A consistent behavior is observed when comparing the particle size distribution of the saltation and of the vertical dust fluxes. Moreover, we observe changes in the size distributions from one event to another that are similar for the saltation and the dust fluxes. This strongly suggests that the processes controlling the saltation significantly affect the dust size distribution. The roles of the vertical transfer and of the micrometeorological conditions on the size distributions are also discussed.

How to cite: Marécar, R., Marticorena, B., Bergametti, G., Rajot, J. L., Bouet, C., Chevaillier, S., Féron, A., Khalfallah, B., Alfaro, S., Labiadh, M. T., Henry des Tureaux, T., Sekrafi, S., and Lifti, M.: Size segregation process along the soil-saltation-dust continuum: observations in southern Tunisia , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18893, https://doi.org/10.5194/egusphere-egu24-18893, 2024.

EGU24-19326 | PICO | AS3.9

Why does it rain in the desert? The dust record in Tunisia. 

Anna Bird, Ian Millar, Doris Wagner, Kaja Fenn, Rachel Smedley, Barbara Mauz, Moez Mansoura, Michael Rogerson, Marc Luetscher, Mahjoor Lone, and Noureddine Elmejdoub

North Africa is one of the regions identified by UNESCO as experiencing severe water stress, and further drying could be devastating for region that is also insecure. Tropical semi-arid regions, such as North Africa are highly sensitive to climate change, and climate predictions for this area suggest that this region will experience drying in the next decades and centuries. This contrasts with findings from palaeo-studies which show that, during the Pleistocene, global warming often correlates to humid phases. This project uses speleotherm records with palaoedust (loess) archives to assess the climate record over humid and dry periods to improve our understanding of past climate change in the sensitive but under-represented central northern Africa region. This presentation will focus on findings from the most important loess deposit in northern Africa, at Matmata in Tunisia.

The loess sections within the Matmata Plateau have loess and soil horizons relating to a series of humid and arid phases during the Quaternary, a sequence that provides valuable insight into the origins and dynamics of desert deposits and the interplay between continental and maritime weather systems. Previous work, in the 1990s, on the Matmata loess has shown onset of loess deposition to be during a humid phase (~70 ka) with loess deposition continuing as the climate becomes more arid into the Upper Holocene. It is currently assumed that the source of this material is the Grand Erg Orient, based on a relatively old study (1987). However, new OSL data presented here shows that the onset of loess deposition was much older than previously thought (~300 ka), with the top of the sections dated at ~24 ka. It appears that deposition was not continuous with a large gap in the record from 143 – 45 ka. Gaps in sedimentation for the section older than ~140 ka are difficult to determine due to limited reliability of older OSL ages.

Provenance analysis has been undertaken on many of the dated samples to establish past transport directions. Detrital zircon U-Pb data suggest that there is dominant Algeria-type source with some input from the north. The amount of this input varies over time with samples older than 200 ka showing a larger input from the north. 87Sr/86Sr and 143Nd/144Nd isotopes from different grainsize fractions tell a similar story, with a dominant west African source.

How to cite: Bird, A., Millar, I., Wagner, D., Fenn, K., Smedley, R., Mauz, B., Mansoura, M., Rogerson, M., Luetscher, M., Lone, M., and Elmejdoub, N.: Why does it rain in the desert? The dust record in Tunisia., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19326, https://doi.org/10.5194/egusphere-egu24-19326, 2024.

EGU24-20434 | ECS | PICO | AS3.9

Forcing factors behind primary productivity variabilities in Western Arabian Sea  since the Last Glacial Maximum: an important role of mineral dust supplies 

Alice Karsenti, Charlotte Skonieczny, Stéphanie Duchamp-Alphonse, Xinquan Zhou, Kara Labidi, Nicolas Musial, Ana Alves, Maxime Leblanc, Julius Nouet, Amélie Plautre, Sébastien Bertrand, Eva Moreno, Annachiara Bartolini, Catherine Kissel, and Franck Bassinot

Located in the Northwestern part of the Indian Ocean, the Arabian Sea (AS) is surrounded by vast arid regions (e.g. Arabian Peninsula, Pakistan, Iran), regularly swept by regional winds, that supply important amounts of mineral dust to the sea. This oceanic area is also under the influence of Indian monsoon surface winds that create a coastal upwelling off Somalia and Oman during summer and a convective mixing north of 15°N during winter. Consequently, mineral dust, coastal upwelling and convective mixing bring important amounts of nutrients to the euphotic zone, making the AS one of the most productive oceanic regions in the world. Although older studies usually highlight the coastal upwelling as a major factor behind primary productivity (PP) patterns in the AS, more recent studies have demonstrated that mineral dust inputs and convective mixing could have a significant influence on PP as well, at least since the Last Glacial Maximum (LGM). This time interval encompasses a glacial-interglacial transition with rapid fluctuations of ice sheet volume and atmospheric CO2 concentration, and represents therefore, a perfect case study to explore the impact of key Earth’s climate forcing mechanisms on the PP for both, past and future climate conditions. Yet, mineral dust component is still poorly documented by proxy data in the AS and direct reconstruction of PP are rare, which limit our understanding of how fertilization of the euphotic zone either by dust, coastal upwelling and/or convective mixing, impacts PP in the past. In this study, we combine high resolution bulk geochemical composition, detrital fraction grain-size distribution and clay mineralogy composition, together with coccoliths counting and carbon organic analyses from sediment cores MD00-2354 and MD00-2355, both retrieved on the Owen ridge. The aim is to reconstruct high-resolution mineral dust and PP patterns over the western part of the AS since the LGM. Both sites are located under the direct influence of dust plumes and among the seasonal latitudinal shift of monsoonal winds. They are therefore willing to register nutrient inputs from mineral dusts, winter convective mixing and/or summer coastal upwelling. Combined with previous paleoclimate records from the area, they will provide for the first time, an unprecedented overview of the forcing factors behind PP distribution in the past. Preliminary results show decreasing PP at both sites through the last 20 ka, suggesting a regional pattern of nutrient distribution in the western AS. Particularly, a strong correlation between PP and mineral dust signals reinforces the hypothesis of a key role of mineral dust on PP in the area. 

How to cite: Karsenti, A., Skonieczny, C., Duchamp-Alphonse, S., Zhou, X., Labidi, K., Musial, N., Alves, A., Leblanc, M., Nouet, J., Plautre, A., Bertrand, S., Moreno, E., Bartolini, A., Kissel, C., and Bassinot, F.: Forcing factors behind primary productivity variabilities in Western Arabian Sea  since the Last Glacial Maximum: an important role of mineral dust supplies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20434, https://doi.org/10.5194/egusphere-egu24-20434, 2024.

EGU24-20949 | PICO | AS3.9

Radiative Forcing Assessment of Black Carbon in Snow from the Antarctic Peninsula  

Francisco Cereceda-Balic, María Florencia Ruggeri, Gonzalo Barcaza, Ximena Fadic, and Hans Moosmüller

The pristine Antarctic environment, despite its remoteness, is not immune to the influence of anthropogenic
pollutants. This study focuses on quantifying the Radiative Forcing (RF) resulting from Black Carbon (BC)
concentrations in snow samples collected from various points on the Antarctic Peninsula during the austral summer
of 2023, aiming to assess the impact of BC on the snowpack albedo and, consequently, on the regional climate. To the
best of our knowledge, in most of the locations studied, BC concentrations in snow have never been measured before.
Snow samples were meticulously collected from different locations on the Antarctic Peninsula, covering a diverse
range of environments, including base surroundings, remote locations, and icebergs. This effort was undertaken as
part of the ECA59 campaign, funded by the Chilean Antarctic Institute (INACH). The sampling constituted the initial
phase of a project involving three distinct sampling periods. Specifically, the collection sites were situated in the
eastern sector of the peninsula, known for its minimal human presence and limited prior research, making it a
relatively unexplored region. BC concentrations in our snow samples were measured following the method described
in Cereceda-Balic et al. (2022, https://doi.org/10.1016/j.envres.2022.113756). To understand the BC RF, the SNICAR
(SNow, ICe, and Aerosol Radiation) model was employed to simulate snow albedo for measured BC concentrations.
This methodology allowed for an assessment of the potential BC-induced changes in albedo and the resulting RF. The
analysis revealed a significant range of BC concentrations in Antarctic snow samples, spanning from 2.4 to 1157 ng g-1. Simulating snow albedo using the SNICAR model indicated BC-induced albedo reductions of up to 20% relative to clean snow. The calculated BC-induced RF reached up to 38 W m-2, indicating a substantial climatic impact of BC in the Antarctic Peninsula region.

Our findings underscore the influence of BC on the radiative properties of snow in the Antarctic Peninsula. The diverse
BC concentrations observed here suggest varying sources and highlight the need for continued monitoring. The results
reveal the vulnerability of the Antarctic Peninsula to the impacts of anthropogenic pollutants, even in its seemingly
pristine surroundings. Acknowledging and addressing these influences is essential for assessing the broader
implications of climate change in polar regions. Continued research at these little-explored sites is crucial for refining
climate models and informing mitigation strategies to preserve the integrity of the Antarctic environment.


Acknowledgments: INACH Project RT_34-21, and ANID Project: Fondecyt Projects N°1221526 andN°11220525, ANILLO ACONCAGUA N°ACT210021, and FOVI230167

How to cite: Cereceda-Balic, F., Ruggeri, M. F., Barcaza, G., Fadic, X., and Moosmüller, H.: Radiative Forcing Assessment of Black Carbon in Snow from the Antarctic Peninsula , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20949, https://doi.org/10.5194/egusphere-egu24-20949, 2024.

EGU24-22132 | ECS | PICO | AS3.9

Reading dust provenance record in Epica Dome C Ice Core (EDC) of Antarctica reveals a shift from Patagonian to African sources through the last deglaciation (2.9 – 33.7 kyr) 

Sibylle Boxho, Nadine Mattielli, Aubry Vanderstraeten, Goulven G. Laruelle, Aloys Bory, Paolo Gabrielli, Stefania Gili, and Steeve Bonneville

Epica Dome C (EDC) ice core is invaluable and highly-resolved record of Earth’s climate. Within the database of climate proxies in deep ice core, quantifying the contribution of the various sources of dust has been very challenging and, so far, no continuous record of dust provenance has been established. Here, we developed an algorithm that combines the REE patterns from a large database (from 207 sediments/soils in well-known Potential Source Areas - PSA - in the Southern Hemisphere) to fit the REE patterns measure in EDC data[1]. Complemented by Monte Carlo simulations to account for analytical uncertainties and by evaluation of goodness-of-fit, our model quantifies the respective contribution of the dust sources (regrouped by large PSA like Patagonia, Africa, S-E Australia, New Zealand and Puna-Altiplano) deposited in EDC ice core between 2.9 and 33.7 kyr at a centennial resolution.

Our provenance record reveals that a major shift in dust provenance occurred at ~14.5-kyr BP during which the contribution of Patagonia (PAT – the main supplier of dust of the Last Glacial Maximum -LGM) declined from   ̴55% to 35% (% of total dust deposition) while African dust (SAF) became more prevalent from   ̴20% during LGM to   ̴40% after 14.5 kyr BP. As a matter of fact, the main supplier of dust in EDC during the Holocene is Southern Africa. We ascribe this abrupt shift to (i) long-lasting changes in the hydrology and of Patagonian rivers and (ii) to a sudden acceleration of sea-level rise between 14 and 15 kyr BP that submerged vast swathes of Patagonian continental shelf, triggering a decline in PAT dust supply to Antarctica. In turn, this induced a steep increase – in relative term - of SAF dust contribution in EDC.

Importantly,our record for EDC is very much consistent with our previous results for Epica Dronning Maud Land (EDML)[2] ice core showing the exact same shift (PAT for SAF dust) between 14 and 15 kyr BP. Yet, compared to EDML, EDC record shows generally larger contribution for SAF and lower PAT dust which seems logical considering the respective localization of EDML and EDC. Our results for EDC thus confirms the relationship between dust composition and eustatic sea level and also highlight the importance of African dust deposition in the Southern Indian ocean and in the adjacent sector of the Southern Ocean since 14 kyr. Our tracing method using REE patterns offers a new, high-resolution tool for the reconstruction of atmospheric paleo-circulation and paleoclimate in the Southern Hemisphere.

[1]Gabrielli et al., (2010), Quaternary Science Review 29, 1-2.

[2]Vanderstraeten et al., (2023), Science of the Total Environment 881, 163450

How to cite: Boxho, S., Mattielli, N., Vanderstraeten, A., Laruelle, G. G., Bory, A., Gabrielli, P., Gili, S., and Bonneville, S.: Reading dust provenance record in Epica Dome C Ice Core (EDC) of Antarctica reveals a shift from Patagonian to African sources through the last deglaciation (2.9 – 33.7 kyr), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22132, https://doi.org/10.5194/egusphere-egu24-22132, 2024.

EGU24-3232 | Posters on site | AS4.2

A climatological satellite view of marine cold air outbreaks in the northeast Atlantic 

Abhay Devasthale and Michael Tjernström

Given the high rate of sea ice loss and the Arctic amplification, the dynamical processes responsible for airmass transport into or out of the Arctic, thus affecting the seasonal melt and recovery of sea ice, need to be understood and scrutinized from different observational perspectives. In a classical, rather binary view of transport “into or out of the Arctic”, a lot of attention in the recent years has rightfully been given on understanding the role of heat and moisture transport into the Arctic in regulating the sea ice melt. However, the cold and dry Arctic airmasses with long residence times are more than occasionally transported out of the Arctic over the open ocean waters, creating one of the most spectacular air mass transformations: the marine cold air outbreaks (MCAOs). The most tangible manifestation of MCAOs are the convectively rolled, narrow cloud streets formed over open water off the edges of the Arctic sea ice in the Nordic and Barents Seas, seen vividly in visible satellite imageries. MCAOs can also locally influence the onset of sea ice melt as they often happen in spring.  

By combining nearly 20 years of remotely sensed data from the hyperspectral Atmospheric Infrared Sounder (AIRS), the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth’s Radiant Energy System (CERES) instruments onboard NASA’s Aqua satellite, this study presents a climatological view of the vertical structure of atmosphere and the cloud radiative effects during MCAOs in the northeast Atlantic.

How to cite: Devasthale, A. and Tjernström, M.: A climatological satellite view of marine cold air outbreaks in the northeast Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3232, https://doi.org/10.5194/egusphere-egu24-3232, 2024.

EGU24-3662 | ECS | Orals | AS4.2

Non-conservative nature of Boron in low salinity Arctic ice and ice melt zones 

Samantha Rush, Chang-Ho Lee, Kitack Lee, Penny Vlahos, and Lauren Barrett

The Arctic Ocean is one of the most rapidly changing environments on the planet as sea ice extent and thickness have declined extensively over the last 40 years. It is predicted that by 2050, Arctic summers will become mostly ice-free, and the Arctic Ocean will be dominated by seasonally annual, rather than multiyear, sea ice. Arctic sea ice serves as a mediator of biogeochemical processes globally, though the impacts of increased ice melt and water column freshening on Arctic biogeochemistry are uncertain. Specifically, declining sea ice raises significant concerns regarding the future carbon uptake potential of the Arctic and the buffering capacity, or alkalinity, of seawater. Boron (B) is a major element in seawater, and in the form of the borate ion, it serves as the third largest contributor to alkalinity. Boron concentrations in the open ocean are typically conservative and accounted for through relationships with other water components, such as with salinity (S) in the boron to salinity ratio (B/S). Well established B/S ratios have been defined for the open ocean; however, salinity variability can create discrepancies in the open ocean boron corrections for alkalinity. In 2021, work in the marginal ice zone of the Bering and Chukchi Seas revealed non-conservative boron behavior and significant alkalinity system inaccuracies based on the deviation in computed B/S ratios in ice cores and brine. In this study, we investigate the B/S ratio in ice melt zone waters, snow, brine, annual, and multiyear sea ice from the eastern Arctic basin. A total of 169 samples were collected during the onset on melt (May-June 2023) on the ARTofMELT expedition across a range of salinities (2 - 63). High salinity samples (S>29) included 1 lead, 7 brine, 16 under-ice, and 28 open ocean water samples. Low salinity samples (S<29) included 1 brine, 10 snow, and 106 ice core samples. Excluding snow, results indicate deviations from the accepted open ocean B/S ratio (0.1336 mg/kg). For both the entire high salinity sample set and the open ocean subset within it, the B/S average value (0.1304 ± 0.001 mg/kg) was lower. For low salinity samples, the average B/S value (0.1328 ± 0.003) was higher than the high salinity sample value but still lower than the accepted field value. The range of B/S ratios was much larger in low salinity samples (0.1260-0.1425 mg/kg) than high salinity samples (0.1275-0.1350 mg/kg); however, both ranges were significantly smaller than the 2021 B/S ratio range (0.0900-0.1850 mg/kg). The smaller deviation from the accepted B/S ratio in this study resulted in carbon system analysis inaccuracies less than 2 µmol/kg across the entire salinity range. We present the computed B/S ratios and the differences in these datasets using the δ18O isotopic ratios to understand the heterogeneity of western, annual ice in the marginal ice zone and eastern, multiyear ice in pack ice regions. The marked distinction in the datasets allows potential insight into boron concentrations and the conversion of total alkalinity to carbonate alkalinity across current and future systemic climate-change shifts in the Arctic.

How to cite: Rush, S., Lee, C.-H., Lee, K., Vlahos, P., and Barrett, L.: Non-conservative nature of Boron in low salinity Arctic ice and ice melt zones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3662, https://doi.org/10.5194/egusphere-egu24-3662, 2024.

EGU24-4403 | ECS | Posters on site | AS4.2

Near-surface particle concentration profiles above the Arctic sea ice 

Theresa Mathes and Andreas Held

The Arctic region is warming rapidly, and aerosol-cloud-sea-ice interactions are considered to be one of the key features of the Arctic climate system. It is therefore crucial to identify Arctic particle sources and sinks in order to study their impact on cloud formation and properties. Scott and Levin (1972) were the first to describe open leads as potential sources of atmospheric particles and thus a local source of particle emissions in the central Arctic. Held et al. (2011) found that open leads and ice ridges in particular emit high levels of particles. Particle concentrations have also been shown to be altered by the intrusion of warm and moist air masses and can be strongly enhanced in turbulence-dominated cases (You et al., 2022). Despite significant progress in Arctic research in recent years, there is still a lack of information on near-surface particle concentrations over different surface types, especially before and during the ice-melting period.

Here, we present measurements of near-surface particle concentration profiles to help to quantify the vertical aerosol exchange between Arctic sea ice and the atmosphere. In spring 2023, during the research cruise ARTofMELT on board the icebreaker Oden, we successfully carried out vertical particle measurements. From 17 May to 9 June 2023, near-surface particle concentration profiles were measured during 16 individual measurement periods. Due to the early season, measurements could be taken both before and during the melting process.

For the profile measurements, an aersol inlet was automatically moved up and down by a 1.50 m linear actuator. A plate was attached to the lift to hold sensors for the distance, wind and temperature as well as the aerosol inlet. An  box containing the condensation particle counter (CPC 3007, TSI, St. Paul, MN, USA) was connected to the inlet. Total particle number concentrations with a lower cut-off diameter of 10 nm were then determined at six different heights from 6 cm above the surface to 1.30 m. These measurements were carried out on the ice close to an open lead or surrounded by a closed ice surface.

Figure 1 shows an example for two days of fluxes at 79.8 ° N and 1.9° W. Due to the proximity to the open lead, an emission (red) of aerosols predominates, which is partially alternated by a deposition (blue). The flow calculations are based on 26 height profiles measured on 17 May and 24 on 18 May.

We thank our colleagues from Leibniz Institute for Tropospheric Research, Stockholm University, Swedish polar research secretariat as well as all expedition participants who provided insight and expertise that greatly assisted the research.

Held, A., Brooks, I.M., Leck, C., and Tjernström, M. (2011) On the potential contribution of open lead particle emissions to the central Arctic aerosol concentration. Atmos.Chem.Phys. 11, 3093-3105.
Scott, W. D. and Z. Levin (1972) Open channels in sea ice as ion sources. Science 177, 425-426.
You, C., Tjernström, M., Devasthale, A. (2022) Warm and moist air intrusions into the winter Arctic: a Lagrangian view on the near-surface energy budgets. Atmos.Chem.Phys. 22, 8037–8057.

How to cite: Mathes, T. and Held, A.: Near-surface particle concentration profiles above the Arctic sea ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4403, https://doi.org/10.5194/egusphere-egu24-4403, 2024.

EGU24-5124 | ECS | Orals | AS4.2 | Highlight

Is spring melting in the Arctic detectable by under-ice radiation? 

Philipp Anhaus, Christian Katlein, Marcel Nicolaus, Noémie Planat, and Martin Schiller

A trend towards earlier sea-ice melt is detected in many ice-covered regions in the Arctic. The timing of the melt onset has a strong impact on the sea-ice energy budget. Melt onset changes the radiative properties of the ice due to increasing snow wetness and meltwater. So far, satellite passive microwave data are used to detect the melt onset. We analyzed transmitted radiation spectra as collected underneath drifting sea-ice using a remotely operated vehicle during the ARTofMELT expedition in the Fram Strait in spring 2023. We colocated those spectra with measurements of snow depth, sea ice and surface topography, chlorophyll-a concentration in the water column, and with aerial images. This combined dataset enables us to track down possible subsurface pathways and accumulation pools of meltwater. Areas of low snow load and depressed surface topography are characterized by higher transmitted radiation compared to areas with a thick snow cover. Those areas overlapped with areas that showed the first signs of surface melt. Chlorophyll-a concentrations varied only slightly in magnitude and did not match with the heterogeneous pattern of snow depth and ice topography. Here we discuss how to disentangle the influences of chlorophyll a and the subsurface meltwater on the spectral shape of transmitted radiation. We propose that upon successful disentanglement, the spectra can be used as an indicator for subsurface melting. Our study suggests that sea-ice melting starts subsurface and that measurements of transmitted solar radiation spectra could be used to identify the melt onset prior to surface melting. This can provide an interesting complementary information on melt occurrence and on the location of the water in the snowpack in addition to satellite passive microwave data.

How to cite: Anhaus, P., Katlein, C., Nicolaus, M., Planat, N., and Schiller, M.: Is spring melting in the Arctic detectable by under-ice radiation?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5124, https://doi.org/10.5194/egusphere-egu24-5124, 2024.

EGU24-5372 | Orals | AS4.2

Impact of warm and moist intrusions on black carbon deposition and summer snow melt in the central Arctic 

Hélène Angot, Marion Réveillet, and Julia Schmale and the MOSAiC team

Warm and moist intrusions (WAMIs) into the central Arctic, predominantly observed in winter and early spring, are becoming more frequent, significantly affecting the region’s near-surface energy budget. This study focuses on the deposition pulses of black carbon (BC) triggered by WAMIs and their subsequent impact on snow properties and melting during the summer, using a modeling approach and comprehensive datasets from the 2019–2020 Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) expedition. Our findings reveal that WAMIs induce episodes of intense BC wet deposition in the central Arctic shoulder season (Nov–Apr) due to transported pollution and moisture. We demonstrate that WAMIs result in exceptionally high BC deposition (> 4 orders of magnitude compared to typical winter/spring conditions) across an area of nearly 1 million km2, approximately 20% of the central Arctic Ocean. Furthermore, we establish a direct connection between these winter/spring BC deposition pulses and subsequent summer increases in absorbed solar energy (> 4 W/m2) and snowpack melt rate (+15%). Despite their sporadic occurrence (only 8% of the time), WAMIs play a significant role in the central Arctic surface energy budget through the BC snow albedo effect.

How to cite: Angot, H., Réveillet, M., and Schmale, J. and the MOSAiC team: Impact of warm and moist intrusions on black carbon deposition and summer snow melt in the central Arctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5372, https://doi.org/10.5194/egusphere-egu24-5372, 2024.

EGU24-5901 | ECS | Posters on site | AS4.2

Aerosol-Cloud-Precipitation Interactions in the Arctic: Insights from the ARTofMELT Campaign 

Lea Haberstock, Julia Asplund, Almuth Neuberger, Luisa Ickes, Gabriel Freitas, Fredrik Mattsson, Darrel Baumgardner, Ilona Riipinen, and Paul Zieger

Aerosol-cloud interactions play a crucial role in the Arctic’s radiative budget. During the campaign ‘Atmospheric rivers and the onset of sea ice melt’ (ARTofMELT 2023) we aimed to improve our understanding of aerosol-cloud interactions by conducting in-situ measurements of microphysical and chemical properties of aerosols, cloud droplets, and precipitation in the Arctic during the onset of sea ice melt. A ground-based fog and aerosol spectrometer (GFAS) and a fog monitor (FM-120) from Droplet Measurement Technologies (DMT) were used to measure among other things droplet size, number concentration, and liquid water content. Precipitation was measured with a meteorological particle spectrometer (MPS, DMT). Throughout the campaign, we observed several fog and blowing snow events, along with occasional precipitation. These events provided an opportunity to investigate and compare the distinctive microphysical properties associated with each event. Our findings reveal significant variations in the size distribution and particle phase of blowing snow, precipitation, and fog.

How to cite: Haberstock, L., Asplund, J., Neuberger, A., Ickes, L., Freitas, G., Mattsson, F., Baumgardner, D., Riipinen, I., and Zieger, P.: Aerosol-Cloud-Precipitation Interactions in the Arctic: Insights from the ARTofMELT Campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5901, https://doi.org/10.5194/egusphere-egu24-5901, 2024.

EGU24-5950 | ECS | Posters on site | AS4.2

What we can learn from aerosol size distribution measurements over the spring Arctic pack ice 

Julia Asplund, Lea Haberstock, Jessica Matthew, Fredrik Mattson, Lovisa Nilsson, Erik Swietlicki, Megan Willis, Cort Zang, and Paul Zieger

Aerosol- cloud interactions remain among the most uncertain key parameters in the fast-changing Arctic climate system, in large part due to a lack of observational data from this hardly accessible region. The spring-summer transition is a particularly under sampled time period, due to harsh ice conditions. Here, we present five weeks of aerosol size distribution measurements over the spring Arctic pack ice, including more than 30 hours of in-cloud data, obtained during the ARTofMELT 2023 expedition. A setup of three inlets, including a whole-air, an interstitial, and a counterflow virtual impactor inlet, were used to cover the full aerosol population as well as both the activated and interstitial aerosol when in cloud. We will show an overview of the collected observations and the link between the size distribution properties and parallel measured aerosol parameters such as chemical tracers, as well as an air mass source analysis. Fog events were recorded during a range of aerosol conditions, allowing us to study the activated fraction when concentrations span from under 20 particles per cc, to over 150. The dataset also features several distinct regimes where different processes such as blowing snow, new particle formation, and secondary ice production dominate or influence the aerosol population, and we will demonstrate how the regimes are characterized by the dominant mode of the size distribution.

How to cite: Asplund, J., Haberstock, L., Matthew, J., Mattson, F., Nilsson, L., Swietlicki, E., Willis, M., Zang, C., and Zieger, P.: What we can learn from aerosol size distribution measurements over the spring Arctic pack ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5950, https://doi.org/10.5194/egusphere-egu24-5950, 2024.

EGU24-6663 | Orals | AS4.2

Perspectives on limitations and mechanisms for atmospheric initiation of onset of the summer melt season over sea ice 

Christopher Cox, Amy Solomon, Ola Persson, Matthew Shupe, Michael Gallagher, Von Walden, Michael Town, Donald Perovich, Sarah Webster, and Jacob Anderson

Onset of surface melt over sea ice is a factor in the duration of the melt season. Onset is often triggered by advection of warm, moist air from lower latitudes. This is especially characteristic of early dates of onset, but such events have also been hypothesized to precondition the ice for an earlier onset even when they don’t act as the trigger. The importance of atmospheric advection to the melt season is well-recognized by the community. Less attention has been given to the potential limitations of these events and to what alternate mechanisms may also be important for initiation, which is the subject of this presentation. We discuss two case studies.

In the first case, atmospheric advection from the North Atlantic in late May 2020 caused onset to occur over a wide area of the sea ice north of Greenland, including the floe being measured by the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. Approximately 6 weeks prior, in April, an anomalously warm advection event also impacted the MOSAiC floe and was responsible for ~40% of the total warming the ice underwent that spring. Using a diffusion model for the ice forced by surface temperatures that both include (observationally) and exclude (synthetically) the April event, we show that its influence relative to its absence was reduced by ~80% within 10 days. The result is explained by a negative feedback that suppresses conduction within the ice when warming events occur. Consequently, despite the apparent influential nature of the April event suggested by the observations, the ice temperatures would likely have been similar several weeks before onset if the April event had not occurred. This implies there are limitations to such events in preconditioning the sea ice for early onset.

Our second case examines data collected from a buoy in the Beaufort Sea during a regional onset event observed in June 2022. In this case, the air that caused melt at the buoy came from the north during a period of generally zonal flow of the polar jet (and lack of poleward moisture transport). Analysis of back trajectories indicates that the air had a residence time in the Arctic of 7-10 days prior to causing melt. The air began at mid-tropospheric levels near the pole then circulated around persistent, large-scale high pressure over the East Siberian Sea, descending along its track. Reanalysis data suggests the adiabatic contribution to the subsidence was sufficient to warm the air to the freezing point when it reached the surface, moving southward across the Beaufort Sea. This case indicates that subsidence is a mechanism internal to the Arctic that is capable of causing melt onset, though its climatological significance remains an open question.

How to cite: Cox, C., Solomon, A., Persson, O., Shupe, M., Gallagher, M., Walden, V., Town, M., Perovich, D., Webster, S., and Anderson, J.: Perspectives on limitations and mechanisms for atmospheric initiation of onset of the summer melt season over sea ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6663, https://doi.org/10.5194/egusphere-egu24-6663, 2024.

EGU24-11158 | ECS | Orals | AS4.2

Synoptic situation during the ARTofMELT 2023 spring expedition 

Sonja Murto and Michael Tjernström

A 6-week long expedition ARTofMELT (Atmospheric rivers and the onset of Arctic sea-ice melt) with the Swedish Icebreaker Oden took place in the Arctic Ocean during late winter and spring of 2023. The aim was to collect observations and study processes leading up to the sea-ice melt onset. One of the targets was to assess the role of atmospheric rivers (ARs), i.e., southerly warm and moist-air injections, in advancing the melt-timing. This paper presents the synoptic situation during the expedition, based on observations measured onboard Oden and reanalysis data (ERA5). Additionally, the origin and paths of airmasses reaching Oden are determined using 7-day backward trajectories computed with the Lagrangian analysis tool LAGRANTO. The meteorological conditions were quite dynamic during these 35 days, strongly influenced by several (at least 6) surface cyclones passing Oden and only two warming events accompanied by rather weak ARs were observed, the latter one leading to the melt onset at the end of the expedition.

 

Based on meteorological conditions from 6-hourly launched radiosoundings, the expedition can be divided into six periods. The first short period encompasses the first days of the expedition, when Oden was located at the marginal ice zone. The winds were variable, mainly southerly, and it was moist with slightly below-freezing temperatures. As Oden was moving northwestwards, a one-week cold (~-15 - -10) and dry period followed. This period was mainly governed by northerly winds, guided by a persistent family of surface cyclones located over the Laptev and Kara Seas. The first major storm, that coincided with an atmospheric blocking over Scandinavia, was related to a cyclone forming to the southwest of Greenland and moving northeast, bringing winds over 25 m/s as it hit Oden on 13 May.  Northerly winds followed after the stormed had passed, guided by a surface pressure dipole between a high over Greenland and a low over the Arctic Ocean.

 

The first one-week long ice camp was built at the end of the second period, extending into the third period. A low-pressure over Greenland and high-pressure and an upper-level blocking over Scandinavia resulted in a pathway for a transient warm-air mass from the south, and melting was observed for the first-time. However, this warming was only temporary, as temperatures dropped below freezing after the AR had passed. Several weaker storms governed this third milder period, ending with the second major storm associated with a cyclone on 25 May. Again, winds turned northerly after the storm passed, which made the entry to the fourth longer, colder and drier period. The second 2-week long ice camp was established at the beginning of this period and expanded over the two last periods. These captured the forecasted (6 June) and the real melt onset (10 June). A surface pressure dipole with a high over Greenland and a low over the Arctic Ocean dominated at the beginning of the fifth period, and warm but dry air aloft was observed. As the winds turned southerly, the melt-onset period was characterized as warm and moist.

How to cite: Murto, S. and Tjernström, M.: Synoptic situation during the ARTofMELT 2023 spring expedition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11158, https://doi.org/10.5194/egusphere-egu24-11158, 2024.

EGU24-11515 | ECS | Posters on site | AS4.2

Overview of SMÄLTA: Secondary Marine Aerosol precursors and Links to aerosol growth at ice-melT onset in the Arctic 

Cort Zang, Megan Willis, Julia Asplund, Fredrik Mattsson, Paul Zieger, and Michael Tjernström

The sources, composition, and reactive transformation of reactive organic carbon (ROC, non-methane organic carbon) as well as the processing, abundances, and distribution of organosulfur compounds in the Arctic marine atmosphere are unconstrained partially due to a lack of targeted measurements.  Understanding the emission, transport and processing of ROC and organosulfur compounds is important for improving our understanding of the impacts of gaseous precursors on aerosol nucleation and growth, and atmospheric oxidation capacity. There is a shift in aerosol size distribution that occurs with the Arctic spring-to-summer transition period and there are very few Arctic marine measurements of trace gases during this same period. Constraining the composition of organosulfur compounds and ROC is important for understanding the drivers in the shift of aerosol size distribution.

We present shipborne gas-phase measurements of ROC and organosulfur compounds in the Arctic marine atmosphere as part of the Atmospheric Rivers and the onseT of sea ice MELT (ARTofMELT) campaign. ARTofMELT took place from May 7th to June 15th of 2023 over pack ice and within the marginal ice zone between 78 and 81°N in the Fram Strait. We deployed a reagent ion switching chemical ionization mass spectrometer to target ROC and organosulfur compounds using H­3O+ ionization for the detection of reduced compounds and NH4+ ionization for the detection oxidized species. The measurements encompass a variety of different conditions including ozone depleted air masses (<10ppbv), cloud influenced air masses, a range of aerosol concentrations, and air masses with southern and northern airmass history with influences from biologically rich marine regions as well as transport from over pack ice. Additionally, measurements of ROC show the presence of ≥C5 organics in the environment with implications for aerosol size and growth. Here, we show an overview of our measurements and some initial observations of the ROC present during the campaign.

How to cite: Zang, C., Willis, M., Asplund, J., Mattsson, F., Zieger, P., and Tjernström, M.: Overview of SMÄLTA: Secondary Marine Aerosol precursors and Links to aerosol growth at ice-melT onset in the Arctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11515, https://doi.org/10.5194/egusphere-egu24-11515, 2024.

EGU24-12340 | ECS | Orals | AS4.2

Sea ice drift and wave pattern analysis of the early melt onset during the ARTofMELT cruise 2023 

Thibault Desjonquères, Leif E. B. Eriksson, Malin Johansson, Denis Demchev, Truls Karlsen, Timo Vihma, and Bing Cheng

In May-June 2023 the ARTofMELT 2023 expedition took place, with the aim to capture the melt onset in the Arctic Ocean. For the sea ice dynamics part of the cruise, in-situ observations were collected to co-inside with satellite observations, enabling studies of changes in drift patterns, capture the breakup of ice floes and studies of changes in backscatter signatures in satellite images as a consequence of melt onset. 

Seven OpenMETbuoys-v2021 and three SIMBA buoys, were placed on four first-year ice floes, away from the Marginal Ice Zone (MIZ). The OpenMETbuoys, equipped with GNSS (Global Navigation Satellite Systems), gyro, and accelerometer, facilitated horizontal motion, rotation, potential deformation, and wave action analysis. SIMBA buoys, with GNSS and thermistor strings, focused on temperature effects connected to melt onset. Three OpenMETbuoys and one SIMBA buoy were deployed on two larger floes. The two remaining drifters were deployed on individual floes. Deploying multiple buoys on each floe allowed detailed examination of small-scale drift changes, convergence, divergence, rotational patterns, frequencies, and connections to satellite Synthetic Aperture Radar (SAR) images. This deployment provides insights into the remaining wave energy in the pack ice. 

Low noise Radarsat Constellation Missions (RCM) SAR images in dual polarization (HH+VV or HH+HV) were acquired to overlap with the campaign in space and time. The temperature sensors onboard the SIMBA buoys enables us to connect changes in  backscatter values in the SAR images from the winter conditions into the early melt season and help define limitations for the SAR sea ice drift retrieval algorithm. 

Initial findings from wave and GNSS data offer insights into the condition of ice floes, including dislocation, disintegration, melting, and interactions with neighboring floes. The dislocation of the floes is indicated by the physical dissociation of the buoys present on the same floe. The OpenMETbuoys' recorded wave height and wave period indicate the drifter's location: on ice, in a transition phase on a small piece of ice or floating in the water between pieces of brash ice, or in open water.

Regarding the two bigger floes, on the first one, the drifters were launched 2023-05-22. An OpenMET drifter was dislocated from the rest of the floe on the 26th of May, and was in the transition phase on the 1st of July. The two remaining drifters were separated on the 29th of May. The last OpenMET drifter reached the transition phase on the 25th of May. The drifters on the second floe were launched 2023-05-28. The first dislocation occurred on the 8th of June, the second one on the 18th of June. The two remaining OpenMET drifters on this floe reached the transition phase on the 13th of June and 15th of June. The third floe contained a SIMBA drifter launched 2023-06-06 and the fourth one an OpenMETbuoy launched 2023-05-28. The latter reached the transition phase on the 10th of June.

How to cite: Desjonquères, T., Eriksson, L. E. B., Johansson, M., Demchev, D., Karlsen, T., Vihma, T., and Cheng, B.: Sea ice drift and wave pattern analysis of the early melt onset during the ARTofMELT cruise 2023, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12340, https://doi.org/10.5194/egusphere-egu24-12340, 2024.

EGU24-15627 | Orals | AS4.2 | Highlight

Arctic spring and the onset of sea-ice melt: Early impressions from the ARTofMELT expedition 

Michael Tjernström, Paul Zieger, and Sonja Murto and the ARTofMELT Science Team

The spring season in the Arctic Ocean has gained relatively little attention with detailed observations from expeditions, due to difficulties to navigate in the ice at this time of the year. This paper reviews experiences from the ARTofMELT (Atmospheric rivers and the onset of sea-ice melt) expedition in spring of 2023.

ARTofMELT had two objectives: To study processes leading up to the onset of the sea-ice melt and to explore links to so-called atmospheric rivers (ARs). ARs are spatially and temporally distinct inflows of warm and moist air from farther south. To fulfill these goals, we instrumented the Swedish research icebreaker Oden and planned to locate her in the Atlantic sector of the Arctic Ocean north of Svalbard from early May to mid-June. Oden was equipped with advanced meteorological instrumentation including standard meteorology and 6-horly radiosoundings, radar and lidars for cloud and wind measurements, and a surface flux tower with eddy-covariance. An advanced suite of atmospheric chemistry and aerosol observations were also deployed along with water isotope measurements, and also sampled and profiled the upper ocean structure. To identify upcoming ARs, we used ensemble forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) at lead time up to seven days, to allow time to navigate the icebreaker to optimal positions and establish ice camps. While carrying out most of the observations on board, in-situ observations on the ice provide valuable details on the impact of ARs on the ice. On ice camps we therefore deployed a surface energy budget station and an ROV surveying the ice from below and also flew a tethered balloon HELIKITE system from the aft of the ship. Additionally, we also used the helicopter to deploy scientists on the ice (sampling snow, ice and water) and deploying buoys, and for flying the HELIPOD instrument package.

ARTofMELT left Svalbard on 8 May and returned on 15 June. Starting with quite cold later winter conditions there was a brief warming period around mid-May, with an AR that brought air temperatures above the melting point twice (19 and 20 May). This was interrupted by a major storm, followed by a cooler period. From the end of May the surface started to gain heat, culminating in the onset of the melt at a second AR on 10 June. Both ARs were documented from ice stations.

A major uncertainty was the navigation in the ice during late winter and this also tuned out to be the most difficult part of the deployment. The ice was thick and hard to break, the size of the largest ice floes was much larger than expected and short-term variations of the ice pressure made navigation very difficult. The maximum latitude obtained was ~80.5 °N, hence, we stayed in the Fram Strait ice pack. Also, only two brief ARs were encountered, less than expected. In spite of this we were able to gain a large amount of unique observations, both from the icebreaker when in transit and from two ice camps.

How to cite: Tjernström, M., Zieger, P., and Murto, S. and the ARTofMELT Science Team: Arctic spring and the onset of sea-ice melt: Early impressions from the ARTofMELT expedition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15627, https://doi.org/10.5194/egusphere-egu24-15627, 2024.

EGU24-17193 | ECS | Orals | AS4.2

The composition and sources of airborne bacteria and proteinaceous Ice Nucleating Particles in the High Arctic marine region during Spring 

Jennie Spicker Schmidt, Marianne Glasius, Camille Mavis, Jessie Creamean, Gabriel Freitas, Paul Zieger, Kai Finster, and Tina Šantl-Temkiv

The Arctic is a particularly vulnerable region on Earth, where climate change takes place at an intense pace. Clouds represent an essential element within the Arctic atmosphere and play a crucial role in the regional radiative balance. The physical properties of clouds are tightly interlinked with the presence of aerosols that can serve as cloud condensation nuclei (CCN) and as ice nucleating particles (INPs), which facilitate the formation of cloud droplets and ice crystals, respectively. Consequently, they affect cloud thickness, lifetime, and albedo.

More studies propose that various biological aerosols e.g., aerosolized microbial cells, proteinaceous compounds and fragments actively contribute to cloud processes serving as INPs active at high subzero temperatures (>-15°C). However, our understanding of microorganisms responsible for producing compounds serving as INPs, their source environments, and their level of activity, remains highly uncertain.

Given the profound impact of climate change in the Arctic region, understanding the role of biological INPs in the atmosphere becomes particularly critical during Arctic melt season. Here, we present an overview of bioaerosol observations and sources tracking from the recent Arctic expedition ”Atmospheric rivers and the onset of Arctic melt” (ARTofMELT 2023).

Biological INPs are thought to originate from the ocean and meltwater sources during the Arctic Spring and Summer. To assess the potential contribution of these sources to INP active aerosols, aerosols were generated from bulk seawater and sea ice melt water with a temperature-controlled sea spray simulation chamber. The presence of microorganisms in the bulk water and aerosol was quantified using flow cytometry and qPCR while the composition of the microbial communities was determined by amplicon sequencing. Additionally, fluorescent bioaerosols generated by the chamber were  analyzed using a Multiparameter Bioaerosol Spectrometer (MBS). Simultaneously, ambient air samples were analyzed for the presence of microbial cells, bioaerosols, and the composition of the collected microbial community. The ice nucleating properties of water, sea ice melt, and aerosols from the chamber and ambient aerosol were also measured to determine their relevance for Arctic cloud formation.

Preliminary results from the ambient measurements revealed low concentrations of airborne bacterial cells and highly active INPs. From the sea spray simulations, we found that ice melt, snow melt and seawater samples generated a high flux of bacterial cells which were accompanied by INPs active predominantly at low freezing temperatures (<-15°C). Therefore, it seems that the local sea spray is not a likely source of proteinaceous INPs detected in the Arctic spring atmosphere, which will be further explored through bacterial community analysis. Our results will thus provide comprehensive insights into the contribution of local and long-range transported sources of bioaerosols to the Arctic.

How to cite: Schmidt, J. S., Glasius, M., Mavis, C., Creamean, J., Freitas, G., Zieger, P., Finster, K., and Šantl-Temkiv, T.: The composition and sources of airborne bacteria and proteinaceous Ice Nucleating Particles in the High Arctic marine region during Spring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17193, https://doi.org/10.5194/egusphere-egu24-17193, 2024.

EGU24-17589 | Posters on site | AS4.2

Intense formation of low liquid clouds over the Arctic sea-ice during May.   

Jean Lac and Hélène Chepfer

Low-liquid stratiform clouds are ubiquitous in the Arctic. Their high surface longwave warming induces change in the surface radiative budget that might have effects on the sea-ice melt especially during transitioning seasons. In particular, low liquid clouds formed in Spring may trigger early melt onset that might have an impact on the following evolution of the sea-ice during summer. 

However, relatively little is known about the existence and the drivers of such clouds in the early melt season. Here we used 13 years of space based lidar cloud profile observations with complementary data to show that the predominance of low clouds happens in May. First, we showed that the low cloud fraction reaches 75% of the Arctic Ocean in May over the sea-ice only with a low interannual variability. This cover increase in May seems to be homogeneous over the whole Arctic Ocean. Second, we investigated potential early summer drivers forming those low liquid clouds. One feature is the moisture sources that could explain the availability of such liquid droplets to form liquid clouds. While the other feature is the boundary layer structure, that might affect the stability and the ocean/atmosphere interaction over sea-ice leads.  

Overall, this study suggests a peak of Arctic low liquid clouds occurring in May that might impact the sea-ice summer melt by triggering early Spring melt. 

How to cite: Lac, J. and Chepfer, H.: Intense formation of low liquid clouds over the Arctic sea-ice during May.  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17589, https://doi.org/10.5194/egusphere-egu24-17589, 2024.

EGU24-17977 | ECS | Posters on site | AS4.2

Springtime observations of black carbon aerosols in and outside of low-level Arctic clouds 

Lovisa Nilsson, August Thomasson, Paul Zieger, Julia Asplund, Pontus Roldin, Fredrik Mattson, Erik Ahlberg, and Erik Swietlicki

Few expeditions have ventured into the Arctic to observe the processes that take place in the transition from winter to summer. Particularly, direct observations of aerosol-cloud interactions are scarce, and comprise a large source of uncertainty in radiative forcing estimations in the Arctic.

Light absorbing aerosol particles, such as black carbon (BC) from incomplete combustion, exert a positive forcing upon direct absorption of sunlight, and affect clouds by serving as cloud condensation nuclei (CCN). During the icebreaker expedition ARTofMELT in spring 2023, we measured BC with a multi-angle absorption photometer (MAAP) and a single particle soot photometer (SP2) for five weeks. The two instruments differ by principle and can be used to inform on complementary aspects of the light absorbing aerosol. For example, the MAAP provides the total mass concentrations of so-called equivalent BC (eBC), whereas the single particle instrument SP2 determines the mass of individual refractory BC (rBC) aggregates. Most of the time, the MAAP and SP2 sampled the total BC concentration on the same inlet (whole-air). However, during cloud-events, the SP2 measured downstream of a counterflow virtual impactor (CVI) inlet that samples just cloud droplets or ice crystals without the interstitial or non-activated aerosol.

Our first results indicate overall low out-of-cloud BC mass concentrations for both instruments (median and interquartile range, IQR: 4.4 (1.6-8.5) ngm-3 for the MAAP and 2.5 (1.2-4.7) ngm-3 for the SP2). The variation in mass concentration was small, although the tendency of a gradual decrease was observed towards the onset of the melt.

The SP2 instrument enables studies of the BC mass size distribution. For example, during a cloud event we observed that the geometric mean diameter (GMD, mass equivalent diameter) shifted from smaller (171 nm, whole-air inlet) to larger sizes (175-192 nm), as the SP2 switched to sampling the cloud-residual BC (CVI inlet). Further investigation is needed to examine the underlying causes for this observation (e.g. variation in airmass origin). 

The total aerosol concentration is influenced by local natural sources and production from gaseous precursors, as opposed to the BC concentration which is mainly affected by anthropogenic activities. BC source footprints from the Lagrangian dispersion model FLEXPART, indicate little influence from industrialized regions during the whole campaign. This may explain the comparably low median concentration of rBC-particles (1.1 cm-3, IQR: 0.5-2.1) to the total aerosol number concentration (in the range ~20-150 cm-3).

How to cite: Nilsson, L., Thomasson, A., Zieger, P., Asplund, J., Roldin, P., Mattson, F., Ahlberg, E., and Swietlicki, E.: Springtime observations of black carbon aerosols in and outside of low-level Arctic clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17977, https://doi.org/10.5194/egusphere-egu24-17977, 2024.

EGU24-19851 | ECS | Orals | AS4.2

Characteristics of natural Arctic aerosols emitted from a wide range of local sources during ARTofMELT2023 

Gabriel Freitas, Kouji Adachi, Julia Asplund, Jessie Creamean, Fredrik Mattsson, Camille Mavis, Lovisa Nilsson, Matthew Salter, Jennie Spiecker Schmidt, Tina Šantl-Temkiv, and Paul Zieger

The Arctic has been experiencing a rise in ambient temperature several times higher than the global average. This warming trend has led to a continuous decline in sea ice coverage and snowpack prevalence. Aerosol sources, such as those from the open ocean and tundra, have become more prevalent throughout the year. These sources emit primary biological aerosol particles (bioaerosols) some of which exhibit ice nucleating properties at high temperatures (>-15C). Ice nucleating particles (INPs) play a crucial role in cloud ice formation, affecting cloud physical and optical properties, as well as their lifetime. Consequently, this has a substantial impact on the Arctic climate. 

During the ARTofMELT2023 expedition (“Atmospheric Rivers and the Onset of Sea Ice Melt 2023”) conducted aboard the Swedish icebreaker Oden in the Atlantic sector of the Arctic Ocean, we assessed the relative importance of several natural bioaerosol sources, such as sea ice, snow melt (to simulate melt ponds) and bulk ocean water. This involved several sea spray simulation chamber and nebulizer experiments, referred to as “source experiments”. The aerosol particles generated in the 61 source experiments conducted were analyzed using single-particle ultraviolet fluorescence spectroscopy along with other complementary aerosol measurements. These included particle size, black carbon content, particle chemical composition, as well as the microbial community and INP concentration of emitted particles. Additionally, filter samples were obtained for transmission electron microscopy (TEM) analysis. 

Our findings indicate that sea ice and snow melt are more significant sources of bioaerosols compared to the bulk ocean water, including the sea surface microlayer, indicating the potential importance of melt ponds as a local Arctic bioaerosol source. Furthermore, we found significant differences in the chemical composition, black carbon content and size distribution of the various analyzed aerosol sources.

How to cite: Freitas, G., Adachi, K., Asplund, J., Creamean, J., Mattsson, F., Mavis, C., Nilsson, L., Salter, M., Spiecker Schmidt, J., Šantl-Temkiv, T., and Zieger, P.: Characteristics of natural Arctic aerosols emitted from a wide range of local sources during ARTofMELT2023, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19851, https://doi.org/10.5194/egusphere-egu24-19851, 2024.

EGU24-19946 | Orals | AS4.2 | Highlight

Helicopter borne measurements during melt onset in the Fram strait as part of ARTofMELT23 

Falk Pätzold, Lutz Bretschneider, Magnus Asmussen, Barbara Altstädter, Evelyn Jäkel, Hendrik Stapel, Tim Sperzel, Manfred Wendisch, Birgit Wehner, Ralf Käthner, and Astrid Lampert

In the Arctic climate system, the onset of melting is a crucial point, and timing is still difficult to predict. Therefore, the expedition ARTofMELT was dedicated to exploring atmospheric conditions and processes that are involved in triggering the onset of melting.

The helicopter borne sensor system HELIPOD was deployed in this expedition to measure the spatial variability of atmospheric dynamics, radiation, aerosols, trace gases and surface properties on a horizontal scale up to 40 km around the icebreaker ODEN. During the ARTofMELT23 expedition, the HELIPOD conducted 12 measurement flights in the FRAM strait around 80° North and the prime meridian between 9 May and 9 June 2023 with 26.5 hours in the air. The flights covered an area of about 20 NM around the location of the icebreaker ODEN and a vertical range from 50 m to 2700 m above sea level. The flight patterns were aligned parallel and perpendicular to dominating directions as the sea ice edge and the wind direction. In one case a cloud layer edge apparently structured the atmospheric situation. The flights covered pre-melt onset conditions, refreezing situations and the melt onset. Synoptic air mass changes were probed as well.    

The presentation gives an overview of the temporal changes of the ambient conditions during the research flights, and a first assessment of the flights during transient weather situations.

How to cite: Pätzold, F., Bretschneider, L., Asmussen, M., Altstädter, B., Jäkel, E., Stapel, H., Sperzel, T., Wendisch, M., Wehner, B., Käthner, R., and Lampert, A.: Helicopter borne measurements during melt onset in the Fram strait as part of ARTofMELT23, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19946, https://doi.org/10.5194/egusphere-egu24-19946, 2024.

EGU24-20594 | Posters on site | AS4.2

Sea ice, snow caps, and freshwater lenses: The hurdles local Arctic aerosols must overcome to become airborne 

Jessie Creamean and the MOSAiC and ARTofMELT field teams

Aerosol particles and clouds play a critical role in regulating radiation reaching the Arctic, which is warming faster than anywhere else globally. However, the magnitude of their effects is not adequately quantified, especially in the Arctic Ocean over sea ice. Specifically, particles generated from open leads, melt ponds, and the snow-covered sea ice surfaces remain poorly understood, yet could have significant impacts on cloud condensation nuclei (CCN) and ice nucleating particle (INP) concentrations, and thus, central Arctic cloud formation. While marine biological processes have been demonstrated to be potentially key primary aerosol sources in the Arctic summer, exact sources and emission processes of these particles remain highly uncertain. 

For this presentation, we provide an overview of aerosol observations from two recent Arctic field campaigns: the 2019–2020 Multidisciplinary drifting Observatory for Study of Arctic Climate (MOSAiC) and the 2023 Atmospheric rivers and the onset of Arctic melt (ARTofMELT) expeditions. We highlight preliminary findings focused on aerosols that have the potential to impact cloud phase and lifetime over the Arctic Ocean, specifically those from local sources in the early spring and summer melt periods. The evolution of open water within the pack ice in late spring and the Arctic melt season coincides with an increase in aerosol particle concentration, which may be attributed to biological activity within seawater and sea ice. However, the emission of aerosol particles is contingent on features like open leads and melt ponds, and whether they are covered by snow, freshwater melt layers, or ice lids. This integrative study involves the use of detailed aerosol, meteorological, oceanographic, and sea ice observations from MOSAiC and ARTofMELT. Overall, this work will enable us to assess local aerosol processes associated with cloud formation to better understand the Arctic system through a holistic approach.

How to cite: Creamean, J. and the MOSAiC and ARTofMELT field teams: Sea ice, snow caps, and freshwater lenses: The hurdles local Arctic aerosols must overcome to become airborne, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20594, https://doi.org/10.5194/egusphere-egu24-20594, 2024.

EGU24-21926 | Posters on site | AS4.2

Water Isotope measurements contribute to the understanding of atmospheric, sea ice, ocean interactions during the ArtofMelt expedition, Fram Strait, spring 2023 

Jeff Welker, Ben Kopec, Eric Klein, Julia Muchowski, Timo Vihma, Paul Zieger, Falk Paetzold, Astrid Lampert, Penny Vlahos, John Prytherch, Valtteri Hyöky, and Truls Karlsen

Transitions periods between seasons in the Arctic are phases when the atmosphere-sea ice-ocean interactions are heightened, especially during these periods of exceptional warming.  These transition periods may be accompanied by shifts in atmospheric transport patterns, the distribution of sea ice and extreme events, such as atmospheric rivers.  Atmospheric Rivers may act as accelerants of sea ice melt and its redistribution, leading to spatial complexity in ice-ocean-atmosphere exchanges of mass and energy.

As part of an interdisciplinary team aboard the I/B Oden from early May to mid-June, four main water isotope measurement packages were collected to maximize collaborations and to resolve nuisances of the Arctic System throughout the cruise track between Svalbard and NE Greenland (Figure 1).  First, in order to delineate longitudinal distribution of the warm and salty W Svalbard current compared to the cold and fresh E Greenland current, we continuously measured the near surface water δ18O, δ2H and d-excess values. Second, in order to source water vapor and moisture sources from the warm, moist, and isotopically enriched subpolar & N Atlantic, compared to cold, dry and isotopically depleted Arctic air, we also continuously measured the δ18O, δ2H and d-excess values of water vapor collected from the ship’s, bow-mounted, eddy covariance tower. Third, in order to understand the horizontal and altitudinal patterns of water vapor parcels that surround the ship; in-situ water vapor isotopes were measured during fHeliPod flight lines that extended up to 30 km N-S-E-W of the Oden and from ~ 50 m above the sea ice and open water to over 2k in altitude.  Fourth, in order to delineate the source of moisture (sea water vs. meteoric water) throughout the sea ice core profiles and the patterns and sources of moisture in the snow pack profiles; ice cores and snow pits were collected (drilled) and dug at ~10 different locations and water isotope samples were analyzed for δ18O, δ2H and d-excess values back in the laboratory.

Four major discoveries will be presented: A) mixing of the surface W Svalbard and NE Greenland current is found to be farther east than previously reported and the surface water masses may differ by up to 5 ‰ δ18O during spring; B) water vapor isotopes responded at hourly time scales as moisture sources during Atmospheric River events begin with northward fluxes of warm, moist air masses but passing cyclones deliver N-S cold-dry, isotopically depleted water vapor in extreme Arctic-sourced storm events lasting a day or more; C) Horizontal and vertical transects during Heliopod flights captured horizontal and altitudinal variation in water vapor isotopes during periods when the weather of the ship was dominated by cold-dry Arctic air, interrupted by periods when the ship was experiencing pulses of warm, moist, and high humidity conditions; D) ice cores and snow packs exhibit vertical isotopic variation indicative of different moisture sources and morphogenesis processes.

How to cite: Welker, J., Kopec, B., Klein, E., Muchowski, J., Vihma, T., Zieger, P., Paetzold, F., Lampert, A., Vlahos, P., Prytherch, J., Hyöky, V., and Karlsen, T.: Water Isotope measurements contribute to the understanding of atmospheric, sea ice, ocean interactions during the ArtofMelt expedition, Fram Strait, spring 2023, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21926, https://doi.org/10.5194/egusphere-egu24-21926, 2024.

EGU24-926 | ECS | Posters on site | CR2.2

Simulating the impact of an AMOC weakening on the Antarctic Ice Sheet using a coupled climate and ice sheet model 

Anna Höse, Moritz Kreuzer, Willem Huiskamp, Torsten Albrecht, Stefan Petri, Ricarda Winkelmann, and Georg Feulner

Many model studies show that a shutdown of the Atlantic meridional overturning circulation (AMOC) causes reduced northward heat transport into the North Atlantic and a warming Southern Ocean in addition to shifts in large-scale atmospheric circulations. How these changing climate conditions could influence the present-day state of the Antarctic Ice Sheet is little studied even though observational data of AMOC strength show a slowdown trend over the last decades. The ocean current as well as the Antarctic Ice Sheet might reach climate tipping points triggering irreversible processes with consequences already on human time-scales. It's unclear whether increasing Southern Ocean temperatures due to a AMOC shutdown could accelerate basal melting rates, the critical parameter which in turn may induce tipping of the West Antarctic Ice Sheet.

Here, a freshwater hosing that forces the shutdown of the AMOC is applied to the North Atlantic in a global climate model with an interactive ice sheet model for Antarctica. This model framework consists of the Parallel Ice Sheet Model (PISM) that is coupled to the CM2Mc global Earth system model via the ice shelf cavity model PICO (Potsdam Ice-shelf Cavity mOdel). PISM is interactively coupled to the ocean module in order to investigate feedbacks at the ice-ocean boundary, while the atmospheric forcing is prescribed. Preliminary results show that an AMOC shutdown results in warming sea surface temperatures in the southern hemisphere along with a small shift in the mid-latitude westerlies due to reduced northward heat transport, which is in line with previous studies. Antarctic marginal temperatures decrease, however, resulting in a reduction of Antarctic mass through increased calving and decreased basal melting.

How to cite: Höse, A., Kreuzer, M., Huiskamp, W., Albrecht, T., Petri, S., Winkelmann, R., and Feulner, G.: Simulating the impact of an AMOC weakening on the Antarctic Ice Sheet using a coupled climate and ice sheet model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-926, https://doi.org/10.5194/egusphere-egu24-926, 2024.

EGU24-966 | ECS | Orals | CR2.2

Greenland Ice Sheet evolution during the Last Interglacial with an improved surface mass balance modeling approach  

Thi Khanh Dieu Hoang, Aurélien Quiquet, Christophe Dumas, Andreas Born, and Didier M. Roche

The Last Interglacial period (LIG) (130 - 116 kaBP), characterized by higher global mean temperature and sea levels compared to the present-day due to the Earth’s orbit configuration, has been well-studied as a recent example of a climate period warmer than today. There is particular interest in studying the ice sheet-climate interactions in view of our current climate change. However, the extent of the ice sheet and its contribution to the rise of sea levels during the LIG remain debatable as different approaches suggest a wide range of estimations. In order to cover such a long period, some processes are simplified in the modeling approach by using prescribed forcings, simple surface mass balance (SMB) schemes, or equilibrium simulations, which all affect the numerical estimation of ice sheet evolution. 

In our work, to perform transient simulations, we use an Earth system model of intermediate complexity (iLOVECLIM), which has been widely used to study various long-timescale periods. Additionally, we use a physically-based energy and mass balance model with 15 vertical snow layers BESSI (BErgen Snow Simulator) to account for the effect of insolation changes as well as snow-albedo feedback. The climate forcings of the snow model are obtained by running iLOVECLIM transiently from 135 to 115 kaBP, downscaled over the Northern Polar region. Using the SMB computed by BESSI, we then simulate the ice sheet evolution during the LIG with GRISLI - the ice sheet model in the iLOVECLIM framework. 

To assess the benefits of using a physically-based SMB model in the ice sheets simulation, the outputs of GRISLI-BESSI are compared to the current SMB scheme of iLOVECLIM, a simple parametrization called ITM (Insolation Temperature Melt). The Greenland ice sheet volume simulated by the two SMB models reaches the minimum value at 127.5 kaBP, around 500 years after the peak of global mean temperature. The magnitude of ice sheet retreat and its contribution to the sea level in ITM simulations are significantly higher than in BESSI due to an overestimation of the zones of ablation. 

The findings suggest that, compared to a parameterization, we have more confidence in the ice sheet estimation with a physically-based SMB model. Further works with fully interactive ice sheet modeling that takes into account the melt-elevation feedback can improve the simulation of the ice sheet-climate interactions of long-time scales. 

How to cite: Hoang, T. K. D., Quiquet, A., Dumas, C., Born, A., and Roche, D. M.: Greenland Ice Sheet evolution during the Last Interglacial with an improved surface mass balance modeling approach , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-966, https://doi.org/10.5194/egusphere-egu24-966, 2024.

EGU24-1991 | ECS | Orals | CR2.2 | Highlight

When will the Antarctic ice shelves not be viable anymore? 

Clara Burgard, Nicolas C. Jourdain, Christoph Kittel, Cyrille Mosbeux, Justine Caillet, and Pierre Mathiot

The Antarctic contribution to sea-level rise in the coming centuries remains very uncertain, due to the possible triggering of instabilities such as the Marine Ice Sheet Instability (MISI) and Marine Ice Cliff Instability (MICI). These instabilities are mainly linked to the evolution of the floating ice shelves, which usually buttress the ice flow from the ice-sheet to the ocean. However, these are currently thinning. Better understanding the evolution of ice shelves in the next decades to centuries is therefore important and crucial to better anticipate the evolution of sea-level rise.

In this study, we investigate the viability of ice shelves for a number of climate models and scenarios. This is estimated from the emulation of the surface and basal mass balance of MAR and NEMO respectively, and from high-end dynamical ice flows obtained through Elmer/Ice. We then use a Bayesian calibration to give weight to members closer to observations. We find that large uncertainties remain, mainly because of the uncertainty in basal melt, and that viability limits vary largely depending on the ice-shelf location.

How to cite: Burgard, C., Jourdain, N. C., Kittel, C., Mosbeux, C., Caillet, J., and Mathiot, P.: When will the Antarctic ice shelves not be viable anymore?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1991, https://doi.org/10.5194/egusphere-egu24-1991, 2024.

EGU24-3666 | Orals | CR2.2

Deciphering Antarctic Ice Sheet Mass Loss: A Modeling Approach to Distinguish Climate Change from Natural Variability 

Johanna Beckmann, Hélène Seroussi, Lawrence Bird, Justine Caillet, Nicolas Jourdain, Felcity McCormack, and Andrew Mackintosh

The Antarctic Ice Sheet (AIS) is currently undergoing accelerated mass loss, significantly contributing to rising sea levels (SLR). Despite numerous observations, uncertainties persist in understanding the drivers and dynamic responses of AIS mass loss. Climate variability strongly influences AIS dynamics, but limited observational data hinders precise attribution to climate change or natural variability. This study addresses this gap by employing advanced modeling techniques to assess the extent to which observed and future AIS mass loss can be attributed to climate change versus variability. Utilizing a unique "initialization method" with the ISSM model, we approximate the AIS state circa 1850, a period minimally affected by anthropogenic forces. From this baseline, we project AIS development using UKESM1 forcing, comparing scenarios with and without anthropogenic influence. This investigation aims to enhance our understanding of the impact of climate change on the AIS and its implications for future SLR.

How to cite: Beckmann, J., Seroussi, H., Bird, L., Caillet, J., Jourdain, N., McCormack, F., and Mackintosh, A.: Deciphering Antarctic Ice Sheet Mass Loss: A Modeling Approach to Distinguish Climate Change from Natural Variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3666, https://doi.org/10.5194/egusphere-egu24-3666, 2024.

EGU24-4093 | ECS | Posters on site | CR2.2

Interactions between ocean circulation and the Northern Hemisphere ice sheets at 40 ky B.P. in an Earth System Model (iLOVECLIM-GRISLI) 

Louise Abot, Claire Waelbroeck, Aurélien Quiquet, Casimir Delavergne, and Nathaelle Bouttes

During the last glacial period, the climate went through rapid fluctuations together with changes in ocean circulation and ice sheets volume accompanied by iceberg discharges. These rapid climate variations, namely Dansgaard-Oeschger events, are still not fully explained. This study’s aim is to contribute to their better understanding, focusing on interactions between ice sheets and ocean circulation. To this end, we use the iLOVECLIM-GRISLI coupled climate-ice sheet model and run two different perturbation experiments related to the ice sheet and ocean components. Starting from a quasi equilibrium corresponding to 40 ky B.P. greenhouse gas concentration, incoming solar radiation and ice sheet volume, the first experiment consists in imposing either constant or amplified sub-shelf melt rates in comparison with the control simulation. In the second experiment, we focus on the interface between the ice sheets and the bedrock. The basal friction coefficient values are imposed following the same procedure. These two experiments are similar to freshwater hosing experiments but here the water comes directly from the interactively computed ice sheets change. For each experiment, the perturbation is imposed for 500 years before returning to the unperturbed conditions for one thousand years and its impacts on the climate system are investigated. Our results highlight feedbacks that may help to explain the abrupt nature of the climate transitions observed during the last glacial period. 

How to cite: Abot, L., Waelbroeck, C., Quiquet, A., Delavergne, C., and Bouttes, N.: Interactions between ocean circulation and the Northern Hemisphere ice sheets at 40 ky B.P. in an Earth System Model (iLOVECLIM-GRISLI), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4093, https://doi.org/10.5194/egusphere-egu24-4093, 2024.

EGU24-4802 | Orals | CR2.2

A synchronously coupled global model iOM4: a new modeling tool for simulations of the ocean-cryosphere interactions  

Olga Sergienko, Matthew Harrison, Alexander Huth, and Nicole Schlegel

How to cite: Sergienko, O., Harrison, M., Huth, A., and Schlegel, N.: A synchronously coupled global model iOM4: a new modeling tool for simulations of the ocean-cryosphere interactions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4802, https://doi.org/10.5194/egusphere-egu24-4802, 2024.

EGU24-5104 | ECS | Posters on site | CR2.2

Simulating Antarctic Ice Sheet evolution through the mid-Pleistocene transition 

Christian Wirths, Antoine Hermant, Christian Stepanek, Johannes Sutter, and Thomas Stocker

Unravelling the main drivers of the mid-Pleistocene transition (MPT; around 1.2–0.8 million years ago) remains a significant challenge in paleoclimate research. Noteworthy changes that occurred in the climate system during that time include a pronounced shift from 41-kyr to 100-kyr periodicity of glacial cycles and the emergence of much larger ice sheets. While a number of studies have focused on the interplay between the climate system and northern hemispheric ice sheets during the MPT, the role of Antarctica in driving and responding to climate change at that time remains largely unknown. This is particularly relevant as, consequently, the response of Antarctica’s vast ice sheets to a major transition in Quaternary climate, and their potential role in shaping the transition, remain uncertain. 

Here, we use the Parallel Ice Sheet Model (PISM) to simulate the transient evolution of the Antarctic Ice Sheet through the MPT. Computation of the evolution of ice sheets in PISM is enabled by means of a climate index approach that is based on snapshots of climatic conditions at key periods. The climate index approach interpolates between individual climate snapshots based on various paleo-proxy records. Further, we test Antarctica's response to different pre-MPT GCM snapshots of different CO2, orbital, and land-sea mask configurations. Climate snapshots are derived from the Community Earth System Models (COSMOS), a general circulation model that simulates atmosphere, ocean, sea ice and land vegetation in dependence of reconstructions of paleogeography, orbital configuration, and greenhouse gas concentrations.  

Our study aims to better understand the evolution of the Antarctic Ice Sheets during the MPT and to constrain potential dynamical transitions in the climate-cryosphere system. Furthermore, we seek to clarify the influence of different pre-MPT ice sheet configurations on simulated characteristics of this transition.  

The findings from this study will contribute to an improved understanding of cryospheric changes that occurred during the Quaternary. Furthermore, we aim to provide insights into potential future Antarctic trajectories under anthropogenic climate change. 

How to cite: Wirths, C., Hermant, A., Stepanek, C., Sutter, J., and Stocker, T.: Simulating Antarctic Ice Sheet evolution through the mid-Pleistocene transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5104, https://doi.org/10.5194/egusphere-egu24-5104, 2024.

EGU24-5525 | Orals | CR2.2

Modeling the Antarctic Surface Mass Balance with a coarse temporal resolution 

Enrico Maiero, Florence Colleoni, Cécile Agosta, Carlo Barbante, and Barbara Stenni

Sublimation is the most important ablation term in the Antarctic Surface Mass Balance (SMB) (Agosta et al., 2019), while it is currently negligible for both Greenland and mountain glaciers (prevailing surface melt). Since simple parameterized SMB models are usually developed for Greenland and Alpine glaciers, they mostly misrepresent sublimation. To face this problem, we developed EBAL, a new parameterized Energy SMB model for Antarctica based on SEMIC (Krapp et al., 2017), which is an Energy SMB model developed for Greenland whose main innovations are a sinusoidal parameterization for the diurnal cycle to assess melt and refreezing and an albedo dependence on snow depth. EBAL was calibrated with both MAR (Kittel et al., 2022) and RACMO (Wessem et al., 2018) outputs for the period 1979-2000 and for the period 2075-2099 under the SSP5-8.5. EBAL can reproduce the statistical properties of MAR and RACMO sublimation time series and spatial distribution even if it uses a coarse time step (1 day). However, our final aim is to use EBAL for paleoclimate simulations, for which the temporal resolution of the inputs is even coarser, as often only monthly data is available. Thus, we have tested the idea of superimposing the present day-to-day variability on the MAR monthly atmospheric forcing of SSP5-8.5. Simulated SMB with EBAL forced with MAR original daily SSP5-8.5 inputs leads to a 210 Gt/yr sublimation, and to a 1425 Gt/yr melt. When forcing EBAL with monthly means only (linearly interpolated), we obtain a 113 Gt/yr sublimation and a 620 Gt/yr melt. When adding present-day variability to linearly interpolated monthly inputs, EBAL computes a 175 Gt/yr sublimation and a 1386 Gt/yr melt. Those latter numbers are very similar to those obtained when forcing with daily inputs. We propose to use this method to test EBAL for paleoclimate applications.

References

  • Agosta, C. et al., (2019). “Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979–2015) and identification of dominant processes”. The Cryosphere. 13,  pp. 281-296. 10.5194/tc-13-281-2019. 
  • Kittel, C. et al., (2022). “Clouds drive differences in future surface melt over the Antarctic ice shelves”. The Cryosphere. 16, pp. 2655-2669. 10.5194/tc-16-2655-2022.
  • Krapp, M et al., (July 2017). “SEMIC: an efficient surface energy and mass balance model applied to the Greenland ice sheet”. The Cryosphere 11.4, pp. 1519–1535. 10.5194/tc-11-1519-2017
  • Wessem, J. M. et al., (Apr. 2018). “Modelling the climate and surface mass balance of polar ice sheets using RACMO2 – Part 2: Antarctica (1979–2016)”. The Cryosphere 12, pp. 1479–1498. 10.5194/tc-12-1479-2018

How to cite: Maiero, E., Colleoni, F., Agosta, C., Barbante, C., and Stenni, B.: Modeling the Antarctic Surface Mass Balance with a coarse temporal resolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5525, https://doi.org/10.5194/egusphere-egu24-5525, 2024.

EGU24-5584 | Orals | CR2.2

Future Greenland melt in coupled ice sheet-climate CESM simulations: feedbacks, thresholds, reversibility 

Miren Vizcaino, Thirza Feenstra, Michele Petrini, Raymond Sellevold, Georgiou Sotiria, Katherine Thayer-Calder, William Lipscomb, and Julia Rudlang

Estimates of future Greenland ice sheet (GrIS) melt are mostly based on regional climate modelling for a fixed GrIS topography or on ice sheet modelling with forcing from climate models. This prevents the modelling of climate and GrIS feedbacks and other types of interaction. Here we examine a set of multi-century simulations with the Community Earth System Model featuring an interactive GrIS to explore future relationship between global climate change and ice sheet change. To this end, we compare a set of coupled CESM-CISM 1% CO2 increase simulations until stabilization at two, two and a half, three and four times pre-industrial CO2 levels to examine the sensitivity of the GrIS to emission mitigation. Here we find a large role of ocean circulation weakening and associated regional climate changes on GrIS melt for moderate emission scenarios and large melt differences between the three times and four times CO2 stabilization scenarios. In addition, we examine the role of feedbacks on ice sheet evolution by comparing a 1% to 4xCO2 coupled simulation with a simulation where the GrIS topography and meltwater fluxes to the ocean are prescribed as pre-industrial. Finally, we explore the effects on GrIS melt rates of a fast 5% CO2 reduction from four times to pre-industrial levels, with a focus on restoration of high latitude climate, GrIS albedo, surface energy fluxes and refreezing capacity.  

How to cite: Vizcaino, M., Feenstra, T., Petrini, M., Sellevold, R., Sotiria, G., Thayer-Calder, K., Lipscomb, W., and Rudlang, J.: Future Greenland melt in coupled ice sheet-climate CESM simulations: feedbacks, thresholds, reversibility, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5584, https://doi.org/10.5194/egusphere-egu24-5584, 2024.

EGU24-5698 | ECS | Posters on site | CR2.2

Geoengineering's role in reducing future Antarctic mass loss is unclear 

Mira Adhikari, Daniel Martin, Tamsin Edwards, Antony Payne, James O'Neill, and Peter Irvine

Using the BISICLES ice sheet model, we compare the Antarctic ice sheet’s response over the 22nd century in a scenario where idealised large scale, instantaneous geoengineering is implemented in 2100 or 2050 (geoengineering), with scenarios where the climate forcing is held constant in the same year (stabilisation). Results are highly climate model dependent, with larger differences between models than between geoengineering and stabilisation scenarios, but show that geoengineering cannot prevent significant losses from Antarctica over the next two centuries. If implemented in 2050, sea level contributions under geoengineering are lower than under stabilisation scenarios. If implemented in 2100, under high emissions, geoengineering produces higher sea level than stabilisation scenarios, as increased surface mass balance in the warmer stabilisation scenarios offsets some of the dynamic losses. Despite this, dynamic losses appear to accelerate and may eventually negate this initial offset, indicating that beyond 2200, geoengineering could eventually be more effective.

How to cite: Adhikari, M., Martin, D., Edwards, T., Payne, A., O'Neill, J., and Irvine, P.: Geoengineering's role in reducing future Antarctic mass loss is unclear, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5698, https://doi.org/10.5194/egusphere-egu24-5698, 2024.

EGU24-6140 | ECS | Orals | CR2.2

Long term ice-sheet albedo feedback constrained by most recent deglaciation 

Alice Booth, Philip Goodwin, and Bb Cael

Slow climate feedbacks that operate on timescales of more than a century are currently underrepresented in model assessments of climate sensitivity, and this continues to hinder efforts to accurately predict future climate change beyond the end of the 21st Century. As such, the magnitude of multi-centennial and millennial climate feedbacks are still poorly constrained. We utilise recent reconstructions of Earth’s Energy Imbalance (EEI) to estimate both the total climate feedback parameter and the ice-sheet albedo feedback since the Last Glacial Maximum. This new proxy-based record of EEI facilitates the first opportunity to simultaneously calculate both the magnitude and timescale of Earth’s climate feedback over the most recent deglaciation using a purely proxy data-driven approach, and without the need for simulated reconstructions. We find the ice-sheet albedo feedback to have been an amplifying feedback reaching an equilibrium magnitude of 0.55 Wm-2K-1, with a 66% confidence interval of 0.45 Wm-2K-1 to 0.63 Wm-2K-1. The timescale for the ice-sheet albedo feedback to reach equilibrium is estimated as 3.61Kyrs, with a 66% confidence interval of 1.88Kyrs to 5.48Kyrs. These results provide new evidence for the timescale and magnitude of the amplifying ice-sheet albedo feedback that will continue to drive anthropogenic warming for millennia to come, further increasing the urgency for an effective climate change mitigation strategy to avoid serious long-term consequences for our planet and its ecosystems.

How to cite: Booth, A., Goodwin, P., and Cael, B.: Long term ice-sheet albedo feedback constrained by most recent deglaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6140, https://doi.org/10.5194/egusphere-egu24-6140, 2024.

EGU24-7415 | ECS | Orals | CR2.2 | Highlight

Stability regimes and safe overshoots in West and East Antarctica 

Ann Kristin Klose and Ricarda Winkelmann

Earth's climate will likely exceed a warming of 1.5°C in the coming decades. Maintaining such warming levels for a longer period of time may pose a considerable risk of crossing critical thresholds in Antarctica and, thereby, triggering self-sustained, potentially irreversible ice loss, even if the forcing is reduced in a temperature overshoot. Due to the complex interplay of several amplifying and dampening feedbacks at play in Antarctica, the duration and amplitude of such warming overshoots as well as their eventual 'landing' climate will determine the long-term evolution of the ice sheet.

Using the Parallel Ice Sheet Model, we systematically test for the reversibility of committed large-scale ice-sheet changes triggered by warming projected over the next centuries, and thereby explore (1) the stability regimes of the Antarctic Ice Sheet and (2) the potential for safe overshoots of critical thresholds in Antarctica.

We demonstrate crucial features of the Antarctic Ice Sheet's stability landscape for its long-term trajectory in response to future human actions: Given ice-sheet inertia, an early reversal of climate may allow for avoiding self-sustained ice loss that would otherwise be irreversible (for the same reduction in warming) due to multistability of the ice sheet at the basin- and continental scale. While we show that such safe overshoots of critical thresholds in Antarctica may be possible, it is also clear that limiting global warming is the only viable option to evade the risk of widespread ice loss in the long term.

How to cite: Klose, A. K. and Winkelmann, R.: Stability regimes and safe overshoots in West and East Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7415, https://doi.org/10.5194/egusphere-egu24-7415, 2024.

EGU24-8333 | ECS | Orals | CR2.2

Coupled ensemble simulations of the Northern Hemisphere ice sheets at last two glacial maxima  

Violet Patterson, Lauren Gregoire, Ruza Ivanovic, Niall Gandy, Stephen Cornford, and Sam Sherriff-Tadano

Coupled climate-ice sheet models can capture important interactions between the ice sheets and the climate that can help us better understand an ice sheet's response to changes in forcings. In this respect, they are a useful tool for simulating future ice sheet and sea level changes as a result of climate change. However, such models have large uncertainties related to the choice of climate and ice sheet parameters used. The same processes that operate today, also occurred in glacial times, and previous work has shown that simulating the North American ice sheet at the Last Glacial Maximum (LGM; ~21 ka BP) provides a strong benchmark for testing coupled climate-ice sheet models and recalibrating uncertain parameters that control surface mass balance and ice flow (Gandy et al., 2023).

Here, we build on this work by performing the first coupled FAMOUS-BISICLES simulations of the last two glacial maxima, including all Northern Hemisphere ice sheets interactively. The ice sheet component of this model is capable of efficiently simulating marine ice sheets, such as the Eurasian ice sheet, despite the high computational cost of higher order physics. We simulate and compare both the LGM and the Penultimate Glacial Maximum (PGM; ~140 ka BP), since both periods displayed major differences in the distribution of ice between Eurasia and North America. Uncertainty is explored by running ensembles of 120 simulations, randomly varying the uncertain parameters controlling ice sheet dynamics and climate through Latin Hypercube Sampling. We also work on improving the representation of ice streams in the model through performing internal ice temperature spin ups and sensitivity tests varying till water drainage properties. The ensemble members are evaluated against empirical data on ice sheet extent and ice stream location to find combinations of parameters that produce reasonable simulations of the North American and Eurasian ice sheets for both periods. We determine the impact of the uncertainty in these parameters on the result and whether both ice sheets show similar sensitivities to the model parameters. These simulations will provide a starting point for analysing some of the interactions between the climate and the ice sheets during glacial periods and how they may have led to different ice sheet evolutions.

How to cite: Patterson, V., Gregoire, L., Ivanovic, R., Gandy, N., Cornford, S., and Sherriff-Tadano, S.: Coupled ensemble simulations of the Northern Hemisphere ice sheets at last two glacial maxima , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8333, https://doi.org/10.5194/egusphere-egu24-8333, 2024.

The dynamics of the ice sheets on glacial-interglacial time scales are highly controlled by interactions with the solid Earth, i.e., glacial isostatic adjustment (GIA). Particularly at marine ice sheets, competing feedback mechanisms govern the migration of the ice sheet’s grounding line and hence the ice sheet stability.

In this study, we run coupled ice sheet–solid Earth simulations over the last two glacial cycles. For the ice sheet dynamics we apply the Parallel Ice Sheet Model PISM and for the load response of the solid Earth we use the three-dimensional viscoelastic Earth in view of sea-level and vertical displacement changes we apply the Viscoelastic Lithosphere and Mantle Model VILMA.

With our coupling setup we evaluate the relevance of feedback mechanisms for the glaciation anddeglaciation phases in Antarctica considering different 3D Earth structures resulting in a range of load-response time scales. For rather long time scales, in a glacial climate associated with far-field sea level low stand, we find grounding line advance up to the edge of the continental shelf mainly in West Antarctica, dominated by a self-amplifying GIA feedback, which we call the ‘forebulge feedback’. For the much shorter time scale of deglaciation, dominated by the Marine Ice Sheet Instability, our simulations suggest that the stabilizing GIA feedback can significantly slow-down grounding line retreat in the Ross sector, which is dominated by a very weak Earth structure (i.e. low mantle viscosity and thin lithosphere).

The described coupled framework, PISM-VILMA, allows for defining restart states to which to run multiple sensitivity simulations. It can be easily implemented in Earth System Models (ESMs) and provides the tools to gain a better understanding of ice sheet stability on glacial time scales as wellas in a warmer future climate.

How to cite: Albrecht, T., Bagge, M., and Klemann, V.: Feedback mechanisms controlling Antarctic glacial cycle dynamics simulated with a coupled ice sheet–solid Earth model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9032, https://doi.org/10.5194/egusphere-egu24-9032, 2024.

EGU24-10162 | ECS | Orals | CR2.2

A new climate and surface mass balance product for the Antarctic and Greenland ice sheet using RACMO2.4.1 

Christiaan van Dalum, Willem Jan van de Berg, Srinidhi Nagarada Gadde, and Michiel van den Broeke

Recent progress in parameterizations of surface and atmospheric processes have led to the development of a major update of the polar version of the Regional Atmospheric Climate Model (RACMO2.4.1). Here, we present a new high-resolution climate and surface mass balance product by applying RACMO2.4.1 to the Antarctic and Greenland ice sheet for the historical period (starting in 1960 and 1945, respectively). In addition, RACMO output is now available for the first time on a pan-Arctic domain, starting in 1980. We assess these products by comparing model output of the surface mass balance and its components and the near-surface climate with in-situ and remote sensing observations, and study differences with the previously operational RACMO iteration, RACMO2.3p2. 

Among other changes, RACMO2.4.1 includes new and updated parameterizations related to surface and atmospheric processes. Most major updates are part of the physics package of cycle 47r1 of the Integrated Forecast System (IFS) of the European Center for Medium-Range Weather Forecasts (ECMWF), which is embedded in RACMO2.4.1. This includes updates to the cloud, radiation, convection, turbulence, aerosol and lake scheme. Other major changes are directly related to the cryosphere, such as the introduction of a new spectral albedo and radiative transfer scheme for glaciated snow, fixes to the snow drift scheme, a new multilayer snow scheme for seasonal snow and an updated ice mask. These updates lead to changes in the near-surface climate. For example, the horizontal transport of snow that is present in the atmosphere leads to a redistribution of snowfall. Furthermore, the spatial resolution for the Antarctic domain is increased to 11 km, which is also used for the pan-Arctic domain, while 5.5 km is used for Greenland. Here, we also discuss the impact that aforementioned changes have on the climate of the polar regions and the surface mass balance and its components of the ice sheets.

How to cite: van Dalum, C., van de Berg, W. J., Nagarada Gadde, S., and van den Broeke, M.: A new climate and surface mass balance product for the Antarctic and Greenland ice sheet using RACMO2.4.1, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10162, https://doi.org/10.5194/egusphere-egu24-10162, 2024.

EGU24-10256 | ECS | Orals | CR2.2

Reconstructing the Greenland ice Sheet during the last two deglaciations 

Majbritt Kristin Eckert, Mikkel Lauritzen, Nicholas Rathmann, Anne Solgaard, and Christine Hvidberg

The Parallel Ice Sheet Model (PISM) is used to build up a glacial Greenland ice sheet, simulate the evolution of the Greenland ice sheet through glacial terminations I and II and investigate the evolution during previous warmer climates, the Eemian and the Holocene thermal maximum. During the Holocene, surface elevation changes derived from ice cores suggest a large thinning in the North, suggesting that the Greenland ice sheet was connected to the North American ice sheet in Canada during the last glacial. By including Canada in the modelling domain this thinning in the early Holocene as the connecting ice bridge broke up will be investigated. 

How to cite: Eckert, M. K., Lauritzen, M., Rathmann, N., Solgaard, A., and Hvidberg, C.: Reconstructing the Greenland ice Sheet during the last two deglaciations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10256, https://doi.org/10.5194/egusphere-egu24-10256, 2024.

EGU24-12773 | ECS | Orals | CR2.2

Improved treatment of snow over ice sheets in the NASA GISS climate model: towards ice sheet–climate coupling 

Damien Ringeisen, Patrick Alexander, Lettie Roach, Ken Mankoff, and Igor Aleinov

Representing the interactions between ice sheets and climate is essential for more accurate prediction of climate change and sea level rise. Ice sheets interact with the overlying atmosphere via the accumulation of snow and its compaction into firn, then ice, as well as the melting of surface snow and ice and the creation of runoff water. Getting an adequate representation of heat transfer, compaction, and melting processes is essential for an accurate representation of snow on land ice in global climate models. We are implementing an improved snow model on top of land ice as part of an effort to couple the NASA GISS climate model with the PISM ice sheet model. The new snow model includes additional layers and processes that are not currently incorporated (e.g., liquid water retention, percolation and refreezing, and snow densification), and mass and energy transfer methods that are consistent with both static ice sheets (with implicit iceberg fluxes) and interactive ice sheets (with explicit dynamics). We are tuning the densification scheme of this snow model with temperature and density data from common FirnCover and SumUp observations at locations in the accumulation zone of Greenland, and we compare the resulting density profiles to other SumUp density profiles in Greenland and Antarctica. We will assess the impact of this new snow model in climate model simulations with a static ice sheet compared with the previous (simpler) 2-layer snow model. Finally, we aim to use the non-coupled simulations as a baseline to assess the impact of dynamic coupling with an interactive ice sheet model.

How to cite: Ringeisen, D., Alexander, P., Roach, L., Mankoff, K., and Aleinov, I.: Improved treatment of snow over ice sheets in the NASA GISS climate model: towards ice sheet–climate coupling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12773, https://doi.org/10.5194/egusphere-egu24-12773, 2024.

EGU24-13618 | ECS | Orals | CR2.2

Reconstructing the coupled Greenland Ice Sheet–climate evolution during the Last Interglacial warm period 

Matt Osman, Jessica Tierney, and Marcus Lofverstrom

During the Last Interglacial (LIG), approximately 130-118 thousand years ago (ka), the Arctic experienced relative warmth and global sea levels considerably higher than modern.  While this interval is thus considered key for understanding long-term ice–climate feedbacks under warm-state climate conditions, large uncertainties remain surrounding i. the magnitude and spatial expression of LIG global temperature change, ii. the relative contributions of the Antarctic vs. Greenlandic Ice Sheets (GrIS) to LIG sea level rise, and iii. the sensitivity of the GrIS to centennial- to millennial-scale ocean-atmospheric forcing.  Here, we present, to our knowledge, a first attempt at reconstructing the coupled GrIS–climate evolution during the LIG using an internally consistent offline “paleoclimate data assimilation” approach.  Our methodology combines a newly compiled database of nearly 400 chronologically consistent marine geochemical and ice sheet-derived climate-proxy records (spanning 250 sites globally) with recently developed, state-of-the-art transient simulations of the LIG using the coupled Community Earth System Model v2 featuring an interactive Community Ice Sheet Model v2 (CESM2-CISM2).  Our preliminary assimilations suggest LIG peak global mean surface warming of +0.1-0.5˚C (±2 range) above the pre-industrial state, arising from enhanced and widespread (>2-5˚C) high Arctic warming.  Leveraging our CESM2-coupled CISM2 results, we further identify a max GrIS contribution of 2.0 (±0.6) meters of sea level rise equivalent at around 125 ka, nearly ~two millennia after peak LIG climate forcing.  These initial results provide a new proxy-model integration framework for reconciling past GrIS contributions to global sea level rise and benchmark the potential long-term sensitivity of the GrIS to ongoing Arctic warming.

How to cite: Osman, M., Tierney, J., and Lofverstrom, M.: Reconstructing the coupled Greenland Ice Sheet–climate evolution during the Last Interglacial warm period, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13618, https://doi.org/10.5194/egusphere-egu24-13618, 2024.

Mass loss from ice sheets under the ongoing anthropogenic warming episode is a major source for sea-level rise. Due to the slow responses of ice sheets to changes in atmospheric and oceanic boundary conditions, ice sheets are projected to undergo further retreat as the climate reaches a new equilibrium, producing a long-term commitment to future sea-level rise that is fulfilled on multi-millennial scale. Future projections of ice sheets beyond 2100 have routinely employed end-of-the-century atmosphere-ocean conditions from climate model output under specified emission scenarios. This approach, however, does not account for long-term responses of the climate system to external forcings. Here we analyze the long-term atmospheric and oceanic responses to a variety of emission scenarios in several climate models and show that polar climates may see substantial changes after the atmospheric CO2 level stabilizes. With a 3-D ice sheet model, we demonstrate that the long-term climate responses are crucial for evaluating ice sheets' commitment to future sea-level rise.

How to cite: Li, D.: Effects of long-term climate responses on ice sheets' commitment to future sea-level rise, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15160, https://doi.org/10.5194/egusphere-egu24-15160, 2024.

EGU24-15323 | ECS | Posters on site | CR2.2

Investigating the evolution and stability of the Greenland ice sheet using remapped surface mass balance forcing 

Charlotte Rahlves, Heiko Goelzer, and Michele Petrini

Surface mass balance (SMB) forcing for projections of the future evolution of the Greenland ice sheet with stand-alone modeling approaches is commonly produced on a fixed ice sheet geometry. As changes of ice sheet geometry become significant over longer time scales, conducting projections for the long-term evolution and stability of the Greenland ice sheet usually requires a coupled climate-ice sheet modeling setup. In this study we use an SMB remapping procedure to capture the first order feedbacks of a coupled climate-ice sheet system with a stand-alone modeling approach. Following a remapping procedure originally developed to apply SMB forcing to a range of initial ice sheet geometries (Goelzer et al., 2020), we produce SMB forcing that adapts to the changing ice sheet geometry as it evolves over time. SMB forcing from a regional climate model is translated from a function of absolute location to a function of surface elevation depending on 25 regional drainage basins, thereby reducing biases that would arise by applying the SMB derived from a fixed ice sheet geometry. We use forcing for different emission scenarios from the CMIP6 archive to compare results from the remapping approach with results from commonly used methods of parameterizing the SMB-height feedback, as well as with results from a semi-coupled climate-ice sheet simulation.

How to cite: Rahlves, C., Goelzer, H., and Petrini, M.: Investigating the evolution and stability of the Greenland ice sheet using remapped surface mass balance forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15323, https://doi.org/10.5194/egusphere-egu24-15323, 2024.

EGU24-15401 | Posters on site | CR2.2

Development and implementation of a refined climate index forcing for paleo ice-sheet modeling applications  

Antoine Hermant, Christian Wirths, and Johannes Sutter

The contribution of the Antarctic Ice Sheet (AIS) to sea-level rise under future scenarios remains uncertain. Simulations of the AIS covering past-climate periods provide valuable insights into its response to a range of climatological background states and transitions, as well as its past contributions to sea-level change. However, data to constrain the modelled ice-flow and the paleo-climate forcing is often lacking, leading to considerable uncertainties with respect to paleo ice sheet evolution. Here, we implement and test a framework to provide paleo-climate scenarios for continental scale ice sheet models. Our approach involves the use of an improved climate index based on ice-core records to translate paleo forcing snapshots from Earth System Models and regional models into transient paleo-climate scenarios, specifically to simulate the dynamics of the AIS throughout the last glaciation and deglaciation. Additionally, we refine paleo-accumulation scenarios by introducing a regionally-specific and temperature-dependant scaling of accumulation. Our study aims to enhance our understanding of AIS dynamics on glacial-interglacial time-scales and provide improved paleo-informed initializations for AIS projections. 

How to cite: Hermant, A., Wirths, C., and Sutter, J.: Development and implementation of a refined climate index forcing for paleo ice-sheet modeling applications , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15401, https://doi.org/10.5194/egusphere-egu24-15401, 2024.

EGU24-15987 | ECS | Posters on site | CR2.2

Assessing Antarctic Ice Sheet dynamics under temporary overshoot and long-term temperature stabilization scenarios   

Emma Spezia, Fabrice Kenneth Michel Lacroix, Vjeran Visnjevic, Christian Wirths, Antoine Hermant, Thomas Frölicher, and Johannes Sutter

Current projections of Antarctic Ice Sheet dynamics during the next centuries are subject to large uncertainties both reflecting the ice sheet model setup as well as the climate pathways taken into consideration. Assessing both we present model projections of the Antarctic Ice Sheet’s response to a range of temporary temperature overshoot and stabilization scenarios until the year 2500 accounting for various ice sheet sensitivities. We employ the ice sheet model PISM at continental scale forced by Earth system model data tailored to specific global temperature scenarios via an adaptive greenhouse gas emissions approach. These scenarios reflect both emission pathways which result in a transient temperature overshoot during the 21st and 22nd century as well as stabilization of global temperatures without overshoot. We contrast these simulations with the well- known CMIP6 scenarios to illustrate the diverse potential pathways of Antarctic Ice Sheet dynamics under uncertain future climate trajectories. 

How to cite: Spezia, E., Lacroix, F. K. M., Visnjevic, V., Wirths, C., Hermant, A., Frölicher, T., and Sutter, J.: Assessing Antarctic Ice Sheet dynamics under temporary overshoot and long-term temperature stabilization scenarios  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15987, https://doi.org/10.5194/egusphere-egu24-15987, 2024.

EGU24-16455 | ECS | Posters on site | CR2.2

Ice-dammed lake-glacier interactions: Modelling the impact on Fennoscandian Ice Sheet retreat 

Ankit Pramanik, Sarah Greenwood, Carl Carl Regnéll, and Richard Gyllencreutz

Ice-dammed lakes expedite glacier retreat, leading to the expansion of lakes and an elevated risk of Glacial Lake Outburst Floods (GLOFs), and delay the freshwater inflow to the ocean. The escalating number of ice-dammed lakes in Greenland, High Mountain Asia, and Patagonia, driven by the swift retreat of glaciers amid rapid warming, poses a significant threat of natural disasters. In the geological record, evidence indicates the rapid retreat of the Fennoscandian ice sheet, marked by the formation, expansion, and drainage of large (10s-1000s km2 surface area and up to 100s m deep) ice-dammed proglacial lakes along the entire length of the late-deglacial ice margin. The deglaciation and ice-lake interactions of the Fennoscandian Ice Sheet (FIS) provide a valuable analogue for projecting the future retreat of the Greenland ice sheet, where a manifold increase in the number and volume of ice-dammed lakes is anticipated.

Despite extensive research on marine-terminating glaciers, the dynamics of lacustrine-terminating glaciers remain poorly understood. While there are some notable differences in thermo-mechanical processes between marine and lacustrine glaciers, a significant contrast lies in the fact that the calving of lake-terminating glaciers is governed by the stress balance induced by rapidly fluctuating lake levels and thermodynamics inherent of lakes. Our study delves into accessing the impact of critical factors, such as lake size and bathymetry, on the retreat of the Fennoscandian Ice Sheet, using the Ice-sheet and Sea-level System Model (ISSM). Furthermore, we aim to evaluate the influence of calving, subaqueous melt, and rapidly fluctuating lake levels on the FIS retreat. The model's accuracy will be ensured through calibration and validation against geologically reconstructed ice sheet boundaries and lake levels.

How to cite: Pramanik, A., Greenwood, S., Carl Regnéll, C., and Gyllencreutz, R.: Ice-dammed lake-glacier interactions: Modelling the impact on Fennoscandian Ice Sheet retreat, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16455, https://doi.org/10.5194/egusphere-egu24-16455, 2024.

EGU24-16702 | ECS | Posters on site | CR2.2

Isochronally constrained ice flow evolution of Dronning Maud Land, Antarctica during the Last Glacial Period 

Vjeran Visnjevic, Julien Bodart, Antoine Hermant, Christian Wirths, Emma Spezia, and Johannes Sutter

To improve the robustness of future simulations of ice flow across the Antarctic continent as well as the projections of sea-level rise accompanying it, it is necessary to improve our understanding of the past evolution of ice dynamics. This is specially the case considering the lack of constraints on climate and basal conditions on the regional scale. To address this, we use high resolution regional ice flow modeling combined with radar obtained repositories of internal reflection horizons and ice core data, to constrain the ice flow evolution of both grounded and floating ice across the Dronning Maud Land during the Last Glacial Period. Combining the modeling results obtained using the ice sheet model PISM with radar and ice core data will enable us to improve our knowledge of conditions at the ice base, but also provide an opportunity to test and compare a range of potential climate reconstructions. The presented workflow will further be expanded to other basins in Antarctica as well as to the interglacial-glacial transition, and the results will be used to improve future simulations of ice flow across Antarctica.

How to cite: Visnjevic, V., Bodart, J., Hermant, A., Wirths, C., Spezia, E., and Sutter, J.: Isochronally constrained ice flow evolution of Dronning Maud Land, Antarctica during the Last Glacial Period, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16702, https://doi.org/10.5194/egusphere-egu24-16702, 2024.

EGU24-17391 | ECS | Orals | CR2.2

Critical thresholds of the Greenland Ice Sheet from the LGM to the future 

Lucía Gutiérrez-González, Jorge Alvarez-Solas, Marisa Montoya, Ilaria Tabone, and Alexander Robinson

In recent decades the Greenland Ice Sheet (GrIS) has undergone accelerating ice-mass loss. The GrIS is thought to be a tipping element of the Earth system due to the existence of positive feedbacks with the climate. Previous work has shown threshold behavior in the system, and its stability has been studied in a range of temperatures of the present to a global warming of +4K. However, there is still no consensus on the values of its critical thresholds for the future. Furthermore,  its stability at  lower temperatures hasn’t been studied yet. Here we use the ice-sheet model Yelmo coupled with the regional climate model REMBO and a parametrization of the ice-ocean interactions to obtain the bifurcation diagram of the GrIS from temperatures representative of the LGM (-12K) to a warmer scenario (+4K). The preindustrial simulated equilibrium volume is larger than the observations, a feature common to many other ice-sheet models. This could indicate model biases, but also that the GrIS could currently not be fully in equilibrium with the preindustrial forcing, with implications for future projections. To investigate this issue, we simulated the transient evolution of the GrIS since the LGM to the present day in the context of the bifurcation diagram, with equilibrium states acting as attractors. 

How to cite: Gutiérrez-González, L., Alvarez-Solas, J., Montoya, M., Tabone, I., and Robinson, A.: Critical thresholds of the Greenland Ice Sheet from the LGM to the future, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17391, https://doi.org/10.5194/egusphere-egu24-17391, 2024.

EGU24-18501 | Posters on site | CR2.2

Protocol for a Last Interglacial Antarctic ice-sheet model inter-comparison 

Lauren Gregoire, Maxence Menthon, Edward Gasson, and Louise Sime

During the last interglacial, geological records show evidence that the sea level peaked between 6 and 9 m above pre-industrial sea level, with a major contribution from the Antarctic ice sheet. However, ice-sheet models give a very large range of values due to a lack of understanding of the mechanisms leading to the Antarctic ice sheet retreat during the Last Interglacial

Here, we propose a protocol to apply systematically to multiple ice-sheet models to better understand the climate and ice-sheet model uncertainties as well as mechanisms leading to a smaller Antarctic ice sheet. We present the climate forcing choices and methodology, ice-sheet model requirements and the group of simulations suggested. The protocol includes transient penultimate deglaciation and last interglacial equilibrium simulations to make it accessible to all types of ice-sheet models. The protocol includes also sensitivity experiments such as hosing.

Inputs from the community are welcome to improve the protocol under development and make it relevant to all ice-sheet modelling groups interested in participating!

How to cite: Gregoire, L., Menthon, M., Gasson, E., and Sime, L.: Protocol for a Last Interglacial Antarctic ice-sheet model inter-comparison, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18501, https://doi.org/10.5194/egusphere-egu24-18501, 2024.

EGU24-19165 | Posters on site | CR2.2

Oceanic gateways in Antarctica - Impact of relative sea-level change on sub-shelf melt 

Moritz Kreuzer, Torsten Albrecht, Lena Nicola, Ronja Reese, and Ricarda Winkelmann

Relative sea level (local water depth) on the Antarctic continental shelf is changing by the complex interplay of processes associated with Glacial Isostatic Adjustment (GIA). This involves near-field visco-elastic bedrock displacement and gravitational effects in response to changes in Antarctic ice load, but also far-field interhemispheric effects on the sea-level pattern. On glacial time scales, these changes can be in the order of several hundred meters, potentially affecting the access of ocean water masses at different depths to Antarctic grounding lines and ice sheet margins. Due to strong vertical gradients in ocean temperature and salinity at the continental shelf margin, basal melt rates of ice shelves could change significantly just by variations in relative sea level alone.
Based on a coupled ice sheet – GIA model setup and the analysis of bathymetric features such as troughs and sills that regulate the access of open ocean water masses onto the continental shelf (oceanic gateways), we conduct sensitivity experiments to derive maximum estimates of Antarctic basal melt
rate changes, solely driven by relative sea-level variations.
Under Last Glacial Maximum sea-level conditions, this effect would lead to a substantial decrease of present-day sub-shelf melt rates in East Antarctica, while the strong subsidence of bedrock in West Antarctica can lead up to a doubling of basal melt rates. For a hypothetical globally ice-free sea-level
scenario, which would lead to a global mean (barystatic) sea-level rise of around +70 m, sub-shelf melt rates for a present-day ice sheet geometry can more than double in East Antarctica, but can also decrease substantially, where bedrock uplift dominates. Also for projected sea-level changes at the
year 2300 we find maximum possible changes of ±20 % in sub-shelf melt rates, as a consequence of relative sea-level changes only.

How to cite: Kreuzer, M., Albrecht, T., Nicola, L., Reese, R., and Winkelmann, R.: Oceanic gateways in Antarctica - Impact of relative sea-level change on sub-shelf melt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19165, https://doi.org/10.5194/egusphere-egu24-19165, 2024.

EGU24-20197 | ECS | Posters on site | CR2.2

Constraining projections of future freshwater fluxes from Antarctica  

Violaine Coulon, Javier Blasco, Qing Qin, Jan De Rydt, and Frank Pattyn

As global temperatures rise, Antarctica's grounded ice sheet and floating ice shelves are experiencing accelerated mass loss, releasing meltwater into the Southern Ocean. This increasing freshwater discharge poses significant implications for global climate change. Despite these consequences, interactive ice sheets and ice shelves have generally not been included in coupled climate model simulations, such as those in CMIP6. Consequently, CMIP6 projections lack a detailed representation of spatiotemporal trends in ice-sheet freshwater fluxes and their impact on the global climate system, introducing major uncertainties in future climate and sea-level projections. To address this, we provide future Antarctic freshwater forcing data and uncertainty estimates for climate models. These are derived from an ensemble of historically calibrated standalone ice sheet model projections, produced with the Kori-ULB ice flow model, under different climate scenarios up to 2300. Here, we analyse spatiotemporal trends in calving rates, ice shelf basal melt and surface mass balance for all Antarctic ice shelves. 

How to cite: Coulon, V., Blasco, J., Qin, Q., De Rydt, J., and Pattyn, F.: Constraining projections of future freshwater fluxes from Antarctica , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20197, https://doi.org/10.5194/egusphere-egu24-20197, 2024.

EGU24-20332 | ECS | Orals | CR2.2

The effect of Pacific climatology on the North American Ice Sheet at the Last Glacial Maximum 

William J. Dow, Sam Sherriff-Tadano, Lauren J. Gregoire, and Ruza Ivanovic

Surface ocean conditions and atmospheric dynamics can affect the surface mass balance (SMB) of remote ice sheets via their influence on heat and moisture transport. Here, we use the FAMOUS-ice coupled climate-ice sheet model, coupled to a slab ocean, to simulate the Last Glacial Maximum (LGM). The model was run hundreds of times to produce a large ensemble that captures a range of uncertain model inputs (parameter values). We investigate the range of simulated atmospheric circulation patterns in the 16 ‘best’ ensemble members based on constraints, such as global temperature, their relationship to sea surface conditions in the North Pacific and the interactions with the North American ice sheet. We present evidence of upper tropospheric planetary waves that facilitate communication between the tropical Pacific and extratropical Laurentide ice sheet region, yet there are clear differences in upper tropopsheric dynamics when compared to recent historical period. There is limited evidence for this tropical-extra-tropical relationship being directly responsible for regional differences in Laurentide SMB evolution.

How to cite: Dow, W. J., Sherriff-Tadano, S., Gregoire, L. J., and Ivanovic, R.: The effect of Pacific climatology on the North American Ice Sheet at the Last Glacial Maximum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20332, https://doi.org/10.5194/egusphere-egu24-20332, 2024.

EGU24-21079 | Orals | CR2.2

Understanding conditions leading to WAIS collapse, from the Last Interglacial to the modern 

Mira Berdahl, Gunter Leguy, Eric Steig, William Lipscomb, Bette Otto-Bliesner, Nathan Urban, Ian Miller, and Harriet Morgan

It is virtually certain that the West Antarctic Ice Sheet (WAIS) collapsed during past warm periods in Earth’s history, prompting concerns about the potential recurrence under anthropogenic climate change. Despite observed ice shelf thinning in the region, the combination of climate forcing and ice sheet sensitivity driving these changes remains unclear. Here, we investigate the joint effects of climate forcing and ice sheet sensitivity to evaluate conditions leading to WAIS collapse. We run ensembles of the Community Ice Sheet Model (CISM), spun up to a pre-industrial state, and apply climate anomalies from the Last Interglacial (LIG, 129 to 116 yr ago), and the future (SSP2-4.5).  Forcing is derived from Community Earth System Model (CESM2) global simulations. We find that only modest ocean warming is required to cause significant WAIS mass loss, though such loss takes multiple centuries to millennia to manifest.

How to cite: Berdahl, M., Leguy, G., Steig, E., Lipscomb, W., Otto-Bliesner, B., Urban, N., Miller, I., and Morgan, H.: Understanding conditions leading to WAIS collapse, from the Last Interglacial to the modern, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21079, https://doi.org/10.5194/egusphere-egu24-21079, 2024.

EGU24-58 | ECS | Orals | HS2.4.2

Unveiling Hydrological Dynamics in Data-Scarce Regions:A Comprehensive Integrated Approach 

Ayenew Desalegn Ayalew, Paul D. Wagner, Dejene Sahlu, and Nicola Fohrer

The hydrological system of Rift Valley Lakes in Ethiopia has recently experienced changes since the past two decades. Potential causes for these changes include anthropogenic, hydro-climatic and geological factors. The main objective of this study was to utilize an integrated methodology to gain a comprehensive understanding of the hydrological systems and potential driving factors within a complex and data-scarce region. To this end, we integrated a hydrologic model, change point analysis, indicators of hydrological alteration (IHA), and bathymetry survey to investigate hydrological dynamics and potential causes. A hydrologic model (SWAT+) was parameterized for the gauged watersheds and extended to the ungauged watersheds using multisite regionalization techniques. The SWAT+ model performed very good to satisfactory for daily streamflow in all watersheds with respect to the objective functions, Kling–Gupta efficiency (KGE), the Nash–Sutcliffe efficiency (NSE), Percent bias (PBIAS). The findings reveal notable changes of lake inflows and lake levels over the past two decades. Chamo Lake experienced an increase in area by 11.86 km², in depth by 4.4 m, and in volume by 7.8 x 108 m³. In contrast, Lake Abijata witnessed an extraordinary 68% decrease in area and a depth decrease of 1.6 m. During the impact period, the mean annual rainfall experienced a decrease of 6.5% and 2.7% over the Abijata Lake and the Chamo Lake, respectively. Actual evapotranspiration decreased by 2.9% in Abijata Lake but increased by up to 0.5% in Chamo Lake. Surface inflow to Abijata Lake decreased by 12.5%, while Lake Chamo experienced an 80.5% increase in surface inflow. Sediment depth in Chamo Lake also increased by 0.6 m. The results highlight that the changing hydrological regime in Chamo Lake is driven by increased surface runoff and sediment intrusion associated with anthropogenic influences. The hydrological regime of Abijata Lake is affected by water abstraction from feeding rivers and lakes for industrial and irrigation purposes. This integrated methodology provides a holistic understanding of complex data-scarce hydrological systems and potential driving factors in the Rift Valley Lakes in Ethiopia, which could have global applicability.

How to cite: Ayalew, A. D., Wagner, P. D., Sahlu, D., and Fohrer, N.: Unveiling Hydrological Dynamics in Data-Scarce Regions:A Comprehensive Integrated Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-58, https://doi.org/10.5194/egusphere-egu24-58, 2024.

EGU24-95 | ECS | Orals | HS2.4.2

Flood prediction based on weather parameters using advanced machine learning-metaheuristic approaches 

Sandeep Samantaray, Abinash Sahoo, and Deba P Satapathy

Flood prediction has become more popular worldwide because of the devastating socioeconomic effects of this hazard and the predicted rise in its frequency in the near future. In India, public health, civil engineering, and agriculture are all greatly affected by flooding. Anything can be flooded, with levels ranging from a few inches to many feet. They may appear suddenly or develop gradually. The intensity and frequency of flooding will frequently increase due to human modifications to the environment. More frequent and severe weather occurrences could lead to more violent floods. Utilizing data-driven and machine-learning models to solve flow- and flood-related problems has lately gained traction as a subject of study. ML model shows two key advantages over traditional physically-based models controlled by differential equation systems. Firstly, without requiring a complete a priori understanding of the phenomenon, data-driven models are able to generate reasonably accurate predictions. The quantity, quality, and variety of data that are accessible all affect how accurate the model is. This feature shows that we can avoid the complexity of problems faced by physical-based models caused by the growing number of important components by learning from observational data. Second, data-driven flood models replace numerical integration of differential equations, which is an iterative process, with non-iterative procedures like forward propagation of neural networks.

We chose to study the floods in the Barak River basin (BRB), India, a high-elevation and quickly urbanized river basin that is prone to frequent flooding because of recent evidence of the impacts of regional climate change on the hydrological cycle. Using principal component analysis (PCA), the optimal inputs were found. Decision-makers in the hydrological field of research need accurate information regarding effective predictors. This study looks into the viability of using weather input data (rainfall, humidity, evapotranspiration, temperature) to predict monthly floods using a support vector machine customized with Manta-Ray foraging optimization (SVM-MRFO). The accuracy of SVM-MRFO was assessed by comparing it against SVM tuned by the Firefly algorithm, whale optimization algorithm, Salp swarm algorithm based on mean absolute errors (MAE), root mean square errors (RMSE), determination coefficient (R2), and Nash-Sutcliffe Efficiency (NSE). Implementing the FFA, WOA, SSA, and MRFO algorithms enhances the accuracy of the SVM.

The best performance metrics, NSE of 0.9914, RMSE of 0.0182, MAE of 0.0073, and BIAS of were obtained by the SVM model constructed using the MRFO training procedure, suggesting the model's potential for use in flood forecasting. The flood models in this study are significant since they were created using a mix of different inputs and AI algorithms. In conclusion, this study demonstrated the ability of AI algorithm-based models to forecast floods and produced a number of practical methods that the flood control departments of different states, regions, and nations might employ to estimate the likelihood of floods.

How to cite: Samantaray, S., Sahoo, A., and Satapathy, D. P.: Flood prediction based on weather parameters using advanced machine learning-metaheuristic approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-95, https://doi.org/10.5194/egusphere-egu24-95, 2024.

Despite rising rainfall constraints on global climate-resilient agriculture, there is no clear consensus on the quantification of the wet season, leading to contentious issues in rainfall regime evolution and subsequent impacts on phenology and vegetation productivity. Hence, we conducted a comprehensive assessment of rainfall regimes between 1982 and 2020 by using a modified anomalous accumulation method on a daily scale at the pixel level. We observed divergent patterns of “wet areas becoming drier, and dry areas becoming wetter” with rainfall amount and rainy days increasing in dry regions, and decreasing in humid regions. The length of the wet season was extended in the dry regions and shortened in the wet regions, and the trends were linearly related on dryness. Simultaneously, as dryness increased, so did the length, number, and cumulative number of dry days. Concurrent increases in rainy days and dry spells indicated a seasonal rainfall regime trend toward more frequent extreme conditions in drier areas, which was not entirely consistent with a global intensification pattern of “dry getting drier and wet getting wetter”, implying increased potential risks of both floods and droughts in dry areas. For climate risk prediction, water resource allocation, and agricultural management, we advocate for a finer and more precise dynamic assessment of the wetting-drying pattern.

How to cite: Hu, Y.: Divergent patterns of rainfall regimes in dry and humid areas of China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-126, https://doi.org/10.5194/egusphere-egu24-126, 2024.

Long-term variations in catchment evapotranspiration control water availability for human societies and freshwater ecosystems, with potential negative impacts particularly during low-flow conditions. Previous studies reported increases in water balance-derived evapotranspiration for parts of Central Europe, mostly between 1980s and 2010s. However, knowledge gaps still remain around (i) the extent of these increases in space and time, and (ii) uncertainties from the catchment water balance. Here we analyse trends in water balance-derived evapotranspiration for 461 German near-natural catchments, over multiple time windows in the last six decades. We constrain uncertainties through estimates of storage changes derived from recession analysis and the use of multiple precipitation products. Results show wide-spread, significant increases in catchment evapotranspiration during 1970s–2000s (for example, average regional trends of 3.2 mm year-2 with an uncertainty from precipitation of ±1 mm year-2 for the period 1970–2002). Yet, catchment evapotranspiration shows no significant changes or rather a tendency to the decrease after 2000s (-3.6±1.4 mm year-2 for Pre-Alpine catchments over 2000–2019). The directions of these variations are robust to the considered uncertainties and consistent with sparse in-situ data. We further discuss implications of these variations with respect to low-flow conditions.  This study offers a comprehensive synthesis on past variations in catchment evapotranspiration and their uncertainties, which is critical for a proper understanding of recent hydrological changes.   

How to cite: Bruno, G. and Duethmann, D.: Inter-decadal variations in water balance-derived catchment evapotranspiration in Central Europe and their uncertainties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1145, https://doi.org/10.5194/egusphere-egu24-1145, 2024.

EGU24-1420 | Orals | HS2.4.2 | Highlight

Storylines of climate variability for hydrological impact studies 

Theodore Shepherd

Physical climate storylines (physically-based unfoldings of past climate or weather events, or of plausible future events or pathways) are increasingly being used to represent the epistemic uncertainty in the forced response to climate change. But storylines can also be used to systematically explore the uncertainty space of climate variability, e.g. to construct plausible worst-case events. Their use in this latter context is perhaps less obvious since variability is generally considered to be an aleatoric rather than an epistemic uncertainty. However, for impact studies, variability is often hugely undersampled, which is a serious problem that storylines can help address. In this talk I will review the rationale behind the use of storylines, discuss some of the concerns and questions about storylines that continue to arise, and provide some examples of their use in this particular context and of how storyline and probabilistic representations of uncertainty can be usefully combined.

How to cite: Shepherd, T.: Storylines of climate variability for hydrological impact studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1420, https://doi.org/10.5194/egusphere-egu24-1420, 2024.

EGU24-1538 | ECS | Posters on site | HS2.4.2

Small, flashy catchments response to variation in rainfall profile shape 

Alexandra Seawell

Flash flooding has the potential for severe consequences but is much less well understood or predictable than longer duration flooding. It is important to improve understanding of patterns of rainfall and behaviour of responding catchments in order to manage flash flooding effectively. One aspect of rainfall that could potentially affect flood hydrographs is the temporal shape of rainfall profiles.

Design flood estimation in the UK is principally based on the FSR /FEH/ReFH methodology, which uses a symmetrical centre-loaded profile for rainfall. However, recent research undertaken during Roberto Villalobos Herrera’s PhD is that front-loaded and back-loaded rainstorms occur just as frequently as centre-loaded. My PhD seeks to test how different rain profile shapes change the river flow hydrograph and flooding across the catchment.

My PhD concentrates on small catchments which have typically been less studied and because they are likely to be responsive to short, intense rainfall that can cause flash flooding. Hydrological modelling has been undertaken for 24 identified study catchments using ReFH2.3 software, which is the standard flood estimation design software in the UK. Results indicate that use of symmetrical profiles risks underestimating potential flood peaks compared to back-loaded storms. Meanwhile, time-to-peak is typically shorter for frontloaded storms indicating the hydrograph rises faster, but lagtime is shorter for back-loaded storms indicating the peak flow occurs more quickly after the peak rain. As well as modelled responses, I have also begun identifying and analysing observed hydrographs for selected study catchments to see if these show any pattern in their response to rainfall profile shapes.

How to cite: Seawell, A.: Small, flashy catchments response to variation in rainfall profile shape, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1538, https://doi.org/10.5194/egusphere-egu24-1538, 2024.

EGU24-1918 | ECS | Posters on site | HS2.4.2

Evaporation and hydrology of the Orinoco and Amazon basins modulated by the Atlantic 

Nicolas Duque-Gardeazabal, Andrew R. Friedman, and Stefan Brönnimann

El Niño/Southern Oscillation (ENSO) strongly impacts the hydroclimate of tropical South America. However, other ocean-atmospheric oscillations in the Atlantic also have teleconnections over the continent with the most extensive tropical rainforest; these oscillations influence hydroclimate extremes (i.e. droughts and floods). Our research focuses on the physical mechanisms that link the Atlantic Sea Surface Temperature conditions with the hydrological anomalies, i.e. soil moisture, streamflow and evaporation.

This research is grounded on the consistency of a multi-evidence approach between datasets. We use independent observations of land-surface and atmospheric variables whose robustness comes from gauges, physically consistent interpolations (i.e. reanalysis), simulations or satellite-based observations. The research focuses on the satellite era (1980-) to compare several datasets. Apart from the Amazon, other important basins such as the Orinoco, Magdalena and Tocantis have received little attention; hence, we also focused on them.

The Atlantic Meridional Mode (AMM) consists of cross-equatorial Sea Level Pressure anomalies that deflect climatological winds northward or southward. Hence, the seesaw of wind anomalies produces anomalous atmospheric transport, convergence and precipitation. When dividing the analysis by independent seasons, the results show changing impacts over different subbasins of the Orinoco and Amazon. On the other hand, the Atlantic El Niño/La Niña (Atl3) weakens or strengthens the trade winds from June to August, producing moisture convergence or divergence over the Guianas and eastern Orinoco.

The SST impact on evaporation is a complex consequence of the anomalous atmospheric circulation. The cascade of abnormal atmospheric circulation modifies not just the surface water but also the radiation availability, causing hydrological anomalies. The radiation anomalies combined with the soil moisture memory control the evaporation anomalies. This dynamic also depends on the season analysed.

How to cite: Duque-Gardeazabal, N., Friedman, A. R., and Brönnimann, S.: Evaporation and hydrology of the Orinoco and Amazon basins modulated by the Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1918, https://doi.org/10.5194/egusphere-egu24-1918, 2024.

EGU24-2089 | ECS | Orals | HS2.4.2

Groundwater level reconstruction using long-term climate reanalysis data and deep neural networks  

Sivarama Krishna Reddy Chidepudi, Nicolas Massei, Abderrahim Jardani, and Abel Henriot

Assessing long-term changes in groundwater is crucial for understanding the impacts of climate change on aquifers and for managing water resources. However, long-term groundwater level (GWL) records are often scarce, limiting understanding of historical trends and variability. In this study, we present a deep learning approach to reconstruct GWLs up to several decades back in time using recurrent-based neural networks with wavelet pre-processing and climate reanalysis data as inputs. GWLs are reconstructed using two different reanalysis datasets with distinct spatial resolutions (ERA5: 0.25◦ x 0.25◦ & ERA20C: 1◦ x 1◦) and monthly time resolution, and the performance of the simulations was evaluated.  Long term GWL timeseries are now available for northern France, corresponding to extended versions of observational timeseries back to the early 20th century. All three types of piezometric behaviors could be reconstructed reliably and consistently capture the multidecadal variability even at coarser resolutions, which is crucial for understanding long-term hydroclimatic trends and cycles. GWLs’multidecadal variability was consistent with the Atlantic multidecadal oscillation. From a synthetic experiment involving a modified long-term observational time series, we highlighted the need for longer training datasets for some low frequency signals. Nevertheless, our study demonstrated the potential of using DL models together with reanalysis data to extend GWL observations and improve our understanding of groundwater variability and climate interactions. 

How to cite: Chidepudi, S. K. R., Massei, N., Jardani, A., and Henriot, A.: Groundwater level reconstruction using long-term climate reanalysis data and deep neural networks , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2089, https://doi.org/10.5194/egusphere-egu24-2089, 2024.

EGU24-3925 | ECS | Orals | HS2.4.2

Multi-decadal changes in root zone water storage capacity through vegetation adaptation to hydro-climatic variability 

Siyuan Wang, Markus Hrachowitz, and Gerrit Schoups

Climate change can considerably affect catchment-scale root zone storage capacity (Sumax) which may further influence the moisture exchange between land and atmosphere, as well as stream flow and biogeochemical processes in terrestrial hydrological systems. However, direct quantification of the evolution of Sumax over multi-decadal time periods at the catchment scale has so far been rare. As a consequence, it remains unclear how climate change affects Sumax (e.g., precipitation regime, canopy water demand) and how changes in Sumax may control the partitioning of water fluxes as well as the hydrological response at catchment scale. The objectives of this study in the upper Neckar river basin in Germany are therefore to provide an analysis of muti-decadal changes in Sumax that can be observed as a result of changing climatic conditions over the past century and how this has further affected hydrological dynamics. More specifically, we test the hypotheses that (1) Sumax significantly changes over multiple decades reflecting vegetation adaptation to climate variability, (2) changes in Sumax control water availability for evapotranspiration and thus multi-decadal deviations from long-term average positions in the Budyko framework, (3) a time-dynamic implementation of Sumax affects the hydrological response, which in return can improve the performance of a hydrological model.

We found that, indeed, a hydroclimatic condition considerably changed over time in the 1953 to 2022 study period, which was reflected by related fluctuations in the values of Sumax derived directly from observed water balance data These ΔSumax values varied by up to -20% in relatively wet decades to +20% in drier decades, which was very similar to ΔSumax obtained from calibration of a hydrological model (R2=0.95, p<0.05) in individual decades. However, evaporation estimated by the hydrological model using a long-term average Sumax for the study period was almost the same as that reproduced by the model when allowing dynamically changing root-zone storage capacities over multiple decades. In addition, no significant improvement in the reproduction of the hydrological response was observed when implementing a time-variant representation of decadally varying Sumax in the model compared with the implementation of a stationary Sumax irrespective of the hydroclimatic conditions in the individual decades.

Overall, this study provides quantitative evidence that Sumax significantly changes over multiple decades reflecting vegetation adaptation to climate variability. However, these changes are not responsible for deviations from the Budyko curves in different climatic conditions, in other words, the temporal evolution of Sumax in the study region is not a major control on the partitioning of water fluxes into evapotranspiration and drainage and does have therefore no significant effects on fundamental hydrological response characteristics of the upper Neckar catchment. This suggests that model predictions of future stream flows remain rather insensitive to uncertainties introduced by the use of time-invariant long-term average values of Sumax as model parameters.

How to cite: Wang, S., Hrachowitz, M., and Schoups, G.: Multi-decadal changes in root zone water storage capacity through vegetation adaptation to hydro-climatic variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3925, https://doi.org/10.5194/egusphere-egu24-3925, 2024.

EGU24-6799 | ECS | Orals | HS2.4.2

Identification of extreme climatic events using SMOS 

Nitu Ojha, Yann Kerr, and Arnaud Mialon

Soil moisture (SM) is a crucial parameter in the hydrological cycle. SM wet and dry trends help to identify extreme weather events, with a rapid increase in SM suggesting heavy rainfall or flood events and a significant or prolonged decrease in SM representing drought events. SMOS and SMAP remote sensing satellites provide surface SM data globally. The surface SM is highly variable in terms of space and time. In contrast, root zone soil moisture (RZSM) is stable and retains long-term information, making it a better indicator of prolonged drought/wet conditions. In this context, SMOS RZSM is computed from the SMOS surface SM using a simple physical model to integrate surface SM information to a root zone. The study benefits from the availability of long-term series data of the SMOS RZSM on a global scale from 2010 to 2023 (approximately 14 years). Then, the SM index is developed using long-time series data of the SMOS RZSM for a better understanding of the distribution of wet and dry SM and its link to extreme events. The study primarily focuses on Australia and Europe. The results show that the developed SMOS SM index captures heavy rainfall/flood and drought conditions. The analysis determines the occurrence of floods due to La Niña and El Niño effects over Australia and the existence of drought in Europe due to the North Atlantic oscillation. This study can help to understand the interconnected factors that influence extreme climatic conditions, ranging from natural climatic phenomena to human-induced activities.

How to cite: Ojha, N., Kerr, Y., and Mialon, A.: Identification of extreme climatic events using SMOS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6799, https://doi.org/10.5194/egusphere-egu24-6799, 2024.

EGU24-7568 | Posters on site | HS2.4.2

Mapping UK Drought Teleconnections from Ocean to Land 

Amulya Chevuturi, Marilena Oltmanns, Maliko Tanguy, Ben Harvey, Cecilia Svensson, and Jamie Hannaford

Given the anticipated changes in future UK drought occurrences attributable to climate change, there is an imminent requirement for a thorough understanding of the underlying influences behind UK drought events, particularly the most extreme events. In this context, our study aims to understand the North Atlantic oceanic drivers responsible for drought events in the UK, subsequently tracing the teleconnection pathways that connect these drivers to meteorological and hydrological droughts within the region. We examine the teleconnection pathways associated with drought conditions by assessing the concurrent and lagged statistical links between the UK's standardized precipitation index (SPI) and standardized streamflow index (SSI) and two distinct North Atlantic Sea surface temperature (SST) patterns, which are associated with freshening events. Our findings reveal that these North Atlantic SST patterns exert varying influences on two distinct regions of the UK (northwest and southeast), each of which have distinct hydrometeorological characteristics. The identified SST patterns are linked to the dominant modes of SST variability in the North Atlantic, thereby contributing to the predictability of drought occurrences across seasonal to multi-annual timescales, including at some very long lead times. Our research therefore has significant potential in practical applications for quantifying and managing drought risk, and for advancing drought forecasting and early warning systems through the identification of novel, skilful predictors. Ultimately, our work endeavours to contribute to the progress of sustainable water resource management amidst the escalating drought risks in the UK.

How to cite: Chevuturi, A., Oltmanns, M., Tanguy, M., Harvey, B., Svensson, C., and Hannaford, J.: Mapping UK Drought Teleconnections from Ocean to Land, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7568, https://doi.org/10.5194/egusphere-egu24-7568, 2024.

EGU24-7930 | Posters on site | HS2.4.2

An increasing role of subsurface processes in the water circulation in the High Arctic catchment – the results from Fuglebekken, SW Spitsbergen 

Marzena Osuch, Abhishek Alphonse, Nicole Hanselmann, and Tomasz Wawrzyniak

Changes in the depth of the active layer thickness (ALT) in Arctic and permafrost regions significantly impact the transformation of rainfall into runoff. Due to climate change, permafrost thawing and ALT alterations modify how water is transported and stored within catchments, affecting surface and subsurface hydrological processes. This study investigates the associations between temporal changes in active layer thickness, hydrological model parameters, and variations in catchment responses.

The study area covers the unglaciated catchment Fuglebekken, located near the Polish Polar Station Hornsund on Spitsbergen. For hydrological modelling, the conceptual rainfall-runoff HBV model was used. Model calibration and validation were carried out on runoff data within subperiods. A moving window approach (3-week duration) using data from the summer seasons 2014-2023 was applied to derive temporal variations of parameters. Model calibration, along with an evaluation of parametric uncertainty, was performed using the Shuffled Complex Evolution Metropolis algorithm.

A comprehensive investigation of the temporal variability of HBV model parameters demonstrated consistency in the results. The smallest parametric uncertainty and the largest temporal changes were estimated for the parameter KS representing a slow runoff reservoir. Temporal variability of the KS parameter is characterized by the presence of two maxima, the first maximum at the beginning of the ablation season (due to snowmelt and ice-rich permafrost thawing) and the second maximum in September (a result of high precipitation). The temporal variability of other parameters was smaller and usually within their parametric uncertainty.

In addition, the use of the HBV model allowed for the assessment of water storage in five conceptual reservoirs characterizing catchment processes. The outcomes highlighted large changes in slow runoff reservoir, demonstrating an increasing significance of subsurface processes in the water circulation in the High Arctic catchment. 

The study was supported by the Polish National Science Centre (grant no. 2020/38/E/ST10/00139).

How to cite: Osuch, M., Alphonse, A., Hanselmann, N., and Wawrzyniak, T.: An increasing role of subsurface processes in the water circulation in the High Arctic catchment – the results from Fuglebekken, SW Spitsbergen, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7930, https://doi.org/10.5194/egusphere-egu24-7930, 2024.

Ice-induced winter flooding, intensified by sustained low temperatures, holds the potential for severe natural disasters, but is seldom explored probabilistically considering warming climate impacts. This study established both marginal and copula-based joint probability distributions of the upstream (QH) and downstream (QL) ice-induced floods in the Lower Yellow River, a hanging river above the ground, under four parametric scenarios (constant, time as covariates, mean air temperature as covariates, and accumulated negative air temperature as covariates), to compare historical and design flood regimes using six inference methods (UNI, OR, AND, KEN, SKEN, and COND) under air temperature changes. The results show that the Lognormal and Weibull marginal distribution models with accumulated negative air temperature as covariate parameters were optimal for QH and QL, respectively and the positive dependence between QH and QL was best described by the Gumbel-Hougaard copula. Impacts of increasing air temperature on flood downtrends and yearly change-points (1990 for QH and 1985 for QL) reduced both historical QH-QL flood magnitude combinations and projected return periods, thus denoting declining flood severities over time. Due to such flood downtrends, the most probable composition (MPC) values of 100-year design floods varied from the highest (1656 m3/s for QH and 1645 m3/s for QL using the OR method) to the lowest (624 m3/s for QH and 342m3/s for QL using the SKEN method). The average decreasing rates of MPC values before and after the discerned flood change-points were 17.4% for QH and 39.6% for QL. When conditioned on the occurrence of upstream QH having flood magnitudes less than 100-year design floods, large floods downstream exceeding a 50-year return period were inferred as improbable. This study can provide a paradigm of flood projections to meet diverse flood control objectives under changing climate.

How to cite: Li, L. and Xu, C.-Y.: Probabilistic projections of winter floods considering cumulative effect of air temperature changes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8371, https://doi.org/10.5194/egusphere-egu24-8371, 2024.

EGU24-10340 | ECS | Orals | HS2.4.2

The Impact of GRACE Data Assimilation on Water Storage Dynamics in CLM3.5 and CLM5 

Yorck Ewerdwalbesloh, Anne Springer, and Jürgen Kusche

The GRACE (Gravity Recovery And Climate Experiment) satellite mission as well as its successor GRACE Follow-On have monitored global and regional variability of total water storage (TWS) for the past two decades. Assimilating observations from these missions into hydrological models helps to improve modeled water storages and fluxes, to overcome deficits arising from simplifications or processes that are not considered in the model (e.g. unmodeled anthropogenic impacts), and to disaggregate GRACE observations temporally and spatially. Determining the optimal approach for assimilating these observations into hydrological models remains an ongoing area of research. The choice often depends on specific applications and the characteristics of the model itself.

In this study, we analyze the water storage dynamics of two versions of the Community Land Model (CLM) - versions 3.5 and 5 - within a GRACE data assimilation framework over a 12.5 km grid covering Europe. The analysis focuses on assessing (i) the skill of both models without data assimilation, (ii) the impact of GRACE data assimilation on the model performance and (iii) the distribution of assimilation increments to different storage compartments. We evaluate water storages and fluxes simulated by both models against independent observations such as discharge from river gauges and satellite derived soil moisture. The results offer valuable insights into the impact of advancements made in biophysical processes and the representation of the carbon cycle in CLM5. Furthermore, we discuss the effectiveness of GRACE data assimilation and its influence on the behavior of CLM3.5 and CLM5, analyzing whether the assimilation helps to address differences between the two model versions - particularly considering the advancements in CLM5 - which would underline the ability of GRACE data assimilation in mitigating model deficits.

How to cite: Ewerdwalbesloh, Y., Springer, A., and Kusche, J.: The Impact of GRACE Data Assimilation on Water Storage Dynamics in CLM3.5 and CLM5, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10340, https://doi.org/10.5194/egusphere-egu24-10340, 2024.

EGU24-10459 | ECS | Posters on site | HS2.4.2

Past, Present, and Future Impacts of Climate Change and Variability on Flood Hazards in Sub-Saharan Africa 

Job Ekolu, Bastien Dieppois, Yves Tramblay, Jonathan Eden, Moussa Sidibe, Gabriele Villarini, Simon Moulds, Louise Slater, Stefania Grimaldi, Peter Salamon, Pierre Camberlin, Benjamin Pohl, Gil Mahé, and Marco van de Wiel

Sub-Saharan Africa (SSA) is strongly affected by flood hazards, which endanger human lives and disrupt economic stability. It is therefore critical to further understand the potential impact of climate change and variability on historical and future flood hazards in SSA. To do so, we first reconstructed a complete 65-yearlong daily streamflow, presenting over 600 stations distributed throughout SSA. Using this new dataset, we found that historical trends in flood frequency, duration, and intensity were strongly modulated by decadal to multidecadal variability. We then identified internal modes of climate variability in the Pacific and Indian Oceans as primary drivers of decadal variations in flood occurrence in southern and eastern Africa. Meanwhile, decadal sea-surface temperature anomalies (SSTa) over the eastern Mediterranean region and the North Atlantic were primarily driving decadal trends in floods occurring over western and central Africa. Using 12 climate model large ensembles from the Coupled Model Intercomparison Project Phases 5 and 6 (CMIP5 and 6), we also found such decadal variations in SSTa in the Mediterranean Atlantic, Pacific, and Indian oceans could modulate the occurrence of flood hazards by up to 50% in SSA during the 21st century. Finally, combining bias-corrected CMIP6 data and the open-source hydrological model LISFLOOD, we examine the potential impact of climate change on future trends affecting the intensity, frequency, and duration of floods in West Africa. This study therefore enabled us to compare for the first time the relative importance of climate change and climate variability on future changes affecting flood hazards in SSA.

How to cite: Ekolu, J., Dieppois, B., Tramblay, Y., Eden, J., Sidibe, M., Villarini, G., Moulds, S., Slater, L., Grimaldi, S., Salamon, P., Camberlin, P., Pohl, B., Mahé, G., and van de Wiel, M.: Past, Present, and Future Impacts of Climate Change and Variability on Flood Hazards in Sub-Saharan Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10459, https://doi.org/10.5194/egusphere-egu24-10459, 2024.

EGU24-10963 | ECS | Orals | HS2.4.2

Future changes in tropical vertical velocity variance and precipitation variability 

Zhenghe Xuan, Clarissa Kroll, and Robert Jnglin Wills

Understanding precipitation variability on subseasonal-to-decadal timescales is important because of its influence on regional water resources and hydrological extremes. The response of precipitation to global warming can be understood in terms of a superposition of thermodynamic and dynamic effects. The former has been studied on a range of timescales, including ENSO variability and precipitation extremes, and is strongly constrained by Clausius-Clapeyron scaling. Changes in dynamics, however, modulate the overall change significantly and represent an important source of uncertainty in projected changes of hydrological cycle variability.

Here, we investigate changes in the variance of vertical velocity in the tropics based on monthly outputs from the Community Earth System Model 2 Large Ensemble. We find a robust decrease in the tropical vertical velocity variance under the SSP3-7.0 scenario, even in periods where the underlying ENSO-related SST variance increases. This reduction in vertical velocity variance can be explained by the deepening of the troposphere, which increases the gross moist stability and thus the energetic demands for vertical motion. Finally, we investigate the influence of reduced vertical velocity variance on precipitation probability distribution and intensity.

How to cite: Xuan, Z., Kroll, C., and Jnglin Wills, R.: Future changes in tropical vertical velocity variance and precipitation variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10963, https://doi.org/10.5194/egusphere-egu24-10963, 2024.

EGU24-11244 | ECS | Orals | HS2.4.2

Inter-annual and long-term variability in streamflow elasticity to precipitation reveal bias in estimates of hydrological sensitivity 

Bailey Anderson, Louise Slater, Jessica Rapson, Manuela Brunner, Simon Dadson, Jiabo Yin, and Marcus Buechel

Empirically derived sensitivities of streamflow to precipitation are often assumed to be temporally unchanging. This assumption may be unrealistic because changes in climate and storage are known to alter this relationship. We present a non-stationary regional regression approach which is functionally similar to typical elasticity estimation approaches. This is applied to 2967 catchments in the United States to estimate variability in interannual, and trends in long-term, streamflow elasticity to precipitation over a 39-year period. We show that interannual elasticity is highly variable in water-limited catchments, indicating that these are especially sensitive to year-to-year climate variability, as compared to other regions. Interannual elasticity is more often correlated with the one-year lagged standardized precipitation index than with temperature or in-phase standardized precipitation index, suggesting that antecedent soil moisture, groundwater storage, and precipitation seasonality influence streamflow sensitivity. Finally, statistically significant long-term trends in elasticity exist in some regions, but trend magnitude is generally small. These findings suggest that an assumption of stationarity in long-term average elasticity may still be appropriate at the regional scale, however, year-to-year variation in streamflow responsiveness to precipitation is often substantial.    

How to cite: Anderson, B., Slater, L., Rapson, J., Brunner, M., Dadson, S., Yin, J., and Buechel, M.: Inter-annual and long-term variability in streamflow elasticity to precipitation reveal bias in estimates of hydrological sensitivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11244, https://doi.org/10.5194/egusphere-egu24-11244, 2024.

EGU24-12189 | ECS | Orals | HS2.4.2

Surface and groundwater drought impact on natural vegetation growth and drought recovery. 

Jorge Vega Briones, Steven De Jong, Wiebe Nijland, and Niko Wanders

Droughts' persistent impact and growing use of surface water and groundwater will likely exacerbate hydrological droughts. Variations in precipitation patterns worsen the effects in particular catchment regions as a result to climate change. The end result is less groundwater recharge and multi-year droughts that impact vegetation and rivers.

An essential factor to better understand the recovery in catchments affected by drought is to understand the interaction between water availability and vegetation dynamics. At the same time, the vegetation recovery in terms of growth and productivity can also be assessed with this framework. In this study, we focus on natural catchments of central Chile which have experienced drought and multi-year drought periods with severe impacts on surface water and groundwater.

We collected 250 tree ring samples of 5 species that are susceptible to droughts in central Chile in natural catchments, and used CAMELS-CL for statistical analysis. Cross correlation analysis between surface, groundwater and vegetation dynamics was performed for each catchment to quantify the interaction between these factors. To further determine the influence of drought events on vegetation, the compound NDVI correlation and SPEI at a catchment level were used. Finally, the drought termination framework was applied to understand the recovery response of surface, groundwater and vegetation.

Our analysis identifies the typical time lag between droughts in surface water, groundwater and  their impact on vegetation growth. This is done on an annual time scale as we are looking at multi-year events. We find that the typical response time varies throughout the country, depending on the local natural water availability. These findings highlight that the multi-year drought impact on vegetation and its recovery is not uniform and should be better understand in light of climate change and the global increase in multi-year drought events.

How to cite: Vega Briones, J., De Jong, S., Nijland, W., and Wanders, N.: Surface and groundwater drought impact on natural vegetation growth and drought recovery., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12189, https://doi.org/10.5194/egusphere-egu24-12189, 2024.

EGU24-14039 | ECS | Orals | HS2.4.2

Historical changes in the seasonality and timing of extreme precipitation events 

Gaby Gründemann, Enrico Zorzetto, Nick van de Giesen, and Ruud van der Ent
Global warming alters the hydrological cycle, influencing the seasonality and timing of extreme precipitation events. Understanding historical changes in the occurrence of extreme precipitation is important for assessing their effects. This study examines the timing and seasonality of extreme precipitation using 63 years of ERA5 data. By using relative entropy, we can assess changes in extreme daily precipitation occurrence on the global domain. Findings show notable regional differences. In the second half of the 20th century, Africa and Asia had high clustering of extreme precipitation events. Over 60 years, clustering intensified in Africa but became more spread out in Asia. North America and Australia, initially with less clustering, saw slight increases. Extreme precipitation events in extra-tropical land regions mainly occurred in summer, with minor shifts in timing. These results are important for improving risk management for hazards like flash floods and landslides and highlight the need for region-specific strategies in adapting to these changes.

How to cite: Gründemann, G., Zorzetto, E., van de Giesen, N., and van der Ent, R.: Historical changes in the seasonality and timing of extreme precipitation events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14039, https://doi.org/10.5194/egusphere-egu24-14039, 2024.

EGU24-14414 | ECS | Orals | HS2.4.2

Navigating Hydroclimatic Extremes: Understanding the Interplay of Climate Change and Variability 

Achala Singh, Priyank J. Sharma, and Ramesh S. V. Teegavarapu

Increased frequency of extreme and rare hydroclimatic events leading to substantial disruptions in hydrological patterns worldwide can be attributed to climate variability and change. The stationarity assumption routinely used for hydrologic design and water resources planning is no longer valid under an evolving climate. Conventional notions about hydrological stability are now challenged, considering the intricate connection between climate fluctuations and the rising prevalence of extreme weather events. High spatial and temporal variability of extreme events in tropical and semi-arid climatic regions pose challenges in assessing non-stationarity considering available data and understanding processing contributing to short and long-term changes in regional climate. This study proposes and evaluates a novel approach using nonparametric statistical tests to explore the presence of non-stationarity in hydroclimatic extremes for a tropical river basin. Further, changes in the return levels of hydroclimatic extremes under stationary and non-stationary conditions will be carried out using statistical modelling approaches. Using the proposed approach, the identification of pivotal climatic drivers, such as oceanic oscillations and atmospheric circulation patterns, and their roles in influencing hydroclimatic extremes is possible. Long-term observational data is assessed in this work to discern trends and patterns in frequency, intensity, and spatial distribution of extremes and their links to climate change and variability. The impact of shifting precipitation patterns, temperature extremes, and seasonal variations is evaluated. This research study helps to investigate the implications of climate-induced hydroclimatic extremes under diverse geographical and climatic settings. This research can help understand the impact of climate change in river basins driven by the shifts in precipitation, temperature patterns, and extremes and address water availability and management issues.

Keywords: Non-stationarity, Hydroclimatic extremes, Climatic drivers, Statistical modelling, Tropical River basin.

How to cite: Singh, A., Sharma, P. J., and Teegavarapu, R. S. V.: Navigating Hydroclimatic Extremes: Understanding the Interplay of Climate Change and Variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14414, https://doi.org/10.5194/egusphere-egu24-14414, 2024.

EGU24-15120 | ECS | Orals | HS2.4.2

Groundwater storage trends in northern Italy as observed by GRACE, well measurements, and vertical land motion 

Grace Carlson, Christian Massari, Marco Rotiroti, Elisabetta Preziosi, Tullia Bonomi, Andrew Wilder, Susanna Werth, Destinee Whitaker, Tianxin Wang, Marianne Cowherd, and Manuela Girotto

Geodetic observations of the Earth’s gravitational and deformational response to changes in terrestrial water storage (∆TWS) have been essential measurements to identify regions experiencing long-term wetting and drying driven by a combination of climate and anthropogenic forces. The northern Italian Plains, home to a third of the country’s population and contributing more than half of the agricultural output, have experienced a dryer-than-normal two decades. Here, we investigate what impact these dry conditions have on the long-term groundwater storage (GWS) using observations of change in terrestrial water storage (∆TWS) from the Gravity Recovery and Climate Experiment (GRACE) and the second-generation follow-on (GRACE-FO) missions and in-situ groundwater level time series from 820 wells over the period of 2003-2022. We use a wavelet time-frequency analysis to deconstruct each signal into seasonal and long-term components and identify multi-year dry and wet epochs. We find two long periods of declining groundwater storage (2003-2007, 2015-2022), two short periods of groundwater recovery (2008-2009, 2012-2014), and one period of near-zero ∆GWS (2010-2011). We find a net volume loss of 12.0 km3 from 2003-2022. Further, we validate these ∆GWS trends and total volume loss estimates using a combination of in-situ groundwater level variations and vertical land motion observed at nearly 500 Global Navigation Satellite System (GNSS) stations. These stations show poroelastic deformation over aquifers related to groundwater storage changes and elastic loading deformation that is highly correlated with predicted elastic loading displacements from GRACE(-FO) ∆TWS outside of aquifer areas. To calculate groundwater storage from groundwater level, we estimate spatially- and depth-variable aquifer storage coefficients using a combination of lithologic information and co-located well and GNSS observations. By analyzing all three datasets in combination we can evaluate the impacts of multi-year dry- and wet- periods on groundwater resources, providing essential contextual information for future water management.

How to cite: Carlson, G., Massari, C., Rotiroti, M., Preziosi, E., Bonomi, T., Wilder, A., Werth, S., Whitaker, D., Wang, T., Cowherd, M., and Girotto, M.: Groundwater storage trends in northern Italy as observed by GRACE, well measurements, and vertical land motion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15120, https://doi.org/10.5194/egusphere-egu24-15120, 2024.

EGU24-15252 | ECS | Orals | HS2.4.2

Spatiotemporal Variability in Hydrological Drought Recovery Time Estimations from GRACE and GRACE-FO Data  

Çağatay Çakan, M. Tuğrul Yılmaz, Henryk Dobslaw, Fatih Evrendilek, Christoph Förste, E. Sinem Ince, and Ali L. Yağcı

This study aimed to explore the global spatiotemporal variability in hydrological drought recovery time (DRT) estimated using terrestrial water storage (TWS) and station-based precipitation data. TWS data were gathered from the Gravity Recovery and Climate Experiment (GRACE) between April 2002 and June 2017 and GRACE Follow-On (GRACE-FO) between June 2018 and September 2023. The GRACE and GRACE-FO mascon (RL06) solution were used. Precipitation data were obtained from the Global Precipitation Climatology Project (GPCP) monthly analysis product. DRT was derived from the following two approaches: (1) TWS data via storage deficit and (2) TWS and precipitation data via absolute required precipitation. Storage deficit was computed as the negative deviation of detrended TWS from climatological values. Absolute required precipitation to fill the storage deficit was estimated from the linear relationship between the cumulative detrended smoothed precipitation anomalies (cdPA) and detrended smoothed TWS anomalies (dTWSA). The end of hydrological drought was assumed as when TWS deviation turned positive for the first methodology and as when observed precipitation exceeded absolute required precipitation for the second one. Mean DRT values across continents were obtained for both the GRACE and GRACE-FO periods, and the temporal variability between these periods was explored across different continents. On average, DRT estimate was 29% higher during the GRACE period (11.2 months) than during the GRACE-FO period (8.6 months). The TWS-based method (11.5 months) yielded 38% higher DRT than did the TWS- and precipitation-based one (8.3 months). Overall, Australia exhibited the highest DRT estimate (averaging 11.3 months) among all continents for both methods, whereas Europe showed the lowest one (averaging 8.6 months), with a global average of 9.9 months. Analysis of the temporal consistency between DRT estimates from both methods revealed that 28% of estimates aligned during the GRACE period, increasing to 49% during the GRACE-FO period. In particular, the highest consistency (61%) was observed over Africa during GRACE-FO period, contrasting with the lowest consistency (17%) over Australia during the GRACE period. Overall, the consistency between the DRT estimates from the two methods increased from the GRACE period to the GRACE-FO period across all the continents by 18% to 40%, except for Europe, where consistency dropped by 3%. These findings provide insights not only into the potential of TWS data in globally estimating DRT with significant consistency but also into understanding the dynamics of global hydrological droughts, thus proving beneficial in devising management strategies for water resources.

How to cite: Çakan, Ç., Yılmaz, M. T., Dobslaw, H., Evrendilek, F., Förste, C., Ince, E. S., and Yağcı, A. L.: Spatiotemporal Variability in Hydrological Drought Recovery Time Estimations from GRACE and GRACE-FO Data , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15252, https://doi.org/10.5194/egusphere-egu24-15252, 2024.

EGU24-19475 | ECS | Orals | HS2.4.2

Long-term changes in water resources: the challenge of disentangling water management, climate change, and natural variability 

Vincent Humphrey, Marius Egli, Johanna Wittholm, Laura Jensen, Sebastian Sippel, Annette Eicker, Gionata Ghiggi, and Reto Knutti

Every year, natural climate variability leads to droughts and floods which have significant impacts for ecosystems and societies. Water reservoirs like soil moisture, lakes, and groundwater act as natural buffers and balance these fluctuations by providing water supply during dry conditions and by storing water surplus after rain and snow events. Such natural fluctuations unfold over time scales that can reach several decades, making it challenging to assess the extent to which trends in water reservoirs observed over the recent past are caused by anthropogenic modifications. Such modifications can themselves be further partitioned into different terms. For instance, one can contrast the contribution of regional land and water management on the one hand, and the contribution of climate change on the other. Another frequent framework is to causally relate changes in water storage to individual changes in precipitation, evapotranspiration, and runoff.

In this contribution, we review the strengths and weaknesses of recent approaches used to causally attribute observed as well as projected changes in water availability. Ensembles of model simulations and factorial experiments typically represent a powerful way of assessing individual responses to drivers and developing a plausible and mechanistic understanding. However, contradictions also quickly emerge between global hydrological model simulations, which typically represent water reservoirs and water management more thoroughly, and Earth system (climate) model simulations, which include biogeochemical effects, like CO2 fertilization, that are typically neglected by hydrological models. We will show that these two incomplete modeling worlds can be reconciled with large-scale satellite observations in only a few regions, while very large uncertainties remain in other parts of the world and in particular over tropical areas.

How to cite: Humphrey, V., Egli, M., Wittholm, J., Jensen, L., Sippel, S., Eicker, A., Ghiggi, G., and Knutti, R.: Long-term changes in water resources: the challenge of disentangling water management, climate change, and natural variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19475, https://doi.org/10.5194/egusphere-egu24-19475, 2024.

Several continental regions on Earth are getting wetter, while others are drying out not only in terms of precipitation but also measured by the increase or decrease in surface water, water stored in the soils, the plant root zone, and in groundwater. Drying and wetting as seen in terrestrial, space-geodetic and remote sensing data are generally ascribed to combined effects of global warming due to greenhouse gas forcing, natural variability, and anthropogenic modification of the water cycle. Existing climate models that account for these effects fail to explain observed patterns of hydrological change sufficiently. Contrary to common beliefs, observations also do not support a simple dry-gets-dryer and wet-gets-wetter logic. Instead, the observed trends, e.g. in precipitation, soil moisture, water storage, or flood discharge, differ considerably from a simplified logic.
The CRC 1502 DETECT, a collaborative research centre of the Universities of Bonn and Göttingen, the Geomar, the Research Centre Jülich and the German National Meteorological Service DWD, has been established by the German Research Foundation DFG with the objective of closing this gap of understanding. To better comprehend the origin of these patterns, DETECT  is developing a regional coupled modeling framework further that explains past observations as realistically as possible, accounts for potential drivers of change that may have been understudied in the past, and that can predict future changes. Our modelling framework is based on the TerrSysMP platform (i.e. the coupling of ICON/COSMO, CLM and ParFlow with/without data assimilation) and it ingests various conventional and new satellite and terrestrial data sets.
By applying this modelling framework to both historical and IPCC-type simulations, DETECT will test the hypothesis that humans – through several decades of land use change, and intensified water use and management – have caused persistent modifications in the coupled land and atmospheric water and energy cycles. It is hypothesized that (1) these human-induced modifications contribute considerably, compared to greenhouse gas (GHG) forcing and natural variability, to the observed trends in water storage at the regional scale, (2) land management and land and water use changes have modified the regional atmospheric circulation and related water transports and (3) these changes in the spatial patterns of the water balance have created and magnified imbalances that lead to excessive drying or wetting in more remote regions.
We test this hypothesis for the Euro-CORDEX region. In later phases, we evaluate the transferability of our approach for regions with different environmental conditions. We will develop evidence-based sustainability criteria for land and water use activities. The presentation will provide an overview on the central hypotheses and objectives of our research programme, the study logic and common approach, as well as anticipated results and contributions to the community. After two years, we highlight some first  findings.

How to cite: Siegismund, F. and Kusche, J.: Collaborative Research Centre 1502 DETECT: 'Regional Climate Change: Disentangling the Role of Land Use and Water Management', EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20232, https://doi.org/10.5194/egusphere-egu24-20232, 2024.

EGU24-20247 | Posters on site | HS2.4.2

Towards a coupled km-scale Atmosphere-Land Reanalysis for Europe 

Bernd Schalge, Jane Roque Mamani, Olaf Stein, Stefan Poll, Klaus Görgen, Jan Keller, and Arianna Valmassoi

Modelling studies in hydrology depend on a good representation of forcing data, in particular precipitation, for a good process representation, especially at the catchment  or sub-catchment scale. Forcing data is often provided through reanalysis, that use observations to obtain model states with the smallest possible errors and biases. Here, we present a prototype convection-permitting reanalysis system using a coupled atmosphere-land model system utilizing ICON-eCLM for the EURO-CORDEX domain at a resolution of 3km. Due to the high resolution it is expected that in particular precipitation will be better represented than in existing reanalyses, leading to more realistic forcing data. We analyzed precipitation and other near-surface observables from preliminary model runs and evaluated them in comparison to other widely used reanalysis products such as ERA-5 as well as to output of an ICON standalone simulation to assess potential improvements of the new reanalysis. We show potential use cases of the new reanalysis and discuss limitations of this dataset, which are related to the currently short available time series.

How to cite: Schalge, B., Mamani, J. R., Stein, O., Poll, S., Görgen, K., Keller, J., and Valmassoi, A.: Towards a coupled km-scale Atmosphere-Land Reanalysis for Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20247, https://doi.org/10.5194/egusphere-egu24-20247, 2024.

EGU24-21583 | ECS | Posters on site | HS2.4.2 | Highlight

Influence of ENSO on extreme precipitation and peak river flow in the US 

Natalie Lord, Simbi Hatchard, Jorge Sebastian Moraga, Nans Addor, and Pete Uhe

Flooding in the US results in billions of dollars of losses every year. This is projected to increase further in many regions as the climate warms, due to a combination of more frequent and severe extreme rainfall events, with resulting impacts on flooding, and increased exposure as the population increases and development in flood-prone areas continues. Superimposed on this warming signal are the impacts of different internal cycles operating within the climate system on various timescales, such as El Niño Southern Oscillation (ENSO). These cycles may act to either exacerbate or reduce the severity of extreme precipitation and flooding, and on interannual timescales, ENSO is a dominant mode of variability. A better understanding of the influence of ENSO and other modes of variability on extreme precipitation and flooding, including under climate change, is important for a number of applications. These include climate change impact assessments, policy and decision-making, early warning systems for flooding and disaster response planning, and climate-related risk planning in the (re)insurance sector.

Here, we investigate the influence of ENSO on extreme precipitation and peak river flow in the US, under both historical and future climate conditions. For the historical period, we calculate annual maximum (AMAX) daily precipitation and flow, from the Multi-Source Weighted-Ensemble Precipitation (MSWEP) precipitation and USGS river gauge datasets, respectively. To assess whether positive, neutral, or negative phases of ENSO have a significant impact on extreme precipitation and flood magnitude, we calculate the correlation between AMAX and different ENSO phases. We use a number of different ENSO indices, including the Oceanic Niño Index (ONI) used operationally by NOAA, in order to test the sensitivity of these relationships to the method used to characterise ENSO.

We also assess the impacts of ENSO on projected future changes in AMAX precipitation, using climate model data from the Community Earth System Model Large Ensemble Project Phase 2 (CESM2-LENS). For this, we calculate the relative change in AMAX daily precipitation for positive, neutral, and negative phases of ENSO, to determine how projected extreme precipitation changes differ between the phases, and how this varies spatially across the US.

How to cite: Lord, N., Hatchard, S., Moraga, J. S., Addor, N., and Uhe, P.: Influence of ENSO on extreme precipitation and peak river flow in the US, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21583, https://doi.org/10.5194/egusphere-egu24-21583, 2024.

EGU24-1830 | ECS | Posters on site | OS1.9

A Detailed Analysis of the Diahaline Overturning Circulation in a Marginal Sea 

Erika Henell, Hans Burchard, Ulf Gräwe, and Knut Klingbeil

We apply a local water mass transformation framework to quantify and decompose the exchange flow associated with diahaline mixing. As a realistic example we analyze two years of numerical model results for the Baltic Sea, which serves as a natural laboratory for processes relevant on the global scale. Despite this regional focus, the diagnostic methods of this study are applicable to diverse regions, as well as for other tracers than salinity, e.g. temperature. We verify relations between local diahaline volume and diffusive salt fluxes, and local diahaline mixing, and present them as maps on chosen isohaline surfaces. In this way, hot spots for mixing and the diahaline circulation are visualized. Two dominant types of diahaline exchange flow are analyzed. First of all there is a large scale overturning circulation with inflow at places where the isohaline surface is close to the bottom and with outflow at places where the isohaline is surfacing. Secondly, there is the well-known small-scale overturning circulation localized inside the bottom boundary layer over sloping bathymetry, driven by boundary mixing. One major result is that about 50% of the simulated diahaline exchange flow is generated by numerical mixing caused by the truncation error of the advection scheme, despite the fact that an anti-diffusive advection scheme and vertically-adaptive coordinates are used. We also demonstrate how model ensembles can be used to study short-term episodic and local events.

How to cite: Henell, E., Burchard, H., Gräwe, U., and Klingbeil, K.: A Detailed Analysis of the Diahaline Overturning Circulation in a Marginal Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1830, https://doi.org/10.5194/egusphere-egu24-1830, 2024.

The atmospheric circulation response to global warming is an important problem that is theoretically still not well understood. This is a particular issue since climate model simulations provide uncertain, and at times contradic- tory, projections of future climate. In particular, it is still unclear how a warmer and moister atmosphere will affect midlati- tude eddies and their associated poleward transport of heat and moisture. Here we perform a trend analysis of three main components of the global circulation}the zonal-mean state, eddies, and the net energy input into the atmosphere}and examine how they relate in terms of a moist static energy budget for the JRA-55 reanalysis data. A particular emphasis is made on understanding the contribution of moisture to circulation trends. The observed trends are very different between the hemispheres. In the Southern Hemisphere there is an overall strengthening and during boreal summer, also a poleward shifting, of the jet stream, the eddies, and the meridional diabatic heating gradients. Correspondingly, we find an overall strengthening of the meridional gradients of the net atmospheric energy input. In the Northern Hemisphere, the trend pat- terns are more complex, with the dominant signal being a clear boreal winter Arctic amplification of positive trends in lower-tropospheric temperature and moisture, as well as a significant weakening of both bandpass and low-pass eddy heat and moisture fluxes. Consistently, surface latent and sensible heat fluxes, upward and downward longwave radiation, and longwave cloud radiative fluxes at high latitudes show significant trends. However, radiative fluxes and eddy fluxes are in- consistent, suggesting data assimilation procedures need to be improved.

How to cite: Franzke, C. and Harnik, N.: Long-Term Trends of the Atmospheric Circulation and Moist Static Energy Budget in the JRA-55 Reanalysis , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3002, https://doi.org/10.5194/egusphere-egu24-3002, 2024.

It has previously been shown that trends in sensible heat from climate models have had a substantial contribution to global precipitation changes. We illustrate that this is the case also in the most recent Coupled Model Intercomparison Project Phase 6 (CMIP6). However, we find that over the period since 1980 reanalysis do not support the reduction in sensible heat from the CMIP6 models and rather estimate a global increase in sensible heat which would contribute to a precipitation reduction. Satellite data over a period of 2 decades over global ocean similarly to reanalysis show an opposite sign of the sensible heat trend to the CMIP6 models.

How to cite: Myhre, G. and Jouan, C.: Strong contribution from sensible heat to global precipitation increase by climate models is not supported by observational based data. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3902, https://doi.org/10.5194/egusphere-egu24-3902, 2024.

EGU24-4138 | ECS | Posters on site | OS1.9

Robust predictions of changes in evenness of global precipitation under global warming 

Hsin Hsu and Stephan Fueglistaler

Global mean precipitation is anticipated to increase by 2-4% per degree Kelvin, with intense events scaling at 7%, driven by boundary layer humidity. The understanding of the change in daily-to-annual precipitation probability density function remains rather incomplete. To address this knowledge gap, we employ Gini index to evaluate spatial unevenness and temporal inequality of precipitation under global warming in CMIP6 models. We observe heightened spatial unevenness of daily precipitation in tropics and extratropics over land and ocean. While the tropics maintain this unevenness over time, indicating large-scale convection aggregation, extratropical precipitation evens out with increasing timescales. This disparity suggests distinct processes governing daily and annual mean precipitation, underscoring the intensification of stronger storms over weaker events.

 

Globally, temporal inequality is on the rise, with more pronounced intensification in regions where projected precipitation deviates significantly from Clausius–Clapeyron scaling. Our hypothesis posits that the shift in precipitation distribution under warming projections stems from an increase in no-rain days coupled with rainfall events scaled by a constant. To assess this proposition, we construct a toy model predicting projected temporal inequality based on local hydroclimate conditions pre-warming, the projected mean precipitation, and a theorem-derived stretching parameter. The toy model demonstrates robust performance overall, except in regions notably influenced by the Hadley cell. Additionally, the model suggests that local precipitation events are scaled by a constant of approximately 1.07. Our analysis establishes meaningful connections among changes in mean precipitation, precipitation distribution, and dry-day number, offering comprehensive insights into hydroclimate transformations under global warming.

How to cite: Hsu, H. and Fueglistaler, S.: Robust predictions of changes in evenness of global precipitation under global warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4138, https://doi.org/10.5194/egusphere-egu24-4138, 2024.

EGU24-6543 | Orals | OS1.9

Relative role of land and ocean in shaping tropical hydroclimate after large volcanic eruptions 

Claudia Timmreck, Roberta D'Agostino, Shih-Wei Fang, Andrew Ballinger, Gabriele Hegerl, Sarah Kang, Dirk Olonscheck, and Andrew Schurer

Volcanic eruptions substantially impact tropical precipitation over the historical period but they differ in their emission strength, geographical latitude and season of the eruption, which makes it difficult to draw general conclusions. Sufficient large ensembles simulations with the same model and radiative forcing scenario but varying initial conditions have become a great tool in recent years to disentangle forced and internal variability).  Here we use a suite of 100-member ensembles of the MPI-ESM-LR for idealized equatorial and extratropical eruptions of different eruption strengths and an additional 100-member ensemble without forcing. We find that precipitation reduction is primarily energetically constrained by less atmospheric net energy input (NEI).  NEI decreases rapidly in the first months after the eruption due to reduced incoming solar radiation and then the circulation weaken as a consequence of less moist static energy (MSE) exported away from the intertropical convergence zone. Only afterwards, when the overturning has already weakened, the MSE, and then the gross moist stability (GMS) contribute stronger to the precipitation reduction. Tropical precipitation over land reacts immediately to forcing changes, while the precipitation response over the ocean and the temperature response have much longer response times. Altered dry-wet pattern (“wet gets drier”) and the decreased monsoon precipitation are strongly tied to the weakening of the regional tropical overturning. Differences related to the geographical locations of the volcanic eruptions will be highlighted.

How to cite: Timmreck, C., D'Agostino, R., Fang, S.-W., Ballinger, A., Hegerl, G., Kang, S., Olonscheck, D., and Schurer, A.: Relative role of land and ocean in shaping tropical hydroclimate after large volcanic eruptions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6543, https://doi.org/10.5194/egusphere-egu24-6543, 2024.

The ocean temperature response to tropical cyclones (TCs) is important for TC development, local air–sea interactions, and the global air–sea heat budget and transport. As TCs and ocean temperature structures are changing in the recent decades, it is worthy to study their contribution on ocean heat uptake. The modulation of the upper ocean temperature structure after TCs were studied at the observation stations in the northern South China Sea. The upper ocean temperature and heat response to the TCs mainly depend on the combined effect of mixing and vertical advection. Mixing cooled the sea surface and warmed the subsurface, while upwelling (downwelling) reduced (increased) the subsurface warm anomaly and cooled (warmed) the deeper ocean. An ideal parameterization that depends on only the nondimensional mixing depth (HE), non-dimensional transition layer thickness (HT), and nondimensional upwelling depth (HU) was able to roughly reproduce sea surface temperature (SST) and upper ocean heat change. After TCs, the subsurface heat anomalies moved into the deeper ocean. The air–sea surface heat flux contributed little to the upper ocean temperature anomaly during the TC forcing stage and did not recover the surface ocean back to pre-TC conditions more than one and a half months after the TC. This work shows how upper ocean temperature and heat content varies by a TC, indicating that TC-induced mixing modulates the warm surface water into the subsurface, and TC-induced advection further modulates the warm water into the deeper ocean and influences the local and global ocean heat budget.

How to cite: Zhang, H.: Modulation of Ocean Temperature Structure and Heat Content by Tropical Cyclones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6938, https://doi.org/10.5194/egusphere-egu24-6938, 2024.

EGU24-7000 | ECS | Orals | OS1.9

Ocean heat uptake and interbasin redistribution driven by anthropogenic aerosols and greenhouse gases 

Shouwei Li, Wei Liu, Robert J. Allen, Jia-Rui Shi, and Laifang Li

Anthropogenic aerosols and greenhouse gases have played important roles in modulating the storage and distribution of heat in oceans since the industrial age. Here we isolate and quantify the effects of both using coupled climate model simulations. We show that, relative to the pre-industrial ocean, the Southern Ocean imports heat from the Indo-Pacific Ocean but exports heat into the Atlantic Ocean in response to anthropogenic aerosols. Ocean heat uptake diminishes in the subpolar Atlantic. Alterations in ocean circulation and temperature have a weak compensation in contributing to interbasin heat exchange. Consequently, interbasin heat exchange contributes comparably to ocean heat uptake changes to modifying the stored heat in the Atlantic and Indo-Pacific. The greenhouse-gas-associated changes are the opposite of the aerosol-associated changes. Anthropogenic greenhouse gases promote the ocean heat uptake in the subpolar Atlantic and allow the Southern Ocean to import heat from the Atlantic but export heat to the Indo-Pacific. The cause of this ocean heat redistribution is distinct from the aerosol-forcing scenario, seeing that ocean circulation effects are strongly offset by temperature shifts. Accordingly, interbasin heat exchange is much less important than ocean heat uptake changes for greenhouse-gas-associated ocean heat storage. Our results suggest that the aerosol-driven changes in ocean circulations and associated interbasin heat transports are more effective in altering oceanic heat distribution than those driven by globally increasing greenhouse gases.

How to cite: Li, S., Liu, W., Allen, R. J., Shi, J.-R., and Li, L.: Ocean heat uptake and interbasin redistribution driven by anthropogenic aerosols and greenhouse gases, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7000, https://doi.org/10.5194/egusphere-egu24-7000, 2024.

EGU24-7842 | Orals | OS1.9

Tracking sea salt instead of saline water 

Kristofer Döös, Inga Koszalka, and Lars Axell

Lagrangian (parcel following) approach is a powerful method to diagnose the modelled flow and associated property changes in atmosphere and ocean and is used to investigate causal links between the property changes between the different regions. The salt in the saline sea water has traditionally been tracked as tracer property or a marker of sea water despite the seawater is constituted of both water and salt molecules. In the present study, we propose an new approach relying on tracking  separately the mass of fresh water and salt in the ocean. As a study region we have chosen the Baltic Sea, a semi-enclosed sea characterised by a distinct estuarine circulation due to river runoff and deep salt water inflow from the North Sea. The salt was tracked by summing over both the advective and diffusive salt fluxes simulated by the circulation model NEMO. Salt and water trajectories were computed with the mass conserving TRACMASS model, where each trajectory tube is in units of m3/s of water flux or kg/s of salt flux. 
The preliminary results show a clear difference between salt and water trajectories, where e.g. the salt trajectories (red in the attached Figure) do not reach as far into the Baltic Sea as the (blue) water trajectories. Many diagnostics such as the residence time and age also differ, which opens up a completely new vision of the ocean circulation

.

Figure: Water mass (blue) and salt mass (red) trajectories entering the Baltic Sea through the Danish straits.

How to cite: Döös, K., Koszalka, I., and Axell, L.: Tracking sea salt instead of saline water, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7842, https://doi.org/10.5194/egusphere-egu24-7842, 2024.

EGU24-7960 | Orals | OS1.9

Zonal Wave Three: Trends and links to extreme events 

James Arthur Renwick

In the Southern Hemisphere atmospheric circulation, one of the most prominent wave patterns is zonal wave three (ZW3), which exhibits three positive and three negative anomalies in the zonal eddy field around the Southern Hemisphere, with maximum amplitude over the Southern Oceans. Using ERA5 data, this presentation will describe the form of ZW3 and trends in its behaviour. Over the past 60 years, the amplitude of ZW3 exhibits significant upward trends throughout the year but most prominently in summer (Dec-Feb). Such trends are related to increasing meridional temperature gradients and to trends in eddy activity in general and to trends in poleward energy fluxes. Implications for surface climate temperature and precipitation extremes will be outlined.

How to cite: Renwick, J. A.: Zonal Wave Three: Trends and links to extreme events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7960, https://doi.org/10.5194/egusphere-egu24-7960, 2024.

EGU24-8252 | ECS | Orals | OS1.9

Surface forcing controls on the volume and heat content of subtropical and subpolar mode waters over the global ocean 

Ciara Pimm, Richard Williams, Dani Jones, and Andrew Meijers

Mode waters provide an important role within the climate system, sequestering large amounts of heat and anthropogenic carbon and play a key role in the transport of these properties around the globe. Our aim is to assess the roles of local versus remote surface forcing in controlling the properties of mode waters over the northern Atlantic and Pacific basins and the Southern Ocean. A set of adjoint sensitivity experiments are conducted using the ECCOv4r4 state estimate to assess the impacts of surface heat flux, freshwater flux, and wind stresses on the volume and heat content of mode waters in density space. Mode waters are identified using areas of deep winter mixed layers and their characteristic temperature, stratification, and neutral density properties. The adjoint modelling approach calculates time-evolving sensitivity maps that identify where and when specific surface forcing impacts properties in the mode water formation sites. The sensitivity analysis reveals the dominance of local forcing from surface heat fluxes with surface cooling initially increasing volume. On longer time scales, the sensitivities have differing responses to surface forcing including surface heat loss leading to a delayed restratification due to a haline contribution after a thermal contribution is effectively damped. The responses of the mode waters to surface forcing are then compared across their formation sites, in the northern basins involving western boundary currents and gyre interiors and in the Southern Ocean involving the Antarctic Circumpolar Current.

How to cite: Pimm, C., Williams, R., Jones, D., and Meijers, A.: Surface forcing controls on the volume and heat content of subtropical and subpolar mode waters over the global ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8252, https://doi.org/10.5194/egusphere-egu24-8252, 2024.

EGU24-8399 | ECS | Posters on site | OS1.9

Future AMOC recovery modulated by atmospheric water vapor shortwave absorption 

Doseok Lee, Hanjun Kim, and Sarah Kang

The amount of shortwave radiation absorbed by atmospheric water vapor is highly model dependent. This study examines how differences in the atmospheric water vapor shortwave radiation absorption affect the CO2-induced climate response pattern. We control the atmospheric water vapor shortwave radiation absorption in Community Earth System Model 1.2.2 (CESM1-CAM4-POP2) by altering the water vapor shortwave absorptivity parameter k by 60% to 120% of the default value. The pre-industrial control simulations with different k values are integrated for 150 years and additional 150 years are integrated after abruptly quadrupling CO2 concentrations. Regardless of the k value, the Atlantic meridional overturning circulation (AMOC) weakens in response to the quadrupling of CO2. However, the simulation with a higher k value exhibits a faster AMOC recovery approximately 30 years after the quadrupled CO2, with the lowest k simulation exhibiting a persistent AMOC weakening with no sign of recovery for the entire 300-year integration period. The faster AMOC restoration with a larger k value is attributed to the climatologically colder and saltier subpolar North Atlantic sea surface condition arising from the larger Arctic sea ice fraction due to colder temperature associated with stronger atmospheric shortwave absorption. The colder and more saline subpolar North Atlantic sea surface facilitates a more rapid destratification of surface density, establishing a favorable condition for the AMOC restoration. The faster restoration of the AMOC with the higher k value leads to a larger inter-hemispheric energy asymmetry followed by a more northward ITCZ shift as well as a stronger equilibrium climate sensitivity. This study demonstrates the complex interaction among different elements within the Earth system, encompassing radiation, sea ice, AMOC, and large-scale atmospheric circulation, suggesting a way to reduce uncertainties in future climate projections by improving the parameterization of shortwave radiation absorption by atmospheric water vapor.

How to cite: Lee, D., Kim, H., and Kang, S.: Future AMOC recovery modulated by atmospheric water vapor shortwave absorption, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8399, https://doi.org/10.5194/egusphere-egu24-8399, 2024.

EGU24-10237 | ECS | Posters on site | OS1.9

New insights into seasonal to interannual salinity variability on the Northeast U.S. continental shelf and slope 

Svenja Ryan, Caroline C. Ummenhofer, and Glen G. Gawarkiewicz

The Northeast U.S. continental shelf is a highly productive and economically important region that has experienced robust changes in upper-ocean properties in recent decades. Warming rates exceed the global and North Atlantic average and in particular several episodes of anomalously warm temperatures, so called marine heatwaves, have had devastating impacts on regional fisheries over the past decade. There are also indicators of a salinification of the region, which might be linked to large-scale changes in the North Atlantic circulation as well as changes in regional processes, such as the number of Warm Core Rings shedding of the Gulf Stream, driving an increased salinity flux into the continental slope and shelf region. With now more than a decade of remote-sensing sea surface salinity data, we revisit seasonal to interannual salinity variability and assess the role of salinity for modulating stratification on the continental shelf. We provide important regional context for the interpretation of data from the OOI Coastal Pioneer array, a local shelf-break observatory. We find that the local seasonal cycle is an interplay of seasonal freshwater input via local river discharge, driving decreasing salinities in spring and summer not just on the shelf but also in the Slope Sea. An observed salinification in the fall is likely linked to offshore forcing over the slope associated with the presence of Warm Core Rings. A coherent low-frequency salinity variability is found over the slope and shelf region in the Mid-Atlantic Bight (MAB) and Gulf of Maine, highlighting that shelf conditions in particular in the MAB are not solely dominated by upstream shelf conditions but are significantly impacted by local offshore variability. Furthermore, we synthesise hydrographic data from the NOAA ECOsystem MONitoring (ECOMON) program to construct mean cross-shelf sections along the MAB to investigate the relative contributions of thermal and haline components to the seasonal stratification. Overall, salinity serves as a valuable tracer, in addition to temperature, of these multi-variate processes and with now more than a decade of satellite surface salinity can shed new light on the spatio-temporal variability on the Northeast U.S. continental shelf. 

How to cite: Ryan, S., Ummenhofer, C. C., and Gawarkiewicz, G. G.: New insights into seasonal to interannual salinity variability on the Northeast U.S. continental shelf and slope, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10237, https://doi.org/10.5194/egusphere-egu24-10237, 2024.

EGU24-10440 | ECS | Posters on site | OS1.9

Linking midlatitude transient eddy moist static energy transport and extratropical cyclones 

Jan Zibell, Sebastian Schemm, and Alejandro Hermoso Verger

Earth's equator-to-pole net radiation gradient is counteracted by poleward atmospheric energy transport. In the extratropics, the largest contribution to this poleward flux can be attributed to variability on the timescale of weather systems. Even though the radiative imbalance has been argued not to strongly differ in a warmer climate, the partitioning of heat flux into moist and dry components is expected to change due to a moister atmosphere. On the synoptic scale, an increase in moisture and associated latent heat release enhances the intensification of cyclones, prolongs cyclone lifetimes, and also strengthens downstream anticyclones. Conversely, latent heating locally alters static stability and thereby affects projected trends in baroclinicity, which in turn vary across height due to different trends in temperature. Given that these drivers of cyclones and thereby storm tracks are subject to change and the resulting interplay is complex, isolating the influence of changes in latent heating on cyclone number and storm track intensity is not straight-forward. By combining the global moist static energy (MSE) budget perspective with cyclone numbers and other feature-based characteristics such as intensity and intensification, we aim to better understand the role of latent heat transport and release on midlatitude storm tracks. In particular, we ask: How are changes in zonal and time mean poleward transient eddy MSE flux and its divergence related to changes in cyclone number and intensities?

We start investigating the linkage between MSE fluxes and surface cyclones in reanalysis data by calculating cyclone composites. These analyses reveal that in general, poleward flux in the vicinity of low-pressure systems reaches its maximum during the intensification phase and drops after cyclones reaching mature stage. Furthermore, MSE flux peaks slightly equatorward and downstream of the cyclone center. In the mean picture, this signal can be related to warm-sector flux along the cold front, also indicating that the footprint of cold-sector flux is not as dominant. Further separating dry and moist flux components is expected to reveal additional insight into how heat transport is distributed across cyclones. These diagnostics can readily be applied to climate model data and idealized aquaplanet simulations, which we make use of to reduce the complexity and single out the effect of individual drivers of storm track changes.

How to cite: Zibell, J., Schemm, S., and Hermoso Verger, A.: Linking midlatitude transient eddy moist static energy transport and extratropical cyclones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10440, https://doi.org/10.5194/egusphere-egu24-10440, 2024.

The Atlantic Multidecadal variability (AMV) is a multivariate climate phenomenon with wide societal impacts in the North Atlantic region and beyond. In order to gain insight into the circulation dynamics controlling the AMV, we calculate Atlantic upper ocean heat and salt budgets at the basin and sub basin scale, focussing on multi-year to multidecadal timescales, for the upper ocean using output from a subset of CMIP6 models which have the same ocean component (the NEMO model) at nominal horizontal resolutions of 1 degree, ¼ degree and 1/12 degree and corresponding atmosphere-forced ocean-only models. We decompose the advection term into geostrophic and ageostrophic components and further use a Reynolds type decomposition to understand contributions from time-mean versus transient components of the flow. We use a novel decomposition of the large-area heat budget which highlights contributions due to spatial covariance between the large scale circulation and temperature/salinity gradients. Finally we relate the spatial pattern of the heat and salt advection to the meridional overturning (zonal) and horizontal gyre (azonal) components of the flow.

How to cite: Sinha, B.: Simulation of historical ocean heat and salt content changes in the Atlantic basin in CMIP6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10628, https://doi.org/10.5194/egusphere-egu24-10628, 2024.

EGU24-11362 | ECS | Posters on site | OS1.9

Deep ocean hydrographic heterogeneity inferred from offshore geodetic experiments 

Anna Jegen, Dietrich Lange, Johannes Karstensen, Oscar Pizarro, and Heidrun Kopp

Observational evidence, supported by high resolution numerical model simulations, indicate that meso- and submesoscale dynamics exists in the deep ocean (>2000m). However, over most parts, observing the deep ocean is restricted to address either spatial but not temporal (ship surveys) or temporal but not spatial (moored sensors) scales of variability. The advent of a growing number of offshore geodesy experiments, conducted with networks of distributed sensor arrays, aiming to evaluate tectonic deformation through strain measurements can potentially provide new ways to observe deep sea hydrographic variability. Despite the different observing objectives of offshore geodetic and oceanographic experiments, a great overlap in the measured parameter space exists, which has motivated analyses exploring possible cross-benefits. Here we present the evaluation of temperature, pressure, and sound speed observations from a 2.5-year offshore geodesy experiment centered along the northern Chilean subduction zone (~21.5°S and ~71.5°W to ~70.5°W). Our analysis confirms multi-year warming trends that previous studies have reported for the deep ocean but shows an additional regionalization of warming trends. Superimposed onto the multi-year warming trend are temperature fluctuations that show multi-hourly to multi-weekly periods and amplitudes that show both spatial and depth/regional dependencies. Aside from a general decrease in energy levels of the fluctuations with depth, we see evidence of ocean-topography interactions through barotropic topography waves. Taken together, the observations reveal de-coupled dynamical regimes seaward and landward of the deep-sea trench that mark the extent of the abyssal part of the eastern boundary current off Chile and demonstrate the potential of time series from offshore geodetic surveys for hydrographic analyses.

How to cite: Jegen, A., Lange, D., Karstensen, J., Pizarro, O., and Kopp, H.: Deep ocean hydrographic heterogeneity inferred from offshore geodetic experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11362, https://doi.org/10.5194/egusphere-egu24-11362, 2024.

EGU24-11856 | ECS | Posters on site | OS1.9

Seasonal Salinification of the US Northeast Continental Shelf Driven by an Imbalance Between Along-Shelf Advection and Cross-Shelf Eddy-Covariance Fluxes 

Lukas Taenzer, Ke Chen, Albert Plueddemann, and Glen Gawarkiewicz

The US Northeast continental shelf “cold pool” defines the body of winter-cooled Shelf Water that decouples from the surface layer during the stratified season. The cold pool canonically preserves fresh Shelf Water properties throughout the summer, which fulfills vital needs for the regional benthic ecosystem in the economically most productive fisheries region across the United States. However, recent warming trends significantly above the global average have put the ecosystem under environmental stress. While the cold pool’s heat content has been studied in detail, data limitations and large interannual variability in salinity have hampered an assessment of the cold pool’s salt budget. Here, we provide first evidence that the cold pool’s salt content increases significantly during the stratified season and investigate dynamical drivers of this trend, using a combination of multi-year mooring and glider observations and high-resolution regional model output. Cold pool salinification rates of 6 mPSU/day remain steady throughout the stratified season, leading to salinity differences of 1 PSU between April and October. The annual cold pool salinification is caused by an imbalance between eddy-covariance salt fluxes across the US Northeast shelfbreak front and advection of freshwater from upstream. While eddy-fluxes deposit salt onto the continental shelf at all times of year, the US Northeast shelfbreak jet is weakest during the summer, which reduces along-shelf advection. A seasonal reduction in the along-shelf salinity gradient is likely caused by processes in the Gulf of Maine/on Georges Bank. The observed interannual variability of the salinification signal is shaped by the intermittency of strong cross-shelfbreak eddy-covariance fluxes that are concentrated within 3-4 episodic events per year. Capturing the hydrographic trends in coastal water mass budgets and identifying their underlying dynamical mechanisms will lead to a better understanding of ecosystem responses and support sustainable fisheries management in a rapidly changing coastal ocean region. 

How to cite: Taenzer, L., Chen, K., Plueddemann, A., and Gawarkiewicz, G.: Seasonal Salinification of the US Northeast Continental Shelf Driven by an Imbalance Between Along-Shelf Advection and Cross-Shelf Eddy-Covariance Fluxes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11856, https://doi.org/10.5194/egusphere-egu24-11856, 2024.

EGU24-11925 | Posters virtual | OS1.9

Spontaneous equatorial flow reversals at the equator in  moist shallow water turbulence 

Nili Harnik, Josef Schröttle, Dl Suhas, and Jai Sukhatme

Equatorial superrotation is a striking feature in planetary circulations, also found in atmospheric circulation models. Geological evidence shows that Earth was in a state of super-rotation during the Eocene and Pliocene. On Earth, such a time period of super-rotation is sometimes referred to as permanent El Niño. While it is well established that a tropical wave source is needed for superrotation, the mechanism that provides this wave source, and what conditions allow it to be maintained are still not understood, and vary between different models. Specifically, in shallow water models with Earth like parameters, superrotation has only been found when relatively strong thermal damping was added. In this study we examine the spontaneous evolution of super-rotation in fully developed isotropically forced two-dimensional moist shallow-water turbulence, and examine the role of moisture by varying the strength of moisture coupling, and performing large ensembles of simulations. 

We find that while the dry runs exhibit both superrotation and sub-rotation, with spontaneous transitions between the two states, moisture results in all runs eventually reaching a stable superrotating state. We further find that a stable superrotation develops in the dry runs when we strengthen the thermal damping. We find that a meridional mass flux from the equator to the subtropics, develops in the runs with stable superrotation, and examine the role of this mass flux, which is enabled by the latent heating and the thermal damping, for the maintenance of the stable superrotation. 

How to cite: Harnik, N., Schröttle, J., Suhas, D., and Sukhatme, J.: Spontaneous equatorial flow reversals at the equator in  moist shallow water turbulence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11925, https://doi.org/10.5194/egusphere-egu24-11925, 2024.

EGU24-13947 | ECS | Posters on site | OS1.9

An Argo Float Study of Temperature and Salinity in the Subpolar region of the Cambpell Plateau 

Ana Amaral Wasielesky, Milena Menna, Angelo Rubino, Riccardo Martellucci, Yuri Cotroneo, Giuseppe Aulicino, Antonino Ian Ferola, and Elena Mauri

The Subantarctic region of New Zealand is marked by a unique and complex bathymetry that includes an ocean ridge and a substantial submarine plateau known as the Campbell Plateau. This plateau is located near the Pacific sector of the Southern Ocean, and plays a vital role in the export of heat, salt, and nutrients into the lower thermocline, primarily through the formation of mode waters. In the present study, Argo floats data from 2003 to 2023 are used to identify the main water masses along the eastern margin of the Campbell Plateau. This region, located at the boundary between subtropical and subantarctic fronts, is characterized by the formation of Sub-Antarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW), which make an important contribution to the broader oceanic circulation patterns. First results reveal the presence of eight distinct water masses in the study region and emphasize their peculiar seasonal variability. A decadal analysis describes colder waters in the period 2003-2013 compared to 2014-2023, while significant changes in salinity are observed in 2017-2018. Water mass identification, depicted through Temperature-Salinity plots, is consistent with existing literature, but can also provide new insights on the interaction between subantarctic and subtropical waters. This research contributes to describe the ocean dynamic of Subantarctic New Zealand. The use of Argo float data provides an unprecedented level of detail in examining the spatial and temporal resolution of an area located between two different current systems, whose changes potentially influence the global and Southern Ocean circulation patterns, with consequent implication on the climate.

How to cite: Amaral Wasielesky, A., Menna, M., Rubino, A., Martellucci, R., Cotroneo, Y., Aulicino, G., Ferola, A. I., and Mauri, E.: An Argo Float Study of Temperature and Salinity in the Subpolar region of the Cambpell Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13947, https://doi.org/10.5194/egusphere-egu24-13947, 2024.

EGU24-14534 | Posters on site | OS1.9

A new spice/heave decomposition of thermohaline variability 

Remi Tailleux

The temporal variability of temperature and salinity in the oceans is strongly impacted by the ocean stratification, which tends to constrain lateral advection and mixing to preferentially take place along approximately neutral surfaces. As a result, it is natural to seek a decomposition of thermohaline variability into heave and spice components, which splits temperature and salinity into a component contributing to density and one that is density-compensated. In this talk, I will outline the theoretical foundations for such an approach, based on a recent redefinition of spiciness, and illustrate its usefulness for understanding the variability of the ocean heat and salt contents in the EN4 dataset over the past century.

How to cite: Tailleux, R.: A new spice/heave decomposition of thermohaline variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14534, https://doi.org/10.5194/egusphere-egu24-14534, 2024.

EGU24-14622 | ECS | Posters on site | OS1.9

Multidecadal meridional dipole mode in the Indian Ocean subsurface ocean heat content 

Anand Babu Amere, Mihir Kumar Dash, and Balaji Senapati

Multidecadal changes in the background state of the Indian Ocean, such as variations in ocean circulation patterns, sea level and heat storage, can act as a carrier wave for the climate change and other variabilities. The long-term (~60 years since 1958) analysis of subsurface ocean heat content (sub-OHC) in the Indian Ocean exhibits the presence of a dominant multidecadal meridional dipole mode in the region. The analysis shows that until the late 1980s, a basin-wide meridional dipole mode is present, followed by the mode embedded in uniform basin-wide patterns. The trends of thermocline depth and sea surface height also exhibit the similar patterns. It is found that two distinct mechanisms are account for the observed patters in the Indian Ocean. Firstly, Local wind forcing is responsible for the meridional dipole patterns. In the off-equatorial southern Indian Ocean region, wind stress and Ekman pumping velocity trends favor downwelling (upwelling), resulting in thermocline depth deepening (shallowing) during 1958-1975 and 1976-1987, respectively. Secondly, the observed basin-wide warming and cooling trends during 1988-2000 and 2001-2014 are explained by the combined effect of local wind forcing and heat transport from the western Pacific through the Indonesian throughflow.

How to cite: Amere, A. B., Dash, M. K., and Senapati, B.: Multidecadal meridional dipole mode in the Indian Ocean subsurface ocean heat content, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14622, https://doi.org/10.5194/egusphere-egu24-14622, 2024.

EGU24-15419 | ECS | Posters on site | OS1.9

Multi-centennial evolution of the climate response and deep ocean heat uptake in a set of abrupt stabilization scenarios 

Federico Fabiano, Paolo Davini, Virna L. Meccia, Giuseppe Zappa, Alessio Bellucci, Valerio Lembo, Katinka Bellomo, and Susanna Corti

A set of 1000-year long abrupt stabilization simulations have been performed with the EC-Earth3 climate model. Each simulation follows a sudden stabilization of the external forcing, starting at different years of the CMIP6 historical and SSP5-8.5 scenario. The final global mean temperature increases range between 1.4 and 9.6 K with respect to the pre-industrial baseline.

We first explore here the evolution of the climate response at multi-centennial timescales and its dependence on the level of forcing, with regards to the climate feedback parameter and to patterns of surface warming. We then focus on the rate of heat storage in the global ocean, which is the main driver of the climate response at multi-centennial timescales. We find that the rate of warming of the deep ocean is almost independent from the amplitude of the forcing, so that most of the additional heat remains in the upper layers at high forcing. We hypothesize that this is due - at least partly - to a decreased ventilation of the deep ocean, caused by a general reorganization of the Meridional Overturning Circulation (MOC).

 

How to cite: Fabiano, F., Davini, P., Meccia, V. L., Zappa, G., Bellucci, A., Lembo, V., Bellomo, K., and Corti, S.: Multi-centennial evolution of the climate response and deep ocean heat uptake in a set of abrupt stabilization scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15419, https://doi.org/10.5194/egusphere-egu24-15419, 2024.

EGU24-16423 | ECS | Posters on site | OS1.9

Estimating Atlantic meridional heat transport through Bayesian modelling of altimetry, Argo and GRACE data 

Parvathi Vallivattathillam and Francisco M Calafat

The Atlantic Meridional Overturning Circulation (AMOC) plays a pivotal role in the meridional transport of heat, freshwater and major dissolved gases such as carbon, and oxygen, making it a crucial component of earth’s climate system and the biosphere. On millennial timescales, the AMOC is believed to act as a conveyor belt of ocean currents wherein the flow varies coherently across latitudes. Past studies have drawn on this conveyor-belt idea to establish links between the AMOC and the Earth's climate tipping points. However, recent research and observations suggest that, on shorter timescales (days to decades), the AMOC may not operate as coherent flow of water. Understanding AMOC variability and coherence on such timescales and how these might respond to anthropogenic influences is crucial to predicting the climate of the next decades. This is, however, challenging due to the sparseness of the observational data in both time and space. Here, we present a Bayesian Hierarchical modelling framework that combines observations from altimetry, gravimetry, and Argo floats to estimate meridional heat transport across the Atlantic. Our approach considers error structures jointly and accounts for spatiotemporal dependencies between processes (thermosteric, halosteric and ocean mass), providing a coherent way to propagate uncertainty and overcoming the limitations of hydrography-only based analyses. Our estimate of heat transport is in very good agreement (correlation of ~0.8 for 3-month means) with that from RAPID observations at 26°N. A meticulous comparison of mean and variance further underscores the precision of our estimates compared to those derived from heat budgets. Our method can be extended to gain further insights into the dynamics and meridional coherence of AMOC at shorter timescales.

How to cite: Vallivattathillam, P. and Calafat, F. M.: Estimating Atlantic meridional heat transport through Bayesian modelling of altimetry, Argo and GRACE data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16423, https://doi.org/10.5194/egusphere-egu24-16423, 2024.

EGU24-16722 | ECS | Posters on site | OS1.9

On critical dependence of atmospheric circulation response to regional SST biases on background SST 

Yuan-Bing Zhao, Nedjeljka Zagar, and Frank Lunkeit

This study examines how the geographic location of sea surface temperature (SST) biases influences global atmospheric responses. Utilizing an intermediate-complexity atmospheric model, 106 century-long simulations with idealized SST perturbations—emulating biases in coupled climate models—were performed. The intensity of the global atmospheric response to SST biases is evaluated by quantifying changes in global wave energy and interannual variance. The findings underscore the response's dependency on local background SST. Notably, with an imposed SST bias of +1.5 K, a significant global response is triggered once background SST surpasses approximately 25°C. This geographic dependency is related to the critical SST threshold for intense convection. Consequently, these results highlight the need for heightened focus on tropical oceans, especially the Indo-West Pacific, where SST biases can significantly impact the accuracy of global climate simulations.

How to cite: Zhao, Y.-B., Zagar, N., and Lunkeit, F.: On critical dependence of atmospheric circulation response to regional SST biases on background SST, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16722, https://doi.org/10.5194/egusphere-egu24-16722, 2024.

EGU24-17118 | Posters on site | OS1.9

Heating rate and energy gradient from the tropics to the North Pole 

Luca Ferrero, Niccolò Losi, Martin Rigler, Asta Gregorič, Griša Močnik, Piotr Markuszewski, Przemysław Makuch, Tymon Zielinski, Paulina Pakszys, Matteo Rinaldi, Marco Paglione, Angelo Lupi, and Ezio Bolzacchini

Absorbing aerosol species, such as Black (BC) and Brown (BrC) Carbon, are able to warm the atmosphere. The role of aerosols is one of the least clear aspects in the so called “Arctic Amplification” (AA) and up to now this was mostly modelled [1,2]. For this reason, we took part in four scientific cruises (AREX, Arctic-Expedition, summer 2018, 2019, 2021 and EUREC4A, 2020) in the North Atlantic, eastward and south-eastward of Barbados, aiming at the determination of the aerosol chemical composition and properties from the Tropics to the North Pole.

The Heating Rate (HR) was experimentally determined at 1 minute time-resolution along different latitudes by means of an innovative methodology [3], obtained by cumulatively taking into account the aerosol optical properties, i.e. the absorption coefficients (measured by AE33 Aethalometer) and incident radiation (direct, diffuse and reflected) across the entire solar spectrum. The HR computed along AREX and in Milan (in the same period) were used to determine the energy gradient, due to the LAA induced heat storage at mid-latitudes, which contributes to AA through the atmospheric heat transport northward.

Moreover, aerosol chemical composition was achieved by means of sampling via high volume sampler (ECHO-PUF Tecora) and analysis via ion chromatography, TCA08 for Total Carbon content, Aethalometer AE33 (for BC), ICP-OES for elements.

A clear latitudinal behaviour in Black Carbon concentrations, with the highest values at low latitudes (e.g. average BC concentration in Gdansk up to 1507±75 ng/m3) and a progressive decrease moving northwards and away from the big Arctic settlements (Black Carbon concentrations within the 81st parallel: 5±1 ng/m3).

According to the latitudinal behaviour of BC concentrations and solar radiation (decreases towards the north while the diffuse component increases), HR decreases noticeably towards the Arctic: e.g. higher in the harbor of Gdansk (0.290±0.010 K/day) followed by the Baltic Sea (0.04±0.01 K/day), the Norvegian Sea (0.010±0.010 K/day) and finally with the lowest values in the pure Arctic Ocean (0.003±0.001 K/day). Accordingly, the energy density added to the system by the aerosol, a positive forcing that differs by 2 orders of magnitude between mid-latitudes and North Pole was found: 347.3 ± 11.8 J/m3 (Milan), 244.8 ± 12.2 J/m3 (Gdansk) and 2.6 ± 0.2 J/m3 (80°N). These results highlight the presence of a great energy gradient between mid-latitudes and Arctic that can trigger a heat transport towards the Arctic. Moreover this was strengthen by the HR value for EUREC4A in Barbados that was 0.175±0.003 K/day. Finally, preliminary results from Antarctica collected onboard the Italian RV Laura Bassi cruising the Southern Ocean and the Ross Sea will be shown.

 

 

Acknoledgements: GEMMA Center, Project TECLA MIUR – Dipartimenti di Eccellenza 2023–2027. JPI EUREC4A-OA project. CAIAC (oCean Atmosphere Interactions in the Antarctic regions and Convergence latitude) PNRA project

 

References

[1] Navarro, J. C. A. et al. (2016) Nat. Geosci. 9, 277–281.

[2] Shindell, D. and Faluvegi, G. (2009) Nat. Geosci. 2, 294–300.

[3] Ferrero, L. et al. (2018) Environ. Sci. Technol. 52, 3546 3555.

How to cite: Ferrero, L., Losi, N., Rigler, M., Gregorič, A., Močnik, G., Markuszewski, P., Makuch, P., Zielinski, T., Pakszys, P., Rinaldi, M., Paglione, M., Lupi, A., and Bolzacchini, E.: Heating rate and energy gradient from the tropics to the North Pole, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17118, https://doi.org/10.5194/egusphere-egu24-17118, 2024.

After many decades of relative stability, the heat content of the oceans has been increasing at a relatively steady rate since the late 70’s, as confirmed by the analysis of many observational datasets. How global warming affects the available potential energy (APE) of the oceans, however, has received comparatively much less attention, yet is important to assess changes in the strength of wind-driven gyres and Antarctic Circumpolar Current for instance. In this talk, I will contrast the temporal changes over the past century of the APE and background potential energy (BPE) of the oceans based on the analysis of the EN4 dataset, by making use of the most recent local theory of APE. Results show that temporal changes in the BPE mimic that of the ocean heat content estimated in terms of potential temperature or Conservative Temperature. In contrast to the ocean heat content, the total APE of the oceans does not exhibit any marked trend. In this talk, I will discuss how regional APE estimates differ from the global APE estimate, to identify whether global warming has any detectable impact the large-scale ocean circulation features.

How to cite: Tailleux, R.: A complete energy analysis of ocean background and available potential energy over the past century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17583, https://doi.org/10.5194/egusphere-egu24-17583, 2024.

EGU24-19893 | Posters on site | OS1.9

Analysis of water mass transformations and the spurious thermohaline overturning circulation in numerical ocean models 

Knut Klingbeil, Erika Henell, Tridib Banerjee, Hans Burchard, and Sergey Danilov

Numerical models have become an important tool for investigating the oceans heat and salt contents. The large-scale thermohaline overturning circulation in the world ocean is directly linked to the transformation of water masses caused by small-scale diapycnal mixing, which is parameterized in models. However, in addition to this physically justified "physical mixing", numerical transport schemes rely on additional "numerical mixing" for stability reasons. Thus, the simulated overturning circulation in ocean models is strongly affected by this spurious mixing.
Diagnostics of spurious mixing in terms of local tracer variance decay offer a detailed analysis of water mass transformations (WMT). Vice versa, analysis methods for WMT can be used to deduce information about the effects of mixing. In contrast to direct mixing diagnostics based on discrete variance decay (DVD) in geographical space, the WMT analysis framework is based on a mapping to tracer space, where diatracer fluxes that quantify the WMT can directly be diagnosed. Recently, a new local framework was derived, which combines the classical WMT framework with the local DVD analysis (Klingbeil & Henell, 2023). The derived analytical relations between dia-surface fluxes and mixing were demonstrated in an isohaline framework by Henell et al. (2023) [see corresponding submission to this session].
We will present how this methodology can be transferred to the world ocean in order to diagnose local diapycnal mixing and to quantify the spurious contribution to the simulated thermohaline overturning circulation in ocean models. In particular, the extension to density space requires the consistent quantification of density DVD, which is challenging in numerical models with prognostic equations for salinity and temperature and a non-linear equation of state.

 

Henell, E., H. Burchard, U. Gräwe, K. Klingbeil (2023) Spatial composition of the diahaline overturning circulation in a fjord-type, non-tidal estuarine system. Journal of Geophysical Research (Oceans). https://dx.doi.org/10.1029/2023JC019862.

Klingbeil, K. and E. Henell (2023) A Rigorous Derivation of the Water Mass Transformation Framework, the Relation between Mixing and Diasurface Exchange Flow, and Links to Recent Theories in Estuarine Research. Journal of Physical Oceanography. https://doi.org/10.1175/JPO-D-23-0130.1.

How to cite: Klingbeil, K., Henell, E., Banerjee, T., Burchard, H., and Danilov, S.: Analysis of water mass transformations and the spurious thermohaline overturning circulation in numerical ocean models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19893, https://doi.org/10.5194/egusphere-egu24-19893, 2024.

EGU24-20262 | ECS | Posters on site | OS1.9

Multi-scale temperature variability in the Arctic Mediterranean between 1958 to 2023 – from surface to abyss  

Birgit Rinde, Shengping He, and Camille Li

The temperature of the Arctic Ocean and adjacent areas has increased over recent decades and is expected to continue to increase through this century. Discrepancies between previous studies based on different periods, domains, and datasets suggest that the warming of the Arctic Ocean is nonlinear and characterized by large temporal and spatial variability. The behavior of this warming signal has numerous local effects on aspects from sea ice cover and surface fluxes to ecosystems, all of which react differently to linear warming compared to episodic warming events. The spatiotemporal warming pattern will also play a role in defining the product of dense-water formation in the region, which feeds into the lower limb of the Atlantic Meridional Overturning Circulation. Utilizing the ORAS5 reanalysis, the Arctic Subpolar gyre sTate Estimates, as well as in-situ observations, we present an overview of the warming of the Arctic Ocean and the Nordic Seas between 1958 and 2023. We shed light on the variability of trends and seasonal signals across the Arctic Ocean, from surface to abyss. This analysis provides a solid baseline for detecting regional changes in the mean state and variability of the Arctic Ocean with global warming and exploring the physical mechanisms causing the warming trend. As such, it will be key for grounding investigations of future changes in heat budgets for the Arctic Ocean and the Nordic Seas. 

How to cite: Rinde, B., He, S., and Li, C.: Multi-scale temperature variability in the Arctic Mediterranean between 1958 to 2023 – from surface to abyss , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20262, https://doi.org/10.5194/egusphere-egu24-20262, 2024.

EGU24-1036 | ECS | Orals | NP1.5

Exploring Noise-induced and CO2-driven AMOC collapses in the PlaSIM-LSG climate model with a Rare Event Algorithm. 

Matteo Cini, Giuseppe Zappa, Francesco Ragone, and Susanna Corti

Earth-system Models of Intermediate Complexity (EMICs) are climate models featuring a simplified representation of climate processes and a much lower computation cost. This makes them particularly suitable for exploring phenomena with a large ensemble simulation approach. Here we use the coupled atmosphere-ocean PlaSIM-LSG EMIC to study the possibility of Atlantic Meridional Overturning Circulation (AMOC) spontaneous collapses and how this is altered in the presence of external anthropogenic forcing. Understanding the stability of the AMOC and its response to anthropogenic forcing is of key importance for advancing climate science. The idea of a “safe-operating space” has been proposed in order to define a threshold on anthropogenic forcing within which the AMOC does not lose stability. This requires understanding the combined action of CO2-driven and noise-induced processes in climate tipping events

 First, we address the occurrence of noise-induced AMOC collapses, i.e. spontaneous abrupt weakening  events induced by chaotic internal climate variability in absence of any external forcing. We address the problem of finding these extreme events via the application of a Rare Event Algorithm, which - via a selective cloning of the most interesting model trajectories -  allows a faster exploration of the model phase space in the direction of an AMOC decrease. The algorithm is applied to a PlaSIM-LSG ensemble simulation run at T21 spectral resolution in the atmosphere, and 3.5 degrees in the ocean, with fixed pre-industrial conditions. A number of collapse events, unseen in the pre-industrial control run, are sampled by the algorithm. Looking at the mechanisms causing the AMOC spontaneous collapse, we find that zonal wind stress over the North Atlantic is the main driver of the initial AMOC slowdown, while the suppression of surface convection in the Labrador sea is the likely cause of the subsequent AMOC collapse. Then, we investigate the influence of increasing CO2 levels on the frequency of these spontaneous AMOC collapses. We show that a higher CO2 not only leads to the well-known weakening of the AMOC mean state, but it also increases the possibility of incurring in abrupt noise-induced transitions. The employment of EMICs, combined with the proposed approach, samples a large number of rare phenomena. This procedure allows us to explore statistical properties that are not accessible with a deterministic approach in state-of-the-art high resolution models.

How to cite: Cini, M., Zappa, G., Ragone, F., and Corti, S.: Exploring Noise-induced and CO2-driven AMOC collapses in the PlaSIM-LSG climate model with a Rare Event Algorithm., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1036, https://doi.org/10.5194/egusphere-egu24-1036, 2024.

EGU24-2167 | ECS | Posters on site | NP1.5

Early-Warning Signs for SPDEs under Boundary Noise 

Paolo Bernuzzi, Christian Kuehn, and Henk Dijkstra

The search of early-warning signs able to predict the approach of a parameter to a deterministic bifurcation threshold is relevant in climate as it aims to enable a proper prediction of qualitative changes in the studied models. The observation of such objects in SPDEs (stochastic partial differential equations) permits the consideration of space variables and the ensuing heterogeneity in the behaviour of their solutions.

The presence of Gaussian noise on the boundary of the studied space is used in order to build the signals, whose properties are discussed thoroughly. An example in the form of application of such tools on a climate model is presented and justified. The utility and appropriate use of the results on a more applied perspective are shown.

How to cite: Bernuzzi, P., Kuehn, C., and Dijkstra, H.: Early-Warning Signs for SPDEs under Boundary Noise, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2167, https://doi.org/10.5194/egusphere-egu24-2167, 2024.

Aeolus 2.0 is an open-source numerical atmosphere model with intermediate complexity designed to capture the dynamics of the atmosphere, especially extreme weather and climate events. The model's dynamical core is built on a novel multi-layer pseudo-spectral moist-convective Thermal Rotating Shallow Water (mcTRSW) model, and it utilizes the Dedalus algorithm, renowned for its efficient handling of spin-weighted spherical harmonics in solving pseudo-spectral problems. Aeolus 2.0 comprehensively characterizes the temporal and spatial evolution of key atmospheric variables, including vertically integrated potential temperature, thickness, water vapor, precipitation, and the influence of bottom topography, radiative transfer, and insolation. It provides a versatile platform with resolutions ranging from smooth to coarse, enabling the exploration of a wide spectrum of dynamic phenomena with varying levels of detail and precision.

The model has been utilized to investigate the adjustment of large-scale localized buoyancy anomalies in mid-latitude and equatorial regions, along with the nonlinear evolution of key variables in both adiabatic and moist-convective environments. Our findings highlight the triggering mechanisms of phenomena such as the Madden-Julian Oscillation (MJO) and the circulation patterns induced by temperature anomalies and buoyancy fields. Furthermore, our simulations of large-scale localized temperature anomalies reveal insights into the impact of perturbation strength, size, and vertical structure on the evolution of eddy heat fluxes, including poleward heat flux, energy, and meridional elongation of the buoyancy field. We observe the initiation of atmospheric instability, leading to precipitation systems, such as rain bands, and asymmetric latent heat release due to moist convection in diabatic environments. This study identifies distinct patterns, including the formation of a comma cloud pattern in the upper troposphere and a comma-shaped buoyancy anomaly in the lower layer, accompanied by the emission of inertia gravity waves. Additionally, the role of buoyancy anomalies in generating heatwaves and precipitation patterns is emphasized, particularly in mid-latitude regions.

In summary, Aeolus 2.0, with its specific capabilities, contributes to our understanding of the complex interactions of moist convection, buoyancy anomalies, and atmospheric dynamics, shedding light on the dynamics of extreme weather events and their implications for climate studies.

References

1. Rostami, M., Zhao, B., & Petri, S. (2022). On the genesis and dynamics of MaddenJulian oscillation-like structure formed by equatorial adjustment of localized heating. Quarterly Journal of the Royal Meteorological Society, 148 (749), 3788-3813. Retrieved from https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.4388 doi: https://doi.org/10.1002/qj.4388

2. Rostami, M., Severino, L., Petri, S., & Hariri, S. (2023). Dynamics of localized extreme heatwaves in the mid-latitude atmosphere: A conceptual examination. Atmospheric Science Letters, e1188. Retrieved from https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/asl.1188 doi: https://doi.org/10.1002/asl.1188

How to cite: Rostami, M. and Petri, S.: Exploring Extreme Weather and Climate Events with Aeolus 2.0: A Multi-layer moist-convective Thermal Rotating Shallow Water (mcTRSW) Dynamical Core, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2867, https://doi.org/10.5194/egusphere-egu24-2867, 2024.

EGU24-4539 | ECS | Posters on site | NP1.5

Extreme value methods in dynamical systems of different complexity 

Ignacio del Amo, George Datseris, and Mark Holland

Extreme value theory provides a universal limit for the extremes of continuous independent and identically distributed random variables and has proven to be robust to generalisation to wider classes of random variables, including stationary processes, some nonstationary processes and even trajectories on deterministic chaotic systems. This universality, together with the fact that these methods require data from only one realization of the system, has been exploited in applications to study many series of climate data.

Fitting a probability distribution to the extreme events of a data series generated by a chaotic dynamical system gives us not only probabilistic predictions of the intensity and return time of the events themselves, but also geometrical information about the local structure of the attractor and the predictability and persistence of the extreme events.

However, these methods are sensitive to the mathematical properties of the dynamical system that generates the data, and are seldomly even mentioned when they are applied to real climate data. One further caveat of these methods is that they are hard to falsify, i.e. we cannot verify easily if an answer is wrong. For these reasons, we explore how these methods respond to different systems with different complexity and different mathematical properties, trying to understand which of the results on the literature could meaningful and which could be numerical artifacts.

How to cite: del Amo, I., Datseris, G., and Holland, M.: Extreme value methods in dynamical systems of different complexity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4539, https://doi.org/10.5194/egusphere-egu24-4539, 2024.

Within the climate model hierarchy, simple models usually play the important role of highlighting dynamical processes that can possibly govern climate phenomena. If, in addition, their results are in significant agreement with observations, the processes thus identified are even more likely to regulate the actual phenomena. In this context, the dynamical process of intrinsic variability paced by a deterministic forcing (also called deterministic excitation, DE [1]) is highlighted here by two simple models of different degrees of complexity and set in the different contexts of paleoclimate and physical oceanography. In both cases, despite the simplicity of the models, the results show significant agreement with observations.

The DE mechanism requires the system (i) to possess intrinsic nonlinear relaxation oscillations (ROs) and (ii) to be in the excitable state (i.e., ROs do not emerge spontaneously but can be excited, and therefore paced, by a suitable forcing); moreover, (iii) ROs are excited by a deterministic forcing if a given tipping point is passed.

In the first case [1], the abrupt late Pleistocene glacial terminations are shown by a conceptual model to correspond to the excitation, by the astronomical forcing, of ROs describing glacial-interglacial transitions (e.g., [2]). In the second case [3], ROs describing the Kuroshio Extension low-frequency variability [4] are shown, by a primitive equation ocean model, to be excited remotely by the North Pacific Oscillation. These results show how simple modeling approaches of different complexity advance process understanding and can, therefore, provide theoretical guidelines for interpreting state-of-the-art ESM results.

[1] Pierini S., 2023: The deterministic excitation paradigm and the late Pleistocene glacial terminations. Chaos, 33, 033108.

[2] Gildor H. and E. Tziperman, 2001: A sea ice climate switch mechanism for the 100-kyr glacial cycles. J. Geophys. Res., 106, 9117–9133.

[3] Pierini S., 2014: Kuroshio Extension bimodality and the North Pacific Oscillation: a case of intrinsic variability paced by external forcing. J. Climate, 27, 448-454.

[4] Pierini S., 2006: A Kuroshio Extension System model study: decadal chaotic self-sustained oscillations. J. Phys. Oceanogr., 36, 1605-1625.

How to cite: Pierini, S.: Simple oceanographic and paleoclimate modeling highlights the same dynamical process: intrinsic variability paced by a deterministic forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4679, https://doi.org/10.5194/egusphere-egu24-4679, 2024.

EGU24-5570 | ECS | Orals | NP1.5

The critical precipitation threshold for the Amazon forest biomass in the LPJmL vegetation model 

Da Nian, Sebastian Bathiany, Boris Sakschewski, Markus Drüke, Lana Blaschke, Maya Ben-Yami, Werner von Bloh, and Niklas Boers

The Amazon rainforest, one of the most important biomes in the world, and recognized as a potential tipping element in the Earth system, has received increasing attention in recent years. Theory and observations suggest that regional climate change from greenhouse gas emissions and deforestation may push the remaining forest toward a catastrophic tipping point.

Despite the urgency to assess the future fate of the Amazon, it remains unclear if state-of-the-art Dynamic Global Vegetation Models (DGVMs) can capture the highly nonlinear dynamics underlying such potentially abrupt dynamics and there is a noticeable scarcity of DGVM evaluations regarding their potential to predict forthcoming tipping points.

In our manuscript, we systematically investigate how the Amazon forest responds in idealized scenarios where precipitation is linearly decreased and subsequently increased between current levels and zero, using the state-of-the-art model LPJmL. We investigate whether large-scale abrupt changes and tipping points occur, and whether early warning signals as expected from theory can be detected. 

Our results indicate a pronounced nonlinearity but reversible behavior between vegetation aboveground biomass (AGB) and mean annual precipitation (MAP) in the LPJmL simulations. In particular, there exists a threshold at a critical rainfall level below which there is a rapid decrease in forest biomass. The value of the threshold is determined by seasonality, evapotranspiration and the adaptive capacity of roots. Significant "early warning signs" can be detected before the transition.

How to cite: Nian, D., Bathiany, S., Sakschewski, B., Drüke, M., Blaschke, L., Ben-Yami, M., von Bloh, W., and Boers, N.: The critical precipitation threshold for the Amazon forest biomass in the LPJmL vegetation model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5570, https://doi.org/10.5194/egusphere-egu24-5570, 2024.

EGU24-8104 | ECS | Posters on site | NP1.5

Disentangling the dynamics of the subpolar gyre and its interaction with the AMOC in the CMIP6 ensemble 

Swinda Falkena and Anna von der Heydt

The subpolar gyre (SPG) is one of the climate tipping elements which could have a large impact on the climate in the northern hemisphere. Improving our understanding of its dynamics is key to assessing the likelihood of it passing a tipping point. Some CMIP6 models exhibit abrupt transitions in the sea surface temperature in the SPG region, but the majority does not. The differences in the model response can be related to the stratification bias, with many models having a too strong stratification preventing them from exhibiting bistable gyre dynamics.

To better understand the SPG we study the (lagged) partial correlations between the relevant aspects of its dynamics in the CMIP6 ensemble. In contrast to standard correlations, partial correlations correct for the effect of autocorrelation and the effect of (the past of) other relevant variables. Therefore, it gives a better indication of there being a causal relation. Based on the partial correlation between the sea surface temperature and mixed layer depth we split the ensemble into two groups (strong or negligible relation) and for each select one model to study its dynamics in detail. In addition, we discuss the interaction of the SPG with the Atlantic Meridional Overturning Circulation (AMOC) using the same methods. These results can help in better informing more conceptual climate models of the SPG, AMOC and their interactions, which can be used to study potential tipping dynamics.

How to cite: Falkena, S. and von der Heydt, A.: Disentangling the dynamics of the subpolar gyre and its interaction with the AMOC in the CMIP6 ensemble, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8104, https://doi.org/10.5194/egusphere-egu24-8104, 2024.

EGU24-8117 | Posters on site | NP1.5

Using a simple model to measure the differences between climate model land surface simulations and FLUXNET observations 

F. Hugo Lambert, Claire Zarakas, Monisha Natchiar S. R., Abigail L. S. Swann, and Charles D. Koven

Complex numerical models of climate consist of simulation of fluid dynamics and thermodynamics on a discrete grid, and parameterizations, which are algorithms that approximate processes smaller than gridscale. Because parameterizations of a given process may be written as different functions of different, potentially non-observable variables, it can be difficult to quantify the process differences between individual climate models and between climate models and the real world.

Here, we attempt to write down a simple linear model that represents the response of the Earth's tropical land surface to atmospheric forcing on monthly timescales in terms of the same observable variables using a technique called continuous structural parameterization. Simulated data are taken from complex General Circulation Models (GCMs) run under the AMIP protocol and a CESM2 perturbed physics ensemble (PPE) of our own devising;  observed measurements are taken from FLUXNET flux tower sites. We find that the simple model captures land surface behaviour well except in mountainous regions.

Establishing a generalised parameter space, we see that most GCMs are in reasonable agreement with FLUXNET at FLUXNET sites, although there is evidence that GCMs consistently slightly overestimate the response of surface turbulent fluxes to downward radiation. Further, it is found that the differences between structurally different AMIP models are considerably greater than the differences between CESM2 PPE members -- even though the PPE parameters are varied across their realistic domain. If the simple model is trained only at GCM spatial gridpoints that contain a FLUXNET site, there is little degradation in simple model performance compared with global training, suggesting that even the few available tropical FLUXNET sites are useful for constraining land surface model response throughout the tropics. This is of course contingent on whether or not point measurements taken by FLUXNET are representative of the wider area around FLUXNET sites.

How to cite: Lambert, F. H., Zarakas, C., Natchiar S. R., M., Swann, A. L. S., and Koven, C. D.: Using a simple model to measure the differences between climate model land surface simulations and FLUXNET observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8117, https://doi.org/10.5194/egusphere-egu24-8117, 2024.

EGU24-8397 | ECS | Orals | NP1.5

AMOC Stability amid Tipping Ice Sheets from Conceptual to Intermediate Complexity Models 

Sacha Sinet, Anna S. von der Heydt, Peter Ashwin, and Henk A. Dijkstra

The Atlantic Meridional Overturning Circulation (AMOC) and polar ice sheets are considered susceptible to critical transitions under climate change. Identified as core tipping elements, their collapse would have global and drastic consequences. Furthermore, the AMOC and polar ice sheets form a complex interacting system, where the collapse of one component can heavily impact the stability of others. In the worst case, this could result in a large-scale domino effect, otherwise known as a cascading tipping event.

In this presentation, our focus is on assessing the stability of the AMOC in the presence of tipping Greenland ice sheet (GIS) and West Antarctica ice sheet (WAIS). While most existing studies agree on the destabilizing impact of a GIS collapse on the AMOC, the consequences of a WAIS collapse remain uncertain. A previous conceptual study suggested that a WAIS tipping event might actually prevent an AMOC collapse against both climate warming and increased GIS meltwater fluxes. Using a better conceptual model of the AMOC, we demonstrate that both the melting rate and natural variability associated with surface meltwater fluxes are decisive factors for this phenomenon to occur. Finally, we present preliminary findings in which the relevance of this stabilizing effect is investigated in the model of intermediate complexity CLIMBER-X.

How to cite: Sinet, S., von der Heydt, A. S., Ashwin, P., and Dijkstra, H. A.: AMOC Stability amid Tipping Ice Sheets from Conceptual to Intermediate Complexity Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8397, https://doi.org/10.5194/egusphere-egu24-8397, 2024.

EGU24-8729 | ECS | Orals | NP1.5

Quantifying risk of a noise-induced AMOC collapse from northern and tropical Atlantic Ocean variability 

Ruth Chapman, Peter Ashwin, Richard Wood, and Jonathan Baker

The Atlantic Meridional Overturning Circulation (AMOC) exerts a major influence on global climate. There is much debate about whether the current strong AMOC may collapse as a result of anthropogenic forcing and/or natural variability. Here, we ask whether internal decadal variability could affect the likelihood of AMOC collapse. We examine natural variability of basin-scale salinities and temperatures in four CMIP6 pre-industrial runs. We fit the CMIP6 variability to several empirical, linear noise models, and to a nonlinear, process-based AMOC model. The variability is weak and its processes inconsistent among the CMIP6 models considered. Based on the CMIP6 variability levels we find that noise-induced AMOC collapse is unlikely in the pre-industrial climate, but plausible if external forcing has shifted the AMOC closer to a threshold, which can be identified for the non-linear model using bifurcation analysis. However the CMIP6 models may systematically underestimate current Atlantic Ocean variability, and we find that substantially stronger variability would increase the likelihood of noise-induced collapse.

How to cite: Chapman, R., Ashwin, P., Wood, R., and Baker, J.: Quantifying risk of a noise-induced AMOC collapse from northern and tropical Atlantic Ocean variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8729, https://doi.org/10.5194/egusphere-egu24-8729, 2024.

EGU24-9253 | ECS | Posters on site | NP1.5

The impact of model resolution on variability in a coupled land atmosphere model 

Oisín Hamilton, Jonathan Demaeyer, Anupama Xavier, and Stéphane Vannitsem

Reduced order quasi-geostrophic land-atmosphere coupled models display qualitatively realistic mid-latitude atmosphere behaviour, meaning that such models can produce typical atmospheric dynamical features such as atmospheric blocking. At the same time, due to a low number of degrees of freedom, they are still simple enough to allow for analysis of the system dynamics. These features mean that these models are well suited to investigating bifurcations in atmospheric dynamics, and use a dynamical systems approach to better understand the corresponding atmospheric behaviour. 

This project introduces a symbolic python workflow for using the flexible  land-atmosphere (qgs, 2020) spectral model with the continuation software AUTO. This work builds on the results of Xavier et al. (2023) to understand how the model variability and predictability is impacted by the model resolution. We also use bifurcation diagrams to better understand how parameters such as atmosphere-land friction impact the atmospheric blocking, and in turn the model atmosphere predictability. This is done for a range of model resolutions to investigate how the number of degrees of freedom impacts both the realism of the model, but also the structures found in the dynamics.

 

Demaeyer, Jonathan & De Cruz, Lesley & Vannitsem, S.: qgs: A flexible Python framework of reduced-order multiscale climate models. Journal of Open Source Software. 5. 2597. 10.21105/joss.02597, 2020. 

 

Xavier, A. K., Demaeyer, J., and Vannitsem, S.: Variability and Predictability of a reduced-order land atmosphere coupled model, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-2257, 2023.

How to cite: Hamilton, O., Demaeyer, J., Xavier, A., and Vannitsem, S.: The impact of model resolution on variability in a coupled land atmosphere model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9253, https://doi.org/10.5194/egusphere-egu24-9253, 2024.

EGU24-10070 | ECS | Posters on site | NP1.5

Spatial fluctuations of the Arctic sea ice border 

Clara Hummel

Every year, the area of the Arctic sea-ice decreases in the boreal spring and summer and reaches its yearly minimum in the early autumn. Due to global warming, Arctic summer sea ice will most probably disappear. As the sea ice cover decreases, its border is retreating northwards towards the central Arctic. This retreat is not uniform in space and the variability of the border’s movement further North could yield an early warning signal for summer sea ice loss. Here, we track the sea ice border from time series obtained from models of various complexity and observations to study the spatial variability of the border’s movement as Arctic summer sea ice approaches its disappearance.

How to cite: Hummel, C.: Spatial fluctuations of the Arctic sea ice border, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10070, https://doi.org/10.5194/egusphere-egu24-10070, 2024.

EGU24-11984 | Posters on site | NP1.5

Dependence of simulated variability of surface climate on model complexity – insights from an ensemble of transient simulations of the Last Deglaciation 

Elisa Ziegler, Nils Weitzel, Jean-Philippe Baudouin, Marie-Luise Kapsch, Uwe Mikolajewicz, Lauren Gregoire, Ruza Ivanovic, Paul Valdes, Christian Wirths, and Kira Rehfeld

Climate variability is crucial to our understanding of future climate change and its impacts on societies and the natural world. However, the climate records of the observational era are too short to explore long-term variability. Conversely, an exploration of long transient simulations from state-of-the-art Earth System Models (ESMs) poses high computational demands. It is therefore pertinent to identify the level of complexity sufficient to simulate the variability of surface climate from annual to centennial and longer timescales.

To this end, we use an ensemble of transient simulations of the Last Deglaciation, the last period of significant global warming. The ensemble covers an energy balance model (EBM), models of intermediate complexity (EMICs), general circulation models (GCMs) and ESMs. This constitutes a hierarchy that we categorize based on employed atmosphere and ocean components and their resolution, as well as implemented radiation, land hydrology, vegetation and aerosol schemes.

To investigate the simulated variability of surface temperature and precipitation, we analyze changes in the shapes of their distributions as characterized by their higher order moments – variance, skewness, kurtosis – with warming. These higher order moments relate the tails to the extremes of the distributions. We identify spatial and temporal patterns and how they depend on model complexity. The EMICs can generally match the global and latitudinal changes in temperature variability found in more complex models. However, they lack in precipitation variability. We further find that the EMICs fail to simulate the tails of the precipitation distributions. We observe dependency of variability on the background state, generally increasing with model complexity. However, there is still a large spread between models of similar complexity, some of which can be related to differences in forcings. Furthermore, questions remain on the abilities of models of any complexity to simulate a magnitude of long-term variability similar to that found regionally in proxy reconstructions. Our analysis offers implications as to the complexity needed and sufficient for capturing the full picture of climate change and we offer some first insights into how the findings translate to future projections of climate change.

How to cite: Ziegler, E., Weitzel, N., Baudouin, J.-P., Kapsch, M.-L., Mikolajewicz, U., Gregoire, L., Ivanovic, R., Valdes, P., Wirths, C., and Rehfeld, K.: Dependence of simulated variability of surface climate on model complexity – insights from an ensemble of transient simulations of the Last Deglaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11984, https://doi.org/10.5194/egusphere-egu24-11984, 2024.

EGU24-12421 | Posters on site | NP1.5

A Novel Process Model of Ocean-Sea-Ice Interaction Using CESM 

Paul Hall, Christopher Horvat, Baylor Fox-Kemper, Samuel Brenner, and Alper Altuntas

We report on the development of a novel process model created to study ocean-sea ice interaction and the dynamics of the upper ocean in the marginal ice zone (MIZ), built using the Community Earth System Model (CESM). Our model uses the MOM6 ocean model and CICE6 sea-ice model as active components within CESM, on a custom ~50km x ~50km grid with a horizontal resolution of ~50m, extending to a depth of 75m (30 vertical layers). The model allows for either reflecting or zonally re-entrant boundary configurations. Atmospheric forcing is imposed through a simplified data atmosphere component that provides constant forcing over the model domain. Results from several simple scenarios are presented and compared to results obtained using the MITgcm.

By working within CESM, we are able to leverage CESM’s existing infrastructure and capabilities, including the use of the Community Mediator for Earth Prediction Systems (CMEPS) for coupling between active components. Furthermore, additional model components that are already available within CESM (e.g., waves, atmosphere) can be incorporated into the process model in a straightforward way. Future work will include incorporation of a modified sea-ice component that allows tracking of individual floes utilizing a discrete element method approach.

How to cite: Hall, P., Horvat, C., Fox-Kemper, B., Brenner, S., and Altuntas, A.: A Novel Process Model of Ocean-Sea-Ice Interaction Using CESM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12421, https://doi.org/10.5194/egusphere-egu24-12421, 2024.

EGU24-14067 | ECS | Orals | NP1.5

A Forecast Test for Reducing Dynamical Dimensionality of Model Emulators 

Tongtong Xu, Matthew Newman, Michael Alexander, and Antonietta Capotondi

The climate system can be numerically represented by a set of physically-based dynamical equations whose solution requires substantial computational resources. This makes computationally efficient, low dimensional emulators that simulate trajectories of the underlying dynamical system an attractive alternative for model evaluation and diagnosis. We suggest that since such an emulator must adequately capture anomaly evolution, its construction should employ a grid search technique where maximum forecast skill determines the best reference model. In this study, we demonstrate this approach by testing different bases used to construct a Linear Inverse Model (LIM), a stochastically-forced multivariate linear model that has often been used to represent the evolution of coarse-grained climate anomalies in both models and observations. LIM state vectors are typically represented in a basis of the leading Empirical Orthogonal Functions (EOFs), but while dominant large-scale climate variations often are captured by a subset of these statistical patterns, key precursor dynamics involving relatively small scales are not. An alternative approach is balanced truncation, where the dynamical system is transformed into its Hankel space, whose modes span both precursors and their subsequent responses. Constructing EOF- and Hankel-based LIMs from monthly observed anomalous Pacific sea surface temperatures, both for the 150-yr observational record and a perfect model study using 600 yrs of LIM output, we find that no balanced truncation model of any dimension can outperform an EOF-based LIM whose dimension is chosen to maximize independent skill. However, the dynamics of a high-dimensional EOF-based LIM can be efficiently reproduced by far fewer Hankel modes.

How to cite: Xu, T., Newman, M., Alexander, M., and Capotondi, A.: A Forecast Test for Reducing Dynamical Dimensionality of Model Emulators, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14067, https://doi.org/10.5194/egusphere-egu24-14067, 2024.

EGU24-14439 | ECS | Posters on site | NP1.5

Nonlocal energy fluxes and fractional operators in updated, stochastic, Budyko-Sellers models 

dustin lebiadowski and shaun Lovejoy

We introduce a stochastic, energy-balance, climate model defined over the macroweather regime (approximately 15 days or longer). Together, the energy balance principle, combined with the model’s natural scaling, demonstrate quite promising results despite the relative simplicity. A special case of the model can also be derived from a very classical basis, and, because of some similarities, we propose this model as a development upon the work of Budyko and Sellers.

When the classical Budyko-Sellers energy balance model is updated by using the (correct) radiative-conductive surface boundary conditions, one obtains the Fractional Energy Balance Equation (FEBE). The FEBE involves fractional space-time operators and its generic solutions are scaling, in agreement with much atmospheric and oceanic data. In time, it implies long range memories that have been successfully used to make both multi-decadal climate projections as well as monthly and seasonal (long range) forecasts. In space, the FEBE is nonlocal so that energy flux imbalances at any location can affect the balance in locations far away. This is possible because the model operates over monthly and longer time scales; over these scales, energy can be both stored and transported in the atmosphere, ocean, and subsurface.

Until now, the FEBE’s full nonlocal space-time interaction operator has been only approximated. Here, by introducing a numerical model, the nonlocal dynamics of the FEBE and corresponding Earth-system FEBE energy flows over the 2D Earth surface are fully detailed.

We propose the FEBE as an alternative to more conventional, deterministic, weather-regime-based climate models. Given the generality of the ideas pursued here - the use of fractional operators; the use of stochasticity and the macroweather regime - there seems a great potential for these to be used much more widely. Hopefully this research, and possibly related works, will encourage a greater diversity of pursuits and be inspiring to others in their own work.

How to cite: lebiadowski, D. and Lovejoy, S.: Nonlocal energy fluxes and fractional operators in updated, stochastic, Budyko-Sellers models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14439, https://doi.org/10.5194/egusphere-egu24-14439, 2024.

EGU24-14831 | ECS | Orals | NP1.5

SPEEDY-NEMO: performance and applications of a fully-coupled intermediate-complexity climate model 

Paolo Ruggieri, Muhammad Adnan Abid, Javier Garcia-Serrano, Carlo Grancini, Fred Kucharski, Salvatore Pascale, and Danila Volpi

A fully-coupled general circulation model of intermediate complexity is documented. The study presents an overview of the model climatology and variability, with particular attention for the phenomenology of processes that are relevant for the predictability of the climate system on seasonal-to-decadal time-scales. It is shown that the model can realistically simulate the general circulation of the atmosphere and the ocean, as well as the major modes of climate variability on the examined time-scales: e.g. El Niño-Southern Oscillation, North Atlantic Oscillation, Tropical Atlantic Variability, Pacific Decadal Variability, Atlantic Multi-decadal Variability. We demonstrate the ability of the model in simulating non-stationarity of coupled ocean-atmosphere modes of variability. Potential applications of the model are discussed, with emphasis on the possibility to generate sets of low-cost large-ensemble retrospective forecasts. We argue that the presented model is suitable to be employed in traditional and innovative model experiments that can play a significant role in future developments of seasonal-to-decadal climate prediction.

How to cite: Ruggieri, P., Abid, M. A., Garcia-Serrano, J., Grancini, C., Kucharski, F., Pascale, S., and Volpi, D.: SPEEDY-NEMO: performance and applications of a fully-coupled intermediate-complexity climate model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14831, https://doi.org/10.5194/egusphere-egu24-14831, 2024.

EGU24-16958 | Orals | NP1.5

The Challenge of Non-Markovian Energy Balance Models in Climate 

Nicholas Wynn Watkins, Raphael Calel, Sandra Chapman, Aleksei Chechkin, Rainer Klages, and David Stainforth

Hasselmann’s paradigm, introduced in 1976 and recently honoured with the Nobel Prize, can, like many key innovations in the sciences of climate and complexity, be understood on several different levels, both technical and conceptual. It can be seen as a mathematical technique to add stochastic variability into pioneering energy balance models (EBMs) of Budyko and Sellers. On a more conceptual level, it used the mathematics  of Brownian motion to provide an  abstract superstructure linking slow climate variability to fast weather fluctuations, in a context broader than EBMs, leading Hasselmann to posit the need for negative feedback in climate modelling.

Hasselmann's paradigm itself has much still to offer us [e.g. Calel et al, Naure Communications, 2020], but naturally, since the 1970s a number of newer developments have built on his pioneering ideas. One important one has been the development of a rigorous mathematical hierarchy that embeds Hasselmann-type models in the more comprehensive Mori-Zwanzig (MZ) framework  (e.g.  Lucarini and Chekroun, Nature Reviews Physics, 2023). Another has been the interest in long range memory in stochastic EBMs, notably Lovejoy et al’s Fractional Energy Balance Equation [FEBE, discussed in this week’s Short Course SC5.15 ]. These have a memory with slower decay and thus longer range than the exponential form seen in Hasselmann’s EBM. My presentation [based on Watkins et al, in review at Chaos] attempts to build a bridge between MZ-based extensions of  Hasselmann, and the fractional derivative-based FEBE model.  I will argue that the Mori-Kubo overdamped Generalised Langevin Equation, as widely used in statistical mechanics, suggests the form of a relatively simple stochastic EBM with memory for the global temperature anomaly, and will discuss how this relates to FEBE.

How to cite: Watkins, N. W., Calel, R., Chapman, S., Chechkin, A., Klages, R., and Stainforth, D.: The Challenge of Non-Markovian Energy Balance Models in Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16958, https://doi.org/10.5194/egusphere-egu24-16958, 2024.

EGU24-18360 | Posters on site | NP1.5

Eddy Saturation and Latitudinal Storm Track Shift in a Reduced Two-level Model of the Atmosphere 

Valerio Lucarini, Melanie Kobras, and Maarten Ambaum

We introduce a minimal dynamical system derived from the classical Phillips two-level model with the goal of elucidating the essential mechanisms responsible for the interaction between eddies and mean flow. The choice of a two-level model as starting points allows for appreciating the relative role of barotropic and baroclinic processes. Specifically, we wish to explore the eddy saturation mechanism, whereby, when average conditions are considered, direct forcing of the zonal flow increases the eddy kinetic energy, while the energy associated with the zonal flow does not increase. The eddy-driven jet stream and storm tracks in the mid-latitude atmosphere are known to shift in latitude on various timescales, but the physical processes that cause these shifts are still unclear. Using our low-order model, we aim to understand the link between the structure of the eddies and the shift of the latitudinal maximum of the zonal flow in the mid-latitude atmosphere. Our findings elucidate the basic mechanisms behind baroclinic adjustment and provide insights into the properties of the storm track change between the jet entrance and jet exit regions of the North Atlantic.

How to cite: Lucarini, V., Kobras, M., and Ambaum, M.: Eddy Saturation and Latitudinal Storm Track Shift in a Reduced Two-level Model of the Atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18360, https://doi.org/10.5194/egusphere-egu24-18360, 2024.

EGU24-18412 | ECS | Orals | NP1.5

Rapid Emulation of Spatially Resolved Temperature Response Functions to Effective Radiative Forcing 

Christopher Womack, Noelle Eckley Selin, and Sebastian Eastham

We utilize ideas from signal processing to demonstrate a novel methodology for climate emulation based on the response of the climate system to effective radiative forcing (ERF). While previous work has demonstrated the efficacy of impulse response functions as a tool for climate emulation, these methods are largely non-generalizable to new scenarios and are inaccessible to more general audiences. To remedy this, we propose a generalizable framework for emulation of climate variables such as near-surface air temperature, representing the climate system through the surrogate of spatially resolved impulse response functions. These response functions are derived through the deconvolution of ERF and near-surface air temperature profiles, treating ERF and near-surface air temperature as input and output signals, respectively. Using this framework, new scenarios can be quickly and easily emulated through convolution and other sets of impulse response functions can be derived from any pair of climate variables. We present results from an application to near-surface air temperature based on ERF and temperature data taken from experiments in the sixth phase of the Coupled Model Intercomparison Project (CMIP6). We evaluate the emulator using additional experiments taken from the CMIP6 archive, including the Shared Socioeconomic Pathways (SSPs), demonstrating accurate emulation of global mean and spatially resolved temperature change with respect to the outputs of the CMIP6 ensemble. Global absolute error in emulated temperature averages 0.25 degrees Celsius with a bias ranging from -0.14 to -0.04 degrees Celsius. We additionally show how our emulator can be implemented as a tool for climate education through integration with the En-ROADS platform, providing fast visualizations of spatially resolved temperature change for a number of policy-relevant scenarios. While it is unable to capture state-dependent climate feedbacks, such as the non-linear effects of Arctic sea ice melt in high-warming scenarios, our results show that the emulator is generalizable to any scenario independent of the specific forcings present.

How to cite: Womack, C., Eckley Selin, N., and Eastham, S.: Rapid Emulation of Spatially Resolved Temperature Response Functions to Effective Radiative Forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18412, https://doi.org/10.5194/egusphere-egu24-18412, 2024.

EGU24-22102 | Orals | NP1.5 | Highlight

From conceptual to complex earth system models: why are models so linear? 

Victor Brovkin, Tobias Stacke, Philipp de Vrese, Thomas Kleinen, and Alexander Winkler

The evolution of the Earth’s climate from the past to the future is explored by a hierarchy of models ranging from conceptual models to full-complexity, high-resolution Earth System Models (ESMs) (Claussen et al., 2002). The strength of conceptual models lies in the clarity of representing the concept of interactions between different climate processes, while ESMs  offer greater realism when it comes to spatial or temporal detail. Intermediate complexity models are somewhere in between, they are able to provide a big picture for long timescales. A common pattern throughout the model hierarchy, except for conceptual models illustrating multiple steady states, is often linearity of model responses to external forcing. This linearity can be visible in transient experiments, but also in equilibrium simulations. The question arises: is this linearity an artefact of our models, or is it reflective of reality?

 

In most cases, the linear response is likely representative of reality. As an example, we will focus on the linearity of land-related processes, such as climate-carbon feedbacks and permafrost-hydrology interactions. Permafrost systems have thresholds at 0°C, leading to nonlinearities at the local scale, but the combined response at large spatial scales tends to be more linear. However, nonlinear and abrupt changes are evident in geological records. For instance, the abrupt onset of the Bölling/Alleröd warming about 14.8 thousand years ago indicates that nonlinear changes on large spatial scales are indeed a real, albeit very rare, phenomenon. We will discuss possible reasons for the predominant linearity of the models and explore whether high-resolution models might show more nonlinear responses than coarse-grid models.

 

Reference:

Claussen, M., Mysak, L., Weaver, A. et al. Earth system models of intermediate complexity: closing the gap in the spectrum of climate system models. Climate Dynamics 18, 579–586 (2002). https://doi.org/10.1007/s00382-001-0200-1

How to cite: Brovkin, V., Stacke, T., de Vrese, P., Kleinen, T., and Winkler, A.: From conceptual to complex earth system models: why are models so linear?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22102, https://doi.org/10.5194/egusphere-egu24-22102, 2024.

EGU24-2344 | ECS | Orals | NP3.3

A North Atlantic Ocean-originated mode of the AMOC multicentennial variability 

Kunpeng Yang, Haijun Yang, and Mengyu Liu

A multicentennial oscillation (MCO) of the Atlantic meridional overturning circulation (AMOC) is exhibited in a CESM1 control simulation. It primarily arises from internal oceanic processes in the North Atlantic, potentially representing a North Atlantic Ocean-originated mode of AMOC multicentennial variability (MCV) in reality. Specifically, this AMOC MCO is mainly driven by salinity variation in the subpolar upper North Atlantic, which dominates local density variation. Salinity anomaly in the subpolar upper ocean is enhanced by the well-known positive salinity advection feedback that is realized through anomalous advection in the subtropical-subpolar upper ocean. Meanwhile, mean advection moves salinity anomaly in the subtropical intermediate ocean northward, weakening the subpolar upper salinity anomaly and leading to its phase change. This mechanism aligns with a theoretical model we proposed earlier. In this theoretical model, artificially deactivating either the anomalous or mean advection in the AMOC upper branch prevents it from exhibiting AMOC MCO, underscoring the indispensability of both the anomalous and mean advections in this North Atlantic Ocean-originated AMOC MCO. In our coupled model simulation, the South Atlantic and Southern Ocean do not exhibit variabilities synchronous with the AMOC MCO; the Arctic Ocean’s contribution to the subpolar upper salinity anomaly is much weaker than the North Atlantic. Hence, this North Atlantic Ocean-originated AMOC MCO is distinct from the previously proposed Southern Ocean-originated and Arctic Ocean-originated AMOC MCOs. 

How to cite: Yang, K., Yang, H., and Liu, M.: A North Atlantic Ocean-originated mode of the AMOC multicentennial variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2344, https://doi.org/10.5194/egusphere-egu24-2344, 2024.

EGU24-3084 | ECS | Posters on site | NP3.3

Spatio-temporal climate fingerprint in palaeoclimate data vs models 

Vanessa Skiba, Andrew Dolman, Raphaël Hébert, Mara McPartland, and Thomas Laepple

Knowledge on natural climate variability is pivotal for making future climate projections. Previous studies demonstrated that centennial to millennial temperature variability is lacking in climate model simulations and that this bias is spatially heterogeneous. Various mechanisms have been proposed that might be important to modulate this low-frequency variability such as the ocean circulation, the meridional temperature gradient or external forcing and climate sensitivity to that forcing, but the evidence to identify the main driver(s) is still debated. Here, we provide preliminary insights on the respective importance of those mechanisms in driving long-term climate variability by investigating spatial patterns of low-frequency climate variability.

Low-frequency variability beyond multi-decadal timescales cannot be studied using only instrumental data due to data limitations and the confounding impact of anthropogenic forcing. Consequently, noisy and biased palaeoclimate proxy observations have to be utilised in order to investigate spatio-temporal patterns of climate change. Using a multi-archive and -proxy approach, we characterise the first-order spatial pattern of low-frequency climate variability of interglacial periods. By combining information on the spatio-temporal fingerprint derived from various archives and proxies with different characteristics, we aim to identify the common climate variability signal and assess the ability of climate models to explain the proxy-based spatial pattern of low-frequency variability.

How to cite: Skiba, V., Dolman, A., Hébert, R., McPartland, M., and Laepple, T.: Spatio-temporal climate fingerprint in palaeoclimate data vs models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3084, https://doi.org/10.5194/egusphere-egu24-3084, 2024.

EGU24-3157 | ECS | Posters on site | NP3.3

Power law error growth in a more realistic atmospheric Lorenz system with three spatiotemporal scales 

Hynek Bednar and Holger Kantz

Inspired by the Lorenz (2005) system, we mimic an atmospheric variable in one dimension, which can be decomposed into three spatiotemporal scales. This is motivated by and consistent with scale phenomena in the atmosphere. When studying the initial error growth in this system, it turns out that small scale phenomena, which contribute little to the forecast product, significantly affect the ability to predict this product. In other words, a more precise knowledge of the initial condition does not translate into a longer closeness of the forecast to the truth. Lorenz gave a sketch of such error growth. After a fast growth of the small scale errors with saturation at these very same small scales, the large scale errors continue to grow at a slower rate until even these saturate. We will present that scale dependent error growth can be translated into power law error growth. We will explain how parameter values of the power law are related to the error growth properties of the individual scales. We apply the results to the initial error growth of numerical weather prediction systems and show that the validity of the power law would imply a finite prediction horizon.

How to cite: Bednar, H. and Kantz, H.: Power law error growth in a more realistic atmospheric Lorenz system with three spatiotemporal scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3157, https://doi.org/10.5194/egusphere-egu24-3157, 2024.

EGU24-4074 | ECS | Posters on site | NP3.3

A model-data comparison of North Atlantic climate variability and its responses to natural forcing over the last millennium  

Qin Tao, Jesper Sjolte, and Raimund Muscheler

North Atlantic climate variability is to a large extent governed by the recurring modes of atmospheric circulation, also exhibiting impacts of volcanic and solar activities. These factors emphasize the importance of evaluating the leading variability modes and their responses to natural forcing in climate models for assessing the North Atlantic-European climate predictions. The recent availability of spatial field reconstructions of atmospheric circulation over the last millennium offers a unique opportunity for the paleo-evaluation of CMIP-PMIP models for these purposes across annual to centennial timescales. Particularly, with the possibility of comparing the spatial structure of variability.


In this study, we perform a model-data comparison of the North Atlantic climate focusing on the leading variability modes (North Atlantic Oscillation, NAO; East Atlantic Pattern, EA; Scandinavian Pattern, SCA) and the imprints of major natural forcing over the last millennium. We first develop an updated version of climate field reconstructions covering the past 700 years by assimilating proxy records into isotope-enabled simulations. This new version shows improved skills in reproducing the leading variability modes to serve as a reference for the comparisons with the past1000 runs. We then evaluate the multidecadal spatial variability in winter modes from the last millennium to the end of the 21st century. The models generally have a good representation of the average spatial structures of the NAO, EA and SCA patterns, but with persistent biases in their spatial variability. Particularly, the underestimated spatial shift in the NAO centres of action is directly related to the biases in regional temperature and precipitation changes. Furthermore, we examine the volcanic and solar imprints over the last millennium. Although not all the models can reproduce the significant NAO responses to volcanic eruptions as shown in the reconstructions, they do capture some NAO-like signals mixed with the EA and SCA patterns. Overall, our model-data comparison presents some potential uncertainties in climate projections over the North Atlantic sector, which remain challenging for the reliability of future projections. Also, this model-data comparison framework presents a pathway for future studies aiming to select the better-performing models for regional climate studies.

How to cite: Tao, Q., Sjolte, J., and Muscheler, R.: A model-data comparison of North Atlantic climate variability and its responses to natural forcing over the last millennium , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4074, https://doi.org/10.5194/egusphere-egu24-4074, 2024.

EGU24-4158 | ECS | Orals | NP3.3

Changes in deep-water formation amplify the Earth's Equilibrium Climate Sensitivity on multi-centennial time scales 

Fernanda DI Alzira Oliveira Matos, Christian Stepanek, Gerrit Lohmann, Qiong Zhang, Katherine Elizabeth Power, Jan Streffing, and Tido Semmler

Quantifying the Earth's climate system response to changes in atmospheric carbon dioxide (CO2) concentrations is crucial for understanding the impact of greenhouse gases on the Earth's past, present, and future climate. The sensitivity of the Earth's climate to increasing CO2 levels will largely determine the environmental conditions faced by human societies, fauna, and flora in the years to come. Projected future climate conditions depend on the sensitivity of the numerical models employed. Therefore, a comprehensive understanding of model sensitivity to radiative forcing across various temporal and spatial scales is essential. Towards this goal, we employ the newly developed AWI-CM3 model, which will be used for future climate projections in CMIP7, to examine Equilibrium Climate Sensitivity (ECS) across different time scales. 

Our quasi-equilibrium simulations span 2,000 model years, subjected to atmospheric CO2 concentrations of 280, 400, 560, and 1120 ppmv. The highest concentration simulation is inspired by the CMIP6 abrupt4xCO2 protocol, designed to assess climate response to an abrupt change in radiative forcing. Notably, our simulations run much longer than the CMIP6 suggested 150-year duration. The lower concentration simulation represents the pre-industrial period (PI), while the remaining were designed to investigate the climate with CO2 concentrations similar to the current climate and with a doubling of PI levels, respectively.

The ECS derived from AWI-CM3 stands at 3.95ºC, ranking it as medium-range sensitivity compared to the CMIP6 ensemble. A key finding is that ECS increases by up to 1.5ºC when simulations are extended beyond the CMIP6 minimum runtime requirement. This change in ECS correlates to alternations in deep water formation in both the North Atlantic and Southern Oceans. Throughout the simulations, we note adjustment processes in the overall climate and multi-centennial variability in the strength of the Atlantic Meridional Overturning Circulation (AMOC) due to changes in North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) formation. 

The simulations also reveal a progressive weakening and shallowing of the AMOC and a strengthening of the AABW as CO2 concentrations increase. Beyond 200 years, under adjusted radiative forcing, the AMOC recovers, but the resultant circulation pattern features persistently shallower NADW and a weaker, more northward-extending AABW in the Atlantic and Pacific Oceans. Our results highlight the intricate relationship between deep water formation and Earth's equilibrium climate sensitivity. Furthermore, our findings suggest a need to reevaluate the current framework for deriving ECS in the standard CMIP6 methodology. Prolonged simulations not only enhance our understanding of the underlying mechanisms driving climate sensitivity to changing radiative forcing but also provide valuable insights into the time required for the Earth's climate to adjust to these changes.

How to cite: Oliveira Matos, F. D. A., Stepanek, C., Lohmann, G., Zhang, Q., Power, K. E., Streffing, J., and Semmler, T.: Changes in deep-water formation amplify the Earth's Equilibrium Climate Sensitivity on multi-centennial time scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4158, https://doi.org/10.5194/egusphere-egu24-4158, 2024.

Multi-centennial climate variability, evident in paleoclimate proxy records and observed in both forced transient and unforced control simulations with numerous fully coupled climate models, presents a significant yet elusive phenomenon in climate dynamics. This study, utilizing a coupled climate model EC-Earth3-LR, identifies and analyzes a prominent multi-centennial climate variability with a distinct 200-year cycle in a pre-industrial (PI, with atmospheric CO2 concentration of 280 ppmv) control simulation. This oscillation originates predominately from the North Atlantic and displays a strong association with the Atlantic Meridional Overturning Circulation (AMOC). 

We pinpoint the crucial interplay between salinity advection feedback and vertical mixing in the subpolar North Atlantic as key roles in providing the continuous internal energy source to maintain this multi-centennial oscillation. The perturbation flow of mean subtropical-subpolar salinity gradients serves as positive feedback that sustain the AMOC anomaly, while the mean advection of salinity anomalies and the vertical mixing acts as negative feedback, constraining the amplitude of AMOC anomaly.
 
In warmer climate conditions, with atmospheric CO2 concentrations elevated to 400 ppmv and 560 ppmv, we observe an expected stabilization of the water column in the North Atlantic deep-water formation regions, potentially leading to a reduction in the AMOC. These conditions are simulated to assess the evolution of unforced internal multi-centennial variability under higher CO2 levels. Results show that while multi-centennial climate variability persists in these warmer climate states, oscillation amplitudes are diminished. Despite the reduced intensity, the most pronounced effects remains in the North Atlantic and the Arctic, hypothesized to be driven by AMOC fluctuations. In contrast to the PI simulation, where the Arctic and subtropical fluxes exhibit aligned power spectra peaks, the warmer climate scenarios reveal longer timescales and reduced amplitudes in multi-centennial climate variability, suggesting a climate state dependence in the subtropical mechanism. Notably, while the subtropical salinity feedback is coupled with the Arctic mechanism in the PI state, it evolves into a weaker, slower, and self-sustaining mechanism in warmer climates.

How to cite: Cao, N., Zhang, Q., and Power, K.: Multi-centennial variability of the Atlantic Meridional Overturning Circulation: underlying mechanisms and its response to elevated CO2 levels , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4605, https://doi.org/10.5194/egusphere-egu24-4605, 2024.

Momentum-scalar coupling turbulence, such as buoyancy-driven turbulence and electrohydrodynamic (EHD) turbulence, involves the transportation of multicomponent scalars under the strong interplay of multiphysics. For instance, in the atmosphere, the temperature gradient can induce buoyancy, driving the flow to form thermal convection. At the same time, electric body force can be generated on droplets, dust, and moisture gradients through spatial electric fields, resulting in air flow into EHD turbulence. Additionally, charged species move and create electric current, leading to Lorentz force due to the magnetic field of the earth, which may induce magnetohydrodynamic (MHD) turbulence. These physical mechanisms generate the diverse phenomena on our beautiful planet. This study theoretically explores how multiphysical mechanisms interplay, governing the cascades of turbulent kinetic energy and multicomponent scalars. Some new scaling properties, which differ from those predicted in buoyancy-driven turbulence, EHD, and MHD, emerge when two mechanisms and scalar components exist simultaneously. The quad-cascade processes of such turbulent systems are again validated. Unfortunately, when three or more mechanisms are taken into account at the same time, the problem becomes unattainable to close. This research endeavors to shed light on the diverse observation in momentum-scalar coupling turbulence across various scenarios.

How to cite: Zhao, W.: Emergence of scaling properties in momentum-scalar coupling turbulence: Exploring interplay of multiphysics mechanisms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4818, https://doi.org/10.5194/egusphere-egu24-4818, 2024.

EGU24-5384 | Orals | NP3.3

Continuous-time state-space time series models for delta-O-18 and delta-C-13 

Eric Hillebrand, Mikkel Bennedsen, Kathrine Larsen, and Siem Jan Koopman

Time series analysis of delta-O-18 and delta-C-13 measurements from benthic foraminifera for purposes of paleoclimatology is challenging. The time series reach back tens of millions of years, they are relatively sparse in the early record and relatively dense in the later, the time stamps of the observations are not evenly spaced, and there are instances of multiple different observations at the same time stamp (Westerhold et al., 2020, Science 369 p. 1383). The time series appear non-stationary over most of the historical record with clearly visible temporary trends of varying directions. In this paper, we propose a continuous-time state-space framework to analyze the time series prepared in Westerhold et al. (2020). State space models are uniquely suited for this purpose, since they can accommodate all the challenging features mentioned above. We specify univariate models and joint bivariate models for the two time series of delta-O-18 and delta-C-13. The models are estimated using maximum likelihood by way of the Kalman filter recursions. The suite of models we consider has an interpretation as an application of the Butterworth filter (Gomez 2001 [JBES 19 p. 365], Harvey & Trimbur 2003 [REStat 85 p. 244]). We propose model specifications that take the origin of the data from different studies into account and that allow for a partition of the total period into sub-periods following Westerhold et al. 2020, which we have been able to confirm with a statistical method (Larsen et al. 2024: Estimating Breakpoints between Climate States in Paleoclimate Data, abstract submitted to EGU General Assembly Session CL3.2.3). The models can be used, for example, to generate evenly time-stamped data by way of Kalman filtering. They can also be used, in future work, to analyze the relation to proxies for CO2 concentrations.

How to cite: Hillebrand, E., Bennedsen, M., Larsen, K., and Koopman, S. J.: Continuous-time state-space time series models for delta-O-18 and delta-C-13, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5384, https://doi.org/10.5194/egusphere-egu24-5384, 2024.

EGU24-6672 | ECS | Posters on site | NP3.3

Unified scaling framework for Holocene, Quaternary and Phanerozoic geochronology variability 

Rhisiart Davies, Shaun Lovejoy, Raphael Hebert, Fabrice Lambert, and Andrej Spiridonov

With few exceptions, paleodata are irregularly sampled; this poses numerous challenges for the statistical characterization of paleoindicators, this includes the indicators needed to understand the climate and macroevolution.  The key variable is the measurement density - the number of measurements per unit time (r(t)).  Our study used 27 paleoindicators collectively spanning time scales from years to hundreds of millions of years.

Using Haar fluctuation analysis and for all the series, we show that r(t) has two scaling regimes.  At high frequencies, there is a low intermittency (quasi-Gaussian) scaling regime (intermittency parameter C1 ≈ 0).  Over this regime, the fluctuation exponent H is negative implying that the chronologies become more uniform at longer time scales, r(t) is commonly close to a Gaussian white noise (H = -1/2).  In contrast, at low frequencies, r(t) is highly intermittent (large C1), but it also has positive H so that fluctuations tend to grow with scale but in a highly intermittent fashion.  In this this regime, “gaps” at all scales are important. 

The two regimes have simple physical interpretations: the high frequency behaviour can be explained by fairly smooth (but scaling) sedimentation rates, whereas the low frequencies can be explained by scaling erosion processes that introduce gaps over a wide range of scales (in conformity with the Sadler effect). To confirm this interpretation, we introduce a simple multiplicative sedimentation -  erosion model that is close to the data.  Finally, we empirically show that the gaps typically have extreme power law probability tails so that the series are not only scaling in time, but also in probability space.

A key issue for paleontologists is the effect of variable r(t) on the paleoindicator estimates themselves (e.g. on paleotemperatures T(t)).  Using Haar fluctuations we determined the fluctuation - fluctuation correlation R(Δt) = < Δ r(Δt) ΔTt) >.  When R(Δt) is small, the measurements and indicators are statistically independent so that the biases due to r(t) variability on paleoindicator statistics are easy to correct.  However, at large Δt, the correlations are frequently large, and this poses additional difficulties in data interpretation.  Strong correlations were observed in the Quaternary, but not the Holocene or Phanerozoic.

Our study spans more than 8 orders of magnitude in time scale and it shows that it is wrong to theorize paleoseries as being fundamentally regularly sampled but interspersed with occasional data “holes” that can be dealt with using conventional techniques such as interpolation.  While Haar fluctuation analysis is insensitive to the chronology variability - and if needed can easily be statistically corrected for any biases that it introduces -  this is not true of existing spectral estimators that are extremely sensitive to scaling data gaps. 

How to cite: Davies, R., Lovejoy, S., Hebert, R., Lambert, F., and Spiridonov, A.: Unified scaling framework for Holocene, Quaternary and Phanerozoic geochronology variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6672, https://doi.org/10.5194/egusphere-egu24-6672, 2024.

EGU24-6829 | ECS | Orals | NP3.3

Tropical-polar teleconnections: Impacts of North Atlantic meltwater forcing on the Indian Ocean 

Benjamin H. Tiger, David McGee, and Caroline Ummenhofer

Across all future IPCC Shared Socioeconomic Pathways, the strength of the Atlantic Meridional Overturning Circulation (AMOC) is projected to decline. However, there is much less certainty about the impacts of AMOC decline further afield. Evidence from paleoclimate archives and simulations suggests eastern African monsoons weakened under periods of high meltwater forcing in the North Atlantic, particularly during the most recent deglaciation. To explore the dynamics of this high- to low-latitude teleconnection, we use a compilation of ~30 sea surface temperature (SST) records from the tropical Indian Ocean spanning the last 30 ka. The zonal Indian Ocean SST gradient calculated from this compilation shows a remarkable similarity with North Atlantic 231Pa/230Th records of AMOC strength, particularly during intervals of variable meltwater forcing such as the Younger Dryas, Bølling-Allerød, and Heinrich stadials. A weaker AMOC is associated with cooler western Indian Ocean and a warmer eastern Indian Ocean, suggesting a tight linkage between AMOC strength and zonal Indian Ocean variability. To better understand this teleconnection, we analyzed a meltwater single-forcing scenario from a transient simulation of the Last Glacial Maximum to present (TraCE, 22ka-0ka). Under simulated meltwater forcing events, the tropical zonal Indian Ocean SST gradient intensifies (i.e., relative cooling in the west and warming in the east), in agreement with SST paleorecords. This response stems from an intensification of the subtropical high over Southern Europe which drives northerly surface wind anomalies across Arabia and the Horn of Africa, with cooler Northern Hemisphere anomalies extending as far south as Madagascar. This cools the surface western Indian Ocean, particularly in the Arabian Sea, enhancing the Bjerknes feedback and strengthening the Walker circulation across the basin. This effect is strongest in austral summer (DJF) when the Somali Jet reverses and northerly winds advect cool northern air into the deep tropics. Anomalous northerly winds and western Indian Ocean cooling were also found to be common feature of eight hosing experiments under preindustrial boundary conditions from the North Atlantic Hosing Model Intercomparison Project (NAHosMIP). Overall, we hypothesize an atmospheric mechanism connecting the high-latitude North Atlantic and tropical Indian Ocean under meltwater forcing, with the western Indian Ocean playing an outsized role in steepening the zonal SST gradient across the basin which weakens monsoon systems in eastern Africa.

How to cite: Tiger, B. H., McGee, D., and Ummenhofer, C.: Tropical-polar teleconnections: Impacts of North Atlantic meltwater forcing on the Indian Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6829, https://doi.org/10.5194/egusphere-egu24-6829, 2024.

Hydroclimatic systems are complex nonlinear dynamically-evolving systems, often made up of a large number of interconnected components that change both in space and in time. Therefore, any effort towards reliable modeling and forecasting of hydroclimatic systems requires proper selection of scientific concepts and methods. Many different scientific concepts and methods have been proposed in the literature and applied to numerous hydroclimatic systems, processes, and problems around the world. Among such, concepts and methods based on chaos theory, complex networks, and fractal theory have been found to offer unique and useful avenues for studying hydroclimatic systems and, thus, have been finding widespread applications in recent times. The purpose of the present study is to discuss the advances in the applications of these concepts to hydroclimatic systems and to look toward the future. This is done through: (1) presenting some key aspects of chaos theory, complex networks, and fractal theory and their relevance to hydroclimatic systems; (2) reviewing various applications of these concepts to hydroclimatic systems, processes, and problems; (3) addressing important data-related issues in the applications of these concepts to hydroclimatic systems; and (4) offering specific directions to advance these concepts and applications further, especially in the context of future grand challenges associated with hydroclimatic systems.

How to cite: Sivakumar, B.: Complexity, Connectivity, and Scale in Hydroclimatic Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7105, https://doi.org/10.5194/egusphere-egu24-7105, 2024.

EGU24-7152 | ECS | Posters on site | NP3.3

Thermohaline Circulation Determines the Multi-centennial Variability of Earth's Climate System 

Fengli An, Mingjun Tong, and Haijun Yang

Long-term proxy data have shown that there is significant multi-centennial variability in Earth's climate system. However, the causes and mechanisms of this variability are still a major scientific problem for climate scientists and archaeologists. From the middle of the Holocene until the Industrial Revolution, there was little change in the Earth's external forcing, so it is important to study the long-term natural oscillations of our climate system during this period. In our research, we designed a series of experiments using CESM1.0 to explore the sources of multi-centennial variability of climate system. In some experiments, the thermohaline circulation was turned off to see if its presence would affect the oscillation of climate system. We finally conclude that thermohaline circulation is likely to determine the multi-centennial variability of Earth's climate system.

How to cite: An, F., Tong, M., and Yang, H.: Thermohaline Circulation Determines the Multi-centennial Variability of Earth's Climate System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7152, https://doi.org/10.5194/egusphere-egu24-7152, 2024.

EGU24-7409 | ECS | Posters virtual | NP3.3

Fractal approach in the Analysis of climate change due to the ozone layer hole 

Meenakshi Murugan

The ozone layer acts as the planet's natural sunscreen, protecting people, plants, and animals from harmful UV-B rays. In Antarctica, British scientists discovered the hole in the ozone layer in 1985. The effects of climate change have been experienced by all living hoods through various kinds of natural calamities due to this hole. Many researchers dedicated their time to solving this problem and saving the planet. This article explores Antarctica's post-1985 climate changes.  The authors have to Investigate the time series data for the global temperature, precipitation, and Antarctica ice sheet mass balance through analysis utilizing the fractal analysis tool.  Additionally, the nonlinear dynamical data's chaotic feature is verified.

How to cite: Murugan, M.: Fractal approach in the Analysis of climate change due to the ozone layer hole, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7409, https://doi.org/10.5194/egusphere-egu24-7409, 2024.

EGU24-8571 | ECS | Posters on site | NP3.3

Unravelling succolarity to quantify multiscale petrophysical properties beyond porosity 

Bo Li, Ciprian Panaitescu, Paul Glover, Kejian Wu, Piroska Lorinczi, and Bingsong Yu

Characterising the complexity of spatial patterns and their underlying physics using a nonlinear approach is growing in many fields. Many features in geomaterials, such as pore and fracture systems, exhibit scaling behaviour, allowing their properties to be characterised using fractal theory.

The widely used fractal dimension is a ratio that compares how the level of detail in a structure varies with its size, measuring its space-filling ability. Lacunarity, derived from the Latin word "lacuna," meaning "gap," quantifies the “voidness” of a texture. Nevertheless, neither fractal dimension nor lacunarity can characterise the percolating properties of a fractal. Mandelbrot coined the concept of succolarity. Given that "percolare" in Latin translates to "to flow through," the term "succolare" (sub-colare) aptly conveys the concept of "to nearly flow through" in neo-Latin. A succolating fractal is characterised by almost containing the connecting paths that permit percolation, i.e., one below the percolation threshold. However, it remains a less known notion than the other two fractal counterparts. In the last ten years, succolarity has evolved from an idea to a computable parameter. It has characterised many patterns in different scales and fields, such as medical objects, material surfaces, and networks from nano-micropores to rivers.

In this contribution, we aim (i) to understand the physical meaning of succolarity and how it relates to pore networks and other petrophysical properties across different scales, and (ii) to provide new approaches to succolarity calculation. We implemented the succolarity algorithm using the gliding box-counting method. We then re-examined the published datasets for validation and comparison. The succolarity for 2/3D images of rock samples and synthetic models with various porous structures was also calculated for deeper understanding. Finally, we correlated the succolarity results with porosity, permeability, and other petrophysical parameters.

Our findings reveal that (i) succolarity contains information about a structure's anisotropy, phase fraction (e.g., porosity in the case of pore space), and percolation information. (ii) It is susceptible to connectedness. As we cut out smaller pores of a structure, succolarity decreases linearly until a pore size (porosity) threshold is reached; it drops significantly and follows a power law. (iii) Succolarity (Su) and permeability are fitted to an exponential relation: k = aebSu. The computation of succolarity excludes isolated pores for a given flooding direction, allowing it to reflect the flow properties better than porosity alone. (iv) Moreover, it is worth noting that using pressure or velocity field in the succolarity calculation algorithm would endow it with a clearer physical meaning than being a proxy for porosity.

How to cite: Li, B., Panaitescu, C., Glover, P., Wu, K., Lorinczi, P., and Yu, B.: Unravelling succolarity to quantify multiscale petrophysical properties beyond porosity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8571, https://doi.org/10.5194/egusphere-egu24-8571, 2024.

EGU24-8588 | ECS | Orals | NP3.3

 Power-spectra of turbulent buoyant jets from laboratory measurements 

Konstantinos Gkoutis, Ilias Papakonstantis, Panagiotis Papanicolaou, and Panayiotis Dimitriadis

In total, 11 experiments of turbulent buoyant jets were carried out in an experimental apparatus, which includes a tank with dimensions 1.00 m x 0.80 m x 0.70 m. Specifically, in a stationary homogeneous ambient fluid, six (6) experiments were performed, with a temperature at the outlet significantly higher than the ambient water, and five (5) experiments with the same temperature but in an ambient saltwater environment of initial density difference between 18.4 and 19.2 kg/m3. The nozzle diameter was equal to 1.5 cm in all experiments, the densimetric Froude number was ranging between 1.72 and 3.73, and the Reynolds number ranging between 1222 and 3136. The experiments included flow visualization and concentration measurements based on the Laser Induced Fluorescence (LIF) technique using Rhodamine 6G as fluorescent tracer. A planar laser sheet was created and the experiments were recorded using a suitable video camera. The energy-spectra of the concentration were estimated using Fast Fourier Transformation and were compared to theoretical arguments, such as the K41 model.

How to cite: Gkoutis, K., Papakonstantis, I., Papanicolaou, P., and Dimitriadis, P.:  Power-spectra of turbulent buoyant jets from laboratory measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8588, https://doi.org/10.5194/egusphere-egu24-8588, 2024.

EGU24-9251 | ECS | Orals | NP3.3

Complex network-based analysis of the spatial evolution of the flash droughts over India 

Akshay Pachore and Renji Remesan

Flash droughts, characterized by a rapid decline in soil moisture, are short-term drying events that can cause significant damage to crops when they occur during the growing season. Understanding the spatial and temporal evolution properties of flash droughts is crucial for the effective mitigation and management of this extreme event. The present study employed the complex network theory to assess the spatio-temporal properties of the flash drought which was quantified using the soil moisture percentile drop (SMPD) based definition during the period from 1981 to 2020 over the entire Indian region. An event synchronization (ES)-based complex network is constructed and the spatial propagation of the flash droughts is analyzed using the unidirectional and directed complex networks-based metrics i.e., strength, direction, and distance. Initial results gave insights into how the flash drought hotspots are connected in space and their temporal evolution pattern. From the result of the distance metrics, it was observed that flash drought propagates for longer distances in the central-eastern and southern peninsular regions as compared to the rest of the regions over India. Inference gained from the present analysis can be useful for building an early warning system for flash drought in terms of onset and spatial propagation along with insights on the spatially connected flash drought vulnerable regions.           

How to cite: Pachore, A. and Remesan, R.: Complex network-based analysis of the spatial evolution of the flash droughts over India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9251, https://doi.org/10.5194/egusphere-egu24-9251, 2024.

EGU24-10640 | Orals | NP3.3

A synchronized solar dynamo model and its consistency with climate data 

Frank Stefani, Gerrit Horstmann, Martins Klevs, George Mamatsashvili, and Tom Weier

We examine a remarkable consistency of the power spectrum of paleoclimatic varved sediment data from Lake Lisan [1] with that of a novel solar dynamo model that is doubly synchronized by tidal effects and the revolution of the Sun around the barycenter of the solar system [2,3]. We support and specify the latter model by quantifying the tidal excitation of magneto-Rossby waves [4] at the solar tachocline and by estimating the effects of spin-orbit coupling. Typical time series resulting from this dynamo model are then utilized in a double regression of solar and anthropogenic influences on the global temperature of the past 170 years in order to quantify various climate sensitivities [5].
 

[1] S. Prasad et al., Geology 32 (2004), 581
[2] F. Stefani et al., Solar Phys. 296 (2021), 88
[3] F. Stefani et al., arXiv:2309.00666
[4] G. Horstmann et al., Astrophys. J. 944 (2023), 48 
[5] F. Stefani, Climate 9 (2021), 163

How to cite: Stefani, F., Horstmann, G., Klevs, M., Mamatsashvili, G., and Weier, T.: A synchronized solar dynamo model and its consistency with climate data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10640, https://doi.org/10.5194/egusphere-egu24-10640, 2024.

EGU24-10986 | Orals | NP3.3

Tropical mountain ice core  : A Goldilocks indicator for global temperature change 

Zhengyu Liu, Yuntao Bao, Lonnie Thompson, Ellen Mosley-Thompson, Clay Tabor, Guang Zhang, Mi Yan, Marcus Lofverstrom, Isabel Montanez, and Jessica Oster

 Tropical mountain ice core : A Goldilocks indicator for global temperature change   Zhengyu Liu1,2,3, , Yuntao Bao1, Lonnie G. Thompson3,4, Ellen Mosley-Thompson1,3,  Tabor Clay5, Guang J. Zhang6, Mi Yan2, Marcus Lofverstrom7, Isabel Montanez8,  Jessica Oster9  1.      Department of Geography, The Ohio State University, Columbus, OH 2.      School of Geography Science, Nanjing Normal University, Nanjing, China. 3.      Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH 4.      School of Earth Sciences, The Ohio State University, Columbus, OH 5.      Department of Earth Sciences, University of Connecticut, Storrs, CT 6.      Scripps Institute of Oceanography, University of California San Diego, San Diego, CA

  • Department of Geosciences, University of Arizona, Tucson, AZ
  • Department of Earth and Planetary Sciences, University of California–Davis, Davis, CA
  • Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN

 

Very high tropical alpine ice coresprovide a distinct paleoclimate record for climate changes in the middle and upper troposphere. However, the climatic interpretation of a key proxy, the stable water oxygen isotopic ratio in ice cores (), remains an outstanding problem. Here, combining proxy records with climate models, modern satellite measurements and radiative-convective equilibrium theory, we show that the tropical  is an indicator of the temperature of the middle and upper troposphere, with a glacial cooling of -7.35+-1.1oC (66% CI). Moreover, it severs as a “Goldilocks-type” indicator of global mean surface temperature change, providing the first estimate of glacial stage cooling that is independent of marine proxies as -5.9+-1.2oC. Combined with all estimations available gives the maximum likelihood estimate of glacial cooling as -5.85+10.51oC .

 

 

How to cite: Liu, Z., Bao, Y., Thompson, L., Mosley-Thompson, E., Tabor, C., Zhang, G., Yan, M., Lofverstrom, M., Montanez, I., and Oster, J.: Tropical mountain ice core  : A Goldilocks indicator for global temperature change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10986, https://doi.org/10.5194/egusphere-egu24-10986, 2024.

EGU24-11058 | ECS | Orals | NP3.3

Analysing the multifractality and cross correlations of river stage records using detrended fluctuation principles 

Sumayah Santhoshkhan, Athira Madhu, Muraleekrishnan Bahuleyan, and Susan Mariam Rajesh

This study presents the application of Multifractal detrended fluctuation analysis (MFDFA) for analyzing the multifractal properties of river stage time series of Indian rivers. Initially, the MFDFA method was applied to detect long-range correlations and multifractal behaviour of river stage time series of 81 locations from 11 basins of Peninsular India. The study found that all the Hurst exponent (H) values are found to be more than 0.5 indicating the long-range power law correlations in the stage data of Indian rivers. The different datasets indicated strong multifractal degree and a strong association between H and Holder exponent supported by a strong correlation over 0.98. Most of the multifractal spectra (93 %) indicated a positive asymmetry showing the frequent low fluctuations and localized high fluctuations. Basin wise analysis showed the strongest long-term persistence (LTP) and highest degree of multifractality for the datasets of Cauvery basin. In order to get an insight on the multifractality, MFDFA was applied to the daily data of corresponding period as that of stage observations. The analysis indicated that unlike the case of stage data 68 % of the data showed LTP while rest of the data displayed STP in the analysis. The multifractality of stage series is more than that of stream flow series at all river basins in India. Multifractal cross correlation analysis performed between daily river stage data and discharge data of same period indicated a strong correlation (>0.8) in majority of cases for different scales, despite the absence of a definite pattern in the correlation behavior for the data of different stations. This analysis is proven to be a very essential and useful prerequisite for developing stage-discharge relationships in a multifractal perspective, which may eventually help in proper flood management of Indian basins' changing climate scenario.

Keywords: Persistence, multifractality, Stage, Streamflow, Correlation, Scale

How to cite: Santhoshkhan, S., Madhu, A., Bahuleyan, M., and Rajesh, S. M.: Analysing the multifractality and cross correlations of river stage records using detrended fluctuation principles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11058, https://doi.org/10.5194/egusphere-egu24-11058, 2024.

EGU24-11382 | Orals | NP3.3

Multifractal correlation of rainfall and wind fields and consequences on wind power production 

Auguste Gires, Jerry Jose, Angel Garcia-Gago, Ioulia Tchiguirinskaia, and Daniel Schertzer

Rainfall and wind exhibit extreme variability over wide range of space-time scales. Such features are naturally transferred to wind turbine torque and ultimately to wind energy production. Improving our understanding of wind power production requires better accounting for the impact of these small scale fluctuations. This is much needed in order to achieve UN’s (United Nations) Sustainable Development Goal 7 (affordable and clean energy for all) and in a context of increasing global transition towards renewable and carbon neutral energy.

The project RW-Turb (https://hmco.enpc.fr/portfolio-archive/rw-turb/; supported by the French National Research Agency, ANR-19-CE05-0022) was developed to address this challenge and to understand better the correlation across scales between rainfall and wind fields and its impact on wind power production. A high resolution measurement campaign was set up between 12/2020 and 07/2023 with two 3D sonic anemometers (manufactured by Thies), two mini meteorological stations (manufactured by Thies), and two disdrometers (Parsivel2, manufactured by OTT) installed on a meteorological mast at 75 and 45 m respectively in the wind farm of Pays d’Othe (110 km south-east of Paris, France; operated by Boralex). The framework of Universal Multifractals (UM) is used to carry out this analysis. It is a physically based and mathematically robust framework that enables to characterize and simulate the extreme variability of geophysical fields across scales. It is furthermore parsimonious since it relies on the use of only three parameters.

In a first step multifractal analysis of the available fields (wind velocity, power available at the wind farm, power produced by wind turbines, air density, and rainfall) is implemented. Event based analysis enabled to observe differences in UM parameters depending on whether it is raining or not. In general, a slightly stronger variability is found when it rains. In a second step, a joint multifractal analysis is implemented to further quantify correlation across scales between the studied fields. An increase in correlation exponent of the various fields with increase in rain rate is found.

Numerical simulations are then used as a complement to data analysis. More precisely, 3D space plus time vector fields which realistically reproduce observed spatial and temporal variability of wind fields are generated with multifractal tools. Then, they are used as input into three modeling chains of increasing complexity to simulate wind turbine torque. The simplest model uses average wind field over swept area, while a more realistic one computes the torque as an integral over the blades of the turbine enabling to account for the space-time variability of wind. Finally, OpenFAST, which is widely used by researchers and practitioners is implemented. UM analysis on the simulated torque time series were performed to quantify the impact of small scale fluctuations on wind power production, as well as the ability of the various models to account for it.

How to cite: Gires, A., Jose, J., Garcia-Gago, A., Tchiguirinskaia, I., and Schertzer, D.: Multifractal correlation of rainfall and wind fields and consequences on wind power production, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11382, https://doi.org/10.5194/egusphere-egu24-11382, 2024.

EGU24-11718 | Orals | NP3.3 | Highlight

An ocean-atmosphere paradox, Phase 2 

Brian Durham and Christian Pfrang

Last year we posed the question:  Given Earth’s ocean-atmosphere gas equilibrium, why do measured atmospheric carbon dioxide (CO2) curves rise more steeply against solvent temperature than predicted by Henry’s Law? (https://presentations.copernicus.org/EGU23/EGU23-6069_presentation.pdf). We here develop our experimental procedure to simulate more closely the ocean-atmosphere gas exchange in the lab, seeking to better understand the relationship between atmospheric COand average sea surface temperatures, with implcations for past and future climate variability in the Earth System. 

To this end, we previously reported provisional trends when water and natural seawater samples are equilibrated with an atmospheric ratio of CO2 in air. We also outlined a narrower interest in the published offset in annual CO2 cycles between marine and terrestrial stations which record atmospheric CO2 levels (Ye Yaun et al 2019).

Provisional results were compared with published values from seawater that had been `killed’ and acidified (Li and Tsui 1971 and Weiss (1974). Working at atmospheric partial pressures of CO2 however, a definitive value for the respective Henry constant was complicated by the difficulty of predicting an equilibrium asymptote in either water or seawater determinations.

We therefore listed a number of modifications to be adopted in future campaigns to address this issue. One proposed modification was to investigate alternative catalysts. Sodium dodecyl sulphate (SDS) is therefore replaced with a natural enzyme complex, generically carbonic anhydrase (CA), described as efficient in the reversible hydration of CO2 to bicarbonate.  CA is seen as an enzyme family with several independent evolutions across the phylogenetic tree, abundant in plants, diatoms, eubacteria and archaea (Supuran, 2016). The metallo-proteins are described as including a reaction space that combines one half hydrophilic and the opposing half hydrophobic, `allowing these enzymes to act as some of the most effective catalysts known in nature’.

In Phase 2 we therefore compare water samples with and without dosing with an infusion of terrestrial soil biota, while for seawater, being a living medium, we use a freshly-unfrozen sample of UK Atlantic coast water for each determination.

How to cite: Durham, B. and Pfrang, C.: An ocean-atmosphere paradox, Phase 2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11718, https://doi.org/10.5194/egusphere-egu24-11718, 2024.

Solar energy is an intricate phenomenon, especially within tropical insular locations, where this energy source demonstrates significant fluctuations across various short-term timeframes and spatial dimensions. Research on the stochastic characteristics of solar energy is gaining momentum in the scientific literature, revealing signs of scaling properties despite its inherent complexity. This paper sequentially delves into the examination of temporal fluctuations scaling and multifractal properties of irradiance for tropical insular sites (Guadeloupe, Réunion, Hawaï). By analogy with Taylor law performed on several complex process, an analysis of temporal fluctuations irradiance scaling properties is proposed. The results showed that the process of intradaily variability obeys Taylor’s power law for every short time scales and several insolation conditions. This approach elucidates the relationship between the variance of fluctuations and the mean with exponent between 1 and 2. This could confirm the relevance of Tweedie Convergence Theorem in a manner related to the central limit theorem; a mathematical basis for Taylor’s power law, 1/f noise and multifractality according to Kendal and Jørgensen [1].
Through various multifractal analysis techniques, including MFDFA, wavelet leader, structure functions, and arbitrary order Hilbert spectral analysis, on global solar radiation sequences, the intermittent and multifractal properties inherent in global solar radiation data have been brought to light across  scales ranging from one second to few hours and all intensities.
The understanding the dynamics of irradiance fluctuations is essential in various fields, including atmospheric science, remote sensing, and renewable energy. The results of these properties can help improve the modeling and prediction, which is crucial to optimally integrate PV onto electrical grids.

 

Reference

W. S. Kendal and B. Jorgensen, Tweedie convergence: A mathematical basis for Taylor's power law, 1/f noise, and multifractality. Phys. Rev. E 84, 066120, 2011. DOI. https://doi.org/10.1103/PhysRevE.84.066120.

 

How to cite: Calif, R. and Andre, M.: Temporal fluctuations scaling, multifractality and Tweedie distributions of solar energy in insular context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13680, https://doi.org/10.5194/egusphere-egu24-13680, 2024.

EGU24-13694 | ECS | Posters on site | NP3.3

Multifractal analysis of Cn2  scintillometer data 

Sitian Zhu, Auguste Gires, Cedo Maksimovic, Ioulia Tchiguirinskaia, and Daniel Schertzer

The cooling efficacy of green roofs in mitigating the urban heat island (UHI) effect within dense cities is largely attributed to evapotranspiration (ET) processes. Hence, accurate understanding and quantification of ET are pivotal for optimizing this cooling effect. ET estimation can be achieved either directly (weighing lysimeters) or indirectly (e.g., Penman-Monteith equation). Micro-meteorological approaches have been developed in recent years. Among which scintillometer can evaluate ET by its measurement parameter   which corresponds to the fluctuations of air refractive index  ) in combination with surface energy balance and Monin-Obukhov similarity theory. Hence, improvement in  data as well as understanding of its variability across wide range of space-time scale would result in better ET estimation and ultimately optimization. Yet it is often overlooked, and little research has focused on it and notably its variability.

This study explores the ET estimation on a wavy and vegetated green roof covering an area of 1 ha, known as the Blue Green Wave, which is located in Ecole des Ponts Paristech campus. Data from a large aperture scintillometer with 10-minute timestep during December 2019 and January 2020 is adopted.   data variability across scales was analysed with the help of structure function and Universal Multifractal model (UM). The UM framework, widely employed for characterizing and simulating geophysical fields extremely variable across wide range of space-time scales, relies on two parameters with physical interpretation: the mean intermittency codimension  and multifractality index  (, indicates monofractal; , indicates log-normal model.) An additional one, which is needed for non-conservative fields such as ET is the non-conservativeness parameter H.

Both structure function and UM approaches reveal good scaling behaviour on scales ranging from 10 min to 2h, confirming the relevance of the framework and demonstrating the potential for upscaling and downscaling. UM analysis conducted through Trace Moment and Double Trace Moment methods, provided similar values for UM parameters around   H is approximately 0.44 in our case, which deviates from traditional scaling laws due to the intricate composition of the fluxes and requires further investigations. Indeed  is influenced by temperature, humidity, air pressure and wind speed. To interpret properly structure function analysis from UM analysis, it is necessary to introduce a parameter denoted a. It corresponds to the power to which the assumed conservative underlying field should be raised before fractional integration to account for non-conservativeness to retrieve the studied field.  Here, we observed that a is around 0.76 to ensure the highest consistency of the outcome from both the structure function and UM analyses. A better understanding of the underlying complexity and variability of Cn2 is achieved by our analysis. This, in turn, improves our understanding of the underlying physical processes generating variability and temporal-spatial dynamics in ET, which paves the way for future applications.

 

How to cite: Zhu, S., Gires, A., Maksimovic, C., Tchiguirinskaia, I., and Schertzer, D.: Multifractal analysis of Cn2  scintillometer data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13694, https://doi.org/10.5194/egusphere-egu24-13694, 2024.

EGU24-14135 | ECS | Posters on site | NP3.3

Spatial coherence as a key metric for interpreting marine records of Holocene temperature variability 

Rebecca Cleveland Stout, Cristian Proistosescu, and Gerard Roe

Constraining forced and unforced climate variability impacts interpretations of past climate variations and predictions of future warming. However, comparing general circulation models (GCMs) and Holocene hydroclimate proxies reveals significant mismatches between simulated and reconstructed low-frequency variability on multi-decadal to multi-centennial timescales. Using a combination of GCMs and energy balance models, we have previously identified robust differences in the spatial pattern and magnitude of forced and unforced temperature variability on these long timescales. Our work suggests that not only is it important to understand variance, but also the spatial correlation between temperature at different sites. In principle, the spatial correlation at low frequencies is strongly related to the nature of variability. Now, we apply this dynamical understanding to the proxy record—specifically, across 49 globally-distributed Holocene sediment core sites with Mg/Ca and Uk37-based temperature reconstructions. We identify spatiotemporal statistics of forced and unforced variability using GCMs, and then use proxy-system models to assess how variability and spatial correlation are filtered by Mg/Ca and Uk37. Understanding these spatial correlations provides extra targets for interpreting these cores. Ultimately, we seek to characterize the forced and unforced components of slow modes of climate adjustment across the Holocene. 

How to cite: Cleveland Stout, R., Proistosescu, C., and Roe, G.: Spatial coherence as a key metric for interpreting marine records of Holocene temperature variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14135, https://doi.org/10.5194/egusphere-egu24-14135, 2024.

EGU24-16097 | ECS | Posters on site | NP3.3

Climatic and environmental impacts of an Oruanui-like supereruption in the Southern Hemisphere extratropics 

Christina Brodowsky, Simon Barker, Michael Sigl, and Kirstin Krüger

Explosive volcanic eruptions have disrupted the climate system dramatically in the past. Recent volcanological fieldwork suggests that at least four VEI 8 events took place in the past 100’000 years, depositing large amounts of volcanic volatiles onto polar ice sheets, each one with potentially significant impacts on human life on Earth. Previous studies on this research topic and time period tend to focus either on tropical eruptions or only consider changes in radiative forcing due to orbital parameters, solar variability, or changes in atmospheric CO2. Here, we seek to evaluate the climatic and environmental impacts of the ~25.5 ka Oruanui eruption (Taupō caldera, 38°S, 175°E, New Zealand). We thereby refine our understanding of the volcanic forcing based on volcanological and ice core data to provide a basis for long-term climate simulations. We use existing emission details for an idealized Oruanui-like eruption scenario. We run an ensemble of CESM2/WACCM simulations with 1850 pre-industrial conditions and instantaneously emit 260 Tg SO2, and the corresponding halogen load derived from petrological estimates into the stratosphere. We then analyze the climatic effects in the decades following the eruption compared with available paleo proxies. Our overarching goal is to provide comprehensive insights into the climatic and environmental repercussions of an Oruanui-like eruption, with a specific emphasis on the differences to tropical events of comparable magnitude. By comparing these two distinct types of eruptions, we aim to contribute to a refined understanding of volcanic impacts on Earth's climate and human life.

How to cite: Brodowsky, C., Barker, S., Sigl, M., and Krüger, K.: Climatic and environmental impacts of an Oruanui-like supereruption in the Southern Hemisphere extratropics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16097, https://doi.org/10.5194/egusphere-egu24-16097, 2024.

EGU24-16400 | Posters on site | NP3.3

Uncertainties in modelling diagenetic self-organisation in limestone-marl sequences 

Hanno Spreeuw, Johan Hidding, Niklas Hohmann, and Emilia Jarochowska

Rhythmic variations in the properties of sediments are commonly used as archives of paleoclimate changes driven by variation in insolation caused by the changes in the Earth's orbit and the tilt of its axis. But rhythmicity can also arise from diagenetic self-organization. Distinguishing between these two drivers requires simulating self-organization. We started with an attempt to reproduce the main results from a paper by Ivan L'Heureux (2018)¹ - who proposed a mathematical model of a nonlinear dynamical system, in which self-organized oscillations arise from homogenous initial sediment and result in sediment layers with different compositions. The model consists of five stiff differential equations, for the composition of calcite and aragonite, two mineral polymorphs of CaCO3, of which aragonite is metastable, for the concentrations of calcium and carbonate ions in the pore water and for the porosity, as functions of depth and time. The self-organized patterns are in this model the result of two processes happening at different temporal scales: rapid dissolution of aragonite and slow sediment compression in response to increased porosity as aragonite is removed from the solid phase. Reproducing the steady-state distributions along depth required a major effort, mostly with regard to understanding what triggers numerical instabilities, but was finally successful.  
Currently, we have not yet succeeded in reproducing oscillations, that L'Heureux predicted
, without requiring an external force, for high initial and boundary sediment porosity.  It is essential that we are able to determine for which inital and boundary conditions oscillations should occur, beyond the uncertainties introduced by numerical algorithms for solving partial differential equations, e.g. for many sets of parameters the integrations over time can easily "derail". We have formulated two questions that we want to share with the audience in order to seek help. These are our questions: 

1) Do the five differential equations describe the underlying physics adequately?  
2) Our current software implementation of the five differential equations does not yield any oscillations, is that a flaw on our side, or does this agree with mathematical insights?

  • "Diagenetic Self-Organization and Stochastic Resonance in a Model of Limestone-Marl Sequences" by Ivan L'Heureux (2018). https://doi.org/10.1155/2018/4968315

How to cite: Spreeuw, H., Hidding, J., Hohmann, N., and Jarochowska, E.: Uncertainties in modelling diagenetic self-organisation in limestone-marl sequences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16400, https://doi.org/10.5194/egusphere-egu24-16400, 2024.

EGU24-16778 | ECS | Orals | NP3.3

Probability distributions as indicators of dissipative dynamics in river chemistry 

Caterina Gozzi, Axel Kleidon, and Antonella Buccianti

The chemistry of rivers plays a crucial role in comprehending the evolution of weathering processes, especially in the context of climate change and human activities. As weathering proceeds within river catchments, chemical concentrations tend to move towards saturation, or thermodynamic equilibrium. However, thermodynamic equilibrium is extremely difficult to achieve in an open system where matter and energy are continuously exchanged.

The speed of weathering processes and the associated probability distributions of concentrations values differ among geochemical species. We demonstrate that these differences are characterized by the rate of entropy production associated with the mixing of groundwater enriched with weathering products with the less saturated river water.

Based on river chemistry and discharge data observations in the Arno River basin in central Italy, we distinguish two groups of chemical variables, reflecting different levels of dissipative behavior. We show that Calcium (Ca2+) and Bicarbonate (HCO3-) concentrations are close to saturation along most of the downstream length of the Arno River, with decreasing dissipation rates and a (log)normal distribution, while Sodium (Na+) and Chlorine (Cl) concentrations increase substantially downstream, showing increased dissipation rates and being power-law distributed. This supports our hypothesis that power law distributions appear to be indicative of dissipative systems far from thermodynamic equilibrium, while (log)normal distributions indicate weakly dissipative systems close to equilibrium. This suggests that the frequency distributions of environmental variables are intricately connected to their thermodynamic state, and the degree of disequilibrium constrains the range over which power-law scaling can be observed. These results should contribute to a more comprehensive understanding of the characteristics and underlying mechanisms that lead to these types of distributions, allowing to better classify variability in systems based on how dissipative they are.

How to cite: Gozzi, C., Kleidon, A., and Buccianti, A.: Probability distributions as indicators of dissipative dynamics in river chemistry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16778, https://doi.org/10.5194/egusphere-egu24-16778, 2024.

EGU24-17721 | ECS | Posters on site | NP3.3

Multifractal analysis of aerosol particle concentration during rain and dry conditions in nm and µm range 

Jerry Jose, Yelva Roustan, Auguste Gires, Ioulia Tchiguirinskaia, and Daniel Schertzer

Below cloud scavenging by rain is known to be a very efficient sinking mechanism for aerosols in atmosphere. Since this scavenging depends on interaction between aerosol particles as well as the scavening raindrops, and notably their respective size ranges, it is interesting to examine both fields together across various size ranges and across temporal scales. Towards this, a 4 month long data was used from Cherbourg-Octeville, France from 01/11/2010 to 12/03/2011 from the experimental station managed by Institut de Radioprotection et de Sûreté Nucléaire (IRSN). Here, simultaneous and continuous measurement of size resolved particle concentration (14.6 to 478.3 nm and 0.523 to 19.81 µm) range has been done using Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS), and rain measurement using a disdrometer.

Variation of total aerosol concentration in nm and µm range, as well as individual number concentration in small size bins were analyzed according to rain and dry events, using the framework of Universal Multifractals (UM). UM is widely used, as a physically based scale invariant framework, for characterizing and simulating extreme variability and intermittency in geophysical fields. From initial analysis, the total concentration showed scaling properties (1 min to 1 hr), in both rain and dry events, regardless the scavenging efficiency of event. This was further explored in individual concentration ranges and they showed similar scaling properties in different rain types. However, while considering the different stages of rain, say start and end, the values of UM parameters showed some variation. To understand the behavior more clearly, few sizes were selected from nm and µm range, and efforts were made to extract the field which is devoid of scavenging by rain. Understanding the correct transformation required to extract accurate UM values and comparing the scavenging and non scavenging fields will improve understanding of particle concentration variation, and eventually understanding of scavenging coefficient.

How to cite: Jose, J., Roustan, Y., Gires, A., Tchiguirinskaia, I., and Schertzer, D.: Multifractal analysis of aerosol particle concentration during rain and dry conditions in nm and µm range, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17721, https://doi.org/10.5194/egusphere-egu24-17721, 2024.

EGU24-17984 | ECS | Orals | NP3.3

Observation of different multifractal phase transitions over three typhoon events 

Ching-Chun Chou, Auguste Gires, Li-Pen Wang, Ioulia Tchiguirinskaia, and Daniel Schertzer

Rainfall is extremely variable in both space and time, which makes its analysis complex. A widely used framework to properly handle these features is Universal Multifractals (UM), which is a physically based and mathematically robust framework. It relies on three parameters, meaning it is parsimonious. Two types of multifractal phase transitions can affect the analysis of a series: (i) the divergence of moments, which is related to the singular limit of the underlying cascade process at small scales and notably explains the power law fall-off observed on numerous geophysical fields, (ii) sampling limitations, which is related to the fact that great moments cannot be observed on finite series.
 
This study employs UM to analyse the time series of rainfall intensities observed by the Parsival2 disdrometer at the 10-second resolution from three distinct typhoons over the period of July to October 2022, revealing differences and limitations in their statistical characteristics. It enables us to illustrate the  two previously mentioned concepts of divergence of moments and sampling limitations and their impact on the analysis of rainfall data.

The analysis of typhoon Hinnamnor exhibited limitations due to the sampling dimension, indicating that the current data length was insufficient to capture the multifractal nature of the rainfall events for large moments, reducing the robustness of the analysis for moments greater than 5.43. It reflects sampling limitations, leading to a constrained understanding of extreme events.

For typhoon Nalgae, our analysis highlighted the occurrence of divergence of moments, i.e. a limitation associated with a critical moment. As higher-order moments were calculated, we observed statistical values tending towards infinity, suggesting that extreme rainfall events significantly influenced this typhoon and pointing out the inadequacy of traditional statistical methods in such scenarios. Such multifractal phase transition is seldom observed on individual series, highlighting the interest of studying this typhoon series. 

Finally, the analysis of the typhoon Nesat presented a behavior affected by both multifractal phase transitions resulting in a more complex interpretation. 

Our findings provide new insights into the multifractal analysis of typhoon rainfall intensities, emphasising the importance of considering multifractal theory and its associated phase transitions when dealing with natural phenomenon data. These discoveries lay a crucial methodological foundation for more accurate prediction and response to extreme weather events. In case of rainfall, it then has some hydrological consequences notably in terms of stormwater management or optimization of dams for hydraulic production.

How to cite: Chou, C.-C., Gires, A., Wang, L.-P., Tchiguirinskaia, I., and Schertzer, D.: Observation of different multifractal phase transitions over three typhoon events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17984, https://doi.org/10.5194/egusphere-egu24-17984, 2024.

EGU24-19055 | ECS | Posters on site | NP3.3

Role of size and height of ice sheet on millennial-scale climate variability 

Yuta Kuniyoshi, Ayako Abe-Ouchi, Sam Sherriff-Tadano, and Wing-Le Chan

Unlike the interglacial stable climate, glacial climate was dominated by millennial-scale variability, which is strongly associated with changes in the Atlantic meridional overturning circulation (AMOC). The development of the North American ice sheet has been shown to have a significant impact on the strength of the AMOC through surface cooling and enhanced surface winds. However, the impact of mid-glacial ice sheet involved in millennial-scale variability of the AMOC are still elusive. Here, using a coupled atmosphere-ocean model MIROC4m, we perform several climate simulations under mid-glacial ice sheet configurations. We use Marine Isotope Stage (MIS)-5a and MIS-3 ice sheet configurations as boundary conditions, which are derived from the simulation of an ice sheet model, IcIES-MIROC. These volumes are the 40 m sea level equivalent for MIS5a (approximately 33% of the LGM) and the 96 m sea level equivalent for MIS3 (approximately 80% of the LGM). To account for uncertainty in the altitude of the ice sheet, we also conduct experiments under topographic conditions in which only the altitude was changed, but not the extent, for each ice sheet configuration. As a result, self-sustained oscillations of millennial-scale periodicity in the climate and AMOC are simulated for both ice sheet cases. The result suggests that the millennial-scale climate variability could occur as long as the North American ice sheet exists, even if the ice sheet is small. The expansion of the North American ice sheet from MIS5a to MIS3 have an influence of shortening the weak AMOC period (stadial) and lengthening of the strong AMOC period (interstadial), because the stronger surface winds over North Atlantic enhance retreat of sea-ice during the stadial and increase salt transport via wind-driven ocean circulation during the interstadial. Meanwhile, one of the other simulations under the ice sheet condition with MIS3-equivalent extent but altitudes as low as 50% results in a persistent stadial state, which is due to the large cooling effect. Our results show that the relative strength of surface wind and surface cooling effects depends on the ice sheet configuration, which could modify the length of stadial and interstadial.

How to cite: Kuniyoshi, Y., Abe-Ouchi, A., Sherriff-Tadano, S., and Chan, W.-L.: Role of size and height of ice sheet on millennial-scale climate variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19055, https://doi.org/10.5194/egusphere-egu24-19055, 2024.

EGU24-19127 | ECS | Orals | NP3.3 | Highlight

Climate legacies in macroevolutionary dynamics 

Gregor Mathes

Biodiversity is critically endangered by anthropogenic climate change. One of the core goals of ecological research and conservation science is therefore to enhance the mechanistic understanding of the processes that cause species to go extinct, particularly in light of anthropogenic climate change. However, the presence of non-linearities, multiple equilibria, thresholds, and internal feedbacks within ecological and climatic systems often impedes a mechanistic comprehension. One fundamental issue for extinction studies using contemporary data is that this data is always dependent on past conditions. Within ecology, the dependence of contemporary biodiversity dynamics on past climate is generally termed “climate legacy”. Climate legacies can arise from a multitude of ecological processes, such as time lags, niche conservatism, physiological thresholds, or cascading effects. Further, climate legacies can be assumed to be present in all ecological systems as a consequence of the dynamic nature of ecological patterns and processes. If not accounted for, climate legacies can hinder or even prevent the detection of true ecological responses to climate change. However, few studies on the relationship between extinction dynamics and climate include these climate legacies. Even less studies reach beyond merely discussing potential impacts of climate legacies and include them in their empirical framework. Those studies where climate legacies were included and quantified found a large impact of these legacy effects on extinction dynamics. Here I introduce a methodical framework for the quantification of effects arising from climate legacies in biotic systems of any temporal scale. I first introduce the concept of climate interactions, which describe and quantify the potential dependence of extinction risk on the long-term climatic context. Climate interactions might create a characteristic pattern in extinction dynamics and can arise from climate legacies acting over days to millions of years. They therefore provide a unifying framework for studying the consequences of climate legacies in ecosystems. The expected characteristic pattern consists of higher extinction risk, or related measures, when climatic changes add to previous trends in the same direction (such as a short-term warming adding to a long-term warming trend). It is hypothesized that these synergistic climate interactions first lead to environmental conditions increasingly different from initial adaptations of taxa, which then result in a higher extinction risk for these taxa. An antagonistic climate interaction, where a short-term climate change reverses a previous long-term trend (such as short-term cooling adding to a long-term warming trend), might result in a generally lower extinction risk through climatic conditions being more similar to initial adaptations of taxa. The emergence of expected patterns are then tested in  a variety of ecosystems, both marine and terrestrial, taking advantage of the fossil record with its rich information of past responses of organisms to climatic changes. 

How to cite: Mathes, G.: Climate legacies in macroevolutionary dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19127, https://doi.org/10.5194/egusphere-egu24-19127, 2024.

CL5 – Tools for Climate studies

EGU24-1995 | ECS | PICO | CL5.2

Balloon drift estimation and improved position estimates for radiosondes 

Ulrich Voggenberger, Leopold Haimberger, Federico Amgrogi, and Paul Poli

When comparing model output to historical radiosonde observations, it is typically assumed that the radiosonde has ascended directly above its launch site and has not been moved by the wind. The introduction of Global Navigation Satellite System (GNSS) receivers on radiosondes in the late 1990s has led to a recent change in the availability of balloon trajectory data. However, this information was still not always transmitted, despite being the basis for estimating wind. Radiosondes can drift a few hundred kilometres, especially in mid-latitudes during winter months, depending on conditions and time of year. Position errors may result in significant representation errors when assimilating corresponding observations.We have developed a methodology to calculate changes in balloon position during vertical ascent using limited information, such as the vertical wind profile in historical observation reports. The investigation analysed the method's sensitivity to various parameters, including the vertical resolution of the input data, the assumption about the vertical ascent speed of the balloon, and the departure of the Earth's surface from a sphere. To validate the method, modern GNSS sonde data reports were considered, which provided the full trajectory of the balloon and the estimated wind. The evaluation was conducted by comparing the results with ERA5 and conducting low-resolution data assimilation experiments. The study evaluated the accuracy of reconstructing the trajectory of radiosonde using original data of varying vertical resolution. The results indicate that the accuracy of the reconstructed trajectory can be improved by using more accurate balloon positions, which reduces both representation and systematic errors.Radiosonde measurements have a wide range of applications, including near-real-time use by forecasters and Numerical Weather Prediction (NWP), as well as for air pollution and other scientific investigations, such as climate monitoring. The production of climate reanalyses that directly assimilate radiosonde observations, such as ERA5, is expected to benefit from more accurate historical balloon position data, similar to NWP. 

How to cite: Voggenberger, U., Haimberger, L., Amgrogi, F., and Poli, P.: Balloon drift estimation and improved position estimates for radiosondes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1995, https://doi.org/10.5194/egusphere-egu24-1995, 2024.

EGU24-3369 | ECS | PICO | CL5.2

Observed climate extreme indices trends and variation in Gandhinagar, Gujarat 

Sandeep Kumar and Bhawana Pathak

Climate change is very evident and transformative in the 21st century. Variations in rainfall and temperature define the ecosystem services, extreme events (flood, drought, heatwave etc.) and agricultural activities, especially in developing countries such as India where the majority of the population is agricultural dependent. Apart from global variability in rainfall and temperature, a significant change has been also observed at the regional level. Thus it’s also very important to study regional variation in climate extreme indices. In this paper historical variation (1991-2022) in rainfall and temperature extreme indices has been computed over the Gandhinagar district, Gujarat. Daily rainfall and temperature gridded data from the Indian Meteorological Department (IMD) have been acquired and used for the Expert Team on Climate Change Detection and Indices (ETCCDI) extreme indices calculation. A data homogenization technique was applied for the quality control and outliers were removed. As recommended by ETCCDI core rainfall (CDD, CWD, PRCPTOT, R30mm) and temperature (CSDI, WSDI, DTR) extreme indices were calculated. The trend was calculated using Mann-Kendall (M-K) and Sen’s slope estimator. It was observed that Consecutive Dry Days (CDD) are decreasing (R2 = 0.05) as the days having a minimum rainfall of 10mm are increasing (R2 = 0.02). Cold Spell Duration Indicator (CSDI) suggests that the period having minimum temperature is decreasing (R2 = 0.3) which is also supported by the decreasing Diurnal Temperature Range (DTR) (R2 = 0.25). The observed change in CSDI and DTR is more influenced by the minimum rather than maximum temperature as a continuous rise in minimum temperature has been observed since 1991. Since Gandhinagar district is developing at a very rapid pace the results of this study could be used for the climate change policy framework and better sustainable developmental strategies for the region.

How to cite: Kumar, S. and Pathak, B.: Observed climate extreme indices trends and variation in Gandhinagar, Gujarat, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3369, https://doi.org/10.5194/egusphere-egu24-3369, 2024.

The identification of non-stationary behavior in extremes is crucial for the analysis of climatic and environmental data. As an alternative to classical extreme value theory, the investigation of events that break new records proves particularly appealing. While the increment in averaged temperatures over recent decades is well-characterized and studied, the characterization of changes in record-breaking temperature events remains an open problem. In this work, the R package RecordTest (Castillo-Mateo et al. 2023a), available on CRAN (https://CRAN.R-project.org/package=RecordTest) and GitHub (https://github.com/JorgeCastilloMateo/RecordTest), is introduced. This package offers a framework for non-parametric analysis of non-stationary behavior in extremes, based on record-breaking analysis. The main idea of these inference tools is based on verifying whether the observed records in the data align with the distribution of record occurrences under stationary series of random variables. Several hypothesis tests are proposed to detect trends or change-points in record occurrences based on both upper and lower records, both in the forward and backward series. The package also implements all necessary steps in such analyses, including data preparation, record identification, exploratory tools, and supplementary graphical tools. The tools included in the package are introduced together with a careful analysis of the impact of climate change on the occurrence of calendar day records in 36 series available from the ECA&D of daily maximum temperatures in the Iberian Peninsula from 1960 to 2021 (Castillo-Mateo et al. 2023b). The objective also includes characterizing the record occurrences in different periods of the year and in different spatial regions. The effects of climate change are heterogeneous within the year, being autumn the season where the effects are weaker and summer where they are stronger. Concerning the spatial variability, the Mediterranean and the North Atlantic region are the areas where the effects are more and less clear, respectively.

References:

Castillo-Mateo, J., Cebrián, A. C., and Asín, J.: RecordTest: An R package to analyse non-stationarity in the extremes based on record-breaking events, Journal of Statistical Software, 106(5), 1-28, https://doi.org/10.18637/jss.v106.i05, 2023a.

Castillo-Mateo, J., Cebrián, A. C., and Asín, J.: Statistical analysis of extreme and record-breaking daily maximum temperatures in peninsular Spain during 1960-2021, Atmospheric Research, 293, 106934, https://doi.org/10.1016/j.atmosres.2023.106934, 2023b.

How to cite: Castillo-Mateo, J., Cebrián, A. C., and Asín, J.: Analyzing non-stationarity in record-breaking temperature events over Peninsular Spain in 1960-2021 using the R package RecordTest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4028, https://doi.org/10.5194/egusphere-egu24-4028, 2024.

EGU24-4100 | PICO | CL5.2

The link between temperature mean and variance trends in summer in France and Spain and its evolution 

Sylvie Parey, Cléo Lemaire, and Thi Thu Huong Hoang

In a previous work (Parey et al. 2010, [1]) a link had been identified between the trends in temperature mean and variance in Europe, with geographical and seasonal differences, and the climate models at the time performed poorly in representing the observed link. In this study, we update the results for summer temperature and go further in looking for possible causes of the observed differences between France and Spain. Then, the performance of the last CMIP6 models in representing the link is assessed in order to anticipate how this link could evolve in the future.

More precisely, in summer in France the trends in mean and variance are generally positively correlated: variance increases when mean increases, whereas in Spain the reverse behavior is generally found. This behavior has been confirmed with recent observation data: individual timeseries as well as the gridded EOBS database. We show that this can be explained by the fact that summers in Spain are more constantly hot, and the variance is explained by the occurrence of milder spells, while in France, summers are mild and the variance is explained by the occurrence of hot spells. The evolution of the link throughout the 1950-2022 period has been studied and revealed that parts of the south of France recently turned toward a similar behavior as Spain, with a decrease in variance when mean increases. The investigated question then is the following: will French summers resemble Spanish summers in the future? To answer the question, the ability of CMIP6 models to represent the observed link is first assessed, and then, the evolution projected by the best performing ones toward the end of the century is studied.

Better understanding the evolution of this link is important to anticipate future hot temperature extremes in France in the long term for adaptation. Owing to the larger impact of variance compared to mean on the intensity of the extremes, this question is crucial for the anticipation of future hot extremes. Do we need to anticipate a general hot summer climate in the second half of the century, or will the summers become warmer with more frequent heat waves and possible large deviations to very hot temperatures?

 

Reference:

[1] Parey S., Dacunha-Castelle D., Hoang T.T.H. : Mean and variance evolutions of the hot and cold temperatures in Europe; Clim Dyn (2010) 34:345–359, DOI 10.1007/s00382-009-0557-0

How to cite: Parey, S., Lemaire, C., and Hoang, T. T. H.: The link between temperature mean and variance trends in summer in France and Spain and its evolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4100, https://doi.org/10.5194/egusphere-egu24-4100, 2024.

EGU24-5530 | PICO | CL5.2

Changes in sector-specific climate indices: an extension to HadEX3 

Robert Dunn, Nicholas Herold, Lisa Alexander, and Markus Donat

Extreme events have widespread impacts across human health, our infrastructure, and the natural environment. So far there has not been a global product which presents climate indices relevant for different sectors of our society, including health, agriculture, and water resources. Here we present an extension to HadEX3, an existing dataset of extremes indices based on in situ observations, by including indices recommended by the World Meteorological Organisation (WMO) which were developed with sector specific applications in mind. We have used the approach and methodology of HadEX3, and where possible the same underlying daily temperature and rainfall observations, to produce quasi-global land fields over 1901-2018.  We will demonstrate the key features of this extension, with temperature indices showing changes consistent with global scale warming, as indicated by heat wave characteristics showing increases in the number, duration, and intensity of these extreme events in most places.

How to cite: Dunn, R., Herold, N., Alexander, L., and Donat, M.: Changes in sector-specific climate indices: an extension to HadEX3, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5530, https://doi.org/10.5194/egusphere-egu24-5530, 2024.

EGU24-5669 | PICO | CL5.2 | Highlight

When winter is weird: Quantifying the change in winters across the Arctic 

Laura Helene Rasmussen, Bo Markussen, and Susanne Ditlevsen

Arctic winter climate is rapidly changing, with more variable snow depths, spring snowmelt timing, and more frequent midwinter thaw events. Less predictable conditions disrupt ecosystem balances and development in Arctic communities, and understanding winter variability across the Arctic and its influence on climate the whole year is needed to mitigate consequences of changing winters. However, access to in situ measured data has been extremely limited and scattered in local databases. Hence, cross-Arctic winter studies are few and based on remotely sensed data with larger spatial and temporal coverage, but less local sensitivity, and the winter contribution to annual average temperature change has not been investigated across the Arctic.

In this project, which runs January 2024-December 2025, we 1) obtain, clean and standardize in situ soil surface temperature, snow depth and soil moisture data from climate monitoring programs across the Arctic and create a unique database with cross-Arctic in situ winter climate data from the last appr. 30 years. We will use this dataset to 2a) estimate the accuracy of remotely sensed soil surface temperature, snow depth and soil moisture data using the regression model with the best fit, and quantify the bias, for each major Arctic region. We further 2b) construct an open access Winter Variability Index (WVI) for each major Arctic region based on the winter phenomena (average snow depth, snowmelt date, frequency of winter thaw events) that are most important drivers of a clustering analysis such as hierarchical clustering or autoencoders. Finally, we 3) use the change in WVI and in annual mean temperatures for each decade in a function-on-function regression analysis, which will quantify the contribution of winter variability change to annual average temperature changes in each Arctic region.  

The project will produce a comprehensive dataset with potential for further research and will improve our region-specific understanding of remotely sensed data accuracy, and the WVI allows scientists or local communities to classify Arctic winter data within a quantitative framework of pan-Arctic winter variability also in the future, and to understand how important changes in winter variability is for Arctic climate changes the whole year.

How to cite: Rasmussen, L. H., Markussen, B., and Ditlevsen, S.: When winter is weird: Quantifying the change in winters across the Arctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5669, https://doi.org/10.5194/egusphere-egu24-5669, 2024.

EGU24-7095 | ECS | PICO | CL5.2

Two-level GLM approach for detection of spatio-temporal interactions in daily maximum temperature record-breaking in Spain 1960-2022 

Zeus Gracia-Tabuenca, Elsa Barrio-Torres, Jorge Castillo-Mateo, Jesus Asin, Ana Carmen Cebrian, and Jesus Abaurrea

Recent findings showed that extreme events such as daily maximum temperature record-breaking are not following a stationary pattern, with trends associated to global warming [1]. But there are spatial variability identifying the change-point when this pattern is dated and, most interesting, there is not evidence of non-stationarity in North stations of Spain in spring and autumn. To this regard, it is essential to develop novel tools and models that represent the seasonal and spatial variability, and effectively capture the spatio-temporal dependence of covariates of interest. Effective detection will enable us to more accurately describe and predict which regions may be affected by stronger trends.
In this framework, the utility of spatio-temporal models including relevant covariates for the occurrence of records is evident. However, achieving this objective requires the preliminary identification of the covariates and interaction terms that influence the occurrence of records. Thus, we propose a two-level generalized linear models (GLM) approach to detect spatio-temporal dependence of covariates of interest in daily maximum temperature record-breaking. To do so, we took daily maximum temperatures in the 1960-2022 period in 36 stations distributed over the peninsular Spain with low level of missing values (below 0.5%). We computed the calendar day record-breaking by binarizing the temporal series assigning a one only if a particular daily maximum on year ‘t’ is above all its previous years on the same date [2]. First, for each station a local logistic regression was applied setting the trend term as log(t-1); note that the trend term in the probability of a record, on the logit scale, is -log(t-1) under a stationary climate. Finally, all the estimated beta coefficients for the trend were gathered and correlated with spatial covariates such as latitude, longitude, altitude, and distance to the coast. We found that only log-altitude and log-distance showed a significant positive correlation with the trend coefficients, being the latter the one with a higher effect (r=0.59). Although preliminary, these results showed a straightforward approach to model the relationship between spatial covariates and the temporal trend in extreme events, in particular, record of maximum temperatures. In addition, we anticipate that this tool will be potentially useful to build models based on atmospheric covariates.

References:
[1] Castillo-Mateo, J., Cebrián, A. C., and Asín, J. (2023). Statistical analysis of extreme and record-breaking daily maximum temperatures in peninsular Spain during 1960–2021. Atmospheric Research, 106934. https://doi.org/10.1016/j.atmosres.2023.106934
[2] Castillo-Mateo, J., Cebrián, A. C., and Asín, J. (2023). RecordTest: An R Package to Analyze Non-Stationarity in the Extremes Based on Record-Breaking Events. Journal of Statistical Software, 106, 1-28. https://doi.org/10.18637/jss.v106.i05

How to cite: Gracia-Tabuenca, Z., Barrio-Torres, E., Castillo-Mateo, J., Asin, J., Cebrian, A. C., and Abaurrea, J.: Two-level GLM approach for detection of spatio-temporal interactions in daily maximum temperature record-breaking in Spain 1960-2022, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7095, https://doi.org/10.5194/egusphere-egu24-7095, 2024.

EGU24-7382 | ECS | PICO | CL5.2

A secular decline in daily maximum wind speed over the Tibetan Plateau from 1973-2020 and its possible causes 

Yaoyao Ma, Gangfeng Zhang, Yiwen Wang, and Heng Ma

 

The observed decline and reversal in average near-surface wind speeds over recent decades have been widely reported and confirmed globally and regionally (especially in mid-latitude areas). The trends in extreme wind speeds do not completely synchronize with average wind speeds, and the variability of extreme wind speeds and their driving mechanisms are still unclear, especially for the high mountainous regions, such as the Tibetan Plateau. This study utilizes a homogenized dataset of daily maximum wind speeds from 1973 to 2020 in the Tibetan Plateau to investigate the variability of daily maximum wind speed and uncover the physical processes through which atmospheric circulation influences it. The results indicate that: (1) the daily maximum wind speed in the Tibetan Plateau has significantly decreased in most areas from 1973 to 2020, with the largest decreasing trends in magnitude observed in the spring(-0.57 m s-1dec-1,p<0.05), summer (-0.46 m s-1dec-1, p<0.05), winter (-0.41 m s-1dec-1,p<0.05), and autumn (-0.37 m s-1dec-1, p<0.05).  The frequency of daily maximum wind speed exceeding 95% quantile shows a similar pattern. (2) Large-scale atmospheric circulation plays a key role in influencing the changes in daily maximum wind speed, with the westerly and monsoon patterns explaining 35%~57% of daily maximum wind speed variations. (3) The physical processes associated with atmospheric circulation changes such as geostrophic wind(0 to -0.4 m s-1 dec -1), anticyclone activity(0 to -0.2 K dec -1), vertical wind shear(0 to -0.1 m s-1 dec -1), and Tibetan Plateau low vortex(-0.69 to 0.26 dec-1) across the Tibetan Plateau region, partly explain the decreasing trends in magnitude and frequency of daily maximum wind speed. Our study provides some new insights for the management of sand and dust storms as well as the utilization of wind energy resources in the Tibetan Plateau.

Keywords: Tibetan Plateau, daily maximum wind speed, trend, atmospheric circulation, physical processes

How to cite: Ma, Y., Zhang, G., Wang, Y., and Ma, H.: A secular decline in daily maximum wind speed over the Tibetan Plateau from 1973-2020 and its possible causes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7382, https://doi.org/10.5194/egusphere-egu24-7382, 2024.

EGU24-9727 | ECS | PICO | CL5.2

Variability and  trends of near-surface wind speed over the Tibetan Plateau: the role played by the westerly and Asian monsoon 

Gangfeng Zhang, Cesar Azorin-Molina, Jose A. Guijarro, Lorenzo Minola, and Yaoyao Ma

Near-surface wind speed over the Tibetan Plateau exerts profound impacts on many environmental issues, while long-term (> 50 years) trend and multidecadal variability in the wind speed and its underlying causes in the Tibetan Plateau remain largely unknown. Here, by examining homogenized wind speed data from 104 meteorological stations over the Tibetan Plateau for 1961-2020 and reanalysis datasets, we investigate the variability and long-term trend in the near-surface wind speed and reveal the role played by the westerly and Asian monsoon interaction. The results show that the homogenized wind speed declined ( -0.091 m s-1 decade-1, p < 0.05) annually, with the strongest trend in spring ( -0.131 m s-1 dec-1, p < 0.05), and the weakest trend in autumn (-0.071 m s-1 dec-1, p < 0.05). However, there is a distinct multidecadal variability of wind speed, which manifested in an abrupt increase in wind speed in 1961-1970, a sustained decrease in 1970-2002, and a consistent increase since 2002. The observed variations in NSWS over different studied periods are likely linked to interdecadal variations in atmospheric-ocean interactions, and the correlation analysis unveiled a more important role of background westerly and East Asian winter monsoon in modulating near-surface wind changes over the Tibetan Plateau when compared to East Asian summer monsoon and Indian summer monsoon. The potential physical processes associated with westerly and Asian monsoon changes are further examined, in terms of: (i) regional pressure gradient force (i.e., geostrophic wind speed); (ii) vertical thermal momentum transfer (i.e., atmospheric stratification thermal instability); (iii) vertical dynamic momentum transfer (i.e., vertical wind shear); and (iv) Tibet Plateau Vortices (TPVs). They all partly concord with wind change, which demonstrates, that to varying degrees, these processes are possible causes of near-surface wind speed changes over the Tibetan Plateau. 

How to cite: Zhang, G., Azorin-Molina, C., A. Guijarro, J., Minola, L., and Ma, Y.: Variability and  trends of near-surface wind speed over the Tibetan Plateau: the role played by the westerly and Asian monsoon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9727, https://doi.org/10.5194/egusphere-egu24-9727, 2024.

EGU24-12929 | PICO | CL5.2

Bias adjustments for the global historical radiosonde network in preparation for ERA6 

Leopold Haimberger, Federico Ambrogi, and Ulrich Voggenberger

In preparation for the next generation Copernicus reanalysis ERA6, we aim at providing an as complete as possible global insitu upper-air dataset, augmented with additional data and metadata that allow to reduce observation and representation errors in those data. 

We first reduce representation errors using actual launch times and balloon positions (see presentation by Voggenberger et al.). This allows to get more smaller observation - background (obs-bg) departures compared to the original obs-bg departures calculated during assimilation with ERA5.

The obs-bg departures form the basis for comprehensive statistics-based adjustment of biases in temperature, wind direction and also humidity, using the RAOBCORE/RICH method. The corresponding software has been further improved compared to the past year, now including also adjustments for mobile platforms and paying attention to adjustments of the most recent parts of the time series. 

Results from bias-adjusted temperature records indicate realistic spatial trend heterogeneity and very good fit to reprocessed satellite data products, clearly better than what could be achieved in preparation to the present operational reanalysis ERA5. Temperature Background departures from ERA5 increase substantially, both in terms of mean and standard deviations when going back to the early 1950s and 1940s. It is tried to shed some light whether this increase comes from poorer quality observations or from issues arising due to the less strongly observationally constrained ERA5 state during this period.

Wind direction adjustments are necessary only at a few stations but also have a clearly positive effect on trend heterogeneity and obs-bg departures. Humidity bias adjustments are more delicate, since it is not sufficient to shift the distributions by a mean value, rather one has to adjust also the shape of the distributions. Results from humidity bias adjustments, considered experimental, are quite promising up to 300 hPa. Pervasive strong drying trends over large countries like the US and China could be substantially reduced. More detailed verification is needed, however.

How to cite: Haimberger, L., Ambrogi, F., and Voggenberger, U.: Bias adjustments for the global historical radiosonde network in preparation for ERA6, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12929, https://doi.org/10.5194/egusphere-egu24-12929, 2024.

This study investigates the thermal characteristics of a highly biodiverse mountain ecosystem in southern Ecuador. The analysis involves temperature measurements conducted within the native mountain forest and at open sites across an altitudinal range from 1600 to 3200 meters. The primary methodological objective is to create a tool for regionalizing air temperature, enabling the generation of spatial datasets for average monthly mean, minimum, and maximum temperatures using observational data. These temperature maps, based on data spanning from 1999 to 2023, are essential for ecological projects operating in areas lacking climate station data.

To develop the temperature maps, a combination of a straightforward detrending technique, a Digital Elevation Model, and a satellite-based land cover classification is employed. This classification also provides information on the relative forest cover per pixel. The specific focus of the study is to examine the thermal structure of both components of the ecosystem (pastures and natural vegetation), with special attention given to how the conversion of natural forest into pasture affects the ecosystem's temperature regulation service.

The findings reveal a distinct thermal variation throughout the year, influenced in part by changes in synoptic weather patterns and the impact of land cover. Thermal amplitudes are notably low during the primary rainy season when cloudiness and air humidity are high. However, they become more pronounced in the relatively dry season, marked by differences in daily irradiance and outgoing nocturnal radiation between land cover units. Lower pasture areas, resulting from slash-and-burn practices on the natural forest, experience the most extreme thermal conditions, while the atmosphere within the mountain forest remains slightly cooler due to the regulating effects of dense vegetation.

In summary, the study underscores that clearing the forest diminishes the ecosystem's thermal regulation function (regulating ecosystem services). This reduction in thermal regulation could pose challenges, especially in the context of anticipated global warming trends in the future.

How to cite: Grigusova, P., Dobbermann, M., and Bendix, J.: Examining the thermal characteristics of a highly diverse Andean mountain ecosystem in southern Ecuador and explore the process of regionalizing its thermal patterns., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13171, https://doi.org/10.5194/egusphere-egu24-13171, 2024.

EGU24-16365 | ECS | PICO | CL5.2

Pushing the time and space resolution for historical marine data: new datasets of sea-surface temperature and marine air temperature 

Agnieszka Faulkner, Richard Cornes, Steven Chan, Joseph Siddons, and Elizabeth Kent

Sea Surface Temperature (SST) and Marine Air Temperature (MAT) are essential climate variables (ECVs) and gridded datasets of these variables are used in many applications including global climate monitoring, evaluation of climate model simulations, providing boundary conditions for reanalysis datasets (in the case of SST) and for understanding air-sea interactions. While surface marine observations of MAT and SST extend back over 200 years, existing global high-resolution in-filled SST datasets span mostly from the early 1980s, which marks the start of satellite observations. Prior to that period, global datasets consist of monthly temperature values at a lower spatial resolution or areas limited to the location of observations without in-filling of grid-cells not covered by data.  

This work presents new global, in-filled datasets of SST and MAT. The SST dataset is provided at a sub-monthly, one-degree spatial resolution back to 1850, whereas the MAT dataset is generated at a monthly five-degree spatial resolution and extends back to the 1790s. As such it is the longest spanning in-filled air temperature record for the global ocean. 

The principal source of data used in these gridded datasets is the International Comprehensive Ocean-Atmosphere Data Set (ICOADS, https://icoads.noaa.gov/). Those data have been supplemented by newly recovered sources for certain regions and periods. The MAT dataset has been constructed solely using ship-based observations of air temperature whereas the SST dataset uses a combination of ship-based measurements and buoy data.  The ship data in both datasets have undergone a new processing procedure, with improved Quality Control (QC) flags, duplicate detection, improved work on the mis-positioning and mis-dating of some of the data sources and newly developed ship tracking method. For the SST dataset improved bias estimates for the measurements have been developed and have applied to the data. Gridded fields have been constructed from these quality-controlled/bias-adjusted values using ordinary kriging. Uncertainty values are provided with the datasets, and the derivation of these estimates will be described. 

How to cite: Faulkner, A., Cornes, R., Chan, S., Siddons, J., and Kent, E.: Pushing the time and space resolution for historical marine data: new datasets of sea-surface temperature and marine air temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16365, https://doi.org/10.5194/egusphere-egu24-16365, 2024.

EGU24-17030 | PICO | CL5.2

A new observational analysis of near surface air temperature change since the late 18th century developed for the GloSAT project 

Colin Morice, David Berry, Richard Cornes, Kevin Cowtan, Thomas Cropper, John Kennedy, Elizabeth Kent, Nick Rayner, Hamish Steptoe, Timothy Osborn, Michael Taylor, Emily Wallis, and Jonathan Winn

The GloSAT project is developing a new observational analysis of global air temperature change over land and ocean since the late 18th century.

A new global analysis processing system has been developed that uses a computationally efficient spatial statistical method to estimate air temperature anomaly fields from historical observations. This will be the first presentation of this analysis approach. This method, based on Gaussian Markov Random Fields, jointly estimates temperature anomaly fields over land and ocean based on weather station and ship-based air temperature observations. The increased computational efficiency of the approach compared to conventional kriging-based estimates allows for increased spatial resolution in the analysis.

Observational uncertainties are represented within the analysis framework to propagate uncertainty into the output ensemble data set. This accounts for errors arising from uncorrelated effects and structured errors such as residual biases in observations from an individual weather station or ship after correction. Observational error models have been co-developed with project partners providing the input land and marine data products.

Initial results from the application of the analysis system to GloSAT air temperature observation data will be demonstrated.

How to cite: Morice, C., Berry, D., Cornes, R., Cowtan, K., Cropper, T., Kennedy, J., Kent, E., Rayner, N., Steptoe, H., Osborn, T., Taylor, M., Wallis, E., and Winn, J.: A new observational analysis of near surface air temperature change since the late 18th century developed for the GloSAT project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17030, https://doi.org/10.5194/egusphere-egu24-17030, 2024.

Indus River Basin supports approximately 268 million inhabitants, covering four different countries, including Pakistan, India, China and Afghanistan. Most countries situated in this basin are highly vulnerable to the impacts of climate change, even though their emissions are low. The basin has a large agriculture-based economy; therefore, we are interested in assessing the impacts of climate change on agriculture under best- and worst-case scenarios. In this study, a mean ensemble of four CMIP6 climate models was used with a resolution of 50km, and the analysis was conducted on a subbasin scale through delineation of the entire Indus basin. The climate indices estimated are extreme maximum temperature (TXx), extreme minimum temperature (TNn), heat stress (TR), maximum 5-day precipitation (RX5day), 95th percentile of precipitation (R95pTot), consecutive dry days (CDD), growing season length (GSL), and heat sum (HS). The climate indices data was analyzed spatially and temporally by estimating trends, their significance, areal mean time series and plotting Hovmuller diagrams. Temperature-based indices TXx and TNn show a significant increase across the basin, while TR seems to increase mostly in the Lower Indus Basin plain. This may lead to crop failure due to excess heat and put more pressure on available water resources. Precipitation-based indices RX5day and R95pTot show a rise in flood risks in the eastern subbasins, while the number of CDD will vary across the region. The Hovmuller diagrams show that spatial precipitation patterns will be irregular across the basin, making it difficult to follow traditional agricultural practices. A significant increase in GSL and HS is noted in the Upper Indus Basin, making the region more suitable for agriculture, and the seasonal differences plot showed that the summer months of July, August & September will have the largest increase in extreme precipitation with high spatial variability. To conclude, climate adaptation measures are necessary, and a nexus-based resource management approach should be considered in the decision-making process. 

How to cite: Pyarali, K., Zhang, L., and Al-Qubati, A.: Unveiling Tomorrow's Climate: Indus River Basin in Focus - A Comprehensive Assessment using Cutting-edge CMIP6 Data for SSP126 and SSP585 Scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18428, https://doi.org/10.5194/egusphere-egu24-18428, 2024.

EGU24-19073 | ECS | PICO | CL5.2

Sampling errors in daily average temperatures from Greenland climate records 

Dina Rapp, Jacob Lorentsen Høyer, and Bo Møllesøe Vinther

Over the last years destructive climate events like heat-waves and floods have been attributed to global warming. The warming trend is higher in the Arctic than the global average, therefore its contribution to the global warming is relatively larger than other areas.  In addition, the temperature increase in Greenland is an important driver of the melting of the Greenland Ice-Sheet, which leads to sea level rise. It is crucial to have temperature records of high quality in this area to properly assess the climatic changes. This will improve understanding of the involved physical mechanisms, past changes and improve predictions for the future temperature development in the Arctic. This study investigates daily averages of the sub-daily 2m air temperature measurements from the DMI Greenland station network spanning 1958-present day. The data from before 1958 has only been digitized as monthly averages, where parts of the data has been homogenized. The data from after 1958 has not been homogenized. The data is currently used for assessment and predictions of the surface mass balance of the Greenland Ice Sheet, temperature/climate reanalyses, global temperature products, validation of proxy data, etc.

This study assesses the errors due to uneven sampling times, and presents a method to improve the calculation of daily average temperatures. The current practice is to average the available measurements without considering what time of day they are from and how the measurements are distributed. In addition to missing values, the weather station network has periods of different measurement practices for different stations. Before automatic weather stations were introduced several weather stations have periods with measurements only from the daytime, when the temperatures are generally higher. This can lead to a warm bias in the daily averages compared to more recent data where there are generally observations for every hour of the day. This can affect temperature trends, as the positive bias is generally found in earlier periods of the dataset. As the diurnal cycle varies over the year, the magnitude of the bias also varies seasonally. The correction method used to reduce these biases is a moving average over the years with evenly distributed data covering the whole day, taking into consideration hours of observation present and time of year of the station in question. The biases before and after correction are assessed. The largest average simulated bias before correction over several years of data is 1.25 °C. The largest average simulated bias after correction is reduced to 0.45 °C. These corrections will improve the monthly and annual average temperatures for the DMI Greenland station network, as they are calculated from the daily average temperatures. This study is limited to the weather station network in Greenland managed by DMI, but the findings are relevant for other networks in other areas, as long as there are uneven sampling times and a diurnal temperature cycle. This problem might affect decision making on a high level, like assessing a breach of the Paris agreement. 

How to cite: Rapp, D., Høyer, J. L., and Vinther, B. M.: Sampling errors in daily average temperatures from Greenland climate records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19073, https://doi.org/10.5194/egusphere-egu24-19073, 2024.

EGU24-6080 | Posters on site | CL5.3

U-Th dating of gypsum: methodology and reference materials 

Xuefeng Wang, Lisheng Wang, Zhibang Ma, Wuhui Duan, and Jule Xiao

Gypsum is a common evaporate mineral in a wide variety of geological settings, especially in arid and semi-arid areas. It often precipitated from the natural brine systems with trace amounts of U and almost no Th, rendering it a potentially valuable U-Th geochronometer. However, U-Th dating of gypsum is often challenging, such as how to quickly and completely digest gypsum into solution, and avoid the re-crystallization of gypsum particles during the digestion and chromatography process. Here we present a rapid and practical method for high-precision U-Th dating of gypsum using the (NH4)2CO3 exchange reaction and double-spike method by MC-ICPMS. Our developed protocol addresses these conventional challenges by using the chemical reaction between calcium sulfate and carbonate, resulting in the (NH4)2SO4 solution and CaCO3 precipitate. Then the CaCO3 could be easily digested by diluted acid. With the solid-liquid separation, Ca2+ and SO42- ions are also effectively separated, minimizing the recrystallization of gypsum. The (NH4)2CO3 median, the gypsum/carbonate molar ratio of 1: 4, and the exchange reaction duration of 1.5 ~ 2 hours are suggested in this protocol. Since there is no gypsum U-Th dating reference materials to validate the accuracy of different approaches and ensure methods are repeatable across laboratories. We also prepared and characterized two natural gypsum U-Th dating reference materials (PXCG-1, PXCG-2) from PiXiao Cave, southwest China. Data from three different laboratories exhibit good agreement with both 238U content, δ234U, 230Th/238U activity ratio, and the 230Th ages. The 230Th ages of PXCG-1, PXCG-2 RMs proposed are 66.97 ± 0.31 ka, 260.82 ± 3.39 ka, respectively.

How to cite: Wang, X., Wang, L., Ma, Z., Duan, W., and Xiao, J.: U-Th dating of gypsum: methodology and reference materials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6080, https://doi.org/10.5194/egusphere-egu24-6080, 2024.

EGU24-10443 | Posters on site | CL5.3

14C bomb peak and the onset of the Anthropocene 

Irka Hajdas, Carley Crann, Kristine DeLong, Barbara Fiałkiewicz-Kozieł, Juliana Ivar Do Sul, Jerome Kaiser, Francine M.G. McCarthy, Simon Turner, Allison Stenger, Colin Waters, and Jens Zinke

The unprecedented environmental changes resulting from anthropogenic activities initiated during the Great Acceleration of the mid-20th century can be traced using radiocarbon analysis. The cosmogenic isotope 14C, which is produced in the atmosphere, is well-known as the geochronological tool applied to archives of the last 55 thousand years. However, during the last 200 years, the natural signal of 14C in the atmosphere and connected reservoirs (biosphere, ocean, soils, etc.,) has been perturbed by human activities. Two anthropogenic effects are observed: a decreasing trend observed in 14C concentration of the atmosphere (Suess effect) which has been temporarily reversed by aboveground thermonuclear tests of the 1950/60s.

The excess of the artificially produced 14C (bomb pulse) is a useful time marker for the mid-20th century and the detection of the bomb peak in natural archives has thus been proposed as a tool to locate and date the onset of a proposed new epoch, the Anthropocene [1].

Here we present the results of radiocarbon analysis conducted as a part of the research dedicated to establishing the Global boundary Stratotype Section and Point (GSSP) for the proposed Anthropocene series. The studied sites include corals (Flinders Reef, AU and Flower Garden Banks, USA)[2, 3], peat (Śnieżka peatland, PL)[4], lake sediment (Crawford Lake, CA and Searsville Lake, USA)[5, 6] and marine sediment (East Gotland Basin, Baltic Sea)[7]. The variety of records (different carbon reservoirs) required site and sample-specific treatment prior to analysis and site-specific interpretation of the measured 14C. Nevertheless, the mid-20th century bomb peak was detected at all but one of these sites (Searsville Lake)[6]. In all records, the observed onset of the 14C bomb peak always postdates 1954, the year of the first atmospheric 14C bomb increase. The specific reservoir effects and corrections will be discussed.

References

The Anthropocene Review, 2023. 10(1):

1.    Waters, C.N., et al. (Eds.), Candidate sites and other reference sections for the Global boundary Stratotype Section and Point of the Anthropocene series.  p. 3-24.

2.    Zinke, J., et al., North Flinders Reef (Coral Sea, Australia) Porites sp. corals as a candidate Global boundary Stratotype Section and Point  for the Anthropocene series.  p. 201-224.

3.    DeLong, K.L., et al., The Flower Garden Banks Siderastrea siderea coral as a candidate Global boundary Stratotype Section and Point  for the Anthropocene series. p. 225-250.

4.    Fiałkiewicz-Kozieł, B., et al., The Śnieżka peatland as a candidate for the Global boundary Stratotype Section and Point  for the Anthropocene series.  p. 288-315.

5.    McCarthy, F.M.G., et al., The varved succession of Crawford Lake, Milton, Ontario, Canada as a candidate Global boundary Stratotype Section and Point for the Anthropocene series.  p. 146-176.

6.    Stegner, M.A., et al., The Searsville Lake Site (California, USA) as a candidate Global boundary Stratotype Section and Point for the Anthropocene Series. p. 116-145.

7.    Kaiser, J., et al., The East Gotland Basin (Baltic Sea) as a candidate Global boundary Stratotype Section and Point for the Anthropocene series. p. 25-48.

How to cite: Hajdas, I., Crann, C., DeLong, K., Fiałkiewicz-Kozieł, B., Ivar Do Sul, J., Kaiser, J., McCarthy, F. M. G., Turner, S., Stenger, A., Waters, C., and Zinke, J.: 14C bomb peak and the onset of the Anthropocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10443, https://doi.org/10.5194/egusphere-egu24-10443, 2024.

EGU24-13250 | Posters on site | CL5.3

Assessing Gol-e-Zard Cave (GZS) and Bergen Speleothem Standards (BSS) for U/Th Geochronometry Using MC-ICP-MS 

Altug Hasözbek, Fernando Jiménez-Barredo, Arash Sharifi, Ali Pourmand, Regina Mertz-Kraus, Michael Weber, Denis Scholz, Stein-Erik Lauritzen, Josep M. Parés, and Silviu Constantin

Recent advancements in MC-ICPMS technology have significantly enhanced the application of U/Th geochronometry in both biogenic and chemically precipitated carbonate rocks of almost middle Pleistocene to upper Holocene. This burgeoning use, particularly in the study of late Pleistocene earth surface processes, underscores the need for standardized reference materials with a broad age spectrum with different uranium and thorium concentrations. Addressing this need, our study evaluates speleothem specimens, Gol-e-Zard Cave Standard (GZS) and Bergen Speleothem Standard (BSS), as potential reference materials.

BSS-2 was processed as a homogenized powder and dissolved aliquot for U-Th dating using MC-ICP-MS analysis. We employed various digestion and ion-resin chromatography separation methods, followed by U-Th dating using MC-ICP-MS at CENIEH, University of Miami, and University of Mainz. The ion chromatography protocols yielded recovery rates ranging from 85% to over 95%. U-series analyses of powdered BSS-2 indicated uncertainties between 0.2-1.5%, attributed to variations in the Beta-factor and the specific U and Th standard bracketing procedures used across laboratories. The dissolved BSS-2 aliquots yield between 1.5-2% of uncertainty. Obtained U-Th ages were 122.8 ± 3.3 ka (University of Miami), 124.5 ± 0.3 ka (University of Mainz), and 123.9 ± 3.2 ka (CENIEH) in the powdered samples. Furthermore, in dissolved samples, the Th-ages vary between 126.9 ± 2.9 to 127.9 ± 3.1 (CENIEH & University of Miami). GZS was prepared as a dissolved standard and the Th-date results obtained from this stalagmite are 3967 ± 0.1 to 3988 ± 0.1 (University of Miami), and 3967 ± 0.1 to 4060 ± 0.4 (CENIEH).

All Th-dates required no correction as activity ratios [230Th/232Th] exceeded 500 and 150 for BSS-2 and GZS, respectively. The consistency of these preliminary results across different laboratories suggest that GZS and BSS-2 are promising reference materials for U-Series analysis of calcium carbonate.

How to cite: Hasözbek, A., Jiménez-Barredo, F., Sharifi, A., Pourmand, A., Mertz-Kraus, R., Weber, M., Scholz, D., Lauritzen, S.-E., M. Parés, J., and Constantin, S.: Assessing Gol-e-Zard Cave (GZS) and Bergen Speleothem Standards (BSS) for U/Th Geochronometry Using MC-ICP-MS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13250, https://doi.org/10.5194/egusphere-egu24-13250, 2024.

EGU24-17301 | ECS | Posters on site | CL5.3

Refining the age-depth model of a marine sediment record in the Laptev Sea using Beryllium-10 

Arnaud Nicolas, Gesine Mollenhauer, Maylin Malter, Jutta Wollenburg, and Florian Adolphi

In order to correctly determine leads and lags in the climate system and compare different proxy records over long time periods, it is important to build robust chronologies that can provide the temporal foundation for paleoclimate correlations between marine, terrestrial and ice-core records. One of the main challenges for building reliable radiocarbon-based chronologies in the marine realm is to estimate the regional marine radiocarbon reservoir age correction. Estimates of the local marine reservoir effect, ΔR, during the deglaciation can be obtained by 14C-independent dating methods such as synchronization to other well-dated archives. The cosmogenic radionuclide 10Be provides such a synchronization tool. Its atmospheric production rate is globally modulated by changes in the cosmic ray flux caused by changes in solar activity and geomagnetic field strength. The resulting variations in the meteoric fallout of10Be are recorded in sediments and ice cores and can thus be used for their synchronization.

In this study we use for the first time the authigenic 10Be/9Be record of a Laptev Sea sediment core and synchronize it to the 10Be records from absolutely dated ice cores. Based on the resulting absolute chronology, the ΔR  was then estimated for the Laptev Sea during the deglaciation. The deglacial estimate for the benthic ΔR value for the Laptev Sea is 345±60 14C years, corresponding to a marine reservoir age of 864±90 14C years. We discuss the obtained ΔR in comparison to modern ΔR estimates from the literature and its consequences for the age-depth model. Our refined age-depth model can be used as a reference for the Laptev Sea and the wider Siberian regions of the Arctic Ocean.    

How to cite: Nicolas, A., Mollenhauer, G., Malter, M., Wollenburg, J., and Adolphi, F.: Refining the age-depth model of a marine sediment record in the Laptev Sea using Beryllium-10, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17301, https://doi.org/10.5194/egusphere-egu24-17301, 2024.

EGU24-18258 | Posters on site | CL5.3

Advancing Quaternary Geochronology: Impact of Sample Preparation and Analytical Techniques on Natural Radioactive Dose Assessment in Stream Sediments 

Fernando Jimenez, Altug Hasozbek, Mathieu Duval, Josep M. Pares, M. Isabel Sarró-Moreno, Ana I. Barrado-Olmedo, Estefania Conde-Vila, Marta Fernández-Díaz, Jose Manuel Cobo, Martin Perez-Estebanez, and Javier Alonso-Garcia

Keywords: Geochronology, Sediment, Uranium, Thorium, Microwave Digestion, HR-ICP-MS

In Quaternary geochronology, accurately estimating natural radiation exposure is crucial for dating materials using Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL). Traditional methods like gamma and alpha spectrometry, despite their utility, are limited by sample size requirements and time inefficiency, especially in low-radiation contexts. This study explores the efficacy of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Plasma Mass Spectrometry (ICP-MS), including both Quadrupole (ICP-QMS) and High-Resolution (HR-ICP-MS), for analyzing uranium, thorium, and potassium concentrations in sediments.

We compared various acid digestion methods using standard hot-blocks, microwave digestion, and single cell microwave technology on Sediment Reference Materials (NIST BRS 8704, OREAS 24d). Potassium detection was more accurate with ICP-OES (96% precision) than ICP-QMS (80%). In contrast, HR-ICP-MS significantly outperformed ICP-QMS in measuring uranium and thorium (U and Th recoveries of 99% and 94% vs. 83% and 81%, respectively). Moreover, microwave-assisted digestion methods showed slight advantages in uranium and thorium recovery.

Our findings suggest that a four-acid microwave-assisted digestion, combined with potassium measurement via ICP-OES in radial mode and uranium and thorium quantification using HR-ICP-MS, offers the most accurate and time-efficient approach for natural dose determination in sediment dating. This methodology is particularly relevant for cave, river, and stream sediments even with expected low uranium levels.

How to cite: Jimenez, F., Hasozbek, A., Duval, M., Pares, J. M., Sarró-Moreno, M. I., Barrado-Olmedo, A. I., Conde-Vila, E., Fernández-Díaz, M., Cobo, J. M., Perez-Estebanez, M., and Alonso-Garcia, J.: Advancing Quaternary Geochronology: Impact of Sample Preparation and Analytical Techniques on Natural Radioactive Dose Assessment in Stream Sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18258, https://doi.org/10.5194/egusphere-egu24-18258, 2024.

EGU24-18925 | Posters on site | CL5.3

μGraphiline: a high-throughput, low-maintenance, fully automated 14C graphitization system 

Konrad Tudyka, Kacper Kłosok, Maksymilian Jedrzejowski, Andrzej Rakowski, Sławomira Pawełczyk, Alicja Ustrzycka, Sebastian Miłosz, and Aleksander Kolarczyk

μGraphiline is an innovative, fully automated graphitization system designed for radiocarbon dating using accelerator mass spectrometry. This system streamlines the conversion of samples into CO2 and subsequently into graphite. The standard configuration of μGraphiline is capable of preparing 24 targets daily, demonstrating its high throughput. It achieves a graphitization efficiency of over 95% for 1 mg graphite targets. μGraphiline also offers additional modules for stepped combustion, ramped pyrolysis, and oxidation, all of which can be operated at user-defined temperatures. Furthermore, its design ensures a low background and reproducibility, significantly enhancing the accuracy and reliability of radiocarbon measurements.

 

One of the notable advantages of the system is its low maintenance requirements. It operates efficiently without the need for working gasses such as helium (He), argon (Ar), oxygen (O2), explosive hydrogen (H2) or liquid nitrogen, which simplifies its operation and enhances safety. This feature, coupled with its modular design and high efficiency, virtually no cross-contamination between modules and samples makes μGraphiline an advanced solution for radiocarbon dating. Lastly, the system's repeatability and reliability are backed by reference materials measurements from the International Atomic Energy Agency, demonstrating good repeatability. 

 

This demonstrates μGraphiline's capability to deliver fast, consistent and accurate results, making it a valuable tool for various scientific and research applications.

How to cite: Tudyka, K., Kłosok, K., Jedrzejowski, M., Rakowski, A., Pawełczyk, S., Ustrzycka, A., Miłosz, S., and Kolarczyk, A.: μGraphiline: a high-throughput, low-maintenance, fully automated 14C graphitization system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18925, https://doi.org/10.5194/egusphere-egu24-18925, 2024.

EGU24-19089 | Posters on site | CL5.3

230Th/U and 234U/238U dating of cold-water corals: Approaching the disequilibrium theory 

Norbert Frank and the DCWC

U-series disequilibrium dating or more specifically 230Th/U - dating of cold-water corals is a major absolute chronological toolbox to study the evolution of coral reefs through time and to determine absolute time scales for climate proxies. Advances in multi-collector inductively coupled ion source mass spectrometry (MC-ICPMS) have continuously improved precision of Th and U isotopic measurements over the past decades thanks the development of new high ohmic resistors for Faraday cups. Consequently, isotopic measurements and absolute precision levels are in epsilon ranges for 234U/238U ratios and in the case of materials older than a few tens of thousands of years also for 230Th/238U ratios. To obtain accurate ages the corals isotope ratios need to evolve as a U series closed system and must be free of initial 230Th and non-carbonate materials. The latter being often traced using the natural most abundant 232Th isotope. Coral diagenesis, bio-erosion, residual ferromanganese coatings, recrystallization, and recoil displacement of U isotopes are known sources of age disturbances and U series open system behavior. Here, I want to advocate, however, that such cold-water corals can be ideal dating objects opening far reaching perspectives of marine climate science and for past ecosystem studies. Based on approx. 1200 coral ages and isotope ratios of reef-forming cold-water corals, which correspond to strict quality criteria, a perfect agreement with theoretical predictions of a closed U series system can be found. The resulting oceanic initial (234U/238U) activity ratio for the past 510 ka varies by at most 6.7 ‰ (2s) surrounding the mean of modern seawater and of all reconstructed values of 146.5 ‰ (HU1 reference material is assumed here to be in secular radioactive equilibrium). Consequently, the 234U/238U ratios may be used for dating of old cold-water corals to expand the dating range to more than 1.2 million years. Moreover, any significant deviation between closed system 234U/238U ages and 230Th/238U ages may be used to detect U series open - system behavior. Based on the combined age determination, more consistent chronologies can be derived for cold-water coral reefs beyond 350 ka and theoretically the quality of this archive has opened a path for absolutely dated marine climate proxy records since the Mid Pleistocene Transition.

How to cite: Frank, N. and the DCWC: 230Th/U and 234U/238U dating of cold-water corals: Approaching the disequilibrium theory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19089, https://doi.org/10.5194/egusphere-egu24-19089, 2024.

EGU24-21472 | ECS | Posters on site | CL5.3

Lyoluminescence: a potential tool for dating evaporites up to the Middle-Pleistocene? 

Magdalena Biernacka and Sebastian Kreutzer

Lyoluminescence (LL) is light emission during the solvation of previously irradiated crystals in the liquid-solid interface (Atari, 1980). Our aim is the breakthrough development of lyoluminescence as a dating tool on halite (here: sodium chloride and potassium chloride) for application in Earth Sciences. The positive correlation between radiation dose and LL light emission makes crystal lattice defects viable natural ionizing radiation dosimeters. With a saturation dose of ~10 kGy (e.g. Atari et al., 1973) for sodium chloride dissolved in pure water and for realistic dose rates of ~4 Gy/ka (e.g., Han et al., 2014), the LL signal from salt minerals potentially may determine an age up to 2.5 Ma.
We hypothesize that LL, naturally observable in salt minerals, will allow dating the last recrystallization event significantly beyond the age limits of conventional luminescence-dating methods. In the past, the potential of halite as a material for optical luminescence dating had been suggested, e.g. Bailey et al., (2000); Zhang et al., (2005). However, LL may offer an additional luminescence-dating tool for routine use in geochronology but targeting the crystallization instead of heat or light exposure event. Moreover, it may enable tapping into different archives and subsurface processes where only the event of the last hydration is of interest.
In our contribution, we present the first basic design of a measurement prototype using 3D printing and preliminary experimental results of salts easily soluble in water.

References
Atari, N.A., 1980. Lyoluminescence mechanism of gamma and additively coloured alkali halides in pure water. Journal of Luminescence 21, 305–316. https://doi.org/10.1016/0022-2313(80)90009-5
Atari, N.A., Ettinger, K.V., Fremlin, J.H., 1973. Lyoluminescence as a possible basis of radiation dosimetry. Radiation Effects 17, 45–48. https://doi.org/10.1080/00337577308232596
Bailey, R.M., Adamiec, G., Rhodes, E.J., 2000. OSL properties of NaCl relative to dating and dosimetry. Radiation Measurements 32, 717–723. https://doi.org/10.1016/S1350-4487(00)00087-1
Han, W., Ma, Z., Lai, Z., Appel, E., Fang, X., Yu, L., 2014. Wind erosion on the north‐eastern Tibetan Plateau: constraints from OSL and U‐Th dating of playa salt crust in the Qaidam Basin. Earth Surf Processes Landf 39, 779–789. https://doi.org/10.1002/esp.3483
Zhang, J.F., Yan, C., Zhou, L.P., 2005. Feasibility of optical dating using halite. Journal of Luminescence 114, 234–240. https://doi.org/10.1016/j.jlumin.2005.01.009
 

How to cite: Biernacka, M. and Kreutzer, S.: Lyoluminescence: a potential tool for dating evaporites up to the Middle-Pleistocene?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21472, https://doi.org/10.5194/egusphere-egu24-21472, 2024.

EGU24-767 | ECS | Posters on site | CL5.4

A multi-proxy paleoclimate record from a peat soil of interior Alaska: insight on mechanisms of Holocene peatland formation and landscape development  

Jennifer Kielhofer, Nicholas Patton, Christopher Baish, Elizabeth Thomas, and Brad Sion

Arctic and subarctic regions are warming at an alarming rate, with consequences for permafrost degradation, greenhouse gas emission, ecosystem destabilization, and infrastructure deterioration. Despite high latitude sensitivity to modern climate change, a substantial gap remains in our understanding of high latitude environmental response to past episodes of climatic change. Peat soils, common across the high latitudes, provide a valuable archive for paleoclimate reconstruction to address this knowledge gap. Many such records exist across interior Alaska and have high potential as paleoclimate archives.

Here we develop a multi-proxy paleoclimate record from a peat bog soil (Terric Hemistel) in the Delta River Valley of interior Alaska to explore mechanisms of peatland initiation and evolution. We aim to develop a comprehensive record related to the formation and evolution of this peat bog and test the hypothesis that increased moisture availability and water perching within the soil, rather than warmer temperatures, initiated peatland development. We evaluate key physical and chemical properties of organic and mineral soil materials from pedon descriptions and samples collected by horizon with depths defined according to organic matter content, bulk density, pH, carbon (C), nitrogen (N), and the carbon to nitrogen (C/N) ratio. We use radiocarbon dates to build an age-depth model and analyze stable isotopic signatures (δ13C) of bulk material for moisture and habitat changes, while also evaluating compound-specific isotopic trends (δ13C, δD) of plant waxes to track hydrological fluctuations. Finally, we perform analyses of bacterial branched glycerol dialkyl glycerol tetraethers (brGDGTs) to enable temperature reconstruction.

Our preliminary chronological framework demonstrates the initiation of the peat bog during the Middle Holocene (ca. 6800 cal yr BP) with a consistent growth rate of ~0.15 mm/yr.  At the landscape scale, there is relative stability indicated by pedogenesis through the Holocene, but at the pedon scale there is a shift from concurrent aeolian deposition and mineral soil development to accumulation of organics. This shift in predominant parent material is likely due to a changing moisture regime, inferred to be the result of feedbacks between increased summer precipitation and increased soil water holding capacity. We hypothesize that brGDGTs will show relatively flat temperatures through the Holocene, following other work in the area, while C/N ratios and stable isotope data will indicate pronounced changes in moisture. This multi-proxy approach will help improve models of peatland formation and resolve debate over the response of peatlands to varying climatic conditions (e.g., drier vs. wetter). Such work is particularly important for contextualizing peatland development under ongoing and future climate change. 

How to cite: Kielhofer, J., Patton, N., Baish, C., Thomas, E., and Sion, B.: A multi-proxy paleoclimate record from a peat soil of interior Alaska: insight on mechanisms of Holocene peatland formation and landscape development , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-767, https://doi.org/10.5194/egusphere-egu24-767, 2024.

EGU24-807 | ECS | Posters on site | CL5.4

Using X-ray Fluorescence and Absorption Spectroscopy to Investigate Redox-Sensitive Metals in Late Cretaceous Pedogenic Carbonate Nodules 

Anna Lesko, Troy Rasbury, Ryan Tappero, Paul Northrup, Amanda Barker, and Steve Dworkin

Synchrotron-based X-ray absorption spectroscopy (XAS), in the context of X-ray florescence (XRF) maps, is a powerful analytical tool that can define element speciation and characterize the local atomic structure of a suitable sample. While this type of analysis is regularly used to provide advances in a variety of scientific fields, including but not limited to material sciences, molecular physics, and medical sciences, it remains an underutilized tool in the (paleo)geosciences.  Here, we show that XAS can advance our knowledge of the Critical Zone in deep time. For this study, we used the X-ray fluorescence microprobe (XFM) beamline above the uranium (U) LIII-edge to create detailed XRF elemental maps. Based on these maps, we used X-ray absorption near edge spectroscopy (XANES) to probe U and Manganese (Mn) speciation of pedogenic carbonate nodules collected from Late Cretaceous paleosols from Big Bend National Park, Texas, USA.

Pedogenic carbonate nodules are derived from soil waters that are oversaturated with respect to calcite. Accumulation of pedogenic calcite primarily occurs in semi-arid environments with mean annual precipitation ranging from 500-1200 mm/yr. Nodules are commonly used for uranium/thorium (U/Th) dating, atmospheric CO2 concentration(pCO2) reconstruction, and weathering intensity reconstruction using major and trace element concentrations. As prevalent as nodule research is in these various geological applications, little is known about the compositional variation on a microscale. We present and elucidate the texture, grainsize, and redox-sensitive elemental heterogeneity found within and between carbonate nodules. Preliminary results from U LIII-edge and Mn K-edge XANES showed primarily oxidized U and Mn.  XRF mapping of the samples indicate element discrimination between different carbonate fabrics as well as element zoning. The methods utilized in this study enable us to understand not only the microscale geochemistry of pedogenic carbonate nodules, but to provide an example of how XAS can be beneficial and useful for the paleoclimate and petrography community.

How to cite: Lesko, A., Rasbury, T., Tappero, R., Northrup, P., Barker, A., and Dworkin, S.: Using X-ray Fluorescence and Absorption Spectroscopy to Investigate Redox-Sensitive Metals in Late Cretaceous Pedogenic Carbonate Nodules, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-807, https://doi.org/10.5194/egusphere-egu24-807, 2024.

EGU24-854 | ECS | Orals | CL5.4

Unveiling Undisturbed Alpine Lake Ecosystems: A Multiproxy Approach to Reconstruct past Ecological Response to Climate Variability in the New Zealand Southern Alps 

Julian Eschenroeder, Christopher M. Moy, Sebastian Naeher, Marcus J. Vandergoes, Oliver Rach, Dirk Sachse, Rik Tjallingii, Krystyna M. Saunders, Jamie D. Howarth, and Claire Shepherd

Apart from natural variations in environmental and climatic conditions, human activities (e.g. land-use changes) can have major impacts on freshwater ecosystems. In the context of New Zealand, the arrival of humans approximately 750 years ago has left a permanent mark on landscapes, posing challenges in discerning undisturbed natural conditions for paleoclimatic reconstructions. Yet, remote alpine lakes in the Southwest Pacific can serve as pristine archives of environmental and climate changes, hardly influenced by human activities.

This study focuses on sediment cores obtained from two neighbouring catchments of Lake Bright and Lake Laffy in Fiordland National Park, situated in an understudied remote area of New Zealand’s Southern Alps. Employing a multiproxy approach, we utilized bulk C and N stable isotopes, lipid biomarker analysis, and high-resolution X-ray fluorescence and hyperspectral imaging to reconstruct Holocene changes in catchment dynamics and climate. Here, we present a new precipitation record based on the compound-specific composition of hydrogen isotopes of plant wax n-alkanes as well as a branched glycerol dialkyl glycerol tetraethers (brGDGTs) derived temperature reconstruction. Examining a sequence spanning the late Holocene, we discern events of evolving environmental conditions impacting these catchments.

Our biomarker paleorecord from Lake Bright revealed a relatively stable temperature range during the last 4 ka, indicating that the changes in the sedimentary record might be dominantly shaped by the local hydroclimate. The low compound δ2H values observed reflect precipitation that has been orographically uplifted over the Southern Alps. Downcore δ2H variations are likely influenced by changes in the isotopic composition of rainfall driven by regional temperature and latitudinal sources of westerly precipitation. In this context, we present these episodes of hydroclimatic variability and derive the ecosystem response to prevalent conditions by correlating the respective changes in lake productivity, water quality and shifts in vegetation composition.

Finally, we extend this record through the Holocene to the last local glacial termination about 10 ka ago using the Lake Laffy stratigraphy and engage in a discussion regarding the potential implications of enhanced climate variability on the future integrity of New Zealand's pristine alpine ecosystems.

How to cite: Eschenroeder, J., Moy, C. M., Naeher, S., Vandergoes, M. J., Rach, O., Sachse, D., Tjallingii, R., Saunders, K. M., Howarth, J. D., and Shepherd, C.: Unveiling Undisturbed Alpine Lake Ecosystems: A Multiproxy Approach to Reconstruct past Ecological Response to Climate Variability in the New Zealand Southern Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-854, https://doi.org/10.5194/egusphere-egu24-854, 2024.

EGU24-1524 | ECS | Orals | CL5.4

Robust land surface temperature record for north China over the past 21,000 years 

Jingjing Guo, Martin Ziegler, Niko Wanders, Mike Vreeken, Qiuzhen Yin, Hao Lu, Louise Fuchs, Jibao Dong, Youbin Sun, and Francien Peterse

Numerous proxy reconstructions have provided general insight into late Quaternary East Asian Monsoon variability. However, challenges persist in precisely assessing absolute temperature impacts on proxy variations. Here we employ two independent paleothermometers, based on bacterial membrane lipids and clumped isotopes of snail shells, in the same section of the western Chinese Loess Plateau to establish a robust land surface temperature record spanning the past ca. 21,000 years. Our independent temperature records consistently reveal similar land surface temperatures between the Last Glacial Maximum and late Holocene, and a gradual cooling Holocene which contrasts with the climate model predictions. We propose that changes in soil moisture availability over the deglaciation modulates the land surface temperature recorded by the proxies. A land surface energy partitioning model confirms this mechanism, suggesting that effects of soil moisture availability should be properly considered when comparing proxy records with climate model outputs.

How to cite: Guo, J., Ziegler, M., Wanders, N., Vreeken, M., Yin, Q., Lu, H., Fuchs, L., Dong, J., Sun, Y., and Peterse, F.: Robust land surface temperature record for north China over the past 21,000 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1524, https://doi.org/10.5194/egusphere-egu24-1524, 2024.

EGU24-5971 | ECS | Posters on site | CL5.4

A proxy system model framework for reconstructing past environmental conditions with cosmogenic noble gases 

Marissa M. Tremblay, Taylor Bourikas, Marie Bergelin, and Greg Balco

Cosmogenic isotopes of helium and neon are produced at the Earth’s surface and exhibit a wide range of thermal sensitivities in common minerals. We can take advantage of this range of thermal sensitivities to reconstruct past near surface thermal conditions using cosmogenic noble gas observations. For example, cosmogenic noble gases have been used to study past ambient temperatures, changes in snow cover duration, and wildfire histories. Interpreting cosmogenic noble gas observations requires a model of both production and diffusion that predicts cosmogenic noble gas concentrations for different thermal histories. Additionally, models that characterize the diffusion kinetics of helium or neon in a particular mineral sample are often needed, as laboratory-based diffusion experiments demonstrate that helium and neon diffusion kinetics are sample specific and often complex. At present, various codes are available that can carry out pieces of the modeling, but they are generally not interoperable and are often highly specific to a particular past application, limiting the codes’ use for future applications. Here we present progress on creating a general forward modeling framework for inferring thermal histories using cosmogenic noble gas observations, structured around the concept of proxy system modeling. We will describe the architecture of this model framework as well as provide examples of applying it to new and existing cosmogenic noble gas datasets.

How to cite: Tremblay, M. M., Bourikas, T., Bergelin, M., and Balco, G.: A proxy system model framework for reconstructing past environmental conditions with cosmogenic noble gases, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5971, https://doi.org/10.5194/egusphere-egu24-5971, 2024.

EGU24-6727 | Posters on site | CL5.4

High-resolution geochemical and petrographic study of a last glacial Cook Islands flowstone and the hydrological significance of calcite optical properties 

Andrea Borsato, Silvia Frisia, Daniel Sinclair, John Hellstrom, Russell Drysdale, and Mohammadali Faraji

The South Pacific Convergence Zone (SPCZ), the largest component of tropical circulation on our planet, extends diagonally across the South Pacific and its displacement controls rainfall variability and tropical cyclone activity. Speleothems that formed during the last glacial period in the Cook Islands offer the opportunity to investigate the strength and position of the SPCZ across both the last glacial termination, and during rapid climate fluctuations (e.g. the Dansgaard-Oeschger Events). We present a high-resolution, multiproxy study of an 80 cm-thick flowstone retrieved in Atiu (Southern Cook Islands) covering the period from 10 to 80 ka. Optical and fluorescence microscopy, synchrotron X-ray fluorescence mapping, stable isotope ratios and LA-ICP-MS trace elements analyses allowed us to characterise the geochemical and optical properties of different calcite fabrics and speleothem facies. The geochemical and textural properties of the flowstone are directly controlled by prior calcite precipitation (PCP), which caused large positive shifts in δ13C and δ18O values, and synchronous peaks in Mg concentration and other hydroclimate-sensitive elements. These rapid shifts are particularly marked between 35 and 45 ka and coincide with several Dansgaard-Oeschger events recorded by the Greenland Ice Cores. The positive shifts in δ13C and δ18O values and Mg concentration are commonly recorded within compact, translucent fabric characterized by low greyscale values. By contrast, shifts to more negative δ13C and δ18O values and low Mg concentrations are associated with a porous, open fabric with a high density of fluid inclusions and high greyscale values. This confirms previous findings from modern Atiuan stalagmites and cave-farmed calcite (Faraji et al., 2022, 2023), thus opening the possibility to utilise greyscale mapping and fabric logs as novel, high-resolution hydroclimate proxies.

References:  Faraji, M., Borsato, A., Frisia, S., Hartland A., Hellstrom, J. (2023). High-resolution and quantitative records of infiltration in the Southern Cook Islands based on multi-element stalagmite data. Quaternary Research, 1-21. https://doi.org/10.1017/qua.2023.51. Faraji, M., Borsato, A., Frisia, S., Mattey, D.P., Drysdale R.N., Verdon-Kidd, D.C., Malcolm, R., Marca, A. (2022). Controls on rainfall variability in the tropical South Pacific for the last 350 years reconstructed from oxygen isotopes in stalagmites from Cook Islands. Quaternary Science Reviews, 289, 107633.

How to cite: Borsato, A., Frisia, S., Sinclair, D., Hellstrom, J., Drysdale, R., and Faraji, M.: High-resolution geochemical and petrographic study of a last glacial Cook Islands flowstone and the hydrological significance of calcite optical properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6727, https://doi.org/10.5194/egusphere-egu24-6727, 2024.

EGU24-6742 | ECS | Posters on site | CL5.4

Insolation and ice volume induced extreme cooling events in East Asia during glacial times  

Hao Lu, Jingjing Guo, Louise Fuchs, Qiuzhen Yin, Youbin Sun, and Francien Peterse

Our current understanding of past changes in East Asian monsoon climate variability is largely based on loess-paleosol sequences and speleothem δ18O records. Although most records have provided insight on the strength of summer monsoon precipitation, past temperature variations over East Asia are so far relatively poorly understood. Here we quantitatively reconstruct a high-resolution land temperature for central China covering the past 250 kyr, based on soil bacterial lipid signatures, co-called branched glycerol dialkyl glycerol tetraethers (brGDGTs) preserved in a loess-paleosol sequence at Mangshan on the eastern Chinese Loess Plateau (CLP). We find that the brGDGT-based temperature is dominated by precession cycles (21 kyr), except during the last deglaciation when temperature change was mainly driven by obliquity due to low eccentricity, consistent with model outputs. Notably, our record provides first evidence of extreme cooling events during glacial times when summer insolation decreases to a critical value as predicted by model simulations. Furthermore, the degree of cyclization (DC) of brGDGTs, which is suggested to indicate moisture availability, also shows clear precession cycles but does not show extreme events in response to the critical low insolation values. Our results thus indicate that the warm season temperature and moisture are mainly forced by precession, and extreme cooling events could be triggered by low summer insolation during glacial times.

How to cite: Lu, H., Guo, J., Fuchs, L., Yin, Q., Sun, Y., and Peterse, F.: Insolation and ice volume induced extreme cooling events in East Asia during glacial times , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6742, https://doi.org/10.5194/egusphere-egu24-6742, 2024.

EGU24-9912 | ECS | Posters on site | CL5.4

Biogeochemical responses of lake Übeschi (Swiss Plateau) during Late-Glacial periods of rapid climate variations  

Noé R.M.M. Schmidhauser, Stan J. Schouten, Petra Zahajská, Andrea Lami, Petra Boltshauser-Kaltenrieder, Jaqueline F.N. van Leeuwen, Rick Tjallingii, Hendrick Vogel, and Martin Grosjean

The present-day rapid degradation of freshwater ecosystems worldwide, due to eutrophication and hypolimnetic anoxia, is primarily driven by human activities and climate change. A comprehensive understanding of these processes and their underlying mechanisms is essential. Traditionally, the study of these phenomena has been challenged by the limited availability of high-resolution sedimentary records and suitable proxies, particularly for past anoxia events. However, recent advancements in Hyperspectral Imaging (HI) techniques have opened up new avenues for examining variability in past lake biogeochemical cycles under changing redox conditions and related chemical feedbacks, providing insight into how freshwater ecosystems have responded to natural and anthropogenic perturbations. We investigate the responses of lake productivity, redox conditions and chemical feedbacks (P, Fe, Mn) during periods of rapid climate shifts (Dansgaard-Oeschger Events) under natural conditions in the past. Furthermore, we seek to reconstruct the lake's history prior to the Bølling warming (14.6 kBP) to gain insights into the lake ecology during initial stages of the lake formation in a cold-dry tundra environment during Heinrich Stadial 1 (HS1, Oldest Dryas). To answer these questions a kettle hole lake Übeschisee in the upper Swiss Plateau was studied. The lake is well suited for analyzing abrupt changes in the lake and in the lake catchment during the Late-Glacial since it formed after the retreat of the Aare glacier >18 kBP and offers a continuous sediment record since then. The biogeochemical composition of lake Übeschi sediments was acquired by X-ray fluorescence core scanning, HI, HPLC measurements of pigment extracts, and ICP-MS measurements of P, Mn and Fe sequential extractions. Bacteriopheophytin a produced by Purple Sulfur Bacteria (PSB) is used as a proxy for hypolimnetic anoxia. Our results show an increase in aquatic primary production already during HS1, i.e. long before the Bølling warming. Cyanobacteria were among the first photosynthetic organisms to colonize the young lake in a deglacial environment. Additionally, hypolimnetic anoxia events indicated by bacteriopheophytin a generally occurred during the cold periods of the Oldest Dryas, the Older Dryas and the Younger Dryas and not during the Bølling warming, as initially hypothesized. Apparently, these anoxia events are attributed to very long ice cover of the lake and a very short open period with strong lake stratification and a chemocline in the photic zone where PSB could grow. Finally, redox-sensitive fractions of Mn and Fe are mostly absent from the sediment during anoxic events, suggesting remobilization of these elements by reductive dissolution. This provides evidence for pre-anthropogenic chemical feedbacks and internal P loads under natural conditions.

How to cite: Schmidhauser, N. R. M. M., Schouten, S. J., Zahajská, P., Lami, A., Boltshauser-Kaltenrieder, P., van Leeuwen, J. F. N., Tjallingii, R., Vogel, H., and Grosjean, M.: Biogeochemical responses of lake Übeschi (Swiss Plateau) during Late-Glacial periods of rapid climate variations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9912, https://doi.org/10.5194/egusphere-egu24-9912, 2024.

EGU24-12108 | Posters on site | CL5.4

Stalagmites with ‘drip cups’ – are they suitable for palaeotemperature reconstructions? 

Sebastian F.M. Breitenbach, Jack Longman, Stuart Umbo, Sevasti Modestou, Ola Kwiecien, Stacy A. Carolin, Daniel H. James, Carlos Peraza Lope, Mark Brenner, and David Hodell

Stalagmites (carbonate deposits in caves) are excellent archives of palaeoenvironmental changes, as they are not only amenable to high-precision radiometric dating but host numerous proxy variables that reflect past changes in climate conditions related to hydrology, temperature, and atmospheric dynamics. In most stalagmites, the convex shape of the apex leads to rapid runoff of dripwater, which results in a thin film of water on top of the stalagmite, fast CO2 degassing, and depletion of the dissolved inorganic carbon (DIC) pool. These kinetic dynamics lead to carbon and oxygen isotope fractionation, hampering quantitative estimation of the carbonate formation temperature and reconstruction of original dripwater composition using, e.g., clumped isotope systematics (Affek et al. 2008; Affek & Zaazur 2014). Equilibrium conditions can be achieved however in subaqueously-formed speleothems (Daëron et al. 2019).

Whether stalagmites that possess a ‘drip cup’, i.e., a concave apex, show near-equilibrium conditions and constitute archives of past temperature should be testable using isochronous clumped isotope analyses. We hypothesized that the deeper water body inside the ‘drip cup’ limits CO2 degassing and DIC depletion, enabling near-equilibrium conditions compared to the outer slope of the rim wall surrounding the ‘drip cup’ that is likely affected by kinetic fractionation. We tested this hypothesis using multiple isochronous samples from stalagmite MAYA-22-7, taken at Cenote Ch’en Mul, Mayapán, Yucatán (México). The actively growing stalagmite was collected in 2022. Air temperature in the cave chamber is very stable, at 25.7 ± 0.6°C year-round. The stalagmite shows a prominent and several-mm-deep ‘drip cup’ in its lower growth section. U-series dating showed that this interval is ca. 500 years old. Very thin growth layers inside the ‘drip cup’ and thick growth layers at the rim wall indicate different growth conditions across the stalagmite at the time of formation, likely with suppressed DIC depletion and reduced kinetic isotope fractionation in the ‘drip cup.’ Δ47 values were predicted to be highest inside the drip cup (if kinetic isotope fractionation increases with distance from the apex) or to remain constant (if kinetic effects are negligible). We milled seven subsamples from growth layers of the same age for Δ47 analysis. Each sample integrates several years (< 10) because of the required sample mass (~ 4.5 mg). Clumped isotopes were measured at Northumbria University on a NU Instruments Perspective IRMS. We discuss the clumped isotope dynamics along a single growth interval and implications for palaeotemperature reconstructions. Finding near-equilibrium conditions inside the ‘drip cup’ would offer the opportunity to reconstruct past temperatures, if not continuously, then at least for some time intervals.

References

Affek, H.P., Bar-Matthews, M., Ayalon, A., Matthews, A., Eiler, J.M., 2008. Glacial/interglacial temperature variations in Soreq cave speleothems as recorded by ‘clumped isotope’ thermometry. Geochim. Cosmochim. Acta 72, 5351–5360

Affek, H.P., Zaarur, S., 2014. Kinetic isotope effect in CO2 degassing: insight from clumped and oxygen isotopes in laboratory precipitation experiments. Geochim. Cosmochim. Acta 143, 319–330

Daëron, M., Drysdale, R.N., Peral, M., Huyghe, D., Blamart, D., Coplen, T.B., Lartaud, F., Zanchetta, G., 2019. Most Earth-surface calcites precipitate out of isotopic equilibrium. Nature Comms. 10:429

How to cite: Breitenbach, S. F. M., Longman, J., Umbo, S., Modestou, S., Kwiecien, O., Carolin, S. A., James, D. H., Peraza Lope, C., Brenner, M., and Hodell, D.: Stalagmites with ‘drip cups’ – are they suitable for palaeotemperature reconstructions?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12108, https://doi.org/10.5194/egusphere-egu24-12108, 2024.

EGU24-13434 | Posters on site | CL5.4

Effects of prior calcite and prior aragonite precipitation on cave dripwater compositions 

Jasper A. Wassenburg, Anupam Samanta, Lijuan Sha, Hosun Lee, Denis Scholz, Hai Cheng, Yassine Ait Brahim, Alexander Budsky, and Sebastian F. M. Breitenbach

Cave monitoring programs have provided a wealth of information on processes that affect speleothem proxy systems such as stable isotopes and trace elements. Prior carbonate precipitation (PCarbP), i.e. the precipitation of a carbonate mineral from supersaturated water occurring in the epikarst or at the ceiling of the cave, is one of the dominant processes that controls the dripwater d13C, Mg/Ca, Sr/Ca, Ba/Ca as well as U/Ca. Enhanced PCarbP is associated with reduced infiltration or a decrease in CO2 partial pressures of the infiltrating water. Often this process can be linked to the precipitation - evaporation balance (P-E) or rainfall variability. The type of carbonate polymorph that precipitates, calcite or aragonite, determines how dripwater trace element to Ca (Me/Ca) ratios evolve as a consequence of PCarbP. This has led to distinguish prior calcite precipitation (PCP) from prior aragonite precipitation (PAP) since calcite trace element partitioning coefficients (DMe) differ from aragonite DMe. Determining accurate calcite and aragonite DMefor Mg, Sr, Ba, and U is crucial to identify the PCarbP mode (i.e., PCP or PAP) and increase our confidence in interpreting speleothem trace element variability.

Using an autosampler we were able to collect dripwater samples from Grotte de Piste, Morocco at unprecedented 4-day resolution covering the transition from the wet winter to the dry summer season. The drip site has high drip rates during the wet winter but progressively dries out during summer. We observe a strong significant positive correlation between dripwater Ca concentrations and drip rate (r=0.996, p<0.01) indicating that PCarbP is the dominant process affecting dripwater Ca concentrations. By studying the evolution of dripwater Ca and trace element concentrations we show that a single drip site can be affected by both PCP as well as PAP. From the dripwater element compositions we determine new aragonite DMe values. As opposed to DMg, DSr and DU, it appears that aragonite DBa is very similar to calcite DBa. Barium thus seems least sensitive to mineral phase changes associated with PCCarbP compared to Mg, Sr, U. However, calcite or aragonite DMe values should not be considered constants and may vary with solution composition, dripwater saturation index and temperature. Aragonite DBa for example increases with dripwater saturation index. It is therefore possible that DBa might differ within the epikarst as compared to the cave ceiling or the speleothem surface unless the dripwater saturation index remains low at the speleothem surface. Barium concentrations in aragonite speleothems with low growth rates may be most suitable to trace combined PCP and PAP variations as they precipitate from dripwater with a low saturation index.

How to cite: Wassenburg, J. A., Samanta, A., Sha, L., Lee, H., Scholz, D., Cheng, H., Ait Brahim, Y., Budsky, A., and Breitenbach, S. F. M.: Effects of prior calcite and prior aragonite precipitation on cave dripwater compositions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13434, https://doi.org/10.5194/egusphere-egu24-13434, 2024.

EGU24-13463 | ECS | Posters on site | CL5.4

Improved analysis of polycyclic aromatic hydrocarbons (PAHs) in speleothems 

Johanna Schäfer, Christoph Spötl, and Thorsten Hoffmann

Speleothems are valuable paleoenvironmental archives that can grow continuously over thousands of years and are particularly favorable due to reliable dating using the 230Th/U-method. As the caves in which these mineral deposits are formed are largely closed systems and the speleothems resist chemical alteration, it is possible to analyse organic substances in addition to established proxies such as stable isotopes and trace elements. [1] The analysis of organic markers has only recently come into focus but shows promising results for the reconstruction of past climatic conditions, especially regarding vegetation changes and paleofires.  [2]

Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous organic compounds consisting of one or more fused aromatic rings. They are formed, for example, during the incomplete combustion of biomass and enter caves with the infiltrating water, where they are incorporated into speleothems. [3] Alongside other proxies such as levoglucosan (combustion product of cellulose), they can provide information about past vegetation and fire activity.

As only a small fraction of PAHs reaches the speleothems, suitable sample preparation methods are required to maximize the amount of analyte while keeping the required amount of sample low. We present a rapid and easy extraction method using an ultrasonic bath and the addition of keepers to reduce the loss of low molecular weight PAHs like naphthalene during the evaporation process.

The developed method, as well as a new and fast GC-HRMS method, was applied to a particularly old flowstone from the Conturines Cave in northern Italy, dating back to the Pliocene. 

[1] A. Blyth et al. Quat. Sci. Rev. 149 (2016) 1-17. [2] J. Homann et al. Biogeosciences. 20 (2023) 3249–3260. [3] Y.Sun et al. Chemosphere 230 (2019) 616–627.

How to cite: Schäfer, J., Spötl, C., and Hoffmann, T.: Improved analysis of polycyclic aromatic hydrocarbons (PAHs) in speleothems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13463, https://doi.org/10.5194/egusphere-egu24-13463, 2024.

EGU24-14491 | Orals | CL5.4

Speleothems as archives for terrestrial dissolved organic carbon export – a radiocarbon perspective 

Franziska Lechleitner, Sarah Rowan, Gang Xue, Giulia Guidobaldi, and Tim Huber

Terrestrial ecosystems are one of the Earth's largest active carbon reservoirs and hold three times more carbon than the atmosphere. However, their sensitivity and response to global climate change remain debated and may be dependent on multiple processes acting on different spatial and temporal scales.

Speleothems, secondary cave carbonate deposits, offer a unique, but under-exploited opportunity to reconstruct the export of dissolved carbon species at the local to regional scale. In this context, radiocarbon is the proxy of choice to unveil the dynamics of the carbon cycle, as it can give information on reservoir turnover times and mixing ratios between different carbon sources. We use an approach consisting in the extraction and isotopic analysis (14C and δ13C) of non-purgeable organic carbon extracts from speleothems, which gives us insight into dissolved organic carbon (DOC) export from the surface. Such observations, especially over periods of rapid climate change exceeding present-day variability, could be invaluable to better constrain the sensitivity of carbon export fluxes to environmental and climatic changes.

In this contribution, we will review the progress our group has made over the past years in methodological advances that allow us to develop reproducible and precise DOC reconstructions based on trace amounts of organic matter incorporated in speleothems. We show that, while strongly driven by local conditions, speleothems do retain information on the dynamics and export of DOC from the terrestrial biosphere, and discuss best steps and practices to achieve reliable results.

How to cite: Lechleitner, F., Rowan, S., Xue, G., Guidobaldi, G., and Huber, T.: Speleothems as archives for terrestrial dissolved organic carbon export – a radiocarbon perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14491, https://doi.org/10.5194/egusphere-egu24-14491, 2024.

EGU24-17844 | Orals | CL5.4

A Bayesian approach to reconstructing quantitative climate using geochemical lake sediment data  

Laura Boyall, Paul Lincoln, Andrew Parnell, and Celia Martin-Puertas

Palaeoclimate reconstructions from proxy data provides the opportunity to extend the instrumental climate record over the last few millennia. This extension allows the identification of climate trends which are not observed in the short observational period, contextualise current changes in the climate system, and be used in climate model sensitivity tests to strengthen future projections. The skill in reconstructing accurate palaeoclimate on centennial to millennial timescales using proxy data has increased over the past decades, however reconstructions at high temporal resolutions (1 to 10 years) are limited. This is mostly due to the sampling resolution of available proxy records and/or uncertain chronologies. Micro X-ray Fluorescence (m-XRF) core scanning data provides multivariate information about the changing geochemical composition of a sediment sequence. When combined with a tightly resolved chronology, such as one from a varved sediment sequence, m-XRF data can be used as a proxy for past changing environmental and climate conditions at an annual to sub-annual timescale. However, despite this, the reconstructions are only semi-quantitative and therefore only used to assess relative changes in climate and environmental variability.

We have developed a novel approach which transforms XRF core scanning data into a quantified climate reconstruction using a Bayesian statistical approach. This method uses a calibration period measuring the relationship between the different geochemical elements and a climate parameter, as well as measuring the covariance and non-linear responses between the different geochemical elements. This learnt statistical relationship is then applied on the proxy data through time with quantified uncertainties calculated at each timestep.

We present the simplification of this approach in a user-friendly R package (SCUBIDO, Simulating Climate Using Bayesian Inference with Proxy Data Observations) which provides functions for the stages of model calibration, application, and validation. We demonstrate this approach using the annually laminated lake sediments of Diss Mere (UK) to reconstruct annual mean temperature for the past 10,000 years. The temperature reconstruction reveals good consistency from the proxy data to the TraCE-21k transient climate simulation, and other palaeoclimate reconstructions from the surrounding region.

How to cite: Boyall, L., Lincoln, P., Parnell, A., and Martin-Puertas, C.: A Bayesian approach to reconstructing quantitative climate using geochemical lake sediment data , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17844, https://doi.org/10.5194/egusphere-egu24-17844, 2024.

EGU24-17926 | ECS | Posters on site | CL5.4

Assessing the potential of bacterial and archaeal membrane lipids (GDGTs) to reconstruct Late Pleistocene and Holocene climatic changes in the Canary Islands 

Nina Davtian, Alvaro Castilla-Beltrán, María del Pilar Martín Ramos, Enrique Fernández-Palacios, Constantino Criado, Sandra Nogué, Joan Villanueva, José María Fernández-Palacios, and Lea de Nascimento

Sedimentary records covering the Late Pleistocene show glacial-interglacial and millennial temperature changes accompanied with, for instance, rainfall and vegetation changes at the global and regional scales. However, such records are missing for the islands of Macaronesia.

Here we generate three sedimentary records over the last 10,000 to 45,000 years from the islands of Tenerife, Gran Canaria, and La Gomera using glycerol dialkyl glycerol tetraethers (GDGTs). At the global scale, air temperature and soil pH influence GDGT distributions in soils, although these biomarkers also react to other environmental factors (e.g., land use, vegetation, and soil moisture and chemistry) and shifts in bacterial and archaeal communities. Accordingly, we examined several GDGT-based proxies, notably those using bacterial branched GDGTs (brGDGTs), to assess their applicability in the Canary Islands.

Our preliminary results show drastic downcore and inter-site changes in GDGT distributions, with brGDGT-based air temperature ranges larger than 10 °C over the last 10,000 to 45,000 years when applying global calibrations at the three study sites. Air temperatures and soil pH inferred from brGDGTs decrease in Tenerife and La Gomera over the end of the African Humid Period, which suggests an effect of reduced rainfall on brGDGTs, possibly accompanied with a shift in bacterial communities. Air temperatures inferred from brGDGTs show a general increase over the last 27,000 years in Gran Canaria, whereas cyclization and isomerization indices of brGDGTs suggest typically opposite changes in soil pH, in disagreement with global-scale patterns from surficial soils. Our GDGT-based records also show a few drastic increases in archaeal GDGT abundances relative to the full GDGT pool after the Last Glacial Maximum, notably in Gran Canaria and La Gomera, partly related to the rainfall increase during the African Humid Period.

Our preliminary application of GDGT-based proxies in the Canary Islands reveals complex environmental influences on soil bacterial and archaeal lipids, which may also be related with local climate and vegetation dynamics. Our preliminary study also motivates a follow-up GDGT study in surficial soils from the Canary Islands to establish, for instance, a brGDGT-temperature calibration suitable for this archipelago.

How to cite: Davtian, N., Castilla-Beltrán, A., Martín Ramos, M. P., Fernández-Palacios, E., Criado, C., Nogué, S., Villanueva, J., Fernández-Palacios, J. M., and de Nascimento, L.: Assessing the potential of bacterial and archaeal membrane lipids (GDGTs) to reconstruct Late Pleistocene and Holocene climatic changes in the Canary Islands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17926, https://doi.org/10.5194/egusphere-egu24-17926, 2024.

EGU24-18355 | ECS | Orals | CL5.4

Disentangling seasonal and annual precipitation signals in the tropics over the Holocene: insights from δD, alkanes and GDGTs 

Petter Hällberg, Malin Kylander, Frederik Schenk, Joan Villanueva, Nina Davtian, Anggi Hapsari, Jenny Sjöström, Guillermo Jarne-Bueno, Kweku Yamoah, Hamdi Rifai, and Rienk Smittenberg

Tropical Asia is a critical component of the global climate system as it provides large amounts of moisture and heat to the extratropics and drives monsoons on both hemispheres. Paleoclimate information remains relatively scarce from the region despite its global significance, calling for additional records from the region. We generated a multiproxy peat record from Sumatra, with a focus on deconvolving seasonal and annual precipitation signals, as well as long term temperature variability. We do this by analyzing the n-alkane distributions reflecting vegetation variability, and the hydrogen isotopic composition (δDalkanes) from alkanes sourced from algae and terrestrial plants. Algae grows during the wet season, while terrestrial plants grow over the whole year, and they therefore reflect the water isotopic signal from different parts of the year. We further analyze the GDGT composition in the peat core to derive information about temperature and hydrological changes. Finally, levoglucosan was measured to reconstruct past wildfire events.

We find that the climate on Sumatra was much more seasonal in the Mid-Holocene than in the Late Holocene, based on the difference between δDterrestrial and δDalgae. In particular, the period between 4-6 ka BP was extremely seasonal, with alternating floods, droughts and fires. This extreme seasonality is coeval with an Asian Summer Monsoon collapse, Australian Summer Monsoon invigoration and the collapse of Green Sahara, suggesting large scale tropical atmospheric reorganization in that period.

Our multiproxy annual precipitation reconstruction indicates the wettest overall conditions between 3.3-4.5 ka BP. which is approximately 1500-2000 years later than indicated by a nearby speleothem δ18O record, which instead is more similar to δDalgae. We therefore hypothesize that speleothem reconstructions in the region record a wet season isotopic signal, similar to the algae, since cave groundwater recharge occur mainly after heavy precipitation. The Late Holocene is marked by rapid drying around 2.8 ka BP, under a much less seasonal climate, which is coeval with the strengthening of ENSO variability in the Pacific Ocean.

In summary, our multiproxy peat record from Sumatra resolves the seasonal versus annual components of past rainfall variability, revealing heightened seasonality during the Mid-Holocene, significant shifts in precipitation pattern, and a notable Late Holocene drying trend. Our findings highlight the importance of considering the δD signal from the full range of alkanes and considering seasonal variability in paleoclimatological reconstructions.

How to cite: Hällberg, P., Kylander, M., Schenk, F., Villanueva, J., Davtian, N., Hapsari, A., Sjöström, J., Jarne-Bueno, G., Yamoah, K., Rifai, H., and Smittenberg, R.: Disentangling seasonal and annual precipitation signals in the tropics over the Holocene: insights from δD, alkanes and GDGTs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18355, https://doi.org/10.5194/egusphere-egu24-18355, 2024.

EGU24-18511 | ECS | Orals | CL5.4

Echoes of change: deciphering environmental history through biomarkers investigation in sediment core from a Central Himalayan Lake 

Ankit Yadav, Ambili Anoop, Praveen Kumar Mishra, Aljasil Chirakkal, and Elisabeth Dietze

The dynamics and scale of anthropogenically induced environmental changes in the Indian Himalayas remain largely unexplored, presenting a complex and enigmatic challenge. To tackle this, we investigated the pollution, eutrophication and fire history of the last century by analyzing the concentration, compositional variation, and temporal trends in polycyclic aromatic hydrocarbons (PAHs), monosaccharide anhydrides, fecal biomarkers and other aliphatic hydrocarbons (n-alkanes, acyclic isoprenoids and botryococcenes) from a lake sediment core in the Central Himalayas at 2084 m asl. The study revealed that the concentration of total PAHs increased steadily with a compositional change after 1970, paralleling an increase in socio-economic activities in the region. The PAHs diagnostic ratios revealed that pyrogenic sources accounted for the majority of the sedimentary PAHs and the high correlation between PAHs and fecal stanols (r = 0.84, p < 0.05) indicated the active role of humans in the catchment. The total concentrations of botryococcenes (C31-34) and n-alkanes showed an increasing trend in eutrophication with greatest values recorded during the 1980s, coinciding with a compositional change between long (nC26-36), mid (nC21-25) and short chain (<nC21) n-alkanes, depicting concurrent environmental change.

Moreover, based on the toxic equivalency factor of PAHs relative to benzo(a)pyrene and sediment quality guidelines (Canadian Council of Ministers of the Environment 2010), an increase in sediment toxicity was observed, surpassing thresholds for aquatic life protection, posing potential risks to both the lake ecosystem and human health.

The presence of monosaccharide anhydrides in the sediment core suggests a link to regional forest fires. These fires potentially contribute to the observed eutrophication, altering the lacustrine environment significantly. This hypothesis, if validated, could provide critical insights into the intertwined effects of wildfires and anthropogenic activities on lacustrine ecosystems. As the inaugural study of its kind from the Indian subcontinent, this research is pivotal in interpreting molecular signals in lacustrine records from this region.

How to cite: Yadav, A., Anoop, A., Mishra, P. K., Chirakkal, A., and Dietze, E.: Echoes of change: deciphering environmental history through biomarkers investigation in sediment core from a Central Himalayan Lake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18511, https://doi.org/10.5194/egusphere-egu24-18511, 2024.

EGU24-18601 | ECS | Posters on site | CL5.4

A novel proxy approach to constraining atmospheric modes in central and southwestern Iran during Marine Isotope Stage 3 

Mojgan Soleimani, Jonathan Baker, Alireza Nadimi, Yuri Dublyansky, Gabriella Koltai, and Christoph Spötl

Terrestrial paleoclimate records from arid southwestern Asia are relatively sparse. Therefore, the regional impact of abrupt glacial climate variability remains poorly constrained for much of the Western Asia, particularly winter (wet season) dynamics during Marine Isotope Stage 3. Here, we present the first paleoclimate reconstructions of Southwestern and Central Iran, which span the interval ~50-30 ka, based on speleothem δ18O and δ13C. Stable-isotope signals in the two stalagmites are generally uncorrelated and do not exhibit a consistent response to Greenland stadials or interstadials; however, both show a positive δ18O excursion that coincides with Heinrich event 4. This behavior contrasts with that observed in northern Iran, Anatolia, and Levant for the last glacial period. We explore the potential mechanisms for intermittent coupling of speleothem δ18O across Iran through isotope-enabled atmospheric modelling outputs, from which we utilize the spatial δ18O gradient as a proxy for wintertime westerly vs. southerly jet strength. Our results suggest that during Heinrich event 4 and several Greenland stadials, stronger westerly winds enhanced Mediterranean moisture contributions to both sites and reduced aridity in southern Iran. We emphasize the importance of analyzing spatial trends in speleothem δ18O to interpret atmospheric dynamics, rather than relying on time series from single sites.

How to cite: Soleimani, M., Baker, J., Nadimi, A., Dublyansky, Y., Koltai, G., and Spötl, C.: A novel proxy approach to constraining atmospheric modes in central and southwestern Iran during Marine Isotope Stage 3, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18601, https://doi.org/10.5194/egusphere-egu24-18601, 2024.

EGU24-18659 | ECS | Posters on site | CL5.4

Comparison of Historical and Speleothem (Paleo)climate Records from Northwest Yucatán (Mexico) 

Aviva Intveld, Sebastian F.M. Breitenbach, Stacy A. Carolin, Daniel H. James, Ola Kwiecien, Mark Brenner, Carlos Peraza Lope, and David A. Hodell

Paleoclimate studies on the Yucatán Peninsula, Mexico, are important for understanding relationships between past climate change and ancient Maya cultural evolution. The Postclassic Maya capital of Mayapán is a site of interest for such studies,  given that evidence of repeated drought conditions corresponded to times of violent conflict, from ~1400 to 1450 CE (Kennett et al., 2022), just before site abandonment in ~1450 and prior to the protracted Spanish conquest of the Yucatán region from 1527 to 1697 CE. As part of further efforts to identify past droughts in northwest Yucatán, we studied a new stalagmite from Cenote Ch’en Mul, located directly beneath the archaeological site of Mayapán. The upper 120 mm section of stalagmite MAYA-22-7 is chronologically constrained by five uranium-series dates between 1618 ± 23 (2σ) and 2001 ± 11, and grew at a near-constant rate of 0.3 mm/yr. Stable isotopes (ẟ18O and ẟ13C) of calcite were measured every 0.1 mm along the upper section growth axis and compared with Colonial-period records of known droughts, famines, and population declines (Hoggarth et al., 2017). 

The ẟ18O and ẟ13C records capture abrupt increases (1-2 ‰ above baseline), coincident (±5 years) with some of the historical records of extreme drought. One notable example includes ẟ18O values 1.0 ‰ above baseline from 1767 to 1770 CE, indicative of an extended dry period contemporaneous with the “Great Famine” of 1765 to 1773. That dry interval is described in historic records as having been characterized by drought, locusts, famine, widespread epidemics, and mortality, which caused a 39 % population reduction (Hoggarth et al., 2017). Evidence for severe drought is replicated for the interval 1765-1768 in a nearby speleothem record from Belize (Kennett et al., 2012). Furthermore, ẟ13C values demonstrate distinct 2 ‰ shifts, from -10 to -8 ‰, and frequent (3-5 year) repeated oscillations, indicating a strong, rapid response of the overlying ecosystem’s carbon budget to climate variability, perhaps related to the El Niño/Southern Oscillation (ENSO). Ultimately, in combination with other local and regional paleoclimate records, study of MAYA-22-7 will help assess the reliability of stalagmite records to capture historic droughts with high temporal accuracy, document patterns of climate variability (e.g., ENSO-related changes), and track land-use change across cultural transitions, while contributing to our understanding of human-climate-environment interactions in the Maya Lowlands.

How to cite: Intveld, A., Breitenbach, S. F. M., Carolin, S. A., James, D. H., Kwiecien, O., Brenner, M., Peraza Lope, C., and Hodell, D. A.: Comparison of Historical and Speleothem (Paleo)climate Records from Northwest Yucatán (Mexico), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18659, https://doi.org/10.5194/egusphere-egu24-18659, 2024.

EGU24-19305 | Orals | CL5.4

Tools to unlock Palaeogene climate records from high-latitude coal seams 

Maria Ansine Jensen, Jochmann Malte, Chris Marshall, Mads Jelby, David Large, Carlette Blok, Anne Hope Jahren, Rhodri Jerrett, and Hamed Sanei

Terrestrial palaeoclimate records are generally challenging to obtain due to the dynamic changes of landscapes, and ubiquitous erosion on land. Deep-time palaeoclimate proxies are typically retrieved from marine sedimentary records of calm depositional environments; these, however, do not capture the land surface-atmosphere interaction, which forms a crucial component of the global carbon exchange. This is particularly true when using palaeoclimate analogues for the future climate state, where land surface temperature, hydrology and vegetation interaction will have direct impact on land surface conditions.

 

The Palaeocene Firkanten Formation on Svalbard, Arctic Norway, holds up to 5 m thick coal seams, representing extensive peatlands in a Boreal climate, at c. 75 degrees N palaeolatitude. Deposition in the high Arctic in a high atmospheric CO2 hyperthermal world, makes this record a highly relevant analogue for the currently rapidly warming Arctic. Undisturbed coal samples from three different coal mines provide a high-resolution archive of C-isotopes, inorganic dust, pollen and coal macerals. In the Svalbard Warm Arctic Palaeoclimate (SWAP) field laboratory we are testing dC13 as a proxy for water stress in the peatland and comparing the potential palaeohydrology proxy to XRF data of inorganic particles as proxies for wind distribution and/or dry/wet conditions. Currently, our samples comprise the dC13 record, preliminary pollen analyses, XRF of inorganic particles, whereas future work will target coal macerals as indicators for the temperature of forest fires, and comparison with carbon exchange in modern Arctic records. We will discuss the robustness of these proxies for the deep-time peat record, and the implications for future climate models for the Arctic land surface in a warming world.

 

How to cite: Jensen, M. A., Malte, J., Marshall, C., Jelby, M., Large, D., Blok, C., Jahren, A. H., Jerrett, R., and Sanei, H.: Tools to unlock Palaeogene climate records from high-latitude coal seams, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19305, https://doi.org/10.5194/egusphere-egu24-19305, 2024.

EGU24-20035 | ECS | Posters on site | CL5.4

Utility of foraminifera environmental DNA as proxies in relative sea-level reconstructions from Northern Norway 

Wenshu Yap, Fangyi Tan, Tanghua Li, Nicole Khan, Max Holthuis, Chantel Nixon, and Benjamin Horton

Foraminifera are commonly applied in saltmarsh and mangrove reconstructions of relative sea level (RSL) due to their distinct vertical zonation with respect to tidal elevation. The success of this approach relies on deriving accurate foraminifera counts that are representative of the true foraminifera assemblage. However, traditional counts using the microscope can be time consuming, and taphonomic processes may lead to poor preservation of foraminifera tests, hindering identification. This study explores a novel approach that compares traditional foraminifera analyses with environmental DNA (eDNA) metabarcoding to assess the utility of foraminifera eDNA as proxies to reconstruct past RSL.

We collected paired samples for traditional foraminifera counts and eDNA metabarcoding from an Arctic saltmarsh near the community of Kongsfjord in Finnmark, northern Norway. Samples were collected along a transect across the modern saltmarsh surface and at successive depths within the fossil saltmarsh sequence. Our metabarcoding targets the 18S rRNA gene’s variable region 37f that are specific to foraminifera. Preliminary findings reveal differences between the foraminifera assemblage determined using traditional microscope methods versus foraminifera metabarcoding, with certain species of foraminifera that were uniquely identified with the eDNA approach. This study demonstrates the utility of foraminifera metabarcoding to complement traditional morphology-based counts and paves the way for wider application of foraminifera metabarcoding in palaeoenvironmental research.

How to cite: Yap, W., Tan, F., Li, T., Khan, N., Holthuis, M., Nixon, C., and Horton, B.: Utility of foraminifera environmental DNA as proxies in relative sea-level reconstructions from Northern Norway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20035, https://doi.org/10.5194/egusphere-egu24-20035, 2024.

EGU24-28 | Orals | CL5.5 | Highlight

Climate model Selection by Independence, Performance, and Spread (ClimSIPS) 

Anna Merrifield, Lukas Brunner, Ruth Lorenz, Vincent Humphrey, and Reto Knutti

As the number of models in Coupled Model Intercomparison Project (CMIP) archives increase from generation to generation, there is a pressing need for guidance on how to interpret and best use the abundance of newly available climate information. Users of the latest CMIP6 seeking to draw conclusions about model agreement must contend with an "ensemble of opportunity" containing similar models that appear under different names. Those who used the previous CMIP5 as a basis for downstream applications must filter through hundreds of new CMIP6 simulations to find several best suited to their region, season, and climate horizon of interest. Here, we present methods to address both issues, model dependence and model subselection, to help users previously anchored in CMIP5 to navigate CMIP6 and multi-model ensembles in general. We refine a definition of model dependence based on climate output to designate discrete model families within CMIP5/6. We show that the increased presence of model families in CMIP6 bolsters the upper mode of the ensemble's bimodal effective Equilibrium Climate Sensitivity (ECS) distribution. Accounting for the mismatch in representation between model families and individual model runs shifts the CMIP6 ECS median and 75th percentile down by 0.43˚C, achieving better alignment with CMIP5's ECS distribution.

 Subsequently, we present a new cost-function minimization-based approach to model subselection, Climate model Selection by Independence, Performance, and Spread (ClimSIPS). We demonstrate ClimSIPS by selecting sets of 2, 3, and 5 CMIP models for European applications, incorporating the new dependence definition along with a performance metric based on agreement with observed mean climate fields and the ensemble spread of projected midcentury change in mean surface air temperature and precipitation. Because different combinations of models are selected by the cost function for different independence, performance, and spread priority balances, we present all selected subsets in ternary contour "subselection triangles". ClimSIPS represents a novel framework to select models in an informed, efficient, and transparent manner and addresses the growing need for guidance and simple tools so those seeking climate services can navigate the increasingly complex CMIP landscape.

How to cite: Merrifield, A., Brunner, L., Lorenz, R., Humphrey, V., and Knutti, R.: Climate model Selection by Independence, Performance, and Spread (ClimSIPS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-28, https://doi.org/10.5194/egusphere-egu24-28, 2024.

EGU24-324 | Posters on site | CL5.5

Convection permitting regional climate modelling with RegCM5 over the Carpathian Region 

Csaba Zsolt Torma and Filippo Giorgi

This study presents a preliminary analysis of the performance of the latest version of the RegCM regional modelling system, RegCM5, when run at a convection permitting resolution of 2 km over the Carpathian Basin. The performance of the model is evaluated by comparing various statistics of surface air temperature and precipitation against the CARPATCLIM high-resolution observational dataset and the ERA5 reanalysis, which is also utilized as the driving field for the simulations. Overall, the model performs well; however, certain biases are observed. During the warm season (JJA), a warm bias is detected over the Hungarian lowlands, while a wet (dry) bias is observed over the mountain chains (flat regions) within the basin. In addition, the model shows a significant orographic forcing effect on precipitation. An important finding is that the high-resolution of the model notably improves its ability to simulate medium to high-intensity precipitation events. This added value enhances its applicability, especially for the studies of such events. Given these promising initial results, future work will include further testing of the model with different physics configurations, longer simulations, and exploring its usability in climate change studies related to the Carpathian Basin.

How to cite: Torma, C. Z. and Giorgi, F.: Convection permitting regional climate modelling with RegCM5 over the Carpathian Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-324, https://doi.org/10.5194/egusphere-egu24-324, 2024.

EGU24-581 | ECS | Posters on site | CL5.5

Integrated Assessment of Climate Change and Land Use Impact on Runoff Dynamics in the Jhelum Basin 

Shahid Ul Islam and Sumedha Chakma

This study addresses the significant factors contributing to warming during the 20th century, namely Greenhouse Gases (GHG) and Land Use (LU), emphasizing the need for localized hydrological impact assessments. Recognizing the limitations of Global Climate Models (GCMs) in predicting local-scale phenomena, the research employs a downscaling approach for hydrological impact studies. Observed datasets and downscaled GCM data are utilized to analyze temperature, precipitation, and potential evapotranspiration (PET) trends. The study integrates downscaled GCM data from the Coupled Model Inter-comparison Project 6 (CMIP6) to project future climate scenarios under Representative Concentration Pathways (RCPs) 4.5 and 8.5. Runoff data from three stations within the Jhelum Basin is collected and analyzed over various time scales, providing a comprehensive understanding of historical and future hydrological trends. Future climate projections are corrected using the Daily Bias Correction (DBC) method). The study then employs the Soil & Water Assessment Tool (SWAT) model, given its suitability for hydrological studies with limited data availability. SWAT is calibrated and validated using SWAT CUP, incorporating observed river discharge. The impact assessment on runoff considers different climate change and land use change scenarios. Future Land Use and Land Cover (LULC) predictions are made for 2025 to 2100, and the model is rerun to analyze the combined impact of changing climate and LULC on runoff. The study aims to achieve a robust understanding of future water resource dynamics for runoff generation; the integrated assessment of climate and land use impact on the hydrological dynamics of the Jhelum Basin uncovers substantial shifts in runoff patterns. The combination of changing climate conditions and evolving Land Use/Land Cover (LULC) scenarios reveals intricate interactions, influencing the basin's hydrological response. Future projections highlight the nuanced interplay between climate scenarios and LULC changes, offering valuable insights into the complex dynamics of water resource management. These results provide essential information for policymakers and decision-makers, guiding the formulation of adaptive strategies to address the evolving challenges in runoff generation within the Jhelum Basin. The research explores runoff responses to LULC and climate change through scenario-based setups. By quantitatively analyzing the effects on runoff and peak discharge across different periods, the study provides valuable insights for policymakers and decision-makers in water resources. This integrated assessment contributes to a more informed and sustainable approach to water resource management in the Jhelum Basin amidst changing climatic and land use conditions.

How to cite: Islam, S. U. and Chakma, S.: Integrated Assessment of Climate Change and Land Use Impact on Runoff Dynamics in the Jhelum Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-581, https://doi.org/10.5194/egusphere-egu24-581, 2024.

EGU24-663 | ECS | Posters on site | CL5.5

The effect of different calibration periods based on bias-adjusted EURO-CORDEX simulations over Hungary 

Csilla Simon, Csaba Zsolt Torma, and Anna Kis

As a result of technological progress, general circulation models and regional climate models (GCMs and RCMs, respectively) became the principal tools for climate science. It is important to note, that these model simulations are encumbered with uncertainty of various origins, leading to biases in model outputs. By using bias-adjusted datasets and evaluating several RCMs together as members of an ensemble, the above-mentioned uncertainties can be quantified and reduced. In addition, unbiased data is required for impact studies (e.g. hydrology, agriculture) and the implementation of a bias-correction procedure has become a standard step in the process of using climate model outputs. However, a reliable observational dataset is required serving as reference data for all bias-adjustment methods.

Coordinated Regional Downscaling Experiments (CORDEX) is an ongoing international initiative which provides a large number of climate model simulations for 14 domains worldwide. EURO-CORDEX is a sub-programme of CORDEX, covering the European domain and providing raw and bias-adjusted RCM outputs at a horizontal resolution of 0.11° (about 12.5 km) and 0.44° (about 50 km). In our study an ensemble of 5 RCMs (CCLM, HIRHAM, RACMO, RCA, REMO) with the finer resolution driven by 4 different GCMs are investigated for the period 1976–2099 under two radiative forcing scenarios (RCP4.5 and RCP8.5). Bias-corrected model simulations are also available from the EURO-CORDEX, which were produced using a distribution-based scaling method and the calibration period of 1989–2010 from the MESAN reanalysis data.

The goal of our research is to investigate how the choice of the reference dataset and different calibration periods affects the results of the bias-corrected simulations focusing on Hungary. For this purpose, a bias-adjustment was carried out by applying the percentile-based quantile mapping method, using the HuClim dataset as a reference, which is the most accurate, measurement-based, quality controlled gridded data for Hungary currently available for the period 1971–2022. Two calibration periods were chosen for this procedure: an earlier (1976–2005) and a more recent (1993–2022) period. Four variables are used for this study (daily minimum- and maximum temperature, mean temperature and precipitation) and the following climate indices are assessed: summer days, frost days, tropical nights, wet days, the warmest day, the coldest night, the highest daily precipitation amount and extremely wet days. The validation of the data is presented here for the selected validation period 1993–2005, which is the common part of the three different calibration periods.

According to our preliminary results, the accuracy of the bias-corrected simulations depends on the chosen calibration period and the selected climate index. The average annual number of tropical nights are overestimated by bias-adjusted simulations using MESAN and the later HuClim period, but simulations corrected by the earlier HuClim period are in a good agreement with the reference values. In the case of precipitation-related indices negligible differences can be seen for the two sets of HuClim-based bias-adjusted model outputs, while the bias-adjusted data based on the MESAN dataset generally show more pronounced underestimation.

How to cite: Simon, C., Torma, C. Z., and Kis, A.: The effect of different calibration periods based on bias-adjusted EURO-CORDEX simulations over Hungary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-663, https://doi.org/10.5194/egusphere-egu24-663, 2024.

EGU24-1884 | Orals | CL5.5

GCM Selection & Ensemble Design: Best Practices and Recommendations from the EURO-CORDEX Community 

Stefan Sobolowski and the EURO-CORDEX CMIP6 GCM Selection & Ensemble Task Team

High resolution climate information is critical for the research community and the downstream vulnerability, impacts, adaptation, and climate services communities (VIACS). Coordinated ensembles generated by initiatives such as the World Climate Reseaerch Program's Coodinated Regional Downscaling Experiments (CORDEX) provide consistent and comparable information for the present as well as future scenarios. CORDEX is the initiative responsible for delivering regional climate data over fourteen different domains encompassing all land areas of the globe. And its output forms the basis for downstreams impacts assessments, adaptation planning and climate services development. This talk will focus on the European CORDEX initiative (hereafter EURO-CORDEX), an established framework of European regional climate modelers, and its coordinated effort to build regional climate ensembles for the years to come. In its first phase (2014 until now), EURO-CORDEX produced a rich ensemble of regional climate simulations under different representative concentration pathway scenarios. The EURO-CORDEX dataset is hosted in global and European databases and fed into the Regional Atlas of 6th IPCC Assessment Report. However, this ensemble and others like it suffered from several shortcomings, which the community seeks to address in the next phase of production. Chief among these is the oft cited criticism that the selection of GCMs that provide input to the regional climate models was not robust and that the resulting ensemble represents an “ensemble of opportunity”. Here we will show how the community has addressed these shortcomings and present a toolkit, which can be used for evaluating the suitability of GCMs for downscaling. The utility of this toolkit extends well beyond the regional climate and VIACS communities to include researchers interested in researching model biases, constraining future change and exploring so-called future storylines. The toolkit is open-source and the community encourages contributions and sugestions for imporvement. Therefore a short tutorial is also included as part of this talk. 

How to cite: Sobolowski, S. and the EURO-CORDEX CMIP6 GCM Selection & Ensemble Task Team: GCM Selection & Ensemble Design: Best Practices and Recommendations from the EURO-CORDEX Community, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1884, https://doi.org/10.5194/egusphere-egu24-1884, 2024.

The impacts of topographic uplift in different areas of the Tibetan Plateau (TP) on the arid climate and dust cycle in the sandy areas on the north and south sides of the plateau are studied using a regional climate model (RCM) by comparing numerical experiments on the uplift of the Pamirs and the northern TP. Simulation results based on tectonic geological records can be used to explain the differences in drought evolution in different areas around the TP. The results show that: (1) The mechanical blocking effect caused by the uplift of the Pamirs has mainly intensified the aridification and desertification of the Taklimakan Desert since the Pliocene, and its uplift has blocked the water vapor channel in the west side of Tarim Basin, causing a 50% reduction in the annual precipitation (mainly winter precipitation) and a 10-30% increase in the atmospheric dust loading in the Taklimakan Deserts. (2) The uplift of the northern Tibetan Plateau mainly intensifies the aridification of the Thar Desert. The uplift of the northern TP controls the position and intensity of the subtropical high center at 700 hPa in the Thar Desert, causing a 50% reduction in summer and annual precipitation and increase in the atmospheric dust loading in the Thar Desert. (3) The aridification of the Gobi Desert and Loess Plateau since the Miocene is also related to the uplift of the northern TP. The uplifting suppresses the East Asian summer monsoon (EASM), causing a 30-50% reduction in summer precipitation in the Gobi Desert and Loess Plateau. Drought further causes a 10-20% increase in the dust loading in the above areas. (4) In view of the limited geological evidence of remarkable tectonic uplift in the northern TP and the Pamirs since the Miocene and Pliocene respectively and based on the current numerical simulation results, it is speculated that the formation of the Thar Desert should be earlier than the Taklimakan Desert.

How to cite: Sun, H. and Liu, X.: Impacts of the uplift of the Pamirs and northern Tibetan Plateau on the aridification of the Taklimakan and Thar deserts since the Miocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2880, https://doi.org/10.5194/egusphere-egu24-2880, 2024.

EGU24-3119 | ECS | Orals | CL5.5 | Highlight

Changes in concurrent hot and dry extremes based on convection-permitting projections under the SSP5-8.5 scenario 

Zixuan Zhou, Eun-Soon Im, and Hyun-Han Kwon

Accelerated global warming is anticipated to intensify the frequency and severity of concurrent extremes, leading to negative impacts that surpass those of individual extreme events. Southeastern China has experienced a rise in the occurrence of concurrent hot and dry extremes in recent years, and the expected amplification of such events is likely to worsen economic losses and endanger human well-being. Due to the significant impacts of such concurrent extremes, there is a strong demand for dependable future projections at the local level. However, most studies have focused on univariate analysis of single extremes using coarse-grid global climate models (GCM), which may not fully capture the region-specific climate impacts of global warming. To address this issue, this study will utilize convection-permitting (CP) regional climate modeling and multivariate statistical analysis to evaluate the future changes in concurrent hot and dry extremes. The Weather Research and Forecasting model (WRF) will be used to downscale the bias-corrected CMIP6 GCM projections under the SSP5-8.5 scenario at the convection-permitting scales (4km) over southeastern China. The study aims to investigate the process-based added value of CP projections when assessing future changes in concurrent hot and dry extremes over densely populated regions in China. The high-resolution simulation is expected to enhance the understanding of compound climate extremes and provide quantified insights into prospective climate risks.

[Acknowledgements]

This research was supported by project GRF16308722, which was funded by the Research Grants Council (RGC) of Hong Kong. This research was also partly supported by Korea Environmental Industry & Technology Institute (KEITI) through Water Management Program for Drought Project, funded by Korea Ministry of Environment (MOE) (2022003610003)

How to cite: Zhou, Z., Im, E.-S., and Kwon, H.-H.: Changes in concurrent hot and dry extremes based on convection-permitting projections under the SSP5-8.5 scenario, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3119, https://doi.org/10.5194/egusphere-egu24-3119, 2024.

 Selecting representative climate models for climate change impact studies: A case study of the eastern Omo basin

Tekalegn Ayele Woldesenbeta b, Nadir Ahmed Elagiba

 

a Institute of Geography, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany

b Ethiopian Institute of Water Resources, Addis Ababa University, Addis Ababa, Ethiopia

Abstract

Selecting reliable general climate models (GCMs) is crucial for assessing the impact of climate change in a region. The current study evaluated the performance of 34 GCMs from the Coupled Model Intercomparison Project Phase 6 (CMIP6) in simulating monthly total rainfall. To this end, the case of eastern Omo basin was considered with observed rainfall data at seven meteorological stations for the period 1985–2014. The corresponding GCM-simulated rainfall data were compared using seven performance metrics. Eight performance metrics were selected under four categories as follow: error metrics (mean bias error, mean absolute error, root mean squared error), model efficiency (Nash and Sutcliffe’s model efficiency, absolute model efficiency, Kling-Gupta model efficiency), indices of agreement (modified index of agreement), and goodness of fit (coefficient of determination). Three key results were obtained: 1) There is no single best overall GCM across the meteorological stations using a single performance metric, 2) No single best GCM was found for a meteorological station using all the performance metrics, and 3) Based on all performance metrics across all the meteorological stations, the best GCMs in order of performance are SAM0-UNICON, TaiESM1, INM_CM5_0, AWI_ESM_1_1_LR, and CMCC_CM2_HR4. The selected GCMs can be used for evaluating the impact of climate change on hydrology, water resource availability, ecological flow regime and for climate adaptation and mitigation strategies.

Keywords: performance metrics, CMIP6, rainfall, climate models, ranking, Omo basin,

How to cite: Woldesenbet, T. A. and Elagib, N.: Selecting representative climate models for climate change impact studies: A case study of the eastern Omo basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3740, https://doi.org/10.5194/egusphere-egu24-3740, 2024.

EGU24-3896 | ECS | Orals | CL5.5

High-resolution climate model data over EURO-CORDEX with a focus on cities 

Sara Top, Steven Caluwaerts, Lesley De Cruz, and Rafiq Hamdi

To investigate the effect of climate change on cities and climate adaptation strategies in cities, high-resolution climate model data is needed to resolve urban-rural and intra-urban processes. Due to computational limits, it is currently impossible to create long-term (sub-)kilometric simulations over extended regional domains, such as the EURO-CORDEX domain (Jacob et al., 2020). However, short-term climate simulations at 2.5 km horizontal resolution were performed over Europe with the atmospheric model ALARO which was coupled to the land surface model SURFEX. The model output has been validated against conventional datasets and non-traditional measurements such as those of urban meteorological networks (Caluwaerts et al., 2021). Including non-traditional meteorological measurements is important to verify whether the model captures the urban signature well. Further, a methodology will be presented to obtain climate projections with a more detailed spatial resolution over several European cities. The added value of this new avenue using machine learning to emulate the climatological characteristics from a limited set of cities and generalise this to other cities in the EURO-CORDEX domain will be investigated.

 

Caluwaerts, S., Top, S., Vergauwen, T., Wauters, G., De Ridder, K., Hamdi, R., Mesuere, B., Van Schaeybroeck, B., Wouters, H. and Termonia, P., 2021. Engaging schools to explore meteorological observational gaps. Bulletin of the American Meteorological Society, 102(6), pp.E1126-E1132.

Jacob, D., Teichmann, C., Sobolowski, S., Katragkou, E., Anders, I., Belda, M., Benestad, R., Boberg, F., Buonomo, E., Cardoso, R.M. and Casanueva, A., 2020. Regional climate downscaling over Europe: perspectives from the EURO-CORDEX community. Regional environmental change, 20, pp.1-20.

How to cite: Top, S., Caluwaerts, S., De Cruz, L., and Hamdi, R.: High-resolution climate model data over EURO-CORDEX with a focus on cities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3896, https://doi.org/10.5194/egusphere-egu24-3896, 2024.

Tibetan Plateau (TP, with the height > 3000 m) is a region with complex topographical features and a large diversity of climate both in space and time. Future climate change over TP and the surrounding areas is investigated based on the ensemble of a set of the 21st century climate change projections using a regional climate model, RegCM4. The model is driven by five different GCMs at a grid spacing of 25 km. Results show the RegCM4 greatly improves the temperature and precipitation simulations by providing finer scale spatial details of them over the region. The topographic effects are well reproduced by RegCM4 but not the GCMs. General warming and increase in precipitation are found in both GCM and RegCM4 simulation, but with substantial differences in both the spatial distribution and magnitude of the changes. For temperature, RegCM4 projected a more pronounced warming in DJF over TP compared to its surrounding areas. The increase of precipitation is more pronounced and over the basins in DJF for RegCM4. For the extreme indices of snowfall, RegCM4 generally reproduces the spatial distributions although with overestimation in the amount. General decreases in SNOWTOT and S1mm, with greater magnitude over the eastern part are projected. Both S10mm and Sx5day show decrease over the eastern part but increase over the central and western parts. Notably, S10mm shows a marked increase (more than double) with high cross-simulation agreement over the central TP. Significant increases in all four indices are found over the Tarim and Qaidam basins, and northwestern China north of the TP. The projected changes show topographic dependence over the TP in the latitudinal direction, and tend to decrease/increase in low-/high-altitude areas.

How to cite: Tang, X., Fu, Y., and Gao, X.: Projected changes in mean temperature, precipitation and extreme snowfall events over the Tibetan Plateau based on a set of RegCM4 simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4982, https://doi.org/10.5194/egusphere-egu24-4982, 2024.

We use an ensemble of a regional climate model (RegCM4) projections to assess future changes in surface air temperature, precipitation and Köppen-Trewartha (K-T) climate types in mid-high latitude Northern Asia (NA) under the 1.5-4°C global warming targets. RegCM4 is driven by five CMIP5 global models over an East Asia domain at a grid spacing of 25 km. Validation of the present day (1986-2005) simulations shows that the ensembles of RegCM4 (ensR) and driving GCMs (ensG) reproduce the major characters of the observed temperature, precipitation and K-T climate zones reasonably well. Greater and more realistic spatial detail is found in RegCM4 compared to the driving GCMs. A general warming and overall increases in precipitation are projected over the region, with these changes being more pronounced at higher warming levels. The projected warming by ensR shows different spatial patterns, and is in general lower, compared to ensG in most months of the year, while the percentage increases of precipitation are maximum during the cold months. The future changes in K-T climate zones are characterized by a substantial expansion of Dc (temperature oceanic) and retreat of Ec (sub-arctic continental) over the region, reaching ~20% under the 4°C warming level. The most significant change in climate types in ensR is found over Japan (~60%), followed by Southern Siberia, Mongolia, and the Korea Peninsula (~40%). The largest change in the K-T climate types is found when increasing from 2°C to 3°C.

How to cite: Gao, X., Wu, J., Tang, X., and Giorgi, F.: Projected changes in Köppen-Trewartha climate zones under 1.5–4°C global warming targets over mid-high latitudes of Northern Asia using an ensemble of RegCM4 simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5253, https://doi.org/10.5194/egusphere-egu24-5253, 2024.

EGU24-5341 | Orals | CL5.5

Comparison of different observational constraint methods to reduce the uncertainty in the AMOC at the end of the 21st century 

valentin portmann, Didier Swingedouw, Marie Chavent, and Omar Khattab

For a given greenhouse gas emission scenario, climate models are showing very significant differences for the future climate, due to processes complex to simulate. Among them, the Atlantic Meridional Overturning Circulation (AMOC) fate has been shown to be very uncertain, explaining large amount of the differences in climate projections in the North Atlantic region. Indeed, under the ssp2-4.5 scenario, CMIP6 models show an AMOC maximum at 26°N that goes from 18.1 ± 4.1 Sv (1 Sv=106 m3/s, ensemble mean of 30 models one standard deviation) during the period 1850-1900, to 11.6 ± 3,9 Sv in the last decade of 2100, with AMOC ranging from 4.3 to 21.3 Sv depending on the model. There is thus a clear need to improve estimates of the AMOC in the future.

In this respect, methods called emergent or observational constraint (OC) have been recently developed. They combine climate models and observations, by finding and using an emergent relationship between a given climate variable in the future and observable predictors, to refine the best guess and uncertainty estimation of this climate variable. This study proposes to apply them to the case of AMOC projections. Both the choice of the predictor, and of the OC method can be key. What are the best choices to reduce most the uncertainty of the AMOC at the end of the 21st century? To answer such a question, this study compares two possible cases: it uses either only one predictor, the past AMOC, or a set of predictors, the sea surface temperature and salinity from various regions in the world, which are known to impact on-going and future fate of the AMOC. Moreover, this study compares five different OC methods. The uncertainty is evaluated for each couple of predictors and OC choice, considering cross-validation and observational errors.

The best estimates of future AMOC under ssp2-4.5 scenario, constrained by the observed AMOC over the period 2004-2021, is 11,6 ± 2,5 Sv, using the linear regression method. When constrained by a larger set of predictors, it is 7,9 ± 2,1 Sv, using also the linear regression found here as the best OC method, with a Ridge regularization that limits overfitting. Thus, the future AMOC, in 2091-2100 compared to 1850-1900, is weakening by 56% when constrained by various recent observations that count for AMOC dynamics, in place of 36% when estimated using ensemble mean or AMOC observation only, as done in last IPCC reports. This result might have therefore considerable impacts on future adaptation plans within the North Atlantic regions.

How to cite: portmann, V., Swingedouw, D., Chavent, M., and Khattab, O.: Comparison of different observational constraint methods to reduce the uncertainty in the AMOC at the end of the 21st century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5341, https://doi.org/10.5194/egusphere-egu24-5341, 2024.

EGU24-5482 | ECS | Orals | CL5.5 | Highlight

The role of convection-permitting RegCM5 simulations in representing synoptic-scale cyclones over Southeastern South America 

Maria Leidinice da Silva, Erika Coppola, Michelle Simões Reboita, Rosmeri Porfírio da Rocha, and Francesca Raffaele

Southeastern South America (SESA) stands out as a hotspot on the planet where weather and climate extremes occur with notable frequency, exerting negative impacts on various socio-economic activities. One cause of these extremes are the synoptic-scale cyclones. In this sense, the objective of this study is to evaluate the performance of a convection-permitting scale simulation (CP) with Regional Climate Model version 5 (RegCM5) in simulating the cyclone features (frequency, intensity, lifetime, preferential regions, precipitation, etc.) in the SESA region from January 2018 to December 2021. The CP simulation was driven by ERA5 reanalysis with 3.0 km of horizontal grid spacing in a domain covering from ~ 11°S to 35°S. Cyclones are identified with a tracking algorithm based on relative vorticity at 925 hPa. The cyclone features in the CP simulation are compared with that from ERA5. The mesoscale structure of the simulated precipitation associated with cyclones is compared with satellite estimates. Overall, CP simulation captured the main observed features associated with cyclones.

How to cite: da Silva, M. L., Coppola, E., Reboita, M. S., da Rocha, R. P., and Raffaele, F.: The role of convection-permitting RegCM5 simulations in representing synoptic-scale cyclones over Southeastern South America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5482, https://doi.org/10.5194/egusphere-egu24-5482, 2024.

EGU24-5782 | Posters on site | CL5.5

Validation of regional climate model ALADIN-CLIM-CZ 

Zuzana Rulfova and Romana Beranova

Regional climate model ALADIN-CLIM-CZ operated by Czech Hydrometeorological Institute has been upgraded to the convection permitting resolution of 2.3 km together with the implementation of the non-hydrostatic, fully elastic dynamical core. This study deals with the validation of the reanalysis using the ALADIN-CLIM-CZ model in the area of Europe with a focus on the area of Central Europe. The main motivation for this validation is to evaluate the quality of the model in connection with its planned use for forecasting the future climate in Central Europe and especially in the territory of the Czech Republic.

Due to the goal of validation, the study presents standard climate statistics for months and quarters such as long-term means and mean annual cycles and compares them with measurements at selected stations. We validated the following predicted quantities: precipitation amount and number of wet days, mean, minimum and maximum temperature at 2 m above surface, relative humidity at 2 m above surface, wind speed at 10 m above surface and global radiation at the surface.

How to cite: Rulfova, Z. and Beranova, R.: Validation of regional climate model ALADIN-CLIM-CZ, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5782, https://doi.org/10.5194/egusphere-egu24-5782, 2024.

EGU24-5801 | Orals | CL5.5 | Highlight

The impact of convection-permitting simulation on the mesoscale structures of two severe synoptic-scale cyclones on the south-southeast coast of Brazil in 2023 austral winter 

Michelle Reboita, Rosmeri da Rocha, Leidinice da Silva, Erika Coppola, and Francesca Raffaele

Synoptic-scale cyclones in the southwestern South Atlantic Ocean often result in heavy rainfall, strong winds, sudden temperature drops, and other abrupt changes that affect important metropolitan areas along the south-southeastern coast of Brazil. Despite notable advancements in understanding these systems, numerical simulations continue to face difficulties in accurately reproducing cyclone-induced rainfall and intense winds. Therefore, the aim of this study is to assess the ability of convection-permitting scale simulations (CP) with a spatial resolution of 3 km, to reproduce the mesoscale structures associated with two extratropical cyclones that caused multiple fatalities in the southern Brazil in June and July of 2023. Regional Climate Model (RegCM) version 5 is configured in CP mode and runned continuously from May to July 2023 in a large domain (lon: -81.12 to -33.09; lat: -48.45 to -10.47). The first month is considered a spin-up period. Precipitation simulated in CP mode is compared with locally observed data and with satellite estimates. The comparison with observations indicates that the resolution refinement and the use of cloud microphysics in CP simulation develop many of the cyclone mesoscale structures generating intense precipitation events. The authors thank CNPq, FAPESP and FAPEMIG for their financial support.

How to cite: Reboita, M., da Rocha, R., da Silva, L., Coppola, E., and Raffaele, F.: The impact of convection-permitting simulation on the mesoscale structures of two severe synoptic-scale cyclones on the south-southeast coast of Brazil in 2023 austral winter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5801, https://doi.org/10.5194/egusphere-egu24-5801, 2024.

EGU24-6495 | Orals | CL5.5

Exploring CORDEX and driving GCM differences, in the context of time evolving aerosols  

ben booth, Tom Crocker, Citlali Solis Salas, Carol McSweeney, and Tim Andrews

An emerging literature has been exploring RCM-GCM differences over Europe and linking many of these differences to the lack (or in a few cases, underestimation) of aerosol “Brightening” in the RCMs (Boe et al, 2019, Gutiérrez et al, 2020, Tarana et al, 2022).  Here we illustrate these differences for mid-century European surface SW, temperature and rainfall projections, with a focus on the spread.  The tendency for the RCMs to underestimate the GCM warming and drying is evident.  For example the RCMs at the lower end show roughly half the warming of the lowest driving CMIP5 GCM and roughly 50% of the RCMs suggest wetter projections that 6 out of 7 driving CMIP5 GCMs.  

We extend this analysis to the wider CORDEX regions and identify where lack of time varying aerosol representation does, and does not matter.   We also use single forcing (AER) CMIP6 experiments, to illustrate how this data can be a useful tool to predict where time varying aerosol representation is (and where it is not) likely to be important in ongoing CMIP6 downscaling.

How to cite: booth, B., Crocker, T., Solis Salas, C., McSweeney, C., and Andrews, T.: Exploring CORDEX and driving GCM differences, in the context of time evolving aerosols , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6495, https://doi.org/10.5194/egusphere-egu24-6495, 2024.

EGU24-6796 | ECS | Orals | CL5.5 | Highlight

Improving Multi-model Ensembles of Climate Projections through Time Variability Correction and Ensemble Dependence Transformation 

Yawen Shao, Craig Bishop, Gab Abramowitz, and Sanaa Hobeichi

The uncertainty of future climate change is typically estimated by a collection of models from various climate institutions. The Ensemble Dependence Transformation (EDT) method has proven effective in producing ensembles with means that lie closer to the verifying observations and with variances that match the variance of the observations about the ensemble mean. However, EDT does not specifically address temporal variability and persistence attributes within individual models. This limitation can potentially be addressed by the Time Variability Correction (TVC) method, designed to quantify, and correct model variability errors across differing time scales.

In this study, we test and compare four approaches: 1) TVC only; 2) EDT only; 3) TE: Applying TVC to individual models first, followed by EDT; 4) ETE: Applying EDT to obtain the time-varying mean series, using TVC to correct the EDT-transformed series, and applying EDT again to TVC post-processed model series. These methods are employed to post-process 26 CMIP6 (Coupled Model Intercomparison Project Phase 6) daily mean temperature projections across Australia under a model-as-truth setup.

We evaluate the results using verification metrics for assessing both individual models and multi-model ensembles. Findings indicate that, overall, ETE performs better in improving individual model statistics, including variance and lag correlations relative to the time-varying ensemble mean. Additionally, ETE enhances ensemble statistics, notably ensemble standard deviation (ESD) during both in-sample historical and out-of-sample projection periods. TE is particularly effective at improving root mean squared difference (RMSD) between ensemble mean and observations, along with continuous ranked probability skill score (CRPSS).

How to cite: Shao, Y., Bishop, C., Abramowitz, G., and Hobeichi, S.: Improving Multi-model Ensembles of Climate Projections through Time Variability Correction and Ensemble Dependence Transformation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6796, https://doi.org/10.5194/egusphere-egu24-6796, 2024.

Precipitation is an important aspect of the climate and is expected to change from increasing greenhouse gases. However, model projections of precipitation changes are stubbornly uncertain, particularly in tropical regions. It has been long recognized that much of the uncertainty in tropical precipitation changes is rooted in the uncertainty in sea surface temperature (SST) changes. But unfortunately, constraining SST changes at regional scales has been quite difficult. Here, we advocate that instead of fixating on regional SST changes, it is much more productive to focus on constraining precipitation sensitivity to SST changes (i.e., hydrological sensitivity). We show that local hydrological sensitivity varies widely among the state-of-the-art global climate models, but it can be effectively constrained by honing in on specific aspects of the observed precipitation-SST relationships. We find that despite the large inter-model disagreement, regional hydrological sensitivity in tropical oceans is accurately projected by the CMIP6 multi-model averages.

How to cite: He, J.: Constraining Hydrological Sensitivity in Tropical Oceans, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6803, https://doi.org/10.5194/egusphere-egu24-6803, 2024.

EGU24-7207 | Posters on site | CL5.5

GCM selection for dynamical downscaling of extreme rainfall changes over Belgium 

Bert Van Schaeybroeck, Kobe Vandelanotte, Nicolas Ghilain, Hans Van de Vyver, Fien Serras, Nicole Van Lipzig, and Piet Termonia

Regional climate models (RCMs) may provide detailed climate information that is required by local stakeholders. Additionally, RCMs have shown added value in their representation of extremes such as extreme rainfall, with respect to Global Climate Models (GCMs). However, RCM simulations are computationally very expensive and depend strongly on the forcing GCM. Therefore, it is essential to carefully select the GCM. Previous coordinated ensemble simulations from EURO-CORDEX forced by GCMs from CMIP5 did not include a coordinated GCM selection. Recent efforts using CMIP6, on the other hand, do provide a framework for GCM selection (Sobolowski et al., 2023) based on different criteria for Europe. These criteria include model performance, availability and reliability of the climate-change signal. In Belgium, the CORDEX.be II project aims to provide regional climate-change information for climate services in support of climate adaptation and mitigation.  This information will be extracted using three regional climate models: ALARO-SURFEX, COSMO-TERRA-URB and MAR at convection-permitting resolutions (Termonia, et al., 2018). We present the overall setup of the CORDEX.be II methodology and the GCM selection. Thereby, the selection criterion of covering the entire range of climate-change signals, as used within the EURO-CORDEX effort, is replaced with the criterion to obtain the strongest changes in climate extremes possible, in line with the demand from the main stakeholders. More specifically, based on the EURO-CORDEX downscaling results forced by CMIP5, we outline a methodology for GCM selection to obtain the highest likelihood of strong changes in rainfall extremes. We explore the dependence of this likelihood with respect to different model predictors, RCM and GCM model groups and regions over Europe. We then apply this methodology on the CMIP6 ensemble over Belgium to obtain a list of selected runs for dynamic downscaling.

Termonia, et al. (2018). The CORDEX. be initiative as a foundation for climate services in Belgium. Climate Services, 11, 49-61.

Sobolowski et al. (2023) 10.5281/zenodo.7673399.

How to cite: Van Schaeybroeck, B., Vandelanotte, K., Ghilain, N., Van de Vyver, H., Serras, F., Van Lipzig, N., and Termonia, P.: GCM selection for dynamical downscaling of extreme rainfall changes over Belgium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7207, https://doi.org/10.5194/egusphere-egu24-7207, 2024.

EGU24-7537 | ECS | Orals | CL5.5

GCM selection based on weather patterns for extreme heat: a case study over Belgium 

Fien Serras, Kobe Vandelanotte, Ruben Borgers, Bert Van Schaeybroeck, Matthias Demuzere, Piet Termonia, and Nicole van Lipzig

The process of selecting suitable time periods within the Coupled Model Intercomparison Project Phase 6 (CMIP6) for a specific region and warming level presents notable challenges, such as the incomplete representation of atmospheric dynamics and climate-change uncertainties. This study aims to develop a selection procedure for CMIP6 model periods using a methodology to address both the representation of atmospheric dynamics and the relevant changes in the climate variable of interest. In the first step, the representation of past atmospheric dynamics is evaluated to investigate the model quality. This is then used as a criterion to exclude underperforming models. The second step gives information on interesting model periods and indicates which model periods are relevant for selection.

To eliminate models that did not adequately represent historical atmospheric dynamics, the Lamb Weather Type (LWT) classification was used to assess the representation of large-scale circulation patterns across 33 CMIP6 models and compare these with ERA5. This resulted in the exclusion of three CMIP6 models for the circulation regimes over Belgium. Furthermore, in order to account for the increased occurrence of weather patterns related to extreme heat, while also reducing the number of different weather types of the existing LWT classification, the classification was adapted to incorporate a temperature-dependent classification through the optimization of the clustering of weather types and the associated maximum temperatures. Additionally, a new index, the hot weather type index, was introduced and combined with a set of heat-related metrics to illustrate the selection methodology. The final period selection was made based on the combination of the ranks of the different metrics for each global warming level considered.

The method developed in this study offers a framework for selecting periods within CMIP6 while considering both the uncertainties of the large-scale circulation patterns and changes in the climate-change signal. This framework holds potential to contribute to regional climate modelling and facilitate decisions related to the selection of model periods for dynamical downscaling of relevant climate projections.

How to cite: Serras, F., Vandelanotte, K., Borgers, R., Van Schaeybroeck, B., Demuzere, M., Termonia, P., and van Lipzig, N.: GCM selection based on weather patterns for extreme heat: a case study over Belgium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7537, https://doi.org/10.5194/egusphere-egu24-7537, 2024.

EGU24-8433 | ECS | Orals | CL5.5

Enhancing 1-Month Forecasts in South Korea with the Combination of Time-Lagged Ensemble and Dynamical Downscaling 

Subin Ha, Eun-Soon Im, Jina Hur, Sera Jo, and Kyo-Moon Shim

In South Korea, daily weather forecasts are currently limited to a 10-day range, which is insufficient for adequately preparing weather-dependent sectors like agriculture for the impact of meteorological conditions over longer periods. To meet the growing demand for subseasonal-to-seasonal predictions, organizations worldwide provide GCM-driven forecasts that extend several weeks or even months ahead. One example is the Climate Forecast System version 2 (CFSv2) operational forecast by NCEP, which is initialized every 6 hours and extends up to 9 months. Its large pool of available forecast members with different initialization times enables the construction of a time-lagged ensemble, which can improve forecasting accuracy by offering a range of potential future meteorological conditions and accounting for the inherent uncertainty in a single deterministic forecast. In this regard, this study aims to build an optimal time-lagged ensemble for 1-month forecasts in South Korea by employing a systematic method to select suitable members from a pool of hundreds of CFSv2 forecast members. Furthermore, the selected ensemble members will be dynamically downscaled to address limitations arising from their coarse resolution. The integration of the time-lagged ensemble and dynamical downscaling methods will be evaluated from both quantitative and qualitative perspectives to assess their added value in enhancing forecasts. By evaluating the performance of the optimized time-lagged ensemble combined with dynamical downscaling, this study will provide valuable insights into the improvement and practical application of subseasonal-to-seasonal forecasts in South Korea, benefiting various sectors that can leverage the enhanced long-term weather predictions.

 

Acknowledgments

This study was carried out with the support of “Research Program for Agricultural Science & Technology Development (Project No. PJ014882)”, National Institute of Agricultural Sciences, Rural Development Administration, Republic of Korea.

How to cite: Ha, S., Im, E.-S., Hur, J., Jo, S., and Shim, K.-M.: Enhancing 1-Month Forecasts in South Korea with the Combination of Time-Lagged Ensemble and Dynamical Downscaling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8433, https://doi.org/10.5194/egusphere-egu24-8433, 2024.

As intermittent meteorological resources become increasingly vital in our energy system, it is crucial to better understand how a changing climate may affect weather variability and, in turn, influence future wind energy production. This study evaluates the performance of climate models in reproducing wind resources over Southern Africa (SA), and in assessing potential impacts of climate change. An ensemble of climate simulations is evaluated over SA, which includes simulations from three Regional Climate Models (RCM; i.e., CCLM4, RegCM4, and REMO2009) that participated in the Coordinated Regional Downscaling Experiment program over Africa (CORDEX-Africa) at a horizontal resolution of approximately 25 km, and the coarser-resolution ones from their four driving General Circulation Models (GCMs; i.e., HadGEM2-ES, MPI-ESM-LR, MPI-ESM-MR, and NorESM1-M) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). The simulated wind is first compared to the reference datasets, derived from ground-based measurements and reanalyses, during 2000-2023 at 3-hour intervals, covering both surface and hub-height (100 m) levels. The performances of both RCMs and GCMs are quantified and compared in terms of their representation of wind resource characteristics, including the mean wind speed and its spatio-temporal variability at hourly-to-annual timescales. Then wind energy potential and capacity factors are also derived for the wind resource assessment in SA, where direct observational data is limited. Finally, the potential impact of climate change on the 100-meter wind energy potential in SA is assessed based on this ensemble of climate projections, up to 2099, under the RCP2.6 and RCP8.5 scenarios. This study helps to understand the performance difference between regional and global models in simulating wind resources and provides insight into how changing climate conditions might affect wind energy production over the long term in SA.

How to cite: Tang, C. and Morel, B.: How do climate models represent wind resources in Southern Africa and predict their future changes?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8855, https://doi.org/10.5194/egusphere-egu24-8855, 2024.

EGU24-8994 | ECS | Posters on site | CL5.5 | Highlight

Assessment of ensemble selection methods aligning decadal climate variability in a perfect-model framework 

Pep Cos, Leandro B. Díaz, Francisco Doblas-Reyes, Raül Marcos-Matamoros, and Markus G. Donat

Multi-model ensembles of climate simulations often fail to correctly represent the climate evolution of the next decades due to the dominance of internal variability uncertainty in the near-term future. With the objective to solve this issue, in recent years new constraining methods have been developed. These methods aim to select members from the ensemble of climate simulations that have their variability and forced response most in phase with an observational or climate prediction reference. Through an evaluation of the performance of the different methods (Befort et al. 2020, Mahmood et al. 2021, Mahmood et al. 2022) against observations, we find that applying them directly to the CMIP6 multi-model ensemble exhibits high sensitivity to variations in the different parameters that define the methods. This complicates the interpretability of the results. 

We will illustrate the results of a study where we simplify the complexity of the ensemble selection methods by applying them to a single-model large ensemble. We use a perfect-model approach where, in turns, one of the members plays the role of the constraining and evaluation reference. In this study there is only one climate system involved, the one of the climate model chosen, and the differences between models and biases against observations no longer influences the results of the selection methods. Therefore, through this idealized approach, the mechanisms of the different selection methods can be better isolated and studied. Furthermore, this study offers perspectives of the potential improvements that could be expected from these methods and opens the door to finding ways of optimizing the metrics and approaches used to constrain a climate projections ensemble.

 

How to cite: Cos, P., Díaz, L. B., Doblas-Reyes, F., Marcos-Matamoros, R., and Donat, M. G.: Assessment of ensemble selection methods aligning decadal climate variability in a perfect-model framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8994, https://doi.org/10.5194/egusphere-egu24-8994, 2024.

EGU24-9010 | ECS | Posters on site | CL5.5

Snowfall over the Andes: a convection-permitting climate model 

Emily Potter, Sihan Li, Julie Jones, Íñigo Irarrázaval, Tom Matthews, Baker Perry, and Jeremy Ely

The Andes has the longest mountain range in the world, stretching over 7000 kilometres from Colombia in the tropics to the bottom of Chile in the extratropics. Millions of people depend on water supply from the Andes for their consumption, agriculture, hydropower, and ecosystem services. Often, this water comes from snow and glacier melt, and these water stores can be especially important in times of drought, or during dry seasons for regions with strong annual cycles of precipitation. The inaccessibility of the higher regions in Andes makes setting up weather stations difficult, and the extremely complex topography leads to sharp gradients in weather and climate with varying altitudes of snowline, therefore requiring very high-resolution models to accurately capture the small-scale processes occurring. Due to these challenges, snowfall and snowcover in the Andes remain poorly understood and difficult to model, which are critical to address in the face of a changing climate, with potential for future precipitation occurring in fewer, more extreme snowfall events.

Here we present initial work optimising a high-resolution climate model over the Andes from Peru to the bottom of Chile. We have determined the best setup to model snowfall over the Andes in the Weather Research and Forecasting Model. The results of a sensitivity study with multiple different setups are compared to observations from weather stations and satellite data. We also show the capability of the model to represent extreme snowfall events at different latitudes. This model setup will be used to create both hindcasts and future projections of snowfall across the Andes mountain range, to better understand the implications for changing water resources in the Andes

How to cite: Potter, E., Li, S., Jones, J., Irarrázaval, Í., Matthews, T., Perry, B., and Ely, J.: Snowfall over the Andes: a convection-permitting climate model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9010, https://doi.org/10.5194/egusphere-egu24-9010, 2024.

EGU24-9141 | ECS | Posters on site | CL5.5

On the relation of CMIP6 GCMs errors at RCM driving boundary condition zones and inner domain for Central Europe  

Natália Machado Crespo, Eva Holtanová, Michal Belda, and Tomáš Halenka

Global climate models (GCMs) are important tools for studying the climate system and climate change projections. Due to their coarse spatial resolution, downscaling is necessary on a regional scale, hence, regional climate models (RCMs) represent a common solution for this issue. Nevertheless, outputs of RCMs are influenced by the boundary conditions provided by GCMs. This study evaluates CMIP6 GCMs regarding the variables relevant as RCM boundary conditions. Special focus is on the simulation of CNRM-ESM2-1, which is being used as a driving model for convection-permitting Aladin-Climate/CZ RCM, used as one source feeding new Czech climate change scenarios. The analysis is conducted over the boundaries and inside the RCM integration domain, where ERA5 is chosen as reference for the boundary and E-OBS for the inner domain. The CNRM-ESM2-1 performs well in terms of near-surface variables over the Czech Republic, but it exhibits larger errors along the boundaries, especially for air temperature and specific humidity. Weak statistical relationship between the GCM performance over the boundaries in the upper levels and over the inner domain suggests that the nested RCM simulation does not necessarily have to be influenced by the biases in the driving data.

How to cite: Machado Crespo, N., Holtanová, E., Belda, M., and Halenka, T.: On the relation of CMIP6 GCMs errors at RCM driving boundary condition zones and inner domain for Central Europe , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9141, https://doi.org/10.5194/egusphere-egu24-9141, 2024.

EGU24-9204 | ECS | Posters on site | CL5.5

The Central Europe Refined analysis version 2 (CER v2): Dynamical downscaling of ERA5 precipitation data for the metropolitan region Berlin-Brandenburg 

Frederik Bart, Benjamin Schmidt, Xun Wang, Achim Holtmann, Dieter Scherer, Fred Meier, and Marco Otto

The Central European Refined analysis (CER) was developed in 2016 as a high-resolution, reanalysis-based, gridded dataset for Central Europe. The second version (CER v2) aims to further improve the performance of the CER with a particular focus on precipitation data for the metropolitan region Berlin-Brandenburg. The simulation setup consists of two-way nested, cascaded domains for Germany (10 km grid spacing) and the region Berlin-Brandenburg (2 km grid spacing) and employs a daily re-initialization approach. Major changes from the precursor version include the use of ECMWF-ERA5 reanalysis forcing data and a newer WRF version, allowing for the production of longer time series. To further improve the precipitation performance for the CER v2 we performed sensitivity experiments with five cumulus and five microphysics schemes. The results of these test simulations were evaluated using one year of daily precipitation data at 244 stations of the German Weather Service (DWD) in the 2 km domain of the model.  The best average performance was achieved for a combination of the conventional Kain-Fritsch cumulus and the Thompson microphysics scheme. Using this setup, we simulated the precipitation conditions for 30 years (1991-2020) and evaluated monthly and annual precipitation averages against station and radar data by the DWD. Here, the CER v2 showed a significant reduction in deviations and mean bias compared to the previous version. Based on the spatial resolution of the ERA5 data, we resampled the CER v2 and observational data to compare the performance of both datasets. We observed a wet bias in the ERA5 precipitation data for this region, which was significantly reduced in the CER v2. Results of monthly averages indicated a comparable performance to ERA5 data throughout most of the year. Deviations from the observational data were typically higher during the summer months. However, due to the significant bias reduction and the high spatial resolution, the CER v2 could provide important insights about the local- to mesoscale precipitation dynamic of this region.

How to cite: Bart, F., Schmidt, B., Wang, X., Holtmann, A., Scherer, D., Meier, F., and Otto, M.: The Central Europe Refined analysis version 2 (CER v2): Dynamical downscaling of ERA5 precipitation data for the metropolitan region Berlin-Brandenburg, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9204, https://doi.org/10.5194/egusphere-egu24-9204, 2024.

EGU24-9624 | Orals | CL5.5 | Highlight

Dynamical downscaling of CMIP6 scenarios with ENEA-REG: an impact oriented application for the MED-CORDEX region 

Sandro Calmanti, Alessandro Anav, Marta Antonelli, Adriana Carillo, Franco Catalano, Alessandro Dell'Aquila, Roberto Iacono, Salvatore Marullo, Ernesto Napolitano, Massimiliano Palma, Giovanna Pisacane, Gianmaria Sannino, and Maria Vittoria Struglia

In the framework of the coordinated regional modeling initiative Med-CORDEX (Coordinated Regional Climate Downscaling Experiment), we present an updated version of the regional Earth System Model ENEA-REG designed to downscale, over the Mediterranean basin, the models used in the Coupled Model Intercomparison Project (CMIP6). The regional ESM includes coupled atmosphere (WRF), ocean (MITgcm), land (Noah-MP, embedded within WRF), and river (HD) components with spatial resolution of 12 km for the atmosphere, 1/12° for the ocean and 0.5° for the river rooting model.

For the present climate, we performed a hindcast (i.e. reanalysis-driven) and a historical simulation (GCM-driven) over the 1980-2014 temporal period. The evaluation shows that the regional ESM reliably reproduces the mean state, spatial and temporal variability of the relevant atmospheric and ocean variables.

In addition, we analyze the future evolution (2015-2100) of the Euro-Mediterranean climate under three different scenarios (SSP1-2.6, SSP2-4.5, SSP5-8.5), focusing on several relevant essential climate variables and climate indicators for impacts. Among others, results highlight how, for the scenarios SSP2-4.5 and SSP5-8.5, the intensity, frequency and duration of marine heat waves continue to increase until the end of the century and anomalies of up to 2°C, which are considered extreme at the beginning of this century, will become the new normal condition of the Mediterranean Sea in less than a hundred years under the SSP5-8.5 scenario.

Overall, our results demonstrate the improvement due to the high-resolution air-sea coupling for the representation of high impact events, such as marine heat waves, and sea-level height.

How to cite: Calmanti, S., Anav, A., Antonelli, M., Carillo, A., Catalano, F., Dell'Aquila, A., Iacono, R., Marullo, S., Napolitano, E., Palma, M., Pisacane, G., Sannino, G., and Struglia, M. V.: Dynamical downscaling of CMIP6 scenarios with ENEA-REG: an impact oriented application for the MED-CORDEX region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9624, https://doi.org/10.5194/egusphere-egu24-9624, 2024.

EGU24-10824 | Orals | CL5.5

Enhanced Driving Data for Regional Climate Models: Investigating the Systematic Improvements with GCM Run-time Empirical Bias Correction 

Marie-Pier Labonté, Dominic Matte, John Scinocca, Slava Kharin, Martin Leduc, and Dominique Paquin

A novel runtime empirical bias correction (EBC) has recently been developed and applied to enhance the Canadian Center for Climate Modelling and Analysis' (CCCma) global earth system model CanESM, demonstrating significant improvements in future climate projections, particularly under strong climate change scenarios. The application of EBC to CanESM provides enhanced driving data for dynamical downscaling through regional climate models (RCMs).

This project aims to assess the impact of the improved EBC driving data on two RCMs, namely CanRCM5 (CCCma) and CRCM5 (Ouranos), in order to evaluate the systematic improvement of meteorological variables. Multiple 10-member ensembles are utilized to investigate the added value of employing EBC in driving the RCM simulations. The ensembles consist of three sets: the first set utilizes the original CanESM5 as driving data, the second set incorporates EBC on sea surface temperature (SST) and sea ice concentration (SIC) using the original CanESM5, and the third set employs bias-corrected atmosphere, SST, and SIC data. All three ensembles are compared against ERA5 data as a reference for the historical period.

Results indicate a clear advantage of using EBC, particularly in cases where the initial bias is substantial. For instance, significant improvement in modeling key meteorological phenomena, notably the North American monsoon and the northeasters (extratropical cyclones). These improvements can be attributed not only to the refinement in addressing climatological biases in land and ocean data but also to an enhanced representation of cyclonic activities due to a better representation of overall circulation in our region. Ultimately, this research seeks to contribute to the scientific community by providing a methodology to mitigate uncertainties in downscaled projections of future climate change through the utilization of EBC.

How to cite: Labonté, M.-P., Matte, D., Scinocca, J., Kharin, S., Leduc, M., and Paquin, D.: Enhanced Driving Data for Regional Climate Models: Investigating the Systematic Improvements with GCM Run-time Empirical Bias Correction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10824, https://doi.org/10.5194/egusphere-egu24-10824, 2024.

EGU24-11350 | Posters on site | CL5.5

Examining Patterns of Temperature and Precipitation Biases in a Dynamic Downscaling Process across Europe 

Rafaella - Eleni Sotiropoulou, Ioannis Stergiou, and Efthimios Tagaris

The Weather Research and Forecasting (WRFv4.0 ARW) mesoscale meteorological model dynamically downscales data from the NASA Goddard Institute for Space Studies (GISS) GCM ModelE2 atmospheric general circulation model (GCM) CMIP5 version (Model E2-R) over Europe to replicate the observed bias and temporal variability and the previously observed impact of climate change on critical meteorological parameters. Given that RCM outputs are still susceptible to climate model errors from the RCM's structure and the driving GCM/ESM's initial and boundary conditions, examining a model's ability to replicate changes in climatic factors over the last several decades is an intriguing task. This activity identifies systematic biases and examines their sources. WRFv4.0 ARW is single-nested with 0.75°–0.25° grid resolutions. The past and current periods are represented by two 30-year datasets, 1951–1980 and 1981–2010. Model biases for mean temperature, mean precipitation, the number of days with temperatures exceeding 25 °C, and days with precipitation surpassing 5 mm (following WMO guidelines) were compared against E-OBS observations at a 0.25° spatial resolution. The analysis revealed consistent underprediction of mean temperature changes across all subregions, indicating a colder climatology assessment, especially during winter in southern and eastern subregions. Most subregions have the strongest bias in winter. The southern and eastern subregions show the largest bias due to land-atmosphere interactions. Conversely, spring or fall simulate the lowest biases. The lower snow cover during these seasons counters the overestimation of surface albedo in winter, and the radiation scheme has a gentler effect than in summer. In terms of days with a mean temperature above 25 °C, Southern Europe experiences an increased number of them. Model biases in mean precipitation displayed a general negative trend across subregions, a known issue in WRF simulations influenced by regional weather patterns that do not show a geographically regular trend. Over the two time slices, northwestern Europe had more days per month with mean daily precipitation above 5 mm than the middle and southern regions. Model simulated bias is quite small everywhere, demonstrating competence in predicting changes beyond the threshold. Model seasonal findings were always comparable to observations, despite minor regional differences. This study underscores the importance and need for more observations, particularly from southern Europe, for more credible evaluation studies.

How to cite: Sotiropoulou, R.-E., Stergiou, I., and Tagaris, E.: Examining Patterns of Temperature and Precipitation Biases in a Dynamic Downscaling Process across Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11350, https://doi.org/10.5194/egusphere-egu24-11350, 2024.

EGU24-11420 | ECS | Posters on site | CL5.5

Reducing snow amount Uncertainty in CMIP6 Pan-Canadian Climate Projections 

Dominic Matte, Martin Leduc, Marie-Pier Labonté, and Dominique Paquin

Recent studies have demonstrated that the uncertainty in projections can be reduced by weighting the GCMs based on their ability to accurately reproduce historical climate conditions in specific geographical regions. This study aims to reduce the uncertainty in projections of the annual maximum snow amount from obtained from the most recent iteration of GCMs in the Coupled Model Intercomparison Project Phase 6 (CMIP6). To do so, we implement a three-phase approach in order to adapt the Climate model Weighting by Independence and Performance (ClimWIP) algorithm to the main drivers of snow-amount projections.
Phase one of our research involves identifying and implementing the most effective metric combinations that yield a weighted field closely aligning with the reference dataset's state. In phase two, these optimal combinations are applied within a perfect model protocol to determine the most appropriate combination for practical application. The final phase uses the selected combination to compute weights specifically for the climate projection of the annual maximum snow amount.
Our findings indicate that our approach primarily impacts regions where snow amount is a critical factor. Additionally, we observe a narrowed range of uncertainties in both the annual maximum snow amount and the 2-meter temperature projections. This study's outcomes not only demonstrate the efficacy of our approach but also offers valuable insights for future climate projection and adaptation strategies in Canada.

How to cite: Matte, D., Leduc, M., Labonté, M.-P., and Paquin, D.: Reducing snow amount Uncertainty in CMIP6 Pan-Canadian Climate Projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11420, https://doi.org/10.5194/egusphere-egu24-11420, 2024.

EGU24-12626 | ECS | Posters on site | CL5.5

Projected Changes in Energy and Hydrologic Budget over Asian Dust Source Regions 

Sujeong Lim, Seon Ki Park, and Claudio Cassardo

Asian dust storms (ADSs) are widely considered to have originated in the Taklimakan and Gobi Deserts, Inner Mongolia, and northeast China. Because dust emissions are dependent on surface conditions such as wind speed and soil moisture, accurate land surface conditions in dust source areas are essential. We use regional climate projections from the Regional Climate Model version 4 (RegCM4) along with emission scenarios (Representative Concentration Pathways; RCP) from the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios to look into how the energy and water budgets of ADS source regions change in response to different climate change scenarios. To quantify changes in energy and hydrologic components over the source regions of ADS, we use the University of Torino model of land Processes Interaction with Atmosphere (UTOPIA), a diagnostic one-dimensional model that represents the interactions between the atmosphere, land surface, vegetation, and soil layers. We will examine the energy and hydrologic climate projections based on two emission scenarios (e.g., RCP4.5 and RCP8.5) with respect to ADS predictions.

How to cite: Lim, S., Park, S. K., and Cassardo, C.: Projected Changes in Energy and Hydrologic Budget over Asian Dust Source Regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12626, https://doi.org/10.5194/egusphere-egu24-12626, 2024.

EGU24-13517 | Orals | CL5.5

Constraining temperature variability projections using SMILEs that best represent observed variability 

Nicola Maher, Laura Suarez-Gutierrez, and Sebastian Milinski

Projecting how temperature variability is likely to change in the future is important for understanding future extreme events. This comes from the fact that such extremes can change due to both changes in the mean climate and its variability. The recent IPCC report found large regions of low model agreement in the change of temperature variability in both December, January, February (DJF) and June, July, August (JJA) when considering 7 Single Model Initial-Condition Large Ensembles (SMILEs). In this study we use the framework described by Suarez-Gutierrez et al, (2021) to constrain future projections of temperature variability by selecting the SMILEs that best represent observed variability.

We consider 11 SMILEs with CMIP5 and CMIP6 forcing over 9 ocean regions and 24 land regions. We find that CESM2-LE, GFDL-SPEAR-MED and MPI-GE-CMIP6 perform best in DJF and CESM2-LE, CESM1-LE and GFDL-SPEAR-MED perform best in JJA. We find that the Southern Ocean is poorly represented in all models and that few models can represent Central America, the Amazon, North-East Brazil, and eastern and southern Asia, with western and eastern Africa poorly represented in JJA and northern Australia poorly represented in DJF. Overall models perform well over the Northern Hemisphere land masses. When we constrain temperature variability estimates, variability is generally lower, particularly over South America, Africa, and Australia – the same regions where the constraint improves projections, and where the projected change is smaller in the constraint. Where hot extremes increase so do cold extremes showing projected changes in all regions as a fattening or thinning of the distribution rather than a change in skewness.

How to cite: Maher, N., Suarez-Gutierrez, L., and Milinski, S.: Constraining temperature variability projections using SMILEs that best represent observed variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13517, https://doi.org/10.5194/egusphere-egu24-13517, 2024.

EGU24-15085 | ECS | Orals | CL5.5

Future projection of extreme precipitation and temperature indices in Central Asia using CORDEX-CORE 

Praveen Rai, Freddy Bangelesa, Daniel Abel, Katrin Ziegler, Jingshui Huang, Timo Schaffhauser, Markus Disse, and Heiko Paeth

Our study aims to investigate the development of extreme climate indices based on temperature and precipitation over Central Asia using multiple RCMs from CORDEX-CORE. The study area is defined by an overlapping area of the Central Asian (CAS) and the East Asian (EAS) CORDEX domains to increase the number of ensemble members from 4 to 10. This enables us to compare the biases and projections among the ensembles of the different domains as well. We focus on three-time slices of the present (1981-2005), the mid- (2031-2065), and far-future (2071-2095) using the scenario RCP8.5.

For precipitation indices, an increase of consecutive dry days in EAS and a slight to moderate decrease in the northern parts of CAS during the mid-future compared to present values is observed. Consecutive wet days, very heavy precipitation events (R20mm), the maximum one-day precipitation, and very wet days (R95p) are projected to increase in most areas. All indices show a further intensification towards the end of the century over large parts of the domain. For temperature indices, the ensembles project a strong increase over the high mountain regions and southern parts for the consecutive summer days, the heat wave duration index, and the percentage of very hot days (TX90p). Accordingly, the number of consecutive frost days and the percentage of very cold days (TX10p) are projected to decrease. However, some discrepancies in the projected changes prevail among the different RCMs being part of the two CORDEX-domains and in specific landscapes like complex mountain or lake areas.

How to cite: Rai, P., Bangelesa, F., Abel, D., Ziegler, K., Huang, J., Schaffhauser, T., Disse, M., and Paeth, H.: Future projection of extreme precipitation and temperature indices in Central Asia using CORDEX-CORE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15085, https://doi.org/10.5194/egusphere-egu24-15085, 2024.

EGU24-15257 | ECS | Posters on site | CL5.5

Sensitivity study of WRF and RegCM models to different physics schemes during two extreme weather events over Europe  

Shruti Verma, Anahí Villalba-Pradas, Tomáš Halenka, Natália Machado Crespo, Jan Karlický, and Peter Huszár

Urban environments not only affect the warming rate over cities but also induce changes in other relevant meteorological variables. One of the main goals of the FPS URB-RCC Project and the Horizont research project Impetus4Change (I4C) is to improve our understanding of the impact of urban areas on the regional climate and vice versa, as well as to identify how urban parameterizations impact the regional-to-local scale processes, and, in general to improve the quality, accessibility and usability of near-term climate information. To evaluate these impacts in the long term, first we need to find the “best” configuration possible for our models and then validate them against high-quality observations.  

 

In this study, we present preliminary results from a series of sensitivity tests focusing on two extreme events occurred in 2020 over Paris, with the aim of finding the “best” model configuration. Simulations were performed using two models (WRF and RegCM5) with a double-nested domain at 12 and 3 km resolution, respectively, centered over Paris. Urban schemes of different complexity are used in WRF (in particular, we use the bulk, SLUCM and BEP+BEM urban schemes) as well as different physics options in both models. In the case of the RegCM5 model, different cores were tested too. The results show that relevant meteorological variables, such as temperature and precipitation, depend on the urban canopy scheme used as well as on the microphysics and planetary boundary layer schemes. Moreover, the effects of dynamical core in RegCM5 are more prominent than explicit moisture schemes for simulation of heat wave events. 

How to cite: Verma, S., Villalba-Pradas, A., Halenka, T., Machado Crespo, N., Karlický, J., and Huszár, P.: Sensitivity study of WRF and RegCM models to different physics schemes during two extreme weather events over Europe , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15257, https://doi.org/10.5194/egusphere-egu24-15257, 2024.

EGU24-16077 | Orals | CL5.5 | Highlight

Projected climate change signals for selected hotspot regions using regional climate simulations in southern Africa   

Armelle Remedio, Torsten Weber, Francois Engelbrecht, Sophie Biskop, Jessica Steinkopf, Jonathan Padvatan, Cornelis van der Waal, Theo Wassenaar, Kawawa Banda, Keabile Tlhalerwa, and Jem Perkins

Based on the IPCC AR6 Report, the southern African climate change signal is projected to have a rapid warming compared to the global signal. A decreasing trend in the observed mean precipitation can already be detected in most of southern Africa and an increasing trend in heavy precipitation in eastern southern Africa. While some areas are experiencing increased rainfall and flood risks, other regions are facing reduced rainfall and more frequent droughts. These changes are projected to intensify in a warmer world, with significant impacts on water security, food security and biodiversity. 

 In this study, the climate change signal for selected hotspot regions in southern Africa were assessed under the “TIPPing points Explained by Climate Change (TIPPECC)” project embedded in the BMBF-funded SASSCAL 2.0 research program. The temperature and precipitation changes were analyzed from existing high resolution simulations (CORDEX, CORDEX-CORE, CMIP6 Simulations) using 2 regional concentration pathways scenarios (RCP2.6 and RCP8.5) during different time periods over case study regions in Namibia, Zambia, Botswana, and South Africa. Based on the initial results from CORDEX-CORE simulations, the ensemble mean of absolute change of precipitation ranges from about -1 to 1 mm/day for both RCP2.6 and RCP8.5 scenarios in the near future. The ensemble mean of absolute change of mean 2-m temperature ranges from about 0.5 to 1.7 K in RCP2.6 and about 0.8 to 3.2 K in RCP8.5 in the near future. These regional climate change signals can be used as information for adaptation measures and sustainable development strategies to mitigate the impacts and enhance the resilience of communities and ecosystems in southern Africa, which is a region already water-stressed and with low adaptive capacity. 

How to cite: Remedio, A., Weber, T., Engelbrecht, F., Biskop, S., Steinkopf, J., Padvatan, J., van der Waal, C., Wassenaar, T., Banda, K., Tlhalerwa, K., and Perkins, J.: Projected climate change signals for selected hotspot regions using regional climate simulations in southern Africa  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16077, https://doi.org/10.5194/egusphere-egu24-16077, 2024.

EGU24-17308 | Orals | CL5.5 | Highlight

Challenging the complexity: assessing the performances of the convection-permitting configuration of the Regional Earth System Model RegCM-ES over northern Italy 

Marco Reale, Graziano Giuliani, Emanuela Pichelli, Matilde Garcia-Valdecasas Ojeda, Fabio Giordano, Erika Coppola, Stefano Querin, and Stefano Salon

Northern Italy is an area located in the northern part of the Mediterranean region where several factors make the modeling of its climate dynamics particularly challenging. The area is characterized by significant environmental gradients due to the complexity and high orography of  the Alpine arc surrounding the relatively flat area of the Po Valley, while strong air-sea interactions and deep water formation processes in the northern Adriatic Sea are associated with Bora wind episodes flowing over the basin. Moreover, the peculiar West-East oriented topography of the region drives the formation of a complex river network including the Po river, which is one of the major freshwater sources of the Mediterranean Sea. 

Here we assess the performances of a state-of-the-art convection-permitting configuration of the Regional Earth System Model RegCM-ES specifically developed for the northern Italy region. The modeling tool components are : (i) RegCM5  with an horizontal resolution of 3 km and 50 vertical levels for the atmosphere, (ii) MITgcm  with an horizontal resolution of approximately 700 m and 59 vertical levels (non hydrostatic) for the ocean and (iii) CHyM with an horizontal resolution of approximately 1 km for the rivers.

Model performances have been evaluated against observations and reanalysis datasets (available for the region) in a numerical experiment driven at the boundaries by ERA5 for the atmosphere and by the Copernicus Marine Service (CMS) reanalysis for the ocean. The model well captures  the spatial gradients and mean values of land and seawater temperature, precipitation and sea surface salinity. Still some deficiencies are observed such as a warm bias in summer over the western part of the Po Valley and an overestimation of precipitation over the Alps, although the latter is likely linked to the poor coverage of high altitude measurement stations in the area. 

This configuration will be adopted in the future to produce high resolution climate projections for the region.

How to cite: Reale, M., Giuliani, G., Pichelli, E., Garcia-Valdecasas Ojeda, M., Giordano, F., Coppola, E., Querin, S., and Salon, S.: Challenging the complexity: assessing the performances of the convection-permitting configuration of the Regional Earth System Model RegCM-ES over northern Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17308, https://doi.org/10.5194/egusphere-egu24-17308, 2024.

EGU24-18186 | ECS | Orals | CL5.5

Bias-adjusting for underestimated large-scale European warming in regional climate model simulations and implications for future extremes 

Stefanie Börsig, Dominik L. Schumacher, Mathias Hauser, Erich Fischer, and Sonia I. Seneviratne

Our warming climate enhances both the frequency and intensity of weather extremes. To enable adequate mitigation and adaptation decision-making and planning,  accurate long-term climate projections across scales are essential. Europe has warmed faster than any other World Meteorological Organization region in the last decades, yet a vast majority of RCM simulations does not capture the strong observed temperature rise. This discrepancy is in part related to the widespread use of constant aerosol representations in RCMs, and emerges most clearly during summer, i.e. the period of strong insolation. Thereby it also affects (changes in) heat extremes even more strongly than the mean warming. This warming mismatch is, crucially, not restricted to the past but also affects climate projections. Several European national climate services of several European countries still rely on these simulations and solutions are required.

Here, we present a novel method to adjust the large-scale warming in RCM simulations based on a reference such as observations or other model simulations. In particular, we re-assemble RCM simulations to match the long-term annual mean temperature evolution over Western Europe in state-of-the-art GCMs, which show less (or no) underestimation of the observed summer warming than the RCMs. We demonstrate that our approach preserves the high-resolution information provided by the RCMs, but ensures consistency with respect to both historic as well as projected large-scale warming. It employs existing regional climate information without the use of interpolation methods, and, as the re-assembling is performed based solely on yearly average temperatures, ensures consistency among different climate variables. We show how correcting European warming affects projections of both the mean state as well as weather extremes at the national level, and illustrate results for Switzerland, a small country characterized by complex orography. 

How to cite: Börsig, S., Schumacher, D. L., Hauser, M., Fischer, E., and Seneviratne, S. I.: Bias-adjusting for underestimated large-scale European warming in regional climate model simulations and implications for future extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18186, https://doi.org/10.5194/egusphere-egu24-18186, 2024.

EGU24-18422 | ECS | Orals | CL5.5 | Highlight

Effects of improved land surface processes in the regional climate model REMO on climate means and extremes in Mainland Southeast Asia 

Daniel Abel, Katrin Ziegler, Felix Pollinger, and Heiko Paeth

The representation of land surface processes is crucial to reduce biases of climate model simulations and increase their reliability. Thus, our study examines the effects of recent improvements of the regional climate model REMO2015 related to soil hydrological and vegetation processes and their interactions with the atmosphere. In detail, a multilayer soil scheme and an interactive vegetation module are combined with each other and substitute the former single layer scheme and static vegetation being used in the recent CORDEX-CORE simulations.

We investigate the effect of the improvements on the climatology and the annual cycle of different variables relevant for the land surface-atmosphere process chain including soil moisture, LAI, evapotranspiration, and 2m temperature. We further study the simulation’s performance of selected warm and dry events. As benchmarks, we consider different validation datasets and compare our simulations with the former REMO2015 model version as well as with recent simulations from CORDEX-CORE covering the study area.

How to cite: Abel, D., Ziegler, K., Pollinger, F., and Paeth, H.: Effects of improved land surface processes in the regional climate model REMO on climate means and extremes in Mainland Southeast Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18422, https://doi.org/10.5194/egusphere-egu24-18422, 2024.

EGU24-19233 | ECS | Orals | CL5.5

Better than Multi-Model Means: combining climate models using multivariate graph cuts for improved CMIP6 projections 

Lucas Schmutz, Soulivanh Thao, Mathieu Vrac, Denis Allard, and Grégoire Mariethoz

Various approaches have been proposed to combine individual climate models and extract a robust signal from an ensemble, such as the Multi-Model Mean or the weighted Multi-Model Mean. However, they often rely on weights that are applied to models globally, overlooking the fact that individual models often demonstrate strengths in specific regions. This suggests that a more localized approach could improve climate projections based on models ensembles.

So far, the only approach that really exploits the regional strengths of different models over multi-decadal timescales is the graph cuts approach (Thao et al., 2022). It consists in selecting for each grid point the most appropriate model, while at the same time considering the overall spatial consistency of the resulting field. Although this method showed encouraging results, outperforming other combination approaches, it is limited to optimizing for one variable, resulting in an inconsistent model selection for each and thus a loss of the multivariate relationships observed in the models. For instance it is known that precipitation and temperature are physically linked. Therefore having an independent model combination for each variable can result in inconsistencies. Moreover, the method was only applicable to multi-decadal averages, not allowing for retrieving distributional properties of the combined models such as extreme events.

Here we present a series of improvements of graph cuts enabling to combine distributions of daily-means while preserving multivariate relationships, thus better capturing the complete span of climate dynamics. Using the Hellinger distance to measure model performance, we are able to select, at each grid location, the model that best represents the joint distribution of the target variables while minimizing the apparition of unrealistic discontinuities in the resulting fields. The resulting projections display more realistic extremes and compound events representations.

 

REFERENCES 

Thao, S., Garvik, M., Mariethoz, G., & Vrac, M. (2022). Combining global climate models using graph cuts. Climate Dynamics, February. https://doi.org/10.1007/s00382-022-06213-4

How to cite: Schmutz, L., Thao, S., Vrac, M., Allard, D., and Mariethoz, G.: Better than Multi-Model Means: combining climate models using multivariate graph cuts for improved CMIP6 projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19233, https://doi.org/10.5194/egusphere-egu24-19233, 2024.

EGU24-19356 | Posters on site | CL5.5

A ranking-based sub-selection of the climate ensemble for climate impact studies 

Anna E. Sikorska-Senoner, Jan Rajczak, Massimiliano Zappa, and Sven Kotlarski

Impact modelling requires fine-scale climate information to simulate possible impacts of climate change on different sectors such as agriculture, water management or food production. Such impact models are run at a much finer spatial and temporal resolution than global or regional climate models, and therefore a pre-selection of climate model chains is required due to the computational limitations of these models. To date, there is no structured guidance for practitioners and impact modelers on how to select climate model chains. This is also the case for the Swiss Climate Scenarios (CH2018), which main products are usually communicated to the users as median, upper and lower estimates calculated for each product and time slice individually.

In this work, we present a new sub-selection climate ensemble method tailored to the users’ needs and the desired emission scenario (Representative Concentration Pathways, RCP). The method builds on the core statements of the CH2018, i.e., droughts, heat waves, heavy rainfalls, and snow-scarce winters, and complements them with three further application cases, i.e., temperature, precipitation, combined temperature and precipitation. For each application case and each RCP, three representative climate model chains are selected from the full ensemble to cover the range of the climate change signal. These include one chain corresponding to the upper, middle and lower limits of the ensemble range. The selection of climate model chains is based on the climate change signals calculated for a set of pre-selected climate indicators (e.g., mean temperature or number of hot days). Next, each climate model chain is ranked for each climate indicator according to its climate change signal calculated between the end of the century and the CH2018 reference period (i.e., 2070-2099 vs. 1981-2010). This ranking is used to divide the models into three terciles, representing the upper, lower and middle bounds of the ensemble. For each tercile, one climate model chain is next selected that best meets the selection criteria. As a result, a sub-selected ensemble with three climate model chains is proposed to the users.

The method has been developed for Switzerland and five major Swiss regions using the CH2018 GRIDDED dataset, which contains of 68 daily, transient and bias-corrected simulations of climate model chains covering the simulation period of 1981-2099. The method allows the CH2018 users to choose from three RCPs (RCP2.6, RCP4.5 and RCP8.5) and seven application cases to obtain a set of three representative climate model chains. The selected climate model chains were next successfully implemented in a hydrological impact model to assess their applicability for assessing climate impacts on hydrological variables. The method is very flexible and can easily be applied to a new or an extended climate model ensemble or to newly defined application cases.

How to cite: Sikorska-Senoner, A. E., Rajczak, J., Zappa, M., and Kotlarski, S.: A ranking-based sub-selection of the climate ensemble for climate impact studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19356, https://doi.org/10.5194/egusphere-egu24-19356, 2024.

EGU24-19815 | ECS | Posters on site | CL5.5 | Highlight

Urban hot spots of Global Temperature of Emergence of several CIDs for the biggest cities in the CORDEX domains 

Natalia Zazulie, Francesca Raffaele, and Erika Coppola
One important type of information for stakeholders is the time of emergence (TOE) of a particular climatic impact-driver (CID) in a specific region as reported also in the latest IPCC AR6. The TOE is the time when a certain signal emerges from the natural variability, thus it is an indicator of the magnitude of the climate change signal and it can be very important in a risk framework for mitigation purposes. Moreover, a focus on big cities and urbanized areas is becoming more and more crucial to plan adaptation strategies.
The Euro-CORDEX regional climate projections, together with the CORDEX-CORE ones, are a good starting point to look at the impact of urbanization on climate change since most of the models in those ensembles are able to detect urban areas and use an urban model parametrization. In this study, we use the available CORDEX ensembles to compute tailored CIDs for some big urban areas all over the world, in order to understand which is the role of the urban effect in enhancing or dumping the specific signal compared to the more rural regions.
The analysis will be done at several resolutions according to the data availability to assess the need for higher-resolution information. As expected urban areas show an exacerbation of the extreme climate signal for several CIDs highlighting the importance of the development of tailored local adaptation strategies.
 
 
 
 
 
 

How to cite: Zazulie, N., Raffaele, F., and Coppola, E.: Urban hot spots of Global Temperature of Emergence of several CIDs for the biggest cities in the CORDEX domains, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19815, https://doi.org/10.5194/egusphere-egu24-19815, 2024.

EGU24-19984 | ECS | Orals | CL5.5

Change of winter climate indicators over the Carpathian Basin 

Péter Szabó and Rita Pongrácz

Winter phenomena such as fog and freezing rain can significantly impact our daily lives by creating hazardous conditions for transportation and other outdoor activities. Dense fog reduces visibility, leading to traffic disruptions and potential accidents on roads, while freezing rain leaves surfaces with a layer of ice with high risks of falls and slide resulting in personal injuries, in addition, both can disrupt air travel as well. The Carpathian Basin can experience an increased occurrence and persistence of fog due to its unique geographical features, such as low-lying areas, lower wind speed, and river valleys that facilitate temperature inversions. Freezing rain is also prevalent in the Carpathian Basin when raindrops of warmer air masses from the Mediterranean fall through a sub-freezing, inversional layer of air before reaching the ground.

To assess these impacts, we created a methodology based on daily, gridded data sets: we analyzed daily minimum and mean temperature, mean relative humidity, and wind speed for the fog from the best available, homogenized, high-resolution HuClim observational database. For the freezing rain, we collected hourly variables of temperature, total precipitation, and snow from the high-resolution, observation-based but modeled reanalysis of ERA5-Land. For the future, we assessed corrected, daily variables from an ensemble of EURO-CORDEX regional climate model simulations. Several scenarios were taken into account for the effects of human activity: RCP2.6 is a scenario aiming at 2 °C global warming by 2100, RCP4.5 urges strong mitigation from 2040, while RCP8.5 is a non-mitigation scenario.

Results suggest that the number of foggy days slightly decreased over parts of the area of interest in the last few decades, but freezing rain did not change remarkably. Regarding the future, the days with fog would decrease significantly following the RCP8.5 scenario, especially by the end of the 21st century, while they would not change much with the RCP2.6. These are one of the rare positive impacts of regional climate change, however, it does not compensate for the adverse effects of anthropogenic climate change.

How to cite: Szabó, P. and Pongrácz, R.: Change of winter climate indicators over the Carpathian Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19984, https://doi.org/10.5194/egusphere-egu24-19984, 2024.

EGU24-20302 | Orals | CL5.5 | Highlight

CORDEX Flagship Pilot Study URB-RCC – Case Studies on Urban Environment Implementation 

Tomas Halenka, Michal Belda, Natália Crespo, Gaby Langendijk, and Peter Hoffmann

Cities play a fundamental role on climate at local to regional scales through modification of heat and moisture fluxes, as well as affecting local atmospheric chemistry and composition, alongside air-pollution dispersion. Vice versa, regional climate change impacts urban areas and is expected to increasingly affect cities and their citizens in the upcoming decades. Indeed, the share of the population living in urban areas is growing, and is projected to reach about 70 % of the world population up to 2050. Urban impact is especially critical in connection to extreme events, for instance heat waves with extremely high temperature exacerbated by the urban heat island effect, in particular during night-time, with significant consequences for human health. Additionally, from the perspective of recent regional climate model development with increasing resolution down to the city scale, proper parameterization of urban processes plays an important role to understand local/regional climate change.  

The inclusion of the individual urban processes affecting energy balance and transport (i.e. heat, humidity, momentum fluxes, emissions) via special urban land-surface interaction parameterization of distinct local processes becomes vital to simulate the urban effects properly. This will enable improved assessment of climate change impacts in the cities and inform adaptation and/or mitigation options by urban decision-makers, as well as adequately prepare for climate related risks (e.g. heat waves, smog conditions etc.). Cities are becoming one of the most vulnerable environments under climate change. Similarly as WCRP, CORDEX community identified cities to be a prime scientific challenge. Therefore, we introduced this topic to the CORDEX platform, within the framework of so-called flagship pilot studies. Main aims of this activity will be presented together with a call for participation in ensemble experiment for selected city following adopted coordinated simulations protocol.

Preliminary results from the analysis of first experiments covering specific case studies, i.e. strong heat wave as an important factor in the urban effects, and strong convective episode to study the convection permitting RCMs performance in urban environment, will be presented. The ensemble of participated teams for selected city – Paris - will be analysed and the first results based on this ensemble will be shown.

How to cite: Halenka, T., Belda, M., Crespo, N., Langendijk, G., and Hoffmann, P.: CORDEX Flagship Pilot Study URB-RCC – Case Studies on Urban Environment Implementation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20302, https://doi.org/10.5194/egusphere-egu24-20302, 2024.

EGU24-20375 | ECS | Posters on site | CL5.5

A multidecadal high resolution atmospheric and dust dataset for the Middle East and North Africa 

Platon Patlakas, Ioannis Chaniotis, Christos Stathopoulos, Andreas Kallos, Ishaq Sulaymon, Alaa Mhawish, and Jumaan Alqahtani

The Middle East and North African region (MENA) is characterized by unique climate patterns due to its complex topography and large-scale atmospheric circulation. On top of that, MENA is significantly affected by impacts associated with climate change. Moreover, desert dust serves as a crucial component in shaping the regional climate. It is present in high concentrations throughout the year and significantly modifies the radiative budget and energy distribution of the atmosphere. Dust particles can also have a crucial role in cloud physics and shape the evolution of extreme events. Dust storms, however, have a more direct effect on communities, influencing health, transportation, aviation and various socioeconomic activities that are crucial for the local economies.

To this end, a multidecadal high resolution atmospheric and dust dataset is developed. The exploration of this comprehensive database can enable the identification of trends, anomalies, and potential climate shifts, in several variables presenting a valuable resource for researchers, policymakers, and climate scientists. Therefore, this effort not only contributes to a better understanding of the regional climate system but also serves as a basis for future studies and mitigation strategies.

How to cite: Patlakas, P., Chaniotis, I., Stathopoulos, C., Kallos, A., Sulaymon, I., Mhawish, A., and Alqahtani, J.: A multidecadal high resolution atmospheric and dust dataset for the Middle East and North Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20375, https://doi.org/10.5194/egusphere-egu24-20375, 2024.

EGU24-20532 | ECS | Posters on site | CL5.5

 Assessment of CMIP6 Regional Climate Model Performance for Wind Speed in Ireland.  

Kavya Rajagopal, Dr. Stephen Nash, and Dr. Paul Nolan

This study focuses on the validation of wind speed simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) against observed station data in Ireland.The aim is to assess the performance of 10 CMIP6 regional climate model (RCM) ensembles in capturing the spatiotemporal variability of wind speeds, a crucial parameter for various applicationssuch as renewable energy assessments and climate impact studies.

Station observation data for wind speed are obtained from 7 Met Éireann weather stations across Ireland, providing a comprehensive and high-quality dataset for model evaluation from 1981 to 2010.The 10 CMIP6 model ensembles are selected based on their representation of historical climate conditions, and a detailed comparison is conducted for various temporal scales.

Key metrics, such as bias, root mean square error, and correlation coefficients, percentiles are employed to quantify the agreement between CMIP6 model outputs and observed wind speed data.Additionally, annual, and monthly climatological patterns of wind speed across different regions of Ireland are examined to identify potential biases or deficiencies in model performance.

The COSMO-CLM regional models overestimate similar patterns, while the WRF simulates underestimated wind speeds for the stations. Despite these notable differences, all models accurately predicted the windiest months, which are January and February, and the least windy months, which are July and August. The windiest location in Ireland is also well represented by the models, which are Malin Head in County Donegal, where winds peak in January while the lowest wind speed is recorded at Valentia Observatory in July.

 The findings of this validation study contribute to our understanding of the reliability and accuracy of CMIP6 model simulations in reproducing wind speed characteristics specific to Ireland. The outcomes have implications for climate model improvement and can enhance the credibility of future climate projections for the region. Improved confidence in wind speed simulations is crucial for supporting informed decision-making in areas such as renewable energy planning, infrastructure design, and climate change adaptation strategies.

How to cite: Rajagopal, K., Nash, Dr. S., and Nolan, Dr. P.:  Assessment of CMIP6 Regional Climate Model Performance for Wind Speed in Ireland. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20532, https://doi.org/10.5194/egusphere-egu24-20532, 2024.

The fifth version of the regional climate model (RegCM5) has recently been released, incorporating updates in several model components such as the dynamic core and physical parameterizations. Traditionally, sensitivity tests based on random selection have been employed to identify the optimal sets from various combinations of model dynamics and physics. However, this approach is largely limited by computing power, often failing to explore the complete range of possible combinations necessary for an accurate representation of the regional climate. To overcome these limitations, advanced optimization techniques have emerged to efficiently explore the complete range of possible combinations, without relying solely on random-based sensitivity tests.  In this study, we employ a micro-genetic algorithm (micro-GA) for combinatorial optimization of the dynamic cores, cumulus parameterizations, and microphysics parameterizations in RegCM5. The model domains consist of one 20km mother domain covering the majority of East Asia, and two 2.5km nested domains covering the Yangtze River Delta (YRD) and Pearl River Delta (PRD), two densely populated regions in China. The focus is on conducting comparative assessments of simulated precipitation and temperature patterns in Southeastern China based on a series of experiments using the coupled RegCM5-micro-GA interface. The findings from this study will provide valuable insights to facilitate the wider use of RegCM5 by customizing its performance over the target regions.  

[Acknowledgements] This research was supported by project GRF16308722, which was funded by the Research Grants Council (RGC) of Hong Kong.

How to cite: Im, E.-S., Zhou, Z., Yoon, J. W., and Park, S. K.: Combinatorial optimization of dynamics and physics in RegCM5 using a micro-genetic algorithm for precipitation and temperature simulations in Southeastern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20577, https://doi.org/10.5194/egusphere-egu24-20577, 2024.

EGU24-20718 | ECS | Posters on site | CL5.5 | Highlight

Exploring Variability and Uncertainty in Precipitation within Earth System Models Using Parametric Estimates from the Precipitation Emulator MESMER-M-TP 

Sarah Schöngart, Peter Pfleiderer, and Carl-Friedrich Schleußner

We investigate the potential of utilizing the precipitation emulator MESMER-M-TP as a tool to gain insights into precipitation patterns derived from Earth System Models (ESMs). MESMER-M-TP generates spatially explicit, monthly mean precipitation fields (2.5°x2.5° resolution) by employing spatially explicit, monthly mean temperatures as input. The approach involves modeling local precipitation as the response variable of a generalized linear model (GLM) with local modes of temperature variability as predictive variables.

The emulator is trained on 24 different ESMs from the CMIP6 dataset based on a single ensemble member across Shared Socioeconomic Pathways (SSPs). This results in a set of 24 distinct parameter sets for each month and location. These parameters link precipitation to temperature via the GLM, providing a basis for quantitatively analyzing inter-model differences and parametric uncertainties. We focus on three key aspects: (1) Investigating parameter distributions to identify locations and months with poor inter-model agreement and understanding how individual predictors contribute to overall discrepancies. (2) Utilizing a clustering-based approach to group the 24 climate models based on their parameters, revealing consistency with genealogy and code streams of CMIP6 model development. (3) Exploring the sensitivity of the emulator to parameter choices.

This explorative analysis offers valuable insights into the intricacies of precipitation modeling in ESMs by providing a quantitative understanding of inter-model variations and exploring sampling strategies that take inter-model variations into acocunt.

How to cite: Schöngart, S., Pfleiderer, P., and Schleußner, C.-F.: Exploring Variability and Uncertainty in Precipitation within Earth System Models Using Parametric Estimates from the Precipitation Emulator MESMER-M-TP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20718, https://doi.org/10.5194/egusphere-egu24-20718, 2024.

EGU24-298 | ECS | Posters on site | CL5.6

Sensitivity of the CNRM-CM6-1 ocean-climate model to freshwater inputs from Antarctica 

Joachim Piret, Sarah Berthet, and Aurore Voldoire

Meltwater fluxes from Antarctica are in general poorly represented in ocean models in terms of quantity and spatio-temporal variability. These meltwater fluxes impact the stratification and the circulation of the Southern Ocean, which is a key component of the climate system. In particular, the opening of deep water polynyas depends, amongst other, on ocean stratification. In turn, these polynyas then, for instance, impact the ventilation of the Southern Ocean and the ocean-atmosphere exchanges of heat. 

 
In this study, we explore how the ocean and sea-ice components of the CNRM-CM6-1 climate model are affected by the spatial distribution and magnitude of meltwater fluxes through three sensitivity experiments. In a first experiment, only a constant basal melting (restricted at the coast) is used as forcing. In a second experiment, only melting from monthly drifting icebergs is used. Finally, in a third experiment, both melting fluxes are used to force the   model.          

                                                                                                                                                                       

In our experiments, several deep water polynyas are diagnosed in the Weddell Sea and offshore of Pridz Bay. We find that these polynyas are places of deep-water formation impacting water masses properties over the entire column.  In this study we analyze how the magnitude, occurrences and frequencies of occurrences of these polynyas are affected by the representation of the meltwater fluxes from Antarctica. We also diagnosed a deep water polynya around Maud Rise with features similar to the giant polynya observed every winter between 1974 and 1976. 

 

Understanding the opening of these polynyas is challenging, since this requires an analysis on the stability of the water column and disentangling the role of external forcing (i.e. the role of the meltwater fluxes) from the model’s internal variability. 

How to cite: Piret, J., Berthet, S., and Voldoire, A.: Sensitivity of the CNRM-CM6-1 ocean-climate model to freshwater inputs from Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-298, https://doi.org/10.5194/egusphere-egu24-298, 2024.

EGU24-1617 | Posters on site | CL5.6

ACCESS-NRI: Supporting Climate Science through Robust Model Evaluation and Community-Driven Strategies 

Romain Beucher, Michael G. Tetley, Yousong Zeng, Felicity Chun, Dougal Squire, Owen Kaluza, Kelsey Druken, and Andy Hogg

The Australian Earth System Simulator (ACCESS-NRI) is a national research infrastructure designed to support the development and research of the Australian Community Climate and Earth System Simulator (ACCESS). With a strategic goal to enhance the quality and performance of the ACCESS suite of model configurations, ACCESS-NRI supports the open development and release of a Model Evaluation and Diagnostics (MED) framework for the Australian Earth system modeling community. 

In climate science, the evaluation of computational models plays a pivotal role in assessing their performance and reliability in simulating the Earth's complex climate system. This process involves a comprehensive analysis of model predictions against observed data to determine accuracy and utility. Through meticulous model evaluation, scientists gain insights into real-world climate processes, identify model strengths and weaknesses, and refine models to enhance predictive capabilities. 

Integral to international climate change assessments, climate models are crucial for shaping policies and guiding investments in climate action. Accurate simulations, reliant on precise modeling of climate physics and realistic forcing conditions, such as CO2 emissions, are fundamental to these endeavors. However, the development of these models is a protracted, iterative process requiring constant evaluation of performance and accuracy. Users seek to compare model simulations derived from diverse configurations, necessitating dedicated tools, workflows, and access to diverse data sources within high-performance computing environments. 

The development of tools and methods is integral to this initiative, providing essential support for the incorporation of model evaluation within code development cycles. The presentation explores community-driven strategies designed to streamline the evaluation of the ACCESS suite of models, addressing specific requirements and constraints associated with the World Climate Research Programme’s (WCRP) Coupled Model Intercomparison Project phase 7 (CMIP7) and its future iterations. Emphasis is placed on the incorporation of model evaluation within code development cycles. 

 

How to cite: Beucher, R., Tetley, M. G., Zeng, Y., Chun, F., Squire, D., Kaluza, O., Druken, K., and Hogg, A.: ACCESS-NRI: Supporting Climate Science through Robust Model Evaluation and Community-Driven Strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1617, https://doi.org/10.5194/egusphere-egu24-1617, 2024.

EGU24-1740 | ECS | Posters on site | CL5.6

Introduction of tropospheric chemistry in the CNRM Earth System Model (ESM): towards methane emission-driven capability. 

Martin Cussac, Martine Michou, Pierre Nabat, Béatrice Josse, and Pelletier Sophie

Methane (CH4) is the second most important greenhouse gas after carbon dioxide (CO2), and improving the representation of its cycle in climate models is a key step to reduce uncertainties in climate projections. Its main sink is chemical removal through oxidation with hydroxyl radicals (OH) in the troposphere, which are produced during the photolysis of ozone (O3) in presence of water vapour. This process is an example of the complex interactions between methane and climate system, highlighting the necessity to have an explicit and interactive representation of atmospheric composition in Earth System Models. Here we present the introduction of two tropospheric/stratospheric chemical schemes of various complexities in ARPEGE-Climat 7.0, the future version of the atmospheric component of CNRM-ESM, and the impact on methane representation. This work includes the addition and changes of multiple processes at stakes in the troposphere, for instance emissions, deposition or production of NOx by lightning strikes. We first present an evaluation of tropospheric air composition in our model including all the aforementioned developments. Diagnostics from both chemical schemes in AMIP-type simulations are compared to observations and to state of the art atmospheric composition reanalyses such as the CAMS reanalysis. We highlight, in particular, the performance of both chemical schemes in terms of biases and seasonal cycles of major tropospheric tracers like O3, CO or NO2. We also compute from RFMIP-type simulations the ozone ERF, and compare it to previous estimates. Secondly, we present an evaluation of the behaviour of pre-industrial simulations in a methane “emission-driven” mode. These simulations are compared to more classical “concentration-driven” simulations in terms of global methane budget and methane chemical lifetime.

How to cite: Cussac, M., Michou, M., Nabat, P., Josse, B., and Sophie, P.: Introduction of tropospheric chemistry in the CNRM Earth System Model (ESM): towards methane emission-driven capability., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1740, https://doi.org/10.5194/egusphere-egu24-1740, 2024.

EGU24-1912 | ECS | Posters on site | CL5.6

Evaluation of the EC-EARTH3-VEG climate model in reproducing the evolution of maximum and minimum air temperatures in Brazil 

Fernanda De Amorim Formigoni, Catarina De Abreu Heil, Juliana Da Costa Mendes Reis, Priscila Esposte Coutinho, Lívia Sancho, and Marcio Cataldi

According to the Sixth Report of the Intergovernmental Panel on Climate Change (IPCC), published in 2023, between 2011 and 2020, global surface temperatures increased by 1.1°C compared to the period 1850-1900. This upward trend in temperature is related to changes in the observed climate patterns, which will potentially lead to a greater incidence of extreme weather events and ecosystem changes, as well as impacting the health of human populations. In Brazil, this scenario could also result in biodiversity losses, reduced agricultural productivity and changes in the availability of water resources, with consequences for the country's economy and energy security. Considering this context, this study aims to evaluate the ability of the EC-Earth3-Veg model, part of the Coupled Model Intercomparison Project Phase 6 (CMIP6), to reproduce the evolution of maximum and minimum air temperatures at 2 meters in Brazil during the historical period, at intervals between 1961 and 2014, comparing it with ERA5 reanalysis data. The CMIP6 data was interpolated to the ERA5 grid to carry out the desired analysis. Based on this, it was observed that EC-Earth3-Veg was able to reproduce the historical climatology for Brazil but showed climatological differences when compared to ERA5 in the four periods observed. It is common among the periods analyzed that the further north of the country is warmer, with maximum temperatures in summer and autumn. In winter and spring, the same happens in the eastern part of the North, the Center-West, and the northern part of the Southeast of Brazil. In the fall, the Northeast and Midwest show cooler highs. The period in which the model's results were closest to ERA5 was from 1961 to 1990, especially for minimum temperatures in summer and winter. Even so, in the fall and spring of this period, the model showed warming in relation to the minimums in the South, and, in all the quarterly cut-outs, it showed cooling in the minimums near the Northeast. In general, certain regional and seasonal patterns were observed in the results, which may indicate a limitation of the model in terms of horizontal resolution in considering a more characteristic atmosphere for Brazil. In the southern region, for example, the maximum and minimum temperatures in the model showed warming. This may indicate that the model is limited in its horizontal resolution and does not consider an atmosphere that is more characteristic of Brazil. Therefore, to improve the model's performance in simulating the climate in Brazil, it is necessary to correct the bias and use EC-Earth3-Veg in conjunction with other models to reduce systematic errors. This study aims to replicate this work for other models.

How to cite: De Amorim Formigoni, F., De Abreu Heil, C., Da Costa Mendes Reis, J., Esposte Coutinho, P., Sancho, L., and Cataldi, M.: Evaluation of the EC-EARTH3-VEG climate model in reproducing the evolution of maximum and minimum air temperatures in Brazil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1912, https://doi.org/10.5194/egusphere-egu24-1912, 2024.

EGU24-2831 | Orals | CL5.6

Efficient spin-up of Earth System Models using sequence acceleration 

Samar Khatiwala and Eleanor Burke

The ocean and land carbon cycles plays a critical role in the climate system and are key components of the Earth System Models (ESMs) used to project future changes in the environment. However, their slow adjustment time also hinders effective use of ESMs because of the enormous computational resources required to integrate them to a pre-industrial quasi-equilibrium, a prerequisite for performing any simulations with these models and, in particular, identifying the human impact on climate. Here, a novel solution to this ``spin-up'' problem, regarded as one of the grand challenges in climate science, is shown to accelerate the equilibration of state-of-the-art marine biogeochemical models typical of those embedded in ESMs by over an order of magnitude. Based on a ``sequence acceleration'' method originally developed in the context of electronic structure problems, the new technique can be applied in a ``black box'' fashion to any existing model. Even under the challenging protocols used to spin-up ESMs for the IPCC Coupled Model Intercomparison Project, which can take up to two years on even some of the most powerful supercomputers, the new algorithm can reduce simulation times by a factor of 5, with preliminary results suggesting that complex land surface models can be similarly accelerated. The ability to efficiently spin-up ESMs would enable for the first time a quantification of major parametric uncertainties in these models, lead to more accurate estimates of metrics such as climate sensitivity, and allow increased model resolution beyond what is currently feasible.

How to cite: Khatiwala, S. and Burke, E.: Efficient spin-up of Earth System Models using sequence acceleration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2831, https://doi.org/10.5194/egusphere-egu24-2831, 2024.

EGU24-3432 | ECS | Orals | CL5.6

Evaluation of precipitation and ITCZ characteristics in CMIP6 models 

Andreas Karpasitis, George Zittis, and Panos Hadjinicolaou

The Intertropical Convergence Zone (ITCZ) is a band of low pressure near the equator, where the trade winds converge. It is usually accompanied by cloudiness and heavy precipitation, and it migrates northward and southward, following the sun in different seasons. Climate models often misrepresent key atmospheric processes, including ITCZ's position, width and strength. As a result, biases in the modeled precipitation are also common in tropical and sub-tropical regions, such as the Indian subcontinent and parts of South America. Here, we assess the skill of four state-of-the-art Earth System Models in representing key ITCZ characteristics and the associated precipitation. The four ESMs under investigation are EC-EARTH, CNRM-ESM, IPSL-ESM, and UKESM. Besides the CMIP6 version of the aforementioned models, we also aim to evaluate post-CMIP6 simulations, which are currently under development in the framework of the OptimESM Horizon Europe project (https://optimesm-he.eu/). These post-CMIP6 models include advancements in the representation of physical, biogeochemical and biophysical processes. As a reference dataset, we use the ERA5 reanalysis data. Firstly, we divide the world into eight longitudinal zones and then calculate the zonal averages. For each season, we define the ITCZ location as the latitude where there is a peak in the 500hPa vertical velocity, while we consider the edges of the ITCZ at the latitudes where the 500hPa vertical velocity becomes zero. The strength of the ITCZ is defined as the value of the rainfall peak associated with the peak in the vertical velocity field. The analysis is performed on an annual basis, for each year from 1981 through 2010, and the corresponding peaks are clustered. The long-term characteristics of the ITCZ from the ESMs are compared to those from the ERA5 to understand the processes that drive precipitation biases in the global tropics.

How to cite: Karpasitis, A., Zittis, G., and Hadjinicolaou, P.: Evaluation of precipitation and ITCZ characteristics in CMIP6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3432, https://doi.org/10.5194/egusphere-egu24-3432, 2024.

EGU24-3938 | Posters on site | CL5.6

Live monitoring, diagnostics and data management for the ACCESS suite of Earth-system simulations. 

Michael Tetley, Dougal Squire, and Romain Beucher

As global Earth-System simulations rapidly increase in complexity as a direct result of available compute resources and advancing scientific model development, monitoring long-running models and managing associated big data outputs has become increasingly difficult. This has inspired a need for open community-focussed software tools that provide intuitive and efficient HPC-native functionality to accurately evaluate live model performance and behaviour, perform diagnostic scientific analyses, compare current results with alternative or reference models, and generate standardised data outputs. Addressing these challenges, we present a new community-driven open-source project Model Live Diagnostics (MLD) which integrates the ACCESS-NRI Intake Catalog API, together forming part of The Australian Earth-System Simulator (ACCESS-NRI) Model Evaluation and Diagnostics (MED) framework supporting climate science research within the Australian Community Climate and Earth System Simulator (ACCESS).

 

MLD is an open-source Python package optimised for use in JupyterLab sessions on the Australian NCI supercomputer Gadi. The primary purpose of MLD is to provide a simple, easy to use and accessible framework for the ACCESS modelling community to check, monitor, visualise and evaluate live running Earth-System model behaviour and progress. Utilising the ACCESS-NRI Intake Catalog API, MLD monitors a given model output data directory on Gadi, dynamically building an intake cataog of the most up-to-date data and automatically generating interactive plots to visualise model variables. From these data, MLD provides functions to perform light-weight diagnostic calculations, compare and plot results against reference models, and export data in standard Xarray format for integration into user workflows. MLD can be installed manually via Conda or PyPI, it comes pre-installed in existing Conda environments on Gadi, and the full source code is available on the project Github repository. MLD currently supports Earth System Model 1.5 (ACCESS-ESM1.5), Model for Ocean/Sea Ice (ACCESS-OM2) and Coupled Model 2 (ACCESS-CM2).

How to cite: Tetley, M., Squire, D., and Beucher, R.: Live monitoring, diagnostics and data management for the ACCESS suite of Earth-system simulations., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3938, https://doi.org/10.5194/egusphere-egu24-3938, 2024.

EGU24-4037 | Orals | CL5.6

Revisiting the performance of CMIP6 models in the Arctic: Concerns on benchmarking climate models 

Shuting Yang, Tian Tian, Jacob L. Hoyer, Pia Nielsen-Englyst, and Suman Singha

Climate models are known to have difficulty in simulating the present day climate in the Arctic. Many studies, including the most recent Inter-governmental Panel on Climate Change Sixth Assessment Report (IPCC AR6), report that, comparing to reanalysis datasets such as ERA5 as reference, climate models participating the past phases of the Coupled Model Intercomparison Project (CMIP) simulate a too cold Arctic. However, recent studies reveal substantial warm biases over sea ice surface in global atmospheric reanalyses due to missing representation of physical processes such as the snow layer on top of the sea-ice.

In this work we revisit the so-called long-standing climate model bias in the Arctic by using a new, satellite-derived near surface air temperature (T2m) dataset for the Arctic sea ice region as an alternative reference to the commonly used reanalysis data ERA5. This observational T2m dataset is derived from the satellite based on DMI/CMEMS daily gap-free (so called L4) sea surface temperature and sea ice surface temperature climate data record, spanning from 1st January 1982 to 31st May 2021, covering the Arctic region (> 58 ◦N). We show that, in comparison with the new observational dataset, the ERA5 reanalysis exhibits widespread warm biases exceeding 2℃ over sea ice in the central Arctic, particularly during winter when the warm bias may be as large as 6-10℃. In contrast, the CMIP6 model ensemble demonstrates reasonable performance, with an annual mean bias less than ±1℃ in the same region. We also find that the CMIP6 model mean slightly outperforms the ERA5 in capturing the observed warming trend over the central Arctic region where is fully covered by sea ice with concentration of more than 70%. Outside of this region, it is evident that ERA5 aligns well with observations, while CMIP6 models show large cold bias in the North Atlantic marginal ice zone, consistent with the well-documented results in the past.

Our results challenge the current assessment of climate models in the central Arctic, suggesting that relying on existing reanalyses datasets as a reference may underestimate the climate models creditability in the region. It is thus imperative to integrate new observational data for benchmarking climate models in the Arctic region.

How to cite: Yang, S., Tian, T., Hoyer, J. L., Nielsen-Englyst, P., and Singha, S.: Revisiting the performance of CMIP6 models in the Arctic: Concerns on benchmarking climate models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4037, https://doi.org/10.5194/egusphere-egu24-4037, 2024.

EGU24-6106 | ECS | Orals | CL5.6

On the implementation of Leith viscosities in NEMO: Results from a forced global ocean model 

Thomas Wilder and Till Kuhlbrodt

In CMIP6, eddy-permitting models (notably HadGEM3-GC3.1 N216ORCA025) were found to perform poorly
against their coarse-resolution counterparts, particularly in the Southern Ocean. Compared with N96ORCA1
(1 degree), ORCA025 exhibited an enhanced warm bias, weakened Antarctic Circumpolar Transport (~ 60 Sv),
overactive Antarctic gyres, and lower Antarctic sea-ice extent and volume. The poor performance of the eddy-
permitting model has been attributed to their difficulty in representing mesoscale processes at higher latitudes.
Despite these shortcomings, eddy-permitting models remain desirable for their capacity to resolve meridional
transports of heat and carbon, and ice-ocean interactions.

The objective of this work is to improve the representation of mesoscale processes in ORCA025 through the
implementation of two viscosity schemes: 2D Leith and Quasi-Geostrophic Leith. These viscosity schemes
have been shown to improve interior mixing by mesoscale eddies in eddy-rich models. Both schemes offer a
parameterised viscosity coefficient that is flow and scale-aware, in contrast to a typical constant biharmonic
viscosity employed in N216ORCA025.

In a forced ocean configuration (GOSI9p8.0 ORCA025), both Leith schemes demonstrate a marked impact on
the ocean’s circulation and its properties compared to biharmonic viscosity. Here, the Leith schemes dampen
the eddy kinetic energy field and reduce the Antarctic circumpolar transport, with corresponding changes in
temperature and salinity fields. Additional simulations, both forced and coupled, are ongoing and may provide
further insights into the different impacts of the Leith viscosity schemes on physical processes in eddy-permitting
Earth system models.

How to cite: Wilder, T. and Kuhlbrodt, T.: On the implementation of Leith viscosities in NEMO: Results from a forced global ocean model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6106, https://doi.org/10.5194/egusphere-egu24-6106, 2024.

EGU24-7132 | Orals | CL5.6

Introduction to an open-source tool for collective Earth System Model evaluation and benchmarking: PCMDI Metrics Package (PMP) 

Jiwoo Lee, Ana Ordonez, Peter Gleckler, Paul Ullrich, Yann Planton, Bo Dong, Kristin Chang, Paul Durack, Elina Valkonen, and Julie Caron

The PCMDI Metrics Package (PMP) is an open-source Python-based framework that enables objective "quick-look" comparisons and benchmarking of Earth System Models (ESMs) against observation-based reference datasets. The PMP, which is focused primarily on atmospheric quantities, has been used for routine and systematic evaluation of thousands of simulations from the Coupled Model Intercomparison Project (CMIP). Ongoing work aims for seamless application of the tool to the next generation of CMIP (CMIP7), with an aspiration to aid modeling groups during their development cycle. The latest version of PMP offers a diverse suite of evaluation capabilities covering large- to global-scale climatology and annual cycle, variability modes such as tropical and extratropical variability modes e.g., ENSO and MJO, regional monsoons, cloud feedback, and high frequency characteristics e.g., extremes. Current work is expanding the scope of PMP to include the evaluation of the following: (1) Quasi-Biennial Oscillation (QBO) and its teleconnection to MJO, (2) atmospheric blocking and rivers leveraging Machine Learning based pattern detection algorithms, and (3) polar and high-latitude regions by implementing sectional sea-ice area metrics. The PMP is also advancing its evaluation capabilities to help evaluate higher resolution simulations such as those from the HighResMIP, cloud-resolving E3SM experiments, and regionally downscaled products. This presentation will highlight the motivation for routine model evaluation, introduce the PMP, share progress on current polar metrics, and discuss future plans and opportunities to connect with ongoing efforts.

How to cite: Lee, J., Ordonez, A., Gleckler, P., Ullrich, P., Planton, Y., Dong, B., Chang, K., Durack, P., Valkonen, E., and Caron, J.: Introduction to an open-source tool for collective Earth System Model evaluation and benchmarking: PCMDI Metrics Package (PMP), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7132, https://doi.org/10.5194/egusphere-egu24-7132, 2024.

The air-sea CO2 flux FCO2 is an important component of the global carbon budget and understanding its response to climate change is crucial to adjust mitigation pathways. Multi-linear regression supports the expectation that the balance between the CO2 partial pressures of air and the sea surface (pCO2) is the most important driver of temporal FCO2 variability. Discrepancies between state-of-the-art Earth System Models (ESMs) and gridded pCO2-products suggest that systematic biases exist across an ensemble of ESMs. In the equatorial regions, upwelling variability of carbon-rich water is biased in ESMs as modeled and observed sea surface temperature are generally uncorrelated. In the high latitudes, the climate change induced trend towards lighter sea water is overestimated in ESMs, which yields - in contrast to observations - shallower mixed layers over the contemporary period and hence a suppressed carbon supply from depth. While mixed layer depth variability and trends appear biased throughout the global ocean, this is not a determining factor for pCO2 variability in subtropical gyres. The results highlight the importance of accurately modeling hydrographic properties to obtain robust estimates of FCO2 and its variability.

How to cite: Danek, C. and Hauck, J.: Discrepancies in temporal pCO2 variability from Earth System Models and pCO2-products related to high-latitude mixed layer dynamics and equatorial upwelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8181, https://doi.org/10.5194/egusphere-egu24-8181, 2024.

EGU24-8947 | ECS | Posters on site | CL5.6

Monitoring and Benchmarking of Earth System Model Simulations with ESMValTool 

Manuel Schlund, Axel Lauer, Lisa Bock, and Birgit Hassler

Earth system models (ESMs) are important tools to improve our understanding of present-day climate and to project climate change under different plausible future scenarios. For this, ESMs are continuously improved and extended resulting in more complex models. Particularly during the model development phase, it is important to continuously monitor how well the historical climate is reproduced and to systematically analyze, evaluate, understand, and document possible shortcomings. For this, putting model biases relative to observations into the context of deviations shown by other state-of-the-art models greatly helps to assess which biases need to be addressed with higher priority. Here, we introduce the new capability of the Earth System Model Evaluation Tool (ESMValTool) to monitor running or benchmark existing simulations with observations in the context of results from the Coupled Model Intercomparison Project (CMIP). ESMValTool is an open-source community-developed diagnostics and performance metrics tool for the evaluation and analysis of ESMs. To benchmark model output, ESMValTool calculates metrics such as root mean square error (RMSE) or the coefficient of determination (R2) relative to reference datasets. This is directly compared to the same metric calculated for an ensemble of models such as CMIP6, which provides a statistical measure for the range of values that can be considered typical for state-of-the-art models. Results are displayed in different types of plots such as map plots (using stippling and hatching) or time series (via uncertainty bands). Automatic downloading of CMIP results from the Earth System Grid Federation (ESGF) makes application of ESMValTool for benchmarking of individual model simulations, for example in preparation of CMIP7, easy and very user friendly.

How to cite: Schlund, M., Lauer, A., Bock, L., and Hassler, B.: Monitoring and Benchmarking of Earth System Model Simulations with ESMValTool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8947, https://doi.org/10.5194/egusphere-egu24-8947, 2024.

EGU24-9963 | Orals | CL5.6 | Highlight

Exploring the Role of Interactive Methane in Earth System Models used for Climate Projections 

Fiona O'Connor, Gerd Folberth, Nicola Gedney, and Chris Jones

Methane plays a crucial role in the Earth System as a greenhouse gas and a tropospheric ozone precursor. However, in Phase 6 of the Coupled Model Intercomparison Project (CMIP6), Earth System Models predominantly relied on prescribed surface methane concentrations derived from historical observations or predefined future pathways. This study uses novel Earth System Model capability to investigate the impact of an emissions-driven methane cycle, including interactive wetland emissions. Specifically, we explore the influence of interactive methane on the effective radiative forcing of carbon dioxide and the model’s transient and equilibrium climate responses to changes in carbon dioxide.

The response of the climate to external forcings is intricately linked to climate feedbacks. With the inclusion of an interactive methane cycle in Earth System Models, understanding how changes in carbon dioxide and climate affect the methane cycle becomes imperative. This work critically re-evaluates the CMIP6 assessment of methane feedbacks and, for the first time, disentangles both the biophysical and radiative effects of carbon dioxide on wetland emissions and methane lifetime. 

By enabling the interaction of the biophysical and radiative effects of carbon dioxide with natural methane emissions, concentrations, and climate responses, this presentation highlights the necessity of incorporating interactive methane components in Earth System Models. Notably, this approach provides scientists with the means to assess the direct implications of methane emission reduction policies and climate feedbacks on meeting global climate and air quality targets.

How to cite: O'Connor, F., Folberth, G., Gedney, N., and Jones, C.: Exploring the Role of Interactive Methane in Earth System Models used for Climate Projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9963, https://doi.org/10.5194/egusphere-egu24-9963, 2024.

EGU24-10399 | Posters on site | CL5.6

Extreme cold events in Europe under a reduced AMOC 

Susanna Corti, Virna Loana Meccia, Claudia Simolo, and Katinka Bellomo

There is a consensus that a weakened Atlantic Meridional Overturning Circulation (AMOC) decreases mean surface temperature in the Northern Hemisphere, both over the ocean and the continents. However, the impacts of a reduced AMOC on cold extreme events have not yet been examined. We analyse the impacts of a reduced AMOC strength on extreme cold events over Europe using targeted sensitivity experiments with the EC-Earth3 climate model. Starting from a fully coupled ocean-atmosphere simulation in which the AMOC was artificially reduced, a set of atmosphere-only integrations with prescribed sea surface temperature and sea-ice cover was conducted to evaluate the effects of weakly and strongly reduced AMOC strength. Despite overall cooling, reduced AMOC leads to fewer winter cold spells in Europe. We find that the weakened AMOC intensifies near-surface meridional gradient temperature in the North Atlantic and Europe, thus providing the energy to boost the jet stream. A stronger jet stream leads to less atmospheric blocking, reducing the frequency of cold spells over Europe. Although limited to the output of one model, our results indicate that a reduced AMOC strength may play a role in shaping future climate change cold spells by modulating the strength of the jet stream and the frequency of atmospheric blocking.

How to cite: Corti, S., Meccia, V. L., Simolo, C., and Bellomo, K.: Extreme cold events in Europe under a reduced AMOC, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10399, https://doi.org/10.5194/egusphere-egu24-10399, 2024.

EGU24-10541 | ECS | Posters on site | CL5.6

Computationally efficient evaluation of Earth System Models in the presence of complex uncertainties 

Nils Weitzel, Muriel Racky, Laura Braschoß, and Kira Rehfeld

Comparing Earth System Model (ESM) simulations with in-situ, lab, and remote sensing measurements often involves analytically intractable uncertainty structures for example due to observational uncertainties, internal variability in the climate system, and limitations of ESMs. With increasing resolution of models, ensemble sizes, length of simulations, and number of observations, this can create computational bottlenecks. Making use of Monte Carlo techniques in a data cube architecture, we present a python package for efficient propagation of complex uncertainties in model-data comparison. Additionally, the package contains functionalities for visualizations of uncertainties and the computation of probabilistic score functions.

Our focus is on measurement operators, in particular so-called proxy system models that map ESM output onto proxy measurements for transient paleoclimate simulations. Proxy system models contain multiple sources of autocorrelated and non-Gaussian uncertainties due to complex proxy-climate relationships, chronological uncertainties, and processes perturbing the recorded climate signal during the sedimentation of the proxy. Thereby, we connect data cube methods for processing climate simulations with analysis techniques for point data such as those stemming from time series of paleoclimate proxy records. We demonstrate our approach by quantifying the discrepancies of temperature and forest cover changes between global proxy networks and transient simulations from the Last Glacial Maximum to present-day. Given the ongoing shift in the paleoclimate modelling community from equilibrium time-slice towards long transient simulations, our work can help integrate the evaluation of simulations from the Paleoclimate Modelling Intercomparison Project (PMIP) into CMIP7 model benchmarking. Additionally, the implemented methods are transferable to other types of observations that are subject to analytically intractable uncertainty structures.

How to cite: Weitzel, N., Racky, M., Braschoß, L., and Rehfeld, K.: Computationally efficient evaluation of Earth System Models in the presence of complex uncertainties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10541, https://doi.org/10.5194/egusphere-egu24-10541, 2024.

EGU24-11464 | Posters on site | CL5.6 | Highlight

Are early warning signals present for climate tipping points detected in CMIP6?   

Tim Lenton, Paul Ritchie, and Chris Boulton

Many elements of the climate system are believed to be at risk of tipping in the near future due to ongoing climate change. Abrupt shifts or tipping points have found to be prevalent in several of the latest generation of climate models (CMIP6) under a range of future emission scenarios. However, by observing the time series alone it is notoriously difficult to predict an upcoming tipping point. Therefore, so-called early warning indicators are needed to try to forewarn of an approaching tipping point. Two commonly used early warning signals, designed to detect critical slowing down prior to the tipping point, are to observe an increase in autocorrelation and variance. In this presentation, we assess the reliability and performance of these indicators for a range of tipping points, scenarios and models. In examples of the indicators performing poorly, we consider the potential for system specific indicators.  

How to cite: Lenton, T., Ritchie, P., and Boulton, C.: Are early warning signals present for climate tipping points detected in CMIP6?  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11464, https://doi.org/10.5194/egusphere-egu24-11464, 2024.

EGU24-12558 | Posters virtual | CL5.6

Recent developments in the Earth System Model evaluation tool 

Bouwe Andela, Birgit Hassler, and Manuel Schlund

ESMValTool (Earth System Model eValuation Tool) is open-source, community-developed software for the evaluation of Earth system models, mainly in the context of multi-model analyses, e.g. the Coupled Model Intercomparison Project (CMIP). ESMValTool provides a large number of “recipes” that reproduce published figures, for example, some of the figures found in reports of the Intergovernmental Panel on Climate Change (IPCC). ESMValCore, the framework powering ESMValTool, provides capabilities that make it easy to work with data produced for CMIP as well as related observational and reanalysis data, e.g. discovering, downloading, and preprocessing these data. Here, we present new features that have been added to ESMValCore and ESMValTool in the past year.

Improved computational performance: it is now possible to use Dask Distributed to run the tool and almost all preprocessor functions are now using Dask arrays, resulting in lower memory use and faster computations. This enables the analysis of higher-resolution datasets, such as those expected for the next round of CMIP. Further performance improvements are planned this year as part of the ESiWACE3 service project.

New recipes and better-looking results: several new analyses have been added, including recipes for reproducing figures from the IPCC’s Fifth and Sixth Assessment Reports and generic recipes for monitoring and evaluating Earth System Model simulations. The webpage displaying the results of a recipe run now looks better and allows for interactive filtering.

More datasets: more observational and reanalysis datasets can now be converted to the CMIP data request standard using the tool. Grids used in the Coordinated Regional Climate Downscaling Experiment (CORDEX) are now better supported.

Communication: the ESMValTool tutorial at https://tutorial.esmvaltool.org has been updated, more Jupyter notebooks are available to demonstrate the use of ESMValCore, and there is a new, open-source website at https://esmvaltool.org.

How to cite: Andela, B., Hassler, B., and Schlund, M.: Recent developments in the Earth System Model evaluation tool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12558, https://doi.org/10.5194/egusphere-egu24-12558, 2024.

EGU24-12905 | Orals | CL5.6

A new ESMValTool metric using point source observations from AeroNET 

Catherine Hardacre, Klaus Zimmermann, Joakim Löw, and Jane Mulcahy

ESMValTool is an open-source community-developed diagnostics and performance metrics tool for the evaluation and analysis of Earth System Models (ESMs). Key to model evaluation with ESMValTool is the use of observational data, which must comply with Climate Model Output Rewriter (CMOR) standards. ESMValTool provides methods to generate CMOR compliant datasets, but these are designed to process gridded observational data sets, such as those from satellites, and currently it is more difficult to develop point source datasets. Here we present a new ESMValTool metric for evaluating model output against an observation-based climatology of aerosol optical depth (AOD) from the Aerosol Robotic Network (AeroNET). This metric includes a downloader and formatter to generate CMOR compliant datasets for the observational AOD timeseries from all AeroNET stations. These are collated into a single NetCDF file. A new ESMValTool recipe and diagnostic process and evaluate the model output against the observational AOD dataset at model grid cells co-located with the AeroNET stations. Model output is processed in the recipe using available pre-processers to generate multi-annual seasonal means. The observational AOD timeseries from the AeroNET stations are processed in the diagnostic to generate multi-annual seasonal means, or ‘climatologies’. Because the AOD timeseries from the AeroNET stations can be incomplete, filtering criteria are applied to the data from each station to ensure sufficient temporal coverage according to the user’s requirements. We evaluate AOD at 440mn simulated by CMIP6 historical ensemble members against the AOD climatologies using the new ESMValTool metric. We also demonstrate how changing the filtering criteria can modify the observational climatologies, and thus the evaluation metrics. The new method extends atmospheric composition evaluation in the ESMValTool framework by adding a key aerosol metric. We hope that the techniques used to develop this metric can be applied to other point source observation datasets.

How to cite: Hardacre, C., Zimmermann, K., Löw, J., and Mulcahy, J.: A new ESMValTool metric using point source observations from AeroNET, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12905, https://doi.org/10.5194/egusphere-egu24-12905, 2024.

EGU24-16708 | Posters on site | CL5.6

Towards a coupled nitrogen cycle representation in NorESM – ocean biogeochemistry 

Joeran Maerz, Dirk Jan Leo Olivié, Tomas Torsvik, and Christoph Heinze

The nitrogen cycle is substantially anthropogenically perturbed with potential negative consequences on biogeochemical cycles, for the climate and society. Within the project ESM2025, we therefore aim at an improved representation and interactive, emission-driven nitrogen cycle in the Norwegian Earth system model (NorESM) to foster providing information about future societal impacts.

We here focus on the ocean biogeochemistry component iHAMOCC of NorESM, where major upgrades have been carried out with a particular focus on processes related to the highly potent greenhouse gas N2O. We included two more tracers, namely NH4+ and NO2-, which enabled an explicit representation of major canonical ocean nitrogen cycle pathways in both, the water column and the sediment. The in parallel substantially improved atmosphere chemistry of NorESM enabled us to realize the thus far technical capability to interactively couple air-sea N2O and NH3 fluxes as well as receiving atmospheric dry and wet deposition fluxes in the form of NHx and NOy. Concomitantly, interactive atmosphere-land N2O and nitrogen deposition fluxes were implemented, further increasing NorESMs capability for coupled nitrogen cycle simulations. The improved NorESM atmosphere and ocean component are currently individually in fine-tuning and spin-up phase in close preparation for first interactively coupled simulations.

Preliminary, partially still in transient ocean-only climatological atmosphere-forced simulations show a reasonable oceanic N2O emission pattern, also quantitatively close to recent reconstructions of Yang et al. 2020 (4.2 TgN/yr, doi:10.1073/pnas.1921914117), while the global ammonia emissions are at the lower end of current estimates (2-27 TgN/yr). With the current improved oceanic nitrogen cycle representation, N2O production during nitrification in well-ventilated areas is closely linked to primary production through subsequent decay and ammonification of organic nitrogen. By contrast, the transition zones of oxygen deficit zones (ODZs) entail microbial key processes of both aerobic and anaerobic N2O production and anaerobic N2O consumption, making those regions to hotspots of nitrogen cycling relevant to N2O. For the sediments, productive ocean and shelf regions feature higher N2O sediment-water column fluxes per unit area than deep sea regions, in line with current observational knowledge. In total, however, the sediments globally contribute significantly less to N2O production than the water column. In brief, future evolution of export fluxes and ODZs can hence be expected to determine the oceanic N2O release in response to ongoing climate change.

With the recent developments in NorESM, we increased the representation of nitrogen cycle-relevant processes and enhanced the thus far technical capability to simulate the nitrogen cycle emission-driven and interactively coupled across major Earth system components, while envisaging to also increase NorESMs land-ocean nitrogen transport representation.

How to cite: Maerz, J., Olivié, D. J. L., Torsvik, T., and Heinze, C.: Towards a coupled nitrogen cycle representation in NorESM – ocean biogeochemistry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16708, https://doi.org/10.5194/egusphere-egu24-16708, 2024.

Simple climate models provide a flexible, computationally cost-effective way to emulate the more complex and higher resolution earth system models. As ESMs are improved, adding in new processes that weren't explicitly included before, so too can the simple climate models be refined to reflect changes to our understanding of the climate response to changing emissions. New developments in modelling of peatlands, wetlands, permafrost, and negative emissions scenarios have provided new data to test the simple models MAGICC and FAIR. By comparing their projections under the same scenarios used by more complex models, the reduced complexity models' limitations and uncertainties can be shown, and thus they can be improved to better capture the new knowledge. Here, we focus on peatlands, comparing the results of a new module in the model OSCAR with the current output from MAGICC and FAIR, quantifying the impact that explicit peatland processes have on global temperature. Negative emissions scenarios are also considered, all as part of a broader project to understand overshoot pathways, scenarios in which the global temperature anomaly exceeds 1.5°C but returns to a temperature below that mark. These results will show the value and capability of the simple climate models as they continue to be refined to emulate the larger models.

How to cite: Sloughter, T. and Rogelj, J.: Understanding uncertainties in the global Earth climate response with reduced complexity climate models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19283, https://doi.org/10.5194/egusphere-egu24-19283, 2024.

EGU24-20894 | Posters on site | CL5.6

Methodological Developments in the International Land Model Benchmarking Effort 

Nathan Collier, Forrest Hoffman, and Dave Lawrence

As earth system models (ESMs) become increasingly complex, there is a growing need for comprehensive and multi-faceted evaluation of model performance. The International Land Model Benchmarking (ILAMB) project is a model-data intercomparison and integration project designed to improve the performance of land models and improve the design of new measurement campaigns to reduce uncertainties associated with key land surface processes. While the effort has been established for over a decade, we continue to make developments and improvements in order to incorporate new datasets as well as adapt our scoring methodology to be more useful for model developers in identifying and diagnosing model errors.

The version 2.7 release of the ILAMB python software includes new datasets for gross primary productivity and latent/sensible heat flux (WECANN: Water, Energy, and Carbon with Artificial Neural Networks), growing season net carbon flux (Loechli2023), biomass (ESACCI: European Space Agency, Biomass Climate Change Initiative and XuSaatchi2021), methane (Fluxnet), and surface soil moisture (Wang2021). In addition to these land-focused datasets, ILAMB v2.7 marks the first release of the International Ocean Model Benchmarking (IOMB) package. While the codebase remains the same as is used with the land, this release encodes datasets and configuration file to be used in benchmarking ocean models.

Finally, we present a shift in the ILAMB scoring methodology. In order to make errors comparable across different areas of the globe, ILAMB originally employed a normalization of errors by the variability of the reference quantity in a particular location. For many variables, this choice tends to strongly weight performance in the tropics and consequently does not give a balanced perspective on model performance across the globe. To balance performance across the globe, we propose a shift to normalize errors by regional error quantiles. We select regions which conform to traditional understanding of biomes in order to focus on areas where we expect errors to be commensurate in the order of magnitude. We then choose a normalizing quantity by taking a quantile of the errors in these biomes across a selection of CMIP5 and CMIP6 era models. In this way, we contextualize the scores by using the performance of the recent generations of models.

How to cite: Collier, N., Hoffman, F., and Lawrence, D.: Methodological Developments in the International Land Model Benchmarking Effort, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20894, https://doi.org/10.5194/egusphere-egu24-20894, 2024.

EGU24-22316 | Orals | CL5.6 | Highlight

Climate Model Benchmarking for CMIP7 – A CMIP Task Team 

Forrest Hoffman and Birgit Hassler

The goal of the Coupled Model Intercomparison Project (CMIP) is to better understand past, present, and future climate changes in a multi-model context. Based on the outcomes of the phase 6 of CMIP (CMIP6) Community Survey, the CMIP panel is seeking to identify ways to increase the project's scientific and societal relevance, improve accessibility, and widen participation. To achieve these goals, a number of Task Teams were established to support the design, scope, and definition of the next phase of CMIP and the evolution of CMIP infrastructure and future operationalization.

An important prerequisite for providing reliable climate information from climate and Earth system models is to understand their capabilities and limitations. Thus, systematically and comprehensively evaluating the models with the best available observations and reanalysis data is essential. For CMIP7 new evaluation challenges stemming from models with higher resolution and enhanced complexity need to be rigorously addressed. These challenges are both technical (e.g., memory limits, increasingly unstructured and regional grids), and scientific. In particular, innovative diagnostics, including the support of machine learning-based analysis of CMIP simulations, must be developed.

The Climate Model Benchmarking Task Team aims to provide a vision and concrete guidance for establishing a systematic, open, and rapid performance assessment of the expected large number of models participating in CMIP7, including a variety of informative diagnostics and performance metrics. The goal is to fully integrate evaluation tools into the CMIP publication workflow, and their diagnostic outputs published alongside the model output on the ESGF, ideally displayed through an easily accessible website. To accomplish this, existing evaluation tools need to be further developed and applied to historical and other CMIP7 simulations. We expect to produce an increasingly systematic characterization of the models which, compared with early phases of CMIP, will more quickly and openly identify the strengths and weaknesses of simulation results. This will also reveal whether long-standing model errors remain evident in newer models and will assist modelling groups in improving their models. This framework will be designed to readily incorporate updates, including new observations and a multitude of additional diagnostics and metrics as they become available from the research community, and will be developed as fully open-source software with high documentation standards.

How to cite: Hoffman, F. and Hassler, B.: Climate Model Benchmarking for CMIP7 – A CMIP Task Team, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22316, https://doi.org/10.5194/egusphere-egu24-22316, 2024.

EGU24-1191 | ECS | PICO | CL5.8

Are users drawing the same conclusions from different climate data portals? 

Juliette Lavoie, Louis-Philippe Caron, Travis Logan, and Elaine Barrow

Climate data portals serve as important tools for climate services providers to effectively communicate with decision-makers. With a rapid increase in the number of such portals and the datasets underlying them, critical questions arise: do users encounter similar narratives across these platforms, and does their choice of portal influence decisions on adaptation measures? This presentation conducts a comparative analysis of two prominent Canadian portals, namely Climate Data Canada and Portraits Climatiques. Both portals feature bias-adjusted CMIP6 simulations that differ in various aspects, including bias-adjustment methodology, climate of reference, ensemble composition, and emissions scenarios. The impact of these choices is explored by assessing three core variables (daily maximum temperature, daily minimum temperature, and daily precipitation) and examining five case studies from the agriculture, transport, and health sectors. Our findings reveal significant disparities between the portals in terms of climate indicator values at the end of the century, while projected changes compared to the present climate are often more similar. Moreover, we observe a strong influence of the reference dataset choice on threshold-based indicators. Despite these discrepancies, users commonly make similar final decisions when employing both platforms, as adaptation measures are not markedly sensitive to the distinctions and as other non-climate-related factors must be considered in the decision-making process. This study sheds light on differences and similarities between climate data portals, emphasizing the need for climate services organizations to transparently communicate the implications of their choices to users, in order to guide the formulation of effective adaptation strategies.

How to cite: Lavoie, J., Caron, L.-P., Logan, T., and Barrow, E.: Are users drawing the same conclusions from different climate data portals?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1191, https://doi.org/10.5194/egusphere-egu24-1191, 2024.

EGU24-3465 | PICO | CL5.8

KNMI’23 climate scenarios for the Netherlands: storyline scenarios of regional climate change 

Karin van der Wiel, Jules Beersma, Henk van den Brink, Folmer Krikken, Frank Selten, Camiel Severijns, Andreas Sterl, Erik van Meijgaard, Thomas Reerink, and Rob van Dorland

We will present the methodology for the construction, and the outcomes, of the KNMI’23 national climate scenarios for the Netherlands. The KNMI’23 national climate scenarios consist of six scenarios that cover a substantial part of the uncertainty in CMIP6 projections of future climate change in the region. They form a detailed storyline of plausible future climates in the Netherlands. The resulting data is used for impact calculations and assessments by stakeholders, and will be used to inform policy making in different sectors of Dutch society.

We have disentangled different sources of uncertainty as much as possible, partly by means of a storyline approach. Uncertainty in future emissions is covered by making scenarios conditional on different SSP scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5). For each SSP scenario and time horizon (2050, 2100, 2150), we determine a global warming level based on the median of the constrained estimates of climate sensitivity from IPCC AR6. The remaining climate model uncertainty of the regional climate response at these warming levels is covered by two storylines, which are designed with a focus on the annual and seasonal mean precipitation response (a dry-trending and wet-trending variant for each SSP). This choice was motivated by the importance of future water management to society. For users with specific interests we provide means how to account for the impact of the uncertainty in climate sensitivity. Since CMIP6 GCM data do not provide the required spatial detail for impact modelling, we reconstruct the CMIP6 responses by resampling internal variability in a GCM-RCM initial-condition ensemble.

More information on: https://www.knmi.nl/klimaatscenarios (see ‘toolkit’ for material in English).

How to cite: van der Wiel, K., Beersma, J., van den Brink, H., Krikken, F., Selten, F., Severijns, C., Sterl, A., van Meijgaard, E., Reerink, T., and van Dorland, R.: KNMI’23 climate scenarios for the Netherlands: storyline scenarios of regional climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3465, https://doi.org/10.5194/egusphere-egu24-3465, 2024.

While dynamical seasonal prediction models offer many benefits, it is challenging for most National Hydrological and Meteorological Services (NMHSs) to develop and operate their own expensive models. Given the limited human and computing resources in South Korea’s modeling communities, increasing our capacity to share small resources and generate joint efforts for a better climate prediction system is thus essential. The Korean Meteorological Administration (KMA) adopted the Global Seasonal Forecasting System version 6 (GloSea6) from the United Kingdom Met Office (UKMO), and has being operated the prediction system for the real-time climate forecasting since 2022 March. The domestic and multi-institutional efforts are currently underway to advance the prediction system in collaboration with academic societies and the APEC Climate Center (APCC), which is a research partner of the KMA. By motivated by great needs for joint collaborative system between academy, research institute and organization, and NMHSs, as well as strengthened strategy of operationalization, we have once recalled the research-to-operation (R2O) process and finally invented the R2O structure customized for the dynamical prediction and modelling environments in South Korea (K-R2O). K-R2O represents technically sound and unique process from research and development to operation through testbed which individual components are carried out by different parties. The role of testbed and framework of standard verification for model development identified in K-R2O is highlighted. Lesson learned and further guidance for K-R2O are also discussed for many NMHSs facing similar situation to South Korea.

How to cite: Sohn, S.-J.: Sharing Small Resources and Making Joint Efforts for the Improvement of Climate Prediction Model in South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7390, https://doi.org/10.5194/egusphere-egu24-7390, 2024.

EGU24-8182 | PICO | CL5.8

C2risk: Co-creating climate management tools for mobility infrastructures 

Jon Xavier Olano Pozo, Anna Boqué-Ciurana, Oleg Skrynyk, Marianna Brichese, Francesco Panico, Mario Calicchio, Serena Pantaneschi, Adrià Balart, Daniel Dermitt, Maurizio di Meglio, Federico Foria, Gabriele Miceli, and Enric Aguilar

Climate variability and change are societal challenges, necessitating urgent and comprehensive responses across many sectors. To confront these challenges effectively, these sectors must devise and execute adaptation and mitigation strategies. Such strategies should focus on minimising contributing factors to climate change and bolstering resilience against its repercussions. The urgency of these measures stems from the recognition that climate change permeates virtually every facet of our environment and daily life, calling for a concerted and enduring effort to safeguard our planet for future generations. A critical component of this endeavour is understanding the influence of meteorological and climatic conditions on specific sectors.
We have embraced a co-creation methodology that actively includes stakeholders to tackle the complexities of climate variability and change, as Font et al. (2021) suggested. This methodology is particularly pertinent to critical infrastructures at various levels. Our inclusive approach gathers many participants, from high-ranking executive managers to hydrogeology specialists. This diversity in perspectives and expertise guarantees that the solutions devised are comprehensive and precisely tailored to meet the distinct needs and contexts of the mobility infrastructures affected by climate change. Such a collaborative process cultivates innovation while fostering a sense of ownership and commitment among all stakeholders, thereby enhancing the effectiveness and durability of the solutions.
Our case study, executed in the Italian regions of Campania and Lazio, demonstrates the varied risks present in these areas and how they change over time and space. For this study, we utilized ERA5 land data, specifically downscaled to reconstruct historical climate scenario, and Cordex data for future climate projections. This presentation aims to transcend the mere explanation of climate data and show the whole process and journey to transform data into a climate service to assist decision-making in the mobility infrastructure sector. It is conveyed through an intuitive and reactive visual medium via a Shiny application crafted for accessibility to a diverse audience. This application proficiently exhibits the various calculated co-created indices over multiple intervals, rendering tailored information and making it more user-friendly and engaging for non-academic and non-climate-related users. Such a presentation style is instrumental in enhancing comprehension of climate change impacts and aiding in informed decision-making

How to cite: Olano Pozo, J. X., Boqué-Ciurana, A., Skrynyk, O., Brichese, M., Panico, F., Calicchio, M., Pantaneschi, S., Balart, A., Dermitt, D., di Meglio, M., Foria, F., Miceli, G., and Aguilar, E.: C2risk: Co-creating climate management tools for mobility infrastructures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8182, https://doi.org/10.5194/egusphere-egu24-8182, 2024.

EGU24-8456 | ECS | PICO | CL5.8

Climate Services and Behavioral Change: Enhancing Resilience in Mediterranean Tourism through co-creation  

Anna Boqué-Ciurana, Òscar Saladié, Carla Garcia-Lozano, Gabriel Borràs, Georgina Giné, Itziar Labairu, Carolina Martí, Maria Trinitat Rovira Soto, Marta Tonda, and Enric Aguilar

This study, conducted in the southeastern Mediterranean, delves into the climate challenges of prominent coastal destinations, specifically Costa Daurada and Terres de l'Ebre (in Northeastern Spain). There is an urgent need to strengthen society's resilience to climate hazards and manage risks in these Mediterranean areas.

Adapting these tourist destinations to climate change and mitigating associated risks necessitates a profound understanding of the Behavioral Change factors impacting businesses, citizens, tourists, and administration. Access to Climate Services emerges as a pivotal element in the climate adaptation strategy for the tourism sector. These services must be of high quality, tailored to end-users' needs, functioning as decision-making tools, offering incentives for social benefits, and communicating effectively (Scott et al., 2011). 

The Horizon2020 Impetus project, which started in Oct 2021, aligns with the EU's-2050 climate goals, translating commitments into tangible actions for community and planet protection.

This project seeks a fundamental behavioral shift to achieve climate-resilient tourism and implement the Catalan Climate Change Adaptation Strategy (ESCACC30) in the tourism sector. Recognizing the paramount role of Behavioral Change, the strategy adopts a problem-solving approach based on Michie et al.'s (2013) taxonomy. This method includes thoroughly examining factors impacting behavioral change, devising strategies to overcome challenges, and improving change facilitators. It includes measures to prevent setbacks and plans to address the consequences of climate change.

The co-creation process, inspired by Font et al.'s (2021) methodology, was used to implement these strategies. Public and private actors in the tourist destinations of Costa Daurada and Terres de l'Ebre actively participated in co-creation workshops, focusing on themes such as weather, climate, climate change, and tourism, energy, water, and tourism, as well as the perception of the beach-dune system. These workshops have developed indicators, shedding light on the climatic potential for various tourism modalities. The stakeholders identified the physical impacts of climate change that affect the attractiveness and vulnerability of the tourist destination. They proposed measures related to water and energy, classifying them based on their priority and vulnerability. Furthermore, we employed the repeat photography method to collect data on citizens' awareness of the temporal changes in the beach-dune system within the study area. This approach also helped us understand their perceptions regarding the roles and the landscape of the beaches and dunes. 

References 

Scott, D. J., Lemieux, C. J., & Malone, L. (2011). Climate services to support sustainable tourism and adaptation to climate change. Climate Research, 47(1-2), 111-122. 

Michie S, Richardson M, Johnston M, Abraham C, Francis J, Hardeman W, Eccles MP, Cane J, Wood CE. The behavior change technique taxonomy of 93 hierarchically clustered techniques: building an international consensus for the reporting of behavior change interventions. Ann Behav Med. (2013) Aug;46(1):81-95. doi: 10.1007/s12160-013-9486-6. PMID: 23512568. 

Font-Barnet, A. F., Boqué-Ciurana, A., Pozo, J. X. O., Russo, A., Coscarelli, R., Antronico, L., De Pascale, F., Anton-Clave, S., Saladié, Ò & Aguilar, E. (2021). Climate services for tourism: An applied methodology for user engagement and co-creation in European destinations. Climate Services, 23, 100249. 

How to cite: Boqué-Ciurana, A., Saladié, Ò., Garcia-Lozano, C., Borràs, G., Giné, G., Labairu, I., Martí, C., Rovira Soto, M. T., Tonda, M., and Aguilar, E.: Climate Services and Behavioral Change: Enhancing Resilience in Mediterranean Tourism through co-creation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8456, https://doi.org/10.5194/egusphere-egu24-8456, 2024.

EGU24-9656 | PICO | CL5.8

A web portal dedicated to climate change impact studies in the Global South: ClimatSuds.ird.fr 

Yves Tramblay, Benjamin Sultan, Ernest Amoussou, Paola A. Arias, Ansoumana Bodian, Lluís Fita Borrell, Audrey Brouillet, Thomas Condom, Alain Dezetter, Arona Diedhou, Fatima Driouech, Lahoucine Hanich, Clémentine Junquas, Emmanuel Roux, Youssouph Sané, Nora Scarcelli, and Thanh Ngo-Duc

The recent sixth IPCC report highlighted the lack of studies on the impacts of climate change in the Global South. While paradoxically these countries have the weakest resilience capacity to adapt to these forthcoming changes. In this context, a co-construction workshop was organized in 2022 to define the multi-sectoral needs of different academic or institutional actors working on the impacts of climate change. Bridging together meteorological and hydrological agencies, universities, research centers, and private companies from Africa, Europe, South Asia, and South America, this workshop allowed defining the types of data and their modalities of access, that are the most adapted to conduct impact studies of climate change in different domains. The main difficulties in accessing climate data identified for researchers working on climate change impacts were related to the lack of technical capability to retrieve and process the worldwide databases of climate models data and also the need for expertise to exploit this wealth of data efficiently. Following this workshop, a climate services platform was implemented in 2023 (https://climatsuds.ird.fr/) to access a large dataset of bias-corrected CMIP6 climate models simulations, as well as a set of climate indices relevant for impacts assessment (heavy rains, extreme heat..) and impact models outputs (ISIMIP2a) in different sectors (water, vegetation, agriculture, and health). The web platform enables data extraction by point, by country, or by free polygons, visualization in graphic formats, and export to NetCDF or CSV files. Besides data access functionalities, the web portal will gradually integrate different training resources for the users and new datasets according to their needs. 

How to cite: Tramblay, Y., Sultan, B., Amoussou, E., Arias, P. A., Bodian, A., Fita Borrell, L., Brouillet, A., Condom, T., Dezetter, A., Diedhou, A., Driouech, F., Hanich, L., Junquas, C., Roux, E., Sané, Y., Scarcelli, N., and Ngo-Duc, T.: A web portal dedicated to climate change impact studies in the Global South: ClimatSuds.ird.fr, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9656, https://doi.org/10.5194/egusphere-egu24-9656, 2024.

EGU24-15388 | PICO | CL5.8

Creating tools for the generation of weather-based crop calendars to support climate services.  

Enric Aguilar, Anna Boqué, Jon Olano, Tania Gascon, Sebastian Gray, and Kossi Agniga

The UN 2030 Sustainable Development Agenda included achieving Zero Hunger as one of its prominent goals. According to Food and Agriculture Organization for the United Nations (FAO), this objective is far from being achieved, as over 735 million people faced hunger in. The geographical distribution of food insecurity is not even across the globe, with greater impact over less developed countries where subsistence agriculture is a major livelihood. Weather, climate, climate variability and climate change alter in time and space the phenological stages of crops and, therefore, agricultural planning and production. One of the most widely used tools to convey weather and climate information to final agricultural users are weather-based crop calendars. They use time series of daily accumulated rainfall to provide actionable information on the timing of phenological stages, specifically on the times for planting (start of the season) and harvesting (end of the season) for different crops and different agroclimatic zones. The creation of a Crop Calendar requires quality controlled and homogeneous rainfall series to detect the onset and cessation of the rainy season, plus crop-specific information, like drought resilience and crop cycle length. Rainy season onset and cessation are determined using threshold-based methods, which combine rainfall accumulation over several days and additional criteria to avoid false alarms, such as the presence/absence of consecutive dry days. The rainy season onset and cessation for each year are calculated and their timeseries fit to a probability distribution to evaluate the climatological expectations for early/normal/late onsets and cessations. The final crop calendar results from assimilating the first/early/normal/late onsets of the rainy season to the span of possibilities for the sowing dates. The harvest dates are defined as the sowing dates plus the crop cycle length for each variety and agroecological zone. In this contribution, we present a series of tools developed with the support of the World Meteorological Organization (WMO) and the Climate Risk and Early Warning Systems Initiative (CREWS) project in West Africa and the Enhancing Adaptive Capacity of Andean Communities through Climate Services (ENANDES) project in South America, following a “from data to service” approach and including a series of training events. The process is illustrated using rainfall series from Togo.

How to cite: Aguilar, E., Boqué, A., Olano, J., Gascon, T., Gray, S., and Agniga, K.: Creating tools for the generation of weather-based crop calendars to support climate services. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15388, https://doi.org/10.5194/egusphere-egu24-15388, 2024.

EGU24-16532 | PICO | CL5.8

Better Climate Services: guidelines, standards and best practices for data processing 

Christian Pagé and Ángel G. Muñoz and the Climateurope2 WP2 Team

Timely delivery and effective use of climate information is fundamental for a green recovery and a resilient, climate neutral Europe, in response to climate change and variability. Climate services address this through the provision of climate information for use in decision-making to manage risks and create opportunities. In order to develop future equitable and quality-assured climate services to all sectors of society, it is important to work on developing standardisation procedures for climate services, as well as supporting an equitable European climate services community and also enhancing the uptake of quality-assured climate services to support adaptation and mitigation to climate change and variability.

An important component of the climate service reliability and use depends on the data, specifically on the traceable quality of its input and output datasets. The output datasets need to be FAIR, also for machines, meaning the output datasets provide full provenance information about e.g. the input datasets, the processing software, the quality and accuracy, all supported by interoperable metadata, including information on uncertainty. To support those needs and objectives for climate services, we will present preliminary guidelines of good practices for vocabularies, formats, metadata and technical standards, including FAIR principles for data and software/processing. As well, preliminary best practices in provenance of processing methodologies to guarantee traceability and reproducibility of climate data and ways to communicate it in a user-friendly manner will also be shown along with climate uncertainty, risk assessment and communication. Eventually all guidelines and good practices will be shared via the Climateurope2 platform, set up under the project to support the climate services community.

Everyone interested can also join our network to actively participate in developing best practices for climate services https://climateurope2.eu/

This project (Climateurope2) has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement N°101056933.

How to cite: Pagé, C. and Muñoz, Á. G. and the Climateurope2 WP2 Team: Better Climate Services: guidelines, standards and best practices for data processing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16532, https://doi.org/10.5194/egusphere-egu24-16532, 2024.

EGU24-16579 | PICO | CL5.8 | Highlight

The Evolution of Climate Services: Shifting Paradigms from commercial exploitation to Societal Engagement 

Marcello Petitta, Sandro Calmanti, and Matteo De Felice

The landscape of climate services is undergoing a remarkable transformation with the definition of a new framework. We call this new framework: Societal Climate Services (SCS). This shift has been primarily driven by a growing trend among large corporations to decrease their reliance on external climate service consultancies in favor of developing dedicated in-house departments. Such a move signifies a transition towards self-reliance in climate-related decision-making and strategy formulation, marking a departure from the traditional reliance on external expertise prevalent in recent research projects.

Traditionally, the development of climate services has relied on the co-creation, co-design and co-development (CO-CO-CO) approach, characterised by collaborative efforts among external experts, academics and researchers. However, the growing in-house expertise within these corporations indicates a significant shift towards more independent, customised climate solutions.

There is the need to shift the current climate services from a purely business approach to a new framework where the society is central. Societal climate services complement this evolution by expanding the focus beyond the needs of businesses to broader societal concerns, particularly in vulnerable and underrepresented communities, especially in developing countries. SCS aims to democratise climate knowledge and make it accessible and usable not only for businesses, but for society as a whole. This approach promotes a people-centred model of engagement where community participation and local knowledge play a central role in shaping climate solutions.

This summary outlines the principles of societal climate services and emphasises the importance of cross-sectoral cooperation for a comprehensive and integrated approach. It emphasises the role of SCS in building sustainable and resilient communities through long-term planning and investment in sustainable practises. It also emphasises the need for equity and justice in the provision of climate services to ensure that solutions do not exacerbate existing inequalities but contribute to their reduction.

The emerging momentum of companies developing internal capacity for climate services alongside the emergence of SCS is a key development in this area. This combination promises a more holistic and effective framework for addressing the multi-faceted challenges of climate change, ensuring that both business interests and societal needs are aligned in the pursuit of global climate resilience.

 

How to cite: Petitta, M., Calmanti, S., and De Felice, M.: The Evolution of Climate Services: Shifting Paradigms from commercial exploitation to Societal Engagement, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16579, https://doi.org/10.5194/egusphere-egu24-16579, 2024.

EGU24-17496 | PICO | CL5.8

Climate Predictions @ DWD – towards a seamless climate prediction website 

Birgit Mannig, Andreas Paxian, Miriam Tivig, Sabrina Wehring, Thomas Leppelt, Alexander Pasternack, Fabiana Castino, Kelly Stanley, and Barbara Früh

To support decision-making processes, Germany's National Meteorological Service, Deutscher Wetterdienst (DWD) is developing an operational seamless climate prediction service. Climate predictions from subseasonal to the decadal time scales are consistently presented on a single platform, the DWD climate predictions website (http://www.dwd.de/climatepredictions) [1]. To strengthen the idea of seamless climate information, we are working on a seamless timeseries, which contextualizes climate predictions with observations from the past and future climate projections.

National users from different sectors (e.g. water, energy, forestry, agriculture) regularly take part in the discussion and evaluation process of the DWD climate prediction website. Design and content of the climate service were developed as a co-design with national users.

To meet users’ needs regarding spatial resolution, climate predictions on all timescales are downscaled using the empirical-statistical downscaling EPISODES [2]. Presented on the website are bias corrected weekly (subseasonal), 3-month (seasonal) 1- and 5-year (decadal) means of temperature and precipitation on global and national scale. DWD always presents its climate predictions in combination with the corresponding prediction skill.

We provide climate predictions in two categories of different complexity. The “basic climate predictions” offer simplified climate predictions, which will be presented on an interactive platform soon. In a second “expert climate predictions” section, we offer more detailed information on global, European, and national climate predictions.

The newest user-oriented addition on the website will be climate predictions and the corresponding evaluations of soil moisture. This new product is calculated with the AMBAV model [3], which retrieves its input variables from DWD’s high-resolution climate predictions. Additionally, user surveys have shown high interest in climate extremes. Currently DWD is working on the publication of several extreme indices concerning drought and heat. Plans for further extensions include multi-year seasonal predictions and multi-model predictions.

[1] A. Paxian, B. Mannig, M. Tivig, K. Reinhardt, K. Isensee, A. Pasternack, A. Hoff, K. Pankatz, S. Buchholz, S. Wehring, P. Lorenz, K. Fröhlich, F. Kreienkamp, B. Früh (2023). The DWD climate predictions website: towards a seamless outlook based on subseasonal, seasonal and decadal predictions. Climate Services 30, 100379. https://doi.org/10.1016/j.cliser.2023.100379.

[2] Kreienkamp, F., Paxian, A., Früh, B., Lorenz, P., Matulla, C., 2018. Evaluation of the Empirical-Statistical Downscaling method EPISODES. Clim. Dyn. 52, 991–1026 (2019). https://doi.org/10.1007/s00382-018-4276-2.

[3] https://www.dwd.de/DE/fachnutzer/landwirtschaft/dokumentationen/allgemein/ambav-20_doku.html

How to cite: Mannig, B., Paxian, A., Tivig, M., Wehring, S., Leppelt, T., Pasternack, A., Castino, F., Stanley, K., and Früh, B.: Climate Predictions @ DWD – towards a seamless climate prediction website, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17496, https://doi.org/10.5194/egusphere-egu24-17496, 2024.

EGU24-17514 | PICO | CL5.8

Impacts of climate change and weather extremes in Europe: building a knowledge base for decision support 

Jens Grieger, Uwe Ulbrich, Sebastian Buschow, Etor E. Lucio Eceiza, Hendrik Feldmann, Petra Friederichs, Frank Kaspar, Torben Kunz, Deborah Niermann, and Joaquim G. Pinto

The ClimXtreme program, funded by the German Ministry of Education and Research, focuses on the assessment of the frequency and intensity of historical extreme events and their impacts in Central Europe, their association with dynamical and thermodynamical processes and how these extreme events might change according to enhanced anthropogenic climate forcing.

The program currently aims at the development of a basis for stakeholder decision making that consists of data, software, and information tailored to their needs. By means of dedicated hazard specific stakeholder interaction groups, relevant stakeholders and researchers will develop the knowledge base through a two-way process. Social scientists will explore and develop the communication process with stakeholders.

Within the research program, a post-event assessment group will be formed aiming at rapid response of the project to extreme events occurring during project runtime. The group will make use of the developed knowledge base, apply pre-defined methods and workflows to assess current extreme events with diverse perspectives which are represented in ClimXtreme.

Both the concept and selected recent results of the ClimXtreme program will be highlighted.

How to cite: Grieger, J., Ulbrich, U., Buschow, S., Lucio Eceiza, E. E., Feldmann, H., Friederichs, P., Kaspar, F., Kunz, T., Niermann, D., and Pinto, J. G.: Impacts of climate change and weather extremes in Europe: building a knowledge base for decision support, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17514, https://doi.org/10.5194/egusphere-egu24-17514, 2024.

EGU24-17578 | PICO | CL5.8

Support Toolbox for Urban Adaptation to Heat Waves in Romania 

Alexandru Dumitrescu, Sorin Cheval, Zenaida Chițu, Vladut Falcescu, Ștefan Gabrian, and Ștefan Dinicilă

A comprehensive toolbox has been developed to support urban adaptation to heat waves (HWs) in the context of the current climate and climate change. The toolbox consists of the following components: (1) full methodology for analysing the interactions between urban heat islands (UHIs) and HWs in the context of climate change; it is exemplified for the city of Bucharest, Romania, but the methodologies used can be easily applied to other cities; (2) a web-based tool that allows users to explore the impacts of different climate change scenarios on the interactions between UHIs and HWs;  for example, users can input changes in land cover, population growth, and temperature and see how these changes affect the UHI-HW relationship in a particular city;  (3) guidelines and specific measures to better cope with the UHI and HW stress under current and future climate conditions, tailored to the specific context of each city; adaptation and mitigation options are included (i.e., more greenery and lesser disruption of the natural water cycle supporting current policies for climate change resilience).

The support toolbox based on an interactive Shiny application built in R and Python provides a comprehensive set of tools and resources, which allows urban planners, policymakers, and stakeholders to make informed decisions about how to adapt to and mitigate the effects of HWs. The interactive features of the application enable users to intuitively visualize and interact with urban adaptation data, thereby facilitating a deeper understanding of the problem and potential solutions.

This study received funding from the project Synergies between Urban Heat Island and Heat Wave Risks in Romania: Climate Change Challenges and Adaptation Options (SynUHI) PN-III-P4-PCE-2021-1695.

How to cite: Dumitrescu, A., Cheval, S., Chițu, Z., Falcescu, V., Gabrian, Ș., and Dinicilă, Ș.: Support Toolbox for Urban Adaptation to Heat Waves in Romania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17578, https://doi.org/10.5194/egusphere-egu24-17578, 2024.

EGU24-19674 | ECS | PICO | CL5.8

Interactive Climate Atlas of Climate Change: an application tool for informing practitioners and policy-maker decisions in Ukraine 

Lidiia Kryshtop, Svitlana Krakovska, Anastasia Chyhareva, and Tetiana Shpytal

The Interactive Climate Atlas of Climate Change serves as a pivotal application tool designed to empower practitioners and policy-makers in Ukraine by providing dynamic, user-friendly access to crucial climate information. This innovative platform amalgamates scientific data, visualizations, and interactive features to elucidate the multifaceted impacts of climate change on the Ukrainian landscape. The atlas not only enhances climate literacy but also fosters a collaborative approach to address environmental challenges, thereby enabling practitioners and policy-makers to formulate effective strategies for sustainable development in the face of a changing climate. This application not only bolsters the resilience of Ukrainian communities but also exemplifies a scalable model for informed decision-making in regions globally affected by the profound impacts of climate change.

 
 
 

How to cite: Kryshtop, L., Krakovska, S., Chyhareva, A., and Shpytal, T.: Interactive Climate Atlas of Climate Change: an application tool for informing practitioners and policy-maker decisions in Ukraine, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19674, https://doi.org/10.5194/egusphere-egu24-19674, 2024.

EGU24-5864 | Posters on site | CL5.9

Investigation of the Suess effect in the South-West Indian Ocean over the last two decades – A model-data study 

Claire Waelbroeck, Coraline Leseurre, Pearse J. Buchanan, Gilles Reverdin, Nicolas Metzl, Virginie Racapé, Claire Lo Monaco, Catherine Pierre, Jérôme Demange, and Jonathan Fin

Measurements of dissolved inorganic carbon (DIC) concentration and its isotopic composition (δ13CDIC) are essential to study chemical and biological processes involved in the ocean carbon cycle, including photosynthesis, respiration, and air-sea CO2 fluxes. Anthropogenic CO2 emissions from fossil fuel combustion have caused an increase in DIC accompanied by a decline in δ13CDIC (called the Suess effect). δ13CDIC is thus a useful tracer to assess the oceanic uptake of anthropogenic CO2.

Annual assessments of the Global Carbon Budget (e.g. Friedlingstein et al., 2023) have revealed a growing deviation over the last 10 to 15 years between the estimates of the ocean carbon sink based on observations and models, with the growth of the observation-based ocean CO2 sink being larger compared to the models. Discrepancies in the multi-decadal trend originate from all latitudes but are greatest in the Southern Ocean.

Here, we present DIC and δ13CDIC measurements from surface and water column samples collected in the South-West Indian Ocean during repeated summer cruises over the last two decades (1998-2021) conducted on board the RV Marion Dufresne within the French monitoring program OISO (Océan Indien Service d’Observation). We compare these measurements with the DIC and δ13CDIC simulated over the same period by the δ13C-enabled version of the NEMO-PISCES ocean-biogeochemical model.

We use different methods to separate the natural and anthropogenic signals over the last 20 years. Our analysis reveals some inconsistencies between simulated and observed DIC and δ13CDIC, as well as between other simulated and observed biogeochemical parameters, whereas physical parameters are generally well reproduced by the model. Identifying the cause for this mismatch bears the potential to explain all or part of the divergence between the observation-based and model-based estimates of oceanic carbon uptake.

How to cite: Waelbroeck, C., Leseurre, C., Buchanan, P. J., Reverdin, G., Metzl, N., Racapé, V., Lo Monaco, C., Pierre, C., Demange, J., and Fin, J.: Investigation of the Suess effect in the South-West Indian Ocean over the last two decades – A model-data study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5864, https://doi.org/10.5194/egusphere-egu24-5864, 2024.

EGU24-10048 | Posters on site | CL5.9

The Amazon plume in 2020-2023: its shelf carbon budget and water origin revisited  

Gilles Reverdin, Léa Olivier, Jacqueline Boutin, Claire Waelbroeck, Coraline Leseurre, Patrice Bretel, Jérôme Demange, Jonathan Fin, Stéphane Pesant, Paula Huber, Hugo Sarmento, Doug Vandemark, Chris Hunt, Daniele Iudicone, Aline Govin, and Sabrina Speich

The Amazon shelf of South America is known to be highly contrasted in its surface carbon dioxide concentrations, from very high concentrations near the estuary, and very low concentrations downstream in the saltier Amazon plume, which results in a great contrast in carbon dioxide exchange with the atmosphere. During three cruises in 2020-2023 (Eurec4A-OA, Tara-Microbiomes legs 5, 6 and 7, Amaryllis), dissolved inorganic carbon (DIC) concentration, its isotopic composition (δ13C-DIC), the water isotopic composition (d18O-H2O and d2H-H2O), as well as inorganic nutrients and surface CO2 partial pressure (pCO2) were measured on the Amazon shelf of South America during three cruises in different seasons. These data are used to better understand mixing in the continuum between river water and open-ocean waters, and the biogeochemical processes taking place on the shelf close to the Amazon and Para river estuaries. The water isotopes are furthermore used to identify different freshwater origins.

The accuracy of the data is discussed as well as its representativeness. The data are then combined to first identify large variations of the river freshwater sources, compatible with 2021 being a year of very large discharge, and 2023 a year of exceptional low discharge. In addition, the data mostly from August and September 2021 identify a smaller influence of sources and sinks of dissolved inorganic carbon in the mixing shelf region than what had been earlier observed during the Amasseds cruise data in November-December 1991, a much lower river discharge period. This indicates that there might be a larger seasonal and/or interannual variability of these processes than what was earlier assessed. Measured pCO2 data on the Amazon shelf in 2021 are then discussed in this context.

How to cite: Reverdin, G., Olivier, L., Boutin, J., Waelbroeck, C., Leseurre, C., Bretel, P., Demange, J., Fin, J., Pesant, S., Huber, P., Sarmento, H., Vandemark, D., Hunt, C., Iudicone, D., Govin, A., and Speich, S.: The Amazon plume in 2020-2023: its shelf carbon budget and water origin revisited , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10048, https://doi.org/10.5194/egusphere-egu24-10048, 2024.

EGU24-10260 | Posters on site | CL5.9

Hydrogen and Oxygen Isotopes as Mass Proxies Along the South Atlantic Ocean 

Jose Marcus Godoy, Loes Gerringa, and Micha Rijkenberg

It was determined the values of δ(D) and δ(18O) on 432 seawater samples from 18 depth profiles collected during the Geotraces West Atlantic cruise leg 3; JC057 on RRS James Cook, 03/2011-04/2011. The first sampling station was located north of Falkland Island and the last one near the Equator line. The samples were collected using a 24 bottles rosette and storage on 2 mL glass vials, kept at 3-4 oC until the measurement. The measurements were carried out applying a PICARRO water analyzer, using IAEA VSMOW2, SLAP2 and GISP reference materials as standards, each batch consisted of the three standards and six samples, with seven injections each and the sample result represent the mean value of the three last injections.

The delta values ranged from -0.91 (station 9, 1250 m) to 1.46 (station 7, 250 m) for δ(18O) and -4.5 (station 5, 5150 m) to 8.2 (station 13, 10 m).

The δ(18O)-salinity relationship varies with the depth range with a slope of 0.37 (R=0.845) for (10- 100 m), 0.39 (R=0.747) for (100-250 m), 0.53 (R=0.813) for (250-1000 m) but poor correlated (R = 0.506) for deeper samples (>1000 m). Similar figure was observed for the δ(D)-salinity relationship with a slope of 3.04 (R=0.938) for (10- 100 m), 3.02 (R=0.879) for (100-250 m), 4.21 (R=0.898) for (250-1000 m) and poor correlated (R = 0.610) for deeper samples (>1000 m).

The δ(18O)-temperature presented a similar figure as observed for the salinity although constant for the depths higher than 1000 m changing for deeper samples. The δ(18O)-temperature relationship had a slope of 0.053 (R=0.820) for (10- 100 m), 0.054 (R=0.739) for (100-250 m), 0.048 (R=0.716) for (250-1000 m) but poor correlated (R = 0.582) for deeper samples (>1000 m). The δ(D)-temperature relationship has also quite constant until 1000 m with a slope of 0.45 (R=0.933) for (10- 100 m), 0.43 (R=0.886) for (100-250 m) and 0.41 (R=0.850) for (250-1000 m) changing the slope to 0.82 (R=0.710) for deeper samples (>1000 m).

 

How to cite: Godoy, J. M., Gerringa, L., and Rijkenberg, M.: Hydrogen and Oxygen Isotopes as Mass Proxies Along the South Atlantic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10260, https://doi.org/10.5194/egusphere-egu24-10260, 2024.

EGU24-10953 | Posters on site | CL5.9

Observation of Oxygen-18 in Ocean Waters in the Vicinity of Iceland  

Arny Sveinbjornsdottir, Jon Olafsson, and Solveig Olafsdottir

The goal of the present project is to use oxygen-18 to map water masses North of Iceland. Here we report on findings from field campaigns carried out over the period from 1988 to 2019. The samples were collected on Icelandic vessel cruises from waters that currents bring from the south and from the north and are found west and north of Iceland.  An emphasis was placed on low salinity waters that characterize the Polar Water of the East Greenland Current. The data cover all seasons and a salinity range from 29.1 to 35.3.  The observations generally also include biogeochemical constituents: dissolved oxygen and the nutrients phosphate, nitrate, and silicate (Olafsson, Olafsdottir et al. 2010).   

Oxygen isotope measurements were carried out at the Science Institute, University of Iceland. Prior to 2007 we used a Finngan MAT 251 Mass-spectrometer and extracted oxygen from the water by equilibrating degassed water with a small amount of CO2 gas (Epstein and Mayeda, 1953). After 2007 the measurements were performed on a continuous flow Delta V Advantage mass-spectrometer, with a Gas bench device. The accuracy of the measurements is better than 0.05‰. 

We examine the δ18O -S relationships for variations with seasons and time. The surface waters of the observed regions are seasonally productive but with different winter nutrient concentrations to support phytoplankton spring blooms. We examine variations in the seasonal δ18O-nutrient relationships.

 

Epstein, S. and Mayeda, T.K. (1953). Variation in O18 content of waters from natural sources. Geochim Cosmochim. Acta 4:213-224. 

Olafsson, J., S. R. Olafsdottir, A. Benoit-Cattin and T. Takahashi (2010). "The Irminger Sea and the Iceland Sea time series measurements of sea water carbon and nutrient chemistry 1983–2008." Earth Syst. Sci. Data 2(1): 99-104.

How to cite: Sveinbjornsdottir, A., Olafsson, J., and Olafsdottir, S.: Observation of Oxygen-18 in Ocean Waters in the Vicinity of Iceland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10953, https://doi.org/10.5194/egusphere-egu24-10953, 2024.

EGU24-11848 | Posters on site | CL5.9

Monitoring hydrographic changes in the mid-latitudinal Northeast Atlantic Ocean using seawater stable isotope data 

Antje H. L. Voelker, Emilia Salgueiro, Gilles Reverdin, Marcos Fontela, Fatima Abrantes, and Robert van Geldern

Since 2010 seawater samples for stable carbon and water isotope measurements were collected during various hydrographic cruises in the NE Atlantic between 29° and 60°N and 9° and 33°W, including pluriannual sampling in the Madeira basin, along the western Iberian margin and along the OVIDE/BOCATS (A25) transect between Portugal and Greenland. The samples cover the complete depth range at the respective station. For all samples δ18O was analyzed, whereas δ2H (δD) measurements were more limited and mainly focused on the wide range of water masses encountered along the OVIDE/BOCATS transect. Carbon isotope values for the dissolved inorganic carbon (δ13C-DIC) was monitored over several years at selected stations of the OVIDE/BOCATS transect and in the waters along the Portuguese margin. For some stations along the OVIDE/BOCATS transects, the results of intercomparison measurements between the laboratories at the GeoZentrum Nordbayern (Erlangen) and at LOCEAN (Paris) will also be presented.

The δ13C-DIC profiles show a clear signal of anthropogenic carbon entering the water column in the NE Atlantic and leading to lower isotopic values. Whereas data obtained for samples collected in 2010 more or less agree with the data from previous decades compiled in the GLODAP database, shifts to lower values became apparent in the subsurface waters already in 2012. The signal transfer is accelerated in the subsequent years with data from 2016 onwards showing penetration of anthropogenic carbon down to 2000 m and already all the way south to 31°N (Madeira basin). New data from a cruise to the southwestern Portuguese margin in 2022 indicate that the changes now already penetrate down to 2200 m.

Changes in the δ18O/ δ2H data are less obvious and mostly linked to the subpolar gyre and water mass changes associated with the “North Atlantic cold blob” between winter 2013-2014 and 2016. The presence of surface and subsurface waters with lower isotopic signals clearly tracks the eastward displacement of the subarctic front in 2014 and 2016. Likewise, the front’s subsequent retraction to the west is reflected in the data from 2018 and 2021. Low δ18O and  δ2H values in depths down to 300 m in the region between the Rockall Plateau and the Reykjanes ridge also clearly distinguish the subpolar mode water formed during the previous “cold blob” winters. On the other hand, and in agreement with the δ13C-DIC evidence, hardly any isotope signal changes are observed in the depths of the North Atlantic Deep Water (NADW) and the Northeast Atlantic Bottom Water (NEABW).

How to cite: Voelker, A. H. L., Salgueiro, E., Reverdin, G., Fontela, M., Abrantes, F., and van Geldern, R.: Monitoring hydrographic changes in the mid-latitudinal Northeast Atlantic Ocean using seawater stable isotope data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11848, https://doi.org/10.5194/egusphere-egu24-11848, 2024.

EGU24-12179 | Posters on site | CL5.9 | Highlight

Uncovering 'Hidden' Insights from the Ocean in the PAGES CoralHydro2k Seawater δ18O Database  

Alyssa R Atwood, Andrea L Moore, Sylvia Long, Raquel Pauly, Emilie Dassie, Jessica Hargreaves, Kristine L DeLong, Chandler Morris, Sara C Sanchez, Amy J Wagner, and Thomas Felis

The oxygen isotope ratio (δ18O) of seawater is a powerful tracer of the global water cycle, providing valuable information on the exchange of water between the ocean, atmosphere, and cryosphere as well as on ocean mixing processes. As such, observational seawater δ18O data place powerful constraints on hydrologic changes in the modern ocean, are essential for calibrating paleoclimate proxies based on the δ18O of marine carbonates, and are an increasingly critical diagnostic tool for assessing model performance and skill in isotope-enabled global climate models. In recognition of the broad value of seawater δ18O data to the Earth science community and the growing number of new seawater δ18O data sets that have been generated over the last decade, we launched the PAGES CoralHydro2k Seawater δ18O Database Project in 2020 to recover ‘hidden’ seawater oxygen isotope data sets. We have collated these records and combined them with public data to create a new, machine-readable, and metadata-rich database that aligns with findability, accessibility, interoperability, and reusability (FAIR) standards for digital assets.

Here, we present a summary of our crowdsourcing efforts and description of the database to date, and report initial findings from the new database. The database consists of over 19,000 observations of seawater δ18O with more than 50 metadata fields. We compare seawater δ18O variability from the database to that simulated by a suite of isotope-enabled climate models and to seawater δ18O reconstructions derived from coral records and find substantial differences at annual to decadal timescales across different data sets. Lastly, we discuss the potential for future investments in water isotope observation networks to tackle 21st century science questions related to ocean changes in the past, present, and future.

How to cite: Atwood, A. R., Moore, A. L., Long, S., Pauly, R., Dassie, E., Hargreaves, J., DeLong, K. L., Morris, C., Sanchez, S. C., Wagner, A. J., and Felis, T.: Uncovering 'Hidden' Insights from the Ocean in the PAGES CoralHydro2k Seawater δ18O Database , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12179, https://doi.org/10.5194/egusphere-egu24-12179, 2024.

Precise and accurate measurements of the stable isotope composition of water with cavity ring down laser spectrometers require post-processing and calibration of raw analytical signals that involves a number of critical procedures to counteract instrumental drift, inter-sample memory effects, and the quantification of total uncertainty. Due to advent of off-the-shelf water isotope analyzers, there is an increased demand from a variety of new, often smaller labs to obtain guidance and assistance when performing such tasks.

Here we present a new, lightweight, free software tool for the post-processing and calibration of water isotope data files from Picarro-brand cavity ring-down spectrometers. It is developed at the Facility for Advanced Isotopic Research and Monitoring of Weather, Climate and Biogeochemical Cycling (FARLAB) at the University of Bergen. FLIIMP1 (FARLAB liquid water isotope measurement processor) is written in MATLAB, but also exists as downloadable precompiled code and runs on Windows, MacOS and Linux. In its current version 2.1, FLIIMP facilitates sample processing by a graphical user interface that guides the user along the processing steps from corrections for memory effects, drift, and mixing ratio to calibration. FLIIMP provides detailed memory correction procedures, creates calibration reports and data files, and includes tools to monitor long-term measurement system behavior. Being an open-source software for the major operating systems, users can adapt FLIIMP to their laboratory environment, and the community can contribute to the software development. We hope that adoption of FLIIMP at other laboratories will lead to its further development into a mature set of calibration and correction routines for consistent, accurate, well-documented measurements of the stable isotope composition in liquid water samples.

 

1 Sodemann, H, Mørkved, PT, and Wahl, S. (2023) FLIIMP - a community software for the processing, calibration, and reporting of liquid water isotope measurements on cavity-ring down spectrometers. Methods X 11:2023 DOI:https://doi.org/10.1016/j.mex.2023.102297

 

How to cite: Mørkved, P. T., Sodemann, H., and Wahl, S.: FLIIMP - a free, open source software for the processing, calibration and reporting of liquid water isotope measurements on cavity-ring down spectrometers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16217, https://doi.org/10.5194/egusphere-egu24-16217, 2024.

EGU24-17734 | Posters on site | CL5.9

Implementing and simulating the water isotopes (δ18O and δD) distribution in the Mediterranean Sea using a high-resolution oceanic model  

Mohamed Ayache, Jean-Claude Dutay, Anne Mouchet, Kazuyo Tachikawa, Camille Risi, and Gilles Ramstein

Water isotopes are one of the most widely used proxies in ocean climate research. However, there are still gaps in our understanding of the processes that control their composition.  Compared to other large ocean basins, the Mediterranean is ideally suited to improve our understanding of the processes influencing and driving oxygen isotopic variability, and to refine the current modelling approach. For the first time in a high-resolution Mediterranean dynamical model (NEMO-MED12), stable water isotopes (δ18O and δD) were successfully implemented and simulated in the whole basin. The well-known east-west gradient of δ18O in Mediterranean water masses is successfully simulated by the model. Results also show good agreement between simulated and observed δD. δD shows a strong linear relationship with δ18O (r2 = 0.98) and salinity (r2 = 0.94) for the entire Mediterranean basin. Furthermore, the modelled δ18O/salinity relationships are in good agreement with observations, with a weaker gradient simulated in the eastern basins than in the western basins. We investigate the relationship of the isotopic signature of the CaCO3 shell (δ18Oc) with temperature and the influence of seasonality. Our results suggest a more quantitative use of δ18O records, combining reconstruction with modelling approaches. This opens up broad perspectives for paleoclimate-related applications.

How to cite: Ayache, M., Dutay, J.-C., Mouchet, A., Tachikawa, K., Risi, C., and Ramstein, G.: Implementing and simulating the water isotopes (δ18O and δD) distribution in the Mediterranean Sea using a high-resolution oceanic model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17734, https://doi.org/10.5194/egusphere-egu24-17734, 2024.

EGU24-19941 | ECS | Posters on site | CL5.9

Investigating upper ocean salinity changes over the past three decades in the Indian sector of the Southern Ocean 

Camille Akhoudas, Jean-Baptiste Sallée, Matthis Auger, Gilles Reverdin, Alexander Haumann, Claire Lo Monaco, Nicolas Metzl, and Christian Stranne

The Southern Ocean is undergoing rapid transformations, marked by significant regional shifts in salinity that carry widespread and irreversible consequences. While the most noticeable changes are observed in the upper ocean, changes in deeper water masses have been identified and are expected to intensify over time. Changes in upper-ocean water mass salinity can be influenced by multiple drivers, and play a crucial role in changing ocean dynamics. However, the underlying causes of these characteristic changes remain poorly understood. In this study, we present a unique three-decade time-series focusing on salinity and oxygen isotopes in the upper 1200 m of the Indian sector of the Southern Ocean. Two regions emerge with pronounced surface ocean salinity trends: freshening of subpolar waters and salinification of subtropical waters. These robust changes in surface salinity are associated with an observed freshening of intermediate and winter waters in the subpolar sector of the Indian sector over the past three decades. Our findings reveal salinity changes of comparable magnitude to those reported in other regions of the upper-ocean water masses in the Southern Ocean. The oxygen isotope data allows for discriminating between different freshwater processes, showing that in the subpolar region, surface freshening is largely caused by the increase in net precipitation, while the decrease in sea ice melt is largely offset by the contribution of glacial meltwater at these latitudes. These changes strengthen the growing evidence of an acceleration of the hydrological cycle and a melting cryosphere resulting from human-induced climate change, which affect Southern Ocean water mass characteristics.

How to cite: Akhoudas, C., Sallée, J.-B., Auger, M., Reverdin, G., Haumann, A., Lo Monaco, C., Metzl, N., and Stranne, C.: Investigating upper ocean salinity changes over the past three decades in the Indian sector of the Southern Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19941, https://doi.org/10.5194/egusphere-egu24-19941, 2024.

EGU24-21082 | ECS | Posters virtual | CL5.9

Simultaneous Onboard Analysis of Seawater Dissolved Inorganic Carbon (DIC) Concentration and Stable Isotope Ratio (δ13C-DIC) 

Zhentao Sun, Xinyu Li, Zhangxian Ouyang, Qian Li, Charles Featherstone, Eliot Atekwana, Najid Hussain, Yiwen Pan, and Wei-Jun Cai

Dissolved inorganic carbon (DIC) concentration and stable carbon isotope value (δ13C-DIC) are valuable for studying aquatic carbon cycles. These parameters reveal significant geochemical insights, such as the discernible effect of ocean anthropogenic CO2 uptake, the primary control of surface δ13C-DIC distribution by photosynthesis and respiration against a meridionally variable air-sea equilibrium background, and the notable impact of terrestrial carbon inputs in estuarine environments. However, one cannot take full advantage of this coupled pair as only 15% or less of water samples during past ocean cruises and very few coastal ocean samples have been analyzed for δ13C-DIC as the traditional isotope analytical technology is labor-intensive and limited in shore-based laboratories. This study reports a rapid and cost-effective method based on Cavity Ring-Down Spectroscopy (CRDS) for automatically and simultaneously analyzing DIC concentration and δ13C-DIC on shipboard. Compared to traditional techniques, our analyzer is more portable and operational-friendly. We also prepared and preserved a set of stable in-house NaHCO3 standards for seawater δ13C-DIC calibration during long cruises. This work represents the first effort to collect a large dataset of δ13C-DIC onboard on any oceanic transect; here along the North American eastern ocean margins in summer 2022. We efficiently processed 30 samples daily per analyzer over a 40-day expedition with excellent on-site uncertainty of ±1.1 μmol kg-1 for the DIC concentration and ±0.03‰ for the δ13C-DIC value (1σ). The duplicates taken from varying depths demonstrated high consistency with average standard deviations of 1.6 μmol kg-1 for DIC concentrations ranging between 1900 and 2300 μmol kg-1 and 0.04‰ for δ13C-DIC from -0.5‰ to 1.8‰. The DIC concentration measurements of CRM displayed average discrepancies of 1.4±1.7 μmol kg-1 for Batch #188 and 1.0±1.1 μmol kg-1 for Batch #195 against certified values, indicating reliable accuracy. Our δ13C-DIC analysis of CRM from Batch #188 yielded an average of -0.20±0.04‰, closely matching the reference value of -0.19±0.02‰ obtained by Isotope Ratio Mass Spectrometry (IRMS). Consistent standard deviations for δ13C-DIC of CRM from Batch #188 (0.04‰, n = 36) and Batch #195 (0.03‰, n = 7) further affirmed the potential utility of CRM as a viable liquid standard for δ13C-DIC measurements in seawater. An interlaboratory comparison of DIC analysis with NOAA/AOML revealed an average offset of 2.0±3.8 μmol kg-1 between onboard CRDS measurements and Coulometry results. Moreover, the cross-validation of δ13C-DIC against historical deep-ocean data exhibited a mean difference of only -0.04±0.06‰, emphasizing the high quality of our data.

How to cite: Sun, Z., Li, X., Ouyang, Z., Li, Q., Featherstone, C., Atekwana, E., Hussain, N., Pan, Y., and Cai, W.-J.: Simultaneous Onboard Analysis of Seawater Dissolved Inorganic Carbon (DIC) Concentration and Stable Isotope Ratio (δ13C-DIC), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21082, https://doi.org/10.5194/egusphere-egu24-21082, 2024.

EGU24-599 | ECS | Posters on site | AS1.22

Langragian analysis of the extreme-windstorm dynamics associated to post-tropical cyclone Leslie landfall in Portugal 

Miguel Lima, Luana C. Santos, Rita M. Cardoso, Pedro M. M. Soares, and Ricardo M. Trigo

Windstorms in Europe are responsible for more than half of the economic loss associated with natural disasters. In October 2018 a post-tropical cyclone, formerly Hurricane Leslie, made landfall in continental Portugal. This event was characterized by very intense winds, with a gust record-hitting value of 176 km/h registered near Figueira da Foz, a coastal city located in the center of the country. The main factors causing this event of extreme winds were likely a “cold-conveyor belt jet” or a “jet sting”, roughly 12 hours after losing its main tropical characteristics. Despite the strong impact associated with this windstorm there are still few studies modeling this kind of dynamics, and here we present a simulation and thorough analysis of the rare dynamics linked with this post-tropical cyclone affecting western Europe.

The WRF-ARW model, version 4.4.1, was used to numerically model Leslie as it transitioned from a hurricane to post-tropical cyclone. Three one-way nested domains were used with a large (5 km), medium (1 km), and lower (200m) resolution, with 68 hybrid levels (15 m - 20 hPa). The larger domain covers the Iberian Peninsula and a large portion of the Atlantic Ocean nearby, while the inner ones are focussed in the central and northern sectors of continental Portugal - the most affected areas. Initial and boundary conditions were retrieved from the GFS operational analysis at 0.25º spacing, in 6-hour intervals. Due to the difficulties modeling this cyclone, nudging was used in the outer domain to ensure that the cyclone would make landfall as close as possible to the real location.

Several state-of-the-art thermodynamics-based diagnostics were used to analyze in-depth the midlatitude cyclone dynamics observed in the recently transitioned cyclone Leslie. Midlatitude cyclone-related dynamics were identified in the simulation, leading to the extreme winds in the most impacted region. The set of final simulated data reveals a close resemblance to the real event, with parameterized wind gusts presenting a lower intensity around 140 km/h, but the largest values impacting approximately the same region of center Portugal. A Langragian approach was also used to study particle trajectories and evaluate the atmospheric circulation leading to the extreme winds showing vertical downdrafts up to 4 m/s. This study highlights the catastrophic potential a post-tropical cyclone such as Leslie has and, while at the end of their life-time with presumably less intensity, storms of this type should not be disregarded for warnings and need to be considered in general evaluations of midlatitude storm impacts.

Acknowledgements: This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020. M. M. Lima was supported through the PhD MIT Portugal MPP2030-FCT programme grant PRT/BD/154680/2023. L. C. Santos is supported by the EarthSystems Doctoral School, at University of Lisbon, supported by Portuguese Fundação para a Ciência e a Tecnologia (FCT) project UIDP/50019/2020-2023, University of Lisbon.

How to cite: Lima, M., C. Santos, L., M. Cardoso, R., M. M. Soares, P., and M. Trigo, R.: Langragian analysis of the extreme-windstorm dynamics associated to post-tropical cyclone Leslie landfall in Portugal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-599, https://doi.org/10.5194/egusphere-egu24-599, 2024.

EGU24-1418 | ECS | Posters on site | AS1.22 | Highlight

Windstorm losses in Europe - What to gain from damage datasets 

Julia Moemken, Gabriele Messori, and Joaquim G. Pinto

Windstorms are among the most impacting natural hazards affecting Western and Central Europe. Information on the associated impacts and losses are essential for risk assessment and the development of adaptation and mitigation strategies. In this study, we compare reported and estimated windstorm losses from five datasets belonging to three categories: Indices combining meteorological and insurance aspects, natural hazard databases, and loss reports from insurance companies. We analyse the similarities and differences between the datasets in terms of reported events, the number of storms per dataset and the ranking of specific storm events for the period October 1999 to March 2022 across 21 European countries.

A total of 94 individual windstorms were documented. Only 11 of them were reported in all five datasets, while the large majority (roughly 60%) was solely recorded in single datasets. Results show that the total number of storms is different in the various datasets, although for the meteorological indices such number is fixed a priori. Additionally, the datasets often disagree on the storm frequency per winter season. Moreover, the ranking of storms based on reported/estimated losses varies in the datasets. However, these differences are reduced when the ranking is calculated relative to storm events that are common in the various datasets. The results generally hold for losses aggregated at European and at country level.

Overall, the datasets provide different views on windstorm impacts. Thus, to avoid misleading conclusions, we use no dataset as “ground truth” but treat all of them as equal. We suggest that these different views can be used to test which features are relevant for calibrating windstorm models in specific regions. Furthermore, it could enable users to assign an uncertainty range to windstorm losses. We conclude that a combination of different datasets is crucial to obtain a representative picture of windstorm associated impacts.

How to cite: Moemken, J., Messori, G., and Pinto, J. G.: Windstorm losses in Europe - What to gain from damage datasets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1418, https://doi.org/10.5194/egusphere-egu24-1418, 2024.

EGU24-1553 | ECS | Posters on site | AS1.22

An Investigation into the Role of the Ocean for Seasonal Predictability of European Windstorms 

Kelvin S. Ng and Gregor C. Leckebusch

Extreme extra-tropical cyclones and related windstorms are the most dangerous and costly meteorological hazards in Europe. The latest state-of-the-art seasonal forecast suites show now usable forecast skill for basic parameters like mean temperature or precipitation for mid-latitude Europe on lead times of up to 4 months (Nov-Feb). One avenue for skilful prediction of extremes is the now-proven forecast skill for large-scale climate modes, as these directly influence extreme windstorms. Improved ability to simulate successfully the relevant large-scale climate patterns like e.g., the North-Atlantic Oscillation, the East-Atlantic pattern, and/or the Scandinavian pattern opens up a prominent route to progress the forecast skill for extreme storms.

Nevertheless, recent publications have shown that even in the current model suites, the existing skill for forecasting the frequency or intensity of windstorm tail events, is not fully explained by those dominant large-scale variability patterns. Furthermore, studies revealed a potential connectivity of storm count predictions to stratospheric sudden warming events and also highlighting the influence of atmosphere-ocean coupling. Recent developments in the forecast skill of the upper-ocean heat content and the role of re-emerging temperature anomalies for the European winter climate allow to explore another pathway with potentially predictive power, the role of ocean-atmosphere interaction. Ocean-atmosphere interaction caused e.g., by the NAO have been increasingly recognised but have not been systematically linked to the ability to predict extreme severe windstorms on a seasonal time scale. In this presentation, we will present preliminary results of the role of ocean on the predictability of European windstorms.

How to cite: Ng, K. S. and Leckebusch, G. C.: An Investigation into the Role of the Ocean for Seasonal Predictability of European Windstorms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1553, https://doi.org/10.5194/egusphere-egu24-1553, 2024.

EGU24-1736 | ECS | Posters on site | AS1.22 | Highlight

Intra-seasonal variability of temporal clustering of European winter windstorms 

Sophie Feltz, Gregor C. Leckebusch, Kelvin S. Ng, and Tim Kruschke

Severe European winter windstorms are one of the most damaging natural hazards and thus a major threat to societies. Clustered European winter windstorms, storms that occur in quick succession over a specific period of time over a fixed location, can result in amplified structural and environmental damage and accumulated losses. Yet, variability of storm clustering on intra-seasonal timescales has not been fully investigated. We analyse winters (DJF) for the period 1981-2016 from ERA5 reanalysis, where tracks and storm impact footprints are identified through the impact-oriented wind-based tracking algorithm WiTRACK.  

We quantify the magnitude of clustering using the widely employed dispersion statistic as used in Mailier et al. (2006). The spatial distribution of clustering on 45- and 30-day timescales as well as the time development of clustering on even shorter 30-, 20-, 15- and 11-days reference periods are investigated. Thus, in a seamless approach from seasonal to synoptic clustering. Results from both windstorm clustering of tracks and the storm footprints will be presented. Preliminary findings suggest an increase in clustering occurrence in the later half of the winter season on 45- and 30-day timescales.  On shorter timescales (<30 days), depending on location, distinct periods of increased clustering e.g., in the middle and the end of the season can be identified.

How to cite: Feltz, S., Leckebusch, G. C., Ng, K. S., and Kruschke, T.: Intra-seasonal variability of temporal clustering of European winter windstorms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1736, https://doi.org/10.5194/egusphere-egu24-1736, 2024.

EGU24-1974 | ECS | Posters virtual | AS1.22

Shifting of Western Disturbances winter precipitation over Western Himalayas 

Pooja Pooja and Ashok Priyadarshan Dimri

The Indian Himalayan region receives an enormous amount of precipitation due to synoptic weather systems known as Western Disturbances (WDs). WDs are east-ward propagating systems embedded in the Subtropical Westerly Jetstream (SWJ). The main objective of this study is to investigate the change in magnitude and dynamics of WDs precipitation over the western Himalayan region. In this study, different observational datasets (IMD, AHRODITE, GPCP, GPCC, and ERA5) were selected to compare and assess the magnitude of WDs precipitation for the period 1987–2020 during the winters (DJF: December, January, and February). Further, to examine the structure of WDs precipitation at the pressure level of 200hPa, ERA5 Reanalysis datasets having a similar resolution of 25 km with the gridded dataset of the Indian Meteorological Department (IMD) are used for the analysis. WDs moisture sources from the Arabian Sea are assessed at 23 pressure levels (1000–200 hPa) for further understanding of WDs dynamics. Our study shows the daily shifting of WDs precipitation towards February during the winters and an intriguing decrease in daily WDs precipitation in recent years. During the study, we found that WDs precipitation contributed a significant amount of precipitation (~80%) over the Western Himalayan region of the Indian subcontinent. Using Theil-Sen method, trend analysis was performed, showing a decreased trend of WDs precipitation in recent years The present findings indicate that WDs have changed their precipitation characteristics and dynamics due to climate change. The number of active WDs days is decreasing. Our results show there is enough moisture present over the Bay of Bengal region other than WDs which helps in sustaining and replenishing glaciers over the Indian Himalayan region.

How to cite: Pooja, P. and Dimri, A. P.: Shifting of Western Disturbances winter precipitation over Western Himalayas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1974, https://doi.org/10.5194/egusphere-egu24-1974, 2024.

EGU24-3651 | ECS | Orals | AS1.22

Air-Sea Flux Influences on Extratropical Cyclone and Atmospheric River Mesoscale Development and Upstream Temporal Clustering 

Juan Crespo, Catherine Naud, Rosa Luna-Niño, James Booth, and Derek Posselt

Latent and sensible heat fluxes (LHF and SHF, respectively) within the marine boundary layer are believed to play a significant role in the genesis and evolution of Extratropical Cyclones (ETCs) and Atmospheric Rivers (ARs, often associated with ETCs in the midlatitudes). However, consistent observations of air-sea interactions with in-situ observatories are limited in both time and space, and traditional polar orbiting satellites may miss large swaths in the lower midlatitudes due to their orbits, leading to daily gaps in coverage where the most robust fluxes often occur and change rapidly. Satellite missions like CYGNSS (Cyclone Global Navigation Satellite System) have filled in data gaps by providing improved observations over the lower midlatitudes of air-sea interactions. These improved observations of air-sea processes, coupled with observations of cloud and precipitation structure within ETCs and ARs from other satellites, like GPM and MODIS, can help one begin to link the correlations between surface heat fluxes to changes of the mesoscale features within these synoptic-scale systems. Previous studies have shown the correlation of observed surface heat fluxes to precipitation and cloud thickness increases along the frontal regions. Still, they have only looked at the connections between ETCs and ARs when LHF and SHF were at their strongest or the peak intensity of the system, not during its early formation (or just before formation) when they may be at their strongest. 

Additionally, recent studies have examined through idealized models how surface heat fluxes within an ETC can impact the development of ETCs and ARs upstream of the primary cyclone and lead to multiple ETCs in succession, often called a family or temporal clustering of ETCs and ARs. This clustering can lead to significant and excessive precipitation over parts of the globe, such as the United States West Coast in early 2023, with successive ARs over one month. Improved observations of real-world conditions can help us better understand the interplay within these systems. This presentation will highlight the role air-sea interactions may have during the genesis and early evolution of ETCs and ARs, the correlations to cloud and precipitation structure changes, the upstream impacts, and setting the groundwork that will be able to show that air-sea interactions directly impact the development of these systems.

How to cite: Crespo, J., Naud, C., Luna-Niño, R., Booth, J., and Posselt, D.: Air-Sea Flux Influences on Extratropical Cyclone and Atmospheric River Mesoscale Development and Upstream Temporal Clustering, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3651, https://doi.org/10.5194/egusphere-egu24-3651, 2024.

EGU24-3675 | Orals | AS1.22 | Highlight

Poleward intensification of midlatitude extreme winds under warmer climate 

Emanuele Silvio Gentile, Ming Zhao, and Kevin Hodges

In this work, we investigate the global impact of midlatitude cyclones on the geographical distribution and intensity of near-surface extreme wind speeds in a warmer climate. We use  state-of-the-art high-resolution general circulation models developed by the Geophysical Fluid Dynamics Laboratory. Results indicate a clear poleward shift of extreme wind speeds, driven by the associated shift in midlatitude storm tracks, and attributed to global warming and associated changes in general circulations. The total number of midlatitude cyclones decreases by roughly 4%, but the proportion of cyclone-associated extreme wind speed events increases by 10% in a warmer climate. Notably, the research has identified Northwestern Europe, the British Isles, and the West Coast of North America as hot spots with the greatest socio-economic impacts from increased cyclone-associated extreme winds. In addition, we also use the GFDL ultra-high resolution global storm resolving model to study cyclone-associated extreme winds.

How to cite: Gentile, E. S., Zhao, M., and Hodges, K.: Poleward intensification of midlatitude extreme winds under warmer climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3675, https://doi.org/10.5194/egusphere-egu24-3675, 2024.

EGU24-3750 | ECS | Orals | AS1.22

Perturbation Energetics of the December 2022 Bomb Cyclone over North America 

Emerson DeLarme, Jianping Li, Hongyuan Zhao, Yuan Liu, and Ruipeng Sun

Bomb cyclones over land are an understudied phenomenon. As such, there are open questions about the underlying physical processes, for example, why do bomb cyclones stop deepening. Atmospheric energetics is a prevalent approach to solve such problems, however the commonly used method of Available Potential Energy is not valid at local scales. Therefore, this study aims to provide further insight into the life cycle of bomb cyclones, specifically over land, by conducting a case study of the bomb cyclone that occurred over North America at the end of December 2022, focusing on the energetics using the Perturbation Potential Energy (PPE) framework. Hourly ERA5 reanalysis data provides the improved time resolution needed to study the evolution of such a rapidly developing system. PPE analysis of the evolution of this bomb cyclone reveals a possible stop signal to the positive feedback loop associated with explosive deepening. Further research is needed to clarify the mechanics associated with this thermodynamic signal.

How to cite: DeLarme, E., Li, J., Zhao, H., Liu, Y., and Sun, R.: Perturbation Energetics of the December 2022 Bomb Cyclone over North America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3750, https://doi.org/10.5194/egusphere-egu24-3750, 2024.

EGU24-5188 | ECS | Posters on site | AS1.22

A climatology of Mediterranean cyclones and compound weather extremes 

Alice Portal, Olivia Martius, Shira Raveh-Rubin, and Jennifer L Catto

Mediterranean cyclones are the main driver of surface weather extremes in the Mediterranean region. In this work we establish a new procedure for the attribution of different types of meteorological extremes to Mediterranean cyclones, where we also distinguish the presence of different airflows (warm conveyor belts, dry intrusions) and fronts composing the structure of a cyclone. We apply the procedure to a dataset of rain-wind and wave-wind compound extremes extracted from ERA5 reanalysis in a recent climatological period, and show that the majority of weather compounds occurring in the Mediterranean area is indeed linked to the presence of a nearby cyclone. The association of compound rain-wind events with Mediterranean cyclones locally surpasses an 80% level, while interesting differences between transition seasons and winter are detected. Winter cyclones - generally stronger, larger and distinctively baroclinic - are associated with a higher compound density. The de-construction of the cyclone in airflows and fronts evidences a strong association of rain-wind compounds with regions of warm conveyor belt ascent, and of wave-wind compounds with regions of dry intrusion outflow.

How to cite: Portal, A., Martius, O., Raveh-Rubin, S., and Catto, J. L.: A climatology of Mediterranean cyclones and compound weather extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5188, https://doi.org/10.5194/egusphere-egu24-5188, 2024.

EGU24-6370 | ECS | Posters on site | AS1.22

A catastrophe model for Windstorm in Italy: developing a stochastic windstorm event set adjusted with open-access reanalysis datasets 

Lorenzo Aiazzi, Simone Persiano, Michele Bottazzi, Glauco Gallotti, Antonio Petruccelli, Farid Ait-Chaalal, and Giovanni Leoncini

Windstorms are one of the most destructive natural disasters in Europe, causing considerable human and economic impacts, ranging from fatalities and injuries to damage to agriculture, infrastructures, and properties. The European Commission’s Joint Research Centre (JRC) estimates annual losses of 5 €-billion for the European Union and United Kingdom (Spinoni et al., 2020). While in these areas there is not high confidence on the projected changes in windstorm intensity and frequency due to climate change (Ranasinghe et al., 2021), damages resulting from windstorms will most likely increase in the future due to the appreciation of asset values (Spinoni et al., 2020).

Although Italy is one of the most affected European countries, with annual absolute losses estimated above 0.5 €-billion (Spinoni et al., 2020), windstorm is still considered to be a secondary peril. However, severe windstorm events in the last few years (e.g., Storm Vaia in October 2018) have raised an increasing interest of the Italian insurance industry in understanding and modelling this peril.

In this context, we aim at developing a catastrophe model that quantifies the financial impacts of windstorms on the insurance market in Italy. To this aim, here we perform the calibration of a stochastic windstorm event set for the hazard component of the model. Uncalibrated footprints are obtained from simulation outputs of global and regional numerical models. Then, historical event footprints are extracted from open-access reanalysis datasets (e.g., ERA5, CERRA) and used to correct the climatology of the stochastic set and to adjust the wind-speeds of its individual events. This analysis is expected to be preparatory for the development of a comprehensive catastrophe model that combines wind hazard with exposure and vulnerability to assess windstorm-related financial losses in Italy.

 

References:

Ranasinghe, R., et al., 2021: Climate Change Information for Regional Impact and for Risk Assessment. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., et al., (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1767–1926, doi: 10.1017/9781009157896.014.

Spinoni, J., et al., 2020: Global warming and windstorm impacts in the EU, EUR 29960 EN, Publications Office of the European Union, Luxembourg, 2020, ISBN 978-92-76-12955-4, doi:10.2760/039014. JRC118595.

How to cite: Aiazzi, L., Persiano, S., Bottazzi, M., Gallotti, G., Petruccelli, A., Ait-Chaalal, F., and Leoncini, G.: A catastrophe model for Windstorm in Italy: developing a stochastic windstorm event set adjusted with open-access reanalysis datasets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6370, https://doi.org/10.5194/egusphere-egu24-6370, 2024.

EGU24-7310 | ECS | Orals | AS1.22

Unlocking the dynamics of extreme wind speeds of North Atlantic storms 

Jun-Hyeok Son, Christian L.E. Franzke, and Seok-Woo Son

North Atlantic extra-tropical storms are some of the most severe weather systems, causing enormous economic damages and threatening human lives. In general, these storms are characterized by strong cyclonic convergent surface winds, upward vertical flow, and precipitation. In specific confined areas inside the storm where downward flows occur with clear sky, extreme surface wind speeds are observed. Such a horizontal variation of vertical wind direction and surface wind speed can cause severe and damaging impacts; however, the underlying key dynamics are not understood. Here we show the dynamical and thermodynamical linkage between the horizontal wind impinging on the frontal surface at the lower troposphere, downward flow, and very intense surface wind speeds inside the storm. The anti-clockwise cyclonic wind into the cold frontal area is mainly responsible for generating the downward flow, which transports the high-altitude horizontal momentum to the surface layer causing intense surface wind speeds. About half of North Atlantic storms accompany the downward wind, and that downward flow is more frequently observed in the southern and western part of the storm center. Overall results illuminated in this paper have a far-reaching impact in multiple ways to enhance forecasting skills for devastating weather events associated with extra-tropical storms.

How to cite: Son, J.-H., Franzke, C. L. E., and Son, S.-W.: Unlocking the dynamics of extreme wind speeds of North Atlantic storms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7310, https://doi.org/10.5194/egusphere-egu24-7310, 2024.

EGU24-7801 | ECS | Posters on site | AS1.22

Environmental Characteristics Associated with the Tropical Transition of Mediterranean Cyclones 

Lisa Bernini, Leone Cavicchia, Fabien Desbiolles, Antonio Parodi, Claudia Pasquero, and Enrico Scoccimarro

Using tracks from a reference dataset (Flaounas et al., 2023), cyclones in the Mediterranean Sea have been classified based on thermal winds (Hart, 2003). This classification allowed us to explore the major differences between extra-tropical cyclones with a cold inner core and tropical-like cyclones with a
deep inner warm core. For that purpose, the time evolution along the cyclones’ lifetime of different environmental characteristics taken from the ERA5 reanalysis has been studied. Warm-core cyclones are characterized by higher surface wind speeds, larger air-sea fluxes, and more intense precipitations. In comparison to cold-core cyclones, their development is favored by low wind shear and high moisture levels in the mid-troposphere. Different proxies also attest the major importance of the convective process in the establishment of the warm core. Finally, their dissipation seems to be driven by an abrupt decrease in the mid-level moisture content. This decrease is possibly related to the occlusion phase of the cyclone, and not to a limitation of moisture supply at the surface due to landfall.

How to cite: Bernini, L., Cavicchia, L., Desbiolles, F., Parodi, A., Pasquero, C., and Scoccimarro, E.: Environmental Characteristics Associated with the Tropical Transition of Mediterranean Cyclones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7801, https://doi.org/10.5194/egusphere-egu24-7801, 2024.

EGU24-8101 | ECS | Posters on site | AS1.22

Past and future Mediterranean cyclone characteristics using a regional climate model 

Onno Doensen, Martina Messmer, Woon Mi Kim, and Christoph Raible

Extratropical cyclones play a dominant role in the Mediterranean. They are important for local water supplies, but they can also cause severe damage due to heavy winds, extreme precipitation and coastal floods. Over the last decades, a decrease in the number of extratropical cyclones in the Mediterranean has been observed. Climate models suggest that this decreasing trend will continue in the future under global warming, leading to fewer storms and dryer conditions over the region compared to the present. However, it is much less clear how extreme cyclones in the Mediterranean will respond to climate change. Our previous study, based on a simulation from the Community Earth System Model (CESM) covering the last 3500 years, indicates that extreme cyclones show a distinct centennial variability in frequency, cyclone-related precipitation and wind speed. In addition, we found a weak relation between atmospheric circulation modes and varying cyclone characteristics across different regions in the Mediterranean. However, the coarse horizontal resolution of CESM (2.0°×2.5°) is not very well suited to resolve the mesoscale cyclones that often occur in the Mediterranean. For this study, we downscaled the CESM simulation for the period 1821–2100 (RCP8.5 scenario from 2005 onwards) to a horizontal grid resolution of 20 km using the Weather Research and Forecasting (WRF) model. The WRF simulation can resolve the cyclone characteristics in the Mediterranean more accurately than CESM. Additionally, the WRF simulation is able to reproduce the complexity of cyclone-related wind speed and precipitation in a much more detailed way. Preliminary results show a strong decrease in cyclone frequency as a result of global warming. However, this trend is much less clear for extreme cyclones with respect to wind speed and precipitation. Using the long downscaled WRF simulation, we intend to identify characteristics in CESM that lead to extreme wind and precipitation in the downscaled simulation. Additionally, we will investigate the most extreme wind and precipitation events in the Mediterranean to understand what processes are better captured at smaller scales than in the global model.

How to cite: Doensen, O., Messmer, M., Kim, W. M., and Raible, C.: Past and future Mediterranean cyclone characteristics using a regional climate model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8101, https://doi.org/10.5194/egusphere-egu24-8101, 2024.

EGU24-10642 | ECS | Orals | AS1.22

Synoptic perspective on the conversion and maintenance of local available potential energy in extratropical cyclones 

Marc Federer, Lukas Papritz, Michael Sprenger, Christian M. Grams, and Marta Wenta

The global atmospheric circulation is maintained by the conversion of available potential energy (APE) into kinetic energy. At midlatitudes, this conversion occurs to a large extent in extratropical cyclones through baroclinic instability. Although kinetic energy is easily defined locally, APE is typically defined as a global integral. Therefore, local APE conversion is not well understood.

Here, we investigate local APE conversion within the North Atlantic storm track using ERA5 reanalysis data. We utilize a recently introduced formulation of APE, which is exact and defined locally for individual air parcels. First, we explore APE conversion during a period of rapid cyclogenesis, which we then extend to a climatology of extratropical cyclones.

Our results indicate that the synoptic upper-level flow determines the distribution of high APE values, which are primarily located in the high-latitude upper troposphere. We show that APE is converted locally into kinetic energy by descending air parcels within the ageostrophic circulation, for example, induced by a jet streak upstream of an extratropical cyclone. The local APE originates not only from advection from the polar, upper-tropospheric APE reservoir, but also from local generation by vertical motion. In fact, the net baroclinic conversion of APE to kinetic energy is the result of much larger positive and negative local contributions. Thus, the global Lorenz energy cycle is more complex on synoptic scales. In addition, we show that surface heat fluxes resulting from air-sea interactions and latent heat release act as diabatic sinks for APE. However, the effect of surface heat fluxes is small compared to the conversion of APE to kinetic energy, as little APE is located in the mid-latitude lower troposphere.

In summary, the study shows that the local APE perspective allows the energetics of North Atlantic extratropical cyclones to be better understood in terms of local APE advection as well as adiabatic (ascent and descent) and diabatic effects.

How to cite: Federer, M., Papritz, L., Sprenger, M., Grams, C. M., and Wenta, M.: Synoptic perspective on the conversion and maintenance of local available potential energy in extratropical cyclones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10642, https://doi.org/10.5194/egusphere-egu24-10642, 2024.

EGU24-11704 | Posters on site | AS1.22

Climate change signature on Euro-Mediterranean lee cyclogenesis 

Lorenzo Sangelantoni, Stefano Tibaldi, Leone Cavicchia, Daniele Peano, and Enrico Scoccimarro

This study explores whether and why a warmer climate induces alterations in climatological statistics and the underlying physical features of lee cyclogenesis in the Euro-Mediterranean region.

The investigation focuses on a specific cyclogenesis type, wherein orography (the Alps), influences the spatial structure and growth rate of the cyclone.

This regional scale phenomenon is inspected within the framework of a general weakening and poleward shift of the mid-latitude jet. This large-scale signal, despite being evident in zonal-averaged results from the majority of climate models, remains subject to considerable uncertainty when specific regions and seasons are considered. This uncertainty stems from the intricate interplay and delicate equilibrium among numerous competing mechanisms.

The analysis focuses on historical and future trends during the cold semesters across the Euro-Mediterranean region. The historical period is examined using ERA5 reanalysis spanning from 1940 to the present, supplemented by a higher-resolution regional reanalysis product (COSMO-REA6) at approximately 6 km resolution, covering the period 1995-2019 over the Euro-CORDEX (EUR11) domain. State-of-the-art high-resolution climate models are employed to assess historical reproducibility and future trends through an ensemble of global climate models from the HighResMIP initiative.

Methodologically, two distinct approaches are pursued. Firstly, changes in statistical properties of lee cyclogenesis are examined, along with composites of precipitation and wind extremes footprint, utilizing two tracking algorithms: TempestExtremes (Ullrich et al., 2021) and TRACK (Hodges, 1994). These algorithms differ in their identification/tracking variables, i.e., mean sea level pressure and 850hPa relative vorticity, respectively. Secondly, an empirical orthogonal function (EOF) analysis is employed to evaluate whether dominant spatial patterns of relevant variables (e.g., mean sea level pressure and 500hPa geopotential height) associated with cyclogenesis undergo significant changes across different time segments.

This investigation is conducted as a spin-off of the Copernicus-ECMWF-funded contract C3S2_413 - Enhanced Operational Windstorm Service. The findings aim to enhance our understanding of the complex dynamics of Euro-Mediterranean lee cyclogenesis in the context of a changing climate, providing further insights for climate science and operational windstorm services.

How to cite: Sangelantoni, L., Tibaldi, S., Cavicchia, L., Peano, D., and Scoccimarro, E.: Climate change signature on Euro-Mediterranean lee cyclogenesis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11704, https://doi.org/10.5194/egusphere-egu24-11704, 2024.

EGU24-13459 | ECS | Orals | AS1.22

Assessing high-resolution global climate models in simulating subtropical cyclones over the southeast coast of Brazil 

Andressa Andrade Cardoso and Rosmeri Porfírio da Rocha

Subtropical cyclones when occurring close to the coast can be very dangerous for human activities bringing high amounts of precipitation, intense winds and gusts in the coastal cities. This can lead to natural hazards and risks, such as floods, inundations, and even deaths. Over the southeast coast of Brazil, seven subtropical cyclones occur on average each year, with higher frequency in austral summer and autumn.  However, there are still few studies focusing on its global models climatology and future projections. It is crucial to evaluate how accurate are the global climate models of the new HighResMIP-CMIP6 dataset, with fine horizontal high-resolution, in representing subtropical cyclones in the historical period. Thus, this study assesses the classification of the subtropical cyclones based on two reanalyses (ERA5 and ERA-Interim) to evaluate the fine-resolution HighResMIP-CMIP6 datasets.  First, we tracked all cyclones over the South Atlantic Ocean applying an automatic scheme using relative vorticity at 925 hPa. Then, the vertical structure of the cyclones are accessed by calculating three parameters (symmetry, thermal wind at low and upper levels) from the cyclone phase space approach. Finally, we classified subtropical features using an automatic scheme based on a pre-establish threshold. In general, the approach is able for classifying subtropical cyclones providing realistic climatology. Overall, for the total of cyclones, ERA5, ERAInterim and HighResMIP-CMIP6 reproduce similar areas of great cyclogenetic activity over the eastern coast of South America.  In terms of frequency, it is greater in ERA5 than ERAInterim, for both total and subtropical cyclones, while a similar behavior is noted in relation to the seasonal frequency. HighResMIP-CMIP6 tends to overestimate the total of cyclones in subtropical latitudes, impacting directly the frequency of the subtropical ones. 

How to cite: Andrade Cardoso, A. and Porfírio da Rocha, R.: Assessing high-resolution global climate models in simulating subtropical cyclones over the southeast coast of Brazil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13459, https://doi.org/10.5194/egusphere-egu24-13459, 2024.

EGU24-14305 | Posters on site | AS1.22

Towards AI-enhanced prediction of Mediterranean cyclones 

Leone Cavicchia, Enrico Scoccimarro, and Silvio Gualdi

Intense cyclones form frequently in the Mediterranean region, with the potential to cause damage to life and property when they hit highly populated coastal areas. Cyclone impacts are caused by the associated strong winds, flash flooding and storm surge. The social and economic impacts are not limited to the Mediterranean area, as cyclones forming in the region can affect Central Europe. While the skill of weather models to forecast such events has dramatically improved over the last decade, the seasonal predictability of Mediterranean cyclones lags behind due to the limitations on horizontal resolution in probabilistic forecasts requiring a large ensemble of simulationss. Improving the climate prediction at a seasonal scale of those extreme events would be of great benefit for society, enabling better disaster risk management and reducing the economic losses they cause. A better prediction of climate extremes would also directly benefit a number of economic sectors such as the insurance and re-insurance industry.

The ambition of the CYCLOPS project is to use Artificial Intelligence techniques to enhance the prediction skills of Mediterranean cyclones in a state-of-the-art Seasonal Prediction System. Here we present initial results making use of AI to link those extreme events to their large-scale driver. The training of different machine learning models is performed using ERA5 reanalysis data. The assessment of model skill is evaluated on the C3S operational seasonal forecast in hindcast mode. The performance of machine learning models of varying complexity (e.g. random forest, artificial neural networks) is evaluated.

How to cite: Cavicchia, L., Scoccimarro, E., and Gualdi, S.: Towards AI-enhanced prediction of Mediterranean cyclones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14305, https://doi.org/10.5194/egusphere-egu24-14305, 2024.

EGU24-14720 | ECS | Posters on site | AS1.22

Mergers as the Maintenance Mechanism of Cutoff Lows: A Case Study over Europe in July 2021 

Koryu Yamamoto, Keita Iga, and Akira Yamazaki

A cutoff low that covered Central Europe in the middle of July 2021 brought heavy rainfall and severe flooding, resulting in more than 200 fatalities. This low was formed by a trough on 11 July and merged with another cutoff low around 12–13 July. Analysis of the energy budget and potential vorticity suggests that the main cutoff low was maintained through the merger with another cutoff low; this was the dominant contributor to maintenance of the main cutoff low around 12–13 July. The results of Lagrangian trajectory analyses support this conclusion. Analysis of diabatic PV modification during the merger indicates that radiation acts mainly to enhance the potential vorticity of the parcels when they move from another cutoff low into the main cutoff low, especially in the upper layer (~ 350 K). However, that effect is not pronounced in the lower layer (~ 330 K). These results demonstrate that cutoff lows can be maintained through the merger with another cutoff low and underline the need to consider diabatic processes when investigating mergers.

How to cite: Yamamoto, K., Iga, K., and Yamazaki, A.: Mergers as the Maintenance Mechanism of Cutoff Lows: A Case Study over Europe in July 2021, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14720, https://doi.org/10.5194/egusphere-egu24-14720, 2024.

EGU24-16593 | ECS | Posters on site | AS1.22

High-impact storms during the extended winters of 2018–2021 in the Iberian Peninsula 

Ana C. R. Gonçalves, Raquel Nieto, and Margarida L. R. Liberato

During the extended winter period from December 2017 to April 2021, the Iberian Peninsula (IP) was impacted by several high-impact storms characterized by intense precipitation and/or strong winds. This study provides a detailed assessment of the events, including synoptic conditions, large-scale dynamics associated with the storms, and a climatological analysis aimed at improving public understanding and preventing natural disasters. The analysis of the cyclones’ variability indicates that their maximum intensity varies between 955 hPa and 985 hPa, with a duration of two to four days, and the most frequent occurrence (eight events) was in January. At the peak of maximum intensity, the composite anomaly patterns showed lower mean sea level pressure (MSLP) values (−21.6 hPa), higher water vapor values (327.6 kg m−1s−1), and wind speed at 250 hPa exceeding 29.6 m s−1 the mean values. Additionally, there were high anomaly values of equivalent potential temperature (θe) of 19.1 °C at 850 hPa, sea surface temperature (SST) anomaly values of −1 °C, and negative anomaly values of surface latent heat flux (QE) (−150 W m−2) close to the IP. During the days impacted by the storms, the recorded values surpassed the 98th percentile in a significant percentage of days for daily accumulated precipitation (34%), instantaneous wind gusts (46%), wind speed at 10 m (47%), and concurrent events of wind/instantaneous wind gusts and precipitation (26% and 29%, respectively). These findings allow us to describe their meteorological consequences on the IP, particularly the effects resulting from intense precipitation such as floods, and strong winds associated with various destructive impacts. Finally, clear, real-time, and predictive information about weather systems and their impacts is crucial for the public to understand and enable effective responses to mitigate these natural hazards damage.

Keywords: extreme events; extratropical cyclones; explosive development cyclones; winter storms; Iberian Peninsula.

 

Acknowledgments

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC)–UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020), UIDP/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020), and project WEx-Atlantic (PTDC/CTAMET/29233/2017, LISBOA-01-0145-FEDER-029233, NORTE-01-0145-FEDER-029233). FCT is also providing for Ana Gonçalves doctoral grant (2021.04927.BD). The EPhysLab group was also funded by Xunta de Galicia, Consellería de Cultura, Educación e Universidade, under project ED431C 2021/44 “Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas.

 

 References

Gonçalves, A.C.R.; Nieto, R.; Liberato, M.L.R. Synoptic and Dynamical Characteristics of High-Impact Storms Affecting the Iberian Peninsula during the 2018–2021 Extended Winters. Atmosphere 2023, 14, 1353. https://doi.org/10.3390/atmos14091353

How to cite: C. R. Gonçalves, A., Nieto, R., and L. R. Liberato, M.: High-impact storms during the extended winters of 2018–2021 in the Iberian Peninsula, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16593, https://doi.org/10.5194/egusphere-egu24-16593, 2024.

EGU24-16634 | ECS | Posters on site | AS1.22

Drivers of Cold Frontal Hourly Extreme Precipitation: A Climatological Study 

Armin Schaffer, Tobias Lichtenegger, Douglas Maraun, Heimo Truhetz, and Albert Ossó

Understanding the processes driving extreme precipitation is paramount to socioeconomic interest. In the mid-latitudes extreme precipitation events are strongly associated with cold fronts. By exploring drivers across a wide range of scales, this study aims to improve our understanding of processes influencing frontal precipitation. Past research predominately focused on detailed studies of individual frontal extreme events. Here we present the first climatological study of frontal characteristics and their impact on precipitation.
Using hourly resolved ERA5 data, cold fronts are detected using the equivalent potential temperature gradient, and associated conditions from the synoptic to the meso-scale are identified. Further, seasonal and regional dependencies are explored. Quantile regression models are employed to find the strongest drivers of frontal precipitation and to quantify these relationships. Additionally, composite analysis are used to study the synoptic conditions and meso-scale structure of extreme events.
Findings reveal that humidity close to the frontal boundary, convergence of different scales and the low level jet speed contribute most to formation of extreme precipitation events. Interestingly, we discovered that stronger fronts, characterized by a significant change in humidity, do not always lead to a higher chance of extreme precipitation. This is evident in the weak correlation between the humidity gradient and frontal precipitation, in contrast with the relationship observed for the temperature gradient.
The findings of this study improve our understanding of cold frontal processes. Additionally, they provide the foundation to evaluate model performance and climate change projections. 

How to cite: Schaffer, A., Lichtenegger, T., Maraun, D., Truhetz, H., and Ossó, A.: Drivers of Cold Frontal Hourly Extreme Precipitation: A Climatological Study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16634, https://doi.org/10.5194/egusphere-egu24-16634, 2024.

EGU24-17127 | ECS | Orals | AS1.22

A Cold Frontal Life Cycle Climatology and Front-Cyclone Relationships over the North Atlantic and Europe during Winter 

Tobias Lichtenegger, Armin Schaffer, Douglas Maraun, Albert Osso Castillon, and Heimo Truhetz

Atmospheric fronts and cyclones play an important role in day-to-day weather variability, especially in the mid-latitudes and during the winter season. Severe rainfall and windstorm events are often associated with the passage of a front or a cyclone. While there are many studies of individual fronts and climatologies based on objectively detected fronts, there is no comprehensive study considering the whole frontal life cycle over time. Therefore, a front and cyclone tracking algorithm, based on overlapping features at consecutive time steps, is used together with an improved front detection method to detect and track cold fronts and cyclones over the North Atlantic and Europe in the extended winter season (October - March) in the ERA5 reanalysis dataset. Several life cycle characteristics, e.g. the duration, velocity, frontogenesis and -lysis regions as well as dynamic and thermodynamic frontal parameters are defined to investigate the frontal life cycle and the conditions and processes in the frontal region. Fronts are linked to their parent cyclone to study relationships between frontal and cyclonic properties. The study confirms that fronts are mostly formed over the western and central North Atlantic and travelling along the main storm track into the European continent. During positive phases of the North Atlantic Oscillation, fronts are travelling faster and further and are associated with stronger precipitation and surface wind speeds over their whole life cycle. Stronger cyclones are related to stronger dynamics in the frontal region.

How to cite: Lichtenegger, T., Schaffer, A., Maraun, D., Osso Castillon, A., and Truhetz, H.: A Cold Frontal Life Cycle Climatology and Front-Cyclone Relationships over the North Atlantic and Europe during Winter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17127, https://doi.org/10.5194/egusphere-egu24-17127, 2024.

EGU24-18002 | ECS | Orals | AS1.22

Power outages in windstorms: the influence of rainfall preconditioning, wind direction and season 

Colin Manning, Sean Wilkinson, Hayley Fowler, Elizabeth Kendon, and Sarah Dunn

Windstorms are the main cause of large power outages in the UK. Faults to electricity distribution networks during windstorms are predominantly a result of windthrow, the uprooting or breakage of trees by winds that then fall on assets such as overhead lines. The impact of strong winds on windthrow is influenced by a several conditions: trees uproot more easily in saturated soils, they are more vulnerable to strong winds from unusual directions, and they are more susceptible to strong winds in the growing season when their leaves catch the wind. Despite this, risk assessments of impacts, such as power outages, during windstorms generally focus on wind intensity alone. Here, we quantify the influence of contributing variables of windthrow including antecedent rainfall, wind direction of the maximum wind gust, and the season a windstorm occurs in. We demonstrate that including them in a logistic regression model alongside wind speed can improve the predictive skill of the number of electricity faults during windstorms compared to a reference model that only includes wind speed. The analysis uses fault data from the National Fault and Interruption Scheme (NaFIRs) database during the period 2006-2018 in four regions in the UK: South Wales, Southwest England, East Midlands, and West Midlands. Meteorological data is provided by ERA5. Each variable is shown to modulate the impact of strong winds and improve predictive skill, though with some regional variability. The probability of a high fault numbers in a windstorm with winds exceeding 25 m/s can be doubled following high rainfall accumulations and five times higher when strong winds come from a direction that deviates more than 40 degrees south or west from the prevailing south-westerly direction. Furthermore, this probability is doubled in summer months compared to winter. These results can help improve impact forecasting during windstorms and highlight the importance of including these variables in historical and future risk assessments of assets vulnerable to windthrow. Ignoring such contributions may lead to misrepresentation of risk and potential maladaptation, particularly for electricity distribution networks that will undergo a huge transformation as we reduce our dependence on greenhouse gases in the future.

How to cite: Manning, C., Wilkinson, S., Fowler, H., Kendon, E., and Dunn, S.: Power outages in windstorms: the influence of rainfall preconditioning, wind direction and season, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18002, https://doi.org/10.5194/egusphere-egu24-18002, 2024.

EGU24-19896 | ECS | Posters on site | AS1.22

Climate change's influence on Cut-off Lows in the future 

Aditya N. Mishra, Douglas Maraun, Reinhard Schiemann, Kevin Hodges, and Giuseppe Zappa

Cut-off Lows (COLs) are mid-latitude storms that are detached from the main westerly flow. They tend to propagate slower than other mid-latitude storms and are often harbingers of heavy and persistent rainfall. COLs have long been subject to thorough studies that have examined the physical structure and climatology across both hemispheres, however, their assessment in models is relatively low. In fact, there is no study on future changes in COLs in models. In this study, we analyze the cut-off lows in the northern hemisphere in the historic and future time slices in the CMIP6 dataset to study the frequency, duration, and intensity of the cut-off lows alongside the changes in velocity. Results show that the COL season, which is currently mostly limited to summer, extends into spring over Europe, North America, and Asia. This rise in activity in spring is more pronounced for COLs that are long-lasting and also have higher intensity maxima, i.e., the most impactful ones. Moreover, COL propagation velocity for persistent systems is due to slow down over North America in the summer. Slow-moving COLs are known to cause heavy localized rainfall. Through this study, we fill the information gap on the first insights of projected future changes in COLs by using TRACK to detect and trace COLs in the SSP5-8.5 projections of the CMIP6 ensemble.

 

How to cite: Mishra, A. N., Maraun, D., Schiemann, R., Hodges, K., and Zappa, G.: Climate change's influence on Cut-off Lows in the future, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19896, https://doi.org/10.5194/egusphere-egu24-19896, 2024.

EGU24-20374 | ECS | Orals | AS1.22

How do winter-time extratropical cyclones change in the future over South Africa? 

Sandeep Chinta, Adam Schlosser, Xiang Gao, and Kevin Hodges

Extratropical cyclones (ETCs) in South Africa usually occur during the winter (June to August), specifically influencing the Western Cape, causing extreme rain and strong winds. We investigate future changes in these winter-time ETCs using the simulations from three CORDEX-CORE Africa models. Each of these models was driven by three Coupled Model Intercomparison Project phase 5 (CMIP5) General Circulation Models (GCMs), resulting in nine sets of simulations. The simulations are from 1970-2100, with scenarios starting from 2006. We identified the cyclone tracks using the Hodges tracking algorithm, which used 6-hourly relative vorticity data at 850 hPa level. We chose a 20-year historical period from 1986 to 2005 for comparison with a future period of the same length from 2080 to 2099, focusing on the Representative Concentration Pathway (RCP) 8.5 scenario for the future projections. We observed a projected decrease in the number of ETCs in the future. The average track distance and duration are also projected to reduce. These reductions are statistically significant. We explored the future changes in the ETC-associated rainfall, which is also projected to be reduced in the future. We are currently looking at extending our analysis with the high-resolution 4 km gridded Climate Predictions for Africa (CP4A) data and see how our earlier results compare with the high-resolution data.

How to cite: Chinta, S., Schlosser, A., Gao, X., and Hodges, K.: How do winter-time extratropical cyclones change in the future over South Africa?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20374, https://doi.org/10.5194/egusphere-egu24-20374, 2024.

EGU24-327 | ECS | Orals | G3.1

Using Inverse GNSS Methods for the Determination of C20 and C30 Gravity Field Coefficients for the Support of GRACE Solutions    

Adrian Nowak, Radosław Zajdel, Filip Gałdyn, and Krzysztof Sośnica

The distribution of atmospheric, hydrological, and oceanic mass loads on the lithosphere affects the deformation of the Earth's surface over time. Monitoring of the relative displacements of the dense global network of permanent Global Navigation Satellite System (GNSS) stations enables the direct measurement of these loads on a global scale. The application of inverse GNSS methods provides an independent tool to retrieve the time variable gravity (TVG) models of the Earth system and to support hydrogeodesy studies, including the monitoring of the water storage cycle or polar ice mass loss.

The goal of this study is to investigate the effectiveness of using inverse GNSS methods to provide independent C20 and C30 coefficients. These coefficients are essential for deriving highly accurate Gravity Recovery and Climate Experiment (GRACE)-based TVG models. In this study, surface mass variations of low-degree TVG coefficients are derived from the displacements of continuously tracking GNSS sites based on the 21 years (2000-2021) of the Center for Orbit Determination in Europe solutions of the 3rd data reprocessing campaign of the International GNSS Service in the framework of the preparation of the International Terrestrial Reference Frame 2020. The geometrical displacements of the GNSS stations calculated by inverse methods are compared with changes in the gravity field based on independent estimates obtained from the GRACE and GRACE Follow-On (GRACE-FO) satellite missions and the Satellite Laser Ranging (SLR).

As an alternative to the solutions provided by SLR, it is shown that the C20 and C30 coefficients can be derived based on GNSS station displacements. The challenge of the inverse GNSS approach is to properly choose the maximum degree of TVG expansion. Compared with the SLR-based solution, the most consistent GNSS estimate of the temporal gravity variation rate of the C20 coefficient (−1.73 ± 0.10 × 10−11/year) and annual variation (4.7 ± 0.6 × 10−11/43.9° ± 7.5°) was obtained by expansion of the spherical harmonics to degree and order of 8. The GNSS-based C30 series is superior to the SLR-based estimates before the launch of the Laser Relativity Satellite. From August 2016, when the C30 estimates are essential for correcting the GRACE solutions, the root mean square between GNSS and SLR solutions is 4.2 × 10−11. GNSS could potentially support GRACE/GRACE-FO solutions that face problems in deriving C20 and C30, which are fundamental to estimates of ice mass changes in the polar regions. Recovery of mass change in the Antarctic ice sheet from April 2002 to December 2020 based on the coefficients replaced by GNSS estimates results in a linear trend of −111 ± 3 Gt/year. In comparison, the trend for the SLR-based replacement from Technical Note 14 shows a trend of −114 ± 2 Gt/year.

How to cite: Nowak, A., Zajdel, R., Gałdyn, F., and Sośnica, K.: Using Inverse GNSS Methods for the Determination of C20 and C30 Gravity Field Coefficients for the Support of GRACE Solutions   , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-327, https://doi.org/10.5194/egusphere-egu24-327, 2024.

EGU24-385 | Posters on site | G3.1

Long-term gravity field changes from SLR data and the combination with GRACE  for improving low-degree coefficients 

Filip Gałdyn, Krzysztof Sośnica, and Radosław Zajdel

In recent two decades, monitoring of changes in the Earth’s gravity field has been carried out mainly by the Gravity Recovery And Climate Experiment (GRACE) and its successor GRACE Follow-On. However, before the GRACE era,  very little information is available on the temporal evolution of the Earth's gravity field prior to that date. Moreover, through these missions, we have many gaps between 2010 and 2019. Fortunately, GRACE and GRACE Follow-On are not the only missions that can be used to recover variations in the Earth's gravity field. For the recovery of the mass redistribution processes on a large scale, we may employ precise Satellite Laser Ranging (SLR) observations.

We propose a set of long-term, continuous solutions based on SLR data. In our solutions, we use observations from spherical geodetic satellites. The gravity field is expanded up to a degree and order 10 with a monthly resolution from 1/1995 to 10/2021. The main solution has been decomposed into solutions expanded to degree and order 4, 6, 8, and 10 and stacked, taking advantage of the stability of the low-degree expansion and the better resolution of the high-degree expansion. The results show the reduction of the correlations between obtained parameters, stabilization of the ice mass estimates in polar regions – in Greenland and Antarctica, and a reduction of the noise over oceans by a factor of four.

In the GRACE and GRACE Follow-On datasets, the replacement of the spherical harmonics C20 and C30 with SLR-derived data is necessitated by suboptimal quality resulting from thermal effects impacting satellites and accelerometer malfunctions. In both SLR and GRACE solutions, coefficients of the same order and parity exhibit strong correlations. Merely replacing two specific coefficients could introduce bias into the solution. Therefore, we propose a comprehensive approach, combining GRACE with SLR solutions up to a degree and order of 10x10. This strategy ensures a proper consideration of the sensitivity of each technique to gravity field coefficients. The combined solution exhibits reduced noise compared to standard GRACE COST-G solution and effectively address the distinct sensitivities of SLR and GRACE techniques to low-degree time-variable gravity field coefficients.

How to cite: Gałdyn, F., Sośnica, K., and Zajdel, R.: Long-term gravity field changes from SLR data and the combination with GRACE  for improving low-degree coefficients, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-385, https://doi.org/10.5194/egusphere-egu24-385, 2024.

EGU24-891 | ECS | Posters on site | G3.1

Vertical Land Motion Detection Using Satellite Altimetry Data at the Hadera Tide Gauge Station 

Milaa Murshan, Balaji Devaraju, Nagarajan Balasubramanian, and Onkar Dikshit

Vertical Land Motion (VLM) estimation involves various methods such as Global Navigation Satellite Systems (GNSS), Very Long Baseline Interferometry (VLBI), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and Satellite Laser Ranging (SLR). However, satellite altimetry presents an alternative approach for estimating VLM independently. This study compares altimetry-based VLM estimates with those obtained from Tide Gauge (TG) devices. The VLM is determined by calculating the difference between the linear trends of sea-level time series derived from altimetry-based data Instantaneous Sea Surface Height (ISSH) and TG data. Additionally, VLM can be estimated by comparing the linear trends of altimetry-based Sea Level Anomalies (SLA) and TG SLA time series.
 To estimate VLM, absolute ISSH measurements from satellite altimetry, unaffected by the Earth's crust, are contrasted with relative sea level measurements recorded by TG stations with respect to a fixed land point. By differentiating and aligning temporal pairs of TG and altimetry data, only the linear trend remains, representing the vertical displacement of the TG station relative to the reference surface. Removing satellite altimetry instrumentation drifts enables the extraction of VLM from the difference in linear trends. 
The VLM estimate obtained for the Hadera TG station, covering 1992-2016, shows a positive trend of 0.24 ± 0.07 mm/year. This finding aligns with GNSS-based VLM estimations at the same station, indicating land uplifting in the region. Consequently, the study suggests that there is no immediate concern about the rise of sea level. These findings enhance our understanding of regional geodetic processes and their implications for assessing sea level changes. By providing valuable information on VLM estimation, this research contributes to our knowledge of vertical displacement on land and its significance for future studies.

How to cite: Murshan, M., Devaraju, B., Balasubramanian, N., and Dikshit, O.: Vertical Land Motion Detection Using Satellite Altimetry Data at the Hadera Tide Gauge Station, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-891, https://doi.org/10.5194/egusphere-egu24-891, 2024.

EGU24-3658 | ECS | Orals | G3.1

A Geodetic Drought Index Driven by Hydrologic Loading Estimates Calculated from Three-Dimensional GPS Displacements   

Zachary M. Young, Hilary R. Martens, Zachary H. Hoylman, and W. Payton Gardner

During periods of drought, quantifying the intensity of water loss within hydrologic reservoirs, both on and below the surface, is critical to sustain water resources. Drought intensity is typically characterized using drought indices which are driven by meteorologic observations, such as precipitation. These drought indices provide good insight into the quantity of water entering the hydrologic system, however, they are unable to quantify the amount of water retained in a watershed or the amount lost due to runoff and evapotranspiration. We address this by leveraging the sensitivity of three-dimensional Global Positioning System displacements to local and regional hydrologic-storage fluctuations, and produce a new geodetic drought index (GDI), derived from estimated hydrologic-storage deviations, to directly characterize hydrologic storage anomalies. The GDI is derived comparably to the Standardized Precipitation Evapotranspiration Index such that it may be easily incorporated into current drought management workflows. We directly compare the GDI to hydrologic observations within California and find strong associations between specific time scales of the GDI and groundwater well, artificial-reservoir storage, and stream discharge observations. The GDI is most sensitive to groundwater, exhibiting a correlation coefficient of 0.87 at the 3-month time scale. Both artificial-reservoir storage and stream discharge exhibit peak correlation coefficients when considering the 1-month GDI, at 0.81 and 0.47 respectively. No relationship is observed with soil moisture observations. The correlation coefficients decline rapidly away from the optimal time scale, indicating the 1- and 3-month GDI are strong predictors of hydrologic variation within California. In addition to capturing long-term trends, rapid changes in the GDI initiate during clusters of large atmospheric-river events that closely mirror fluctuations in the hydrologic observations. The GDI provides an opportunity to improve hydrologic models for drought-management and to advance our understanding of the water cycle.

 

How to cite: Young, Z. M., Martens, H. R., Hoylman, Z. H., and Gardner, W. P.: A Geodetic Drought Index Driven by Hydrologic Loading Estimates Calculated from Three-Dimensional GPS Displacements  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3658, https://doi.org/10.5194/egusphere-egu24-3658, 2024.

EGU24-5267 | ECS | Posters on site | G3.1

Reconciling ocean mass changes from 20 years of GRACE and GRACE Follow On observations 

Carsten Bjerre Ludwigsen, Ole Baltazar Andersen, Christopher Watson, and Matt King

The total mass change of the Earth's land surface precisely offsets the combined changes in the atmosphere and oceans, resulting in a net-zero change for the entire system (land+ocean+atmosphere).

Closing the ocean mass budget is crucial for understanding current and future sea-level changes. Recent efforts to reconcile ocean mass observations from GRACE and GRACE-Follow On satellites (hereafter unitedly referred to as ‘GRACE’) with both steric-corrected altimetry and and land/ice to ocean estimates have revealed a discrepancy in the mass budget (Wang et al, 2022; Barnoud et al, 2022). This finding indicates a concerning misalignment in our global observation system or understanding of earth mass transport.

This study uses GRACE-independent estimates/models of land surface mass changes to validate 20 years of GRACE observations. By calculating the monthly Gravitational, Rotational, and Deformational (GRD) response to 20 years of land mass changes, we reconstruct the global, regional, and seasonal ocean mass changes observed by GRACE from 2003 to 2022.

Over the 20-year period, the ocean mass reconstruction aligns well with the GRACE observations. However, a significant deviation emerges after 2020, with the reconstruction showing a larger ocean mass change than GRACE. We demonstrate that this deviation is likely caused by an underestimation of Western Africa precipitation in the ERA5 reanalysis, commonly used by hydrological models to estimate changes in land water storage. Land mass observations from GRACE further confirmvthis underestimation and shows great alignment between models and observations when excluding sub-Saharan Africa.

Our results show a global agreement between GRACE and GRD-induced ocean mass changes, suggesting that the misalignment between GRACE and steric-corrected altimetry is likely due to errors in the ARGO observing system. A reported 'salinity-drift' is the primary source of error, and together with an error in the wet path delay originating from drift in the radiometer of the Jason-3 satellite explains most of the post-2016 difference between GRACE and steric-corrected altimetry is identified. The remaining differences likely originate from GIA and/or Argo-biases.

How to cite: Ludwigsen, C. B., Andersen, O. B., Watson, C., and King, M.: Reconciling ocean mass changes from 20 years of GRACE and GRACE Follow On observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5267, https://doi.org/10.5194/egusphere-egu24-5267, 2024.

The accuracy of global ocean tide models (OTMs) in shallow waters and along coasts impacts on their numerous applications. For example, the use of OTMs to provide tide corrections (‘de-tiding’) for satellite altimetry observations is required for, e.g., sea level studies and marine gravity field recovery. OTMs are also indispensable in the mitigation of striping errors in GRACE and GRACE-FO time-variable gravity field solutions. It therefore follows that OTM errors in coastal and shelf ocean may then introduce biases into the ‘corrected’ satellite altimetry and gravimetry observations with the potential to impact models using these data. The purpose of our study is to assess the accuracy of two high resolution assimilated OTMs (TPXO9v5, and FES2014b) using an updated set of >100 coastal and shelf tide gauges across the northern Australia and Papua New Guinea region. TPXO9v5 and FES2014b are used here because they have previously compared better than other tidal models in adjacent coastal and shelf areas. This study will also provide insight into the tides in this region which contain a mix of shallow and medium depth waters adjacent to the coast, in addition to land and island barriers that result in a complex tidal regime. This study takes advantage of the large number of short-term tide gauges situated on the coast or offshore islands in Northern Australia and Papua New Guinea. This set of tide gauges have observation periods of >30 days, with a number being more than 90 days long which allows the resolution of the major semidiurnal and diurnal tidal constituents. We use harmonic analysis to estimate tidal constants of major diurnal and semi-diurnal constituents from tide gauges then compare them with corresponding values from TPXO9v5 and FES2014b at the tide gauge location. This comparison identifies improvements and also limitations in these OTMs in this region, and their potential impact on tide corrections provided for satellite altimetry products that may propagate into coastal sea surface, and gravity at the coast. The results also provide additional insight into the local tidal patterns in this region, with particular interest in the Torres Strait and surrounding area.

How to cite: Filmer, M., Seifi, F., and Claessens, S.: Evaluation of ocean tide models in coastal ocean regions of northern Australia and Papua New Guinea using an updated set of short term tide gauges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7127, https://doi.org/10.5194/egusphere-egu24-7127, 2024.

EGU24-7430 | ECS | Posters on site | G3.1

Regional modelling of water storage variations from combined GRACE/-FO and GNSS data in a Kalman filter framework 

Viviana Wöhnke, Annette Eicker, Matthias Weigelt, Marvin Reich, and Andreas Güntner

Water mass changes at and below the surface of the Earth cause changes in the Earth’s gravity field which can be observed by at least three geodetic observation techniques: ground-based point measurements using terrestrial gravimeters, space-borne gravimetric satellite missions (GRACE and GRACE-FO) and geometrical deformations of the Earth’s crust observed by GNSS. Combining these techniques promises the opportunity to compute the most accurate (regional) water mass change time series with the highest possible spatial and temporal resolution, which is the goal of a joint project with the interdisciplinary DFG Collaborative Research Centre (SFB 1464) "TerraQ – Relativistic and Quantum-based Geodesy".

A method well suited for data combination of time-variable quantities is the Kalman filter algorithm, which sequentially updates water storage changes by combining a prediction step with observations from the next time step. As opposed to the standard way of describing gravity field variations by global spherical harmonics, we introduce space-localizing radial basis functions as a more suitable parameterisation of high-resolution regional water storage change. An estimation environment has been set up for the combination of GRACE/-FO satellite gravimetry with GNSS station displacements. The feasibility and stability of the approach is first demonstrated in a closed-loop simulation to test the setup and tune the algorithm. Subsequently, it is applied to real GRACE and GNSS observations to sequentially update the parameters of a regional gravity field model for Central Europe. The implementation was designed to flexibly include further observation techniques (e.g. terrestrial gravimetry) at a later stage. This presentation will outline the Kalman filter framework and regional parameterisation approach, and addresses challenges such as the relative weighting between the GRACE and GNSS data, and the appropriate choice of the Kalman filter process model and radial basis function parameterisation.

How to cite: Wöhnke, V., Eicker, A., Weigelt, M., Reich, M., and Güntner, A.: Regional modelling of water storage variations from combined GRACE/-FO and GNSS data in a Kalman filter framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7430, https://doi.org/10.5194/egusphere-egu24-7430, 2024.

EGU24-7669 | ECS | Orals | G3.1

Evaluation of extreme events in global coupled climate models by satellite gravimetry 

Klara Middendorf, Annette Eicker, Laura Jensen, and Henryk Dobslaw

Under the assumption that a warming climate leads to an intensification of the global water cycle, it can be hypothesized that also the occurrence frequency and severity of extreme events such as droughts or floods will increase in the upcoming decades to centuries. Global coupled climate models, which project the future evolution of various variables of the Earth's climate system are important tools for the analysis of such expected changes. To assess the reliability of the models and to identify possible systematic discrepancies, it is essential to evaluate the model output against observations.

In this study, present and future occurrences of extreme events are analysed in water storage time series simulated by coupled global climate models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) and compared against spatio-temporal changes in water mass derived from GRACE and GRACE-FO. This comparison is based on Extreme Value Theory, as the exact timing of modelled extreme events cannot be assessed by observations due to the stochastic behavior of climate variability in unconstrained model experiments. From estimated extreme value distributions return levels are calculated, a quantity describing the magnitude or frequency of extreme values.  Challenges that have to be overcome in the analysis are the non-stationary data and the relatively short time span of the GRACE observations. The latter issue is addressed by additionally assessing GRACE-based water storage reconstructions available over many decades.

This study provides insights into the ability of global climate models to model the occurrence of TWS extremes, namely unusual dry and wet phases. It also examines whether the climate model projections predict an increasing intensity of extreme events.

How to cite: Middendorf, K., Eicker, A., Jensen, L., and Dobslaw, H.: Evaluation of extreme events in global coupled climate models by satellite gravimetry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7669, https://doi.org/10.5194/egusphere-egu24-7669, 2024.

Changes in soil water storage can be studied on a global scale using a variety of satellite observations. With active or passive microwave remote sensing, we can study the upper few centimeters of the soil, while satellite gravimetry allows us to detect changes in the entire column of terrestrial water storage (TWS). The combination of both types of data can provide valuable insight into hydrological dynamics in different soil depths towards a better understanding of changes in subsurface water storage.

We use daily Gravity Recovery and Climate Experiment (GRACE) data and satellite soil moisture data to identify extreme hydroclimatic events, focusing on prolonged droughts. To enhance our comprehension of the subsurface, we utilize not just surface soil moisture data but also integrate information on root zone soil moisture. Original level-3 surface soil moisture data sets of SMAP and SMOS are compared to post-processed level-4 data products (both surface and root zone soil moisture) and a multi-satellite product provided by the ESA CCI.

We analyse the correspondence between high and low percentiles in TWS and soil moisture time series, which allows us to identify extreme events in different integration depths and storage compartments. Furthermore, we compute the rate of change of anomalies to assess how quickly the system accumulates storage deficits during drought conditions and recovers from them for different soil depths. Our investigation focuses on the temporal dynamics of near-surface soil moisture and TWS, highlighting the cascading effects that propagate from the surface into the subsurface. The results we obtained indicate characteristic patterns of the temporal dynamics of drought recovery in varying soil depths. Specifically, our analysis shows that surface soil moisture recovers faster than TWS, and that this recovery process slows down as soil integration depth increases.

How to cite: Blank, D., Eicker, A., and Güntner, A.: From surface to subsurface: Investigating drought cascades and recovery patterns with (daily) satellite observations of soil moisture and terrestrial water storage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7888, https://doi.org/10.5194/egusphere-egu24-7888, 2024.

EGU24-8727 | Posters on site | G3.1

20-year-long sea level changes along the world’s coastlines from satellite altimetry: a new data set of coastal virtual stations 

Anny Cazenave, Lancelot Leclercq, Fabien Leger, Florence Birol, Fernando Nino, Marcello Passaro, and Jean Francois Legeais

In the context of the ESA Climate Change Initiative (CCI) Coastal Sea Level project, a complete reprocessing (including retracking of the radar waveforms) of high resolution (20 Hz, i.e. 350 m) along-track altimetry data of the Jason-1, Jason-2 and Jason-3 missions since January 2002 was performed along the world coastal zones. Different versions have been provided so far. The latest release (SL_cci+ coastal altimeter sea level dataset, v2.3) is now available to users. It is an extension in time of the previous data set (v2.2) which covers the period January 2002 to June 2021. A new improved processing for the waveform retracking and computation of the coastal sea level anomalies was developed and a new editing procedure for the coastal sea level trend computation was implemented. This new data set shows spectacular reduction of the data noise compared to previous versions, both in terms of sea level anomaly time series and trends. As a consequence, compared to the previous versions we now obtain an important increase of the number of virtual coastal stations (i.e., the location of the first valid point along the satellite track, with about 1200 sites at an average distance from the coast of about 3 km, including more than 200 stations at less than 2 km from the coast). The coastal sea level anomalies and trends of the altimetry-based virtual stations have been validated with tide gauge data where possible. An example in the Mississippi Delta is presented.

How to cite: Cazenave, A., Leclercq, L., Leger, F., Birol, F., Nino, F., Passaro, M., and Legeais, J. F.: 20-year-long sea level changes along the world’s coastlines from satellite altimetry: a new data set of coastal virtual stations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8727, https://doi.org/10.5194/egusphere-egu24-8727, 2024.

EGU24-8830 | Orals | G3.1 | Highlight

Will the MAGIC mission improve the observability of extreme hydrological events? 

Eva Boergens, Josefine Wilms, Markus Hauk, Christoph Dahle, Henryk Dobslaw, and Frank Flechtner

NASA and DLR will launch in 2028 GRACE-C (Gravity Recovery and Climate Experiment – Continuation). This mission will again be launched into a polar orbit at 500 km initial altitude and extend the observation of the time-variable Earth’s gravity field from GRACE (2002-2017) and GRACE-FO (GRACE Follow-On, 2018-today). ESA plans to launch a Next Generation Gravity Mission (NGGM) in 2032, which shall fly in a lower and inclined orbit and be based on improved instrumentation. GRACE-C and NGGM will then form the double-pair Mass-Change and Geosciences International Constellation (MAGIC) to significantly increase the spatial and temporal resolution of mass transport products and deduce water mass redistribution over the oceans, ice sheets and continents.

Thanks to the 20+ years period of GRACE and GRACE-FO observations, scientists are able to analyse extreme hydrological events, such as flooding and droughts. However, due to the rather coarse spatial resolution of the GRACE and GRACE-FO data sets of approximately 350 km, finer spatial details of such extreme events are kept hidden. Further, spatial leakage limits the value of these data for smaller-scale regional investigations.

In this contribution, we will employ five years of simulated data for both a single polar pair (GRACE-FO-like) and a MAGIC baseline scenario. Thanks to the simulation, we can also assess the true values of the hydrological input models. Both simulated data sets are filtered with the same DDK filters for comparison. The filter strength can be reduced for the MAGIC baseline scenario without introducing more striping errors.

With these simulated data sets, we investigate extreme hydrological events. For example, the localisation of extreme wet events along the northern coast of Australia is much improved, with less signal leakage into the surrounding ocean.

How to cite: Boergens, E., Wilms, J., Hauk, M., Dahle, C., Dobslaw, H., and Flechtner, F.: Will the MAGIC mission improve the observability of extreme hydrological events?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8830, https://doi.org/10.5194/egusphere-egu24-8830, 2024.

EGU24-8938 | Orals | G3.1

Strategies for assimilating GRACE/-FO terrestrial water storage anomalies into hydrological models 

Anne Springer, Yorck Ewerdwalbesloh, Helena Gerdener, Kerstin Schulze, and Jürgen Kusche

After more than 15 years of experience with GRACE/-FO data assimilation (DA) into hydrological models, numerous studies have conducted various tests on GRACE product and preprocessing options as well as DA strategies. However, a commonly accepted standard procedure has yet to emerge. This contribution comprises (1) a review on the prevalence of GRACE-DA options based on existing studies together with (2) insights from applying two GRACE assimilating frameworks: the high-resolution CLM-DA framework over Europe and the global WGHM-based calibration and data assimilation framework.

We discuss the selection of different GRACE/-FO products for DA into hydrological models, including spherical harmonics, MASCONS, level 3 products, and the recently evolved along-orbit line-of-sight gravity differences. Additionally, we explore processing choices such as filtering and rescaling, possible corrections for phenomena like glacial isostatic adjustment, large lakes and reservoirs or earthquakes, observation grid representation, and various approaches to handle observation errors. We evaluate the impact of these processing strategies on simulated water storage trends and the representation of selected extreme events.

Through this research, we contribute to understanding optimal strategies in assimilating GRACE/-FO data, addressing critical aspects influencing hydrological model reliability.

How to cite: Springer, A., Ewerdwalbesloh, Y., Gerdener, H., Schulze, K., and Kusche, J.: Strategies for assimilating GRACE/-FO terrestrial water storage anomalies into hydrological models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8938, https://doi.org/10.5194/egusphere-egu24-8938, 2024.

EGU24-10138 | ECS | Posters on site | G3.1

Reconstructing GRACE-like TWSA maps from 1992 on by combining data-driven methods with time-variable gravity fields from SLR range analyses 

Charlotte Hacker, Jürgen Kusche, Anno Löcher, and Fupeng Li

The Gravity Recovery And Climate Experiment (GRACE) and its follow-on mission, GRACE-FO, have observed global mass changes and transports, expressed as total water storage anomalies (TWSA), for over two decades. However, for climate change attribution and other applications, multi-decadal TWSA time series are required. This need has triggered several studies on reconstructing TWSA via regression approaches or machine learning techniques, with the help of predictor variables such as rainfall or sea surface temperature. Here, we combine such an approach, for the first time, with low-resolution information from geodetic satellite laser ranging (SLR). The reconstruction is formulated on a GRACE-derived empirical orthogonal functions (EOFs) basis and complemented with the Löcher and Kusche (2021) approach, in which global gravity fields are solved from SLR ranges in a GRACE EOF basis for the pre-GRACE time frame. Although our technique works globally, we focus mainly on European basins and reconstruct water storage anomalies from 1992 onward.

How to cite: Hacker, C., Kusche, J., Löcher, A., and Li, F.: Reconstructing GRACE-like TWSA maps from 1992 on by combining data-driven methods with time-variable gravity fields from SLR range analyses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10138, https://doi.org/10.5194/egusphere-egu24-10138, 2024.

EGU24-10234 | ECS | Posters on site | G3.1

Sub-Monthly Mass Change Signal in Greenland from GRACE-FO Laser Interferometry Data 

Barbara Jenny, Marcus Jepsen, Sebastian Bjerregaard Simonsen, René Forsberg, and Tim Enzlberger Jensen

GRACE and GRACE-FO have proven valuable for monitoring the health of ice sheets by showing seasonal mass changes along with the decadal trends of mass loss. Two years stand out in the Greenland ice sheet mass loss record with record melt: 2012 and 2019. On the West coast of Greenland, the ice mass fluctuations act on remarkably short time scales during these events, as evident at Ilulissat isbræ, which nearly doubled its ice speed in just one week. Here, we study if these sub-monthly ice mass change variations can be measured using GRACE-FO line-of-sight measurements.

It has been shown several times that using dynamic orbits and Laser Ranging Interferometer (LRI) data, one can calculate residual Line-of-sight gravity signals. This method was primarily used to study hydrological signals such as storm surges or heavy rainfall. In this study, we focus on ice mass changes in Greenland, and we compare these GRACE-FO measurements to the expectation based on the monthly gravity field and the signal from mass change based on IceSat2 data for 2019-2021.

How to cite: Jenny, B., Jepsen, M., Simonsen, S. B., Forsberg, R., and Jensen, T. E.: Sub-Monthly Mass Change Signal in Greenland from GRACE-FO Laser Interferometry Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10234, https://doi.org/10.5194/egusphere-egu24-10234, 2024.

EGU24-10483 | ECS | Orals | G3.1

Resolving the interannual to multi-decadal variability in ocean heat content, a simulation study of current and future satellite gravity missions 

Marius Schlaak, Roland Pail, Alejandro Blazquez, Benoit Meyssignac, and Jean-Michel Lemoine

Ocean Heat Content (OHC) is an essential indicator of Earth’s climate state. Climate change is driven by the disequilibrium of Earth’s radiation budget. This abundant energy in the system is the Earth Energy Imbalance (EEI), which is challenging to measure globally. About 90% of EEI is accumulated in the oceans, resulting in an increase in ocean heat content. Therefore, OHC is a suitable proxy for EEI and can be measured globally using a combination of geodetic satellite techniques. By combining satellite altimetry and satellite gravimetry, it is possible to measure the change in global ocean heat content over the mission’s lifetime. While the altimeter record covers several decades, satellite gravity missions have been observing global mass transports for two decades. To steadily estimate the system’s long-term behavior, an extended observation period of the satellite systems is needed. The upcoming satellite gravity mission Grace-C, planned to be launched in 2028 by NASA, is meant to ensure continuity and extension of the data record. At the beginning of the 2030s, an additional inclined pair will be launched by ESA to form together with GRACE-C the Mass change And Geosciences International Constellation (MAGIC), for which higher spatial and temporal resolutions are expected.

This contribution presents the results of multi-decadal closed-loop simulations of current and future satellite gravity observations. It shows the benefit of an increased duration of the observation and an improved observational system while comparing processing strategies for long-term trends in ocean mass changes. The observed climate signal is based on projections of mass change signals of oceans, ice sheets, and glaciers derived from CMIP6 climate projection under a shared socio-economic pathway scenario without drastic reduction of Greenhouse gases emissions (SSP5-8.5). A particular focus here is on the accuracy of long-term ocean trends. The direct estimation of long-term trends benefits from an increasing observation period and allows improved spatial resolution compared to trends estimated from monthly temporal gravity fields. The global ocean heat content is estimated from the steric sea-level change which is derived by subtracting the observed ocean mass change from the overall sea level change. The resulting long-term trends in ocean heat content are then compared to initial inputs to the simulation to illustrate the difference in performance between current and future satellite gravity constellations.

How to cite: Schlaak, M., Pail, R., Blazquez, A., Meyssignac, B., and Lemoine, J.-M.: Resolving the interannual to multi-decadal variability in ocean heat content, a simulation study of current and future satellite gravity missions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10483, https://doi.org/10.5194/egusphere-egu24-10483, 2024.

EGU24-10526 | Orals | G3.1

Assessment of global high-resolution water storage simulations from the LISFLOOD hydrological model 

Henryk Dobslaw, Laura Jensen, Robert Dill, and Kyriakos Balidakis

Simulated terrestrial water storage (TWS) data from global hydrological models are indispensable for various geodetic applications, e.g., for simulating Earth orientation parameters, deriving time series of deformations of the Earth’s surface needed for the realization of global reference systems, or de-aliasing purposes of GRACE/-FO gravity products. So far, the Land Surface Discharge Model (LSDM) has been routinely used for such tasks at the GFZ. However, the current standard experiment of LSDM is already several years old, and many limitations are known, in particular a limited spatial resolution of 0.5°, which limits the accuracy of crustal deformation predictions close to rivers and lakes. In this contribution, we evaluate the suitability of LISFLOOD (https://ec-jrc.github.io/lisflood/), an open source, high-resolution hydrological rainfall-runoff-routing model, for geodetic purposes.

We compare the performance of various global LISFLOOD model runs for the time period 2000 – 2022 against the current LSDM configuration. In addition to two LISFLOOD model generations, which differ in their spatial resolution (0.1° and 0.05°) and their input land surface parameter data set, we also explore a number of high-resolution (0.05°) model runs with respect to the influence of the soil depth on simulated TWS. Model results are validated against mass anomalies from the satellite gravimetry missions GRACE and GRACE-FO on different spatial and temporal scales. Furthermore, to demonstrate the benefit of the higher spatial resolution of LISFLOOD, we utilize data from selected ground based GNSS stations to validate the models’ performance regarding mass-induced loading.

We find that LISFLOOD significantly outperforms LSDM in many regions, especially on interannual time scales, in terms of various validation metrics (i.e., correlation, root mean squared deviation, and explained variance). Analyzing the different LISFLOOD runs reveals advantages of the new (0.05°) over the old (0.1°) model version, and a large impact of the choice of soil depth on simulated TWS.

How to cite: Dobslaw, H., Jensen, L., Dill, R., and Balidakis, K.: Assessment of global high-resolution water storage simulations from the LISFLOOD hydrological model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10526, https://doi.org/10.5194/egusphere-egu24-10526, 2024.

EGU24-11213 | Posters on site | G3.1

GNSS Precipitable Water Vapour for Climate Monitoring 

Galina Dick, Florian Zus, Jens Wickert, Benjamin Männel, and Markus Ramatschi

Aside from main geodetic applications, the Global Navigation Satellite System (GNSS) is now an established observing system for atmospheric water vapour which is the most important greenhouse gas as it is responsible for around 60% of the natural greenhouse effect. Water vapour is under-sampled in the current climate-observing systems. Obtaining and exploiting more high-quality humidity observations is essential for climate research.

Established in 2006, the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN), is an international reference observing network of sites measuring essential climate variables above the Earth's surface. Currently, this network comprises more than 30 reference sites worldwide, designed to detect long-term trends of key climate variables such as temperature and humidity in the upper atmosphere. GRUAN observations are required to be of reference quality, with known biases removed and with an associated uncertainty value, based on thorough characterization of all sources of measurement.

A complementary small scale regional climate station network is the Austrian WegenerNet, which provides since 2007 measurements of hydrometeorological variables with very high spatial and temporal resolution. GNSS precipitable water vapour (GNSS-PWV) measurement has been included as a priority one measurement of the essential climate variable water vapour to both GRUAN and WegenerNet climate station networks.

GFZ contributes to climate research within GRUAN and WegenerNet with its expertise in processing of ground-based GNSS network data to generate precise PWV products. GFZ is responsible for the installation of GNSS hardware, data transfer, processing and archiving, derivation of GNSS-PWV data products according to GRUAN and WegenerNet requirements including PWV uncertainty estimation. GNSS-PWV products and results of selected validation studies will be presented.

How to cite: Dick, G., Zus, F., Wickert, J., Männel, B., and Ramatschi, M.: GNSS Precipitable Water Vapour for Climate Monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11213, https://doi.org/10.5194/egusphere-egu24-11213, 2024.

EGU24-11433 | ECS | Posters on site | G3.1

Solid Earth’s response to climate change in Svalbard monitored by space geodesy  

Alicia Tafflet, Joelle Nicolas, Jean-Paul Boy, Jean-Michel Lemoine, Félix Perosanz, Frédéric Durand, Achraf Koulali, Lissa Gourillon, Agnès Baltzer, and Jérôme Verdun

The Svalbard archipelago in the Arctic is extremely sensitive to climate change. The resulting redistribution of mass, including recent and past ice melt, induces deformations of the Earth's surface and temporal variations in its gravity field, which can be detected by space geodesy. The cross-comparison of different techniques takes advantage of their complementary temporal and spatial resolutions, helping to distinguish between local, regional and global signals. We analyse more than 20 years of GNSS (Global Navigation Satellite System) satellite 3D positionning solutions at 17 permanent sites. The results are compared with deformations computed from time gravity field variations observed by the space gravimetry missions GRACE (Gravity Recovery and Climate Experiment) and GRACE Follow-On. The mean vertical motion is of about 9 mm/year and can reach 15 mm/year. We then compare these GNSS and GRACE datasets with Little Ice Age (LIA) and Global Isostatic Adjustment (GIA) models as well as with satellite altimetry observations from Cryosat-2 and IceSat-2. We infer the various contributions and quantify the impact of the current climate change on Svalbard. In addition to better estimate the acceleration of the current ice melting we apply an innovative seasonal adjustment method. The results are then discussed in relation to in situ observations.

How to cite: Tafflet, A., Nicolas, J., Boy, J.-P., Lemoine, J.-M., Perosanz, F., Durand, F., Koulali, A., Gourillon, L., Baltzer, A., and Verdun, J.: Solid Earth’s response to climate change in Svalbard monitored by space geodesy , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11433, https://doi.org/10.5194/egusphere-egu24-11433, 2024.

Since March 2002, the Gravity Recovery and Climate Experiment (GRACE) satellite and its following mission GRACE-FO have measured the time-variable gravity fields of the Earth, by which water shifts around Earth can be captured. Among its innovations, GRACE has monitored the change of ice mass from Earth's ice sheets and glaciers, which is essential for the better understanding of the changing climate system. Over the past few decades, glacier mass loss has been significant across the globe. The European Alps are among the regions experiencing the greatest shrinkage of glaciers, which becomes the main focus of this work.
In this work, we will challenge the information of satellite gravimetry, hydrological models, and satellite geodesy to monitor the ice mass loss in the Alps in central Europe. The temporal variations of total water storage (TWS) in the Alpine region are determined from GRACE- and GRACE-FO-based Level-2 products provided by COST-G and Mascon surface mass change fields calculated by JPL. Furthermore, the correction of GIA effects and hydrological signals in the study area is indispensable to isolate the estimate of glacier melting. For the GIA correction, the GIA model ICE-6G_D and the regional dataset of surface displacements obtained from geodetic observation techniques are applied to GRACE data respectively, resulting in obvious different results. For the hydrological correction, the WaterGAP Global Hydrology Model (WGHM) model and the Global Land Data Assimilation System (GLDAS) model are used to estimate the mass change of the liquid part. In addition, the ice mass loss in the Alps between 2000 and 2014 based on glacier inventory was estimated in another publication, which can be a reference (-1.34 Gt/yr). Glaciers in the Alps lost mass at a rate of around -1.4 Gt/yr and around -2.2 Gt/yr depending on different ways of GIA correction during the 21-year period, which have similar magnitudes with the reference value.

How to cite: Liu, S. and Pail, R.: The estimation of glacier changes in the Alps in 2002-2022 with the use of satellite gravimetry data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11913, https://doi.org/10.5194/egusphere-egu24-11913, 2024.

EGU24-11918 | ECS | Posters on site | G3.1

Estimating terrestrial water storage trends by developing a joint inversion scheme using GRACE and GRACE-FO data 

Sedigheh Karimi, Amin Shakya, Roelof Rietbroek, Marloes Penning de Vries, and Christiaan van der Tol

Climate change and global warming can affect the water cycle, leading to increased hydrological extremes, such as droughts affecting the environment, agricultural activities, and human life and causing serious social and economic problems worldwide. Therefore, monitoring changes in the water cycle can be helpful for effective water resources management and provide a management plan for sharing with stakeholders, water managers, and local people.

This study focuses on terrestrial water storage changes (e.g., trends and seasonal shifts) that potentially indicate climate change patterns like droughts and large scale flooding events within watersheds across the Horn of Africa.

In this study, an inversion scheme is being developed to process level-2 data obtained from the Gravity Recovery and Climate Experiment (GRACE) and subsequent measurements from GRACE Follow-On (GRACE-FO) spanning the period from 2002 to 2023 considering the variance-covariance matrix (error matrix) of observations for estimating TWS variations monthly at basin scale. We expect that our inversion scheme will be independent of filters, and there will be no need for empirical rescaling factors to amplify the primary signal after filtering and damping effect. The TWS changes estimated from the developed inversion scheme will be compared with the TWS trends of basins that have been derived using the basin averaging standard approach and Mascon solutions TWS changes products. Additionally, the atmospheric reanalysis products will be used, along with hydrological model discharge estimates, to assess the accuracy of time derivatives of TWS changes.

How to cite: Karimi, S., Shakya, A., Rietbroek, R., Penning de Vries, M., and van der Tol, C.: Estimating terrestrial water storage trends by developing a joint inversion scheme using GRACE and GRACE-FO data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11918, https://doi.org/10.5194/egusphere-egu24-11918, 2024.

EGU24-11963 | ECS | Orals | G3.1

Combination of GRACE/GRACE-FO and CryoSat-2 data resolves Glacial Isostatic Adjustment spatially and temporally in the Amundsen Sea Embayment, West Antarctica 

Matthias O. Willen, Bert Wouters, Taco Broerse, Eric Buchta, and Veit Helm

An effective spatial resolution of a few hundred kilometres, typically assessed for mass variations derived from GRACE/GRACE-FO data, is a major limitation for the rigorous investigation of local causes of mass variations. This is crucial for analyzing mass changes of the West Antarctic Ice Sheet, which is one of the tipping elements in the Earth’s climate system. In this region, ice mass changes occur on spatial scales smaller than the typical GRACE/GRACE-FO resolution. Furthermore, this is also the case for the solid-Earth deformation induced by ice load changes, which in turn can affect the glacier flow. Especially in the Amundsen Sea Embayment, mass changes due to the ongoing Glacial Isostatic Adjustment (GIA) have been postulated to vary on spatial scales smaller than 200 km and to feed back significantly on ice flow dynamics. Here, we present results from a data combination approach with a focus on the Amundsen Sea Embayment, West Antarctica. This approach utilizes data from GRACE/GRACE-FO and CryoSat-2 satellite altimetry with regional climate and firn model results over a time span of 10 years from 2011 to 2020. Improved GRACE/GRACE-FO gravity-field processing and a study area in a high latitude region, where the signal-to-noise is high, benefit a high spatial resolution of the results. One processing step is the smoothing of the input data sets in order to unify their different spatial resolution. We find a best fit of the combination results with independent GNSS observations by applying a Gaussian smoother of 135 km half-response width. The weighted rms difference is 3.8 mm/a in terms of estimated bedrock motion. It is almost twice as large when the input data sets are smoothed with a 300 km half-response filter. The determined effects of solid-Earth deformation may be a useful boundary information for GIA modelling in this region, e.g. for testing rheological models or (centennial) glacial histories.

How to cite: Willen, M. O., Wouters, B., Broerse, T., Buchta, E., and Helm, V.: Combination of GRACE/GRACE-FO and CryoSat-2 data resolves Glacial Isostatic Adjustment spatially and temporally in the Amundsen Sea Embayment, West Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11963, https://doi.org/10.5194/egusphere-egu24-11963, 2024.

Drought is one of the most complex recurring natural disasters, defined by a deficiency of precipitations that causes prolonged water scarcity. Failure to manage drought risk has the potential to have dire consequences for people, livelihoods, economy and ecosystems.
In northern Italy, particularly in the highly productive industrial area of the Po river basin, the 2021-2022 period culminated in the most severe drought of the last two centuries.
In order to evaluate the best policies to address the problems caused by water scarcity, it is crucial to measure and monitor variations in terrestrial water storage (TWS). For drought monitoring, in fact, changes or anomalies in TWS provide direct observations of total water availability, complementing model-based measures such as drought severity indices.
To estimate the quantities and spatial distribution of TWS loss, we analyze vertical ground displacement time-series data from Global Navigation Satellite System (GNSS) stations in the Po river basin.
We use a regularization model, based on L1-norm, to reconstruct the long-term temporal evolution of vertical ground displacement trends. Next, we performed a Principal Component Analysis (PCA) on GNSS time series to extract a spatially consistent signal in vertical ground displacements. The temporal evolution of the first principal component is well-correlated with trend changes of the Po river level and with the  SPEI-12 drought index, with stations moving upward during periods of river/index level decrease and vice versa, indicating that common long-term variations in vertical ground displacements are driven by the hydrology of the area.
The inversion of the displacements associated with the first principal component allows us to estimate variations in equivalent water height (EWH) and find that between January 2021 and August 2022, the GNSS stations underwent uplift, up to 7 mm, which corresponds to ~70 Gtons of water loss. The results are compared with the Global Land Data Assimilation System (GLDAS) model and the Gravity Recovery and Climate Experiment (GRACE) data: while the temporal evolution of the three products, when averaged over the study area, is similar, the spatial distributions are different. This is likely due to the fact that GLDAS only takes surface water into account, and GRACE has a too-coarse spatio-temporal resolution.
Our results show that multi-year changes in water storage can be effectively monitored both in terms of temporal evolution and spatial distribution using space geodetic measurements, such as GNSS. This approach eliminates the need to rely solely on large-scale models or satellite measurements, which cannot reach the spatial resolution required at the scale of river basins such as the Po.

How to cite: Pintori, F. and Serpelloni, E.: Drought‐Induced Vertical Displacements and Water Loss in the Po River Basin (Northern Italy) From GNSS Measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12650, https://doi.org/10.5194/egusphere-egu24-12650, 2024.

Since the beginning of the precision satellite altimeter era in the early 1990s, efforts have been focused on computing the mean height of the ocean surface for use in various geodetic and oceanographic studies. With 30 years of satellite measurements now available, it is time to rethink how we model the mean sea surface (MSS) in the era of climate change.

There are linear changes in the height of the ocean surface due to melting ice and increasing ocean heat content that will not average to zero when computing the mean. Today, there are places in the ocean that are 15 cm higher than they were at the start of the altimetric era some 30 years ago. Today, conventional MSS models like CLS15/22 or DTU15/21 are roughly 5 cm lower than what is observed by present-day satellites like Sentinel6-MF.

We propose that linear sea level changes are estimated simultaneously and consistently with the mean sea surface computation and added to the definition of the MSS, which is tied to a particular date in time. This is possible because the MSS are tied to the 2003.01.01 period for the DTU MSS models. 

We also investigated the acceleration of sea surface height but found these small and still unstable [Nerem et al., 2018]. We also found that these are still somewhat dependent on the Side A correction of the TOPEX mission. We conclude that a longer time series is needed before a stable map of the accelerations can be computed and applied.

There is considerable evidence that using a 30-year trend pattern in sea surface height is stable and is driven by the “forced response” of Greenhouse gases and aerosols. These patterns will be reasonably persistent as we move forward in time.

Testing a new DTU23MSS mean surface tailored to the year 2023 to our processing of the recently available 2023 SWOT data, we find this new DTU23MSS reduces the spatial variability of the SWOT data which is important to the processing and particularly the roll-error correction applied to the 2D SWOT sea surface height data. Applying the new DtU21MSS to conventional satellites like Sentinel-3A/B and 6 reduces both offset and spatial variability of the data indicating that the new MSS is actually very close to a “present-day mean”

 

How to cite: Andersen, O. B., Nerem, S., and Nielsson, B.: Consistent Mean Sea Surface and sea level change estimation in the Era of Climate Change – application to SWOT processing. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12785, https://doi.org/10.5194/egusphere-egu24-12785, 2024.

EGU24-13313 | ECS | Posters on site | G3.1

On the uncertainty of the uncertainty of long-term trends derived from geophysical and climate time series 

Kevin Gobron, Paul Rebischung, Roland Hohensinn, Janusz Bogusz, and Anna Klos

Quantifying the uncertainty associated with parameter estimates is crucial for a wide range of geophysical and climate applications. This is particularly important for interpreting the long-term trends of quantities of interest, such as ground displacement, sea level, and water storage (among others), estimated from geophysical time series. Unfortunately, our imperfect understanding of measurement error sources and of the intrinsic stochastic behavior of the quantities of interest often makes it difficult to realistically assess the uncertainty of long-term trend estimates. 

One pragmatic approach to obtaining realistic trend uncertainties is to model all the stochastic variations observed in the time series (that is, the “noise”) by stochastic processes, and then derive the trend uncertainty using the variance propagation law. In practice, such noise models often include unknown stochastic parameters controlling, e.g., the amplitudes or time correlations of the stochastic processes, which need to be estimated from the observations. Estimated stochastic parameters, however, come with uncertainty, just like any estimated quantity. And an uncertainty on the parameters of the noise model implies an uncertainty on the long-term trend uncertainty based on that noise model. In view of trend analysis from geophysical and climate time series data, the importance of considering such “uncertainty on the uncertainty” remains so far to be investigated.

In this study, we address this issue by assessing, using numerical simulation, how the uncertainty of stochastic models derived from sparse geophysical time series (a few hundred data points) translates into the uncertainty of long-term trend uncertainty estimates. We demonstrate that uncertainty in the time-correlation structure can result in significant uncertainty on trend uncertainty estimates. We then discuss the impact of such “uncertainty on the uncertainty” on the assessment of long-term trend significance from geodetic time series and provide recommendations on how to deal with the issue in practice.

How to cite: Gobron, K., Rebischung, P., Hohensinn, R., Bogusz, J., and Klos, A.: On the uncertainty of the uncertainty of long-term trends derived from geophysical and climate time series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13313, https://doi.org/10.5194/egusphere-egu24-13313, 2024.

EGU24-14224 | ECS | Orals | G3.1

Climate Change Studies through SWOT Phenomenology Research 

Jessica Fayne

Climate change is driving extreme spatial and temporal variability in surface water resources. This is particularly important for lake and wetland features, which have been under-characterized on the global scale. This under-characterization is largely due to the complex structural properties of these surfaces relative to available remote sensing data.  

The Surface Water and Ocean Topography Mission, as the first-of-its-kind 2D mapping and satellite interferometer using Ka-band SAR, was developed for mapping water surface extents and water surface elevations, providing a significant improvement in how we characterize and monitor surface water. Because of the novelty of the Ka-band SAR data for surface mapping, there have been limited studies of additional utilities SWOT can provide to complement water surface extent and elevation observations.  

First-look images from SWOT over Toulouse, France and Long Island, New York, USA, revealed strong signal returns over non-water surfaces, including agricultural fields and urban regions. Subsequent images highlighted by the SWOT Science Team also demonstrated wind-driven water surface signal variability, akin to NASA-JPL airborne AirSWOT investigations.  

This project provides early assessments of SWOT phenomenology for estimating characteristics that could contribute to novel datasets, such as wind speed, wind direction (for long wave formations), vegetation moisture, vegetation structure, and land surface moisture fraction. This work provides the foundation for a multi-year study to further develop the Ka-band Phenomenology Scattering Model (KaPS), and the wind model Ka-SWOT Model (Ka-SMOD), and will additionally discuss necessary reference datasets, models, and in-situ sampling necessary to complete this these assessments.

This project will increase the utility of the SWOT mission for studying diverse water and land features and significantly improve our understanding of fine-scale terrestrial hydrology. Given the relatively short temporal availability of the preliminary SWOT data, this work will focus on spatial variability across global sites, within the fast-sampling orbit, for observations taken for available dates in 2023. This preliminary analysis of the spatial and temporal variability of SWOT-derived phenomena aims to demonstrate how SWOT can be used in novel ways to study climate change. 

How to cite: Fayne, J.: Climate Change Studies through SWOT Phenomenology Research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14224, https://doi.org/10.5194/egusphere-egu24-14224, 2024.

EGU24-14655 | Orals | G3.1

The Big Soak:  Change in Water in 2023 in North America's Pacific Mountain System  

Donald Argus, Hilary Martens, Wiese David, Swarr Matthew, Borsa Adrian, Peidou Athina, Nicholas Lau, Dain Kim, Kevin Gaastra, Matthias Ellmer, Zachary Young, Ellen Knappe, Noah Molotch, Sarfaraz Alam, Felix Landerer, Payton Gardner, and Reager John

We are strengthening the application of GPS's capability to estimate change in total water using measurements of elastic displacements of Earth's surface; breaking down total water into its components such as snow, soil moisture, and groundwater; and integrating GRACE gravity data to infer change in total water in groundwater basins.

In California's Sierra Nevada, GPS each day tracks the dumping and dissipation of storm water.  In Water Year 2023, total water increased abruptly during each of two sequences of snow-dominated atmospheric rivers.  Subsurface water, which we take to be total water inferred from GPS minus snow water equivalent, to rise in early January at the time of the first AR sequence, remain constant from late Jan through March (with no increase during the second AR sequence), and rise from April to June as the snowpack melts.  Subsurface water increases in the Sierra Nevada by 0.6 m from Oct 2022 to Jun 2023, 45 per cent of cumulative precipitation of 1.4 m.  Such a big rise in subsurface water begins to rejuvenate the Sierra Nevada critical zone (Earth's living outer layer between the top of the trees and the bottom of groundwater) and to replenish subsurface water lost during the prior 3 years of drought from 2020 to 2022.

Change in total water in California's Central Valley can be determined neither by GRACE alone nor GPS alone.  There GPS records primarily Earth's poroelastic response, from which water change is difficult to infer.  GRACE cannot distinguish water change in Central Valley from water change in the Sierra Nevada without assuming a hydrology model.  We integrate GPS elastic displacements and GRACE gravity to estimate water change in the Central Valley.  In the rigorous inversion, GPS determines water change in the Sierra Nevada and Coast Ranges and the remaining water change from GRACE is placed in the Central Valley.  We find Central Valley groundwater increased by 0.75 m in the first nine months of Water Year 2023 (the biggest gain ever recorded), replenishing more groundwater than lost during the prior 3 years of drought.

How to cite: Argus, D., Martens, H., David, W., Matthew, S., Adrian, B., Athina, P., Lau, N., Kim, D., Gaastra, K., Ellmer, M., Young, Z., Knappe, E., Molotch, N., Alam, S., Landerer, F., Gardner, P., and John, R.: The Big Soak:  Change in Water in 2023 in North America's Pacific Mountain System , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14655, https://doi.org/10.5194/egusphere-egu24-14655, 2024.

EGU24-14952 | ECS | Posters on site | G3.1

Impact of Climate Change and Terrestrial Water Storage on the Himalayan Seismicity  

Sukanta Malakar and Abhishek K. Rai

The Himalayan terrain epitomises continuing convergence and geodetic deformation caused by tectonic and non-tectonic factors. Climate change and induced secondary factors are some of the dominant non-tectonic forces. A small change in stress and pore-fluid pressure caused by precipitation and temperature fluctuations may trigger seismic activity in the vicinity of already critically stressed faults and fractures at local and regional scales. The increase in temperature has also resulted in the melting of mountain glaciers in the Himalayan region and the release of the glacial load, leading to post-glacial rebound and elastic deformation. This study investigates the correlation and causal relationship between climatic parameters and earthquakes in the Himalayas. Further, we study the hydrological loading effect (derived from the GRACE/GRACE-FO satellite) and correlate it with the seismic hazard map. The results show that temperature anomalies have a relatively strong influence (r ~0.36-0.54) on the occurrence of minor-magnitude earthquakes in the Eastern Himalayas. However, the North-western Himalayas show a moderately positive correlation with precipitation anomalies (r ~0.23-0.37). Furthermore, a positive correlation has been found between regional terrestrial water storage (TWS) influence and the seismic hazard, ranging from 0.04-0.45. The result shows higher positive correlation values in the post-monsoon period for the North-western and Eastern Himalayas, whereas the Central Seismic Gap and Eastern Nepal and Sikkim show a higher value for the pre-monsoon period.

How to cite: Malakar, S. and Rai, A. K.: Impact of Climate Change and Terrestrial Water Storage on the Himalayan Seismicity , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14952, https://doi.org/10.5194/egusphere-egu24-14952, 2024.

EGU24-15227 | Orals | G3.1

Homogenization of GNSS IWV time series and estimation of climatic trends 

Olivier Bock, Ninh Khanh Nguyen, and Emilie Lebarbier

Water vapor plays a key role in the Earth's climate as a dominant greenhouse gas. It is also the most efficient actor of heat transfer from the surface to the atmosphere and from low to high latitudes which shapes the global atmospheric circulation and weather systems. Monitoring and understanding the spatial and temporal variability and changes of water vapor are thus of crucial importance.

This work aims at computing decadal trends of total column Integrated Water Vapour (IWV) from a global network of ground-based GNSS observations. Although GNSS observations are available with high accuracy in all weather conditions, it has been shown that, over long periods of time, changes in instrumentation, in station location and environment, and in processing methods can introduce spurious shifts in the IWV time series and bias trend estimates. Homogenization is a crucial step to detect and correct such non-climatic signals.

We have developed a relative homogenization method which involves three steps.

  • Segmentation. First, change-points are detected from the difference series (GNSS – reference) with the help of the GNSSseg segmentation package (Quarello et al., 2022). The method uses a difference series in order to cancel out the common climatic variations. It also accounts for changes in the variance on fixed intervals (monthly) and a periodic bias (annual) due to representativeness differences between GNSS and the reference (in our case the ERA5 reanalysis). Because the change-points detected in the difference series could be either due to GNSS or to the reference (ERA5), the next step is the attribution.
  • Attribution. Second, the detected change-points are attributed to either GNSS or to the reference (ERA5) using a statistical test based on linear regression and a predictive rule based on the Random Forest learning algorithm (Nguyen et al., 2023). This step requires additional neighbors stations (at least one).
  • Correction. The last step is the correction. Here the initial GNSS series is corrected only for the shifts which are attributed to the GNSS in the second step.

We will present results of the homogenization procedure applied to a global network of GNSS stations and discuss the impact of homogenization on linear trend estimates for stations that have more than 20 years of observations.

Quarello et al., 2022, https://doi.org/10.3390/rs14143379

Nguyen et al., 2023, https://hal-obspm.ccsd.cnrs.fr/IGN-ENSG/hal-04014145v1

How to cite: Bock, O., Nguyen, N. K., and Lebarbier, E.: Homogenization of GNSS IWV time series and estimation of climatic trends, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15227, https://doi.org/10.5194/egusphere-egu24-15227, 2024.

EGU24-15647 | ECS | Posters on site | G3.1

Spatio-temporal analysis of the ice mass changes over Greenland from GRACE and GRACE-FO. 

Florent Cambier, José Darrozes, Muriel Llubes, Lucia Seoane, and Guillaume Ramillien

Prediction of the trends of ice mass loss in Greenland can help for understanding what occurred during the last 20 years and in the future. The Level-2 GRACE and GRACE-FO solutions provided by the official computing centres CSR and ITSG as well as the combined products of the COST-G project give access to the spatio-temporal variations of the ice mass balance of Greenland from 2002 to present. We first reduce the GRACE data from post-glacial rebound. We propose to analyse these solutions by applying Singular Value Decomposition (SVD) and Empirical Mode Decomposition (EMD) to extract the trend. This trend is then removed from the timeseries for the Fast Fourier Transform (FFT) and 1-D Continuous Wavelet Transform (CWT) analysis. CWT and FFT analysis enable to unravel the long-term trend of the ice loss ranging from 6-9 years, as well as the annual and semi-annual part. The period of 6 to 9 years shows some correlation with meteorological and climate indexes such as North Atlantic Oscillation (NAO). The spatial component of the first SVD mode indicates that the ice melting is the most important along the west and southeast coast at the rate of -30 to -40 Gt/yr. Globally, the trend is not linear, it consist of different phases of acceleration and deceleration with rates between -60 and -340 Gt/yr.

How to cite: Cambier, F., Darrozes, J., Llubes, M., Seoane, L., and Ramillien, G.: Spatio-temporal analysis of the ice mass changes over Greenland from GRACE and GRACE-FO., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15647, https://doi.org/10.5194/egusphere-egu24-15647, 2024.

EGU24-16124 | ECS | Orals | G3.1

ACC Volume Transport: A Geodetic Analysis via Satellite Data 

Juan Adrián Vargas Alemañy, Isabel Vigo Aguiar, David García García, and Ferdous Zid

Geostrophic currents, driven by the Coriolis and pressure gradient forces, are crucial for understanding ocean circulation. The Antarctic Circumpolar Current (ACC) in the Southern Ocean, encircling Antarctica, has substantial global impact, and its volume transport (VT) remains challenging to measure. We utilize satellite data, combining Altimetry and Gravity Satellite missions, to estimate VT within the ACC. Our study offers a comprehensive spatial and temporal analysis, encompassing barotropic and baroclinic VT components. We validate our results with in-situ measurements from the Drake Passage. Our analysis reveals a steady spatial VT of 210.44 ± 3.4 Sv, with maxima near critical choke points. Temporally, we identify a mean VT of 15.86 ± 0.05 Sv per 1º grid cell, a linear trend of -0.007 ± 0.002 Sv per month, and significant seasonal and biannual signals. Zonal VT predominantly influences total VT, while meridional VT remains near zero. The baroclinic component drives low-frequency variations, while the barotropic component controls high-frequency variations. We propose a specific ACC zonal VT of 201.63 ± 0.71 Sv. In summary, our satellite-based approach offers valuable insights into ACC VT. This methodological extension enhances our understanding of the ACC's ocean circulation dynamics, showcasing the utility and robustness of satellite data in oceanographic research.

How to cite: Vargas Alemañy, J. A., Vigo Aguiar, I., García García, D., and Zid, F.: ACC Volume Transport: A Geodetic Analysis via Satellite Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16124, https://doi.org/10.5194/egusphere-egu24-16124, 2024.

EGU24-16767 | Posters on site | G3.1

A seafloor deformation study using A-0-A pressure instruments and ocean models to contribute to the monitoring of the Mayotte volcanic crisis. 

Valerie Ballu, Yann-Treden Tranchant, Denis Dausse, and Laurent Testut

The sudden 2018 volcanic eruption offshore Mayotte, in the western Indian Ocean, demonstrated, once again, the crucial need for means to monitor telluric activity occurring on the seafloor and threatening coastal zones. In the Mayotte case, on-land GNSS stations were of primary importance to detect the subsidence induced by the emptying of a deep magma chamber (Peltier et al. 2022), however they are not adequate to properly characterize and monitor the deformation created by further offshore or shallower processes.

Ocean bottom pressure (OBP) records can be used to monitor seafloor motion. However, detecting small or slow deformation is challenging due to instrumental drift and oceanic variations at different timescales. New Ambient-Zero-Ambient (A0A) pressure systems allow the estimation of the instrumental drift in situ by periodic venting from ocean pressures to a reference atmospheric pressure (Wilcock et al., 2021) and therefore allow access to the accurate monitoring of slow deformation. A A0A drift-controlled pressure gauge has been deployed since 2020 (four successive deployments) to monitor the seafloor vertical deformation on the flank of Mayotte island. The deployment site is located within a seismically active circular-shape zone, called the proximal cluster (Lavayssière et al., 2022). During the last deployment (2022-2023), an additional reference instrument was installed outside the proximal cluster, to allow for differential deformation analysis.

Beside volcanic activity monitoring, the objective of this study is to assess the performance of these new A0A pressure gauges and our ability to reduce the oceanic “noise” in corrected OBP records and characterize seafloor deformation in the Mayotte region. We investigate the use of numerical models, including available global ocean circulation reanalyses (OGCMs) and barotropic simulations, to account for the different oceanic processes contributing to the seafloor pressure variations and therefore limiting our ability to identify crustal deformation in the integrated pressure records.

We also use temperature and salinity profiles from repetitive glider transects to validate OGCMs in the region and quantify the contribution of unresolved fine-scale processes to OBP records. Our results provide valuable insights into the feasibility of using numerical modeling for improving the accuracy of OBP-based monitoring at different timescales, in the context of the Mayotte seismic crisis as well as for other seafloor deformation monitoring. Finally, we present a preliminary work on the combination of sparse regional altimetric data with the glider observations to compute a seafloor pressure series to be compared to the recorded data. Current altimetry spatio-temporal coverage is limited, however, newcoming SWOT observations are likely to provide new perspectives in seafloor geodesy.

Our results bring insights for future A0A deployments, especially in the perspective of the planned MARMOR seafloor cabled observatory offshore Mayotte.

How to cite: Ballu, V., Tranchant, Y.-T., Dausse, D., and Testut, L.: A seafloor deformation study using A-0-A pressure instruments and ocean models to contribute to the monitoring of the Mayotte volcanic crisis., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16767, https://doi.org/10.5194/egusphere-egu24-16767, 2024.

EGU24-16813 | Orals | G3.1

Global mean and local sea level budget from updated observations andresiduals analysis (SLBC_cci+ project) 

Marie Bouih, Anne Barnoud, Robin Fraudeau, Gilles Larnicol, Anny Cazenave, Benoit Meyssignac, Alejandro Blazquez, Martin Horwath, Thorben Döhne, Jonathan Bamber, Anrijs Abele, Stéphanie Leroux, Nicolas Kolodziejcyk, William Llovel, Giorgio Spada, Andrea Storto, Chunxue Yang, Sarah Connors, Marco Restano, and Jérôme Benveniste and the SLBC_cci+ team

The closure of the Sea Level Budget (SLB) at monthly, yearly, and interannual scales, with the utmost precision, remains a fundamental challenge in modern physical oceanography. Firstly, this closure is crucial to assert that all major contributors to sea level variability are accurately identified and quantified. Secondly, it serves as a valuable means for cross-validating complex global observation systems, such as the Argo in-situ network, satellite gravimetry missions GRACE/GRACE-FO, and the satellite altimetry constellation, while closely monitoring their performances. Thirdly, this closure proves to be an effective approach for testing the consistency of various observed variables within the climate system, including sea level, ocean temperature and salinity, ocean mass, land ice melt, and changes in land water storage, in accordance with conservation laws, notably those governing mass and energy.

In this presentation, we will share the latest results obtained for the sea level budget, including 1) an up-to-date estimate of the global mean budget closure from 1993 to 2022; 2) advancements in the analysis of regional patterns of each component of the budget, as well as of the budget residuals, allowing the identification of regions where the SLB does not close, with a focus on the North Atlantic and the Arctic Ocean where the residuals are significantly high. When and where the SLB closes, we can interpret the causes of the total sea level variations. The analysis at regional scales allows us to assess the relative importance of the individual components all over the oceans. When the SLB does not close, we investigate in each component the potential errors causing non-closure (e.g., in-situ data sampling, geocenter correction in gravimetric data) and how potential inconsistencies in their processing can impact large-scale patterns (e.g., geocenter and atmosphere corrections).

Future works will address questions related to the structural deficiency of the observing system, inconsistent effective resolution across different observing subsystems (in-situ data, satellite gravimetry, and satellite altimetry), potential measurement errors in a single observing subsystem, and the isolation of errors in terms of time and space. To address these questions, we will assess an SLB using synthetic components derived from oceanic models. This novel approach will enable us to estimate the spatial and temporal resolutions inherent in each observation, thereby enhancing the estimation of their respective uncertainties. We will also analyse the signature of internal climate variability on sea level budget components interannual changes, by using state-of-the-art model simulations and reanalyses.

This work is performed within the framework of the Sea Level Budget Closure Climate Change Initiative (SLBC_cci+) programme of the European Space Agency (ESA).

How to cite: Bouih, M., Barnoud, A., Fraudeau, R., Larnicol, G., Cazenave, A., Meyssignac, B., Blazquez, A., Horwath, M., Döhne, T., Bamber, J., Abele, A., Leroux, S., Kolodziejcyk, N., Llovel, W., Spada, G., Storto, A., Yang, C., Connors, S., Restano, M., and Benveniste, J. and the SLBC_cci+ team: Global mean and local sea level budget from updated observations andresiduals analysis (SLBC_cci+ project), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16813, https://doi.org/10.5194/egusphere-egu24-16813, 2024.

EGU24-17367 | Orals | G3.1

Assessing daily to interannual geocenter motion variations from Low Earth Orbiters 

Alexandre Couhert, Flavien Mercier, John Moyard, and Pierre Exertier

The ever-changing fluid mass (oceans, continental water, snow, atmosphere, …) redistributions on the Earth's surface give rise to a motion of the deformable terrestrial crust, that is its geometrical center-of-figure (CF), with respect to the center-of-mass (CM) of the Earth, about which satellites naturally orbit. This motion, called “geocenter motion”, is the largest scale variability of mass within the Earth system. Yet, non-tidal geocenter motion, which reflects major water and atmosphere mass transports occurring over large regions, is traditionally neglected.

However, new climate-driven precise monitoring of geocenter motion is needed. Indeed, satellite altimetry and gravimetry precise orbits connect sea level and global water budgets to the Earth’s center of mass. As such, the geocenter motion is now the leading error term in Regional Mean Sea Level and mass changes over polar ice sheets estimates. Reliable solutions of geocenter motion are thus crucial for assessing the current status of climate change and its future evolution (e.g., for the Earth’s Energy Imbalance).

Global Navigation Satellite Systems (GNSS) measurement models and derived products are currently aligned to the International Terrestrial Reference Frame (ITRF) origin (which is referenced to the crust), instead of CM. Looking at sub-daily cross-track perturbations estimated with the GNSS receivers on board the Jason-3 and Sentinel-6 MF altimetry satellites during their tandem phase (December 18, 2020 – April 7, 2022) revealed consistent diurnal oscillations with an impressive temporal resolution. These could only be related to the miscentering effect of the constellation solution around the Earth’ CM. In this paper, a parametric model is derived, representing the translation of the GNSS ground station networks with respect to the center of mass of the whole Earth system. This model is estimated with GNSS-based low Earth satellite precise orbits and unambiguously validated with independent altimetry satellite missions (e.g., Sentinel-3A, Sentinel-6 MF, Jason-3). It helps to clearly identify interannual variations in the geocenter motion, as short as a day long.

How to cite: Couhert, A., Mercier, F., Moyard, J., and Exertier, P.: Assessing daily to interannual geocenter motion variations from Low Earth Orbiters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17367, https://doi.org/10.5194/egusphere-egu24-17367, 2024.

EGU24-18031 | Posters on site | G3.1

Inferring North Atlantic Deep Water Transports from Ocean Bottom Pressure at the Western Boundary 

Maik Thomas, Linus Shihora, and Henryk Dobslaw

Estimating oceanic transports of volume, heat, carbon, and freshwater is fundamental to understanding the ocean’s role in the evolving climate system. Unique in this context is the Atlantic Meridional Overturning Circulation (AMOC) that comprises a net northward transport of relatively warm water at depths of ≲1 km throughout the Atlantic basin, compensated at ≳1–5 km by a colder net southward return flow.
While in-situ measurements, such as the RAPID array at 26.5°N, are considered the 'gold standard' to monitore changes in the AMOC, measurements at many latitudes and the detection of e.g. basin-wide modes are non feasible.
However, variations in the overturning are to a good degree accompanied by associated changes in oceanic bottom pressure which opens up new avenues of AMOC monitoring through bottom pressure recorders or even through future satellite gravimetry measurements. 

Here, we investigate the connection between changes in the Atlantic overturning and associated variations in bottom pressure along the western continental shelf in a suite of ocean models. This includes high resolution simulations from a CMIP6 FESOM run by AWI, the regional VIKING20X model by GEOMAR. We investigate to what degree the transport variations can be inferred from bottom pressure signatures alone, limitations of the approach and especially how such signatures could be implemented into a future iteration of the ESA ESM. This would allow the inclusion the these transport-related OBP changes in dedicated simulation studies for future satellite gravimetry missions.

How to cite: Thomas, M., Shihora, L., and Dobslaw, H.: Inferring North Atlantic Deep Water Transports from Ocean Bottom Pressure at the Western Boundary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18031, https://doi.org/10.5194/egusphere-egu24-18031, 2024.

EGU24-18783 | Posters on site | G3.1

A New Knowledge Portal on Mass Transport Satellite Missions: www.globalwaterstorage.info 

Ulrike Sylla, Pia Klinghammer, Antonia Cozacu, Frank Flechtner, Henryk Dobslaw, Julian Haas, Eva Boergens, Josef Zens, and Jörn Krupa

Dedicated satellite gravity missions orbiting the Earth at very low altitudes have greatly improved our knowledge about mass transport processes. That includes the terrestrial water cycle, ice sheet and glacier dynamics, ocean mass variability, and changes deep within the solid Earth, like the adjustment in the upper mantle in response to massive deglaciations since the last ice age. Initiated with the original GRACE (Gravity Recovery and Climate Experiment) mission launched in 2002, the record of monthly gravity fields now spans 22 years and is still being extended by GRACE-FO which has been in orbit since 2018. To enhance the visibility of the missions within society and to inform about the various contributions of GRACE/GRACE-FO to various scientific fields, GFZ  is maintaining a new knowledge portal accessible via www.globalwaterstorage.info.

On the one hand, this new portal provides overview information on satellite technology, various geophysical applications, and the numerous industrial and scientific partners who were vital for the success of the GRACE/GRACE-FO missions with the specific aim of informing European stakeholders. On the other hand, we also work towards developing the portal into a publicity channel for the gravimetry community to highlight recent developments towards future satellite missions or new research insights  based on mission data. International colleagues interested in advertising their latest achievements through a blog post (ca. 5000 characters) in the knowledge portal are kindly invited to contact globalwaterstorage@gfz-potsdam.de.

How to cite: Sylla, U., Klinghammer, P., Cozacu, A., Flechtner, F., Dobslaw, H., Haas, J., Boergens, E., Zens, J., and Krupa, J.: A New Knowledge Portal on Mass Transport Satellite Missions: www.globalwaterstorage.info, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18783, https://doi.org/10.5194/egusphere-egu24-18783, 2024.

EGU24-21332 | ECS | Orals | G3.1 | Highlight

Mass Balance of Greenland and Antarctic Ice Sheets since the 1970s 

Athul Kaitheri, Ines Otosaka, and Andrew Shepherd

Ice sheets in Antarctica and Greenland have continued to undergo rapid changes since the 1970s causing a significant rise in global mean sea level. The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) community has produced reconciled estimates of ice sheet mass changes for both ice sheets from the 1970s till 2021 by combining more than 50 independent mass balance estimates produced from varied satellite observations. Ice sheet mass changes are driven by competing processes due to their interaction with the atmosphere (surface mass balance) and ocean (ice dynamics). Here, we present an updated IMBIE assessment and partition mass trends into their surface mass balance (SMB) and ice dynamics components. This new assessment shows that Antarctica and Greenland contributed 29.3 mm to the global mean sea level between 1979 and 2021. While in Antarctica, almost all ice losses were driven by ice dynamical imbalance, we find that 60 % of Greenland’s ice losses were caused by increased ice discharge with reduced SMB accounting for the remainder. This exercise reveals the different drivers of Antarctica and Greenland mass changes and highlights their high interannual variability. Finally, we are aiming at producing reconciled regional ice sheet mass balance estimates for the main drainage basins of Antarctica and Greenland for the first time and will be presenting preliminary results for some of the key regions of the ice sheets that have been undergoing rapid changes. Partitioning mass trends and producing regional assessments will contribute to a better understanding of the remaining differences between the different satellite geodesy techniques employed within IMBIE and will provide a key dataset for both the Earth Observation and ice sheet modelling communities. 

How to cite: Kaitheri, A., Otosaka, I., and Shepherd, A.: Mass Balance of Greenland and Antarctic Ice Sheets since the 1970s, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21332, https://doi.org/10.5194/egusphere-egu24-21332, 2024.

EGU24-24 | Orals | NP4.1

The fractional Sinusoidal wavefront Model (fSwp) for time series displaying persistent stationary cycles 

Gael Kermarrec, Federico Maddanu, Anna Klos, and Tommaso Proietti

In the analysis of sub-annual climatological or geodetic time series such as tide gauges, precipitable water vapor, or GNSS vertical displacements time series but also temperatures or gases concentrations, seasonal cycles are often found to have a time-varying amplitude and phase.

These time series are usually modelled with a deterministic approach that includes trend, annual, and semi-annual periodic components having constant amplitude and phase-lag. This approach can potentially lead to inadequate interpretations, such as an overestimation of Global Navigation Satellite System (GNSS) station velocity, up to masking important geophysical phenomena that are related to the amplitude variability and are important for deriving trustworthy interpretation for climate change assessment.

We address that challenge by proposing a novel linear additive model called the fractional Sinusoidal Waveform process (fSWp), accounting for possible nonstationary cyclical long memory, a stochastic trend that can evolve over time and an additional serially correlated noise capturing the short-term variability. The model has a state space representation and makes use of the Kalman filter (KF). Suitable enhancements of the basic methodology enable handling data gaps, outliers, and offsets. We demonstrate our method using various climatological and geodetic time series to illustrate its potential to capture the time-varying stochastic seasonal signals.

How to cite: Kermarrec, G., Maddanu, F., Klos, A., and Proietti, T.: The fractional Sinusoidal wavefront Model (fSwp) for time series displaying persistent stationary cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-24, https://doi.org/10.5194/egusphere-egu24-24, 2024.

On some maps of the first military survey of the Habsburg Empire, the upper direction of the sections does not face the cartographic north, but makes an angle of about 15° with it. This may be due to the fact that the sections were subsequently rotated to the magnetic north of the time. Basically, neither their projection nor their projection origin is known yet.

In my research, I am dealing with maps of Inner Austria, the Principality of Transylvania and Galicia (nowadays Poland and Ukraine), and I am trying to determine their projection origin. For this purpose, it is assumed, based on the archival documentation of the survey, that these are Cassini projection maps. My hypothesis is that they are Graz, Cluj Napoca or Alba Julia and Lviv. I also consider the position of Vienna in each case, since it was the main centre of the survey.

The angle of rotation was taken in part from the gufm1 historical magnetic model back to 1590 for the assumed starting points and year of mapping. In addition, as a theoretical case, I calculated the rotation angle of the map sections using coordinate geometry. I then calculated the longitude of the projection starting point for each case using univariate minimization. Since the method is invariant to latitude, it can only be determined from archival data.

Based on these, the starting point for Inner Austria from the rotation of the map was Vienna, which is not excluded by the archival sources, and since the baseline through Graz also started from there, it is partly logical. The map rotation for Galicia and Transylvania also confirmed the starting point of the hypothesis.  Since both Alba Julia and Cluj Napoca lie at about the same longitude, the method cannot make a difference there; and the archival data did not provide enough evidence. In comparison, the magnetic declination rotations yielded differences of about 1°, which may be due to an error in the magnetic model.

On this basis, I have given the assumed projections of the three maps with projection starting points, and developed a method for determining the projection starting points of the other rotated grid maps. The results suggest that there is a very high probability that the section network was rotated in the magnetic north direction, and thus provide a way to refine the magnetic declination data at that time.

With this method I managed to give new indirekt magnetic declinations data from Central-East Europe, which can help to improve the historical magnetic field models. The main reason for this is that we don’t have any measurement from that region.

Furthermore the difference beetwen the angle of the section north and the declination data from gufm1 always 0.8-1°. Maybe there are systematical data error at that region.

Supported by the ÚNKP-23-6 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund.

How to cite: Koszta, B. and Timár, G.: A possible cartographical data source for historical magnetic field improvement: The direction of the section north of the Habsburg first military survey, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-582, https://doi.org/10.5194/egusphere-egu24-582, 2024.

EGU24-1988 | ECS | Posters on site | NP4.1

Predictive ability assessment of Bayesian Causal Reasoning (BCR) on runoff temporal series 

Santiago Zazo, José Luis Molina, Carmen Patino-Alonso, and Fernando Espejo

The alteration of traditional hydrological patterns due to global warming is leading to a modification of the hydrological cycle. This situation draws a complex scenario for the sustainable management of water resources. However, this issue offers a challenge for the development of innovative approaches that allow an in-depth capturing the logical temporal-dependence structure of these modifications to advance sustainable management of water resources, mainly through the reliable predictive models. In this context, Bayesian Causality (BC), addressed through Causal Reasoning (CR) and supported by a Bayesian Networks (BNs), called Bayesian Causal Reasoning (BCR) is a novel hydrological research area that can help identify those temporal interactions efficiently.

This contribution aims to assesses the BCR ability to discover the logical and non-trivial temporal-dependence structure of the hydrological series, as well as its predictability. For this, a BN that conceptually synthesizes the time series is defined, and where the conditional probability is propagated over the time throughout the BN through an innovative Dependence Mitigation Graph. This is done by coupling among an autoregressive parametric approach and causal model. The analytical ability of the BCR highlighted the logical temporal structure, latent in the time series, which defines the general behavior of the runoff. This logical structure allowed to quantify, through a dependence matrix which summarizes the strength of the temporal dependencies, the two temporal fractions that compose the runoff: one due to time (Temporally Conditioned Runoff) and one not (Temporally Non-conditioned Runoff). Based on this temporal conditionality, a predictive model is implemented for each temporal fraction, and its reliability is assessed from a double probabilistic and metrological perspective.

This methodological framework is applied to two Spanish unregulated sub-basins; Voltoya river belongs to Duero River Basin, and Mijares river, in the Jucar River Basin. Both cases with a clearly opposite temporal behavior, Voltoya independent and Mijares dependent, and with increasingly more problems associated with droughts.

The findings of this study may have important implications over the knowledge of temporal behavior of water resources of river basin and their adaptation. In addition, TCR and TNCR predictive models would allow advances in the optimal dimensioning of storage infrastructures (reservoirs), with relevant substantial economic/environmental savings. Also, a more sustainable management of river basins through more reliable control reservoirs’ operation is expected to be achieved. Finally, these results open new possibilities for developing predictive hydrological models within a BCR framework.

How to cite: Zazo, S., Molina, J. L., Patino-Alonso, C., and Espejo, F.: Predictive ability assessment of Bayesian Causal Reasoning (BCR) on runoff temporal series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1988, https://doi.org/10.5194/egusphere-egu24-1988, 2024.

EGU24-3857 | ECS | Posters on site | NP4.1 | Highlight

Spatial-Temporal Analysis of Forest Mortality 

Sara Alibakhshi

Climate-induced forest mortality poses an increasing threat worldwide, which calls for developing robust approaches to generate early warning signals of upcoming forest state change. This research explores the potential of satellite imagery, utilizing advanced spatio-temporal indicators and methodologies, to assess the state of forests preceding mortality events. Traditional approaches, such as techniques based on temporal analyses, are impacted by limitations related to window size selection and detrending methods, potentially leading to false alarms. To tackle these challenges, our study introduces two new approaches, namely the Spatial-Temporal Moran (STM) and Spatial-Temporal Geary (STG) approaches, both focusing on local spatial autocorrelation measures. These approaches can effectively address the shortcomings inherent in traditional methods. The research findings were assessed across three study sites within California national parks, and Kendall's tau was employed to quantify the significance of false and positive alarms. To facilitate the measurement of ecosystem state change, trend estimation, and identification of early warning signals, this study also provides "stew" R package. The implications of this research extend to various groups, such as ecologists, conservation practitioners, and policymakers, providing them with the means to address emerging environmental challenges in global forest ecosystems.

How to cite: Alibakhshi, S.: Spatial-Temporal Analysis of Forest Mortality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3857, https://doi.org/10.5194/egusphere-egu24-3857, 2024.

Iram Parvez1, Massimiliano Cannata2, Giorgio Boni1, Rossella Bovolenta1 ,Eva Riccomagno3 , Bianca Federici1

1 Department of Civil, Chemical and Environmental Engineering (DICCA), Università degli Studi di Genova, Via Montallegro 1, 16145 Genoa, Italy (iram.parvez@edu.unige.it,bianca.federici@unige.it, giorgio.boni@unige.it, rossella.bovolenta@unige.it).

2 Institute of Earth Sciences (IST), Department for Environment Constructions and Design (DACD), University of Applied Sciences and Arts of Southern Switzerland (SUPSI), CH-6952 Canobbio, Switzerland(massimiliano.cannata@supsi.ch).

3 Department of Mathematics, Università degli Studi di Genova, Via Dodecaneso 35, 16146 Genova, Italy(riccomag@dima.unige.it).

The deployment of hydrometeorological sensors significantly contributes to generating real-time big data. The quality and reliability of large datasets pose considerable challenges, as flawed analyses and decision-making processes can result. This research aims to address the issue of anomaly detection in real-time data by exploring machine learning models. Time-series data is collected from IstSOS - Sensor Observation Service, an open-source software that stores, collects and disseminates sensor data. The methodology consists of Gated Recurrent Units based on recurrent neural networks, along with corresponding prediction intervals, applied both to individual sensors and collectively across all temperature sensors within the Ticino region of Switzerland. Additionally, non-parametric methods like Bootstrap and Mean absolute deviation are employed instead of standard prediction intervals to tackle the non-normality of the data. The results indicate that Gated Recurrent Units based on recurrent neural networks, coupled with non-parametric forecast intervals, perform well in identifying erroneous data points. The application of the model on multivariate time series-sensor data establishes a pattern or baseline of normal behavior for the area (Ticino). When a new sensor is installed in the same region, the recognized pattern is used as a reference to identify outliers in the data gathered from the new sensor.

How to cite: Parvez, I.: Exploring Machine Learning Models to Detect Outliers in HydroMet Sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4280, https://doi.org/10.5194/egusphere-egu24-4280, 2024.

EGU24-5268 | ECS | Orals | NP4.1

Unveiling Geological Patterns: Bayesian Exploration of Zircon-Derived Time Series Data 

Hang Qian, Meng Tian, and Nan Zhang

For its immunity to post-formation geological modifications, zircon is widely utilized as chronological time capsule and provides critical time series data potential to unravel key events in Earth’s geological history, such as supercontinent cycles. Fourier analysis, which assumes stationary periodicity, has been applied to zircon-derived time series data to find the cyclicity of supercontinents, and wavelet analysis, which assumes non-stationary periodicity, corroborates the results of Fourier Analysis in addition to detecting finer-scale signals. Nonetheless, both methods still prognostically assume periodicity in the zircon-derived time-domain data. To stay away from the periodicity assumption and extract more objective information from zircon data, we opt for a Bayesian approach and treat zircon preservation as a composite stochastic process where the number of preserved zircon grains per magmatic event obeys logarithmic series distribution and the number of magmatic events during a geological time interval obeys Poisson distribution. An analytical solution was found to allow us to efficiently invert for the number and distribution(s) of changepoints hidden in the globally compiled zircon data, as well as for the zircon preservation potential (encoded as a model parameter) between two neighboring changepoints. If the distributions of changepoints temporally overlap with those of known supercontinents, then our results serve as an independent, mathematically robust test of the cyclicity of supercontinents. Moreover, our statistical approach inherently provides a sensitivity parameter the tuning of which allows to probe changepoints at various temporal resolution. The constructed Bayesian framework is thus of significant potential to detect other types of trend swings in Earth’s history, such as shift of geodynamic regimes, moving beyond cyclicity detection which limits the application of conventional Fourier/Wavelet analysis.

How to cite: Qian, H., Tian, M., and Zhang, N.: Unveiling Geological Patterns: Bayesian Exploration of Zircon-Derived Time Series Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5268, https://doi.org/10.5194/egusphere-egu24-5268, 2024.

Semi-enclosed freshwater and brackish ecosystems, characterised by restricted water outflow and prolonged residence times, often accumulate nutrients, influencing their productivity and ecological dynamics. These ecosystems exhibit significant variations in bio-physical-chemical attributes, ecological importance, and susceptibility to human impacts. Untangling the complexities of their interactions remains challenging, necessitating a deeper understanding of effective management strategies adapted to their vulnerabilities. This research focuses on the bio-physical aspects, investigating the differential effects of spring and summer light on phytoplankton communities in semi-enclosed freshwater and brackish aquatic ecosystems.

Through extensive field sampling and comprehensive environmental parameter analysis, we explore how phytoplankton respond to varying light conditions in these distinct environments. Sampling campaigns were conducted at Müggelsee, a freshwater lake on Berlin's eastern edge, and Barther Bodden, a coastal lagoon northeast of Rostock on the German Baltic Sea coast, during the springs and summers of 2022 and 2023, respectively. Our analysis integrates environmental factors such as surface light intensity, diffuse attenuation coefficients, nutrient availability, water column dynamics, meteorological data, Chlorophyll-a concentration, and phytoplankton communities. Sampling encompassed multiple depths at continuous intervals lasting three days.

Preliminary findings underscore significant differences in seasonal light availability, with summer exhibiting extended periods of substantial light penetration. These variations seem to impact phytoplankton abundance and diversity uniquely in each ecosystem. While ongoing analyses are underway, early indications suggest distinct phytoplankton responses in terms of species composition and community structure, influenced by the changing light levels. In 2022 the clear water phase during spring indicated that bloom events have occurred under ice cover much earlier than spring, while in the summer there were weak and short-lived blooms of cyanobacteria. The relationship between nutrient availability and phytoplankton dynamics, however, remains uncertain according to our data.

This ongoing study contributes to understanding the role of light as a primary driver shaping phytoplankton community structures and dynamics in these environments.  Our research findings offer insights for refining predictive models, aiding in ecosystem-specific eutrophication management strategies, and supporting monitoring efforts of Harmful Algal Blooms.

How to cite: Kaharuddin, A. and Kaligatla, R.: Comparative Study of Spring and Summer Light Effects on Phytoplankton Communities in Semi-Enclosed Fresh- and Brackish Aquatic Ecosystems., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5733, https://doi.org/10.5194/egusphere-egu24-5733, 2024.

EGU24-6065 | ECS | Orals | NP4.1

Magnetospheric time history:  How much do we need for forecasting? 

Kendra R. Gilmore, Sarah N. Bentley, and Andy W. Smith

Forecasting the aurora and its location accurately is important to mitigate any potential harm to vital infrastructure like communications and electricity grid networks. Current auroral prediction models rely on our understanding of the interaction between the magnetosphere and the solar wind or geomagnetic indices. Both approaches do well in predicting but have limitations concerning forecasting (geomagnetic indices-based model) or because of the underlying assumptions driving the model (due to a simplification of the complex interaction). By applying machine learning algorithms to this problem, gaps in our understanding can be identified, investigated, and closed. Finding the important time scales for driving empirical models provides the necessary basis for our long-term goal of predicting the aurora using machine learning.

Periodicities of the Earth’s magnetic field have been extensively studied on a global scale or in regional case studies. Using a suite of different time series analysis techniques including frequency analysis and investigation of long-scale changes of the median/ mean, we examine the dominant periodicities of ground magnetic field measurements at selected locations. A selected number of stations from the SuperMAG network (Gjerloev, 2012), which is a global network of magnetometer stations across the world, are the focus of this investigation.

The periodicities retrieved from the different magnetic field components are compared to each other as well as to other locations. In the context of auroral predictions, an analysis of the dominating periodicities in the auroral boundary data derived from the IMAGE satellite (Chisham et al., 2022) provides a counterpart to the magnetic field periodicities.

Ultimately, we can constrain the length of time history sensible for forecasting.

How to cite: Gilmore, K. R., Bentley, S. N., and Smith, A. W.: Magnetospheric time history:  How much do we need for forecasting?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6065, https://doi.org/10.5194/egusphere-egu24-6065, 2024.

EGU24-6151 | Posters on site | NP4.1

Using information-theory metrics to detect regime changes in dynamical systems 

Javier Amezcua and Nachiketa Chakraborty

Dynamical systems can display a range of dynamical regimes (e.g. attraction to, fixed points, limit cycles, intermittency, chaotic behaviour) depending on the values of parameters in the system. In this work we demonstrate how non-parametric entropy estimation codes (in particular NPEET) based on the Kraskov method can be applied to find regime transitions in a 3D chaotic model (the Lorenz 1963 system) when varying the values of the parameters. These infromation-theory-based methods are simpler and cheaper to apply than more traditional metrics from dynamical systems (e.g. computation of Lyapunov exponents). The non-parametric nature of the method allows for handling long time series without a prohibitive computational burden. 

How to cite: Amezcua, J. and Chakraborty, N.: Using information-theory metrics to detect regime changes in dynamical systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6151, https://doi.org/10.5194/egusphere-egu24-6151, 2024.

EGU24-9367 | ECS | Orals | NP4.1

Fractal complexity evaluation of meteorological droughts over three Indian subdivisions using visibility Graphs 

Susan Mariam Rajesh, Muraleekrishnan Bahuleyan, Arathy Nair GR, and Adarsh Sankaran

Evaluation of scaling properties and fractal formalisms is one of the potential approaches for modelling complex series. Understanding the complexity and fractal characterization of drought index time series is essential for better preparedness against drought disasters. This study presents a novel visibility graph-based evaluation of fractal characterization of droughts of three meteorological subdivisions of India. In this method, the horizontal visibility graph (HVG) and Upside-down visibility graph (UDVG) are used for evaluating the network properties for different standardized precipitation index (SPI) series of 3, 6 and 12 month time scales representing short, medium and long term droughts. The relative magnitude of fractal estimates is controlled by the drought characteristics of wet-dry transitions. The estimates of degree distribution clearly deciphered the self-similar properties of droughts of all the subdivisions. For an insightful depiction of drought dynamics, the fractal exponents and spectrum are evaluated by the concurrent application of Sand Box Method (SBM) and Chhabra and Jenson Method (CJM). The analysis was performed for overall series along with the pre- and post-1976-77 Global climate shift scenarios. The complexity is more evident in short term drought series and UDVG formulations implied higher fractal exponents for different moment orders irrespective of drought type and locations considered in this study. Useful insights on the relationship between complex network and fractality are evolved from the study, which may help in improved drought forecasting. The visibility graph based fractality estimation evaluation is efficient in capturing drought and it has vast potential in the drought predictions in a changing environment.

Keywords:  Drought, Fractal, SPI, Visibility Graph

How to cite: Rajesh, S. M., Bahuleyan, M., Nair GR, A., and Sankaran, A.: Fractal complexity evaluation of meteorological droughts over three Indian subdivisions using visibility Graphs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9367, https://doi.org/10.5194/egusphere-egu24-9367, 2024.

EGU24-9537 | Posters on site | NP4.1

Wavelet-Induced Mode Extraction procedure: Application to climatic data 

Elise Faulx, Xavier Fettweis, Georges Mabille, and Samuel Nicolay

The Wavelet-Induced Mode Extraction procedure (WIME) [2] was developed drawing inspiration from Empirical Mode Decomposition. The concept involves decomposing the signal into modes, each presenting a characteristic frequency, using continuous wavelet transform. This method has yielded intriguing results in climatology [3,4]. However, the initial algorithm did not account for the potential existence of slight frequency fluctuations within a mode, which could impact the reconstruction of the original signal [4]. The new version (https://atoms.scilab.org/toolboxes/toolbox_WIME/0.1.0) now allows for the evolution of a mode in the space-frequency half-plane, thus considering the frequency evolution of a mode [2]. A natural application of this tool is in the analysis of Milankovitch cycles, where subtle changes have been observed throughout history. The method also refines the study of solar activity, highlighting the role of the "Solar Flip-Flop." Additionally, the examination of temperature time series confirms the existence of cycles around 2.5 years. It is now possible to attempt to correlate solar activity with this observed temperature cycle, as seen in speleothem records [1].

[1] Allan, M., Deliège, A., Verheyden, S., Nicolay S. and Fagel, N. Evidence for solar influence in a Holocene speleothem record, Quaternary Science Reviews, 2018.
[2] Deliège, A. and Nicolay, S., Extracting oscillating components from nonstationary time series: A wavelet-induced method, Physical Review. E, 2017.
[3] Nicolay, S., Mabille, G., Fettweis, X. and Erpicum, M., A statistical validation for the cycles found in air temperature data using a Morlet wavelet-based method, Nonlinear Processes in Geophysics, 2010.
[4] Nicolay, S., Mabille, G., Fettweis, X. and Erpicum, M., 30 and 43 months period cycles found in air temperature time series using the Morlet wavelet, Climate Dynamics, 2009.

How to cite: Faulx, E., Fettweis, X., Mabille, G., and Nicolay, S.: Wavelet-Induced Mode Extraction procedure: Application to climatic data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9537, https://doi.org/10.5194/egusphere-egu24-9537, 2024.

EGU24-10258 | Orals | NP4.1

New concepts on quantifying event data 

Norbert Marwan and Tobias Braun

A wide range of geoprocesses manifest as observable events in a variety of contexts, including shifts in palaeoclimate regimes, evolutionary milestones, tectonic activities, and more. Many prominent research questions, such as synchronisation analysis or power spectrum estimation of discrete data, pose considerable challenges to linear tools. We present recent advances using a specific similarity measure for discrete data and the method of recurrence plots for different applications in the field of highly discrete event data. We illustrate their potential for palaeoclimate studies, particularly in detecting synchronisation between signals of discrete extreme events and continuous signals, estimating power spectra of spiky signals, and analysing data with irregular sampling.

How to cite: Marwan, N. and Braun, T.: New concepts on quantifying event data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10258, https://doi.org/10.5194/egusphere-egu24-10258, 2024.

EGU24-10415 | ECS | Orals | NP4.1

Application of Transfer Learning techniques in one day ahead PV production prediction 

Marek Lóderer, Michal Sandanus, Peter Pavlík, and Viera Rozinajová

Nowadays photovoltaic panels are becoming more affordable, efficient, and popular due to their low carbon footprint. PV panels can be installed in many places providing green energy to the local grid reducing energy cost and transmission losses. Since the PV production is highly dependent on the weather conditions, it is extremely important to estimate expected output in advance in order to maintain energy balance in the grid and provide enough time to schedule load distribution. The PV production output can be calculated by various statistical and machine learning prediction methods. In general, the more data available, the more precise predictions can be produced. This poses a problem for recently installed PV panels for which not enough data has been collected or the collected data are incomplete. 

A possible solution to the problem can be the application of an approach called Transfer Learning which has the inherent ability to effectively deal with missing or insufficient amounts of data. Basically, Transfer Learning is a machine learning approach which offers the capability of transferring knowledge acquired from the source domain (in our case a PV panel with a large amount of historical data) to different target domains (PV panels with very little collected historical data) to resolve related problems (provide reliable PV production predictions). 

In our study, we investigate the application, benefits and drawbacks of Transfer Learning for one day ahead PV production prediction. The model used in the study is based on complex neural network architecture, feature engineering and data selection. Moreover, we focus on the exploration of multiple approaches of adjusting weights in the target model retraining process which affect the minimum amount of training data required, final prediction accuracy and model’s overall robustness. Our models use historical meteorological forecasts from Deutscher Wetterdienst (DWD) and photovoltaic measurements from the project PVOutput which collects data from installed solar systems across the globe. Evaluation is performed on more than 100 installed PV panels in Central Europe.

How to cite: Lóderer, M., Sandanus, M., Pavlík, P., and Rozinajová, V.: Application of Transfer Learning techniques in one day ahead PV production prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10415, https://doi.org/10.5194/egusphere-egu24-10415, 2024.

EGU24-11897 | Posters on site | NP4.1

Results of joint processing of magnetic observatory data of international Intermagnet network in a unified coordinate system 

Beibit Zhumabayev, Ivan Vassilyev, Zhasulan Mendakulov, Inna Fedulina, and Vitaliy Kapytin

In each magnetic observatory, the magnetic field is registered in local Cartesian coordinate systems associated with the geographic coordinates of the locations of these observatories. To observe extraterrestrial magnetic field sources, such as the interplanetary magnetic field or magnetic clouds, a method of joint processing of data from magnetic observatories of the international Intermagnet network was implemented. In this method, the constant component is removed from the observation results of individual observatories, their measurement data is converted into the ecliptic coordinate system, and the results obtained from all observatories are averaged after the coordinate transformation.

The first data on joint processing of measurement results from the international network of Intermagnet magnetic observatories in the period before the onset of magnetic storms of various types, during these storms and after their end are presented. There is a significant improvement in the signal-to-noise ratio after combining the measurement results from all observatories, which makes it possible to isolate weaker external magnetic fields. A change in the shape of magnetic field variations is shown, which can provide new knowledge about the mechanism of development of magnetic storms.

How to cite: Zhumabayev, B., Vassilyev, I., Mendakulov, Z., Fedulina, I., and Kapytin, V.: Results of joint processing of magnetic observatory data of international Intermagnet network in a unified coordinate system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11897, https://doi.org/10.5194/egusphere-egu24-11897, 2024.

We introduce the CLEAN algorithm to identify narrowband Ultra Low Frequency (ULF) Pc5 plasma waves in Earth’s magnetosphere. The CLEAN method was first used for constructing 2D images in astronomical radio interferometry but has since been applied to a huge range of areas including adaptation for time series analysis. The algorithm performs a nonlinear deconvolution in the frequency domain (equivalent to a least-squares in the time domain) allowing for identification of multiple individual wave spectral peaks within the same power spectral density. The CLEAN method also produces real amplitudes instead of model fits to the peaks and retains phase information. We applied the method to GOES magnetometer data spanning 30 years to study the distribution of narrowband Pc5 ULF waves at geosynchronous orbit. We found close to 30,0000 wave events in each of the vector magnetic field components in field-aligned coordinates. We discuss wave occurrence and amplitudes distributed in local time and frequency. The distribution of the waves under different solar wind conditions are also presented. With some precautions, which are applicable to other event identification methods, the CLEAN technique can be utilized to detect wave events and its harmonics in the magnetosphere and beyond. We also discuss limitations of the method mainly the detection of unrealistic peaks due to aliasing and Gibbs phenomena.

How to cite: Inceoglu, F. and Loto'aniu, P.: Using the CLEAN Algorithm to Determine the Distribution of Ultra Low Frequency Waves at Geostationary Orbit, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12928, https://doi.org/10.5194/egusphere-egu24-12928, 2024.

EGU24-12938 | Posters on site | NP4.1

Applying Multifractal Theory and Statistical Techniques for High Energy Volcanic Explosion Detection and Seismic Activity Monitoring in Volcanic Time Series 

Marisol Monterrubio-Velasco, Xavier Lana, Raúl Arámbula-Mendoza, and Ramón Zúñiga

Understanding volcanic activity through time series data analysis is crucial for uncovering the fundamental physical mechanisms governing this natural phenomenon.

In this study, we show the application of multifractal and fractal methodologies, along with statistical analysis, to investigate time series associated with volcanic activity. We aim to make use of these approaches to identify significant variations within the physical processes related to changes in volcanic activity. These methodologies offer the potential to identify pertinent changes preceding a high-energy explosion or a significant volcanic eruption.

In particular, we apply it to analyze two study cases. First, the evolution of the multifractal structure of volcanic emissions of low, moderate, and high energy explosions applied to Volcán de Colima (México years 2013-2015). The results contribute to obtaining quite evident signs of the immediacy of possible dangerous emissions of high energy, close to 8.0x10^8 J. Additionally, the evolution of the adapted Gutenberg-Richter seismic law to volcanic energy emissions contributes to confirm the results obtained using multifractal analysis. Secondly, we also studied the time series of the Gutenberg-Richter b-parameter of seismic activities associated with volcanic emissions in Iceland, Hawaii, and the Canary Islands, through the concept of Disparity (degree of irregularity), the fractal Hurst exponent, H, and several multifractal parameters. The results obtained should facilitate a better knowledge of the relationships between the activity of volcanic emissions and the corresponding related seismic activities.  

How to cite: Monterrubio-Velasco, M., Lana, X., Arámbula-Mendoza, R., and Zúñiga, R.: Applying Multifractal Theory and Statistical Techniques for High Energy Volcanic Explosion Detection and Seismic Activity Monitoring in Volcanic Time Series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12938, https://doi.org/10.5194/egusphere-egu24-12938, 2024.

EGU24-13593 | ECS | Posters on site | NP4.1

Characterizing Uncertainty in Spatially Interpolated Time Series of Near-Surface Air Temperature 

Conor Doherty and Weile Wang

Spatially interpolated meteorological data products are widely used in the geosciences as well as disciplines like epidemiology, economics, and others. Recent work has examined methods for quantifying uncertainty in gridded estimates of near-surface air temperature that produce distributions rather than simply point estimates at each location. However, meteorological variables are correlated not only in space but in time, and sampling without accounting for temporal autocorrelation produces unrealistic time series and potentially underestimates cumulative errors. This work first examines how uncertainty in air temperature estimates varies in time, both seasonally and at shorter timescales. It then uses data-driven, spectral, and statistical methods to better characterize uncertainty in time series of estimated air temperature values. Methods for sampling that reproduce spatial and temporal autocorrelation are presented and evaluated. The results of this work are particularly relevant to domains like agricultural and ecology. Physical processes including evapotranspiration and primary production are sensitive to variables like near-surface air temperature, and errors in these important meteorological inputs accumulate in model outputs over time.

How to cite: Doherty, C. and Wang, W.: Characterizing Uncertainty in Spatially Interpolated Time Series of Near-Surface Air Temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13593, https://doi.org/10.5194/egusphere-egu24-13593, 2024.

EGU24-13879 | ECS | Posters on site | NP4.1

Understanding the role of vegetation responses to drought in regulating autumn senescence 

Eunhye Choi and Josh Gray

Vegetation phenology is the recurring of plant growth, including the cessation and resumption of growth, and plays a significant role in shaping terrestrial water, nutrient, and carbon cycles. Changes in temperature and precipitation have already induced phenological changes around the globe, and these trends are likely to continue or even accelerate. While warming has advanced spring arrival in many places, the effects on autumn phenology are less clear-cut, with evidence for earlier, delayed, or even unchanged end of the growing season (EOS). Meteorological droughts are intensifying in duration and frequency because of climate change. Droughts intricately impact changes in vegetation, contingent upon whether the ecosystem is limited by water or energy. These droughts have the potential to influence EOS changes. Despite this, the influence of drought on EOS remains largely unexplored. This study examined moisture’s role in controlling EOS by understanding the relationship between precipitation anomalies, vegetation’s sensitivity to precipitation (SPPT), and EOS. We also assess regional variations in responses to the impact of SPPT on EOS.

The study utilized multiple vegetation and water satellite products to examine the patterns of SPPT in drought and its impact on EOS across aridity gradients and vegetation types. By collectively evaluating diverse SPPTs from various satellite datasets, this work offers a comprehensive understanding and critical basis for assessing the impact of drought on EOS. We focused on the Northern Hemisphere from 2000 to 2020, employing robust statistical methods. This work found that, in many places, there was a stronger relationship between EOS and drought in areas with higher SPPT. Additionally, a non-linear negative relationship was identified between EOS and SPPT in drier regions, contracting with a non-linear positive relationship observed in wetter regions. These findings were consistent across a range of satellite-derived vegetation products. Our findings provide valuable insights into the effects of SPPT on EOS during drought, enhancing our understanding of vegetation responses to drought and its consequences on EOS and aiding in identifying drought-vulnerable areas.

How to cite: Choi, E. and Gray, J.: Understanding the role of vegetation responses to drought in regulating autumn senescence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13879, https://doi.org/10.5194/egusphere-egu24-13879, 2024.

EGU24-16981 | ECS | Orals | NP4.1

A machine-learning-based approach for predicting the geomagnetic secular variation 

Sho Sato and Hiroaki Toh

We present a machine-learning-based approach for predicting the geomagnetic main field changes, known as secular variation (SV), in a 5-year range for use for the 14th generation of International Geomagnetic Reference Field (IGRF-14). The training and test datasets of the machine learning (ML) models are geomagnetic field snapshots derived from magnetic observatory hourly means, and CHAMP and Swarm-A satellite data (MCM Model; Ropp et al., 2020). The geomagnetic field data are not used as-is in the original time series but were differenced twice before training. Because SV is strongly influenced by the geodynamo process occurring in the Earth's outer core, challenges still persist despite efforts to model and forecast the realistic nonlinear behaviors (such as the geomagnetic jerks) of the geodynamo through data assimilation. We compare three physics-uninformed ML models, namely, the Autoregressive (AR) model, Vector Autoregressive (VAR) model, and Recurrent Neural Network (RNN) model, to represent the short-term temporal evolution of the geomagnetic main field on the Earth’s surface. The quality of 5-year predictions is tested by the hindcast results for the learning window from 2004.50 to 2014.25. These tests show that the forecast performance of our ML model is comparable with that of candidate models of IGRF-13 in terms of data misfits after the release epoch (Year 2014.75). It is found that all three ML models give 5-year prediction errors of less than 100nT, among which the RNN model shows a slightly better accuracy. They also suggest that Overfitting to the training data used is an undesirable machine learning behavior that occurs when the RNN model gives accurate reproduction of training data but not for forecasting targets.

How to cite: Sato, S. and Toh, H.: A machine-learning-based approach for predicting the geomagnetic secular variation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16981, https://doi.org/10.5194/egusphere-egu24-16981, 2024.

EGU24-17344 | Posters on site | NP4.1

Introducing a new statistical theory to quantify the Gaussianity of the continuous seismic signal 

Éric Beucler, Mickaël Bonnin, and Arthur Cuvier

The quality of the seismic signal recorded at permanent and temporary stations is sometimes degraded, either abruptly or over time. The most likely cause is a high level of humidity, leading to corrosion of the connectors but environmental changes can also alter recording conditions in various frequency ranges and not necessarily for all three components in the same way. Assuming that the continuous seismic signal can be described by a normal distribution, we present a new approach to quantify the seismogram quality and to point out any time sample that deviates from this Gaussian assumption. To this end the notion of background Gaussian signal (BGS) to statistically describe a set of samples that follows a normal distribution. The discrete function obtained by sorting the samples in ascending order of amplitudes is compared to a modified probit function to retrieve the elements composing the BGS, and its statistical properties, mostly the Gaussian standard deviation, which can then differ from the classical standard deviation. Hence the ratio of both standard deviations directly quantifies the dominant gaussianity of the continuous signal and any variation reflects a statistical modification of the signal quality. We present examples showing daily variations in this ratio for stations known to have been affected by humidity, resulting in signal degradation. The theory developed can be used to detect subtle variations in the Gaussianity of the signal, but also to point out any samples that don't match the Gaussianity assumption, which can then be used for other seismological purposes, such as coda determination.

How to cite: Beucler, É., Bonnin, M., and Cuvier, A.: Introducing a new statistical theory to quantify the Gaussianity of the continuous seismic signal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17344, https://doi.org/10.5194/egusphere-egu24-17344, 2024.

EGU24-17566 | ECS | Posters on site | NP4.1

Unveiling Climate-Induced Ocean Wave Activities Using Seismic Array Data in the North Sea Region 

Yichen Zhong, Chen Gu, Michael Fehler, German Prieto, Peng Wu, Zhi Yuan, Zhuoyu Chen, and Borui Kang

Climate events may induce abnormal ocean wave activities, that can be detected by seismic array on nearby coastlines. We collected long-term continuous array seismic data in the Groningen area and the coastal areas of the North Sea, conducted a comprehensive analysis to extract valuable climate information hidden within the ambient noise. Through long-term spectral analysis, we identified the frequency band ranging from approximately 0.2Hz, which appears to be associated with swell waves within the region, exhibiting a strong correlation with the significant wave height (SWH). Additionally, the wind waves with a frequency of approximately 0.4 Hz and gravity waves with periods exceeding 100 seconds were detected from the seismic ambient noise. We performed a correlation analysis between the ambient noise and various climatic indexes across different frequency bands. The results revealed a significant correlation between the North Atlantic Oscillation (NAO) Index and the ambient noise around 0.17Hz.

Subsequently, we extracted the annual variation curves of SWH frequency from ambient noise at each station around the North Sea and assembled them into a sparse spatial grid time series (SGTS). An empirical orthogonal function (EOF) analysis was conducted, and the Principal Component (PC) time series derived from the EOF analysis were subjected to a correlation analysis with the WAVEWATCH III (WW3) model simulation data, thereby confirming the wave patterns. Moreover, we conducted the spatial distribution study of SGTS. The spatial features revealed that the southern regions of the North Sea exhibit higher wind-wave energy components influenced by the Icelandic Low pressure system and topography, which explains the correlation between ambient noise in the region and the NAO index. Furthermore, spatial features disclosed a correlation between the first EOF mode of the North Sea ocean waves and the third mode of sea surface temperature anomalies. This research shows the potential of utilizing existing off-shore seismic monitoring systems to study global climate variation and physical oceanography.

How to cite: Zhong, Y., Gu, C., Fehler, M., Prieto, G., Wu, P., Yuan, Z., Chen, Z., and Kang, B.: Unveiling Climate-Induced Ocean Wave Activities Using Seismic Array Data in the North Sea Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17566, https://doi.org/10.5194/egusphere-egu24-17566, 2024.

EGU24-18061 | ECS | Orals | NP4.1

A new methodology for time-series reconstruction of global scale historical Earth observation data 

Davide Consoli, Leandro Parente, and Martijn Witjes

Several machine learning algorithms and analytical techniques do not allow gaps or non-values in input data. Unfortunately, earth observation (EO) datasets, such as satellite images, are gravely affected by cloud contamination and sensor artifacts that create gaps in the time series of collected images. This limits the usage of several powerful techniques for modeling and analysis. To overcome these limitations, several works in literature propose different imputation methods to reconstruct the gappy time series of images, providing complete time-space datasets and enabling their usage as input for many techniques.

However, among the time-series reconstruction methods available in literature, only a few of them are publicly available (open source code), applicable without any external source of data, and suitable for application to petabyte (PB) sized dataset like the full Landsat archive. The few methods that match all these characteristics are usually quite trivial (e.g. linear interpolation) and, as a consequence, they often show poor performance in reconstructing the images. 

For this reason, we propose a new methodology for time series reconstruction designed to match all these requirements. Like some other methods in literature, the new method, named seasonally weighted average generalization (SWAG), works purely on the time dimension, reconstructing the images working on each time series of each pixel separately. In particular, the method uses a weighted average of the samples available in the original time series to reconstruct the missing values. Enforcing the annual seasonality of each band as a prior, for the reconstruction of each missing sample in the time series a higher weight is given to images that are collected exactly on integer multiples of a year. To avoid propagation of land cover changes in future or past images, higher weights are given to more recent images. Finally, to have a method that respects causality, only images from the past of each sample in the time series are used.

To have computational performance suitable for PB sized datasets the method has been implemented in C++ using a sequence of fast convolution methods and Hadamard products and divisions. The method has been applied to a bimonthly aggregated version of the global GLAD Landsat ARD-2 collection from 1997 to 2022, producing a 400 terabyte output dataset. The produced dataset will be used to generate maps for several biophysical parameters, such as Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), normalized difference water index (NDWI) and bare soil fraction (BSF). The code is available as open source, and the result is fully reproducible.

References:

Potapov, Hansen, Kommareddy, Kommareddy, Turubanova, Pickens, ... & Ying  (2020). Landsat analysis ready data for global land cover and land cover change mapping. Remote Sensing, 12(3), 426.

Julien, & Sobrino (2019). Optimizing and comparing gap-filling techniques using simulated NDVI time series from remotely sensed global data. International Journal of Applied Earth Observation and Geoinformation, 76, 93-111.

Radeloff, Roy, Wulder, Anderson, Cook, Crawford, ... & Zhu (2024). Need and vision for global medium-resolution Landsat and Sentinel-2 data products. Remote Sensing of Environment, 300, 113918.

How to cite: Consoli, D., Parente, L., and Witjes, M.: A new methodology for time-series reconstruction of global scale historical Earth observation data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18061, https://doi.org/10.5194/egusphere-egu24-18061, 2024.

EGU24-18197 | ECS | Orals | NP4.1 | Highlight

The regularity of climate-related extreme events under global warming 

Karim Zantout, Katja Frieler, and Jacob Schewe and the ISIMIP team

Climate variability gives rise to many different kinds of extreme impact events, including heat waves, crop failures, or wildfires. The frequency and magnitude of such events are changing under global warming. However, it is less known to what extent such events occur with some regularity, and whether this regularity is also changing as a result of climate change. Here, we present a novel method to systematically study the time-autocorrelation of these extreme impact events, that is, whether they occur with a certain regularity. In studies of climate change impacts, different types of events are often studied in isolation, but in reality they interact. We use ensembles of global biophysical impact simulations from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) driven with climate models to assess current conditions and projections. The time series analysis is based on a discrete Fourier transformation that accounts for the stochastic fluctuations from the climate model. Our results show that some climate impacts, such as crop failure, indeed exhibit a dominant frequency of recurrence; and also, that these regularity patterns change over time due to anthropogenic climate forcing.

How to cite: Zantout, K., Frieler, K., and Schewe, J. and the ISIMIP team: The regularity of climate-related extreme events under global warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18197, https://doi.org/10.5194/egusphere-egu24-18197, 2024.

EGU24-18210 | ECS | Posters on site | NP4.1

Long-term vegetation development in context of morphodynamic processes since mid-19th century 

Katharina Ramskogler, Moritz Altmann, Sebastian Mikolka-Flöry, and Erich Tasser

The availability of comprehensive aerial photography is limited to the mid-20th century, posing a challenge for quantitatively analyzing long-term surface changes in proglacial areas. This creates a gap of approximately 100 years, spanning the end of the Little Ice Age (LIA). Employing digital monoplotting and historical terrestrial images, our study reveals quantitative surface changes in a LIA lateral moraine section dating back to the second half of the 19th century, encompassing a total study period of 130 years (1890 to 2020). With the long-term analysis at the steep lateral moraines of Gepatschferner (Kauner Valley, Tyrol, Austria) we aimed to identify changes in vegetation development in context with morphodynamic processes and the changing climate.

In 1953, there was an expansion in the area covered by vegetation, notably encompassing scree communities, alpine grassland, and dwarf shrubs. However, the destabilization of the system after 1980, triggered by rising temperatures and the resulting thawing of permafrost, led to a decline in vegetation cover by 2020. Notably, our observations indicated that, in addition to morphodynamic processes, the overarching trends in temperature and precipitation exerted a substantial influence on vegetation development. Furthermore, areas with robust vegetation cover, once stabilised, were reactivated and subjected to erosion, possibly attributed to rising temperatures post-1980.

This study demonstrates the capability of historical terrestrial images to enhance the reconstruction of vegetation development in context with morphodynamics in high alpine environments within the context of climate change. However, it is important to note that long-term mapping of vegetation development through digital monoplotting has limitations, contingent on the accessibility and quality of historical terrestrial images, as well as the challenges posed by shadows in high alpine regions. Despite these limitations, this long-term approach offers fundamental data on vegetation development for future modelling efforts.

How to cite: Ramskogler, K., Altmann, M., Mikolka-Flöry, S., and Tasser, E.: Long-term vegetation development in context of morphodynamic processes since mid-19th century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18210, https://doi.org/10.5194/egusphere-egu24-18210, 2024.

EGU24-19601 | ECS | Posters on site | NP4.1

Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform 

Palangio Paolo Giovanni and Santarelli Lucia

Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform

  • Palangio1, L. Santarelli 1

1Istituto Nazionale di Geofisica e Vulcanologia L’Aquila

3Istituto Nazionale di Geofisica e Vulcanologia Roma

 

Correspondence to:  lucia.santarelli@ingv.it

 

Abstract

In this paper we present an application of  the SSA Transform to the detection and reconstruction of  very weak geomagnetic signals hidden in noise. In the SSA Transform  multiple subspaces are used for representing and reconstructing   signals and noise.  This analysis allows us to reconstruct, in the time domain, the different harmonic components contained in the original signal by using  ortogonal functions. The objective is to identificate the dominant  subspaces that can be attributed to the  signals and the subspaces that can be attributed to the noise,  assuming that all these  subspaces are orthogonal to each other, which implies that the  signals and noise  are independent of one another. The subspace of the signals is mapped simultaneously on several spaces with a lower dimension, favoring the dimensions that best discriminate the patterns. Each subspace of the signal space is used to encode different subsets of functions having common characteristics, such as  the same periodicities. The subspaces  identification was performed by using singular value decomposition (SVD) techniques,  known as  SVD-based identification methods  classified in a subspace-oriented scheme.The  quasi-periodic variations of geomagnetic field  has been investigated in the range of scale which span from 22 years to 8.9 days such as the  Sun’s polarity reversal cycle (22 years), sun-spot cycle (11 years), equinoctial effect (6 months), synodic rotation of the Sun (27 days) and its harmonics. The strength of these signals vary from fractions of a nT to tens of nT. Phase and frequency variability of these cycles has been evaluated from the range of variations in the geomagnetic field recorded at middle latitude place (covering roughly 4.5 sunspot cycles). Magnetic data recorded at L'Aquila Geomagnetic observatory (geographic coordinates: 42° 23’ N, 13° 19’E, geomagnetic coordinates: 36.3° N,87°.2 E, L-shell=1.6) are used from 1960 to 2009.

 

 

How to cite: Paolo Giovanni, P. and Lucia, S.: Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19601, https://doi.org/10.5194/egusphere-egu24-19601, 2024.

EGU24-22262 | ECS | Posters on site | NP4.1

Temporal Interpolation of Sentinel-2 Multispectral Time Series in Context of Land Cover Classification with Machine Learning Algorithms 

Mate Simon, Mátyás Richter-Cserey, Vivien Pacskó, and Dániel Kristóf

Over the past decades, especially since 2014, large quantities of Earth Observation (EO) data became available in high spatial and temporal resolution, thanks to ever-developing constellations (e.g.: Sentinel, Landsat) and open data policy. However, in the case of optical images, affected by cloud coverage and the spatially changing overlap of relative satellite orbits, creating temporally generalized and dense time series by using only measured data is challenging, especially when studying larger areas.

Several papers investigate the question of spatio-temporal gap filling and show different interpolation methods to calculate missing values corresponding to the measurements. In the past years more products and technologies have been constructed and published in this field, for example Copernicus HR-VPP Seasonal Trajectories (ST) product.  These generalized data structures are essential to the comparative analysis of different time periods or areas and improve the reliability of data analyzing methods such as Fourier transform or correlation. Temporally harmonized input data is also necessary in order to improve the results of Machine Learning classification algorithms such as Random Forest or Convolutional Neural Networks (CNN). These are among the most efficient methods to separate land cover categories like arable lands, forests, grasslands and built-up areas, or crop types within the arable category.

This study analyzes the efficiency of different interpolation methods on Sentinel-2 multispectral time series in the context of land cover classification with Machine Learning. We compare several types of interpolation e.g. linear, cubic and cubic-spline and also examine and optimize more advanced methods like Inverse Distance Weighted (IDW) and Radial Basis Function (RBF). We quantify the accuracy of each method by calculating mean square error between measured and interpolated data points. The role of interpolation of the input dataset in Deep Learning (CNN) is investigated by comparing Overall, Kappa and categorical accuracies of land cover maps created from only measured and interpolated time series. First results show that interpolation has a relevant positive effect on accuracy statistics. This method is also essential in taking a step towards constructing robust pretrained Deep Learning models, transferable between different time intervals and agro-ecological regions.

The research has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2021 funding scheme.

 

Keywords: time series analysis, Machine Learning, interpolation, Sentinel

How to cite: Simon, M., Richter-Cserey, M., Pacskó, V., and Kristóf, D.: Temporal Interpolation of Sentinel-2 Multispectral Time Series in Context of Land Cover Classification with Machine Learning Algorithms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22262, https://doi.org/10.5194/egusphere-egu24-22262, 2024.

EGU24-313 | ECS | Orals | OS1.3 | Highlight

Multi-decadal changes in water mass properties of the South Indian Ocean along 110°E 

Meng Han, Helen Phillips, Nathan Bindoff, Ming Feng, and Ramkrushnbhai Patel

Two hydrographic voyages separated by 56 years reveal significant changes in the watermass properties in the southeast Indian Ocean along 110°E. The observations from the International Indian Ocean Expedition in 1963 and the reoccupation of the line in 2019 covered the full ocean depth from 40°S to 11°S, measuring physical, chemical, and biological properties. We focus on the physical and biogeochemical properties in watermass layers of the global meridional overturning circulation and the Indian Ocean’s shallow overturning cells.  The subtropical high salinity water (STHW), which forms the lower branch of the shallow overturning cells, has warmer and increased salinity. Subantarctic Mode Water has cooled and freshened on density levels and Antarctic Intermediate Water (AAIW) has warmed and increased in salinity. Both the SAMW and AAIW watermasses have decreased dissolved oxygen content but increased concentrations of nitrate and phosphate. The results show that changes within watermasses follow their northward pathways, suggesting influences from their formation regions, modified by interior mixing along the overturning pathways.

How to cite: Han, M., Phillips, H., Bindoff, N., Feng, M., and Patel, R.: Multi-decadal changes in water mass properties of the South Indian Ocean along 110°E, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-313, https://doi.org/10.5194/egusphere-egu24-313, 2024.

EGU24-727 | ECS | Orals | OS1.3 | Highlight

Indian Summer Monsoon Rainfall trends over 1979-2022 driven by ocean warming and anomalous wind patterns. 

Ligin Joseph, Nikolaos Skliris, Dipanjan Dey, and Robert Marsh

India receives 80% of its annual rainfall during the Indian Summer Monsoon (ISM) season from June to September. The climate model simulations of Coupled Model Intercomparison Project 6 (CMIP6) robustly indicate a strengthening of the Indian summer monsoon rainfall in a warming climate, despite a reduced land-sea thermal contrast. In this study, we analysed the ISM precipitation trend over India from 1979 to 2022 using rain gauge, satellite-derived, and atmospheric re-analysis data. The results show a broad-scale increasing precipitation trend over major parts of India. However, there is strong spatial variability, with a pronounced precipitation increase over Western India and decreasing precipitation in parts of north-eastern India. The precipitation trend pattern is associated with sea surface temperature (SST) and wind anomalies over the Indian Ocean. Observations indicate a basin-scale warming of the Indian Ocean (IO) that is more prominent in the west equatorial region and Arabian Sea (AS), altering the east-west SST gradient over this period, which is associated with increased equatorial winds during the summer monsoon period. Evaporation correspondingly increases over the Indian Ocean, with widespread increases along the typical atmospheric moisture transport pathway over the western Indian Ocean during the summer monsoon, driven by both ocean surface warming and increasing winds. Increased evaporation results in more moisture being available in the atmosphere over the western Indian Ocean, which subsequently feeds ISM precipitation. Furthermore, a strong correlation between the AS moisture transport and the ISM rainfall has been noticed over the central and western parts of India, where increased precipitation trends exist. A moisture budget trend analysis over Western India suggests that the large increase in moisture convergence in this area is driven by increased moisture entering from the AS concomitant with strongly reduced outgoing moisture transport through the eastern and northern boundaries. A detailed analysis shows that the increased moisture convergence in Western India is predominantly attributed to changes in the wind pattern driven by anomalously reduced winds in the northern part of the peninsula. In addition, the teleconnections between ISM rainfall and large-scale natural climate variability modes such as ENSO and IOD were also shown to modulate precipitation variations over India during the considered period at inter-annual to multi-decadal scales. 

How to cite: Joseph, L., Skliris, N., Dey, D., and Marsh, R.: Indian Summer Monsoon Rainfall trends over 1979-2022 driven by ocean warming and anomalous wind patterns., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-727, https://doi.org/10.5194/egusphere-egu24-727, 2024.

The Indian Ocean dipole (IOD) has a significant impact on the global atmospheric circulation and contributes to determining important aspects of local and global environments. Although the IOD events can significantly cause SST anomalies and chlorophyll fluctuations in the western Indian Ocean, there is still very little known about the interannual variability of the Arabian Sea oxygen minimum zone (ASOMZ) under the influence of these remote forcing processes. In this study, a coupled physical-biogeochemical numerical model was used to investigate the dynamical response of the ASOMZ to extreme negative (2016) and positive (2019) IOD events. Our findings revealed that the suboxic area of the ASOMZ reduced (expanded) by about 27% (about 28%) after the negative (positive) IOD event. Compared to the 2019 pIOD event, approximately 2.5 times more oxygen-rich water was delivered into the Arabian Sea during the 2016 nIOD event, replenishing dissolved oxygen (DO) consumed by intensified upwelling-induced enhanced remineralization of particulate organic matter (POM), thereby increasing the DO concentration in the Gulf of Aden. Conversely, more POM from the upwelling regions in the western Arabian Sea was transported to the central Arabian Sea, leading to a subsequent decrease in DO concentration there. These findings contributed to our understanding of the ASOMZ's response to IOD events, which is essential for studying the Arabian Sea's marine ecosystem.

How to cite: Zhang, Z.: Dynamical Response of the Arabian Sea Oxygen Minimum Zone to the Extreme Indian Ocean Dipole Events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1410, https://doi.org/10.5194/egusphere-egu24-1410, 2024.

EGU24-1583 | ECS | Orals | OS1.3

The Influence of Freshwater Input on the Evolution of the 1995 Benguela Niño 

Leo Costa Aroucha, Joke Lübbecke, Mareike Körner, Rodrigue Anicet Imbol Koungue, and Founi Mesmin Awo

Benguela Niño events are characterized by strong warm sea surface temperature (SST) anomalies off the Angolan and Namibian coasts. In 1995, the strongest event in the satellite era took place, impacting fish availability in both Angolan and Namibian waters. In this study, we use direct observations, satellite data, and reanalysis products to investigate the impact that the up-until-now unnoticed mechanism of freshwater input from Congo River discharge (CRD) and precipitation had on the evolution of the 1995 Benguela Niño. Before the onset phase of the event, anomalous rainfall in November/December 1994 at around 6ºS, combined with a high CRD, generated a low salinity plume. The plume was advected into the Angola-Namibia region in the following February/March 1995 by an anomalously strong poleward surface current generated by the relaxation of the southerly winds and shifts in the coastal wind stress curl. The presence of this low surface salinity anomaly of about -2 psu increased ocean stability by generating barrier layers, thereby reducing the turbulent heat loss, since turbulent mixing acted on a weak vertical temperature gradient. A mixed layer heat budget analysis demonstrates that southward advection of Angolan waters drove the warming at the onset of the event, while reduced mixing played the main role at the event’s peak. We conclude that a freshwater input contributed to the SST increase in this exceptionally strong event and suggest that this input can influence the SST variability in Angola-Namibia waters through a combination of high CRD, precipitation, and the presence of a strong poleward surface current.

How to cite: Costa Aroucha, L., Lübbecke, J., Körner, M., Imbol Koungue, R. A., and Awo, F. M.: The Influence of Freshwater Input on the Evolution of the 1995 Benguela Niño, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1583, https://doi.org/10.5194/egusphere-egu24-1583, 2024.

EGU24-2595 | Orals | OS1.3

Emergence of the Central Atlantic Niño 

Lei Zhang, Chunzai Wang, Weiqing Han, Michael McPhaden, Aixue Hu, and Wen Xing

The Atlantic Niño is characterized by sea surface warming in the equatorial Atlantic, which can trigger La Niña - the cold phase of El Niño-Southern Oscillation (ENSO). Although observations show that the Atlantic Niño has weakened by approximately 30% since the 1970s, its remote influence on ENSO remains strong. Here we show that this apparent discrepancy is due to the existence of two types of Atlantic Niño with distinct patterns and climatic impacts, which we refer to as the central and eastern Atlantic Niño. Our results show that with equal strength, the central Atlantic Niño has a stronger influence on tropical climate than its eastern counterpart. Meanwhile, the eastern Atlantic Niño has weakened by approximately 50% in recent decades, allowing the central Atlantic Niño to emerge and dominate the remote impact on ENSO. Given the distinct climatic impacts of the two types, it is necessary to distinguish between them and investigate their behaviors and influences on climate in future studies.

How to cite: Zhang, L., Wang, C., Han, W., McPhaden, M., Hu, A., and Xing, W.: Emergence of the Central Atlantic Niño, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2595, https://doi.org/10.5194/egusphere-egu24-2595, 2024.

EGU24-2956 * | ECS | Orals | OS1.3 | Highlight

Future Indian Ocean warming patterns 

Sahil Sharma, Kyung-Ja Ha, Ryohei Yamaguchi, Keith B. Rodgers, Axel Timmermann, and Eui-Seok Chung

Most future projections conducted with coupled general circulation models simulate a non-uniform Indian Ocean warming, with warming hotspots occurring in the Arabian Sea (AS) and the southeastern Indian Ocean (SEIO). But little is known about the underlying physical drivers. Here, we are using a suite of large ensemble simulations of the Community Earth System Model 2 to elucidate the causes of non-uniform Indian Ocean warming. Strong negative air-sea interactions in the Eastern Indian Ocean are responsible for a future weakening of the zonal sea surface temperature gradient, resulting in a slowdown of the Indian Ocean Walker circulation and the generation of southeasterly wind anomalies over the AS. These contribute to anomalous northward ocean heat transport, reduced evaporative cooling, a weakening in upper ocean vertical mixing and an enhanced AS future warming. In contrast, the projected warming in the SEIO is related to a reduction of low-cloud cover and an associated increase in shortwave radiation. Therefore, the regional character of air-sea interactions plays a key role in promoting future large-scale tropical atmospheric circulation anomalies with implications for society and ecosystems far outside the Indian Ocean realm.

How to cite: Sharma, S., Ha, K.-J., Yamaguchi, R., Rodgers, K. B., Timmermann, A., and Chung, E.-S.: Future Indian Ocean warming patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2956, https://doi.org/10.5194/egusphere-egu24-2956, 2024.

EGU24-3250 | Orals | OS1.3 | Highlight

Indian Ocean Dipole Intensifies Benguela Niño Through Congo River Discharge 

Michael McPhaden, Sreelekha Jarugula, Leo Aroucha, and Joke Luebbecke

Benguela Niños are periodic episodes of unusual El Niño-like warming in the upwelling zone off the coast of southwest Africa with significant impacts on marine ecosystems, coastal fisheries and regional weather variability.  The strongest Benguela Niño in the past 40 years occurred in February-April 1995 with areal average sea surface temperature (SST) anomalies of 2°C and local anomalies up to 4°C off the coast of Angola and Namibia.  Benguela Niños are generated through a combination of remote and regional wind-forced dynamical processes originating within the Atlantic basin. However, a recent study has argued that the extraordinary warming observed in early 1995 resulted from southward advection of unusually high fresh water discharge from the Congo River, which led to the formation of thin mixed layers that trapped heat near the surface to boost coastal SSTs. 

The purpose of this presentation is to show that a strong Indian Ocean Dipole (IOD) that peaked in September-November 1994 was the reason for the high Congo River discharge in early 1995. IOD events are roughly the Indian Ocean equivalent of El Niño and La Niña events in the Pacific, which are generated though anomalous coupled interactions between surface winds and SSTs. It has been previously demonstrated that the IOD can affect eastern tropical Atlantic sea surface salinity through Congo River basin hydrology.  In particular, positive IOD events (warm SSTs in the western Indian Ocean and cold SSTs in the east) like that which occurred in 1994 lead to elevated Congo River discharge and subsequently lower eastern tropical Atlantic sea surface salinity.  However, it has not been previously shown how these the end-to-end processes originating with IOD development can affect Benguela Niños.

We use a variety of data sets and reanalyses (both oceanic and atmospheric) to show how during the 1994 IOD event, moisture was transported through the atmosphere from the western Indian Ocean to the Congo River basin where it converged and rained out to increase Congo River discharge.  The freshwater discharge in turn was advected southward in early 1995 which resulted in formation of thin surface mixed layers atop thick barrier layers that arrested the entrainment of cold subsurface waters, thereby amplifying Benguela Nino SSTs. We further show that this sequence of events has occurred at other times, as for example during a weak 2015 IOD and subsequent 2016 Benguela Niño.  These results suggest that the significant temporal lags between IOD development, Congo River basin rainfall, river discharge, and offshore accumulation of freshwater offer opportunities for improved seasonal forecasting of Indian Ocean impacts on the Atlantic through ocean-atmosphere-land interactions.

How to cite: McPhaden, M., Jarugula, S., Aroucha, L., and Luebbecke, J.: Indian Ocean Dipole Intensifies Benguela Niño Through Congo River Discharge, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3250, https://doi.org/10.5194/egusphere-egu24-3250, 2024.

EGU24-3828 | ECS | Posters on site | OS1.3

Equatorial wave diagnosis for the Atlantic Niño with an ocean reanalysis 

Qingyang Song

There has been a long-standing need for a rapid-detection method for waves using simulation data for Atlantic Niño events. This study addresses this by utilizing an ocean reanalysis.  The proposed method firstly decomposes the climatological values and anomalies at each grid point are decomposed into the first four baroclinic modes based on their local density profiles, then the wave energy flux is calculated by means of a group-velocity-based scheme.  In the instance during the 2019 Niño event, the decomposed geopotential can well reproduce the displacement of the thermocline during the event. The obtained wave energy fluxes confirm the significant influence of subseasonal Kelvin waves on the event and also suggest that wave energy from off-equatorial regions likely preconditioned the event. This study is thus a useful tool for diagnosing the equatorial waveguide and can support the warning systems for Atlantic Niño events.

How to cite: Song, Q.: Equatorial wave diagnosis for the Atlantic Niño with an ocean reanalysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3828, https://doi.org/10.5194/egusphere-egu24-3828, 2024.

EGU24-6857 | ECS | Orals | OS1.3

Seasonality of Mixing at Tropical Instability Wave Fronts in the Atlantic Ocean  

Mia Sophie Specht, Johann Jungclaus, and Jürgen Bader

Tropical Instability Waves (TIWs) in both Pacific and Atlantic Ocean have been shown to play a role in modulating upper ocean mixing. However, previous studies on the modulation of TIW related mixing are based on small numbers of TIWs. These approaches do not allow for the consideration of temporal variability, which can lead to discrepancies in the findings. In this study, we analyze 12-years of simulation output from the comprehensive, global, high-resolution ocean model ICON, to show for the first time that deep reaching mixing at TIW fronts in the Atlantic Ocean follows a distinct seasonal cycle. We find that, regardless of whether TIWs are present earlier in the year, mixing primarily occurs in boreal summer when the vertical shear of the mean zonal currents also reaches its maximum. Our results suggest that in the Atlantic Ocean, shear at the TIW fronts related to the wave itself is generally not large enough to trigger deep reaching mixing. Instead, the background shear in addition to the TIW related shear also needs to be sufficiently large to generate mixing. This additional background shear is strongly modulated by the seasonality of the South Equatorial Current (SEC). Hence, the SEC and its temporal variability contribute to the generation and modulation of deep reaching mixing at TIW fronts in the Atlantic Ocean.

How to cite: Specht, M. S., Jungclaus, J., and Bader, J.: Seasonality of Mixing at Tropical Instability Wave Fronts in the Atlantic Ocean , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6857, https://doi.org/10.5194/egusphere-egu24-6857, 2024.

EGU24-7178 | Orals | OS1.3 | Highlight

Winter Convective Mixing Mediating Coupling of N-gain and -loss in the Arabian Sea 

Arvind Singh, Himanshu Saxena, Deepika Sahoo, Sipai Nazirahmed, Niharika Sharma, Deepak Kumar Rai, and Sanjeev Kumar

Marine dinitrogen (N2) fixation fuels primary production and thereby influences the Earth’s climate. Yet, its geographical distribution and controlling environmental parameters remain debatable. We measured N2 fixation rates from the two spatially and physicochemically contrasting regions of the Arabian Sea during the winter monsoon: (a) the colder and nutrient-rich waters in the northern region owing to winter convection and (b) the warmer and nutrient-poor waters in the southern region unaffected by winter convection. We found higher N2 fixation rates at the surface of northern region due to convective mixing driven supply of phosphate (intuitively iron also) from the underlying suboxic waters, whereas the lower rates in the southern region are attributable to the limited supply of iron. N2 fixation was favoured by high nutrients concentration in the euphotic waters, whereas remained unaffected by nutrients availability in the aphotic waters. We conclude that diazotrophs dwelling in the euphotic zone chose phosphate and iron over fixed nitrogen-poor waters. However, we found that among oligotrophic waters, anticyclonic eddy extremes the barrier of fixed nitrogen supply and thereby elevates N2 fixation. While the Arabian Sea loses about 20 to 40% of the global ocean fixed nitrogen, we estimate that N2 fixation in the Arabian Sea offsets only up to 42% of its fixed nitrogen-loss by denitrification, but this offset could be higher if diazotrophic activity is further examined up to the deeper depths of the Arabian Sea.

How to cite: Singh, A., Saxena, H., Sahoo, D., Nazirahmed, S., Sharma, N., Rai, D. K., and Kumar, S.: Winter Convective Mixing Mediating Coupling of N-gain and -loss in the Arabian Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7178, https://doi.org/10.5194/egusphere-egu24-7178, 2024.

EGU24-7353 | ECS | Orals | OS1.3

Mechanisms of the Indian Ocean surface warming pattern in CMIP5 and 6 models 

Gopika Suresh, Sadhvi Kwatra, Jérôme Vialard, Vincent Danielli, Neetu Suresh, and Matthieu Lengaigne

The latest assessment report of the Intergovernmental Panel on Climate Change highlights an accelerated warming of the Indian Ocean (IO) compared to the global average. Coupled Model Intercomparison Project Phase 5 and 6 (CMIP5/6) projections also indicate a distinct warming pattern, reminiscent of the Indian Ocean Dipole (IOD), characterized by enhanced warming in the Arabian Sea and western Indian Ocean alongside a reduction in the IO branch of the Walker Cell. This study uses an SST heat budget adapted from Zhang and Li (2014, hereafter ZL14) across 46 CMIP5/6 simulations, to examine the drivers of the IO mean warming and its spatial distribution, for both the multi-model mean (MMM) and inter-model diversity.

Differing from the prior ZL14 approach, this study incorporates feedback related to downward longwave heat fluxes. While ZL14 highlighted downward longwave fluxes as the main driver of the IO average warming, our results reveal a dominant role of latent heat flux changes for both the MMM and diversity. These changes are further related to a basin-scale wind speed reduction, linked to the winter monsoon & IO Walker cell branch weakening.

Regarding the spatial pattern, our results emphasize a key role in the Bjerknes feedback in driving the IOD-like pattern for both the MMM and inter-model diversity. There is indeed a strong relationship across models between the IOD-like warming pattern, rainfall increase over the western IO, weakened equatorial easterlies, an east-west dipole in thermocline anomalies and the contribution of oceanic processes to surface warming. In the Arabian Sea, the enhanced warming is controlled by a seasonally varying balance, with the evaporative cooling feedback dominating during spring and summer when upwellings are strong, and the wind speed reduction associated with the winter monsoon weakening dominating later in the year.

Overall, these results call for more comprehensive process-oriented studies with more sophisticated approaches (ocean or coupled model sensitivity experiments) to unravel the IO warming mechanisms.

Keywords: Indian Ocean warming, Air-Sea Interaction, IOD-like warming, Walker cell weakening, Arabian sea warming, Coupled model intercomparison project (CMIP)

How to cite: Suresh, G., Kwatra, S., Vialard, J., Danielli, V., Suresh, N., and Lengaigne, M.: Mechanisms of the Indian Ocean surface warming pattern in CMIP5 and 6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7353, https://doi.org/10.5194/egusphere-egu24-7353, 2024.

EGU24-8544 | Posters on site | OS1.3

Changes in the Variability and Teleconnections of the Northeastern Tropical Atlantic Upwelling Region around 2000 

Joke Lübbecke, Belén Rodríguez-Fonseca, Marta Martin-Rey, Teresa Losada, Elsa Mohino, and Irene Polo

Sea Surface Temperatures (SST) in the Northeastern Tropical Atlantic upwelling region off Senegal and Mauritania feature pronounced variability on interannual time scales with impacts on the marine ecosystem. While part of this variability results from wind stress and wind stress curl-driven changes in local upwelling, the roles of air-sea heat fluxes, horizontal advection and potentially remotely forced thermocline variations have also been discussed. Here the relative roles of these forcing mechanisms and how they change over the time period from 1958 to 2020 are investigated utilizing reanalysis products as well as output from a general ocean circulation model (NEMO) forced by the atmospheric JRA55-do forcing. In the configuration analyzed (VIKING20X), oceanic resolution is increased to 1/20º over the Northern Atlantic via a two-way nesting approach, allowing for a better representation of the near-coastal upwelling region.

Interestingly, while interannual SST variability in the eastern equatorial Atlantic and the Angola Benguela region has decreased since 2000 and is projected to further decrease in the future, there is an increase of SST variability in the Northeastern Tropical Atlantic. To understand this increase, we address the roles of changes in local wind forcing and the connection to the equatorial region via the propagation of equatorial and coastal trapped waves. Along with the altered SST variability, teleconnection patterns related the Northeastern Tropical Atlantic, in particular with the El Niño – Southern Oscillation, also changed.    

How to cite: Lübbecke, J., Rodríguez-Fonseca, B., Martin-Rey, M., Losada, T., Mohino, E., and Polo, I.: Changes in the Variability and Teleconnections of the Northeastern Tropical Atlantic Upwelling Region around 2000, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8544, https://doi.org/10.5194/egusphere-egu24-8544, 2024.

EGU24-8829 | ECS | Orals | OS1.3

An assessment of equatorial Atlantic interannual variability in OMIP simulations 

Arthur Prigent and Riccardo Farneti

The eastern equatorial Atlantic (EEA) seasonal cycle and interannual variability of the sea surface temperature strongly influence the climate of the surrounding continents. It is thus crucial that models used in both climate predictions and future climate projections are able to simulate them accurately. In that context, the EEA seasonal cycle and interannual variability are evaluated over the period 1985-2004 in models participating to the Ocean Model Intercomparison Project Phases 1 and 2 (OMIP1 and OMIP2). The main difference between OMIP1 and OMIP2 simulations is their atmospheric forcing: CORE-II and JRA55-do, respectively. Seasonal cycles of the equatorial Atlantic zonal winds, sea level anomaly and sea surface temper- ature in OMIP1 and OMIP2 are comparable to reanalysis datasets. Yet, some discrepancies exist in both OMIP ensembles: the thermocline is too diffusive and there is a lack of cooling during the development of the Atlantic cold tongue. In addition, the vertical ocean velocity in the eastern equatorial Atlantic in boreal summer is larger in OMIP1 than in OMIP2 simulations. The EEA interannual sea surface temperature variability in the OMIP1 ensemble mean is found to be 51% larger (0.62 ± 0.04 ˚C) than the OMIP2 ensemble mean (0.41 ± 0.03 ˚C). Sensitivity experiments demonstrate that the discrepancy in interannual sea surface temperature variability between OMIP1 and OMIP2 is mainly attributed to their wind forcing. While the April-May- June zonal wind variability in the western equatorial Atlantic is similar in both forcing, the zonal wind variability peaks in April for JRA55-do and in May for CORE-II. Differences in surface heat fluxes between the two atmospheric forcing datasets have no significant impacts on the simulated interannual SST variability.

How to cite: Prigent, A. and Farneti, R.: An assessment of equatorial Atlantic interannual variability in OMIP simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8829, https://doi.org/10.5194/egusphere-egu24-8829, 2024.

EGU24-10500 | ECS | Posters on site | OS1.3

Decadal Variability of the Indonesian Throughflow’s Vertical Structure and the Impact on Heat and Salinity Transport 

Daniel Waitzmann, Shouyi Wang, Delia W. Oppo, and Caroline C. Ummenhofer

The Indonesian Throughflow, a low-latitude passage of the global conveyor belt, transfers water from the tropical Pacific to the Indian Ocean, modulating the properties of both oceans. Observational and modelling studies have shown that the interannual and decadal variability of the Indonesian Throughflow is closely linked to the leading climate modes of the tropical Pacific, namely the El Niño Southern Oscillation and the Interdecadal Pacific Oscillation; further, it is modulated by variability in the Indian Ocean, especially in the outflow region. The Indonesian Throughflow volume transport variability affects salinity and temperature transport and ocean-atmosphere exchange in the Indo-Pacific warm pool. The Makassar Strait transport represents about 80% of the total Indonesian Throughflow transport and is, therefore, a good proxy for the Indonesian Throughflow transport. Observations from the Indonesian Seas have been used to explain the variability on seasonal to interannual time scales. However, due to the lack of long observational time series in the region, assessing the variability and driving mechanisms on longer time scales is challenging. Here, we use transient runs of a high-resolution coupled ocean-atmosphere model to address the decadal variability of the Indonesian Throughflow and its change under global warming over the time period 1850-2102. We assess how heat content, salinity, and volume transport in the Makassar Strait region change on these timescales and how they contribute to the heat and freshwater transport changes. In addition, we investigate the vertical structure of the Indonesian Throughflow variability and its driving mechanisms. This involves understanding how Indonesian Throughflow variability is connected more broadly to large-scale conditions in the Pacific and Indian Oceans. The results presented here may motivate further analysis using multiple simulations of the high-resolution model configurations conducted as part of HighResMIP to assess the forced changes to the Indonesian Throughflow under RCP8.5 forcing in a highly dynamic ocean region that plays a pivotal role in global heat and freshwater transport.

How to cite: Waitzmann, D., Wang, S., Oppo, D. W., and Ummenhofer, C. C.: Decadal Variability of the Indonesian Throughflow’s Vertical Structure and the Impact on Heat and Salinity Transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10500, https://doi.org/10.5194/egusphere-egu24-10500, 2024.

EGU24-12377 | Posters on site | OS1.3 | Highlight

Developing a 3.5-million-year benchmark record of Indian Ocean Dipole variability  

Stefanie Kaboth-Bahr, Oliver Kern, and André Bahr

The Indian Ocean Dipole (IOD) is the primary mode of interannual sea surface temperature variability (SST) in the tropical Indian Ocean. The climatic effects of the IOD are diverse and geographically widespread. Extreme flood events in eastern Africa, weakened summer monsoon intensity over India and Southeast Asia, and severe droughts in Australia are among the most significant societal consequences of IOD variability. These extreme climate events caused by the IOD are predicted to become more common as greenhouse gas emissions increase. However, despite its significance, surprisingly little is known about IOD variability during the geological past, which would allow for a better assessment of its sensitivity to atmospheric CO2 level changes in the future. This study presents the first insights into the spatio-temporal complexity of the IOD over the past 3.5 million years. We utilize geochemical proxy data (XRF core scanning, stable oxygen, and carbon isotopes, as well as Mg/Ca paleothermometry of planktonic foraminifera) derived from Site ODP 709, situated in the western equatorial Indian Ocean - a critical region for IOD forcing.

How to cite: Kaboth-Bahr, S., Kern, O., and Bahr, A.: Developing a 3.5-million-year benchmark record of Indian Ocean Dipole variability , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12377, https://doi.org/10.5194/egusphere-egu24-12377, 2024.

EGU24-14029 | Orals | OS1.3

Exploring 6-month lead predictability of the Atlantic zonal mode in CMIP6 

Ingo Richter, Tomoki Tozuka, Yu Kosaka, Shoichiro Kido, and Hiroki Tokinaga

Skillful prediction of the equatorial Atlantic zonal mode (AZM) remains challenging, with many prediction systems dropping below an anomaly correlation coefficient (ACC) of 0.5 beyond a lead time of 3 months. Since the El Niño-Southern Oscillation (ENSO) is well known to have global impacts, it could be expect to be a useful predictor of the AZM but its influence on the adjacent equatorial Atlantic basin is inconsistent. This is perhaps best exemplified by the fact that the extreme 1982 and 1997 El Niño events were followed by Atlantic zonal mode (AZM) events of the opposite sign.

Here we re-examine the potential role of ENSO in the predictability of the AZM using pre-industrial control simulations (piControl) from the Coupled Model Intercomparison Phase 6 (CMIP6). The observed correlation between boreal winter (DJF) sea-surface temperature (SST) in the Niño 3.4 region and the following summer (JJA) SSTs in the ATL3 region is close to zero, indicative of the inconsistent relation between the two. Individual models, however, exhibit a wide range of behaviors with correlations ranging from about -0.5 to +0.5. While the influence of ENSO on equatorial Atlantic SST is inconsistent, the influence of ENSO on surface winds over the equatorial Atlantic is rather robust. All models show a negative correlation between DJF Niño 3.4 SST and boreal spring (MAM) surface winds over the western equatorial Atlantic. In addition, we find that SSTs in the South Atlantic act as a precursor to AZM events. Based on these relations, we construct a multi-linear regression model to predict AZM events in JJA based on Pacific and Atlantic SST in DJF. In most climate models, this simple scheme can predict AZM events with an ACC above 0.5 during ENSO years. We will discuss to what extent these insights may help in the prediction of real-world AZM events.

How to cite: Richter, I., Tozuka, T., Kosaka, Y., Kido, S., and Tokinaga, H.: Exploring 6-month lead predictability of the Atlantic zonal mode in CMIP6, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14029, https://doi.org/10.5194/egusphere-egu24-14029, 2024.

EGU24-14272 | ECS | Orals | OS1.3

Anomalous Seawater Radiocarbon Depletion Event during Glacial Interval in the Equatorial Indian Ocean Thermocline 

Sanjit Kumar Jena, Ravi Bhushan, Partha Sarathi Jena, Nisha Bharti, Sudheer Athiyarath Krishnan, Ajay Shivam, and Ankur Dabhi

The role of intermediate water mass in ocean circulation is well acknowledged from the global oceanographic and climatic perspectives. Abnormal depletions in the upper oceanic radiocarbon concentrations during the last deglaciation have been attributed to the southern ocean sourced aged CO2 ventilations via Antarctic intermediate waters. However, the fundamental origin and nature of the source, and its spatio-temporal variability still remains a question.

The present study reconstructs the radiocarbon records of the upper Equatorial Indian Ocean (EIO) over the last 44 ka using the radiocarbon dating of depth-specific planktonic foraminifers. The results reveal an extremely depleted radiocarbon interval in the EIO thermocline between 25-34 ka during the Marine Isotopic Stage 3 – Marine Isotopic Stage 2 (MIS3-MIS2) transition. The Reunion hotspot and/or the Amsterdam Island appear to be the responsible source(s) of contemporaneous hydrothermal dead carbon supply into the EIO thermocline. However, the deglacial thermocline radiocarbon depletions were primarily caused by the southern ocean sourced aged CO2 ventilations only. The radiocarbon records also indicate a well stratified upper oceanic condition prevailing over the EIO during the last 44 ka.

How to cite: Jena, S. K., Bhushan, R., Jena, P. S., Bharti, N., Athiyarath Krishnan, S., Shivam, A., and Dabhi, A.: Anomalous Seawater Radiocarbon Depletion Event during Glacial Interval in the Equatorial Indian Ocean Thermocline, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14272, https://doi.org/10.5194/egusphere-egu24-14272, 2024.

EGU24-14616 | ECS | Posters on site | OS1.3

Volcanic ash likely triggers N2 fixation in the Andaman Sea  

Himanshu Saxena, Deepika Sahoo, Ajayeta Rathi, Sipai Nazirahmed, Sanjeev Kumar, and Arvind Singh

Marine N2 fixation fuels the growth of primary producers, drives marine carbon export fluxes, and in turn, influence the Earth’s climate. While the Bay of Bengal is at least explored, the Andaman Sea, which is adjacent to the only active volcano of the south Asia and is separated from the Bay of Bengal by the Andaman and the Nicobar Islands to its west, has never been explored for its viability to N2 fixation. The warm and oligotrophic surface waters and suboxic subsurface waters of these two basins may provide suitable stimulus for N2 fixation. We investigated N2 fixation in the euphotic and the oxygen minimum zones of the Bay of Bengal and the Andaman Sea during the autumn inter-monsoon. We found that N2 fixation is about an order of magnitude higher in the surface waters of the Andaman Sea than the Bay of Bengal, attributable to the relatively high iron input associated with volcanic ash deposition in the Andaman Sea. We underscored that N2 fixation at the immediate sea surface (sampled manually through a bucket) is largely four times higher than the subsurface waters at 10 m depth (sampled through CTD) in the northeastern Indian Ocean. Our findings imply that the traditional CTD rosette sampling is unable to capture the surface N2 fixation activity, and therefore, previously reported N2 fixation rates in the global ocean are likely to be massively underestimated.

How to cite: Saxena, H., Sahoo, D., Rathi, A., Nazirahmed, S., Kumar, S., and Singh, A.: Volcanic ash likely triggers N2 fixation in the Andaman Sea , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14616, https://doi.org/10.5194/egusphere-egu24-14616, 2024.

EGU24-15235 | ECS | Posters on site | OS1.3

Bayesian optimization of ocean mixed layer parameterizations 

Marta Mrozowska, Markus Jochum, James Avery, Ida Stoustrup, and Roman Nuterman

Global climate is highly sensitive to tropical sea surface temperature. Accurately representing the tropical SST remains a significant challenge for general circulation and climate models. One of the largest sources of uncertainty is the vertical turbulent mixing. To accurately represent the distribution of ocean mixed layer depths, turbulence closure schemes necessitate careful tuning. This is most commonly done manually by comparing with mixed layer depth climatologies. Advancements in machine learning research introduce a new strategy: automated tuning. Veropt, an add-on to the python ocean model Veros, uses Gaussian processes to emulate an objective function in a multi-dimensional parameter space. We present a surprising combination of changes to the default parameters of the commonly used turbulent kinetic energy (TKE) closure scheme that minimise the model bias in tropical mixed layer depth.

How to cite: Mrozowska, M., Jochum, M., Avery, J., Stoustrup, I., and Nuterman, R.: Bayesian optimization of ocean mixed layer parameterizations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15235, https://doi.org/10.5194/egusphere-egu24-15235, 2024.

EGU24-17728 | ECS | Orals | OS1.3

Merging Process of the Great Whirl and the Socotra Gyre in 2019 

Lingxing Dai, Xingwei Jiang, Yifan Xia, Minyang Wang, Shilin Tang, and Yan Du

The Great Whirl (GW) and the Socotra Gyre (SoG), two prominent anticyclonic eddies in the western Arabian Sea, exhibit strong dynamic interactions. This study reports a case of the merging of the GW and the SoG recorded by Argo floats in September 2019. Combined with satellite observations and a state-of-the-art ocean reanalysis, we show that the merging process was first detected at the subsurface layer (~150 m depth) rather than the surface. As the original water inside the GW is cooler than the SoG, the merging created a baroclinic structure between the eddies. The density gradients associated with the baroclinic structure drive strong subsurface geostrophic currents following the thermal wind relationship, leading to the fast merging at 100-200 m depth. Energy analysis shows that the predominant energy source for the merged eddy was the barotropic and baroclinic instability. The dissipative processes caused the rapid decay of the merged eddy. The merging process induced sub-mesoscale activities and promoted ocean vertical exchanges south of Socotra Island.

How to cite: Dai, L., Jiang, X., Xia, Y., Wang, M., Tang, S., and Du, Y.: Merging Process of the Great Whirl and the Socotra Gyre in 2019, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17728, https://doi.org/10.5194/egusphere-egu24-17728, 2024.

The tropical Indian Ocean presents a distinctive opportunity to investigate monsoon-induced changes in primary productivity and ocean hydrography. Planktic foraminifera, with their unique ecological preferences, are well-suited for reconstructing past environmental conditions. Different species of planktic foraminifera exhibit varied responses to changes in the physico-chemical parameters of the ambient water. This study presents a high-resolution planktic foraminiferal assemblage from the marine sediment core SSD004 GC03 for the last 24,000 years from the tropical Indian Ocean. The record includes 24 planktic foraminifera species with G. bulloides, G. glutinata, G. ruber, G. sacculifer, N. dutertrei and G. menardii  being the most abundant. The species are categorized into eutrophic, oligotrophic, mixed layer, and thermocline assemblages. Notably, during the last glacial maximum (LGM; 19.0-23.0 ka), a significant abundance of mixed layer assemblage is observed between 21.0-19.0 kyr. Heinrich stadial 1 (~15.0-18.0 ka) and the Younger Dryas (~11.-12.9 ka) periods exhibit a lower mixed layer assemblage and a higher thermocline assemblage. The Bølling-Allerød (~12.9-15.0 ka) period is characterized by a sudden increase in mixed-layer assemblages. The abundance of eutrophic species G. bulloides and G. glutinata during the LGM and Holocene indicates increased surface productivity influenced by the Northeast Monsoon and the strong Southwest Monsoon, respectively. The results underscore the unique and intricate dynamics of the studied region, primarily influenced by both the southwest and northeast monsoons.

How to cite: Rai, S. and Singh, D. P.: Planktic foraminifera reflects surface productivity and hydrographic changes in the tropical Indian Ocean during the last 24,000 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17818, https://doi.org/10.5194/egusphere-egu24-17818, 2024.

EGU24-17832 | ECS | Posters on site | OS1.3

The Atlantic sibling: a reconciling vision on the nature of El Niño’s “little brother”  

Cosimo Enrico Carniel, Gian Luca Borzelli, Aniello Russo, and Sandro Carniel

The Atlantic Niño, also referred to as Atlantic zonal mode, equatorial Atlantic mode or, sometimes, El Niño’s little brother, is an important source of the year-to-year variability of the tropical Atlantic, consisting in an irregular oscillation of the Sea Surface Temperature (SST) in the eastern part of the basin. The physical mechanism underlying the activation of the oscillation is a matter of debate; some theories, termed dynamical, explain the Atlantic Niño as an ENSO-like phenomenon initiated by internal waves excited by the relaxation of easterly winds in the western tropical Atlantic and/or by the reflection of Rossby waves impinging the western Atlantic boundary. Some other theories, called thermodynamic, attribute the eastern tropical Atlantic SST variability to thermodynamic processes induced by off equatorial heat fluxes. Here, by using Sea Surface Height (SSH) data provided by orbiting altimeters and heat fluxes deduced from horizontal currents and Temperature-Salinity (TS) profiles provided by the Copernicus project, we show that, at least in the period Jan 1993-Dec 2021, both mechanisms were active and two sub-periods can be identified: the first, between Jan 1993 and Dec 2009, in which the eastern tropical Atlantic temperature variability can be explained reasonably well in terms of heat advected from the south by horizontal currents and, another period, between Jan 2010 and Dec 2021, in which the temperature variability of the eastern tropical Atlantic is explained by displacements of the thermocline induced by internal Kelvin waves propagating along the equatorial wave-guide. Finally, by using daily SST anomaly data over the period Jan 1940-Dec 2022, we show that the SST variability in the eastern tropical Atlantic and in the Angola-Benguela upwelling region are well correlated with each other with a lag slightly lower than a month and the SST in the Angola-Benguela region leading, suggesting a positive feedback between off equatorial heat availability and increasing SST in the eastern tropical Atlantic.

How to cite: Carniel, C. E., Borzelli, G. L., Russo, A., and Carniel, S.: The Atlantic sibling: a reconciling vision on the nature of El Niño’s “little brother” , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17832, https://doi.org/10.5194/egusphere-egu24-17832, 2024.

EGU24-19767 | Orals | OS1.3 | Highlight

Impact of the Atlantic Niño on California Ecosystem predictability 

Belen Rodríguez-Fonseca, Mercedes Pozo, Jerome Fiechter, Steven Bograd, and Mike Jacox

The Atlantic Niño is the dominant mode of sea surface temperature variability in the tropical Atlantic at interannual time scales. In the last decades this mode of variability has been identified as a driver of the Pacific Niño, increasing its predictability. The mechanism involved in the relation between the Atlantic Niño and ENSO is through the modification of the Walker Cell, altering surface winds in the western Pacific and triggering oceanic kelvin waves. These kelvin waves propagate to the east in the equatorial Pacific and along the north and South American coasts, altering the structure of the water column. The impact of this teleconnection on eastern boundary current upwelling systems has not been analyzed so far. This work demonstrates, for the first time, the impact of the Atlantic Niño on physical and biogeochemical processes in the California Current ecosystem, by the alteration of wind-driven coastal upwelling and the modification of upwelled source water properties. The mechanism relates an Atlantic Niño with enhanced production due to the uplifting of isopycnals, which that supplies more nutrients to the euphotic zone and enhances primary production and subsequent vertical export and remineralization at depth. In addition, statistical prediction is performed, indicating strong predictability of California Current biogeochemical variability from the equatorial Atlantic anomalous SSTs more than one year ahead.

 

How to cite: Rodríguez-Fonseca, B., Pozo, M., Fiechter, J., Bograd, S., and Jacox, M.: Impact of the Atlantic Niño on California Ecosystem predictability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19767, https://doi.org/10.5194/egusphere-egu24-19767, 2024.

EGU24-1857 | Orals | ESSI2.9

A Replicable Multi-Cloud Automation Architecture for Earth Observation 

Armagan Karatosun, Claudio Pisa, Tolga Kaprol, Vasileios Baousis, and Mohanad Albughdadi

The EO4EU project aims at making the access and use of Earth Observation (EO) data easier for environmental, government and business forecasts and operations.

To reach this goal, the EO4EU Platform will soon be made officially available, leveraging existing EO data sources such as DestinE, GEOSS, INSPIRE, Copernicus and Galileo, and offering advanced tools and services, based also on machine learning techniques, to help users find, access and handle the data they are interested in. The EO4EU Platform relies on a combination of a multi-cloud computing infrastructure coupled with pre-exascale high-performance computing facilities to manage demanding processing workloads.

The EO4EU multi-cloud infrastructure is composed by IaaS resources hosted on the WEkEO and CINECA Ada clouds, leveraged by a set of Kubernetes clusters dedicated to different workloads (e.g. cluster management tools, observability, or specific applications such as an inference server). To automate the deployment and management of these clusters, with advantages in terms of minimisation of dedicated effort and human errors, we have devised an Infrastructure-as-Code (IaC) architecture based on the Terraform, Rancher and Ansible technologies.

We believe that the proposed IaC architecture, based on open-source components and extensively documented and tested on the field, can be successfully replicated by other EO initiatives leveraging cloud infrastructures.

How to cite: Karatosun, A., Pisa, C., Kaprol, T., Baousis, V., and Albughdadi, M.: A Replicable Multi-Cloud Automation Architecture for Earth Observation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1857, https://doi.org/10.5194/egusphere-egu24-1857, 2024.

EGU24-6216 | Posters on site | ESSI2.9

Pangeo environment in Galaxy Earth System supported by Fair-Ease 

Thierry Carval, Marie Jossé, and Jérôme Detoc

The Earth System is a complex and dynamic system that encompasses the interactions between the atmosphere, oceans, land, and biosphere. Understanding and analyzing data from the Earth System Model (ESM) is essential, for example to predict and mitigate the impacts of climate change.

Today, collaborative efforts among scientists across diverse fields are increasingly urgent. The FAIR-EASE project aims to build an interdomain digital architecture for integrated and collaborative use of environmental data. Galaxy is a main component of this architecture which will be used by several domains of study chose by FAIR-EASE.

Galaxy, an open-source web platform, provides users with an easy and FAIR tool to access and handle multidisciplinary environmental data. By design, Galaxy manages data analyses by sharing and publishing all involved items like inputs, results, workflows, and visualisations, ensuring reproducibility by capturing the necessary information to repeat and understand data analyses.

From this point on, a Pangeo environment is a tool more than relevant to be used alongside earth-system related data and processing tools in order to create cross domain analyses. The good news is that a Pangeo environment is accessible on Galaxy. It can be exploited as a jupyterlab and allows the user to manage their NetCDF data in a Pangeo environment with the use of notebooks. Multiple tutorials are available on the Galaxy Training Network to learn how to use Pangeo.

The Galaxy Training Network significantly contributes to enhancing the accessibility and reusability of tools and workflows. The Galaxy Training platform hosts an extensive collection of tutorials. These tutorials serve as valuable resources for individuals seeking to learn how to navigate Galaxy, employ specific functionalities like Interactive Tools or how to execute workflows for specific analyses.

In synthetisis, Pangeo in Galaxy provide Pangeo users with an up-to-date data analysis platform ensuring reproducibility and mixing trainings and tools.

On the Earth System side, a first step was the creation of a Galaxy declination for Earth System studies (earth-system.usegalaxy.eu) with dedicated data, models, processing, visualisations and tutorials. It will make Earth System modeling more accessible to researchers in different fields.

In this Galaxy subdomain we choose to have the Pangeo tools. Our hope is to be able to implement cross domain workflows including climate and earth system sciences.

During this session our aim is to present how you can use the Pangeo environment from the Galaxy Earth System.

How to cite: Carval, T., Jossé, M., and Detoc, J.: Pangeo environment in Galaxy Earth System supported by Fair-Ease, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6216, https://doi.org/10.5194/egusphere-egu24-6216, 2024.

EGU24-7765 | Orals | ESSI2.9

Unleashing the power of Dask with a high-throughput Trust Region Reflectance solver for raster datacubes 

Bernhard Raml, Raphael Quast, Martin Schobben, Christoph Reimer, and Wolfgang Wagner

In remote sensing applications, the ability to efficiently fit models to vast amounts of observational data is vital for deriving high-quality data products, as well as accelerating research and development. Addressing this challenge, we developed a high-performance non-linear Trust Region Reflectance solver specialised for datacubes, by integrating Python's interoperability with C++ and Dask's distributed computing capabilities. Our solution achieves high throughput both locally and potentially on any Dask-compatible backend, such as EODC's Dask Gateway. The Dask framework takes care of chunking the datacube, and streaming each chunk efficiently to available workers where our specialised solver is applied. Introducing Dask for distributed computing enables our algorithm to run on different compatible backends. This approach not only broadens operational flexibility, but also allows us to focus on enhancing the algorithm's efficiency, free from concerns about concurrency. This enabled us to implement a highly efficient solver in C++, which is optimised to run on a single core, but still utilise all available resources effectively. For the heavy lifting, such as performing singular value decompositions and matrix operations we rely on Eigen, a powerful open-source C++ library specialized on linear algebra. To describe the spatial reference and other auxiliary data associated with our datacube, we employ the Xarray framework. Importantly, Xarray integrates seamlessly with Dask. Finally, to ensure robustness and extensibility of our framework, we applied state-of-the-art software engineering practices, including Continuous Integration and Test-Driven Development. In our work we demonstrate the significant performance gains achievable by effectively utilising available open-source frameworks, and adhering to best engineering practices. This is exemplified by our practical workflow demonstration to fit a soil moisture estimation model. 

How to cite: Raml, B., Quast, R., Schobben, M., Reimer, C., and Wagner, W.: Unleashing the power of Dask with a high-throughput Trust Region Reflectance solver for raster datacubes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7765, https://doi.org/10.5194/egusphere-egu24-7765, 2024.

The Earth System Grid Federation (ESGF) data nodes are usually the first address for accessing climate model datasets from WCRP-CMIP activities. It is currently hosting different datasets in several projects, e.g., CMIP6, CORDEX, Input4MIPs or Obs4MIPs. Datasets are usually hosted on different data nodes all over the world while data access is managed by any of the ESGF web portals through a web-based GUI or the ESGF Search RESTful API. The ESGF data nodes provide different access methods, e.g., https, OPeNDAP or Globus. 

Beyond ESGF, there has been the Pangeo / ESGF Cloud Data Working Group that coordinates efforts related to storing and cataloging CMIP data in the cloud, e.g., in the Google cloud and in the Amazon Web Services Simple Storage Service (S3) where a large part of the WCRP-CMIP6 ensemble of global climate simulations is now available in analysis-ready cloud-optimized (ARCO) zarr format. The availibility in the cloud has significantly lowered the barrier for users with limited resources and no access to an HPC environment to work with CMIP6 datasets and at the same time increases the chance for reproducibility and reusability of scientific results. 

Following the Pangeo strategy, we have adapted parts of the Pangeo Forge software stack for publishing our regional climate model datasets from the EURO-CORDEX initiative on AWS S3 cloud storage. The main tools involved are Xarray, Dask, Zarr, Intake and the ETL tools of pangeo-forge-recipes. Thanks to similar meta data conventions in comparison to the global CMIP6 datasets, the workflows require only minor adaptations. In this talk, we will show the strategy and workflow implemented and orchestrated in GitHub Actions workflows as well as a demonstration of how to access EURO-CORDEX datasets in the cloud.

How to cite: Buntemeyer, L.: Beyond ESGF – Bringing regional climate model datasets to the cloud on AWS S3 using the Pangeo Forge ETL framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8058, https://doi.org/10.5194/egusphere-egu24-8058, 2024.

EGU24-8343 | ECS | Posters on site | ESSI2.9 | Highlight

Implementation of a reproducible pipeline for producing seasonal Arctic sea ice forecasts 

Vanessa Stöckl, Björn Grüning, Anne Fouilloux, Jean Iaquinta, and Alejandro Coca-Castro

This work highlights the integration of IceNet (https://doi.org/10.1038/s41467-021-25257-4), a cutting-edge sea ice forecasting system leveraging numerous Python packages from the Pangeo ecosystem, into the Galaxy platform—an open-source tool designed for FAIR (Findable, Accessible, Interoperable, and Reusable) data analysis. Aligned with the Pangeo ecosystem's broader objectives, and carried out in the frame of the EuroScienceGateway project (https://eurosciencegateway.eu), this initiative embraces a collaborative approach to tackle significant geoscience data challenges. The primary aim is to democratise access to IceNet's capabilities by converting a Jupyter Notebook, published in the Environmental Data Science book (www.edsbook.org), into Galaxy Tools and crafting a reusable workflow executable through a Graphical User Interface or standardised APIs. IceNet is meant to predict Arctic sea ice concentration up to six months in advance, and it outperforms previous systems. This integration establishes a fully reproducible workflow, enabling scientists with diverse computational expertise to automate sea ice predictions. The IceNet workflow is hosted on the European Galaxy Server (https://climate.usegalaxy.eu), along with the related tools, ensuring accessibility for a wide community of researchers. With the urgency of accurate predictions amid global warming's impact on Arctic sea ice, this work addresses challenges faced by scientists, particularly those with limited programming experience. The transparent, accessible, and reproducible pipeline for Arctic sea ice forecasting aligns with Open and Science principles. The integrated IceNet into Galaxy enhances accessibility to advanced climate science tools, allowing for automated predictions that contribute to early and precise identification of potential damages from sea ice loss. This initiative mirrors the overarching goals of the Pangeo community, advancing transparent, accessible, and reproducible research. The Galaxy-based pipeline presented serves as a testament to collaborative efforts within the Pangeo community, breaking down barriers related to computational literacy and empowering a diverse range of scientists to contribute to climate science research. The integration of IceNet into Galaxy not only provides a valuable tool for seasonal sea ice predictions but also exemplifies the potential for broad interdisciplinary collaboration within the Pangeo ecosystem.

How to cite: Stöckl, V., Grüning, B., Fouilloux, A., Iaquinta, J., and Coca-Castro, A.: Implementation of a reproducible pipeline for producing seasonal Arctic sea ice forecasts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8343, https://doi.org/10.5194/egusphere-egu24-8343, 2024.

EGU24-9156 | ECS | Orals | ESSI2.9

DataLabs: development of a cloud collaborative platform for open interdisciplinary geo-environmental sciences  

Michael Tso, Michael Hollaway, Faiza Samreen, Iain Walmsley, Matthew Fry, John Watkins, and Gordon Blair

In environmental science, scientists and practitioners are increasingly facing the need to create data-driven solutions to the environment's grand challenges, often needing to use data from disparate sources and advanced analytical methods, as well as drawing expertise from collaborative and cross-disciplinary teams [1]. Virtual labs allow scientists to collaboratively explore large or heterogeneous datasets, develop and share methods, and communicate their results to stakeholders and decision-makers. 

DataLabs [2] has been developed as a cloud-based collaborative platform to tackle these challenges and promote open, collaborative, interdisciplinary geo-environmental sciences. It allows users to share notebooks (e.g. JupyterLab, R Studio, and most recently VS Code), datasets and computational environments and promote transparency and end-to-end reasoning of model uncertainty. It supports FAIR access to data and digital assets by providing shared data stores and discovery functionality of datasets and assets hosted on the platform’s asset catalogue. Its tailorable design allows it to be adaptable to different challenges and applications. It is also an excellent platform for large collaborative teams to work on outputs together [3] as well as communicating results to stakeholders by allowing easy prototyping and publishing of web applications (e.g. Shiny, Panel, Voila). It is currently deployed on JASMIN [4] and is part of the UK NERC Environmental data service [5]. 

There are a growing number of use cases and requirements for DataLabs and it is going to play a central part in several planned digital research infrastructure (DRI) initiatives. Future development needs of the platform to further its vision include e.g. more intuitive onboarding experience, easier access to key datasets at source, better connectivity to other cloud platforms, and better use of workflow tools. DataLabs shares many of the features (e.g. heavy use of PANGEO core packages) and design principles of PANGEO. We would be interested in exploring commonalities and differences, sharing best practices, and growing the community of practice in this increasingly important area. 

[1]  Blair, G.S., Henrys, P., Leeson, A., Watkins, J., Eastoe, E., Jarvis, S., Young, P.J., 2019. Data Science of the Natural Environment: A Research Roadmap. Front. Environ. Sci. 7. https://doi.org/10.3389/fenvs.2019.00121  

[2] Hollaway, M.J., Dean, G., Blair, G.S., Brown, M., Henrys, P.A., Watkins, J., 2020. Tackling the Challenges of 21st-Century Open Science and Beyond: A Data Science Lab Approach. Patterns 1, 100103. https://doi.org/10.1016/j.patter.2020.100103 

[3] https://eds.ukri.org/news/impacts/datalabs-streamlines-workflow-assessing-state-nature-uk  

[4] https://jasmin.ac.uk/  

[5] https://eds.ukri.org/news/impacts/datalabs-digital-collaborative-platform-tackling-environmental-science-challenges  

How to cite: Tso, M., Hollaway, M., Samreen, F., Walmsley, I., Fry, M., Watkins, J., and Blair, G.: DataLabs: development of a cloud collaborative platform for open interdisciplinary geo-environmental sciences , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9156, https://doi.org/10.5194/egusphere-egu24-9156, 2024.

EGU24-9781 | Posters on site | ESSI2.9

Optimizing NetCDF performance for cloud computing : exploring a new chunking strategy 

Flavien Gouillon, Cédric Pénard, Xavier Delaunay, and Florian Wery

Owing to the increasing number of satellites and advancements in sensor resolutions, the volume of scientific data is experiencing rapid growth. NetCDF (Network Common Data Form) stands as the community standard for storing such data, necessitating the development of efficient solutions for file storage and manipulation in this format.

Object storage, emerging with cloud infrastructures, offers potential solutions for data storage and parallel access challenges. However, NetCDF may not fully harness this technology without appropriate adjustments and fine-tuning. To optimize computing and storage resource utilization, evaluating NetCDF performance on cloud infrastructures is essential. Additionally, exploring how cloud-developed software solutions contribute to enhanced overall performance for scientific data is crucial.

Offering multiple file versions with data split into chunks tailored for each use case incurs significant storage costs. Thus, we investigate methods to read portions of compressed chunks, creating virtual sub-chunks that can be read independently. A novel approach involves indexing data within NetCDF chunks compressed with deflate, enabling extraction of smaller data portions without reading the entire chunk.

This feature is very valuable in use cases such as pixel drilling or extracting small amounts of data from large files with sizable chunks. It also saves reading time, particularly in scenarios of poor network connection, such as those encountered onboard research vessels.

We conduct performance assessments of various libraries in various use cases to provide recommendations for the most suitable and efficient library for reading NetCDF data in different situations.

Our tests involved accessing remote NetCDF datasets (two files from the SWOT mission) available on the network via a lighttpd server and an s3 server. Additionally, simulations of degraded Internet connections, featuring high latency, packet loss, and limited bandwidth, are also performed.

We evaluate the performance of four Python libraries (netcdf4 lib, Xarray, h5py, and our chunk indexing library) for reading dataset portions through fsspec or fs_s3. A comparison of reading performance using netCDF, zarr, and nczarr data formats is also conducted on an s3 server.

Preliminary findings indicate that the h5py library is the most efficient, while Xarray exhibits poor performance in reading NetCDF files. Furthermore, the NetCDF format demonstrates reasonably good performance on an s3 server, albeit lower than zarr or nczarr formats. However, the considerable efforts required to convert petabytes of archived NetCDF files and adapt numerous software libraries for a performance improvement within the same order of magnitude can raise questions about the practicality of such endeavors and benefits is thus extremely related to the use cases.

How to cite: Gouillon, F., Pénard, C., Delaunay, X., and Wery, F.: Optimizing NetCDF performance for cloud computing : exploring a new chunking strategy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9781, https://doi.org/10.5194/egusphere-egu24-9781, 2024.

EGU24-9795 | ECS | Orals | ESSI2.9

Unifying HPC and Cloud Systems; A Containerized Approach for the Integrated Forecast System (IFS) 

Cathal O'Brien, Armagan Karatosun, Adrian Hill, Paul Cresswell, Michael Sleigh, and Ioan Hadade

The IFS (Integrated Forecast System) is a global numerical weather prediction system maintained by the European Centre for Medium-Range Weather Forecasts (ECMWF). Traditionally, ECMWF’s high-performance computing facility (HPCF) is responsible for operationally supporting the IFS cycles. However, with the emergence of new cloud technologies, initiatives such as Destination Earth (DestinE), and growth of OpenIFS users within Europe and around the globe, the need to run IFS outside of ECMWF's computing facilities becomes more evident. Concerning such use cases, IFSTestsuite allows for the complete IFS system and its dependencies (e.g. ecCodes) to be built and tested outside of ECMWF's HPCF and designed to be self-contained, eliminating the need for external tools like MARS or ecCodes. Despite the need for users to perform multiple steps and the dependency of the software availability and versions on the host operating system, this indicates that there might be a potential for more generic and broader approach. 

Containerization might provide the much-needed portability and disposable environments to trigger new cycles with the desired compiler versions, or even with different compilers. In addition, pre-built container images can be executed on any platform, provided there is a compatible container runtime installed on the target system that adheres to Open Container Initiative (OCI) standards like Singularity or Docker. Another benefit of using container images is container image layers which can significantly reduce the image build time. Lastly, despite their differences, both Singularity and Docker adhere to the OCI standards, and converting one container image to another is straightforward. However, despite the clear advantages, there are several crucial design choices to keep in mind. Notably, the available hardware and software stacks varies greatly across different HPC systems. When performance is important, this heterogeneous landscape limits the portability of containers. The libraries and drivers inside the container must be specially selected with regard to the hardware and software stack of a specific host system to maximize performance on that system. If this is done correctly, the performance of containerized HPC applications can match native applications. We demonstrate this process with the use of a hybrid containerization strategy where compatible MPI stacks and drivers are built inside the containers. The binding of host libraries into containers is also used on systems where proprietary software cannot be rebuilt inside the container.  

In this study we present a containerized solution which balances portability and efficient performance, with examples of containerizing the IFS on a variety of systems including cloud systems with generic x86-64 architecture, such as European Weather Cloud (EWC) and Microsoft Azure, on EuroHPC systems such as Leonardo and LUMI and provided container image recipes for OpenIFS. 

How to cite: O'Brien, C., Karatosun, A., Hill, A., Cresswell, P., Sleigh, M., and Hadade, I.: Unifying HPC and Cloud Systems; A Containerized Approach for the Integrated Forecast System (IFS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9795, https://doi.org/10.5194/egusphere-egu24-9795, 2024.

EGU24-10741 | Posters on site | ESSI2.9

Harnessing the Pangeo ecosystem for delivering the cloud-based Global Fish Tracking System 

Daniel Wiesmann, Tina Odaka, Anne Fouilloux, Emmanuelle Autret, Mathieu Woillez, and Benjamin Ragan-Kelley

We present our approach of leveraging the Pangeo software stack for developing the Global Fish Tracking System (GFTS). The GFTS project tackles the challenge of accurately modelling fish movement in the ocean based on biologging data with a primary focus on Sea Bass. Modelling fish movements is essential to better understand migration strategies and site fidelity, which are critical aspects for fish stock management policy and marine life conservation efforts.

Estimating fish movements is a highly compute intensive process. It involves matching pressure and temperature data from in-situ biologging sensors with high resolution ocean temperature simulations over long time periods. The Pangeo software stack provides an ideal environment for this kind of modelling. While the primary target platform of the GFTS project is the new Destination Earth Service Platform (DESP), relying on the Pangeo ecosystem ensures that the GFTS project is a robust and portable solution that can be re-deployed on different infrastructure. 

One of the distinctive features of the GFTS project is its advanced data management approach, synergizing with the capabilities of Pangeo. Diverse datasets, including climate change adaptation digital twin data, sea temperature observations, bathymetry, and biologging in-situ data from tagged fish, are seamlessly integrated within the Pangeo environment. A dedicated software called pangeo-fish has been developed to streamline this complex modelling process. The technical framework of the GFTS project includes Pangeo core packages such as Xarray and Dask, which facilitate scalable computations.

Pangeo's added value in data management becomes apparent in its capability to optimise data access and enhance performance. The concept of "data visitation" is central to this approach. By strategically deploying Dask clusters close to the data sources, the GFTS project aims to significantly improve performance of fish track modelling when compared to traditional approaches. This optimised data access ensures that end-users can efficiently interact with large datasets, leading to more streamlined and efficient analyses.

The cloud-based delivery of the GFTS project aligns with the overarching goal of Pangeo. In addition, the GFTS includes the development of a custom interactive Decision Support Tool (DST). The DST empowers non-technical users with an intuitive interface for better understanding the results of the GFTS project, leading to more informed decision-making. The integration with Pangeo and providing intuitive access to the GFTS data is not merely a technicality; it is a commitment to FAIR (Findable, Accessible, Interoperable and Reusable), TRUST (Transparency, Responsibility, User focus, Sustainability and Technology) and open science principles. 

In short, the GFTS project, within the Pangeo ecosystem, exemplifies how advanced data management, coupled with the optimization of data access through "data visitation," can significantly enhance the performance and usability of geoscience tools. This collaborative and innovative approach not only benefits the immediate goals of the GFTS project but contributes to the evolving landscape of community-driven geoscience initiatives.

How to cite: Wiesmann, D., Odaka, T., Fouilloux, A., Autret, E., Woillez, M., and Ragan-Kelley, B.: Harnessing the Pangeo ecosystem for delivering the cloud-based Global Fish Tracking System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10741, https://doi.org/10.5194/egusphere-egu24-10741, 2024.

EGU24-12410 | Orals | ESSI2.9

Towards Enhancing WaaS and Data Provenance over Reana 

Iraklis Klampanos, Antonis Ganios, and Antonis Troumpoukis

Interoperability and reproducibility are critical aspects of scientific computation. The data analysis platform Reana [1], developed by CERN, enhances the interoperability and reproducibility of scientific analyses by allowing researchers to describe, execute, and share their analyses. This is achieved via the execution of standardised scientific workflows, such as CWL, within reusable containers. Moreover, it allows execution to span different types of resources, such as Cloud and HPC. 

In this session we will present ongoing work to enhance Reana’s Workflows-as-a-Service (WaaS) functionality and also support Workflow registration and discoverability. Building upon the design goals and principles of the DARE platform [2], this work aims to enhance Reana by enabling users to register and discover available workflows within the system. In addition, we will present the integration of Data Provenance based on the W3C PROV-O standard [3] allowing the tracking and recording of data lineage in a systematic and dependable way across resource types. 

In summary, key aspects of this ongoing work include:

  • Workflows-as-a-Service (WaaS): Extending Reana's service-oriented mode of operation, allowing users to register, discover, access, execute, and manage workflows by name or ID, via APIs, therefore enhancing the platform's accessibility and usability.
  • Data Provenance based on W3C PROV-O: Implementing support for recording and visualising data lineage information in compliance with the W3C PROV-O standard. This ensures transparency and traceability of data processing steps, aiding in reproducibility and understanding of scientific analyses.

This work aims to broaden Reana's functionality, aligning with best practices for reproducible and transparent scientific research. We aim to make use of the enhanced Reana-based system on the European AI-on-demand platform [4], currently under development, to address the requirements of AI innovators and researchers when studying and executing large-scale AI-infused workflows.

References: 

[1] Simko et al., (2019). Reana: A system for reusable research data analyses. EPJ Web Conf., 214:06034, https://doi.org/10.1051/epjconf/201921406034

[2] Klampanos et al., (2020). DARE Platform: a Developer-Friendly and Self-Optimising Workflows-as-a-Service Framework for e-Science on the Cloud. Journal of Open Source Software, 5(54), 2664, https://doi.org/10.21105/joss.02664

[3] PROV-O: The PROV Ontology: https://www.w3.org/TR/prov-o/ (viewed 9 Jan 2024)

[4] The European AI-on-Demand platform: https://aiod.eu (viewed 9 Jan 2024)

This work has been has received funding from the European Union’s Horizon Europe research and innovation programme under Grant Agreement No 101070000.

How to cite: Klampanos, I., Ganios, A., and Troumpoukis, A.: Towards Enhancing WaaS and Data Provenance over Reana, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12410, https://doi.org/10.5194/egusphere-egu24-12410, 2024.

EGU24-12669 | ECS | Orals | ESSI2.9

DeployAI to Deliver Interoperability of Cloud and HPC Resources for Earth Observation in the Context of the European AI-on-Demand Platform 

Antonis Troumpoukis, Iraklis Klampanos, and Vangelis Karkaletsis

The European AI-on-Demand Platform (AIoD, http://aiod.eu) is a vital resource for leveraging and boosting the European AI research landscape towards economic growth and societal advancement across Europe. Following and emphasising European values, such as openness, transparency, and trustworthiness for developing and using AI technologies, the AIoD platform aims to become the main one-stop shop for exchanging and building AI resources and applications within the European AI innovation ecosystem, whilst also adhering to European values. The primary goal of the DIGITAL-EUROPE CSA initiative DeployAI (DIGITAL-2022-CLOUD-AI-B-03, 01/2024-12/2027) is to build, deploy, and launch a fully operational AIoD platform, promoting trustworthy, ethical, and transparent European AI solutions for the industry, with a focus on SMEs and the public sector.

Building on Open-source and trusted software, DeployAI will provide a number of technological assets such as a comprehensive and Trustworthy AI resource catalogue and marketplace offering responsible AI resources and tools, workflow composition and execution systems for prototyping and user-friendly creation of novel services, responsible foundational models and services to foster dependable innovation, etc. In addition, and building upon the results of the ICT-49 AI4Copernicus project [1], which provided a bridge between the AIoD platform and the Copernicus ecosystem and the DIAS platforms, DeployAI will integrate impactful Earth Observation AI services into the AIoD platform. These will include (but not limited to) satellite imagery preprocessing, land usage classification, crop type identification, super-resolution, and weather forecasting.

Furthermore, DeployAI will allow the rapid prototyping of AI applications and their deployment to a variety of Cloud/Edge/HPC infrastructures. The project will focus on establishing a cohesive interaction framework that integrates with European Data Spaces and Gaia-X initiatives, HPC systems with an emphasis on the EuroHPC context, and the European Open Science Cloud. Interfaces to European initiatives and industrial AI-capable cloud platforms will be further implemented to enable interoperability. This capability enables the execution of Earth Observation applications not only within the context of a DIAS/DAS but also within several other compute systems. This level of interoperability enhances the adaptability and accessibility of AI applications, fostering a collaborative environment where geoscientific workflows can be seamlessly executed across diverse computational infrastructures and made available to a wide audience of innovators.

[1] A. Troumpoukis et al., "Bridging the European Earth-Observation and AI Communities for Data-Intensive Innovation", 2023 IEEE Ninth International Conference on Big Data Computing Service and Applications (BigDataService), Athens, Greece, 2023, pp. 9-16, doi:10.1109/BigDataService58306.2023.00008.

This work has been has received funding from the European Union’s Digital Europe Programme (DIGITAL) under grant agreement No 101146490.

How to cite: Troumpoukis, A., Klampanos, I., and Karkaletsis, V.: DeployAI to Deliver Interoperability of Cloud and HPC Resources for Earth Observation in the Context of the European AI-on-Demand Platform, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12669, https://doi.org/10.5194/egusphere-egu24-12669, 2024.

EGU24-15366 | ECS | Posters on site | ESSI2.9

Enabling seamless integration of Copernicus and in-situ data 

Iason Sotiropoulos, Athos Papanikolaou, Odysseas Sekkas, Anastasios Polydoros, Vassileios Tsetsos, Claudio Pisa, and Stamatia Rizou

BUILDSPACE aims to combine terrestrial data from buildings collected by IoT devices with aerial imaging from drones equipped with thermal cameras and location annotated data from satellite services (i.e., EGNSS and Copernicus) to deliver innovative services at building scale, enabling the generation of high fidelity multi-modal digital twins and at city scale providing decision support services for energy demand prediction, urban heat and urban flood analysis. A pivotal element and the foundational support of the BUILDSPACE ecosystem is the Core Platform and it plays a crucial role in facilitating seamless data exchange, secure and scalable data storage, and streamlined access to data from three Copernicus services, namely the Land, Atmosphere, and Climate Change.The platform's underlying technology is robust, incorporating two key components: OIDC for user authentication and group authorization over the data, and a REST API to handle various file operations. OIDC stands for OpenID Connect, a standard protocol that enables secure user authentication and allows for effective management of user groups and their access permissions. On the other hand, the platform employs a REST API for seamless handling of file-related tasks, including uploading, downloading, and sharing. This combination ensures efficient and secure data exchange within the system. Additionally, the use of an S3 compatible file system ensures secure and scalable file storage, while a separate metadata storage system enhances data organization and accessibility. Currently deployed on a Kubernetes cluster, this platform offers numerous advantages, including enhanced scalability, efficient resource management, and simplified deployment processes. The implementation of the Core Platform has led to a current focus on integrating APIs from Copernicus services into the Core Platform's API. This ongoing effort aims to enhance the platform's capabilities by seamlessly incorporating external data, enriching the overall functionality and utility of the project.

How to cite: Sotiropoulos, I., Papanikolaou, A., Sekkas, O., Polydoros, A., Tsetsos, V., Pisa, C., and Rizou, S.: Enabling seamless integration of Copernicus and in-situ data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15366, https://doi.org/10.5194/egusphere-egu24-15366, 2024.

EGU24-15416 | ECS | Orals | ESSI2.9

XDGGS: Xarray Extension for Discrete Global Grid Systems (DGGS) 

Alexander Kmoch, Benoît Bovy, Justus Magin, Ryan Abernathey, Peter Strobl, Alejandro Coca-Castro, Anne Fouilloux, Daniel Loos, and Tina Odaka

Traditional geospatial representations of the globe on a 2-dimensional plane often introduce distortions in area, distance, and angles. Discrete Global Grid Systems (DGGS) mitigate these distortions and introduce a hierarchical structure of global grids. Defined by ISO standards, DGGSs serve as spatial reference systems facilitating data cube construction, enabling integration and aggregation of multi-resolution data sources. Various tessellation schemes such as hexagons and triangles cater to different needs - equal area, optimal neighborhoods, congruent parent-child relationships, ease of use, or vector field representation in modeling flows.

The fusion of Discrete Global Grid Systems (DGGS) and Datacubes represents a promising synergy for integrated handling of planetary-scale data.

The recent Pangeo community initiative at the ESA BiDS'23 conference has led to significant advancements in supporting Discrete Global Grid Systems (DGGS) within the widely used Xarray package. This collaboration resulted in the development of the Xarray extension XDGGS (https://github.com/xarray-contrib/xdggs). The aim of xdggs is to provide a unified, high-level, and user-friendly API that simplifies working with various DGGS types and their respective backend libraries, seamlessly integrating with Xarray and the Pangeo scientific computing ecosystem. Executable notebooks demonstrating the use of the xdggs package are also developed to showcase its capabilities.

This development represents a significant step forward, though continuous efforts are necessary to broaden the accessibility of DGGS for scientific and operational applications, especially in handling gridded data such as global climate and ocean modeling, satellite imagery, raster data, and maps.

Keywords: Discrete Global Grid Systems, Xarray Extension, Geospatial Data Integration, Earth Observation, Data Cube, Scientific Collaboration

How to cite: Kmoch, A., Bovy, B., Magin, J., Abernathey, R., Strobl, P., Coca-Castro, A., Fouilloux, A., Loos, D., and Odaka, T.: XDGGS: Xarray Extension for Discrete Global Grid Systems (DGGS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15416, https://doi.org/10.5194/egusphere-egu24-15416, 2024.

EGU24-15872 | Posters on site | ESSI2.9

Deploying Pangeo on HPC: our experience with the Remote Sensing Deployment Analysis environmenT on SURF infrastructure 

Francesco Nattino, Meiert W. Grootes, Pranav Chandramouli, Ou Ku, Fakhereh Alidoost, and Yifat Dzigan

The Pangeo software stack includes powerful tools that have the potential to revolutionize the way in which research on big (geo)data is conducted. A few of the aspects that make them very attractive to researchers are the ease of use of the Jupyter web-based interface, the level of integration of the tools with the Dask distributed computing library, and the possibility to seamlessly move from local deployments to large-scale infrastructures. 

The Pangeo community and project Pythia are playing a key role in providing training resources and examples that showcase what is possible with these tools. These are essential to guide interested researchers with clear end goals but also to provide inspiration for new applications. 

However, configuring and setting up a Pangeo-like deployment is not always straightforward. Scientists whose primary focus is domain-specific often do not have the time to spend solving issues that are mostly ICT in nature. In this contribution, we share our experience in providing support to researchers in running use cases backed by deployments based on Jupyter and Dask at the SURF supercomputing center in the Netherlands, in what we call the Remote Sensing Deployment Analysis environmenT (RS-DAT) project. 

Despite the popularity of cloud-based deployments, which are justified by the enormous data availability at various public cloud providers, we discuss the role that HPC infrastructure still plays for researchers, due to the ease of access via merit-based allocation grants and the requirements of integration with pre-existing workflows. We present the solution that we have identified to seamlessly access datasets from the SURF dCache massive storage system, we stress how installation and deployment scripts can facilitate adoption and re-use, and we finally highlight how technical research-support staff such as Research Software Engineers can be key in bridging researchers and HPC centers. 

How to cite: Nattino, F., Grootes, M. W., Chandramouli, P., Ku, O., Alidoost, F., and Dzigan, Y.: Deploying Pangeo on HPC: our experience with the Remote Sensing Deployment Analysis environmenT on SURF infrastructure, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15872, https://doi.org/10.5194/egusphere-egu24-15872, 2024.

EGU24-17111 | Posters on site | ESSI2.9

Cloudifying Earth System Model Output 

Fabian Wachsmann

We introduce eerie.cloud (eerie.cloud.dkrz.de), a data server for efficient access to prominent climate data sets stored on disk at the German Climate Computing Center (DKRZ). We show how we “cloudify” data from two projects, EERIE and ERA5, and how one can benefit from it. 

The European Eddy-rich Earth System Model (EERIE) project aims to develop state-of-the-art high-resolution Earth System Models (ESM) that are able to resolve ocean mesoscale processes. These models are then used to perform simulations over centennial scales and make their output available for the global community. At present, the total volume of the EERIE data set exceeds 0.5PB  and is rapidly growing, posing challenges for data management.
ERA5 is the fifth generation ECMWF global atmospheric reanalysis. It is widely used as forcing data for climate model simulations, for model evaluation or for the analysis of climate trends. DKRZ maintains a 1.6 PB subset of ERA5 data at its native resolution.

We use Xpublish to set up the data server. Xpublish is a python package and a plugin for Pangeo's central analysis package Xarray. Its main feature is to provide ESM output by mapping any input data to virtual zarr data sets. Users can retrieve these data sets as if they were cloud-native and cloud-optimized.

eerie.cloud features

  • Parallel access to data subsets on chunk-level
  • Interfaces to make the data more FAIR
    • User friendly content overviews with displays of xarray-like dataset representations
    • Simple browsing and loading data with an intake catalog
  • On-the-fly server-side computation 
    • Register simple xarray routines for generating customized variables
    • Compression for speeding up downloads
  • Generation of interactive geographical plots, including animations

Eerie.cloud is a solution to make EERIE data more usable by a wider community.

How to cite: Wachsmann, F.: Cloudifying Earth System Model Output, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17111, https://doi.org/10.5194/egusphere-egu24-17111, 2024.

EGU24-17150 | ECS | Posters on site | ESSI2.9

Data access patterns of km-scale resolution models 

Janos Zimmermann, Florian Ziemen, and Tobias Kölling

Climate models produce vast amounts of output data. In the nextGEMS project, we have run the ICON model at 5 km resolution for 5 years, producing about 750 TB of output data from one simulation. To ease analysis, the data is stored at multiple temporal and spatial resolutions. The dataset is now analyzed by more than a hundred scientists on the DKRZ levante system. As disk space is limited, it is crucial to obtain information, which parts of this dataset are accessed frequently and need to be kept on disk, and which parts can be moved to the tape archive and only be fetched on request.

By storing the output as zarr files with many small files for the individual data chunks, and logging file access times, we obtained a detailed view of more than half a year of access to the nextGEMS dataset, even going to regional level for a given variable and time step. The evaluation of those access patterns offers the possibility to optimize various aspects such as caching, chunking, and archiving. Furthermore, it provides valuable information for designing future output configurations.

In this poster, we present the observed access patterns and discuss their implications for our chunking and archiving strategy. Leveraging an interactive visualization tool, we explore and compare access patterns, distinguishing frequently accessed subsets, sparsely accessed variables, and preferred resolutions. We furthermore provide information on how we analyzed the data access to enable other users to follow our approach.

How to cite: Zimmermann, J., Ziemen, F., and Kölling, T.: Data access patterns of km-scale resolution models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17150, https://doi.org/10.5194/egusphere-egu24-17150, 2024.

EGU24-18256 | Orals | ESSI2.9

Data access for km-scale resolution models 

Florian Ziemen, Tobias Kölling, and Lukas Kluft

With the transition to global, km-scale simulations, model outputs have grown in size, and efficient ways of accessing data have become more important than ever. This implies that the data storage has to be optimized for efficient read access to small sub-sets of the data, and multiple resolutions of the same data need to be provided for efficient analysis on coarse as well as fine-grained scales.

In this high-level overview presentation, we present an approach based on datasets. Each dataset represents a coherent subset of a model output (e.g. all model variables stored at daily resolution). Aiming for a minimum number of datasets makes us enforce consistency in the model output and thus eases analysis. Each dataset is served to the user as one zarr store, independent of the actual file layout on disks or other storage media. Multiple datasets are grouped in catalogs for findability.

By serving the data via https, we can implement a middle layer between the user and the storage systems, allowing to combine different storage backends behind a unifying frontend. At the same time, this approach allows us to largely build the system on existing technologies such as web servers and caches, and efficiently serve data to users outside the compute center where the data is stored.
The approach we present is currently under development in the BMBF project WarmWorld with contributions by the H2020 project nextGEMS, and we expect it to be useful for many other projects as well.

How to cite: Ziemen, F., Kölling, T., and Kluft, L.: Data access for km-scale resolution models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18256, https://doi.org/10.5194/egusphere-egu24-18256, 2024.

EGU24-18585 | ECS | Posters on site | ESSI2.9

STAC catalogs for time-varying in-situ data 

Justus Magin

The ability to search a collection of datasets is an important factor for the usefulness of the data. By organizing the metadata into catalogs, we can enable dataset discovery, look up file locations and avoid access to the data files before the actual computation. Spatio-Temporal Asset Catalogs (STAC) is a increasingly popular language-agnostic specification and vibrant ecosystem of tools for geospatial data catalogs, and is tailored for raster data like satellite imagery. It allows for a search using a variety of patterns, including the spatial and temporal extent.

In-situ data is heterogenous and would benefit from being cataloged, as well as the ecosystem of tools. However, due to the strict separation between the spatial and temporal dimensions in STAC the time-varying nature of in-situ data is not optimally captured. While for approximately stationary sensors like tide gauges, moorings, weather stations, and high-frequency radars this is not an issue (see https://doi.org/10.5194/egusphere-egu23-8096), it becomes troublesome for moving sensors, especially if the sensor moves at a high speed, covers big distances, or if the dataset contains a long time series.

To resolve this, we extend the STAC specification by replacing the geojson data with the JSON-encoded ODC moving feature standard.

How to cite: Magin, J.: STAC catalogs for time-varying in-situ data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18585, https://doi.org/10.5194/egusphere-egu24-18585, 2024.

EGU24-20779 | Orals | ESSI2.9

Project Pythia: Building an Inclusive Geoscience Community with Cookbooks 

John Clyne, Brian Rose, Orhan Eroglu, James Munroe, Ryan May, Drew Camron, Julia Kent, Amelia Snyder, Kevin Tyle, Maxwell Grover, and Robert Ford

Project Pythia is the educational arm of the Pangeo community, and provides a growing collection of community driven and developed training resources that help geoscientists navigate the Pangeo ecosystem, and the myriad complex technologies essential for today’s Big Data science challenges. Project Pythia began in 2020 with the support of a U.S. NSF EarthCube award. Much of the initial effort focused on Pythia Foundations: a collection of Jupyter Notebooks that covered essential topics such as Python language basics; managing projects with GitHub; authoring and using “binderized” Jupyter Notebooks; and many of Pangeo’s core packages such as Xarray, Pandas, and Matplotlib. Building upon Foundations, the Pythia community turned its attention toward creating Pythia Cookbooks: exemplar collections of recipes for transforming raw ingredients (publicly available, cloud-hosted data) into scientifically useful results. Built from Jupyter Notebooks, Cookbooks are explicitly tied to reproducible computational environments and supported by a rich infrastructure enabling collaborative authoring and automated health-checking – essential tools in the struggle against the widespread notebook obsolescence problem.

 

Open-access, cloud-based Cookbooks are a democratizing force for growing the capacity of current and future geoscientists to practice open science within the rapidly evolving open science ecosystem. In this talk we outline our vision of a sustainable, inclusive open geoscience community enabled by Cookbooks. With further support from the NSF, the Pythia community will accelerate the development and broad buy-in of these resources, demonstrating highly scalable versions of common analysis workflows on high-value datasets across the geosciences. Infrastructure will be deployed for performant data-proximate Cookbook authoring, testing, and use, on both commercial and public cloud platforms. Content and community will expand through annual workshops, outreach, and classroom use, with recruitment targeting under-served communities. Priorities will be guided by an independent steering board; sustainability will be achieved by nurturing a vibrant, inclusive community backed by automation that lowers barriers to participation.

How to cite: Clyne, J., Rose, B., Eroglu, O., Munroe, J., May, R., Camron, D., Kent, J., Snyder, A., Tyle, K., Grover, M., and Ford, R.: Project Pythia: Building an Inclusive Geoscience Community with Cookbooks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20779, https://doi.org/10.5194/egusphere-egu24-20779, 2024.

EGU24-20909 | ECS | Orals | ESSI2.9

UXarray: Extensions to Xarray to support unstructured grids 

Orhan Eroglu, Hongyu Chen, Philip Chmielowiec, John Clyne, Corrine DeCiampa, Cecile Hannay, Robert Jacob, Rajeev Jain, Richard Loft, Brian Medeiros, Lantao Sun, Paul Ullrich, and Colin Zarzycki

The arrival of kilometer-scale climate and global weather models presents substantial challenges for the analysis and visualization of the resulting data, not only because of their tremendous size but also because of the employment of unstructured grids upon which the governing equations of state are solved. Few Open Source analysis and visualization software tools exist that are capable of operating directly on unstructured grid data. Those that do exist are not comprehensive in the capabilities they offer, do not scale adequately, or both. Recognizing this gap in much-needed capability, Project Raijin - funded by an NSF EarthCube award - and the DOE SEATS project, launched a collaborative effort to develop an open source Python package called UXarray. 

UXarray extends the widely used Xarray package, providing support for operating directly (without regridding) on unstructured grid model outputs found in the Earth System Sciences, such as CAM-SE, MPAS, SCRIP, UGRID, and in the future, ICON. Much like Xarray, UXarray provides fundamental analysis and visualization operators, upon which more specialized, domain-specific capabilities can be layered. This talk will present an overview of the current capabilities of UXarray, provide a roadmap for near term future development, and will describe how the Pangeo community can contribute to this on-going effort.

How to cite: Eroglu, O., Chen, H., Chmielowiec, P., Clyne, J., DeCiampa, C., Hannay, C., Jacob, R., Jain, R., Loft, R., Medeiros, B., Sun, L., Ullrich, P., and Zarzycki, C.: UXarray: Extensions to Xarray to support unstructured grids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20909, https://doi.org/10.5194/egusphere-egu24-20909, 2024.

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